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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
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.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
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:
18 usbcore.blinkenlights=1
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}".
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:
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 .
104 In addition, the following text indicates that the option:
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.
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>.
115 There are also arch-specific kernel-parameters not documented here.
116 See for example <Documentation/x86_64/boot-options.txt>.
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.
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.
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.
141 <<<<<<< HEAD:Documentation/kernel-parameters.txt
142 See also Documentation/pm.txt, pci=noacpi
143 =======
144 See also Documentation/power/pm.txt, pci=noacpi
145 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
147 acpi_apic_instance= [ACPI, IOAPIC]
148 Format: <int>
149 2: use 2nd APIC table, if available
150 1,0: use 1st APIC table
151 default: 0
153 acpi_sleep= [HW,ACPI] Sleep options
154 Format: { s3_bios, s3_mode, s3_beep }
155 See Documentation/power/video.txt for s3_bios and s3_mode.
156 s3_beep is for debugging; it makes the PC's speaker beep
157 as soon as the kernel's real-mode entry point is called.
159 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
160 Format: { level | edge | high | low }
162 acpi_irq_balance [HW,ACPI]
163 ACPI will balance active IRQs
164 default in APIC mode
166 acpi_irq_nobalance [HW,ACPI]
167 ACPI will not move active IRQs (default)
168 default in PIC mode
170 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
171 use by PCI
172 Format: <irq>,<irq>...
174 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
175 Format: <irq>,<irq>...
177 acpi_new_pts_ordering [HW,ACPI]
178 Enforce the ACPI 2.0 ordering of the _PTS control
179 method wrt putting devices into low power states
180 default: pre ACPI 2.0 ordering of _PTS
182 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
184 <<<<<<< HEAD:Documentation/kernel-parameters.txt
185 acpi_no_initrd_override [KNL,ACPI]
186 Disable loading custom ACPI tables from the initramfs
188 =======
189 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
190 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
191 Format: To spoof as Windows 98: ="Microsoft Windows"
193 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
194 acpi_osi="string1" # add string1 -- only one string
195 acpi_osi="!string2" # remove built-in string2
196 acpi_osi= # disable all strings
198 acpi_serialize [HW,ACPI] force serialization of AML methods
200 acpi_skip_timer_override [HW,ACPI]
201 Recognize and ignore IRQ0/pin2 Interrupt Override.
202 For broken nForce2 BIOS resulting in XT-PIC timer.
203 acpi_use_timer_override [HW,ACPI}
204 Use timer override. For some broken Nvidia NF5 boards
205 that require a timer override, but don't have
206 HPET
208 acpi.debug_layer= [HW,ACPI]
209 Format: <int>
210 Each bit of the <int> indicates an ACPI debug layer,
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_layer.
214 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
215 Available bits (add the numbers together) to enable debug output
216 for specific parts of the ACPI subsystem:
217 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
218 0x10 namespace 0x20 parser 0x40 dispatcher
219 0x80 executer 0x100 resources 0x200 acpica debugger
220 0x400 os services 0x800 acpica disassembler.
221 The number can be in decimal or prefixed with 0x in hex.
222 Warning: Many of these options can produce a lot of
223 output and make your system unusable. Be very careful.
225 acpi.debug_level= [HW,ACPI]
226 Format: <int>
227 Each bit of the <int> indicates an ACPI debug level,
228 1: enable, 0: disable. It is useful for boot time
229 debugging. After system has booted up, it can be set
230 via /sys/module/acpi/parameters/debug_level.
231 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
232 Available bits (add the numbers together) to enable different
233 debug output levels of the ACPI subsystem:
234 0x01 error 0x02 warn 0x04 init 0x08 debug object
235 0x10 info 0x20 init names 0x40 parse 0x80 load
236 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
237 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
238 0x10000 resources 0x20000 user requests 0x40000 package.
239 The number can be in decimal or prefixed with 0x in hex.
240 Warning: Many of these options can produce a lot of
241 output and make your system unusable. Be very careful.
243 acpi_pm_good [X86-32,X86-64]
244 Override the pmtimer bug detection: force the kernel
245 to assume that this machine's pmtimer latches its value
246 and always returns good values.
248 agp= [AGP]
249 { off | try_unsupported }
250 off: disable AGP support
251 try_unsupported: try to drive unsupported chipsets
252 (may crash computer or cause data corruption)
254 enable_timer_pin_1 [i386,x86-64]
255 Enable PIN 1 of APIC timer
256 Can be useful to work around chipset bugs
257 (in particular on some ATI chipsets).
258 The kernel tries to set a reasonable default.
260 disable_timer_pin_1 [i386,x86-64]
261 Disable PIN 1 of APIC timer
262 Can be useful to work around chipset bugs.
264 ad1848= [HW,OSS]
265 Format: <io>,<irq>,<dma>,<dma2>,<type>
267 advansys= [HW,SCSI]
268 See header of drivers/scsi/advansys.c.
270 advwdt= [HW,WDT] Advantech WDT
271 Format: <iostart>,<iostop>
273 aedsp16= [HW,OSS] Audio Excel DSP 16
274 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
275 See also header of sound/oss/aedsp16.c.
277 aha152x= [HW,SCSI]
278 See Documentation/scsi/aha152x.txt.
280 aha1542= [HW,SCSI]
281 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
283 aic7xxx= [HW,SCSI]
284 See Documentation/scsi/aic7xxx.txt.
286 aic79xx= [HW,SCSI]
287 See Documentation/scsi/aic79xx.txt.
289 amijoy.map= [HW,JOY] Amiga joystick support
290 Map of devices attached to JOY0DAT and JOY1DAT
291 Format: <a>,<b>
292 See also Documentation/kernel/input/joystick.txt
294 analog.map= [HW,JOY] Analog joystick and gamepad support
295 Specifies type or capabilities of an analog joystick
296 connected to one of 16 gameports
297 Format: <type1>,<type2>,..<type16>
299 apc= [HW,SPARC]
300 Power management functions (SPARCstation-4/5 + deriv.)
301 Format: noidle
302 Disable APC CPU standby support. SPARCstation-Fox does
303 not play well with APC CPU idle - disable it if you have
304 APC and your system crashes randomly.
306 apic= [APIC,i386] Advanced Programmable Interrupt Controller
307 Change the output verbosity whilst booting
308 Format: { quiet (default) | verbose | debug }
309 Change the amount of debugging information output
310 when initialising the APIC and IO-APIC components.
312 apm= [APM] Advanced Power Management
313 See header of arch/i386/kernel/apm.c.
315 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
316 Format: <io>,<irq>,<nodeID>
318 ataflop= [HW,M68k]
320 atarimouse= [HW,MOUSE] Atari Mouse
322 atascsi= [HW,SCSI] Atari SCSI
324 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
325 EzKey and similar keyboards
327 atkbd.reset= [HW] Reset keyboard during initialization
329 atkbd.set= [HW] Select keyboard code set
330 Format: <int> (2 = AT (default), 3 = PS/2)
332 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
333 keyboards
335 atkbd.softraw= [HW] Choose between synthetic and real raw mode
336 Format: <bool> (0 = real, 1 = synthetic (default))
338 atkbd.softrepeat= [HW]
339 Use software keyboard repeat
341 autotest [IA64]
343 baycom_epp= [HW,AX25]
344 Format: <io>,<mode>
346 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
347 Format: <io>,<mode>
348 See header of drivers/net/hamradio/baycom_par.c.
350 baycom_ser_fdx= [HW,AX25]
351 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
352 Format: <io>,<irq>,<mode>[,<baud>]
353 See header of drivers/net/hamradio/baycom_ser_fdx.c.
355 baycom_ser_hdx= [HW,AX25]
356 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
357 Format: <io>,<irq>,<mode>
358 See header of drivers/net/hamradio/baycom_ser_hdx.c.
360 boot_delay= Milliseconds to delay each printk during boot.
361 Values larger than 10 seconds (10000) are changed to
362 no delay (0).
363 Format: integer
365 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
366 bttv.radio= Most important insmod options are available as
367 kernel args too.
