Doc/kernel-parameters.txt: mention modinfo and sysfs
[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
a9913044 27The text in square brackets at the beginning of the description states the
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28restrictions on the kernel for the said kernel parameter to be valid. The
29restrictions referred to are that the relevant option is valid if:
30
31 ACPI ACPI support is enabled.
32 ALSA ALSA sound support is enabled.
33 APIC APIC support is enabled.
34 APM Advanced Power Management support is enabled.
35 AX25 Appropriate AX.25 support is enabled.
36 CD Appropriate CD support is enabled.
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37 DEVFS devfs support is enabled.
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.
63 NFS Appropriate NFS support is enabled.
64 OSS OSS sound support is enabled.
65 PARIDE The ParIDE subsystem is enabled.
66 PARISC The PA-RISC architecture is enabled.
67 PCI PCI bus support is enabled.
68 PCMCIA The PCMCIA subsystem is enabled.
69 PNP Plug & Play support is enabled.
70 PPC PowerPC architecture is enabled.
71 PPT Parallel port support is enabled.
72 PS2 Appropriate PS/2 support is enabled.
73 RAM RAM disk support is enabled.
74 S390 S390 architecture is enabled.
75 SCSI Appropriate SCSI support is enabled.
76 A lot of drivers has their options described inside of
77 Documentation/scsi/.
78 SELINUX SELinux support is enabled.
79 SERIAL Serial support is enabled.
80 SMP The kernel is an SMP kernel.
81 SPARC Sparc architecture is enabled.
a9913044 82 SWSUSP Software suspend is enabled.
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83 TS Appropriate touchscreen support is enabled.
84 USB USB support is enabled.
85 USBHID USB Human Interface Device support is enabled.
86 V4L Video For Linux support is enabled.
87 VGA The VGA console has been enabled.
88 VT Virtual terminal support is enabled.
89 WDT Watchdog support is enabled.
90 XT IBM PC/XT MFM hard disk support is enabled.
91 X86-64 X86-64 architecture is enabled.
92 More X86-64 boot options can be found in
93 Documentation/x86_64/boot-options.txt .
94
95In addition, the following text indicates that the option:
96
97 BUGS= Relates to possible processor bugs on the said processor.
98 KNL Is a kernel start-up parameter.
99 BOOT Is a boot loader parameter.
100
101Parameters denoted with BOOT are actually interpreted by the boot
102loader, and have no meaning to the kernel directly.
103Do not modify the syntax of boot loader parameters without extreme
104need or coordination with <Documentation/i386/boot.txt>.
105
106Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
107a trailing = on the name of any parameter states that that parameter will
108be entered as an environment variable, whereas its absence indicates that
109it will appear as a kernel argument readable via /proc/cmdline by programs
110running once the system is up.
111
112 53c7xx= [HW,SCSI] Amiga SCSI controllers
113 See header of drivers/scsi/53c7xx.c.
114 See also Documentation/scsi/ncr53c7xx.txt.
115
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116 acpi= [HW,ACPI] Advanced Configuration and Power Interface
117 Format: { force | off | ht | strict | noirq }
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118 force -- enable ACPI if default was off
119 off -- disable ACPI if default was on
120 noirq -- do not use ACPI for IRQ routing
121 ht -- run only enough ACPI to enable Hyper Threading
a9913044 122 strict -- Be less tolerant of platforms that are not
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123 strictly ACPI specification compliant.
124
125 See also Documentation/pm.txt, pci=noacpi
126
127 acpi_sleep= [HW,ACPI] Sleep options
128 Format: { s3_bios, s3_mode }
129 See Documentation/power/video.txt
a9913044 130
1da177e4 131 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 132 Format: { level | edge | high | low }
1da177e4 133
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134 acpi_irq_balance [HW,ACPI]
135 ACPI will balance active IRQs
136 default in APIC mode
1da177e4 137
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138 acpi_irq_nobalance [HW,ACPI]
139 ACPI will not move active IRQs (default)
140 default in PIC mode
1da177e4 141
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142 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
143 use by PCI
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144 Format: <irq>,<irq>...
145
a9913044 146 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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147 Format: <irq>,<irq>...
148
149 acpi_osi= [HW,ACPI] empty param disables _OSI
150
151 acpi_serialize [HW,ACPI] force serialization of AML methods
152
153 acpi_skip_timer_override [HW,ACPI]
154 Recognize and ignore IRQ0/pin2 Interrupt Override.
155 For broken nForce2 BIOS resulting in XT-PIC timer.
156
157 acpi_dbg_layer= [HW,ACPI]
158 Format: <int>
a9913044 159 Each bit of the <int> indicates an ACPI debug layer,
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160 1: enable, 0: disable. It is useful for boot time
161 debugging. After system has booted up, it can be set
162 via /proc/acpi/debug_layer.
163
164 acpi_dbg_level= [HW,ACPI]
165 Format: <int>
a9913044 166 Each bit of the <int> indicates an ACPI debug level,
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167 1: enable, 0: disable. It is useful for boot time
168 debugging. After system has booted up, it can be set
169 via /proc/acpi/debug_level.
170
171 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
172
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173 acpi_generic_hotkey [HW,ACPI]
174 Allow consolidated generic hotkey driver to
a9913044 175 override platform specific driver.
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176 See also Documentation/acpi-hotkey.txt.
177
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178 enable_timer_pin_1 [i386,x86-64]
179 Enable PIN 1 of APIC timer
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180 Can be useful to work around chipset bugs
181 (in particular on some ATI chipsets).
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182 The kernel tries to set a reasonable default.
183
184 disable_timer_pin_1 [i386,x86-64]
185 Disable PIN 1 of APIC timer
186 Can be useful to work around chipset bugs.
187
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188 ad1816= [HW,OSS]
189 Format: <io>,<irq>,<dma>,<dma2>
190 See also Documentation/sound/oss/AD1816.
191
192 ad1848= [HW,OSS]
193 Format: <io>,<irq>,<dma>,<dma2>,<type>
194
195 adlib= [HW,OSS]
196 Format: <io>
a9913044 197
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198 advansys= [HW,SCSI]
199 See header of drivers/scsi/advansys.c.
200
201 advwdt= [HW,WDT] Advantech WDT
202 Format: <iostart>,<iostop>
203
204 aedsp16= [HW,OSS] Audio Excel DSP 16
205 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
206 See also header of sound/oss/aedsp16.c.
a9913044 207
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208 aha152x= [HW,SCSI]
209 See Documentation/scsi/aha152x.txt.
210
211 aha1542= [HW,SCSI]
212 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
213
214 aic7xxx= [HW,SCSI]
215 See Documentation/scsi/aic7xxx.txt.
216
217 aic79xx= [HW,SCSI]
218 See Documentation/scsi/aic79xx.txt.
219
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220 amijoy.map= [HW,JOY] Amiga joystick support
221 Map of devices attached to JOY0DAT and JOY1DAT
222 Format: <a>,<b>
223 See also Documentation/kernel/input/joystick.txt
224
225 analog.map= [HW,JOY] Analog joystick and gamepad support
226 Specifies type or capabilities of an analog joystick
227 connected to one of 16 gameports
228 Format: <type1>,<type2>,..<type16>
229
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230 apc= [HW,SPARC]
231 Power management functions (SPARCstation-4/5 + deriv.)
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232 Format: noidle
233 Disable APC CPU standby support. SPARCstation-Fox does
234 not play well with APC CPU idle - disable it if you have
235 APC and your system crashes randomly.
236
a9913044 237 apic= [APIC,i386] Change the output verbosity whilst booting
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238 Format: { quiet (default) | verbose | debug }
239 Change the amount of debugging information output
240 when initialising the APIC and IO-APIC components.
