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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
9c4751fd 113The number of kernel parameters is not limited, but the length of the
114complete command line (parameters including spaces etc.) is limited to
115a fixed number of characters. This limit depends on the architecture
116and is between 256 and 4096 characters. It is defined in the file
117./include/asm/setup.h as COMMAND_LINE_SIZE.
118
119
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120 53c7xx= [HW,SCSI] Amiga SCSI controllers
121 See header of drivers/scsi/53c7xx.c.
122 See also Documentation/scsi/ncr53c7xx.txt.
123
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124 acpi= [HW,ACPI] Advanced Configuration and Power Interface
125 Format: { force | off | ht | strict | noirq }
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126 force -- enable ACPI if default was off
127 off -- disable ACPI if default was on
128 noirq -- do not use ACPI for IRQ routing
129 ht -- run only enough ACPI to enable Hyper Threading
a9913044 130 strict -- Be less tolerant of platforms that are not
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131 strictly ACPI specification compliant.
132
133 See also Documentation/pm.txt, pci=noacpi
134
135 acpi_sleep= [HW,ACPI] Sleep options
136 Format: { s3_bios, s3_mode }
137 See Documentation/power/video.txt
a9913044 138
1da177e4 139 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 140 Format: { level | edge | high | low }
1da177e4 141
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142 acpi_irq_balance [HW,ACPI]
143 ACPI will balance active IRQs
144 default in APIC mode
1da177e4 145
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146 acpi_irq_nobalance [HW,ACPI]
147 ACPI will not move active IRQs (default)
148 default in PIC mode
1da177e4 149
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150 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
151 use by PCI
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152 Format: <irq>,<irq>...
153
a9913044 154 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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155 Format: <irq>,<irq>...
156
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157 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
158 Format: To spoof as Windows 98: ="Microsoft Windows"
159
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160 acpi_osi= [HW,ACPI] empty param disables _OSI
161
162 acpi_serialize [HW,ACPI] force serialization of AML methods
163
164 acpi_skip_timer_override [HW,ACPI]
165 Recognize and ignore IRQ0/pin2 Interrupt Override.
166 For broken nForce2 BIOS resulting in XT-PIC timer.
167
168 acpi_dbg_layer= [HW,ACPI]
169 Format: <int>
a9913044 170 Each bit of the <int> indicates an ACPI debug layer,
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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_layer.
174
175 acpi_dbg_level= [HW,ACPI]
176 Format: <int>
a9913044 177 Each bit of the <int> indicates an ACPI debug level,
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178 1: enable, 0: disable. It is useful for boot time
179 debugging. After system has booted up, it can be set
180 via /proc/acpi/debug_level.
181
182 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
183
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184 acpi_generic_hotkey [HW,ACPI]
185 Allow consolidated generic hotkey driver to
a9913044 186 override platform specific driver.
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187 See also Documentation/acpi-hotkey.txt.
188
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189 acpi_pm_good [IA-32,X86-64]
190 Override the pmtimer bug detection: force the kernel
191 to assume that this machine's pmtimer latches its value
192 and always returns good values.
193
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194 enable_timer_pin_1 [i386,x86-64]
195 Enable PIN 1 of APIC timer
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196 Can be useful to work around chipset bugs
197 (in particular on some ATI chipsets).
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198 The kernel tries to set a reasonable default.
199
200 disable_timer_pin_1 [i386,x86-64]
201 Disable PIN 1 of APIC timer
202 Can be useful to work around chipset bugs.
203
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204 ad1816= [HW,OSS]
205 Format: <io>,<irq>,<dma>,<dma2>
206 See also Documentation/sound/oss/AD1816.
207
208 ad1848= [HW,OSS]
209 Format: <io>,<irq>,<dma>,<dma2>,<type>
210
211 adlib= [HW,OSS]
212 Format: <io>
a9913044 213
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214 advansys= [HW,SCSI]
215 See header of drivers/scsi/advansys.c.
216
217 advwdt= [HW,WDT] Advantech WDT
218 Format: <iostart>,<iostop>
219
220 aedsp16= [HW,OSS] Audio Excel DSP 16
221 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
222 See also header of sound/oss/aedsp16.c.
a9913044 223
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224 aha152x= [HW,SCSI]
225 See Documentation/scsi/aha152x.txt.
226
227 aha1542= [HW,SCSI]
228 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
229
230 aic7xxx= [HW,SCSI]
231 See Documentation/scsi/aic7xxx.txt.
232
233 aic79xx= [HW,SCSI]
234 See Documentation/scsi/aic79xx.txt.
235
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236 amijoy.map= [HW,JOY] Amiga joystick support
237 Map of devices attached to JOY0DAT and JOY1DAT
238 Format: <a>,<b>
239 See also Documentation/kernel/input/joystick.txt
240
241 analog.map= [HW,JOY] Analog joystick and gamepad support
242 Specifies type or capabilities of an analog joystick
243 connected to one of 16 gameports
244 Format: <type1>,<type2>,..<type16>
245
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246 apc= [HW,SPARC]
247 Power management functions (SPARCstation-4/5 + deriv.)
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248 Format: noidle
249 Disable APC CPU standby support. SPARCstation-Fox does
250 not play well with APC CPU idle - disable it if you have
251 APC and your system crashes randomly.
252
a9913044 253 apic= [APIC,i386] Change the output verbosity whilst booting
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254 Format: { quiet (default) | verbose | debug }
255 Change the amount of debugging information output
256 when initialising the APIC and IO-APIC components.
a9913044 257
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258 apm= [APM] Advanced Power Management
259 See header of arch/i386/kernel/apm.c.
260
261 applicom= [HW]
262 Format: <mem>,<irq>
a9913044 263
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264 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
265 Format: <io>,<irq>,<nodeID>
266
267 ataflop= [HW,M68k]
268
269 atarimouse= [HW,MOUSE] Atari Mouse
270
271 atascsi= [HW,SCSI] Atari SCSI
272
273 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
274 EzKey and similar keyboards
275
276 atkbd.reset= [HW] Reset keyboard during initialization
277
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278 atkbd.set= [HW] Select keyboard code set
279 Format: <int> (2 = AT (default), 3 = PS/2)
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280
281 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
282 keyboards
283
284 atkbd.softraw= [HW] Choose between synthetic and real raw mode
285 Format: <bool> (0 = real, 1 = synthetic (default))
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286
287 atkbd.softrepeat= [HW]
288 Use software keyboard repeat
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289
290 autotest [IA64]
291
292 awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
293 Format: <io>,<memsize>,<isapnp>
a9913044 294
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295 aztcd= [HW,CD] Aztech CD268 CDROM driver
296 Format: <io>,0x79 (?)
297
298 baycom_epp= [HW,AX25]
299 Format: <io>,<mode>
a9913044 300
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301 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
302 Format: <io>,<mode>
303 See header of drivers/net/hamradio/baycom_par.c.
304
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305 baycom_ser_fdx= [HW,AX25]
306 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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307 Format: <io>,<irq>,<mode>[,<baud>]
308 See header of drivers/net/hamradio/baycom_ser_fdx.c.
309
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310 baycom_ser_hdx= [HW,AX25]
311 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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312 Format: <io>,<irq>,<mode>
313 See header of drivers/net/hamradio/baycom_ser_hdx.c.
314
315 blkmtd_device= [HW,MTD]
316 blkmtd_erasesz=
317 blkmtd_ro=
318 blkmtd_bs=
319 blkmtd_count=
320
321 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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322 bttv.radio= Most important insmod options are available as
323 kernel args too.