368 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
369 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
371 BusLogic= [HW,SCSI]
372 See drivers/scsi/BusLogic.c, comment before function
373 BusLogic_ParseDriverOptions().
375 c101= [NET] Moxa C101 synchronous serial card
377 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
378 Sometimes CPU hardware bugs make them report the cache
379 size incorrectly. The kernel will attempt work arounds
380 to fix known problems, but for some CPUs it is not
381 possible to determine what the correct size should be.
382 This option provides an override for these situations.
384 capability.disable=
385 [SECURITY] Disable capabilities. This would normally
386 be used only if an alternative security model is to be
387 configured. Potentially dangerous and should only be
388 used if you are entirely sure of the consequences.
390 ccw_timeout_log [S390]
391 See Documentation/s390/CommonIO for details.
393 checkreqprot [SELINUX] Set initial checkreqprot flag value.
394 Format: { "0" | "1" }
395 See security/selinux/Kconfig help text.
396 0 -- check protection applied by kernel (includes
397 any implied execute protection).
398 1 -- check protection requested by application.
399 Default value is set via a kernel config option.
400 Value can be changed at runtime via
401 /selinux/checkreqprot.
403 cio_ignore= [S390]
404 See Documentation/s390/CommonIO for details.
406 cio_msg= [S390]
407 See Documentation/s390/CommonIO for details.
409 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
410 [Deprecated]
411 Forces specified clocksource (if available) to be used
412 when calculating gettimeofday(). If specified
413 clocksource is not available, it defaults to PIT.
414 Format: { pit | tsc | cyclone | pmtmr }
416 clocksource= [GENERIC_TIME] Override the default clocksource
417 Format: <string>
418 Override the default clocksource and use the clocksource
419 with the name specified.
420 Some clocksource names to choose from, depending on
421 the platform:
422 [all] jiffies (this is the base, fallback clocksource)
423 [ACPI] acpi_pm
424 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
425 pxa_timer,timer3,32k_counter,timer0_1
426 [AVR32] avr32
427 [X86-32] pit,hpet,tsc,vmi-timer;
428 scx200_hrt on Geode; cyclone on IBM x440
429 [MIPS] MIPS
430 [PARISC] cr16
431 [S390] tod
432 [SH] SuperH
433 [SPARC64] tick
434 [X86-64] hpet,tsc
436 clearcpuid=BITNUM [X86]
437 Disable CPUID feature X for the kernel. See
438 include/asm-x86/cpufeature.h for the valid bit numbers.
439 Note the Linux specific bits are not necessarily
440 stable over kernel options, but the vendor specific
441 ones should be.
442 Also note that user programs calling CPUID directly
443 or using the feature without checking anything
444 will still see it. This just prevents it from
445 being used by the kernel or shown in /proc/cpuinfo.
446 Also note the kernel might malfunction if you disable
447 some critical bits.
449 code_bytes [IA32/X86_64] How many bytes of object code to print
450 in an oops report.
451 Range: 0 - 8192
452 Default: 64
454 disable_8254_timer
455 enable_8254_timer
456 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
457 over the 8254 in addition to over the IO-APIC. The
458 kernel tries to set a sensible default.
460 hpet= [X86-32,HPET] option to control HPET usage
461 Format: { enable (default) | disable | force }
462 disable: disable HPET and use PIT instead
463 force: allow force enabled of undocumented chips (ICH4,
464 VIA, nVidia)
466 com20020= [HW,NET] ARCnet - COM20020 chipset
467 Format:
468 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
470 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
471 Format: <io>[,<irq>]
473 com90xx= [HW,NET]
474 ARCnet - COM90xx chipset (memory-mapped buffers)
475 Format: <io>[,<irq>[,<memstart>]]
477 condev= [HW,S390] console device
478 conmode=
480 console= [KNL] Output console device and options.
482 tty<n> Use the virtual console device <n>.
484 ttyS<n>[,options]
485 ttyUSB0[,options]
486 Use the specified serial port. The options are of
487 the form "bbbbpnf", where "bbbb" is the baud rate,
488 "p" is parity ("n", "o", or "e"), "n" is number of
489 bits, and "f" is flow control ("r" for RTS or
490 omit it). Default is "9600n8".
492 See Documentation/serial-console.txt for more
493 information. See
494 Documentation/networking/netconsole.txt for an
495 alternative.
497 uart[8250],io,<addr>[,options]
498 uart[8250],mmio,<addr>[,options]
499 Start an early, polled-mode console on the 8250/16550
500 UART at the specified I/O port or MMIO address,
501 switching to the matching ttyS device later. The
502 options are the same as for ttyS, above.
504 earlycon= [KNL] Output early console device and options.
505 uart[8250],io,<addr>[,options]
506 uart[8250],mmio,<addr>[,options]
507 Start an early, polled-mode console on the 8250/16550
508 UART at the specified I/O port or MMIO address.
509 The options are the same as for ttyS, above.
511 no_console_suspend
512 [HW] Never suspend the console
513 Disable suspending of consoles during suspend and
514 hibernate operations. Once disabled, debugging
515 messages can reach various consoles while the rest
516 of the system is being put to sleep (ie, while
517 debugging driver suspend/resume hooks). This may
518 not work reliably with all consoles, but is known
519 to work with serial and VGA consoles.
521 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
522 Format:
523 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
525 crashkernel=nn[KMG]@ss[KMG]
526 [KNL] Reserve a chunk of physical memory to
527 hold a kernel to switch to with kexec on panic.
529 crashkernel=range1:size1[,range2:size2,...][@offset]
530 [KNL] Same as above, but depends on the memory
531 in the running system. The syntax of range is
532 start-[end] where start and end are both
533 a memory unit (amount[KMG]). See also
534 Documentation/kdump/kdump.txt for a example.
536 cs4232= [HW,OSS]
537 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
539 cs89x0_dma= [HW,NET]
540 Format: <dma>
542 cs89x0_media= [HW,NET]
543 Format: { rj45 | aui | bnc }
545 dasd= [HW,NET]
546 See header of drivers/s390/block/dasd_devmap.c.
548 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
549 (one device per port)
550 Format: <port#>,<type>
551 See also Documentation/input/joystick-parport.txt
553 debug [KNL] Enable kernel debugging (events log level).
555 debug_locks_verbose=
556 [KNL] verbose self-tests
557 Format=<0|1>
558 Print debugging info while doing the locking API
559 self-tests.
560 We default to 0 (no extra messages), setting it to
561 1 will print _a lot_ more information - normally
562 only useful to kernel developers.
564 decnet.addr= [HW,NET]
565 Format: <area>[,<node>]
566 See also Documentation/networking/decnet.txt.
568 vt.default_blu= [VT]
569 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
570 Change the default blue palette of the console.
571 This is a 16-member array composed of values
572 ranging from 0-255.
574 vt.default_grn= [VT]
575 Format: <green0>,<green1>,<green2>,...,<green15>
576 Change the default green palette of the console.
577 This is a 16-member array composed of values
578 ranging from 0-255.
580 vt.default_red= [VT]
581 Format: <red0>,<red1>,<red2>,...,<red15>
582 Change the default red palette of the console.
583 This is a 16-member array composed of values
584 ranging from 0-255.
586 vt.default_utf8=
587 [VT]
588 Format=<0|1>
589 Set system-wide default UTF-8 mode for all tty's.
590 Default is 1, i.e. UTF-8 mode is enabled for all
591 newly opened terminals.
593 dhash_entries= [KNL]
594 Set number of hash buckets for dentry cache.
596 digi= [HW,SERIAL]
597 IO parameters + enable/disable command.
599 digiepca= [HW,SERIAL]
600 See drivers/char/README.epca and
601 Documentation/digiepca.txt.
603 disable_mtrr_trim [X86, Intel and AMD only]
604 By default the kernel will trim any uncacheable
605 memory out of your available memory pool based on
606 MTRR settings. This parameter disables that behavior,
607 possibly causing your machine to run very slowly.
609 dmasound= [HW,OSS] Sound subsystem buffers
611 dscc4.setup= [NET]
613 dtc3181e= [HW,SCSI]
615 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
616 earlyprintk=vga
617 earlyprintk=serial[,ttySn[,baudrate]]
619 Append ",keep" to not disable it when the real console
620 takes over.