a9913044 241
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242 apm= [APM] Advanced Power Management
243 See header of arch/i386/kernel/apm.c.
244
245 applicom= [HW]
246 Format: <mem>,<irq>
a9913044 247
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248 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
249 Format: <io>,<irq>,<nodeID>
250
251 ataflop= [HW,M68k]
252
253 atarimouse= [HW,MOUSE] Atari Mouse
254
255 atascsi= [HW,SCSI] Atari SCSI
256
257 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
258 EzKey and similar keyboards
259
260 atkbd.reset= [HW] Reset keyboard during initialization
261
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262 atkbd.set= [HW] Select keyboard code set
263 Format: <int> (2 = AT (default), 3 = PS/2)
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264
265 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
266 keyboards
267
268 atkbd.softraw= [HW] Choose between synthetic and real raw mode
269 Format: <bool> (0 = real, 1 = synthetic (default))
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270
271 atkbd.softrepeat= [HW]
272 Use software keyboard repeat
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273
274 autotest [IA64]
275
276 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
277 Format: <io>,<memsize>,<isapnp>
a9913044 278
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279 aztcd= [HW,CD] Aztech CD268 CDROM driver
280 Format: <io>,0x79 (?)
281
282 baycom_epp= [HW,AX25]
283 Format: <io>,<mode>
a9913044 284
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285 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
286 Format: <io>,<mode>
287 See header of drivers/net/hamradio/baycom_par.c.
288
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289 baycom_ser_fdx= [HW,AX25]
290 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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291 Format: <io>,<irq>,<mode>[,<baud>]
292 See header of drivers/net/hamradio/baycom_ser_fdx.c.
293
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294 baycom_ser_hdx= [HW,AX25]
295 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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296 Format: <io>,<irq>,<mode>
297 See header of drivers/net/hamradio/baycom_ser_hdx.c.
298
299 blkmtd_device= [HW,MTD]
300 blkmtd_erasesz=
301 blkmtd_ro=
302 blkmtd_bs=
303 blkmtd_count=
304
305 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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306 bttv.radio= Most important insmod options are available as
307 kernel args too.
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308 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
309 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
310
311 BusLogic= [HW,SCSI]
312 See drivers/scsi/BusLogic.c, comment before function
313 BusLogic_ParseDriverOptions().
314
315 c101= [NET] Moxa C101 synchronous serial card
316
317 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
318 Sometimes CPU hardware bugs make them report the cache
319 size incorrectly. The kernel will attempt work arounds
320 to fix known problems, but for some CPUs it is not
321 possible to determine what the correct size should be.
322 This option provides an override for these situations.
323
324 cdu31a= [HW,CD]
325 Format: <io>,<irq>[,PAS]
326 See header of drivers/cdrom/cdu31a.c.
327
328 chandev= [HW,NET] Generic channel device initialisation
329
330 checkreqprot [SELINUX] Set initial checkreqprot flag value.
331 Format: { "0" | "1" }
332 See security/selinux/Kconfig help text.
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333 0 -- check protection applied by kernel (includes
334 any implied execute protection).
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335 1 -- check protection requested by application.
336 Default value is set via a kernel config option.
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337 Value can be changed at runtime via
338 /selinux/checkreqprot.
339
340 clock= [BUGS=IA-32,HW] gettimeofday timesource override.
1da177e4 341 Forces specified timesource (if avaliable) to be used
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342 when calculating gettimeofday(). If specicified
343 timesource is not avalible, it defaults to PIT.
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344 Format: { pit | tsc | cyclone | pmtmr }
345
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346 disable_8254_timer
347 enable_8254_timer
348 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
349 over the 8254 in addition to over the IO-APIC. The
350 kernel tries to set a sensible default.
351
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352 hpet= [IA-32,HPET] option to disable HPET and use PIT.
353 Format: disable
354
355 cm206= [HW,CD]
356 Format: { auto | [<io>,][<irq>] }
357
358 com20020= [HW,NET] ARCnet - COM20020 chipset
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359 Format:
360 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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361
362 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
363 Format: <io>[,<irq>]
364
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365 com90xx= [HW,NET]
366 ARCnet - COM90xx chipset (memory-mapped buffers)
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367 Format: <io>[,<irq>[,<memstart>]]
368
369 condev= [HW,S390] console device
370 conmode=
a9913044 371
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372 console= [KNL] Output console device and options.
373
374 tty<n> Use the virtual console device <n>.
375
376 ttyS<n>[,options]
f1a1c2dc 377 ttyUSB0[,options]
1da177e4 378 Use the specified serial port. The options are of
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379 the form "bbbbpnf", where "bbbb" is the baud rate,
380 "p" is parity ("n", "o", or "e"), "n" is number of
381 bits, and "f" is flow control ("r" for RTS or
382 omit it). Default is "9600n8".
383
384 See Documentation/serial-console.txt for more
385 information. See
386 Documentation/networking/netconsole.txt for an
387 alternative.
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388
389 uart,io,<addr>[,options]
390 uart,mmio,<addr>[,options]
391 Start an early, polled-mode console on the 8250/16550
392 UART at the specified I/O port or MMIO address,
393 switching to the matching ttyS device later. The
394 options are the same as for ttyS, above.
395
396 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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397 Format:
398 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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399
400 cpia_pp= [HW,PPT]
401 Format: { parport<nr> | auto | none }
402
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403 crashkernel=nn[KMG]@ss[KMG]
404 [KNL] Reserve a chunk of physical memory to
405 hold a kernel to switch to with kexec on panic.
406
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407 cs4232= [HW,OSS]
408 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
409
410 cs89x0_dma= [HW,NET]
411 Format: <dma>
412
413 cs89x0_media= [HW,NET]
414 Format: { rj45 | aui | bnc }
a9913044 415
1da177e4 416 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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417
418 dasd= [HW,NET]
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419 See header of drivers/s390/block/dasd_devmap.c.
420
421 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
422 (one device per port)
423 Format: <port#>,<type>
424 See also Documentation/input/joystick-parport.txt
425
426 debug [KNL] Enable kernel debugging (events log level).
427
428 decnet= [HW,NET]
429 Format: <area>[,<node>]
430 See also Documentation/networking/decnet.txt.
431
432 devfs= [DEVFS]
433 See Documentation/filesystems/devfs/boot-options.
434
435 dhash_entries= [KNL]
436 Set number of hash buckets for dentry cache.
a9913044 437
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438 digi= [HW,SERIAL]
439 IO parameters + enable/disable command.
440
441 digiepca= [HW,SERIAL]
442 See drivers/char/README.epca and
443 Documentation/digiepca.txt.
444
445 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
446 support available.
