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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] HugeTLB pages to allocate at boot.
778 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
779 On x86 this option can be specified multiple times
780 interleaved with hugepages= to reserve huge pages
781 of different sizes. Valid pages sizes on x86-64
782 are 2M (when the CPU supports "pse") and 1G (when the
783 CPU supports the "pdpe1gb" cpuinfo flag)
784 Note that 1GB pages can only be allocated at boot time
785 using hugepages= and not freed afterwards.
787 i8042.direct [HW] Put keyboard port into non-translated mode
788 i8042.dumbkbd [HW] Pretend that controller can only read data from
789 keyboard and cannot control its state
790 (Don't attempt to blink the leds)
791 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
792 i8042.nokbd [HW] Don't check/create keyboard port
793 i8042.noloop [HW] Disable the AUX Loopback command while probing
794 for the AUX port
795 i8042.nomux [HW] Don't check presence of an active multiplexing
796 controller
797 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
798 controllers
799 i8042.panicblink=
800 [HW] Frequency with which keyboard LEDs should blink
801 when kernel panics (default is 0.5 sec)
802 i8042.reset [HW] Reset the controller during init and cleanup
803 i8042.unlock [HW] Unlock (ignore) the keylock
805 i810= [HW,DRM]
807 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
808 indicates that the driver is running on unsupported
809 hardware.
810 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
811 does not match list of supported models.
812 i8k.power_status
813 [HW] Report power status in /proc/i8k
814 (disabled by default)
815 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
816 capability is set.
818 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
819 See Documentation/mca.txt.
821 icn= [HW,ISDN]
822 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
824 ide= [HW] (E)IDE subsystem
825 Format: ide=nodma or ide=doubler
826 See Documentation/ide/ide.txt.
828 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
829 See Documentation/ide/ide.txt.
831 idle= [X86]
832 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
833 Poll forces a polling idle loop that can slightly improves the performance
834 of waking up a idle CPU, but will use a lot of power and make the system
835 run hot. Not recommended.
836 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
837 to not use it because it doesn't save as much power as a normal idle
838 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
839 as idle=poll.
840 idle=halt. Halt is forced to be used for CPU idle.
841 In such case C2/C3 won't be used again.
842 idle=nomwait. Disable mwait for CPU C-states
844 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
845 Claim all unknown PCI IDE storage controllers.
847 ignore_loglevel [KNL]
848 Ignore loglevel setting - this will print /all/
849 kernel messages to the console. Useful for debugging.
851 ihash_entries= [KNL]
852 Set number of hash buckets for inode cache.
854 in2000= [HW,SCSI]
855 See header of drivers/scsi/in2000.c.
857 init= [KNL]
858 Format: <full_path>
859 Run specified binary instead of /sbin/init as init
860 process.
862 initcall_debug [KNL] Trace initcalls as they are executed. Useful
863 for working out where the kernel is dying during
864 startup.
866 initrd= [BOOT] Specify the location of the initial ramdisk
868 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
869 Format: <irq>
871 inttest= [IA64]
873 iommu= [x86]
874 off
875 force
876 noforce
877 biomerge
878 panic
879 nopanic
880 merge
881 nomerge
882 forcesac
883 soft
886 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
887 off
888 Disable intel iommu driver.
889 igfx_off [Default Off]
890 By default, gfx is mapped as normal device. If a gfx
891 device has a dedicated DMAR unit, the DMAR unit is
892 bypassed by not enabling DMAR with this option. In
893 this case, gfx device will use physical address for
894 DMA.
895 forcedac [x86_64]
896 With this option iommu will not optimize to look
897 for io virtual address below 32 bit forcing dual
898 address cycle on pci bus for cards supporting greater
899 than 32 bit addressing. The default is to look
900 for translation below 32 bit and if not available
901 then look in the higher range.
902 strict [Default Off]
903 With this option on every unmap_single operation will
904 result in a hardware IOTLB flush operation as opposed
905 to batching them for performance.