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324 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
325 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
326
327 BusLogic= [HW,SCSI]
328 See drivers/scsi/BusLogic.c, comment before function
329 BusLogic_ParseDriverOptions().
330
331 c101= [NET] Moxa C101 synchronous serial card
332
333 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
334 Sometimes CPU hardware bugs make them report the cache
335 size incorrectly. The kernel will attempt work arounds
336 to fix known problems, but for some CPUs it is not
337 possible to determine what the correct size should be.
338 This option provides an override for these situations.
339
340 cdu31a= [HW,CD]
341 Format: <io>,<irq>[,PAS]
342 See header of drivers/cdrom/cdu31a.c.
343
344 chandev= [HW,NET] Generic channel device initialisation
345
346 checkreqprot [SELINUX] Set initial checkreqprot flag value.
347 Format: { "0" | "1" }
348 See security/selinux/Kconfig help text.
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349 0 -- check protection applied by kernel (includes
350 any implied execute protection).
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351 1 -- check protection requested by application.
352 Default value is set via a kernel config option.
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353 Value can be changed at runtime via
354 /selinux/checkreqprot.
355
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356 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
357 [Deprecated]
3f6dee9b 358 Forces specified clocksource (if available) to be used
734efb46 359 when calculating gettimeofday(). If specified
3f6dee9b 360 clocksource is not available, it defaults to PIT.
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361 Format: { pit | tsc | cyclone | pmtmr }
362
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363 disable_8254_timer
364 enable_8254_timer
365 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
366 over the 8254 in addition to over the IO-APIC. The
367 kernel tries to set a sensible default.
368
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369 hpet= [IA-32,HPET] option to disable HPET and use PIT.
370 Format: disable
371
372 cm206= [HW,CD]
373 Format: { auto | [<io>,][<irq>] }
374
375 com20020= [HW,NET] ARCnet - COM20020 chipset
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376 Format:
377 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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378
379 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
380 Format: <io>[,<irq>]
381
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382 com90xx= [HW,NET]
383 ARCnet - COM90xx chipset (memory-mapped buffers)
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384 Format: <io>[,<irq>[,<memstart>]]
385
386 condev= [HW,S390] console device
387 conmode=
a9913044 388
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389 console= [KNL] Output console device and options.
390
391 tty<n> Use the virtual console device <n>.
392
393 ttyS<n>[,options]
f1a1c2dc 394 ttyUSB0[,options]
1da177e4 395 Use the specified serial port. The options are of
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396 the form "bbbbpnf", where "bbbb" is the baud rate,
397 "p" is parity ("n", "o", or "e"), "n" is number of
398 bits, and "f" is flow control ("r" for RTS or
399 omit it). Default is "9600n8".
400
401 See Documentation/serial-console.txt for more
402 information. See
403 Documentation/networking/netconsole.txt for an
404 alternative.
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405
406 uart,io,<addr>[,options]
407 uart,mmio,<addr>[,options]
408 Start an early, polled-mode console on the 8250/16550
409 UART at the specified I/O port or MMIO address,
410 switching to the matching ttyS device later. The
411 options are the same as for ttyS, above.
412
413 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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414 Format:
415 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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416
417 cpia_pp= [HW,PPT]
418 Format: { parport<nr> | auto | none }
419
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420 crashkernel=nn[KMG]@ss[KMG]
421 [KNL] Reserve a chunk of physical memory to
422 hold a kernel to switch to with kexec on panic.
423
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424 cs4232= [HW,OSS]
425 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
426
427 cs89x0_dma= [HW,NET]
428 Format: <dma>
429
430 cs89x0_media= [HW,NET]
431 Format: { rj45 | aui | bnc }
a9913044 432
1da177e4 433 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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434
435 dasd= [HW,NET]
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436 See header of drivers/s390/block/dasd_devmap.c.
437
438 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
439 (one device per port)
440 Format: <port#>,<type>
441 See also Documentation/input/joystick-parport.txt
442
443 debug [KNL] Enable kernel debugging (events log level).
444
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445 debug_locks_verbose=
446 [KNL] verbose self-tests
447 Format=<0|1>
448 Print debugging info while doing the locking API
449 self-tests.
450 We default to 0 (no extra messages), setting it to
451 1 will print _a lot_ more information - normally
452 only useful to kernel developers.
453
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454 decnet= [HW,NET]
455 Format: <area>[,<node>]
456 See also Documentation/networking/decnet.txt.
457
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458 dhash_entries= [KNL]
459 Set number of hash buckets for dentry cache.
a9913044 460
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461 digi= [HW,SERIAL]
462 IO parameters + enable/disable command.
463
464 digiepca= [HW,SERIAL]
465 See drivers/char/README.epca and
466 Documentation/digiepca.txt.
467
468 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
469 support available.
470 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
471
472 dmasound= [HW,OSS] Sound subsystem buffers
473
474 dscc4.setup= [NET]
475
476 dtc3181e= [HW,SCSI]
477
a9913044 478 earlyprintk= [IA-32,X86-64]
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479 earlyprintk=vga
480 earlyprintk=serial[,ttySn[,baudrate]]
481
a9913044 482 Append ",keep" to not disable it when the real console
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483 takes over.
484
485 Only vga or serial at a time, not both.
486
487 Currently only ttyS0 and ttyS1 are supported.
488
489 Interaction with the standard serial driver is not
490 very good.
491
492 The VGA output is eventually overwritten by the real
493 console.
494
495 eata= [HW,SCSI]
496
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497 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
498 Format: <int>
499 0: polling mode
500 non-0: interrupt mode (default)
501
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502 eda= [HW,PS2]
503
504 edb= [HW,PS2]
505
506 edd= [EDD]
507 Format: {"of[f]" | "sk[ipmbr]"}
508 See comment in arch/i386/boot/edd.S
509
a9913044 510 eicon= [HW,ISDN]
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511 Format: <id>,<membase>,<irq>
512
513 eisa_irq_edge= [PARISC,HW]
514 See header of drivers/parisc/eisa.c.
515
516 elanfreq= [IA-32]
517 See comment before function elanfreq_setup() in
518 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
519
520 elevator= [IOSCHED]
16ab3adf 521 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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522 See Documentation/block/as-iosched.txt and
523 Documentation/block/deadline-iosched.txt for details.
524
aac04b32 525 elfcorehdr= [IA-32, X86_64]
a9913044 526 Specifies physical address of start of kernel core
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527 image elf header. Generally kexec loader will
528 pass this option to capture kernel.