447 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
448
449 dmasound= [HW,OSS] Sound subsystem buffers
450
451 dscc4.setup= [NET]
452
453 dtc3181e= [HW,SCSI]
454
a9913044 455 earlyprintk= [IA-32,X86-64]
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456 earlyprintk=vga
457 earlyprintk=serial[,ttySn[,baudrate]]
458
a9913044 459 Append ",keep" to not disable it when the real console
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460 takes over.
461
462 Only vga or serial at a time, not both.
463
464 Currently only ttyS0 and ttyS1 are supported.
465
466 Interaction with the standard serial driver is not
467 very good.
468
469 The VGA output is eventually overwritten by the real
470 console.
471
472 eata= [HW,SCSI]
473
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474 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
475 Format: <int>
476 0: polling mode
477 non-0: interrupt mode (default)
478
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479 eda= [HW,PS2]
480
481 edb= [HW,PS2]
482
483 edd= [EDD]
484 Format: {"of[f]" | "sk[ipmbr]"}
485 See comment in arch/i386/boot/edd.S
486
a9913044 487 eicon= [HW,ISDN]
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488 Format: <id>,<membase>,<irq>
489
490 eisa_irq_edge= [PARISC,HW]
491 See header of drivers/parisc/eisa.c.
492
493 elanfreq= [IA-32]
494 See comment before function elanfreq_setup() in
495 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
496
497 elevator= [IOSCHED]
16ab3adf 498 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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499 See Documentation/block/as-iosched.txt and
500 Documentation/block/deadline-iosched.txt for details.
501
aac04b32 502 elfcorehdr= [IA-32, X86_64]
a9913044 503 Specifies physical address of start of kernel core
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504 image elf header. Generally kexec loader will
505 pass this option to capture kernel.
506 See Documentation/kdump/kdump.txt for details.
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507
508 enforcing [SELINUX] Set initial enforcing status.
509 Format: {"0" | "1"}
510 See security/selinux/Kconfig help text.
511 0 -- permissive (log only, no denials).
512 1 -- enforcing (deny and log).
513 Default value is 0.
514 Value can be changed at runtime via /selinux/enforce.
515
516 es1370= [HW,OSS]
517 Format: <lineout>[,<micbias>]
518 See also header of sound/oss/es1370.c.
519
520 es1371= [HW,OSS]
521 Format: <spdif>,[<nomix>,[<amplifier>]]
522 See also header of sound/oss/es1371.c.
a9913044 523
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524 ether= [HW,NET] Ethernet cards parameters
525 This option is obsoleted by the "netdev=" option, which
526 has equivalent usage. See its documentation for details.
527
528 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
529 Format: <io>[,<irq>]
530
531 fd_mcs= [HW,SCSI]
532 See header of drivers/scsi/fd_mcs.c.
533
534 fdomain= [HW,SCSI]
535 See header of drivers/scsi/fdomain.c.
536
537 floppy= [HW]
538 See Documentation/floppy.txt.
539
540 ftape= [HW] Floppy Tape subsystem debugging options.
541 See Documentation/ftape.txt.
542
543 gamecon.map[2|3]=
544 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
545 support via parallel port (up to 5 devices per port)
546 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
547 See also Documentation/input/joystick-parport.txt
548
549 gamma= [HW,DRM]
550
551 gdth= [HW,SCSI]
552 See header of drivers/scsi/gdth.c.
553
554 gpt [EFI] Forces disk with valid GPT signature but
555 invalid Protective MBR to be treated as GPT.
556
557 gscd= [HW,CD]
558 Format: <io>
559
560 gt96100eth= [NET] MIPS GT96100 Advanced Communication Controller
561
562 gus= [HW,OSS]
563 Format: <io>,<irq>,<dma>,<dma16>
a9913044 564
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565 gvp11= [HW,SCSI]
566
567 hashdist= [KNL,NUMA] Large hashes allocated during boot
568 are distributed across NUMA nodes. Defaults on
569 for IA-64, off otherwise.
a9913044 570 Format: 0 | 1 (for off | on)
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571
572 hcl= [IA-64] SGI's Hardware Graph compatibility layer
573
574 hd= [EIDE] (E)IDE hard drive subsystem geometry
575 Format: <cyl>,<head>,<sect>
576
577 hd?= [HW] (E)IDE subsystem
578 hd?lun= See Documentation/ide.txt.
579
580 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
581 size of <nn>. This works even on boxes that have no
582 highmem otherwise. This also works to reduce highmem
583 size on bigger boxes.
584
585 hisax= [HW,ISDN]
586 See Documentation/isdn/README.HiSax.
587
588 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
589
590 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
591
592 i8042.direct [HW] Put keyboard port into non-translated mode
593 i8042.dumbkbd [HW] Pretend that controlled can only read data from
594 keyboard and can not control its state
595 (Don't attempt to blink the leds)
596 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 597 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
598 i8042.nomux [HW] Don't check presence of an active multiplexing
599 controller
600 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
601 controllers
602 i8042.panicblink=
603 [HW] Frequency with which keyboard LEDs should blink
604 when kernel panics (default is 0.5 sec)
605 i8042.reset [HW] Reset the controller during init and cleanup
606 i8042.unlock [HW] Unlock (ignore) the keylock
607
608 i810= [HW,DRM]
609
e70c9d5e
DT
610 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
611 indicates that the driver is running on unsupported
612 hardware.
1da177e4
LT
613 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
614 does not match list of supported models.
615 i8k.power_status
616 [HW] Report power status in /proc/i8k
617 (disabled by default)
618 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
619 capability is set.
620
621 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
622 See Documentation/mca.txt.
623
624 icn= [HW,ISDN]
625 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
626
627 ide= [HW] (E)IDE subsystem
628 Format: ide=nodma or ide=doubler or ide=reverse
629 See Documentation/ide.txt.
630
631 ide?= [HW] (E)IDE subsystem
632 Format: ide?=noprobe or chipset specific parameters.
633 See Documentation/ide.txt.
a9913044 634
1da177e4
LT
635 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
636 See Documentation/ide.txt.
637
638 idle= [HW]
639 Format: idle=poll or idle=halt
a9913044 640
1da177e4
LT
641 ihash_entries= [KNL]
642 Set number of hash buckets for inode cache.
643
644 in2000= [HW,SCSI]
645 See header of drivers/scsi/in2000.c.
646
647 init= [KNL]
648 Format: <full_path>
649 Run specified binary instead of /sbin/init as init
650 process.
651
652 initcall_debug [KNL] Trace initcalls as they are executed. Useful
653 for working out where the kernel is dying during
654 startup.
