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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 See also Documentation/power/pm.txt, pci=noacpi
143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
147 default: 0
149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode, s3_beep, old_ordering }
151 See Documentation/power/video.txt for s3_bios and s3_mode.
152 s3_beep is for debugging; it makes the PC's speaker beep
153 as soon as the kernel's real-mode entry point is called.
154 old_ordering causes the ACPI 1.0 ordering of the _PTS
155 control method, wrt putting devices into low power
156 states, to be enforced (the ACPI 2.0 ordering of _PTS is
157 used by default).
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_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
179 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
180 Format: To spoof as Windows 98: ="Microsoft Windows"
182 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
183 acpi_osi="string1" # add string1 -- only one string
184 acpi_osi="!string2" # remove built-in string2
185 acpi_osi= # disable all strings
187 acpi_serialize [HW,ACPI] force serialization of AML methods
189 acpi_skip_timer_override [HW,ACPI]
190 Recognize and ignore IRQ0/pin2 Interrupt Override.
191 For broken nForce2 BIOS resulting in XT-PIC timer.
192 acpi_use_timer_override [HW,ACPI}
193 Use timer override. For some broken Nvidia NF5 boards
194 that require a timer override, but don't have
195 HPET
197 acpi.debug_layer= [HW,ACPI]
198 Format: <int>
199 Each bit of the <int> indicates an ACPI debug layer,
200 1: enable, 0: disable. It is useful for boot time
201 debugging. After system has booted up, it can be set
202 via /sys/module/acpi/parameters/debug_layer.
203 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
204 Available bits (add the numbers together) to enable debug output
205 for specific parts of the ACPI subsystem:
206 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
207 0x10 namespace 0x20 parser 0x40 dispatcher
208 0x80 executer 0x100 resources 0x200 acpica debugger
209 0x400 os services 0x800 acpica disassembler.
210 The number can be in decimal or prefixed with 0x in hex.
211 Warning: Many of these options can produce a lot of
212 output and make your system unusable. Be very careful.
214 acpi.debug_level= [HW,ACPI]
215 Format: <int>
216 Each bit of the <int> indicates an ACPI debug level,
217 1: enable, 0: disable. It is useful for boot time
218 debugging. After system has booted up, it can be set
219 via /sys/module/acpi/parameters/debug_level.
220 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
221 Available bits (add the numbers together) to enable different
222 debug output levels of the ACPI subsystem:
223 0x01 error 0x02 warn 0x04 init 0x08 debug object
224 0x10 info 0x20 init names 0x40 parse 0x80 load
225 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
226 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
227 0x10000 resources 0x20000 user requests 0x40000 package.
228 The number can be in decimal or prefixed with 0x in hex.
229 Warning: Many of these options can produce a lot of
230 output and make your system unusable. Be very careful.
232 acpi_pm_good [X86-32,X86-64]
233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
237 agp= [AGP]
238 { off | try_unsupported }
239 off: disable AGP support
240 try_unsupported: try to drive unsupported chipsets
241 (may crash computer or cause data corruption)
243 enable_timer_pin_1 [i386,x86-64]
244 Enable PIN 1 of APIC timer
245 Can be useful to work around chipset bugs
246 (in particular on some ATI chipsets).
247 The kernel tries to set a reasonable default.
249 disable_timer_pin_1 [i386,x86-64]
250 Disable PIN 1 of APIC timer
251 Can be useful to work around chipset bugs.
253 ad1848= [HW,OSS]
254 Format: <io>,<irq>,<dma>,<dma2>,<type>
256 advansys= [HW,SCSI]
257 See header of drivers/scsi/advansys.c.
259 advwdt= [HW,WDT] Advantech WDT
260 Format: <iostart>,<iostop>
262 aedsp16= [HW,OSS] Audio Excel DSP 16
263 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
264 See also header of sound/oss/aedsp16.c.
266 aha152x= [HW,SCSI]
267 See Documentation/scsi/aha152x.txt.
269 aha1542= [HW,SCSI]
270 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
272 aic7xxx= [HW,SCSI]
273 See Documentation/scsi/aic7xxx.txt.
275 aic79xx= [HW,SCSI]
276 See Documentation/scsi/aic79xx.txt.
278 amijoy.map= [HW,JOY] Amiga joystick support
279 Map of devices attached to JOY0DAT and JOY1DAT
280 Format: <a>,<b>
281 See also Documentation/kernel/input/joystick.txt
283 analog.map= [HW,JOY] Analog joystick and gamepad support
284 Specifies type or capabilities of an analog joystick
285 connected to one of 16 gameports
286 Format: <type1>,<type2>,..<type16>
288 apc= [HW,SPARC]
289 Power management functions (SPARCstation-4/5 + deriv.)
290 Format: noidle
291 Disable APC CPU standby support. SPARCstation-Fox does
292 not play well with APC CPU idle - disable it if you have
293 APC and your system crashes randomly.
295 apic= [APIC,i386] Advanced Programmable Interrupt Controller
296 Change the output verbosity whilst booting
297 Format: { quiet (default) | verbose | debug }
298 Change the amount of debugging information output
299 when initialising the APIC and IO-APIC components.
301 apm= [APM] Advanced Power Management
302 See header of arch/i386/kernel/apm.c.
304 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
305 Format: <io>,<irq>,<nodeID>
307 ataflop= [HW,M68k]
309 atarimouse= [HW,MOUSE] Atari Mouse
311 atascsi= [HW,SCSI] Atari SCSI
313 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
314 EzKey and similar keyboards
316 atkbd.reset= [HW] Reset keyboard during initialization
318 atkbd.set= [HW] Select keyboard code set
319 Format: <int> (2 = AT (default), 3 = PS/2)
321 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
322 keyboards
324 atkbd.softraw= [HW] Choose between synthetic and real raw mode
325 Format: <bool> (0 = real, 1 = synthetic (default))
327 atkbd.softrepeat= [HW]
328 Use software keyboard repeat
330 autotest [IA64]
332 baycom_epp= [HW,AX25]
333 Format: <io>,<mode>
335 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
336 Format: <io>,<mode>
337 See header of drivers/net/hamradio/baycom_par.c.
339 baycom_ser_fdx= [HW,AX25]
340 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
341 Format: <io>,<irq>,<mode>[,<baud>]
342 See header of drivers/net/hamradio/baycom_ser_fdx.c.
344 baycom_ser_hdx= [HW,AX25]
345 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
346 Format: <io>,<irq>,<mode>
347 See header of drivers/net/hamradio/baycom_ser_hdx.c.
349 boot_delay= Milliseconds to delay each printk during boot.
350 Values larger than 10 seconds (10000) are changed to
351 no delay (0).
352 Format: integer
354 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
355 bttv.radio= Most important insmod options are available as
356 kernel args too.
357 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
358 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
360 BusLogic= [HW,SCSI]
361 See drivers/scsi/BusLogic.c, comment before function
362 BusLogic_ParseDriverOptions().
364 c101= [NET] Moxa C101 synchronous serial card
366 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
367 Sometimes CPU hardware bugs make them report the cache
368 size incorrectly. The kernel will attempt work arounds
369 to fix known problems, but for some CPUs it is not
370 possible to determine what the correct size should be.
371 This option provides an override for these situations.
373 security= [SECURITY] Choose a security module to enable at boot.
374 If this boot parameter is not specified, only the first
375 security module asking for security registration will be
376 loaded. An invalid security module name will be treated
377 as if no module has been chosen.
379 capability.disable=
380 [SECURITY] Disable capabilities. This would normally
381 be used only if an alternative security model is to be
382 configured. Potentially dangerous and should only be
383 used if you are entirely sure of the consequences.
385 ccw_timeout_log [S390]
386 See Documentation/s390/CommonIO for details.
388 cgroup_disable= [KNL] Disable a particular controller
389 Format: {name of the controller(s) to disable}
390 {Currently supported controllers - "memory"}
392 checkreqprot [SELINUX] Set initial checkreqprot flag value.
393 Format: { "0" | "1" }
394 See security/selinux/Kconfig help text.
395 0 -- check protection applied by kernel (includes
396 any implied execute protection).
