x86 vDSO: consolidate vdso32
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / Documentation / kernel-parameters.txt
1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
3
4 The 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
7 case insensitive manner), and with descriptions where known.
8
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
11
12 modprobe usbcore blinkenlights=1
13
14 Module parameters for modules that are built into the kernel image
15 are 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
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
26
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
31
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend is enabled.
91 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
99 X86-32 X86-32, aka i386 architecture is enabled.
100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
103
104 In addition, the following text indicates that the option:
105
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
109
110 Parameters denoted with BOOT are actually interpreted by the boot
111 loader, and have no meaning to the kernel directly.
112 Do not modify the syntax of boot loader parameters without extreme
113 need or coordination with <Documentation/i386/boot.txt>.
114
115 There are also arch-specific kernel-parameters not documented here.
116 See for example <Documentation/x86_64/boot-options.txt>.
117
118 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119 a trailing = on the name of any parameter states that that parameter will
120 be entered as an environment variable, whereas its absence indicates that
121 it will appear as a kernel argument readable via /proc/cmdline by programs
122 running once the system is up.
123
124 The number of kernel parameters is not limited, but the length of the
125 complete command line (parameters including spaces etc.) is limited to
126 a fixed number of characters. This limit depends on the architecture
127 and is between 256 and 4096 characters. It is defined in the file
128 ./include/asm/setup.h as COMMAND_LINE_SIZE.
129
130
131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
133 Format: { force | off | ht | strict | noirq }
134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
138 strict -- Be less tolerant of platforms that are not
139 strictly ACPI specification compliant.
140
141 See also Documentation/pm.txt, pci=noacpi
142
143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
147 default: 0
148
149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode }
151 See Documentation/power/video.txt
152
153 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
154 Format: { level | edge | high | low }
155
156 acpi_irq_balance [HW,ACPI]
157 ACPI will balance active IRQs
158 default in APIC mode
159
160 acpi_irq_nobalance [HW,ACPI]
161 ACPI will not move active IRQs (default)
162 default in PIC mode
163
164 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
165 use by PCI
166 Format: <irq>,<irq>...
167
168 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
169 Format: <irq>,<irq>...
170
171 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
172
173 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
174 Format: To spoof as Windows 98: ="Microsoft Windows"
175
176 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
177 acpi_osi="string1" # add string1 -- only one string
178 acpi_osi="!string2" # remove built-in string2
179 acpi_osi= # disable all strings
180
181 acpi_serialize [HW,ACPI] force serialization of AML methods
182
183 acpi_skip_timer_override [HW,ACPI]
184 Recognize and ignore IRQ0/pin2 Interrupt Override.
185 For broken nForce2 BIOS resulting in XT-PIC timer.
186 acpi_use_timer_override [HW,ACPI}
187 Use timer override. For some broken Nvidia NF5 boards
188 that require a timer override, but don't have
189 HPET
190
191 acpi.debug_layer= [HW,ACPI]
192 Format: <int>
193 Each bit of the <int> indicates an ACPI debug layer,
194 1: enable, 0: disable. It is useful for boot time
195 debugging. After system has booted up, it can be set
196 via /sys/module/acpi/parameters/debug_layer.
197 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
198 Available bits (add the numbers together) to enable debug output
199 for specific parts of the ACPI subsystem:
200 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
201 0x10 namespace 0x20 parser 0x40 dispatcher
202 0x80 executer 0x100 resources 0x200 acpica debugger
203 0x400 os services 0x800 acpica disassembler.
204 The number can be in decimal or prefixed with 0x in hex.
205 Warning: Many of these options can produce a lot of
206 output and make your system unusable. Be very careful.
207
208 acpi.debug_level= [HW,ACPI]
209 Format: <int>
210 Each bit of the <int> indicates an ACPI debug level,
211 1: enable, 0: disable. It is useful for boot time
212 debugging. After system has booted up, it can be set
213 via /sys/module/acpi/parameters/debug_level.
214 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
215 Available bits (add the numbers together) to enable different
216 debug output levels of the ACPI subsystem:
217 0x01 error 0x02 warn 0x04 init 0x08 debug object
218 0x10 info 0x20 init names 0x40 parse 0x80 load
219 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
220 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
221 0x10000 resources 0x20000 user requests 0x40000 package.
222 The number can be in decimal or prefixed with 0x in hex.
223 Warning: Many of these options can produce a lot of
224 output and make your system unusable. Be very careful.
225
226 acpi_pm_good [X86-32,X86-64]
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
230
231 agp= [AGP]
232 { off | try_unsupported }
233 off: disable AGP support
234 try_unsupported: try to drive unsupported chipsets
235 (may crash computer or cause data corruption)
236
237 enable_timer_pin_1 [i386,x86-64]
238 Enable PIN 1 of APIC timer
239 Can be useful to work around chipset bugs
240 (in particular on some ATI chipsets).
241 The kernel tries to set a reasonable default.
242
243 disable_timer_pin_1 [i386,x86-64]
244 Disable PIN 1 of APIC timer
245 Can be useful to work around chipset bugs.
246
247 ad1848= [HW,OSS]
248 Format: <io>,<irq>,<dma>,<dma2>,<type>
249
250 advansys= [HW,SCSI]
251 See header of drivers/scsi/advansys.c.
252
253 advwdt= [HW,WDT] Advantech WDT
254 Format: <iostart>,<iostop>
255
256 aedsp16= [HW,OSS] Audio Excel DSP 16
257 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
258 See also header of sound/oss/aedsp16.c.
259
260 aha152x= [HW,SCSI]
261 See Documentation/scsi/aha152x.txt.
262
263 aha1542= [HW,SCSI]
264 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
265
266 aic7xxx= [HW,SCSI]
267 See Documentation/scsi/aic7xxx.txt.
268
269 aic79xx= [HW,SCSI]
270 See Documentation/scsi/aic79xx.txt.
271
272 amijoy.map= [HW,JOY] Amiga joystick support
273 Map of devices attached to JOY0DAT and JOY1DAT
274 Format: <a>,<b>
275 See also Documentation/kernel/input/joystick.txt
276
277 analog.map= [HW,JOY] Analog joystick and gamepad support
278 Specifies type or capabilities of an analog joystick
279 connected to one of 16 gameports
280 Format: <type1>,<type2>,..<type16>
281
282 apc= [HW,SPARC]
283 Power management functions (SPARCstation-4/5 + deriv.)
284 Format: noidle
285 Disable APC CPU standby support. SPARCstation-Fox does
286 not play well with APC CPU idle - disable it if you have
287 APC and your system crashes randomly.
288
289 apic= [APIC,i386] Advanced Programmable Interrupt Controller
290 Change the output verbosity whilst booting
291 Format: { quiet (default) | verbose | debug }
292 Change the amount of debugging information output
293 when initialising the APIC and IO-APIC components.
294
295 apm= [APM] Advanced Power Management
296 See header of arch/i386/kernel/apm.c.
297
298 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
299 Format: <io>,<irq>,<nodeID>
300
301 ataflop= [HW,M68k]
302
303 atarimouse= [HW,MOUSE] Atari Mouse
304
305 atascsi= [HW,SCSI] Atari SCSI
306
307 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
308 EzKey and similar keyboards
309
310 atkbd.reset= [HW] Reset keyboard during initialization
311
312 atkbd.set= [HW] Select keyboard code set
313 Format: <int> (2 = AT (default), 3 = PS/2)
314
315 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
316 keyboards
317
318 atkbd.softraw= [HW] Choose between synthetic and real raw mode
319 Format: <bool> (0 = real, 1 = synthetic (default))
320
321 atkbd.softrepeat= [HW]
322 Use software keyboard repeat
323
324 autotest [IA64]
325
326 baycom_epp= [HW,AX25]
327 Format: <io>,<mode>
328
329 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
330 Format: <io>,<mode>
331 See header of drivers/net/hamradio/baycom_par.c.
332
333 baycom_ser_fdx= [HW,AX25]
334 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
335 Format: <io>,<irq>,<mode>[,<baud>]
336 See header of drivers/net/hamradio/baycom_ser_fdx.c.
337
338 baycom_ser_hdx= [HW,AX25]
339 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
340 Format: <io>,<irq>,<mode>
341 See header of drivers/net/hamradio/baycom_ser_hdx.c.
342
343 boot_delay= Milliseconds to delay each printk during boot.
