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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 KMEMTRACE kmemtrace is enabled.
53 LIBATA Libata driver is enabled
54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
62 MSI Message Signaled Interrupts (PCI).
63 MTD MTD (Memory Technology Device) support is enabled.
64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
66 GENERIC_TIME The generic timeofday code is enabled.
67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
73 PCIE PCI Express support is enabled.
74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
80 ROOTPLUG The example Root Plug LSM is enabled.
81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
84 Documentation/scsi/.
85 SECURITY Different security models are enabled.
86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
88 SH SuperH architecture is enabled.
89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
91 SWSUSP Software suspend is enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
105 In addition, the following text indicates that the option:
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
111 Parameters denoted with BOOT are actually interpreted by the boot
112 loader, and have no meaning to the kernel directly.
113 Do not modify the syntax of boot loader parameters without extreme
114 need or coordination with <Documentation/i386/boot.txt>.
116 There are also arch-specific kernel-parameters not documented here.
117 See for example <Documentation/x86_64/boot-options.txt>.
119 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120 a trailing = on the name of any parameter states that that parameter will
121 be entered as an environment variable, whereas its absence indicates that
122 it will appear as a kernel argument readable via /proc/cmdline by programs
123 running once the system is up.
125 The number of kernel parameters is not limited, but the length of the
126 complete command line (parameters including spaces etc.) is limited to
127 a fixed number of characters. This limit depends on the architecture
128 and is between 256 and 4096 characters. It is defined in the file
129 ./include/asm/setup.h as COMMAND_LINE_SIZE.
132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
134 Format: { force | off | ht | strict | noirq }
135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
139 strict -- Be less tolerant of platforms that are not
140 strictly ACPI specification compliant.
142 See also Documentation/power/pm.txt, pci=noacpi
144 acpi_apic_instance= [ACPI, IOAPIC]
145 Format: <int>
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
148 default: 0
150 acpi_sleep= [HW,ACPI] Sleep options
151 Format: { s3_bios, s3_mode, s3_beep }
152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
156 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
157 Format: { level | edge | high | low }
159 acpi_irq_balance [HW,ACPI]
160 ACPI will balance active IRQs
161 default in APIC mode
163 acpi_irq_nobalance [HW,ACPI]
164 ACPI will not move active IRQs (default)
165 default in PIC mode
167 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
168 use by PCI
169 Format: <irq>,<irq>...
171 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
172 Format: <irq>,<irq>...
174 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
176 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
177 Format: To spoof as Windows 98: ="Microsoft Windows"
179 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
180 acpi_osi="string1" # add string1 -- only one string
181 acpi_osi="!string2" # remove built-in string2
182 acpi_osi= # disable all strings
184 acpi_serialize [HW,ACPI] force serialization of AML methods
186 acpi_skip_timer_override [HW,ACPI]
187 Recognize and ignore IRQ0/pin2 Interrupt Override.
188 For broken nForce2 BIOS resulting in XT-PIC timer.
189 acpi_use_timer_override [HW,ACPI}
190 Use timer override. For some broken Nvidia NF5 boards
191 that require a timer override, but don't have
192 HPET
194 acpi.debug_layer= [HW,ACPI]
195 Format: <int>
196 Each bit of the <int> indicates an ACPI debug layer,
197 1: enable, 0: disable. It is useful for boot time
198 debugging. After system has booted up, it can be set
199 via /sys/module/acpi/parameters/debug_layer.
200 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
201 Available bits (add the numbers together) to enable debug output
202 for specific parts of the ACPI subsystem:
203 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
204 0x10 namespace 0x20 parser 0x40 dispatcher
205 0x80 executer 0x100 resources 0x200 acpica debugger
206 0x400 os services 0x800 acpica disassembler.
207 The number can be in decimal or prefixed with 0x in hex.
208 Warning: Many of these options can produce a lot of
209 output and make your system unusable. Be very careful.
211 acpi.debug_level= [HW,ACPI]
212 Format: <int>
213 Each bit of the <int> indicates an ACPI debug level,
214 1: enable, 0: disable. It is useful for boot time
215 debugging. After system has booted up, it can be set
216 via /sys/module/acpi/parameters/debug_level.
217 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
218 Available bits (add the numbers together) to enable different
219 debug output levels of the ACPI subsystem:
220 0x01 error 0x02 warn 0x04 init 0x08 debug object
221 0x10 info 0x20 init names 0x40 parse 0x80 load
222 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
223 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
224 0x10000 resources 0x20000 user requests 0x40000 package.
225 The number can be in decimal or prefixed with 0x in hex.
226 Warning: Many of these options can produce a lot of
227 output and make your system unusable. Be very careful.
229 acpi_pm_good [X86-32,X86-64]
230 Override the pmtimer bug detection: force the kernel
231 to assume that this machine's pmtimer latches its value
232 and always returns good values.
234 agp= [AGP]
235 { off | try_unsupported }
236 off: disable AGP support
237 try_unsupported: try to drive unsupported chipsets
238 (may crash computer or cause data corruption)
240 enable_timer_pin_1 [i386,x86-64]
241 Enable PIN 1 of APIC timer
242 Can be useful to work around chipset bugs
243 (in particular on some ATI chipsets).
244 The kernel tries to set a reasonable default.
246 disable_timer_pin_1 [i386,x86-64]
247 Disable PIN 1 of APIC timer
248 Can be useful to work around chipset bugs.
250 ad1848= [HW,OSS]
251 Format: <io>,<irq>,<dma>,<dma2>,<type>
253 advansys= [HW,SCSI]
254 See header of drivers/scsi/advansys.c.
256 advwdt= [HW,WDT] Advantech WDT
257 Format: <iostart>,<iostop>
259 aedsp16= [HW,OSS] Audio Excel DSP 16
260 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
261 See also header of sound/oss/aedsp16.c.
263 aha152x= [HW,SCSI]
264 See Documentation/scsi/aha152x.txt.
266 aha1542= [HW,SCSI]
267 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
269 aic7xxx= [HW,SCSI]
270 See Documentation/scsi/aic7xxx.txt.
272 aic79xx= [HW,SCSI]
273 See Documentation/scsi/aic79xx.txt.
275 amijoy.map= [HW,JOY] Amiga joystick support
276 Map of devices attached to JOY0DAT and JOY1DAT
277 Format: <a>,<b>
278 See also Documentation/kernel/input/joystick.txt
280 analog.map= [HW,JOY] Analog joystick and gamepad support
281 Specifies type or capabilities of an analog joystick
282 connected to one of 16 gameports
283 Format: <type1>,<type2>,..<type16>
285 apc= [HW,SPARC]
286 Power management functions (SPARCstation-4/5 + deriv.)
287 Format: noidle
288 Disable APC CPU standby support. SPARCstation-Fox does
289 not play well with APC CPU idle - disable it if you have
290 APC and your system crashes randomly.
292 apic= [APIC,i386] Advanced Programmable Interrupt Controller
293 Change the output verbosity whilst booting
294 Format: { quiet (default) | verbose | debug }
295 Change the amount of debugging information output
296 when initialising the APIC and IO-APIC components.
298 apm= [APM] Advanced Power Management
299 See header of arch/x86/kernel/apm_32.c.
301 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
302 Format: <io>,<irq>,<nodeID>
304 ataflop= [HW,M68k]
306 atarimouse= [HW,MOUSE] Atari Mouse
308 atascsi= [HW,SCSI] Atari SCSI
310 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
311 EzKey and similar keyboards
313 atkbd.reset= [HW] Reset keyboard during initialization
315 atkbd.set= [HW] Select keyboard code set
316 Format: <int> (2 = AT (default), 3 = PS/2)
318 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
319 keyboards
321 atkbd.softraw= [HW] Choose between synthetic and real raw mode
322 Format: <bool> (0 = real, 1 = synthetic (default))
324 atkbd.softrepeat= [HW]
325 Use software keyboard repeat
327 autotest [IA64]
329 baycom_epp= [HW,AX25]
330 Format: <io>,<mode>
332 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
333 Format: <io>,<mode>
334 See header of drivers/net/hamradio/baycom_par.c.
336 baycom_ser_fdx= [HW,AX25]
337 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
338 Format: <io>,<irq>,<mode>[,<baud>]
339 See header of drivers/net/hamradio/baycom_ser_fdx.c.
341 baycom_ser_hdx= [HW,AX25]
342 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
343 Format: <io>,<irq>,<mode>
344 See header of drivers/net/hamradio/baycom_ser_hdx.c.
346 boot_delay= Milliseconds to delay each printk during boot.
