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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.
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167 acpi_use_timer_override [HW,ACPI}
168 Use timer override. For some broken Nvidia NF5 boards
169 that require a timer override, but don't have
170 HPET
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171
172 acpi_dbg_layer= [HW,ACPI]
173 Format: <int>
a9913044 174 Each bit of the <int> indicates an ACPI debug layer,
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175 1: enable, 0: disable. It is useful for boot time
176 debugging. After system has booted up, it can be set
177 via /proc/acpi/debug_layer.
178
179 acpi_dbg_level= [HW,ACPI]
180 Format: <int>
a9913044 181 Each bit of the <int> indicates an ACPI debug level,
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182 1: enable, 0: disable. It is useful for boot time
183 debugging. After system has booted up, it can be set
184 via /proc/acpi/debug_level.
185
186 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
187
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188 acpi_generic_hotkey [HW,ACPI]
189 Allow consolidated generic hotkey driver to
a9913044 190 override platform specific driver.
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191 See also Documentation/acpi-hotkey.txt.
192
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193 acpi_pm_good [IA-32,X86-64]
194 Override the pmtimer bug detection: force the kernel
195 to assume that this machine's pmtimer latches its value
196 and always returns good values.
197
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198 enable_timer_pin_1 [i386,x86-64]
199 Enable PIN 1 of APIC timer
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200 Can be useful to work around chipset bugs
201 (in particular on some ATI chipsets).
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202 The kernel tries to set a reasonable default.
203
204 disable_timer_pin_1 [i386,x86-64]
205 Disable PIN 1 of APIC timer
206 Can be useful to work around chipset bugs.
207
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208 ad1816= [HW,OSS]
209 Format: <io>,<irq>,<dma>,<dma2>
210 See also Documentation/sound/oss/AD1816.
211
212 ad1848= [HW,OSS]
213 Format: <io>,<irq>,<dma>,<dma2>,<type>
214
215 adlib= [HW,OSS]
216 Format: <io>
a9913044 217
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218 advansys= [HW,SCSI]
219 See header of drivers/scsi/advansys.c.
220
221 advwdt= [HW,WDT] Advantech WDT
222 Format: <iostart>,<iostop>
223
224 aedsp16= [HW,OSS] Audio Excel DSP 16
225 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
226 See also header of sound/oss/aedsp16.c.
a9913044 227
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228 aha152x= [HW,SCSI]
229 See Documentation/scsi/aha152x.txt.
230
231 aha1542= [HW,SCSI]
232 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
233
234 aic7xxx= [HW,SCSI]
235 See Documentation/scsi/aic7xxx.txt.
236
237 aic79xx= [HW,SCSI]
238 See Documentation/scsi/aic79xx.txt.
239
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240 amijoy.map= [HW,JOY] Amiga joystick support
241 Map of devices attached to JOY0DAT and JOY1DAT
242 Format: <a>,<b>
243 See also Documentation/kernel/input/joystick.txt
244
245 analog.map= [HW,JOY] Analog joystick and gamepad support
246 Specifies type or capabilities of an analog joystick
247 connected to one of 16 gameports
248 Format: <type1>,<type2>,..<type16>
249
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250 apc= [HW,SPARC]
251 Power management functions (SPARCstation-4/5 + deriv.)
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252 Format: noidle
253 Disable APC CPU standby support. SPARCstation-Fox does
254 not play well with APC CPU idle - disable it if you have
255 APC and your system crashes randomly.
256
a9913044 257 apic= [APIC,i386] Change the output verbosity whilst booting
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258 Format: { quiet (default) | verbose | debug }
259 Change the amount of debugging information output
260 when initialising the APIC and IO-APIC components.
a9913044 261
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262 apm= [APM] Advanced Power Management
263 See header of arch/i386/kernel/apm.c.
264
265 applicom= [HW]
266 Format: <mem>,<irq>
a9913044 267
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268 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
269 Format: <io>,<irq>,<nodeID>
270
271 ataflop= [HW,M68k]
272
273 atarimouse= [HW,MOUSE] Atari Mouse
274
275 atascsi= [HW,SCSI] Atari SCSI
276
277 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
278 EzKey and similar keyboards
279
280 atkbd.reset= [HW] Reset keyboard during initialization
281
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282 atkbd.set= [HW] Select keyboard code set
283 Format: <int> (2 = AT (default), 3 = PS/2)
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284
285 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
286 keyboards
287
288 atkbd.softraw= [HW] Choose between synthetic and real raw mode
289 Format: <bool> (0 = real, 1 = synthetic (default))
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290
291 atkbd.softrepeat= [HW]
292 Use software keyboard repeat
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293
294 autotest [IA64]
295
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296 aztcd= [HW,CD] Aztech CD268 CDROM driver
297 Format: <io>,0x79 (?)
298
299 baycom_epp= [HW,AX25]
300 Format: <io>,<mode>
a9913044 301
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302 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
303 Format: <io>,<mode>
304 See header of drivers/net/hamradio/baycom_par.c.
305
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306 baycom_ser_fdx= [HW,AX25]
307 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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308 Format: <io>,<irq>,<mode>[,<baud>]
309 See header of drivers/net/hamradio/baycom_ser_fdx.c.
310
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311 baycom_ser_hdx= [HW,AX25]
312 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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313 Format: <io>,<irq>,<mode>
314 See header of drivers/net/hamradio/baycom_ser_hdx.c.
315
316 blkmtd_device= [HW,MTD]
317 blkmtd_erasesz=
318 blkmtd_ro=
319 blkmtd_bs=
320 blkmtd_count=
321
322 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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323 bttv.radio= Most important insmod options are available as
324 kernel args too.
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325 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
326 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
327
328 BusLogic= [HW,SCSI]
329 See drivers/scsi/BusLogic.c, comment before function
330 BusLogic_ParseDriverOptions().
331
332 c101= [NET] Moxa C101 synchronous serial card
333
334 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
335 Sometimes CPU hardware bugs make them report the cache
336 size incorrectly. The kernel will attempt work arounds
337 to fix known problems, but for some CPUs it is not
338 possible to determine what the correct size should be.
339 This option provides an override for these situations.
340
341 cdu31a= [HW,CD]
342 Format: <io>,<irq>[,PAS]
343 See header of drivers/cdrom/cdu31a.c.
344
345 chandev= [HW,NET] Generic channel device initialisation
346
347 checkreqprot [SELINUX] Set initial checkreqprot flag value.
348 Format: { "0" | "1" }
349 See security/selinux/Kconfig help text.
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350 0 -- check protection applied by kernel (includes
351 any implied execute protection).
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352 1 -- check protection requested by application.
353 Default value is set via a kernel config option.
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354 Value can be changed at runtime via
355 /selinux/checkreqprot.
