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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.
a9913044 38 DRM Direct Rendering Management support is enabled.
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39 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LP Printer support is enabled.
52 LOOP Loopback device support is enabled.
53 M68k M68k architecture is enabled.
54 These options have more detailed description inside of
55 Documentation/m68k/kernel-options.txt.
56 MCA MCA bus support is enabled.
57 MDA MDA console support is enabled.
58 MOUSE Appropriate mouse support is enabled.
309e57df 59 MSI Message Signaled Interrupts (PCI).
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60 MTD MTD support is enabled.
61 NET Appropriate network support is enabled.
62 NUMA NUMA support is enabled.
734efb46 63 GENERIC_TIME The generic timeofday code is enabled.
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64 NFS Appropriate NFS support is enabled.
65 OSS OSS sound support is enabled.
66 PARIDE The ParIDE subsystem is enabled.
67 PARISC The PA-RISC architecture is enabled.
68 PCI PCI bus support is enabled.
69 PCMCIA The PCMCIA subsystem is enabled.
70 PNP Plug & Play support is enabled.
71 PPC PowerPC architecture is enabled.
72 PPT Parallel port support is enabled.
73 PS2 Appropriate PS/2 support is enabled.
74 RAM RAM disk support is enabled.
75 S390 S390 architecture is enabled.
76 SCSI Appropriate SCSI support is enabled.
77 A lot of drivers has their options described inside of
78 Documentation/scsi/.
79 SELINUX SELinux support is enabled.
80 SERIAL Serial support is enabled.
81 SMP The kernel is an SMP kernel.
82 SPARC Sparc architecture is enabled.
a9913044 83 SWSUSP Software suspend is enabled.
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84 TS Appropriate touchscreen support is enabled.
85 USB USB support is enabled.
86 USBHID USB Human Interface Device support is enabled.
87 V4L Video For Linux support is enabled.
88 VGA The VGA console has been enabled.
89 VT Virtual terminal support is enabled.
90 WDT Watchdog support is enabled.
91 XT IBM PC/XT MFM hard disk support is enabled.
92 X86-64 X86-64 architecture is enabled.
93 More X86-64 boot options can be found in
94 Documentation/x86_64/boot-options.txt .
95
96In addition, the following text indicates that the option:
97
98 BUGS= Relates to possible processor bugs on the said processor.
99 KNL Is a kernel start-up parameter.
100 BOOT Is a boot loader parameter.
101
102Parameters denoted with BOOT are actually interpreted by the boot
103loader, and have no meaning to the kernel directly.
104Do not modify the syntax of boot loader parameters without extreme
105need or coordination with <Documentation/i386/boot.txt>.
106
107Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
108a trailing = on the name of any parameter states that that parameter will
109be entered as an environment variable, whereas its absence indicates that
110it will appear as a kernel argument readable via /proc/cmdline by programs
111running once the system is up.
112
113 53c7xx= [HW,SCSI] Amiga SCSI controllers
114 See header of drivers/scsi/53c7xx.c.
115 See also Documentation/scsi/ncr53c7xx.txt.
116
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117 acpi= [HW,ACPI] Advanced Configuration and Power Interface
118 Format: { force | off | ht | strict | noirq }
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119 force -- enable ACPI if default was off
120 off -- disable ACPI if default was on
121 noirq -- do not use ACPI for IRQ routing
122 ht -- run only enough ACPI to enable Hyper Threading
a9913044 123 strict -- Be less tolerant of platforms that are not
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124 strictly ACPI specification compliant.
125
126 See also Documentation/pm.txt, pci=noacpi
127
128 acpi_sleep= [HW,ACPI] Sleep options
129 Format: { s3_bios, s3_mode }
130 See Documentation/power/video.txt
a9913044 131
1da177e4 132 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 133 Format: { level | edge | high | low }
1da177e4 134
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135 acpi_irq_balance [HW,ACPI]
136 ACPI will balance active IRQs
137 default in APIC mode
1da177e4 138
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139 acpi_irq_nobalance [HW,ACPI]
140 ACPI will not move active IRQs (default)
141 default in PIC mode
1da177e4 142
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143 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
144 use by PCI
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145 Format: <irq>,<irq>...
146
a9913044 147 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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148 Format: <irq>,<irq>...
149
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150 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
151 Format: To spoof as Windows 98: ="Microsoft Windows"
152
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153 acpi_osi= [HW,ACPI] empty param disables _OSI
154
155 acpi_serialize [HW,ACPI] force serialization of AML methods
156
157 acpi_skip_timer_override [HW,ACPI]
158 Recognize and ignore IRQ0/pin2 Interrupt Override.
159 For broken nForce2 BIOS resulting in XT-PIC timer.
160
161 acpi_dbg_layer= [HW,ACPI]
162 Format: <int>
a9913044 163 Each bit of the <int> indicates an ACPI debug layer,
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164 1: enable, 0: disable. It is useful for boot time
165 debugging. After system has booted up, it can be set
166 via /proc/acpi/debug_layer.
167
168 acpi_dbg_level= [HW,ACPI]
169 Format: <int>
a9913044 170 Each bit of the <int> indicates an ACPI debug level,
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171 1: enable, 0: disable. It is useful for boot time
172 debugging. After system has booted up, it can be set
173 via /proc/acpi/debug_level.
174
175 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
176
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177 acpi_generic_hotkey [HW,ACPI]
178 Allow consolidated generic hotkey driver to
a9913044 179 override platform specific driver.
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180 See also Documentation/acpi-hotkey.txt.
181
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182 acpi_pm_good [IA-32,X86-64]
183 Override the pmtimer bug detection: force the kernel
184 to assume that this machine's pmtimer latches its value
185 and always returns good values.
186
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187 enable_timer_pin_1 [i386,x86-64]
188 Enable PIN 1 of APIC timer
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189 Can be useful to work around chipset bugs
190 (in particular on some ATI chipsets).
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191 The kernel tries to set a reasonable default.
192
193 disable_timer_pin_1 [i386,x86-64]
194 Disable PIN 1 of APIC timer
195 Can be useful to work around chipset bugs.
196
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197 ad1816= [HW,OSS]
198 Format: <io>,<irq>,<dma>,<dma2>
199 See also Documentation/sound/oss/AD1816.
200
201 ad1848= [HW,OSS]
202 Format: <io>,<irq>,<dma>,<dma2>,<type>
203
204 adlib= [HW,OSS]
205 Format: <io>
a9913044 206
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207 advansys= [HW,SCSI]
208 See header of drivers/scsi/advansys.c.
209
210 advwdt= [HW,WDT] Advantech WDT
211 Format: <iostart>,<iostop>
212
213 aedsp16= [HW,OSS] Audio Excel DSP 16
214 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
215 See also header of sound/oss/aedsp16.c.
a9913044 216
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217 aha152x= [HW,SCSI]
218 See Documentation/scsi/aha152x.txt.
219
220 aha1542= [HW,SCSI]
221 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
222
223 aic7xxx= [HW,SCSI]
224 See Documentation/scsi/aic7xxx.txt.
225
226 aic79xx= [HW,SCSI]
227 See Documentation/scsi/aic79xx.txt.
228
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229 amijoy.map= [HW,JOY] Amiga joystick support
230 Map of devices attached to JOY0DAT and JOY1DAT
231 Format: <a>,<b>
232 See also Documentation/kernel/input/joystick.txt
233
234 analog.map= [HW,JOY] Analog joystick and gamepad support
235 Specifies type or capabilities of an analog joystick
236 connected to one of 16 gameports
237 Format: <type1>,<type2>,..<type16>
238
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239 apc= [HW,SPARC]
240 Power management functions (SPARCstation-4/5 + deriv.)
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241 Format: noidle
242 Disable APC CPU standby support. SPARCstation-Fox does
243 not play well with APC CPU idle - disable it if you have
244 APC and your system crashes randomly.
245
a9913044 246 apic= [APIC,i386] Change the output verbosity whilst booting
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247 Format: { quiet (default) | verbose | debug }
248 Change the amount of debugging information output
249 when initialising the APIC and IO-APIC components.
