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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend is enabled.
91 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
99 X86-32 X86-32, aka i386 architecture is enabled.
100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
104 In addition, the following text indicates that the option:
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
110 Parameters denoted with BOOT are actually interpreted by the boot
111 loader, and have no meaning to the kernel directly.
112 Do not modify the syntax of boot loader parameters without extreme
113 need or coordination with <Documentation/i386/boot.txt>.
115 There are also arch-specific kernel-parameters not documented here.
116 See for example <Documentation/x86_64/boot-options.txt>.
118 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119 a trailing = on the name of any parameter states that that parameter will
120 be entered as an environment variable, whereas its absence indicates that
121 it will appear as a kernel argument readable via /proc/cmdline by programs
122 running once the system is up.
124 The number of kernel parameters is not limited, but the length of the
125 complete command line (parameters including spaces etc.) is limited to
126 a fixed number of characters. This limit depends on the architecture
127 and is between 256 and 4096 characters. It is defined in the file
128 ./include/asm/setup.h as COMMAND_LINE_SIZE.
131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
133 Format: { force | off | ht | strict | noirq }
134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
138 strict -- Be less tolerant of platforms that are not
139 strictly ACPI specification compliant.
141 See also Documentation/power/pm.txt, pci=noacpi
143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
147 default: 0
149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode, s3_beep, old_ordering }
151 See Documentation/power/video.txt for s3_bios and s3_mode.
152 s3_beep is for debugging; it makes the PC's speaker beep
153 as soon as the kernel's real-mode entry point is called.
154 old_ordering causes the ACPI 1.0 ordering of the _PTS
155 control method, wrt putting devices into low power
156 states, to be enforced (the ACPI 2.0 ordering of _PTS is
157 used by default).
159 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
160 Format: { level | edge | high | low }
162 acpi_irq_balance [HW,ACPI]
163 ACPI will balance active IRQs
164 default in APIC mode
166 acpi_irq_nobalance [HW,ACPI]
167 ACPI will not move active IRQs (default)
168 default in PIC mode
170 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
171 use by PCI
172 Format: <irq>,<irq>...
174 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
175 Format: <irq>,<irq>...
177 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
179 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
180 Format: To spoof as Windows 98: ="Microsoft Windows"
182 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
183 acpi_osi="string1" # add string1 -- only one string
184 acpi_osi="!string2" # remove built-in string2
185 acpi_osi= # disable all strings
187 acpi_serialize [HW,ACPI] force serialization of AML methods
189 acpi_skip_timer_override [HW,ACPI]
190 Recognize and ignore IRQ0/pin2 Interrupt Override.
191 For broken nForce2 BIOS resulting in XT-PIC timer.
192 acpi_use_timer_override [HW,ACPI}
193 Use timer override. For some broken Nvidia NF5 boards
194 that require a timer override, but don't have
195 HPET
197 acpi.debug_layer= [HW,ACPI]
198 Format: <int>
199 Each bit of the <int> indicates an ACPI debug layer,
200 1: enable, 0: disable. It is useful for boot time
201 debugging. After system has booted up, it can be set
202 via /sys/module/acpi/parameters/debug_layer.
203 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
204 Available bits (add the numbers together) to enable debug output
205 for specific parts of the ACPI subsystem:
206 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
207 0x10 namespace 0x20 parser 0x40 dispatcher
208 0x80 executer 0x100 resources 0x200 acpica debugger
209 0x400 os services 0x800 acpica disassembler.
210 The number can be in decimal or prefixed with 0x in hex.
211 Warning: Many of these options can produce a lot of
212 output and make your system unusable. Be very careful.
214 acpi.debug_level= [HW,ACPI]
215 Format: <int>
216 Each bit of the <int> indicates an ACPI debug level,
217 1: enable, 0: disable. It is useful for boot time
218 debugging. After system has booted up, it can be set
219 via /sys/module/acpi/parameters/debug_level.
220 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
221 Available bits (add the numbers together) to enable different
222 debug output levels of the ACPI subsystem:
223 0x01 error 0x02 warn 0x04 init 0x08 debug object
224 0x10 info 0x20 init names 0x40 parse 0x80 load
225 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
226 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
227 0x10000 resources 0x20000 user requests 0x40000 package.
228 The number can be in decimal or prefixed with 0x in hex.
229 Warning: Many of these options can produce a lot of
230 output and make your system unusable. Be very careful.
232 acpi_pm_good [X86-32,X86-64]
233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
237 agp= [AGP]
238 { off | try_unsupported }
239 off: disable AGP support
240 try_unsupported: try to drive unsupported chipsets
241 (may crash computer or cause data corruption)
243 enable_timer_pin_1 [i386,x86-64]
244 Enable PIN 1 of APIC timer
245 Can be useful to work around chipset bugs
246 (in particular on some ATI chipsets).
247 The kernel tries to set a reasonable default.
249 disable_timer_pin_1 [i386,x86-64]
250 Disable PIN 1 of APIC timer
251 Can be useful to work around chipset bugs.
253 ad1848= [HW,OSS]
254 Format: <io>,<irq>,<dma>,<dma2>,<type>
256 advansys= [HW,SCSI]
257 See header of drivers/scsi/advansys.c.
259 advwdt= [HW,WDT] Advantech WDT
260 Format: <iostart>,<iostop>
262 aedsp16= [HW,OSS] Audio Excel DSP 16
263 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
264 See also header of sound/oss/aedsp16.c.
266 aha152x= [HW,SCSI]
267 See Documentation/scsi/aha152x.txt.
269 aha1542= [HW,SCSI]
270 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
272 aic7xxx= [HW,SCSI]
273 See Documentation/scsi/aic7xxx.txt.
275 aic79xx= [HW,SCSI]
276 See Documentation/scsi/aic79xx.txt.
278 amd_iommu= [HW,X86-84]
279 Pass parameters to the AMD IOMMU driver in the system.
280 Possible values are:
281 isolate - enable device isolation (each device, as far
282 as possible, will get its own protection
283 domain)
284 amd_iommu_size= [HW,X86-64]
285 Define the size of the aperture for the AMD IOMMU
286 driver. Possible values are:
287 '32M', '64M' (default), '128M', '256M', '512M', '1G'
289 amijoy.map= [HW,JOY] Amiga joystick support
290 Map of devices attached to JOY0DAT and JOY1DAT
291 Format: <a>,<b>
292 See also Documentation/kernel/input/joystick.txt
294 analog.map= [HW,JOY] Analog joystick and gamepad support
295 Specifies type or capabilities of an analog joystick
296 connected to one of 16 gameports
297 Format: <type1>,<type2>,..<type16>
299 apc= [HW,SPARC]
300 Power management functions (SPARCstation-4/5 + deriv.)
301 Format: noidle
302 Disable APC CPU standby support. SPARCstation-Fox does
303 not play well with APC CPU idle - disable it if you have
304 APC and your system crashes randomly.
306 apic= [APIC,i386] Advanced Programmable Interrupt Controller
307 Change the output verbosity whilst booting
308 Format: { quiet (default) | verbose | debug }
309 Change the amount of debugging information output
310 when initialising the APIC and IO-APIC components.
312 apm= [APM] Advanced Power Management
313 See header of arch/x86/kernel/apm_32.c.
315 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
316 Format: <io>,<irq>,<nodeID>
318 ataflop= [HW,M68k]
320 atarimouse= [HW,MOUSE] Atari Mouse
322 atascsi= [HW,SCSI] Atari SCSI
324 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
325 EzKey and similar keyboards
327 atkbd.reset= [HW] Reset keyboard during initialization
329 atkbd.set= [HW] Select keyboard code set
330 Format: <int> (2 = AT (default), 3 = PS/2)
332 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
333 keyboards
335 atkbd.softraw= [HW] Choose between synthetic and real raw mode
336 Format: <bool> (0 = real, 1 = synthetic (default))
338 atkbd.softrepeat= [HW]
339 Use software keyboard repeat
341 autotest [IA64]
343 baycom_epp= [HW,AX25]
344 Format: <io>,<mode>
346 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
347 Format: <io>,<mode>
348 See header of drivers/net/hamradio/baycom_par.c.
350 baycom_ser_fdx= [HW,AX25]
351 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
352 Format: <io>,<irq>,<mode>[,<baud>]
353 See header of drivers/net/hamradio/baycom_ser_fdx.c.
355 baycom_ser_hdx= [HW,AX25]
356 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
357 Format: <io>,<irq>,<mode>
358 See header of drivers/net/hamradio/baycom_ser_hdx.c.
360 boot_delay= Milliseconds to delay each printk during boot.