356
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357 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
358 [Deprecated]
3f6dee9b 359 Forces specified clocksource (if available) to be used
734efb46 360 when calculating gettimeofday(). If specified
3f6dee9b 361 clocksource is not available, it defaults to PIT.
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362 Format: { pit | tsc | cyclone | pmtmr }
363
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364 disable_8254_timer
365 enable_8254_timer
366 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
367 over the 8254 in addition to over the IO-APIC. The
368 kernel tries to set a sensible default.
369
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370 hpet= [IA-32,HPET] option to disable HPET and use PIT.
371 Format: disable
372
373 cm206= [HW,CD]
374 Format: { auto | [<io>,][<irq>] }
375
376 com20020= [HW,NET] ARCnet - COM20020 chipset
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377 Format:
378 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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379
380 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
381 Format: <io>[,<irq>]
382
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383 com90xx= [HW,NET]
384 ARCnet - COM90xx chipset (memory-mapped buffers)
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385 Format: <io>[,<irq>[,<memstart>]]
386
387 condev= [HW,S390] console device
388 conmode=
a9913044 389
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390 console= [KNL] Output console device and options.
391
392 tty<n> Use the virtual console device <n>.
393
394 ttyS<n>[,options]
f1a1c2dc 395 ttyUSB0[,options]
1da177e4 396 Use the specified serial port. The options are of
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397 the form "bbbbpnf", where "bbbb" is the baud rate,
398 "p" is parity ("n", "o", or "e"), "n" is number of
399 bits, and "f" is flow control ("r" for RTS or
400 omit it). Default is "9600n8".
401
402 See Documentation/serial-console.txt for more
403 information. See
404 Documentation/networking/netconsole.txt for an
405 alternative.
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406
407 uart,io,<addr>[,options]
408 uart,mmio,<addr>[,options]
409 Start an early, polled-mode console on the 8250/16550
410 UART at the specified I/O port or MMIO address,
411 switching to the matching ttyS device later. The
412 options are the same as for ttyS, above.
413
414 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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415 Format:
416 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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417
418 cpia_pp= [HW,PPT]
419 Format: { parport<nr> | auto | none }
420
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421 crashkernel=nn[KMG]@ss[KMG]
422 [KNL] Reserve a chunk of physical memory to
423 hold a kernel to switch to with kexec on panic.
424
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425 cs4232= [HW,OSS]
426 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
427
428 cs89x0_dma= [HW,NET]
429 Format: <dma>
430
431 cs89x0_media= [HW,NET]
432 Format: { rj45 | aui | bnc }
a9913044 433
1da177e4 434 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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435
436 dasd= [HW,NET]
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437 See header of drivers/s390/block/dasd_devmap.c.
438
439 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
440 (one device per port)
441 Format: <port#>,<type>
442 See also Documentation/input/joystick-parport.txt
443
444 debug [KNL] Enable kernel debugging (events log level).
445
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446 debug_locks_verbose=
447 [KNL] verbose self-tests
448 Format=<0|1>
449 Print debugging info while doing the locking API
450 self-tests.
451 We default to 0 (no extra messages), setting it to
452 1 will print _a lot_ more information - normally
453 only useful to kernel developers.
454
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455 decnet= [HW,NET]
456 Format: <area>[,<node>]
457 See also Documentation/networking/decnet.txt.
458
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459 dhash_entries= [KNL]
460 Set number of hash buckets for dentry cache.
a9913044 461
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462 digi= [HW,SERIAL]
463 IO parameters + enable/disable command.
464
465 digiepca= [HW,SERIAL]
466 See drivers/char/README.epca and
467 Documentation/digiepca.txt.
468
469 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
470 support available.
471 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
472
473 dmasound= [HW,OSS] Sound subsystem buffers
474
475 dscc4.setup= [NET]
476
477 dtc3181e= [HW,SCSI]
478
a9913044 479 earlyprintk= [IA-32,X86-64]
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480 earlyprintk=vga
481 earlyprintk=serial[,ttySn[,baudrate]]
482
a9913044 483 Append ",keep" to not disable it when the real console
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484 takes over.
485
486 Only vga or serial at a time, not both.
487
488 Currently only ttyS0 and ttyS1 are supported.
489
490 Interaction with the standard serial driver is not
491 very good.
492
493 The VGA output is eventually overwritten by the real
494 console.
495
496 eata= [HW,SCSI]
497
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498 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
499 Format: <int>
500 0: polling mode
501 non-0: interrupt mode (default)
502
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503 eda= [HW,PS2]
504
505 edb= [HW,PS2]
506
507 edd= [EDD]
508 Format: {"of[f]" | "sk[ipmbr]"}
509 See comment in arch/i386/boot/edd.S
510
a9913044 511 eicon= [HW,ISDN]
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512 Format: <id>,<membase>,<irq>
513
514 eisa_irq_edge= [PARISC,HW]
515 See header of drivers/parisc/eisa.c.
516
517 elanfreq= [IA-32]
518 See comment before function elanfreq_setup() in
519 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
520
521 elevator= [IOSCHED]
16ab3adf 522 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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523 See Documentation/block/as-iosched.txt and
524 Documentation/block/deadline-iosched.txt for details.
525
aac04b32 526 elfcorehdr= [IA-32, X86_64]
a9913044 527 Specifies physical address of start of kernel core
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528 image elf header. Generally kexec loader will
529 pass this option to capture kernel.
530 See Documentation/kdump/kdump.txt for details.
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531
532 enforcing [SELINUX] Set initial enforcing status.
533 Format: {"0" | "1"}
534 See security/selinux/Kconfig help text.
535 0 -- permissive (log only, no denials).
536 1 -- enforcing (deny and log).
537 Default value is 0.
538 Value can be changed at runtime via /selinux/enforce.
539
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540 es1371= [HW,OSS]
541 Format: <spdif>,[<nomix>,[<amplifier>]]
542 See also header of sound/oss/es1371.c.
a9913044 543
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544 ether= [HW,NET] Ethernet cards parameters
545 This option is obsoleted by the "netdev=" option, which
546 has equivalent usage. See its documentation for details.
547
548 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
549 Format: <io>[,<irq>]
550
551 fd_mcs= [HW,SCSI]
552 See header of drivers/scsi/fd_mcs.c.
553
554 fdomain= [HW,SCSI]
555 See header of drivers/scsi/fdomain.c.
556
557 floppy= [HW]
558 See Documentation/floppy.txt.
559
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560 gamecon.map[2|3]=
561 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
562 support via parallel port (up to 5 devices per port)
563 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
564 See also Documentation/input/joystick-parport.txt
565
566 gamma= [HW,DRM]
567
568 gdth= [HW,SCSI]
569 See header of drivers/scsi/gdth.c.
570
571 gpt [EFI] Forces disk with valid GPT signature but
572 invalid Protective MBR to be treated as GPT.