655
656 initrd= [BOOT] Specify the location of the initial ramdisk
657
658 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
659 Format: <irq>
660
2bd0fa3b
JB
661 combined_mode= [HW] control which driver uses IDE ports in combined
662 mode: legacy IDE driver, libata, or both
663 (in the libata case, libata.atapi_enabled=1 may be
664 useful as well). Note that using the ide or libata
665 options may affect your device naming (e.g. by
666 changing hdc to sdb).
667 Format: combined (default), ide, or libata
668
1da177e4
LT
669 inttest= [IA64]
670
671 io7= [HW] IO7 for Marvel based alpha systems
672 See comment before marvel_specify_io7 in
673 arch/alpha/kernel/core_marvel.c.
674
675 ip= [IP_PNP]
676 See Documentation/nfsroot.txt.
677
678 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
679 See comment before ip2_setup() in drivers/char/ip2.c.
680
681 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
682 See header of drivers/scsi/ips.c.
683
200803df
AC
684 irqfixup [HW]
685 When an interrupt is not handled search all handlers
686 for it. Intended to get systems with badly broken
687 firmware running.
688
689 irqpoll [HW]
690 When an interrupt is not handled search all handlers
691 for it. Also check all handlers each timer
692 interrupt. Intended to get systems with badly broken
693 firmware running.
694
1da177e4 695 isapnp= [ISAPNP]
a9913044 696 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
697
698 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
699 Format: <cpu number>,...,<cpu number>
700 This option can be used to specify one or more CPUs
701 to isolate from the general SMP balancing and scheduling
702 algorithms. The only way to move a process onto or off
703 an "isolated" CPU is via the CPU affinity syscalls.
704 <cpu number> begins at 0 and the maximum value is
705 "number of CPUs in system - 1".
706
707 This option is the preferred way to isolate CPUs. The
a9913044
RD
708 alternative -- manually setting the CPU mask of all
709 tasks in the system -- can cause problems and
710 suboptimal load balancer performance.
1da177e4
LT
711
712 isp16= [HW,CD]
713 Format: <io>,<irq>,<dma>,<setup>
714
a9913044 715 iucv= [HW,NET]
1da177e4
LT
716
717 js= [HW,JOY] Analog joystick
718 See Documentation/input/joystick.txt.
719
720 keepinitrd [HW,ARM]
721
a9913044 722 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
723 in oops dumps.
724
725 l2cr= [PPC]
726
a9913044
RD
727 lapic [IA-32,APIC] Enable the local APIC even if BIOS
728 disabled it.
1da177e4
LT
729
730 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
731 Format: addr:<io>,irq:<irq>
732
a9913044
RD
733 llsc*= [IA64] See function print_params() in
734 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
735
736 load_ramdisk= [RAM] List of ramdisks to load from floppy
737 See Documentation/ramdisk.txt.
738
a6b25b67
RD
739 lockd.nlm_grace_period=P [NFS] Assign grace period.
740 Format: <integer>
1da177e4 741
a6b25b67
RD
742 lockd.nlm_tcpport=N [NFS] Assign TCP port.
743 Format: <integer>
744
745 lockd.nlm_timeout=T [NFS] Assign timeout value.
746 Format: <integer>
747
748 lockd.nlm_udpport=M [NFS] Assign UDP port.
749 Format: <integer>
1da177e4
LT
750
751 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
752 Format: <irq>
753
754 loglevel= All Kernel Messages with a loglevel smaller than the
755 console loglevel will be printed to the console. It can
756 also be changed with klogd or other programs. The
757 loglevels are defined as follows:
758
759 0 (KERN_EMERG) system is unusable
760 1 (KERN_ALERT) action must be taken immediately
761 2 (KERN_CRIT) critical conditions
762 3 (KERN_ERR) error conditions
763 4 (KERN_WARNING) warning conditions
764 5 (KERN_NOTICE) normal but significant condition
765 6 (KERN_INFO) informational
766 7 (KERN_DEBUG) debug-level messages
767
768 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
769 Format: { n | nk | nM }
770 n must be a power of two. The default size
771 is set in the kernel config file.
1da177e4
LT
772
773 lp=0 [LP] Specify parallel ports to use, e.g,
774 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
775 lp=reset first parallel port). 'lp=0' disables the
776 lp=auto printer driver. 'lp=reset' (which can be
777 specified in addition to the ports) causes
778 attached printers to be reset. Using
779 lp=port1,port2,... specifies the parallel ports
780 to associate lp devices with, starting with
781 lp0. A port specification may be 'none' to skip
782 that lp device, or a parport name such as
783 'parport0'. Specifying 'lp=auto' instead of a
784 port specification list means that device IDs
785 from each port should be examined, to see if
786 an IEEE 1284-compliant printer is attached; if
787 so, the driver will manage that printer.
788 See also header of drivers/char/lp.c.
789
790 lpj=n [KNL]
791 Sets loops_per_jiffy to given constant, thus avoiding
792 time-consuming boot-time autodetection (up to 250 ms per
793 CPU). 0 enables autodetection (default). To determine
794 the correct value for your kernel, boot with normal
795 autodetection and see what value is printed. Note that
796 on SMP systems the preset will be applied to all CPUs,
797 which is likely to cause problems if your CPUs need
798 significantly divergent settings. An incorrect value
799 will cause delays in the kernel to be wrong, leading to
800 unpredictable I/O errors and other breakage. Although
801 unlikely, in the extreme case this might damage your
802 hardware.
803
804 ltpc= [NET]
805 Format: <io>,<irq>,<dma>
806
a9913044
RD
807 mac5380= [HW,SCSI] Format:
808 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 809
a9913044
RD
810 mac53c9x= [HW,SCSI] Format:
811 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 812
a9913044
RD
813 machvec= [IA64] Force the use of a particular machine-vector
814 (machvec) in a generic kernel.
815 Example: machvec=hpzx1_swiotlb
1da177e4 816
a9913044
RD
817 mad16= [HW,OSS] Format:
818 <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
1da177e4
LT
819
820 maui= [HW,OSS]
821 Format: <io>,<irq>
a9913044
RD
822
823 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
824 be mounted
825 Format: <1-256>
826
827 maxcpus= [SMP] Maximum number of processors that an SMP kernel
828 should make use of
829
2b2c3750
BP
830 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
831 equal to this physical address is ignored.
832
a9913044 833 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
834 Should be between 1 and 2^32-1.
835
836 max_report_luns=
a9913044 837 [SCSI] Maximum number of LUNs received.
1da177e4
LT
838 Should be between 1 and 16384.
839
840 mca-pentium [BUGS=IA-32]
841
842 mcatest= [IA-64]
843
844 mcd= [HW,CD]
845 Format: <port>,<irq>,<mitsumi_bug_93_wait>
846
847 mcdx= [HW,CD]
848
849 mce [IA-32] Machine Check Exception
850
851 md= [HW] RAID subsystems devices and level
852 See Documentation/md.txt.
a9913044 853
1da177e4
LT
854 mdacon= [MDA]
855 Format: <first>,<last>
856 Specifies range of consoles to be captured by the MDA.
a9913044 857
1da177e4
LT
858 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
859 Amount of memory to be used when the kernel is not able
860 to see the whole system memory or for test.
