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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/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/ide.txt.
771 ide?= [HW] (E)IDE subsystem
772 Format: ide?=noprobe or chipset specific parameters.
773 See Documentation/ide/ide.txt.
775 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
776 See Documentation/ide/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 libata.force= [LIBATA] Force configurations. The format is comma
954 separated list of "[ID:]VAL" where ID is
955 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
956 matching port, link or device. Basically, it matches
957 the ATA ID string printed on console by libata. If
958 the whole ID part is omitted, the last PORT and DEVICE
959 values are used. If ID hasn't been specified yet, the
960 configuration applies to all ports, links and devices.
962 If only DEVICE is omitted, the parameter applies to
963 the port and all links and devices behind it. DEVICE
964 number of 0 either selects the first device or the
965 first fan-out link behind PMP device. It does not
966 select the host link. DEVICE number of 15 selects the
967 host link and device attached to it.
969 The VAL specifies the configuration to force. As long
970 as there's no ambiguity shortcut notation is allowed.
971 For example, both 1.5 and 1.5G would work for 1.5Gbps.
972 The following configurations can be forced.
974 * Cable type: 40c, 80c, short40c, unk, ign or sata.
975 Any ID with matching PORT is used.
977 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
979 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
980 udma[/][16,25,33,44,66,100,133] notation is also
981 allowed.
983 * [no]ncq: Turn on or off NCQ.
985 If there are multiple matching configurations changing
986 the same attribute, the last one is used.
988 load_ramdisk= [RAM] List of ramdisks to load from floppy
989 See Documentation/ramdisk.txt.
991 lockd.nlm_grace_period=P [NFS] Assign grace period.
992 Format: <integer>
994 lockd.nlm_tcpport=N [NFS] Assign TCP port.
995 Format: <integer>
997 lockd.nlm_timeout=T [NFS] Assign timeout value.
998 Format: <integer>
1000 lockd.nlm_udpport=M [NFS] Assign UDP port.
1001 Format: <integer>
1003 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1004 Format: <irq>
1006 loglevel= All Kernel Messages with a loglevel smaller than the
1007 console loglevel will be printed to the console. It can
1008 also be changed with klogd or other programs. The
1009 loglevels are defined as follows:
1011 0 (KERN_EMERG) system is unusable
1012 1 (KERN_ALERT) action must be taken immediately
1013 2 (KERN_CRIT) critical conditions
1014 3 (KERN_ERR) error conditions
1015 4 (KERN_WARNING) warning conditions
1016 5 (KERN_NOTICE) normal but significant condition
1017 6 (KERN_INFO) informational
1018 7 (KERN_DEBUG) debug-level messages
1020 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1021 Format: { n | nk | nM }
1022 n must be a power of two. The default size
1023 is set in the kernel config file.
1025 logo.nologo [FB] Disables display of the built-in Linux logo.
1026 This may be used to provide more screen space for
1027 kernel log messages and is useful when debugging
1028 kernel boot problems.
1030 lp=0 [LP] Specify parallel ports to use, e.g,
1031 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1032 lp=reset first parallel port). 'lp=0' disables the
1033 lp=auto printer driver. 'lp=reset' (which can be
1034 specified in addition to the ports) causes
1035 attached printers to be reset. Using
1036 lp=port1,port2,... specifies the parallel ports
1037 to associate lp devices with, starting with
1038 lp0. A port specification may be 'none' to skip
1039 that lp device, or a parport name such as
1040 'parport0'. Specifying 'lp=auto' instead of a
1041 port specification list means that device IDs
1042 from each port should be examined, to see if
1043 an IEEE 1284-compliant printer is attached; if
1044 so, the driver will manage that printer.
1045 See also header of drivers/char/lp.c.
1047 lpj=n [KNL]
1048 Sets loops_per_jiffy to given constant, thus avoiding
1049 time-consuming boot-time autodetection (up to 250 ms per
1050 CPU). 0 enables autodetection (default). To determine
1051 the correct value for your kernel, boot with normal
1052 autodetection and see what value is printed. Note that
1053 on SMP systems the preset will be applied to all CPUs,
1054 which is likely to cause problems if your CPUs need
1055 significantly divergent settings. An incorrect value
1056 will cause delays in the kernel to be wrong, leading to
1057 unpredictable I/O errors and other breakage. Although
1058 unlikely, in the extreme case this might damage your
1059 hardware.
1061 ltpc= [NET]
1062 Format: <io>,<irq>,<dma>
1064 mac5380= [HW,SCSI] Format:
1065 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1067 mac53c9x= [HW,SCSI] Format:
1068 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1070 machvec= [IA64] Force the use of a particular machine-vector
1071 (machvec) in a generic kernel.
