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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 }
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_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
181 Format: To spoof as Windows 98: ="Microsoft Windows"
183 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
184 acpi_osi="string1" # add string1 -- only one string
185 acpi_osi="!string2" # remove built-in string2
186 acpi_osi= # disable all strings
188 acpi_serialize [HW,ACPI] force serialization of AML methods
190 acpi_skip_timer_override [HW,ACPI]
191 Recognize and ignore IRQ0/pin2 Interrupt Override.
192 For broken nForce2 BIOS resulting in XT-PIC timer.
193 acpi_use_timer_override [HW,ACPI}
194 Use timer override. For some broken Nvidia NF5 boards
195 that require a timer override, but don't have
196 HPET
198 acpi.debug_layer= [HW,ACPI]
199 Format: <int>
200 Each bit of the <int> indicates an ACPI debug layer,
201 1: enable, 0: disable. It is useful for boot time
202 debugging. After system has booted up, it can be set
203 via /sys/module/acpi/parameters/debug_layer.
204 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
205 Available bits (add the numbers together) to enable debug output
206 for specific parts of the ACPI subsystem:
207 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
208 0x10 namespace 0x20 parser 0x40 dispatcher
209 0x80 executer 0x100 resources 0x200 acpica debugger
210 0x400 os services 0x800 acpica disassembler.
211 The number can be in decimal or prefixed with 0x in hex.
212 Warning: Many of these options can produce a lot of
213 output and make your system unusable. Be very careful.
215 acpi.debug_level= [HW,ACPI]
216 Format: <int>
217 Each bit of the <int> indicates an ACPI debug level,
218 1: enable, 0: disable. It is useful for boot time
219 debugging. After system has booted up, it can be set
220 via /sys/module/acpi/parameters/debug_level.
221 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
222 Available bits (add the numbers together) to enable different
223 debug output levels of the ACPI subsystem:
224 0x01 error 0x02 warn 0x04 init 0x08 debug object
225 0x10 info 0x20 init names 0x40 parse 0x80 load
226 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
227 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
228 0x10000 resources 0x20000 user requests 0x40000 package.
229 The number can be in decimal or prefixed with 0x in hex.
230 Warning: Many of these options can produce a lot of
231 output and make your system unusable. Be very careful.
233 acpi_pm_good [X86-32,X86-64]
234 Override the pmtimer bug detection: force the kernel
235 to assume that this machine's pmtimer latches its value
236 and always returns good values.
238 agp= [AGP]
239 { off | try_unsupported }
240 off: disable AGP support
241 try_unsupported: try to drive unsupported chipsets
242 (may crash computer or cause data corruption)
244 enable_timer_pin_1 [i386,x86-64]
245 Enable PIN 1 of APIC timer
246 Can be useful to work around chipset bugs
247 (in particular on some ATI chipsets).
248 The kernel tries to set a reasonable default.
250 disable_timer_pin_1 [i386,x86-64]
251 Disable PIN 1 of APIC timer
252 Can be useful to work around chipset bugs.
254 ad1848= [HW,OSS]
255 Format: <io>,<irq>,<dma>,<dma2>,<type>
257 advansys= [HW,SCSI]
258 See header of drivers/scsi/advansys.c.
260 advwdt= [HW,WDT] Advantech WDT
261 Format: <iostart>,<iostop>
263 aedsp16= [HW,OSS] Audio Excel DSP 16
264 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
265 See also header of sound/oss/aedsp16.c.
267 aha152x= [HW,SCSI]
268 See Documentation/scsi/aha152x.txt.
270 aha1542= [HW,SCSI]
271 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
273 aic7xxx= [HW,SCSI]
274 See Documentation/scsi/aic7xxx.txt.
276 aic79xx= [HW,SCSI]
277 See Documentation/scsi/aic79xx.txt.
279 amijoy.map= [HW,JOY] Amiga joystick support
280 Map of devices attached to JOY0DAT and JOY1DAT
281 Format: <a>,<b>
282 See also Documentation/kernel/input/joystick.txt
284 analog.map= [HW,JOY] Analog joystick and gamepad support
285 Specifies type or capabilities of an analog joystick
286 connected to one of 16 gameports
287 Format: <type1>,<type2>,..<type16>
289 apc= [HW,SPARC]
290 Power management functions (SPARCstation-4/5 + deriv.)
291 Format: noidle
292 Disable APC CPU standby support. SPARCstation-Fox does
293 not play well with APC CPU idle - disable it if you have
294 APC and your system crashes randomly.
296 apic= [APIC,i386] Advanced Programmable Interrupt Controller
297 Change the output verbosity whilst booting
298 Format: { quiet (default) | verbose | debug }
299 Change the amount of debugging information output
300 when initialising the APIC and IO-APIC components.
302 apm= [APM] Advanced Power Management
303 See header of arch/i386/kernel/apm.c.
305 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
306 Format: <io>,<irq>,<nodeID>
308 ataflop= [HW,M68k]
310 atarimouse= [HW,MOUSE] Atari Mouse
312 atascsi= [HW,SCSI] Atari SCSI
314 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
315 EzKey and similar keyboards
317 atkbd.reset= [HW] Reset keyboard during initialization
319 atkbd.set= [HW] Select keyboard code set
320 Format: <int> (2 = AT (default), 3 = PS/2)
322 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
323 keyboards
325 atkbd.softraw= [HW] Choose between synthetic and real raw mode
326 Format: <bool> (0 = real, 1 = synthetic (default))
328 atkbd.softrepeat= [HW]
329 Use software keyboard repeat
331 autotest [IA64]
333 baycom_epp= [HW,AX25]
334 Format: <io>,<mode>
336 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
337 Format: <io>,<mode>
338 See header of drivers/net/hamradio/baycom_par.c.
340 baycom_ser_fdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
342 Format: <io>,<irq>,<mode>[,<baud>]
343 See header of drivers/net/hamradio/baycom_ser_fdx.c.
345 baycom_ser_hdx= [HW,AX25]
346 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
347 Format: <io>,<irq>,<mode>
348 See header of drivers/net/hamradio/baycom_ser_hdx.c.
350 boot_delay= Milliseconds to delay each printk during boot.
351 Values larger than 10 seconds (10000) are changed to
352 no delay (0).
353 Format: integer
355 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
356 bttv.radio= Most important insmod options are available as
357 kernel args too.
358 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
359 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
361 BusLogic= [HW,SCSI]
362 See drivers/scsi/BusLogic.c, comment before function
363 BusLogic_ParseDriverOptions().
365 c101= [NET] Moxa C101 synchronous serial card
367 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
368 Sometimes CPU hardware bugs make them report the cache
369 size incorrectly. The kernel will attempt work arounds
370 to fix known problems, but for some CPUs it is not
371 possible to determine what the correct size should be.
372 This option provides an override for these situations.
374 capability.disable=
375 [SECURITY] Disable capabilities. This would normally
376 be used only if an alternative security model is to be
377 configured. Potentially dangerous and should only be
378 used if you are entirely sure of the consequences.
380 ccw_timeout_log [S390]
381 See Documentation/s390/CommonIO for details.
383 checkreqprot [SELINUX] Set initial checkreqprot flag value.
384 Format: { "0" | "1" }
385 See security/selinux/Kconfig help text.
386 0 -- check protection applied by kernel (includes
387 any implied execute protection).
388 1 -- check protection requested by application.
389 Default value is set via a kernel config option.
390 Value can be changed at runtime via
391 /selinux/checkreqprot.
393 cio_ignore= [S390]
394 See Documentation/s390/CommonIO for details.
396 cio_msg= [S390]
397 See Documentation/s390/CommonIO for details.
399 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
400 [Deprecated]
401 Forces specified clocksource (if available) to be used
402 when calculating gettimeofday(). If specified
403 clocksource is not available, it defaults to PIT.
