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0ee9d71f 1 Kernel Parameters
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2 ~~~~~~~~~~~~~~~~~
3
4The following is a consolidated list of the kernel parameters as implemented
5(mostly) by the __setup() macro and sorted into English Dictionary order
6(defined as ignoring all punctuation and sorting digits before letters in a
7case insensitive manner), and with descriptions where known.
8
9Module parameters for loadable modules are specified only as the
10parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14Module parameters for modules that are built into the kernel image
15are specified on the kernel command line with the module name plus
16'.' plus parameter name, with '=' and value if appropriate, such as:
17
18 usbcore.blinkenlights=1
19
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20This document may not be entirely up to date and comprehensive. The command
21"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22module. Loadable modules, after being loaded into the running kernel, also
23reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24parameters may be changed at runtime by the command
25"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
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27The parameters listed below are only valid if certain kernel build options were
28enabled and if respective hardware is present. The text in square brackets at
29the beginning of each description states the restrictions within which a
30parameter is applicable:
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31
32 ACPI ACPI support is enabled.
33 ALSA ALSA sound support is enabled.
34 APIC APIC support is enabled.
35 APM Advanced Power Management support is enabled.
36 AX25 Appropriate AX.25 support is enabled.
37 CD Appropriate CD support is enabled.
a9913044 38 DRM Direct Rendering Management support is enabled.
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39 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
40 EFI EFI Partitioning (GPT) is enabled
41 EIDE EIDE/ATAPI support is enabled.
42 FB The frame buffer device is enabled.
43 HW Appropriate hardware is enabled.
44 IA-32 IA-32 aka i386 architecture is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
41e2e8be 47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LP Printer support is enabled.
52 LOOP Loopback device support is enabled.
53 M68k M68k architecture is enabled.
54 These options have more detailed description inside of
55 Documentation/m68k/kernel-options.txt.
56 MCA MCA bus support is enabled.
57 MDA MDA console support is enabled.
58 MOUSE Appropriate mouse support is enabled.
309e57df 59 MSI Message Signaled Interrupts (PCI).
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60 MTD MTD support is enabled.
61 NET Appropriate network support is enabled.
62 NUMA NUMA support is enabled.
734efb46 63 GENERIC_TIME The generic timeofday code is enabled.
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64 NFS Appropriate NFS support is enabled.
65 OSS OSS sound support is enabled.
66 PARIDE The ParIDE subsystem is enabled.
67 PARISC The PA-RISC architecture is enabled.
68 PCI PCI bus support is enabled.
69 PCMCIA The PCMCIA subsystem is enabled.
70 PNP Plug & Play support is enabled.
71 PPC PowerPC architecture is enabled.
72 PPT Parallel port support is enabled.
73 PS2 Appropriate PS/2 support is enabled.
74 RAM RAM disk support is enabled.
75 S390 S390 architecture is enabled.
76 SCSI Appropriate SCSI support is enabled.
77 A lot of drivers has their options described inside of
78 Documentation/scsi/.
79 SELINUX SELinux support is enabled.
80 SERIAL Serial support is enabled.
81 SMP The kernel is an SMP kernel.
82 SPARC Sparc architecture is enabled.
a9913044 83 SWSUSP Software suspend is enabled.
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84 TS Appropriate touchscreen support is enabled.
85 USB USB support is enabled.
86 USBHID USB Human Interface Device support is enabled.
87 V4L Video For Linux support is enabled.
88 VGA The VGA console has been enabled.
89 VT Virtual terminal support is enabled.
90 WDT Watchdog support is enabled.
91 XT IBM PC/XT MFM hard disk support is enabled.
92 X86-64 X86-64 architecture is enabled.
93 More X86-64 boot options can be found in
94 Documentation/x86_64/boot-options.txt .
95
96In addition, the following text indicates that the option:
97
98 BUGS= Relates to possible processor bugs on the said processor.
99 KNL Is a kernel start-up parameter.
100 BOOT Is a boot loader parameter.
101
102Parameters denoted with BOOT are actually interpreted by the boot
103loader, and have no meaning to the kernel directly.
104Do not modify the syntax of boot loader parameters without extreme
105need or coordination with <Documentation/i386/boot.txt>.
106
107Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
108a trailing = on the name of any parameter states that that parameter will
109be entered as an environment variable, whereas its absence indicates that
110it will appear as a kernel argument readable via /proc/cmdline by programs
111running once the system is up.
112
9c4751fd 113The number of kernel parameters is not limited, but the length of the
114complete command line (parameters including spaces etc.) is limited to
115a fixed number of characters. This limit depends on the architecture
116and is between 256 and 4096 characters. It is defined in the file
117./include/asm/setup.h as COMMAND_LINE_SIZE.
118
119
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120 53c7xx= [HW,SCSI] Amiga SCSI controllers
121 See header of drivers/scsi/53c7xx.c.
122 See also Documentation/scsi/ncr53c7xx.txt.
123
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124 acpi= [HW,ACPI] Advanced Configuration and Power Interface
125 Format: { force | off | ht | strict | noirq }
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126 force -- enable ACPI if default was off
127 off -- disable ACPI if default was on
128 noirq -- do not use ACPI for IRQ routing
129 ht -- run only enough ACPI to enable Hyper Threading
a9913044 130 strict -- Be less tolerant of platforms that are not
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131 strictly ACPI specification compliant.
132
133 See also Documentation/pm.txt, pci=noacpi
134
135 acpi_sleep= [HW,ACPI] Sleep options
136 Format: { s3_bios, s3_mode }
137 See Documentation/power/video.txt
a9913044 138
1da177e4 139 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
a9913044 140 Format: { level | edge | high | low }
1da177e4 141
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142 acpi_irq_balance [HW,ACPI]
143 ACPI will balance active IRQs
144 default in APIC mode
1da177e4 145
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146 acpi_irq_nobalance [HW,ACPI]
147 ACPI will not move active IRQs (default)
148 default in PIC mode
1da177e4 149
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150 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
151 use by PCI
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152 Format: <irq>,<irq>...
153
a9913044 154 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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155 Format: <irq>,<irq>...
156
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157 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
158 Format: To spoof as Windows 98: ="Microsoft Windows"
159
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160 acpi_osi= [HW,ACPI] empty param disables _OSI
161
162 acpi_serialize [HW,ACPI] force serialization of AML methods
163
164 acpi_skip_timer_override [HW,ACPI]
165 Recognize and ignore IRQ0/pin2 Interrupt Override.
166 For broken nForce2 BIOS resulting in XT-PIC timer.
167
168 acpi_dbg_layer= [HW,ACPI]
169 Format: <int>
a9913044 170 Each bit of the <int> indicates an ACPI debug layer,
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171 1: enable, 0: disable. It is useful for boot time
172 debugging. After system has booted up, it can be set
173 via /proc/acpi/debug_layer.
174
175 acpi_dbg_level= [HW,ACPI]
176 Format: <int>
a9913044 177 Each bit of the <int> indicates an ACPI debug level,
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178 1: enable, 0: disable. It is useful for boot time
179 debugging. After system has booted up, it can be set
180 via /proc/acpi/debug_level.
181
182 acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
183
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184 acpi_generic_hotkey [HW,ACPI]
185 Allow consolidated generic hotkey driver to
a9913044 186 override platform specific driver.
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187 See also Documentation/acpi-hotkey.txt.
188
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189 acpi_pm_good [IA-32,X86-64]
190 Override the pmtimer bug detection: force the kernel
191 to assume that this machine's pmtimer latches its value
192 and always returns good values.
193
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194 enable_timer_pin_1 [i386,x86-64]
195 Enable PIN 1 of APIC timer
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196 Can be useful to work around chipset bugs
197 (in particular on some ATI chipsets).
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198 The kernel tries to set a reasonable default.