573
574 gscd= [HW,CD]
575 Format: <io>
576
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577 gvp11= [HW,SCSI]
578
579 hashdist= [KNL,NUMA] Large hashes allocated during boot
580 are distributed across NUMA nodes. Defaults on
581 for IA-64, off otherwise.
a9913044 582 Format: 0 | 1 (for off | on)
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583
584 hcl= [IA-64] SGI's Hardware Graph compatibility layer
585
586 hd= [EIDE] (E)IDE hard drive subsystem geometry
587 Format: <cyl>,<head>,<sect>
588
589 hd?= [HW] (E)IDE subsystem
590 hd?lun= See Documentation/ide.txt.
591
592 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
593 size of <nn>. This works even on boxes that have no
594 highmem otherwise. This also works to reduce highmem
595 size on bigger boxes.
596
597 hisax= [HW,ISDN]
598 See Documentation/isdn/README.HiSax.
599
600 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
601
1da177e4 602 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
603 i8042.dumbkbd [HW] Pretend that controller can only read data from
604 keyboard and cannot control its state
1da177e4
LT
605 (Don't attempt to blink the leds)
606 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 607 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
608 i8042.nomux [HW] Don't check presence of an active multiplexing
609 controller
610 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
611 controllers
612 i8042.panicblink=
613 [HW] Frequency with which keyboard LEDs should blink
614 when kernel panics (default is 0.5 sec)
615 i8042.reset [HW] Reset the controller during init and cleanup
616 i8042.unlock [HW] Unlock (ignore) the keylock
617
618 i810= [HW,DRM]
619
e70c9d5e
DT
620 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
621 indicates that the driver is running on unsupported
622 hardware.
1da177e4
LT
623 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
624 does not match list of supported models.
625 i8k.power_status
626 [HW] Report power status in /proc/i8k
627 (disabled by default)
628 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
629 capability is set.
630
631 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
632 See Documentation/mca.txt.
633
634 icn= [HW,ISDN]
635 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
636
637 ide= [HW] (E)IDE subsystem
638 Format: ide=nodma or ide=doubler or ide=reverse
639 See Documentation/ide.txt.
640
641 ide?= [HW] (E)IDE subsystem
642 Format: ide?=noprobe or chipset specific parameters.
643 See Documentation/ide.txt.
a9913044 644
1da177e4
LT
645 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
646 See Documentation/ide.txt.
647
648 idle= [HW]
649 Format: idle=poll or idle=halt
a9913044 650
1da177e4
LT
651 ihash_entries= [KNL]
652 Set number of hash buckets for inode cache.
653
654 in2000= [HW,SCSI]
655 See header of drivers/scsi/in2000.c.
656
657 init= [KNL]
658 Format: <full_path>
659 Run specified binary instead of /sbin/init as init
660 process.
661
662 initcall_debug [KNL] Trace initcalls as they are executed. Useful
663 for working out where the kernel is dying during
664 startup.
665
666 initrd= [BOOT] Specify the location of the initial ramdisk
667
668 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
669 Format: <irq>
670
2bd0fa3b
JB
671 combined_mode= [HW] control which driver uses IDE ports in combined
672 mode: legacy IDE driver, libata, or both
673 (in the libata case, libata.atapi_enabled=1 may be
674 useful as well). Note that using the ide or libata
675 options may affect your device naming (e.g. by
676 changing hdc to sdb).
677 Format: combined (default), ide, or libata
678
1da177e4
LT
679 inttest= [IA64]
680
681 io7= [HW] IO7 for Marvel based alpha systems
682 See comment before marvel_specify_io7 in
683 arch/alpha/kernel/core_marvel.c.
684
685 ip= [IP_PNP]
686 See Documentation/nfsroot.txt.
687
688 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
689 See comment before ip2_setup() in drivers/char/ip2.c.
690
691 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
692 See header of drivers/scsi/ips.c.
693
72c4a13a
SH
694 ports= [IP_VS_FTP] IPVS ftp helper module
695 Default is 21.
696 Up to 8 (IP_VS_APP_MAX_PORTS) ports
697 may be specified.
698 Format: <port>,<port>....
699
200803df
AC
700 irqfixup [HW]
701 When an interrupt is not handled search all handlers
702 for it. Intended to get systems with badly broken
703 firmware running.
704
705 irqpoll [HW]
706 When an interrupt is not handled search all handlers
707 for it. Also check all handlers each timer
708 interrupt. Intended to get systems with badly broken
709 firmware running.
710
1da177e4 711 isapnp= [ISAPNP]
a9913044 712 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
713
714 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
715 Format: <cpu number>,...,<cpu number>
716 This option can be used to specify one or more CPUs
717 to isolate from the general SMP balancing and scheduling
718 algorithms. The only way to move a process onto or off
719 an "isolated" CPU is via the CPU affinity syscalls.
720 <cpu number> begins at 0 and the maximum value is
721 "number of CPUs in system - 1".
722
723 This option is the preferred way to isolate CPUs. The
a9913044
RD
724 alternative -- manually setting the CPU mask of all
725 tasks in the system -- can cause problems and
726 suboptimal load balancer performance.
1da177e4
LT
727
728 isp16= [HW,CD]
729 Format: <io>,<irq>,<dma>,<setup>
730
a9913044 731 iucv= [HW,NET]
1da177e4
LT
732
733 js= [HW,JOY] Analog joystick
734 See Documentation/input/joystick.txt.
735
736 keepinitrd [HW,ARM]
737
a9913044 738 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
739 in oops dumps.
740
741 l2cr= [PPC]
742
a9913044
RD
743 lapic [IA-32,APIC] Enable the local APIC even if BIOS
744 disabled it.
1da177e4
LT
745
746 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
747 Format: addr:<io>,irq:<irq>
748
a9913044
RD
749 llsc*= [IA64] See function print_params() in
750 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
751
752 load_ramdisk= [RAM] List of ramdisks to load from floppy
753 See Documentation/ramdisk.txt.
754
a6b25b67
RD
755 lockd.nlm_grace_period=P [NFS] Assign grace period.
756 Format: <integer>
1da177e4 757
a6b25b67
RD
758 lockd.nlm_tcpport=N [NFS] Assign TCP port.
759 Format: <integer>
760
761 lockd.nlm_timeout=T [NFS] Assign timeout value.
762 Format: <integer>
763
764 lockd.nlm_udpport=M [NFS] Assign UDP port.