529 See Documentation/kdump/kdump.txt for details.
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530
531 enforcing [SELINUX] Set initial enforcing status.
532 Format: {"0" | "1"}
533 See security/selinux/Kconfig help text.
534 0 -- permissive (log only, no denials).
535 1 -- enforcing (deny and log).
536 Default value is 0.
537 Value can be changed at runtime via /selinux/enforce.
538
539 es1370= [HW,OSS]
540 Format: <lineout>[,<micbias>]
541 See also header of sound/oss/es1370.c.
542
543 es1371= [HW,OSS]
544 Format: <spdif>,[<nomix>,[<amplifier>]]
545 See also header of sound/oss/es1371.c.
a9913044 546
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547 ether= [HW,NET] Ethernet cards parameters
548 This option is obsoleted by the "netdev=" option, which
549 has equivalent usage. See its documentation for details.
550
551 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
552 Format: <io>[,<irq>]
553
554 fd_mcs= [HW,SCSI]
555 See header of drivers/scsi/fd_mcs.c.
556
557 fdomain= [HW,SCSI]
558 See header of drivers/scsi/fdomain.c.
559
560 floppy= [HW]
561 See Documentation/floppy.txt.
562
563 ftape= [HW] Floppy Tape subsystem debugging options.
564 See Documentation/ftape.txt.
565
566 gamecon.map[2|3]=
567 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
568 support via parallel port (up to 5 devices per port)
569 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
570 See also Documentation/input/joystick-parport.txt
571
572 gamma= [HW,DRM]
573
574 gdth= [HW,SCSI]
575 See header of drivers/scsi/gdth.c.
576
577 gpt [EFI] Forces disk with valid GPT signature but
578 invalid Protective MBR to be treated as GPT.
579
580 gscd= [HW,CD]
581 Format: <io>
582
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583 gus= [HW,OSS]
584 Format: <io>,<irq>,<dma>,<dma16>
a9913044 585
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586 gvp11= [HW,SCSI]
587
588 hashdist= [KNL,NUMA] Large hashes allocated during boot
589 are distributed across NUMA nodes. Defaults on
590 for IA-64, off otherwise.
a9913044 591 Format: 0 | 1 (for off | on)
1da177e4
LT
592
593 hcl= [IA-64] SGI's Hardware Graph compatibility layer
594
595 hd= [EIDE] (E)IDE hard drive subsystem geometry
596 Format: <cyl>,<head>,<sect>
597
598 hd?= [HW] (E)IDE subsystem
599 hd?lun= See Documentation/ide.txt.
600
601 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
602 size of <nn>. This works even on boxes that have no
603 highmem otherwise. This also works to reduce highmem
604 size on bigger boxes.
605
606 hisax= [HW,ISDN]
607 See Documentation/isdn/README.HiSax.
608
609 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
610
611 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
612
613 i8042.direct [HW] Put keyboard port into non-translated mode
614 i8042.dumbkbd [HW] Pretend that controlled can only read data from
615 keyboard and can not control its state
616 (Don't attempt to blink the leds)
617 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 618 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
619 i8042.nomux [HW] Don't check presence of an active multiplexing
620 controller
621 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
622 controllers
623 i8042.panicblink=
624 [HW] Frequency with which keyboard LEDs should blink
625 when kernel panics (default is 0.5 sec)
626 i8042.reset [HW] Reset the controller during init and cleanup
627 i8042.unlock [HW] Unlock (ignore) the keylock
628
629 i810= [HW,DRM]
630
e70c9d5e
DT
631 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
632 indicates that the driver is running on unsupported
633 hardware.
1da177e4
LT
634 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
635 does not match list of supported models.
636 i8k.power_status
637 [HW] Report power status in /proc/i8k
638 (disabled by default)
639 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
640 capability is set.
641
642 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
643 See Documentation/mca.txt.
644
645 icn= [HW,ISDN]
646 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
647
648 ide= [HW] (E)IDE subsystem
649 Format: ide=nodma or ide=doubler or ide=reverse
650 See Documentation/ide.txt.
651
652 ide?= [HW] (E)IDE subsystem
653 Format: ide?=noprobe or chipset specific parameters.
654 See Documentation/ide.txt.
a9913044 655
1da177e4
LT
656 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
657 See Documentation/ide.txt.
658
659 idle= [HW]
660 Format: idle=poll or idle=halt
a9913044 661
1da177e4
LT
662 ihash_entries= [KNL]
663 Set number of hash buckets for inode cache.
664
665 in2000= [HW,SCSI]
666 See header of drivers/scsi/in2000.c.
667
668 init= [KNL]
669 Format: <full_path>
670 Run specified binary instead of /sbin/init as init
671 process.
672
673 initcall_debug [KNL] Trace initcalls as they are executed. Useful
674 for working out where the kernel is dying during
675 startup.
676
677 initrd= [BOOT] Specify the location of the initial ramdisk
678
679 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
680 Format: <irq>
681
2bd0fa3b
JB
682 combined_mode= [HW] control which driver uses IDE ports in combined
683 mode: legacy IDE driver, libata, or both
684 (in the libata case, libata.atapi_enabled=1 may be
685 useful as well). Note that using the ide or libata
686 options may affect your device naming (e.g. by
687 changing hdc to sdb).
688 Format: combined (default), ide, or libata
689
1da177e4
LT
690 inttest= [IA64]
691
692 io7= [HW] IO7 for Marvel based alpha systems
693 See comment before marvel_specify_io7 in
694 arch/alpha/kernel/core_marvel.c.
695
696 ip= [IP_PNP]
697 See Documentation/nfsroot.txt.
698
699 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
700 See comment before ip2_setup() in drivers/char/ip2.c.
701
702 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
703 See header of drivers/scsi/ips.c.
704
72c4a13a
SH
705 ports= [IP_VS_FTP] IPVS ftp helper module
706 Default is 21.
707 Up to 8 (IP_VS_APP_MAX_PORTS) ports
708 may be specified.
709 Format: <port>,<port>....
710
200803df
AC
711 irqfixup [HW]
712 When an interrupt is not handled search all handlers
713 for it. Intended to get systems with badly broken
714 firmware running.
715
716 irqpoll [HW]
717 When an interrupt is not handled search all handlers
718 for it. Also check all handlers each timer
719 interrupt. Intended to get systems with badly broken
720 firmware running.
721
1da177e4 722 isapnp= [ISAPNP]
a9913044 723 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
724
725 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
726 Format: <cpu number>,...,<cpu number>
727 This option can be used to specify one or more CPUs
728 to isolate from the general SMP balancing and scheduling
729 algorithms. The only way to move a process onto or off
730 an "isolated" CPU is via the CPU affinity syscalls.
731 <cpu number> begins at 0 and the maximum value is
732 "number of CPUs in system - 1".
733
734 This option is the preferred way to isolate CPUs. The
a9913044
RD
735 alternative -- manually setting the CPU mask of all
736 tasks in the system -- can cause problems and
737 suboptimal load balancer performance.