361 Values larger than 10 seconds (10000) are changed to
362 no delay (0).
363 Format: integer
365 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
366 bttv.radio= Most important insmod options are available as
367 kernel args too.
368 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
369 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
371 BusLogic= [HW,SCSI]
372 See drivers/scsi/BusLogic.c, comment before function
373 BusLogic_ParseDriverOptions().
375 c101= [NET] Moxa C101 synchronous serial card
377 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
378 Sometimes CPU hardware bugs make them report the cache
379 size incorrectly. The kernel will attempt work arounds
380 to fix known problems, but for some CPUs it is not
381 possible to determine what the correct size should be.
382 This option provides an override for these situations.
384 security= [SECURITY] Choose a security module to enable at boot.
385 If this boot parameter is not specified, only the first
386 security module asking for security registration will be
387 loaded. An invalid security module name will be treated
388 as if no module has been chosen.
390 capability.disable=
391 [SECURITY] Disable capabilities. This would normally
392 be used only if an alternative security model is to be
393 configured. Potentially dangerous and should only be
394 used if you are entirely sure of the consequences.
396 ccw_timeout_log [S390]
397 See Documentation/s390/CommonIO for details.
399 cgroup_disable= [KNL] Disable a particular controller
400 Format: {name of the controller(s) to disable}
401 {Currently supported controllers - "memory"}
403 checkreqprot [SELINUX] Set initial checkreqprot flag value.
404 Format: { "0" | "1" }
405 See security/selinux/Kconfig help text.
406 0 -- check protection applied by kernel (includes
407 any implied execute protection).
408 1 -- check protection requested by application.
409 Default value is set via a kernel config option.
410 Value can be changed at runtime via
411 /selinux/checkreqprot.
413 cio_ignore= [S390]
414 See Documentation/s390/CommonIO for details.
416 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
417 [Deprecated]
418 Forces specified clocksource (if available) to be used
419 when calculating gettimeofday(). If specified
420 clocksource is not available, it defaults to PIT.
421 Format: { pit | tsc | cyclone | pmtmr }
423 clocksource= [GENERIC_TIME] Override the default clocksource
424 Format: <string>
425 Override the default clocksource and use the clocksource
426 with the name specified.
427 Some clocksource names to choose from, depending on
428 the platform:
429 [all] jiffies (this is the base, fallback clocksource)
430 [ACPI] acpi_pm
431 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
432 pxa_timer,timer3,32k_counter,timer0_1
433 [AVR32] avr32
434 [X86-32] pit,hpet,tsc,vmi-timer;
435 scx200_hrt on Geode; cyclone on IBM x440
436 [MIPS] MIPS
437 [PARISC] cr16
438 [S390] tod
439 [SH] SuperH
440 [SPARC64] tick
441 [X86-64] hpet,tsc
443 clearcpuid=BITNUM [X86]
444 Disable CPUID feature X for the kernel. See
445 include/asm-x86/cpufeature.h for the valid bit numbers.
446 Note the Linux specific bits are not necessarily
447 stable over kernel options, but the vendor specific
448 ones should be.
449 Also note that user programs calling CPUID directly
450 or using the feature without checking anything
451 will still see it. This just prevents it from
452 being used by the kernel or shown in /proc/cpuinfo.
453 Also note the kernel might malfunction if you disable
454 some critical bits.
456 code_bytes [IA32/X86_64] How many bytes of object code to print
457 in an oops report.
458 Range: 0 - 8192
459 Default: 64
461 disable_8254_timer
462 enable_8254_timer
463 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
464 over the 8254 in addition to over the IO-APIC. The
465 kernel tries to set a sensible default.
467 hpet= [X86-32,HPET] option to control HPET usage
468 Format: { enable (default) | disable | force }
469 disable: disable HPET and use PIT instead
470 force: allow force enabled of undocumented chips (ICH4,
471 VIA, nVidia)
473 com20020= [HW,NET] ARCnet - COM20020 chipset
474 Format:
475 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
477 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
478 Format: <io>[,<irq>]
480 com90xx= [HW,NET]
481 ARCnet - COM90xx chipset (memory-mapped buffers)
482 Format: <io>[,<irq>[,<memstart>]]
484 condev= [HW,S390] console device
485 conmode=
487 console= [KNL] Output console device and options.
489 tty<n> Use the virtual console device <n>.
491 ttyS<n>[,options]
492 ttyUSB0[,options]
493 Use the specified serial port. The options are of
494 the form "bbbbpnf", where "bbbb" is the baud rate,
495 "p" is parity ("n", "o", or "e"), "n" is number of
496 bits, and "f" is flow control ("r" for RTS or
497 omit it). Default is "9600n8".
499 See Documentation/serial-console.txt for more
500 information. See
501 Documentation/networking/netconsole.txt for an
502 alternative.
504 uart[8250],io,<addr>[,options]
505 uart[8250],mmio,<addr>[,options]
506 Start an early, polled-mode console on the 8250/16550
507 UART at the specified I/O port or MMIO address,
508 switching to the matching ttyS device later. The
509 options are the same as for ttyS, above.
511 If the device connected to the port is not a TTY but a braille
512 device, prepend "brl," before the device type, for instance
513 console=brl,ttyS0
514 For now, only VisioBraille is supported.
516 earlycon= [KNL] Output early console device and options.
517 uart[8250],io,<addr>[,options]
518 uart[8250],mmio,<addr>[,options]
519 Start an early, polled-mode console on the 8250/16550
520 UART at the specified I/O port or MMIO address.
521 The options are the same as for ttyS, above.
523 no_console_suspend
524 [HW] Never suspend the console
525 Disable suspending of consoles during suspend and
526 hibernate operations. Once disabled, debugging
527 messages can reach various consoles while the rest
528 of the system is being put to sleep (ie, while
529 debugging driver suspend/resume hooks). This may
530 not work reliably with all consoles, but is known
531 to work with serial and VGA consoles.
533 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
534 Format:
535 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
537 crashkernel=nn[KMG]@ss[KMG]
538 [KNL] Reserve a chunk of physical memory to
539 hold a kernel to switch to with kexec on panic.
541 crashkernel=range1:size1[,range2:size2,...][@offset]
542 [KNL] Same as above, but depends on the memory
543 in the running system. The syntax of range is
544 start-[end] where start and end are both
545 a memory unit (amount[KMG]). See also
546 Documentation/kdump/kdump.txt for a example.
548 cs4232= [HW,OSS]
549 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
551 cs89x0_dma= [HW,NET]
552 Format: <dma>
554 cs89x0_media= [HW,NET]
555 Format: { rj45 | aui | bnc }
557 dasd= [HW,NET]
558 See header of drivers/s390/block/dasd_devmap.c.
560 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
561 (one device per port)
562 Format: <port#>,<type>
563 See also Documentation/input/joystick-parport.txt
565 debug [KNL] Enable kernel debugging (events log level).
567 debug_locks_verbose=
568 [KNL] verbose self-tests
569 Format=<0|1>
570 Print debugging info while doing the locking API
571 self-tests.
572 We default to 0 (no extra messages), setting it to
573 1 will print _a lot_ more information - normally
574 only useful to kernel developers.
576 debug_objects [KNL] Enable object debugging
578 debugpat [X86] Enable PAT debugging
580 decnet.addr= [HW,NET]
581 Format: <area>[,<node>]
582 See also Documentation/networking/decnet.txt.
584 vt.default_blu= [VT]
585 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
586 Change the default blue palette of the console.
587 This is a 16-member array composed of values
588 ranging from 0-255.
590 vt.default_grn= [VT]
591 Format: <green0>,<green1>,<green2>,...,<green15>
592 Change the default green palette of the console.
593 This is a 16-member array composed of values
594 ranging from 0-255.
596 vt.default_red= [VT]
597 Format: <red0>,<red1>,<red2>,...,<red15>
598 Change the default red palette of the console.
599 This is a 16-member array composed of values
600 ranging from 0-255.
602 vt.default_utf8=
603 [VT]
604 Format=<0|1>
605 Set system-wide default UTF-8 mode for all tty's.
606 Default is 1, i.e. UTF-8 mode is enabled for all
607 newly opened terminals.
609 dhash_entries= [KNL]
610 Set number of hash buckets for dentry cache.
612 digi= [HW,SERIAL]
613 IO parameters + enable/disable command.
615 digiepca= [HW,SERIAL]
616 See drivers/char/README.epca and
617 Documentation/digiepca.txt.
619 disable_mtrr_cleanup [X86]
620 enable_mtrr_cleanup [X86]
621 The kernel tries to adjust MTRR layout from continuous
622 to discrete, to make X server driver able to add WB
623 entry later. This parameter enables/disables that.