404 Format: { pit | tsc | cyclone | pmtmr }
406 clocksource= [GENERIC_TIME] Override the default clocksource
407 Format: <string>
408 Override the default clocksource and use the clocksource
409 with the name specified.
410 Some clocksource names to choose from, depending on
411 the platform:
412 [all] jiffies (this is the base, fallback clocksource)
413 [ACPI] acpi_pm
414 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
415 pxa_timer,timer3,32k_counter,timer0_1
416 [AVR32] avr32
417 [X86-32] pit,hpet,tsc,vmi-timer;
418 scx200_hrt on Geode; cyclone on IBM x440
419 [MIPS] MIPS
420 [PARISC] cr16
421 [S390] tod
422 [SH] SuperH
423 [SPARC64] tick
424 [X86-64] hpet,tsc
426 clearcpuid=BITNUM [X86]
427 Disable CPUID feature X for the kernel. See
428 include/asm-x86/cpufeature.h for the valid bit numbers.
429 Note the Linux specific bits are not necessarily
430 stable over kernel options, but the vendor specific
431 ones should be.
432 Also note that user programs calling CPUID directly
433 or using the feature without checking anything
434 will still see it. This just prevents it from
435 being used by the kernel or shown in /proc/cpuinfo.
436 Also note the kernel might malfunction if you disable
437 some critical bits.
439 code_bytes [IA32/X86_64] How many bytes of object code to print
440 in an oops report.
441 Range: 0 - 8192
442 Default: 64
444 disable_8254_timer
445 enable_8254_timer
446 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
447 over the 8254 in addition to over the IO-APIC. The
448 kernel tries to set a sensible default.
450 hpet= [X86-32,HPET] option to control HPET usage
451 Format: { enable (default) | disable | force }
452 disable: disable HPET and use PIT instead
453 force: allow force enabled of undocumented chips (ICH4,
454 VIA, nVidia)
456 com20020= [HW,NET] ARCnet - COM20020 chipset
457 Format:
458 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
460 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
461 Format: <io>[,<irq>]
463 com90xx= [HW,NET]
464 ARCnet - COM90xx chipset (memory-mapped buffers)
465 Format: <io>[,<irq>[,<memstart>]]
467 condev= [HW,S390] console device
468 conmode=
470 console= [KNL] Output console device and options.
472 tty<n> Use the virtual console device <n>.
474 ttyS<n>[,options]
475 ttyUSB0[,options]
476 Use the specified serial port. The options are of
477 the form "bbbbpnf", where "bbbb" is the baud rate,
478 "p" is parity ("n", "o", or "e"), "n" is number of
479 bits, and "f" is flow control ("r" for RTS or
480 omit it). Default is "9600n8".
482 See Documentation/serial-console.txt for more
483 information. See
484 Documentation/networking/netconsole.txt for an
485 alternative.
487 uart[8250],io,<addr>[,options]
488 uart[8250],mmio,<addr>[,options]
489 Start an early, polled-mode console on the 8250/16550
490 UART at the specified I/O port or MMIO address,
491 switching to the matching ttyS device later. The
492 options are the same as for ttyS, above.
494 earlycon= [KNL] Output early console device and options.
495 uart[8250],io,<addr>[,options]
496 uart[8250],mmio,<addr>[,options]
497 Start an early, polled-mode console on the 8250/16550
498 UART at the specified I/O port or MMIO address.
499 The options are the same as for ttyS, above.
501 no_console_suspend
502 [HW] Never suspend the console
503 Disable suspending of consoles during suspend and
504 hibernate operations. Once disabled, debugging
505 messages can reach various consoles while the rest
506 of the system is being put to sleep (ie, while
507 debugging driver suspend/resume hooks). This may
508 not work reliably with all consoles, but is known
509 to work with serial and VGA consoles.
511 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
512 Format:
513 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
515 crashkernel=nn[KMG]@ss[KMG]
516 [KNL] Reserve a chunk of physical memory to
517 hold a kernel to switch to with kexec on panic.
519 crashkernel=range1:size1[,range2:size2,...][@offset]
520 [KNL] Same as above, but depends on the memory
521 in the running system. The syntax of range is
522 start-[end] where start and end are both
523 a memory unit (amount[KMG]). See also
524 Documentation/kdump/kdump.txt for a example.
526 cs4232= [HW,OSS]
527 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
529 cs89x0_dma= [HW,NET]
530 Format: <dma>
532 cs89x0_media= [HW,NET]
533 Format: { rj45 | aui | bnc }
535 dasd= [HW,NET]
536 See header of drivers/s390/block/dasd_devmap.c.
538 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
539 (one device per port)
540 Format: <port#>,<type>
541 See also Documentation/input/joystick-parport.txt
543 debug [KNL] Enable kernel debugging (events log level).
545 debug_locks_verbose=
546 [KNL] verbose self-tests
547 Format=<0|1>
548 Print debugging info while doing the locking API
549 self-tests.
550 We default to 0 (no extra messages), setting it to
551 1 will print _a lot_ more information - normally
552 only useful to kernel developers.
554 decnet.addr= [HW,NET]
555 Format: <area>[,<node>]
556 See also Documentation/networking/decnet.txt.
558 vt.default_blu= [VT]
559 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
560 Change the default blue palette of the console.
561 This is a 16-member array composed of values
562 ranging from 0-255.
564 vt.default_grn= [VT]
565 Format: <green0>,<green1>,<green2>,...,<green15>
566 Change the default green palette of the console.
567 This is a 16-member array composed of values
568 ranging from 0-255.
570 vt.default_red= [VT]
571 Format: <red0>,<red1>,<red2>,...,<red15>
572 Change the default red palette of the console.
573 This is a 16-member array composed of values
574 ranging from 0-255.
576 vt.default_utf8=
577 [VT]
578 Format=<0|1>
579 Set system-wide default UTF-8 mode for all tty's.
580 Default is 1, i.e. UTF-8 mode is enabled for all
581 newly opened terminals.
583 dhash_entries= [KNL]
584 Set number of hash buckets for dentry cache.
586 digi= [HW,SERIAL]
587 IO parameters + enable/disable command.
589 digiepca= [HW,SERIAL]
590 See drivers/char/README.epca and
591 Documentation/digiepca.txt.
593 disable_mtrr_trim [X86, Intel and AMD only]
594 By default the kernel will trim any uncacheable
595 memory out of your available memory pool based on
596 MTRR settings. This parameter disables that behavior,
597 possibly causing your machine to run very slowly.
599 dmasound= [HW,OSS] Sound subsystem buffers
601 dscc4.setup= [NET]
603 dtc3181e= [HW,SCSI]
605 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
606 earlyprintk=vga
607 earlyprintk=serial[,ttySn[,baudrate]]
609 Append ",keep" to not disable it when the real console
610 takes over.
612 Only vga or serial at a time, not both.
614 Currently only ttyS0 and ttyS1 are supported.
616 Interaction with the standard serial driver is not
617 very good.
619 The VGA output is eventually overwritten by the real
620 console.
622 eata= [HW,SCSI]
624 edd= [EDD]
625 Format: {"of[f]" | "sk[ipmbr]"}
626 See comment in arch/i386/boot/edd.S
628 eisa_irq_edge= [PARISC,HW]
629 See header of drivers/parisc/eisa.c.
631 elanfreq= [X86-32]
632 See comment before function elanfreq_setup() in
633 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
635 elevator= [IOSCHED]
636 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
637 See Documentation/block/as-iosched.txt and
638 Documentation/block/deadline-iosched.txt for details.
640 elfcorehdr= [X86-32, X86_64]
641 Specifies physical address of start of kernel core
642 image elf header. Generally kexec loader will
643 pass this option to capture kernel.
644 See Documentation/kdump/kdump.txt for details.
646 enforcing [SELINUX] Set initial enforcing status.