1da177e4
LT
738
739 isp16= [HW,CD]
740 Format: <io>,<irq>,<dma>,<setup>
741
a9913044 742 iucv= [HW,NET]
1da177e4
LT
743
744 js= [HW,JOY] Analog joystick
745 See Documentation/input/joystick.txt.
746
747 keepinitrd [HW,ARM]
748
a9913044 749 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
750 in oops dumps.
751
752 l2cr= [PPC]
753
a9913044
RD
754 lapic [IA-32,APIC] Enable the local APIC even if BIOS
755 disabled it.
1da177e4
LT
756
757 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
758 Format: addr:<io>,irq:<irq>
759
a9913044
RD
760 llsc*= [IA64] See function print_params() in
761 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
762
763 load_ramdisk= [RAM] List of ramdisks to load from floppy
764 See Documentation/ramdisk.txt.
765
a6b25b67
RD
766 lockd.nlm_grace_period=P [NFS] Assign grace period.
767 Format: <integer>
1da177e4 768
a6b25b67
RD
769 lockd.nlm_tcpport=N [NFS] Assign TCP port.
770 Format: <integer>
771
772 lockd.nlm_timeout=T [NFS] Assign timeout value.
773 Format: <integer>
774
775 lockd.nlm_udpport=M [NFS] Assign UDP port.
776 Format: <integer>
1da177e4
LT
777
778 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
779 Format: <irq>
780
781 loglevel= All Kernel Messages with a loglevel smaller than the
782 console loglevel will be printed to the console. It can
783 also be changed with klogd or other programs. The
784 loglevels are defined as follows:
785
786 0 (KERN_EMERG) system is unusable
787 1 (KERN_ALERT) action must be taken immediately
788 2 (KERN_CRIT) critical conditions
789 3 (KERN_ERR) error conditions
790 4 (KERN_WARNING) warning conditions
791 5 (KERN_NOTICE) normal but significant condition
792 6 (KERN_INFO) informational
793 7 (KERN_DEBUG) debug-level messages
794
795 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
796 Format: { n | nk | nM }
797 n must be a power of two. The default size
798 is set in the kernel config file.
1da177e4
LT
799
800 lp=0 [LP] Specify parallel ports to use, e.g,
801 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
802 lp=reset first parallel port). 'lp=0' disables the
803 lp=auto printer driver. 'lp=reset' (which can be
804 specified in addition to the ports) causes
805 attached printers to be reset. Using
806 lp=port1,port2,... specifies the parallel ports
807 to associate lp devices with, starting with
808 lp0. A port specification may be 'none' to skip
809 that lp device, or a parport name such as
810 'parport0'. Specifying 'lp=auto' instead of a
811 port specification list means that device IDs
812 from each port should be examined, to see if
813 an IEEE 1284-compliant printer is attached; if
814 so, the driver will manage that printer.
815 See also header of drivers/char/lp.c.
816
817 lpj=n [KNL]
818 Sets loops_per_jiffy to given constant, thus avoiding
819 time-consuming boot-time autodetection (up to 250 ms per
820 CPU). 0 enables autodetection (default). To determine
821 the correct value for your kernel, boot with normal
822 autodetection and see what value is printed. Note that
823 on SMP systems the preset will be applied to all CPUs,
824 which is likely to cause problems if your CPUs need
825 significantly divergent settings. An incorrect value
826 will cause delays in the kernel to be wrong, leading to
827 unpredictable I/O errors and other breakage. Although
828 unlikely, in the extreme case this might damage your
829 hardware.
830
831 ltpc= [NET]
832 Format: <io>,<irq>,<dma>
833
a9913044
RD
834 mac5380= [HW,SCSI] Format:
835 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 836
a9913044
RD
837 mac53c9x= [HW,SCSI] Format:
838 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 839
a9913044
RD
840 machvec= [IA64] Force the use of a particular machine-vector
841 (machvec) in a generic kernel.
842 Example: machvec=hpzx1_swiotlb
1da177e4 843
a9913044
RD
844 mad16= [HW,OSS] Format:
845 <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
1da177e4
LT
846
847 maui= [HW,OSS]
848 Format: <io>,<irq>
a9913044
RD
849
850 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
851 be mounted
852 Format: <1-256>
853
854 maxcpus= [SMP] Maximum number of processors that an SMP kernel
855 should make use of
856
2b2c3750
BP
857 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
858 equal to this physical address is ignored.
859
a9913044 860 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
861 Should be between 1 and 2^32-1.
862
863 max_report_luns=
a9913044 864 [SCSI] Maximum number of LUNs received.
1da177e4
LT
865 Should be between 1 and 16384.
866
867 mca-pentium [BUGS=IA-32]
868
869 mcatest= [IA-64]
870
871 mcd= [HW,CD]
872 Format: <port>,<irq>,<mitsumi_bug_93_wait>
873
874 mcdx= [HW,CD]
875
876 mce [IA-32] Machine Check Exception
877
878 md= [HW] RAID subsystems devices and level
879 See Documentation/md.txt.
a9913044 880
1da177e4
LT
881 mdacon= [MDA]
882 Format: <first>,<last>
883 Specifies range of consoles to be captured by the MDA.
a9913044 884
1da177e4
LT
885 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
886 Amount of memory to be used when the kernel is not able
887 to see the whole system memory or for test.
888 [IA-32] Use together with memmap= to avoid physical
889 address space collisions. Without memmap= PCI devices
890 could be placed at addresses belonging to unused RAM.
891
892 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
893 memory.
894
69cda7b1 895 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
896 E820 memory map, as specified by the user.
897 Such memmap=exactmap lines can be constructed based on
898 BIOS output or other requirements. See the memmap=nn@ss
899 option description.
900
901 memmap=nn[KMG]@ss[KMG]
902 [KNL] Force usage of a specific region of memory
903 Region of memory to be used, from ss to ss+nn.
904
905 memmap=nn[KMG]#ss[KMG]
906 [KNL,ACPI] Mark specific memory as ACPI data.
907 Region of memory to be used, from ss to ss+nn.
908
909 memmap=nn[KMG]$ss[KMG]
910 [KNL,ACPI] Mark specific memory as reserved.
911 Region of memory to be used, from ss to ss+nn.
912
913 meye.*= [HW] Set MotionEye Camera parameters
914 See Documentation/video4linux/meye.txt.
915
916 mga= [HW,DRM]
917
198e2f18 918 migration_cost=
919 [KNL,SMP] debug: override scheduler migration costs
920 Format: <level-1-usecs>,<level-2-usecs>,...
921 This debugging option can be used to override the
922 default scheduler migration cost matrix. The numbers
923 are indexed by 'CPU domain distance'.
924 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
925 box will set up an intra-core migration cost of
926 1 msec, an inter-core migration cost of 2 msecs,
927 and an inter-node migration cost of 3 msecs.
928
929 WARNING: using the wrong values here can break
930 scheduler performance, so it's only for scheduler
931 development purposes, not production environments.