397 1 -- check protection requested by application.
398 Default value is set via a kernel config option.
399 Value can be changed at runtime via
400 /selinux/checkreqprot.
402 cio_ignore= [S390]
403 See Documentation/s390/CommonIO for details.
405 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
406 [Deprecated]
407 Forces specified clocksource (if available) to be used
408 when calculating gettimeofday(). If specified
409 clocksource is not available, it defaults to PIT.
410 Format: { pit | tsc | cyclone | pmtmr }
412 clocksource= [GENERIC_TIME] Override the default clocksource
413 Format: <string>
414 Override the default clocksource and use the clocksource
415 with the name specified.
416 Some clocksource names to choose from, depending on
417 the platform:
418 [all] jiffies (this is the base, fallback clocksource)
419 [ACPI] acpi_pm
420 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
421 pxa_timer,timer3,32k_counter,timer0_1
422 [AVR32] avr32
423 [X86-32] pit,hpet,tsc,vmi-timer;
424 scx200_hrt on Geode; cyclone on IBM x440
425 [MIPS] MIPS
426 [PARISC] cr16
427 [S390] tod
428 [SH] SuperH
429 [SPARC64] tick
430 [X86-64] hpet,tsc
432 clearcpuid=BITNUM [X86]
433 Disable CPUID feature X for the kernel. See
434 include/asm-x86/cpufeature.h for the valid bit numbers.
435 Note the Linux specific bits are not necessarily
436 stable over kernel options, but the vendor specific
437 ones should be.
438 Also note that user programs calling CPUID directly
439 or using the feature without checking anything
440 will still see it. This just prevents it from
441 being used by the kernel or shown in /proc/cpuinfo.
442 Also note the kernel might malfunction if you disable
443 some critical bits.
445 code_bytes [IA32/X86_64] How many bytes of object code to print
446 in an oops report.
447 Range: 0 - 8192
448 Default: 64
450 disable_8254_timer
451 enable_8254_timer
452 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
453 over the 8254 in addition to over the IO-APIC. The
454 kernel tries to set a sensible default.
456 hpet= [X86-32,HPET] option to control HPET usage
457 Format: { enable (default) | disable | force }
458 disable: disable HPET and use PIT instead
459 force: allow force enabled of undocumented chips (ICH4,
460 VIA, nVidia)
462 com20020= [HW,NET] ARCnet - COM20020 chipset
463 Format:
464 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
466 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
467 Format: <io>[,<irq>]
469 com90xx= [HW,NET]
470 ARCnet - COM90xx chipset (memory-mapped buffers)
471 Format: <io>[,<irq>[,<memstart>]]
473 condev= [HW,S390] console device
474 conmode=
476 console= [KNL] Output console device and options.
478 tty<n> Use the virtual console device <n>.
480 ttyS<n>[,options]
481 ttyUSB0[,options]
482 Use the specified serial port. The options are of
483 the form "bbbbpnf", where "bbbb" is the baud rate,
484 "p" is parity ("n", "o", or "e"), "n" is number of
485 bits, and "f" is flow control ("r" for RTS or
486 omit it). Default is "9600n8".
488 See Documentation/serial-console.txt for more
489 information. See
490 Documentation/networking/netconsole.txt for an
491 alternative.
493 uart[8250],io,<addr>[,options]
494 uart[8250],mmio,<addr>[,options]
495 Start an early, polled-mode console on the 8250/16550
496 UART at the specified I/O port or MMIO address,
497 switching to the matching ttyS device later. The
498 options are the same as for ttyS, above.
500 If the device connected to the port is not a TTY but a braille
501 device, prepend "brl," before the device type, for instance
502 console=brl,ttyS0
503 For now, only VisioBraille is supported.
505 earlycon= [KNL] Output early console device and options.
506 uart[8250],io,<addr>[,options]
507 uart[8250],mmio,<addr>[,options]
508 Start an early, polled-mode console on the 8250/16550
509 UART at the specified I/O port or MMIO address.
510 The options are the same as for ttyS, above.
512 no_console_suspend
513 [HW] Never suspend the console
514 Disable suspending of consoles during suspend and
515 hibernate operations. Once disabled, debugging
516 messages can reach various consoles while the rest
517 of the system is being put to sleep (ie, while
518 debugging driver suspend/resume hooks). This may
519 not work reliably with all consoles, but is known
520 to work with serial and VGA consoles.
522 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
523 Format:
524 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
526 crashkernel=nn[KMG]@ss[KMG]
527 [KNL] Reserve a chunk of physical memory to
528 hold a kernel to switch to with kexec on panic.
530 crashkernel=range1:size1[,range2:size2,...][@offset]
531 [KNL] Same as above, but depends on the memory
532 in the running system. The syntax of range is
533 start-[end] where start and end are both
534 a memory unit (amount[KMG]). See also
535 Documentation/kdump/kdump.txt for a example.
537 cs4232= [HW,OSS]
538 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
540 cs89x0_dma= [HW,NET]
541 Format: <dma>
543 cs89x0_media= [HW,NET]
544 Format: { rj45 | aui | bnc }
546 dasd= [HW,NET]
547 See header of drivers/s390/block/dasd_devmap.c.
549 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
550 (one device per port)
551 Format: <port#>,<type>
552 See also Documentation/input/joystick-parport.txt
554 debug [KNL] Enable kernel debugging (events log level).
556 debug_locks_verbose=
557 [KNL] verbose self-tests
558 Format=<0|1>
559 Print debugging info while doing the locking API
560 self-tests.
561 We default to 0 (no extra messages), setting it to
562 1 will print _a lot_ more information - normally
563 only useful to kernel developers.
565 debug_objects [KNL] Enable object debugging
567 decnet.addr= [HW,NET]
568 Format: <area>[,<node>]
569 See also Documentation/networking/decnet.txt.
571 vt.default_blu= [VT]
572 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
573 Change the default blue palette of the console.
574 This is a 16-member array composed of values
575 ranging from 0-255.
577 vt.default_grn= [VT]
578 Format: <green0>,<green1>,<green2>,...,<green15>
579 Change the default green palette of the console.
580 This is a 16-member array composed of values
581 ranging from 0-255.
583 vt.default_red= [VT]
584 Format: <red0>,<red1>,<red2>,...,<red15>
585 Change the default red palette of the console.
586 This is a 16-member array composed of values
587 ranging from 0-255.
589 vt.default_utf8=
590 [VT]
591 Format=<0|1>
592 Set system-wide default UTF-8 mode for all tty's.
593 Default is 1, i.e. UTF-8 mode is enabled for all
594 newly opened terminals.
596 dhash_entries= [KNL]
597 Set number of hash buckets for dentry cache.
599 digi= [HW,SERIAL]
600 IO parameters + enable/disable command.
602 digiepca= [HW,SERIAL]
603 See drivers/char/README.epca and
604 Documentation/digiepca.txt.
606 disable_mtrr_trim [X86, Intel and AMD only]
607 By default the kernel will trim any uncacheable
608 memory out of your available memory pool based on
609 MTRR settings. This parameter disables that behavior,
610 possibly causing your machine to run very slowly.
612 dmasound= [HW,OSS] Sound subsystem buffers
614 dscc4.setup= [NET]
616 dtc3181e= [HW,SCSI]
618 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
619 earlyprintk=vga
620 earlyprintk=serial[,ttySn[,baudrate]]
622 Append ",keep" to not disable it when the real console
623 takes over.
625 Only vga or serial at a time, not both.
627 Currently only ttyS0 and ttyS1 are supported.
629 Interaction with the standard serial driver is not
630 very good.
632 The VGA output is eventually overwritten by the real
633 console.
635 eata= [HW,SCSI]
637 edd= [EDD]
638 Format: {"off" | "on" | "skip[mbr]"}
640 eisa_irq_edge= [PARISC,HW]
641 See header of drivers/parisc/eisa.c.
643 elanfreq= [X86-32]
644 See comment before function elanfreq_setup() in
645 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
647 elevator= [IOSCHED]
648 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
649 See Documentation/block/as-iosched.txt and
650 Documentation/block/deadline-iosched.txt for details.
652 elfcorehdr= [X86-32, X86_64]
653 Specifies physical address of start of kernel core
654 image elf header. Generally kexec loader will
655 pass this option to capture kernel.