347 Values larger than 10 seconds (10000) are changed to
348 no delay (0).
349 Format: integer
351 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
352 bttv.radio= Most important insmod options are available as
353 kernel args too.
354 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
355 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
357 BusLogic= [HW,SCSI]
358 See drivers/scsi/BusLogic.c, comment before function
359 BusLogic_ParseDriverOptions().
361 c101= [NET] Moxa C101 synchronous serial card
363 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
364 Sometimes CPU hardware bugs make them report the cache
365 size incorrectly. The kernel will attempt work arounds
366 to fix known problems, but for some CPUs it is not
367 possible to determine what the correct size should be.
368 This option provides an override for these situations.
370 security= [SECURITY] Choose a security module to enable at boot.
371 If this boot parameter is not specified, only the first
372 security module asking for security registration will be
373 loaded. An invalid security module name will be treated
374 as if no module has been chosen.
376 capability.disable=
377 [SECURITY] Disable capabilities. This would normally
378 be used only if an alternative security model is to be
379 configured. Potentially dangerous and should only be
380 used if you are entirely sure of the consequences.
382 ccw_timeout_log [S390]
383 See Documentation/s390/CommonIO for details.
385 cgroup_disable= [KNL] Disable a particular controller
386 Format: {name of the controller(s) to disable}
387 {Currently supported controllers - "memory"}
389 checkreqprot [SELINUX] Set initial checkreqprot flag value.
390 Format: { "0" | "1" }
391 See security/selinux/Kconfig help text.
392 0 -- check protection applied by kernel (includes
393 any implied execute protection).
394 1 -- check protection requested by application.
395 Default value is set via a kernel config option.
396 Value can be changed at runtime via
397 /selinux/checkreqprot.
399 cio_ignore= [S390]
400 See Documentation/s390/CommonIO for details.
402 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
403 [Deprecated]
404 Forces specified clocksource (if available) to be used
405 when calculating gettimeofday(). If specified
406 clocksource is not available, it defaults to PIT.
407 Format: { pit | tsc | cyclone | pmtmr }
409 clocksource= [GENERIC_TIME] Override the default clocksource
410 Format: <string>
411 Override the default clocksource and use the clocksource
412 with the name specified.
413 Some clocksource names to choose from, depending on
414 the platform:
415 [all] jiffies (this is the base, fallback clocksource)
416 [ACPI] acpi_pm
417 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
418 pxa_timer,timer3,32k_counter,timer0_1
419 [AVR32] avr32
420 [X86-32] pit,hpet,tsc,vmi-timer;
421 scx200_hrt on Geode; cyclone on IBM x440
422 [MIPS] MIPS
423 [PARISC] cr16
424 [S390] tod
425 [SH] SuperH
426 [SPARC64] tick
427 [X86-64] hpet,tsc
429 clearcpuid=BITNUM [X86]
430 Disable CPUID feature X for the kernel. See
431 include/asm-x86/cpufeature.h for the valid bit numbers.
432 Note the Linux specific bits are not necessarily
433 stable over kernel options, but the vendor specific
434 ones should be.
435 Also note that user programs calling CPUID directly
436 or using the feature without checking anything
437 will still see it. This just prevents it from
438 being used by the kernel or shown in /proc/cpuinfo.
439 Also note the kernel might malfunction if you disable
440 some critical bits.
442 code_bytes [IA32/X86_64] How many bytes of object code to print
443 in an oops report.
444 Range: 0 - 8192
445 Default: 64
447 disable_8254_timer
448 enable_8254_timer
449 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
450 over the 8254 in addition to over the IO-APIC. The
451 kernel tries to set a sensible default.
453 hpet= [X86-32,HPET] option to control HPET usage
454 Format: { enable (default) | disable | force }
455 disable: disable HPET and use PIT instead
456 force: allow force enabled of undocumented chips (ICH4,
457 VIA, nVidia)
459 com20020= [HW,NET] ARCnet - COM20020 chipset
460 Format:
461 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
463 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
464 Format: <io>[,<irq>]
466 com90xx= [HW,NET]
467 ARCnet - COM90xx chipset (memory-mapped buffers)
468 Format: <io>[,<irq>[,<memstart>]]
470 condev= [HW,S390] console device
471 conmode=
473 console= [KNL] Output console device and options.
475 tty<n> Use the virtual console device <n>.
477 ttyS<n>[,options]
478 ttyUSB0[,options]
479 Use the specified serial port. The options are of
480 the form "bbbbpnf", where "bbbb" is the baud rate,
481 "p" is parity ("n", "o", or "e"), "n" is number of
482 bits, and "f" is flow control ("r" for RTS or
483 omit it). Default is "9600n8".
485 See Documentation/serial-console.txt for more
486 information. See
487 Documentation/networking/netconsole.txt for an
488 alternative.
490 uart[8250],io,<addr>[,options]
491 uart[8250],mmio,<addr>[,options]
492 Start an early, polled-mode console on the 8250/16550
493 UART at the specified I/O port or MMIO address,
494 switching to the matching ttyS device later. The
495 options are the same as for ttyS, above.
497 If the device connected to the port is not a TTY but a braille
498 device, prepend "brl," before the device type, for instance
499 console=brl,ttyS0
500 For now, only VisioBraille is supported.
502 earlycon= [KNL] Output early console device and options.
503 uart[8250],io,<addr>[,options]
504 uart[8250],mmio,<addr>[,options]
505 Start an early, polled-mode console on the 8250/16550
506 UART at the specified I/O port or MMIO address.
507 The options are the same as for ttyS, above.
509 no_console_suspend
510 [HW] Never suspend the console
511 Disable suspending of consoles during suspend and
512 hibernate operations. Once disabled, debugging
513 messages can reach various consoles while the rest
514 of the system is being put to sleep (ie, while
515 debugging driver suspend/resume hooks). This may
516 not work reliably with all consoles, but is known
517 to work with serial and VGA consoles.
519 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
520 Format:
521 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
523 crashkernel=nn[KMG]@ss[KMG]
524 [KNL] Reserve a chunk of physical memory to
525 hold a kernel to switch to with kexec on panic.
527 crashkernel=range1:size1[,range2:size2,...][@offset]
528 [KNL] Same as above, but depends on the memory
529 in the running system. The syntax of range is
530 start-[end] where start and end are both
531 a memory unit (amount[KMG]). See also
532 Documentation/kdump/kdump.txt for a example.
534 cs4232= [HW,OSS]
535 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
537 cs89x0_dma= [HW,NET]
538 Format: <dma>
540 cs89x0_media= [HW,NET]
541 Format: { rj45 | aui | bnc }
543 dasd= [HW,NET]
544 See header of drivers/s390/block/dasd_devmap.c.
546 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
547 (one device per port)
548 Format: <port#>,<type>
549 See also Documentation/input/joystick-parport.txt
551 debug [KNL] Enable kernel debugging (events log level).
553 debug_locks_verbose=
554 [KNL] verbose self-tests
555 Format=<0|1>
556 Print debugging info while doing the locking API
557 self-tests.
558 We default to 0 (no extra messages), setting it to
559 1 will print _a lot_ more information - normally
560 only useful to kernel developers.
562 debug_objects [KNL] Enable object debugging
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: {"off" | "on" | "skip[mbr]"}
637 eisa_irq_edge= [PARISC,HW]
638 See header of drivers/parisc/eisa.c.
640 elanfreq= [X86-32]
641 See comment before function elanfreq_setup() in
642 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
644 elevator= [IOSCHED]
645 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
646 See Documentation/block/as-iosched.txt and
647 Documentation/block/deadline-iosched.txt for details.
649 elfcorehdr= [X86-32, X86_64]
650 Specifies physical address of start of kernel core
651 image elf header. Generally kexec loader will
652 pass this option to capture kernel.
