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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/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 }
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.
155 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
156 Format: { level | edge | high | low }
158 acpi_irq_balance [HW,ACPI]
159 ACPI will balance active IRQs
160 default in APIC mode
162 acpi_irq_nobalance [HW,ACPI]
163 ACPI will not move active IRQs (default)
164 default in PIC mode
166 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
167 use by PCI
168 Format: <irq>,<irq>...
170 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
171 Format: <irq>,<irq>...
173 acpi_new_pts_ordering [HW,ACPI]
174 Enforce the ACPI 2.0 ordering of the _PTS control
175 method wrt putting devices into low power states
176 default: pre ACPI 2.0 ordering of _PTS
178 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
180 acpi_no_initrd_override [KNL,ACPI]
181 Disable loading custom ACPI tables from the initramfs
183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
191 acpi_serialize [HW,ACPI] force serialization of AML methods
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
199 HPET
201 acpi.debug_layer= [HW,ACPI]
202 Format: <int>
203 Each bit of the <int> indicates an ACPI debug layer,
204 1: enable, 0: disable. It is useful for boot time
205 debugging. After system has booted up, it can be set
206 via /sys/module/acpi/parameters/debug_layer.
207 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
208 Available bits (add the numbers together) to enable debug output
209 for specific parts of the ACPI subsystem:
210 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
211 0x10 namespace 0x20 parser 0x40 dispatcher
212 0x80 executer 0x100 resources 0x200 acpica debugger
213 0x400 os services 0x800 acpica disassembler.
214 The number can be in decimal or prefixed with 0x in hex.
215 Warning: Many of these options can produce a lot of
216 output and make your system unusable. Be very careful.
218 acpi.debug_level= [HW,ACPI]
219 Format: <int>
220 Each bit of the <int> indicates an ACPI debug level,
221 1: enable, 0: disable. It is useful for boot time
222 debugging. After system has booted up, it can be set
223 via /sys/module/acpi/parameters/debug_level.
224 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
225 Available bits (add the numbers together) to enable different
226 debug output levels of the ACPI subsystem:
227 0x01 error 0x02 warn 0x04 init 0x08 debug object
228 0x10 info 0x20 init names 0x40 parse 0x80 load
229 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
230 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
231 0x10000 resources 0x20000 user requests 0x40000 package.
232 The number can be in decimal or prefixed with 0x in hex.
233 Warning: Many of these options can produce a lot of
234 output and make your system unusable. Be very careful.
236 acpi_pm_good [X86-32,X86-64]
237 Override the pmtimer bug detection: force the kernel
238 to assume that this machine's pmtimer latches its value
239 and always returns good values.
241 agp= [AGP]
242 { off | try_unsupported }
243 off: disable AGP support
244 try_unsupported: try to drive unsupported chipsets
245 (may crash computer or cause data corruption)
247 enable_timer_pin_1 [i386,x86-64]
248 Enable PIN 1 of APIC timer
249 Can be useful to work around chipset bugs
250 (in particular on some ATI chipsets).
251 The kernel tries to set a reasonable default.
253 disable_timer_pin_1 [i386,x86-64]
254 Disable PIN 1 of APIC timer
255 Can be useful to work around chipset bugs.
257 ad1848= [HW,OSS]
258 Format: <io>,<irq>,<dma>,<dma2>,<type>
260 advansys= [HW,SCSI]
261 See header of drivers/scsi/advansys.c.
263 advwdt= [HW,WDT] Advantech WDT
264 Format: <iostart>,<iostop>
266 aedsp16= [HW,OSS] Audio Excel DSP 16
267 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
268 See also header of sound/oss/aedsp16.c.
270 aha152x= [HW,SCSI]
271 See Documentation/scsi/aha152x.txt.
273 aha1542= [HW,SCSI]
274 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
276 aic7xxx= [HW,SCSI]
277 See Documentation/scsi/aic7xxx.txt.
279 aic79xx= [HW,SCSI]
280 See Documentation/scsi/aic79xx.txt.
282 amijoy.map= [HW,JOY] Amiga joystick support
283 Map of devices attached to JOY0DAT and JOY1DAT
284 Format: <a>,<b>
285 See also Documentation/kernel/input/joystick.txt
287 analog.map= [HW,JOY] Analog joystick and gamepad support
288 Specifies type or capabilities of an analog joystick
289 connected to one of 16 gameports
290 Format: <type1>,<type2>,..<type16>
292 apc= [HW,SPARC]
293 Power management functions (SPARCstation-4/5 + deriv.)
294 Format: noidle
295 Disable APC CPU standby support. SPARCstation-Fox does
296 not play well with APC CPU idle - disable it if you have
297 APC and your system crashes randomly.
299 apic= [APIC,i386] Advanced Programmable Interrupt Controller
300 Change the output verbosity whilst booting
301 Format: { quiet (default) | verbose | debug }
302 Change the amount of debugging information output
303 when initialising the APIC and IO-APIC components.
305 apm= [APM] Advanced Power Management
306 See header of arch/i386/kernel/apm.c.
308 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
309 Format: <io>,<irq>,<nodeID>
311 ataflop= [HW,M68k]
313 atarimouse= [HW,MOUSE] Atari Mouse
315 atascsi= [HW,SCSI] Atari SCSI
317 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
318 EzKey and similar keyboards
320 atkbd.reset= [HW] Reset keyboard during initialization
322 atkbd.set= [HW] Select keyboard code set
323 Format: <int> (2 = AT (default), 3 = PS/2)
325 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
326 keyboards
328 atkbd.softraw= [HW] Choose between synthetic and real raw mode
329 Format: <bool> (0 = real, 1 = synthetic (default))
331 atkbd.softrepeat= [HW]
332 Use software keyboard repeat
334 autotest [IA64]
336 baycom_epp= [HW,AX25]
337 Format: <io>,<mode>
339 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
340 Format: <io>,<mode>
341 See header of drivers/net/hamradio/baycom_par.c.
343 baycom_ser_fdx= [HW,AX25]
344 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
345 Format: <io>,<irq>,<mode>[,<baud>]
346 See header of drivers/net/hamradio/baycom_ser_fdx.c.
348 baycom_ser_hdx= [HW,AX25]
349 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
350 Format: <io>,<irq>,<mode>
351 See header of drivers/net/hamradio/baycom_ser_hdx.c.
353 boot_delay= Milliseconds to delay each printk during boot.
354 Values larger than 10 seconds (10000) are changed to
355 no delay (0).
356 Format: integer
358 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
359 bttv.radio= Most important insmod options are available as
360 kernel args too.
361 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
362 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
364 BusLogic= [HW,SCSI]
365 See drivers/scsi/BusLogic.c, comment before function
366 BusLogic_ParseDriverOptions().
368 c101= [NET] Moxa C101 synchronous serial card
370 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
371 Sometimes CPU hardware bugs make them report the cache
372 size incorrectly. The kernel will attempt work arounds
373 to fix known problems, but for some CPUs it is not
374 possible to determine what the correct size should be.
375 This option provides an override for these situations.
377 capability.disable=
378 [SECURITY] Disable capabilities. This would normally
379 be used only if an alternative security model is to be
380 configured. Potentially dangerous and should only be
381 used if you are entirely sure of the consequences.