861 [IA-32] Use together with memmap= to avoid physical
862 address space collisions. Without memmap= PCI devices
863 could be placed at addresses belonging to unused RAM.
864
865 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
866 memory.
867
69cda7b1 868 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
869 E820 memory map, as specified by the user.
870 Such memmap=exactmap lines can be constructed based on
871 BIOS output or other requirements. See the memmap=nn@ss
872 option description.
873
874 memmap=nn[KMG]@ss[KMG]
875 [KNL] Force usage of a specific region of memory
876 Region of memory to be used, from ss to ss+nn.
877
878 memmap=nn[KMG]#ss[KMG]
879 [KNL,ACPI] Mark specific memory as ACPI data.
880 Region of memory to be used, from ss to ss+nn.
881
882 memmap=nn[KMG]$ss[KMG]
883 [KNL,ACPI] Mark specific memory as reserved.
884 Region of memory to be used, from ss to ss+nn.
885
886 meye.*= [HW] Set MotionEye Camera parameters
887 See Documentation/video4linux/meye.txt.
888
889 mga= [HW,DRM]
890
198e2f18 891 migration_cost=
892 [KNL,SMP] debug: override scheduler migration costs
893 Format: <level-1-usecs>,<level-2-usecs>,...
894 This debugging option can be used to override the
895 default scheduler migration cost matrix. The numbers
896 are indexed by 'CPU domain distance'.
897 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
898 box will set up an intra-core migration cost of
899 1 msec, an inter-core migration cost of 2 msecs,
900 and an inter-node migration cost of 3 msecs.
901
902 WARNING: using the wrong values here can break
903 scheduler performance, so it's only for scheduler
904 development purposes, not production environments.
905
906 migration_debug=
907 [KNL,SMP] migration cost auto-detect verbosity
908 Format=<0|1|2>
909 If a system's migration matrix reported at bootup
910 seems erroneous then this option can be used to
911 increase verbosity of the detection process.
912 We default to 0 (no extra messages), 1 will print
913 some more information, and 2 will be really
914 verbose (probably only useful if you also have a
915 serial console attached to the system).
916
917 migration_factor=
918 [KNL,SMP] multiply/divide migration costs by a factor
919 Format=<percent>
920 This debug option can be used to proportionally
921 increase or decrease the auto-detected migration
922 costs for all entries of the migration matrix.
923 E.g. migration_factor=150 will increase migration
924 costs by 50%. (and thus the scheduler will be less
925 eager migrating cache-hot tasks)
926 migration_factor=80 will decrease migration costs
927 by 20%. (thus the scheduler will be more eager to
928 migrate tasks)
929
930 WARNING: using the wrong values here can break
931 scheduler performance, so it's only for scheduler
932 development purposes, not production environments.
933
1da177e4
LT
934 mousedev.tap_time=
935 [MOUSE] Maximum time between finger touching and
936 leaving touchpad surface for touch to be considered
937 a tap and be reported as a left button click (for
938 touchpads working in absolute mode only).
939 Format: <msecs>
940 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
941 reporting absolute coordinates, such as tablets
942 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
943 reporting absolute coordinates, such as tablets
944
945 mpu401= [HW,OSS]
946 Format: <io>,<irq>
947
948 MTD_Partition= [MTD]
949 Format: <name>,<region-number>,<size>,<offset>
950
a9913044
RD
951 MTD_Region= [MTD] Format:
952 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
953
954 mtdparts= [MTD]
955 See drivers/mtd/cmdline.c.
956
957 mtouchusb.raw_coordinates=
a9913044
RD
958 [HW] Make the MicroTouch USB driver use raw coordinates
959 ('y', default) or cooked coordinates ('n')
1da177e4
LT
960
961 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
962
963 NCR_D700= [HW,SCSI]
964 See header of drivers/scsi/NCR_D700.c.
965
966 ncr5380= [HW,SCSI]
967
968 ncr53c400= [HW,SCSI]
969
970 ncr53c400a= [HW,SCSI]
971
972 ncr53c406a= [HW,SCSI]
973
974 ncr53c8xx= [HW,SCSI]
975
976 netdev= [NET] Network devices parameters
977 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
978 Note that mem_start is often overloaded to mean
979 something different and driver-specific.
a9913044
RD
980 This usage is only documented in each driver source
981 file if at all.
982
1da177e4
LT
983 nfsaddrs= [NFS]
984 See Documentation/nfsroot.txt.
985
986 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
987 See Documentation/nfsroot.txt.
988
a72b4422
TM
989 nfs.callback_tcpport=
990 [NFS] set the TCP port on which the NFSv4 callback
991 channel should listen.
992
58df095b
TM
993 nfs.idmap_cache_timeout=
994 [NFS] set the maximum lifetime for idmapper cache
995 entries.
996
1da177e4
LT
997 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
998
999 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1000 emulation library even if a 387 maths coprocessor
1001 is present.
1002
a9913044
RD
1003 noalign [KNL,ARM]
1004
1da177e4
LT
1005 noapic [SMP,APIC] Tells the kernel to not make use of any
1006 IOAPICs that may be present in the system.
1007
1008 noasync [HW,M68K] Disables async and sync negotiation for
1009 all devices.
1010
1011 nobats [PPC] Do not use BATs for mapping kernel lowmem
1012 on "Classic" PPC cores.
1013
1014 nocache [ARM]
a9913044 1015
1da177e4
LT
1016 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1017
1018 noexec [IA-64]
1019
a9913044 1020 noexec [IA-32,X86-64]
1da177e4
LT
1021 noexec=on: enable non-executable mappings (default)
1022 noexec=off: disable nn-executable mappings
1023
4f886511
CE
1024 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1025 register save and restore. The kernel will only save
1026 legacy floating-point registers on task switch.
1da177e4
LT
1027
1028 nohlt [BUGS=ARM]
a9913044 1029
1da177e4
LT
1030 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1031 instruction doesn't work correctly and not to
1032 use it.
1033
1034 nohalt [IA-64] Tells the kernel not to use the power saving
1035 function PAL_HALT_LIGHT when idle. This increases
1036 power-consumption. On the positive side, it reduces
1037 interrupt wake-up latency, which may improve performance
1038 in certain environments such as networked servers or
1039 real-time systems.
1040
1041 noirqdebug [IA-32] Disables the code which attempts to detect and
1042 disable unhandled interrupt sources.
1043
1044 noisapnp [ISAPNP] Disables ISA PnP code.
1045
1046 noinitrd [RAM] Tells the kernel not to load any configured
1047 initial RAM disk.
1048
1049 nointroute [IA-64]
1050
1051 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1052
1053 noltlbs [PPC] Do not use large page/tlb entries for kernel
1054 lowmem mapping on PPC40x.
1055
312f1f01
H
1056 nomca [IA-64] Disable machine check abort handling
1057
abe37e5a
H
1058 nomce [IA-32] Machine Check Exception
1059
1da177e4
LT
1060 noresidual [PPC] Don't use residual data on PReP machines.
