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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.noloop [HW] Disable the AUX Loopback command while probing
736 for the AUX port
737 i8042.nomux [HW] Don't check presence of an active multiplexing
738 controller
739 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
740 controllers
741 i8042.panicblink=
742 [HW] Frequency with which keyboard LEDs should blink
743 when kernel panics (default is 0.5 sec)
744 i8042.reset [HW] Reset the controller during init and cleanup
745 i8042.unlock [HW] Unlock (ignore) the keylock
747 i810= [HW,DRM]
749 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
750 indicates that the driver is running on unsupported
751 hardware.
752 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
753 does not match list of supported models.
754 i8k.power_status
755 [HW] Report power status in /proc/i8k
756 (disabled by default)
757 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
758 capability is set.
760 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
761 See Documentation/mca.txt.
763 icn= [HW,ISDN]
764 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
766 ide= [HW] (E)IDE subsystem
767 Format: ide=nodma or ide=doubler or ide=reverse
768 See Documentation/ide/ide.txt.
770 ide?= [HW] (E)IDE subsystem
771 Format: ide?=noprobe or chipset specific parameters.
772 See Documentation/ide/ide.txt.
774 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
775 See Documentation/ide/ide.txt.
777 idle= [X86]
778 Format: idle=poll or idle=mwait
779 Poll forces a polling idle loop that can slightly improves the performance
780 of waking up a idle CPU, but will use a lot of power and make the system
781 run hot. Not recommended.
782 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
783 to not use it because it doesn't save as much power as a normal idle
784 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
785 as idle=poll.
787 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
788 Claim all unknown PCI IDE storage controllers.
790 ignore_loglevel [KNL]
791 Ignore loglevel setting - this will print /all/
792 kernel messages to the console. Useful for debugging.
794 ihash_entries= [KNL]
795 Set number of hash buckets for inode cache.
797 in2000= [HW,SCSI]
798 See header of drivers/scsi/in2000.c.
800 init= [KNL]
801 Format: <full_path>
802 Run specified binary instead of /sbin/init as init
803 process.
805 initcall_debug [KNL] Trace initcalls as they are executed. Useful
806 for working out where the kernel is dying during
807 startup.
809 initrd= [BOOT] Specify the location of the initial ramdisk
811 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
812 Format: <irq>
814 inttest= [IA64]
816 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
817 off
818 Disable intel iommu driver.
819 igfx_off [Default Off]
820 By default, gfx is mapped as normal device. If a gfx
821 device has a dedicated DMAR unit, the DMAR unit is
822 bypassed by not enabling DMAR with this option. In
823 this case, gfx device will use physical address for
824 DMA.
825 forcedac [x86_64]
826 With this option iommu will not optimize to look
827 for io virtual address below 32 bit forcing dual
828 address cycle on pci bus for cards supporting greater
829 than 32 bit addressing. The default is to look
830 for translation below 32 bit and if not available
831 then look in the higher range.
833 io_delay= [X86-32,X86-64] I/O delay method
834 0x80
835 Standard port 0x80 based delay
836 0xed
837 Alternate port 0xed based delay (needed on some systems)
838 udelay
839 Simple two microseconds delay
840 none
841 No delay
843 io7= [HW] IO7 for Marvel based alpha systems
844 See comment before marvel_specify_io7 in
845 arch/alpha/kernel/core_marvel.c.
847 ip= [IP_PNP]
848 See Documentation/nfsroot.txt.
850 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
851 See comment before ip2_setup() in
852 drivers/char/ip2/ip2base.c.
854 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
855 See header of drivers/scsi/ips.c.
857 ports= [IP_VS_FTP] IPVS ftp helper module
858 Default is 21.
859 Up to 8 (IP_VS_APP_MAX_PORTS) ports
860 may be specified.
861 Format: <port>,<port>....
863 irqfixup [HW]
864 When an interrupt is not handled search all handlers
865 for it. Intended to get systems with badly broken
866 firmware running.
868 irqpoll [HW]
869 When an interrupt is not handled search all handlers
870 for it. Also check all handlers each timer
871 interrupt. Intended to get systems with badly broken
872 firmware running.
874 isapnp= [ISAPNP]
875 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
877 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
878 Format:
879 <cpu number>,...,<cpu number>
880 or
881 <cpu number>-<cpu number> (must be a positive range in ascending order)
882 or a mixture
883 <cpu number>,...,<cpu number>-<cpu number>
884 This option can be used to specify one or more CPUs
885 to isolate from the general SMP balancing and scheduling
886 algorithms. The only way to move a process onto or off
887 an "isolated" CPU is via the CPU affinity syscalls.
888 <cpu number> begins at 0 and the maximum value is
889 "number of CPUs in system - 1".
891 This option is the preferred way to isolate CPUs. The
892 alternative -- manually setting the CPU mask of all
893 tasks in the system -- can cause problems and
894 suboptimal load balancer performance.
896 iucv= [HW,NET]
898 js= [HW,JOY] Analog joystick
899 See Documentation/input/joystick.txt.
901 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
902 specifies the amount of memory usable by the kernel
903 for non-movable allocations. The requested amount is
904 spread evenly throughout all nodes in the system. The
905 remaining memory in each node is used for Movable
906 pages. In the event, a node is too small to have both
907 kernelcore and Movable pages, kernelcore pages will
908 take priority and other nodes will have a larger number
909 of kernelcore pages. The Movable zone is used for the
910 allocation of pages that may be reclaimed or moved
911 by the page migration subsystem. This means that
912 HugeTLB pages may not be allocated from this zone.
913 Note that allocations like PTEs-from-HighMem still
914 use the HighMem zone if it exists, and the Normal
915 zone if it does not.