765 Format: <integer>
1da177e4
LT
766
767 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
768 Format: <irq>
769
770 loglevel= All Kernel Messages with a loglevel smaller than the
771 console loglevel will be printed to the console. It can
772 also be changed with klogd or other programs. The
773 loglevels are defined as follows:
774
775 0 (KERN_EMERG) system is unusable
776 1 (KERN_ALERT) action must be taken immediately
777 2 (KERN_CRIT) critical conditions
778 3 (KERN_ERR) error conditions
779 4 (KERN_WARNING) warning conditions
780 5 (KERN_NOTICE) normal but significant condition
781 6 (KERN_INFO) informational
782 7 (KERN_DEBUG) debug-level messages
783
784 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
785 Format: { n | nk | nM }
786 n must be a power of two. The default size
787 is set in the kernel config file.
1da177e4
LT
788
789 lp=0 [LP] Specify parallel ports to use, e.g,
790 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
791 lp=reset first parallel port). 'lp=0' disables the
792 lp=auto printer driver. 'lp=reset' (which can be
793 specified in addition to the ports) causes
794 attached printers to be reset. Using
795 lp=port1,port2,... specifies the parallel ports
796 to associate lp devices with, starting with
797 lp0. A port specification may be 'none' to skip
798 that lp device, or a parport name such as
799 'parport0'. Specifying 'lp=auto' instead of a
800 port specification list means that device IDs
801 from each port should be examined, to see if
802 an IEEE 1284-compliant printer is attached; if
803 so, the driver will manage that printer.
804 See also header of drivers/char/lp.c.
805
806 lpj=n [KNL]
807 Sets loops_per_jiffy to given constant, thus avoiding
808 time-consuming boot-time autodetection (up to 250 ms per
809 CPU). 0 enables autodetection (default). To determine
810 the correct value for your kernel, boot with normal
811 autodetection and see what value is printed. Note that
812 on SMP systems the preset will be applied to all CPUs,
813 which is likely to cause problems if your CPUs need
814 significantly divergent settings. An incorrect value
815 will cause delays in the kernel to be wrong, leading to
816 unpredictable I/O errors and other breakage. Although
817 unlikely, in the extreme case this might damage your
818 hardware.
819
820 ltpc= [NET]
821 Format: <io>,<irq>,<dma>
822
a9913044
RD
823 mac5380= [HW,SCSI] Format:
824 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 825
a9913044
RD
826 mac53c9x= [HW,SCSI] Format:
827 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 828
a9913044
RD
829 machvec= [IA64] Force the use of a particular machine-vector
830 (machvec) in a generic kernel.
831 Example: machvec=hpzx1_swiotlb
1da177e4 832
a9913044 833 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
834 be mounted
835 Format: <1-256>
836
837 maxcpus= [SMP] Maximum number of processors that an SMP kernel
838 should make use of
839
2b2c3750
BP
840 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
841 equal to this physical address is ignored.
842
a9913044 843 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
844 Should be between 1 and 2^32-1.
845
846 max_report_luns=
a9913044 847 [SCSI] Maximum number of LUNs received.
1da177e4
LT
848 Should be between 1 and 16384.
849
850 mca-pentium [BUGS=IA-32]
851
852 mcatest= [IA-64]
853
854 mcd= [HW,CD]
855 Format: <port>,<irq>,<mitsumi_bug_93_wait>
856
857 mcdx= [HW,CD]
858
859 mce [IA-32] Machine Check Exception
860
861 md= [HW] RAID subsystems devices and level
862 See Documentation/md.txt.
a9913044 863
1da177e4
LT
864 mdacon= [MDA]
865 Format: <first>,<last>
866 Specifies range of consoles to be captured by the MDA.
a9913044 867
1da177e4
LT
868 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
869 Amount of memory to be used when the kernel is not able
870 to see the whole system memory or for test.
871 [IA-32] Use together with memmap= to avoid physical
872 address space collisions. Without memmap= PCI devices
873 could be placed at addresses belonging to unused RAM.
874
875 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
876 memory.
877
69cda7b1 878 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
879 E820 memory map, as specified by the user.
880 Such memmap=exactmap lines can be constructed based on
881 BIOS output or other requirements. See the memmap=nn@ss
882 option description.
883
884 memmap=nn[KMG]@ss[KMG]
885 [KNL] Force usage of a specific region of memory
886 Region of memory to be used, from ss to ss+nn.
887
888 memmap=nn[KMG]#ss[KMG]
889 [KNL,ACPI] Mark specific memory as ACPI data.
890 Region of memory to be used, from ss to ss+nn.
891
892 memmap=nn[KMG]$ss[KMG]
893 [KNL,ACPI] Mark specific memory as reserved.
894 Region of memory to be used, from ss to ss+nn.
895
896 meye.*= [HW] Set MotionEye Camera parameters
897 See Documentation/video4linux/meye.txt.
898
899 mga= [HW,DRM]
900
198e2f18
AM
901 migration_cost=
902 [KNL,SMP] debug: override scheduler migration costs
903 Format: <level-1-usecs>,<level-2-usecs>,...
904 This debugging option can be used to override the
905 default scheduler migration cost matrix. The numbers
906 are indexed by 'CPU domain distance'.
907 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
908 box will set up an intra-core migration cost of
909 1 msec, an inter-core migration cost of 2 msecs,
910 and an inter-node migration cost of 3 msecs.
911
912 WARNING: using the wrong values here can break
913 scheduler performance, so it's only for scheduler
914 development purposes, not production environments.
915
916 migration_debug=
917 [KNL,SMP] migration cost auto-detect verbosity
918 Format=<0|1|2>
919 If a system's migration matrix reported at bootup
920 seems erroneous then this option can be used to
921 increase verbosity of the detection process.
922 We default to 0 (no extra messages), 1 will print
923 some more information, and 2 will be really
924 verbose (probably only useful if you also have a
925 serial console attached to the system).
926
927 migration_factor=
928 [KNL,SMP] multiply/divide migration costs by a factor
929 Format=<percent>
930 This debug option can be used to proportionally
931 increase or decrease the auto-detected migration
932 costs for all entries of the migration matrix.
933 E.g. migration_factor=150 will increase migration
934 costs by 50%. (and thus the scheduler will be less
935 eager migrating cache-hot tasks)
936 migration_factor=80 will decrease migration costs
937 by 20%. (thus the scheduler will be more eager to
938 migrate tasks)
939
940 WARNING: using the wrong values here can break
941 scheduler performance, so it's only for scheduler
942 development purposes, not production environments.
943
1da177e4
LT
944 mousedev.tap_time=
945 [MOUSE] Maximum time between finger touching and
946 leaving touchpad surface for touch to be considered
947 a tap and be reported as a left button click (for
948 touchpads working in absolute mode only).