653 See Documentation/kdump/kdump.txt for details.
655 enforcing [SELINUX] Set initial enforcing status.
656 Format: {"0" | "1"}
657 See security/selinux/Kconfig help text.
658 0 -- permissive (log only, no denials).
659 1 -- enforcing (deny and log).
660 Default value is 0.
661 Value can be changed at runtime via /selinux/enforce.
663 es1371= [HW,OSS]
664 Format: <spdif>,[<nomix>,[<amplifier>]]
665 See also header of sound/oss/es1371.c.
667 ether= [HW,NET] Ethernet cards parameters
668 This option is obsoleted by the "netdev=" option, which
669 has equivalent usage. See its documentation for details.
671 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
672 Format: <io>[,<irq>]
674 failslab=
675 fail_page_alloc=
676 fail_make_request=[KNL]
677 General fault injection mechanism.
678 Format: <interval>,<probability>,<space>,<times>
679 See also /Documentation/fault-injection/.
681 fd_mcs= [HW,SCSI]
682 See header of drivers/scsi/fd_mcs.c.
684 fdomain= [HW,SCSI]
685 See header of drivers/scsi/fdomain.c.
687 floppy= [HW]
688 See Documentation/floppy.txt.
690 force_pal_cache_flush
691 [IA-64] Avoid check_sal_cache_flush which may hang on
692 buggy SAL_CACHE_FLUSH implementations. Using this
693 parameter will force ia64_sal_cache_flush to call
694 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
696 gamecon.map[2|3]=
697 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
698 support via parallel port (up to 5 devices per port)
699 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
700 See also Documentation/input/joystick-parport.txt
702 gamma= [HW,DRM]
704 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
705 Format: off | on
706 default: on
708 gdth= [HW,SCSI]
709 See header of drivers/scsi/gdth.c.
711 gpt [EFI] Forces disk with valid GPT signature but
712 invalid Protective MBR to be treated as GPT.
714 gvp11= [HW,SCSI]
716 hashdist= [KNL,NUMA] Large hashes allocated during boot
717 are distributed across NUMA nodes. Defaults on
718 for IA-64, off otherwise.
719 Format: 0 | 1 (for off | on)
721 hcl= [IA-64] SGI's Hardware Graph compatibility layer
723 hd= [EIDE] (E)IDE hard drive subsystem geometry
724 Format: <cyl>,<head>,<sect>
726 hd?= [HW] (E)IDE subsystem
727 hd?lun= See Documentation/ide/ide.txt.
729 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
730 size of <nn>. This works even on boxes that have no
731 highmem otherwise. This also works to reduce highmem
732 size on bigger boxes.
734 highres= [KNL] Enable/disable high resolution timer mode.
735 Valid parameters: "on", "off"
736 Default: "on"
738 hisax= [HW,ISDN]
739 See Documentation/isdn/README.HiSax.
741 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
742 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
744 i8042.direct [HW] Put keyboard port into non-translated mode
745 i8042.dumbkbd [HW] Pretend that controller can only read data from
746 keyboard and cannot control its state
747 (Don't attempt to blink the leds)
748 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
749 i8042.nokbd [HW] Don't check/create keyboard port
750 i8042.noloop [HW] Disable the AUX Loopback command while probing
751 for the AUX port
752 i8042.nomux [HW] Don't check presence of an active multiplexing
753 controller
754 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
755 controllers
756 i8042.panicblink=
757 [HW] Frequency with which keyboard LEDs should blink
758 when kernel panics (default is 0.5 sec)
759 i8042.reset [HW] Reset the controller during init and cleanup
760 i8042.unlock [HW] Unlock (ignore) the keylock
762 i810= [HW,DRM]
764 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
765 indicates that the driver is running on unsupported
766 hardware.
767 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
768 does not match list of supported models.
769 i8k.power_status
770 [HW] Report power status in /proc/i8k
771 (disabled by default)
772 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
773 capability is set.
775 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
776 See Documentation/mca.txt.
778 icn= [HW,ISDN]
779 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
781 ide= [HW] (E)IDE subsystem
782 Format: ide=nodma or ide=doubler
783 See Documentation/ide/ide.txt.
785 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
786 See Documentation/ide/ide.txt.
788 idle= [X86]
789 Format: idle=poll or idle=mwait
790 Poll forces a polling idle loop that can slightly improves the performance
791 of waking up a idle CPU, but will use a lot of power and make the system
792 run hot. Not recommended.
793 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
794 to not use it because it doesn't save as much power as a normal idle
795 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
796 as idle=poll.
798 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
799 Claim all unknown PCI IDE storage controllers.
801 ignore_loglevel [KNL]
802 Ignore loglevel setting - this will print /all/
803 kernel messages to the console. Useful for debugging.
805 ihash_entries= [KNL]
806 Set number of hash buckets for inode cache.
808 in2000= [HW,SCSI]
809 See header of drivers/scsi/in2000.c.
811 init= [KNL]
812 Format: <full_path>
813 Run specified binary instead of /sbin/init as init
814 process.
816 initcall_debug [KNL] Trace initcalls as they are executed. Useful
817 for working out where the kernel is dying during
818 startup.
820 initrd= [BOOT] Specify the location of the initial ramdisk
822 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
823 Format: <irq>
825 inttest= [IA64]
827 iommu= [x86]
828 off
829 force
830 noforce
831 biomerge
832 panic
833 nopanic
834 merge
835 nomerge
836 forcesac
837 soft
840 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
841 off
842 Disable intel iommu driver.
843 igfx_off [Default Off]
844 By default, gfx is mapped as normal device. If a gfx
845 device has a dedicated DMAR unit, the DMAR unit is
846 bypassed by not enabling DMAR with this option. In
847 this case, gfx device will use physical address for
848 DMA.
849 forcedac [x86_64]
850 With this option iommu will not optimize to look
851 for io virtual address below 32 bit forcing dual
852 address cycle on pci bus for cards supporting greater
853 than 32 bit addressing. The default is to look
854 for translation below 32 bit and if not available
855 then look in the higher range.
856 strict [Default Off]
857 With this option on every unmap_single operation will
858 result in a hardware IOTLB flush operation as opposed
859 to batching them for performance.
861 io_delay= [X86-32,X86-64] I/O delay method
862 0x80
863 Standard port 0x80 based delay
864 0xed
865 Alternate port 0xed based delay (needed on some systems)
866 udelay
867 Simple two microseconds delay
868 none
869 No delay
871 io7= [HW] IO7 for Marvel based alpha systems
872 See comment before marvel_specify_io7 in
873 arch/alpha/kernel/core_marvel.c.
875 ip= [IP_PNP]
876 See Documentation/filesystems/nfsroot.txt.
878 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
879 See comment before ip2_setup() in
880 drivers/char/ip2/ip2base.c.
882 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
883 See header of drivers/scsi/ips.c.
885 ports= [IP_VS_FTP] IPVS ftp helper module
886 Default is 21.
887 Up to 8 (IP_VS_APP_MAX_PORTS) ports
888 may be specified.
889 Format: <port>,<port>....
891 irqfixup [HW]
892 When an interrupt is not handled search all handlers
893 for it. Intended to get systems with badly broken
894 firmware running.
896 irqpoll [HW]
897 When an interrupt is not handled search all handlers
898 for it. Also check all handlers each timer
899 interrupt. Intended to get systems with badly broken
900 firmware running.
902 isapnp= [ISAPNP]
903 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
905 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
906 Format:
907 <cpu number>,...,<cpu number>
908 or
909 <cpu number>-<cpu number> (must be a positive range in ascending order)
910 or a mixture
911 <cpu number>,...,<cpu number>-<cpu number>
912 This option can be used to specify one or more CPUs
913 to isolate from the general SMP balancing and scheduling
914 algorithms. The only way to move a process onto or off
915 an "isolated" CPU is via the CPU affinity syscalls.
916 <cpu number> begins at 0 and the maximum value is
917 "number of CPUs in system - 1".
919 This option is the preferred way to isolate CPUs. The
920 alternative -- manually setting the CPU mask of all
921 tasks in the system -- can cause problems and
922 suboptimal load balancer performance.