625 mtrr_chunk_size=nn[KMG] [X86]
626 used for mtrr cleanup. It is largest continous chunk
627 that could hold holes aka. UC entries.
629 mtrr_gran_size=nn[KMG] [X86]
630 Used for mtrr cleanup. It is granularity of mtrr block.
631 Default is 1.
632 Large value could prevent small alignment from
633 using up MTRRs.
635 mtrr_spare_reg_nr=n [X86]
636 Format: <integer>
637 Range: 0,7 : spare reg number
638 Default : 1
639 Used for mtrr cleanup. It is spare mtrr entries number.
640 Set to 2 or more if your graphical card needs more.
642 disable_mtrr_trim [X86, Intel and AMD only]
643 By default the kernel will trim any uncacheable
644 memory out of your available memory pool based on
645 MTRR settings. This parameter disables that behavior,
646 possibly causing your machine to run very slowly.
648 dmasound= [HW,OSS] Sound subsystem buffers
650 dscc4.setup= [NET]
652 dtc3181e= [HW,SCSI]
654 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
655 earlyprintk=vga
656 earlyprintk=serial[,ttySn[,baudrate]]
658 Append ",keep" to not disable it when the real console
659 takes over.
661 Only vga or serial at a time, not both.
663 Currently only ttyS0 and ttyS1 are supported.
665 Interaction with the standard serial driver is not
666 very good.
668 The VGA output is eventually overwritten by the real
669 console.
671 eata= [HW,SCSI]
673 edd= [EDD]
674 Format: {"off" | "on" | "skip[mbr]"}
676 eisa_irq_edge= [PARISC,HW]
677 See header of drivers/parisc/eisa.c.
679 elanfreq= [X86-32]
680 See comment before function elanfreq_setup() in
681 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
683 elevator= [IOSCHED]
684 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
685 See Documentation/block/as-iosched.txt and
686 Documentation/block/deadline-iosched.txt for details.
688 elfcorehdr= [X86-32, X86_64]
689 Specifies physical address of start of kernel core
690 image elf header. Generally kexec loader will
691 pass this option to capture kernel.
692 See Documentation/kdump/kdump.txt for details.
694 enforcing [SELINUX] Set initial enforcing status.
695 Format: {"0" | "1"}
696 See security/selinux/Kconfig help text.
697 0 -- permissive (log only, no denials).
698 1 -- enforcing (deny and log).
699 Default value is 0.
700 Value can be changed at runtime via /selinux/enforce.
702 es1371= [HW,OSS]
703 Format: <spdif>,[<nomix>,[<amplifier>]]
704 See also header of sound/oss/es1371.c.
706 ether= [HW,NET] Ethernet cards parameters
707 This option is obsoleted by the "netdev=" option, which
708 has equivalent usage. See its documentation for details.
710 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
711 Format: <io>[,<irq>]
713 failslab=
714 fail_page_alloc=
715 fail_make_request=[KNL]
716 General fault injection mechanism.
717 Format: <interval>,<probability>,<space>,<times>
718 See also /Documentation/fault-injection/.
720 fd_mcs= [HW,SCSI]
721 See header of drivers/scsi/fd_mcs.c.
723 fdomain= [HW,SCSI]
724 See header of drivers/scsi/fdomain.c.
726 floppy= [HW]
727 See Documentation/floppy.txt.
729 force_pal_cache_flush
730 [IA-64] Avoid check_sal_cache_flush which may hang on
731 buggy SAL_CACHE_FLUSH implementations. Using this
732 parameter will force ia64_sal_cache_flush to call
733 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
735 gamecon.map[2|3]=
736 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
737 support via parallel port (up to 5 devices per port)
738 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
739 See also Documentation/input/joystick-parport.txt
741 gamma= [HW,DRM]
743 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
744 Format: off | on
745 default: on
747 gdth= [HW,SCSI]
748 See header of drivers/scsi/gdth.c.
750 gpt [EFI] Forces disk with valid GPT signature but
751 invalid Protective MBR to be treated as GPT.
753 gvp11= [HW,SCSI]
755 hashdist= [KNL,NUMA] Large hashes allocated during boot
756 are distributed across NUMA nodes. Defaults on
757 for IA-64, off otherwise.
758 Format: 0 | 1 (for off | on)
760 hcl= [IA-64] SGI's Hardware Graph compatibility layer
762 hd= [EIDE] (E)IDE hard drive subsystem geometry
763 Format: <cyl>,<head>,<sect>
765 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
766 size of <nn>. This works even on boxes that have no
767 highmem otherwise. This also works to reduce highmem
768 size on bigger boxes.
770 highres= [KNL] Enable/disable high resolution timer mode.
771 Valid parameters: "on", "off"
772 Default: "on"
774 hisax= [HW,ISDN]
775 See Documentation/isdn/README.HiSax.
777 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
778 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
780 i8042.direct [HW] Put keyboard port into non-translated mode
781 i8042.dumbkbd [HW] Pretend that controller can only read data from
782 keyboard and cannot control its state
783 (Don't attempt to blink the leds)
784 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
785 i8042.nokbd [HW] Don't check/create keyboard port
786 i8042.noloop [HW] Disable the AUX Loopback command while probing
787 for the AUX port
788 i8042.nomux [HW] Don't check presence of an active multiplexing
789 controller
790 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
791 controllers
792 i8042.panicblink=
793 [HW] Frequency with which keyboard LEDs should blink
794 when kernel panics (default is 0.5 sec)
795 i8042.reset [HW] Reset the controller during init and cleanup
796 i8042.unlock [HW] Unlock (ignore) the keylock
798 i810= [HW,DRM]
800 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
801 indicates that the driver is running on unsupported
802 hardware.
803 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
804 does not match list of supported models.
805 i8k.power_status
806 [HW] Report power status in /proc/i8k
807 (disabled by default)
808 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
809 capability is set.
811 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
812 See Documentation/mca.txt.
814 icn= [HW,ISDN]
815 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
817 ide= [HW] (E)IDE subsystem
818 Format: ide=nodma or ide=doubler
819 See Documentation/ide/ide.txt.
821 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
822 See Documentation/ide/ide.txt.
824 idle= [X86]
825 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
826 Poll forces a polling idle loop that can slightly improves the performance
827 of waking up a idle CPU, but will use a lot of power and make the system
828 run hot. Not recommended.
829 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
830 to not use it because it doesn't save as much power as a normal idle
831 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
832 as idle=poll.
833 idle=halt. Halt is forced to be used for CPU idle.
834 In such case C2/C3 won't be used again.
835 idle=nomwait. Disable mwait for CPU C-states
837 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
838 Claim all unknown PCI IDE storage controllers.
840 ignore_loglevel [KNL]
841 Ignore loglevel setting - this will print /all/
842 kernel messages to the console. Useful for debugging.
844 ihash_entries= [KNL]
845 Set number of hash buckets for inode cache.
847 in2000= [HW,SCSI]
848 See header of drivers/scsi/in2000.c.
850 init= [KNL]
851 Format: <full_path>
852 Run specified binary instead of /sbin/init as init
853 process.
855 initcall_debug [KNL] Trace initcalls as they are executed. Useful
856 for working out where the kernel is dying during
857 startup.
859 initrd= [BOOT] Specify the location of the initial ramdisk
861 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
862 Format: <irq>
864 inttest= [IA64]
866 iommu= [x86]
867 off
868 force
869 noforce
870 biomerge
871 panic
872 nopanic
873 merge
874 nomerge
875 forcesac
876 soft
879 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
880 off
881 Disable intel iommu driver.
882 igfx_off [Default Off]
883 By default, gfx is mapped as normal device. If a gfx
884 device has a dedicated DMAR unit, the DMAR unit is
885 bypassed by not enabling DMAR with this option. In
886 this case, gfx device will use physical address for
887 DMA.
888 forcedac [x86_64]
889 With this option iommu will not optimize to look
890 for io virtual address below 32 bit forcing dual
891 address cycle on pci bus for cards supporting greater
892 than 32 bit addressing. The default is to look
893 for translation below 32 bit and if not available
894 then look in the higher range.
895 strict [Default Off]
896 With this option on every unmap_single operation will
897 result in a hardware IOTLB flush operation as opposed
898 to batching them for performance.
900 io_delay= [X86-32,X86-64] I/O delay method
901 0x80
902 Standard port 0x80 based delay
903 0xed
904 Alternate port 0xed based delay (needed on some systems)
905 udelay
906 Simple two microseconds delay
907 none
908 No delay
910 io7= [HW] IO7 for Marvel based alpha systems
911 See comment before marvel_specify_io7 in
912 arch/alpha/kernel/core_marvel.c.