932
933 migration_debug=
934 [KNL,SMP] migration cost auto-detect verbosity
935 Format=<0|1|2>
936 If a system's migration matrix reported at bootup
937 seems erroneous then this option can be used to
938 increase verbosity of the detection process.
939 We default to 0 (no extra messages), 1 will print
940 some more information, and 2 will be really
941 verbose (probably only useful if you also have a
942 serial console attached to the system).
943
944 migration_factor=
945 [KNL,SMP] multiply/divide migration costs by a factor
946 Format=<percent>
947 This debug option can be used to proportionally
948 increase or decrease the auto-detected migration
949 costs for all entries of the migration matrix.
950 E.g. migration_factor=150 will increase migration
951 costs by 50%. (and thus the scheduler will be less
952 eager migrating cache-hot tasks)
953 migration_factor=80 will decrease migration costs
954 by 20%. (thus the scheduler will be more eager to
955 migrate tasks)
956
957 WARNING: using the wrong values here can break
958 scheduler performance, so it's only for scheduler
959 development purposes, not production environments.
960
1da177e4
LT
961 mousedev.tap_time=
962 [MOUSE] Maximum time between finger touching and
963 leaving touchpad surface for touch to be considered
964 a tap and be reported as a left button click (for
965 touchpads working in absolute mode only).
966 Format: <msecs>
967 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
968 reporting absolute coordinates, such as tablets
969 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
970 reporting absolute coordinates, such as tablets
971
972 mpu401= [HW,OSS]
973 Format: <io>,<irq>
974
975 MTD_Partition= [MTD]
976 Format: <name>,<region-number>,<size>,<offset>
977
a9913044
RD
978 MTD_Region= [MTD] Format:
979 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
980
981 mtdparts= [MTD]
982 See drivers/mtd/cmdline.c.
983
984 mtouchusb.raw_coordinates=
a9913044
RD
985 [HW] Make the MicroTouch USB driver use raw coordinates
986 ('y', default) or cooked coordinates ('n')
1da177e4
LT
987
988 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
989
990 NCR_D700= [HW,SCSI]
991 See header of drivers/scsi/NCR_D700.c.
992
993 ncr5380= [HW,SCSI]
994
995 ncr53c400= [HW,SCSI]
996
997 ncr53c400a= [HW,SCSI]
998
999 ncr53c406a= [HW,SCSI]
1000
1001 ncr53c8xx= [HW,SCSI]
1002
1003 netdev= [NET] Network devices parameters
1004 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1005 Note that mem_start is often overloaded to mean
1006 something different and driver-specific.
a9913044
RD
1007 This usage is only documented in each driver source
1008 file if at all.
1009
1da177e4
LT
1010 nfsaddrs= [NFS]
1011 See Documentation/nfsroot.txt.
1012
1013 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1014 See Documentation/nfsroot.txt.
1015
a72b4422
TM
1016 nfs.callback_tcpport=
1017 [NFS] set the TCP port on which the NFSv4 callback
1018 channel should listen.
1019
58df095b
TM
1020 nfs.idmap_cache_timeout=
1021 [NFS] set the maximum lifetime for idmapper cache
1022 entries.
1023
1da177e4
LT
1024 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1025
1026 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1027 emulation library even if a 387 maths coprocessor
1028 is present.
1029
a9913044
RD
1030 noalign [KNL,ARM]
1031
1da177e4
LT
1032 noapic [SMP,APIC] Tells the kernel to not make use of any
1033 IOAPICs that may be present in the system.
1034
1035 noasync [HW,M68K] Disables async and sync negotiation for
1036 all devices.
1037
1038 nobats [PPC] Do not use BATs for mapping kernel lowmem
1039 on "Classic" PPC cores.
1040
1041 nocache [ARM]
a9913044 1042
163ecdff
SN
1043 nodelayacct [KNL] Disable per-task delay accounting
1044
1da177e4
LT
1045 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1046
1047 noexec [IA-64]
1048
a9913044 1049 noexec [IA-32,X86-64]
1da177e4
LT
1050 noexec=on: enable non-executable mappings (default)
1051 noexec=off: disable nn-executable mappings
1052
4f886511
CE
1053 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1054 register save and restore. The kernel will only save
1055 legacy floating-point registers on task switch.
1da177e4
LT
1056
1057 nohlt [BUGS=ARM]
a9913044 1058
1da177e4
LT
1059 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1060 instruction doesn't work correctly and not to
1061 use it.
1062
1063 nohalt [IA-64] Tells the kernel not to use the power saving
1064 function PAL_HALT_LIGHT when idle. This increases
1065 power-consumption. On the positive side, it reduces
1066 interrupt wake-up latency, which may improve performance
1067 in certain environments such as networked servers or
1068 real-time systems.
1069
1070 noirqdebug [IA-32] Disables the code which attempts to detect and
1071 disable unhandled interrupt sources.
1072
1073 noisapnp [ISAPNP] Disables ISA PnP code.
1074
1075 noinitrd [RAM] Tells the kernel not to load any configured
1076 initial RAM disk.
1077
1078 nointroute [IA-64]
1079
1080 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1081
1082 noltlbs [PPC] Do not use large page/tlb entries for kernel
1083 lowmem mapping on PPC40x.
1084
312f1f01
H
1085 nomca [IA-64] Disable machine check abort handling
1086
abe37e5a
H
1087 nomce [IA-32] Machine Check Exception
1088
1da177e4
LT
1089 noresidual [PPC] Don't use residual data on PReP machines.
1090
a9913044
RD
1091 noresume [SWSUSP] Disables resume and restores original swap
1092 space.
1093
1da177e4
LT
1094 no-scroll [VGA] Disables scrollback.
1095 This is required for the Braillex ib80-piezo Braille
1096 reader made by F.H. Papenmeier (Germany).
1097
1098 nosbagart [IA-64]
1099
4f886511
CE
1100 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1101
1da177e4
LT
1102 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1103
1104 nosync [HW,M68K] Disables sync negotiation for all devices.
1105
1106 notsc [BUGS=IA-32] Disable Time Stamp Counter
1107
1108 nousb [USB] Disable the USB subsystem
1109
1110 nowb [ARM]
a9913044 1111
a61c2d78
DJ
1112 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1113
1da177e4
LT
1114 opl3= [HW,OSS]
1115 Format: <io>
1116
1117 opl3sa= [HW,OSS]
1118 Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
1119
a9913044
RD
1120 opl3sa2= [HW,OSS] Format:
1121 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1122
1da177e4
LT
1123 oprofile.timer= [HW]
1124 Use timer interrupt instead of performance counters
1125
1126 optcd= [HW,CD]
1127 Format: <io>
1128
1129 osst= [HW,SCSI] SCSI Tape Driver
1130 Format: <buffer_size>,<write_threshold>
1131 See also Documentation/scsi/st.txt.
1132
1133 panic= [KNL] Kernel behaviour on panic
1134 Format: <timeout>
1135
1136 parkbd.port= [HW] Parallel port number the keyboard adapter is
1137 connected to, default is 0.