1072 Example: machvec=hpzx1_swiotlb
1074 max_loop= [LOOP] Maximum number of loopback devices that can
1075 be mounted
1076 Format: <1-256>
1078 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1079 should make use of. maxcpus=n : n >= 0 limits the
1080 kernel to using 'n' processors. n=0 is a special case,
1081 it is equivalent to "nosmp", which also disables
1082 the IO APIC.
1084 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1085 equal to this physical address is ignored.
1087 max_luns= [SCSI] Maximum number of LUNs to probe.
1088 Should be between 1 and 2^32-1.
1090 max_report_luns=
1091 [SCSI] Maximum number of LUNs received.
1092 Should be between 1 and 16384.
1094 mcatest= [IA-64]
1096 mce [X86-32] Machine Check Exception
1098 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1100 md= [HW] RAID subsystems devices and level
1101 See Documentation/md.txt.
1103 mdacon= [MDA]
1104 Format: <first>,<last>
1105 Specifies range of consoles to be captured by the MDA.
1107 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1108 Amount of memory to be used when the kernel is not able
1109 to see the whole system memory or for test.
1110 [X86-32] Use together with memmap= to avoid physical
1111 address space collisions. Without memmap= PCI devices
1112 could be placed at addresses belonging to unused RAM.
1114 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1115 memory.
1117 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1118 E820 memory map, as specified by the user.
1119 Such memmap=exactmap lines can be constructed based on
1120 BIOS output or other requirements. See the memmap=nn@ss
1121 option description.
1123 memmap=nn[KMG]@ss[KMG]
1124 [KNL] Force usage of a specific region of memory
1125 Region of memory to be used, from ss to ss+nn.
1127 memmap=nn[KMG]#ss[KMG]
1128 [KNL,ACPI] Mark specific memory as ACPI data.
1129 Region of memory to be used, from ss to ss+nn.
1131 memmap=nn[KMG]$ss[KMG]
1132 [KNL,ACPI] Mark specific memory as reserved.
1133 Region of memory to be used, from ss to ss+nn.
1135 meye.*= [HW] Set MotionEye Camera parameters
1136 See Documentation/video4linux/meye.txt.
1138 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1139 Multi-Function General Purpose Timers on AMD Geode
1140 platforms.
1142 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1143 the BIOS has incorrectly applied a workaround. TinyBIOS
1144 version 0.98 is known to be affected, 0.99 fixes the
1145 problem by letting the user disable the workaround.
1147 mga= [HW,DRM]
1149 mousedev.tap_time=
1150 [MOUSE] Maximum time between finger touching and
1151 leaving touchpad surface for touch to be considered
1152 a tap and be reported as a left button click (for
1153 touchpads working in absolute mode only).
1154 Format: <msecs>
1155 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1156 reporting absolute coordinates, such as tablets
1157 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1158 reporting absolute coordinates, such as tablets
1160 mpu401= [HW,OSS]
1161 Format: <io>,<irq>
1163 MTD_Partition= [MTD]
1164 Format: <name>,<region-number>,<size>,<offset>
1166 MTD_Region= [MTD] Format:
1167 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1169 mtdparts= [MTD]
1170 See drivers/mtd/cmdlinepart.c.
1172 mtouchusb.raw_coordinates=
1173 [HW] Make the MicroTouch USB driver use raw coordinates
1174 ('y', default) or cooked coordinates ('n')
1176 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1178 NCR_D700= [HW,SCSI]
1179 See header of drivers/scsi/NCR_D700.c.
1181 ncr5380= [HW,SCSI]
1183 ncr53c400= [HW,SCSI]
1185 ncr53c400a= [HW,SCSI]
1187 ncr53c406a= [HW,SCSI]
1189 ncr53c8xx= [HW,SCSI]
1191 netdev= [NET] Network devices parameters
1192 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1193 Note that mem_start is often overloaded to mean
1194 something different and driver-specific.
1195 This usage is only documented in each driver source
1196 file if at all.
1198 nfsaddrs= [NFS]
1199 See Documentation/nfsroot.txt.
1201 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1202 See Documentation/nfsroot.txt.
1204 nfs.callback_tcpport=
1205 [NFS] set the TCP port on which the NFSv4 callback
1206 channel should listen.
1208 nfs.idmap_cache_timeout=
1209 [NFS] set the maximum lifetime for idmapper cache
1210 entries.
1212 nfs.enable_ino64=
1213 [NFS] enable 64-bit inode numbers.
1214 If zero, the NFS client will fake up a 32-bit inode
1215 number for the readdir() and stat() syscalls instead
1216 of returning the full 64-bit number.
1217 The default is to return 64-bit inode numbers.
1219 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1220 when a NMI is triggered.
1221 Format: [state][,regs][,debounce][,die]
1223 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1225 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1226 emulation library even if a 387 maths coprocessor
1227 is present.