914 ip= [IP_PNP]
915 See Documentation/filesystems/nfsroot.txt.
917 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
918 See comment before ip2_setup() in
919 drivers/char/ip2/ip2base.c.
921 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
922 See header of drivers/scsi/ips.c.
924 ports= [IP_VS_FTP] IPVS ftp helper module
925 Default is 21.
926 Up to 8 (IP_VS_APP_MAX_PORTS) ports
927 may be specified.
928 Format: <port>,<port>....
930 irqfixup [HW]
931 When an interrupt is not handled search all handlers
932 for it. Intended to get systems with badly broken
933 firmware running.
935 irqpoll [HW]
936 When an interrupt is not handled search all handlers
937 for it. Also check all handlers each timer
938 interrupt. Intended to get systems with badly broken
939 firmware running.
941 isapnp= [ISAPNP]
942 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
944 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
945 Format:
946 <cpu number>,...,<cpu number>
947 or
948 <cpu number>-<cpu number> (must be a positive range in ascending order)
949 or a mixture
950 <cpu number>,...,<cpu number>-<cpu number>
951 This option can be used to specify one or more CPUs
952 to isolate from the general SMP balancing and scheduling
953 algorithms. The only way to move a process onto or off
954 an "isolated" CPU is via the CPU affinity syscalls.
955 <cpu number> begins at 0 and the maximum value is
956 "number of CPUs in system - 1".
958 This option is the preferred way to isolate CPUs. The
959 alternative -- manually setting the CPU mask of all
960 tasks in the system -- can cause problems and
961 suboptimal load balancer performance.
963 iucv= [HW,NET]
965 js= [HW,JOY] Analog joystick
966 See Documentation/input/joystick.txt.
968 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
969 specifies the amount of memory usable by the kernel
970 for non-movable allocations. The requested amount is
971 spread evenly throughout all nodes in the system. The
972 remaining memory in each node is used for Movable
973 pages. In the event, a node is too small to have both
974 kernelcore and Movable pages, kernelcore pages will
975 take priority and other nodes will have a larger number
976 of kernelcore pages. The Movable zone is used for the
977 allocation of pages that may be reclaimed or moved
978 by the page migration subsystem. This means that
979 HugeTLB pages may not be allocated from this zone.
980 Note that allocations like PTEs-from-HighMem still
981 use the HighMem zone if it exists, and the Normal
982 zone if it does not.
984 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
985 is similar to kernelcore except it specifies the
986 amount of memory used for migratable allocations.
987 If both kernelcore and movablecore is specified,
988 then kernelcore will be at *least* the specified
989 value but may be more. If movablecore on its own
990 is specified, the administrator must be careful
991 that the amount of memory usable for all allocations
992 is not too small.
994 keepinitrd [HW,ARM]
996 kstack=N [X86-32,X86-64] Print N words from the kernel stack
997 in oops dumps.
999 kgdboc= [HW] kgdb over consoles.
1000 Requires a tty driver that supports console polling.
1001 (only serial suported for now)
1002 Format: <serial_device>[,baud]
1004 l2cr= [PPC]
1006 l3cr= [PPC]
1008 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1009 disabled it.
1011 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1012 C2 power state.
1014 libata.dma= [LIBATA] DMA control
1015 libata.dma=0 Disable all PATA and SATA DMA
1016 libata.dma=1 PATA and SATA Disk DMA only
1017 libata.dma=2 ATAPI (CDROM) DMA only
1018 libata.dma=4 Compact Flash DMA only
1019 Combinations also work, so libata.dma=3 enables DMA
1020 for disks and CDROMs, but not CFs.
1022 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1023 when set.
1024 Format: <int>
1026 libata.force= [LIBATA] Force configurations. The format is comma
1027 separated list of "[ID:]VAL" where ID is
1028 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1029 matching port, link or device. Basically, it matches
1030 the ATA ID string printed on console by libata. If
1031 the whole ID part is omitted, the last PORT and DEVICE
1032 values are used. If ID hasn't been specified yet, the
1033 configuration applies to all ports, links and devices.
1035 If only DEVICE is omitted, the parameter applies to
1036 the port and all links and devices behind it. DEVICE
1037 number of 0 either selects the first device or the
1038 first fan-out link behind PMP device. It does not
1039 select the host link. DEVICE number of 15 selects the
1040 host link and device attached to it.
1042 The VAL specifies the configuration to force. As long
1043 as there's no ambiguity shortcut notation is allowed.
1044 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1045 The following configurations can be forced.
1047 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1048 Any ID with matching PORT is used.
1050 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1052 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1053 udma[/][16,25,33,44,66,100,133] notation is also
1054 allowed.
1056 * [no]ncq: Turn on or off NCQ.
1058 If there are multiple matching configurations changing
1059 the same attribute, the last one is used.
1061 load_ramdisk= [RAM] List of ramdisks to load from floppy
1062 See Documentation/ramdisk.txt.
1064 lockd.nlm_grace_period=P [NFS] Assign grace period.
1065 Format: <integer>
1067 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1068 Format: <integer>
1070 lockd.nlm_timeout=T [NFS] Assign timeout value.
1071 Format: <integer>
1073 lockd.nlm_udpport=M [NFS] Assign UDP port.
1074 Format: <integer>
1076 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1077 Format: <irq>
1079 loglevel= All Kernel Messages with a loglevel smaller than the
1080 console loglevel will be printed to the console. It can
1081 also be changed with klogd or other programs. The
1082 loglevels are defined as follows:
1084 0 (KERN_EMERG) system is unusable
1085 1 (KERN_ALERT) action must be taken immediately
1086 2 (KERN_CRIT) critical conditions
1087 3 (KERN_ERR) error conditions
1088 4 (KERN_WARNING) warning conditions
1089 5 (KERN_NOTICE) normal but significant condition
1090 6 (KERN_INFO) informational
1091 7 (KERN_DEBUG) debug-level messages
1093 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1094 Format: { n | nk | nM }
1095 n must be a power of two. The default size
1096 is set in the kernel config file.
1098 logo.nologo [FB] Disables display of the built-in Linux logo.
1099 This may be used to provide more screen space for
1100 kernel log messages and is useful when debugging
1101 kernel boot problems.
1103 lp=0 [LP] Specify parallel ports to use, e.g,
1104 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1105 lp=reset first parallel port). 'lp=0' disables the
1106 lp=auto printer driver. 'lp=reset' (which can be
1107 specified in addition to the ports) causes
1108 attached printers to be reset. Using
1109 lp=port1,port2,... specifies the parallel ports
1110 to associate lp devices with, starting with
1111 lp0. A port specification may be 'none' to skip
1112 that lp device, or a parport name such as
1113 'parport0'. Specifying 'lp=auto' instead of a
1114 port specification list means that device IDs
1115 from each port should be examined, to see if
1116 an IEEE 1284-compliant printer is attached; if
1117 so, the driver will manage that printer.
1118 See also header of drivers/char/lp.c.
1120 lpj=n [KNL]
1121 Sets loops_per_jiffy to given constant, thus avoiding
1122 time-consuming boot-time autodetection (up to 250 ms per
1123 CPU). 0 enables autodetection (default). To determine
1124 the correct value for your kernel, boot with normal
1125 autodetection and see what value is printed. Note that
1126 on SMP systems the preset will be applied to all CPUs,
1127 which is likely to cause problems if your CPUs need
1128 significantly divergent settings. An incorrect value
1129 will cause delays in the kernel to be wrong, leading to
1130 unpredictable I/O errors and other breakage. Although
1131 unlikely, in the extreme case this might damage your
1132 hardware.
1134 ltpc= [NET]
1135 Format: <io>,<irq>,<dma>
1137 mac5380= [HW,SCSI] Format:
1138 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1140 machvec= [IA64] Force the use of a particular machine-vector
1141 (machvec) in a generic kernel.
1142 Example: machvec=hpzx1_swiotlb
1144 max_loop= [LOOP] Maximum number of loopback devices that can
1145 be mounted
1146 Format: <1-256>
1148 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1149 should make use of. maxcpus=n : n >= 0 limits the
1150 kernel to using 'n' processors. n=0 is a special case,
1151 it is equivalent to "nosmp", which also disables
1152 the IO APIC.
1154 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1155 equal to this physical address is ignored.
1157 max_luns= [SCSI] Maximum number of LUNs to probe.
1158 Should be between 1 and 2^32-1.
1160 max_report_luns=
1161 [SCSI] Maximum number of LUNs received.