949 Format: <msecs>
950 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
951 reporting absolute coordinates, such as tablets
952 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
953 reporting absolute coordinates, such as tablets
954
955 mpu401= [HW,OSS]
956 Format: <io>,<irq>
957
958 MTD_Partition= [MTD]
959 Format: <name>,<region-number>,<size>,<offset>
960
a9913044
RD
961 MTD_Region= [MTD] Format:
962 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
963
964 mtdparts= [MTD]
965 See drivers/mtd/cmdline.c.
966
967 mtouchusb.raw_coordinates=
a9913044
RD
968 [HW] Make the MicroTouch USB driver use raw coordinates
969 ('y', default) or cooked coordinates ('n')
1da177e4
LT
970
971 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
972
973 NCR_D700= [HW,SCSI]
974 See header of drivers/scsi/NCR_D700.c.
975
976 ncr5380= [HW,SCSI]
977
978 ncr53c400= [HW,SCSI]
979
980 ncr53c400a= [HW,SCSI]
981
982 ncr53c406a= [HW,SCSI]
983
984 ncr53c8xx= [HW,SCSI]
985
986 netdev= [NET] Network devices parameters
987 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
988 Note that mem_start is often overloaded to mean
989 something different and driver-specific.
a9913044
RD
990 This usage is only documented in each driver source
991 file if at all.
992
1da177e4
LT
993 nfsaddrs= [NFS]
994 See Documentation/nfsroot.txt.
995
996 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
997 See Documentation/nfsroot.txt.
998
a72b4422
TM
999 nfs.callback_tcpport=
1000 [NFS] set the TCP port on which the NFSv4 callback
1001 channel should listen.
1002
58df095b
TM
1003 nfs.idmap_cache_timeout=
1004 [NFS] set the maximum lifetime for idmapper cache
1005 entries.
1006
1da177e4
LT
1007 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1008
1009 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1010 emulation library even if a 387 maths coprocessor
1011 is present.
1012
a9913044
RD
1013 noalign [KNL,ARM]
1014
1da177e4
LT
1015 noapic [SMP,APIC] Tells the kernel to not make use of any
1016 IOAPICs that may be present in the system.
1017
1018 noasync [HW,M68K] Disables async and sync negotiation for
1019 all devices.
1020
1021 nobats [PPC] Do not use BATs for mapping kernel lowmem
1022 on "Classic" PPC cores.
1023
1024 nocache [ARM]
a9913044 1025
163ecdff
SN
1026 nodelayacct [KNL] Disable per-task delay accounting
1027
1da177e4
LT
1028 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1029
1030 noexec [IA-64]
1031
a9913044 1032 noexec [IA-32,X86-64]
1da177e4
LT
1033 noexec=on: enable non-executable mappings (default)
1034 noexec=off: disable nn-executable mappings
1035
4f886511
CE
1036 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1037 register save and restore. The kernel will only save
1038 legacy floating-point registers on task switch.
1da177e4
LT
1039
1040 nohlt [BUGS=ARM]
a9913044 1041
1da177e4
LT
1042 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1043 instruction doesn't work correctly and not to
1044 use it.
1045
1046 nohalt [IA-64] Tells the kernel not to use the power saving
1047 function PAL_HALT_LIGHT when idle. This increases
1048 power-consumption. On the positive side, it reduces
1049 interrupt wake-up latency, which may improve performance
1050 in certain environments such as networked servers or
1051 real-time systems.
1052
8542b200
ZA
1053 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
1054
1da177e4
LT
1055 noirqdebug [IA-32] Disables the code which attempts to detect and
1056 disable unhandled interrupt sources.
1057
8542b200
ZA
1058 no_timer_check [IA-32,X86_64,APIC] Disables the code which tests for
1059 broken timer IRQ sources.
1060
1da177e4
LT
1061 noisapnp [ISAPNP] Disables ISA PnP code.
1062
1063 noinitrd [RAM] Tells the kernel not to load any configured
1064 initial RAM disk.
1065
1066 nointroute [IA-64]
1067
1068 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1069
1070 noltlbs [PPC] Do not use large page/tlb entries for kernel
1071 lowmem mapping on PPC40x.
1072
312f1f01
H
1073 nomca [IA-64] Disable machine check abort handling
1074
abe37e5a
H
1075 nomce [IA-32] Machine Check Exception
1076
1da177e4
LT
1077 noresidual [PPC] Don't use residual data on PReP machines.
1078
a9913044
RD
1079 noresume [SWSUSP] Disables resume and restores original swap
1080 space.
1081
1da177e4
LT
1082 no-scroll [VGA] Disables scrollback.
1083 This is required for the Braillex ib80-piezo Braille
1084 reader made by F.H. Papenmeier (Germany).
1085
1086 nosbagart [IA-64]
1087
4f886511
CE
1088 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1089
1da177e4
LT
1090 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1091
1092 nosync [HW,M68K] Disables sync negotiation for all devices.
1093
1094 notsc [BUGS=IA-32] Disable Time Stamp Counter
1095
1096 nousb [USB] Disable the USB subsystem
1097
1098 nowb [ARM]
a9913044 1099
a61c2d78
DJ
1100 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1101
1da177e4
LT
1102 opl3= [HW,OSS]
1103 Format: <io>
1104
a9913044
RD
1105 opl3sa2= [HW,OSS] Format:
1106 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1107
1da177e4
LT
1108 oprofile.timer= [HW]
1109 Use timer interrupt instead of performance counters
1110
1111 optcd= [HW,CD]
1112 Format: <io>
1113
1114 osst= [HW,SCSI] SCSI Tape Driver
1115 Format: <buffer_size>,<write_threshold>
1116 See also Documentation/scsi/st.txt.
1117
1118 panic= [KNL] Kernel behaviour on panic
1119 Format: <timeout>
1120
1121 parkbd.port= [HW] Parallel port number the keyboard adapter is
1122 connected to, default is 0.
1123 Format: <parport#>
1124 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1125 0 for XT, 1 for AT (default is AT).
a9913044
RD
1126 Format: <mode>
1127
1128 parport= [HW,PPT] Specify parallel ports. 0 disables.
1129 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1130 Use 'auto' to force the driver to use any
1131 IRQ/DMA settings detected (the default is to
1132 ignore detected IRQ/DMA settings because of
1133 possible conflicts). You can specify the base
1134 address, IRQ, and DMA settings; IRQ and DMA
1135 should be numbers, or 'auto' (for using detected
1136 settings on that particular port), or 'nofifo'
1137 (to avoid using a FIFO even if it is detected).
1138 Parallel ports are assigned in the order they
1139 are specified on the command line, starting
1140 with parport0.
1141
1142 parport_init_mode= [HW,PPT]
1143 Configure VIA parallel port to operate in
1144 a specific mode. This is necessary on Pegasos
1145 computer where firmware has no options for setting
1146 up parallel port mode and sets it to spp.