924 iucv= [HW,NET]
926 js= [HW,JOY] Analog joystick
927 See Documentation/input/joystick.txt.
929 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
930 specifies the amount of memory usable by the kernel
931 for non-movable allocations. The requested amount is
932 spread evenly throughout all nodes in the system. The
933 remaining memory in each node is used for Movable
934 pages. In the event, a node is too small to have both
935 kernelcore and Movable pages, kernelcore pages will
936 take priority and other nodes will have a larger number
937 of kernelcore pages. The Movable zone is used for the
938 allocation of pages that may be reclaimed or moved
939 by the page migration subsystem. This means that
940 HugeTLB pages may not be allocated from this zone.
941 Note that allocations like PTEs-from-HighMem still
942 use the HighMem zone if it exists, and the Normal
943 zone if it does not.
945 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
946 Controls whether kmemtrace is enabled
947 at boot-time.
949 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
950 subbufs kmemtrace's relay channel has. Set this
951 higher than default (KMEMTRACE_N_SUBBUFS in code) if
952 you experience buffer overruns.
954 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
955 is similar to kernelcore except it specifies the
956 amount of memory used for migratable allocations.
957 If both kernelcore and movablecore is specified,
958 then kernelcore will be at *least* the specified
959 value but may be more. If movablecore on its own
960 is specified, the administrator must be careful
961 that the amount of memory usable for all allocations
962 is not too small.
964 keepinitrd [HW,ARM]
966 kstack=N [X86-32,X86-64] Print N words from the kernel stack
967 in oops dumps.
969 kgdboc= [HW] kgdb over consoles.
970 Requires a tty driver that supports console polling.
971 (only serial suported for now)
972 Format: <serial_device>[,baud]
974 l2cr= [PPC]
976 l3cr= [PPC]
978 lapic [X86-32,APIC] Enable the local APIC even if BIOS
979 disabled it.
981 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
982 C2 power state.
984 libata.dma= [LIBATA] DMA control
985 libata.dma=0 Disable all PATA and SATA DMA
986 libata.dma=1 PATA and SATA Disk DMA only
987 libata.dma=2 ATAPI (CDROM) DMA only
988 libata.dma=4 Compact Flash DMA only
989 Combinations also work, so libata.dma=3 enables DMA
990 for disks and CDROMs, but not CFs.
992 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
993 when set.
994 Format: <int>
996 libata.force= [LIBATA] Force configurations. The format is comma
997 separated list of "[ID:]VAL" where ID is
998 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
999 matching port, link or device. Basically, it matches
1000 the ATA ID string printed on console by libata. If
1001 the whole ID part is omitted, the last PORT and DEVICE
1002 values are used. If ID hasn't been specified yet, the
1003 configuration applies to all ports, links and devices.
1005 If only DEVICE is omitted, the parameter applies to
1006 the port and all links and devices behind it. DEVICE
1007 number of 0 either selects the first device or the
1008 first fan-out link behind PMP device. It does not
1009 select the host link. DEVICE number of 15 selects the
1010 host link and device attached to it.
1012 The VAL specifies the configuration to force. As long
1013 as there's no ambiguity shortcut notation is allowed.
1014 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1015 The following configurations can be forced.
1017 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1018 Any ID with matching PORT is used.
1020 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1022 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1023 udma[/][16,25,33,44,66,100,133] notation is also
1024 allowed.
1026 * [no]ncq: Turn on or off NCQ.
1028 If there are multiple matching configurations changing
1029 the same attribute, the last one is used.
1031 load_ramdisk= [RAM] List of ramdisks to load from floppy
1032 See Documentation/ramdisk.txt.
1034 lockd.nlm_grace_period=P [NFS] Assign grace period.
1035 Format: <integer>
1037 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1038 Format: <integer>
1040 lockd.nlm_timeout=T [NFS] Assign timeout value.
1041 Format: <integer>
1043 lockd.nlm_udpport=M [NFS] Assign UDP port.
1044 Format: <integer>
1046 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1047 Format: <irq>
1049 loglevel= All Kernel Messages with a loglevel smaller than the
1050 console loglevel will be printed to the console. It can
1051 also be changed with klogd or other programs. The
1052 loglevels are defined as follows:
1054 0 (KERN_EMERG) system is unusable
1055 1 (KERN_ALERT) action must be taken immediately
1056 2 (KERN_CRIT) critical conditions
1057 3 (KERN_ERR) error conditions
1058 4 (KERN_WARNING) warning conditions
1059 5 (KERN_NOTICE) normal but significant condition
1060 6 (KERN_INFO) informational
1061 7 (KERN_DEBUG) debug-level messages
1063 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1064 Format: { n | nk | nM }
1065 n must be a power of two. The default size
1066 is set in the kernel config file.
1068 logo.nologo [FB] Disables display of the built-in Linux logo.
1069 This may be used to provide more screen space for
1070 kernel log messages and is useful when debugging
1071 kernel boot problems.
1073 lp=0 [LP] Specify parallel ports to use, e.g,
1074 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1075 lp=reset first parallel port). 'lp=0' disables the
1076 lp=auto printer driver. 'lp=reset' (which can be
1077 specified in addition to the ports) causes
1078 attached printers to be reset. Using
1079 lp=port1,port2,... specifies the parallel ports
1080 to associate lp devices with, starting with
1081 lp0. A port specification may be 'none' to skip
1082 that lp device, or a parport name such as
1083 'parport0'. Specifying 'lp=auto' instead of a
1084 port specification list means that device IDs
1085 from each port should be examined, to see if
1086 an IEEE 1284-compliant printer is attached; if
1087 so, the driver will manage that printer.
1088 See also header of drivers/char/lp.c.
1090 lpj=n [KNL]
1091 Sets loops_per_jiffy to given constant, thus avoiding
1092 time-consuming boot-time autodetection (up to 250 ms per
1093 CPU). 0 enables autodetection (default). To determine
1094 the correct value for your kernel, boot with normal
1095 autodetection and see what value is printed. Note that
1096 on SMP systems the preset will be applied to all CPUs,
1097 which is likely to cause problems if your CPUs need
1098 significantly divergent settings. An incorrect value
1099 will cause delays in the kernel to be wrong, leading to
1100 unpredictable I/O errors and other breakage. Although
1101 unlikely, in the extreme case this might damage your
1102 hardware.
1104 ltpc= [NET]
1105 Format: <io>,<irq>,<dma>
1107 mac5380= [HW,SCSI] Format:
1108 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1110 machvec= [IA64] Force the use of a particular machine-vector
1111 (machvec) in a generic kernel.
1112 Example: machvec=hpzx1_swiotlb
1114 max_loop= [LOOP] Maximum number of loopback devices that can
1115 be mounted
1116 Format: <1-256>
1118 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1119 should make use of. maxcpus=n : n >= 0 limits the
1120 kernel to using 'n' processors. n=0 is a special case,
1121 it is equivalent to "nosmp", which also disables
1122 the IO APIC.
1124 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1125 equal to this physical address is ignored.
1127 max_luns= [SCSI] Maximum number of LUNs to probe.
1128 Should be between 1 and 2^32-1.
1130 max_report_luns=
1131 [SCSI] Maximum number of LUNs received.
1132 Should be between 1 and 16384.
1134 mcatest= [IA-64]
1136 mce [X86-32] Machine Check Exception
1138 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1140 md= [HW] RAID subsystems devices and level
1141 See Documentation/md.txt.
1143 mdacon= [MDA]
1144 Format: <first>,<last>
1145 Specifies range of consoles to be captured by the MDA.
1147 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1148 Amount of memory to be used when the kernel is not able
1149 to see the whole system memory or for test.
1150 [X86-32] Use together with memmap= to avoid physical
1151 address space collisions. Without memmap= PCI devices
1152 could be placed at addresses belonging to unused RAM.
1154 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1155 memory.
1157 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1158 E820 memory map, as specified by the user.
1159 Such memmap=exactmap lines can be constructed based on
1160 BIOS output or other requirements. See the memmap=nn@ss
1161 option description.