344 Values larger than 10 seconds (10000) are changed to
345 no delay (0).
346 Format: integer
347
348 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
349 bttv.radio= Most important insmod options are available as
350 kernel args too.
351 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
352 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
353
354 BusLogic= [HW,SCSI]
355 See drivers/scsi/BusLogic.c, comment before function
356 BusLogic_ParseDriverOptions().
357
358 c101= [NET] Moxa C101 synchronous serial card
359
360 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
361 Sometimes CPU hardware bugs make them report the cache
362 size incorrectly. The kernel will attempt work arounds
363 to fix known problems, but for some CPUs it is not
364 possible to determine what the correct size should be.
365 This option provides an override for these situations.
366
367 capability.disable=
368 [SECURITY] Disable capabilities. This would normally
369 be used only if an alternative security model is to be
370 configured. Potentially dangerous and should only be
371 used if you are entirely sure of the consequences.
372
373 ccw_timeout_log [S390]
374 See Documentation/s390/CommonIO for details.
375
376 checkreqprot [SELINUX] Set initial checkreqprot flag value.
377 Format: { "0" | "1" }
378 See security/selinux/Kconfig help text.
379 0 -- check protection applied by kernel (includes
380 any implied execute protection).
381 1 -- check protection requested by application.
382 Default value is set via a kernel config option.
383 Value can be changed at runtime via
384 /selinux/checkreqprot.
385
386 cio_ignore= [S390]
387 See Documentation/s390/CommonIO for details.
388
389 cio_msg= [S390]
390 See Documentation/s390/CommonIO for details.
391
392 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
393 [Deprecated]
394 Forces specified clocksource (if available) to be used
395 when calculating gettimeofday(). If specified
396 clocksource is not available, it defaults to PIT.
397 Format: { pit | tsc | cyclone | pmtmr }
398
399 clocksource= [GENERIC_TIME] Override the default clocksource
400 Format: <string>
401 Override the default clocksource and use the clocksource
402 with the name specified.
403 Some clocksource names to choose from, depending on
404 the platform:
405 [all] jiffies (this is the base, fallback clocksource)
406 [ACPI] acpi_pm
407 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
408 pxa_timer,timer3,32k_counter,timer0_1
409 [AVR32] avr32
410 [X86-32] pit,hpet,tsc,vmi-timer;
411 scx200_hrt on Geode; cyclone on IBM x440
412 [MIPS] MIPS
413 [PARISC] cr16
414 [S390] tod
415 [SH] SuperH
416 [SPARC64] tick
417 [X86-64] hpet,tsc
418
419 code_bytes [IA32] How many bytes of object code to print in an
420 oops report.
421 Range: 0 - 8192
422 Default: 64
423
424 disable_8254_timer
425 enable_8254_timer
426 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
427 over the 8254 in addition to over the IO-APIC. The
428 kernel tries to set a sensible default.
429
430 hpet= [X86-32,HPET] option to control HPET usage
431 Format: { enable (default) | disable | force }
432 disable: disable HPET and use PIT instead
433 force: allow force enabled of undocumented chips (ICH4,
434 VIA, nVidia)
435
436 com20020= [HW,NET] ARCnet - COM20020 chipset
437 Format:
438 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
439
440 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
441 Format: <io>[,<irq>]
442
443 com90xx= [HW,NET]
444 ARCnet - COM90xx chipset (memory-mapped buffers)
445 Format: <io>[,<irq>[,<memstart>]]
446
447 condev= [HW,S390] console device
448 conmode=
449
450 console= [KNL] Output console device and options.
451
452 tty<n> Use the virtual console device <n>.
453
454 ttyS<n>[,options]
455 ttyUSB0[,options]
456 Use the specified serial port. The options are of
457 the form "bbbbpnf", where "bbbb" is the baud rate,
458 "p" is parity ("n", "o", or "e"), "n" is number of
459 bits, and "f" is flow control ("r" for RTS or
460 omit it). Default is "9600n8".
461
462 See Documentation/serial-console.txt for more
463 information. See
464 Documentation/networking/netconsole.txt for an
465 alternative.
466
467 uart[8250],io,<addr>[,options]
468 uart[8250],mmio,<addr>[,options]
469 Start an early, polled-mode console on the 8250/16550
470 UART at the specified I/O port or MMIO address,
471 switching to the matching ttyS device later. The
472 options are the same as for ttyS, above.
473
474 earlycon= [KNL] Output early console device and options.
475 uart[8250],io,<addr>[,options]
476 uart[8250],mmio,<addr>[,options]
477 Start an early, polled-mode console on the 8250/16550
478 UART at the specified I/O port or MMIO address.
479 The options are the same as for ttyS, above.
480
481 no_console_suspend
482 [HW] Never suspend the console
483 Disable suspending of consoles during suspend and
484 hibernate operations. Once disabled, debugging
485 messages can reach various consoles while the rest
486 of the system is being put to sleep (ie, while
487 debugging driver suspend/resume hooks). This may
488 not work reliably with all consoles, but is known
489 to work with serial and VGA consoles.
490
491 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
492 Format:
493 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
494
495 crashkernel=nn[KMG]@ss[KMG]
496 [KNL] Reserve a chunk of physical memory to
497 hold a kernel to switch to with kexec on panic.
498
499 crashkernel=range1:size1[,range2:size2,...][@offset]
500 [KNL] Same as above, but depends on the memory
501 in the running system. The syntax of range is
502 start-[end] where start and end are both
503 a memory unit (amount[KMG]). See also
504 Documentation/kdump/kdump.txt for a example.
505
506 cs4232= [HW,OSS]
507 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
508
509 cs89x0_dma= [HW,NET]
510 Format: <dma>
511
512 cs89x0_media= [HW,NET]
513 Format: { rj45 | aui | bnc }
514
515 dasd= [HW,NET]
516 See header of drivers/s390/block/dasd_devmap.c.
517
518 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
519 (one device per port)
520 Format: <port#>,<type>
521 See also Documentation/input/joystick-parport.txt
522
523 debug [KNL] Enable kernel debugging (events log level).
524
525 debug_locks_verbose=
526 [KNL] verbose self-tests
527 Format=<0|1>
528 Print debugging info while doing the locking API
529 self-tests.
530 We default to 0 (no extra messages), setting it to
531 1 will print _a lot_ more information - normally
532 only useful to kernel developers.
533
534 decnet= [HW,NET]
535 Format: <area>[,<node>]
536 See also Documentation/networking/decnet.txt.
537
538 vt.default_blu= [VT]
539 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
540 Change the default blue palette of the console.
541 This is a 16-member array composed of values
542 ranging from 0-255.
543
544 vt.default_grn= [VT]
545 Format: <green0>,<green1>,<green2>,...,<green15>
546 Change the default green palette of the console.
547 This is a 16-member array composed of values
548 ranging from 0-255.
549
550 vt.default_red= [VT]
551 Format: <red0>,<red1>,<red2>,...,<red15>
552 Change the default red palette of the console.
553 This is a 16-member array composed of values
554 ranging from 0-255.
555
556 vt.default_utf8=
557 [VT]
558 Format=<0|1>
559 Set system-wide default UTF-8 mode for all tty's.
560 Default is 1, i.e. UTF-8 mode is enabled for all
561 newly opened terminals.
562
563 dhash_entries= [KNL]
564 Set number of hash buckets for dentry cache.
565
566 digi= [HW,SERIAL]
567 IO parameters + enable/disable command.
568
569 digiepca= [HW,SERIAL]
570 See drivers/char/README.epca and
571 Documentation/digiepca.txt.
572
573 dmasound= [HW,OSS] Sound subsystem buffers
574
575 dscc4.setup= [NET]
576
577 dtc3181e= [HW,SCSI]
578
579 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
580 earlyprintk=vga
581 earlyprintk=serial[,ttySn[,baudrate]]
582
583 Append ",keep" to not disable it when the real console
584 takes over.