656 See Documentation/kdump/kdump.txt for details.
658 enforcing [SELINUX] Set initial enforcing status.
659 Format: {"0" | "1"}
660 See security/selinux/Kconfig help text.
661 0 -- permissive (log only, no denials).
662 1 -- enforcing (deny and log).
663 Default value is 0.
664 Value can be changed at runtime via /selinux/enforce.
666 es1371= [HW,OSS]
667 Format: <spdif>,[<nomix>,[<amplifier>]]
668 See also header of sound/oss/es1371.c.
670 ether= [HW,NET] Ethernet cards parameters
671 This option is obsoleted by the "netdev=" option, which
672 has equivalent usage. See its documentation for details.
674 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
675 Format: <io>[,<irq>]
677 failslab=
678 fail_page_alloc=
679 fail_make_request=[KNL]
680 General fault injection mechanism.
681 Format: <interval>,<probability>,<space>,<times>
682 See also /Documentation/fault-injection/.
684 fd_mcs= [HW,SCSI]
685 See header of drivers/scsi/fd_mcs.c.
687 fdomain= [HW,SCSI]
688 See header of drivers/scsi/fdomain.c.
690 floppy= [HW]
691 See Documentation/floppy.txt.
693 force_pal_cache_flush
694 [IA-64] Avoid check_sal_cache_flush which may hang on
695 buggy SAL_CACHE_FLUSH implementations. Using this
696 parameter will force ia64_sal_cache_flush to call
697 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
699 gamecon.map[2|3]=
700 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
701 support via parallel port (up to 5 devices per port)
702 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
703 See also Documentation/input/joystick-parport.txt
705 gamma= [HW,DRM]
707 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
708 Format: off | on
709 default: on
711 gdth= [HW,SCSI]
712 See header of drivers/scsi/gdth.c.
714 gpt [EFI] Forces disk with valid GPT signature but
715 invalid Protective MBR to be treated as GPT.
717 gvp11= [HW,SCSI]
719 hashdist= [KNL,NUMA] Large hashes allocated during boot
720 are distributed across NUMA nodes. Defaults on
721 for IA-64, off otherwise.
722 Format: 0 | 1 (for off | on)
724 hcl= [IA-64] SGI's Hardware Graph compatibility layer
726 hd= [EIDE] (E)IDE hard drive subsystem geometry
727 Format: <cyl>,<head>,<sect>
729 hd?= [HW] (E)IDE subsystem
730 hd?lun= See Documentation/ide/ide.txt.
732 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
733 size of <nn>. This works even on boxes that have no
734 highmem otherwise. This also works to reduce highmem
735 size on bigger boxes.
737 highres= [KNL] Enable/disable high resolution timer mode.
738 Valid parameters: "on", "off"
739 Default: "on"
741 hisax= [HW,ISDN]
742 See Documentation/isdn/README.HiSax.
744 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
745 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
747 i8042.direct [HW] Put keyboard port into non-translated mode
748 i8042.dumbkbd [HW] Pretend that controller can only read data from
749 keyboard and cannot control its state
750 (Don't attempt to blink the leds)
751 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
752 i8042.nokbd [HW] Don't check/create keyboard port
753 i8042.noloop [HW] Disable the AUX Loopback command while probing
754 for the AUX port
755 i8042.nomux [HW] Don't check presence of an active multiplexing
756 controller
757 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
758 controllers
759 i8042.panicblink=
760 [HW] Frequency with which keyboard LEDs should blink
761 when kernel panics (default is 0.5 sec)
762 i8042.reset [HW] Reset the controller during init and cleanup
763 i8042.unlock [HW] Unlock (ignore) the keylock
765 i810= [HW,DRM]
767 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
768 indicates that the driver is running on unsupported
769 hardware.
770 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
771 does not match list of supported models.
772 i8k.power_status
773 [HW] Report power status in /proc/i8k
774 (disabled by default)
775 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
776 capability is set.
778 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
779 See Documentation/mca.txt.
781 icn= [HW,ISDN]
782 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
784 ide= [HW] (E)IDE subsystem
785 Format: ide=nodma or ide=doubler
786 See Documentation/ide/ide.txt.
788 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
789 See Documentation/ide/ide.txt.
791 idle= [X86]
792 Format: idle=poll or idle=mwait
793 Poll forces a polling idle loop that can slightly improves the performance
794 of waking up a idle CPU, but will use a lot of power and make the system
795 run hot. Not recommended.
796 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
797 to not use it because it doesn't save as much power as a normal idle
798 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
799 as idle=poll.
801 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
802 Claim all unknown PCI IDE storage controllers.
804 ignore_loglevel [KNL]
805 Ignore loglevel setting - this will print /all/
806 kernel messages to the console. Useful for debugging.
808 ihash_entries= [KNL]
809 Set number of hash buckets for inode cache.
811 in2000= [HW,SCSI]
812 See header of drivers/scsi/in2000.c.
814 init= [KNL]
815 Format: <full_path>
816 Run specified binary instead of /sbin/init as init
817 process.
819 initcall_debug [KNL] Trace initcalls as they are executed. Useful
820 for working out where the kernel is dying during
821 startup.
823 initrd= [BOOT] Specify the location of the initial ramdisk
825 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
826 Format: <irq>
828 inttest= [IA64]
830 iommu= [x86]
831 off
832 force
833 noforce
834 biomerge
835 panic
836 nopanic
837 merge
838 nomerge
839 forcesac
840 soft
843 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
844 off
845 Disable intel iommu driver.
846 igfx_off [Default Off]
847 By default, gfx is mapped as normal device. If a gfx
848 device has a dedicated DMAR unit, the DMAR unit is
849 bypassed by not enabling DMAR with this option. In
850 this case, gfx device will use physical address for
851 DMA.
852 forcedac [x86_64]
853 With this option iommu will not optimize to look
854 for io virtual address below 32 bit forcing dual
855 address cycle on pci bus for cards supporting greater
856 than 32 bit addressing. The default is to look
857 for translation below 32 bit and if not available
858 then look in the higher range.
859 strict [Default Off]
860 With this option on every unmap_single operation will
861 result in a hardware IOTLB flush operation as opposed
862 to batching them for performance.
864 io_delay= [X86-32,X86-64] I/O delay method
865 0x80
866 Standard port 0x80 based delay
867 0xed
868 Alternate port 0xed based delay (needed on some systems)
869 udelay
870 Simple two microseconds delay
871 none
872 No delay
874 io7= [HW] IO7 for Marvel based alpha systems
875 See comment before marvel_specify_io7 in
876 arch/alpha/kernel/core_marvel.c.
878 ip= [IP_PNP]
879 See Documentation/filesystems/nfsroot.txt.
881 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
882 See comment before ip2_setup() in
883 drivers/char/ip2/ip2base.c.
885 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
886 See header of drivers/scsi/ips.c.
888 ports= [IP_VS_FTP] IPVS ftp helper module
889 Default is 21.
890 Up to 8 (IP_VS_APP_MAX_PORTS) ports
891 may be specified.
892 Format: <port>,<port>....
894 irqfixup [HW]
895 When an interrupt is not handled search all handlers
896 for it. Intended to get systems with badly broken
897 firmware running.
899 irqpoll [HW]
900 When an interrupt is not handled search all handlers
901 for it. Also check all handlers each timer
902 interrupt. Intended to get systems with badly broken
903 firmware running.
905 isapnp= [ISAPNP]
906 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
908 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
909 Format:
910 <cpu number>,...,<cpu number>
911 or
912 <cpu number>-<cpu number> (must be a positive range in ascending order)
913 or a mixture
914 <cpu number>,...,<cpu number>-<cpu number>
915 This option can be used to specify one or more CPUs
916 to isolate from the general SMP balancing and scheduling
917 algorithms. The only way to move a process onto or off
918 an "isolated" CPU is via the CPU affinity syscalls.
919 <cpu number> begins at 0 and the maximum value is
920 "number of CPUs in system - 1".