1229 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1230 caches in the slab allocator. Saves per-node memory,
1231 but will impact performance.
1233 noalign [KNL,ARM]
1235 noapic [SMP,APIC] Tells the kernel to not make use of any
1236 IOAPICs that may be present in the system.
1238 nobats [PPC] Do not use BATs for mapping kernel lowmem
1239 on "Classic" PPC cores.
1241 nocache [ARM]
1243 nodelayacct [KNL] Disable per-task delay accounting
1245 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1247 noefi [X86-32,X86-64] Disable EFI runtime services support.
1249 noexec [IA-64]
1251 noexec [X86-32,X86-64]
1252 noexec=on: enable non-executable mappings (default)
1253 noexec=off: disable nn-executable mappings
1255 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1256 register save and restore. The kernel will only save
1257 legacy floating-point registers on task switch.
1259 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1261 nohlt [BUGS=ARM]
1263 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1264 instruction doesn't work correctly and not to
1265 use it.
1267 nohalt [IA-64] Tells the kernel not to use the power saving
1268 function PAL_HALT_LIGHT when idle. This increases
1269 power-consumption. On the positive side, it reduces
1270 interrupt wake-up latency, which may improve performance
1271 in certain environments such as networked servers or
1272 real-time systems.
1274 nohz= [KNL] Boottime enable/disable dynamic ticks
1275 Valid arguments: on, off
1276 Default: on
1278 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1280 noirqdebug [X86-32] Disables the code which attempts to detect and
1281 disable unhandled interrupt sources.
1283 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1284 broken timer IRQ sources.
1286 noisapnp [ISAPNP] Disables ISA PnP code.
1288 noinitrd [RAM] Tells the kernel not to load any configured
1289 initial RAM disk.
1291 nointroute [IA-64]
1293 nojitter [IA64] Disables jitter checking for ITC timers.
1295 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1297 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1299 noltlbs [PPC] Do not use large page/tlb entries for kernel
1300 lowmem mapping on PPC40x.
1302 nomca [IA-64] Disable machine check abort handling
1304 nomce [X86-32] Machine Check Exception
1306 nomfgpt [X86-32] Disable Multi-Function General Purpose
1307 Timer usage (for AMD Geode machines).
1309 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1311 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1312 with UP alternatives
1314 noresidual [PPC] Don't use residual data on PReP machines.
1316 noresume [SWSUSP] Disables resume and restores original swap
1317 space.
1319 no-scroll [VGA] Disables scrollback.
1320 This is required for the Braillex ib80-piezo Braille
1321 reader made by F.H. Papenmeier (Germany).
1323 nosbagart [IA-64]
1325 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1327 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1328 and disable the IO APIC. legacy for "maxcpus=0".
1330 nosoftlockup [KNL] Disable the soft-lockup detector.
1332 nosync [HW,M68K] Disables sync negotiation for all devices.
1334 notsc [BUGS=X86-32] Disable Time Stamp Counter
1336 nousb [USB] Disable the USB subsystem
1338 nowb [ARM]
1340 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1341 one of ['zone', 'node', 'default'] can be specified
1342 This can be set from sysctl after boot.
1343 See Documentation/sysctl/vm.txt for details.
1345 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1347 opl3= [HW,OSS]
1348 Format: <io>
1350 oprofile.timer= [HW]
1351 Use timer interrupt instead of performance counters
1353 osst= [HW,SCSI] SCSI Tape Driver
1354 Format: <buffer_size>,<write_threshold>
1355 See also Documentation/scsi/st.txt.
1357 panic= [KNL] Kernel behaviour on panic
1358 Format: <timeout>
1360 parkbd.port= [HW] Parallel port number the keyboard adapter is
1361 connected to, default is 0.
1362 Format: <parport#>
1363 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1364 0 for XT, 1 for AT (default is AT).
1365 Format: <mode>
1367 parport= [HW,PPT] Specify parallel ports. 0 disables.
1368 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1369 Use 'auto' to force the driver to use any
1370 IRQ/DMA settings detected (the default is to
1371 ignore detected IRQ/DMA settings because of
1372 possible conflicts). You can specify the base
1373 address, IRQ, and DMA settings; IRQ and DMA
1374 should be numbers, or 'auto' (for using detected
1375 settings on that particular port), or 'nofifo'
1376 (to avoid using a FIFO even if it is detected).
1377 Parallel ports are assigned in the order they
1378 are specified on the command line, starting
1379 with parport0.
1381 parport_init_mode= [HW,PPT]
1382 Configure VIA parallel port to operate in
1383 a specific mode. This is necessary on Pegasos
1384 computer where firmware has no options for setting
1385 up parallel port mode and sets it to spp.