917 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
918 is similar to kernelcore except it specifies the
919 amount of memory used for migratable allocations.
920 If both kernelcore and movablecore is specified,
921 then kernelcore will be at *least* the specified
922 value but may be more. If movablecore on its own
923 is specified, the administrator must be careful
924 that the amount of memory usable for all allocations
925 is not too small.
927 keepinitrd [HW,ARM]
929 kstack=N [X86-32,X86-64] Print N words from the kernel stack
930 in oops dumps.
932 l2cr= [PPC]
934 l3cr= [PPC]
936 lapic [X86-32,APIC] Enable the local APIC even if BIOS
937 disabled it.
939 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
940 C2 power state.
942 libata.dma= [LIBATA] DMA control
943 libata.dma=0 Disable all PATA and SATA DMA
944 libata.dma=1 PATA and SATA Disk DMA only
945 libata.dma=2 ATAPI (CDROM) DMA only
946 libata.dma=4 Compact Flash DMA only
947 Combinations also work, so libata.dma=3 enables DMA
948 for disks and CDROMs, but not CFs.
950 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
951 when set.
952 Format: <int>
954 libata.force= [LIBATA] Force configurations. The format is comma
955 separated list of "[ID:]VAL" where ID is
956 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
957 matching port, link or device. Basically, it matches
958 the ATA ID string printed on console by libata. If
959 the whole ID part is omitted, the last PORT and DEVICE
960 values are used. If ID hasn't been specified yet, the
961 configuration applies to all ports, links and devices.
963 If only DEVICE is omitted, the parameter applies to
964 the port and all links and devices behind it. DEVICE
965 number of 0 either selects the first device or the
966 first fan-out link behind PMP device. It does not
967 select the host link. DEVICE number of 15 selects the
968 host link and device attached to it.
970 The VAL specifies the configuration to force. As long
971 as there's no ambiguity shortcut notation is allowed.
972 For example, both 1.5 and 1.5G would work for 1.5Gbps.
973 The following configurations can be forced.
975 * Cable type: 40c, 80c, short40c, unk, ign or sata.
976 Any ID with matching PORT is used.
978 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
980 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
981 udma[/][16,25,33,44,66,100,133] notation is also
982 allowed.
984 * [no]ncq: Turn on or off NCQ.
986 If there are multiple matching configurations changing
987 the same attribute, the last one is used.
989 load_ramdisk= [RAM] List of ramdisks to load from floppy
990 See Documentation/ramdisk.txt.
992 lockd.nlm_grace_period=P [NFS] Assign grace period.
993 Format: <integer>
995 lockd.nlm_tcpport=N [NFS] Assign TCP port.
996 Format: <integer>
998 lockd.nlm_timeout=T [NFS] Assign timeout value.
999 Format: <integer>
1001 lockd.nlm_udpport=M [NFS] Assign UDP port.
1002 Format: <integer>
1004 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1005 Format: <irq>
1007 loglevel= All Kernel Messages with a loglevel smaller than the
1008 console loglevel will be printed to the console. It can
1009 also be changed with klogd or other programs. The
1010 loglevels are defined as follows:
1012 0 (KERN_EMERG) system is unusable
1013 1 (KERN_ALERT) action must be taken immediately
1014 2 (KERN_CRIT) critical conditions
1015 3 (KERN_ERR) error conditions
1016 4 (KERN_WARNING) warning conditions
1017 5 (KERN_NOTICE) normal but significant condition
1018 6 (KERN_INFO) informational
1019 7 (KERN_DEBUG) debug-level messages
1021 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1022 Format: { n | nk | nM }
1023 n must be a power of two. The default size
1024 is set in the kernel config file.
1026 logo.nologo [FB] Disables display of the built-in Linux logo.
1027 This may be used to provide more screen space for
1028 kernel log messages and is useful when debugging
1029 kernel boot problems.
1031 lp=0 [LP] Specify parallel ports to use, e.g,
1032 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1033 lp=reset first parallel port). 'lp=0' disables the
1034 lp=auto printer driver. 'lp=reset' (which can be
1035 specified in addition to the ports) causes
1036 attached printers to be reset. Using
1037 lp=port1,port2,... specifies the parallel ports
1038 to associate lp devices with, starting with
1039 lp0. A port specification may be 'none' to skip
1040 that lp device, or a parport name such as
1041 'parport0'. Specifying 'lp=auto' instead of a
1042 port specification list means that device IDs
1043 from each port should be examined, to see if
1044 an IEEE 1284-compliant printer is attached; if
1045 so, the driver will manage that printer.
1046 See also header of drivers/char/lp.c.
1048 lpj=n [KNL]
1049 Sets loops_per_jiffy to given constant, thus avoiding
1050 time-consuming boot-time autodetection (up to 250 ms per
1051 CPU). 0 enables autodetection (default). To determine
1052 the correct value for your kernel, boot with normal
1053 autodetection and see what value is printed. Note that
1054 on SMP systems the preset will be applied to all CPUs,
1055 which is likely to cause problems if your CPUs need
1056 significantly divergent settings. An incorrect value
1057 will cause delays in the kernel to be wrong, leading to
1058 unpredictable I/O errors and other breakage. Although
1059 unlikely, in the extreme case this might damage your
1060 hardware.
1062 ltpc= [NET]
1063 Format: <io>,<irq>,<dma>
1065 mac5380= [HW,SCSI] Format:
1066 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1068 mac53c9x= [HW,SCSI] Format:
1069 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1071 machvec= [IA64] Force the use of a particular machine-vector
1072 (machvec) in a generic kernel.