585
586 Only vga or serial at a time, not both.
587
588 Currently only ttyS0 and ttyS1 are supported.
589
590 Interaction with the standard serial driver is not
591 very good.
592
593 The VGA output is eventually overwritten by the real
594 console.
595
596 eata= [HW,SCSI]
597
598 edd= [EDD]
599 Format: {"of[f]" | "sk[ipmbr]"}
600 See comment in arch/i386/boot/edd.S
601
602 eisa_irq_edge= [PARISC,HW]
603 See header of drivers/parisc/eisa.c.
604
605 elanfreq= [X86-32]
606 See comment before function elanfreq_setup() in
607 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
608
609 elevator= [IOSCHED]
610 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
611 See Documentation/block/as-iosched.txt and
612 Documentation/block/deadline-iosched.txt for details.
613
614 elfcorehdr= [X86-32, X86_64]
615 Specifies physical address of start of kernel core
616 image elf header. Generally kexec loader will
617 pass this option to capture kernel.
618 See Documentation/kdump/kdump.txt for details.
619
620 enforcing [SELINUX] Set initial enforcing status.
621 Format: {"0" | "1"}
622 See security/selinux/Kconfig help text.
623 0 -- permissive (log only, no denials).
624 1 -- enforcing (deny and log).
625 Default value is 0.
626 Value can be changed at runtime via /selinux/enforce.
627
628 es1371= [HW,OSS]
629 Format: <spdif>,[<nomix>,[<amplifier>]]
630 See also header of sound/oss/es1371.c.
631
632 ether= [HW,NET] Ethernet cards parameters
633 This option is obsoleted by the "netdev=" option, which
634 has equivalent usage. See its documentation for details.
635
636 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
637 Format: <io>[,<irq>]
638
639 failslab=
640 fail_page_alloc=
641 fail_make_request=[KNL]
642 General fault injection mechanism.
643 Format: <interval>,<probability>,<space>,<times>
644 See also /Documentation/fault-injection/.
645
646 fd_mcs= [HW,SCSI]
647 See header of drivers/scsi/fd_mcs.c.
648
649 fdomain= [HW,SCSI]
650 See header of drivers/scsi/fdomain.c.
651
652 floppy= [HW]
653 See Documentation/floppy.txt.
654
655 gamecon.map[2|3]=
656 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
657 support via parallel port (up to 5 devices per port)
658 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
659 See also Documentation/input/joystick-parport.txt
660
661 gamma= [HW,DRM]
662
663 gdth= [HW,SCSI]
664 See header of drivers/scsi/gdth.c.
665
666 gpt [EFI] Forces disk with valid GPT signature but
667 invalid Protective MBR to be treated as GPT.
668
669 gvp11= [HW,SCSI]
670
671 hashdist= [KNL,NUMA] Large hashes allocated during boot
672 are distributed across NUMA nodes. Defaults on
673 for IA-64, off otherwise.
674 Format: 0 | 1 (for off | on)
675
676 hcl= [IA-64] SGI's Hardware Graph compatibility layer
677
678 hd= [EIDE] (E)IDE hard drive subsystem geometry
679 Format: <cyl>,<head>,<sect>
680
681 hd?= [HW] (E)IDE subsystem
682 hd?lun= See Documentation/ide.txt.
683
684 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
685 size of <nn>. This works even on boxes that have no
686 highmem otherwise. This also works to reduce highmem
687 size on bigger boxes.
688
689 highres= [KNL] Enable/disable high resolution timer mode.
690 Valid parameters: "on", "off"
691 Default: "on"
692
693 hisax= [HW,ISDN]
694 See Documentation/isdn/README.HiSax.
695
696 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
697
698 i8042.direct [HW] Put keyboard port into non-translated mode
699 i8042.dumbkbd [HW] Pretend that controller can only read data from
700 keyboard and cannot control its state
701 (Don't attempt to blink the leds)
702 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
703 i8042.nokbd [HW] Don't check/create keyboard port
704 i8042.nomux [HW] Don't check presence of an active multiplexing
705 controller
706 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
707 controllers
708 i8042.panicblink=
709 [HW] Frequency with which keyboard LEDs should blink
710 when kernel panics (default is 0.5 sec)
711 i8042.reset [HW] Reset the controller during init and cleanup
712 i8042.unlock [HW] Unlock (ignore) the keylock
713
714 i810= [HW,DRM]
715
716 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
717 indicates that the driver is running on unsupported
718 hardware.
719 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
720 does not match list of supported models.
721 i8k.power_status
722 [HW] Report power status in /proc/i8k
723 (disabled by default)
724 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
725 capability is set.
726
727 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
728 See Documentation/mca.txt.
729
730 icn= [HW,ISDN]
731 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
732
733 ide= [HW] (E)IDE subsystem
734 Format: ide=nodma or ide=doubler or ide=reverse
735 See Documentation/ide.txt.
736
737 ide?= [HW] (E)IDE subsystem
738 Format: ide?=noprobe or chipset specific parameters.
739 See Documentation/ide.txt.
740
741 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
742 See Documentation/ide.txt.
743
744 idle= [X86]
745 Format: idle=poll or idle=mwait
746 Poll forces a polling idle loop that can slightly improves the performance
747 of waking up a idle CPU, but will use a lot of power and make the system
748 run hot. Not recommended.
749 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
750 to not use it because it doesn't save as much power as a normal idle
751 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
752 as idle=poll.
753
754 ignore_loglevel [KNL]
755 Ignore loglevel setting - this will print /all/
756 kernel messages to the console. Useful for debugging.
757
758 ihash_entries= [KNL]
759 Set number of hash buckets for inode cache.
760
761 in2000= [HW,SCSI]
762 See header of drivers/scsi/in2000.c.
763
764 init= [KNL]
765 Format: <full_path>
766 Run specified binary instead of /sbin/init as init
767 process.
768
769 initcall_debug [KNL] Trace initcalls as they are executed. Useful
770 for working out where the kernel is dying during
771 startup.
772
773 initrd= [BOOT] Specify the location of the initial ramdisk
774
775 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
776 Format: <irq>
777
778 inttest= [IA64]
779
780 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
781 off
782 Disable intel iommu driver.
783 igfx_off [Default Off]
784 By default, gfx is mapped as normal device. If a gfx
785 device has a dedicated DMAR unit, the DMAR unit is
786 bypassed by not enabling DMAR with this option. In
787 this case, gfx device will use physical address for
788 DMA.
789 forcedac [x86_64]
790 With this option iommu will not optimize to look
791 for io virtual address below 32 bit forcing dual
792 address cycle on pci bus for cards supporting greater
793 than 32 bit addressing. The default is to look
794 for translation below 32 bit and if not available
795 then look in the higher range.
796
797 io_delay= [X86-32,X86-64] I/O delay method
798 0x80
799 Standard port 0x80 based delay
800 0xed
801 Alternate port 0xed based delay (needed on some systems)
802 udelay
803 Simple two microseconds delay
804 none
805 No delay
806
807 io7= [HW] IO7 for Marvel based alpha systems
808 See comment before marvel_specify_io7 in
809 arch/alpha/kernel/core_marvel.c.
810
811 ip= [IP_PNP]
812 See Documentation/nfsroot.txt.
813
814 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
815 See comment before ip2_setup() in
816 drivers/char/ip2/ip2base.c.
817
818 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
819 See header of drivers/scsi/ips.c.
820
821 ports= [IP_VS_FTP] IPVS ftp helper module
822 Default is 21.
823 Up to 8 (IP_VS_APP_MAX_PORTS) ports
824 may be specified.
825 Format: <port>,<port>....
826
827 irqfixup [HW]
828 When an interrupt is not handled search all handlers
829 for it. Intended to get systems with badly broken
830 firmware running.
831
832 irqpoll [HW]
833 When an interrupt is not handled search all handlers
834 for it. Also check all handlers each timer
835 interrupt. Intended to get systems with badly broken
836 firmware running.