922 This option is the preferred way to isolate CPUs. The
923 alternative -- manually setting the CPU mask of all
924 tasks in the system -- can cause problems and
925 suboptimal load balancer performance.
927 iucv= [HW,NET]
929 js= [HW,JOY] Analog joystick
930 See Documentation/input/joystick.txt.
932 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
933 specifies the amount of memory usable by the kernel
934 for non-movable allocations. The requested amount is
935 spread evenly throughout all nodes in the system. The
936 remaining memory in each node is used for Movable
937 pages. In the event, a node is too small to have both
938 kernelcore and Movable pages, kernelcore pages will
939 take priority and other nodes will have a larger number
940 of kernelcore pages. The Movable zone is used for the
941 allocation of pages that may be reclaimed or moved
942 by the page migration subsystem. This means that
943 HugeTLB pages may not be allocated from this zone.
944 Note that allocations like PTEs-from-HighMem still
945 use the HighMem zone if it exists, and the Normal
946 zone if it does not.
948 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
949 is similar to kernelcore except it specifies the
950 amount of memory used for migratable allocations.
951 If both kernelcore and movablecore is specified,
952 then kernelcore will be at *least* the specified
953 value but may be more. If movablecore on its own
954 is specified, the administrator must be careful
955 that the amount of memory usable for all allocations
956 is not too small.
958 keepinitrd [HW,ARM]
960 kstack=N [X86-32,X86-64] Print N words from the kernel stack
961 in oops dumps.
963 kgdboc= [HW] kgdb over consoles.
964 Requires a tty driver that supports console polling.
965 (only serial suported for now)
966 Format: <serial_device>[,baud]
968 l2cr= [PPC]
970 l3cr= [PPC]
972 lapic [X86-32,APIC] Enable the local APIC even if BIOS
973 disabled it.
975 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
976 C2 power state.
978 libata.dma= [LIBATA] DMA control
979 libata.dma=0 Disable all PATA and SATA DMA
980 libata.dma=1 PATA and SATA Disk DMA only
981 libata.dma=2 ATAPI (CDROM) DMA only
982 libata.dma=4 Compact Flash DMA only
983 Combinations also work, so libata.dma=3 enables DMA
984 for disks and CDROMs, but not CFs.
986 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
987 when set.
988 Format: <int>
990 libata.force= [LIBATA] Force configurations. The format is comma
991 separated list of "[ID:]VAL" where ID is
992 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
993 matching port, link or device. Basically, it matches
994 the ATA ID string printed on console by libata. If
995 the whole ID part is omitted, the last PORT and DEVICE
996 values are used. If ID hasn't been specified yet, the
997 configuration applies to all ports, links and devices.
999 If only DEVICE is omitted, the parameter applies to
1000 the port and all links and devices behind it. DEVICE
1001 number of 0 either selects the first device or the
1002 first fan-out link behind PMP device. It does not
1003 select the host link. DEVICE number of 15 selects the
1004 host link and device attached to it.
1006 The VAL specifies the configuration to force. As long
1007 as there's no ambiguity shortcut notation is allowed.
1008 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1009 The following configurations can be forced.
1011 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1012 Any ID with matching PORT is used.
1014 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1016 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1017 udma[/][16,25,33,44,66,100,133] notation is also
1018 allowed.
1020 * [no]ncq: Turn on or off NCQ.
1022 If there are multiple matching configurations changing
1023 the same attribute, the last one is used.
1025 load_ramdisk= [RAM] List of ramdisks to load from floppy
1026 See Documentation/ramdisk.txt.
1028 lockd.nlm_grace_period=P [NFS] Assign grace period.
1029 Format: <integer>
1031 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1032 Format: <integer>
1034 lockd.nlm_timeout=T [NFS] Assign timeout value.
1035 Format: <integer>
1037 lockd.nlm_udpport=M [NFS] Assign UDP port.
1038 Format: <integer>
1040 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1041 Format: <irq>
1043 loglevel= All Kernel Messages with a loglevel smaller than the
1044 console loglevel will be printed to the console. It can
1045 also be changed with klogd or other programs. The
1046 loglevels are defined as follows:
1048 0 (KERN_EMERG) system is unusable
1049 1 (KERN_ALERT) action must be taken immediately
1050 2 (KERN_CRIT) critical conditions
1051 3 (KERN_ERR) error conditions
1052 4 (KERN_WARNING) warning conditions
1053 5 (KERN_NOTICE) normal but significant condition
1054 6 (KERN_INFO) informational
1055 7 (KERN_DEBUG) debug-level messages
1057 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1058 Format: { n | nk | nM }
1059 n must be a power of two. The default size
1060 is set in the kernel config file.
1062 logo.nologo [FB] Disables display of the built-in Linux logo.
1063 This may be used to provide more screen space for
1064 kernel log messages and is useful when debugging
1065 kernel boot problems.
1067 lp=0 [LP] Specify parallel ports to use, e.g,
1068 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1069 lp=reset first parallel port). 'lp=0' disables the
1070 lp=auto printer driver. 'lp=reset' (which can be
1071 specified in addition to the ports) causes
1072 attached printers to be reset. Using
1073 lp=port1,port2,... specifies the parallel ports
1074 to associate lp devices with, starting with
1075 lp0. A port specification may be 'none' to skip
1076 that lp device, or a parport name such as
1077 'parport0'. Specifying 'lp=auto' instead of a
1078 port specification list means that device IDs
1079 from each port should be examined, to see if
1080 an IEEE 1284-compliant printer is attached; if
1081 so, the driver will manage that printer.
1082 See also header of drivers/char/lp.c.
1084 lpj=n [KNL]
1085 Sets loops_per_jiffy to given constant, thus avoiding
1086 time-consuming boot-time autodetection (up to 250 ms per
1087 CPU). 0 enables autodetection (default). To determine
1088 the correct value for your kernel, boot with normal
1089 autodetection and see what value is printed. Note that
1090 on SMP systems the preset will be applied to all CPUs,
1091 which is likely to cause problems if your CPUs need
1092 significantly divergent settings. An incorrect value
1093 will cause delays in the kernel to be wrong, leading to
1094 unpredictable I/O errors and other breakage. Although
1095 unlikely, in the extreme case this might damage your
1096 hardware.
1098 ltpc= [NET]
1099 Format: <io>,<irq>,<dma>
1101 mac5380= [HW,SCSI] Format:
1102 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1104 machvec= [IA64] Force the use of a particular machine-vector
1105 (machvec) in a generic kernel.
1106 Example: machvec=hpzx1_swiotlb
1108 max_loop= [LOOP] Maximum number of loopback devices that can
1109 be mounted
1110 Format: <1-256>
1112 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1113 should make use of. maxcpus=n : n >= 0 limits the
1114 kernel to using 'n' processors. n=0 is a special case,
1115 it is equivalent to "nosmp", which also disables
1116 the IO APIC.
1118 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1119 equal to this physical address is ignored.
1121 max_luns= [SCSI] Maximum number of LUNs to probe.
1122 Should be between 1 and 2^32-1.
1124 max_report_luns=
1125 [SCSI] Maximum number of LUNs received.
1126 Should be between 1 and 16384.
1128 mcatest= [IA-64]
1130 mce [X86-32] Machine Check Exception
1132 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1134 md= [HW] RAID subsystems devices and level
1135 See Documentation/md.txt.
1137 mdacon= [MDA]
1138 Format: <first>,<last>
1139 Specifies range of consoles to be captured by the MDA.
1141 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1142 Amount of memory to be used when the kernel is not able
1143 to see the whole system memory or for test.
1144 [X86-32] Use together with memmap= to avoid physical
1145 address space collisions. Without memmap= PCI devices
1146 could be placed at addresses belonging to unused RAM.
1148 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1149 memory.
1151 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1152 E820 memory map, as specified by the user.
1153 Such memmap=exactmap lines can be constructed based on
1154 BIOS output or other requirements. See the memmap=nn@ss
1155 option description.
1157 memmap=nn[KMG]@ss[KMG]
1158 [KNL] Force usage of a specific region of memory
1159 Region of memory to be used, from ss to ss+nn.
1161 memmap=nn[KMG]#ss[KMG]
1162 [KNL,ACPI] Mark specific memory as ACPI data.