a9913044 250
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251 apm= [APM] Advanced Power Management
252 See header of arch/i386/kernel/apm.c.
253
254 applicom= [HW]
255 Format: <mem>,<irq>
a9913044 256
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257 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
258 Format: <io>,<irq>,<nodeID>
259
260 ataflop= [HW,M68k]
261
262 atarimouse= [HW,MOUSE] Atari Mouse
263
264 atascsi= [HW,SCSI] Atari SCSI
265
266 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
267 EzKey and similar keyboards
268
269 atkbd.reset= [HW] Reset keyboard during initialization
270
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271 atkbd.set= [HW] Select keyboard code set
272 Format: <int> (2 = AT (default), 3 = PS/2)
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273
274 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
275 keyboards
276
277 atkbd.softraw= [HW] Choose between synthetic and real raw mode
278 Format: <bool> (0 = real, 1 = synthetic (default))
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279
280 atkbd.softrepeat= [HW]
281 Use software keyboard repeat
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282
283 autotest [IA64]
284
285 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
286 Format: <io>,<memsize>,<isapnp>
a9913044 287
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288 aztcd= [HW,CD] Aztech CD268 CDROM driver
289 Format: <io>,0x79 (?)
290
291 baycom_epp= [HW,AX25]
292 Format: <io>,<mode>
a9913044 293
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294 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
295 Format: <io>,<mode>
296 See header of drivers/net/hamradio/baycom_par.c.
297
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298 baycom_ser_fdx= [HW,AX25]
299 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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300 Format: <io>,<irq>,<mode>[,<baud>]
301 See header of drivers/net/hamradio/baycom_ser_fdx.c.
302
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303 baycom_ser_hdx= [HW,AX25]
304 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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305 Format: <io>,<irq>,<mode>
306 See header of drivers/net/hamradio/baycom_ser_hdx.c.
307
308 blkmtd_device= [HW,MTD]
309 blkmtd_erasesz=
310 blkmtd_ro=
311 blkmtd_bs=
312 blkmtd_count=
313
314 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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315 bttv.radio= Most important insmod options are available as
316 kernel args too.
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317 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
318 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
319
320 BusLogic= [HW,SCSI]
321 See drivers/scsi/BusLogic.c, comment before function
322 BusLogic_ParseDriverOptions().
323
324 c101= [NET] Moxa C101 synchronous serial card
325
326 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
327 Sometimes CPU hardware bugs make them report the cache
328 size incorrectly. The kernel will attempt work arounds
329 to fix known problems, but for some CPUs it is not
330 possible to determine what the correct size should be.
331 This option provides an override for these situations.
332
333 cdu31a= [HW,CD]
334 Format: <io>,<irq>[,PAS]
335 See header of drivers/cdrom/cdu31a.c.
336
337 chandev= [HW,NET] Generic channel device initialisation
338
339 checkreqprot [SELINUX] Set initial checkreqprot flag value.
340 Format: { "0" | "1" }
341 See security/selinux/Kconfig help text.
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342 0 -- check protection applied by kernel (includes
343 any implied execute protection).
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344 1 -- check protection requested by application.
345 Default value is set via a kernel config option.
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346 Value can be changed at runtime via
347 /selinux/checkreqprot.
348
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349 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
350 [Deprecated]
351 Forces specified clocksource (if avaliable) to be used
352 when calculating gettimeofday(). If specified
353 clocksource is not avalible, it defaults to PIT.
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354 Format: { pit | tsc | cyclone | pmtmr }
355
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356 disable_8254_timer
357 enable_8254_timer
358 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
359 over the 8254 in addition to over the IO-APIC. The
360 kernel tries to set a sensible default.
361
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362 hpet= [IA-32,HPET] option to disable HPET and use PIT.
363 Format: disable
364
365 cm206= [HW,CD]
366 Format: { auto | [<io>,][<irq>] }
367
368 com20020= [HW,NET] ARCnet - COM20020 chipset
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369 Format:
370 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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371
372 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
373 Format: <io>[,<irq>]
374
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375 com90xx= [HW,NET]
376 ARCnet - COM90xx chipset (memory-mapped buffers)
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377 Format: <io>[,<irq>[,<memstart>]]
378
379 condev= [HW,S390] console device
380 conmode=
a9913044 381
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382 console= [KNL] Output console device and options.
383
384 tty<n> Use the virtual console device <n>.
385
386 ttyS<n>[,options]
f1a1c2dc 387 ttyUSB0[,options]
1da177e4 388 Use the specified serial port. The options are of
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389 the form "bbbbpnf", where "bbbb" is the baud rate,
390 "p" is parity ("n", "o", or "e"), "n" is number of
391 bits, and "f" is flow control ("r" for RTS or
392 omit it). Default is "9600n8".
393
394 See Documentation/serial-console.txt for more
395 information. See
396 Documentation/networking/netconsole.txt for an
397 alternative.
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398
399 uart,io,<addr>[,options]
400 uart,mmio,<addr>[,options]
401 Start an early, polled-mode console on the 8250/16550
402 UART at the specified I/O port or MMIO address,
403 switching to the matching ttyS device later. The
404 options are the same as for ttyS, above.
405
406 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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407 Format:
408 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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409
410 cpia_pp= [HW,PPT]
411 Format: { parport<nr> | auto | none }
412
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413 crashkernel=nn[KMG]@ss[KMG]
414 [KNL] Reserve a chunk of physical memory to
415 hold a kernel to switch to with kexec on panic.
416
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417 cs4232= [HW,OSS]
418 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
419
420 cs89x0_dma= [HW,NET]
421 Format: <dma>
422
423 cs89x0_media= [HW,NET]
424 Format: { rj45 | aui | bnc }
a9913044 425
1da177e4 426 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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427
428 dasd= [HW,NET]
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429 See header of drivers/s390/block/dasd_devmap.c.
430
431 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
432 (one device per port)
433 Format: <port#>,<type>
434 See also Documentation/input/joystick-parport.txt
435
436 debug [KNL] Enable kernel debugging (events log level).