1073 Example: machvec=hpzx1_swiotlb
1075 max_loop= [LOOP] Maximum number of loopback devices that can
1076 be mounted
1077 Format: <1-256>
1079 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1080 should make use of. maxcpus=n : n >= 0 limits the
1081 kernel to using 'n' processors. n=0 is a special case,
1082 it is equivalent to "nosmp", which also disables
1083 the IO APIC.
1085 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1086 equal to this physical address is ignored.
1088 max_luns= [SCSI] Maximum number of LUNs to probe.
1089 Should be between 1 and 2^32-1.
1091 max_report_luns=
1092 [SCSI] Maximum number of LUNs received.
1093 Should be between 1 and 16384.
1095 mcatest= [IA-64]
1097 mce [X86-32] Machine Check Exception
1099 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1101 md= [HW] RAID subsystems devices and level
1102 See Documentation/md.txt.
1104 mdacon= [MDA]
1105 Format: <first>,<last>
1106 Specifies range of consoles to be captured by the MDA.
1108 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1109 Amount of memory to be used when the kernel is not able
1110 to see the whole system memory or for test.
1111 [X86-32] Use together with memmap= to avoid physical
1112 address space collisions. Without memmap= PCI devices
1113 could be placed at addresses belonging to unused RAM.
1115 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1116 memory.
1118 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1119 E820 memory map, as specified by the user.
1120 Such memmap=exactmap lines can be constructed based on
1121 BIOS output or other requirements. See the memmap=nn@ss
1122 option description.
1124 memmap=nn[KMG]@ss[KMG]
1125 [KNL] Force usage of a specific region of memory
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 ACPI data.
1130 Region of memory to be used, from ss to ss+nn.
1132 memmap=nn[KMG]$ss[KMG]
1133 [KNL,ACPI] Mark specific memory as reserved.
1134 Region of memory to be used, from ss to ss+nn.
1135 Example: Exclude memory from 0x18690000-0x1869ffff
1136 memmap=64K$0x18690000
1137 or
1138 memmap=0x10000$0x18690000
1140 meye.*= [HW] Set MotionEye Camera parameters
1141 See Documentation/video4linux/meye.txt.
1143 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1144 Multi-Function General Purpose Timers on AMD Geode
1145 platforms.
1147 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1148 the BIOS has incorrectly applied a workaround. TinyBIOS
1149 version 0.98 is known to be affected, 0.99 fixes the
1150 problem by letting the user disable the workaround.
1152 mga= [HW,DRM]
1154 mousedev.tap_time=
1155 [MOUSE] Maximum time between finger touching and
1156 leaving touchpad surface for touch to be considered
1157 a tap and be reported as a left button click (for
1158 touchpads working in absolute mode only).
1159 Format: <msecs>
1160 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1161 reporting absolute coordinates, such as tablets
1162 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1163 reporting absolute coordinates, such as tablets
1165 mpu401= [HW,OSS]
1166 Format: <io>,<irq>
1168 MTD_Partition= [MTD]
1169 Format: <name>,<region-number>,<size>,<offset>
1171 MTD_Region= [MTD] Format:
1172 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1174 mtdparts= [MTD]
1175 See drivers/mtd/cmdlinepart.c.
1177 mtouchusb.raw_coordinates=
1178 [HW] Make the MicroTouch USB driver use raw coordinates
1179 ('y', default) or cooked coordinates ('n')
1181 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1183 NCR_D700= [HW,SCSI]
1184 See header of drivers/scsi/NCR_D700.c.
1186 ncr5380= [HW,SCSI]
1188 ncr53c400= [HW,SCSI]
1190 ncr53c400a= [HW,SCSI]
1192 ncr53c406a= [HW,SCSI]
1194 ncr53c8xx= [HW,SCSI]
1196 netdev= [NET] Network devices parameters
1197 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1198 Note that mem_start is often overloaded to mean
1199 something different and driver-specific.
1200 This usage is only documented in each driver source
1201 file if at all.
1203 nfsaddrs= [NFS]
1204 See Documentation/nfsroot.txt.
1206 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1207 See Documentation/nfsroot.txt.
1209 nfs.callback_tcpport=
1210 [NFS] set the TCP port on which the NFSv4 callback
1211 channel should listen.
1213 nfs.idmap_cache_timeout=
1214 [NFS] set the maximum lifetime for idmapper cache
1215 entries.
1217 nfs.enable_ino64=
1218 [NFS] enable 64-bit inode numbers.
1219 If zero, the NFS client will fake up a 32-bit inode
1220 number for the readdir() and stat() syscalls instead
1221 of returning the full 64-bit number.
1222 The default is to return 64-bit inode numbers.
1224 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1225 when a NMI is triggered.
1226 Format: [state][,regs][,debounce][,die]
1228 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1230 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1231 emulation library even if a 387 maths coprocessor
1232 is present.
1234 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1235 caches in the slab allocator. Saves per-node memory,
1236 but will impact performance.
1238 noalign [KNL,ARM]
1240 noapic [SMP,APIC] Tells the kernel to not make use of any
1241 IOAPICs that may be present in the system.
1243 nobats [PPC] Do not use BATs for mapping kernel lowmem
1244 on "Classic" PPC cores.
1246 nocache [ARM]
1248 nodelayacct [KNL] Disable per-task delay accounting
1250 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1252 noefi [X86-32,X86-64] Disable EFI runtime services support.