199
200 disable_timer_pin_1 [i386,x86-64]
201 Disable PIN 1 of APIC timer
202 Can be useful to work around chipset bugs.
203
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204 ad1816= [HW,OSS]
205 Format: <io>,<irq>,<dma>,<dma2>
206 See also Documentation/sound/oss/AD1816.
207
208 ad1848= [HW,OSS]
209 Format: <io>,<irq>,<dma>,<dma2>,<type>
210
211 adlib= [HW,OSS]
212 Format: <io>
a9913044 213
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214 advansys= [HW,SCSI]
215 See header of drivers/scsi/advansys.c.
216
217 advwdt= [HW,WDT] Advantech WDT
218 Format: <iostart>,<iostop>
219
220 aedsp16= [HW,OSS] Audio Excel DSP 16
221 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
222 See also header of sound/oss/aedsp16.c.
a9913044 223
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224 aha152x= [HW,SCSI]
225 See Documentation/scsi/aha152x.txt.
226
227 aha1542= [HW,SCSI]
228 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
229
230 aic7xxx= [HW,SCSI]
231 See Documentation/scsi/aic7xxx.txt.
232
233 aic79xx= [HW,SCSI]
234 See Documentation/scsi/aic79xx.txt.
235
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236 amijoy.map= [HW,JOY] Amiga joystick support
237 Map of devices attached to JOY0DAT and JOY1DAT
238 Format: <a>,<b>
239 See also Documentation/kernel/input/joystick.txt
240
241 analog.map= [HW,JOY] Analog joystick and gamepad support
242 Specifies type or capabilities of an analog joystick
243 connected to one of 16 gameports
244 Format: <type1>,<type2>,..<type16>
245
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246 apc= [HW,SPARC]
247 Power management functions (SPARCstation-4/5 + deriv.)
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248 Format: noidle
249 Disable APC CPU standby support. SPARCstation-Fox does
250 not play well with APC CPU idle - disable it if you have
251 APC and your system crashes randomly.
252
a9913044 253 apic= [APIC,i386] Change the output verbosity whilst booting
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254 Format: { quiet (default) | verbose | debug }
255 Change the amount of debugging information output
256 when initialising the APIC and IO-APIC components.
a9913044 257
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258 apm= [APM] Advanced Power Management
259 See header of arch/i386/kernel/apm.c.
260
261 applicom= [HW]
262 Format: <mem>,<irq>
a9913044 263
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264 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
265 Format: <io>,<irq>,<nodeID>
266
267 ataflop= [HW,M68k]
268
269 atarimouse= [HW,MOUSE] Atari Mouse
270
271 atascsi= [HW,SCSI] Atari SCSI
272
273 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
274 EzKey and similar keyboards
275
276 atkbd.reset= [HW] Reset keyboard during initialization
277
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278 atkbd.set= [HW] Select keyboard code set
279 Format: <int> (2 = AT (default), 3 = PS/2)
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280
281 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
282 keyboards
283
284 atkbd.softraw= [HW] Choose between synthetic and real raw mode
285 Format: <bool> (0 = real, 1 = synthetic (default))
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286
287 atkbd.softrepeat= [HW]
288 Use software keyboard repeat
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289
290 autotest [IA64]
291
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292 aztcd= [HW,CD] Aztech CD268 CDROM driver
293 Format: <io>,0x79 (?)
294
295 baycom_epp= [HW,AX25]
296 Format: <io>,<mode>
a9913044 297
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298 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
299 Format: <io>,<mode>
300 See header of drivers/net/hamradio/baycom_par.c.
301
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302 baycom_ser_fdx= [HW,AX25]
303 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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304 Format: <io>,<irq>,<mode>[,<baud>]
305 See header of drivers/net/hamradio/baycom_ser_fdx.c.
306
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307 baycom_ser_hdx= [HW,AX25]
308 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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309 Format: <io>,<irq>,<mode>
310 See header of drivers/net/hamradio/baycom_ser_hdx.c.
311
312 blkmtd_device= [HW,MTD]
313 blkmtd_erasesz=
314 blkmtd_ro=
315 blkmtd_bs=
316 blkmtd_count=
317
318 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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319 bttv.radio= Most important insmod options are available as
320 kernel args too.
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321 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
322 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
323
324 BusLogic= [HW,SCSI]
325 See drivers/scsi/BusLogic.c, comment before function
326 BusLogic_ParseDriverOptions().
327
328 c101= [NET] Moxa C101 synchronous serial card
329
330 cachesize= [BUGS=IA-32] Override level 2 CPU cache size detection.
331 Sometimes CPU hardware bugs make them report the cache
332 size incorrectly. The kernel will attempt work arounds
333 to fix known problems, but for some CPUs it is not
334 possible to determine what the correct size should be.
335 This option provides an override for these situations.
336
337 cdu31a= [HW,CD]
338 Format: <io>,<irq>[,PAS]
339 See header of drivers/cdrom/cdu31a.c.
340
341 chandev= [HW,NET] Generic channel device initialisation
342
343 checkreqprot [SELINUX] Set initial checkreqprot flag value.
344 Format: { "0" | "1" }
345 See security/selinux/Kconfig help text.
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346 0 -- check protection applied by kernel (includes
347 any implied execute protection).
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348 1 -- check protection requested by application.
349 Default value is set via a kernel config option.
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350 Value can be changed at runtime via
351 /selinux/checkreqprot.
352
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353 clock= [BUGS=IA-32, HW] gettimeofday clocksource override.
354 [Deprecated]
3f6dee9b 355 Forces specified clocksource (if available) to be used
734efb46 356 when calculating gettimeofday(). If specified
3f6dee9b 357 clocksource is not available, it defaults to PIT.
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358 Format: { pit | tsc | cyclone | pmtmr }
359
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360 disable_8254_timer
361 enable_8254_timer
362 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
363 over the 8254 in addition to over the IO-APIC. The
364 kernel tries to set a sensible default.
365
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366 hpet= [IA-32,HPET] option to disable HPET and use PIT.
367 Format: disable
368
369 cm206= [HW,CD]
370 Format: { auto | [<io>,][<irq>] }
371
372 com20020= [HW,NET] ARCnet - COM20020 chipset
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373 Format:
374 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
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375
376 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
377 Format: <io>[,<irq>]
378
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379 com90xx= [HW,NET]
380 ARCnet - COM90xx chipset (memory-mapped buffers)
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381 Format: <io>[,<irq>[,<memstart>]]
382
383 condev= [HW,S390] console device
384 conmode=
a9913044 385
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386 console= [KNL] Output console device and options.
387
388 tty<n> Use the virtual console device <n>.
389
390 ttyS<n>[,options]
f1a1c2dc 391 ttyUSB0[,options]
1da177e4 392 Use the specified serial port. The options are of
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393 the form "bbbbpnf", where "bbbb" is the baud rate,
394 "p" is parity ("n", "o", or "e"), "n" is number of
395 bits, and "f" is flow control ("r" for RTS or
396 omit it). Default is "9600n8".
397
398 See Documentation/serial-console.txt for more
399 information. See
400 Documentation/networking/netconsole.txt for an
401 alternative.
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402
403 uart,io,<addr>[,options]
404 uart,mmio,<addr>[,options]
405 Start an early, polled-mode console on the 8250/16550
406 UART at the specified I/O port or MMIO address,
407 switching to the matching ttyS device later. The
408 options are the same as for ttyS, above.
409
410 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
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411 Format:
412 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
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413
414 cpia_pp= [HW,PPT]
415 Format: { parport<nr> | auto | none }
416
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417 crashkernel=nn[KMG]@ss[KMG]
418 [KNL] Reserve a chunk of physical memory to
419 hold a kernel to switch to with kexec on panic.
