[PATCH] get_options to allow a hypenated range for isolcpus
[linux-block.git] / Documentation / kernel-parameters.txt
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0ee9d71f 1 Kernel Parameters
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2 ~~~~~~~~~~~~~~~~~
3
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
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20This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
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27The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
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31
32 ACPI ACPI support is enabled.
33 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
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
5d0cf410 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
734efb46 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
602 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
603
604 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
605 i8042.dumbkbd [HW] Pretend that controller can only read data from
606 keyboard and cannot control its state
1da177e4
LT
607 (Don't attempt to blink the leds)
608 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 609 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
610 i8042.nomux [HW] Don't check presence of an active multiplexing
611 controller
612 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
613 controllers
614 i8042.panicblink=
615 [HW] Frequency with which keyboard LEDs should blink
616 when kernel panics (default is 0.5 sec)
617 i8042.reset [HW] Reset the controller during init and cleanup
618 i8042.unlock [HW] Unlock (ignore) the keylock
619
620 i810= [HW,DRM]
621
e70c9d5e
DT
622 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
623 indicates that the driver is running on unsupported
624 hardware.
1da177e4
LT
625 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
626 does not match list of supported models.
627 i8k.power_status
628 [HW] Report power status in /proc/i8k
629 (disabled by default)
630 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
631 capability is set.
632
633 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
634 See Documentation/mca.txt.
635
636 icn= [HW,ISDN]
637 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
638
639 ide= [HW] (E)IDE subsystem
640 Format: ide=nodma or ide=doubler or ide=reverse
641 See Documentation/ide.txt.
642
643 ide?= [HW] (E)IDE subsystem
644 Format: ide?=noprobe or chipset specific parameters.
645 See Documentation/ide.txt.
a9913044 646
1da177e4
LT
647 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
648 See Documentation/ide.txt.
649
650 idle= [HW]
651 Format: idle=poll or idle=halt
a9913044 652
1da177e4
LT
653 ihash_entries= [KNL]
654 Set number of hash buckets for inode cache.
655
656 in2000= [HW,SCSI]
657 See header of drivers/scsi/in2000.c.
658
659 init= [KNL]
660 Format: <full_path>
661 Run specified binary instead of /sbin/init as init
662 process.
663
664 initcall_debug [KNL] Trace initcalls as they are executed. Useful
665 for working out where the kernel is dying during
666 startup.
667
668 initrd= [BOOT] Specify the location of the initial ramdisk
669
670 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
671 Format: <irq>
672
2bd0fa3b
JB
673 combined_mode= [HW] control which driver uses IDE ports in combined
674 mode: legacy IDE driver, libata, or both
675 (in the libata case, libata.atapi_enabled=1 may be
676 useful as well). Note that using the ide or libata
677 options may affect your device naming (e.g. by
678 changing hdc to sdb).
679 Format: combined (default), ide, or libata
680
1da177e4
LT
681 inttest= [IA64]
682
683 io7= [HW] IO7 for Marvel based alpha systems
684 See comment before marvel_specify_io7 in
685 arch/alpha/kernel/core_marvel.c.
686
687 ip= [IP_PNP]
688 See Documentation/nfsroot.txt.
689
690 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
691 See comment before ip2_setup() in drivers/char/ip2.c.
692
693 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
694 See header of drivers/scsi/ips.c.
695
72c4a13a
SH
696 ports= [IP_VS_FTP] IPVS ftp helper module
697 Default is 21.
698 Up to 8 (IP_VS_APP_MAX_PORTS) ports
699 may be specified.
700 Format: <port>,<port>....
701
200803df
AC
702 irqfixup [HW]
703 When an interrupt is not handled search all handlers
704 for it. Intended to get systems with badly broken
705 firmware running.
706
707 irqpoll [HW]
708 When an interrupt is not handled search all handlers
709 for it. Also check all handlers each timer
710 interrupt. Intended to get systems with badly broken
711 firmware running.
712
1da177e4 713 isapnp= [ISAPNP]
a9913044 714 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
715
716 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
22f2e280
DF
717 Format:
718 <cpu number>,...,<cpu number>
719 or
720 <cpu number>-<cpu number> (must be a positive range in ascending order)
721 or a mixture
722 <cpu number>,...,<cpu number>-<cpu number>
1da177e4
LT
723 This option can be used to specify one or more CPUs
724 to isolate from the general SMP balancing and scheduling
725 algorithms. The only way to move a process onto or off
726 an "isolated" CPU is via the CPU affinity syscalls.