437
438 decnet= [HW,NET]
439 Format: <area>[,<node>]
440 See also Documentation/networking/decnet.txt.
441
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442 dhash_entries= [KNL]
443 Set number of hash buckets for dentry cache.
a9913044 444
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445 digi= [HW,SERIAL]
446 IO parameters + enable/disable command.
447
448 digiepca= [HW,SERIAL]
449 See drivers/char/README.epca and
450 Documentation/digiepca.txt.
451
452 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
453 support available.
454 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
455
456 dmasound= [HW,OSS] Sound subsystem buffers
457
458 dscc4.setup= [NET]
459
460 dtc3181e= [HW,SCSI]
461
a9913044 462 earlyprintk= [IA-32,X86-64]
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463 earlyprintk=vga
464 earlyprintk=serial[,ttySn[,baudrate]]
465
a9913044 466 Append ",keep" to not disable it when the real console
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467 takes over.
468
469 Only vga or serial at a time, not both.
470
471 Currently only ttyS0 and ttyS1 are supported.
472
473 Interaction with the standard serial driver is not
474 very good.
475
476 The VGA output is eventually overwritten by the real
477 console.
478
479 eata= [HW,SCSI]
480
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481 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
482 Format: <int>
483 0: polling mode
484 non-0: interrupt mode (default)
485
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486 eda= [HW,PS2]
487
488 edb= [HW,PS2]
489
490 edd= [EDD]
491 Format: {"of[f]" | "sk[ipmbr]"}
492 See comment in arch/i386/boot/edd.S
493
a9913044 494 eicon= [HW,ISDN]
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495 Format: <id>,<membase>,<irq>
496
497 eisa_irq_edge= [PARISC,HW]
498 See header of drivers/parisc/eisa.c.
499
500 elanfreq= [IA-32]
501 See comment before function elanfreq_setup() in
502 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
503
504 elevator= [IOSCHED]
16ab3adf 505 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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506 See Documentation/block/as-iosched.txt and
507 Documentation/block/deadline-iosched.txt for details.
508
aac04b32 509 elfcorehdr= [IA-32, X86_64]
a9913044 510 Specifies physical address of start of kernel core
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511 image elf header. Generally kexec loader will
512 pass this option to capture kernel.
513 See Documentation/kdump/kdump.txt for details.
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514
515 enforcing [SELINUX] Set initial enforcing status.
516 Format: {"0" | "1"}
517 See security/selinux/Kconfig help text.
518 0 -- permissive (log only, no denials).
519 1 -- enforcing (deny and log).
520 Default value is 0.
521 Value can be changed at runtime via /selinux/enforce.
522
523 es1370= [HW,OSS]
524 Format: <lineout>[,<micbias>]
525 See also header of sound/oss/es1370.c.
526
527 es1371= [HW,OSS]
528 Format: <spdif>,[<nomix>,[<amplifier>]]
529 See also header of sound/oss/es1371.c.
a9913044 530
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531 ether= [HW,NET] Ethernet cards parameters
532 This option is obsoleted by the "netdev=" option, which
533 has equivalent usage. See its documentation for details.
534
535 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
536 Format: <io>[,<irq>]
537
538 fd_mcs= [HW,SCSI]
539 See header of drivers/scsi/fd_mcs.c.
540
541 fdomain= [HW,SCSI]
542 See header of drivers/scsi/fdomain.c.
543
544 floppy= [HW]
545 See Documentation/floppy.txt.
546
547 ftape= [HW] Floppy Tape subsystem debugging options.
548 See Documentation/ftape.txt.
549
550 gamecon.map[2|3]=
551 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
552 support via parallel port (up to 5 devices per port)
553 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
554 See also Documentation/input/joystick-parport.txt
555
556 gamma= [HW,DRM]
557
558 gdth= [HW,SCSI]
559 See header of drivers/scsi/gdth.c.
560
561 gpt [EFI] Forces disk with valid GPT signature but
562 invalid Protective MBR to be treated as GPT.
563
564 gscd= [HW,CD]
565 Format: <io>
566
567 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
568
569 gus= [HW,OSS]
570 Format: <io>,<irq>,<dma>,<dma16>
a9913044 571
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572 gvp11= [HW,SCSI]
573
574 hashdist= [KNL,NUMA] Large hashes allocated during boot
575 are distributed across NUMA nodes. Defaults on
576 for IA-64, off otherwise.
a9913044 577 Format: 0 | 1 (for off | on)
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578
579 hcl= [IA-64] SGI's Hardware Graph compatibility layer
580
581 hd= [EIDE] (E)IDE hard drive subsystem geometry
582 Format: <cyl>,<head>,<sect>
583
584 hd?= [HW] (E)IDE subsystem
585 hd?lun= See Documentation/ide.txt.
586
587 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
588 size of <nn>. This works even on boxes that have no
589 highmem otherwise. This also works to reduce highmem
590 size on bigger boxes.
591
592 hisax= [HW,ISDN]
593 See Documentation/isdn/README.HiSax.
594
595 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
596
597 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
598
599 i8042.direct [HW] Put keyboard port into non-translated mode
600 i8042.dumbkbd [HW] Pretend that controlled can only read data from
601 keyboard and can not control its state
602 (Don't attempt to blink the leds)
603 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 604 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
605 i8042.nomux [HW] Don't check presence of an active multiplexing
606 controller
607 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
608 controllers
609 i8042.panicblink=
610 [HW] Frequency with which keyboard LEDs should blink
611 when kernel panics (default is 0.5 sec)
612 i8042.reset [HW] Reset the controller during init and cleanup
613 i8042.unlock [HW] Unlock (ignore) the keylock
614
615 i810= [HW,DRM]
616
e70c9d5e
DT
617 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
618 indicates that the driver is running on unsupported
619 hardware.
1da177e4
LT
620 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
621 does not match list of supported models.
622 i8k.power_status
623 [HW] Report power status in /proc/i8k
624 (disabled by default)
625 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
626 capability is set.
627
628 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
629 See Documentation/mca.txt.
630
631 icn= [HW,ISDN]
632 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
633
634 ide= [HW] (E)IDE subsystem
635 Format: ide=nodma or ide=doubler or ide=reverse
636 See Documentation/ide.txt.
637
638 ide?= [HW] (E)IDE subsystem
639 Format: ide?=noprobe or chipset specific parameters.
640 See Documentation/ide.txt.
a9913044 641
1da177e4
LT
642 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
643 See Documentation/ide.txt.
644
645 idle= [HW]
646 Format: idle=poll or idle=halt
a9913044 647
1da177e4
LT
648 ihash_entries= [KNL]
649 Set number of hash buckets for inode cache.
650
651 in2000= [HW,SCSI]
652 See header of drivers/scsi/in2000.c.
653
654 init= [KNL]
655 Format: <full_path>
656 Run specified binary instead of /sbin/init as init
657 process.
658
659 initcall_debug [KNL] Trace initcalls as they are executed. Useful
660 for working out where the kernel is dying during
661 startup.
662
663 initrd= [BOOT] Specify the location of the initial ramdisk
664
665 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
666 Format: <irq>
667
2bd0fa3b
JB
668 combined_mode= [HW] control which driver uses IDE ports in combined
669 mode: legacy IDE driver, libata, or both
670 (in the libata case, libata.atapi_enabled=1 may be
671 useful as well). Note that using the ide or libata
672 options may affect your device naming (e.g. by
673 changing hdc to sdb).