383 ccw_timeout_log [S390]
384 See Documentation/s390/CommonIO for details.
386 checkreqprot [SELINUX] Set initial checkreqprot flag value.
387 Format: { "0" | "1" }
388 See security/selinux/Kconfig help text.
389 0 -- check protection applied by kernel (includes
390 any implied execute protection).
391 1 -- check protection requested by application.
392 Default value is set via a kernel config option.
393 Value can be changed at runtime via
394 /selinux/checkreqprot.
396 cio_ignore= [S390]
397 See Documentation/s390/CommonIO for details.
399 cio_msg= [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 earlycon= [KNL] Output early console device and options.
498 uart[8250],io,<addr>[,options]
499 uart[8250],mmio,<addr>[,options]
500 Start an early, polled-mode console on the 8250/16550
501 UART at the specified I/O port or MMIO address.
502 The options are the same as for ttyS, above.
504 no_console_suspend
505 [HW] Never suspend the console
506 Disable suspending of consoles during suspend and
507 hibernate operations. Once disabled, debugging
508 messages can reach various consoles while the rest
509 of the system is being put to sleep (ie, while
510 debugging driver suspend/resume hooks). This may
511 not work reliably with all consoles, but is known
512 to work with serial and VGA consoles.
514 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
515 Format:
516 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
518 crashkernel=nn[KMG]@ss[KMG]
519 [KNL] Reserve a chunk of physical memory to
520 hold a kernel to switch to with kexec on panic.
522 crashkernel=range1:size1[,range2:size2,...][@offset]
523 [KNL] Same as above, but depends on the memory
524 in the running system. The syntax of range is
525 start-[end] where start and end are both
526 a memory unit (amount[KMG]). See also
527 Documentation/kdump/kdump.txt for a example.
529 cs4232= [HW,OSS]
530 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
532 cs89x0_dma= [HW,NET]
533 Format: <dma>
535 cs89x0_media= [HW,NET]
536 Format: { rj45 | aui | bnc }
538 dasd= [HW,NET]
539 See header of drivers/s390/block/dasd_devmap.c.
541 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
542 (one device per port)
543 Format: <port#>,<type>
544 See also Documentation/input/joystick-parport.txt
546 debug [KNL] Enable kernel debugging (events log level).
548 debug_locks_verbose=
549 [KNL] verbose self-tests
550 Format=<0|1>
551 Print debugging info while doing the locking API
552 self-tests.
553 We default to 0 (no extra messages), setting it to
554 1 will print _a lot_ more information - normally
555 only useful to kernel developers.
557 decnet.addr= [HW,NET]
558 Format: <area>[,<node>]
559 See also Documentation/networking/decnet.txt.
561 vt.default_blu= [VT]
562 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
563 Change the default blue palette of the console.
564 This is a 16-member array composed of values
565 ranging from 0-255.
567 vt.default_grn= [VT]
568 Format: <green0>,<green1>,<green2>,...,<green15>
569 Change the default green palette of the console.
570 This is a 16-member array composed of values
571 ranging from 0-255.
573 vt.default_red= [VT]
574 Format: <red0>,<red1>,<red2>,...,<red15>
575 Change the default red palette of the console.
576 This is a 16-member array composed of values
577 ranging from 0-255.
579 vt.default_utf8=
580 [VT]
581 Format=<0|1>
582 Set system-wide default UTF-8 mode for all tty's.
583 Default is 1, i.e. UTF-8 mode is enabled for all
584 newly opened terminals.
586 dhash_entries= [KNL]
587 Set number of hash buckets for dentry cache.
589 digi= [HW,SERIAL]
590 IO parameters + enable/disable command.
592 digiepca= [HW,SERIAL]
593 See drivers/char/README.epca and
594 Documentation/digiepca.txt.
596 disable_mtrr_trim [X86, Intel and AMD only]
597 By default the kernel will trim any uncacheable
598 memory out of your available memory pool based on
599 MTRR settings. This parameter disables that behavior,
600 possibly causing your machine to run very slowly.
602 dmasound= [HW,OSS] Sound subsystem buffers
604 dscc4.setup= [NET]
606 dtc3181e= [HW,SCSI]
608 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
609 earlyprintk=vga
610 earlyprintk=serial[,ttySn[,baudrate]]
612 Append ",keep" to not disable it when the real console
613 takes over.
615 Only vga or serial at a time, not both.
617 Currently only ttyS0 and ttyS1 are supported.
619 Interaction with the standard serial driver is not
620 very good.
622 The VGA output is eventually overwritten by the real
623 console.
625 eata= [HW,SCSI]
627 edd= [EDD]
628 Format: {"of[f]" | "sk[ipmbr]"}
629 See comment in arch/i386/boot/edd.S
631 eisa_irq_edge= [PARISC,HW]
632 See header of drivers/parisc/eisa.c.
634 elanfreq= [X86-32]
635 See comment before function elanfreq_setup() in
636 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
638 elevator= [IOSCHED]
639 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
640 See Documentation/block/as-iosched.txt and
641 Documentation/block/deadline-iosched.txt for details.
643 elfcorehdr= [X86-32, X86_64]
644 Specifies physical address of start of kernel core
645 image elf header. Generally kexec loader will
646 pass this option to capture kernel.
647 See Documentation/kdump/kdump.txt for details.
649 enforcing [SELINUX] Set initial enforcing status.
650 Format: {"0" | "1"}
651 See security/selinux/Kconfig help text.
652 0 -- permissive (log only, no denials).
653 1 -- enforcing (deny and log).
654 Default value is 0.
655 Value can be changed at runtime via /selinux/enforce.
657 es1371= [HW,OSS]
658 Format: <spdif>,[<nomix>,[<amplifier>]]
659 See also header of sound/oss/es1371.c.
661 ether= [HW,NET] Ethernet cards parameters
662 This option is obsoleted by the "netdev=" option, which
663 has equivalent usage. See its documentation for details.
665 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
666 Format: <io>[,<irq>]
668 failslab=
669 fail_page_alloc=
670 fail_make_request=[KNL]
671 General fault injection mechanism.
672 Format: <interval>,<probability>,<space>,<times>
673 See also /Documentation/fault-injection/.
675 fd_mcs= [HW,SCSI]
676 See header of drivers/scsi/fd_mcs.c.
678 fdomain= [HW,SCSI]
679 See header of drivers/scsi/fdomain.c.
681 floppy= [HW]
682 See Documentation/floppy.txt.
684 gamecon.map[2|3]=
685 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
686 support via parallel port (up to 5 devices per port)
687 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
688 See also Documentation/input/joystick-parport.txt
690 gamma= [HW,DRM]
692 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
693 Format: off | on
694 default: on
696 gdth= [HW,SCSI]
697 See header of drivers/scsi/gdth.c.
699 gpt [EFI] Forces disk with valid GPT signature but
700 invalid Protective MBR to be treated as GPT.
702 gvp11= [HW,SCSI]
704 hashdist= [KNL,NUMA] Large hashes allocated during boot
705 are distributed across NUMA nodes. Defaults on
706 for IA-64, off otherwise.
707 Format: 0 | 1 (for off | on)
709 hcl= [IA-64] SGI's Hardware Graph compatibility layer
711 hd= [EIDE] (E)IDE hard drive subsystem geometry
712 Format: <cyl>,<head>,<sect>
714 hd?= [HW] (E)IDE subsystem
715 hd?lun= See Documentation/ide.txt.