907 io_delay= [X86-32,X86-64] I/O delay method
908 0x80
909 Standard port 0x80 based delay
910 0xed
911 Alternate port 0xed based delay (needed on some systems)
912 udelay
913 Simple two microseconds delay
914 none
915 No delay
917 io7= [HW] IO7 for Marvel based alpha systems
918 See comment before marvel_specify_io7 in
919 arch/alpha/kernel/core_marvel.c.
921 ip= [IP_PNP]
922 See Documentation/filesystems/nfsroot.txt.
924 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
925 See comment before ip2_setup() in
926 drivers/char/ip2/ip2base.c.
928 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
929 See header of drivers/scsi/ips.c.
931 ports= [IP_VS_FTP] IPVS ftp helper module
932 Default is 21.
933 Up to 8 (IP_VS_APP_MAX_PORTS) ports
934 may be specified.
935 Format: <port>,<port>....
937 irqfixup [HW]
938 When an interrupt is not handled search all handlers
939 for it. Intended to get systems with badly broken
940 firmware running.
942 irqpoll [HW]
943 When an interrupt is not handled search all handlers
944 for it. Also check all handlers each timer
945 interrupt. Intended to get systems with badly broken
946 firmware running.
948 isapnp= [ISAPNP]
949 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
951 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
952 Format:
953 <cpu number>,...,<cpu number>
954 or
955 <cpu number>-<cpu number> (must be a positive range in ascending order)
956 or a mixture
957 <cpu number>,...,<cpu number>-<cpu number>
958 This option can be used to specify one or more CPUs
959 to isolate from the general SMP balancing and scheduling
960 algorithms. The only way to move a process onto or off
961 an "isolated" CPU is via the CPU affinity syscalls.
962 <cpu number> begins at 0 and the maximum value is
963 "number of CPUs in system - 1".
965 This option is the preferred way to isolate CPUs. The
966 alternative -- manually setting the CPU mask of all
967 tasks in the system -- can cause problems and
968 suboptimal load balancer performance.
970 iucv= [HW,NET]
972 js= [HW,JOY] Analog joystick
973 See Documentation/input/joystick.txt.
975 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
976 specifies the amount of memory usable by the kernel
977 for non-movable allocations. The requested amount is
978 spread evenly throughout all nodes in the system. The
979 remaining memory in each node is used for Movable
980 pages. In the event, a node is too small to have both
981 kernelcore and Movable pages, kernelcore pages will
982 take priority and other nodes will have a larger number
983 of kernelcore pages. The Movable zone is used for the
984 allocation of pages that may be reclaimed or moved
985 by the page migration subsystem. This means that
986 HugeTLB pages may not be allocated from this zone.
987 Note that allocations like PTEs-from-HighMem still
988 use the HighMem zone if it exists, and the Normal
989 zone if it does not.
991 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
992 is similar to kernelcore except it specifies the
993 amount of memory used for migratable allocations.
994 If both kernelcore and movablecore is specified,
995 then kernelcore will be at *least* the specified
996 value but may be more. If movablecore on its own
997 is specified, the administrator must be careful
998 that the amount of memory usable for all allocations
999 is not too small.
1001 keepinitrd [HW,ARM]
1003 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1004 in oops dumps.
1006 kgdboc= [HW] kgdb over consoles.
1007 Requires a tty driver that supports console polling.
1008 (only serial suported for now)
1009 Format: <serial_device>[,baud]
1011 l2cr= [PPC]
1013 l3cr= [PPC]
1015 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1016 disabled it.
1018 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1019 C2 power state.
1021 libata.dma= [LIBATA] DMA control
1022 libata.dma=0 Disable all PATA and SATA DMA
1023 libata.dma=1 PATA and SATA Disk DMA only
1024 libata.dma=2 ATAPI (CDROM) DMA only
1025 libata.dma=4 Compact Flash DMA only
1026 Combinations also work, so libata.dma=3 enables DMA
1027 for disks and CDROMs, but not CFs.
1029 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1030 when set.