1163 Region of memory to be used, from ss to ss+nn.
1165 memmap=nn[KMG]$ss[KMG]
1166 [KNL,ACPI] Mark specific memory as reserved.
1167 Region of memory to be used, from ss to ss+nn.
1168 Example: Exclude memory from 0x18690000-0x1869ffff
1169 memmap=64K$0x18690000
1170 or
1171 memmap=0x10000$0x18690000
1173 memtest= [KNL,X86_64] Enable memtest
1174 Format: <integer>
1175 range: 0,4 : pattern number
1176 default : 0 <disable>
1178 meye.*= [HW] Set MotionEye Camera parameters
1179 See Documentation/video4linux/meye.txt.
1181 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1182 Multi-Function General Purpose Timers on AMD Geode
1183 platforms.
1185 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1186 the BIOS has incorrectly applied a workaround. TinyBIOS
1187 version 0.98 is known to be affected, 0.99 fixes the
1188 problem by letting the user disable the workaround.
1190 mga= [HW,DRM]
1192 mousedev.tap_time=
1193 [MOUSE] Maximum time between finger touching and
1194 leaving touchpad surface for touch to be considered
1195 a tap and be reported as a left button click (for
1196 touchpads working in absolute mode only).
1197 Format: <msecs>
1198 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1199 reporting absolute coordinates, such as tablets
1200 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1201 reporting absolute coordinates, such as tablets
1203 mpu401= [HW,OSS]
1204 Format: <io>,<irq>
1206 MTD_Partition= [MTD]
1207 Format: <name>,<region-number>,<size>,<offset>
1209 MTD_Region= [MTD] Format:
1210 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1212 mtdparts= [MTD]
1213 See drivers/mtd/cmdlinepart.c.
1215 mtouchusb.raw_coordinates=
1216 [HW] Make the MicroTouch USB driver use raw coordinates
1217 ('y', default) or cooked coordinates ('n')
1219 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1221 NCR_D700= [HW,SCSI]
1222 See header of drivers/scsi/NCR_D700.c.
1224 ncr5380= [HW,SCSI]
1226 ncr53c400= [HW,SCSI]
1228 ncr53c400a= [HW,SCSI]
1230 ncr53c406a= [HW,SCSI]
1232 ncr53c8xx= [HW,SCSI]
1234 netdev= [NET] Network devices parameters
1235 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1236 Note that mem_start is often overloaded to mean
1237 something different and driver-specific.
1238 This usage is only documented in each driver source
1239 file if at all.
1241 nfsaddrs= [NFS]
1242 See Documentation/filesystems/nfsroot.txt.
1244 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1245 See Documentation/filesystems/nfsroot.txt.
1247 nfs.callback_tcpport=
1248 [NFS] set the TCP port on which the NFSv4 callback
1249 channel should listen.
1251 nfs.idmap_cache_timeout=
1252 [NFS] set the maximum lifetime for idmapper cache
1253 entries.
1255 nfs.enable_ino64=
1256 [NFS] enable 64-bit inode numbers.
1257 If zero, the NFS client will fake up a 32-bit inode
1258 number for the readdir() and stat() syscalls instead
1259 of returning the full 64-bit number.
1260 The default is to return 64-bit inode numbers.
1262 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1263 when a NMI is triggered.
1264 Format: [state][,regs][,debounce][,die]
1266 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1268 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1269 emulation library even if a 387 maths coprocessor
1270 is present.
1272 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1273 caches in the slab allocator. Saves per-node memory,
1274 but will impact performance.
1276 noalign [KNL,ARM]
1278 noapic [SMP,APIC] Tells the kernel to not make use of any
1279 IOAPICs that may be present in the system.
1281 nobats [PPC] Do not use BATs for mapping kernel lowmem
1282 on "Classic" PPC cores.
1284 nocache [ARM]
1286 nodelayacct [KNL] Disable per-task delay accounting
1288 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1290 noefi [X86-32,X86-64] Disable EFI runtime services support.
1292 noexec [IA-64]
1294 noexec [X86-32,X86-64]
1295 On X86-32 available only on PAE configured kernels.
1296 noexec=on: enable non-executable mappings (default)
1297 noexec=off: disable non-executable mappings
1299 noexec32 [X86-64]
1300 This affects only 32-bit executables.
1301 noexec32=on: enable non-executable mappings (default)
1302 read doesn't imply executable mappings
1303 noexec32=off: disable non-executable mappings
1304 read implies executable mappings
1306 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1307 register save and restore. The kernel will only save
1308 legacy floating-point registers on task switch.
1310 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1312 nohlt [BUGS=ARM]
1314 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1315 instruction doesn't work correctly and not to
1316 use it.
1318 nohalt [IA-64] Tells the kernel not to use the power saving
1319 function PAL_HALT_LIGHT when idle. This increases
1320 power-consumption. On the positive side, it reduces
1321 interrupt wake-up latency, which may improve performance
1322 in certain environments such as networked servers or
1323 real-time systems.
1325 nohz= [KNL] Boottime enable/disable dynamic ticks
1326 Valid arguments: on, off
1327 Default: on
1329 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1331 noirqdebug [X86-32] Disables the code which attempts to detect and
1332 disable unhandled interrupt sources.
1334 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1335 broken timer IRQ sources.
1337 noisapnp [ISAPNP] Disables ISA PnP code.
1339 noinitrd [RAM] Tells the kernel not to load any configured
1340 initial RAM disk.
1342 nointroute [IA-64]
1344 nojitter [IA64] Disables jitter checking for ITC timers.
1346 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1348 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1350 noltlbs [PPC] Do not use large page/tlb entries for kernel
1351 lowmem mapping on PPC40x.
1353 nomca [IA-64] Disable machine check abort handling
1355 nomce [X86-32] Machine Check Exception
1357 nomfgpt [X86-32] Disable Multi-Function General Purpose
1358 Timer usage (for AMD Geode machines).
1360 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1362 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1363 with UP alternatives
1365 noresidual [PPC] Don't use residual data on PReP machines.
1367 noresume [SWSUSP] Disables resume and restores original swap
1368 space.
1370 no-scroll [VGA] Disables scrollback.
1371 This is required for the Braillex ib80-piezo Braille
1372 reader made by F.H. Papenmeier (Germany).
1374 nosbagart [IA-64]
1376 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1378 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1379 and disable the IO APIC. legacy for "maxcpus=0".
1381 nosoftlockup [KNL] Disable the soft-lockup detector.
1383 nosync [HW,M68K] Disables sync negotiation for all devices.
1385 notsc [BUGS=X86-32] Disable Time Stamp Counter
1387 nousb [USB] Disable the USB subsystem
1389 nowb [ARM]
1391 nptcg= [IA64] Override max number of concurrent global TLB
1392 purges which is reported from either PAL_VM_SUMMARY or
1393 SAL PALO.
1395 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1396 one of ['zone', 'node', 'default'] can be specified
1397 This can be set from sysctl after boot.
1398 See Documentation/sysctl/vm.txt for details.
1400 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1402 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1403 Rather than timing out after 20 ms if an EC
1404 command is not properly ACKed, override the length
1405 of the timeout. We have interrupts disabled while
1406 waiting for the ACK, so if this is set too high
1407 interrupts *may* be lost!
1409 opl3= [HW,OSS]
1410 Format: <io>
1412 oprofile.timer= [HW]
1413 Use timer interrupt instead of performance counters
1415 osst= [HW,SCSI] SCSI Tape Driver
1416 Format: <buffer_size>,<write_threshold>
1417 See also Documentation/scsi/st.txt.
1419 panic= [KNL] Kernel behaviour on panic
1420 Format: <timeout>
1422 parkbd.port= [HW] Parallel port number the keyboard adapter is
1423 connected to, default is 0.
1424 Format: <parport#>
1425 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1426 0 for XT, 1 for AT (default is AT).
1427 Format: <mode>
1429 parport= [HW,PPT] Specify parallel ports. 0 disables.