1138 Format: <parport#>
1139 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1140 0 for XT, 1 for AT (default is AT).
a9913044
RD
1141 Format: <mode>
1142
1143 parport= [HW,PPT] Specify parallel ports. 0 disables.
1144 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1145 Use 'auto' to force the driver to use any
1146 IRQ/DMA settings detected (the default is to
1147 ignore detected IRQ/DMA settings because of
1148 possible conflicts). You can specify the base
1149 address, IRQ, and DMA settings; IRQ and DMA
1150 should be numbers, or 'auto' (for using detected
1151 settings on that particular port), or 'nofifo'
1152 (to avoid using a FIFO even if it is detected).
1153 Parallel ports are assigned in the order they
1154 are specified on the command line, starting
1155 with parport0.
1156
1157 parport_init_mode= [HW,PPT]
1158 Configure VIA parallel port to operate in
1159 a specific mode. This is necessary on Pegasos
1160 computer where firmware has no options for setting
1161 up parallel port mode and sets it to spp.
1162 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1163 Format: [spp|ps2|epp|ecp|ecpepp]
1164
a9913044
RD
1165 pas2= [HW,OSS] Format:
1166 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1167
1da177e4
LT
1168 pas16= [HW,SCSI]
1169 See header of drivers/scsi/pas16.c.
1170
dd287796
AM
1171 pause_on_oops=
1172 Halt all CPUs after the first oops has been printed for
1173 the specified number of seconds. This is to be used if
1174 your oopses keep scrolling off the screen.
1175
1da177e4
LT
1176 pcbit= [HW,ISDN]
1177
1178 pcd. [PARIDE]
1179 See header of drivers/block/paride/pcd.c.
1180 See also Documentation/paride.txt.
1181
a9913044
RD
1182 pci=option[,option...] [PCI] various PCI subsystem options:
1183 off [IA-32] don't probe for the PCI bus
1184 bios [IA-32] force use of PCI BIOS, don't access
1185 the hardware directly. Use this if your machine
1186 has a non-standard PCI host bridge.
1187 nobios [IA-32] disallow use of PCI BIOS, only direct
1188 hardware access methods are allowed. Use this
1189 if you experience crashes upon bootup and you
1190 suspect they are caused by the BIOS.
1191 conf1 [IA-32] Force use of PCI Configuration
1192 Mechanism 1.
1193 conf2 [IA-32] Force use of PCI Configuration
1194 Mechanism 2.
61be6d66
BH
1195 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1196 Configuration
309e57df
MW
1197 nomsi [MSI] If the PCI_MSI kernel config parameter is
1198 enabled, this kernel boot option can be used to
1199 disable the use of MSI interrupts system-wide.
a9913044
RD
1200 nosort [IA-32] Don't sort PCI devices according to
1201 order given by the PCI BIOS. This sorting is
1202 done to get a device order compatible with
1203 older kernels.
1204 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1205 routing table. These calls are known to be buggy
1206 on several machines and they hang the machine
1207 when used, but on other computers it's the only
1208 way to get the interrupt routing table. Try
1209 this option if the kernel is unable to allocate
1210 IRQs or discover secondary PCI buses on your
1211 motherboard.
1212 rom [IA-32] Assign address space to expansion ROMs.
1213 Use with caution as certain devices share
1214 address decoders between ROMs and other
1215 resources.
1216 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1217 assigned automatically to PCI devices. You can
1218 make the kernel exclude IRQs of your ISA cards
1219 this way.
120bb424 1220 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1221 of the PIRQ table (normally generated
1222 by the BIOS) if it is outside the
1223 F0000h-100000h range.
1224 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1225 useful if the kernel is unable to find your
1226 secondary buses and you want to tell it
1227 explicitly which ones they are.
1228 assign-busses [IA-32] Always assign all PCI bus
1229 numbers ourselves, overriding
1230 whatever the firmware may have done.
1231 usepirqmask [IA-32] Honor the possible IRQ mask stored
1232 in the BIOS $PIR table. This is needed on
1233 some systems with broken BIOSes, notably
1234 some HP Pavilion N5400 and Omnibook XE3
1235 notebooks. This will have no effect if ACPI
1236 IRQ routing is enabled.
1237 noacpi [IA-32] Do not use ACPI for IRQ routing
1238 or for PCI scanning.
1239 routeirq Do IRQ routing for all PCI devices.
1240 This is normally done in pci_enable_device(),
1241 so this option is a temporary workaround
1242 for broken drivers that don't call it.
1243 firmware [ARM] Do not re-enumerate the bus but instead
1244 just use the configuration from the
1245 bootloader. This is currently used on
1246 IXP2000 systems where the bus has to be
1247 configured a certain way for adjunct CPUs.
0637a70a
AK
1248 noearly [X86] Don't do any early type 1 scanning.
1249 This might help on some broken boards which
1250 machine check when some devices' config space
1251 is read. But various workarounds are disabled
1252 and some IOMMU drivers will not work.
1da177e4
LT
1253 pcmv= [HW,PCMCIA] BadgePAD 4
1254
1255 pd. [PARIDE]
1256 See Documentation/paride.txt.
1257
1258 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1259 boot time.
1260 Format: { 0 | 1 }
1261 See arch/parisc/kernel/pdc_chassis.c
1262
1263 pf. [PARIDE]
1264 See Documentation/paride.txt.
1265
1266 pg. [PARIDE]
1267 See Documentation/paride.txt.
1268
1269 pirq= [SMP,APIC] Manual mp-table setup
1270 See Documentation/i386/IO-APIC.txt.
1271
1272 plip= [PPT,NET] Parallel port network link
1273 Format: { parport<nr> | timid | 0 }
1274 See also Documentation/parport.txt.
1275
1276 pnpacpi= [ACPI]
1277 { off }
1278
1279 pnpbios= [ISAPNP]
1280 { on | off | curr | res | no-curr | no-res }
1281
1282 pnp_reserve_irq=
1283 [ISAPNP] Exclude IRQs for the autoconfiguration
1284
1285 pnp_reserve_dma=
1286 [ISAPNP] Exclude DMAs for the autoconfiguration
1287
1288 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1289 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1290
1291 pnp_reserve_mem=
a9913044
RD
1292 [ISAPNP] Exclude memory regions for the
1293 autoconfiguration.
1da177e4
LT
1294 Ranges are in pairs (memory base and size).
1295
1296 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1297 Format: [schedule,]<number>
1298 Param: "schedule" - profile schedule points.
1299 Param: <number> - step/bucket size as a power of 2 for
1300 statistical time based profiling.
1da177e4 1301
a9913044 1302 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1303 Limit processor to maximum C-state
1304 max_cstate=9 overrides any DMI blacklist limit.
1305
41c0d868
LB
1306 processor.nocst [HW,ACPI]
1307 Ignore the _CST method to determine C-states,
1308 instead using the legacy FADT method
1309
1da177e4
LT
1310 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1311 before loading.