1061
a9913044
RD
1062 noresume [SWSUSP] Disables resume and restores original swap
1063 space.
1064
1da177e4
LT
1065 no-scroll [VGA] Disables scrollback.
1066 This is required for the Braillex ib80-piezo Braille
1067 reader made by F.H. Papenmeier (Germany).
1068
1069 nosbagart [IA-64]
1070
4f886511
CE
1071 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1072
1da177e4
LT
1073 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1074
1075 nosync [HW,M68K] Disables sync negotiation for all devices.
1076
1077 notsc [BUGS=IA-32] Disable Time Stamp Counter
1078
1079 nousb [USB] Disable the USB subsystem
1080
1081 nowb [ARM]
a9913044 1082
a61c2d78
DJ
1083 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1084
1da177e4
LT
1085 opl3= [HW,OSS]
1086 Format: <io>
1087
1088 opl3sa= [HW,OSS]
1089 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1090
a9913044
RD
1091 opl3sa2= [HW,OSS] Format:
1092 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1093
1da177e4
LT
1094 oprofile.timer= [HW]
1095 Use timer interrupt instead of performance counters
1096
1097 optcd= [HW,CD]
1098 Format: <io>
1099
1100 osst= [HW,SCSI] SCSI Tape Driver
1101 Format: <buffer_size>,<write_threshold>
1102 See also Documentation/scsi/st.txt.
1103
1104 panic= [KNL] Kernel behaviour on panic
1105 Format: <timeout>
1106
1107 parkbd.port= [HW] Parallel port number the keyboard adapter is
1108 connected to, default is 0.
1109 Format: <parport#>
1110 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1111 0 for XT, 1 for AT (default is AT).
a9913044
RD
1112 Format: <mode>
1113
1114 parport= [HW,PPT] Specify parallel ports. 0 disables.
1115 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1116 Use 'auto' to force the driver to use any
1117 IRQ/DMA settings detected (the default is to
1118 ignore detected IRQ/DMA settings because of
1119 possible conflicts). You can specify the base
1120 address, IRQ, and DMA settings; IRQ and DMA
1121 should be numbers, or 'auto' (for using detected
1122 settings on that particular port), or 'nofifo'
1123 (to avoid using a FIFO even if it is detected).
1124 Parallel ports are assigned in the order they
1125 are specified on the command line, starting
1126 with parport0.
1127
1128 parport_init_mode= [HW,PPT]
1129 Configure VIA parallel port to operate in
1130 a specific mode. This is necessary on Pegasos
1131 computer where firmware has no options for setting
1132 up parallel port mode and sets it to spp.
1133 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1134 Format: [spp|ps2|epp|ecp|ecpepp]
1135
a9913044
RD
1136 pas2= [HW,OSS] Format:
1137 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1138
1da177e4
LT
1139 pas16= [HW,SCSI]
1140 See header of drivers/scsi/pas16.c.
1141
dd287796
AM
1142 pause_on_oops=
1143 Halt all CPUs after the first oops has been printed for
1144 the specified number of seconds. This is to be used if
1145 your oopses keep scrolling off the screen.
1146
1da177e4
LT
1147 pcbit= [HW,ISDN]
1148
1149 pcd. [PARIDE]
1150 See header of drivers/block/paride/pcd.c.
1151 See also Documentation/paride.txt.
1152
a9913044
RD
1153 pci=option[,option...] [PCI] various PCI subsystem options:
1154 off [IA-32] don't probe for the PCI bus
1155 bios [IA-32] force use of PCI BIOS, don't access
1156 the hardware directly. Use this if your machine
1157 has a non-standard PCI host bridge.
1158 nobios [IA-32] disallow use of PCI BIOS, only direct
1159 hardware access methods are allowed. Use this
1160 if you experience crashes upon bootup and you
1161 suspect they are caused by the BIOS.
1162 conf1 [IA-32] Force use of PCI Configuration
1163 Mechanism 1.
1164 conf2 [IA-32] Force use of PCI Configuration
1165 Mechanism 2.
61be6d66
BH
1166 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1167 Configuration
309e57df
MW
1168 nomsi [MSI] If the PCI_MSI kernel config parameter is
1169 enabled, this kernel boot option can be used to
1170 disable the use of MSI interrupts system-wide.
a9913044
RD
1171 nosort [IA-32] Don't sort PCI devices according to
1172 order given by the PCI BIOS. This sorting is
1173 done to get a device order compatible with
1174 older kernels.
1175 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1176 routing table. These calls are known to be buggy
1177 on several machines and they hang the machine
1178 when used, but on other computers it's the only
1179 way to get the interrupt routing table. Try
1180 this option if the kernel is unable to allocate
1181 IRQs or discover secondary PCI buses on your
1182 motherboard.
1183 rom [IA-32] Assign address space to expansion ROMs.
1184 Use with caution as certain devices share
1185 address decoders between ROMs and other
1186 resources.
1187 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1188 assigned automatically to PCI devices. You can
1189 make the kernel exclude IRQs of your ISA cards
1190 this way.
120bb424 1191 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1192 of the PIRQ table (normally generated
1193 by the BIOS) if it is outside the
1194 F0000h-100000h range.
1195 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1196 useful if the kernel is unable to find your
1197 secondary buses and you want to tell it
1198 explicitly which ones they are.
1199 assign-busses [IA-32] Always assign all PCI bus
1200 numbers ourselves, overriding
1201 whatever the firmware may have done.
1202 usepirqmask [IA-32] Honor the possible IRQ mask stored
1203 in the BIOS $PIR table. This is needed on
1204 some systems with broken BIOSes, notably
1205 some HP Pavilion N5400 and Omnibook XE3
1206 notebooks. This will have no effect if ACPI
1207 IRQ routing is enabled.
1208 noacpi [IA-32] Do not use ACPI for IRQ routing
1209 or for PCI scanning.
1210 routeirq Do IRQ routing for all PCI devices.
1211 This is normally done in pci_enable_device(),
1212 so this option is a temporary workaround
1213 for broken drivers that don't call it.
1214 firmware [ARM] Do not re-enumerate the bus but instead
1215 just use the configuration from the
1216 bootloader. This is currently used on
1217 IXP2000 systems where the bus has to be
1218 configured a certain way for adjunct CPUs.
1da177e4
LT
1219
1220 pcmv= [HW,PCMCIA] BadgePAD 4
1221
1222 pd. [PARIDE]
1223 See Documentation/paride.txt.
1224
1225 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1226 boot time.
1227 Format: { 0 | 1 }
1228 See arch/parisc/kernel/pdc_chassis.c
1229
1230 pf. [PARIDE]
1231 See Documentation/paride.txt.
1232
1233 pg. [PARIDE]
1234 See Documentation/paride.txt.
1235
1236 pirq= [SMP,APIC] Manual mp-table setup
1237 See Documentation/i386/IO-APIC.txt.
1238
1239 plip= [PPT,NET] Parallel port network link
1240 Format: { parport<nr> | timid | 0 }
1241 See also Documentation/parport.txt.
1242
1243 pnpacpi= [ACPI]
1244 { off }
1245
1246 pnpbios= [ISAPNP]
1247 { on | off | curr | res | no-curr | no-res }
1248
1249 pnp_reserve_irq=
1250 [ISAPNP] Exclude IRQs for the autoconfiguration
1251
1252 pnp_reserve_dma=
1253 [ISAPNP] Exclude DMAs for the autoconfiguration
1254
1255 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1256 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1257
1258 pnp_reserve_mem=
a9913044
RD
1259 [ISAPNP] Exclude memory regions for the
1260 autoconfiguration.