717 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
718 size of <nn>. This works even on boxes that have no
719 highmem otherwise. This also works to reduce highmem
720 size on bigger boxes.
722 highres= [KNL] Enable/disable high resolution timer mode.
723 Valid parameters: "on", "off"
724 Default: "on"
726 hisax= [HW,ISDN]
727 See Documentation/isdn/README.HiSax.
729 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
730 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
732 i8042.direct [HW] Put keyboard port into non-translated mode
733 i8042.dumbkbd [HW] Pretend that controller can only read data from
734 keyboard and cannot control its state
735 (Don't attempt to blink the leds)
736 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
737 i8042.nokbd [HW] Don't check/create keyboard port
738 i8042.nomux [HW] Don't check presence of an active multiplexing
739 controller
740 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
741 controllers
742 i8042.panicblink=
743 [HW] Frequency with which keyboard LEDs should blink
744 when kernel panics (default is 0.5 sec)
745 i8042.reset [HW] Reset the controller during init and cleanup
746 i8042.unlock [HW] Unlock (ignore) the keylock
748 i810= [HW,DRM]
750 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
751 indicates that the driver is running on unsupported
752 hardware.
753 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
754 does not match list of supported models.
755 i8k.power_status
756 [HW] Report power status in /proc/i8k
757 (disabled by default)
758 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
759 capability is set.
761 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
762 See Documentation/mca.txt.
764 icn= [HW,ISDN]
765 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
767 ide= [HW] (E)IDE subsystem
768 Format: ide=nodma or ide=doubler or ide=reverse
769 See Documentation/ide.txt.
771 ide?= [HW] (E)IDE subsystem
772 Format: ide?=noprobe or chipset specific parameters.
773 See Documentation/ide.txt.
775 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
776 See Documentation/ide.txt.
778 idle= [X86]
779 Format: idle=poll or idle=mwait
780 Poll forces a polling idle loop that can slightly improves the performance
781 of waking up a idle CPU, but will use a lot of power and make the system
782 run hot. Not recommended.
783 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
784 to not use it because it doesn't save as much power as a normal idle
785 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
786 as idle=poll.
788 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
789 Claim all unknown PCI IDE storage controllers.
791 ignore_loglevel [KNL]
792 Ignore loglevel setting - this will print /all/
793 kernel messages to the console. Useful for debugging.
795 ihash_entries= [KNL]
796 Set number of hash buckets for inode cache.
798 in2000= [HW,SCSI]
799 See header of drivers/scsi/in2000.c.
801 init= [KNL]
802 Format: <full_path>
803 Run specified binary instead of /sbin/init as init
804 process.
806 initcall_debug [KNL] Trace initcalls as they are executed. Useful
807 for working out where the kernel is dying during
808 startup.
810 initrd= [BOOT] Specify the location of the initial ramdisk
812 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
813 Format: <irq>
815 inttest= [IA64]
817 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
818 off
819 Disable intel iommu driver.
820 igfx_off [Default Off]
821 By default, gfx is mapped as normal device. If a gfx
822 device has a dedicated DMAR unit, the DMAR unit is
823 bypassed by not enabling DMAR with this option. In
824 this case, gfx device will use physical address for
825 DMA.
826 forcedac [x86_64]
827 With this option iommu will not optimize to look
828 for io virtual address below 32 bit forcing dual
829 address cycle on pci bus for cards supporting greater
830 than 32 bit addressing. The default is to look
831 for translation below 32 bit and if not available
832 then look in the higher range.
834 io_delay= [X86-32,X86-64] I/O delay method
835 0x80
836 Standard port 0x80 based delay
837 0xed
838 Alternate port 0xed based delay (needed on some systems)
839 udelay
840 Simple two microseconds delay
841 none
842 No delay
844 io7= [HW] IO7 for Marvel based alpha systems
845 See comment before marvel_specify_io7 in
846 arch/alpha/kernel/core_marvel.c.
848 ip= [IP_PNP]
849 See Documentation/nfsroot.txt.
851 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
852 See comment before ip2_setup() in
853 drivers/char/ip2/ip2base.c.
855 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
856 See header of drivers/scsi/ips.c.
858 ports= [IP_VS_FTP] IPVS ftp helper module
859 Default is 21.
860 Up to 8 (IP_VS_APP_MAX_PORTS) ports
861 may be specified.
862 Format: <port>,<port>....
864 irqfixup [HW]
865 When an interrupt is not handled search all handlers
866 for it. Intended to get systems with badly broken
867 firmware running.
869 irqpoll [HW]
870 When an interrupt is not handled search all handlers
871 for it. Also check all handlers each timer
872 interrupt. Intended to get systems with badly broken
873 firmware running.
875 isapnp= [ISAPNP]
876 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
878 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
879 Format:
880 <cpu number>,...,<cpu number>
881 or
882 <cpu number>-<cpu number> (must be a positive range in ascending order)
883 or a mixture
884 <cpu number>,...,<cpu number>-<cpu number>
885 This option can be used to specify one or more CPUs
886 to isolate from the general SMP balancing and scheduling
887 algorithms. The only way to move a process onto or off
888 an "isolated" CPU is via the CPU affinity syscalls.
889 <cpu number> begins at 0 and the maximum value is
890 "number of CPUs in system - 1".
892 This option is the preferred way to isolate CPUs. The
893 alternative -- manually setting the CPU mask of all
894 tasks in the system -- can cause problems and
895 suboptimal load balancer performance.
897 iucv= [HW,NET]
899 js= [HW,JOY] Analog joystick
900 See Documentation/input/joystick.txt.
902 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
903 specifies the amount of memory usable by the kernel
904 for non-movable allocations. The requested amount is
905 spread evenly throughout all nodes in the system. The
906 remaining memory in each node is used for Movable
907 pages. In the event, a node is too small to have both
908 kernelcore and Movable pages, kernelcore pages will
909 take priority and other nodes will have a larger number
910 of kernelcore pages. The Movable zone is used for the
911 allocation of pages that may be reclaimed or moved
912 by the page migration subsystem. This means that
913 HugeTLB pages may not be allocated from this zone.
914 Note that allocations like PTEs-from-HighMem still
915 use the HighMem zone if it exists, and the Normal
916 zone if it does not.
918 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
919 is similar to kernelcore except it specifies the
920 amount of memory used for migratable allocations.
921 If both kernelcore and movablecore is specified,
922 then kernelcore will be at *least* the specified
923 value but may be more. If movablecore on its own
924 is specified, the administrator must be careful
925 that the amount of memory usable for all allocations
926 is not too small.
928 keepinitrd [HW,ARM]
930 kstack=N [X86-32,X86-64] Print N words from the kernel stack
931 in oops dumps.
933 l2cr= [PPC]
935 lapic [X86-32,APIC] Enable the local APIC even if BIOS
936 disabled it.
938 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
939 C2 power state.
941 libata.dma= [LIBATA] DMA control
942 libata.dma=0 Disable all PATA and SATA DMA
943 libata.dma=1 PATA and SATA Disk DMA only
944 libata.dma=2 ATAPI (CDROM) DMA only
945 libata.dma=4 Compact Flash DMA only
946 Combinations also work, so libata.dma=3 enables DMA
947 for disks and CDROMs, but not CFs.