674 Format: combined (default), ide, or libata
675
1da177e4
LT
676 inttest= [IA64]
677
678 io7= [HW] IO7 for Marvel based alpha systems
679 See comment before marvel_specify_io7 in
680 arch/alpha/kernel/core_marvel.c.
681
682 ip= [IP_PNP]
683 See Documentation/nfsroot.txt.
684
685 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
686 See comment before ip2_setup() in drivers/char/ip2.c.
687
688 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
689 See header of drivers/scsi/ips.c.
690
200803df
AC
691 irqfixup [HW]
692 When an interrupt is not handled search all handlers
693 for it. Intended to get systems with badly broken
694 firmware running.
695
696 irqpoll [HW]
697 When an interrupt is not handled search all handlers
698 for it. Also check all handlers each timer
699 interrupt. Intended to get systems with badly broken
700 firmware running.
701
1da177e4 702 isapnp= [ISAPNP]
a9913044 703 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
704
705 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
706 Format: <cpu number>,...,<cpu number>
707 This option can be used to specify one or more CPUs
708 to isolate from the general SMP balancing and scheduling
709 algorithms. The only way to move a process onto or off
710 an "isolated" CPU is via the CPU affinity syscalls.
711 <cpu number> begins at 0 and the maximum value is
712 "number of CPUs in system - 1".
713
714 This option is the preferred way to isolate CPUs. The
a9913044
RD
715 alternative -- manually setting the CPU mask of all
716 tasks in the system -- can cause problems and
717 suboptimal load balancer performance.
1da177e4
LT
718
719 isp16= [HW,CD]
720 Format: <io>,<irq>,<dma>,<setup>
721
a9913044 722 iucv= [HW,NET]
1da177e4
LT
723
724 js= [HW,JOY] Analog joystick
725 See Documentation/input/joystick.txt.
726
727 keepinitrd [HW,ARM]
728
a9913044 729 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
730 in oops dumps.
731
732 l2cr= [PPC]
733
a9913044
RD
734 lapic [IA-32,APIC] Enable the local APIC even if BIOS
735 disabled it.
1da177e4
LT
736
737 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
738 Format: addr:<io>,irq:<irq>
739
a9913044
RD
740 llsc*= [IA64] See function print_params() in
741 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
742
743 load_ramdisk= [RAM] List of ramdisks to load from floppy
744 See Documentation/ramdisk.txt.
745
a6b25b67
RD
746 lockd.nlm_grace_period=P [NFS] Assign grace period.
747 Format: <integer>
1da177e4 748
a6b25b67
RD
749 lockd.nlm_tcpport=N [NFS] Assign TCP port.
750 Format: <integer>
751
752 lockd.nlm_timeout=T [NFS] Assign timeout value.
753 Format: <integer>
754
755 lockd.nlm_udpport=M [NFS] Assign UDP port.
756 Format: <integer>
1da177e4
LT
757
758 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
759 Format: <irq>
760
761 loglevel= All Kernel Messages with a loglevel smaller than the
762 console loglevel will be printed to the console. It can
763 also be changed with klogd or other programs. The
764 loglevels are defined as follows:
765
766 0 (KERN_EMERG) system is unusable
767 1 (KERN_ALERT) action must be taken immediately
768 2 (KERN_CRIT) critical conditions
769 3 (KERN_ERR) error conditions
770 4 (KERN_WARNING) warning conditions
771 5 (KERN_NOTICE) normal but significant condition
772 6 (KERN_INFO) informational
773 7 (KERN_DEBUG) debug-level messages
774
775 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
776 Format: { n | nk | nM }
777 n must be a power of two. The default size
778 is set in the kernel config file.
1da177e4
LT
779
780 lp=0 [LP] Specify parallel ports to use, e.g,
781 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
782 lp=reset first parallel port). 'lp=0' disables the
783 lp=auto printer driver. 'lp=reset' (which can be
784 specified in addition to the ports) causes
785 attached printers to be reset. Using
786 lp=port1,port2,... specifies the parallel ports
787 to associate lp devices with, starting with
788 lp0. A port specification may be 'none' to skip
789 that lp device, or a parport name such as
790 'parport0'. Specifying 'lp=auto' instead of a
791 port specification list means that device IDs
792 from each port should be examined, to see if
793 an IEEE 1284-compliant printer is attached; if
794 so, the driver will manage that printer.
795 See also header of drivers/char/lp.c.
796
797 lpj=n [KNL]
798 Sets loops_per_jiffy to given constant, thus avoiding
799 time-consuming boot-time autodetection (up to 250 ms per
800 CPU). 0 enables autodetection (default). To determine
801 the correct value for your kernel, boot with normal
802 autodetection and see what value is printed. Note that
803 on SMP systems the preset will be applied to all CPUs,
804 which is likely to cause problems if your CPUs need
805 significantly divergent settings. An incorrect value
806 will cause delays in the kernel to be wrong, leading to
807 unpredictable I/O errors and other breakage. Although
808 unlikely, in the extreme case this might damage your
809 hardware.
810
811 ltpc= [NET]
812 Format: <io>,<irq>,<dma>
813
a9913044
RD
814 mac5380= [HW,SCSI] Format:
815 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 816
a9913044
RD
817 mac53c9x= [HW,SCSI] Format:
818 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 819
a9913044
RD
820 machvec= [IA64] Force the use of a particular machine-vector
821 (machvec) in a generic kernel.
822 Example: machvec=hpzx1_swiotlb
1da177e4 823
a9913044
RD
824 mad16= [HW,OSS] Format:
825 <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
1da177e4
LT
826
827 maui= [HW,OSS]
828 Format: <io>,<irq>
a9913044
RD
829
830 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
831 be mounted
832 Format: <1-256>
833
834 maxcpus= [SMP] Maximum number of processors that an SMP kernel
835 should make use of
836
2b2c3750
BP
837 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
838 equal to this physical address is ignored.
839
a9913044 840 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
841 Should be between 1 and 2^32-1.
842
843 max_report_luns=
a9913044 844 [SCSI] Maximum number of LUNs received.
1da177e4
LT
845 Should be between 1 and 16384.
846
847 mca-pentium [BUGS=IA-32]
848
849 mcatest= [IA-64]
850
851 mcd= [HW,CD]
852 Format: <port>,<irq>,<mitsumi_bug_93_wait>
853
854 mcdx= [HW,CD]
855
856 mce [IA-32] Machine Check Exception
857
858 md= [HW] RAID subsystems devices and level
859 See Documentation/md.txt.
a9913044 860
1da177e4
LT
861 mdacon= [MDA]
862 Format: <first>,<last>
863 Specifies range of consoles to be captured by the MDA.
a9913044 864
1da177e4
LT
865 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
866 Amount of memory to be used when the kernel is not able
867 to see the whole system memory or for test.
868 [IA-32] Use together with memmap= to avoid physical
869 address space collisions. Without memmap= PCI devices
870 could be placed at addresses belonging to unused RAM.
871
872 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
873 memory.
874
69cda7b1 875 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
876 E820 memory map, as specified by the user.
877 Such memmap=exactmap lines can be constructed based on
878 BIOS output or other requirements. See the memmap=nn@ss
879 option description.