1254 noexec [IA-64]
1256 noexec [X86-32,X86-64]
1257 noexec=on: enable non-executable mappings (default)
1258 noexec=off: disable nn-executable mappings
1260 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1261 register save and restore. The kernel will only save
1262 legacy floating-point registers on task switch.
1264 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1266 nohlt [BUGS=ARM]
1268 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1269 instruction doesn't work correctly and not to
1270 use it.
1272 nohalt [IA-64] Tells the kernel not to use the power saving
1273 function PAL_HALT_LIGHT when idle. This increases
1274 power-consumption. On the positive side, it reduces
1275 interrupt wake-up latency, which may improve performance
1276 in certain environments such as networked servers or
1277 real-time systems.
1279 nohz= [KNL] Boottime enable/disable dynamic ticks
1280 Valid arguments: on, off
1281 Default: on
1283 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1285 noirqdebug [X86-32] Disables the code which attempts to detect and
1286 disable unhandled interrupt sources.
1288 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1289 broken timer IRQ sources.
1291 noisapnp [ISAPNP] Disables ISA PnP code.
1293 noinitrd [RAM] Tells the kernel not to load any configured
1294 initial RAM disk.
1296 nointroute [IA-64]
1298 nojitter [IA64] Disables jitter checking for ITC timers.
1300 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1302 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1304 noltlbs [PPC] Do not use large page/tlb entries for kernel
1305 lowmem mapping on PPC40x.
1307 nomca [IA-64] Disable machine check abort handling
1309 nomce [X86-32] Machine Check Exception
1311 nomfgpt [X86-32] Disable Multi-Function General Purpose
1312 Timer usage (for AMD Geode machines).
1314 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1316 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1317 with UP alternatives
1319 noresidual [PPC] Don't use residual data on PReP machines.
1321 noresume [SWSUSP] Disables resume and restores original swap
1322 space.
1324 no-scroll [VGA] Disables scrollback.
1325 This is required for the Braillex ib80-piezo Braille
1326 reader made by F.H. Papenmeier (Germany).
1328 nosbagart [IA-64]
1330 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1332 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1333 and disable the IO APIC. legacy for "maxcpus=0".
1335 nosoftlockup [KNL] Disable the soft-lockup detector.
1337 nosync [HW,M68K] Disables sync negotiation for all devices.
1339 notsc [BUGS=X86-32] Disable Time Stamp Counter
1341 nousb [USB] Disable the USB subsystem
1343 nowb [ARM]
1345 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1346 one of ['zone', 'node', 'default'] can be specified
1347 This can be set from sysctl after boot.
1348 See Documentation/sysctl/vm.txt for details.
1350 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1352 opl3= [HW,OSS]
1353 Format: <io>
1355 oprofile.timer= [HW]
1356 Use timer interrupt instead of performance counters
1358 osst= [HW,SCSI] SCSI Tape Driver
1359 Format: <buffer_size>,<write_threshold>
1360 See also Documentation/scsi/st.txt.
1362 panic= [KNL] Kernel behaviour on panic
1363 Format: <timeout>
1365 parkbd.port= [HW] Parallel port number the keyboard adapter is
1366 connected to, default is 0.
1367 Format: <parport#>
1368 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1369 0 for XT, 1 for AT (default is AT).
1370 Format: <mode>
1372 parport= [HW,PPT] Specify parallel ports. 0 disables.
1373 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1374 Use 'auto' to force the driver to use any
1375 IRQ/DMA settings detected (the default is to
1376 ignore detected IRQ/DMA settings because of
1377 possible conflicts). You can specify the base
1378 address, IRQ, and DMA settings; IRQ and DMA
1379 should be numbers, or 'auto' (for using detected
1380 settings on that particular port), or 'nofifo'
1381 (to avoid using a FIFO even if it is detected).
1382 Parallel ports are assigned in the order they
1383 are specified on the command line, starting
1384 with parport0.
1386 parport_init_mode= [HW,PPT]
1387 Configure VIA parallel port to operate in
1388 a specific mode. This is necessary on Pegasos
1389 computer where firmware has no options for setting
1390 up parallel port mode and sets it to spp.
1391 Currently this function knows 686a and 8231 chips.
1392 Format: [spp|ps2|epp|ecp|ecpepp]
1394 pas2= [HW,OSS] Format:
1395 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1397 pas16= [HW,SCSI]
1398 See header of drivers/scsi/pas16.c.
1400 pause_on_oops=
1401 Halt all CPUs after the first oops has been printed for
1402 the specified number of seconds. This is to be used if
1403 your oopses keep scrolling off the screen.
1405 pcbit= [HW,ISDN]
1407 pcd. [PARIDE]
1408 See header of drivers/block/paride/pcd.c.
1409 See also Documentation/paride.txt.
1411 pci=option[,option...] [PCI] various PCI subsystem options:
1412 off [X86-32] don't probe for the PCI bus
1413 bios [X86-32] force use of PCI BIOS, don't access
1414 the hardware directly. Use this if your machine
1415 has a non-standard PCI host bridge.
1416 nobios [X86-32] disallow use of PCI BIOS, only direct
1417 hardware access methods are allowed. Use this
1418 if you experience crashes upon bootup and you
1419 suspect they are caused by the BIOS.
1420 conf1 [X86-32] Force use of PCI Configuration
1421 Mechanism 1.
1422 conf2 [X86-32] Force use of PCI Configuration
1423 Mechanism 2.
1424 noaer [PCIE] If the PCIEAER kernel config parameter is
1425 enabled, this kernel boot option can be used to
1426 disable the use of PCIE advanced error reporting.