1031 Format: <int>
1033 libata.force= [LIBATA] Force configurations. The format is comma
1034 separated list of "[ID:]VAL" where ID is
1035 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1036 matching port, link or device. Basically, it matches
1037 the ATA ID string printed on console by libata. If
1038 the whole ID part is omitted, the last PORT and DEVICE
1039 values are used. If ID hasn't been specified yet, the
1040 configuration applies to all ports, links and devices.
1042 If only DEVICE is omitted, the parameter applies to
1043 the port and all links and devices behind it. DEVICE
1044 number of 0 either selects the first device or the
1045 first fan-out link behind PMP device. It does not
1046 select the host link. DEVICE number of 15 selects the
1047 host link and device attached to it.
1049 The VAL specifies the configuration to force. As long
1050 as there's no ambiguity shortcut notation is allowed.
1051 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1052 The following configurations can be forced.
1054 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1055 Any ID with matching PORT is used.
1057 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1059 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1060 udma[/][16,25,33,44,66,100,133] notation is also
1061 allowed.
1063 * [no]ncq: Turn on or off NCQ.
1065 If there are multiple matching configurations changing
1066 the same attribute, the last one is used.
1068 load_ramdisk= [RAM] List of ramdisks to load from floppy
1069 See Documentation/ramdisk.txt.
1071 lockd.nlm_grace_period=P [NFS] Assign grace period.
1072 Format: <integer>
1074 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1075 Format: <integer>
1077 lockd.nlm_timeout=T [NFS] Assign timeout value.
1078 Format: <integer>
1080 lockd.nlm_udpport=M [NFS] Assign UDP port.
1081 Format: <integer>
1083 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1084 Format: <irq>
1086 loglevel= All Kernel Messages with a loglevel smaller than the
1087 console loglevel will be printed to the console. It can
1088 also be changed with klogd or other programs. The
1089 loglevels are defined as follows:
1091 0 (KERN_EMERG) system is unusable
1092 1 (KERN_ALERT) action must be taken immediately
1093 2 (KERN_CRIT) critical conditions
1094 3 (KERN_ERR) error conditions
1095 4 (KERN_WARNING) warning conditions
1096 5 (KERN_NOTICE) normal but significant condition
1097 6 (KERN_INFO) informational
1098 7 (KERN_DEBUG) debug-level messages
1100 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1101 Format: { n | nk | nM }
1102 n must be a power of two. The default size
1103 is set in the kernel config file.
1105 logo.nologo [FB] Disables display of the built-in Linux logo.
1106 This may be used to provide more screen space for
1107 kernel log messages and is useful when debugging
1108 kernel boot problems.
1110 lp=0 [LP] Specify parallel ports to use, e.g,
1111 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1112 lp=reset first parallel port). 'lp=0' disables the
1113 lp=auto printer driver. 'lp=reset' (which can be
1114 specified in addition to the ports) causes
1115 attached printers to be reset. Using
1116 lp=port1,port2,... specifies the parallel ports
1117 to associate lp devices with, starting with
1118 lp0. A port specification may be 'none' to skip
1119 that lp device, or a parport name such as
1120 'parport0'. Specifying 'lp=auto' instead of a
1121 port specification list means that device IDs
1122 from each port should be examined, to see if
1123 an IEEE 1284-compliant printer is attached; if
1124 so, the driver will manage that printer.
1125 See also header of drivers/char/lp.c.
1127 lpj=n [KNL]
1128 Sets loops_per_jiffy to given constant, thus avoiding
1129 time-consuming boot-time autodetection (up to 250 ms per
1130 CPU). 0 enables autodetection (default). To determine
1131 the correct value for your kernel, boot with normal
1132 autodetection and see what value is printed. Note that
1133 on SMP systems the preset will be applied to all CPUs,
1134 which is likely to cause problems if your CPUs need
1135 significantly divergent settings. An incorrect value
1136 will cause delays in the kernel to be wrong, leading to
1137 unpredictable I/O errors and other breakage. Although
1138 unlikely, in the extreme case this might damage your
1139 hardware.