647 Format: {"0" | "1"}
648 See security/selinux/Kconfig help text.
649 0 -- permissive (log only, no denials).
650 1 -- enforcing (deny and log).
651 Default value is 0.
652 Value can be changed at runtime via /selinux/enforce.
654 es1371= [HW,OSS]
655 Format: <spdif>,[<nomix>,[<amplifier>]]
656 See also header of sound/oss/es1371.c.
658 ether= [HW,NET] Ethernet cards parameters
659 This option is obsoleted by the "netdev=" option, which
660 has equivalent usage. See its documentation for details.
662 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
663 Format: <io>[,<irq>]
665 failslab=
666 fail_page_alloc=
667 fail_make_request=[KNL]
668 General fault injection mechanism.
669 Format: <interval>,<probability>,<space>,<times>
670 See also /Documentation/fault-injection/.
672 fd_mcs= [HW,SCSI]
673 See header of drivers/scsi/fd_mcs.c.
675 fdomain= [HW,SCSI]
676 See header of drivers/scsi/fdomain.c.
678 floppy= [HW]
679 See Documentation/floppy.txt.
681 gamecon.map[2|3]=
682 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
683 support via parallel port (up to 5 devices per port)
684 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
685 See also Documentation/input/joystick-parport.txt
687 gamma= [HW,DRM]
689 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
690 Format: off | on
691 default: on
693 gdth= [HW,SCSI]
694 See header of drivers/scsi/gdth.c.
696 gpt [EFI] Forces disk with valid GPT signature but
697 invalid Protective MBR to be treated as GPT.
699 gvp11= [HW,SCSI]
701 hashdist= [KNL,NUMA] Large hashes allocated during boot
702 are distributed across NUMA nodes. Defaults on
703 for IA-64, off otherwise.
704 Format: 0 | 1 (for off | on)
706 hcl= [IA-64] SGI's Hardware Graph compatibility layer
708 hd= [EIDE] (E)IDE hard drive subsystem geometry
709 Format: <cyl>,<head>,<sect>
711 hd?= [HW] (E)IDE subsystem
712 hd?lun= See Documentation/ide/ide.txt.
714 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
715 size of <nn>. This works even on boxes that have no
716 highmem otherwise. This also works to reduce highmem
717 size on bigger boxes.
719 highres= [KNL] Enable/disable high resolution timer mode.
720 Valid parameters: "on", "off"
721 Default: "on"
723 hisax= [HW,ISDN]
724 See Documentation/isdn/README.HiSax.
726 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
727 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
729 i8042.direct [HW] Put keyboard port into non-translated mode
730 i8042.dumbkbd [HW] Pretend that controller can only read data from
731 keyboard and cannot control its state
732 (Don't attempt to blink the leds)
733 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
734 i8042.nokbd [HW] Don't check/create keyboard port
735 i8042.nomux [HW] Don't check presence of an active multiplexing
736 controller
737 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
738 controllers
739 i8042.panicblink=
740 [HW] Frequency with which keyboard LEDs should blink
741 when kernel panics (default is 0.5 sec)
742 i8042.reset [HW] Reset the controller during init and cleanup
743 i8042.unlock [HW] Unlock (ignore) the keylock
745 i810= [HW,DRM]
747 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
748 indicates that the driver is running on unsupported
749 hardware.
750 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
751 does not match list of supported models.
752 i8k.power_status
753 [HW] Report power status in /proc/i8k
754 (disabled by default)
755 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
756 capability is set.
758 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
759 See Documentation/mca.txt.
761 icn= [HW,ISDN]
762 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
764 ide= [HW] (E)IDE subsystem
765 Format: ide=nodma or ide=doubler or ide=reverse
766 See Documentation/ide/ide.txt.
768 ide?= [HW] (E)IDE subsystem
769 Format: ide?=noprobe or chipset specific parameters.
770 See Documentation/ide/ide.txt.
772 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
773 See Documentation/ide/ide.txt.
775 idle= [X86]
776 Format: idle=poll or idle=mwait
777 Poll forces a polling idle loop that can slightly improves the performance
778 of waking up a idle CPU, but will use a lot of power and make the system
779 run hot. Not recommended.
780 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
781 to not use it because it doesn't save as much power as a normal idle
782 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
783 as idle=poll.
785 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
786 Claim all unknown PCI IDE storage controllers.
788 ignore_loglevel [KNL]
789 Ignore loglevel setting - this will print /all/
790 kernel messages to the console. Useful for debugging.
792 ihash_entries= [KNL]
793 Set number of hash buckets for inode cache.
795 in2000= [HW,SCSI]
796 See header of drivers/scsi/in2000.c.
798 init= [KNL]
799 Format: <full_path>
800 Run specified binary instead of /sbin/init as init
801 process.
803 initcall_debug [KNL] Trace initcalls as they are executed. Useful
804 for working out where the kernel is dying during
805 startup.
807 initrd= [BOOT] Specify the location of the initial ramdisk
809 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
810 Format: <irq>
812 inttest= [IA64]
814 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
815 off
816 Disable intel iommu driver.
817 igfx_off [Default Off]
818 By default, gfx is mapped as normal device. If a gfx
819 device has a dedicated DMAR unit, the DMAR unit is
820 bypassed by not enabling DMAR with this option. In
821 this case, gfx device will use physical address for
822 DMA.
823 forcedac [x86_64]
824 With this option iommu will not optimize to look
825 for io virtual address below 32 bit forcing dual
826 address cycle on pci bus for cards supporting greater
827 than 32 bit addressing. The default is to look
828 for translation below 32 bit and if not available
829 then look in the higher range.
831 io_delay= [X86-32,X86-64] I/O delay method
832 0x80
833 Standard port 0x80 based delay
834 0xed
835 Alternate port 0xed based delay (needed on some systems)
836 udelay
837 Simple two microseconds delay
838 none
839 No delay
841 io7= [HW] IO7 for Marvel based alpha systems
842 See comment before marvel_specify_io7 in
843 arch/alpha/kernel/core_marvel.c.
845 ip= [IP_PNP]
846 See Documentation/nfsroot.txt.
848 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
849 See comment before ip2_setup() in
850 drivers/char/ip2/ip2base.c.
852 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
853 See header of drivers/scsi/ips.c.
855 ports= [IP_VS_FTP] IPVS ftp helper module
856 Default is 21.
857 Up to 8 (IP_VS_APP_MAX_PORTS) ports
858 may be specified.
859 Format: <port>,<port>....
861 irqfixup [HW]
862 When an interrupt is not handled search all handlers
863 for it. Intended to get systems with badly broken
864 firmware running.
866 irqpoll [HW]
867 When an interrupt is not handled search all handlers
868 for it. Also check all handlers each timer
869 interrupt. Intended to get systems with badly broken
870 firmware running.
872 isapnp= [ISAPNP]
873 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
875 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
876 Format:
877 <cpu number>,...,<cpu number>
878 or
879 <cpu number>-<cpu number> (must be a positive range in ascending order)
880 or a mixture
881 <cpu number>,...,<cpu number>-<cpu number>
882 This option can be used to specify one or more CPUs
883 to isolate from the general SMP balancing and scheduling
884 algorithms. The only way to move a process onto or off
885 an "isolated" CPU is via the CPU affinity syscalls.
886 <cpu number> begins at 0 and the maximum value is
887 "number of CPUs in system - 1".
889 This option is the preferred way to isolate CPUs. The
890 alternative -- manually setting the CPU mask of all
891 tasks in the system -- can cause problems and
892 suboptimal load balancer performance.