420
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421 cs4232= [HW,OSS]
422 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
423
424 cs89x0_dma= [HW,NET]
425 Format: <dma>
426
427 cs89x0_media= [HW,NET]
428 Format: { rj45 | aui | bnc }
a9913044 429
1da177e4 430 cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
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431
432 dasd= [HW,NET]
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433 See header of drivers/s390/block/dasd_devmap.c.
434
435 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
436 (one device per port)
437 Format: <port#>,<type>
438 See also Documentation/input/joystick-parport.txt
439
440 debug [KNL] Enable kernel debugging (events log level).
441
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442 debug_locks_verbose=
443 [KNL] verbose self-tests
444 Format=<0|1>
445 Print debugging info while doing the locking API
446 self-tests.
447 We default to 0 (no extra messages), setting it to
448 1 will print _a lot_ more information - normally
449 only useful to kernel developers.
450
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451 decnet= [HW,NET]
452 Format: <area>[,<node>]
453 See also Documentation/networking/decnet.txt.
454
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455 dhash_entries= [KNL]
456 Set number of hash buckets for dentry cache.
a9913044 457
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458 digi= [HW,SERIAL]
459 IO parameters + enable/disable command.
460
461 digiepca= [HW,SERIAL]
462 See drivers/char/README.epca and
463 Documentation/digiepca.txt.
464
465 dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA
466 support available.
467 Format: <io_dev0>[,<io_dev1>[,..<io_dev32>]]
468
469 dmasound= [HW,OSS] Sound subsystem buffers
470
471 dscc4.setup= [NET]
472
473 dtc3181e= [HW,SCSI]
474
a9913044 475 earlyprintk= [IA-32,X86-64]
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476 earlyprintk=vga
477 earlyprintk=serial[,ttySn[,baudrate]]
478
a9913044 479 Append ",keep" to not disable it when the real console
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480 takes over.
481
482 Only vga or serial at a time, not both.
483
484 Currently only ttyS0 and ttyS1 are supported.
485
486 Interaction with the standard serial driver is not
487 very good.
488
489 The VGA output is eventually overwritten by the real
490 console.
491
492 eata= [HW,SCSI]
493
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494 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
495 Format: <int>
496 0: polling mode
497 non-0: interrupt mode (default)
498
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499 eda= [HW,PS2]
500
501 edb= [HW,PS2]
502
503 edd= [EDD]
504 Format: {"of[f]" | "sk[ipmbr]"}
505 See comment in arch/i386/boot/edd.S
506
a9913044 507 eicon= [HW,ISDN]
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508 Format: <id>,<membase>,<irq>
509
510 eisa_irq_edge= [PARISC,HW]
511 See header of drivers/parisc/eisa.c.
512
513 elanfreq= [IA-32]
514 See comment before function elanfreq_setup() in
515 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
516
517 elevator= [IOSCHED]
16ab3adf 518 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
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519 See Documentation/block/as-iosched.txt and
520 Documentation/block/deadline-iosched.txt for details.
521
aac04b32 522 elfcorehdr= [IA-32, X86_64]
a9913044 523 Specifies physical address of start of kernel core
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524 image elf header. Generally kexec loader will
525 pass this option to capture kernel.
526 See Documentation/kdump/kdump.txt for details.
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527
528 enforcing [SELINUX] Set initial enforcing status.
529 Format: {"0" | "1"}
530 See security/selinux/Kconfig help text.
531 0 -- permissive (log only, no denials).
532 1 -- enforcing (deny and log).
533 Default value is 0.
534 Value can be changed at runtime via /selinux/enforce.
535
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536 es1371= [HW,OSS]
537 Format: <spdif>,[<nomix>,[<amplifier>]]
538 See also header of sound/oss/es1371.c.
a9913044 539
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540 ether= [HW,NET] Ethernet cards parameters
541 This option is obsoleted by the "netdev=" option, which
542 has equivalent usage. See its documentation for details.
543
544 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
545 Format: <io>[,<irq>]
546
547 fd_mcs= [HW,SCSI]
548 See header of drivers/scsi/fd_mcs.c.
549
550 fdomain= [HW,SCSI]
551 See header of drivers/scsi/fdomain.c.
552
553 floppy= [HW]
554 See Documentation/floppy.txt.
555
556 ftape= [HW] Floppy Tape subsystem debugging options.
557 See Documentation/ftape.txt.
558
559 gamecon.map[2|3]=
560 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
561 support via parallel port (up to 5 devices per port)
562 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
563 See also Documentation/input/joystick-parport.txt
564
565 gamma= [HW,DRM]
566
567 gdth= [HW,SCSI]
568 See header of drivers/scsi/gdth.c.
569
570 gpt [EFI] Forces disk with valid GPT signature but
571 invalid Protective MBR to be treated as GPT.
572
573 gscd= [HW,CD]
574 Format: <io>
575
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576 gvp11= [HW,SCSI]
577
578 hashdist= [KNL,NUMA] Large hashes allocated during boot
579 are distributed across NUMA nodes. Defaults on
580 for IA-64, off otherwise.
a9913044 581 Format: 0 | 1 (for off | on)
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582
583 hcl= [IA-64] SGI's Hardware Graph compatibility layer
584
585 hd= [EIDE] (E)IDE hard drive subsystem geometry
586 Format: <cyl>,<head>,<sect>
587
588 hd?= [HW] (E)IDE subsystem
589 hd?lun= See Documentation/ide.txt.
590
591 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
592 size of <nn>. This works even on boxes that have no
593 highmem otherwise. This also works to reduce highmem
594 size on bigger boxes.
595
596 hisax= [HW,ISDN]
597 See Documentation/isdn/README.HiSax.
598
599 hugepages= [HW,IA-32,IA-64] Maximal number of HugeTLB pages.
600
601 noirqbalance [IA-32,SMP,KNL] Disable kernel irq balancing
602
603 i8042.direct [HW] Put keyboard port into non-translated mode
84eb8d06
ML
604 i8042.dumbkbd [HW] Pretend that controller can only read data from
605 keyboard and cannot control its state
1da177e4
LT
606 (Don't attempt to blink the leds)
607 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
945ef0d4 608 i8042.nokbd [HW] Don't check/create keyboard port
1da177e4
LT
609 i8042.nomux [HW] Don't check presence of an active multiplexing
610 controller
611 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
612 controllers
613 i8042.panicblink=
614 [HW] Frequency with which keyboard LEDs should blink
615 when kernel panics (default is 0.5 sec)
616 i8042.reset [HW] Reset the controller during init and cleanup
617 i8042.unlock [HW] Unlock (ignore) the keylock
618
619 i810= [HW,DRM]
620
e70c9d5e
DT
621 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
622 indicates that the driver is running on unsupported
623 hardware.
1da177e4
LT
624 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
625 does not match list of supported models.
626 i8k.power_status
627 [HW] Report power status in /proc/i8k
628 (disabled by default)
629 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
630 capability is set.
631
632 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
633 See Documentation/mca.txt.
634
635 icn= [HW,ISDN]
636 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
637
638 ide= [HW] (E)IDE subsystem
639 Format: ide=nodma or ide=doubler or ide=reverse
640 See Documentation/ide.txt.
641
642 ide?= [HW] (E)IDE subsystem
643 Format: ide?=noprobe or chipset specific parameters.
644 See Documentation/ide.txt.
a9913044 645
1da177e4
LT
646 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
647 See Documentation/ide.txt.
648
649 idle= [HW]
650 Format: idle=poll or idle=halt
a9913044 651
1da177e4
LT
652 ihash_entries= [KNL]
653 Set number of hash buckets for inode cache.
654
655 in2000= [HW,SCSI]
656 See header of drivers/scsi/in2000.c.
657
658 init= [KNL]
659 Format: <full_path>
660 Run specified binary instead of /sbin/init as init
661 process.