727 <cpu number> begins at 0 and the maximum value is
728 "number of CPUs in system - 1".
729
730 This option is the preferred way to isolate CPUs. The
a9913044
RD
731 alternative -- manually setting the CPU mask of all
732 tasks in the system -- can cause problems and
733 suboptimal load balancer performance.
1da177e4
LT
734
735 isp16= [HW,CD]
736 Format: <io>,<irq>,<dma>,<setup>
737
a9913044 738 iucv= [HW,NET]
1da177e4
LT
739
740 js= [HW,JOY] Analog joystick
741 See Documentation/input/joystick.txt.
742
743 keepinitrd [HW,ARM]
744
a9913044 745 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
746 in oops dumps.
747
748 l2cr= [PPC]
749
a9913044
RD
750 lapic [IA-32,APIC] Enable the local APIC even if BIOS
751 disabled it.
1da177e4
LT
752
753 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
754 Format: addr:<io>,irq:<irq>
755
a9913044
RD
756 llsc*= [IA64] See function print_params() in
757 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
758
759 load_ramdisk= [RAM] List of ramdisks to load from floppy
760 See Documentation/ramdisk.txt.
761
a6b25b67
RD
762 lockd.nlm_grace_period=P [NFS] Assign grace period.
763 Format: <integer>
1da177e4 764
a6b25b67
RD
765 lockd.nlm_tcpport=N [NFS] Assign TCP port.
766 Format: <integer>
767
768 lockd.nlm_timeout=T [NFS] Assign timeout value.
769 Format: <integer>
770
771 lockd.nlm_udpport=M [NFS] Assign UDP port.
772 Format: <integer>
1da177e4
LT
773
774 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
775 Format: <irq>
776
777 loglevel= All Kernel Messages with a loglevel smaller than the
778 console loglevel will be printed to the console. It can
779 also be changed with klogd or other programs. The
780 loglevels are defined as follows:
781
782 0 (KERN_EMERG) system is unusable
783 1 (KERN_ALERT) action must be taken immediately
784 2 (KERN_CRIT) critical conditions
785 3 (KERN_ERR) error conditions
786 4 (KERN_WARNING) warning conditions
787 5 (KERN_NOTICE) normal but significant condition
788 6 (KERN_INFO) informational
789 7 (KERN_DEBUG) debug-level messages
790
791 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
792 Format: { n | nk | nM }
793 n must be a power of two. The default size
794 is set in the kernel config file.
1da177e4
LT
795
796 lp=0 [LP] Specify parallel ports to use, e.g,
797 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
798 lp=reset first parallel port). 'lp=0' disables the
799 lp=auto printer driver. 'lp=reset' (which can be
800 specified in addition to the ports) causes
801 attached printers to be reset. Using
802 lp=port1,port2,... specifies the parallel ports
803 to associate lp devices with, starting with
804 lp0. A port specification may be 'none' to skip
805 that lp device, or a parport name such as
806 'parport0'. Specifying 'lp=auto' instead of a
807 port specification list means that device IDs
808 from each port should be examined, to see if
809 an IEEE 1284-compliant printer is attached; if
810 so, the driver will manage that printer.
811 See also header of drivers/char/lp.c.
812
813 lpj=n [KNL]
814 Sets loops_per_jiffy to given constant, thus avoiding
815 time-consuming boot-time autodetection (up to 250 ms per
816 CPU). 0 enables autodetection (default). To determine
817 the correct value for your kernel, boot with normal
818 autodetection and see what value is printed. Note that
819 on SMP systems the preset will be applied to all CPUs,
820 which is likely to cause problems if your CPUs need
821 significantly divergent settings. An incorrect value
822 will cause delays in the kernel to be wrong, leading to
823 unpredictable I/O errors and other breakage. Although
824 unlikely, in the extreme case this might damage your
825 hardware.
826
827 ltpc= [NET]
828 Format: <io>,<irq>,<dma>
829
a9913044
RD
830 mac5380= [HW,SCSI] Format:
831 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 832
a9913044
RD
833 mac53c9x= [HW,SCSI] Format:
834 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 835
a9913044
RD
836 machvec= [IA64] Force the use of a particular machine-vector
837 (machvec) in a generic kernel.
838 Example: machvec=hpzx1_swiotlb
1da177e4 839
a9913044 840 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
841 be mounted
842 Format: <1-256>
843
844 maxcpus= [SMP] Maximum number of processors that an SMP kernel
845 should make use of
846
2b2c3750
BP
847 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
848 equal to this physical address is ignored.