894 iucv= [HW,NET]
896 js= [HW,JOY] Analog joystick
897 See Documentation/input/joystick.txt.
899 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
900 specifies the amount of memory usable by the kernel
901 for non-movable allocations. The requested amount is
902 spread evenly throughout all nodes in the system. The
903 remaining memory in each node is used for Movable
904 pages. In the event, a node is too small to have both
905 kernelcore and Movable pages, kernelcore pages will
906 take priority and other nodes will have a larger number
907 of kernelcore pages. The Movable zone is used for the
908 allocation of pages that may be reclaimed or moved
909 by the page migration subsystem. This means that
910 HugeTLB pages may not be allocated from this zone.
911 Note that allocations like PTEs-from-HighMem still
912 use the HighMem zone if it exists, and the Normal
913 zone if it does not.
915 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
916 is similar to kernelcore except it specifies the
917 amount of memory used for migratable allocations.
918 If both kernelcore and movablecore is specified,
919 then kernelcore will be at *least* the specified
920 value but may be more. If movablecore on its own
921 is specified, the administrator must be careful
922 that the amount of memory usable for all allocations
923 is not too small.
925 keepinitrd [HW,ARM]
927 kstack=N [X86-32,X86-64] Print N words from the kernel stack
928 in oops dumps.
930 l2cr= [PPC]
932 lapic [X86-32,APIC] Enable the local APIC even if BIOS
933 disabled it.
935 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
936 C2 power state.
938 libata.dma= [LIBATA] DMA control
939 libata.dma=0 Disable all PATA and SATA DMA
940 libata.dma=1 PATA and SATA Disk DMA only
941 libata.dma=2 ATAPI (CDROM) DMA only
942 libata.dma=4 Compact Flash DMA only
943 Combinations also work, so libata.dma=3 enables DMA
944 for disks and CDROMs, but not CFs.
946 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
947 when set.
948 Format: <int>
950 libata.force= [LIBATA] Force configurations. The format is comma
951 separated list of "[ID:]VAL" where ID is
952 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
953 matching port, link or device. Basically, it matches
954 the ATA ID string printed on console by libata. If
955 the whole ID part is omitted, the last PORT and DEVICE
956 values are used. If ID hasn't been specified yet, the
957 configuration applies to all ports, links and devices.
959 If only DEVICE is omitted, the parameter applies to
960 the port and all links and devices behind it. DEVICE
961 number of 0 either selects the first device or the
962 first fan-out link behind PMP device. It does not
963 select the host link. DEVICE number of 15 selects the
964 host link and device attached to it.
966 The VAL specifies the configuration to force. As long
967 as there's no ambiguity shortcut notation is allowed.
968 For example, both 1.5 and 1.5G would work for 1.5Gbps.
969 The following configurations can be forced.
971 * Cable type: 40c, 80c, short40c, unk, ign or sata.
972 Any ID with matching PORT is used.
974 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
976 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
977 udma[/][16,25,33,44,66,100,133] notation is also
978 allowed.
980 * [no]ncq: Turn on or off NCQ.
982 If there are multiple matching configurations changing
983 the same attribute, the last one is used.
985 load_ramdisk= [RAM] List of ramdisks to load from floppy
986 See Documentation/ramdisk.txt.
988 lockd.nlm_grace_period=P [NFS] Assign grace period.
989 Format: <integer>
991 lockd.nlm_tcpport=N [NFS] Assign TCP port.
992 Format: <integer>
994 lockd.nlm_timeout=T [NFS] Assign timeout value.
995 Format: <integer>
997 lockd.nlm_udpport=M [NFS] Assign UDP port.
998 Format: <integer>
1000 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1001 Format: <irq>
1003 loglevel= All Kernel Messages with a loglevel smaller than the
1004 console loglevel will be printed to the console. It can
1005 also be changed with klogd or other programs. The
1006 loglevels are defined as follows:
1008 0 (KERN_EMERG) system is unusable
1009 1 (KERN_ALERT) action must be taken immediately
1010 2 (KERN_CRIT) critical conditions
1011 3 (KERN_ERR) error conditions
1012 4 (KERN_WARNING) warning conditions
1013 5 (KERN_NOTICE) normal but significant condition
1014 6 (KERN_INFO) informational
1015 7 (KERN_DEBUG) debug-level messages
1017 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1018 Format: { n | nk | nM }
1019 n must be a power of two. The default size
1020 is set in the kernel config file.
1022 logo.nologo [FB] Disables display of the built-in Linux logo.
1023 This may be used to provide more screen space for
1024 kernel log messages and is useful when debugging
1025 kernel boot problems.
1027 lp=0 [LP] Specify parallel ports to use, e.g,
1028 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1029 lp=reset first parallel port). 'lp=0' disables the
1030 lp=auto printer driver. 'lp=reset' (which can be
1031 specified in addition to the ports) causes
1032 attached printers to be reset. Using
1033 lp=port1,port2,... specifies the parallel ports
1034 to associate lp devices with, starting with
1035 lp0. A port specification may be 'none' to skip
1036 that lp device, or a parport name such as
1037 'parport0'. Specifying 'lp=auto' instead of a
1038 port specification list means that device IDs
1039 from each port should be examined, to see if
1040 an IEEE 1284-compliant printer is attached; if
1041 so, the driver will manage that printer.
1042 See also header of drivers/char/lp.c.
1044 lpj=n [KNL]
1045 Sets loops_per_jiffy to given constant, thus avoiding
1046 time-consuming boot-time autodetection (up to 250 ms per
1047 CPU). 0 enables autodetection (default). To determine
1048 the correct value for your kernel, boot with normal
1049 autodetection and see what value is printed. Note that
1050 on SMP systems the preset will be applied to all CPUs,
1051 which is likely to cause problems if your CPUs need
1052 significantly divergent settings. An incorrect value
1053 will cause delays in the kernel to be wrong, leading to
1054 unpredictable I/O errors and other breakage. Although
1055 unlikely, in the extreme case this might damage your
1056 hardware.
1058 ltpc= [NET]
1059 Format: <io>,<irq>,<dma>
1061 mac5380= [HW,SCSI] Format:
1062 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1064 mac53c9x= [HW,SCSI] Format:
1065 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1067 machvec= [IA64] Force the use of a particular machine-vector
1068 (machvec) in a generic kernel.
1069 Example: machvec=hpzx1_swiotlb
1071 max_loop= [LOOP] Maximum number of loopback devices that can
1072 be mounted
1073 Format: <1-256>
1075 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1076 should make use of. maxcpus=n : n >= 0 limits the
1077 kernel to using 'n' processors. n=0 is a special case,
1078 it is equivalent to "nosmp", which also disables
1079 the IO APIC.
1081 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1082 equal to this physical address is ignored.
1084 max_luns= [SCSI] Maximum number of LUNs to probe.
1085 Should be between 1 and 2^32-1.
1087 max_report_luns=
1088 [SCSI] Maximum number of LUNs received.
1089 Should be between 1 and 16384.
1091 mcatest= [IA-64]
1093 mce [X86-32] Machine Check Exception
1095 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1097 md= [HW] RAID subsystems devices and level
1098 See Documentation/md.txt.
1100 mdacon= [MDA]
1101 Format: <first>,<last>
1102 Specifies range of consoles to be captured by the MDA.
1104 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1105 Amount of memory to be used when the kernel is not able
1106 to see the whole system memory or for test.
1107 [X86-32] Use together with memmap= to avoid physical
1108 address space collisions. Without memmap= PCI devices
1109 could be placed at addresses belonging to unused RAM.
1111 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1112 memory.
1114 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1115 E820 memory map, as specified by the user.
1116 Such memmap=exactmap lines can be constructed based on
1117 BIOS output or other requirements. See the memmap=nn@ss
1118 option description.
1120 memmap=nn[KMG]@ss[KMG]
1121 [KNL] Force usage of a specific region of memory
1122 Region of memory to be used, from ss to ss+nn.
1124 memmap=nn[KMG]#ss[KMG]
1125 [KNL,ACPI] Mark specific memory as ACPI data.