1da177e4
LT
1261 Ranges are in pairs (memory base and size).
1262
1263 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1264 Format: [schedule,]<number>
1265 Param: "schedule" - profile schedule points.
1266 Param: <number> - step/bucket size as a power of 2 for
1267 statistical time based profiling.
1da177e4 1268
a9913044 1269 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1270 Limit processor to maximum C-state
1271 max_cstate=9 overrides any DMI blacklist limit.
1272
41c0d868
LB
1273 processor.nocst [HW,ACPI]
1274 Ignore the _CST method to determine C-states,
1275 instead using the legacy FADT method
1276
1da177e4
LT
1277 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1278 before loading.
1279 See Documentation/ramdisk.txt.
1280
a9913044
RD
1281 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1282 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1283 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1284 per second.
a9913044
RD
1285 psmouse.resetafter= [HW,MOUSE]
1286 Try to reset the device after so many bad packets
1da177e4
LT
1287 (0 = never).
1288 psmouse.resolution=
1289 [HW,MOUSE] Set desired mouse resolution, in dpi.
1290 psmouse.smartscroll=
a9913044 1291 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1292 0 = disabled, 1 = enabled (default).
1293
1294 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1295 Format:
1296 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1297
1298 pt. [PARIDE]
1299 See Documentation/paride.txt.
1300
1301 quiet= [KNL] Disable log messages
a9913044 1302
1da177e4
LT
1303 r128= [HW,DRM]
1304
1305 raid= [HW,RAID]
1306 See Documentation/md.txt.
1307
1308 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1309 See Documentation/ramdisk.txt.
1310
a9913044 1311 ramdisk_blocksize= [RAM]
1da177e4 1312 See Documentation/ramdisk.txt.
a9913044 1313
1da177e4
LT
1314 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1315 New name for the ramdisk parameter.
1316 See Documentation/ramdisk.txt.
1317
21a1ea9e
DS
1318 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1319 RCU callbacks to process in one batch.
1320
1321 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1322 RCU callbacks over which batch limiting is disabled.
1323
1324 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1325 RCU callbacks below which batch limiting is re-enabled.
1326
1327 rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
1328 RCU callbacks to queued before forcing reschedule
1329 on all cpus.
1330
ffdfc409
OJ
1331 rdinit= [KNL]
1332 Format: <full_path>
1333 Run specified binary instead of /init from the ramdisk,
1334 used for early userspace startup. See initrd.
1335
1da177e4
LT
1336 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1337 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1338 See arch/*/kernel/reboot.c.
1339
1340 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1341
a9913044
RD
1342 resume= [SWSUSP]
1343 Specify the partition device for software suspend
1da177e4
LT
1344
1345 rhash_entries= [KNL,NET]
1346 Set number of hash buckets for route cache
1347
1348 riscom8= [HW,SERIAL]
1349 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1350
1351 ro [KNL] Mount root device read-only on boot
1352
1353 root= [KNL] Root filesystem
1354
1355 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1356 mount the root filesystem
1357
1358 rootflags= [KNL] Set root filesystem mount option string
1359
1360 rootfstype= [KNL] Set root filesystem type
1361
1362 rw [KNL] Mount root device read-write on boot
1363
1364 S [KNL] Run init in single mode
1365
1366 sa1100ir [NET]
1367 See drivers/net/irda/sa1100_ir.c.
1368
1369 sb= [HW,OSS]
1370 Format: <io>,<irq>,<dma>,<dma2>
1371
1372 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1373
1da177e4
LT
1374 sbpcd= [HW,CD] Soundblaster CD adapter
1375 Format: <io>,<type>
1376 See a comment before function sbpcd_setup() in
1377 drivers/cdrom/sbpcd.c.
1378
1379 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1380 Format: <io>[,<timeout>[,<isapnp>]]
1381
1382 scsi_debug_*= [SCSI]
1383 See drivers/scsi/scsi_debug.c.
1384
1385 scsi_default_dev_flags=
1386 [SCSI] SCSI default device flags
1387 Format: <integer>
1388
1389 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1390 Format: <vendor>:<model>:<flags>
1391 (flags are integer value)
1392
1393 scsi_logging= [SCSI]
1394
1395 selinux [SELINUX] Disable or enable SELinux at boot time.
1396 Format: { "0" | "1" }
1397 See security/selinux/Kconfig help text.
1398 0 -- disable.
1399 1 -- enable.
1400 Default value is set via kernel config option.
1401 If enabled at boot time, /selinux/disable can be used
1402 later to disable prior to initial policy load.
1403
1404 serialnumber [BUGS=IA-32]
1405
a9913044
RD
1406 sg_def_reserved_size= [SCSI]
1407
1da177e4
LT
1408 sgalaxy= [HW,OSS]
1409 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1410
1411 shapers= [NET]
1412 Maximal number of shapers.
a9913044 1413
1da177e4
LT
1414 sim710= [SCSI,HW]
1415 See header of drivers/scsi/sim710.c.
1416
1417 simeth= [IA-64]
1418 simscsi=
a9913044 1419
1da177e4
LT
1420 sjcd= [HW,CD]