1427 nodomains [PCI] Disable support for multiple PCI
1428 root domains (aka PCI segments, in ACPI-speak).
1429 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1430 Configuration
1431 nomsi [MSI] If the PCI_MSI kernel config parameter is
1432 enabled, this kernel boot option can be used to
1433 disable the use of MSI interrupts system-wide.
1434 nosort [X86-32] Don't sort PCI devices according to
1435 order given by the PCI BIOS. This sorting is
1436 done to get a device order compatible with
1437 older kernels.
1438 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1439 routing table. These calls are known to be buggy
1440 on several machines and they hang the machine
1441 when used, but on other computers it's the only
1442 way to get the interrupt routing table. Try
1443 this option if the kernel is unable to allocate
1444 IRQs or discover secondary PCI buses on your
1445 motherboard.
1446 rom [X86-32] Assign address space to expansion ROMs.
1447 Use with caution as certain devices share
1448 address decoders between ROMs and other
1449 resources.
1450 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1451 assigned automatically to PCI devices. You can
1452 make the kernel exclude IRQs of your ISA cards
1453 this way.
1454 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1455 of the PIRQ table (normally generated
1456 by the BIOS) if it is outside the
1457 F0000h-100000h range.
1458 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1459 useful if the kernel is unable to find your
1460 secondary buses and you want to tell it
1461 explicitly which ones they are.
1462 assign-busses [X86-32] Always assign all PCI bus
1463 numbers ourselves, overriding
1464 whatever the firmware may have done.
1465 usepirqmask [X86-32] Honor the possible IRQ mask stored
1466 in the BIOS $PIR table. This is needed on
1467 some systems with broken BIOSes, notably
1468 some HP Pavilion N5400 and Omnibook XE3
1469 notebooks. This will have no effect if ACPI
1470 IRQ routing is enabled.
1471 noacpi [X86-32] Do not use ACPI for IRQ routing
1472 or for PCI scanning.
1473 use_crs [X86-32] Use _CRS for PCI resource
1474 allocation.
1475 routeirq Do IRQ routing for all PCI devices.
1476 This is normally done in pci_enable_device(),
1477 so this option is a temporary workaround
1478 for broken drivers that don't call it.
1479 firmware [ARM] Do not re-enumerate the bus but instead
1480 just use the configuration from the
1481 bootloader. This is currently used on
1482 IXP2000 systems where the bus has to be
1483 configured a certain way for adjunct CPUs.
1484 noearly [X86] Don't do any early type 1 scanning.
1485 This might help on some broken boards which
1486 machine check when some devices' config space
1487 is read. But various workarounds are disabled
1488 and some IOMMU drivers will not work.
1489 bfsort Sort PCI devices into breadth-first order.
1490 This sorting is done to get a device
1491 order compatible with older (<= 2.4) kernels.
1492 nobfsort Don't sort PCI devices into breadth-first order.
1493 cbiosize=nn[KMG] The fixed amount of bus space which is
1494 reserved for the CardBus bridge's IO window.
1495 The default value is 256 bytes.
1496 cbmemsize=nn[KMG] The fixed amount of bus space which is
1497 reserved for the CardBus bridge's memory
1498 window. The default value is 64 megabytes.
1500 pcmv= [HW,PCMCIA] BadgePAD 4
1502 pd. [PARIDE]
1503 See Documentation/paride.txt.
1505 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1506 boot time.
1507 Format: { 0 | 1 }
1508 See arch/parisc/kernel/pdc_chassis.c
1510 pf. [PARIDE]
1511 See Documentation/paride.txt.
1513 pg. [PARIDE]
1514 See Documentation/paride.txt.
1516 pirq= [SMP,APIC] Manual mp-table setup
1517 See Documentation/i386/IO-APIC.txt.
1519 plip= [PPT,NET] Parallel port network link
1520 Format: { parport<nr> | timid | 0 }
1521 See also Documentation/parport.txt.
1523 pnpacpi= [ACPI]
1524 { off }
1526 pnpbios= [ISAPNP]
1527 { on | off | curr | res | no-curr | no-res }
1529 pnp_reserve_irq=
1530 [ISAPNP] Exclude IRQs for the autoconfiguration
1532 pnp_reserve_dma=
1533 [ISAPNP] Exclude DMAs for the autoconfiguration
1535 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1536 Ranges are in pairs (I/O port base and size).
1538 pnp_reserve_mem=
1539 [ISAPNP] Exclude memory regions for the
1540 autoconfiguration.
1541 Ranges are in pairs (memory base and size).
1543 print-fatal-signals=
1544 [KNL] debug: print fatal signals
1545 print-fatal-signals=1: print segfault info to
1546 the kernel console.
1547 default: off.
1549 printk.time= Show timing data prefixed to each printk message line
1550 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1552 profile= [KNL] Enable kernel profiling via /proc/profile
1553 Format: [schedule,]<number>
1554 Param: "schedule" - profile schedule points.
1555 Param: <number> - step/bucket size as a power of 2 for
1556 statistical time based profiling.
1557 Param: "sleep" - profile D-state sleeping (millisecs).
1558 Requires CONFIG_SCHEDSTATS
1559 Param: "kvm" - profile VM exits.
1561 processor.max_cstate= [HW,ACPI]
1562 Limit processor to maximum C-state
1563 max_cstate=9 overrides any DMI blacklist limit.
1565 processor.nocst [HW,ACPI]
1566 Ignore the _CST method to determine C-states,
1567 instead using the legacy FADT method
1569 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1570 before loading.
1571 See Documentation/ramdisk.txt.
1573 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1574 probe for; one of (bare|imps|exps|lifebook|any).