1147 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1148 Format: [spp|ps2|epp|ecp|ecpepp]
1149
a9913044
RD
1150 pas2= [HW,OSS] Format:
1151 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1152
1da177e4
LT
1153 pas16= [HW,SCSI]
1154 See header of drivers/scsi/pas16.c.
1155
dd287796
AM
1156 pause_on_oops=
1157 Halt all CPUs after the first oops has been printed for
1158 the specified number of seconds. This is to be used if
1159 your oopses keep scrolling off the screen.
1160
1da177e4
LT
1161 pcbit= [HW,ISDN]
1162
1163 pcd. [PARIDE]
1164 See header of drivers/block/paride/pcd.c.
1165 See also Documentation/paride.txt.
1166
a9913044
RD
1167 pci=option[,option...] [PCI] various PCI subsystem options:
1168 off [IA-32] don't probe for the PCI bus
1169 bios [IA-32] force use of PCI BIOS, don't access
1170 the hardware directly. Use this if your machine
1171 has a non-standard PCI host bridge.
1172 nobios [IA-32] disallow use of PCI BIOS, only direct
1173 hardware access methods are allowed. Use this
1174 if you experience crashes upon bootup and you
1175 suspect they are caused by the BIOS.
1176 conf1 [IA-32] Force use of PCI Configuration
1177 Mechanism 1.
1178 conf2 [IA-32] Force use of PCI Configuration
1179 Mechanism 2.
61be6d66
BH
1180 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1181 Configuration
309e57df
MW
1182 nomsi [MSI] If the PCI_MSI kernel config parameter is
1183 enabled, this kernel boot option can be used to
1184 disable the use of MSI interrupts system-wide.
a9913044
RD
1185 nosort [IA-32] Don't sort PCI devices according to
1186 order given by the PCI BIOS. This sorting is
1187 done to get a device order compatible with
1188 older kernels.
1189 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1190 routing table. These calls are known to be buggy
1191 on several machines and they hang the machine
1192 when used, but on other computers it's the only
1193 way to get the interrupt routing table. Try
1194 this option if the kernel is unable to allocate
1195 IRQs or discover secondary PCI buses on your
1196 motherboard.
1197 rom [IA-32] Assign address space to expansion ROMs.
1198 Use with caution as certain devices share
1199 address decoders between ROMs and other
1200 resources.
1201 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1202 assigned automatically to PCI devices. You can
1203 make the kernel exclude IRQs of your ISA cards
1204 this way.
120bb424 1205 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1206 of the PIRQ table (normally generated
1207 by the BIOS) if it is outside the
1208 F0000h-100000h range.
1209 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1210 useful if the kernel is unable to find your
1211 secondary buses and you want to tell it
1212 explicitly which ones they are.
1213 assign-busses [IA-32] Always assign all PCI bus
1214 numbers ourselves, overriding
1215 whatever the firmware may have done.
1216 usepirqmask [IA-32] Honor the possible IRQ mask stored
1217 in the BIOS $PIR table. This is needed on
1218 some systems with broken BIOSes, notably
1219 some HP Pavilion N5400 and Omnibook XE3
1220 notebooks. This will have no effect if ACPI
1221 IRQ routing is enabled.
1222 noacpi [IA-32] Do not use ACPI for IRQ routing
1223 or for PCI scanning.
1224 routeirq Do IRQ routing for all PCI devices.
1225 This is normally done in pci_enable_device(),
1226 so this option is a temporary workaround
1227 for broken drivers that don't call it.
1228 firmware [ARM] Do not re-enumerate the bus but instead
1229 just use the configuration from the
1230 bootloader. This is currently used on
1231 IXP2000 systems where the bus has to be
1232 configured a certain way for adjunct CPUs.
0637a70a
AK
1233 noearly [X86] Don't do any early type 1 scanning.
1234 This might help on some broken boards which
1235 machine check when some devices' config space
1236 is read. But various workarounds are disabled
1237 and some IOMMU drivers will not work.
6b4b78fe
MD
1238 bfsort Sort PCI devices into breadth-first order.
1239 This sorting is done to get a device
1240 order compatible with older (<= 2.4) kernels.
1241 nobfsort Don't sort PCI devices into breadth-first order.
1242
1da177e4
LT
1243 pcmv= [HW,PCMCIA] BadgePAD 4
1244
1245 pd. [PARIDE]
1246 See Documentation/paride.txt.
1247
1248 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1249 boot time.
1250 Format: { 0 | 1 }
1251 See arch/parisc/kernel/pdc_chassis.c
1252
1253 pf. [PARIDE]
1254 See Documentation/paride.txt.
1255
1256 pg. [PARIDE]
1257 See Documentation/paride.txt.
1258
1259 pirq= [SMP,APIC] Manual mp-table setup
1260 See Documentation/i386/IO-APIC.txt.
1261
1262 plip= [PPT,NET] Parallel port network link
1263 Format: { parport<nr> | timid | 0 }
1264 See also Documentation/parport.txt.
1265
1266 pnpacpi= [ACPI]
1267 { off }
1268
1269 pnpbios= [ISAPNP]
1270 { on | off | curr | res | no-curr | no-res }
1271
1272 pnp_reserve_irq=
1273 [ISAPNP] Exclude IRQs for the autoconfiguration
1274
1275 pnp_reserve_dma=
1276 [ISAPNP] Exclude DMAs for the autoconfiguration
1277
1278 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1279 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1280
1281 pnp_reserve_mem=
a9913044
RD
1282 [ISAPNP] Exclude memory regions for the
1283 autoconfiguration.
1da177e4
LT
1284 Ranges are in pairs (memory base and size).
1285
1286 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1287 Format: [schedule,]<number>
1288 Param: "schedule" - profile schedule points.
1289 Param: <number> - step/bucket size as a power of 2 for
1290 statistical time based profiling.
1da177e4 1291
a9913044 1292 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1293 Limit processor to maximum C-state
1294 max_cstate=9 overrides any DMI blacklist limit.
1295
41c0d868
LB
1296 processor.nocst [HW,ACPI]
1297 Ignore the _CST method to determine C-states,
1298 instead using the legacy FADT method
1299
1da177e4
LT
1300 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1301 before loading.
1302 See Documentation/ramdisk.txt.
1303
a9913044
RD
1304 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1305 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1306 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1307 per second.
a9913044
RD
1308 psmouse.resetafter= [HW,MOUSE]
1309 Try to reset the device after so many bad packets
1da177e4
LT
1310 (0 = never).
1311 psmouse.resolution=
1312 [HW,MOUSE] Set desired mouse resolution, in dpi.
1313 psmouse.smartscroll=
a9913044 1314 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1315 0 = disabled, 1 = enabled (default).