662
663 initcall_debug [KNL] Trace initcalls as they are executed. Useful
664 for working out where the kernel is dying during
665 startup.
666
667 initrd= [BOOT] Specify the location of the initial ramdisk
668
669 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
670 Format: <irq>
671
2bd0fa3b
JB
672 combined_mode= [HW] control which driver uses IDE ports in combined
673 mode: legacy IDE driver, libata, or both
674 (in the libata case, libata.atapi_enabled=1 may be
675 useful as well). Note that using the ide or libata
676 options may affect your device naming (e.g. by
677 changing hdc to sdb).
678 Format: combined (default), ide, or libata
679
1da177e4
LT
680 inttest= [IA64]
681
682 io7= [HW] IO7 for Marvel based alpha systems
683 See comment before marvel_specify_io7 in
684 arch/alpha/kernel/core_marvel.c.
685
686 ip= [IP_PNP]
687 See Documentation/nfsroot.txt.
688
689 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
690 See comment before ip2_setup() in drivers/char/ip2.c.
691
692 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
693 See header of drivers/scsi/ips.c.
694
72c4a13a
SH
695 ports= [IP_VS_FTP] IPVS ftp helper module
696 Default is 21.
697 Up to 8 (IP_VS_APP_MAX_PORTS) ports
698 may be specified.
699 Format: <port>,<port>....
700
200803df
AC
701 irqfixup [HW]
702 When an interrupt is not handled search all handlers
703 for it. Intended to get systems with badly broken
704 firmware running.
705
706 irqpoll [HW]
707 When an interrupt is not handled search all handlers
708 for it. Also check all handlers each timer
709 interrupt. Intended to get systems with badly broken
710 firmware running.
711
1da177e4 712 isapnp= [ISAPNP]
a9913044 713 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1da177e4
LT
714
715 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
716 Format: <cpu number>,...,<cpu number>
717 This option can be used to specify one or more CPUs
718 to isolate from the general SMP balancing and scheduling
719 algorithms. The only way to move a process onto or off
720 an "isolated" CPU is via the CPU affinity syscalls.
721 <cpu number> begins at 0 and the maximum value is
722 "number of CPUs in system - 1".
723
724 This option is the preferred way to isolate CPUs. The
a9913044
RD
725 alternative -- manually setting the CPU mask of all
726 tasks in the system -- can cause problems and
727 suboptimal load balancer performance.
1da177e4
LT
728
729 isp16= [HW,CD]
730 Format: <io>,<irq>,<dma>,<setup>
731
a9913044 732 iucv= [HW,NET]
1da177e4
LT
733
734 js= [HW,JOY] Analog joystick
735 See Documentation/input/joystick.txt.
736
737 keepinitrd [HW,ARM]
738
a9913044 739 kstack=N [IA-32,X86-64] Print N words from the kernel stack
1da177e4
LT
740 in oops dumps.
741
742 l2cr= [PPC]
743
a9913044
RD
744 lapic [IA-32,APIC] Enable the local APIC even if BIOS
745 disabled it.
1da177e4
LT
746
747 lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
748 Format: addr:<io>,irq:<irq>
749
a9913044
RD
750 llsc*= [IA64] See function print_params() in
751 arch/ia64/sn/kernel/llsc4.c.
1da177e4
LT
752
753 load_ramdisk= [RAM] List of ramdisks to load from floppy
754 See Documentation/ramdisk.txt.
755
a6b25b67
RD
756 lockd.nlm_grace_period=P [NFS] Assign grace period.
757 Format: <integer>
1da177e4 758
a6b25b67
RD
759 lockd.nlm_tcpport=N [NFS] Assign TCP port.
760 Format: <integer>
761
762 lockd.nlm_timeout=T [NFS] Assign timeout value.
763 Format: <integer>
764
765 lockd.nlm_udpport=M [NFS] Assign UDP port.
766 Format: <integer>
1da177e4
LT
767
768 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
769 Format: <irq>
770
771 loglevel= All Kernel Messages with a loglevel smaller than the
772 console loglevel will be printed to the console. It can
773 also be changed with klogd or other programs. The
774 loglevels are defined as follows:
775
776 0 (KERN_EMERG) system is unusable
777 1 (KERN_ALERT) action must be taken immediately
778 2 (KERN_CRIT) critical conditions
779 3 (KERN_ERR) error conditions
780 4 (KERN_WARNING) warning conditions
781 5 (KERN_NOTICE) normal but significant condition
782 6 (KERN_INFO) informational
783 7 (KERN_DEBUG) debug-level messages
784
785 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
a9913044
RD
786 Format: { n | nk | nM }
787 n must be a power of two. The default size
788 is set in the kernel config file.
1da177e4
LT
789
790 lp=0 [LP] Specify parallel ports to use, e.g,
791 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
792 lp=reset first parallel port). 'lp=0' disables the
793 lp=auto printer driver. 'lp=reset' (which can be
794 specified in addition to the ports) causes
795 attached printers to be reset. Using
796 lp=port1,port2,... specifies the parallel ports
797 to associate lp devices with, starting with
798 lp0. A port specification may be 'none' to skip
799 that lp device, or a parport name such as
800 'parport0'. Specifying 'lp=auto' instead of a
801 port specification list means that device IDs
802 from each port should be examined, to see if
803 an IEEE 1284-compliant printer is attached; if
804 so, the driver will manage that printer.
805 See also header of drivers/char/lp.c.
806
807 lpj=n [KNL]
808 Sets loops_per_jiffy to given constant, thus avoiding
809 time-consuming boot-time autodetection (up to 250 ms per
810 CPU). 0 enables autodetection (default). To determine
811 the correct value for your kernel, boot with normal
812 autodetection and see what value is printed. Note that
813 on SMP systems the preset will be applied to all CPUs,
814 which is likely to cause problems if your CPUs need
815 significantly divergent settings. An incorrect value
816 will cause delays in the kernel to be wrong, leading to
817 unpredictable I/O errors and other breakage. Although
818 unlikely, in the extreme case this might damage your
819 hardware.
820
821 ltpc= [NET]
822 Format: <io>,<irq>,<dma>
823
a9913044
RD
824 mac5380= [HW,SCSI] Format:
825 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 826
a9913044
RD
827 mac53c9x= [HW,SCSI] Format:
828 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1da177e4 829
a9913044
RD
830 machvec= [IA64] Force the use of a particular machine-vector
831 (machvec) in a generic kernel.
832 Example: machvec=hpzx1_swiotlb
1da177e4 833
a9913044 834 max_loop= [LOOP] Maximum number of loopback devices that can
1da177e4
LT
835 be mounted
836 Format: <1-256>
837
838 maxcpus= [SMP] Maximum number of processors that an SMP kernel
839 should make use of
840
2b2c3750
BP
841 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
842 equal to this physical address is ignored.
843
a9913044 844 max_luns= [SCSI] Maximum number of LUNs to probe.
1da177e4
LT
845 Should be between 1 and 2^32-1.
846
847 max_report_luns=
a9913044 848 [SCSI] Maximum number of LUNs received.
1da177e4
LT
849 Should be between 1 and 16384.
850
851 mca-pentium [BUGS=IA-32]
852
853 mcatest= [IA-64]
854
855 mcd= [HW,CD]
856 Format: <port>,<irq>,<mitsumi_bug_93_wait>
857
858 mcdx= [HW,CD]
859
860 mce [IA-32] Machine Check Exception
861
862 md= [HW] RAID subsystems devices and level
863 See Documentation/md.txt.
a9913044 864
1da177e4
LT
865 mdacon= [MDA]
866 Format: <first>,<last>
867 Specifies range of consoles to be captured by the MDA.
a9913044 868
1da177e4
LT
869 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
870 Amount of memory to be used when the kernel is not able
871 to see the whole system memory or for test.