837
838 isapnp= [ISAPNP]
839 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
840
841 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
842 Format:
843 <cpu number>,...,<cpu number>
844 or
845 <cpu number>-<cpu number> (must be a positive range in ascending order)
846 or a mixture
847 <cpu number>,...,<cpu number>-<cpu number>
848 This option can be used to specify one or more CPUs
849 to isolate from the general SMP balancing and scheduling
850 algorithms. The only way to move a process onto or off
851 an "isolated" CPU is via the CPU affinity syscalls.
852 <cpu number> begins at 0 and the maximum value is
853 "number of CPUs in system - 1".
854
855 This option is the preferred way to isolate CPUs. The
856 alternative -- manually setting the CPU mask of all
857 tasks in the system -- can cause problems and
858 suboptimal load balancer performance.
859
860 iucv= [HW,NET]
861
862 js= [HW,JOY] Analog joystick
863 See Documentation/input/joystick.txt.
864
865 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
866 specifies the amount of memory usable by the kernel
867 for non-movable allocations. The requested amount is
868 spread evenly throughout all nodes in the system. The
869 remaining memory in each node is used for Movable
870 pages. In the event, a node is too small to have both
871 kernelcore and Movable pages, kernelcore pages will
872 take priority and other nodes will have a larger number
873 of kernelcore pages. The Movable zone is used for the
874 allocation of pages that may be reclaimed or moved
875 by the page migration subsystem. This means that
876 HugeTLB pages may not be allocated from this zone.
877 Note that allocations like PTEs-from-HighMem still
878 use the HighMem zone if it exists, and the Normal
879 zone if it does not.
880
881 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
882 is similar to kernelcore except it specifies the
883 amount of memory used for migratable allocations.
884 If both kernelcore and movablecore is specified,
885 then kernelcore will be at *least* the specified
886 value but may be more. If movablecore on its own
887 is specified, the administrator must be careful
888 that the amount of memory usable for all allocations
889 is not too small.
890
891 keepinitrd [HW,ARM]
892
893 kstack=N [X86-32,X86-64] Print N words from the kernel stack
894 in oops dumps.
895
896 l2cr= [PPC]
897
898 lapic [X86-32,APIC] Enable the local APIC even if BIOS
899 disabled it.
900
901 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
902 C2 power state.
903
904 libata.dma= [LIBATA] DMA control
905 libata.dma=0 Disable all PATA and SATA DMA
906 libata.dma=1 PATA and SATA Disk DMA only
907 libata.dma=2 ATAPI (CDROM) DMA only
908 libata.dma=4 Compact Flash DMA only
909 Combinations also work, so libata.dma=3 enables DMA
910 for disks and CDROMs, but not CFs.
911
912 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
913 when set.
914 Format: <int>
915
916 load_ramdisk= [RAM] List of ramdisks to load from floppy
917 See Documentation/ramdisk.txt.
918
919 lockd.nlm_grace_period=P [NFS] Assign grace period.
920 Format: <integer>
921
922 lockd.nlm_tcpport=N [NFS] Assign TCP port.
923 Format: <integer>
924
925 lockd.nlm_timeout=T [NFS] Assign timeout value.
926 Format: <integer>
927
928 lockd.nlm_udpport=M [NFS] Assign UDP port.
929 Format: <integer>
930
931 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
932 Format: <irq>
933
934 loglevel= All Kernel Messages with a loglevel smaller than the
935 console loglevel will be printed to the console. It can
936 also be changed with klogd or other programs. The
937 loglevels are defined as follows:
938
939 0 (KERN_EMERG) system is unusable
940 1 (KERN_ALERT) action must be taken immediately
941 2 (KERN_CRIT) critical conditions
942 3 (KERN_ERR) error conditions
943 4 (KERN_WARNING) warning conditions
944 5 (KERN_NOTICE) normal but significant condition
945 6 (KERN_INFO) informational
946 7 (KERN_DEBUG) debug-level messages
947
948 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
949 Format: { n | nk | nM }
950 n must be a power of two. The default size
951 is set in the kernel config file.
952
953 logo.nologo [FB] Disables display of the built-in Linux logo.
954 This may be used to provide more screen space for
955 kernel log messages and is useful when debugging
956 kernel boot problems.
957
958 lp=0 [LP] Specify parallel ports to use, e.g,
959 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
960 lp=reset first parallel port). 'lp=0' disables the
961 lp=auto printer driver. 'lp=reset' (which can be
962 specified in addition to the ports) causes
963 attached printers to be reset. Using
964 lp=port1,port2,... specifies the parallel ports
965 to associate lp devices with, starting with
966 lp0. A port specification may be 'none' to skip
967 that lp device, or a parport name such as
968 'parport0'. Specifying 'lp=auto' instead of a
969 port specification list means that device IDs
970 from each port should be examined, to see if
971 an IEEE 1284-compliant printer is attached; if
972 so, the driver will manage that printer.
973 See also header of drivers/char/lp.c.
974
975 lpj=n [KNL]
976 Sets loops_per_jiffy to given constant, thus avoiding
977 time-consuming boot-time autodetection (up to 250 ms per
978 CPU). 0 enables autodetection (default). To determine
979 the correct value for your kernel, boot with normal
980 autodetection and see what value is printed. Note that
981 on SMP systems the preset will be applied to all CPUs,
982 which is likely to cause problems if your CPUs need
983 significantly divergent settings. An incorrect value
984 will cause delays in the kernel to be wrong, leading to
985 unpredictable I/O errors and other breakage. Although
986 unlikely, in the extreme case this might damage your
987 hardware.
988
989 ltpc= [NET]
990 Format: <io>,<irq>,<dma>
991
992 mac5380= [HW,SCSI] Format:
993 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
994
995 mac53c9x= [HW,SCSI] Format:
996 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
997
998 machvec= [IA64] Force the use of a particular machine-vector
999 (machvec) in a generic kernel.
1000 Example: machvec=hpzx1_swiotlb
1001
1002 max_loop= [LOOP] Maximum number of loopback devices that can
1003 be mounted
1004 Format: <1-256>
1005
1006 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1007 should make use of. maxcpus=n : n >= 0 limits the
1008 kernel to using 'n' processors. n=0 is a special case,
1009 it is equivalent to "nosmp", which also disables
1010 the IO APIC.
1011
1012 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1013 equal to this physical address is ignored.
1014
1015 max_luns= [SCSI] Maximum number of LUNs to probe.
1016 Should be between 1 and 2^32-1.
1017
1018 max_report_luns=
1019 [SCSI] Maximum number of LUNs received.
1020 Should be between 1 and 16384.
1021
1022 mca-pentium [BUGS=X86-32]
1023
1024 mcatest= [IA-64]
1025
1026 mce [X86-32] Machine Check Exception
1027
1028 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1029
1030 md= [HW] RAID subsystems devices and level
1031 See Documentation/md.txt.
1032
1033 mdacon= [MDA]
1034 Format: <first>,<last>
1035 Specifies range of consoles to be captured by the MDA.
1036
1037 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1038 Amount of memory to be used when the kernel is not able
1039 to see the whole system memory or for test.
1040 [X86-32] Use together with memmap= to avoid physical
1041 address space collisions. Without memmap= PCI devices
1042 could be placed at addresses belonging to unused RAM.
1043
1044 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1045 memory.
1046
1047 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1048 E820 memory map, as specified by the user.
1049 Such memmap=exactmap lines can be constructed based on
1050 BIOS output or other requirements. See the memmap=nn@ss
1051 option description.
1052
1053 memmap=nn[KMG]@ss[KMG]
1054 [KNL] Force usage of a specific region of memory
1055 Region of memory to be used, from ss to ss+nn.
1056
1057 memmap=nn[KMG]#ss[KMG]
1058 [KNL,ACPI] Mark specific memory as ACPI data.
1059 Region of memory to be used, from ss to ss+nn.
1060
1061 memmap=nn[KMG]$ss[KMG]
1062 [KNL,ACPI] Mark specific memory as reserved.
1063 Region of memory to be used, from ss to ss+nn.
1064
1065 meye.*= [HW] Set MotionEye Camera parameters
1066 See Documentation/video4linux/meye.txt.
1067
1068 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1069 Multi-Function General Purpose Timers on AMD Geode
1070 platforms.