949 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
950 when set.
951 Format: <int>
953 load_ramdisk= [RAM] List of ramdisks to load from floppy
954 See Documentation/ramdisk.txt.
956 lockd.nlm_grace_period=P [NFS] Assign grace period.
957 Format: <integer>
959 lockd.nlm_tcpport=N [NFS] Assign TCP port.
960 Format: <integer>
962 lockd.nlm_timeout=T [NFS] Assign timeout value.
963 Format: <integer>
965 lockd.nlm_udpport=M [NFS] Assign UDP port.
966 Format: <integer>
968 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
969 Format: <irq>
971 loglevel= All Kernel Messages with a loglevel smaller than the
972 console loglevel will be printed to the console. It can
973 also be changed with klogd or other programs. The
974 loglevels are defined as follows:
976 0 (KERN_EMERG) system is unusable
977 1 (KERN_ALERT) action must be taken immediately
978 2 (KERN_CRIT) critical conditions
979 3 (KERN_ERR) error conditions
980 4 (KERN_WARNING) warning conditions
981 5 (KERN_NOTICE) normal but significant condition
982 6 (KERN_INFO) informational
983 7 (KERN_DEBUG) debug-level messages
985 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
986 Format: { n | nk | nM }
987 n must be a power of two. The default size
988 is set in the kernel config file.
990 logo.nologo [FB] Disables display of the built-in Linux logo.
991 This may be used to provide more screen space for
992 kernel log messages and is useful when debugging
993 kernel boot problems.
995 lp=0 [LP] Specify parallel ports to use, e.g,
996 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
997 lp=reset first parallel port). 'lp=0' disables the
998 lp=auto printer driver. 'lp=reset' (which can be
999 specified in addition to the ports) causes
1000 attached printers to be reset. Using
1001 lp=port1,port2,... specifies the parallel ports
1002 to associate lp devices with, starting with
1003 lp0. A port specification may be 'none' to skip
1004 that lp device, or a parport name such as
1005 'parport0'. Specifying 'lp=auto' instead of a
1006 port specification list means that device IDs
1007 from each port should be examined, to see if
1008 an IEEE 1284-compliant printer is attached; if
1009 so, the driver will manage that printer.
1010 See also header of drivers/char/lp.c.
1012 lpj=n [KNL]
1013 Sets loops_per_jiffy to given constant, thus avoiding
1014 time-consuming boot-time autodetection (up to 250 ms per
1015 CPU). 0 enables autodetection (default). To determine
1016 the correct value for your kernel, boot with normal
1017 autodetection and see what value is printed. Note that
1018 on SMP systems the preset will be applied to all CPUs,
1019 which is likely to cause problems if your CPUs need
1020 significantly divergent settings. An incorrect value
1021 will cause delays in the kernel to be wrong, leading to
1022 unpredictable I/O errors and other breakage. Although
1023 unlikely, in the extreme case this might damage your
1024 hardware.
1026 ltpc= [NET]
1027 Format: <io>,<irq>,<dma>
1029 mac5380= [HW,SCSI] Format:
1030 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1032 mac53c9x= [HW,SCSI] Format:
1033 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1035 machvec= [IA64] Force the use of a particular machine-vector
1036 (machvec) in a generic kernel.
1037 Example: machvec=hpzx1_swiotlb
1039 max_loop= [LOOP] Maximum number of loopback devices that can
1040 be mounted
1041 Format: <1-256>
1043 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1044 should make use of. maxcpus=n : n >= 0 limits the
1045 kernel to using 'n' processors. n=0 is a special case,
1046 it is equivalent to "nosmp", which also disables
1047 the IO APIC.
1049 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1050 equal to this physical address is ignored.
1052 max_luns= [SCSI] Maximum number of LUNs to probe.
1053 Should be between 1 and 2^32-1.
1055 max_report_luns=
1056 [SCSI] Maximum number of LUNs received.
1057 Should be between 1 and 16384.
1059 mca-pentium [BUGS=X86-32]
1061 mcatest= [IA-64]
1063 mce [X86-32] Machine Check Exception
1065 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1067 md= [HW] RAID subsystems devices and level
1068 See Documentation/md.txt.
1070 mdacon= [MDA]
1071 Format: <first>,<last>
1072 Specifies range of consoles to be captured by the MDA.
1074 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1075 Amount of memory to be used when the kernel is not able
1076 to see the whole system memory or for test.
1077 [X86-32] Use together with memmap= to avoid physical
1078 address space collisions. Without memmap= PCI devices
1079 could be placed at addresses belonging to unused RAM.
1081 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1082 memory.
1084 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1085 E820 memory map, as specified by the user.
1086 Such memmap=exactmap lines can be constructed based on
1087 BIOS output or other requirements. See the memmap=nn@ss
1088 option description.
1090 memmap=nn[KMG]@ss[KMG]
1091 [KNL] Force usage of a specific region of memory
1092 Region of memory to be used, from ss to ss+nn.
1094 memmap=nn[KMG]#ss[KMG]
1095 [KNL,ACPI] Mark specific memory as ACPI data.
1096 Region of memory to be used, from ss to ss+nn.
1098 memmap=nn[KMG]$ss[KMG]
1099 [KNL,ACPI] Mark specific memory as reserved.
1100 Region of memory to be used, from ss to ss+nn.
1102 meye.*= [HW] Set MotionEye Camera parameters
1103 See Documentation/video4linux/meye.txt.
1105 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1106 Multi-Function General Purpose Timers on AMD Geode
1107 platforms.
1109 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1110 the BIOS has incorrectly applied a workaround. TinyBIOS
1111 version 0.98 is known to be affected, 0.99 fixes the
1112 problem by letting the user disable the workaround.
1114 mga= [HW,DRM]
1116 mousedev.tap_time=
1117 [MOUSE] Maximum time between finger touching and
1118 leaving touchpad surface for touch to be considered
1119 a tap and be reported as a left button click (for
1120 touchpads working in absolute mode only).
1121 Format: <msecs>
1122 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1123 reporting absolute coordinates, such as tablets
1124 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1125 reporting absolute coordinates, such as tablets
1127 mpu401= [HW,OSS]
1128 Format: <io>,<irq>
1130 MTD_Partition= [MTD]
1131 Format: <name>,<region-number>,<size>,<offset>
1133 MTD_Region= [MTD] Format:
1134 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1136 mtdparts= [MTD]
1137 See drivers/mtd/cmdlinepart.c.
1139 mtouchusb.raw_coordinates=
1140 [HW] Make the MicroTouch USB driver use raw coordinates
1141 ('y', default) or cooked coordinates ('n')
1143 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1145 NCR_D700= [HW,SCSI]
1146 See header of drivers/scsi/NCR_D700.c.
1148 ncr5380= [HW,SCSI]
1150 ncr53c400= [HW,SCSI]
1152 ncr53c400a= [HW,SCSI]
1154 ncr53c406a= [HW,SCSI]
1156 ncr53c8xx= [HW,SCSI]
1158 netdev= [NET] Network devices parameters
1159 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1160 Note that mem_start is often overloaded to mean
1161 something different and driver-specific.
1162 This usage is only documented in each driver source
1163 file if at all.