872 [IA-32] Use together with memmap= to avoid physical
873 address space collisions. Without memmap= PCI devices
874 could be placed at addresses belonging to unused RAM.
875
876 mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
877 memory.
878
69cda7b1 879 memmap=exactmap [KNL,IA-32,X86_64] Enable setting of an exact
1da177e4
LT
880 E820 memory map, as specified by the user.
881 Such memmap=exactmap lines can be constructed based on
882 BIOS output or other requirements. See the memmap=nn@ss
883 option description.
884
885 memmap=nn[KMG]@ss[KMG]
886 [KNL] Force usage of a specific region of memory
887 Region of memory to be used, from ss to ss+nn.
888
889 memmap=nn[KMG]#ss[KMG]
890 [KNL,ACPI] Mark specific memory as ACPI data.
891 Region of memory to be used, from ss to ss+nn.
892
893 memmap=nn[KMG]$ss[KMG]
894 [KNL,ACPI] Mark specific memory as reserved.
895 Region of memory to be used, from ss to ss+nn.
896
897 meye.*= [HW] Set MotionEye Camera parameters
898 See Documentation/video4linux/meye.txt.
899
900 mga= [HW,DRM]
901
198e2f18 902 migration_cost=
903 [KNL,SMP] debug: override scheduler migration costs
904 Format: <level-1-usecs>,<level-2-usecs>,...
905 This debugging option can be used to override the
906 default scheduler migration cost matrix. The numbers
907 are indexed by 'CPU domain distance'.
908 E.g. migration_cost=1000,2000,3000 on an SMT NUMA
909 box will set up an intra-core migration cost of
910 1 msec, an inter-core migration cost of 2 msecs,
911 and an inter-node migration cost of 3 msecs.
912
913 WARNING: using the wrong values here can break
914 scheduler performance, so it's only for scheduler
915 development purposes, not production environments.
916
917 migration_debug=
918 [KNL,SMP] migration cost auto-detect verbosity
919 Format=<0|1|2>
920 If a system's migration matrix reported at bootup
921 seems erroneous then this option can be used to
922 increase verbosity of the detection process.
923 We default to 0 (no extra messages), 1 will print
924 some more information, and 2 will be really
925 verbose (probably only useful if you also have a
926 serial console attached to the system).
927
928 migration_factor=
929 [KNL,SMP] multiply/divide migration costs by a factor
930 Format=<percent>
931 This debug option can be used to proportionally
932 increase or decrease the auto-detected migration
933 costs for all entries of the migration matrix.
934 E.g. migration_factor=150 will increase migration
935 costs by 50%. (and thus the scheduler will be less
936 eager migrating cache-hot tasks)
937 migration_factor=80 will decrease migration costs
938 by 20%. (thus the scheduler will be more eager to
939 migrate tasks)
940
941 WARNING: using the wrong values here can break
942 scheduler performance, so it's only for scheduler
943 development purposes, not production environments.
944
1da177e4
LT
945 mousedev.tap_time=
946 [MOUSE] Maximum time between finger touching and
947 leaving touchpad surface for touch to be considered
948 a tap and be reported as a left button click (for
949 touchpads working in absolute mode only).
950 Format: <msecs>
951 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
952 reporting absolute coordinates, such as tablets
953 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
954 reporting absolute coordinates, such as tablets
955
956 mpu401= [HW,OSS]
957 Format: <io>,<irq>
958
959 MTD_Partition= [MTD]
960 Format: <name>,<region-number>,<size>,<offset>
961
a9913044
RD
962 MTD_Region= [MTD] Format:
963 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1da177e4
LT
964
965 mtdparts= [MTD]
966 See drivers/mtd/cmdline.c.
967
968 mtouchusb.raw_coordinates=
a9913044
RD
969 [HW] Make the MicroTouch USB driver use raw coordinates
970 ('y', default) or cooked coordinates ('n')
1da177e4
LT
971
972 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
973
974 NCR_D700= [HW,SCSI]
975 See header of drivers/scsi/NCR_D700.c.
976
977 ncr5380= [HW,SCSI]
978
979 ncr53c400= [HW,SCSI]
980
981 ncr53c400a= [HW,SCSI]
982
983 ncr53c406a= [HW,SCSI]
984
985 ncr53c8xx= [HW,SCSI]
986
987 netdev= [NET] Network devices parameters
988 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
989 Note that mem_start is often overloaded to mean
990 something different and driver-specific.
a9913044
RD
991 This usage is only documented in each driver source
992 file if at all.
993
1da177e4
LT
994 nfsaddrs= [NFS]
995 See Documentation/nfsroot.txt.
996
997 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
998 See Documentation/nfsroot.txt.
999
a72b4422
TM
1000 nfs.callback_tcpport=
1001 [NFS] set the TCP port on which the NFSv4 callback
1002 channel should listen.
1003
58df095b
TM
1004 nfs.idmap_cache_timeout=
1005 [NFS] set the maximum lifetime for idmapper cache
1006 entries.
1007
1da177e4
LT
1008 nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
1009
1010 no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
1011 emulation library even if a 387 maths coprocessor
1012 is present.
1013
a9913044
RD
1014 noalign [KNL,ARM]
1015
1da177e4
LT
1016 noapic [SMP,APIC] Tells the kernel to not make use of any
1017 IOAPICs that may be present in the system.
1018
1019 noasync [HW,M68K] Disables async and sync negotiation for
1020 all devices.
1021
1022 nobats [PPC] Do not use BATs for mapping kernel lowmem
1023 on "Classic" PPC cores.
1024
1025 nocache [ARM]
a9913044 1026
163ecdff
SN
1027 nodelayacct [KNL] Disable per-task delay accounting
1028
1da177e4
LT
1029 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1030
1031 noexec [IA-64]
1032
a9913044 1033 noexec [IA-32,X86-64]
1da177e4
LT
1034 noexec=on: enable non-executable mappings (default)
1035 noexec=off: disable nn-executable mappings
1036
4f886511
CE
1037 nofxsr [BUGS=IA-32] Disables x86 floating point extended
1038 register save and restore. The kernel will only save
1039 legacy floating-point registers on task switch.
1da177e4
LT
1040
1041 nohlt [BUGS=ARM]
a9913044 1042
1da177e4
LT
1043 no-hlt [BUGS=IA-32] Tells the kernel that the hlt
1044 instruction doesn't work correctly and not to
1045 use it.
1046
1047 nohalt [IA-64] Tells the kernel not to use the power saving
1048 function PAL_HALT_LIGHT when idle. This increases
1049 power-consumption. On the positive side, it reduces
1050 interrupt wake-up latency, which may improve performance
1051 in certain environments such as networked servers or
1052 real-time systems.
1053
1054 noirqdebug [IA-32] Disables the code which attempts to detect and
1055 disable unhandled interrupt sources.
1056
1057 noisapnp [ISAPNP] Disables ISA PnP code.
1058
1059 noinitrd [RAM] Tells the kernel not to load any configured
1060 initial RAM disk.
1061
1062 nointroute [IA-64]
1063
1064 nolapic [IA-32,APIC] Do not enable or use the local APIC.
1065
1066 noltlbs [PPC] Do not use large page/tlb entries for kernel
1067 lowmem mapping on PPC40x.
1068
312f1f01
H
1069 nomca [IA-64] Disable machine check abort handling
1070
abe37e5a
H
1071 nomce [IA-32] Machine Check Exception
1072
1da177e4
LT
1073 noresidual [PPC] Don't use residual data on PReP machines.
1074
a9913044
RD
1075 noresume [SWSUSP] Disables resume and restores original swap
1076 space.
1077
1da177e4
LT
1078 no-scroll [VGA] Disables scrollback.