1126 Region of memory to be used, from ss to ss+nn.
1128 memmap=nn[KMG]$ss[KMG]
1129 [KNL,ACPI] Mark specific memory as reserved.
1130 Region of memory to be used, from ss to ss+nn.
1132 meye.*= [HW] Set MotionEye Camera parameters
1133 See Documentation/video4linux/meye.txt.
1135 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1136 Multi-Function General Purpose Timers on AMD Geode
1137 platforms.
1139 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1140 the BIOS has incorrectly applied a workaround. TinyBIOS
1141 version 0.98 is known to be affected, 0.99 fixes the
1142 problem by letting the user disable the workaround.
1144 mga= [HW,DRM]
1146 mousedev.tap_time=
1147 [MOUSE] Maximum time between finger touching and
1148 leaving touchpad surface for touch to be considered
1149 a tap and be reported as a left button click (for
1150 touchpads working in absolute mode only).
1151 Format: <msecs>
1152 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1153 reporting absolute coordinates, such as tablets
1154 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1155 reporting absolute coordinates, such as tablets
1157 mpu401= [HW,OSS]
1158 Format: <io>,<irq>
1160 MTD_Partition= [MTD]
1161 Format: <name>,<region-number>,<size>,<offset>
1163 MTD_Region= [MTD] Format:
1164 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1166 mtdparts= [MTD]
1167 See drivers/mtd/cmdlinepart.c.
1169 mtouchusb.raw_coordinates=
1170 [HW] Make the MicroTouch USB driver use raw coordinates
1171 ('y', default) or cooked coordinates ('n')
1173 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1175 NCR_D700= [HW,SCSI]
1176 See header of drivers/scsi/NCR_D700.c.
1178 ncr5380= [HW,SCSI]
1180 ncr53c400= [HW,SCSI]
1182 ncr53c400a= [HW,SCSI]
1184 ncr53c406a= [HW,SCSI]
1186 ncr53c8xx= [HW,SCSI]
1188 netdev= [NET] Network devices parameters
1189 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1190 Note that mem_start is often overloaded to mean
1191 something different and driver-specific.
1192 This usage is only documented in each driver source
1193 file if at all.
1195 nfsaddrs= [NFS]
1196 See Documentation/nfsroot.txt.
1198 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1199 See Documentation/nfsroot.txt.
1201 nfs.callback_tcpport=
1202 [NFS] set the TCP port on which the NFSv4 callback
1203 channel should listen.
1205 nfs.idmap_cache_timeout=
1206 [NFS] set the maximum lifetime for idmapper cache
1207 entries.
1209 nfs.enable_ino64=
1210 [NFS] enable 64-bit inode numbers.
1211 If zero, the NFS client will fake up a 32-bit inode
1212 number for the readdir() and stat() syscalls instead
1213 of returning the full 64-bit number.
1214 The default is to return 64-bit inode numbers.
1216 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1217 when a NMI is triggered.
1218 Format: [state][,regs][,debounce][,die]
1220 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1222 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1223 emulation library even if a 387 maths coprocessor
1224 is present.
1226 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1227 caches in the slab allocator. Saves per-node memory,
1228 but will impact performance.
1230 noalign [KNL,ARM]
1232 noapic [SMP,APIC] Tells the kernel to not make use of any
1233 IOAPICs that may be present in the system.
1235 nobats [PPC] Do not use BATs for mapping kernel lowmem
1236 on "Classic" PPC cores.
1238 nocache [ARM]
1240 nodelayacct [KNL] Disable per-task delay accounting
1242 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1244 noefi [X86-32,X86-64] Disable EFI runtime services support.
1246 noexec [IA-64]
1248 noexec [X86-32,X86-64]
1249 noexec=on: enable non-executable mappings (default)
1250 noexec=off: disable nn-executable mappings
1252 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1253 register save and restore. The kernel will only save
1254 legacy floating-point registers on task switch.
1256 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1258 nohlt [BUGS=ARM]
1260 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1261 instruction doesn't work correctly and not to
1262 use it.
1264 nohalt [IA-64] Tells the kernel not to use the power saving
1265 function PAL_HALT_LIGHT when idle. This increases
1266 power-consumption. On the positive side, it reduces
1267 interrupt wake-up latency, which may improve performance
1268 in certain environments such as networked servers or
1269 real-time systems.
1271 nohz= [KNL] Boottime enable/disable dynamic ticks
1272 Valid arguments: on, off
1273 Default: on
1275 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1277 noirqdebug [X86-32] Disables the code which attempts to detect and
1278 disable unhandled interrupt sources.
1280 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1281 broken timer IRQ sources.
1283 noisapnp [ISAPNP] Disables ISA PnP code.
1285 noinitrd [RAM] Tells the kernel not to load any configured
1286 initial RAM disk.
1288 nointroute [IA-64]
1290 nojitter [IA64] Disables jitter checking for ITC timers.
1292 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1294 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1296 noltlbs [PPC] Do not use large page/tlb entries for kernel
1297 lowmem mapping on PPC40x.
1299 nomca [IA-64] Disable machine check abort handling
1301 nomce [X86-32] Machine Check Exception
1303 nomfgpt [X86-32] Disable Multi-Function General Purpose
1304 Timer usage (for AMD Geode machines).
1306 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1308 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1309 with UP alternatives
1311 noresidual [PPC] Don't use residual data on PReP machines.
1313 noresume [SWSUSP] Disables resume and restores original swap
1314 space.
1316 no-scroll [VGA] Disables scrollback.
1317 This is required for the Braillex ib80-piezo Braille
1318 reader made by F.H. Papenmeier (Germany).
1320 nosbagart [IA-64]
1322 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1324 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1325 and disable the IO APIC. legacy for "maxcpus=0".
1327 nosoftlockup [KNL] Disable the soft-lockup detector.
1329 nosync [HW,M68K] Disables sync negotiation for all devices.
1331 notsc [BUGS=X86-32] Disable Time Stamp Counter
1333 nousb [USB] Disable the USB subsystem
1335 nowb [ARM]
1337 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1338 one of ['zone', 'node', 'default'] can be specified
1339 This can be set from sysctl after boot.
1340 See Documentation/sysctl/vm.txt for details.
1342 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1344 opl3= [HW,OSS]
1345 Format: <io>
1347 oprofile.timer= [HW]
1348 Use timer interrupt instead of performance counters
1350 osst= [HW,SCSI] SCSI Tape Driver
1351 Format: <buffer_size>,<write_threshold>
1352 See also Documentation/scsi/st.txt.
1354 panic= [KNL] Kernel behaviour on panic
1355 Format: <timeout>
1357 parkbd.port= [HW] Parallel port number the keyboard adapter is
1358 connected to, default is 0.
1359 Format: <parport#>
1360 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1361 0 for XT, 1 for AT (default is AT).
1362 Format: <mode>
1364 parport= [HW,PPT] Specify parallel ports. 0 disables.
1365 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1366 Use 'auto' to force the driver to use any
1367 IRQ/DMA settings detected (the default is to
1368 ignore detected IRQ/DMA settings because of
1369 possible conflicts). You can specify the base
1370 address, IRQ, and DMA settings; IRQ and DMA
1371 should be numbers, or 'auto' (for using detected
1372 settings on that particular port), or 'nofifo'
1373 (to avoid using a FIFO even if it is detected).
1374 Parallel ports are assigned in the order they
1375 are specified on the command line, starting
1376 with parport0.
1378 parport_init_mode= [HW,PPT]
1379 Configure VIA parallel port to operate in
1380 a specific mode. This is necessary on Pegasos
1381 computer where firmware has no options for setting
1382 up parallel port mode and sets it to spp.