1316
1317 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1318 Format:
1319 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1320
1321 pt. [PARIDE]
1322 See Documentation/paride.txt.
1323
7d2c502f 1324 quiet [KNL] Disable most log messages
a9913044 1325
1da177e4
LT
1326 r128= [HW,DRM]
1327
1328 raid= [HW,RAID]
1329 See Documentation/md.txt.
1330
1331 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1332 See Documentation/ramdisk.txt.
1333
a9913044 1334 ramdisk_blocksize= [RAM]
1da177e4 1335 See Documentation/ramdisk.txt.
a9913044 1336
1da177e4
LT
1337 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1338 New name for the ramdisk parameter.
1339 See Documentation/ramdisk.txt.
1340
21a1ea9e
DS
1341 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1342 RCU callbacks to process in one batch.
1343
1344 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1345 RCU callbacks over which batch limiting is disabled.
1346
1347 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1348 RCU callbacks below which batch limiting is re-enabled.
1349
ffdfc409
OJ
1350 rdinit= [KNL]
1351 Format: <full_path>
1352 Run specified binary instead of /init from the ramdisk,
1353 used for early userspace startup. See initrd.
1354
1da177e4
LT
1355 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1356 Format: <reboot_mode>[,<reboot_mode2>[,...]]
f3e299fe 1357 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4
LT
1358
1359 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1360
461a9aff
ZA
1361 reservetop= [IA-32]
1362 Format: nn[KMG]
1363 Reserves a hole at the top of the kernel virtual
1364 address space.
1365
7e96287d
VG
1366 reset_devices [KNL] Force drivers to reset the underlying device
1367 during initialization.
1368
a9913044
RD
1369 resume= [SWSUSP]
1370 Specify the partition device for software suspend
1da177e4
LT
1371
1372 rhash_entries= [KNL,NET]
1373 Set number of hash buckets for route cache
1374
1375 riscom8= [HW,SERIAL]
1376 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1377
1378 ro [KNL] Mount root device read-only on boot
1379
1380 root= [KNL] Root filesystem
1381
1382 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1383 mount the root filesystem
1384
1385 rootflags= [KNL] Set root filesystem mount option string
1386
1387 rootfstype= [KNL] Set root filesystem type
1388
1389 rw [KNL] Mount root device read-write on boot
1390
1391 S [KNL] Run init in single mode
1392
1393 sa1100ir [NET]
1394 See drivers/net/irda/sa1100_ir.c.
1395
1396 sb= [HW,OSS]
1397 Format: <io>,<irq>,<dma>,<dma2>
1398
1399 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1400
1da177e4
LT
1401 sbpcd= [HW,CD] Soundblaster CD adapter
1402 Format: <io>,<type>
1403 See a comment before function sbpcd_setup() in
1404 drivers/cdrom/sbpcd.c.
1405
1406 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1407 Format: <io>[,<timeout>[,<isapnp>]]
1408
1409 scsi_debug_*= [SCSI]
1410 See drivers/scsi/scsi_debug.c.
1411
1412 scsi_default_dev_flags=
1413 [SCSI] SCSI default device flags
1414 Format: <integer>
1415
1416 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1417 Format: <vendor>:<model>:<flags>
1418 (flags are integer value)
1419
1420 scsi_logging= [SCSI]
1421
3e082a91
MW
1422 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1423 discovered. async scans them in kernel threads,
1424 allowing boot to proceed. none ignores them, expecting
1425 user space to do the scan.
1426
1da177e4
LT
1427 selinux [SELINUX] Disable or enable SELinux at boot time.
1428 Format: { "0" | "1" }
1429 See security/selinux/Kconfig help text.
1430 0 -- disable.
1431 1 -- enable.
1432 Default value is set via kernel config option.
1433 If enabled at boot time, /selinux/disable can be used
1434 later to disable prior to initial policy load.
1435
4e5ab4cb
JM
1436 selinux_compat_net =
1437 [SELINUX] Set initial selinux_compat_net flag value.
1438 Format: { "0" | "1" }
1439 0 -- use new secmark-based packet controls
1440 1 -- use legacy packet controls
1441 Default value is 0 (preferred).
1442 Value can be changed at runtime via
1443 /selinux/compat_net.
1444
1da177e4
LT
1445 serialnumber [BUGS=IA-32]
1446
a9913044
RD
1447 sg_def_reserved_size= [SCSI]
1448
1da177e4
LT
1449 shapers= [NET]
1450 Maximal number of shapers.
a9913044 1451
1da177e4
LT
1452 sim710= [SCSI,HW]
1453 See header of drivers/scsi/sim710.c.
1454
1455 simeth= [IA-64]
1456 simscsi=
a9913044 1457
1da177e4
LT
1458 sjcd= [HW,CD]