880
881 memmap=nn[KMG]@ss[KMG]
882 [KNL] Force usage of a specific region of memory
883 Region of memory to be used, from ss to ss+nn.
884
885 memmap=nn[KMG]#ss[KMG]
886 [KNL,ACPI] Mark specific memory as ACPI data.
887 Region of memory to be used, from ss to ss+nn.
888
889 memmap=nn[KMG]$ss[KMG]
890 [KNL,ACPI] Mark specific memory as reserved.
891 Region of memory to be used, from ss to ss+nn.
892
893 meye.*= [HW] Set MotionEye Camera parameters
894 See Documentation/video4linux/meye.txt.
895
896 mga= [HW,DRM]
897
198e2f18 898 migration_cost=
899 [KNL,SMP] debug: override scheduler migration costs
900 Format: <level-1-usecs>,<level-2-usecs>,...
901 This debugging option can be used to override the
902 default scheduler migration cost matrix. The numbers
903 are indexed by 'CPU domain distance'.
904 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
905 box will set up an intra-core migration cost of
906 1 msec, an inter-core migration cost of 2 msecs,
907 and an inter-node migration cost of 3 msecs.
908
909 WARNING: using the wrong values here can break
910 scheduler performance, so it's only for scheduler
911 development purposes, not production environments.
912
913 migration_debug=
914 [KNL,SMP] migration cost auto-detect verbosity
915 Format=<0|1|2>
916 If a system's migration matrix reported at bootup
917 seems erroneous then this option can be used to
918 increase verbosity of the detection process.
919 We default to 0 (no extra messages), 1 will print
920 some more information, and 2 will be really
921 verbose (probably only useful if you also have a
922 serial console attached to the system).
923
924 migration_factor=
925 [KNL,SMP] multiply/divide migration costs by a factor
926 Format=<percent>
927 This debug option can be used to proportionally
928 increase or decrease the auto-detected migration
929 costs for all entries of the migration matrix.
930 E.g. migration_factor=150 will increase migration
931 costs by 50%. (and thus the scheduler will be less
932 eager migrating cache-hot tasks)
933 migration_factor=80 will decrease migration costs
934 by 20%. (thus the scheduler will be more eager to
935 migrate tasks)
936
937 WARNING: using the wrong values here can break
938 scheduler performance, so it's only for scheduler
939 development purposes, not production environments.
940
1da177e4
LT
941 mousedev.tap_time=
942 [MOUSE] Maximum time between finger touching and
943 leaving touchpad surface for touch to be considered
944 a tap and be reported as a left button click (for
945 touchpads working in absolute mode only).
946 Format: <msecs>
947 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
948 reporting absolute coordinates, such as tablets
949 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
950 reporting absolute coordinates, such as tablets
951
952 mpu401= [HW,OSS]
953 Format: <io>,<irq>
954
955 MTD_Partition= [MTD]
956 Format: <name>,<region-number>,<size>,<offset>
957
a9913044
RD
958 MTD_Region= [MTD] Format:
959 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
960
961 mtdparts= [MTD]
962 See drivers/mtd/cmdline.c.
963
964 mtouchusb.raw_coordinates=
a9913044
RD
965 [HW] Make the MicroTouch USB driver use raw coordinates
966 ('y', default) or cooked coordinates ('n')
1da177e4
LT
967
968 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
969
970 NCR_D700= [HW,SCSI]
971 See header of drivers/scsi/NCR_D700.c.
972
973 ncr5380= [HW,SCSI]
974
975 ncr53c400= [HW,SCSI]
976
977 ncr53c400a= [HW,SCSI]
978
979 ncr53c406a= [HW,SCSI]
980
981 ncr53c8xx= [HW,SCSI]
982
983 netdev= [NET] Network devices parameters
984 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
985 Note that mem_start is often overloaded to mean
986 something different and driver-specific.
a9913044
RD
987 This usage is only documented in each driver source
988 file if at all.
989
1da177e4
LT
990 nfsaddrs= [NFS]
991 See Documentation/nfsroot.txt.
992
993 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
994 See Documentation/nfsroot.txt.
995
a72b4422
TM
996 nfs.callback_tcpport=
997 [NFS] set the TCP port on which the NFSv4 callback
998 channel should listen.
999
58df095b
TM
1000 nfs.idmap_cache_timeout=
1001 [NFS] set the maximum lifetime for idmapper cache
1002 entries.
1003
1da177e4
LT
1004 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1005
1006 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1007 emulation library even if a 387 maths coprocessor
1008 is present.
1009
a9913044
RD
1010 noalign [KNL,ARM]
1011
1da177e4
LT
1012 noapic [SMP,APIC] Tells the kernel to not make use of any
1013 IOAPICs that may be present in the system.
1014
1015 noasync [HW,M68K] Disables async and sync negotiation for
1016 all devices.
1017
1018 nobats [PPC] Do not use BATs for mapping kernel lowmem
1019 on "Classic" PPC cores.
1020
1021 nocache [ARM]
a9913044 1022
1da177e4
LT
1023 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1024
1025 noexec [IA-64]
1026
a9913044 1027 noexec [IA-32,X86-64]
1da177e4
LT
1028 noexec=on: enable non-executable mappings (default)
1029 noexec=off: disable nn-executable mappings
1030
4f886511
CE
1031 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1032 register save and restore. The kernel will only save
1033 legacy floating-point registers on task switch.
1da177e4
LT
1034
1035 nohlt [BUGS=ARM]
a9913044 1036
1da177e4
LT
1037 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1038 instruction doesn't work correctly and not to
1039 use it.
1040
1041 nohalt [IA-64] Tells the kernel not to use the power saving
1042 function PAL_HALT_LIGHT when idle. This increases
1043 power-consumption. On the positive side, it reduces
1044 interrupt wake-up latency, which may improve performance
1045 in certain environments such as networked servers or
1046 real-time systems.
1047
1048 noirqdebug [IA-32] Disables the code which attempts to detect and
1049 disable unhandled interrupt sources.
1050
1051 noisapnp [ISAPNP] Disables ISA PnP code.
1052
1053 noinitrd [RAM] Tells the kernel not to load any configured
1054 initial RAM disk.
1055
1056 nointroute [IA-64]
1057
1058 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1059
1060 noltlbs [PPC] Do not use large page/tlb entries for kernel
1061 lowmem mapping on PPC40x.
1062
312f1f01
H
1063 nomca [IA-64] Disable machine check abort handling
1064
abe37e5a
H
1065 nomce [IA-32] Machine Check Exception
1066
1da177e4
LT
1067 noresidual [PPC] Don't use residual data on PReP machines.
1068
a9913044
RD
1069 noresume [SWSUSP] Disables resume and restores original swap
1070 space.
1071
1da177e4
LT
1072 no-scroll [VGA] Disables scrollback.
1073 This is required for the Braillex ib80-piezo Braille
1074 reader made by F.H. Papenmeier (Germany).
1075
1076 nosbagart [IA-64]
1077
4f886511
CE
1078 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1079
1da177e4
LT
1080 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1081
1082 nosync [HW,M68K] Disables sync negotiation for all devices.