1163 memmap=nn[KMG]@ss[KMG]
1164 [KNL] Force usage of a specific region of memory
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 ACPI data.
1169 Region of memory to be used, from ss to ss+nn.
1171 memmap=nn[KMG]$ss[KMG]
1172 [KNL,ACPI] Mark specific memory as reserved.
1173 Region of memory to be used, from ss to ss+nn.
1174 Example: Exclude memory from 0x18690000-0x1869ffff
1175 memmap=64K$0x18690000
1176 or
1177 memmap=0x10000$0x18690000
1179 memtest= [KNL,X86_64] Enable memtest
1180 Format: <integer>
1181 range: 0,4 : pattern number
1182 default : 0 <disable>
1184 meye.*= [HW] Set MotionEye Camera parameters
1185 See Documentation/video4linux/meye.txt.
1187 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1188 Multi-Function General Purpose Timers on AMD Geode
1189 platforms.
1191 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1192 the BIOS has incorrectly applied a workaround. TinyBIOS
1193 version 0.98 is known to be affected, 0.99 fixes the
1194 problem by letting the user disable the workaround.
1196 mga= [HW,DRM]
1198 mousedev.tap_time=
1199 [MOUSE] Maximum time between finger touching and
1200 leaving touchpad surface for touch to be considered
1201 a tap and be reported as a left button click (for
1202 touchpads working in absolute mode only).
1203 Format: <msecs>
1204 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1205 reporting absolute coordinates, such as tablets
1206 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1207 reporting absolute coordinates, such as tablets
1209 mpu401= [HW,OSS]
1210 Format: <io>,<irq>
1212 MTD_Partition= [MTD]
1213 Format: <name>,<region-number>,<size>,<offset>
1215 MTD_Region= [MTD] Format:
1216 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1218 mtdparts= [MTD]
1219 See drivers/mtd/cmdlinepart.c.
1221 mtouchusb.raw_coordinates=
1222 [HW] Make the MicroTouch USB driver use raw coordinates
1223 ('y', default) or cooked coordinates ('n')
1225 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1227 NCR_D700= [HW,SCSI]
1228 See header of drivers/scsi/NCR_D700.c.
1230 ncr5380= [HW,SCSI]
1232 ncr53c400= [HW,SCSI]
1234 ncr53c400a= [HW,SCSI]
1236 ncr53c406a= [HW,SCSI]
1238 ncr53c8xx= [HW,SCSI]
1240 netdev= [NET] Network devices parameters
1241 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1242 Note that mem_start is often overloaded to mean
1243 something different and driver-specific.
1244 This usage is only documented in each driver source
1245 file if at all.
1247 nfsaddrs= [NFS]
1248 See Documentation/filesystems/nfsroot.txt.
1250 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1251 See Documentation/filesystems/nfsroot.txt.
1253 nfs.callback_tcpport=
1254 [NFS] set the TCP port on which the NFSv4 callback
1255 channel should listen.
1257 nfs.idmap_cache_timeout=
1258 [NFS] set the maximum lifetime for idmapper cache
1259 entries.
1261 nfs.enable_ino64=
1262 [NFS] enable 64-bit inode numbers.
1263 If zero, the NFS client will fake up a 32-bit inode
1264 number for the readdir() and stat() syscalls instead
1265 of returning the full 64-bit number.
1266 The default is to return 64-bit inode numbers.
1268 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1269 when a NMI is triggered.
1270 Format: [state][,regs][,debounce][,die]
1272 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1274 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1275 emulation library even if a 387 maths coprocessor
1276 is present.
1278 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1279 caches in the slab allocator. Saves per-node memory,
1280 but will impact performance.
1282 noalign [KNL,ARM]
1284 noapic [SMP,APIC] Tells the kernel to not make use of any
1285 IOAPICs that may be present in the system.
1287 nobats [PPC] Do not use BATs for mapping kernel lowmem
1288 on "Classic" PPC cores.
1290 nocache [ARM]
1292 nodelayacct [KNL] Disable per-task delay accounting
1294 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1296 noefi [X86-32,X86-64] Disable EFI runtime services support.
1298 noexec [IA-64]
1300 noexec [X86-32,X86-64]
1301 On X86-32 available only on PAE configured kernels.
1302 noexec=on: enable non-executable mappings (default)
1303 noexec=off: disable non-executable mappings
1305 noexec32 [X86-64]
1306 This affects only 32-bit executables.
1307 noexec32=on: enable non-executable mappings (default)
1308 read doesn't imply executable mappings
1309 noexec32=off: disable non-executable mappings
1310 read implies executable mappings
1312 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1313 register save and restore. The kernel will only save
1314 legacy floating-point registers on task switch.
1316 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1318 nohlt [BUGS=ARM]
1320 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1321 instruction doesn't work correctly and not to
1322 use it.
1324 nohalt [IA-64] Tells the kernel not to use the power saving
1325 function PAL_HALT_LIGHT when idle. This increases
1326 power-consumption. On the positive side, it reduces
1327 interrupt wake-up latency, which may improve performance
1328 in certain environments such as networked servers or
1329 real-time systems.
1331 nohz= [KNL] Boottime enable/disable dynamic ticks
1332 Valid arguments: on, off
1333 Default: on
1335 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1337 noirqdebug [X86-32] Disables the code which attempts to detect and
1338 disable unhandled interrupt sources.
1340 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1341 broken timer IRQ sources.
1343 noisapnp [ISAPNP] Disables ISA PnP code.
1345 noinitrd [RAM] Tells the kernel not to load any configured
1346 initial RAM disk.
1348 nointroute [IA-64]
1350 nojitter [IA64] Disables jitter checking for ITC timers.
1352 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1354 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1356 noltlbs [PPC] Do not use large page/tlb entries for kernel
1357 lowmem mapping on PPC40x.
1359 nomca [IA-64] Disable machine check abort handling
1361 nomce [X86-32] Machine Check Exception
1363 nomfgpt [X86-32] Disable Multi-Function General Purpose
1364 Timer usage (for AMD Geode machines).
1366 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1368 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1369 with UP alternatives
1371 noresidual [PPC] Don't use residual data on PReP machines.
1373 noresume [SWSUSP] Disables resume and restores original swap
1374 space.
1376 no-scroll [VGA] Disables scrollback.
1377 This is required for the Braillex ib80-piezo Braille
1378 reader made by F.H. Papenmeier (Germany).
1380 nosbagart [IA-64]
1382 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1384 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1385 and disable the IO APIC. legacy for "maxcpus=0".
1387 nosoftlockup [KNL] Disable the soft-lockup detector.
1389 nosync [HW,M68K] Disables sync negotiation for all devices.
1391 notsc [BUGS=X86-32] Disable Time Stamp Counter
1393 nousb [USB] Disable the USB subsystem
1395 nowb [ARM]
1397 nptcg= [IA64] Override max number of concurrent global TLB
1398 purges which is reported from either PAL_VM_SUMMARY or
1399 SAL PALO.
1401 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1402 one of ['zone', 'node', 'default'] can be specified
1403 This can be set from sysctl after boot.
1404 See Documentation/sysctl/vm.txt for details.
1406 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1408 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1409 Rather than timing out after 20 ms if an EC
1410 command is not properly ACKed, override the length
1411 of the timeout. We have interrupts disabled while
1412 waiting for the ACK, so if this is set too high
1413 interrupts *may* be lost!
1415 opl3= [HW,OSS]
1416 Format: <io>
1418 oprofile.timer= [HW]
1419 Use timer interrupt instead of performance counters
1421 osst= [HW,SCSI] SCSI Tape Driver
1422 Format: <buffer_size>,<write_threshold>
1423 See also Documentation/scsi/st.txt.
1425 panic= [KNL] Kernel behaviour on panic
1426 Format: <timeout>
1428 parkbd.port= [HW] Parallel port number the keyboard adapter is
1429 connected to, default is 0.
1430 Format: <parport#>
1431 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1432 0 for XT, 1 for AT (default is AT).
1433 Format: <mode>
1435 parport= [HW,PPT] Specify parallel ports. 0 disables.