1386 Currently this function knows 686a and 8231 chips.
1387 Format: [spp|ps2|epp|ecp|ecpepp]
1389 pas2= [HW,OSS] Format:
1390 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1392 pas16= [HW,SCSI]
1393 See header of drivers/scsi/pas16.c.
1395 pause_on_oops=
1396 Halt all CPUs after the first oops has been printed for
1397 the specified number of seconds. This is to be used if
1398 your oopses keep scrolling off the screen.
1400 pcbit= [HW,ISDN]
1402 pcd. [PARIDE]
1403 See header of drivers/block/paride/pcd.c.
1404 See also Documentation/paride.txt.
1406 pci=option[,option...] [PCI] various PCI subsystem options:
1407 off [X86-32] don't probe for the PCI bus
1408 bios [X86-32] force use of PCI BIOS, don't access
1409 the hardware directly. Use this if your machine
1410 has a non-standard PCI host bridge.
1411 nobios [X86-32] disallow use of PCI BIOS, only direct
1412 hardware access methods are allowed. Use this
1413 if you experience crashes upon bootup and you
1414 suspect they are caused by the BIOS.
1415 conf1 [X86-32] Force use of PCI Configuration
1416 Mechanism 1.
1417 conf2 [X86-32] Force use of PCI Configuration
1418 Mechanism 2.
1419 noaer [PCIE] If the PCIEAER kernel config parameter is
1420 enabled, this kernel boot option can be used to
1421 disable the use of PCIE advanced error reporting.
1422 nodomains [PCI] Disable support for multiple PCI
1423 root domains (aka PCI segments, in ACPI-speak).
1424 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1425 Configuration
1426 nomsi [MSI] If the PCI_MSI kernel config parameter is
1427 enabled, this kernel boot option can be used to
1428 disable the use of MSI interrupts system-wide.
1429 nosort [X86-32] Don't sort PCI devices according to
1430 order given by the PCI BIOS. This sorting is
1431 done to get a device order compatible with
1432 older kernels.
1433 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1434 routing table. These calls are known to be buggy
1435 on several machines and they hang the machine
1436 when used, but on other computers it's the only
1437 way to get the interrupt routing table. Try
1438 this option if the kernel is unable to allocate
1439 IRQs or discover secondary PCI buses on your
1440 motherboard.
1441 rom [X86-32] Assign address space to expansion ROMs.
1442 Use with caution as certain devices share
1443 address decoders between ROMs and other
1444 resources.
1445 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1446 assigned automatically to PCI devices. You can
1447 make the kernel exclude IRQs of your ISA cards
1448 this way.
1449 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1450 of the PIRQ table (normally generated
1451 by the BIOS) if it is outside the
1452 F0000h-100000h range.
1453 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1454 useful if the kernel is unable to find your
1455 secondary buses and you want to tell it
1456 explicitly which ones they are.
1457 assign-busses [X86-32] Always assign all PCI bus
1458 numbers ourselves, overriding
1459 whatever the firmware may have done.
1460 usepirqmask [X86-32] Honor the possible IRQ mask stored
1461 in the BIOS $PIR table. This is needed on
1462 some systems with broken BIOSes, notably
1463 some HP Pavilion N5400 and Omnibook XE3
1464 notebooks. This will have no effect if ACPI
1465 IRQ routing is enabled.
1466 noacpi [X86-32] Do not use ACPI for IRQ routing
1467 or for PCI scanning.
1468 use_crs [X86-32] Use _CRS for PCI resource
1469 allocation.
1470 routeirq Do IRQ routing for all PCI devices.
1471 This is normally done in pci_enable_device(),
1472 so this option is a temporary workaround
1473 for broken drivers that don't call it.
1474 firmware [ARM] Do not re-enumerate the bus but instead
1475 just use the configuration from the
1476 bootloader. This is currently used on
1477 IXP2000 systems where the bus has to be
1478 configured a certain way for adjunct CPUs.
1479 noearly [X86] Don't do any early type 1 scanning.
1480 This might help on some broken boards which
1481 machine check when some devices' config space
1482 is read. But various workarounds are disabled
1483 and some IOMMU drivers will not work.
1484 bfsort Sort PCI devices into breadth-first order.
1485 This sorting is done to get a device
1486 order compatible with older (<= 2.4) kernels.
1487 nobfsort Don't sort PCI devices into breadth-first order.
1488 cbiosize=nn[KMG] The fixed amount of bus space which is
1489 reserved for the CardBus bridge's IO window.
1490 The default value is 256 bytes.
1491 cbmemsize=nn[KMG] The fixed amount of bus space which is
1492 reserved for the CardBus bridge's memory
1493 window. The default value is 64 megabytes.
1495 pcmv= [HW,PCMCIA] BadgePAD 4
1497 pd. [PARIDE]
1498 See Documentation/paride.txt.
1500 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1501 boot time.