622 Only vga or serial at a time, not both.
624 Currently only ttyS0 and ttyS1 are supported.
626 Interaction with the standard serial driver is not
627 very good.
629 The VGA output is eventually overwritten by the real
630 console.
632 eata= [HW,SCSI]
634 edd= [EDD]
635 Format: {"of[f]" | "sk[ipmbr]"}
636 See comment in arch/i386/boot/edd.S
638 eisa_irq_edge= [PARISC,HW]
639 See header of drivers/parisc/eisa.c.
641 elanfreq= [X86-32]
642 See comment before function elanfreq_setup() in
643 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
645 elevator= [IOSCHED]
646 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
647 See Documentation/block/as-iosched.txt and
648 Documentation/block/deadline-iosched.txt for details.
650 elfcorehdr= [X86-32, X86_64]
651 Specifies physical address of start of kernel core
652 image elf header. Generally kexec loader will
653 pass this option to capture kernel.
654 See Documentation/kdump/kdump.txt for details.
656 enforcing [SELINUX] Set initial enforcing status.
657 Format: {"0" | "1"}
658 See security/selinux/Kconfig help text.
659 0 -- permissive (log only, no denials).
660 1 -- enforcing (deny and log).
661 Default value is 0.
662 Value can be changed at runtime via /selinux/enforce.
664 es1371= [HW,OSS]
665 Format: <spdif>,[<nomix>,[<amplifier>]]
666 See also header of sound/oss/es1371.c.
668 ether= [HW,NET] Ethernet cards parameters
669 This option is obsoleted by the "netdev=" option, which
670 has equivalent usage. See its documentation for details.
672 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
673 Format: <io>[,<irq>]
675 failslab=
676 fail_page_alloc=
677 fail_make_request=[KNL]
678 General fault injection mechanism.
679 Format: <interval>,<probability>,<space>,<times>
680 See also /Documentation/fault-injection/.
682 fd_mcs= [HW,SCSI]
683 See header of drivers/scsi/fd_mcs.c.
685 fdomain= [HW,SCSI]
686 See header of drivers/scsi/fdomain.c.
688 floppy= [HW]
689 See Documentation/floppy.txt.
691 gamecon.map[2|3]=
692 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
693 support via parallel port (up to 5 devices per port)
694 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
695 See also Documentation/input/joystick-parport.txt
697 gamma= [HW,DRM]
699 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
700 Format: off | on
701 default: on
703 gdth= [HW,SCSI]
704 See header of drivers/scsi/gdth.c.
706 gpt [EFI] Forces disk with valid GPT signature but
707 invalid Protective MBR to be treated as GPT.
709 gvp11= [HW,SCSI]
711 hashdist= [KNL,NUMA] Large hashes allocated during boot
712 are distributed across NUMA nodes. Defaults on
713 for IA-64, off otherwise.
714 Format: 0 | 1 (for off | on)
716 hcl= [IA-64] SGI's Hardware Graph compatibility layer
718 hd= [EIDE] (E)IDE hard drive subsystem geometry
719 Format: <cyl>,<head>,<sect>
721 hd?= [HW] (E)IDE subsystem
722 <<<<<<< HEAD:Documentation/kernel-parameters.txt
723 hd?lun= See Documentation/ide.txt.
724 =======
725 hd?lun= See Documentation/ide/ide.txt.
726 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
728 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
729 size of <nn>. This works even on boxes that have no
730 highmem otherwise. This also works to reduce highmem
731 size on bigger boxes.
733 highres= [KNL] Enable/disable high resolution timer mode.
734 Valid parameters: "on", "off"
735 Default: "on"
737 hisax= [HW,ISDN]
738 See Documentation/isdn/README.HiSax.
740 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
741 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
743 i8042.direct [HW] Put keyboard port into non-translated mode
744 i8042.dumbkbd [HW] Pretend that controller can only read data from
745 keyboard and cannot control its state
746 (Don't attempt to blink the leds)
747 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
748 i8042.nokbd [HW] Don't check/create keyboard port
749 <<<<<<< HEAD:Documentation/kernel-parameters.txt
750 =======
751 i8042.noloop [HW] Disable the AUX Loopback command while probing
752 for the AUX port
753 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
754 i8042.nomux [HW] Don't check presence of an active multiplexing
755 controller
756 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
757 controllers
758 i8042.panicblink=
759 [HW] Frequency with which keyboard LEDs should blink
760 when kernel panics (default is 0.5 sec)
761 i8042.reset [HW] Reset the controller during init and cleanup
762 i8042.unlock [HW] Unlock (ignore) the keylock
764 i810= [HW,DRM]
766 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
767 indicates that the driver is running on unsupported
768 hardware.
769 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
770 does not match list of supported models.
771 i8k.power_status
772 [HW] Report power status in /proc/i8k
773 (disabled by default)
774 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
775 capability is set.
777 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
778 See Documentation/mca.txt.
780 icn= [HW,ISDN]
781 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
783 ide= [HW] (E)IDE subsystem
784 Format: ide=nodma or ide=doubler or ide=reverse
785 <<<<<<< HEAD:Documentation/kernel-parameters.txt
786 See Documentation/ide.txt.
787 =======
788 See Documentation/ide/ide.txt.
789 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
791 ide?= [HW] (E)IDE subsystem
792 Format: ide?=noprobe or chipset specific parameters.
793 <<<<<<< HEAD:Documentation/kernel-parameters.txt
794 See Documentation/ide.txt.
795 =======
796 See Documentation/ide/ide.txt.
797 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
799 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
800 <<<<<<< HEAD:Documentation/kernel-parameters.txt
801 See Documentation/ide.txt.
802 =======
803 See Documentation/ide/ide.txt.
804 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
806 idle= [X86]
807 Format: idle=poll or idle=mwait
808 Poll forces a polling idle loop that can slightly improves the performance
809 of waking up a idle CPU, but will use a lot of power and make the system
810 run hot. Not recommended.
811 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
812 to not use it because it doesn't save as much power as a normal idle
813 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
814 as idle=poll.
816 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
817 Claim all unknown PCI IDE storage controllers.
819 ignore_loglevel [KNL]
820 Ignore loglevel setting - this will print /all/
821 kernel messages to the console. Useful for debugging.
823 ihash_entries= [KNL]
824 Set number of hash buckets for inode cache.
826 in2000= [HW,SCSI]
827 See header of drivers/scsi/in2000.c.
829 init= [KNL]
830 Format: <full_path>
831 Run specified binary instead of /sbin/init as init
832 process.
834 initcall_debug [KNL] Trace initcalls as they are executed. Useful
835 for working out where the kernel is dying during
836 startup.
838 initrd= [BOOT] Specify the location of the initial ramdisk
840 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
841 Format: <irq>
843 inttest= [IA64]
845 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
846 off
847 Disable intel iommu driver.
848 igfx_off [Default Off]
849 By default, gfx is mapped as normal device. If a gfx
850 device has a dedicated DMAR unit, the DMAR unit is
851 bypassed by not enabling DMAR with this option. In
852 this case, gfx device will use physical address for
853 DMA.
854 forcedac [x86_64]
855 With this option iommu will not optimize to look
856 for io virtual address below 32 bit forcing dual
857 address cycle on pci bus for cards supporting greater
858 than 32 bit addressing. The default is to look
859 for translation below 32 bit and if not available
860 then look in the higher range.
862 io_delay= [X86-32,X86-64] I/O delay method
863 0x80
864 Standard port 0x80 based delay
865 0xed
866 Alternate port 0xed based delay (needed on some systems)
867 udelay
868 Simple two microseconds delay
869 none
870 No delay
872 io7= [HW] IO7 for Marvel based alpha systems
873 See comment before marvel_specify_io7 in
874 arch/alpha/kernel/core_marvel.c.
876 ip= [IP_PNP]
877 See Documentation/nfsroot.txt.
879 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
880 See comment before ip2_setup() in
881 drivers/char/ip2/ip2base.c.
883 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
884 See header of drivers/scsi/ips.c.
886 ports= [IP_VS_FTP] IPVS ftp helper module
887 Default is 21.
888 Up to 8 (IP_VS_APP_MAX_PORTS) ports
889 may be specified.