1383 Currently this function knows 686a and 8231 chips.
1384 Format: [spp|ps2|epp|ecp|ecpepp]
1386 pas2= [HW,OSS] Format:
1387 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1389 pas16= [HW,SCSI]
1390 See header of drivers/scsi/pas16.c.
1392 pause_on_oops=
1393 Halt all CPUs after the first oops has been printed for
1394 the specified number of seconds. This is to be used if
1395 your oopses keep scrolling off the screen.
1397 pcbit= [HW,ISDN]
1399 pcd. [PARIDE]
1400 See header of drivers/block/paride/pcd.c.
1401 See also Documentation/paride.txt.
1403 pci=option[,option...] [PCI] various PCI subsystem options:
1404 off [X86-32] don't probe for the PCI bus
1405 bios [X86-32] force use of PCI BIOS, don't access
1406 the hardware directly. Use this if your machine
1407 has a non-standard PCI host bridge.
1408 nobios [X86-32] disallow use of PCI BIOS, only direct
1409 hardware access methods are allowed. Use this
1410 if you experience crashes upon bootup and you
1411 suspect they are caused by the BIOS.
1412 conf1 [X86-32] Force use of PCI Configuration
1413 Mechanism 1.
1414 conf2 [X86-32] Force use of PCI Configuration
1415 Mechanism 2.
1416 noaer [PCIE] If the PCIEAER kernel config parameter is
1417 enabled, this kernel boot option can be used to
1418 disable the use of PCIE advanced error reporting.
1419 nodomains [PCI] Disable support for multiple PCI
1420 root domains (aka PCI segments, in ACPI-speak).
1421 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1422 Configuration
1423 nomsi [MSI] If the PCI_MSI kernel config parameter is
1424 enabled, this kernel boot option can be used to
1425 disable the use of MSI interrupts system-wide.
1426 nosort [X86-32] Don't sort PCI devices according to
1427 order given by the PCI BIOS. This sorting is
1428 done to get a device order compatible with
1429 older kernels.
1430 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1431 routing table. These calls are known to be buggy
1432 on several machines and they hang the machine
1433 when used, but on other computers it's the only
1434 way to get the interrupt routing table. Try
1435 this option if the kernel is unable to allocate
1436 IRQs or discover secondary PCI buses on your
1437 motherboard.
1438 rom [X86-32] Assign address space to expansion ROMs.
1439 Use with caution as certain devices share
1440 address decoders between ROMs and other
1441 resources.
1442 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1443 assigned automatically to PCI devices. You can
1444 make the kernel exclude IRQs of your ISA cards
1445 this way.
1446 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1447 of the PIRQ table (normally generated
1448 by the BIOS) if it is outside the
1449 F0000h-100000h range.
1450 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1451 useful if the kernel is unable to find your
1452 secondary buses and you want to tell it
1453 explicitly which ones they are.
1454 assign-busses [X86-32] Always assign all PCI bus
1455 numbers ourselves, overriding
1456 whatever the firmware may have done.
1457 usepirqmask [X86-32] Honor the possible IRQ mask stored
1458 in the BIOS $PIR table. This is needed on
1459 some systems with broken BIOSes, notably
1460 some HP Pavilion N5400 and Omnibook XE3
1461 notebooks. This will have no effect if ACPI
1462 IRQ routing is enabled.
1463 noacpi [X86-32] Do not use ACPI for IRQ routing
1464 or for PCI scanning.
1465 use_crs [X86-32] Use _CRS for PCI resource
1466 allocation.
1467 routeirq Do IRQ routing for all PCI devices.
1468 This is normally done in pci_enable_device(),
1469 so this option is a temporary workaround
1470 for broken drivers that don't call it.
1471 firmware [ARM] Do not re-enumerate the bus but instead
1472 just use the configuration from the
1473 bootloader. This is currently used on
1474 IXP2000 systems where the bus has to be
1475 configured a certain way for adjunct CPUs.
1476 noearly [X86] Don't do any early type 1 scanning.
1477 This might help on some broken boards which
1478 machine check when some devices' config space
1479 is read. But various workarounds are disabled
1480 and some IOMMU drivers will not work.
1481 bfsort Sort PCI devices into breadth-first order.
1482 This sorting is done to get a device
1483 order compatible with older (<= 2.4) kernels.
1484 nobfsort Don't sort PCI devices into breadth-first order.
1485 cbiosize=nn[KMG] The fixed amount of bus space which is
1486 reserved for the CardBus bridge's IO window.
1487 The default value is 256 bytes.
1488 cbmemsize=nn[KMG] The fixed amount of bus space which is
1489 reserved for the CardBus bridge's memory
1490 window. The default value is 64 megabytes.
1492 pcmv= [HW,PCMCIA] BadgePAD 4
1494 pd. [PARIDE]
1495 See Documentation/paride.txt.
1497 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1498 boot time.
1499 Format: { 0 | 1 }
1500 See arch/parisc/kernel/pdc_chassis.c
1502 pf. [PARIDE]
1503 See Documentation/paride.txt.
1505 pg. [PARIDE]
1506 See Documentation/paride.txt.
1508 pirq= [SMP,APIC] Manual mp-table setup
1509 See Documentation/i386/IO-APIC.txt.
1511 plip= [PPT,NET] Parallel port network link
1512 Format: { parport<nr> | timid | 0 }
1513 See also Documentation/parport.txt.
1515 pnpacpi= [ACPI]
1516 { off }
1518 pnpbios= [ISAPNP]
1519 { on | off | curr | res | no-curr | no-res }
1521 pnp_reserve_irq=
1522 [ISAPNP] Exclude IRQs for the autoconfiguration
1524 pnp_reserve_dma=
1525 [ISAPNP] Exclude DMAs for the autoconfiguration
1527 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1528 Ranges are in pairs (I/O port base and size).
1530 pnp_reserve_mem=
1531 [ISAPNP] Exclude memory regions for the
1532 autoconfiguration.
1533 Ranges are in pairs (memory base and size).
1535 print-fatal-signals=
1536 [KNL] debug: print fatal signals
1537 print-fatal-signals=1: print segfault info to
1538 the kernel console.
1539 default: off.
1541 printk.time= Show timing data prefixed to each printk message line
1542 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1544 profile= [KNL] Enable kernel profiling via /proc/profile
1545 Format: [schedule,]<number>
1546 Param: "schedule" - profile schedule points.
1547 Param: <number> - step/bucket size as a power of 2 for
1548 statistical time based profiling.
1549 Param: "sleep" - profile D-state sleeping (millisecs).
1550 Requires CONFIG_SCHEDSTATS
1551 Param: "kvm" - profile VM exits.
1553 processor.max_cstate= [HW,ACPI]
1554 Limit processor to maximum C-state
1555 max_cstate=9 overrides any DMI blacklist limit.
1557 processor.nocst [HW,ACPI]
1558 Ignore the _CST method to determine C-states,
1559 instead using the legacy FADT method
1561 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1562 before loading.
1563 See Documentation/ramdisk.txt.
1565 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1566 probe for; one of (bare|imps|exps|lifebook|any).
1567 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1568 per second.
1569 psmouse.resetafter= [HW,MOUSE]
1570 Try to reset the device after so many bad packets
1571 (0 = never).
1572 psmouse.resolution=
1573 [HW,MOUSE] Set desired mouse resolution, in dpi.
1574 psmouse.smartscroll=
1575 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1576 0 = disabled, 1 = enabled (default).
1578 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1579 Format:
1580 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1582 pt. [PARIDE]
1583 See Documentation/paride.txt.
1585 pty.legacy_count=
1586 [KNL] Number of legacy pty's. Overwrites compiled-in
1587 default number.
1589 quiet [KNL] Disable most log messages
1591 r128= [HW,DRM]
1593 raid= [HW,RAID]
1594 See Documentation/md.txt.
1596 ramdisk_blocksize= [RAM]
1597 See Documentation/ramdisk.txt.
1599 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1600 See Documentation/ramdisk.txt.