1502 Format: { 0 | 1 }
1503 See arch/parisc/kernel/pdc_chassis.c
1505 pf. [PARIDE]
1506 See Documentation/paride.txt.
1508 pg. [PARIDE]
1509 See Documentation/paride.txt.
1511 pirq= [SMP,APIC] Manual mp-table setup
1512 See Documentation/i386/IO-APIC.txt.
1514 plip= [PPT,NET] Parallel port network link
1515 Format: { parport<nr> | timid | 0 }
1516 See also Documentation/parport.txt.
1518 pnpacpi= [ACPI]
1519 { off }
1521 pnpbios= [ISAPNP]
1522 { on | off | curr | res | no-curr | no-res }
1524 pnp_reserve_irq=
1525 [ISAPNP] Exclude IRQs for the autoconfiguration
1527 pnp_reserve_dma=
1528 [ISAPNP] Exclude DMAs for the autoconfiguration
1530 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1531 Ranges are in pairs (I/O port base and size).
1533 pnp_reserve_mem=
1534 [ISAPNP] Exclude memory regions for the
1535 autoconfiguration.
1536 Ranges are in pairs (memory base and size).
1538 print-fatal-signals=
1539 [KNL] debug: print fatal signals
1540 print-fatal-signals=1: print segfault info to
1541 the kernel console.
1542 default: off.
1544 printk.time= Show timing data prefixed to each printk message line
1545 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1547 profile= [KNL] Enable kernel profiling via /proc/profile
1548 Format: [schedule,]<number>
1549 Param: "schedule" - profile schedule points.
1550 Param: <number> - step/bucket size as a power of 2 for
1551 statistical time based profiling.
1552 Param: "sleep" - profile D-state sleeping (millisecs).
1553 Requires CONFIG_SCHEDSTATS
1554 Param: "kvm" - profile VM exits.
1556 processor.max_cstate= [HW,ACPI]
1557 Limit processor to maximum C-state
1558 max_cstate=9 overrides any DMI blacklist limit.
1560 processor.nocst [HW,ACPI]
1561 Ignore the _CST method to determine C-states,
1562 instead using the legacy FADT method
1564 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1565 before loading.
1566 See Documentation/ramdisk.txt.
1568 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1569 probe for; one of (bare|imps|exps|lifebook|any).
1570 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1571 per second.
1572 psmouse.resetafter= [HW,MOUSE]
1573 Try to reset the device after so many bad packets
1574 (0 = never).
1575 psmouse.resolution=
1576 [HW,MOUSE] Set desired mouse resolution, in dpi.
1577 psmouse.smartscroll=
1578 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1579 0 = disabled, 1 = enabled (default).
1581 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1582 Format:
1583 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1585 pt. [PARIDE]
1586 See Documentation/paride.txt.
1588 pty.legacy_count=
1589 [KNL] Number of legacy pty's. Overwrites compiled-in
1590 default number.
1592 quiet [KNL] Disable most log messages
1594 r128= [HW,DRM]
1596 raid= [HW,RAID]
1597 See Documentation/md.txt.
1599 ramdisk_blocksize= [RAM]
1600 See Documentation/ramdisk.txt.
1602 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1603 See Documentation/ramdisk.txt.
1605 rcupdate.blimit= [KNL,BOOT]
1606 Set maximum number of finished RCU callbacks to process
1607 in one batch.
1609 rcupdate.qhimark= [KNL,BOOT]
1610 Set threshold of queued
1611 RCU callbacks over which batch limiting is disabled.
1613 rcupdate.qlowmark= [KNL,BOOT]
1614 Set threshold of queued RCU callbacks below which
1615 batch limiting is re-enabled.
1617 rdinit= [KNL]
1618 Format: <full_path>
1619 Run specified binary instead of /init from the ramdisk,
1620 used for early userspace startup. See initrd.
1622 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1623 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1624 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1626 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1628 reservetop= [X86-32]
1629 Format: nn[KMG]
1630 Reserves a hole at the top of the kernel virtual
1631 address space.
1633 reset_devices [KNL] Force drivers to reset the underlying device
1634 during initialization.
1636 resume= [SWSUSP]
1637 Specify the partition device for software suspend
1639 resume_offset= [SWSUSP]
1640 Specify the offset from the beginning of the partition
1641 given by "resume=" at which the swap header is located,
1642 in <PAGE_SIZE> units (needed only for swap files).
1643 See Documentation/power/swsusp-and-swap-files.txt
1645 retain_initrd [RAM] Keep initrd memory after extraction
1647 rhash_entries= [KNL,NET]
1648 Set number of hash buckets for route cache
1650 riscom8= [HW,SERIAL]
1651 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1653 ro [KNL] Mount root device read-only on boot
1655 root= [KNL] Root filesystem
1657 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1658 mount the root filesystem
1660 rootflags= [KNL] Set root filesystem mount option string
1662 rootfstype= [KNL] Set root filesystem type
1664 rootwait [KNL] Wait (indefinitely) for root device to show up.