1071
1072 mga= [HW,DRM]
1073
1074 mousedev.tap_time=
1075 [MOUSE] Maximum time between finger touching and
1076 leaving touchpad surface for touch to be considered
1077 a tap and be reported as a left button click (for
1078 touchpads working in absolute mode only).
1079 Format: <msecs>
1080 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1081 reporting absolute coordinates, such as tablets
1082 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1083 reporting absolute coordinates, such as tablets
1084
1085 mpu401= [HW,OSS]
1086 Format: <io>,<irq>
1087
1088 MTD_Partition= [MTD]
1089 Format: <name>,<region-number>,<size>,<offset>
1090
1091 MTD_Region= [MTD] Format:
1092 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1093
1094 mtdparts= [MTD]
1095 See drivers/mtd/cmdlinepart.c.
1096
1097 mtouchusb.raw_coordinates=
1098 [HW] Make the MicroTouch USB driver use raw coordinates
1099 ('y', default) or cooked coordinates ('n')
1100
1101 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1102
1103 NCR_D700= [HW,SCSI]
1104 See header of drivers/scsi/NCR_D700.c.
1105
1106 ncr5380= [HW,SCSI]
1107
1108 ncr53c400= [HW,SCSI]
1109
1110 ncr53c400a= [HW,SCSI]
1111
1112 ncr53c406a= [HW,SCSI]
1113
1114 ncr53c8xx= [HW,SCSI]
1115
1116 netdev= [NET] Network devices parameters
1117 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1118 Note that mem_start is often overloaded to mean
1119 something different and driver-specific.
1120 This usage is only documented in each driver source
1121 file if at all.
1122
1123 nfsaddrs= [NFS]
1124 See Documentation/nfsroot.txt.
1125
1126 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1127 See Documentation/nfsroot.txt.
1128
1129 nfs.callback_tcpport=
1130 [NFS] set the TCP port on which the NFSv4 callback
1131 channel should listen.
1132
1133 nfs.idmap_cache_timeout=
1134 [NFS] set the maximum lifetime for idmapper cache
1135 entries.
1136
1137 nfs.enable_ino64=
1138 [NFS] enable 64-bit inode numbers.
1139 If zero, the NFS client will fake up a 32-bit inode
1140 number for the readdir() and stat() syscalls instead
1141 of returning the full 64-bit number.
1142 The default is to return 64-bit inode numbers.
1143
1144 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1145 when a NMI is triggered.
1146 Format: [state][,regs][,debounce][,die]
1147
1148 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1149
1150 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1151 emulation library even if a 387 maths coprocessor
1152 is present.
1153
1154 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1155 caches in the slab allocator. Saves per-node memory,
1156 but will impact performance.
1157
1158 noalign [KNL,ARM]
1159
1160 noapic [SMP,APIC] Tells the kernel to not make use of any
1161 IOAPICs that may be present in the system.
1162
1163 nobats [PPC] Do not use BATs for mapping kernel lowmem
1164 on "Classic" PPC cores.
1165
1166 nocache [ARM]
1167
1168 nodelayacct [KNL] Disable per-task delay accounting
1169
1170 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1171
1172 noexec [IA-64]
1173
1174 noexec [X86-32,X86-64]
1175 noexec=on: enable non-executable mappings (default)
1176 noexec=off: disable nn-executable mappings
1177
1178 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1179 register save and restore. The kernel will only save
1180 legacy floating-point registers on task switch.
1181
1182 nohlt [BUGS=ARM]
1183
1184 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1185 instruction doesn't work correctly and not to
1186 use it.
1187
1188 nohalt [IA-64] Tells the kernel not to use the power saving
1189 function PAL_HALT_LIGHT when idle. This increases
1190 power-consumption. On the positive side, it reduces
1191 interrupt wake-up latency, which may improve performance
1192 in certain environments such as networked servers or
1193 real-time systems.
1194
1195 nohz= [KNL] Boottime enable/disable dynamic ticks
1196 Valid arguments: on, off
1197 Default: on
1198
1199 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1200
1201 noirqdebug [X86-32] Disables the code which attempts to detect and
1202 disable unhandled interrupt sources.
1203
1204 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1205 broken timer IRQ sources.
1206
1207 noisapnp [ISAPNP] Disables ISA PnP code.
1208
1209 noinitrd [RAM] Tells the kernel not to load any configured
1210 initial RAM disk.
1211
1212 nointroute [IA-64]
1213
1214 nojitter [IA64] Disables jitter checking for ITC timers.
1215
1216 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1217
1218 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1219
1220 noltlbs [PPC] Do not use large page/tlb entries for kernel
1221 lowmem mapping on PPC40x.
1222
1223 nomca [IA-64] Disable machine check abort handling
1224
1225 nomce [X86-32] Machine Check Exception
1226
1227 nomfgpt [X86-32] Disable Multi-Function General Purpose
1228 Timer usage (for AMD Geode machines).
1229
1230 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1231
1232 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1233 with UP alternatives
1234
1235 noresidual [PPC] Don't use residual data on PReP machines.
1236
1237 noresume [SWSUSP] Disables resume and restores original swap
1238 space.
1239
1240 no-scroll [VGA] Disables scrollback.
1241 This is required for the Braillex ib80-piezo Braille
1242 reader made by F.H. Papenmeier (Germany).
1243
1244 nosbagart [IA-64]
1245
1246 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1247
1248 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1249 and disable the IO APIC. legacy for "maxcpus=0".
1250
1251 nosoftlockup [KNL] Disable the soft-lockup detector.
1252
1253 nosync [HW,M68K] Disables sync negotiation for all devices.
1254
1255 notsc [BUGS=X86-32] Disable Time Stamp Counter
1256
1257 nousb [USB] Disable the USB subsystem
1258
1259 nowb [ARM]
1260
1261 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1262 one of ['zone', 'node', 'default'] can be specified
1263 This can be set from sysctl after boot.
1264 See Documentation/sysctl/vm.txt for details.
1265
1266 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1267
1268 opl3= [HW,OSS]
1269 Format: <io>
1270
1271 oprofile.timer= [HW]
1272 Use timer interrupt instead of performance counters
1273
1274 osst= [HW,SCSI] SCSI Tape Driver
1275 Format: <buffer_size>,<write_threshold>
1276 See also Documentation/scsi/st.txt.
1277
1278 panic= [KNL] Kernel behaviour on panic
1279 Format: <timeout>
1280
1281 parkbd.port= [HW] Parallel port number the keyboard adapter is
1282 connected to, default is 0.
1283 Format: <parport#>
1284 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1285 0 for XT, 1 for AT (default is AT).
1286 Format: <mode>
1287
1288 parport= [HW,PPT] Specify parallel ports. 0 disables.
1289 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1290 Use 'auto' to force the driver to use any
1291 IRQ/DMA settings detected (the default is to
1292 ignore detected IRQ/DMA settings because of
1293 possible conflicts). You can specify the base
1294 address, IRQ, and DMA settings; IRQ and DMA
1295 should be numbers, or 'auto' (for using detected
1296 settings on that particular port), or 'nofifo'
1297 (to avoid using a FIFO even if it is detected).
1298 Parallel ports are assigned in the order they
1299 are specified on the command line, starting
1300 with parport0.
1301
1302 parport_init_mode= [HW,PPT]
1303 Configure VIA parallel port to operate in
1304 a specific mode. This is necessary on Pegasos
1305 computer where firmware has no options for setting
1306 up parallel port mode and sets it to spp.
1307 Currently this function knows 686a and 8231 chips.
1308 Format: [spp|ps2|epp|ecp|ecpepp]
1309
1310 pas2= [HW,OSS] Format:
1311 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1312
1313 pas16= [HW,SCSI]
1314 See header of drivers/scsi/pas16.c.
1315
1316 pause_on_oops=
1317 Halt all CPUs after the first oops has been printed for
1318 the specified number of seconds. This is to be used if
1319 your oopses keep scrolling off the screen.
1320
1321 pcbit= [HW,ISDN]
1322
1323 pcd. [PARIDE]
1324 See header of drivers/block/paride/pcd.c.
1325 See also Documentation/paride.txt.
1326
1327 pci=option[,option...] [PCI] various PCI subsystem options:
1328 off [X86-32] don't probe for the PCI bus
1329 bios [X86-32] force use of PCI BIOS, don't access
1330 the hardware directly. Use this if your machine
1331 has a non-standard PCI host bridge.