1602 rcupdate.blimit= [KNL,BOOT]
1603 Set maximum number of finished RCU callbacks to process
1604 in one batch.
1606 rcupdate.qhimark= [KNL,BOOT]
1607 Set threshold of queued
1608 RCU callbacks over which batch limiting is disabled.
1610 rcupdate.qlowmark= [KNL,BOOT]
1611 Set threshold of queued RCU callbacks below which
1612 batch limiting is re-enabled.
1614 rdinit= [KNL]
1615 Format: <full_path>
1616 Run specified binary instead of /init from the ramdisk,
1617 used for early userspace startup. See initrd.
1619 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1620 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1621 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1623 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1625 reservetop= [X86-32]
1626 Format: nn[KMG]
1627 Reserves a hole at the top of the kernel virtual
1628 address space.
1630 reset_devices [KNL] Force drivers to reset the underlying device
1631 during initialization.
1633 resume= [SWSUSP]
1634 Specify the partition device for software suspend
1636 resume_offset= [SWSUSP]
1637 Specify the offset from the beginning of the partition
1638 given by "resume=" at which the swap header is located,
1639 in <PAGE_SIZE> units (needed only for swap files).
1640 See Documentation/power/swsusp-and-swap-files.txt
1642 retain_initrd [RAM] Keep initrd memory after extraction
1644 rhash_entries= [KNL,NET]
1645 Set number of hash buckets for route cache
1647 riscom8= [HW,SERIAL]
1648 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1650 ro [KNL] Mount root device read-only on boot
1652 root= [KNL] Root filesystem
1654 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1655 mount the root filesystem
1657 rootflags= [KNL] Set root filesystem mount option string
1659 rootfstype= [KNL] Set root filesystem type
1661 rootwait [KNL] Wait (indefinitely) for root device to show up.
1662 Useful for devices that are detected asynchronously
1663 (e.g. USB and MMC devices).
1665 root_plug.vendor_id=
1666 [ROOTPLUG] Override the default vendor ID
1668 root_plug.product_id=
1669 [ROOTPLUG] Override the default product ID
1671 root_plug.debug=
1672 [ROOTPLUG] Enable debugging output
1674 rw [KNL] Mount root device read-write on boot
1676 S [KNL] Run init in single mode
1678 sa1100ir [NET]
1679 See drivers/net/irda/sa1100_ir.c.
1681 sbni= [NET] Granch SBNI12 leased line adapter
1683 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1684 Format: <io>[,<timeout>[,<isapnp>]]
1686 scsi_debug_*= [SCSI]
1687 See drivers/scsi/scsi_debug.c.
1689 scsi_default_dev_flags=
1690 [SCSI] SCSI default device flags
1691 Format: <integer>
1693 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1694 Format: <vendor>:<model>:<flags>
1695 (flags are integer value)
1697 scsi_logging_level= [SCSI] a bit mask of logging levels
1698 See drivers/scsi/scsi_logging.h for bits. Also
1699 settable via sysctl at dev.scsi.logging_level
1700 (/proc/sys/dev/scsi/logging_level).
1701 There is also a nice 'scsi_logging_level' script in the
1702 S390-tools package, available for download at
1703 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1705 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1706 discovered. async scans them in kernel threads,
1707 allowing boot to proceed. none ignores them, expecting
1708 user space to do the scan.
1710 selinux [SELINUX] Disable or enable SELinux at boot time.
1711 Format: { "0" | "1" }
1712 See security/selinux/Kconfig help text.
1713 0 -- disable.
1714 1 -- enable.
1715 Default value is set via kernel config option.
1716 If enabled at boot time, /selinux/disable can be used
1717 later to disable prior to initial policy load.
1719 selinux_compat_net =
1720 [SELINUX] Set initial selinux_compat_net flag value.
1721 Format: { "0" | "1" }
1722 0 -- use new secmark-based packet controls
1723 1 -- use legacy packet controls
1724 Default value is 0 (preferred).
1725 Value can be changed at runtime via
1726 /selinux/compat_net.
1728 serialnumber [BUGS=X86-32]
1730 shapers= [NET]
1731 Maximal number of shapers.
1733 sim710= [SCSI,HW]
1734 See header of drivers/scsi/sim710.c.
1736 simeth= [IA-64]
1737 simscsi=
1739 slram= [HW,MTD]
1741 slub_debug[=options[,slabs]] [MM, SLUB]
1742 Enabling slub_debug allows one to determine the
1743 culprit if slab objects become corrupted. Enabling
1744 slub_debug can create guard zones around objects and
1745 may poison objects when not in use. Also tracks the
1746 last alloc / free. For more information see
1747 Documentation/vm/slub.txt.
1749 slub_max_order= [MM, SLUB]
1750 Determines the maximum allowed order for slabs.
1751 A high setting may cause OOMs due to memory
1752 fragmentation. For more information see
1753 Documentation/vm/slub.txt.
1755 slub_min_objects= [MM, SLUB]
1756 The minimum number of objects per slab. SLUB will
1757 increase the slab order up to slub_max_order to
1758 generate a sufficiently large slab able to contain
1759 the number of objects indicated. The higher the number
1760 of objects the smaller the overhead of tracking slabs
1761 and the less frequently locks need to be acquired.
1762 For more information see Documentation/vm/slub.txt.
1764 slub_min_order= [MM, SLUB]
1765 Determines the mininum page order for slabs. Must be
1766 lower than slub_max_order.
1767 For more information see Documentation/vm/slub.txt.
1769 slub_nomerge [MM, SLUB]
1770 Disable merging of slabs with similar size. May be
1771 necessary if there is some reason to distinguish
1772 allocs to different slabs. Debug options disable
1773 merging on their own.
1774 For more information see Documentation/vm/slub.txt.
1776 smart2= [HW]
1777 Format: <io1>[,<io2>[,...,<io8>]]
1779 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1780 attempt to substitute SMP alternatives once at boot.
1782 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1783 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1784 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1785 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1786 smsc-ircc2.ircc_irq= [HW] IRQ line
1787 smsc-ircc2.ircc_dma= [HW] DMA channel
1788 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1789 0: Toshiba Satellite 1800 (GP data pin select)
1790 1: Fast pin select (default)
1791 2: ATC IRMode
1793 snd-ad1816a= [HW,ALSA]
1795 snd-ad1848= [HW,ALSA]
1797 snd-ali5451= [HW,ALSA]
1799 snd-als100= [HW,ALSA]
1801 snd-als4000= [HW,ALSA]
1803 snd-azt2320= [HW,ALSA]
1805 snd-cmi8330= [HW,ALSA]
1807 snd-cmipci= [HW,ALSA]
1809 snd-cs4231= [HW,ALSA]
1811 snd-cs4232= [HW,ALSA]
1813 snd-cs4236= [HW,ALSA]
1815 snd-cs4281= [HW,ALSA]
1817 snd-cs46xx= [HW,ALSA]
1819 snd-dt019x= [HW,ALSA]
1821 snd-dummy= [HW,ALSA]
1823 snd-emu10k1= [HW,ALSA]
1825 snd-ens1370= [HW,ALSA]
1827 snd-ens1371= [HW,ALSA]
1829 snd-es968= [HW,ALSA]
1831 snd-es1688= [HW,ALSA]
1833 snd-es18xx= [HW,ALSA]
1835 snd-es1938= [HW,ALSA]
1837 snd-es1968= [HW,ALSA]
1839 snd-fm801= [HW,ALSA]
1841 snd-gusclassic= [HW,ALSA]
1843 snd-gusextreme= [HW,ALSA]
1845 snd-gusmax= [HW,ALSA]
1847 snd-hdsp= [HW,ALSA]
1849 snd-ice1712= [HW,ALSA]
1851 snd-intel8x0= [HW,ALSA]
1853 snd-interwave= [HW,ALSA]
1855 snd-interwave-stb=
1856 [HW,ALSA]
1858 snd-korg1212= [HW,ALSA]
1860 snd-maestro3= [HW,ALSA]
1862 snd-mpu401= [HW,ALSA]
1864 snd-mtpav= [HW,ALSA]
1866 snd-nm256= [HW,ALSA]
1868 snd-opl3sa2= [HW,ALSA]
1870 snd-opti92x-ad1848=
1871 [HW,ALSA]
1873 snd-opti92x-cs4231=
1874 [HW,ALSA]
1876 snd-opti93x= [HW,ALSA]
1878 snd-pmac= [HW,ALSA]
1880 snd-rme32= [HW,ALSA]
1882 snd-rme96= [HW,ALSA]
1884 snd-rme9652= [HW,ALSA]
1886 snd-sb8= [HW,ALSA]
1888 snd-sb16= [HW,ALSA]
1890 snd-sbawe= [HW,ALSA]
1892 snd-serial= [HW,ALSA]
1894 snd-sgalaxy= [HW,ALSA]
1896 snd-sonicvibes= [HW,ALSA]
1898 snd-sun-amd7930=
1899 [HW,ALSA]
1901 snd-sun-cs4231= [HW,ALSA]
1903 snd-trident= [HW,ALSA]
1905 snd-usb-audio= [HW,ALSA,USB]
1907 snd-via82xx= [HW,ALSA]
1909 snd-virmidi= [HW,ALSA]
1911 snd-wavefront= [HW,ALSA]
1913 snd-ymfpci= [HW,ALSA]
1915 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1916 See Documentation/sonypi.txt
1918 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1919 See Documentation/specialix.txt.