1162 Should be between 1 and 16384.
1164 mcatest= [IA-64]
1166 mce [X86-32] Machine Check Exception
1168 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1170 md= [HW] RAID subsystems devices and level
1171 See Documentation/md.txt.
1173 mdacon= [MDA]
1174 Format: <first>,<last>
1175 Specifies range of consoles to be captured by the MDA.
1177 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1178 Amount of memory to be used when the kernel is not able
1179 to see the whole system memory or for test.
1180 [X86-32] Use together with memmap= to avoid physical
1181 address space collisions. Without memmap= PCI devices
1182 could be placed at addresses belonging to unused RAM.
1184 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1185 memory.
1187 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1188 E820 memory map, as specified by the user.
1189 Such memmap=exactmap lines can be constructed based on
1190 BIOS output or other requirements. See the memmap=nn@ss
1191 option description.
1193 memmap=nn[KMG]@ss[KMG]
1194 [KNL] Force usage of a specific region of memory
1195 Region of memory to be used, from ss to ss+nn.
1197 memmap=nn[KMG]#ss[KMG]
1198 [KNL,ACPI] Mark specific memory as ACPI data.
1199 Region of memory to be used, from ss to ss+nn.
1201 memmap=nn[KMG]$ss[KMG]
1202 [KNL,ACPI] Mark specific memory as reserved.
1203 Region of memory to be used, from ss to ss+nn.
1204 Example: Exclude memory from 0x18690000-0x1869ffff
1205 memmap=64K$0x18690000
1206 or
1207 memmap=0x10000$0x18690000
1209 memtest= [KNL,X86] Enable memtest
1210 Format: <integer>
1211 range: 0,4 : pattern number
1212 default : 0 <disable>
1214 meye.*= [HW] Set MotionEye Camera parameters
1215 See Documentation/video4linux/meye.txt.
1217 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1218 Multi-Function General Purpose Timers on AMD Geode
1219 platforms.
1221 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1222 the BIOS has incorrectly applied a workaround. TinyBIOS
1223 version 0.98 is known to be affected, 0.99 fixes the
1224 problem by letting the user disable the workaround.
1226 mga= [HW,DRM]
1228 mousedev.tap_time=
1229 [MOUSE] Maximum time between finger touching and
1230 leaving touchpad surface for touch to be considered
1231 a tap and be reported as a left button click (for
1232 touchpads working in absolute mode only).
1233 Format: <msecs>
1234 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1235 reporting absolute coordinates, such as tablets
1236 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1237 reporting absolute coordinates, such as tablets
1239 mpu401= [HW,OSS]
1240 Format: <io>,<irq>
1242 MTD_Partition= [MTD]
1243 Format: <name>,<region-number>,<size>,<offset>
1245 MTD_Region= [MTD] Format:
1246 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1248 mtdparts= [MTD]
1249 See drivers/mtd/cmdlinepart.c.
1251 mtdset= [ARM]
1252 ARM/S3C2412 JIVE boot control
1254 See arch/arm/mach-s3c2412/mach-jive.c
1256 mtouchusb.raw_coordinates=
1257 [HW] Make the MicroTouch USB driver use raw coordinates
1258 ('y', default) or cooked coordinates ('n')
1260 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1262 NCR_D700= [HW,SCSI]
1263 See header of drivers/scsi/NCR_D700.c.
1265 ncr5380= [HW,SCSI]
1267 ncr53c400= [HW,SCSI]
1269 ncr53c400a= [HW,SCSI]
1271 ncr53c406a= [HW,SCSI]
1273 ncr53c8xx= [HW,SCSI]
1275 netdev= [NET] Network devices parameters
1276 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1277 Note that mem_start is often overloaded to mean
1278 something different and driver-specific.
1279 This usage is only documented in each driver source
1280 file if at all.
1282 nf_conntrack.acct=
1283 [NETFILTER] Enable connection tracking flow accounting
1284 0 to disable accounting
1285 1 to enable accounting
1286 Default value depends on CONFIG_NF_CT_ACCT that is
1287 going to be removed in 2.6.29.
1289 nfsaddrs= [NFS]
1290 See Documentation/filesystems/nfsroot.txt.
1292 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1293 See Documentation/filesystems/nfsroot.txt.
1295 nfs.callback_tcpport=
1296 [NFS] set the TCP port on which the NFSv4 callback
1297 channel should listen.
1299 nfs.idmap_cache_timeout=
1300 [NFS] set the maximum lifetime for idmapper cache
1301 entries.
1303 nfs.enable_ino64=
1304 [NFS] enable 64-bit inode numbers.
1305 If zero, the NFS client will fake up a 32-bit inode
1306 number for the readdir() and stat() syscalls instead
1307 of returning the full 64-bit number.
1308 The default is to return 64-bit inode numbers.
1310 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1311 when a NMI is triggered.
1312 Format: [state][,regs][,debounce][,die]
1314 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1316 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1317 emulation library even if a 387 maths coprocessor
1318 is present.
1320 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1321 caches in the slab allocator. Saves per-node memory,
1322 but will impact performance.
1324 noalign [KNL,ARM]
1326 noapic [SMP,APIC] Tells the kernel to not make use of any
1327 IOAPICs that may be present in the system.
1329 nobats [PPC] Do not use BATs for mapping kernel lowmem
1330 on "Classic" PPC cores.
1332 nocache [ARM]
1334 nodelayacct [KNL] Disable per-task delay accounting
1336 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1338 noefi [X86-32,X86-64] Disable EFI runtime services support.
1340 noexec [IA-64]
1342 noexec [X86-32,X86-64]
1343 On X86-32 available only on PAE configured kernels.
1344 noexec=on: enable non-executable mappings (default)
1345 noexec=off: disable non-executable mappings
1347 noexec32 [X86-64]
1348 This affects only 32-bit executables.
1349 noexec32=on: enable non-executable mappings (default)
1350 read doesn't imply executable mappings
1351 noexec32=off: disable non-executable mappings
1352 read implies executable mappings
1354 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1355 register save and restore. The kernel will only save
1356 legacy floating-point registers on task switch.
1358 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1360 nohlt [BUGS=ARM]
1362 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1363 instruction doesn't work correctly and not to
1364 use it.
1366 nohalt [IA-64] Tells the kernel not to use the power saving
1367 function PAL_HALT_LIGHT when idle. This increases
1368 power-consumption. On the positive side, it reduces
1369 interrupt wake-up latency, which may improve performance
1370 in certain environments such as networked servers or
1371 real-time systems.
1373 nohz= [KNL] Boottime enable/disable dynamic ticks
1374 Valid arguments: on, off
1375 Default: on
1377 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1379 noirqdebug [X86-32] Disables the code which attempts to detect and
1380 disable unhandled interrupt sources.
1382 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1383 broken timer IRQ sources.
1385 noisapnp [ISAPNP] Disables ISA PnP code.
1387 noinitrd [RAM] Tells the kernel not to load any configured
1388 initial RAM disk.
1390 nointroute [IA-64]
1392 nojitter [IA64] Disables jitter checking for ITC timers.
1394 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1396 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1398 noltlbs [PPC] Do not use large page/tlb entries for kernel
1399 lowmem mapping on PPC40x.
1401 nomca [IA-64] Disable machine check abort handling
1403 nomce [X86-32] Machine Check Exception
1405 nomfgpt [X86-32] Disable Multi-Function General Purpose
1406 Timer usage (for AMD Geode machines).
1408 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1410 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1411 with UP alternatives
1413 noresidual [PPC] Don't use residual data on PReP machines.
1415 noresume [SWSUSP] Disables resume and restores original swap
1416 space.
1418 no-scroll [VGA] Disables scrollback.
1419 This is required for the Braillex ib80-piezo Braille
1420 reader made by F.H. Papenmeier (Germany).
1422 nosbagart [IA-64]
1424 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1426 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1427 and disable the IO APIC. legacy for "maxcpus=0".
1429 nosoftlockup [KNL] Disable the soft-lockup detector.
1431 nosync [HW,M68K] Disables sync negotiation for all devices.
1433 notsc [BUGS=X86-32] Disable Time Stamp Counter
1435 nousb [USB] Disable the USB subsystem
1437 nowb [ARM]
1439 nptcg= [IA64] Override max number of concurrent global TLB
1440 purges which is reported from either PAL_VM_SUMMARY or
1441 SAL PALO.
1443 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1444 one of ['zone', 'node', 'default'] can be specified
1445 This can be set from sysctl after boot.
1446 See Documentation/sysctl/vm.txt for details.
1448 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1450 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1451 Rather than timing out after 20 ms if an EC
1452 command is not properly ACKed, override the length
1453 of the timeout. We have interrupts disabled while
1454 waiting for the ACK, so if this is set too high
1455 interrupts *may* be lost!