1332 nobios [X86-32] disallow use of PCI BIOS, only direct
1333 hardware access methods are allowed. Use this
1334 if you experience crashes upon bootup and you
1335 suspect they are caused by the BIOS.
1336 conf1 [X86-32] Force use of PCI Configuration
1337 Mechanism 1.
1338 conf2 [X86-32] Force use of PCI Configuration
1339 Mechanism 2.
1340 noaer [PCIE] If the PCIEAER kernel config parameter is
1341 enabled, this kernel boot option can be used to
1342 disable the use of PCIE advanced error reporting.
1343 nodomains [PCI] Disable support for multiple PCI
1344 root domains (aka PCI segments, in ACPI-speak).
1345 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1346 Configuration
1347 nomsi [MSI] If the PCI_MSI kernel config parameter is
1348 enabled, this kernel boot option can be used to
1349 disable the use of MSI interrupts system-wide.
1350 nosort [X86-32] Don't sort PCI devices according to
1351 order given by the PCI BIOS. This sorting is
1352 done to get a device order compatible with
1353 older kernels.
1354 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1355 routing table. These calls are known to be buggy
1356 on several machines and they hang the machine
1357 when used, but on other computers it's the only
1358 way to get the interrupt routing table. Try
1359 this option if the kernel is unable to allocate
1360 IRQs or discover secondary PCI buses on your
1361 motherboard.
1362 rom [X86-32] Assign address space to expansion ROMs.
1363 Use with caution as certain devices share
1364 address decoders between ROMs and other
1365 resources.
1366 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1367 assigned automatically to PCI devices. You can
1368 make the kernel exclude IRQs of your ISA cards
1369 this way.
1370 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1371 of the PIRQ table (normally generated
1372 by the BIOS) if it is outside the
1373 F0000h-100000h range.
1374 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1375 useful if the kernel is unable to find your
1376 secondary buses and you want to tell it
1377 explicitly which ones they are.
1378 assign-busses [X86-32] Always assign all PCI bus
1379 numbers ourselves, overriding
1380 whatever the firmware may have done.
1381 usepirqmask [X86-32] Honor the possible IRQ mask stored
1382 in the BIOS $PIR table. This is needed on
1383 some systems with broken BIOSes, notably
1384 some HP Pavilion N5400 and Omnibook XE3
1385 notebooks. This will have no effect if ACPI
1386 IRQ routing is enabled.
1387 noacpi [X86-32] Do not use ACPI for IRQ routing
1388 or for PCI scanning.
1389 use_crs [X86-32] Use _CRS for PCI resource
1390 allocation.
1391 routeirq Do IRQ routing for all PCI devices.
1392 This is normally done in pci_enable_device(),
1393 so this option is a temporary workaround
1394 for broken drivers that don't call it.
1395 firmware [ARM] Do not re-enumerate the bus but instead
1396 just use the configuration from the
1397 bootloader. This is currently used on
1398 IXP2000 systems where the bus has to be
1399 configured a certain way for adjunct CPUs.
1400 noearly [X86] Don't do any early type 1 scanning.
1401 This might help on some broken boards which
1402 machine check when some devices' config space
1403 is read. But various workarounds are disabled
1404 and some IOMMU drivers will not work.
1405 bfsort Sort PCI devices into breadth-first order.
1406 This sorting is done to get a device
1407 order compatible with older (<= 2.4) kernels.
1408 nobfsort Don't sort PCI devices into breadth-first order.
1409 cbiosize=nn[KMG] The fixed amount of bus space which is
1410 reserved for the CardBus bridge's IO window.
1411 The default value is 256 bytes.
1412 cbmemsize=nn[KMG] The fixed amount of bus space which is
1413 reserved for the CardBus bridge's memory
1414 window. The default value is 64 megabytes.
1415
1416 pcmv= [HW,PCMCIA] BadgePAD 4
1417
1418 pd. [PARIDE]
1419 See Documentation/paride.txt.
1420
1421 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1422 boot time.
1423 Format: { 0 | 1 }
1424 See arch/parisc/kernel/pdc_chassis.c
1425
1426 pf. [PARIDE]
1427 See Documentation/paride.txt.
1428
1429 pg. [PARIDE]
1430 See Documentation/paride.txt.
1431
1432 pirq= [SMP,APIC] Manual mp-table setup
1433 See Documentation/i386/IO-APIC.txt.
1434
1435 plip= [PPT,NET] Parallel port network link
1436 Format: { parport<nr> | timid | 0 }
1437 See also Documentation/parport.txt.
1438
1439 pnpacpi= [ACPI]
1440 { off }
1441
1442 pnpbios= [ISAPNP]
1443 { on | off | curr | res | no-curr | no-res }
1444
1445 pnp_reserve_irq=
1446 [ISAPNP] Exclude IRQs for the autoconfiguration
1447
1448 pnp_reserve_dma=
1449 [ISAPNP] Exclude DMAs for the autoconfiguration
1450
1451 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1452 Ranges are in pairs (I/O port base and size).
1453
1454 pnp_reserve_mem=
1455 [ISAPNP] Exclude memory regions for the
1456 autoconfiguration.
1457 Ranges are in pairs (memory base and size).
1458
1459 print-fatal-signals=
1460 [KNL] debug: print fatal signals
1461 print-fatal-signals=1: print segfault info to
1462 the kernel console.
1463 default: off.
1464
1465 printk.time= Show timing data prefixed to each printk message line
1466 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1467
1468 profile= [KNL] Enable kernel profiling via /proc/profile
1469 Format: [schedule,]<number>
1470 Param: "schedule" - profile schedule points.
1471 Param: <number> - step/bucket size as a power of 2 for
1472 statistical time based profiling.
1473 Param: "sleep" - profile D-state sleeping (millisecs).
1474 Requires CONFIG_SCHEDSTATS
1475 Param: "kvm" - profile VM exits.
1476
1477 processor.max_cstate= [HW,ACPI]
1478 Limit processor to maximum C-state
1479 max_cstate=9 overrides any DMI blacklist limit.
1480
1481 processor.nocst [HW,ACPI]
1482 Ignore the _CST method to determine C-states,
1483 instead using the legacy FADT method
1484
1485 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1486 before loading.
1487 See Documentation/ramdisk.txt.
1488
1489 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1490 probe for; one of (bare|imps|exps|lifebook|any).
1491 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1492 per second.
1493 psmouse.resetafter= [HW,MOUSE]
1494 Try to reset the device after so many bad packets
1495 (0 = never).
1496 psmouse.resolution=
1497 [HW,MOUSE] Set desired mouse resolution, in dpi.
1498 psmouse.smartscroll=
1499 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1500 0 = disabled, 1 = enabled (default).
1501
1502 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1503 Format:
1504 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1505
1506 pt. [PARIDE]
1507 See Documentation/paride.txt.
1508
1509 pty.legacy_count=
1510 [KNL] Number of legacy pty's. Overwrites compiled-in
1511 default number.
1512
1513 quiet [KNL] Disable most log messages
1514
1515 r128= [HW,DRM]
1516
1517 raid= [HW,RAID]
1518 See Documentation/md.txt.
1519
1520 ramdisk_blocksize= [RAM]
1521 See Documentation/ramdisk.txt.
1522
1523 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1524 See Documentation/ramdisk.txt.
1525
1526 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1527 RCU callbacks to process in one batch.
1528
1529 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1530 RCU callbacks over which batch limiting is disabled.
1531
1532 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1533 RCU callbacks below which batch limiting is re-enabled.
1534
1535 rdinit= [KNL]
1536 Format: <full_path>
1537 Run specified binary instead of /init from the ramdisk,
1538 used for early userspace startup. See initrd.
1539
1540 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1541 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1542 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1543
1544 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1545
1546 reservetop= [X86-32]
1547 Format: nn[KMG]
1548 Reserves a hole at the top of the kernel virtual
1549 address space.