1436 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1437 Use 'auto' to force the driver to use any
1438 IRQ/DMA settings detected (the default is to
1439 ignore detected IRQ/DMA settings because of
1440 possible conflicts). You can specify the base
1441 address, IRQ, and DMA settings; IRQ and DMA
1442 should be numbers, or 'auto' (for using detected
1443 settings on that particular port), or 'nofifo'
1444 (to avoid using a FIFO even if it is detected).
1445 Parallel ports are assigned in the order they
1446 are specified on the command line, starting
1447 with parport0.
1449 parport_init_mode= [HW,PPT]
1450 Configure VIA parallel port to operate in
1451 a specific mode. This is necessary on Pegasos
1452 computer where firmware has no options for setting
1453 up parallel port mode and sets it to spp.
1454 Currently this function knows 686a and 8231 chips.
1455 Format: [spp|ps2|epp|ecp|ecpepp]
1457 pas2= [HW,OSS] Format:
1458 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1460 pas16= [HW,SCSI]
1461 See header of drivers/scsi/pas16.c.
1463 pause_on_oops=
1464 Halt all CPUs after the first oops has been printed for
1465 the specified number of seconds. This is to be used if
1466 your oopses keep scrolling off the screen.
1468 pcbit= [HW,ISDN]
1470 pcd. [PARIDE]
1471 See header of drivers/block/paride/pcd.c.
1472 See also Documentation/paride.txt.
1474 pci=option[,option...] [PCI] various PCI subsystem options:
1475 off [X86-32] don't probe for the PCI bus
1476 bios [X86-32] force use of PCI BIOS, don't access
1477 the hardware directly. Use this if your machine
1478 has a non-standard PCI host bridge.
1479 nobios [X86-32] disallow use of PCI BIOS, only direct
1480 hardware access methods are allowed. Use this
1481 if you experience crashes upon bootup and you
1482 suspect they are caused by the BIOS.
1483 conf1 [X86-32] Force use of PCI Configuration
1484 Mechanism 1.
1485 conf2 [X86-32] Force use of PCI Configuration
1486 Mechanism 2.
1487 noaer [PCIE] If the PCIEAER kernel config parameter is
1488 enabled, this kernel boot option can be used to
1489 disable the use of PCIE advanced error reporting.
1490 nodomains [PCI] Disable support for multiple PCI
1491 root domains (aka PCI segments, in ACPI-speak).
1492 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1493 Configuration
1494 nomsi [MSI] If the PCI_MSI kernel config parameter is
1495 enabled, this kernel boot option can be used to
1496 disable the use of MSI interrupts system-wide.
1497 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1498 routing table. These calls are known to be buggy
1499 on several machines and they hang the machine
1500 when used, but on other computers it's the only
1501 way to get the interrupt routing table. Try
1502 this option if the kernel is unable to allocate
1503 IRQs or discover secondary PCI buses on your
1504 motherboard.
1505 rom [X86-32] Assign address space to expansion ROMs.
1506 Use with caution as certain devices share
1507 address decoders between ROMs and other
1508 resources.
1509 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1510 assigned automatically to PCI devices. You can
1511 make the kernel exclude IRQs of your ISA cards
1512 this way.
1513 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1514 of the PIRQ table (normally generated
1515 by the BIOS) if it is outside the
1516 F0000h-100000h range.
1517 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1518 useful if the kernel is unable to find your
1519 secondary buses and you want to tell it
1520 explicitly which ones they are.
1521 assign-busses [X86-32] Always assign all PCI bus
1522 numbers ourselves, overriding
1523 whatever the firmware may have done.
1524 usepirqmask [X86-32] Honor the possible IRQ mask stored
1525 in the BIOS $PIR table. This is needed on
1526 some systems with broken BIOSes, notably
1527 some HP Pavilion N5400 and Omnibook XE3
1528 notebooks. This will have no effect if ACPI
1529 IRQ routing is enabled.
1530 noacpi [X86-32] Do not use ACPI for IRQ routing
1531 or for PCI scanning.
1532 use_crs [X86-32] Use _CRS for PCI resource
1533 allocation.
1534 routeirq Do IRQ routing for all PCI devices.
1535 This is normally done in pci_enable_device(),
1536 so this option is a temporary workaround
1537 for broken drivers that don't call it.
1538 skip_isa_align [X86] do not align io start addr, so can
1539 handle more pci cards
1540 firmware [ARM] Do not re-enumerate the bus but instead
1541 just use the configuration from the
1542 bootloader. This is currently used on
1543 IXP2000 systems where the bus has to be
1544 configured a certain way for adjunct CPUs.
1545 noearly [X86] Don't do any early type 1 scanning.
1546 This might help on some broken boards which
1547 machine check when some devices' config space
1548 is read. But various workarounds are disabled
1549 and some IOMMU drivers will not work.
1550 bfsort Sort PCI devices into breadth-first order.
1551 This sorting is done to get a device
1552 order compatible with older (<= 2.4) kernels.
1553 nobfsort Don't sort PCI devices into breadth-first order.
1554 cbiosize=nn[KMG] The fixed amount of bus space which is
1555 reserved for the CardBus bridge's IO window.
1556 The default value is 256 bytes.
1557 cbmemsize=nn[KMG] The fixed amount of bus space which is
1558 reserved for the CardBus bridge's memory
1559 window. The default value is 64 megabytes.
1561 pcmv= [HW,PCMCIA] BadgePAD 4
1563 pd. [PARIDE]
1564 See Documentation/paride.txt.
1566 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1567 boot time.
1568 Format: { 0 | 1 }
1569 See arch/parisc/kernel/pdc_chassis.c
1571 pf. [PARIDE]
1572 See Documentation/paride.txt.
1574 pg. [PARIDE]
1575 See Documentation/paride.txt.
1577 pirq= [SMP,APIC] Manual mp-table setup
1578 See Documentation/i386/IO-APIC.txt.
1580 plip= [PPT,NET] Parallel port network link
1581 Format: { parport<nr> | timid | 0 }
1582 See also Documentation/parport.txt.
1584 pnpacpi= [ACPI]
1585 { off }
1587 pnpbios= [ISAPNP]
1588 { on | off | curr | res | no-curr | no-res }
1590 pnp_reserve_irq=
1591 [ISAPNP] Exclude IRQs for the autoconfiguration
1593 pnp_reserve_dma=
1594 [ISAPNP] Exclude DMAs for the autoconfiguration
1596 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1597 Ranges are in pairs (I/O port base and size).
1599 pnp_reserve_mem=
1600 [ISAPNP] Exclude memory regions for the
1601 autoconfiguration.
1602 Ranges are in pairs (memory base and size).
1604 print-fatal-signals=
1605 [KNL] debug: print fatal signals
1606 print-fatal-signals=1: print segfault info to
1607 the kernel console.
1608 default: off.
1610 printk.time= Show timing data prefixed to each printk message line
1611 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1613 profile= [KNL] Enable kernel profiling via /proc/profile
1614 Format: [schedule,]<number>
1615 Param: "schedule" - profile schedule points.
1616 Param: <number> - step/bucket size as a power of 2 for
1617 statistical time based profiling.
1618 Param: "sleep" - profile D-state sleeping (millisecs).
1619 Requires CONFIG_SCHEDSTATS
1620 Param: "kvm" - profile VM exits.
1622 processor.max_cstate= [HW,ACPI]
1623 Limit processor to maximum C-state
1624 max_cstate=9 overrides any DMI blacklist limit.
1626 processor.nocst [HW,ACPI]
1627 Ignore the _CST method to determine C-states,
1628 instead using the legacy FADT method
1630 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1631 before loading.
1632 See Documentation/ramdisk.txt.
1634 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1635 probe for; one of (bare|imps|exps|lifebook|any).
1636 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1637 per second.
1638 psmouse.resetafter= [HW,MOUSE]
1639 Try to reset the device after so many bad packets
1640 (0 = never).
1641 psmouse.resolution=
1642 [HW,MOUSE] Set desired mouse resolution, in dpi.
1643 psmouse.smartscroll=
1644 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1645 0 = disabled, 1 = enabled (default).