849
a9913044 850 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
851 Should be between 1 and 2^32-1.
852
853 max_report_luns=
a9913044 854 [SCSI] Maximum number of LUNs received.
1da177e4
LT
855 Should be between 1 and 16384.
856
857 mca-pentium [BUGS=IA-32]
858
859 mcatest= [IA-64]
860
861 mcd= [HW,CD]
862 Format: <port>,<irq>,<mitsumi_bug_93_wait>
863
864 mcdx= [HW,CD]
865
866 mce [IA-32] Machine Check Exception
867
868 md= [HW] RAID subsystems devices and level
869 See Documentation/md.txt.
a9913044 870
1da177e4
LT
871 mdacon= [MDA]
872 Format: <first>,<last>
873 Specifies range of consoles to be captured by the MDA.
a9913044 874
1da177e4
LT
875 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
876 Amount of memory to be used when the kernel is not able
877 to see the whole system memory or for test.
878 [IA-32] Use together with memmap= to avoid physical
879 address space collisions. Without memmap= PCI devices
880 could be placed at addresses belonging to unused RAM.
881
882 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
883 memory.
884
69cda7b1 885 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
886 E820 memory map, as specified by the user.
887 Such memmap=exactmap lines can be constructed based on
888 BIOS output or other requirements. See the memmap=nn@ss
889 option description.
890
891 memmap=nn[KMG]@ss[KMG]
892 [KNL] Force usage of a specific region of memory
893 Region of memory to be used, from ss to ss+nn.
894
895 memmap=nn[KMG]#ss[KMG]
896 [KNL,ACPI] Mark specific memory as ACPI data.
897 Region of memory to be used, from ss to ss+nn.
898
899 memmap=nn[KMG]$ss[KMG]
900 [KNL,ACPI] Mark specific memory as reserved.
901 Region of memory to be used, from ss to ss+nn.
902
903 meye.*= [HW] Set MotionEye Camera parameters
904 See Documentation/video4linux/meye.txt.
905
906 mga= [HW,DRM]
907
198e2f18 908 migration_cost=
909 [KNL,SMP] debug: override scheduler migration costs
910 Format: <level-1-usecs>,<level-2-usecs>,...
911 This debugging option can be used to override the
912 default scheduler migration cost matrix. The numbers
913 are indexed by 'CPU domain distance'.
914 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
915 box will set up an intra-core migration cost of
916 1 msec, an inter-core migration cost of 2 msecs,
917 and an inter-node migration cost of 3 msecs.
918
919 WARNING: using the wrong values here can break
920 scheduler performance, so it's only for scheduler
921 development purposes, not production environments.
922
923 migration_debug=
924 [KNL,SMP] migration cost auto-detect verbosity
925 Format=<0|1|2>
926 If a system's migration matrix reported at bootup
927 seems erroneous then this option can be used to
928 increase verbosity of the detection process.
929 We default to 0 (no extra messages), 1 will print
930 some more information, and 2 will be really
931 verbose (probably only useful if you also have a
932 serial console attached to the system).
933
934 migration_factor=
935 [KNL,SMP] multiply/divide migration costs by a factor
936 Format=<percent>
937 This debug option can be used to proportionally
938 increase or decrease the auto-detected migration
939 costs for all entries of the migration matrix.
940 E.g. migration_factor=150 will increase migration
941 costs by 50%. (and thus the scheduler will be less
942 eager migrating cache-hot tasks)
943 migration_factor=80 will decrease migration costs
944 by 20%. (thus the scheduler will be more eager to
945 migrate tasks)
946
947 WARNING: using the wrong values here can break
948 scheduler performance, so it's only for scheduler
949 development purposes, not production environments.
950
1da177e4
LT
951 mousedev.tap_time=
952 [MOUSE] Maximum time between finger touching and
953 leaving touchpad surface for touch to be considered
954 a tap and be reported as a left button click (for
955 touchpads working in absolute mode only).