1575 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1576 per second.
1577 psmouse.resetafter= [HW,MOUSE]
1578 Try to reset the device after so many bad packets
1579 (0 = never).
1580 psmouse.resolution=
1581 [HW,MOUSE] Set desired mouse resolution, in dpi.
1582 psmouse.smartscroll=
1583 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1584 0 = disabled, 1 = enabled (default).
1586 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1587 Format:
1588 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1590 pt. [PARIDE]
1591 See Documentation/paride.txt.
1593 pty.legacy_count=
1594 [KNL] Number of legacy pty's. Overwrites compiled-in
1595 default number.
1597 quiet [KNL] Disable most log messages
1599 r128= [HW,DRM]
1601 raid= [HW,RAID]
1602 See Documentation/md.txt.
1604 ramdisk_blocksize= [RAM]
1605 See Documentation/ramdisk.txt.
1607 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1608 See Documentation/ramdisk.txt.
1610 rcupdate.blimit= [KNL,BOOT]
1611 Set maximum number of finished RCU callbacks to process
1612 in one batch.
1614 rcupdate.qhimark= [KNL,BOOT]
1615 Set threshold of queued
1616 RCU callbacks over which batch limiting is disabled.
1618 rcupdate.qlowmark= [KNL,BOOT]
1619 Set threshold of queued RCU callbacks below which
1620 batch limiting is re-enabled.
1622 rdinit= [KNL]
1623 Format: <full_path>
1624 Run specified binary instead of /init from the ramdisk,
1625 used for early userspace startup. See initrd.
1627 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1628 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1629 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1631 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1633 reservetop= [X86-32]
1634 Format: nn[KMG]
1635 Reserves a hole at the top of the kernel virtual
1636 address space.
1638 reset_devices [KNL] Force drivers to reset the underlying device
1639 during initialization.
1641 resume= [SWSUSP]
1642 Specify the partition device for software suspend
1644 resume_offset= [SWSUSP]
1645 Specify the offset from the beginning of the partition
1646 given by "resume=" at which the swap header is located,
1647 in <PAGE_SIZE> units (needed only for swap files).
1648 See Documentation/power/swsusp-and-swap-files.txt
1650 retain_initrd [RAM] Keep initrd memory after extraction
1652 rhash_entries= [KNL,NET]
1653 Set number of hash buckets for route cache
1655 riscom8= [HW,SERIAL]
1656 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1658 ro [KNL] Mount root device read-only on boot
1660 root= [KNL] Root filesystem
1662 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1663 mount the root filesystem
1665 rootflags= [KNL] Set root filesystem mount option string
1667 rootfstype= [KNL] Set root filesystem type
1669 rootwait [KNL] Wait (indefinitely) for root device to show up.
1670 Useful for devices that are detected asynchronously
1671 (e.g. USB and MMC devices).
1673 root_plug.vendor_id=
1674 [ROOTPLUG] Override the default vendor ID
1676 root_plug.product_id=
1677 [ROOTPLUG] Override the default product ID
1679 root_plug.debug=
1680 [ROOTPLUG] Enable debugging output
1682 rw [KNL] Mount root device read-write on boot
1684 S [KNL] Run init in single mode
1686 sa1100ir [NET]
1687 See drivers/net/irda/sa1100_ir.c.
1689 sbni= [NET] Granch SBNI12 leased line adapter
1691 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1692 Format: <io>[,<timeout>[,<isapnp>]]
1694 scsi_debug_*= [SCSI]
1695 See drivers/scsi/scsi_debug.c.
1697 scsi_default_dev_flags=
1698 [SCSI] SCSI default device flags
1699 Format: <integer>
1701 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1702 Format: <vendor>:<model>:<flags>
1703 (flags are integer value)
1705 scsi_logging_level= [SCSI] a bit mask of logging levels
1706 See drivers/scsi/scsi_logging.h for bits. Also
1707 settable via sysctl at dev.scsi.logging_level
1708 (/proc/sys/dev/scsi/logging_level).
1709 There is also a nice 'scsi_logging_level' script in the
1710 S390-tools package, available for download at
1711 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1713 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1714 discovered. async scans them in kernel threads,
1715 allowing boot to proceed. none ignores them, expecting
1716 user space to do the scan.
1718 selinux [SELINUX] Disable or enable SELinux at boot time.
1719 Format: { "0" | "1" }
1720 See security/selinux/Kconfig help text.
1721 0 -- disable.
1722 1 -- enable.
1723 Default value is set via kernel config option.
1724 If enabled at boot time, /selinux/disable can be used
1725 later to disable prior to initial policy load.
1727 selinux_compat_net =
1728 [SELINUX] Set initial selinux_compat_net flag value.
1729 Format: { "0" | "1" }
1730 0 -- use new secmark-based packet controls
1731 1 -- use legacy packet controls
1732 Default value is 0 (preferred).
1733 Value can be changed at runtime via
1734 /selinux/compat_net.
1736 serialnumber [BUGS=X86-32]
1738 shapers= [NET]
1739 Maximal number of shapers.
1741 sim710= [SCSI,HW]
1742 See header of drivers/scsi/sim710.c.
1744 simeth= [IA-64]
1745 simscsi=
1747 slram= [HW,MTD]
1749 slub_debug[=options[,slabs]] [MM, SLUB]
1750 Enabling slub_debug allows one to determine the
1751 culprit if slab objects become corrupted. Enabling
1752 slub_debug can create guard zones around objects and
1753 may poison objects when not in use. Also tracks the
1754 last alloc / free. For more information see
1755 Documentation/vm/slub.txt.
1757 slub_max_order= [MM, SLUB]
1758 Determines the maximum allowed order for slabs.
1759 A high setting may cause OOMs due to memory
1760 fragmentation. For more information see
1761 Documentation/vm/slub.txt.
1763 slub_min_objects= [MM, SLUB]
1764 The minimum number of objects per slab. SLUB will
1765 increase the slab order up to slub_max_order to
1766 generate a sufficiently large slab able to contain
1767 the number of objects indicated. The higher the number
1768 of objects the smaller the overhead of tracking slabs
1769 and the less frequently locks need to be acquired.