1550
1551 reset_devices [KNL] Force drivers to reset the underlying device
1552 during initialization.
1553
1554 resume= [SWSUSP]
1555 Specify the partition device for software suspend
1556
1557 resume_offset= [SWSUSP]
1558 Specify the offset from the beginning of the partition
1559 given by "resume=" at which the swap header is located,
1560 in <PAGE_SIZE> units (needed only for swap files).
1561 See Documentation/power/swsusp-and-swap-files.txt
1562
1563 retain_initrd [RAM] Keep initrd memory after extraction
1564
1565 rhash_entries= [KNL,NET]
1566 Set number of hash buckets for route cache
1567
1568 riscom8= [HW,SERIAL]
1569 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1570
1571 ro [KNL] Mount root device read-only on boot
1572
1573 root= [KNL] Root filesystem
1574
1575 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1576 mount the root filesystem
1577
1578 rootflags= [KNL] Set root filesystem mount option string
1579
1580 rootfstype= [KNL] Set root filesystem type
1581
1582 rootwait [KNL] Wait (indefinitely) for root device to show up.
1583 Useful for devices that are detected asynchronously
1584 (e.g. USB and MMC devices).
1585
1586 root_plug.vendor_id=
1587 [ROOTPLUG] Override the default vendor ID
1588
1589 root_plug.product_id=
1590 [ROOTPLUG] Override the default product ID
1591
1592 root_plug.debug=
1593 [ROOTPLUG] Enable debugging output
1594
1595 rw [KNL] Mount root device read-write on boot
1596
1597 S [KNL] Run init in single mode
1598
1599 sa1100ir [NET]
1600 See drivers/net/irda/sa1100_ir.c.
1601
1602 sbni= [NET] Granch SBNI12 leased line adapter
1603
1604 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1605 Format: <io>[,<timeout>[,<isapnp>]]
1606
1607 scsi_debug_*= [SCSI]
1608 See drivers/scsi/scsi_debug.c.
1609
1610 scsi_default_dev_flags=
1611 [SCSI] SCSI default device flags
1612 Format: <integer>
1613
1614 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1615 Format: <vendor>:<model>:<flags>
1616 (flags are integer value)
1617
1618 scsi_logging_level= [SCSI] a bit mask of logging levels
1619 See drivers/scsi/scsi_logging.h for bits. Also
1620 settable via sysctl at dev.scsi.logging_level
1621 (/proc/sys/dev/scsi/logging_level).
1622 There is also a nice 'scsi_logging_level' script in the
1623 S390-tools package, available for download at
1624 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1625
1626 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1627 discovered. async scans them in kernel threads,
1628 allowing boot to proceed. none ignores them, expecting
1629 user space to do the scan.
1630
1631 selinux [SELINUX] Disable or enable SELinux at boot time.
1632 Format: { "0" | "1" }
1633 See security/selinux/Kconfig help text.
1634 0 -- disable.
1635 1 -- enable.
1636 Default value is set via kernel config option.
1637 If enabled at boot time, /selinux/disable can be used
1638 later to disable prior to initial policy load.
1639
1640 selinux_compat_net =
1641 [SELINUX] Set initial selinux_compat_net flag value.
1642 Format: { "0" | "1" }
1643 0 -- use new secmark-based packet controls
1644 1 -- use legacy packet controls
1645 Default value is 0 (preferred).
1646 Value can be changed at runtime via
1647 /selinux/compat_net.
1648
1649 serialnumber [BUGS=X86-32]
1650
1651 shapers= [NET]
1652 Maximal number of shapers.
1653
1654 sim710= [SCSI,HW]
1655 See header of drivers/scsi/sim710.c.
1656
1657 simeth= [IA-64]
1658 simscsi=
1659
1660 slram= [HW,MTD]
1661
1662 slub_debug[=options[,slabs]] [MM, SLUB]
1663 Enabling slub_debug allows one to determine the
1664 culprit if slab objects become corrupted. Enabling
1665 slub_debug can create guard zones around objects and
1666 may poison objects when not in use. Also tracks the
1667 last alloc / free. For more information see
1668 Documentation/vm/slub.txt.
1669
1670 slub_max_order= [MM, SLUB]
1671 Determines the maximum allowed order for slabs.
1672 A high setting may cause OOMs due to memory
1673 fragmentation. For more information see
1674 Documentation/vm/slub.txt.
1675
1676 slub_min_objects= [MM, SLUB]
1677 The minimum number of objects per slab. SLUB will
1678 increase the slab order up to slub_max_order to
1679 generate a sufficiently large slab able to contain
1680 the number of objects indicated. The higher the number
1681 of objects the smaller the overhead of tracking slabs
1682 and the less frequently locks need to be acquired.
1683 For more information see Documentation/vm/slub.txt.
1684
1685 slub_min_order= [MM, SLUB]
1686 Determines the mininum page order for slabs. Must be
1687 lower than slub_max_order.
1688 For more information see Documentation/vm/slub.txt.
1689
1690 slub_nomerge [MM, SLUB]
1691 Disable merging of slabs with similar size. May be
1692 necessary if there is some reason to distinguish
1693 allocs to different slabs. Debug options disable
1694 merging on their own.
1695 For more information see Documentation/vm/slub.txt.
1696
1697 smart2= [HW]
1698 Format: <io1>[,<io2>[,...,<io8>]]
1699
1700 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1701 attempt to substitute SMP alternatives once at boot.
1702
1703 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1704 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1705 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1706 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1707 smsc-ircc2.ircc_irq= [HW] IRQ line
1708 smsc-ircc2.ircc_dma= [HW] DMA channel
1709 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1710 0: Toshiba Satellite 1800 (GP data pin select)
1711 1: Fast pin select (default)
1712 2: ATC IRMode
1713
1714 snd-ad1816a= [HW,ALSA]
1715
1716 snd-ad1848= [HW,ALSA]
1717
1718 snd-ali5451= [HW,ALSA]
1719
1720 snd-als100= [HW,ALSA]
1721
1722 snd-als4000= [HW,ALSA]
1723
1724 snd-azt2320= [HW,ALSA]
1725
1726 snd-cmi8330= [HW,ALSA]
1727
1728 snd-cmipci= [HW,ALSA]
1729
1730 snd-cs4231= [HW,ALSA]
1731
1732 snd-cs4232= [HW,ALSA]
1733
1734 snd-cs4236= [HW,ALSA]
1735
1736 snd-cs4281= [HW,ALSA]
1737
1738 snd-cs46xx= [HW,ALSA]
1739
1740 snd-dt019x= [HW,ALSA]
1741
1742 snd-dummy= [HW,ALSA]
1743
1744 snd-emu10k1= [HW,ALSA]
1745
1746 snd-ens1370= [HW,ALSA]
1747
1748 snd-ens1371= [HW,ALSA]
1749
1750 snd-es968= [HW,ALSA]
1751
1752 snd-es1688= [HW,ALSA]
1753
1754 snd-es18xx= [HW,ALSA]
1755
1756 snd-es1938= [HW,ALSA]
1757
1758 snd-es1968= [HW,ALSA]
1759
1760 snd-fm801= [HW,ALSA]
1761
1762 snd-gusclassic= [HW,ALSA]
1763
1764 snd-gusextreme= [HW,ALSA]
1765
1766 snd-gusmax= [HW,ALSA]
1767
1768 snd-hdsp= [HW,ALSA]
1769
1770 snd-ice1712= [HW,ALSA]
1771
1772 snd-intel8x0= [HW,ALSA]
1773
1774 snd-interwave= [HW,ALSA]
1775
1776 snd-interwave-stb=
1777 [HW,ALSA]
1778
1779 snd-korg1212= [HW,ALSA]
1780
1781 snd-maestro3= [HW,ALSA]
1782
1783 snd-mpu401= [HW,ALSA]
1784
1785 snd-mtpav= [HW,ALSA]
1786
1787 snd-nm256= [HW,ALSA]
1788
1789 snd-opl3sa2= [HW,ALSA]
1790
1791 snd-opti92x-ad1848=
1792 [HW,ALSA]
1793
1794 snd-opti92x-cs4231=
1795 [HW,ALSA]
1796
1797 snd-opti93x= [HW,ALSA]
1798
1799 snd-pmac= [HW,ALSA]
1800
1801 snd-rme32= [HW,ALSA]
1802
1803 snd-rme96= [HW,ALSA]
1804
1805 snd-rme9652= [HW,ALSA]
1806
1807 snd-sb8= [HW,ALSA]
1808
1809 snd-sb16= [HW,ALSA]
1810
1811 snd-sbawe= [HW,ALSA]
1812
1813 snd-serial= [HW,ALSA]
1814
1815 snd-sgalaxy= [HW,ALSA]
1816
1817 snd-sonicvibes= [HW,ALSA]
1818
1819 snd-sun-amd7930=
1820 [HW,ALSA]
1821
1822 snd-sun-cs4231= [HW,ALSA]
1823
1824 snd-trident= [HW,ALSA]
1825
1826 snd-usb-audio= [HW,ALSA,USB]
1827
1828 snd-via82xx= [HW,ALSA]
1829
1830 snd-virmidi= [HW,ALSA]
1831
1832 snd-wavefront= [HW,ALSA]
1833
1834 snd-ymfpci= [HW,ALSA]
1835
1836 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1837 See Documentation/sonypi.txt
1838
1839 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1840 See Documentation/specialix.txt.