1457 opl3= [HW,OSS]
1458 Format: <io>
1460 oprofile.timer= [HW]
1461 Use timer interrupt instead of performance counters
1463 osst= [HW,SCSI] SCSI Tape Driver
1464 Format: <buffer_size>,<write_threshold>
1465 See also Documentation/scsi/st.txt.
1467 panic= [KNL] Kernel behaviour on panic
1468 Format: <timeout>
1470 parkbd.port= [HW] Parallel port number the keyboard adapter is
1471 connected to, default is 0.
1472 Format: <parport#>
1473 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1474 0 for XT, 1 for AT (default is AT).
1475 Format: <mode>
1477 parport= [HW,PPT] Specify parallel ports. 0 disables.
1478 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1479 Use 'auto' to force the driver to use any
1480 IRQ/DMA settings detected (the default is to
1481 ignore detected IRQ/DMA settings because of
1482 possible conflicts). You can specify the base
1483 address, IRQ, and DMA settings; IRQ and DMA
1484 should be numbers, or 'auto' (for using detected
1485 settings on that particular port), or 'nofifo'
1486 (to avoid using a FIFO even if it is detected).
1487 Parallel ports are assigned in the order they
1488 are specified on the command line, starting
1489 with parport0.
1491 parport_init_mode= [HW,PPT]
1492 Configure VIA parallel port to operate in
1493 a specific mode. This is necessary on Pegasos
1494 computer where firmware has no options for setting
1495 up parallel port mode and sets it to spp.
1496 Currently this function knows 686a and 8231 chips.
1497 Format: [spp|ps2|epp|ecp|ecpepp]
1499 pas2= [HW,OSS] Format:
1500 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1502 pas16= [HW,SCSI]
1503 See header of drivers/scsi/pas16.c.
1505 pause_on_oops=
1506 Halt all CPUs after the first oops has been printed for
1507 the specified number of seconds. This is to be used if
1508 your oopses keep scrolling off the screen.
1510 pcbit= [HW,ISDN]
1512 pcd. [PARIDE]
1513 See header of drivers/block/paride/pcd.c.
1514 See also Documentation/paride.txt.
1516 pci=option[,option...] [PCI] various PCI subsystem options:
1517 off [X86-32] don't probe for the PCI bus
1518 bios [X86-32] force use of PCI BIOS, don't access
1519 the hardware directly. Use this if your machine
1520 has a non-standard PCI host bridge.
1521 nobios [X86-32] disallow use of PCI BIOS, only direct
1522 hardware access methods are allowed. Use this
1523 if you experience crashes upon bootup and you
1524 suspect they are caused by the BIOS.
1525 conf1 [X86-32] Force use of PCI Configuration
1526 Mechanism 1.
1527 conf2 [X86-32] Force use of PCI Configuration
1528 Mechanism 2.
1529 noaer [PCIE] If the PCIEAER kernel config parameter is
1530 enabled, this kernel boot option can be used to
1531 disable the use of PCIE advanced error reporting.
1532 nodomains [PCI] Disable support for multiple PCI
1533 root domains (aka PCI segments, in ACPI-speak).
1534 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1535 Configuration
1536 nomsi [MSI] If the PCI_MSI kernel config parameter is
1537 enabled, this kernel boot option can be used to
1538 disable the use of MSI interrupts system-wide.
1539 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1540 routing table. These calls are known to be buggy
1541 on several machines and they hang the machine
1542 when used, but on other computers it's the only
1543 way to get the interrupt routing table. Try
1544 this option if the kernel is unable to allocate
1545 IRQs or discover secondary PCI buses on your
1546 motherboard.
1547 rom [X86-32] Assign address space to expansion ROMs.
1548 Use with caution as certain devices share
1549 address decoders between ROMs and other
1550 resources.
1551 norom [X86-32,X86_64] Do not assign address space to
1552 expansion ROMs that do not already have
1553 BIOS assigned address ranges.
1554 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1555 assigned automatically to PCI devices. You can
1556 make the kernel exclude IRQs of your ISA cards
1557 this way.
1558 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1559 of the PIRQ table (normally generated
1560 by the BIOS) if it is outside the
1561 F0000h-100000h range.
1562 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1563 useful if the kernel is unable to find your
1564 secondary buses and you want to tell it
1565 explicitly which ones they are.
1566 assign-busses [X86-32] Always assign all PCI bus
1567 numbers ourselves, overriding
1568 whatever the firmware may have done.
1569 usepirqmask [X86-32] Honor the possible IRQ mask stored
1570 in the BIOS $PIR table. This is needed on
1571 some systems with broken BIOSes, notably
1572 some HP Pavilion N5400 and Omnibook XE3
1573 notebooks. This will have no effect if ACPI
1574 IRQ routing is enabled.
1575 noacpi [X86-32] Do not use ACPI for IRQ routing
1576 or for PCI scanning.
1577 use_crs [X86-32] Use _CRS for PCI resource
1578 allocation.
1579 routeirq Do IRQ routing for all PCI devices.
1580 This is normally done in pci_enable_device(),
1581 so this option is a temporary workaround
1582 for broken drivers that don't call it.
1583 skip_isa_align [X86] do not align io start addr, so can
1584 handle more pci cards
1585 firmware [ARM] Do not re-enumerate the bus but instead
1586 just use the configuration from the
1587 bootloader. This is currently used on
1588 IXP2000 systems where the bus has to be
1589 configured a certain way for adjunct CPUs.
1590 noearly [X86] Don't do any early type 1 scanning.
1591 This might help on some broken boards which
1592 machine check when some devices' config space
1593 is read. But various workarounds are disabled
1594 and some IOMMU drivers will not work.
1595 bfsort Sort PCI devices into breadth-first order.
1596 This sorting is done to get a device
1597 order compatible with older (<= 2.4) kernels.
1598 nobfsort Don't sort PCI devices into breadth-first order.
1599 cbiosize=nn[KMG] The fixed amount of bus space which is
1600 reserved for the CardBus bridge's IO window.
1601 The default value is 256 bytes.
1602 cbmemsize=nn[KMG] The fixed amount of bus space which is
1603 reserved for the CardBus bridge's memory
1604 window. The default value is 64 megabytes.
1606 pcmv= [HW,PCMCIA] BadgePAD 4
1608 pd. [PARIDE]
1609 See Documentation/paride.txt.
1611 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1612 boot time.
1613 Format: { 0 | 1 }
1614 See arch/parisc/kernel/pdc_chassis.c
1616 pf. [PARIDE]
1617 See Documentation/paride.txt.
1619 pg. [PARIDE]
1620 See Documentation/paride.txt.
1622 pirq= [SMP,APIC] Manual mp-table setup
1623 See Documentation/i386/IO-APIC.txt.
1625 plip= [PPT,NET] Parallel port network link
1626 Format: { parport<nr> | timid | 0 }
1627 See also Documentation/parport.txt.
1629 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1630 Override pmtimer IOPort with a hex value.
1631 e.g. pmtmr=0x508
1633 pnpacpi= [ACPI]
1634 { off }
1636 pnpbios= [ISAPNP]
1637 { on | off | curr | res | no-curr | no-res }
1639 pnp_reserve_irq=
1640 [ISAPNP] Exclude IRQs for the autoconfiguration
1642 pnp_reserve_dma=
1643 [ISAPNP] Exclude DMAs for the autoconfiguration
1645 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1646 Ranges are in pairs (I/O port base and size).
1648 pnp_reserve_mem=
1649 [ISAPNP] Exclude memory regions for the
1650 autoconfiguration.
1651 Ranges are in pairs (memory base and size).
1653 print-fatal-signals=
1654 [KNL] debug: print fatal signals
1655 print-fatal-signals=1: print segfault info to
1656 the kernel console.
1657 default: off.
1659 printk.time= Show timing data prefixed to each printk message line
1660 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1662 profile= [KNL] Enable kernel profiling via /proc/profile
1663 Format: [schedule,]<number>
1664 Param: "schedule" - profile schedule points.
1665 Param: <number> - step/bucket size as a power of 2 for
1666 statistical time based profiling.
1667 Param: "sleep" - profile D-state sleeping (millisecs).
1668 Requires CONFIG_SCHEDSTATS
1669 Param: "kvm" - profile VM exits.
1671 processor.max_cstate= [HW,ACPI]
1672 Limit processor to maximum C-state
1673 max_cstate=9 overrides any DMI blacklist limit.