890 Format: <port>,<port>....
892 irqfixup [HW]
893 When an interrupt is not handled search all handlers
894 for it. Intended to get systems with badly broken
895 firmware running.
897 irqpoll [HW]
898 When an interrupt is not handled search all handlers
899 for it. Also check all handlers each timer
900 interrupt. Intended to get systems with badly broken
901 firmware running.
903 isapnp= [ISAPNP]
904 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
906 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
907 Format:
908 <cpu number>,...,<cpu number>
909 or
910 <cpu number>-<cpu number> (must be a positive range in ascending order)
911 or a mixture
912 <cpu number>,...,<cpu number>-<cpu number>
913 This option can be used to specify one or more CPUs
914 to isolate from the general SMP balancing and scheduling
915 algorithms. The only way to move a process onto or off
916 an "isolated" CPU is via the CPU affinity syscalls.
917 <cpu number> begins at 0 and the maximum value is
918 "number of CPUs in system - 1".
920 This option is the preferred way to isolate CPUs. The
921 alternative -- manually setting the CPU mask of all
922 tasks in the system -- can cause problems and
923 suboptimal load balancer performance.
925 iucv= [HW,NET]
927 js= [HW,JOY] Analog joystick
928 See Documentation/input/joystick.txt.
930 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
931 specifies the amount of memory usable by the kernel
932 for non-movable allocations. The requested amount is
933 spread evenly throughout all nodes in the system. The
934 remaining memory in each node is used for Movable
935 pages. In the event, a node is too small to have both
936 kernelcore and Movable pages, kernelcore pages will
937 take priority and other nodes will have a larger number
938 of kernelcore pages. The Movable zone is used for the
939 allocation of pages that may be reclaimed or moved
940 by the page migration subsystem. This means that
941 HugeTLB pages may not be allocated from this zone.
942 Note that allocations like PTEs-from-HighMem still
943 use the HighMem zone if it exists, and the Normal
944 zone if it does not.
946 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
947 is similar to kernelcore except it specifies the
948 amount of memory used for migratable allocations.
949 If both kernelcore and movablecore is specified,
950 then kernelcore will be at *least* the specified
951 value but may be more. If movablecore on its own
952 is specified, the administrator must be careful
953 that the amount of memory usable for all allocations
954 is not too small.
956 keepinitrd [HW,ARM]
958 kstack=N [X86-32,X86-64] Print N words from the kernel stack
959 in oops dumps.
961 l2cr= [PPC]
963 lapic [X86-32,APIC] Enable the local APIC even if BIOS
964 disabled it.
966 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
967 C2 power state.
969 libata.dma= [LIBATA] DMA control
970 libata.dma=0 Disable all PATA and SATA DMA
971 libata.dma=1 PATA and SATA Disk DMA only
972 libata.dma=2 ATAPI (CDROM) DMA only
973 libata.dma=4 Compact Flash DMA only
974 Combinations also work, so libata.dma=3 enables DMA
975 for disks and CDROMs, but not CFs.
977 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
978 when set.
979 Format: <int>
981 <<<<<<< HEAD:Documentation/kernel-parameters.txt
982 =======
983 libata.force= [LIBATA] Force configurations. The format is comma
984 separated list of "[ID:]VAL" where ID is
985 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
986 matching port, link or device. Basically, it matches
987 the ATA ID string printed on console by libata. If
988 the whole ID part is omitted, the last PORT and DEVICE
989 values are used. If ID hasn't been specified yet, the
990 configuration applies to all ports, links and devices.
992 If only DEVICE is omitted, the parameter applies to
993 the port and all links and devices behind it. DEVICE
994 number of 0 either selects the first device or the
995 first fan-out link behind PMP device. It does not
996 select the host link. DEVICE number of 15 selects the
997 host link and device attached to it.
999 The VAL specifies the configuration to force. As long
1000 as there's no ambiguity shortcut notation is allowed.
1001 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1002 The following configurations can be forced.
1004 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1005 Any ID with matching PORT is used.
1007 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1009 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1010 udma[/][16,25,33,44,66,100,133] notation is also
1011 allowed.
1013 * [no]ncq: Turn on or off NCQ.
1015 If there are multiple matching configurations changing
1016 the same attribute, the last one is used.
1018 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
1019 load_ramdisk= [RAM] List of ramdisks to load from floppy
1020 See Documentation/ramdisk.txt.
1022 lockd.nlm_grace_period=P [NFS] Assign grace period.
1023 Format: <integer>
1025 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1026 Format: <integer>
1028 lockd.nlm_timeout=T [NFS] Assign timeout value.
1029 Format: <integer>
1031 lockd.nlm_udpport=M [NFS] Assign UDP port.
1032 Format: <integer>
1034 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1035 Format: <irq>
1037 loglevel= All Kernel Messages with a loglevel smaller than the
1038 console loglevel will be printed to the console. It can
1039 also be changed with klogd or other programs. The
1040 loglevels are defined as follows:
1042 0 (KERN_EMERG) system is unusable
1043 1 (KERN_ALERT) action must be taken immediately
1044 2 (KERN_CRIT) critical conditions
1045 3 (KERN_ERR) error conditions
1046 4 (KERN_WARNING) warning conditions
1047 5 (KERN_NOTICE) normal but significant condition
1048 6 (KERN_INFO) informational
1049 7 (KERN_DEBUG) debug-level messages
1051 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1052 Format: { n | nk | nM }
1053 n must be a power of two. The default size
1054 is set in the kernel config file.
1056 logo.nologo [FB] Disables display of the built-in Linux logo.
1057 This may be used to provide more screen space for
1058 kernel log messages and is useful when debugging
1059 kernel boot problems.
1061 lp=0 [LP] Specify parallel ports to use, e.g,
1062 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1063 lp=reset first parallel port). 'lp=0' disables the
1064 lp=auto printer driver. 'lp=reset' (which can be
1065 specified in addition to the ports) causes
1066 attached printers to be reset. Using
1067 lp=port1,port2,... specifies the parallel ports
1068 to associate lp devices with, starting with
1069 lp0. A port specification may be 'none' to skip
1070 that lp device, or a parport name such as
1071 'parport0'. Specifying 'lp=auto' instead of a
1072 port specification list means that device IDs
1073 from each port should be examined, to see if
1074 an IEEE 1284-compliant printer is attached; if
1075 so, the driver will manage that printer.
1076 See also header of drivers/char/lp.c.
1078 lpj=n [KNL]
1079 Sets loops_per_jiffy to given constant, thus avoiding
1080 time-consuming boot-time autodetection (up to 250 ms per
1081 CPU). 0 enables autodetection (default). To determine
1082 the correct value for your kernel, boot with normal
1083 autodetection and see what value is printed. Note that
1084 on SMP systems the preset will be applied to all CPUs,
1085 which is likely to cause problems if your CPUs need
1086 significantly divergent settings. An incorrect value
1087 will cause delays in the kernel to be wrong, leading to
1088 unpredictable I/O errors and other breakage. Although
1089 unlikely, in the extreme case this might damage your
1090 hardware.
1092 ltpc= [NET]
1093 Format: <io>,<irq>,<dma>
1095 mac5380= [HW,SCSI] Format:
1096 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1098 mac53c9x= [HW,SCSI] Format:
1099 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1101 machvec= [IA64] Force the use of a particular machine-vector
1102 (machvec) in a generic kernel.
1103 Example: machvec=hpzx1_swiotlb
1105 max_loop= [LOOP] Maximum number of loopback devices that can
1106 be mounted
1107 Format: <1-256>
1109 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1110 should make use of. maxcpus=n : n >= 0 limits the
1111 kernel to using 'n' processors. n=0 is a special case,
1112 it is equivalent to "nosmp", which also disables
1113 the IO APIC.
1115 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1116 equal to this physical address is ignored.
1118 max_luns= [SCSI] Maximum number of LUNs to probe.
1119 Should be between 1 and 2^32-1.
1121 max_report_luns=
1122 [SCSI] Maximum number of LUNs received.