956 Format: <msecs>
957 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
958 reporting absolute coordinates, such as tablets
959 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
960 reporting absolute coordinates, such as tablets
961
962 mpu401= [HW,OSS]
963 Format: <io>,<irq>
964
965 MTD_Partition= [MTD]
966 Format: <name>,<region-number>,<size>,<offset>
967
a9913044
RD
968 MTD_Region= [MTD] Format:
969 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
970
971 mtdparts= [MTD]
972 See drivers/mtd/cmdline.c.
973
974 mtouchusb.raw_coordinates=
a9913044
RD
975 [HW] Make the MicroTouch USB driver use raw coordinates
976 ('y', default) or cooked coordinates ('n')
1da177e4
LT
977
978 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
979
980 NCR_D700= [HW,SCSI]
981 See header of drivers/scsi/NCR_D700.c.
982
983 ncr5380= [HW,SCSI]
984
985 ncr53c400= [HW,SCSI]
986
987 ncr53c400a= [HW,SCSI]
988
989 ncr53c406a= [HW,SCSI]
990
991 ncr53c8xx= [HW,SCSI]
992
993 netdev= [NET] Network devices parameters
994 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
995 Note that mem_start is often overloaded to mean
996 something different and driver-specific.
a9913044
RD
997 This usage is only documented in each driver source
998 file if at all.
999
1da177e4
LT
1000 nfsaddrs= [NFS]
1001 See Documentation/nfsroot.txt.
1002
1003 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1004 See Documentation/nfsroot.txt.
1005
a72b4422
TM
1006 nfs.callback_tcpport=
1007 [NFS] set the TCP port on which the NFSv4 callback
1008 channel should listen.
1009
58df095b
TM
1010 nfs.idmap_cache_timeout=
1011 [NFS] set the maximum lifetime for idmapper cache
1012 entries.
1013
1da177e4
LT
1014 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1015
1016 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1017 emulation library even if a 387 maths coprocessor
1018 is present.
1019
3395ee05
PM
1020 noaliencache [MM, NUMA] Disables the allcoation of alien caches in
1021 the slab allocator. Saves per-node memory, but will
1022 impact performance on real NUMA hardware.
1023
a9913044
RD
1024 noalign [KNL,ARM]
1025
1da177e4
LT
1026 noapic [SMP,APIC] Tells the kernel to not make use of any
1027 IOAPICs that may be present in the system.
1028
1029 noasync [HW,M68K] Disables async and sync negotiation for
1030 all devices.
1031
1032 nobats [PPC] Do not use BATs for mapping kernel lowmem
1033 on "Classic" PPC cores.
1034
1035 nocache [ARM]
a9913044 1036
163ecdff
SN
1037 nodelayacct [KNL] Disable per-task delay accounting
1038
1da177e4
LT
1039 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1040
1041 noexec [IA-64]
1042
a9913044 1043 noexec [IA-32,X86-64]
1da177e4
LT
1044 noexec=on: enable non-executable mappings (default)
1045 noexec=off: disable nn-executable mappings
1046
4f886511
CE
1047 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1048 register save and restore. The kernel will only save
1049 legacy floating-point registers on task switch.
1da177e4
LT
1050
1051 nohlt [BUGS=ARM]
a9913044 1052
1da177e4
LT
1053 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1054 instruction doesn't work correctly and not to
1055 use it.
1056
1057 nohalt [IA-64] Tells the kernel not to use the power saving
1058 function PAL_HALT_LIGHT when idle. This increases
1059 power-consumption. On the positive side, it reduces
1060 interrupt wake-up latency, which may improve performance
1061 in certain environments such as networked servers or
1062 real-time systems.
1063
1064 noirqdebug [IA-32] Disables the code which attempts to detect and
1065 disable unhandled interrupt sources.
1066
1067 noisapnp [ISAPNP] Disables ISA PnP code.
1068
1069 noinitrd [RAM] Tells the kernel not to load any configured
1070 initial RAM disk.
1071
1072 nointroute [IA-64]
1073
1074 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1075
1076 noltlbs [PPC] Do not use large page/tlb entries for kernel
1077 lowmem mapping on PPC40x.
1078
312f1f01
H
1079 nomca [IA-64] Disable machine check abort handling
1080
abe37e5a
H
1081 nomce [IA-32] Machine Check Exception
1082
1da177e4
LT
1083 noresidual [PPC] Don't use residual data on PReP machines.
1084
a9913044
RD
1085 noresume [SWSUSP] Disables resume and restores original swap
1086 space.
1087
1da177e4
LT
1088 no-scroll [VGA] Disables scrollback.
1089 This is required for the Braillex ib80-piezo Braille
1090 reader made by F.H. Papenmeier (Germany).
1091
1092 nosbagart [IA-64]
1093
4f886511
CE
1094 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1095
1da177e4
LT
1096 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1097
1098 nosync [HW,M68K] Disables sync negotiation for all devices.