1675 processor.nocst [HW,ACPI]
1676 Ignore the _CST method to determine C-states,
1677 instead using the legacy FADT method
1679 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1680 before loading.
1681 See Documentation/ramdisk.txt.
1683 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1684 probe for; one of (bare|imps|exps|lifebook|any).
1685 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1686 per second.
1687 psmouse.resetafter= [HW,MOUSE]
1688 Try to reset the device after so many bad packets
1689 (0 = never).
1690 psmouse.resolution=
1691 [HW,MOUSE] Set desired mouse resolution, in dpi.
1692 psmouse.smartscroll=
1693 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1694 0 = disabled, 1 = enabled (default).
1696 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1697 Format:
1698 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1700 pt. [PARIDE]
1701 See Documentation/paride.txt.
1703 pty.legacy_count=
1704 [KNL] Number of legacy pty's. Overwrites compiled-in
1705 default number.
1707 quiet [KNL] Disable most log messages
1709 r128= [HW,DRM]
1711 raid= [HW,RAID]
1712 See Documentation/md.txt.
1714 ramdisk_blocksize= [RAM]
1715 See Documentation/ramdisk.txt.
1717 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1718 See Documentation/ramdisk.txt.
1720 rcupdate.blimit= [KNL,BOOT]
1721 Set maximum number of finished RCU callbacks to process
1722 in one batch.
1724 rcupdate.qhimark= [KNL,BOOT]
1725 Set threshold of queued
1726 RCU callbacks over which batch limiting is disabled.
1728 rcupdate.qlowmark= [KNL,BOOT]
1729 Set threshold of queued RCU callbacks below which
1730 batch limiting is re-enabled.
1732 rdinit= [KNL]
1733 Format: <full_path>
1734 Run specified binary instead of /init from the ramdisk,
1735 used for early userspace startup. See initrd.
1737 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1738 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1739 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1741 relax_domain_level=
1742 [KNL, SMP] Set scheduler's default relax_domain_level.
1743 See Documentation/cpusets.txt.
1745 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1747 reservetop= [X86-32]
1748 Format: nn[KMG]
1749 Reserves a hole at the top of the kernel virtual
1750 address space.
1752 reset_devices [KNL] Force drivers to reset the underlying device
1753 during initialization.
1755 resume= [SWSUSP]
1756 Specify the partition device for software suspend
1758 resume_offset= [SWSUSP]
1759 Specify the offset from the beginning of the partition
1760 given by "resume=" at which the swap header is located,
1761 in <PAGE_SIZE> units (needed only for swap files).
1762 See Documentation/power/swsusp-and-swap-files.txt
1764 retain_initrd [RAM] Keep initrd memory after extraction
1766 rhash_entries= [KNL,NET]
1767 Set number of hash buckets for route cache
1769 riscom8= [HW,SERIAL]
1770 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1772 ro [KNL] Mount root device read-only on boot
1774 root= [KNL] Root filesystem
1776 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1777 mount the root filesystem
1779 rootflags= [KNL] Set root filesystem mount option string
1781 rootfstype= [KNL] Set root filesystem type
1783 rootwait [KNL] Wait (indefinitely) for root device to show up.
1784 Useful for devices that are detected asynchronously
1785 (e.g. USB and MMC devices).
1787 root_plug.vendor_id=
1788 [ROOTPLUG] Override the default vendor ID
1790 root_plug.product_id=
1791 [ROOTPLUG] Override the default product ID
1793 root_plug.debug=
1794 [ROOTPLUG] Enable debugging output
1796 rw [KNL] Mount root device read-write on boot
1798 S [KNL] Run init in single mode
1800 sa1100ir [NET]
1801 See drivers/net/irda/sa1100_ir.c.
1803 sbni= [NET] Granch SBNI12 leased line adapter
1805 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1806 Format: <io>[,<timeout>[,<isapnp>]]
1808 scsi_debug_*= [SCSI]
1809 See drivers/scsi/scsi_debug.c.
1811 scsi_default_dev_flags=
1812 [SCSI] SCSI default device flags
1813 Format: <integer>
1815 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1816 Format: <vendor>:<model>:<flags>
1817 (flags are integer value)
1819 scsi_logging_level= [SCSI] a bit mask of logging levels
1820 See drivers/scsi/scsi_logging.h for bits. Also
1821 settable via sysctl at dev.scsi.logging_level
1822 (/proc/sys/dev/scsi/logging_level).
1823 There is also a nice 'scsi_logging_level' script in the
1824 S390-tools package, available for download at
1825 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1827 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1828 discovered. async scans them in kernel threads,
1829 allowing boot to proceed. none ignores them, expecting
1830 user space to do the scan.
1832 selinux [SELINUX] Disable or enable SELinux at boot time.
1833 Format: { "0" | "1" }
1834 See security/selinux/Kconfig help text.
1835 0 -- disable.
1836 1 -- enable.
1837 Default value is set via kernel config option.
1838 If enabled at boot time, /selinux/disable can be used
1839 later to disable prior to initial policy load.
1841 selinux_compat_net =
1842 [SELINUX] Set initial selinux_compat_net flag value.
1843 Format: { "0" | "1" }
1844 0 -- use new secmark-based packet controls
1845 1 -- use legacy packet controls
1846 Default value is 0 (preferred).
1847 Value can be changed at runtime via
1848 /selinux/compat_net.
1850 serialnumber [BUGS=X86-32]
1852 shapers= [NET]
1853 Maximal number of shapers.
1855 sim710= [SCSI,HW]
1856 See header of drivers/scsi/sim710.c.
1858 simeth= [IA-64]
1859 simscsi=
1861 slram= [HW,MTD]
1863 slub_debug[=options[,slabs]] [MM, SLUB]
1864 Enabling slub_debug allows one to determine the
1865 culprit if slab objects become corrupted. Enabling
1866 slub_debug can create guard zones around objects and
1867 may poison objects when not in use. Also tracks the
1868 last alloc / free. For more information see
1869 Documentation/vm/slub.txt.
1871 slub_max_order= [MM, SLUB]
1872 Determines the maximum allowed order for slabs.
1873 A high setting may cause OOMs due to memory
1874 fragmentation. For more information see
1875 Documentation/vm/slub.txt.
1877 slub_min_objects= [MM, SLUB]
1878 The minimum number of objects per slab. SLUB will
1879 increase the slab order up to slub_max_order to
1880 generate a sufficiently large slab able to contain
1881 the number of objects indicated. The higher the number
1882 of objects the smaller the overhead of tracking slabs
1883 and the less frequently locks need to be acquired.
1884 For more information see Documentation/vm/slub.txt.
1886 slub_min_order= [MM, SLUB]
1887 Determines the mininum page order for slabs. Must be
1888 lower than slub_max_order.
1889 For more information see Documentation/vm/slub.txt.
1891 slub_nomerge [MM, SLUB]
1892 Disable merging of slabs with similar size. May be
1893 necessary if there is some reason to distinguish
1894 allocs to different slabs. Debug options disable
1895 merging on their own.
1896 For more information see Documentation/vm/slub.txt.
1898 smart2= [HW]
1899 Format: <io1>[,<io2>[,...,<io8>]]
1901 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1902 attempt to substitute SMP alternatives once at boot.