1459 Format: <io>,<irq>,<dma>
1460 See header of drivers/cdrom/sjcd.c.
1461
1462 slram= [HW,MTD]
1463
1464 smart2= [HW]
1465 Format: <io1>[,<io2>[,...,<io8>]]
1466
1467 snd-ad1816a= [HW,ALSA]
1468
1469 snd-ad1848= [HW,ALSA]
1470
1471 snd-ali5451= [HW,ALSA]
1472
1473 snd-als100= [HW,ALSA]
1474
1475 snd-als4000= [HW,ALSA]
1476
1477 snd-azt2320= [HW,ALSA]
1478
1479 snd-cmi8330= [HW,ALSA]
1480
1481 snd-cmipci= [HW,ALSA]
1482
1483 snd-cs4231= [HW,ALSA]
1484
1485 snd-cs4232= [HW,ALSA]
1486
1487 snd-cs4236= [HW,ALSA]
1488
1489 snd-cs4281= [HW,ALSA]
1490
1491 snd-cs46xx= [HW,ALSA]
1492
1493 snd-dt019x= [HW,ALSA]
1494
1495 snd-dummy= [HW,ALSA]
1496
1497 snd-emu10k1= [HW,ALSA]
1498
1499 snd-ens1370= [HW,ALSA]
1500
1501 snd-ens1371= [HW,ALSA]
1502
1503 snd-es968= [HW,ALSA]
1504
1505 snd-es1688= [HW,ALSA]
1506
1507 snd-es18xx= [HW,ALSA]
1508
1509 snd-es1938= [HW,ALSA]
1510
1511 snd-es1968= [HW,ALSA]
1512
1513 snd-fm801= [HW,ALSA]
1514
1515 snd-gusclassic= [HW,ALSA]
1516
1517 snd-gusextreme= [HW,ALSA]
1518
1519 snd-gusmax= [HW,ALSA]
1520
1521 snd-hdsp= [HW,ALSA]
1522
1523 snd-ice1712= [HW,ALSA]
1524
1525 snd-intel8x0= [HW,ALSA]
1526
1527 snd-interwave= [HW,ALSA]
1528
1529 snd-interwave-stb=
1530 [HW,ALSA]
1531
1532 snd-korg1212= [HW,ALSA]
1533
1534 snd-maestro3= [HW,ALSA]
1535
1536 snd-mpu401= [HW,ALSA]
1537
1538 snd-mtpav= [HW,ALSA]
1539
1540 snd-nm256= [HW,ALSA]
1541
1542 snd-opl3sa2= [HW,ALSA]
1543
1544 snd-opti92x-ad1848=
1545 [HW,ALSA]
1546
1547 snd-opti92x-cs4231=
1548 [HW,ALSA]
1549
1550 snd-opti93x= [HW,ALSA]
1551
1552 snd-pmac= [HW,ALSA]
1553
1554 snd-rme32= [HW,ALSA]
1555
1556 snd-rme96= [HW,ALSA]
1557
1558 snd-rme9652= [HW,ALSA]
1559
1560 snd-sb8= [HW,ALSA]
1561
1562 snd-sb16= [HW,ALSA]
1563
1564 snd-sbawe= [HW,ALSA]
1565
1566 snd-serial= [HW,ALSA]
1567
1568 snd-sgalaxy= [HW,ALSA]
1569
1570 snd-sonicvibes= [HW,ALSA]
1571
1572 snd-sun-amd7930=
1573 [HW,ALSA]
1574
1575 snd-sun-cs4231= [HW,ALSA]
1576
1577 snd-trident= [HW,ALSA]
1578
1579 snd-usb-audio= [HW,ALSA,USB]
1580
1581 snd-via82xx= [HW,ALSA]
1582
1583 snd-virmidi= [HW,ALSA]
1584
1585 snd-wavefront= [HW,ALSA]
1586
1587 snd-ymfpci= [HW,ALSA]
a9913044 1588
1da177e4
LT
1589 sonycd535= [HW,CD]
1590 Format: <io>[,<irq>]
1591
1592 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1593 See Documentation/sonypi.txt
1594
1595 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1596 See Documentation/specialix.txt.
1597
1598 spia_io_base= [HW,MTD]
1599 spia_fio_base=
1600 spia_pedr=
1601 spia_peddr=
1602
1603 sscape= [HW,OSS]
1604 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1605
1da177e4
LT
1606 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1607 See Documentation/scsi/st.txt.
1608
1609 st0x= [HW,SCSI]
1610 See header of drivers/scsi/seagate.c.
1611
1612 sti= [PARISC,HW]
1613 Format: <num>
1614 Set the STI (builtin display/keyboard on the HP-PARISC
1615 machines) console (graphic card) which should be used
1616 as the initial boot-console.
1617 See also comment in drivers/video/console/sticore.c.
1618
1619 sti_font= [HW]
1620 See comment in drivers/video/console/sticore.c.
1621
1622 stifb= [HW]
1623 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1624
1da177e4 1625 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1626
1da177e4
LT
1627 switches= [HW,M68k]
1628
1629 sym53c416= [HW,SCSI]
1630 See header of drivers/scsi/sym53c416.c.
1631
1632 t128= [HW,SCSI]
1633 See header of drivers/scsi/t128.c.
1634
1635 tdfx= [HW,DRM]
1636
1637 thash_entries= [KNL,NET]
1638 Set number of hash buckets for TCP connection
1639
1640 time Show timing data prefixed to each printk message line
1641
734efb46
JS
1642 clocksource= [GENERIC_TIME] Override the default clocksource
1643 Override the default clocksource and use the clocksource
1644 with the name specified.
1645
1da177e4
LT
1646 tipar.timeout= [HW,PPT]
1647 Set communications timeout in tenths of a second
1648 (default 15).
1649
1650 tipar.delay= [HW,PPT]
1651 Set inter-bit delay in microseconds (default 10).
1652
1653 tmc8xx= [HW,SCSI]
1654 See header of drivers/scsi/seagate.c.
1655
1656 tmscsim= [HW,SCSI]
1657 See comment before function dc390_setup() in
1658 drivers/scsi/tmscsim.c.
1659
1660 tp720= [HW,PS2]
1661
1662 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1663 Format:
1664 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1665
1da177e4
LT
1666 tsdev.xres= [TS] Horizontal screen resolution.
1667 tsdev.yres= [TS] Vertical screen resolution.
1668
a9913044
RD
1669 turbografx.map[2|3]= [HW,JOY]
1670 TurboGraFX parallel port interface
1671 Format:
1672 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1673 See also Documentation/input/joystick-parport.txt
1674
1675 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1676 See header of drivers/scsi/u14-34f.c.
1677
1678 uart401= [HW,OSS]
1679 Format: <io>,<irq>
1680
1681 uart6850= [HW,OSS]
1682 Format: <io>,<irq>
1683
1da177e4
LT
1684 usbhid.mousepoll=
1685 [USBHID] The interval which mice are to be polled at.
a9913044 1686
e6e5494c
IM
1687 vdso= [IA-32]
1688 vdso=1: enable VDSO (default)
1689 vdso=0: disable VDSO mapping
1690
1da177e4
LT
1691 video= [FB] Frame buffer configuration
1692 See Documentation/fb/modedb.txt.
1693
1694 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1695 See Documentation/i386/boot.txt and
1696 Documentation/svga.txt.
1da177e4
LT
1697 Use vga=ask for menu.
1698 This is actually a boot loader parameter; the value is
1699 passed to the kernel using a special protocol.
1700
a9913044 1701 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1702 size of <nn>. This can be used to increase the
1703 minimum size (128MB on x86). It can also be used to
1704 decrease the size and leave more room for directly
1705 mapped kernel RAM.
1706
585c3047
PO
1707 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1708 Format: <command>
1da177e4 1709
585c3047
PO
1710 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1711 Format: <command>
1712
1713 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1714 Format: <command>
a9913044 1715
1da177e4
LT
1716 waveartist= [HW,OSS]
1717 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1718
1da177e4
LT
1719 wd33c93= [HW,SCSI]
1720 See header of drivers/scsi/wd33c93.c.
1721
1722 wd7000= [HW,SCSI]
1723 See header of drivers/scsi/wd7000.c.
1724
1725 wdt= [WDT] Watchdog
1726 See Documentation/watchdog/watchdog.txt.
1727
1728 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1729 xd_geo= See header of drivers/block/xd.c.
1730
1731 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1732 Format:
1733 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1734
a62eaf15
AK
1735 norandmaps Don't use address space randomization
1736 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1737
1da177e4 1738
a9913044 1739______________________________________________________________________
1da177e4
LT
1740
1741TODO:
1742
1743 Add documentation for ALSA options.
1744 Add more DRM drivers.