1770 For more information see Documentation/vm/slub.txt.
1772 slub_min_order= [MM, SLUB]
1773 Determines the mininum page order for slabs. Must be
1774 lower than slub_max_order.
1775 For more information see Documentation/vm/slub.txt.
1777 slub_nomerge [MM, SLUB]
1778 Disable merging of slabs with similar size. May be
1779 necessary if there is some reason to distinguish
1780 allocs to different slabs. Debug options disable
1781 merging on their own.
1782 For more information see Documentation/vm/slub.txt.
1784 smart2= [HW]
1785 Format: <io1>[,<io2>[,...,<io8>]]
1787 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1788 attempt to substitute SMP alternatives once at boot.
1790 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1791 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1792 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1793 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1794 smsc-ircc2.ircc_irq= [HW] IRQ line
1795 smsc-ircc2.ircc_dma= [HW] DMA channel
1796 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1797 0: Toshiba Satellite 1800 (GP data pin select)
1798 1: Fast pin select (default)
1799 2: ATC IRMode
1801 snd-ad1816a= [HW,ALSA]
1803 snd-ad1848= [HW,ALSA]
1805 snd-ali5451= [HW,ALSA]
1807 snd-als100= [HW,ALSA]
1809 snd-als4000= [HW,ALSA]
1811 snd-azt2320= [HW,ALSA]
1813 snd-cmi8330= [HW,ALSA]
1815 snd-cmipci= [HW,ALSA]
1817 snd-cs4231= [HW,ALSA]
1819 snd-cs4232= [HW,ALSA]
1821 snd-cs4236= [HW,ALSA]
1823 snd-cs4281= [HW,ALSA]
1825 snd-cs46xx= [HW,ALSA]
1827 snd-dt019x= [HW,ALSA]
1829 snd-dummy= [HW,ALSA]
1831 snd-emu10k1= [HW,ALSA]
1833 snd-ens1370= [HW,ALSA]
1835 snd-ens1371= [HW,ALSA]
1837 snd-es968= [HW,ALSA]
1839 snd-es1688= [HW,ALSA]
1841 snd-es18xx= [HW,ALSA]
1843 snd-es1938= [HW,ALSA]
1845 snd-es1968= [HW,ALSA]
1847 snd-fm801= [HW,ALSA]
1849 snd-gusclassic= [HW,ALSA]
1851 snd-gusextreme= [HW,ALSA]
1853 snd-gusmax= [HW,ALSA]
1855 snd-hdsp= [HW,ALSA]
1857 snd-ice1712= [HW,ALSA]
1859 snd-intel8x0= [HW,ALSA]
1861 snd-interwave= [HW,ALSA]
1863 snd-interwave-stb=
1864 [HW,ALSA]
1866 snd-korg1212= [HW,ALSA]
1868 snd-maestro3= [HW,ALSA]
1870 snd-mpu401= [HW,ALSA]
1872 snd-mtpav= [HW,ALSA]
1874 snd-nm256= [HW,ALSA]
1876 snd-opl3sa2= [HW,ALSA]
1878 snd-opti92x-ad1848=
1879 [HW,ALSA]
1881 snd-opti92x-cs4231=
1882 [HW,ALSA]
1884 snd-opti93x= [HW,ALSA]
1886 snd-pmac= [HW,ALSA]
1888 snd-rme32= [HW,ALSA]
1890 snd-rme96= [HW,ALSA]
1892 snd-rme9652= [HW,ALSA]
1894 snd-sb8= [HW,ALSA]
1896 snd-sb16= [HW,ALSA]
1898 snd-sbawe= [HW,ALSA]
1900 snd-serial= [HW,ALSA]
1902 snd-sgalaxy= [HW,ALSA]
1904 snd-sonicvibes= [HW,ALSA]
1906 snd-sun-amd7930=
1907 [HW,ALSA]
1909 snd-sun-cs4231= [HW,ALSA]
1911 snd-trident= [HW,ALSA]
1913 snd-usb-audio= [HW,ALSA,USB]
1915 snd-via82xx= [HW,ALSA]
1917 snd-virmidi= [HW,ALSA]
1919 snd-wavefront= [HW,ALSA]
1921 snd-ymfpci= [HW,ALSA]
1923 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1924 See Documentation/sonypi.txt
1926 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1927 See Documentation/specialix.txt.
1929 spia_io_base= [HW,MTD]
1930 spia_fio_base=
1931 spia_pedr=
1932 spia_peddr=
1934 sscape= [HW,OSS]
1935 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1937 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1938 See Documentation/scsi/st.txt.
1940 sti= [PARISC,HW]
1941 Format: <num>
1942 Set the STI (builtin display/keyboard on the HP-PARISC
1943 machines) console (graphic card) which should be used
1944 as the initial boot-console.