1165 nfsaddrs= [NFS]
1166 See Documentation/nfsroot.txt.
1168 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1169 See Documentation/nfsroot.txt.
1171 nfs.callback_tcpport=
1172 [NFS] set the TCP port on which the NFSv4 callback
1173 channel should listen.
1175 nfs.idmap_cache_timeout=
1176 [NFS] set the maximum lifetime for idmapper cache
1177 entries.
1179 nfs.enable_ino64=
1180 [NFS] enable 64-bit inode numbers.
1181 If zero, the NFS client will fake up a 32-bit inode
1182 number for the readdir() and stat() syscalls instead
1183 of returning the full 64-bit number.
1184 The default is to return 64-bit inode numbers.
1186 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1187 when a NMI is triggered.
1188 Format: [state][,regs][,debounce][,die]
1190 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1192 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1193 emulation library even if a 387 maths coprocessor
1194 is present.
1196 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1197 caches in the slab allocator. Saves per-node memory,
1198 but will impact performance.
1200 noalign [KNL,ARM]
1202 noapic [SMP,APIC] Tells the kernel to not make use of any
1203 IOAPICs that may be present in the system.
1205 nobats [PPC] Do not use BATs for mapping kernel lowmem
1206 on "Classic" PPC cores.
1208 nocache [ARM]
1210 nodelayacct [KNL] Disable per-task delay accounting
1212 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1214 noefi [X86-32,X86-64] Disable EFI runtime services support.
1216 noexec [IA-64]
1218 noexec [X86-32,X86-64]
1219 noexec=on: enable non-executable mappings (default)
1220 noexec=off: disable nn-executable mappings
1222 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1223 register save and restore. The kernel will only save
1224 legacy floating-point registers on task switch.
1226 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1228 nohlt [BUGS=ARM]
1230 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1231 instruction doesn't work correctly and not to
1232 use it.
1234 nohalt [IA-64] Tells the kernel not to use the power saving
1235 function PAL_HALT_LIGHT when idle. This increases
1236 power-consumption. On the positive side, it reduces
1237 interrupt wake-up latency, which may improve performance
1238 in certain environments such as networked servers or
1239 real-time systems.
1241 nohz= [KNL] Boottime enable/disable dynamic ticks
1242 Valid arguments: on, off
1243 Default: on
1245 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1247 noirqdebug [X86-32] Disables the code which attempts to detect and
1248 disable unhandled interrupt sources.
1250 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1251 broken timer IRQ sources.
1253 noisapnp [ISAPNP] Disables ISA PnP code.
1255 noinitrd [RAM] Tells the kernel not to load any configured
1256 initial RAM disk.
1258 nointroute [IA-64]
1260 nojitter [IA64] Disables jitter checking for ITC timers.
1262 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1264 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1266 noltlbs [PPC] Do not use large page/tlb entries for kernel
1267 lowmem mapping on PPC40x.
1269 nomca [IA-64] Disable machine check abort handling
1271 nomce [X86-32] Machine Check Exception
1273 nomfgpt [X86-32] Disable Multi-Function General Purpose
1274 Timer usage (for AMD Geode machines).
1276 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1278 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1279 with UP alternatives
1281 noresidual [PPC] Don't use residual data on PReP machines.
1283 noresume [SWSUSP] Disables resume and restores original swap
1284 space.
1286 no-scroll [VGA] Disables scrollback.
1287 This is required for the Braillex ib80-piezo Braille
1288 reader made by F.H. Papenmeier (Germany).
1290 nosbagart [IA-64]
1292 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1294 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1295 and disable the IO APIC. legacy for "maxcpus=0".
1297 nosoftlockup [KNL] Disable the soft-lockup detector.
1299 nosync [HW,M68K] Disables sync negotiation for all devices.
1301 notsc [BUGS=X86-32] Disable Time Stamp Counter
1303 nousb [USB] Disable the USB subsystem
1305 nowb [ARM]
1307 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1308 one of ['zone', 'node', 'default'] can be specified
1309 This can be set from sysctl after boot.
1310 See Documentation/sysctl/vm.txt for details.
1312 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1314 opl3= [HW,OSS]
1315 Format: <io>
1317 oprofile.timer= [HW]
1318 Use timer interrupt instead of performance counters
1320 osst= [HW,SCSI] SCSI Tape Driver
1321 Format: <buffer_size>,<write_threshold>
1322 See also Documentation/scsi/st.txt.
1324 panic= [KNL] Kernel behaviour on panic
1325 Format: <timeout>
1327 parkbd.port= [HW] Parallel port number the keyboard adapter is
1328 connected to, default is 0.
1329 Format: <parport#>
1330 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1331 0 for XT, 1 for AT (default is AT).
1332 Format: <mode>
1334 parport= [HW,PPT] Specify parallel ports. 0 disables.
1335 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1336 Use 'auto' to force the driver to use any
1337 IRQ/DMA settings detected (the default is to
1338 ignore detected IRQ/DMA settings because of
1339 possible conflicts). You can specify the base
1340 address, IRQ, and DMA settings; IRQ and DMA
1341 should be numbers, or 'auto' (for using detected
1342 settings on that particular port), or 'nofifo'
1343 (to avoid using a FIFO even if it is detected).
1344 Parallel ports are assigned in the order they
1345 are specified on the command line, starting
1346 with parport0.
1348 parport_init_mode= [HW,PPT]
1349 Configure VIA parallel port to operate in
1350 a specific mode. This is necessary on Pegasos
1351 computer where firmware has no options for setting
1352 up parallel port mode and sets it to spp.
1353 Currently this function knows 686a and 8231 chips.
1354 Format: [spp|ps2|epp|ecp|ecpepp]
1356 pas2= [HW,OSS] Format:
1357 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1359 pas16= [HW,SCSI]
1360 See header of drivers/scsi/pas16.c.
1362 pause_on_oops=
1363 Halt all CPUs after the first oops has been printed for
1364 the specified number of seconds. This is to be used if
1365 your oopses keep scrolling off the screen.
1367 pcbit= [HW,ISDN]
1369 pcd. [PARIDE]
1370 See header of drivers/block/paride/pcd.c.
1371 See also Documentation/paride.txt.
1373 pci=option[,option...] [PCI] various PCI subsystem options:
1374 off [X86-32] don't probe for the PCI bus
1375 bios [X86-32] force use of PCI BIOS, don't access
1376 the hardware directly. Use this if your machine
1377 has a non-standard PCI host bridge.
1378 nobios [X86-32] disallow use of PCI BIOS, only direct
1379 hardware access methods are allowed. Use this
1380 if you experience crashes upon bootup and you
1381 suspect they are caused by the BIOS.
1382 conf1 [X86-32] Force use of PCI Configuration
1383 Mechanism 1.
1384 conf2 [X86-32] Force use of PCI Configuration
1385 Mechanism 2.
1386 noaer [PCIE] If the PCIEAER kernel config parameter is
1387 enabled, this kernel boot option can be used to
1388 disable the use of PCIE advanced error reporting.
1389 nodomains [PCI] Disable support for multiple PCI
1390 root domains (aka PCI segments, in ACPI-speak).
1391 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1392 Configuration
1393 nomsi [MSI] If the PCI_MSI kernel config parameter is
1394 enabled, this kernel boot option can be used to
1395 disable the use of MSI interrupts system-wide.