1841
1842 spia_io_base= [HW,MTD]
1843 spia_fio_base=
1844 spia_pedr=
1845 spia_peddr=
1846
1847 sscape= [HW,OSS]
1848 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1849
1850 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1851 See Documentation/scsi/st.txt.
1852
1853 st0x= [HW,SCSI]
1854 See header of drivers/scsi/seagate.c.
1855
1856 sti= [PARISC,HW]
1857 Format: <num>
1858 Set the STI (builtin display/keyboard on the HP-PARISC
1859 machines) console (graphic card) which should be used
1860 as the initial boot-console.
1861 See also comment in drivers/video/console/sticore.c.
1862
1863 sti_font= [HW]
1864 See comment in drivers/video/console/sticore.c.
1865
1866 stifb= [HW]
1867 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1868
1869 sunrpc.pool_mode=
1870 [NFS]
1871 Control how the NFS server code allocates CPUs to
1872 service thread pools. Depending on how many NICs
1873 you have and where their interrupts are bound, this
1874 option will affect which CPUs will do NFS serving.
1875 Note: this parameter cannot be changed while the
1876 NFS server is running.
1877
1878 auto the server chooses an appropriate mode
1879 automatically using heuristics
1880 global a single global pool contains all CPUs
1881 percpu one pool for each CPU
1882 pernode one pool for each NUMA node (equivalent
1883 to global on non-NUMA machines)
1884
1885 swiotlb= [IA-64] Number of I/O TLB slabs
1886
1887 switches= [HW,M68k]
1888
1889 sym53c416= [HW,SCSI]
1890 See header of drivers/scsi/sym53c416.c.
1891
1892 sysrq_always_enabled
1893 [KNL]
1894 Ignore sysrq setting - this boot parameter will
1895 neutralize any effect of /proc/sys/kernel/sysrq.
1896 Useful for debugging.
1897
1898 t128= [HW,SCSI]
1899 See header of drivers/scsi/t128.c.
1900
1901 tdfx= [HW,DRM]
1902
1903 thash_entries= [KNL,NET]
1904 Set number of hash buckets for TCP connection
1905
1906 thermal.act= [HW,ACPI]
1907 -1: disable all active trip points in all thermal zones
1908 <degrees C>: override all lowest active trip points
1909
1910 thermal.crt= [HW,ACPI]
1911 -1: disable all critical trip points in all thermal zones
1912 <degrees C>: lower all critical trip points
1913
1914 thermal.nocrt= [HW,ACPI]
1915 Set to disable actions on ACPI thermal zone
1916 critical and hot trip points.
1917
1918 thermal.off= [HW,ACPI]
1919 1: disable ACPI thermal control
1920
1921 thermal.psv= [HW,ACPI]
1922 -1: disable all passive trip points
1923 <degrees C>: override all passive trip points to this value
1924
1925 thermal.tzp= [HW,ACPI]
1926 Specify global default ACPI thermal zone polling rate
1927 <deci-seconds>: poll all this frequency
1928 0: no polling (default)
1929
1930 time Show timing data prefixed to each printk message line
1931 [deprecated, see 'printk.time']
1932
1933 tipar.timeout= [HW,PPT]
1934 Set communications timeout in tenths of a second
1935 (default 15).
1936
1937 tipar.delay= [HW,PPT]
1938 Set inter-bit delay in microseconds (default 10).
1939
1940 tmc8xx= [HW,SCSI]
1941 See header of drivers/scsi/seagate.c.
1942
1943 tmscsim= [HW,SCSI]
1944 See comment before function dc390_setup() in
1945 drivers/scsi/tmscsim.c.
1946
1947 tp720= [HW,PS2]
1948
1949 trix= [HW,OSS] MediaTrix AudioTrix Pro
1950 Format:
1951 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1952
1953 turbografx.map[2|3]= [HW,JOY]
1954 TurboGraFX parallel port interface
1955 Format:
1956 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1957 See also Documentation/input/joystick-parport.txt
1958
1959 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1960 See header of drivers/scsi/u14-34f.c.
1961
1962 uart401= [HW,OSS]
1963 Format: <io>,<irq>
1964
1965 uart6850= [HW,OSS]
1966 Format: <io>,<irq>
1967
1968 uhci-hcd.ignore_oc=
1969 [USB] Ignore overcurrent events (default N).
1970 Some badly-designed motherboards generate lots of
1971 bogus events, for ports that aren't wired to
1972 anything. Set this parameter to avoid log spamming.
1973 Note that genuine overcurrent events won't be
1974 reported either.
1975
1976 usbcore.autosuspend=
1977 [USB] The autosuspend time delay (in seconds) used
1978 for newly-detected USB devices (default 2). This
1979 is the time required before an idle device will be
1980 autosuspended. Devices for which the delay is set
1981 to a negative value won't be autosuspended at all.
1982
1983 usbhid.mousepoll=
1984 [USBHID] The interval which mice are to be polled at.
1985
1986 vdso= [X86-32,SH,x86-64]
1987 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1988 vdso=1: enable VDSO (default)
1989 vdso=0: disable VDSO mapping
1990
1991 vdso32= [X86-32,X86-64]
1992 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
1993 vdso32=1: enable 32-bit VDSO (default)
1994 vdso32=0: disable 32-bit VDSO mapping
1995
1996 vector= [IA-64,SMP]
1997 vector=percpu: enable percpu vector domain
1998
1999 video= [FB] Frame buffer configuration
2000 See Documentation/fb/modedb.txt.
2001
2002 vga= [BOOT,X86-32] Select a particular video mode
2003 See Documentation/i386/boot.txt and
2004 Documentation/svga.txt.
2005 Use vga=ask for menu.
2006 This is actually a boot loader parameter; the value is
2007 passed to the kernel using a special protocol.
2008
2009 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2010 size of <nn>. This can be used to increase the
2011 minimum size (128MB on x86). It can also be used to
2012 decrease the size and leave more room for directly
2013 mapped kernel RAM.
2014
2015 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2016 Format: <command>
2017
2018 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2019 Format: <command>
2020
2021 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2022 Format: <command>
2023
2024 waveartist= [HW,OSS]
2025 Format: <io>,<irq>,<dma>,<dma2>
2026
2027 wd33c93= [HW,SCSI]
2028 See header of drivers/scsi/wd33c93.c.
2029
2030 wd7000= [HW,SCSI]
2031 See header of drivers/scsi/wd7000.c.
2032
2033 wdt= [WDT] Watchdog
2034 See Documentation/watchdog/wdt.txt.
2035
2036 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2037 xd_geo= See header of drivers/block/xd.c.
2038
2039 xirc2ps_cs= [NET,PCMCIA]
2040 Format:
2041 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2042
2043 norandmaps Don't use address space randomization
2044 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2045
2046 ______________________________________________________________________
2047
2048 TODO:
2049
2050 Add documentation for ALSA options.
2051 Add more DRM drivers.