1141 ltpc= [NET]
1142 Format: <io>,<irq>,<dma>
1144 mac5380= [HW,SCSI] Format:
1145 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1147 machvec= [IA64] Force the use of a particular machine-vector
1148 (machvec) in a generic kernel.
1149 Example: machvec=hpzx1_swiotlb
1151 max_loop= [LOOP] Maximum number of loopback devices that can
1152 be mounted
1153 Format: <1-256>
1155 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1156 should make use of. maxcpus=n : n >= 0 limits the
1157 kernel to using 'n' processors. n=0 is a special case,
1158 it is equivalent to "nosmp", which also disables
1159 the IO APIC.
1161 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1162 equal to this physical address is ignored.
1164 max_luns= [SCSI] Maximum number of LUNs to probe.
1165 Should be between 1 and 2^32-1.
1167 max_report_luns=
1168 [SCSI] Maximum number of LUNs received.
1169 Should be between 1 and 16384.
1171 mcatest= [IA-64]
1173 mce [X86-32] Machine Check Exception
1175 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1177 md= [HW] RAID subsystems devices and level
1178 See Documentation/md.txt.
1180 mdacon= [MDA]
1181 Format: <first>,<last>
1182 Specifies range of consoles to be captured by the MDA.
1184 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1185 Amount of memory to be used when the kernel is not able
1186 to see the whole system memory or for test.
1187 [X86-32] Use together with memmap= to avoid physical
1188 address space collisions. Without memmap= PCI devices
1189 could be placed at addresses belonging to unused RAM.
1191 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1192 memory.
1194 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1195 E820 memory map, as specified by the user.
1196 Such memmap=exactmap lines can be constructed based on
1197 BIOS output or other requirements. See the memmap=nn@ss
1198 option description.
1200 memmap=nn[KMG]@ss[KMG]
1201 [KNL] Force usage of a specific region of memory
1202 Region of memory to be used, from ss to ss+nn.
1204 memmap=nn[KMG]#ss[KMG]
1205 [KNL,ACPI] Mark specific memory as ACPI data.
1206 Region of memory to be used, from ss to ss+nn.
1208 memmap=nn[KMG]$ss[KMG]
1209 [KNL,ACPI] Mark specific memory as reserved.
1210 Region of memory to be used, from ss to ss+nn.
1211 Example: Exclude memory from 0x18690000-0x1869ffff
1212 memmap=64K$0x18690000
1213 or
1214 memmap=0x10000$0x18690000
1216 memtest= [KNL,X86] Enable memtest
1217 Format: <integer>
1218 range: 0,4 : pattern number
1219 default : 0 <disable>
1221 meye.*= [HW] Set MotionEye Camera parameters
1222 See Documentation/video4linux/meye.txt.
1224 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1225 Multi-Function General Purpose Timers on AMD Geode
1226 platforms.
1228 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1229 the BIOS has incorrectly applied a workaround. TinyBIOS
1230 version 0.98 is known to be affected, 0.99 fixes the
1231 problem by letting the user disable the workaround.
1233 mga= [HW,DRM]
1235 mminit_loglevel=
1236 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1237 parameter allows control of the logging verbosity for
1238 the additional memory initialisation checks. A value
1239 of 0 disables mminit logging and a level of 4 will
1240 log everything. Information is printed at KERN_DEBUG
1241 so loglevel=8 may also need to be specified.
1243 mousedev.tap_time=
1244 [MOUSE] Maximum time between finger touching and
1245 leaving touchpad surface for touch to be considered
1246 a tap and be reported as a left button click (for
1247 touchpads working in absolute mode only).