1396 nosort [X86-32] Don't sort PCI devices according to
1397 order given by the PCI BIOS. This sorting is
1398 done to get a device order compatible with
1399 older kernels.
1400 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1401 routing table. These calls are known to be buggy
1402 on several machines and they hang the machine
1403 when used, but on other computers it's the only
1404 way to get the interrupt routing table. Try
1405 this option if the kernel is unable to allocate
1406 IRQs or discover secondary PCI buses on your
1407 motherboard.
1408 rom [X86-32] Assign address space to expansion ROMs.
1409 Use with caution as certain devices share
1410 address decoders between ROMs and other
1411 resources.
1412 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1413 assigned automatically to PCI devices. You can
1414 make the kernel exclude IRQs of your ISA cards
1415 this way.
1416 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1417 of the PIRQ table (normally generated
1418 by the BIOS) if it is outside the
1419 F0000h-100000h range.
1420 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1421 useful if the kernel is unable to find your
1422 secondary buses and you want to tell it
1423 explicitly which ones they are.
1424 assign-busses [X86-32] Always assign all PCI bus
1425 numbers ourselves, overriding
1426 whatever the firmware may have done.
1427 usepirqmask [X86-32] Honor the possible IRQ mask stored
1428 in the BIOS $PIR table. This is needed on
1429 some systems with broken BIOSes, notably
1430 some HP Pavilion N5400 and Omnibook XE3
1431 notebooks. This will have no effect if ACPI
1432 IRQ routing is enabled.
1433 noacpi [X86-32] Do not use ACPI for IRQ routing
1434 or for PCI scanning.
1435 use_crs [X86-32] Use _CRS for PCI resource
1436 allocation.
1437 routeirq Do IRQ routing for all PCI devices.
1438 This is normally done in pci_enable_device(),
1439 so this option is a temporary workaround
1440 for broken drivers that don't call it.
1441 firmware [ARM] Do not re-enumerate the bus but instead
1442 just use the configuration from the
1443 bootloader. This is currently used on
1444 IXP2000 systems where the bus has to be
1445 configured a certain way for adjunct CPUs.
1446 noearly [X86] Don't do any early type 1 scanning.
1447 This might help on some broken boards which
1448 machine check when some devices' config space
1449 is read. But various workarounds are disabled
1450 and some IOMMU drivers will not work.
1451 bfsort Sort PCI devices into breadth-first order.
1452 This sorting is done to get a device
1453 order compatible with older (<= 2.4) kernels.
1454 nobfsort Don't sort PCI devices into breadth-first order.
1455 cbiosize=nn[KMG] The fixed amount of bus space which is
1456 reserved for the CardBus bridge's IO window.
1457 The default value is 256 bytes.
1458 cbmemsize=nn[KMG] The fixed amount of bus space which is
1459 reserved for the CardBus bridge's memory
1460 window. The default value is 64 megabytes.
1462 pcmv= [HW,PCMCIA] BadgePAD 4
1464 pd. [PARIDE]
1465 See Documentation/paride.txt.
1467 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1468 boot time.
1469 Format: { 0 | 1 }
1470 See arch/parisc/kernel/pdc_chassis.c
1472 pf. [PARIDE]
1473 See Documentation/paride.txt.
1475 pg. [PARIDE]
1476 See Documentation/paride.txt.
1478 pirq= [SMP,APIC] Manual mp-table setup
1479 See Documentation/i386/IO-APIC.txt.
1481 plip= [PPT,NET] Parallel port network link
1482 Format: { parport<nr> | timid | 0 }
1483 See also Documentation/parport.txt.
1485 pnpacpi= [ACPI]
1486 { off }
1488 pnpbios= [ISAPNP]
1489 { on | off | curr | res | no-curr | no-res }
1491 pnp_reserve_irq=
1492 [ISAPNP] Exclude IRQs for the autoconfiguration
1494 pnp_reserve_dma=
1495 [ISAPNP] Exclude DMAs for the autoconfiguration
1497 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1498 Ranges are in pairs (I/O port base and size).
1500 pnp_reserve_mem=
1501 [ISAPNP] Exclude memory regions for the
1502 autoconfiguration.
1503 Ranges are in pairs (memory base and size).
1505 print-fatal-signals=
1506 [KNL] debug: print fatal signals
1507 print-fatal-signals=1: print segfault info to
1508 the kernel console.
1509 default: off.
1511 printk.time= Show timing data prefixed to each printk message line
1512 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1514 profile= [KNL] Enable kernel profiling via /proc/profile
1515 Format: [schedule,]<number>
1516 Param: "schedule" - profile schedule points.
1517 Param: <number> - step/bucket size as a power of 2 for
1518 statistical time based profiling.
1519 Param: "sleep" - profile D-state sleeping (millisecs).
1520 Requires CONFIG_SCHEDSTATS
1521 Param: "kvm" - profile VM exits.
1523 processor.max_cstate= [HW,ACPI]
1524 Limit processor to maximum C-state
1525 max_cstate=9 overrides any DMI blacklist limit.
1527 processor.nocst [HW,ACPI]
1528 Ignore the _CST method to determine C-states,
1529 instead using the legacy FADT method
1531 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1532 before loading.
1533 See Documentation/ramdisk.txt.
1535 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1536 probe for; one of (bare|imps|exps|lifebook|any).
1537 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1538 per second.
1539 psmouse.resetafter= [HW,MOUSE]
1540 Try to reset the device after so many bad packets
1541 (0 = never).
1542 psmouse.resolution=
1543 [HW,MOUSE] Set desired mouse resolution, in dpi.
1544 psmouse.smartscroll=
1545 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1546 0 = disabled, 1 = enabled (default).
1548 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1549 Format:
1550 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1552 pt. [PARIDE]
1553 See Documentation/paride.txt.
1555 pty.legacy_count=
1556 [KNL] Number of legacy pty's. Overwrites compiled-in
1557 default number.
1559 quiet [KNL] Disable most log messages
1561 r128= [HW,DRM]
1563 raid= [HW,RAID]
1564 See Documentation/md.txt.
1566 ramdisk_blocksize= [RAM]
1567 See Documentation/ramdisk.txt.
1569 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1570 See Documentation/ramdisk.txt.
1572 rcupdate.blimit= [KNL,BOOT]
1573 Set maximum number of finished RCU callbacks to process
1574 in one batch.
1576 rcupdate.qhimark= [KNL,BOOT]
1577 Set threshold of queued
1578 RCU callbacks over which batch limiting is disabled.
1580 rcupdate.qlowmark= [KNL,BOOT]
1581 Set threshold of queued RCU callbacks below which
1582 batch limiting is re-enabled.
1584 rdinit= [KNL]
1585 Format: <full_path>
1586 Run specified binary instead of /init from the ramdisk,
1587 used for early userspace startup. See initrd.
1589 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1590 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1591 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1593 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1595 reservetop= [X86-32]
1596 Format: nn[KMG]
1597 Reserves a hole at the top of the kernel virtual
1598 address space.
1600 reset_devices [KNL] Force drivers to reset the underlying device
1601 during initialization.
1603 resume= [SWSUSP]
1604 Specify the partition device for software suspend
1606 resume_offset= [SWSUSP]
1607 Specify the offset from the beginning of the partition
1608 given by "resume=" at which the swap header is located,
1609 in <PAGE_SIZE> units (needed only for swap files).