1079 This is required for the Braillex ib80-piezo Braille
1080 reader made by F.H. Papenmeier (Germany).
1081
1082 nosbagart [IA-64]
1083
4f886511
CE
1084 nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
1085
1da177e4
LT
1086 nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
1087
1088 nosync [HW,M68K] Disables sync negotiation for all devices.
1089
1090 notsc [BUGS=IA-32] Disable Time Stamp Counter
1091
1092 nousb [USB] Disable the USB subsystem
1093
1094 nowb [ARM]
a9913044 1095
a61c2d78
DJ
1096 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1097
1da177e4
LT
1098 opl3= [HW,OSS]
1099 Format: <io>
1100
a9913044
RD
1101 opl3sa2= [HW,OSS] Format:
1102 <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
1103
1da177e4
LT
1104 oprofile.timer= [HW]
1105 Use timer interrupt instead of performance counters
1106
1107 optcd= [HW,CD]
1108 Format: <io>
1109
1110 osst= [HW,SCSI] SCSI Tape Driver
1111 Format: <buffer_size>,<write_threshold>
1112 See also Documentation/scsi/st.txt.
1113
1114 panic= [KNL] Kernel behaviour on panic
1115 Format: <timeout>
1116
1117 parkbd.port= [HW] Parallel port number the keyboard adapter is
1118 connected to, default is 0.
1119 Format: <parport#>
1120 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1121 0 for XT, 1 for AT (default is AT).
a9913044
RD
1122 Format: <mode>
1123
1124 parport= [HW,PPT] Specify parallel ports. 0 disables.
1125 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1126 Use 'auto' to force the driver to use any
1127 IRQ/DMA settings detected (the default is to
1128 ignore detected IRQ/DMA settings because of
1129 possible conflicts). You can specify the base
1130 address, IRQ, and DMA settings; IRQ and DMA
1131 should be numbers, or 'auto' (for using detected
1132 settings on that particular port), or 'nofifo'
1133 (to avoid using a FIFO even if it is detected).
1134 Parallel ports are assigned in the order they
1135 are specified on the command line, starting
1136 with parport0.
1137
1138 parport_init_mode= [HW,PPT]
1139 Configure VIA parallel port to operate in
1140 a specific mode. This is necessary on Pegasos
1141 computer where firmware has no options for setting
1142 up parallel port mode and sets it to spp.
1143 Currently this function knows 686a and 8231 chips.
1da177e4
LT
1144 Format: [spp|ps2|epp|ecp|ecpepp]
1145
a9913044
RD
1146 pas2= [HW,OSS] Format:
1147 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1148
1da177e4
LT
1149 pas16= [HW,SCSI]
1150 See header of drivers/scsi/pas16.c.
1151
dd287796
AM
1152 pause_on_oops=
1153 Halt all CPUs after the first oops has been printed for
1154 the specified number of seconds. This is to be used if
1155 your oopses keep scrolling off the screen.
1156
1da177e4
LT
1157 pcbit= [HW,ISDN]
1158
1159 pcd. [PARIDE]
1160 See header of drivers/block/paride/pcd.c.
1161 See also Documentation/paride.txt.
1162
a9913044
RD
1163 pci=option[,option...] [PCI] various PCI subsystem options:
1164 off [IA-32] don't probe for the PCI bus
1165 bios [IA-32] force use of PCI BIOS, don't access
1166 the hardware directly. Use this if your machine
1167 has a non-standard PCI host bridge.
1168 nobios [IA-32] disallow use of PCI BIOS, only direct
1169 hardware access methods are allowed. Use this
1170 if you experience crashes upon bootup and you
1171 suspect they are caused by the BIOS.
1172 conf1 [IA-32] Force use of PCI Configuration
1173 Mechanism 1.
1174 conf2 [IA-32] Force use of PCI Configuration
1175 Mechanism 2.
61be6d66
BH
1176 nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
1177 Configuration
309e57df
MW
1178 nomsi [MSI] If the PCI_MSI kernel config parameter is
1179 enabled, this kernel boot option can be used to
1180 disable the use of MSI interrupts system-wide.
a9913044
RD
1181 nosort [IA-32] Don't sort PCI devices according to
1182 order given by the PCI BIOS. This sorting is
1183 done to get a device order compatible with
1184 older kernels.
1185 biosirq [IA-32] Use PCI BIOS calls to get the interrupt
1186 routing table. These calls are known to be buggy
1187 on several machines and they hang the machine
1188 when used, but on other computers it's the only
1189 way to get the interrupt routing table. Try
1190 this option if the kernel is unable to allocate
1191 IRQs or discover secondary PCI buses on your
1192 motherboard.
1193 rom [IA-32] Assign address space to expansion ROMs.
1194 Use with caution as certain devices share
1195 address decoders between ROMs and other
1196 resources.
1197 irqmask=0xMMMM [IA-32] Set a bit mask of IRQs allowed to be
1198 assigned automatically to PCI devices. You can
1199 make the kernel exclude IRQs of your ISA cards
1200 this way.
120bb424 1201 pirqaddr=0xAAAAA [IA-32] Specify the physical address
a9913044
RD
1202 of the PIRQ table (normally generated
1203 by the BIOS) if it is outside the
1204 F0000h-100000h range.
1205 lastbus=N [IA-32] Scan all buses thru bus #N. Can be
1206 useful if the kernel is unable to find your
1207 secondary buses and you want to tell it
1208 explicitly which ones they are.
1209 assign-busses [IA-32] Always assign all PCI bus
1210 numbers ourselves, overriding
1211 whatever the firmware may have done.
1212 usepirqmask [IA-32] Honor the possible IRQ mask stored
1213 in the BIOS $PIR table. This is needed on
1214 some systems with broken BIOSes, notably
1215 some HP Pavilion N5400 and Omnibook XE3
1216 notebooks. This will have no effect if ACPI
1217 IRQ routing is enabled.
1218 noacpi [IA-32] Do not use ACPI for IRQ routing
1219 or for PCI scanning.
1220 routeirq Do IRQ routing for all PCI devices.
1221 This is normally done in pci_enable_device(),
1222 so this option is a temporary workaround
1223 for broken drivers that don't call it.
1224 firmware [ARM] Do not re-enumerate the bus but instead
1225 just use the configuration from the
1226 bootloader. This is currently used on
1227 IXP2000 systems where the bus has to be
1228 configured a certain way for adjunct CPUs.
0637a70a
AK
1229 noearly [X86] Don't do any early type 1 scanning.
1230 This might help on some broken boards which
1231 machine check when some devices' config space
1232 is read. But various workarounds are disabled
1233 and some IOMMU drivers will not work.
1da177e4
LT
1234 pcmv= [HW,PCMCIA] BadgePAD 4
1235
1236 pd. [PARIDE]
1237 See Documentation/paride.txt.
1238
1239 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1240 boot time.
1241 Format: { 0 | 1 }
1242 See arch/parisc/kernel/pdc_chassis.c
1243
1244 pf. [PARIDE]
1245 See Documentation/paride.txt.
1246
1247 pg. [PARIDE]
1248 See Documentation/paride.txt.
1249
1250 pirq= [SMP,APIC] Manual mp-table setup
1251 See Documentation/i386/IO-APIC.txt.
1252
1253 plip= [PPT,NET] Parallel port network link
1254 Format: { parport<nr> | timid | 0 }
1255 See also Documentation/parport.txt.
1256
1257 pnpacpi= [ACPI]
1258 { off }
1259
1260 pnpbios= [ISAPNP]
1261 { on | off | curr | res | no-curr | no-res }
1262
1263 pnp_reserve_irq=
1264 [ISAPNP] Exclude IRQs for the autoconfiguration
1265
1266 pnp_reserve_dma=
1267 [ISAPNP] Exclude DMAs for the autoconfiguration
1268
1269 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
a9913044 1270 Ranges are in pairs (I/O port base and size).