1665 Useful for devices that are detected asynchronously
1666 (e.g. USB and MMC devices).
1668 root_plug.vendor_id=
1669 [ROOTPLUG] Override the default vendor ID
1671 root_plug.product_id=
1672 [ROOTPLUG] Override the default product ID
1674 root_plug.debug=
1675 [ROOTPLUG] Enable debugging output
1677 rw [KNL] Mount root device read-write on boot
1679 S [KNL] Run init in single mode
1681 sa1100ir [NET]
1682 See drivers/net/irda/sa1100_ir.c.
1684 sbni= [NET] Granch SBNI12 leased line adapter
1686 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1687 Format: <io>[,<timeout>[,<isapnp>]]
1689 scsi_debug_*= [SCSI]
1690 See drivers/scsi/scsi_debug.c.
1692 scsi_default_dev_flags=
1693 [SCSI] SCSI default device flags
1694 Format: <integer>
1696 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1697 Format: <vendor>:<model>:<flags>
1698 (flags are integer value)
1700 scsi_logging_level= [SCSI] a bit mask of logging levels
1701 See drivers/scsi/scsi_logging.h for bits. Also
1702 settable via sysctl at dev.scsi.logging_level
1703 (/proc/sys/dev/scsi/logging_level).
1704 There is also a nice 'scsi_logging_level' script in the
1705 S390-tools package, available for download at
1706 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1708 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1709 discovered. async scans them in kernel threads,
1710 allowing boot to proceed. none ignores them, expecting
1711 user space to do the scan.
1713 selinux [SELINUX] Disable or enable SELinux at boot time.
1714 Format: { "0" | "1" }
1715 See security/selinux/Kconfig help text.
1716 0 -- disable.
1717 1 -- enable.
1718 Default value is set via kernel config option.
1719 If enabled at boot time, /selinux/disable can be used
1720 later to disable prior to initial policy load.
1722 selinux_compat_net =
1723 [SELINUX] Set initial selinux_compat_net flag value.
1724 Format: { "0" | "1" }
1725 0 -- use new secmark-based packet controls
1726 1 -- use legacy packet controls
1727 Default value is 0 (preferred).
1728 Value can be changed at runtime via
1729 /selinux/compat_net.
1731 serialnumber [BUGS=X86-32]
1733 shapers= [NET]
1734 Maximal number of shapers.
1736 sim710= [SCSI,HW]
1737 See header of drivers/scsi/sim710.c.
1739 simeth= [IA-64]
1740 simscsi=
1742 slram= [HW,MTD]
1744 slub_debug[=options[,slabs]] [MM, SLUB]
1745 Enabling slub_debug allows one to determine the
1746 culprit if slab objects become corrupted. Enabling
1747 slub_debug can create guard zones around objects and
1748 may poison objects when not in use. Also tracks the
1749 last alloc / free. For more information see
1750 Documentation/vm/slub.txt.
1752 slub_max_order= [MM, SLUB]
1753 Determines the maximum allowed order for slabs.
1754 A high setting may cause OOMs due to memory
1755 fragmentation. For more information see
1756 Documentation/vm/slub.txt.
1758 slub_min_objects= [MM, SLUB]
1759 The minimum number of objects per slab. SLUB will
1760 increase the slab order up to slub_max_order to
1761 generate a sufficiently large slab able to contain
1762 the number of objects indicated. The higher the number
1763 of objects the smaller the overhead of tracking slabs
1764 and the less frequently locks need to be acquired.
1765 For more information see Documentation/vm/slub.txt.
1767 slub_min_order= [MM, SLUB]
1768 Determines the mininum page order for slabs. Must be
1769 lower than slub_max_order.
1770 For more information see Documentation/vm/slub.txt.
1772 slub_nomerge [MM, SLUB]
1773 Disable merging of slabs with similar size. May be
1774 necessary if there is some reason to distinguish
1775 allocs to different slabs. Debug options disable
1776 merging on their own.
1777 For more information see Documentation/vm/slub.txt.
1779 smart2= [HW]
1780 Format: <io1>[,<io2>[,...,<io8>]]
1782 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1783 attempt to substitute SMP alternatives once at boot.