1099
1100 notsc [BUGS=IA-32] Disable Time Stamp Counter
1101
1102 nousb [USB] Disable the USB subsystem
1103
1104 nowb [ARM]
a9913044 1105
a61c2d78
DJ
1106 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1107
1da177e4
LT
1108 opl3= [HW,OSS]
1109 Format: <io>
1110
a9913044
RD
1111 opl3sa2= [HW,OSS] Format:
1112 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1113
1da177e4
LT
1114 oprofile.timer= [HW]
1115 Use timer interrupt instead of performance counters
1116
1117 optcd= [HW,CD]
1118 Format: <io>
1119
1120 osst= [HW,SCSI] SCSI Tape Driver
1121 Format: <buffer_size>,<write_threshold>
1122 See also Documentation/scsi/st.txt.
1123
1124 panic= [KNL] Kernel behaviour on panic
1125 Format: <timeout>
1126
1127 parkbd.port= [HW] Parallel port number the keyboard adapter is
1128 connected to, default is 0.
1129 Format: <parport#>
1130 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1131 0 for XT, 1 for AT (default is AT).
a9913044
RD
1132 Format: <mode>
1133
1134 parport= [HW,PPT] Specify parallel ports. 0 disables.
1135 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1136 Use 'auto' to force the driver to use any
1137 IRQ/DMA settings detected (the default is to
1138 ignore detected IRQ/DMA settings because of
1139 possible conflicts). You can specify the base
1140 address, IRQ, and DMA settings; IRQ and DMA
1141 should be numbers, or 'auto' (for using detected
1142 settings on that particular port), or 'nofifo'
1143 (to avoid using a FIFO even if it is detected).
1144 Parallel ports are assigned in the order they
1145 are specified on the command line, starting
1146 with parport0.
1147
1148 parport_init_mode= [HW,PPT]
1149 Configure VIA parallel port to operate in
1150 a specific mode. This is necessary on Pegasos
1151 computer where firmware has no options for setting
1152 up parallel port mode and sets it to spp.
1153 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1154 Format: [spp|ps2|epp|ecp|ecpepp]
1155
a9913044
RD
1156 pas2= [HW,OSS] Format:
1157 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1158
1da177e4
LT
1159 pas16= [HW,SCSI]
1160 See header of drivers/scsi/pas16.c.
1161
dd287796
AM
1162 pause_on_oops=
1163 Halt all CPUs after the first oops has been printed for
1164 the specified number of seconds. This is to be used if
1165 your oopses keep scrolling off the screen.
1166
1da177e4
LT
1167 pcbit= [HW,ISDN]
1168
1169 pcd. [PARIDE]
1170 See header of drivers/block/paride/pcd.c.
1171 See also Documentation/paride.txt.
1172
a9913044
RD
1173 pci=option[,option...] [PCI] various PCI subsystem options:
1174 off [IA-32] don't probe for the PCI bus
1175 bios [IA-32] force use of PCI BIOS, don't access
1176 the hardware directly. Use this if your machine
1177 has a non-standard PCI host bridge.
1178 nobios [IA-32] disallow use of PCI BIOS, only direct
1179 hardware access methods are allowed. Use this
1180 if you experience crashes upon bootup and you
1181 suspect they are caused by the BIOS.
1182 conf1 [IA-32] Force use of PCI Configuration
1183 Mechanism 1.
1184 conf2 [IA-32] Force use of PCI Configuration
1185 Mechanism 2.
61be6d66
BH
1186 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1187 Configuration
309e57df
MW
1188 nomsi [MSI] If the PCI_MSI kernel config parameter is
1189 enabled, this kernel boot option can be used to
1190 disable the use of MSI interrupts system-wide.
a9913044
RD
1191 nosort [IA-32] Don't sort PCI devices according to
1192 order given by the PCI BIOS. This sorting is
1193 done to get a device order compatible with
1194 older kernels.
1195 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1196 routing table. These calls are known to be buggy
1197 on several machines and they hang the machine
1198 when used, but on other computers it's the only
1199 way to get the interrupt routing table. Try
1200 this option if the kernel is unable to allocate
1201 IRQs or discover secondary PCI buses on your
1202 motherboard.
1203 rom [IA-32] Assign address space to expansion ROMs.
1204 Use with caution as certain devices share
1205 address decoders between ROMs and other
1206 resources.
1207 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1208 assigned automatically to PCI devices. You can
1209 make the kernel exclude IRQs of your ISA cards
1210 this way.
120bb424 1211 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1212 of the PIRQ table (normally generated
1213 by the BIOS) if it is outside the
1214 F0000h-100000h range.
1215 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1216 useful if the kernel is unable to find your
1217 secondary buses and you want to tell it
1218 explicitly which ones they are.