1904 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1905 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1906 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1907 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1908 smsc-ircc2.ircc_irq= [HW] IRQ line
1909 smsc-ircc2.ircc_dma= [HW] DMA channel
1910 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1911 0: Toshiba Satellite 1800 (GP data pin select)
1912 1: Fast pin select (default)
1913 2: ATC IRMode
1915 snd-ad1816a= [HW,ALSA]
1917 snd-ad1848= [HW,ALSA]
1919 snd-ali5451= [HW,ALSA]
1921 snd-als100= [HW,ALSA]
1923 snd-als4000= [HW,ALSA]
1925 snd-azt2320= [HW,ALSA]
1927 snd-cmi8330= [HW,ALSA]
1929 snd-cmipci= [HW,ALSA]
1931 snd-cs4231= [HW,ALSA]
1933 snd-cs4232= [HW,ALSA]
1935 snd-cs4236= [HW,ALSA]
1937 snd-cs4281= [HW,ALSA]
1939 snd-cs46xx= [HW,ALSA]
1941 snd-dt019x= [HW,ALSA]
1943 snd-dummy= [HW,ALSA]
1945 snd-emu10k1= [HW,ALSA]
1947 snd-ens1370= [HW,ALSA]
1949 snd-ens1371= [HW,ALSA]
1951 snd-es968= [HW,ALSA]
1953 snd-es1688= [HW,ALSA]
1955 snd-es18xx= [HW,ALSA]
1957 snd-es1938= [HW,ALSA]
1959 snd-es1968= [HW,ALSA]
1961 snd-fm801= [HW,ALSA]
1963 snd-gusclassic= [HW,ALSA]
1965 snd-gusextreme= [HW,ALSA]
1967 snd-gusmax= [HW,ALSA]
1969 snd-hdsp= [HW,ALSA]
1971 snd-ice1712= [HW,ALSA]
1973 snd-intel8x0= [HW,ALSA]
1975 snd-interwave= [HW,ALSA]
1977 snd-interwave-stb=
1978 [HW,ALSA]
1980 snd-korg1212= [HW,ALSA]
1982 snd-maestro3= [HW,ALSA]
1984 snd-mpu401= [HW,ALSA]
1986 snd-mtpav= [HW,ALSA]
1988 snd-nm256= [HW,ALSA]
1990 snd-opl3sa2= [HW,ALSA]
1992 snd-opti92x-ad1848=
1993 [HW,ALSA]
1995 snd-opti92x-cs4231=
1996 [HW,ALSA]
1998 snd-opti93x= [HW,ALSA]
2000 snd-pmac= [HW,ALSA]
2002 snd-rme32= [HW,ALSA]
2004 snd-rme96= [HW,ALSA]
2006 snd-rme9652= [HW,ALSA]
2008 snd-sb8= [HW,ALSA]
2010 snd-sb16= [HW,ALSA]
2012 snd-sbawe= [HW,ALSA]
2014 snd-serial= [HW,ALSA]
2016 snd-sgalaxy= [HW,ALSA]
2018 snd-sonicvibes= [HW,ALSA]
2020 snd-sun-amd7930=
2021 [HW,ALSA]
2023 snd-sun-cs4231= [HW,ALSA]
2025 snd-trident= [HW,ALSA]
2027 snd-usb-audio= [HW,ALSA,USB]
2029 snd-via82xx= [HW,ALSA]
2031 snd-virmidi= [HW,ALSA]
2033 snd-wavefront= [HW,ALSA]
2035 snd-ymfpci= [HW,ALSA]
2037 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2038 See Documentation/sonypi.txt
2040 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2041 See Documentation/specialix.txt.
2043 spia_io_base= [HW,MTD]
2044 spia_fio_base=
2045 spia_pedr=
2046 spia_peddr=
2048 sscape= [HW,OSS]
2049 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2051 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2052 See Documentation/scsi/st.txt.
2054 sti= [PARISC,HW]
2055 Format: <num>
2056 Set the STI (builtin display/keyboard on the HP-PARISC
2057 machines) console (graphic card) which should be used
2058 as the initial boot-console.
2059 See also comment in drivers/video/console/sticore.c.
2061 sti_font= [HW]
2062 See comment in drivers/video/console/sticore.c.
2064 stifb= [HW]
2065 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2067 sunrpc.pool_mode=
2068 [NFS]
2069 Control how the NFS server code allocates CPUs to
2070 service thread pools. Depending on how many NICs
2071 you have and where their interrupts are bound, this
2072 option will affect which CPUs will do NFS serving.
2073 Note: this parameter cannot be changed while the
2074 NFS server is running.
2076 auto the server chooses an appropriate mode
2077 automatically using heuristics
2078 global a single global pool contains all CPUs
2079 percpu one pool for each CPU
2080 pernode one pool for each NUMA node (equivalent
2081 to global on non-NUMA machines)
2083 swiotlb= [IA-64] Number of I/O TLB slabs
2085 switches= [HW,M68k]
2087 sym53c416= [HW,SCSI]
2088 See header of drivers/scsi/sym53c416.c.
2090 sysrq_always_enabled
2091 [KNL]
2092 Ignore sysrq setting - this boot parameter will
2093 neutralize any effect of /proc/sys/kernel/sysrq.
2094 Useful for debugging.
2096 t128= [HW,SCSI]
2097 See header of drivers/scsi/t128.c.
2099 tdfx= [HW,DRM]
2101 thash_entries= [KNL,NET]
2102 Set number of hash buckets for TCP connection
2104 thermal.act= [HW,ACPI]
2105 -1: disable all active trip points in all thermal zones
2106 <degrees C>: override all lowest active trip points
2108 thermal.crt= [HW,ACPI]
2109 -1: disable all critical trip points in all thermal zones
2110 <degrees C>: lower all critical trip points
2112 thermal.nocrt= [HW,ACPI]
2113 Set to disable actions on ACPI thermal zone
2114 critical and hot trip points.
2116 thermal.off= [HW,ACPI]
2117 1: disable ACPI thermal control
2119 thermal.psv= [HW,ACPI]
2120 -1: disable all passive trip points
2121 <degrees C>: override all passive trip points to this value
2123 thermal.tzp= [HW,ACPI]
2124 Specify global default ACPI thermal zone polling rate
2125 <deci-seconds>: poll all this frequency
2126 0: no polling (default)
2128 tipar.timeout= [HW,PPT]
2129 Set communications timeout in tenths of a second
2130 (default 15).
2132 tipar.delay= [HW,PPT]
2133 Set inter-bit delay in microseconds (default 10).
2135 tmscsim= [HW,SCSI]
2136 See comment before function dc390_setup() in
2137 drivers/scsi/tmscsim.c.
2139 tp720= [HW,PS2]
2141 trix= [HW,OSS] MediaTrix AudioTrix Pro
2142 Format:
2143 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2145 turbografx.map[2|3]= [HW,JOY]
2146 TurboGraFX parallel port interface
2147 Format:
2148 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2149 See also Documentation/input/joystick-parport.txt
2151 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2152 See header of drivers/scsi/u14-34f.c.
2154 uart401= [HW,OSS]
2155 Format: <io>,<irq>
2157 uart6850= [HW,OSS]
2158 Format: <io>,<irq>
2160 uhci-hcd.ignore_oc=
2161 [USB] Ignore overcurrent events (default N).
2162 Some badly-designed motherboards generate lots of
2163 bogus events, for ports that aren't wired to
2164 anything. Set this parameter to avoid log spamming.
2165 Note that genuine overcurrent events won't be
2166 reported either.
2168 unknown_nmi_panic
2169 [X86-32,X86-64]
2170 Set unknown_nmi_panic=1 early on boot.
2172 usbcore.autosuspend=
2173 [USB] The autosuspend time delay (in seconds) used
2174 for newly-detected USB devices (default 2). This
2175 is the time required before an idle device will be
2176 autosuspended. Devices for which the delay is set
2177 to a negative value won't be autosuspended at all.
2179 usbhid.mousepoll=
2180 [USBHID] The interval which mice are to be polled at.
2182 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2183 kernel's map of available physical RAM.
2185 vdso= [X86-32,SH,x86-64]
2186 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2187 vdso=1: enable VDSO (default)
2188 vdso=0: disable VDSO mapping
2190 vdso32= [X86-32,X86-64]
2191 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2192 vdso32=1: enable 32-bit VDSO (default)
2193 vdso32=0: disable 32-bit VDSO mapping
2195 vector= [IA-64,SMP]
2196 vector=percpu: enable percpu vector domain
2198 video= [FB] Frame buffer configuration
2199 See Documentation/fb/modedb.txt.
2201 vga= [BOOT,X86-32] Select a particular video mode
2202 See Documentation/i386/boot.txt and
2203 Documentation/svga.txt.
2204 Use vga=ask for menu.
2205 This is actually a boot loader parameter; the value is
2206 passed to the kernel using a special protocol.
2208 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2209 size of <nn>. This can be used to increase the
2210 minimum size (128MB on x86). It can also be used to
2211 decrease the size and leave more room for directly
2212 mapped kernel RAM.
2214 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2215 Format: <command>
2217 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2218 Format: <command>
2220 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2221 Format: <command>
2223 waveartist= [HW,OSS]
2224 Format: <io>,<irq>,<dma>,<dma2>
2226 wd33c93= [HW,SCSI]
2227 See header of drivers/scsi/wd33c93.c.
2229 wd7000= [HW,SCSI]
2230 See header of drivers/scsi/wd7000.c.
2232 wdt= [WDT] Watchdog
2233 See Documentation/watchdog/wdt.txt.
2235 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2236 xd_geo= See header of drivers/block/xd.c.
2238 xirc2ps_cs= [NET,PCMCIA]
2239 Format:
2240 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2242 norandmaps Don't use address space randomization
2243 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2245 ______________________________________________________________________
2247 TODO:
2249 Add documentation for ALSA options.
2250 Add more DRM drivers.