1785 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1786 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1787 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1788 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1789 smsc-ircc2.ircc_irq= [HW] IRQ line
1790 smsc-ircc2.ircc_dma= [HW] DMA channel
1791 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1792 0: Toshiba Satellite 1800 (GP data pin select)
1793 1: Fast pin select (default)
1794 2: ATC IRMode
1796 snd-ad1816a= [HW,ALSA]
1798 snd-ad1848= [HW,ALSA]
1800 snd-ali5451= [HW,ALSA]
1802 snd-als100= [HW,ALSA]
1804 snd-als4000= [HW,ALSA]
1806 snd-azt2320= [HW,ALSA]
1808 snd-cmi8330= [HW,ALSA]
1810 snd-cmipci= [HW,ALSA]
1812 snd-cs4231= [HW,ALSA]
1814 snd-cs4232= [HW,ALSA]
1816 snd-cs4236= [HW,ALSA]
1818 snd-cs4281= [HW,ALSA]
1820 snd-cs46xx= [HW,ALSA]
1822 snd-dt019x= [HW,ALSA]
1824 snd-dummy= [HW,ALSA]
1826 snd-emu10k1= [HW,ALSA]
1828 snd-ens1370= [HW,ALSA]
1830 snd-ens1371= [HW,ALSA]
1832 snd-es968= [HW,ALSA]
1834 snd-es1688= [HW,ALSA]
1836 snd-es18xx= [HW,ALSA]
1838 snd-es1938= [HW,ALSA]
1840 snd-es1968= [HW,ALSA]
1842 snd-fm801= [HW,ALSA]
1844 snd-gusclassic= [HW,ALSA]
1846 snd-gusextreme= [HW,ALSA]
1848 snd-gusmax= [HW,ALSA]
1850 snd-hdsp= [HW,ALSA]
1852 snd-ice1712= [HW,ALSA]
1854 snd-intel8x0= [HW,ALSA]
1856 snd-interwave= [HW,ALSA]
1858 snd-interwave-stb=
1859 [HW,ALSA]
1861 snd-korg1212= [HW,ALSA]
1863 snd-maestro3= [HW,ALSA]
1865 snd-mpu401= [HW,ALSA]
1867 snd-mtpav= [HW,ALSA]
1869 snd-nm256= [HW,ALSA]
1871 snd-opl3sa2= [HW,ALSA]
1873 snd-opti92x-ad1848=
1874 [HW,ALSA]
1876 snd-opti92x-cs4231=
1877 [HW,ALSA]
1879 snd-opti93x= [HW,ALSA]
1881 snd-pmac= [HW,ALSA]
1883 snd-rme32= [HW,ALSA]
1885 snd-rme96= [HW,ALSA]
1887 snd-rme9652= [HW,ALSA]
1889 snd-sb8= [HW,ALSA]
1891 snd-sb16= [HW,ALSA]
1893 snd-sbawe= [HW,ALSA]
1895 snd-serial= [HW,ALSA]
1897 snd-sgalaxy= [HW,ALSA]
1899 snd-sonicvibes= [HW,ALSA]
1901 snd-sun-amd7930=
1902 [HW,ALSA]
1904 snd-sun-cs4231= [HW,ALSA]
1906 snd-trident= [HW,ALSA]
1908 snd-usb-audio= [HW,ALSA,USB]
1910 snd-via82xx= [HW,ALSA]
1912 snd-virmidi= [HW,ALSA]
1914 snd-wavefront= [HW,ALSA]
1916 snd-ymfpci= [HW,ALSA]
1918 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1919 See Documentation/sonypi.txt
1921 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1922 See Documentation/specialix.txt.
1924 spia_io_base= [HW,MTD]
1925 spia_fio_base=
1926 spia_pedr=
1927 spia_peddr=
1929 sscape= [HW,OSS]
1930 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1932 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1933 See Documentation/scsi/st.txt.
1935 sti= [PARISC,HW]
1936 Format: <num>
1937 Set the STI (builtin display/keyboard on the HP-PARISC
1938 machines) console (graphic card) which should be used
1939 as the initial boot-console.
1940 See also comment in drivers/video/console/sticore.c.
1942 sti_font= [HW]
1943 See comment in drivers/video/console/sticore.c.
1945 stifb= [HW]
1946 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1948 sunrpc.pool_mode=
1949 [NFS]
1950 Control how the NFS server code allocates CPUs to
1951 service thread pools. Depending on how many NICs
1952 you have and where their interrupts are bound, this
1953 option will affect which CPUs will do NFS serving.
1954 Note: this parameter cannot be changed while the
1955 NFS server is running.
1957 auto the server chooses an appropriate mode
1958 automatically using heuristics
1959 global a single global pool contains all CPUs
1960 percpu one pool for each CPU
1961 pernode one pool for each NUMA node (equivalent
1962 to global on non-NUMA machines)
1964 swiotlb= [IA-64] Number of I/O TLB slabs
1966 switches= [HW,M68k]
1968 sym53c416= [HW,SCSI]
1969 See header of drivers/scsi/sym53c416.c.
1971 sysrq_always_enabled
1972 [KNL]
1973 Ignore sysrq setting - this boot parameter will
1974 neutralize any effect of /proc/sys/kernel/sysrq.