1647 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1648 Format:
1649 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1651 pt. [PARIDE]
1652 See Documentation/paride.txt.
1654 pty.legacy_count=
1655 [KNL] Number of legacy pty's. Overwrites compiled-in
1656 default number.
1658 quiet [KNL] Disable most log messages
1660 r128= [HW,DRM]
1662 raid= [HW,RAID]
1663 See Documentation/md.txt.
1665 ramdisk_blocksize= [RAM]
1666 See Documentation/ramdisk.txt.
1668 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1669 See Documentation/ramdisk.txt.
1671 rcupdate.blimit= [KNL,BOOT]
1672 Set maximum number of finished RCU callbacks to process
1673 in one batch.
1675 rcupdate.qhimark= [KNL,BOOT]
1676 Set threshold of queued
1677 RCU callbacks over which batch limiting is disabled.
1679 rcupdate.qlowmark= [KNL,BOOT]
1680 Set threshold of queued RCU callbacks below which
1681 batch limiting is re-enabled.
1683 rdinit= [KNL]
1684 Format: <full_path>
1685 Run specified binary instead of /init from the ramdisk,
1686 used for early userspace startup. See initrd.
1688 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1689 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1690 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1692 relax_domain_level=
1693 [KNL, SMP] Set scheduler's default relax_domain_level.
1694 See Documentation/cpusets.txt.
1696 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1698 reservetop= [X86-32]
1699 Format: nn[KMG]
1700 Reserves a hole at the top of the kernel virtual
1701 address space.
1703 reset_devices [KNL] Force drivers to reset the underlying device
1704 during initialization.
1706 resume= [SWSUSP]
1707 Specify the partition device for software suspend
1709 resume_offset= [SWSUSP]
1710 Specify the offset from the beginning of the partition
1711 given by "resume=" at which the swap header is located,
1712 in <PAGE_SIZE> units (needed only for swap files).
1713 See Documentation/power/swsusp-and-swap-files.txt
1715 retain_initrd [RAM] Keep initrd memory after extraction
1717 rhash_entries= [KNL,NET]
1718 Set number of hash buckets for route cache
1720 riscom8= [HW,SERIAL]
1721 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1723 ro [KNL] Mount root device read-only on boot
1725 root= [KNL] Root filesystem
1727 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1728 mount the root filesystem
1730 rootflags= [KNL] Set root filesystem mount option string
1732 rootfstype= [KNL] Set root filesystem type
1734 rootwait [KNL] Wait (indefinitely) for root device to show up.
1735 Useful for devices that are detected asynchronously
1736 (e.g. USB and MMC devices).
1738 root_plug.vendor_id=
1739 [ROOTPLUG] Override the default vendor ID
1741 root_plug.product_id=
1742 [ROOTPLUG] Override the default product ID
1744 root_plug.debug=
1745 [ROOTPLUG] Enable debugging output
1747 rw [KNL] Mount root device read-write on boot
1749 S [KNL] Run init in single mode
1751 sa1100ir [NET]
1752 See drivers/net/irda/sa1100_ir.c.
1754 sbni= [NET] Granch SBNI12 leased line adapter
1756 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1757 Format: <io>[,<timeout>[,<isapnp>]]
1759 scsi_debug_*= [SCSI]
1760 See drivers/scsi/scsi_debug.c.
1762 scsi_default_dev_flags=
1763 [SCSI] SCSI default device flags
1764 Format: <integer>
1766 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1767 Format: <vendor>:<model>:<flags>
1768 (flags are integer value)
1770 scsi_logging_level= [SCSI] a bit mask of logging levels
1771 See drivers/scsi/scsi_logging.h for bits. Also
1772 settable via sysctl at dev.scsi.logging_level
1773 (/proc/sys/dev/scsi/logging_level).
1774 There is also a nice 'scsi_logging_level' script in the
1775 S390-tools package, available for download at
1776 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1778 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1779 discovered. async scans them in kernel threads,
1780 allowing boot to proceed. none ignores them, expecting
1781 user space to do the scan.
1783 selinux [SELINUX] Disable or enable SELinux at boot time.
1784 Format: { "0" | "1" }
1785 See security/selinux/Kconfig help text.
1786 0 -- disable.
1787 1 -- enable.
1788 Default value is set via kernel config option.
1789 If enabled at boot time, /selinux/disable can be used
1790 later to disable prior to initial policy load.
1792 selinux_compat_net =
1793 [SELINUX] Set initial selinux_compat_net flag value.
1794 Format: { "0" | "1" }
1795 0 -- use new secmark-based packet controls
1796 1 -- use legacy packet controls
1797 Default value is 0 (preferred).
1798 Value can be changed at runtime via
1799 /selinux/compat_net.
1801 serialnumber [BUGS=X86-32]
1803 shapers= [NET]
1804 Maximal number of shapers.
1806 sim710= [SCSI,HW]
1807 See header of drivers/scsi/sim710.c.
1809 simeth= [IA-64]
1810 simscsi=
1812 slram= [HW,MTD]
1814 slub_debug[=options[,slabs]] [MM, SLUB]
1815 Enabling slub_debug allows one to determine the
1816 culprit if slab objects become corrupted. Enabling
1817 slub_debug can create guard zones around objects and
1818 may poison objects when not in use. Also tracks the
1819 last alloc / free. For more information see
1820 Documentation/vm/slub.txt.
1822 slub_max_order= [MM, SLUB]
1823 Determines the maximum allowed order for slabs.
1824 A high setting may cause OOMs due to memory
1825 fragmentation. For more information see
1826 Documentation/vm/slub.txt.
1828 slub_min_objects= [MM, SLUB]
1829 The minimum number of objects per slab. SLUB will
1830 increase the slab order up to slub_max_order to
1831 generate a sufficiently large slab able to contain
1832 the number of objects indicated. The higher the number
1833 of objects the smaller the overhead of tracking slabs
1834 and the less frequently locks need to be acquired.
1835 For more information see Documentation/vm/slub.txt.
1837 slub_min_order= [MM, SLUB]
1838 Determines the mininum page order for slabs. Must be
1839 lower than slub_max_order.
1840 For more information see Documentation/vm/slub.txt.
1842 slub_nomerge [MM, SLUB]
1843 Disable merging of slabs with similar size. May be
1844 necessary if there is some reason to distinguish
1845 allocs to different slabs. Debug options disable
1846 merging on their own.
1847 For more information see Documentation/vm/slub.txt.
1849 smart2= [HW]
1850 Format: <io1>[,<io2>[,...,<io8>]]
1852 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1853 attempt to substitute SMP alternatives once at boot.