1083
1084 notsc [BUGS=IA-32] Disable Time Stamp Counter
1085
1086 nousb [USB] Disable the USB subsystem
1087
1088 nowb [ARM]
a9913044 1089
a61c2d78
DJ
1090 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1091
1da177e4
LT
1092 opl3= [HW,OSS]
1093 Format: <io>
1094
1095 opl3sa= [HW,OSS]
1096 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1097
a9913044
RD
1098 opl3sa2= [HW,OSS] Format:
1099 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1100
1da177e4
LT
1101 oprofile.timer= [HW]
1102 Use timer interrupt instead of performance counters
1103
1104 optcd= [HW,CD]
1105 Format: <io>
1106
1107 osst= [HW,SCSI] SCSI Tape Driver
1108 Format: <buffer_size>,<write_threshold>
1109 See also Documentation/scsi/st.txt.
1110
1111 panic= [KNL] Kernel behaviour on panic
1112 Format: <timeout>
1113
1114 parkbd.port= [HW] Parallel port number the keyboard adapter is
1115 connected to, default is 0.
1116 Format: <parport#>
1117 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1118 0 for XT, 1 for AT (default is AT).
a9913044
RD
1119 Format: <mode>
1120
1121 parport= [HW,PPT] Specify parallel ports. 0 disables.
1122 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1123 Use 'auto' to force the driver to use any
1124 IRQ/DMA settings detected (the default is to
1125 ignore detected IRQ/DMA settings because of
1126 possible conflicts). You can specify the base
1127 address, IRQ, and DMA settings; IRQ and DMA
1128 should be numbers, or 'auto' (for using detected
1129 settings on that particular port), or 'nofifo'
1130 (to avoid using a FIFO even if it is detected).
1131 Parallel ports are assigned in the order they
1132 are specified on the command line, starting
1133 with parport0.
1134
1135 parport_init_mode= [HW,PPT]
1136 Configure VIA parallel port to operate in
1137 a specific mode. This is necessary on Pegasos
1138 computer where firmware has no options for setting
1139 up parallel port mode and sets it to spp.
1140 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1141 Format: [spp|ps2|epp|ecp|ecpepp]
1142
a9913044
RD
1143 pas2= [HW,OSS] Format:
1144 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1145
1da177e4
LT
1146 pas16= [HW,SCSI]
1147 See header of drivers/scsi/pas16.c.
1148
dd287796
AM
1149 pause_on_oops=
1150 Halt all CPUs after the first oops has been printed for
1151 the specified number of seconds. This is to be used if
1152 your oopses keep scrolling off the screen.
1153
1da177e4
LT
1154 pcbit= [HW,ISDN]
1155
1156 pcd. [PARIDE]
1157 See header of drivers/block/paride/pcd.c.
1158 See also Documentation/paride.txt.
1159
a9913044
RD
1160 pci=option[,option...] [PCI] various PCI subsystem options:
1161 off [IA-32] don't probe for the PCI bus
1162 bios [IA-32] force use of PCI BIOS, don't access
1163 the hardware directly. Use this if your machine
1164 has a non-standard PCI host bridge.
1165 nobios [IA-32] disallow use of PCI BIOS, only direct
1166 hardware access methods are allowed. Use this
1167 if you experience crashes upon bootup and you
1168 suspect they are caused by the BIOS.
1169 conf1 [IA-32] Force use of PCI Configuration
1170 Mechanism 1.
1171 conf2 [IA-32] Force use of PCI Configuration
1172 Mechanism 2.
61be6d66
BH
1173 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1174 Configuration
309e57df
MW
1175 nomsi [MSI] If the PCI_MSI kernel config parameter is
1176 enabled, this kernel boot option can be used to
1177 disable the use of MSI interrupts system-wide.
a9913044
RD
1178 nosort [IA-32] Don't sort PCI devices according to
1179 order given by the PCI BIOS. This sorting is
1180 done to get a device order compatible with
1181 older kernels.
1182 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1183 routing table. These calls are known to be buggy
1184 on several machines and they hang the machine
1185 when used, but on other computers it's the only
1186 way to get the interrupt routing table. Try
1187 this option if the kernel is unable to allocate
1188 IRQs or discover secondary PCI buses on your
1189 motherboard.
1190 rom [IA-32] Assign address space to expansion ROMs.
1191 Use with caution as certain devices share
1192 address decoders between ROMs and other
1193 resources.
1194 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1195 assigned automatically to PCI devices. You can
1196 make the kernel exclude IRQs of your ISA cards
1197 this way.
120bb424 1198 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1199 of the PIRQ table (normally generated
1200 by the BIOS) if it is outside the
1201 F0000h-100000h range.
1202 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1203 useful if the kernel is unable to find your
1204 secondary buses and you want to tell it
1205 explicitly which ones they are.
1206 assign-busses [IA-32] Always assign all PCI bus
1207 numbers ourselves, overriding
1208 whatever the firmware may have done.
1209 usepirqmask [IA-32] Honor the possible IRQ mask stored
1210 in the BIOS $PIR table. This is needed on
1211 some systems with broken BIOSes, notably
1212 some HP Pavilion N5400 and Omnibook XE3
1213 notebooks. This will have no effect if ACPI
1214 IRQ routing is enabled.
1215 noacpi [IA-32] Do not use ACPI for IRQ routing
1216 or for PCI scanning.
1217 routeirq Do IRQ routing for all PCI devices.
1218 This is normally done in pci_enable_device(),
1219 so this option is a temporary workaround
1220 for broken drivers that don't call it.
1221 firmware [ARM] Do not re-enumerate the bus but instead
1222 just use the configuration from the
1223 bootloader. This is currently used on
1224 IXP2000 systems where the bus has to be
1225 configured a certain way for adjunct CPUs.
1da177e4
LT
1226
1227 pcmv= [HW,PCMCIA] BadgePAD 4
1228
1229 pd. [PARIDE]
1230 See Documentation/paride.txt.
1231
1232 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1233 boot time.
1234 Format: { 0 | 1 }
1235 See arch/parisc/kernel/pdc_chassis.c
1236
1237 pf. [PARIDE]
1238 See Documentation/paride.txt.
1239
1240 pg. [PARIDE]
1241 See Documentation/paride.txt.
1242
1243 pirq= [SMP,APIC] Manual mp-table setup
1244 See Documentation/i386/IO-APIC.txt.
1245
1246 plip= [PPT,NET] Parallel port network link
1247 Format: { parport<nr> | timid | 0 }
1248 See also Documentation/parport.txt.
1249
1250 pnpacpi= [ACPI]
1251 { off }
1252
1253 pnpbios= [ISAPNP]
1254 { on | off | curr | res | no-curr | no-res }
1255
1256 pnp_reserve_irq=
1257 [ISAPNP] Exclude IRQs for the autoconfiguration
1258
1259 pnp_reserve_dma=
1260 [ISAPNP] Exclude DMAs for the autoconfiguration
1261
1262 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1263 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1264
1265 pnp_reserve_mem=
a9913044
RD
1266 [ISAPNP] Exclude memory regions for the
1267 autoconfiguration.