1421 Format: <io>,<irq>,<dma>
1422 See header of drivers/cdrom/sjcd.c.
1423
1424 slram= [HW,MTD]
1425
1426 smart2= [HW]
1427 Format: <io1>[,<io2>[,...,<io8>]]
1428
1429 snd-ad1816a= [HW,ALSA]
1430
1431 snd-ad1848= [HW,ALSA]
1432
1433 snd-ali5451= [HW,ALSA]
1434
1435 snd-als100= [HW,ALSA]
1436
1437 snd-als4000= [HW,ALSA]
1438
1439 snd-azt2320= [HW,ALSA]
1440
1441 snd-cmi8330= [HW,ALSA]
1442
1443 snd-cmipci= [HW,ALSA]
1444
1445 snd-cs4231= [HW,ALSA]
1446
1447 snd-cs4232= [HW,ALSA]
1448
1449 snd-cs4236= [HW,ALSA]
1450
1451 snd-cs4281= [HW,ALSA]
1452
1453 snd-cs46xx= [HW,ALSA]
1454
1455 snd-dt019x= [HW,ALSA]
1456
1457 snd-dummy= [HW,ALSA]
1458
1459 snd-emu10k1= [HW,ALSA]
1460
1461 snd-ens1370= [HW,ALSA]
1462
1463 snd-ens1371= [HW,ALSA]
1464
1465 snd-es968= [HW,ALSA]
1466
1467 snd-es1688= [HW,ALSA]
1468
1469 snd-es18xx= [HW,ALSA]
1470
1471 snd-es1938= [HW,ALSA]
1472
1473 snd-es1968= [HW,ALSA]
1474
1475 snd-fm801= [HW,ALSA]
1476
1477 snd-gusclassic= [HW,ALSA]
1478
1479 snd-gusextreme= [HW,ALSA]
1480
1481 snd-gusmax= [HW,ALSA]
1482
1483 snd-hdsp= [HW,ALSA]
1484
1485 snd-ice1712= [HW,ALSA]
1486
1487 snd-intel8x0= [HW,ALSA]
1488
1489 snd-interwave= [HW,ALSA]
1490
1491 snd-interwave-stb=
1492 [HW,ALSA]
1493
1494 snd-korg1212= [HW,ALSA]
1495
1496 snd-maestro3= [HW,ALSA]
1497
1498 snd-mpu401= [HW,ALSA]
1499
1500 snd-mtpav= [HW,ALSA]
1501
1502 snd-nm256= [HW,ALSA]
1503
1504 snd-opl3sa2= [HW,ALSA]
1505
1506 snd-opti92x-ad1848=
1507 [HW,ALSA]
1508
1509 snd-opti92x-cs4231=
1510 [HW,ALSA]
1511
1512 snd-opti93x= [HW,ALSA]
1513
1514 snd-pmac= [HW,ALSA]
1515
1516 snd-rme32= [HW,ALSA]
1517
1518 snd-rme96= [HW,ALSA]
1519
1520 snd-rme9652= [HW,ALSA]
1521
1522 snd-sb8= [HW,ALSA]
1523
1524 snd-sb16= [HW,ALSA]
1525
1526 snd-sbawe= [HW,ALSA]
1527
1528 snd-serial= [HW,ALSA]
1529
1530 snd-sgalaxy= [HW,ALSA]
1531
1532 snd-sonicvibes= [HW,ALSA]
1533
1534 snd-sun-amd7930=
1535 [HW,ALSA]
1536
1537 snd-sun-cs4231= [HW,ALSA]
1538
1539 snd-trident= [HW,ALSA]
1540
1541 snd-usb-audio= [HW,ALSA,USB]
1542
1543 snd-via82xx= [HW,ALSA]
1544
1545 snd-virmidi= [HW,ALSA]
1546
1547 snd-wavefront= [HW,ALSA]
1548
1549 snd-ymfpci= [HW,ALSA]
a9913044 1550
1da177e4
LT
1551 sonicvibes= [HW,OSS]
1552 Format: <reverb>
a9913044 1553
1da177e4
LT
1554 sonycd535= [HW,CD]
1555 Format: <io>[,<irq>]
1556
1557 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1558 See Documentation/sonypi.txt
1559
1560 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1561 See Documentation/specialix.txt.
1562
1563 spia_io_base= [HW,MTD]
1564 spia_fio_base=
1565 spia_pedr=
1566 spia_peddr=
1567
1568 sscape= [HW,OSS]
1569 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1570
1da177e4
LT
1571 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1572 See Documentation/scsi/st.txt.
1573
1574 st0x= [HW,SCSI]
1575 See header of drivers/scsi/seagate.c.
1576
1577 sti= [PARISC,HW]
1578 Format: <num>
1579 Set the STI (builtin display/keyboard on the HP-PARISC
1580 machines) console (graphic card) which should be used
1581 as the initial boot-console.
1582 See also comment in drivers/video/console/sticore.c.
1583
1584 sti_font= [HW]
1585 See comment in drivers/video/console/sticore.c.
1586
1587 stifb= [HW]
1588 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1589
1da177e4 1590 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1591
1da177e4
LT
1592 switches= [HW,M68k]
1593
1594 sym53c416= [HW,SCSI]
1595 See header of drivers/scsi/sym53c416.c.
1596
1597 t128= [HW,SCSI]
1598 See header of drivers/scsi/t128.c.
1599
1600 tdfx= [HW,DRM]
1601
1602 thash_entries= [KNL,NET]
1603 Set number of hash buckets for TCP connection
1604
1605 time Show timing data prefixed to each printk message line
1606
1607 tipar.timeout= [HW,PPT]
1608 Set communications timeout in tenths of a second
1609 (default 15).
1610
1611 tipar.delay= [HW,PPT]
1612 Set inter-bit delay in microseconds (default 10).
1613
1614 tmc8xx= [HW,SCSI]
1615 See header of drivers/scsi/seagate.c.
1616
1617 tmscsim= [HW,SCSI]
1618 See comment before function dc390_setup() in
1619 drivers/scsi/tmscsim.c.
1620
1621 tp720= [HW,PS2]
1622
1623 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1624 Format:
1625 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1626
1da177e4
LT
1627 tsdev.xres= [TS] Horizontal screen resolution.
1628 tsdev.yres= [TS] Vertical screen resolution.
1629
a9913044
RD
1630 turbografx.map[2|3]= [HW,JOY]
1631 TurboGraFX parallel port interface
1632 Format:
1633 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1634 See also Documentation/input/joystick-parport.txt
1635
1636 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1637 See header of drivers/scsi/u14-34f.c.
1638
1639 uart401= [HW,OSS]
1640 Format: <io>,<irq>
1641
1642 uart6850= [HW,OSS]
1643 Format: <io>,<irq>
1644
1da177e4
LT
1645 usbhid.mousepoll=
1646 [USBHID] The interval which mice are to be polled at.
a9913044 1647
1da177e4
LT
1648 video= [FB] Frame buffer configuration
1649 See Documentation/fb/modedb.txt.
1650
1651 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1652 See Documentation/i386/boot.txt and
1653 Documentation/svga.txt.
1da177e4
LT
1654 Use vga=ask for menu.
1655 This is actually a boot loader parameter; the value is
1656 passed to the kernel using a special protocol.
1657
a9913044 1658 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1659 size of <nn>. This can be used to increase the
1660 minimum size (128MB on x86). It can also be used to
1661 decrease the size and leave more room for directly
1662 mapped kernel RAM.
1663
1664 vmhalt= [KNL,S390]
1665
a9913044
RD
1666 vmpoff= [KNL,S390]
1667
1da177e4
LT
1668 waveartist= [HW,OSS]
1669 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1670
1da177e4
LT
1671 wd33c93= [HW,SCSI]
1672 See header of drivers/scsi/wd33c93.c.
1673
1674 wd7000= [HW,SCSI]
1675 See header of drivers/scsi/wd7000.c.
1676
1677 wdt= [WDT] Watchdog
1678 See Documentation/watchdog/watchdog.txt.
1679
1680 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1681 xd_geo= See header of drivers/block/xd.c.
1682
1683 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1684 Format:
1685 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1686
a62eaf15
AK
1687 norandmaps Don't use address space randomization
1688 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1689
1da177e4 1690
a9913044 1691______________________________________________________________________
1da177e4
LT
1692
1693TODO:
1694
1695 Add documentation for ALSA options.
1696 Add more DRM drivers.