1219 assign-busses [IA-32] Always assign all PCI bus
1220 numbers ourselves, overriding
1221 whatever the firmware may have done.
1222 usepirqmask [IA-32] Honor the possible IRQ mask stored
1223 in the BIOS $PIR table. This is needed on
1224 some systems with broken BIOSes, notably
1225 some HP Pavilion N5400 and Omnibook XE3
1226 notebooks. This will have no effect if ACPI
1227 IRQ routing is enabled.
1228 noacpi [IA-32] Do not use ACPI for IRQ routing
1229 or for PCI scanning.
1230 routeirq Do IRQ routing for all PCI devices.
1231 This is normally done in pci_enable_device(),
1232 so this option is a temporary workaround
1233 for broken drivers that don't call it.
1234 firmware [ARM] Do not re-enumerate the bus but instead
1235 just use the configuration from the
1236 bootloader. This is currently used on
1237 IXP2000 systems where the bus has to be
1238 configured a certain way for adjunct CPUs.
0637a70a
AK
1239 noearly [X86] Don't do any early type 1 scanning.
1240 This might help on some broken boards which
1241 machine check when some devices' config space
1242 is read. But various workarounds are disabled
1243 and some IOMMU drivers will not work.
6b4b78fe
MD
1244 bfsort Sort PCI devices into breadth-first order.
1245 This sorting is done to get a device
1246 order compatible with older (<= 2.4) kernels.
1247 nobfsort Don't sort PCI devices into breadth-first order.
1248
1da177e4
LT
1249 pcmv= [HW,PCMCIA] BadgePAD 4
1250
1251 pd. [PARIDE]
1252 See Documentation/paride.txt.
1253
1254 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1255 boot time.
1256 Format: { 0 | 1 }
1257 See arch/parisc/kernel/pdc_chassis.c
1258
1259 pf. [PARIDE]
1260 See Documentation/paride.txt.
1261
1262 pg. [PARIDE]
1263 See Documentation/paride.txt.
1264
1265 pirq= [SMP,APIC] Manual mp-table setup
1266 See Documentation/i386/IO-APIC.txt.
1267
1268 plip= [PPT,NET] Parallel port network link
1269 Format: { parport<nr> | timid | 0 }
1270 See also Documentation/parport.txt.
1271
1272 pnpacpi= [ACPI]
1273 { off }
1274
1275 pnpbios= [ISAPNP]
1276 { on | off | curr | res | no-curr | no-res }
1277
1278 pnp_reserve_irq=
1279 [ISAPNP] Exclude IRQs for the autoconfiguration
1280
1281 pnp_reserve_dma=
1282 [ISAPNP] Exclude DMAs for the autoconfiguration
1283
1284 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1285 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1286
1287 pnp_reserve_mem=
a9913044
RD
1288 [ISAPNP] Exclude memory regions for the
1289 autoconfiguration.
1da177e4
LT
1290 Ranges are in pairs (memory base and size).
1291
1292 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1293 Format: [schedule,]<number>
1294 Param: "schedule" - profile schedule points.
1295 Param: <number> - step/bucket size as a power of 2 for
1296 statistical time based profiling.
1da177e4 1297
a9913044 1298 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1299 Limit processor to maximum C-state
1300 max_cstate=9 overrides any DMI blacklist limit.
1301
41c0d868
LB
1302 processor.nocst [HW,ACPI]
1303 Ignore the _CST method to determine C-states,
1304 instead using the legacy FADT method
1305
1da177e4
LT
1306 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1307 before loading.
1308 See Documentation/ramdisk.txt.
1309
a9913044
RD
1310 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1311 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1312 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1313 per second.
a9913044
RD
1314 psmouse.resetafter= [HW,MOUSE]
1315 Try to reset the device after so many bad packets
1da177e4
LT
1316 (0 = never).
1317 psmouse.resolution=
1318 [HW,MOUSE] Set desired mouse resolution, in dpi.
1319 psmouse.smartscroll=
a9913044 1320 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1321 0 = disabled, 1 = enabled (default).
1322
1323 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1324 Format:
1325 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1326
1327 pt. [PARIDE]
1328 See Documentation/paride.txt.
1329
7d2c502f 1330 quiet [KNL] Disable most log messages
a9913044 1331
1da177e4
LT
1332 r128= [HW,DRM]
1333
1334 raid= [HW,RAID]
1335 See Documentation/md.txt.
1336
1337 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1338 See Documentation/ramdisk.txt.
1339
a9913044 1340 ramdisk_blocksize= [RAM]
1da177e4 1341 See Documentation/ramdisk.txt.
a9913044 1342
1da177e4
LT
1343 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1344 New name for the ramdisk parameter.