1123 Should be between 1 and 16384.
1125 <<<<<<< HEAD:Documentation/kernel-parameters.txt
1126 mca-pentium [BUGS=X86-32]
1128 =======
1129 >>>>>>> 264e3e889d86e552b4191d69bb60f4f3b383135a:Documentation/kernel-parameters.txt
1130 mcatest= [IA-64]
1132 mce [X86-32] Machine Check Exception
1134 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1136 md= [HW] RAID subsystems devices and level
1137 See Documentation/md.txt.
1139 mdacon= [MDA]
1140 Format: <first>,<last>
1141 Specifies range of consoles to be captured by the MDA.
1143 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1144 Amount of memory to be used when the kernel is not able
1145 to see the whole system memory or for test.
1146 [X86-32] Use together with memmap= to avoid physical
1147 address space collisions. Without memmap= PCI devices
1148 could be placed at addresses belonging to unused RAM.
1150 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1151 memory.
1153 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1154 E820 memory map, as specified by the user.
1155 Such memmap=exactmap lines can be constructed based on
1156 BIOS output or other requirements. See the memmap=nn@ss
1157 option description.
1159 memmap=nn[KMG]@ss[KMG]
1160 [KNL] Force usage of a specific region of memory
1161 Region of memory to be used, from ss to ss+nn.
1163 memmap=nn[KMG]#ss[KMG]
1164 [KNL,ACPI] Mark specific memory as ACPI data.
1165 Region of memory to be used, from ss to ss+nn.
1167 memmap=nn[KMG]$ss[KMG]
1168 [KNL,ACPI] Mark specific memory as reserved.
1169 Region of memory to be used, from ss to ss+nn.
1171 meye.*= [HW] Set MotionEye Camera parameters
1172 See Documentation/video4linux/meye.txt.
1174 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1175 Multi-Function General Purpose Timers on AMD Geode
1176 platforms.
1178 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1179 the BIOS has incorrectly applied a workaround. TinyBIOS
1180 version 0.98 is known to be affected, 0.99 fixes the
1181 problem by letting the user disable the workaround.
1183 mga= [HW,DRM]
1185 mousedev.tap_time=
1186 [MOUSE] Maximum time between finger touching and
1187 leaving touchpad surface for touch to be considered
1188 a tap and be reported as a left button click (for
1189 touchpads working in absolute mode only).
1190 Format: <msecs>
1191 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1192 reporting absolute coordinates, such as tablets
1193 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1194 reporting absolute coordinates, such as tablets
1196 mpu401= [HW,OSS]
1197 Format: <io>,<irq>
1199 MTD_Partition= [MTD]
1200 Format: <name>,<region-number>,<size>,<offset>
1202 MTD_Region= [MTD] Format:
1203 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1205 mtdparts= [MTD]
1206 See drivers/mtd/cmdlinepart.c.
1208 mtouchusb.raw_coordinates=
1209 [HW] Make the MicroTouch USB driver use raw coordinates
1210 ('y', default) or cooked coordinates ('n')
1212 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1214 NCR_D700= [HW,SCSI]
1215 See header of drivers/scsi/NCR_D700.c.
1217 ncr5380= [HW,SCSI]
1219 ncr53c400= [HW,SCSI]
1221 ncr53c400a= [HW,SCSI]
1223 ncr53c406a= [HW,SCSI]
1225 ncr53c8xx= [HW,SCSI]
1227 netdev= [NET] Network devices parameters
1228 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1229 Note that mem_start is often overloaded to mean
1230 something different and driver-specific.
1231 This usage is only documented in each driver source
1232 file if at all.
1234 nfsaddrs= [NFS]
1235 See Documentation/nfsroot.txt.
1237 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1238 See Documentation/nfsroot.txt.
1240 nfs.callback_tcpport=
1241 [NFS] set the TCP port on which the NFSv4 callback
1242 channel should listen.
1244 nfs.idmap_cache_timeout=
1245 [NFS] set the maximum lifetime for idmapper cache
1246 entries.
1248 nfs.enable_ino64=
1249 [NFS] enable 64-bit inode numbers.
1250 If zero, the NFS client will fake up a 32-bit inode
1251 number for the readdir() and stat() syscalls instead
1252 of returning the full 64-bit number.
1253 The default is to return 64-bit inode numbers.
1255 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1256 when a NMI is triggered.
1257 Format: [state][,regs][,debounce][,die]
1259 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1261 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1262 emulation library even if a 387 maths coprocessor
1263 is present.
1265 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1266 caches in the slab allocator. Saves per-node memory,
1267 but will impact performance.
1269 noalign [KNL,ARM]
1271 noapic [SMP,APIC] Tells the kernel to not make use of any
1272 IOAPICs that may be present in the system.
1274 nobats [PPC] Do not use BATs for mapping kernel lowmem
1275 on "Classic" PPC cores.
1277 nocache [ARM]
1279 nodelayacct [KNL] Disable per-task delay accounting
1281 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1283 noefi [X86-32,X86-64] Disable EFI runtime services support.
1285 noexec [IA-64]
1287 noexec [X86-32,X86-64]
1288 noexec=on: enable non-executable mappings (default)
1289 noexec=off: disable nn-executable mappings
1291 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1292 register save and restore. The kernel will only save
1293 legacy floating-point registers on task switch.
1295 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1297 nohlt [BUGS=ARM]
1299 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1300 instruction doesn't work correctly and not to
1301 use it.
1303 nohalt [IA-64] Tells the kernel not to use the power saving
1304 function PAL_HALT_LIGHT when idle. This increases
1305 power-consumption. On the positive side, it reduces
1306 interrupt wake-up latency, which may improve performance
1307 in certain environments such as networked servers or
1308 real-time systems.
1310 nohz= [KNL] Boottime enable/disable dynamic ticks
1311 Valid arguments: on, off
1312 Default: on
1314 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1316 noirqdebug [X86-32] Disables the code which attempts to detect and
1317 disable unhandled interrupt sources.
1319 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1320 broken timer IRQ sources.
1322 noisapnp [ISAPNP] Disables ISA PnP code.
1324 noinitrd [RAM] Tells the kernel not to load any configured
1325 initial RAM disk.
1327 nointroute [IA-64]
1329 nojitter [IA64] Disables jitter checking for ITC timers.
1331 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1333 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1335 noltlbs [PPC] Do not use large page/tlb entries for kernel
1336 lowmem mapping on PPC40x.
1338 nomca [IA-64] Disable machine check abort handling
1340 nomce [X86-32] Machine Check Exception
1342 nomfgpt [X86-32] Disable Multi-Function General Purpose
1343 Timer usage (for AMD Geode machines).
1345 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1347 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1348 with UP alternatives
1350 noresidual [PPC] Don't use residual data on PReP machines.
1352 noresume [SWSUSP] Disables resume and restores original swap
1353 space.
1355 no-scroll [VGA] Disables scrollback.
1356 This is required for the Braillex ib80-piezo Braille
1357 reader made by F.H. Papenmeier (Germany).
1359 nosbagart [IA-64]
1361 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1363 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1364 and disable the IO APIC. legacy for "maxcpus=0".
1366 nosoftlockup [KNL] Disable the soft-lockup detector.
1368 nosync [HW,M68K] Disables sync negotiation for all devices.
1370 notsc [BUGS=X86-32] Disable Time Stamp Counter
1372 nousb [USB] Disable the USB subsystem
1374 nowb [ARM]
1376 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1377 one of ['zone', 'node', 'default'] can be specified
1378 This can be set from sysctl after boot.
1379 See Documentation/sysctl/vm.txt for details.
1381 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1383 opl3= [HW,OSS]
1384 Format: <io>
1386 oprofile.timer= [HW]
1387 Use timer interrupt instead of performance counters
1389 osst= [HW,SCSI] SCSI Tape Driver
1390 Format: <buffer_size>,<write_threshold>
1391 See also Documentation/scsi/st.txt.
1393 panic= [KNL] Kernel behaviour on panic
1394 Format: <timeout>
1396 parkbd.port= [HW] Parallel port number the keyboard adapter is
1397 connected to, default is 0.
1398 Format: <parport#>
1399 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1400 0 for XT, 1 for AT (default is AT).