1430 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1431 Use 'auto' to force the driver to use any
1432 IRQ/DMA settings detected (the default is to
1433 ignore detected IRQ/DMA settings because of
1434 possible conflicts). You can specify the base
1435 address, IRQ, and DMA settings; IRQ and DMA
1436 should be numbers, or 'auto' (for using detected
1437 settings on that particular port), or 'nofifo'
1438 (to avoid using a FIFO even if it is detected).
1439 Parallel ports are assigned in the order they
1440 are specified on the command line, starting
1441 with parport0.
1443 parport_init_mode= [HW,PPT]
1444 Configure VIA parallel port to operate in
1445 a specific mode. This is necessary on Pegasos
1446 computer where firmware has no options for setting
1447 up parallel port mode and sets it to spp.
1448 Currently this function knows 686a and 8231 chips.
1449 Format: [spp|ps2|epp|ecp|ecpepp]
1451 pas2= [HW,OSS] Format:
1452 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1454 pas16= [HW,SCSI]
1455 See header of drivers/scsi/pas16.c.
1457 pause_on_oops=
1458 Halt all CPUs after the first oops has been printed for
1459 the specified number of seconds. This is to be used if
1460 your oopses keep scrolling off the screen.
1462 pcbit= [HW,ISDN]
1464 pcd. [PARIDE]
1465 See header of drivers/block/paride/pcd.c.
1466 See also Documentation/paride.txt.
1468 pci=option[,option...] [PCI] various PCI subsystem options:
1469 off [X86-32] don't probe for the PCI bus
1470 bios [X86-32] force use of PCI BIOS, don't access
1471 the hardware directly. Use this if your machine
1472 has a non-standard PCI host bridge.
1473 nobios [X86-32] disallow use of PCI BIOS, only direct
1474 hardware access methods are allowed. Use this
1475 if you experience crashes upon bootup and you
1476 suspect they are caused by the BIOS.
1477 conf1 [X86-32] Force use of PCI Configuration
1478 Mechanism 1.
1479 conf2 [X86-32] Force use of PCI Configuration
1480 Mechanism 2.
1481 noaer [PCIE] If the PCIEAER kernel config parameter is
1482 enabled, this kernel boot option can be used to
1483 disable the use of PCIE advanced error reporting.
1484 nodomains [PCI] Disable support for multiple PCI
1485 root domains (aka PCI segments, in ACPI-speak).
1486 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1487 Configuration
1488 nomsi [MSI] If the PCI_MSI kernel config parameter is
1489 enabled, this kernel boot option can be used to
1490 disable the use of MSI interrupts system-wide.
1491 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1492 routing table. These calls are known to be buggy
1493 on several machines and they hang the machine
1494 when used, but on other computers it's the only
1495 way to get the interrupt routing table. Try
1496 this option if the kernel is unable to allocate
1497 IRQs or discover secondary PCI buses on your
1498 motherboard.
1499 rom [X86-32] Assign address space to expansion ROMs.
1500 Use with caution as certain devices share
1501 address decoders between ROMs and other
1502 resources.
1503 norom [X86-32,X86_64] Do not assign address space to
1504 expansion ROMs that do not already have
1505 BIOS assigned address ranges.
1506 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1507 assigned automatically to PCI devices. You can
1508 make the kernel exclude IRQs of your ISA cards
1509 this way.
1510 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1511 of the PIRQ table (normally generated
1512 by the BIOS) if it is outside the
1513 F0000h-100000h range.
1514 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1515 useful if the kernel is unable to find your
1516 secondary buses and you want to tell it
1517 explicitly which ones they are.
1518 assign-busses [X86-32] Always assign all PCI bus
1519 numbers ourselves, overriding
1520 whatever the firmware may have done.
1521 usepirqmask [X86-32] Honor the possible IRQ mask stored
1522 in the BIOS $PIR table. This is needed on
1523 some systems with broken BIOSes, notably
1524 some HP Pavilion N5400 and Omnibook XE3
1525 notebooks. This will have no effect if ACPI
1526 IRQ routing is enabled.
1527 noacpi [X86-32] Do not use ACPI for IRQ routing
1528 or for PCI scanning.
1529 use_crs [X86-32] Use _CRS for PCI resource
1530 allocation.
1531 routeirq Do IRQ routing for all PCI devices.
1532 This is normally done in pci_enable_device(),
1533 so this option is a temporary workaround
1534 for broken drivers that don't call it.
1535 skip_isa_align [X86] do not align io start addr, so can
1536 handle more pci cards
1537 firmware [ARM] Do not re-enumerate the bus but instead
1538 just use the configuration from the
1539 bootloader. This is currently used on
1540 IXP2000 systems where the bus has to be
1541 configured a certain way for adjunct CPUs.
1542 noearly [X86] Don't do any early type 1 scanning.
1543 This might help on some broken boards which
1544 machine check when some devices' config space
1545 is read. But various workarounds are disabled
1546 and some IOMMU drivers will not work.
1547 bfsort Sort PCI devices into breadth-first order.
1548 This sorting is done to get a device
1549 order compatible with older (<= 2.4) kernels.
1550 nobfsort Don't sort PCI devices into breadth-first order.
1551 cbiosize=nn[KMG] The fixed amount of bus space which is
1552 reserved for the CardBus bridge's IO window.
1553 The default value is 256 bytes.
1554 cbmemsize=nn[KMG] The fixed amount of bus space which is
1555 reserved for the CardBus bridge's memory
1556 window. The default value is 64 megabytes.
1558 pcmv= [HW,PCMCIA] BadgePAD 4
1560 pd. [PARIDE]
1561 See Documentation/paride.txt.
1563 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1564 boot time.
1565 Format: { 0 | 1 }
1566 See arch/parisc/kernel/pdc_chassis.c
1568 pf. [PARIDE]
1569 See Documentation/paride.txt.
1571 pg. [PARIDE]
1572 See Documentation/paride.txt.
1574 pirq= [SMP,APIC] Manual mp-table setup
1575 See Documentation/i386/IO-APIC.txt.
1577 plip= [PPT,NET] Parallel port network link
1578 Format: { parport<nr> | timid | 0 }
1579 See also Documentation/parport.txt.
1581 pnpacpi= [ACPI]
1582 { off }
1584 pnpbios= [ISAPNP]
1585 { on | off | curr | res | no-curr | no-res }
1587 pnp_reserve_irq=
1588 [ISAPNP] Exclude IRQs for the autoconfiguration
1590 pnp_reserve_dma=
1591 [ISAPNP] Exclude DMAs for the autoconfiguration
1593 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1594 Ranges are in pairs (I/O port base and size).
1596 pnp_reserve_mem=
1597 [ISAPNP] Exclude memory regions for the
1598 autoconfiguration.
1599 Ranges are in pairs (memory base and size).
1601 print-fatal-signals=
1602 [KNL] debug: print fatal signals
1603 print-fatal-signals=1: print segfault info to
1604 the kernel console.
1605 default: off.
1607 printk.time= Show timing data prefixed to each printk message line
1608 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1610 profile= [KNL] Enable kernel profiling via /proc/profile
1611 Format: [schedule,]<number>
1612 Param: "schedule" - profile schedule points.
1613 Param: <number> - step/bucket size as a power of 2 for
1614 statistical time based profiling.
1615 Param: "sleep" - profile D-state sleeping (millisecs).
1616 Requires CONFIG_SCHEDSTATS
1617 Param: "kvm" - profile VM exits.
1619 processor.max_cstate= [HW,ACPI]
1620 Limit processor to maximum C-state
1621 max_cstate=9 overrides any DMI blacklist limit.
1623 processor.nocst [HW,ACPI]
1624 Ignore the _CST method to determine C-states,
1625 instead using the legacy FADT method
1627 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1628 before loading.
1629 See Documentation/ramdisk.txt.
1631 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1632 probe for; one of (bare|imps|exps|lifebook|any).
1633 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1634 per second.
1635 psmouse.resetafter= [HW,MOUSE]
1636 Try to reset the device after so many bad packets
1637 (0 = never).
1638 psmouse.resolution=
1639 [HW,MOUSE] Set desired mouse resolution, in dpi.