1da177e4
LT
1268 Ranges are in pairs (memory base and size).
1269
1270 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1271 Format: [schedule,]<number>
1272 Param: "schedule" - profile schedule points.
1273 Param: <number> - step/bucket size as a power of 2 for
1274 statistical time based profiling.
1da177e4 1275
a9913044 1276 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1277 Limit processor to maximum C-state
1278 max_cstate=9 overrides any DMI blacklist limit.
1279
41c0d868
LB
1280 processor.nocst [HW,ACPI]
1281 Ignore the _CST method to determine C-states,
1282 instead using the legacy FADT method
1283
1da177e4
LT
1284 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1285 before loading.
1286 See Documentation/ramdisk.txt.
1287
a9913044
RD
1288 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1289 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1290 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1291 per second.
a9913044
RD
1292 psmouse.resetafter= [HW,MOUSE]
1293 Try to reset the device after so many bad packets
1da177e4
LT
1294 (0 = never).
1295 psmouse.resolution=
1296 [HW,MOUSE] Set desired mouse resolution, in dpi.
1297 psmouse.smartscroll=
a9913044 1298 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1299 0 = disabled, 1 = enabled (default).
1300
1301 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1302 Format:
1303 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1304
1305 pt. [PARIDE]
1306 See Documentation/paride.txt.
1307
1308 quiet= [KNL] Disable log messages
a9913044 1309
1da177e4
LT
1310 r128= [HW,DRM]
1311
1312 raid= [HW,RAID]
1313 See Documentation/md.txt.
1314
1315 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1316 See Documentation/ramdisk.txt.
1317
a9913044 1318 ramdisk_blocksize= [RAM]
1da177e4 1319 See Documentation/ramdisk.txt.
a9913044 1320
1da177e4
LT
1321 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1322 New name for the ramdisk parameter.
1323 See Documentation/ramdisk.txt.
1324
21a1ea9e
DS
1325 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1326 RCU callbacks to process in one batch.
1327
1328 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1329 RCU callbacks over which batch limiting is disabled.
1330
1331 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1332 RCU callbacks below which batch limiting is re-enabled.
1333
1334 rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
1335 RCU callbacks to queued before forcing reschedule
1336 on all cpus.
1337
ffdfc409
OJ
1338 rdinit= [KNL]
1339 Format: <full_path>
1340 Run specified binary instead of /init from the ramdisk,
1341 used for early userspace startup. See initrd.
1342
1da177e4
LT
1343 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1344 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1345 See arch/*/kernel/reboot.c.
1346
1347 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1348
a9913044
RD
1349 resume= [SWSUSP]
1350 Specify the partition device for software suspend
1da177e4
LT
1351
1352 rhash_entries= [KNL,NET]
1353 Set number of hash buckets for route cache
1354
1355 riscom8= [HW,SERIAL]
1356 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1357
1358 ro [KNL] Mount root device read-only on boot
1359
1360 root= [KNL] Root filesystem
1361
1362 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1363 mount the root filesystem
1364
1365 rootflags= [KNL] Set root filesystem mount option string
1366
1367 rootfstype= [KNL] Set root filesystem type
1368
1369 rw [KNL] Mount root device read-write on boot
1370
1371 S [KNL] Run init in single mode
1372
1373 sa1100ir [NET]
1374 See drivers/net/irda/sa1100_ir.c.
1375
1376 sb= [HW,OSS]
1377 Format: <io>,<irq>,<dma>,<dma2>
1378
1379 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1380
1da177e4
LT
1381 sbpcd= [HW,CD] Soundblaster CD adapter
1382 Format: <io>,<type>
1383 See a comment before function sbpcd_setup() in
1384 drivers/cdrom/sbpcd.c.
1385
1386 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1387 Format: <io>[,<timeout>[,<isapnp>]]
1388
1389 scsi_debug_*= [SCSI]
1390 See drivers/scsi/scsi_debug.c.
1391
1392 scsi_default_dev_flags=
1393 [SCSI] SCSI default device flags
1394 Format: <integer>
1395
1396 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1397 Format: <vendor>:<model>:<flags>
1398 (flags are integer value)
1399
1400 scsi_logging= [SCSI]
1401
1402 selinux [SELINUX] Disable or enable SELinux at boot time.
1403 Format: { "0" | "1" }
1404 See security/selinux/Kconfig help text.
1405 0 -- disable.
1406 1 -- enable.
1407 Default value is set via kernel config option.
1408 If enabled at boot time, /selinux/disable can be used
1409 later to disable prior to initial policy load.
1410
4e5ab4cb
JM
1411 selinux_compat_net =
1412 [SELINUX] Set initial selinux_compat_net flag value.
1413 Format: { "0" | "1" }
1414 0 -- use new secmark-based packet controls
1415 1 -- use legacy packet controls
1416 Default value is 0 (preferred).
1417 Value can be changed at runtime via
1418 /selinux/compat_net.
1419
1da177e4
LT
1420 serialnumber [BUGS=IA-32]
1421
a9913044
RD
1422 sg_def_reserved_size= [SCSI]
1423
1da177e4
LT
1424 sgalaxy= [HW,OSS]
1425 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1426
1427 shapers= [NET]
1428 Maximal number of shapers.
a9913044 1429
1da177e4
LT
1430 sim710= [SCSI,HW]
1431 See header of drivers/scsi/sim710.c.
1432
1433 simeth= [IA-64]
1434 simscsi=
a9913044 1435
1da177e4
LT
1436 sjcd= [HW,CD]