1401 Format: <mode>
1403 parport= [HW,PPT] Specify parallel ports. 0 disables.
1404 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1405 Use 'auto' to force the driver to use any
1406 IRQ/DMA settings detected (the default is to
1407 ignore detected IRQ/DMA settings because of
1408 possible conflicts). You can specify the base
1409 address, IRQ, and DMA settings; IRQ and DMA
1410 should be numbers, or 'auto' (for using detected
1411 settings on that particular port), or 'nofifo'
1412 (to avoid using a FIFO even if it is detected).
1413 Parallel ports are assigned in the order they
1414 are specified on the command line, starting
1415 with parport0.
1417 parport_init_mode= [HW,PPT]
1418 Configure VIA parallel port to operate in
1419 a specific mode. This is necessary on Pegasos
1420 computer where firmware has no options for setting
1421 up parallel port mode and sets it to spp.
1422 Currently this function knows 686a and 8231 chips.
1423 Format: [spp|ps2|epp|ecp|ecpepp]
1425 pas2= [HW,OSS] Format:
1426 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1428 pas16= [HW,SCSI]
1429 See header of drivers/scsi/pas16.c.
1431 pause_on_oops=
1432 Halt all CPUs after the first oops has been printed for
1433 the specified number of seconds. This is to be used if
1434 your oopses keep scrolling off the screen.
1436 pcbit= [HW,ISDN]
1438 pcd. [PARIDE]
1439 See header of drivers/block/paride/pcd.c.
1440 See also Documentation/paride.txt.
1442 pci=option[,option...] [PCI] various PCI subsystem options:
1443 off [X86-32] don't probe for the PCI bus
1444 bios [X86-32] force use of PCI BIOS, don't access
1445 the hardware directly. Use this if your machine
1446 has a non-standard PCI host bridge.
1447 nobios [X86-32] disallow use of PCI BIOS, only direct
1448 hardware access methods are allowed. Use this
1449 if you experience crashes upon bootup and you
1450 suspect they are caused by the BIOS.
1451 conf1 [X86-32] Force use of PCI Configuration
1452 Mechanism 1.
1453 conf2 [X86-32] Force use of PCI Configuration
1454 Mechanism 2.
1455 noaer [PCIE] If the PCIEAER kernel config parameter is
1456 enabled, this kernel boot option can be used to
1457 disable the use of PCIE advanced error reporting.
1458 nodomains [PCI] Disable support for multiple PCI
1459 root domains (aka PCI segments, in ACPI-speak).
1460 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1461 Configuration
1462 nomsi [MSI] If the PCI_MSI kernel config parameter is
1463 enabled, this kernel boot option can be used to
1464 disable the use of MSI interrupts system-wide.
1465 nosort [X86-32] Don't sort PCI devices according to
1466 order given by the PCI BIOS. This sorting is
1467 done to get a device order compatible with
1468 older kernels.
1469 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1470 routing table. These calls are known to be buggy
1471 on several machines and they hang the machine
1472 when used, but on other computers it's the only
1473 way to get the interrupt routing table. Try
1474 this option if the kernel is unable to allocate
1475 IRQs or discover secondary PCI buses on your
1476 motherboard.
1477 rom [X86-32] Assign address space to expansion ROMs.
1478 Use with caution as certain devices share
1479 address decoders between ROMs and other
1480 resources.
1481 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1482 assigned automatically to PCI devices. You can
1483 make the kernel exclude IRQs of your ISA cards
1484 this way.
1485 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1486 of the PIRQ table (normally generated
1487 by the BIOS) if it is outside the
1488 F0000h-100000h range.
1489 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1490 useful if the kernel is unable to find your
1491 secondary buses and you want to tell it
1492 explicitly which ones they are.
1493 assign-busses [X86-32] Always assign all PCI bus
1494 numbers ourselves, overriding
1495 whatever the firmware may have done.
1496 usepirqmask [X86-32] Honor the possible IRQ mask stored
1497 in the BIOS $PIR table. This is needed on
1498 some systems with broken BIOSes, notably
1499 some HP Pavilion N5400 and Omnibook XE3
1500 notebooks. This will have no effect if ACPI
1501 IRQ routing is enabled.
1502 noacpi [X86-32] Do not use ACPI for IRQ routing
1503 or for PCI scanning.
1504 use_crs [X86-32] Use _CRS for PCI resource
1505 allocation.
1506 routeirq Do IRQ routing for all PCI devices.
1507 This is normally done in pci_enable_device(),
1508 so this option is a temporary workaround
1509 for broken drivers that don't call it.
1510 firmware [ARM] Do not re-enumerate the bus but instead
1511 just use the configuration from the
1512 bootloader. This is currently used on
1513 IXP2000 systems where the bus has to be
1514 configured a certain way for adjunct CPUs.
1515 noearly [X86] Don't do any early type 1 scanning.
1516 This might help on some broken boards which
1517 machine check when some devices' config space
1518 is read. But various workarounds are disabled
1519 and some IOMMU drivers will not work.
1520 bfsort Sort PCI devices into breadth-first order.
1521 This sorting is done to get a device
1522 order compatible with older (<= 2.4) kernels.
1523 nobfsort Don't sort PCI devices into breadth-first order.
1524 cbiosize=nn[KMG] The fixed amount of bus space which is
1525 reserved for the CardBus bridge's IO window.
1526 The default value is 256 bytes.
1527 cbmemsize=nn[KMG] The fixed amount of bus space which is
1528 reserved for the CardBus bridge's memory
1529 window. The default value is 64 megabytes.
1531 pcmv= [HW,PCMCIA] BadgePAD 4
1533 pd. [PARIDE]
1534 See Documentation/paride.txt.
1536 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1537 boot time.
1538 Format: { 0 | 1 }
1539 See arch/parisc/kernel/pdc_chassis.c
1541 pf. [PARIDE]
1542 See Documentation/paride.txt.
1544 pg. [PARIDE]
1545 See Documentation/paride.txt.
1547 pirq= [SMP,APIC] Manual mp-table setup
1548 See Documentation/i386/IO-APIC.txt.
1550 plip= [PPT,NET] Parallel port network link
1551 Format: { parport<nr> | timid | 0 }
1552 See also Documentation/parport.txt.
1554 pnpacpi= [ACPI]
1555 { off }
1557 pnpbios= [ISAPNP]
1558 { on | off | curr | res | no-curr | no-res }
1560 pnp_reserve_irq=
1561 [ISAPNP] Exclude IRQs for the autoconfiguration
1563 pnp_reserve_dma=
1564 [ISAPNP] Exclude DMAs for the autoconfiguration
1566 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1567 Ranges are in pairs (I/O port base and size).
1569 pnp_reserve_mem=
1570 [ISAPNP] Exclude memory regions for the
1571 autoconfiguration.
1572 Ranges are in pairs (memory base and size).
1574 print-fatal-signals=
1575 [KNL] debug: print fatal signals
1576 print-fatal-signals=1: print segfault info to
1577 the kernel console.
1578 default: off.
1580 printk.time= Show timing data prefixed to each printk message line
1581 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1583 profile= [KNL] Enable kernel profiling via /proc/profile
1584 Format: [schedule,]<number>
1585 Param: "schedule" - profile schedule points.
1586 Param: <number> - step/bucket size as a power of 2 for
1587 statistical time based profiling.
1588 Param: "sleep" - profile D-state sleeping (millisecs).
1589 Requires CONFIG_SCHEDSTATS
1590 Param: "kvm" - profile VM exits.
1592 processor.max_cstate= [HW,ACPI]
1593 Limit processor to maximum C-state
1594 max_cstate=9 overrides any DMI blacklist limit.
1596 processor.nocst [HW,ACPI]
1597 Ignore the _CST method to determine C-states,
1598 instead using the legacy FADT method
1600 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1601 before loading.
1602 See Documentation/ramdisk.txt.
1604 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1605 probe for; one of (bare|imps|exps|lifebook|any).
1606 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1607 per second.
1608 psmouse.resetafter= [HW,MOUSE]
1609 Try to reset the device after so many bad packets
1610 (0 = never).
1611 psmouse.resolution=
1612 [HW,MOUSE] Set desired mouse resolution, in dpi.