1312 See Documentation/ramdisk.txt.
1313
a9913044
RD
1314 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1315 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1316 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1317 per second.
a9913044
RD
1318 psmouse.resetafter= [HW,MOUSE]
1319 Try to reset the device after so many bad packets
1da177e4
LT
1320 (0 = never).
1321 psmouse.resolution=
1322 [HW,MOUSE] Set desired mouse resolution, in dpi.
1323 psmouse.smartscroll=
a9913044 1324 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1325 0 = disabled, 1 = enabled (default).
1326
1327 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1328 Format:
1329 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1330
1331 pt. [PARIDE]
1332 See Documentation/paride.txt.
1333
7d2c502f 1334 quiet [KNL] Disable most log messages
a9913044 1335
1da177e4
LT
1336 r128= [HW,DRM]
1337
1338 raid= [HW,RAID]
1339 See Documentation/md.txt.
1340
1341 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1342 See Documentation/ramdisk.txt.
1343
a9913044 1344 ramdisk_blocksize= [RAM]
1da177e4 1345 See Documentation/ramdisk.txt.
a9913044 1346
1da177e4
LT
1347 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1348 New name for the ramdisk parameter.
1349 See Documentation/ramdisk.txt.
1350
21a1ea9e
DS
1351 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1352 RCU callbacks to process in one batch.
1353
1354 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1355 RCU callbacks over which batch limiting is disabled.
1356
1357 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1358 RCU callbacks below which batch limiting is re-enabled.
1359
1360 rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
1361 RCU callbacks to queued before forcing reschedule
1362 on all cpus.
1363
ffdfc409
OJ
1364 rdinit= [KNL]
1365 Format: <full_path>
1366 Run specified binary instead of /init from the ramdisk,
1367 used for early userspace startup. See initrd.
1368
1da177e4
LT
1369 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1370 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1371 See arch/*/kernel/reboot.c.
1372
1373 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1374
461a9aff
ZA
1375 reservetop= [IA-32]
1376 Format: nn[KMG]
1377 Reserves a hole at the top of the kernel virtual
1378 address space.
1379
7e96287d
VG
1380 reset_devices [KNL] Force drivers to reset the underlying device
1381 during initialization.
1382
a9913044
RD
1383 resume= [SWSUSP]
1384 Specify the partition device for software suspend
1da177e4
LT
1385
1386 rhash_entries= [KNL,NET]
1387 Set number of hash buckets for route cache
1388
1389 riscom8= [HW,SERIAL]
1390 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1391
1392 ro [KNL] Mount root device read-only on boot
1393
1394 root= [KNL] Root filesystem
1395
1396 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1397 mount the root filesystem
1398
1399 rootflags= [KNL] Set root filesystem mount option string
1400
1401 rootfstype= [KNL] Set root filesystem type
1402
1403 rw [KNL] Mount root device read-write on boot
1404
1405 S [KNL] Run init in single mode
1406
1407 sa1100ir [NET]
1408 See drivers/net/irda/sa1100_ir.c.
1409
1410 sb= [HW,OSS]
1411 Format: <io>,<irq>,<dma>,<dma2>
1412
1413 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1414
1da177e4
LT
1415 sbpcd= [HW,CD] Soundblaster CD adapter
1416 Format: <io>,<type>
1417 See a comment before function sbpcd_setup() in
1418 drivers/cdrom/sbpcd.c.
1419
1420 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1421 Format: <io>[,<timeout>[,<isapnp>]]
1422
1423 scsi_debug_*= [SCSI]
1424 See drivers/scsi/scsi_debug.c.
1425
1426 scsi_default_dev_flags=
1427 [SCSI] SCSI default device flags
1428 Format: <integer>
1429
1430 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1431 Format: <vendor>:<model>:<flags>
1432 (flags are integer value)
1433
1434 scsi_logging= [SCSI]
1435
1436 selinux [SELINUX] Disable or enable SELinux at boot time.
1437 Format: { "0" | "1" }
1438 See security/selinux/Kconfig help text.
1439 0 -- disable.
1440 1 -- enable.
1441 Default value is set via kernel config option.
1442 If enabled at boot time, /selinux/disable can be used
1443 later to disable prior to initial policy load.
1444
4e5ab4cb
JM
1445 selinux_compat_net =
1446 [SELINUX] Set initial selinux_compat_net flag value.
1447 Format: { "0" | "1" }
1448 0 -- use new secmark-based packet controls
1449 1 -- use legacy packet controls
1450 Default value is 0 (preferred).
1451 Value can be changed at runtime via
1452 /selinux/compat_net.
1453
1da177e4
LT
1454 serialnumber [BUGS=IA-32]
1455
a9913044
RD
1456 sg_def_reserved_size= [SCSI]
1457
1da177e4
LT
1458 sgalaxy= [HW,OSS]
1459 Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
1460
1461 shapers= [NET]
1462 Maximal number of shapers.
a9913044 1463
1da177e4
LT
1464 sim710= [SCSI,HW]
1465 See header of drivers/scsi/sim710.c.
1466
1467 simeth= [IA-64]
1468 simscsi=
a9913044 1469
1da177e4
LT
1470 sjcd= [HW,CD]