1da177e4
LT
1271
1272 pnp_reserve_mem=
a9913044
RD
1273 [ISAPNP] Exclude memory regions for the
1274 autoconfiguration.
1da177e4
LT
1275 Ranges are in pairs (memory base and size).
1276
1277 profile= [KNL] Enable kernel profiling via /proc/profile
a9913044
RD
1278 Format: [schedule,]<number>
1279 Param: "schedule" - profile schedule points.
1280 Param: <number> - step/bucket size as a power of 2 for
1281 statistical time based profiling.
1da177e4 1282
a9913044 1283 processor.max_cstate= [HW,ACPI]
1da177e4
LT
1284 Limit processor to maximum C-state
1285 max_cstate=9 overrides any DMI blacklist limit.
1286
41c0d868
LB
1287 processor.nocst [HW,ACPI]
1288 Ignore the _CST method to determine C-states,
1289 instead using the legacy FADT method
1290
1da177e4
LT
1291 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1292 before loading.
1293 See Documentation/ramdisk.txt.
1294
a9913044
RD
1295 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1296 probe for; one of (bare|imps|exps|lifebook|any).
1da177e4
LT
1297 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1298 per second.
a9913044
RD
1299 psmouse.resetafter= [HW,MOUSE]
1300 Try to reset the device after so many bad packets
1da177e4
LT
1301 (0 = never).
1302 psmouse.resolution=
1303 [HW,MOUSE] Set desired mouse resolution, in dpi.
1304 psmouse.smartscroll=
a9913044 1305 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1da177e4
LT
1306 0 = disabled, 1 = enabled (default).
1307
1308 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
a9913044
RD
1309 Format:
1310 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1da177e4
LT
1311
1312 pt. [PARIDE]
1313 See Documentation/paride.txt.
1314
7d2c502f 1315 quiet [KNL] Disable most log messages
a9913044 1316
1da177e4
LT
1317 r128= [HW,DRM]
1318
1319 raid= [HW,RAID]
1320 See Documentation/md.txt.
1321
1322 ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
1323 See Documentation/ramdisk.txt.
1324
a9913044 1325 ramdisk_blocksize= [RAM]
1da177e4 1326 See Documentation/ramdisk.txt.
a9913044 1327
1da177e4
LT
1328 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1329 New name for the ramdisk parameter.
1330 See Documentation/ramdisk.txt.
1331
21a1ea9e
DS
1332 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1333 RCU callbacks to process in one batch.
1334
1335 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1336 RCU callbacks over which batch limiting is disabled.
1337
1338 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1339 RCU callbacks below which batch limiting is re-enabled.
1340
ffdfc409
OJ
1341 rdinit= [KNL]
1342 Format: <full_path>
1343 Run specified binary instead of /init from the ramdisk,
1344 used for early userspace startup. See initrd.
1345
1da177e4
LT
1346 reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1347 Format: <reboot_mode>[,<reboot_mode2>[,...]]
f3e299fe 1348 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1da177e4
LT
1349
1350 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1351
461a9aff
ZA
1352 reservetop= [IA-32]
1353 Format: nn[KMG]
1354 Reserves a hole at the top of the kernel virtual
1355 address space.
1356
7e96287d
VG
1357 reset_devices [KNL] Force drivers to reset the underlying device
1358 during initialization.
1359
a9913044
RD
1360 resume= [SWSUSP]
1361 Specify the partition device for software suspend
1da177e4
LT
1362
1363 rhash_entries= [KNL,NET]
1364 Set number of hash buckets for route cache
1365
1366 riscom8= [HW,SERIAL]
1367 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1368
1369 ro [KNL] Mount root device read-only on boot
1370
1371 root= [KNL] Root filesystem
1372
1373 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1374 mount the root filesystem
1375
1376 rootflags= [KNL] Set root filesystem mount option string
1377
1378 rootfstype= [KNL] Set root filesystem type
1379
1380 rw [KNL] Mount root device read-write on boot
1381
1382 S [KNL] Run init in single mode
1383
1384 sa1100ir [NET]
1385 See drivers/net/irda/sa1100_ir.c.
1386
1387 sb= [HW,OSS]
1388 Format: <io>,<irq>,<dma>,<dma2>
1389
1390 sbni= [NET] Granch SBNI12 leased line adapter
a9913044 1391
1da177e4
LT
1392 sbpcd= [HW,CD] Soundblaster CD adapter
1393 Format: <io>,<type>
1394 See a comment before function sbpcd_setup() in
1395 drivers/cdrom/sbpcd.c.
1396
1397 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1398 Format: <io>[,<timeout>[,<isapnp>]]
1399
1400 scsi_debug_*= [SCSI]
1401 See drivers/scsi/scsi_debug.c.
1402
1403 scsi_default_dev_flags=
1404 [SCSI] SCSI default device flags
1405 Format: <integer>
1406
1407 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1408 Format: <vendor>:<model>:<flags>
1409 (flags are integer value)
1410
1411 scsi_logging= [SCSI]
1412
1413 selinux [SELINUX] Disable or enable SELinux at boot time.
1414 Format: { "0" | "1" }
1415 See security/selinux/Kconfig help text.
1416 0 -- disable.
1417 1 -- enable.
1418 Default value is set via kernel config option.
1419 If enabled at boot time, /selinux/disable can be used
1420 later to disable prior to initial policy load.
1421
4e5ab4cb
JM
1422 selinux_compat_net =
1423 [SELINUX] Set initial selinux_compat_net flag value.
1424 Format: { "0" | "1" }
1425 0 -- use new secmark-based packet controls
1426 1 -- use legacy packet controls
1427 Default value is 0 (preferred).
1428 Value can be changed at runtime via
1429 /selinux/compat_net.
1430
1da177e4
LT
1431 serialnumber [BUGS=IA-32]
1432
a9913044
RD
1433 sg_def_reserved_size= [SCSI]
1434
1da177e4
LT
1435 shapers= [NET]
1436 Maximal number of shapers.
a9913044 1437
1da177e4
LT
1438 sim710= [SCSI,HW]
1439 See header of drivers/scsi/sim710.c.
1440
1441 simeth= [IA-64]
1442 simscsi=
a9913044 1443
1da177e4
LT
1444 sjcd= [HW,CD]