1248 Format: <msecs>
1249 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1250 reporting absolute coordinates, such as tablets
1251 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1252 reporting absolute coordinates, such as tablets
1254 mpu401= [HW,OSS]
1255 Format: <io>,<irq>
1257 MTD_Partition= [MTD]
1258 Format: <name>,<region-number>,<size>,<offset>
1260 MTD_Region= [MTD] Format:
1261 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1263 mtdparts= [MTD]
1264 See drivers/mtd/cmdlinepart.c.
1266 mtdset= [ARM]
1267 ARM/S3C2412 JIVE boot control
1269 See arch/arm/mach-s3c2412/mach-jive.c
1271 mtouchusb.raw_coordinates=
1272 [HW] Make the MicroTouch USB driver use raw coordinates
1273 ('y', default) or cooked coordinates ('n')
1275 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1277 NCR_D700= [HW,SCSI]
1278 See header of drivers/scsi/NCR_D700.c.
1280 ncr5380= [HW,SCSI]
1282 ncr53c400= [HW,SCSI]
1284 ncr53c400a= [HW,SCSI]
1286 ncr53c406a= [HW,SCSI]
1288 ncr53c8xx= [HW,SCSI]
1290 netdev= [NET] Network devices parameters
1291 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1292 Note that mem_start is often overloaded to mean
1293 something different and driver-specific.
1294 This usage is only documented in each driver source
1295 file if at all.
1297 nf_conntrack.acct=
1298 [NETFILTER] Enable connection tracking flow accounting
1299 0 to disable accounting
1300 1 to enable accounting
1301 Default value depends on CONFIG_NF_CT_ACCT that is
1302 going to be removed in 2.6.29.
1304 nfsaddrs= [NFS]
1305 See Documentation/filesystems/nfsroot.txt.
1307 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1308 See Documentation/filesystems/nfsroot.txt.
1310 nfs.callback_tcpport=
1311 [NFS] set the TCP port on which the NFSv4 callback
1312 channel should listen.
1314 nfs.idmap_cache_timeout=
1315 [NFS] set the maximum lifetime for idmapper cache
1316 entries.
1318 nfs.enable_ino64=
1319 [NFS] enable 64-bit inode numbers.
1320 If zero, the NFS client will fake up a 32-bit inode
1321 number for the readdir() and stat() syscalls instead
1322 of returning the full 64-bit number.
1323 The default is to return 64-bit inode numbers.
1325 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1326 when a NMI is triggered.
1327 Format: [state][,regs][,debounce][,die]
1329 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1331 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1332 emulation library even if a 387 maths coprocessor
1333 is present.
1335 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1336 caches in the slab allocator. Saves per-node memory,
1337 but will impact performance.
1339 noalign [KNL,ARM]
1341 noapic [SMP,APIC] Tells the kernel to not make use of any
1342 IOAPICs that may be present in the system.
1344 nobats [PPC] Do not use BATs for mapping kernel lowmem
1345 on "Classic" PPC cores.
1347 nocache [ARM]
1349 nodelayacct [KNL] Disable per-task delay accounting
1351 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1353 noefi [X86-32,X86-64] Disable EFI runtime services support.
1355 noexec [IA-64]
1357 noexec [X86-32,X86-64]
1358 On X86-32 available only on PAE configured kernels.
1359 noexec=on: enable non-executable mappings (default)
1360 noexec=off: disable non-executable mappings
1362 noexec32 [X86-64]
1363 This affects only 32-bit executables.
1364 noexec32=on: enable non-executable mappings (default)
1365 read doesn't imply executable mappings
1366 noexec32=off: disable non-executable mappings
1367 read implies executable mappings
1369 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1370 register save and restore. The kernel will only save
1371 legacy floating-point registers on task switch.
1373 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1375 nohlt [BUGS=ARM]
1377 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1378 instruction doesn't work correctly and not to
1379 use it.
1381 nohalt [IA-64] Tells the kernel not to use the power saving
1382 function PAL_HALT_LIGHT when idle. This increases
1383 power-consumption. On the positive side, it reduces
1384 interrupt wake-up latency, which may improve performance
1385 in certain environments such as networked servers or
1386 real-time systems.
1388 nohz= [KNL] Boottime enable/disable dynamic ticks
1389 Valid arguments: on, off
1390 Default: on
1392 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1394 noirqdebug [X86-32] Disables the code which attempts to detect and
1395 disable unhandled interrupt sources.