1471 Format: <io>,<irq>,<dma>
1472 See header of drivers/cdrom/sjcd.c.
1473
1474 slram= [HW,MTD]
1475
1476 smart2= [HW]
1477 Format: <io1>[,<io2>[,...,<io8>]]
1478
1479 snd-ad1816a= [HW,ALSA]
1480
1481 snd-ad1848= [HW,ALSA]
1482
1483 snd-ali5451= [HW,ALSA]
1484
1485 snd-als100= [HW,ALSA]
1486
1487 snd-als4000= [HW,ALSA]
1488
1489 snd-azt2320= [HW,ALSA]
1490
1491 snd-cmi8330= [HW,ALSA]
1492
1493 snd-cmipci= [HW,ALSA]
1494
1495 snd-cs4231= [HW,ALSA]
1496
1497 snd-cs4232= [HW,ALSA]
1498
1499 snd-cs4236= [HW,ALSA]
1500
1501 snd-cs4281= [HW,ALSA]
1502
1503 snd-cs46xx= [HW,ALSA]
1504
1505 snd-dt019x= [HW,ALSA]
1506
1507 snd-dummy= [HW,ALSA]
1508
1509 snd-emu10k1= [HW,ALSA]
1510
1511 snd-ens1370= [HW,ALSA]
1512
1513 snd-ens1371= [HW,ALSA]
1514
1515 snd-es968= [HW,ALSA]
1516
1517 snd-es1688= [HW,ALSA]
1518
1519 snd-es18xx= [HW,ALSA]
1520
1521 snd-es1938= [HW,ALSA]
1522
1523 snd-es1968= [HW,ALSA]
1524
1525 snd-fm801= [HW,ALSA]
1526
1527 snd-gusclassic= [HW,ALSA]
1528
1529 snd-gusextreme= [HW,ALSA]
1530
1531 snd-gusmax= [HW,ALSA]
1532
1533 snd-hdsp= [HW,ALSA]
1534
1535 snd-ice1712= [HW,ALSA]
1536
1537 snd-intel8x0= [HW,ALSA]
1538
1539 snd-interwave= [HW,ALSA]
1540
1541 snd-interwave-stb=
1542 [HW,ALSA]
1543
1544 snd-korg1212= [HW,ALSA]
1545
1546 snd-maestro3= [HW,ALSA]
1547
1548 snd-mpu401= [HW,ALSA]
1549
1550 snd-mtpav= [HW,ALSA]
1551
1552 snd-nm256= [HW,ALSA]
1553
1554 snd-opl3sa2= [HW,ALSA]
1555
1556 snd-opti92x-ad1848=
1557 [HW,ALSA]
1558
1559 snd-opti92x-cs4231=
1560 [HW,ALSA]
1561
1562 snd-opti93x= [HW,ALSA]
1563
1564 snd-pmac= [HW,ALSA]
1565
1566 snd-rme32= [HW,ALSA]
1567
1568 snd-rme96= [HW,ALSA]
1569
1570 snd-rme9652= [HW,ALSA]
1571
1572 snd-sb8= [HW,ALSA]
1573
1574 snd-sb16= [HW,ALSA]
1575
1576 snd-sbawe= [HW,ALSA]
1577
1578 snd-serial= [HW,ALSA]
1579
1580 snd-sgalaxy= [HW,ALSA]
1581
1582 snd-sonicvibes= [HW,ALSA]
1583
1584 snd-sun-amd7930=
1585 [HW,ALSA]
1586
1587 snd-sun-cs4231= [HW,ALSA]
1588
1589 snd-trident= [HW,ALSA]
1590
1591 snd-usb-audio= [HW,ALSA,USB]
1592
1593 snd-via82xx= [HW,ALSA]
1594
1595 snd-virmidi= [HW,ALSA]
1596
1597 snd-wavefront= [HW,ALSA]
1598
1599 snd-ymfpci= [HW,ALSA]
a9913044 1600
1da177e4
LT
1601 sonicvibes= [HW,OSS]
1602 Format: <reverb>
a9913044 1603
1da177e4
LT
1604 sonycd535= [HW,CD]
1605 Format: <io>[,<irq>]
1606
1607 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1608 See Documentation/sonypi.txt
1609
1610 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1611 See Documentation/specialix.txt.
1612
1613 spia_io_base= [HW,MTD]
1614 spia_fio_base=
1615 spia_pedr=
1616 spia_peddr=
1617
1618 sscape= [HW,OSS]
1619 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1620
1da177e4
LT
1621 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1622 See Documentation/scsi/st.txt.
1623
1624 st0x= [HW,SCSI]
1625 See header of drivers/scsi/seagate.c.
1626
1627 sti= [PARISC,HW]
1628 Format: <num>
1629 Set the STI (builtin display/keyboard on the HP-PARISC
1630 machines) console (graphic card) which should be used
1631 as the initial boot-console.
1632 See also comment in drivers/video/console/sticore.c.
1633
1634 sti_font= [HW]
1635 See comment in drivers/video/console/sticore.c.
1636
1637 stifb= [HW]
1638 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1639
1da177e4 1640 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1641
1da177e4
LT
1642 switches= [HW,M68k]
1643
1644 sym53c416= [HW,SCSI]
1645 See header of drivers/scsi/sym53c416.c.
1646
1647 t128= [HW,SCSI]
1648 See header of drivers/scsi/t128.c.
1649
1650 tdfx= [HW,DRM]
1651
1652 thash_entries= [KNL,NET]
1653 Set number of hash buckets for TCP connection
1654
1655 time Show timing data prefixed to each printk message line
1656
734efb46
JS
1657 clocksource= [GENERIC_TIME] Override the default clocksource
1658 Override the default clocksource and use the clocksource
1659 with the name specified.
1660
1da177e4
LT
1661 tipar.timeout= [HW,PPT]
1662 Set communications timeout in tenths of a second
1663 (default 15).
1664
1665 tipar.delay= [HW,PPT]
1666 Set inter-bit delay in microseconds (default 10).
1667
1668 tmc8xx= [HW,SCSI]
1669 See header of drivers/scsi/seagate.c.
1670
1671 tmscsim= [HW,SCSI]
1672 See comment before function dc390_setup() in
1673 drivers/scsi/tmscsim.c.
1674
1675 tp720= [HW,PS2]
1676
1677 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1678 Format:
1679 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1680
1da177e4
LT
1681 tsdev.xres= [TS] Horizontal screen resolution.
1682 tsdev.yres= [TS] Vertical screen resolution.
1683
a9913044
RD
1684 turbografx.map[2|3]= [HW,JOY]
1685 TurboGraFX parallel port interface
1686 Format:
1687 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1688 See also Documentation/input/joystick-parport.txt
1689
1690 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1691 See header of drivers/scsi/u14-34f.c.
1692
1693 uart401= [HW,OSS]
1694 Format: <io>,<irq>
1695
1696 uart6850= [HW,OSS]
1697 Format: <io>,<irq>
1698
1da177e4
LT
1699 usbhid.mousepoll=
1700 [USBHID] The interval which mice are to be polled at.
a9913044 1701
e6e5494c
IM
1702 vdso= [IA-32]
1703 vdso=1: enable VDSO (default)
1704 vdso=0: disable VDSO mapping
1705
1da177e4
LT
1706 video= [FB] Frame buffer configuration
1707 See Documentation/fb/modedb.txt.
1708
1709 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1710 See Documentation/i386/boot.txt and
1711 Documentation/svga.txt.
1da177e4
LT
1712 Use vga=ask for menu.
1713 This is actually a boot loader parameter; the value is
1714 passed to the kernel using a special protocol.
1715
a9913044 1716 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1717 size of <nn>. This can be used to increase the
1718 minimum size (128MB on x86). It can also be used to
1719 decrease the size and leave more room for directly
1720 mapped kernel RAM.
1721
585c3047
PO
1722 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1723 Format: <command>
1da177e4 1724
585c3047
PO
1725 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1726 Format: <command>
1727
1728 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1729 Format: <command>
a9913044 1730
1da177e4
LT
1731 waveartist= [HW,OSS]
1732 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1733
1da177e4
LT
1734 wd33c93= [HW,SCSI]
1735 See header of drivers/scsi/wd33c93.c.
1736
1737 wd7000= [HW,SCSI]
1738 See header of drivers/scsi/wd7000.c.
1739
1740 wdt= [WDT] Watchdog
1741 See Documentation/watchdog/watchdog.txt.
1742
1743 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1744 xd_geo= See header of drivers/block/xd.c.
1745
1746 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1747 Format:
1748 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1749
a62eaf15
AK
1750 norandmaps Don't use address space randomization
1751 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1752
1da177e4 1753
a9913044 1754______________________________________________________________________
1da177e4
LT
1755
1756TODO:
1757
1758 Add documentation for ALSA options.
1759 Add more DRM drivers.