1921 spia_io_base= [HW,MTD]
1922 spia_fio_base=
1923 spia_pedr=
1924 spia_peddr=
1926 sscape= [HW,OSS]
1927 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1929 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1930 See Documentation/scsi/st.txt.
1932 sti= [PARISC,HW]
1933 Format: <num>
1934 Set the STI (builtin display/keyboard on the HP-PARISC
1935 machines) console (graphic card) which should be used
1936 as the initial boot-console.
1937 See also comment in drivers/video/console/sticore.c.
1939 sti_font= [HW]
1940 See comment in drivers/video/console/sticore.c.
1942 stifb= [HW]
1943 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1945 sunrpc.pool_mode=
1946 [NFS]
1947 Control how the NFS server code allocates CPUs to
1948 service thread pools. Depending on how many NICs
1949 you have and where their interrupts are bound, this
1950 option will affect which CPUs will do NFS serving.
1951 Note: this parameter cannot be changed while the
1952 NFS server is running.
1954 auto the server chooses an appropriate mode
1955 automatically using heuristics
1956 global a single global pool contains all CPUs
1957 percpu one pool for each CPU
1958 pernode one pool for each NUMA node (equivalent
1959 to global on non-NUMA machines)
1961 swiotlb= [IA-64] Number of I/O TLB slabs
1963 switches= [HW,M68k]
1965 sym53c416= [HW,SCSI]
1966 See header of drivers/scsi/sym53c416.c.
1968 sysrq_always_enabled
1969 [KNL]
1970 Ignore sysrq setting - this boot parameter will
1971 neutralize any effect of /proc/sys/kernel/sysrq.
1972 Useful for debugging.
1974 t128= [HW,SCSI]
1975 See header of drivers/scsi/t128.c.
1977 tdfx= [HW,DRM]
1979 thash_entries= [KNL,NET]
1980 Set number of hash buckets for TCP connection
1982 thermal.act= [HW,ACPI]
1983 -1: disable all active trip points in all thermal zones
1984 <degrees C>: override all lowest active trip points
1986 thermal.crt= [HW,ACPI]
1987 -1: disable all critical trip points in all thermal zones
1988 <degrees C>: lower all critical trip points
1990 thermal.nocrt= [HW,ACPI]
1991 Set to disable actions on ACPI thermal zone
1992 critical and hot trip points.
1994 thermal.off= [HW,ACPI]
1995 1: disable ACPI thermal control
1997 thermal.psv= [HW,ACPI]
1998 -1: disable all passive trip points
1999 <degrees C>: override all passive trip points to this value
2001 thermal.tzp= [HW,ACPI]
2002 Specify global default ACPI thermal zone polling rate
2003 <deci-seconds>: poll all this frequency
2004 0: no polling (default)
2006 tipar.timeout= [HW,PPT]
2007 Set communications timeout in tenths of a second
2008 (default 15).
2010 tipar.delay= [HW,PPT]
2011 Set inter-bit delay in microseconds (default 10).
2013 tmscsim= [HW,SCSI]
2014 See comment before function dc390_setup() in
2015 drivers/scsi/tmscsim.c.
2017 tp720= [HW,PS2]
2019 trix= [HW,OSS] MediaTrix AudioTrix Pro
2020 Format:
2021 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2023 turbografx.map[2|3]= [HW,JOY]
2024 TurboGraFX parallel port interface
2025 Format:
2026 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2027 See also Documentation/input/joystick-parport.txt
2029 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2030 See header of drivers/scsi/u14-34f.c.
2032 uart401= [HW,OSS]
2033 Format: <io>,<irq>
2035 uart6850= [HW,OSS]
2036 Format: <io>,<irq>
2038 uhci-hcd.ignore_oc=
2039 [USB] Ignore overcurrent events (default N).
2040 Some badly-designed motherboards generate lots of
2041 bogus events, for ports that aren't wired to
2042 anything. Set this parameter to avoid log spamming.
2043 Note that genuine overcurrent events won't be
2044 reported either.
2046 usbcore.autosuspend=
2047 [USB] The autosuspend time delay (in seconds) used
2048 for newly-detected USB devices (default 2). This
2049 is the time required before an idle device will be
2050 autosuspended. Devices for which the delay is set
2051 to a negative value won't be autosuspended at all.
2053 usbhid.mousepoll=
2054 [USBHID] The interval which mice are to be polled at.
2056 vdso= [X86-32,SH,x86-64]
2057 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2058 vdso=1: enable VDSO (default)
2059 vdso=0: disable VDSO mapping
2061 vdso32= [X86-32,X86-64]
2062 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2063 vdso32=1: enable 32-bit VDSO (default)
2064 vdso32=0: disable 32-bit VDSO mapping
2066 vector= [IA-64,SMP]
2067 vector=percpu: enable percpu vector domain
2069 video= [FB] Frame buffer configuration
2070 See Documentation/fb/modedb.txt.
2072 vga= [BOOT,X86-32] Select a particular video mode
2073 See Documentation/i386/boot.txt and
2074 Documentation/svga.txt.
2075 Use vga=ask for menu.
2076 This is actually a boot loader parameter; the value is
2077 passed to the kernel using a special protocol.
2079 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2080 size of <nn>. This can be used to increase the
2081 minimum size (128MB on x86). It can also be used to
2082 decrease the size and leave more room for directly
2083 mapped kernel RAM.
2085 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2086 Format: <command>
2088 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2089 Format: <command>
2091 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2092 Format: <command>
2094 waveartist= [HW,OSS]
2095 Format: <io>,<irq>,<dma>,<dma2>
2097 wd33c93= [HW,SCSI]
2098 See header of drivers/scsi/wd33c93.c.
2100 wd7000= [HW,SCSI]
2101 See header of drivers/scsi/wd7000.c.
2103 wdt= [WDT] Watchdog
2104 See Documentation/watchdog/wdt.txt.
2106 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2107 xd_geo= See header of drivers/block/xd.c.
2109 xirc2ps_cs= [NET,PCMCIA]
2110 Format:
2111 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2113 norandmaps Don't use address space randomization
2114 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2116 ______________________________________________________________________
2118 TODO:
2120 Add documentation for ALSA options.
2121 Add more DRM drivers.