1613 psmouse.smartscroll=
1614 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1615 0 = disabled, 1 = enabled (default).
1617 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1618 Format:
1619 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1621 pt. [PARIDE]
1622 See Documentation/paride.txt.
1624 pty.legacy_count=
1625 [KNL] Number of legacy pty's. Overwrites compiled-in
1626 default number.
1628 quiet [KNL] Disable most log messages
1630 r128= [HW,DRM]
1632 raid= [HW,RAID]
1633 See Documentation/md.txt.
1635 ramdisk_blocksize= [RAM]
1636 See Documentation/ramdisk.txt.
1638 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1639 See Documentation/ramdisk.txt.
1641 rcupdate.blimit= [KNL,BOOT]
1642 Set maximum number of finished RCU callbacks to process
1643 in one batch.
1645 rcupdate.qhimark= [KNL,BOOT]
1646 Set threshold of queued
1647 RCU callbacks over which batch limiting is disabled.
1649 rcupdate.qlowmark= [KNL,BOOT]
1650 Set threshold of queued RCU callbacks below which
1651 batch limiting is re-enabled.
1653 rdinit= [KNL]
1654 Format: <full_path>
1655 Run specified binary instead of /init from the ramdisk,
1656 used for early userspace startup. See initrd.
1658 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1659 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1660 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1662 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1664 reservetop= [X86-32]
1665 Format: nn[KMG]
1666 Reserves a hole at the top of the kernel virtual
1667 address space.
1669 reset_devices [KNL] Force drivers to reset the underlying device
1670 during initialization.
1672 resume= [SWSUSP]
1673 Specify the partition device for software suspend
1675 resume_offset= [SWSUSP]
1676 Specify the offset from the beginning of the partition
1677 given by "resume=" at which the swap header is located,
1678 in <PAGE_SIZE> units (needed only for swap files).
1679 See Documentation/power/swsusp-and-swap-files.txt
1681 retain_initrd [RAM] Keep initrd memory after extraction
1683 rhash_entries= [KNL,NET]
1684 Set number of hash buckets for route cache
1686 riscom8= [HW,SERIAL]
1687 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1689 ro [KNL] Mount root device read-only on boot
1691 root= [KNL] Root filesystem
1693 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1694 mount the root filesystem
1696 rootflags= [KNL] Set root filesystem mount option string
1698 rootfstype= [KNL] Set root filesystem type
1700 rootwait [KNL] Wait (indefinitely) for root device to show up.
1701 Useful for devices that are detected asynchronously
1702 (e.g. USB and MMC devices).
1704 root_plug.vendor_id=
1705 [ROOTPLUG] Override the default vendor ID
1707 root_plug.product_id=
1708 [ROOTPLUG] Override the default product ID
1710 root_plug.debug=
1711 [ROOTPLUG] Enable debugging output
1713 rw [KNL] Mount root device read-write on boot
1715 S [KNL] Run init in single mode
1717 sa1100ir [NET]
1718 See drivers/net/irda/sa1100_ir.c.
1720 sbni= [NET] Granch SBNI12 leased line adapter
1722 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1723 Format: <io>[,<timeout>[,<isapnp>]]
1725 scsi_debug_*= [SCSI]
1726 See drivers/scsi/scsi_debug.c.
1728 scsi_default_dev_flags=
1729 [SCSI] SCSI default device flags
1730 Format: <integer>
1732 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1733 Format: <vendor>:<model>:<flags>
1734 (flags are integer value)
1736 scsi_logging_level= [SCSI] a bit mask of logging levels
1737 See drivers/scsi/scsi_logging.h for bits. Also
1738 settable via sysctl at dev.scsi.logging_level
1739 (/proc/sys/dev/scsi/logging_level).
1740 There is also a nice 'scsi_logging_level' script in the
1741 S390-tools package, available for download at
1742 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1744 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1745 discovered. async scans them in kernel threads,
1746 allowing boot to proceed. none ignores them, expecting
1747 user space to do the scan.
1749 selinux [SELINUX] Disable or enable SELinux at boot time.
1750 Format: { "0" | "1" }
1751 See security/selinux/Kconfig help text.
1752 0 -- disable.
1753 1 -- enable.
1754 Default value is set via kernel config option.
1755 If enabled at boot time, /selinux/disable can be used
1756 later to disable prior to initial policy load.
1758 selinux_compat_net =
1759 [SELINUX] Set initial selinux_compat_net flag value.
1760 Format: { "0" | "1" }
1761 0 -- use new secmark-based packet controls
1762 1 -- use legacy packet controls
1763 Default value is 0 (preferred).
1764 Value can be changed at runtime via
1765 /selinux/compat_net.
1767 serialnumber [BUGS=X86-32]
1769 shapers= [NET]
1770 Maximal number of shapers.
1772 sim710= [SCSI,HW]
1773 See header of drivers/scsi/sim710.c.
1775 simeth= [IA-64]
1776 simscsi=
1778 slram= [HW,MTD]
1780 slub_debug[=options[,slabs]] [MM, SLUB]
1781 Enabling slub_debug allows one to determine the
1782 culprit if slab objects become corrupted. Enabling
1783 slub_debug can create guard zones around objects and
1784 may poison objects when not in use. Also tracks the
1785 last alloc / free. For more information see
1786 Documentation/vm/slub.txt.
1788 slub_max_order= [MM, SLUB]
1789 Determines the maximum allowed order for slabs.
1790 A high setting may cause OOMs due to memory
1791 fragmentation. For more information see
1792 Documentation/vm/slub.txt.
1794 slub_min_objects= [MM, SLUB]
1795 The minimum number of objects per slab. SLUB will
1796 increase the slab order up to slub_max_order to
1797 generate a sufficiently large slab able to contain
1798 the number of objects indicated. The higher the number
1799 of objects the smaller the overhead of tracking slabs
1800 and the less frequently locks need to be acquired.
1801 For more information see Documentation/vm/slub.txt.
1803 slub_min_order= [MM, SLUB]
1804 Determines the mininum page order for slabs. Must be
1805 lower than slub_max_order.
1806 For more information see Documentation/vm/slub.txt.
1808 slub_nomerge [MM, SLUB]
1809 Disable merging of slabs with similar size. May be
1810 necessary if there is some reason to distinguish
1811 allocs to different slabs. Debug options disable
1812 merging on their own.
1813 For more information see Documentation/vm/slub.txt.
1815 smart2= [HW]
1816 Format: <io1>[,<io2>[,...,<io8>]]
1818 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1819 attempt to substitute SMP alternatives once at boot.