1397 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1398 broken timer IRQ sources.
1400 noisapnp [ISAPNP] Disables ISA PnP code.
1402 noinitrd [RAM] Tells the kernel not to load any configured
1403 initial RAM disk.
1405 nointroute [IA-64]
1407 nojitter [IA64] Disables jitter checking for ITC timers.
1409 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1411 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1413 noltlbs [PPC] Do not use large page/tlb entries for kernel
1414 lowmem mapping on PPC40x.
1416 nomca [IA-64] Disable machine check abort handling
1418 nomce [X86-32] Machine Check Exception
1420 nomfgpt [X86-32] Disable Multi-Function General Purpose
1421 Timer usage (for AMD Geode machines).
1423 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1425 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1426 with UP alternatives
1428 noresidual [PPC] Don't use residual data on PReP machines.
1430 noresume [SWSUSP] Disables resume and restores original swap
1431 space.
1433 no-scroll [VGA] Disables scrollback.
1434 This is required for the Braillex ib80-piezo Braille
1435 reader made by F.H. Papenmeier (Germany).
1437 nosbagart [IA-64]
1439 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1441 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1442 and disable the IO APIC. legacy for "maxcpus=0".
1444 nosoftlockup [KNL] Disable the soft-lockup detector.
1446 nosync [HW,M68K] Disables sync negotiation for all devices.
1448 notsc [BUGS=X86-32] Disable Time Stamp Counter
1450 nousb [USB] Disable the USB subsystem
1452 nowb [ARM]
1454 nptcg= [IA64] Override max number of concurrent global TLB
1455 purges which is reported from either PAL_VM_SUMMARY or
1456 SAL PALO.
1458 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1459 one of ['zone', 'node', 'default'] can be specified
1460 This can be set from sysctl after boot.
1461 See Documentation/sysctl/vm.txt for details.
1463 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1465 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1466 Rather than timing out after 20 ms if an EC
1467 command is not properly ACKed, override the length
1468 of the timeout. We have interrupts disabled while
1469 waiting for the ACK, so if this is set too high
1470 interrupts *may* be lost!
1472 opl3= [HW,OSS]
1473 Format: <io>
1475 oprofile.timer= [HW]
1476 Use timer interrupt instead of performance counters
1478 osst= [HW,SCSI] SCSI Tape Driver
1479 Format: <buffer_size>,<write_threshold>
1480 See also Documentation/scsi/st.txt.
1482 panic= [KNL] Kernel behaviour on panic
1483 Format: <timeout>
1485 parkbd.port= [HW] Parallel port number the keyboard adapter is
1486 connected to, default is 0.
1487 Format: <parport#>
1488 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1489 0 for XT, 1 for AT (default is AT).
1490 Format: <mode>
1492 parport= [HW,PPT] Specify parallel ports. 0 disables.
1493 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1494 Use 'auto' to force the driver to use any
1495 IRQ/DMA settings detected (the default is to
1496 ignore detected IRQ/DMA settings because of
1497 possible conflicts). You can specify the base
1498 address, IRQ, and DMA settings; IRQ and DMA
1499 should be numbers, or 'auto' (for using detected
1500 settings on that particular port), or 'nofifo'
1501 (to avoid using a FIFO even if it is detected).
1502 Parallel ports are assigned in the order they
1503 are specified on the command line, starting
1504 with parport0.
1506 parport_init_mode= [HW,PPT]
1507 Configure VIA parallel port to operate in
1508 a specific mode. This is necessary on Pegasos
1509 computer where firmware has no options for setting
1510 up parallel port mode and sets it to spp.
1511 Currently this function knows 686a and 8231 chips.
1512 Format: [spp|ps2|epp|ecp|ecpepp]
1514 pas2= [HW,OSS] Format:
1515 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1517 pas16= [HW,SCSI]
1518 See header of drivers/scsi/pas16.c.
1520 pause_on_oops=
1521 Halt all CPUs after the first oops has been printed for
1522 the specified number of seconds. This is to be used if
1523 your oopses keep scrolling off the screen.