1437 Format: <io>,<irq>,<dma>
1438 See header of drivers/cdrom/sjcd.c.
1439
1440 slram= [HW,MTD]
1441
1442 smart2= [HW]
1443 Format: <io1>[,<io2>[,...,<io8>]]
1444
1445 snd-ad1816a= [HW,ALSA]
1446
1447 snd-ad1848= [HW,ALSA]
1448
1449 snd-ali5451= [HW,ALSA]
1450
1451 snd-als100= [HW,ALSA]
1452
1453 snd-als4000= [HW,ALSA]
1454
1455 snd-azt2320= [HW,ALSA]
1456
1457 snd-cmi8330= [HW,ALSA]
1458
1459 snd-cmipci= [HW,ALSA]
1460
1461 snd-cs4231= [HW,ALSA]
1462
1463 snd-cs4232= [HW,ALSA]
1464
1465 snd-cs4236= [HW,ALSA]
1466
1467 snd-cs4281= [HW,ALSA]
1468
1469 snd-cs46xx= [HW,ALSA]
1470
1471 snd-dt019x= [HW,ALSA]
1472
1473 snd-dummy= [HW,ALSA]
1474
1475 snd-emu10k1= [HW,ALSA]
1476
1477 snd-ens1370= [HW,ALSA]
1478
1479 snd-ens1371= [HW,ALSA]
1480
1481 snd-es968= [HW,ALSA]
1482
1483 snd-es1688= [HW,ALSA]
1484
1485 snd-es18xx= [HW,ALSA]
1486
1487 snd-es1938= [HW,ALSA]
1488
1489 snd-es1968= [HW,ALSA]
1490
1491 snd-fm801= [HW,ALSA]
1492
1493 snd-gusclassic= [HW,ALSA]
1494
1495 snd-gusextreme= [HW,ALSA]
1496
1497 snd-gusmax= [HW,ALSA]
1498
1499 snd-hdsp= [HW,ALSA]
1500
1501 snd-ice1712= [HW,ALSA]
1502
1503 snd-intel8x0= [HW,ALSA]
1504
1505 snd-interwave= [HW,ALSA]
1506
1507 snd-interwave-stb=
1508 [HW,ALSA]
1509
1510 snd-korg1212= [HW,ALSA]
1511
1512 snd-maestro3= [HW,ALSA]
1513
1514 snd-mpu401= [HW,ALSA]
1515
1516 snd-mtpav= [HW,ALSA]
1517
1518 snd-nm256= [HW,ALSA]
1519
1520 snd-opl3sa2= [HW,ALSA]
1521
1522 snd-opti92x-ad1848=
1523 [HW,ALSA]
1524
1525 snd-opti92x-cs4231=
1526 [HW,ALSA]
1527
1528 snd-opti93x= [HW,ALSA]
1529
1530 snd-pmac= [HW,ALSA]
1531
1532 snd-rme32= [HW,ALSA]
1533
1534 snd-rme96= [HW,ALSA]
1535
1536 snd-rme9652= [HW,ALSA]
1537
1538 snd-sb8= [HW,ALSA]
1539
1540 snd-sb16= [HW,ALSA]
1541
1542 snd-sbawe= [HW,ALSA]
1543
1544 snd-serial= [HW,ALSA]
1545
1546 snd-sgalaxy= [HW,ALSA]
1547
1548 snd-sonicvibes= [HW,ALSA]
1549
1550 snd-sun-amd7930=
1551 [HW,ALSA]
1552
1553 snd-sun-cs4231= [HW,ALSA]
1554
1555 snd-trident= [HW,ALSA]
1556
1557 snd-usb-audio= [HW,ALSA,USB]
1558
1559 snd-via82xx= [HW,ALSA]
1560
1561 snd-virmidi= [HW,ALSA]
1562
1563 snd-wavefront= [HW,ALSA]
1564
1565 snd-ymfpci= [HW,ALSA]
a9913044 1566
1da177e4
LT
1567 sonicvibes= [HW,OSS]
1568 Format: <reverb>
a9913044 1569
1da177e4
LT
1570 sonycd535= [HW,CD]
1571 Format: <io>[,<irq>]
1572
1573 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1574 See Documentation/sonypi.txt
1575
1576 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1577 See Documentation/specialix.txt.
1578
1579 spia_io_base= [HW,MTD]
1580 spia_fio_base=
1581 spia_pedr=
1582 spia_peddr=
1583
1584 sscape= [HW,OSS]
1585 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1586
1da177e4
LT
1587 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1588 See Documentation/scsi/st.txt.
1589
1590 st0x= [HW,SCSI]
1591 See header of drivers/scsi/seagate.c.
1592
1593 sti= [PARISC,HW]
1594 Format: <num>
1595 Set the STI (builtin display/keyboard on the HP-PARISC
1596 machines) console (graphic card) which should be used
1597 as the initial boot-console.
1598 See also comment in drivers/video/console/sticore.c.
1599
1600 sti_font= [HW]
1601 See comment in drivers/video/console/sticore.c.
1602
1603 stifb= [HW]
1604 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1605
1da177e4 1606 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1607
1da177e4
LT
1608 switches= [HW,M68k]
1609
1610 sym53c416= [HW,SCSI]
1611 See header of drivers/scsi/sym53c416.c.
1612
1613 t128= [HW,SCSI]
1614 See header of drivers/scsi/t128.c.
1615
1616 tdfx= [HW,DRM]
1617
1618 thash_entries= [KNL,NET]
1619 Set number of hash buckets for TCP connection
1620
1621 time Show timing data prefixed to each printk message line
1622
734efb46
JS
1623 clocksource= [GENERIC_TIME] Override the default clocksource
1624 Override the default clocksource and use the clocksource
1625 with the name specified.
1626
1da177e4
LT
1627 tipar.timeout= [HW,PPT]
1628 Set communications timeout in tenths of a second
1629 (default 15).
1630
1631 tipar.delay= [HW,PPT]
1632 Set inter-bit delay in microseconds (default 10).
1633
1634 tmc8xx= [HW,SCSI]
1635 See header of drivers/scsi/seagate.c.
1636
1637 tmscsim= [HW,SCSI]
1638 See comment before function dc390_setup() in
1639 drivers/scsi/tmscsim.c.
1640
1641 tp720= [HW,PS2]
1642
1643 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1644 Format:
1645 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1646
1da177e4
LT
1647 tsdev.xres= [TS] Horizontal screen resolution.
1648 tsdev.yres= [TS] Vertical screen resolution.
1649
a9913044
RD
1650 turbografx.map[2|3]= [HW,JOY]
1651 TurboGraFX parallel port interface
1652 Format:
1653 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1654 See also Documentation/input/joystick-parport.txt
1655
1656 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1657 See header of drivers/scsi/u14-34f.c.
1658
1659 uart401= [HW,OSS]
1660 Format: <io>,<irq>
1661
1662 uart6850= [HW,OSS]
1663 Format: <io>,<irq>
1664
1da177e4
LT
1665 usbhid.mousepoll=
1666 [USBHID] The interval which mice are to be polled at.
a9913044 1667
e6e5494c
IM
1668 vdso= [IA-32]
1669 vdso=1: enable VDSO (default)
1670 vdso=0: disable VDSO mapping
1671
1da177e4
LT
1672 video= [FB] Frame buffer configuration
1673 See Documentation/fb/modedb.txt.
1674
1675 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1676 See Documentation/i386/boot.txt and
1677 Documentation/svga.txt.
1da177e4
LT
1678 Use vga=ask for menu.
1679 This is actually a boot loader parameter; the value is
1680 passed to the kernel using a special protocol.
1681
a9913044 1682 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1683 size of <nn>. This can be used to increase the
1684 minimum size (128MB on x86). It can also be used to
1685 decrease the size and leave more room for directly
1686 mapped kernel RAM.
1687
585c3047
PO
1688 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1689 Format: <command>
1da177e4 1690
585c3047
PO
1691 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1692 Format: <command>
1693
1694 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1695 Format: <command>
a9913044 1696
1da177e4
LT
1697 waveartist= [HW,OSS]
1698 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1699
1da177e4
LT
1700 wd33c93= [HW,SCSI]
1701 See header of drivers/scsi/wd33c93.c.
1702
1703 wd7000= [HW,SCSI]
1704 See header of drivers/scsi/wd7000.c.
1705
1706 wdt= [WDT] Watchdog
1707 See Documentation/watchdog/watchdog.txt.
1708
1709 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1710 xd_geo= See header of drivers/block/xd.c.
1711
1712 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1713 Format:
1714 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1715
a62eaf15
AK
1716 norandmaps Don't use address space randomization
1717 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1718
1da177e4 1719
a9913044 1720______________________________________________________________________
1da177e4
LT
1721
1722TODO:
1723
1724 Add documentation for ALSA options.
1725 Add more DRM drivers.