1975 Useful for debugging.
1977 t128= [HW,SCSI]
1978 See header of drivers/scsi/t128.c.
1980 tdfx= [HW,DRM]
1982 thash_entries= [KNL,NET]
1983 Set number of hash buckets for TCP connection
1985 thermal.act= [HW,ACPI]
1986 -1: disable all active trip points in all thermal zones
1987 <degrees C>: override all lowest active trip points
1989 thermal.crt= [HW,ACPI]
1990 -1: disable all critical trip points in all thermal zones
1991 <degrees C>: lower all critical trip points
1993 thermal.nocrt= [HW,ACPI]
1994 Set to disable actions on ACPI thermal zone
1995 critical and hot trip points.
1997 thermal.off= [HW,ACPI]
1998 1: disable ACPI thermal control
2000 thermal.psv= [HW,ACPI]
2001 -1: disable all passive trip points
2002 <degrees C>: override all passive trip points to this value
2004 thermal.tzp= [HW,ACPI]
2005 Specify global default ACPI thermal zone polling rate
2006 <deci-seconds>: poll all this frequency
2007 0: no polling (default)
2009 tipar.timeout= [HW,PPT]
2010 Set communications timeout in tenths of a second
2011 (default 15).
2013 tipar.delay= [HW,PPT]
2014 Set inter-bit delay in microseconds (default 10).
2016 tmscsim= [HW,SCSI]
2017 See comment before function dc390_setup() in
2018 drivers/scsi/tmscsim.c.
2020 tp720= [HW,PS2]
2022 trix= [HW,OSS] MediaTrix AudioTrix Pro
2023 Format:
2024 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2026 turbografx.map[2|3]= [HW,JOY]
2027 TurboGraFX parallel port interface
2028 Format:
2029 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2030 See also Documentation/input/joystick-parport.txt
2032 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2033 See header of drivers/scsi/u14-34f.c.
2035 uart401= [HW,OSS]
2036 Format: <io>,<irq>
2038 uart6850= [HW,OSS]
2039 Format: <io>,<irq>
2041 uhci-hcd.ignore_oc=
2042 [USB] Ignore overcurrent events (default N).
2043 Some badly-designed motherboards generate lots of
2044 bogus events, for ports that aren't wired to
2045 anything. Set this parameter to avoid log spamming.
2046 Note that genuine overcurrent events won't be
2047 reported either.
2049 usbcore.autosuspend=
2050 [USB] The autosuspend time delay (in seconds) used
2051 for newly-detected USB devices (default 2). This
2052 is the time required before an idle device will be
2053 autosuspended. Devices for which the delay is set
2054 to a negative value won't be autosuspended at all.
2056 usbhid.mousepoll=
2057 [USBHID] The interval which mice are to be polled at.
2059 vdso= [X86-32,SH,x86-64]
2060 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2061 vdso=1: enable VDSO (default)
2062 vdso=0: disable VDSO mapping
2064 vdso32= [X86-32,X86-64]
2065 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2066 vdso32=1: enable 32-bit VDSO (default)
2067 vdso32=0: disable 32-bit VDSO mapping
2069 vector= [IA-64,SMP]
2070 vector=percpu: enable percpu vector domain
2072 video= [FB] Frame buffer configuration
2073 See Documentation/fb/modedb.txt.
2075 vga= [BOOT,X86-32] Select a particular video mode
2076 See Documentation/i386/boot.txt and
2077 Documentation/svga.txt.
2078 Use vga=ask for menu.
2079 This is actually a boot loader parameter; the value is
2080 passed to the kernel using a special protocol.
2082 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2083 size of <nn>. This can be used to increase the
2084 minimum size (128MB on x86). It can also be used to
2085 decrease the size and leave more room for directly
2086 mapped kernel RAM.
2088 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2089 Format: <command>
2091 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2092 Format: <command>
2094 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2095 Format: <command>
2097 waveartist= [HW,OSS]
2098 Format: <io>,<irq>,<dma>,<dma2>
2100 wd33c93= [HW,SCSI]
2101 See header of drivers/scsi/wd33c93.c.
2103 wd7000= [HW,SCSI]
2104 See header of drivers/scsi/wd7000.c.
2106 wdt= [WDT] Watchdog
2107 See Documentation/watchdog/wdt.txt.
2109 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2110 xd_geo= See header of drivers/block/xd.c.
2112 xirc2ps_cs= [NET,PCMCIA]
2113 Format:
2114 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2116 norandmaps Don't use address space randomization
2117 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2119 ______________________________________________________________________
2121 TODO:
2123 Add documentation for ALSA options.
2124 Add more DRM drivers.