1640 psmouse.smartscroll=
1641 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1642 0 = disabled, 1 = enabled (default).
1644 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1645 Format:
1646 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1648 pt. [PARIDE]
1649 See Documentation/paride.txt.
1651 pty.legacy_count=
1652 [KNL] Number of legacy pty's. Overwrites compiled-in
1653 default number.
1655 quiet [KNL] Disable most log messages
1657 r128= [HW,DRM]
1659 raid= [HW,RAID]
1660 See Documentation/md.txt.
1662 ramdisk_blocksize= [RAM]
1663 See Documentation/ramdisk.txt.
1665 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1666 See Documentation/ramdisk.txt.
1668 rcupdate.blimit= [KNL,BOOT]
1669 Set maximum number of finished RCU callbacks to process
1670 in one batch.
1672 rcupdate.qhimark= [KNL,BOOT]
1673 Set threshold of queued
1674 RCU callbacks over which batch limiting is disabled.
1676 rcupdate.qlowmark= [KNL,BOOT]
1677 Set threshold of queued RCU callbacks below which
1678 batch limiting is re-enabled.
1680 rdinit= [KNL]
1681 Format: <full_path>
1682 Run specified binary instead of /init from the ramdisk,
1683 used for early userspace startup. See initrd.
1685 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1686 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1687 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1689 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1691 reservetop= [X86-32]
1692 Format: nn[KMG]
1693 Reserves a hole at the top of the kernel virtual
1694 address space.
1696 reset_devices [KNL] Force drivers to reset the underlying device
1697 during initialization.
1699 resume= [SWSUSP]
1700 Specify the partition device for software suspend
1702 resume_offset= [SWSUSP]
1703 Specify the offset from the beginning of the partition
1704 given by "resume=" at which the swap header is located,
1705 in <PAGE_SIZE> units (needed only for swap files).
1706 See Documentation/power/swsusp-and-swap-files.txt
1708 retain_initrd [RAM] Keep initrd memory after extraction
1710 rhash_entries= [KNL,NET]
1711 Set number of hash buckets for route cache
1713 riscom8= [HW,SERIAL]
1714 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1716 ro [KNL] Mount root device read-only on boot
1718 root= [KNL] Root filesystem
1720 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1721 mount the root filesystem
1723 rootflags= [KNL] Set root filesystem mount option string
1725 rootfstype= [KNL] Set root filesystem type
1727 rootwait [KNL] Wait (indefinitely) for root device to show up.
1728 Useful for devices that are detected asynchronously
1729 (e.g. USB and MMC devices).
1731 root_plug.vendor_id=
1732 [ROOTPLUG] Override the default vendor ID
1734 root_plug.product_id=
1735 [ROOTPLUG] Override the default product ID
1737 root_plug.debug=
1738 [ROOTPLUG] Enable debugging output
1740 rw [KNL] Mount root device read-write on boot
1742 S [KNL] Run init in single mode
1744 sa1100ir [NET]
1745 See drivers/net/irda/sa1100_ir.c.
1747 sbni= [NET] Granch SBNI12 leased line adapter
1749 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1750 Format: <io>[,<timeout>[,<isapnp>]]
1752 scsi_debug_*= [SCSI]
1753 See drivers/scsi/scsi_debug.c.
1755 scsi_default_dev_flags=
1756 [SCSI] SCSI default device flags
1757 Format: <integer>
1759 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1760 Format: <vendor>:<model>:<flags>
1761 (flags are integer value)
1763 scsi_logging_level= [SCSI] a bit mask of logging levels
1764 See drivers/scsi/scsi_logging.h for bits. Also
1765 settable via sysctl at dev.scsi.logging_level
1766 (/proc/sys/dev/scsi/logging_level).
1767 There is also a nice 'scsi_logging_level' script in the
1768 S390-tools package, available for download at
1769 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1771 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1772 discovered. async scans them in kernel threads,
1773 allowing boot to proceed. none ignores them, expecting
1774 user space to do the scan.
1776 selinux [SELINUX] Disable or enable SELinux at boot time.
1777 Format: { "0" | "1" }
1778 See security/selinux/Kconfig help text.
1779 0 -- disable.
1780 1 -- enable.
1781 Default value is set via kernel config option.
1782 If enabled at boot time, /selinux/disable can be used
1783 later to disable prior to initial policy load.
1785 selinux_compat_net =
1786 [SELINUX] Set initial selinux_compat_net flag value.
1787 Format: { "0" | "1" }
1788 0 -- use new secmark-based packet controls
1789 1 -- use legacy packet controls
1790 Default value is 0 (preferred).
1791 Value can be changed at runtime via
1792 /selinux/compat_net.
1794 serialnumber [BUGS=X86-32]
1796 shapers= [NET]
1797 Maximal number of shapers.
1799 sim710= [SCSI,HW]
1800 See header of drivers/scsi/sim710.c.
1802 simeth= [IA-64]
1803 simscsi=
1805 slram= [HW,MTD]
1807 slub_debug[=options[,slabs]] [MM, SLUB]
1808 Enabling slub_debug allows one to determine the
1809 culprit if slab objects become corrupted. Enabling
1810 slub_debug can create guard zones around objects and
1811 may poison objects when not in use. Also tracks the
1812 last alloc / free. For more information see
1813 Documentation/vm/slub.txt.
1815 slub_max_order= [MM, SLUB]
1816 Determines the maximum allowed order for slabs.
1817 A high setting may cause OOMs due to memory
1818 fragmentation. For more information see
1819 Documentation/vm/slub.txt.
1821 slub_min_objects= [MM, SLUB]
1822 The minimum number of objects per slab. SLUB will
1823 increase the slab order up to slub_max_order to
1824 generate a sufficiently large slab able to contain
1825 the number of objects indicated. The higher the number
1826 of objects the smaller the overhead of tracking slabs
1827 and the less frequently locks need to be acquired.
1828 For more information see Documentation/vm/slub.txt.
1830 slub_min_order= [MM, SLUB]
1831 Determines the mininum page order for slabs. Must be
1832 lower than slub_max_order.
1833 For more information see Documentation/vm/slub.txt.
1835 slub_nomerge [MM, SLUB]
1836 Disable merging of slabs with similar size. May be
1837 necessary if there is some reason to distinguish
1838 allocs to different slabs. Debug options disable
1839 merging on their own.
1840 For more information see Documentation/vm/slub.txt.
1842 smart2= [HW]
1843 Format: <io1>[,<io2>[,...,<io8>]]
1845 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1846 attempt to substitute SMP alternatives once at boot.