1610 See Documentation/power/swsusp-and-swap-files.txt
1612 retain_initrd [RAM] Keep initrd memory after extraction
1614 rhash_entries= [KNL,NET]
1615 Set number of hash buckets for route cache
1617 riscom8= [HW,SERIAL]
1618 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1620 ro [KNL] Mount root device read-only on boot
1622 root= [KNL] Root filesystem
1624 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1625 mount the root filesystem
1627 rootflags= [KNL] Set root filesystem mount option string
1629 rootfstype= [KNL] Set root filesystem type
1631 rootwait [KNL] Wait (indefinitely) for root device to show up.
1632 Useful for devices that are detected asynchronously
1633 (e.g. USB and MMC devices).
1635 root_plug.vendor_id=
1636 [ROOTPLUG] Override the default vendor ID
1638 root_plug.product_id=
1639 [ROOTPLUG] Override the default product ID
1641 root_plug.debug=
1642 [ROOTPLUG] Enable debugging output
1644 rw [KNL] Mount root device read-write on boot
1646 S [KNL] Run init in single mode
1648 sa1100ir [NET]
1649 See drivers/net/irda/sa1100_ir.c.
1651 sbni= [NET] Granch SBNI12 leased line adapter
1653 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1654 Format: <io>[,<timeout>[,<isapnp>]]
1656 scsi_debug_*= [SCSI]
1657 See drivers/scsi/scsi_debug.c.
1659 scsi_default_dev_flags=
1660 [SCSI] SCSI default device flags
1661 Format: <integer>
1663 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1664 Format: <vendor>:<model>:<flags>
1665 (flags are integer value)
1667 scsi_logging_level= [SCSI] a bit mask of logging levels
1668 See drivers/scsi/scsi_logging.h for bits. Also
1669 settable via sysctl at dev.scsi.logging_level
1670 (/proc/sys/dev/scsi/logging_level).
1671 There is also a nice 'scsi_logging_level' script in the
1672 S390-tools package, available for download at
1673 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1675 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1676 discovered. async scans them in kernel threads,
1677 allowing boot to proceed. none ignores them, expecting
1678 user space to do the scan.
1680 selinux [SELINUX] Disable or enable SELinux at boot time.
1681 Format: { "0" | "1" }
1682 See security/selinux/Kconfig help text.
1683 0 -- disable.
1684 1 -- enable.
1685 Default value is set via kernel config option.
1686 If enabled at boot time, /selinux/disable can be used
1687 later to disable prior to initial policy load.
1689 selinux_compat_net =
1690 [SELINUX] Set initial selinux_compat_net flag value.
1691 Format: { "0" | "1" }
1692 0 -- use new secmark-based packet controls
1693 1 -- use legacy packet controls
1694 Default value is 0 (preferred).
1695 Value can be changed at runtime via
1696 /selinux/compat_net.
1698 serialnumber [BUGS=X86-32]
1700 shapers= [NET]
1701 Maximal number of shapers.
1703 sim710= [SCSI,HW]
1704 See header of drivers/scsi/sim710.c.
1706 simeth= [IA-64]
1707 simscsi=
1709 slram= [HW,MTD]
1711 slub_debug[=options[,slabs]] [MM, SLUB]
1712 Enabling slub_debug allows one to determine the
1713 culprit if slab objects become corrupted. Enabling
1714 slub_debug can create guard zones around objects and
1715 may poison objects when not in use. Also tracks the
1716 last alloc / free. For more information see
1717 Documentation/vm/slub.txt.
1719 slub_max_order= [MM, SLUB]
1720 Determines the maximum allowed order for slabs.
1721 A high setting may cause OOMs due to memory
1722 fragmentation. For more information see
1723 Documentation/vm/slub.txt.
1725 slub_min_objects= [MM, SLUB]
1726 The minimum number of objects per slab. SLUB will
1727 increase the slab order up to slub_max_order to
1728 generate a sufficiently large slab able to contain
1729 the number of objects indicated. The higher the number
1730 of objects the smaller the overhead of tracking slabs
1731 and the less frequently locks need to be acquired.
1732 For more information see Documentation/vm/slub.txt.
1734 slub_min_order= [MM, SLUB]
1735 Determines the mininum page order for slabs. Must be
1736 lower than slub_max_order.
1737 For more information see Documentation/vm/slub.txt.
1739 slub_nomerge [MM, SLUB]
1740 Disable merging of slabs with similar size. May be
1741 necessary if there is some reason to distinguish
1742 allocs to different slabs. Debug options disable
1743 merging on their own.
1744 For more information see Documentation/vm/slub.txt.
1746 smart2= [HW]
1747 Format: <io1>[,<io2>[,...,<io8>]]
1749 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1750 attempt to substitute SMP alternatives once at boot.
1752 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1753 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1754 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1755 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1756 smsc-ircc2.ircc_irq= [HW] IRQ line
1757 smsc-ircc2.ircc_dma= [HW] DMA channel
1758 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1759 0: Toshiba Satellite 1800 (GP data pin select)
1760 1: Fast pin select (default)
1761 2: ATC IRMode
1763 snd-ad1816a= [HW,ALSA]
1765 snd-ad1848= [HW,ALSA]
1767 snd-ali5451= [HW,ALSA]
1769 snd-als100= [HW,ALSA]
1771 snd-als4000= [HW,ALSA]
1773 snd-azt2320= [HW,ALSA]
1775 snd-cmi8330= [HW,ALSA]
1777 snd-cmipci= [HW,ALSA]
1779 snd-cs4231= [HW,ALSA]
1781 snd-cs4232= [HW,ALSA]
1783 snd-cs4236= [HW,ALSA]
1785 snd-cs4281= [HW,ALSA]
1787 snd-cs46xx= [HW,ALSA]
1789 snd-dt019x= [HW,ALSA]
1791 snd-dummy= [HW,ALSA]
1793 snd-emu10k1= [HW,ALSA]
1795 snd-ens1370= [HW,ALSA]
1797 snd-ens1371= [HW,ALSA]
1799 snd-es968= [HW,ALSA]
1801 snd-es1688= [HW,ALSA]
1803 snd-es18xx= [HW,ALSA]
1805 snd-es1938= [HW,ALSA]
1807 snd-es1968= [HW,ALSA]
1809 snd-fm801= [HW,ALSA]
1811 snd-gusclassic= [HW,ALSA]
1813 snd-gusextreme= [HW,ALSA]
1815 snd-gusmax= [HW,ALSA]
1817 snd-hdsp= [HW,ALSA]
1819 snd-ice1712= [HW,ALSA]
1821 snd-intel8x0= [HW,ALSA]
1823 snd-interwave= [HW,ALSA]
1825 snd-interwave-stb=
1826 [HW,ALSA]
1828 snd-korg1212= [HW,ALSA]
1830 snd-maestro3= [HW,ALSA]
1832 snd-mpu401= [HW,ALSA]
1834 snd-mtpav= [HW,ALSA]
1836 snd-nm256= [HW,ALSA]
1838 snd-opl3sa2= [HW,ALSA]
1840 snd-opti92x-ad1848=
1841 [HW,ALSA]
1843 snd-opti92x-cs4231=
1844 [HW,ALSA]
1846 snd-opti93x= [HW,ALSA]
1848 snd-pmac= [HW,ALSA]
1850 snd-rme32= [HW,ALSA]
1852 snd-rme96= [HW,ALSA]
1854 snd-rme9652= [HW,ALSA]
1856 snd-sb8= [HW,ALSA]
1858 snd-sb16= [HW,ALSA]
1860 snd-sbawe= [HW,ALSA]
1862 snd-serial= [HW,ALSA]
1864 snd-sgalaxy= [HW,ALSA]
1866 snd-sonicvibes= [HW,ALSA]
1868 snd-sun-amd7930=
1869 [HW,ALSA]
1871 snd-sun-cs4231= [HW,ALSA]
1873 snd-trident= [HW,ALSA]
1875 snd-usb-audio= [HW,ALSA,USB]
1877 snd-via82xx= [HW,ALSA]
1879 snd-virmidi= [HW,ALSA]
1881 snd-wavefront= [HW,ALSA]
1883 snd-ymfpci= [HW,ALSA]
1885 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1886 See Documentation/sonypi.txt
1888 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1889 See Documentation/specialix.txt.