1821 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1822 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1823 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1824 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1825 smsc-ircc2.ircc_irq= [HW] IRQ line
1826 smsc-ircc2.ircc_dma= [HW] DMA channel
1827 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1828 0: Toshiba Satellite 1800 (GP data pin select)
1829 1: Fast pin select (default)
1830 2: ATC IRMode
1832 snd-ad1816a= [HW,ALSA]
1834 snd-ad1848= [HW,ALSA]
1836 snd-ali5451= [HW,ALSA]
1838 snd-als100= [HW,ALSA]
1840 snd-als4000= [HW,ALSA]
1842 snd-azt2320= [HW,ALSA]
1844 snd-cmi8330= [HW,ALSA]
1846 snd-cmipci= [HW,ALSA]
1848 snd-cs4231= [HW,ALSA]
1850 snd-cs4232= [HW,ALSA]
1852 snd-cs4236= [HW,ALSA]
1854 snd-cs4281= [HW,ALSA]
1856 snd-cs46xx= [HW,ALSA]
1858 snd-dt019x= [HW,ALSA]
1860 snd-dummy= [HW,ALSA]
1862 snd-emu10k1= [HW,ALSA]
1864 snd-ens1370= [HW,ALSA]
1866 snd-ens1371= [HW,ALSA]
1868 snd-es968= [HW,ALSA]
1870 snd-es1688= [HW,ALSA]
1872 snd-es18xx= [HW,ALSA]
1874 snd-es1938= [HW,ALSA]
1876 snd-es1968= [HW,ALSA]
1878 snd-fm801= [HW,ALSA]
1880 snd-gusclassic= [HW,ALSA]
1882 snd-gusextreme= [HW,ALSA]
1884 snd-gusmax= [HW,ALSA]
1886 snd-hdsp= [HW,ALSA]
1888 snd-ice1712= [HW,ALSA]
1890 snd-intel8x0= [HW,ALSA]
1892 snd-interwave= [HW,ALSA]
1894 snd-interwave-stb=
1895 [HW,ALSA]
1897 snd-korg1212= [HW,ALSA]
1899 snd-maestro3= [HW,ALSA]
1901 snd-mpu401= [HW,ALSA]
1903 snd-mtpav= [HW,ALSA]
1905 snd-nm256= [HW,ALSA]
1907 snd-opl3sa2= [HW,ALSA]
1909 snd-opti92x-ad1848=
1910 [HW,ALSA]
1912 snd-opti92x-cs4231=
1913 [HW,ALSA]
1915 snd-opti93x= [HW,ALSA]
1917 snd-pmac= [HW,ALSA]
1919 snd-rme32= [HW,ALSA]
1921 snd-rme96= [HW,ALSA]
1923 snd-rme9652= [HW,ALSA]
1925 snd-sb8= [HW,ALSA]
1927 snd-sb16= [HW,ALSA]
1929 snd-sbawe= [HW,ALSA]
1931 snd-serial= [HW,ALSA]
1933 snd-sgalaxy= [HW,ALSA]
1935 snd-sonicvibes= [HW,ALSA]
1937 snd-sun-amd7930=
1938 [HW,ALSA]
1940 snd-sun-cs4231= [HW,ALSA]
1942 snd-trident= [HW,ALSA]
1944 snd-usb-audio= [HW,ALSA,USB]
1946 snd-via82xx= [HW,ALSA]
1948 snd-virmidi= [HW,ALSA]
1950 snd-wavefront= [HW,ALSA]
1952 snd-ymfpci= [HW,ALSA]
1954 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1955 See Documentation/sonypi.txt
1957 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1958 See Documentation/specialix.txt.
1960 spia_io_base= [HW,MTD]
1961 spia_fio_base=
1962 spia_pedr=
1963 spia_peddr=
1965 sscape= [HW,OSS]
1966 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1968 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1969 See Documentation/scsi/st.txt.
1971 sti= [PARISC,HW]
1972 Format: <num>
1973 Set the STI (builtin display/keyboard on the HP-PARISC
1974 machines) console (graphic card) which should be used
1975 as the initial boot-console.
1976 See also comment in drivers/video/console/sticore.c.
1978 sti_font= [HW]
1979 See comment in drivers/video/console/sticore.c.
1981 stifb= [HW]
1982 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1984 sunrpc.pool_mode=
1985 [NFS]
1986 Control how the NFS server code allocates CPUs to
1987 service thread pools. Depending on how many NICs
1988 you have and where their interrupts are bound, this
1989 option will affect which CPUs will do NFS serving.
1990 Note: this parameter cannot be changed while the
1991 NFS server is running.
1993 auto the server chooses an appropriate mode
1994 automatically using heuristics
1995 global a single global pool contains all CPUs
1996 percpu one pool for each CPU
1997 pernode one pool for each NUMA node (equivalent
1998 to global on non-NUMA machines)
2000 swiotlb= [IA-64] Number of I/O TLB slabs
2002 switches= [HW,M68k]
2004 sym53c416= [HW,SCSI]
2005 See header of drivers/scsi/sym53c416.c.
2007 sysrq_always_enabled
2008 [KNL]
2009 Ignore sysrq setting - this boot parameter will
2010 neutralize any effect of /proc/sys/kernel/sysrq.
2011 Useful for debugging.
2013 t128= [HW,SCSI]
2014 See header of drivers/scsi/t128.c.
2016 tdfx= [HW,DRM]
2018 thash_entries= [KNL,NET]
2019 Set number of hash buckets for TCP connection
2021 thermal.act= [HW,ACPI]
2022 -1: disable all active trip points in all thermal zones
2023 <degrees C>: override all lowest active trip points
2025 thermal.crt= [HW,ACPI]
2026 -1: disable all critical trip points in all thermal zones
2027 <degrees C>: lower all critical trip points
2029 thermal.nocrt= [HW,ACPI]
2030 Set to disable actions on ACPI thermal zone
2031 critical and hot trip points.
2033 thermal.off= [HW,ACPI]
2034 1: disable ACPI thermal control
2036 thermal.psv= [HW,ACPI]
2037 -1: disable all passive trip points
2038 <degrees C>: override all passive trip points to this value
2040 thermal.tzp= [HW,ACPI]
2041 Specify global default ACPI thermal zone polling rate
2042 <deci-seconds>: poll all this frequency
2043 0: no polling (default)
2045 tipar.timeout= [HW,PPT]
2046 Set communications timeout in tenths of a second
2047 (default 15).
2049 tipar.delay= [HW,PPT]
2050 Set inter-bit delay in microseconds (default 10).
2052 tmscsim= [HW,SCSI]
2053 See comment before function dc390_setup() in
2054 drivers/scsi/tmscsim.c.
2056 tp720= [HW,PS2]
2058 trix= [HW,OSS] MediaTrix AudioTrix Pro
2059 Format:
2060 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2062 turbografx.map[2|3]= [HW,JOY]
2063 TurboGraFX parallel port interface
2064 Format:
2065 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2066 See also Documentation/input/joystick-parport.txt
2068 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2069 See header of drivers/scsi/u14-34f.c.
2071 uart401= [HW,OSS]
2072 Format: <io>,<irq>
2074 uart6850= [HW,OSS]
2075 Format: <io>,<irq>
2077 uhci-hcd.ignore_oc=
2078 [USB] Ignore overcurrent events (default N).
2079 Some badly-designed motherboards generate lots of
2080 bogus events, for ports that aren't wired to
2081 anything. Set this parameter to avoid log spamming.
2082 Note that genuine overcurrent events won't be
2083 reported either.
2085 usbcore.autosuspend=
2086 [USB] The autosuspend time delay (in seconds) used
2087 for newly-detected USB devices (default 2). This
2088 is the time required before an idle device will be
2089 autosuspended. Devices for which the delay is set
2090 to a negative value won't be autosuspended at all.
2092 usbhid.mousepoll=
2093 [USBHID] The interval which mice are to be polled at.
2095 vdso= [X86-32,SH,x86-64]
2096 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2097 vdso=1: enable VDSO (default)
2098 vdso=0: disable VDSO mapping
2100 vdso32= [X86-32,X86-64]
2101 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2102 vdso32=1: enable 32-bit VDSO (default)
2103 vdso32=0: disable 32-bit VDSO mapping
2105 vector= [IA-64,SMP]
2106 vector=percpu: enable percpu vector domain
2108 video= [FB] Frame buffer configuration
2109 See Documentation/fb/modedb.txt.
2111 vga= [BOOT,X86-32] Select a particular video mode
2112 See Documentation/i386/boot.txt and
2113 Documentation/svga.txt.
2114 Use vga=ask for menu.
2115 This is actually a boot loader parameter; the value is
2116 passed to the kernel using a special protocol.
2118 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2119 size of <nn>. This can be used to increase the
2120 minimum size (128MB on x86). It can also be used to
2121 decrease the size and leave more room for directly
2122 mapped kernel RAM.
2124 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2125 Format: <command>
2127 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2128 Format: <command>
2130 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2131 Format: <command>
2133 waveartist= [HW,OSS]
2134 Format: <io>,<irq>,<dma>,<dma2>
2136 wd33c93= [HW,SCSI]
2137 See header of drivers/scsi/wd33c93.c.
2139 wd7000= [HW,SCSI]
2140 See header of drivers/scsi/wd7000.c.
2142 wdt= [WDT] Watchdog
2143 See Documentation/watchdog/wdt.txt.
2145 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2146 xd_geo= See header of drivers/block/xd.c.
2148 xirc2ps_cs= [NET,PCMCIA]
2149 Format:
2150 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2152 norandmaps Don't use address space randomization
2153 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2155 ______________________________________________________________________
2157 TODO:
2159 Add documentation for ALSA options.
2160 Add more DRM drivers.