1945 See also comment in drivers/video/console/sticore.c.
1947 sti_font= [HW]
1948 See comment in drivers/video/console/sticore.c.
1950 stifb= [HW]
1951 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1953 sunrpc.pool_mode=
1954 [NFS]
1955 Control how the NFS server code allocates CPUs to
1956 service thread pools. Depending on how many NICs
1957 you have and where their interrupts are bound, this
1958 option will affect which CPUs will do NFS serving.
1959 Note: this parameter cannot be changed while the
1960 NFS server is running.
1962 auto the server chooses an appropriate mode
1963 automatically using heuristics
1964 global a single global pool contains all CPUs
1965 percpu one pool for each CPU
1966 pernode one pool for each NUMA node (equivalent
1967 to global on non-NUMA machines)
1969 swiotlb= [IA-64] Number of I/O TLB slabs
1971 switches= [HW,M68k]
1973 sym53c416= [HW,SCSI]
1974 See header of drivers/scsi/sym53c416.c.
1976 sysrq_always_enabled
1977 [KNL]
1978 Ignore sysrq setting - this boot parameter will
1979 neutralize any effect of /proc/sys/kernel/sysrq.
1980 Useful for debugging.
1982 t128= [HW,SCSI]
1983 See header of drivers/scsi/t128.c.
1985 tdfx= [HW,DRM]
1987 thash_entries= [KNL,NET]
1988 Set number of hash buckets for TCP connection
1990 thermal.act= [HW,ACPI]
1991 -1: disable all active trip points in all thermal zones
1992 <degrees C>: override all lowest active trip points
1994 thermal.crt= [HW,ACPI]
1995 -1: disable all critical trip points in all thermal zones
1996 <degrees C>: lower all critical trip points
1998 thermal.nocrt= [HW,ACPI]
1999 Set to disable actions on ACPI thermal zone
2000 critical and hot trip points.
2002 thermal.off= [HW,ACPI]
2003 1: disable ACPI thermal control
2005 thermal.psv= [HW,ACPI]
2006 -1: disable all passive trip points
2007 <degrees C>: override all passive trip points to this value
2009 thermal.tzp= [HW,ACPI]
2010 Specify global default ACPI thermal zone polling rate
2011 <deci-seconds>: poll all this frequency
2012 0: no polling (default)
2014 tipar.timeout= [HW,PPT]
2015 Set communications timeout in tenths of a second
2016 (default 15).
2018 tipar.delay= [HW,PPT]
2019 Set inter-bit delay in microseconds (default 10).
2021 tmscsim= [HW,SCSI]
2022 See comment before function dc390_setup() in
2023 drivers/scsi/tmscsim.c.
2025 tp720= [HW,PS2]
2027 trix= [HW,OSS] MediaTrix AudioTrix Pro
2028 Format:
2029 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2031 turbografx.map[2|3]= [HW,JOY]
2032 TurboGraFX parallel port interface
2033 Format:
2034 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2035 See also Documentation/input/joystick-parport.txt
2037 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2038 See header of drivers/scsi/u14-34f.c.
2040 uart401= [HW,OSS]
2041 Format: <io>,<irq>
2043 uart6850= [HW,OSS]
2044 Format: <io>,<irq>
2046 uhci-hcd.ignore_oc=
2047 [USB] Ignore overcurrent events (default N).
2048 Some badly-designed motherboards generate lots of
2049 bogus events, for ports that aren't wired to
2050 anything. Set this parameter to avoid log spamming.
2051 Note that genuine overcurrent events won't be
2052 reported either.
2054 usbcore.autosuspend=
2055 [USB] The autosuspend time delay (in seconds) used
2056 for newly-detected USB devices (default 2). This
2057 is the time required before an idle device will be
2058 autosuspended. Devices for which the delay is set
2059 to a negative value won't be autosuspended at all.
2061 usbhid.mousepoll=
2062 [USBHID] The interval which mice are to be polled at.
2064 vdso= [X86-32,SH,x86-64]
2065 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2066 vdso=1: enable VDSO (default)
2067 vdso=0: disable VDSO mapping
2069 vdso32= [X86-32,X86-64]
2070 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2071 vdso32=1: enable 32-bit VDSO (default)
2072 vdso32=0: disable 32-bit VDSO mapping
2074 vector= [IA-64,SMP]
2075 vector=percpu: enable percpu vector domain
2077 video= [FB] Frame buffer configuration
2078 See Documentation/fb/modedb.txt.
2080 vga= [BOOT,X86-32] Select a particular video mode
2081 See Documentation/i386/boot.txt and
2082 Documentation/svga.txt.
2083 Use vga=ask for menu.
2084 This is actually a boot loader parameter; the value is
2085 passed to the kernel using a special protocol.
2087 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2088 size of <nn>. This can be used to increase the
2089 minimum size (128MB on x86). It can also be used to
2090 decrease the size and leave more room for directly
2091 mapped kernel RAM.
2093 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2094 Format: <command>
2096 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2097 Format: <command>
2099 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2100 Format: <command>
2102 waveartist= [HW,OSS]
2103 Format: <io>,<irq>,<dma>,<dma2>
2105 wd33c93= [HW,SCSI]
2106 See header of drivers/scsi/wd33c93.c.
2108 wd7000= [HW,SCSI]
2109 See header of drivers/scsi/wd7000.c.
2111 wdt= [WDT] Watchdog
2112 See Documentation/watchdog/wdt.txt.
2114 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2115 xd_geo= See header of drivers/block/xd.c.
2117 xirc2ps_cs= [NET,PCMCIA]
2118 Format:
2119 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2121 norandmaps Don't use address space randomization
2122 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2124 ______________________________________________________________________
2126 TODO:
2128 Add documentation for ALSA options.
2129 Add more DRM drivers.