1891 spia_io_base= [HW,MTD]
1892 spia_fio_base=
1893 spia_pedr=
1894 spia_peddr=
1896 sscape= [HW,OSS]
1897 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1899 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1900 See Documentation/scsi/st.txt.
1902 sti= [PARISC,HW]
1903 Format: <num>
1904 Set the STI (builtin display/keyboard on the HP-PARISC
1905 machines) console (graphic card) which should be used
1906 as the initial boot-console.
1907 See also comment in drivers/video/console/sticore.c.
1909 sti_font= [HW]
1910 See comment in drivers/video/console/sticore.c.
1912 stifb= [HW]
1913 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1915 sunrpc.pool_mode=
1916 [NFS]
1917 Control how the NFS server code allocates CPUs to
1918 service thread pools. Depending on how many NICs
1919 you have and where their interrupts are bound, this
1920 option will affect which CPUs will do NFS serving.
1921 Note: this parameter cannot be changed while the
1922 NFS server is running.
1924 auto the server chooses an appropriate mode
1925 automatically using heuristics
1926 global a single global pool contains all CPUs
1927 percpu one pool for each CPU
1928 pernode one pool for each NUMA node (equivalent
1929 to global on non-NUMA machines)
1931 swiotlb= [IA-64] Number of I/O TLB slabs
1933 switches= [HW,M68k]
1935 sym53c416= [HW,SCSI]
1936 See header of drivers/scsi/sym53c416.c.
1938 sysrq_always_enabled
1939 [KNL]
1940 Ignore sysrq setting - this boot parameter will
1941 neutralize any effect of /proc/sys/kernel/sysrq.
1942 Useful for debugging.
1944 t128= [HW,SCSI]
1945 See header of drivers/scsi/t128.c.
1947 tdfx= [HW,DRM]
1949 thash_entries= [KNL,NET]
1950 Set number of hash buckets for TCP connection
1952 thermal.act= [HW,ACPI]
1953 -1: disable all active trip points in all thermal zones
1954 <degrees C>: override all lowest active trip points
1956 thermal.crt= [HW,ACPI]
1957 -1: disable all critical trip points in all thermal zones
1958 <degrees C>: lower all critical trip points
1960 thermal.nocrt= [HW,ACPI]
1961 Set to disable actions on ACPI thermal zone
1962 critical and hot trip points.
1964 thermal.off= [HW,ACPI]
1965 1: disable ACPI thermal control
1967 thermal.psv= [HW,ACPI]
1968 -1: disable all passive trip points
1969 <degrees C>: override all passive trip points to this value
1971 thermal.tzp= [HW,ACPI]
1972 Specify global default ACPI thermal zone polling rate
1973 <deci-seconds>: poll all this frequency
1974 0: no polling (default)
1976 tipar.timeout= [HW,PPT]
1977 Set communications timeout in tenths of a second
1978 (default 15).
1980 tipar.delay= [HW,PPT]
1981 Set inter-bit delay in microseconds (default 10).
1983 tmscsim= [HW,SCSI]
1984 See comment before function dc390_setup() in
1985 drivers/scsi/tmscsim.c.
1987 tp720= [HW,PS2]
1989 trix= [HW,OSS] MediaTrix AudioTrix Pro
1990 Format:
1991 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1993 turbografx.map[2|3]= [HW,JOY]
1994 TurboGraFX parallel port interface
1995 Format:
1996 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1997 See also Documentation/input/joystick-parport.txt
1999 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2000 See header of drivers/scsi/u14-34f.c.
2002 uart401= [HW,OSS]
2003 Format: <io>,<irq>
2005 uart6850= [HW,OSS]
2006 Format: <io>,<irq>
2008 uhci-hcd.ignore_oc=
2009 [USB] Ignore overcurrent events (default N).
2010 Some badly-designed motherboards generate lots of
2011 bogus events, for ports that aren't wired to
2012 anything. Set this parameter to avoid log spamming.
2013 Note that genuine overcurrent events won't be
2014 reported either.
2016 usbcore.autosuspend=
2017 [USB] The autosuspend time delay (in seconds) used
2018 for newly-detected USB devices (default 2). This
2019 is the time required before an idle device will be
2020 autosuspended. Devices for which the delay is set
2021 to a negative value won't be autosuspended at all.
2023 usbhid.mousepoll=
2024 [USBHID] The interval which mice are to be polled at.
2026 vdso= [X86-32,SH,x86-64]
2027 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2028 vdso=1: enable VDSO (default)
2029 vdso=0: disable VDSO mapping
2031 vdso32= [X86-32,X86-64]
2032 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2033 vdso32=1: enable 32-bit VDSO (default)
2034 vdso32=0: disable 32-bit VDSO mapping
2036 vector= [IA-64,SMP]
2037 vector=percpu: enable percpu vector domain
2039 video= [FB] Frame buffer configuration
2040 See Documentation/fb/modedb.txt.
2042 vga= [BOOT,X86-32] Select a particular video mode
2043 See Documentation/i386/boot.txt and
2044 Documentation/svga.txt.
2045 Use vga=ask for menu.
2046 This is actually a boot loader parameter; the value is
2047 passed to the kernel using a special protocol.
2049 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2050 size of <nn>. This can be used to increase the
2051 minimum size (128MB on x86). It can also be used to
2052 decrease the size and leave more room for directly
2053 mapped kernel RAM.
2055 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2056 Format: <command>
2058 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2059 Format: <command>
2061 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2062 Format: <command>
2064 waveartist= [HW,OSS]
2065 Format: <io>,<irq>,<dma>,<dma2>
2067 wd33c93= [HW,SCSI]
2068 See header of drivers/scsi/wd33c93.c.
2070 wd7000= [HW,SCSI]
2071 See header of drivers/scsi/wd7000.c.
2073 wdt= [WDT] Watchdog
2074 See Documentation/watchdog/wdt.txt.
2076 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2077 xd_geo= See header of drivers/block/xd.c.
2079 xirc2ps_cs= [NET,PCMCIA]
2080 Format:
2081 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2083 norandmaps Don't use address space randomization
2084 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2086 ______________________________________________________________________
2088 TODO:
2090 Add documentation for ALSA options.
2091 Add more DRM drivers.