1445 Format: <io>,<irq>,<dma>
1446 See header of drivers/cdrom/sjcd.c.
1447
1448 slram= [HW,MTD]
1449
1450 smart2= [HW]
1451 Format: <io1>[,<io2>[,...,<io8>]]
1452
1453 snd-ad1816a= [HW,ALSA]
1454
1455 snd-ad1848= [HW,ALSA]
1456
1457 snd-ali5451= [HW,ALSA]
1458
1459 snd-als100= [HW,ALSA]
1460
1461 snd-als4000= [HW,ALSA]
1462
1463 snd-azt2320= [HW,ALSA]
1464
1465 snd-cmi8330= [HW,ALSA]
1466
1467 snd-cmipci= [HW,ALSA]
1468
1469 snd-cs4231= [HW,ALSA]
1470
1471 snd-cs4232= [HW,ALSA]
1472
1473 snd-cs4236= [HW,ALSA]
1474
1475 snd-cs4281= [HW,ALSA]
1476
1477 snd-cs46xx= [HW,ALSA]
1478
1479 snd-dt019x= [HW,ALSA]
1480
1481 snd-dummy= [HW,ALSA]
1482
1483 snd-emu10k1= [HW,ALSA]
1484
1485 snd-ens1370= [HW,ALSA]
1486
1487 snd-ens1371= [HW,ALSA]
1488
1489 snd-es968= [HW,ALSA]
1490
1491 snd-es1688= [HW,ALSA]
1492
1493 snd-es18xx= [HW,ALSA]
1494
1495 snd-es1938= [HW,ALSA]
1496
1497 snd-es1968= [HW,ALSA]
1498
1499 snd-fm801= [HW,ALSA]
1500
1501 snd-gusclassic= [HW,ALSA]
1502
1503 snd-gusextreme= [HW,ALSA]
1504
1505 snd-gusmax= [HW,ALSA]
1506
1507 snd-hdsp= [HW,ALSA]
1508
1509 snd-ice1712= [HW,ALSA]
1510
1511 snd-intel8x0= [HW,ALSA]
1512
1513 snd-interwave= [HW,ALSA]
1514
1515 snd-interwave-stb=
1516 [HW,ALSA]
1517
1518 snd-korg1212= [HW,ALSA]
1519
1520 snd-maestro3= [HW,ALSA]
1521
1522 snd-mpu401= [HW,ALSA]
1523
1524 snd-mtpav= [HW,ALSA]
1525
1526 snd-nm256= [HW,ALSA]
1527
1528 snd-opl3sa2= [HW,ALSA]
1529
1530 snd-opti92x-ad1848=
1531 [HW,ALSA]
1532
1533 snd-opti92x-cs4231=
1534 [HW,ALSA]
1535
1536 snd-opti93x= [HW,ALSA]
1537
1538 snd-pmac= [HW,ALSA]
1539
1540 snd-rme32= [HW,ALSA]
1541
1542 snd-rme96= [HW,ALSA]
1543
1544 snd-rme9652= [HW,ALSA]
1545
1546 snd-sb8= [HW,ALSA]
1547
1548 snd-sb16= [HW,ALSA]
1549
1550 snd-sbawe= [HW,ALSA]
1551
1552 snd-serial= [HW,ALSA]
1553
1554 snd-sgalaxy= [HW,ALSA]
1555
1556 snd-sonicvibes= [HW,ALSA]
1557
1558 snd-sun-amd7930=
1559 [HW,ALSA]
1560
1561 snd-sun-cs4231= [HW,ALSA]
1562
1563 snd-trident= [HW,ALSA]
1564
1565 snd-usb-audio= [HW,ALSA,USB]
1566
1567 snd-via82xx= [HW,ALSA]
1568
1569 snd-virmidi= [HW,ALSA]
1570
1571 snd-wavefront= [HW,ALSA]
1572
1573 snd-ymfpci= [HW,ALSA]
a9913044 1574
1da177e4
LT
1575 sonycd535= [HW,CD]
1576 Format: <io>[,<irq>]
1577
1578 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1579 See Documentation/sonypi.txt
1580
1581 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1582 See Documentation/specialix.txt.
1583
1584 spia_io_base= [HW,MTD]
1585 spia_fio_base=
1586 spia_pedr=
1587 spia_peddr=
1588
1589 sscape= [HW,OSS]
1590 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
a9913044 1591
1da177e4
LT
1592 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1593 See Documentation/scsi/st.txt.
1594
1595 st0x= [HW,SCSI]
1596 See header of drivers/scsi/seagate.c.
1597
1598 sti= [PARISC,HW]
1599 Format: <num>
1600 Set the STI (builtin display/keyboard on the HP-PARISC
1601 machines) console (graphic card) which should be used
1602 as the initial boot-console.
1603 See also comment in drivers/video/console/sticore.c.
1604
1605 sti_font= [HW]
1606 See comment in drivers/video/console/sticore.c.
1607
1608 stifb= [HW]
1609 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1610
1da177e4 1611 swiotlb= [IA-64] Number of I/O TLB slabs
a9913044 1612
1da177e4
LT
1613 switches= [HW,M68k]
1614
1615 sym53c416= [HW,SCSI]
1616 See header of drivers/scsi/sym53c416.c.
1617
1618 t128= [HW,SCSI]
1619 See header of drivers/scsi/t128.c.
1620
1621 tdfx= [HW,DRM]
1622
1623 thash_entries= [KNL,NET]
1624 Set number of hash buckets for TCP connection
1625
1626 time Show timing data prefixed to each printk message line
1627
734efb46
JS
1628 clocksource= [GENERIC_TIME] Override the default clocksource
1629 Override the default clocksource and use the clocksource
1630 with the name specified.
1631
1da177e4
LT
1632 tipar.timeout= [HW,PPT]
1633 Set communications timeout in tenths of a second
1634 (default 15).
1635
1636 tipar.delay= [HW,PPT]
1637 Set inter-bit delay in microseconds (default 10).
1638
1639 tmc8xx= [HW,SCSI]
1640 See header of drivers/scsi/seagate.c.
1641
1642 tmscsim= [HW,SCSI]
1643 See comment before function dc390_setup() in
1644 drivers/scsi/tmscsim.c.
1645
1646 tp720= [HW,PS2]
1647
1648 trix= [HW,OSS] MediaTrix AudioTrix Pro
a9913044
RD
1649 Format:
1650 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1651
1da177e4
LT
1652 tsdev.xres= [TS] Horizontal screen resolution.
1653 tsdev.yres= [TS] Vertical screen resolution.
1654
a9913044
RD
1655 turbografx.map[2|3]= [HW,JOY]
1656 TurboGraFX parallel port interface
1657 Format:
1658 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1da177e4
LT
1659 See also Documentation/input/joystick-parport.txt
1660
1661 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1662 See header of drivers/scsi/u14-34f.c.
1663
1664 uart401= [HW,OSS]
1665 Format: <io>,<irq>
1666
1667 uart6850= [HW,OSS]
1668 Format: <io>,<irq>
1669
1da177e4
LT
1670 usbhid.mousepoll=
1671 [USBHID] The interval which mice are to be polled at.
a9913044 1672
e6e5494c
IM
1673 vdso= [IA-32]
1674 vdso=1: enable VDSO (default)
1675 vdso=0: disable VDSO mapping
1676
1da177e4
LT
1677 video= [FB] Frame buffer configuration
1678 See Documentation/fb/modedb.txt.
1679
1680 vga= [BOOT,IA-32] Select a particular video mode
a9913044
RD
1681 See Documentation/i386/boot.txt and
1682 Documentation/svga.txt.
1da177e4
LT
1683 Use vga=ask for menu.
1684 This is actually a boot loader parameter; the value is
1685 passed to the kernel using a special protocol.
1686
a9913044 1687 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1da177e4
LT
1688 size of <nn>. This can be used to increase the
1689 minimum size (128MB on x86). It can also be used to
1690 decrease the size and leave more room for directly
1691 mapped kernel RAM.
1692
585c3047
PO
1693 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1694 Format: <command>
1da177e4 1695
585c3047
PO
1696 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1697 Format: <command>
1698
1699 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1700 Format: <command>
a9913044 1701
1da177e4
LT
1702 waveartist= [HW,OSS]
1703 Format: <io>,<irq>,<dma>,<dma2>
a9913044 1704
1da177e4
LT
1705 wd33c93= [HW,SCSI]
1706 See header of drivers/scsi/wd33c93.c.
1707
1708 wd7000= [HW,SCSI]
1709 See header of drivers/scsi/wd7000.c.
1710
1711 wdt= [WDT] Watchdog
1712 See Documentation/watchdog/watchdog.txt.
1713
1714 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1715 xd_geo= See header of drivers/block/xd.c.
1716
1717 xirc2ps_cs= [NET,PCMCIA]
a9913044
RD
1718 Format:
1719 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1da177e4 1720
a62eaf15
AK
1721 norandmaps Don't use address space randomization
1722 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1723
1da177e4 1724
a9913044 1725______________________________________________________________________
1da177e4
LT
1726
1727TODO:
1728
1729 Add documentation for ALSA options.
1730 Add more DRM drivers.