1848 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1849 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1850 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1851 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1852 smsc-ircc2.ircc_irq= [HW] IRQ line
1853 smsc-ircc2.ircc_dma= [HW] DMA channel
1854 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1855 0: Toshiba Satellite 1800 (GP data pin select)
1856 1: Fast pin select (default)
1857 2: ATC IRMode
1859 snd-ad1816a= [HW,ALSA]
1861 snd-ad1848= [HW,ALSA]
1863 snd-ali5451= [HW,ALSA]
1865 snd-als100= [HW,ALSA]
1867 snd-als4000= [HW,ALSA]
1869 snd-azt2320= [HW,ALSA]
1871 snd-cmi8330= [HW,ALSA]
1873 snd-cmipci= [HW,ALSA]
1875 snd-cs4231= [HW,ALSA]
1877 snd-cs4232= [HW,ALSA]
1879 snd-cs4236= [HW,ALSA]
1881 snd-cs4281= [HW,ALSA]
1883 snd-cs46xx= [HW,ALSA]
1885 snd-dt019x= [HW,ALSA]
1887 snd-dummy= [HW,ALSA]
1889 snd-emu10k1= [HW,ALSA]
1891 snd-ens1370= [HW,ALSA]
1893 snd-ens1371= [HW,ALSA]
1895 snd-es968= [HW,ALSA]
1897 snd-es1688= [HW,ALSA]
1899 snd-es18xx= [HW,ALSA]
1901 snd-es1938= [HW,ALSA]
1903 snd-es1968= [HW,ALSA]
1905 snd-fm801= [HW,ALSA]
1907 snd-gusclassic= [HW,ALSA]
1909 snd-gusextreme= [HW,ALSA]
1911 snd-gusmax= [HW,ALSA]
1913 snd-hdsp= [HW,ALSA]
1915 snd-ice1712= [HW,ALSA]
1917 snd-intel8x0= [HW,ALSA]
1919 snd-interwave= [HW,ALSA]
1921 snd-interwave-stb=
1922 [HW,ALSA]
1924 snd-korg1212= [HW,ALSA]
1926 snd-maestro3= [HW,ALSA]
1928 snd-mpu401= [HW,ALSA]
1930 snd-mtpav= [HW,ALSA]
1932 snd-nm256= [HW,ALSA]
1934 snd-opl3sa2= [HW,ALSA]
1936 snd-opti92x-ad1848=
1937 [HW,ALSA]
1939 snd-opti92x-cs4231=
1940 [HW,ALSA]
1942 snd-opti93x= [HW,ALSA]
1944 snd-pmac= [HW,ALSA]
1946 snd-rme32= [HW,ALSA]
1948 snd-rme96= [HW,ALSA]
1950 snd-rme9652= [HW,ALSA]
1952 snd-sb8= [HW,ALSA]
1954 snd-sb16= [HW,ALSA]
1956 snd-sbawe= [HW,ALSA]
1958 snd-serial= [HW,ALSA]
1960 snd-sgalaxy= [HW,ALSA]
1962 snd-sonicvibes= [HW,ALSA]
1964 snd-sun-amd7930=
1965 [HW,ALSA]
1967 snd-sun-cs4231= [HW,ALSA]
1969 snd-trident= [HW,ALSA]
1971 snd-usb-audio= [HW,ALSA,USB]
1973 snd-via82xx= [HW,ALSA]
1975 snd-virmidi= [HW,ALSA]
1977 snd-wavefront= [HW,ALSA]
1979 snd-ymfpci= [HW,ALSA]
1981 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1982 See Documentation/sonypi.txt
1984 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1985 See Documentation/specialix.txt.
1987 spia_io_base= [HW,MTD]
1988 spia_fio_base=
1989 spia_pedr=
1990 spia_peddr=
1992 sscape= [HW,OSS]
1993 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1995 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1996 See Documentation/scsi/st.txt.
1998 sti= [PARISC,HW]
1999 Format: <num>
2000 Set the STI (builtin display/keyboard on the HP-PARISC
2001 machines) console (graphic card) which should be used
2002 as the initial boot-console.
2003 See also comment in drivers/video/console/sticore.c.
2005 sti_font= [HW]
2006 See comment in drivers/video/console/sticore.c.
2008 stifb= [HW]
2009 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2011 sunrpc.pool_mode=
2012 [NFS]
2013 Control how the NFS server code allocates CPUs to
2014 service thread pools. Depending on how many NICs
2015 you have and where their interrupts are bound, this
2016 option will affect which CPUs will do NFS serving.
2017 Note: this parameter cannot be changed while the
2018 NFS server is running.
2020 auto the server chooses an appropriate mode
2021 automatically using heuristics
2022 global a single global pool contains all CPUs
2023 percpu one pool for each CPU
2024 pernode one pool for each NUMA node (equivalent
2025 to global on non-NUMA machines)
2027 swiotlb= [IA-64] Number of I/O TLB slabs
2029 switches= [HW,M68k]
2031 sym53c416= [HW,SCSI]
2032 See header of drivers/scsi/sym53c416.c.
2034 sysrq_always_enabled
2035 [KNL]
2036 Ignore sysrq setting - this boot parameter will
2037 neutralize any effect of /proc/sys/kernel/sysrq.
2038 Useful for debugging.
2040 t128= [HW,SCSI]
2041 See header of drivers/scsi/t128.c.
2043 tdfx= [HW,DRM]
2045 thash_entries= [KNL,NET]
2046 Set number of hash buckets for TCP connection
2048 thermal.act= [HW,ACPI]
2049 -1: disable all active trip points in all thermal zones
2050 <degrees C>: override all lowest active trip points
2052 thermal.crt= [HW,ACPI]
2053 -1: disable all critical trip points in all thermal zones
2054 <degrees C>: lower all critical trip points
2056 thermal.nocrt= [HW,ACPI]
2057 Set to disable actions on ACPI thermal zone
2058 critical and hot trip points.
2060 thermal.off= [HW,ACPI]
2061 1: disable ACPI thermal control
2063 thermal.psv= [HW,ACPI]
2064 -1: disable all passive trip points
2065 <degrees C>: override all passive trip points to this value
2067 thermal.tzp= [HW,ACPI]
2068 Specify global default ACPI thermal zone polling rate
2069 <deci-seconds>: poll all this frequency
2070 0: no polling (default)
2072 tipar.timeout= [HW,PPT]
2073 Set communications timeout in tenths of a second
2074 (default 15).
2076 tipar.delay= [HW,PPT]
2077 Set inter-bit delay in microseconds (default 10).
2079 tmscsim= [HW,SCSI]
2080 See comment before function dc390_setup() in
2081 drivers/scsi/tmscsim.c.
2083 tp720= [HW,PS2]
2085 trix= [HW,OSS] MediaTrix AudioTrix Pro
2086 Format:
2087 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2089 turbografx.map[2|3]= [HW,JOY]
2090 TurboGraFX parallel port interface
2091 Format:
2092 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2093 See also Documentation/input/joystick-parport.txt
2095 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2096 See header of drivers/scsi/u14-34f.c.
2098 uart401= [HW,OSS]
2099 Format: <io>,<irq>
2101 uart6850= [HW,OSS]
2102 Format: <io>,<irq>
2104 uhci-hcd.ignore_oc=
2105 [USB] Ignore overcurrent events (default N).
2106 Some badly-designed motherboards generate lots of
2107 bogus events, for ports that aren't wired to
2108 anything. Set this parameter to avoid log spamming.
2109 Note that genuine overcurrent events won't be
2110 reported either.
2112 usbcore.autosuspend=
2113 [USB] The autosuspend time delay (in seconds) used
2114 for newly-detected USB devices (default 2). This
2115 is the time required before an idle device will be
2116 autosuspended. Devices for which the delay is set
2117 to a negative value won't be autosuspended at all.
2119 usbhid.mousepoll=
2120 [USBHID] The interval which mice are to be polled at.
2122 vdso= [X86-32,SH,x86-64]
2123 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2124 vdso=1: enable VDSO (default)
2125 vdso=0: disable VDSO mapping
2127 vdso32= [X86-32,X86-64]
2128 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2129 vdso32=1: enable 32-bit VDSO (default)
2130 vdso32=0: disable 32-bit VDSO mapping
2132 vector= [IA-64,SMP]
2133 vector=percpu: enable percpu vector domain
2135 video= [FB] Frame buffer configuration
2136 See Documentation/fb/modedb.txt.
2138 vga= [BOOT,X86-32] Select a particular video mode
2139 See Documentation/i386/boot.txt and
2140 Documentation/svga.txt.
2141 Use vga=ask for menu.
2142 This is actually a boot loader parameter; the value is
2143 passed to the kernel using a special protocol.
2145 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2146 size of <nn>. This can be used to increase the
2147 minimum size (128MB on x86). It can also be used to
2148 decrease the size and leave more room for directly
2149 mapped kernel RAM.
2151 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2152 Format: <command>
2154 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2155 Format: <command>
2157 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2158 Format: <command>
2160 waveartist= [HW,OSS]
2161 Format: <io>,<irq>,<dma>,<dma2>
2163 wd33c93= [HW,SCSI]
2164 See header of drivers/scsi/wd33c93.c.
2166 wd7000= [HW,SCSI]
2167 See header of drivers/scsi/wd7000.c.
2169 wdt= [WDT] Watchdog
2170 See Documentation/watchdog/wdt.txt.
2172 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2173 xd_geo= See header of drivers/block/xd.c.
2175 xirc2ps_cs= [NET,PCMCIA]
2176 Format:
2177 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2179 norandmaps Don't use address space randomization
2180 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2182 ______________________________________________________________________
2184 TODO:
2186 Add documentation for ALSA options.
2187 Add more DRM drivers.