1855 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1856 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1857 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1858 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1859 smsc-ircc2.ircc_irq= [HW] IRQ line
1860 smsc-ircc2.ircc_dma= [HW] DMA channel
1861 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1862 0: Toshiba Satellite 1800 (GP data pin select)
1863 1: Fast pin select (default)
1864 2: ATC IRMode
1866 snd-ad1816a= [HW,ALSA]
1868 snd-ad1848= [HW,ALSA]
1870 snd-ali5451= [HW,ALSA]
1872 snd-als100= [HW,ALSA]
1874 snd-als4000= [HW,ALSA]
1876 snd-azt2320= [HW,ALSA]
1878 snd-cmi8330= [HW,ALSA]
1880 snd-cmipci= [HW,ALSA]
1882 snd-cs4231= [HW,ALSA]
1884 snd-cs4232= [HW,ALSA]
1886 snd-cs4236= [HW,ALSA]
1888 snd-cs4281= [HW,ALSA]
1890 snd-cs46xx= [HW,ALSA]
1892 snd-dt019x= [HW,ALSA]
1894 snd-dummy= [HW,ALSA]
1896 snd-emu10k1= [HW,ALSA]
1898 snd-ens1370= [HW,ALSA]
1900 snd-ens1371= [HW,ALSA]
1902 snd-es968= [HW,ALSA]
1904 snd-es1688= [HW,ALSA]
1906 snd-es18xx= [HW,ALSA]
1908 snd-es1938= [HW,ALSA]
1910 snd-es1968= [HW,ALSA]
1912 snd-fm801= [HW,ALSA]
1914 snd-gusclassic= [HW,ALSA]
1916 snd-gusextreme= [HW,ALSA]
1918 snd-gusmax= [HW,ALSA]
1920 snd-hdsp= [HW,ALSA]
1922 snd-ice1712= [HW,ALSA]
1924 snd-intel8x0= [HW,ALSA]
1926 snd-interwave= [HW,ALSA]
1928 snd-interwave-stb=
1929 [HW,ALSA]
1931 snd-korg1212= [HW,ALSA]
1933 snd-maestro3= [HW,ALSA]
1935 snd-mpu401= [HW,ALSA]
1937 snd-mtpav= [HW,ALSA]
1939 snd-nm256= [HW,ALSA]
1941 snd-opl3sa2= [HW,ALSA]
1943 snd-opti92x-ad1848=
1944 [HW,ALSA]
1946 snd-opti92x-cs4231=
1947 [HW,ALSA]
1949 snd-opti93x= [HW,ALSA]
1951 snd-pmac= [HW,ALSA]
1953 snd-rme32= [HW,ALSA]
1955 snd-rme96= [HW,ALSA]
1957 snd-rme9652= [HW,ALSA]
1959 snd-sb8= [HW,ALSA]
1961 snd-sb16= [HW,ALSA]
1963 snd-sbawe= [HW,ALSA]
1965 snd-serial= [HW,ALSA]
1967 snd-sgalaxy= [HW,ALSA]
1969 snd-sonicvibes= [HW,ALSA]
1971 snd-sun-amd7930=
1972 [HW,ALSA]
1974 snd-sun-cs4231= [HW,ALSA]
1976 snd-trident= [HW,ALSA]
1978 snd-usb-audio= [HW,ALSA,USB]
1980 snd-via82xx= [HW,ALSA]
1982 snd-virmidi= [HW,ALSA]
1984 snd-wavefront= [HW,ALSA]
1986 snd-ymfpci= [HW,ALSA]
1988 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1989 See Documentation/sonypi.txt
1991 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1992 See Documentation/specialix.txt.
1994 spia_io_base= [HW,MTD]
1995 spia_fio_base=
1996 spia_pedr=
1997 spia_peddr=
1999 sscape= [HW,OSS]
2000 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2002 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2003 See Documentation/scsi/st.txt.
2005 sti= [PARISC,HW]
2006 Format: <num>
2007 Set the STI (builtin display/keyboard on the HP-PARISC
2008 machines) console (graphic card) which should be used
2009 as the initial boot-console.
2010 See also comment in drivers/video/console/sticore.c.
2012 sti_font= [HW]
2013 See comment in drivers/video/console/sticore.c.
2015 stifb= [HW]
2016 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2018 sunrpc.pool_mode=
2019 [NFS]
2020 Control how the NFS server code allocates CPUs to
2021 service thread pools. Depending on how many NICs
2022 you have and where their interrupts are bound, this
2023 option will affect which CPUs will do NFS serving.
2024 Note: this parameter cannot be changed while the
2025 NFS server is running.
2027 auto the server chooses an appropriate mode
2028 automatically using heuristics
2029 global a single global pool contains all CPUs
2030 percpu one pool for each CPU
2031 pernode one pool for each NUMA node (equivalent
2032 to global on non-NUMA machines)
2034 swiotlb= [IA-64] Number of I/O TLB slabs
2036 switches= [HW,M68k]
2038 sym53c416= [HW,SCSI]
2039 See header of drivers/scsi/sym53c416.c.
2041 sysrq_always_enabled
2042 [KNL]
2043 Ignore sysrq setting - this boot parameter will
2044 neutralize any effect of /proc/sys/kernel/sysrq.
2045 Useful for debugging.
2047 t128= [HW,SCSI]
2048 See header of drivers/scsi/t128.c.
2050 tdfx= [HW,DRM]
2052 thash_entries= [KNL,NET]
2053 Set number of hash buckets for TCP connection
2055 thermal.act= [HW,ACPI]
2056 -1: disable all active trip points in all thermal zones
2057 <degrees C>: override all lowest active trip points
2059 thermal.crt= [HW,ACPI]
2060 -1: disable all critical trip points in all thermal zones
2061 <degrees C>: lower all critical trip points
2063 thermal.nocrt= [HW,ACPI]
2064 Set to disable actions on ACPI thermal zone
2065 critical and hot trip points.
2067 thermal.off= [HW,ACPI]
2068 1: disable ACPI thermal control
2070 thermal.psv= [HW,ACPI]
2071 -1: disable all passive trip points
2072 <degrees C>: override all passive trip points to this value
2074 thermal.tzp= [HW,ACPI]
2075 Specify global default ACPI thermal zone polling rate
2076 <deci-seconds>: poll all this frequency
2077 0: no polling (default)
2079 tipar.timeout= [HW,PPT]
2080 Set communications timeout in tenths of a second
2081 (default 15).
2083 tipar.delay= [HW,PPT]
2084 Set inter-bit delay in microseconds (default 10).
2086 tmscsim= [HW,SCSI]
2087 See comment before function dc390_setup() in
2088 drivers/scsi/tmscsim.c.
2090 tp720= [HW,PS2]
2092 trix= [HW,OSS] MediaTrix AudioTrix Pro
2093 Format:
2094 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2096 turbografx.map[2|3]= [HW,JOY]
2097 TurboGraFX parallel port interface
2098 Format:
2099 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2100 See also Documentation/input/joystick-parport.txt
2102 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2103 See header of drivers/scsi/u14-34f.c.
2105 uart401= [HW,OSS]
2106 Format: <io>,<irq>
2108 uart6850= [HW,OSS]
2109 Format: <io>,<irq>
2111 uhci-hcd.ignore_oc=
2112 [USB] Ignore overcurrent events (default N).
2113 Some badly-designed motherboards generate lots of
2114 bogus events, for ports that aren't wired to
2115 anything. Set this parameter to avoid log spamming.
2116 Note that genuine overcurrent events won't be
2117 reported either.
2119 usbcore.autosuspend=
2120 [USB] The autosuspend time delay (in seconds) used
2121 for newly-detected USB devices (default 2). This
2122 is the time required before an idle device will be
2123 autosuspended. Devices for which the delay is set
2124 to a negative value won't be autosuspended at all.
2126 usbhid.mousepoll=
2127 [USBHID] The interval which mice are to be polled at.
2129 vdso= [X86-32,SH,x86-64]
2130 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2131 vdso=1: enable VDSO (default)
2132 vdso=0: disable VDSO mapping
2134 vdso32= [X86-32,X86-64]
2135 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2136 vdso32=1: enable 32-bit VDSO (default)
2137 vdso32=0: disable 32-bit VDSO mapping
2139 vector= [IA-64,SMP]
2140 vector=percpu: enable percpu vector domain
2142 video= [FB] Frame buffer configuration
2143 See Documentation/fb/modedb.txt.
2145 vga= [BOOT,X86-32] Select a particular video mode
2146 See Documentation/i386/boot.txt and
2147 Documentation/svga.txt.
2148 Use vga=ask for menu.
2149 This is actually a boot loader parameter; the value is
2150 passed to the kernel using a special protocol.
2152 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2153 size of <nn>. This can be used to increase the
2154 minimum size (128MB on x86). It can also be used to
2155 decrease the size and leave more room for directly
2156 mapped kernel RAM.
2158 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2159 Format: <command>
2161 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2162 Format: <command>
2164 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2165 Format: <command>
2167 waveartist= [HW,OSS]
2168 Format: <io>,<irq>,<dma>,<dma2>
2170 wd33c93= [HW,SCSI]
2171 See header of drivers/scsi/wd33c93.c.
2173 wd7000= [HW,SCSI]
2174 See header of drivers/scsi/wd7000.c.
2176 wdt= [WDT] Watchdog
2177 See Documentation/watchdog/wdt.txt.
2179 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2180 xd_geo= See header of drivers/block/xd.c.
2182 xirc2ps_cs= [NET,PCMCIA]
2183 Format:
2184 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2186 norandmaps Don't use address space randomization
2187 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2189 ______________________________________________________________________
2191 TODO:
2193 Add documentation for ALSA options.
2194 Add more DRM drivers.