1345 See Documentation/ramdisk.txt.
1346
21a1ea9e
DS
1347 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1348 RCU callbacks to process in one batch.
1349
1350 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1351 RCU callbacks over which batch limiting is disabled.
1352
1353 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1354 RCU callbacks below which batch limiting is re-enabled.
1355
ffdfc409
OJ
1356 rdinit= [KNL]
1357 Format: <full_path>
1358 Run specified binary instead of /init from the ramdisk,
1359 used for early userspace startup. See initrd.
1360
1da177e4
LT
1361 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1362 Format: <reboot_mode>[,<reboot_mode2>[,...]]
f3e299fe 1363 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4
LT
1364
1365 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1366
461a9aff
ZA
1367 reservetop= [IA-32]
1368 Format: nn[KMG]
1369 Reserves a hole at the top of the kernel virtual
1370 address space.
1371
7e96287d
VG
1372 reset_devices [KNL] Force drivers to reset the underlying device
1373 during initialization.
1374
a9913044
RD
1375 resume= [SWSUSP]
1376 Specify the partition device for software suspend
1da177e4 1377
ecbd0da1
RW
1378 resume_offset= [SWSUSP]
1379 Specify the offset from the beginning of the partition
1380 given by "resume=" at which the swap header is located,
1381 in <PAGE_SIZE> units (needed only for swap files).
1382 See Documentation/power/swsusp-and-swap-files.txt
1383
1da177e4
LT
1384 rhash_entries= [KNL,NET]
1385 Set number of hash buckets for route cache
1386
1387 riscom8= [HW,SERIAL]
1388 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1389
1390 ro [KNL] Mount root device read-only on boot
1391
1392 root= [KNL] Root filesystem
1393
1394 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1395 mount the root filesystem
1396
1397 rootflags= [KNL] Set root filesystem mount option string
1398
1399 rootfstype= [KNL] Set root filesystem type
1400
1401 rw [KNL] Mount root device read-write on boot
1402
1403 S [KNL] Run init in single mode
1404
1405 sa1100ir [NET]
1406 See drivers/net/irda/sa1100_ir.c.
1407
1408 sb= [HW,OSS]
1409 Format: <io>,<irq>,<dma>,<dma2>
1410
1411 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1412
1da177e4
LT
1413 sbpcd= [HW,CD] Soundblaster CD adapter
1414 Format: <io>,<type>
1415 See a comment before function sbpcd_setup() in
1416 drivers/cdrom/sbpcd.c.
1417
1418 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1419 Format: <io>[,<timeout>[,<isapnp>]]
1420
1421 scsi_debug_*= [SCSI]
1422 See drivers/scsi/scsi_debug.c.
1423
1424 scsi_default_dev_flags=
1425 [SCSI] SCSI default device flags
1426 Format: <integer>
1427
1428 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1429 Format: <vendor>:<model>:<flags>
1430 (flags are integer value)
1431
1432 scsi_logging= [SCSI]
1433
3e082a91
MW
1434 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1435 discovered. async scans them in kernel threads,
1436 allowing boot to proceed. none ignores them, expecting
1437 user space to do the scan.
1438
1da177e4
LT
1439 selinux [SELINUX] Disable or enable SELinux at boot time.
1440 Format: { "0" | "1" }
1441 See security/selinux/Kconfig help text.
1442 0 -- disable.
1443 1 -- enable.
1444 Default value is set via kernel config option.
1445 If enabled at boot time, /selinux/disable can be used
1446 later to disable prior to initial policy load.
1447
4e5ab4cb
JM
1448 selinux_compat_net =
1449 [SELINUX] Set initial selinux_compat_net flag value.
1450 Format: { "0" | "1" }
1451 0 -- use new secmark-based packet controls
1452 1 -- use legacy packet controls
1453 Default value is 0 (preferred).
1454 Value can be changed at runtime via
1455 /selinux/compat_net.
1456
1da177e4
LT
1457 serialnumber [BUGS=IA-32]
1458
a9913044
RD
1459 sg_def_reserved_size= [SCSI]
1460
1da177e4
LT
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 sonycd535= [HW,CD]
1602 Format: <io>[,<irq>]
1603
1604 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1605 See Documentation/sonypi.txt
1606
1607 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1608 See Documentation/specialix.txt.
1609
1610 spia_io_base= [HW,MTD]
1611 spia_fio_base=
1612 spia_pedr=
1613 spia_peddr=
1614
1615 sscape= [HW,OSS]
1616 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1617
1da177e4
LT
1618 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1619 See Documentation/scsi/st.txt.
1620
1621 st0x= [HW,SCSI]
1622 See header of drivers/scsi/seagate.c.
1623
1624 sti= [PARISC,HW]
1625 Format: <num>
1626 Set the STI (builtin display/keyboard on the HP-PARISC
1627 machines) console (graphic card) which should be used
1628 as the initial boot-console.
1629 See also comment in drivers/video/console/sticore.c.
1630
1631 sti_font= [HW]
1632 See comment in drivers/video/console/sticore.c.
1633
1634 stifb= [HW]
1635 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1636
1da177e4 1637 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1638
1da177e4
LT
1639 switches= [HW,M68k]
1640
1641 sym53c416= [HW,SCSI]
1642 See header of drivers/scsi/sym53c416.c.
1643
1644 t128= [HW,SCSI]
1645 See header of drivers/scsi/t128.c.
1646
1647 tdfx= [HW,DRM]
1648
1649 thash_entries= [KNL,NET]
1650 Set number of hash buckets for TCP connection
1651
1652 time Show timing data prefixed to each printk message line
1653
734efb46 1654 clocksource= [GENERIC_TIME] Override the default clocksource
1655 Override the default clocksource and use the clocksource
1656 with the name specified.
1657
1da177e4
LT
1658 tipar.timeout= [HW,PPT]
1659 Set communications timeout in tenths of a second
1660 (default 15).
1661
1662 tipar.delay= [HW,PPT]
1663 Set inter-bit delay in microseconds (default 10).
1664
1665 tmc8xx= [HW,SCSI]
1666 See header of drivers/scsi/seagate.c.
1667
1668 tmscsim= [HW,SCSI]
1669 See comment before function dc390_setup() in
1670 drivers/scsi/tmscsim.c.
1671
1672 tp720= [HW,PS2]
1673
1674 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1675 Format:
1676 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1677
1da177e4
LT
1678 tsdev.xres= [TS] Horizontal screen resolution.
1679 tsdev.yres= [TS] Vertical screen resolution.
1680
a9913044
RD
1681 turbografx.map[2|3]= [HW,JOY]
1682 TurboGraFX parallel port interface
1683 Format:
1684 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1685 See also Documentation/input/joystick-parport.txt
1686
1687 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1688 See header of drivers/scsi/u14-34f.c.
1689
1690 uart401= [HW,OSS]
1691 Format: <io>,<irq>
1692
1693 uart6850= [HW,OSS]
1694 Format: <io>,<irq>
1695
1da177e4
LT
1696 usbhid.mousepoll=
1697 [USBHID] The interval which mice are to be polled at.
a9913044 1698
e6e5494c
IM
1699 vdso= [IA-32]
1700 vdso=1: enable VDSO (default)
1701 vdso=0: disable VDSO mapping
1702
1da177e4
LT
1703 video= [FB] Frame buffer configuration
1704 See Documentation/fb/modedb.txt.
1705
1706 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1707 See Documentation/i386/boot.txt and
1708 Documentation/svga.txt.
1da177e4
LT
1709 Use vga=ask for menu.
1710 This is actually a boot loader parameter; the value is
1711 passed to the kernel using a special protocol.
1712
a9913044 1713 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1714 size of <nn>. This can be used to increase the
1715 minimum size (128MB on x86). It can also be used to
1716 decrease the size and leave more room for directly
1717 mapped kernel RAM.
1718
585c3047
PO
1719 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1720 Format: <command>
1da177e4 1721
585c3047
PO
1722 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1723 Format: <command>
1724
1725 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1726 Format: <command>
a9913044 1727
1da177e4
LT
1728 waveartist= [HW,OSS]
1729 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1730
1da177e4
LT
1731 wd33c93= [HW,SCSI]
1732 See header of drivers/scsi/wd33c93.c.
1733
1734 wd7000= [HW,SCSI]
1735 See header of drivers/scsi/wd7000.c.
1736
1737 wdt= [WDT] Watchdog
1738 See Documentation/watchdog/watchdog.txt.
1739
1740 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1741 xd_geo= See header of drivers/block/xd.c.
1742
1743 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1744 Format:
1745 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1746
a62eaf15
AK
1747 norandmaps Don't use address space randomization
1748 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1749
1da177e4 1750
a9913044 1751______________________________________________________________________
1da177e4
LT
1752
1753TODO:
1754
1755 Add documentation for ALSA options.
1756 Add more DRM drivers.