1525 pcbit= [HW,ISDN]
1527 pcd. [PARIDE]
1528 See header of drivers/block/paride/pcd.c.
1529 See also Documentation/paride.txt.
1531 pci=option[,option...] [PCI] various PCI subsystem options:
1532 off [X86-32] don't probe for the PCI bus
1533 bios [X86-32] force use of PCI BIOS, don't access
1534 the hardware directly. Use this if your machine
1535 has a non-standard PCI host bridge.
1536 nobios [X86-32] disallow use of PCI BIOS, only direct
1537 hardware access methods are allowed. Use this
1538 if you experience crashes upon bootup and you
1539 suspect they are caused by the BIOS.
1540 conf1 [X86-32] Force use of PCI Configuration
1541 Mechanism 1.
1542 conf2 [X86-32] Force use of PCI Configuration
1543 Mechanism 2.
1544 noaer [PCIE] If the PCIEAER kernel config parameter is
1545 enabled, this kernel boot option can be used to
1546 disable the use of PCIE advanced error reporting.
1547 nodomains [PCI] Disable support for multiple PCI
1548 root domains (aka PCI segments, in ACPI-speak).
1549 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1550 Configuration
1551 nomsi [MSI] If the PCI_MSI kernel config parameter is
1552 enabled, this kernel boot option can be used to
1553 disable the use of MSI interrupts system-wide.
1554 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1555 routing table. These calls are known to be buggy
1556 on several machines and they hang the machine
1557 when used, but on other computers it's the only
1558 way to get the interrupt routing table. Try
1559 this option if the kernel is unable to allocate
1560 IRQs or discover secondary PCI buses on your
1561 motherboard.
1562 rom [X86-32] Assign address space to expansion ROMs.
1563 Use with caution as certain devices share
1564 address decoders between ROMs and other
1565 resources.
1566 norom [X86-32,X86_64] Do not assign address space to
1567 expansion ROMs that do not already have
1568 BIOS assigned address ranges.
1569 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1570 assigned automatically to PCI devices. You can
1571 make the kernel exclude IRQs of your ISA cards
1572 this way.
1573 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1574 of the PIRQ table (normally generated
1575 by the BIOS) if it is outside the
1576 F0000h-100000h range.
1577 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1578 useful if the kernel is unable to find your
1579 secondary buses and you want to tell it
1580 explicitly which ones they are.
1581 assign-busses [X86-32] Always assign all PCI bus
1582 numbers ourselves, overriding
1583 whatever the firmware may have done.
1584 usepirqmask [X86-32] Honor the possible IRQ mask stored
1585 in the BIOS $PIR table. This is needed on
1586 some systems with broken BIOSes, notably
1587 some HP Pavilion N5400 and Omnibook XE3
1588 notebooks. This will have no effect if ACPI
1589 IRQ routing is enabled.
1590 noacpi [X86-32] Do not use ACPI for IRQ routing
1591 or for PCI scanning.
1592 use_crs [X86-32] Use _CRS for PCI resource
1593 allocation.
1594 routeirq Do IRQ routing for all PCI devices.
1595 This is normally done in pci_enable_device(),
1596 so this option is a temporary workaround
1597 for broken drivers that don't call it.
1598 skip_isa_align [X86] do not align io start addr, so can
1599 handle more pci cards
1600 firmware [ARM] Do not re-enumerate the bus but instead
1601 just use the configuration from the
1602 bootloader. This is currently used on
1603 IXP2000 systems where the bus has to be
1604 configured a certain way for adjunct CPUs.
1605 noearly [X86] Don't do any early type 1 scanning.
1606 This might help on some broken boards which
1607 machine check when some devices' config space
1608 is read. But various workarounds are disabled
1609 and some IOMMU drivers will not work.
1610 bfsort Sort PCI devices into breadth-first order.
1611 This sorting is done to get a device
1612 order compatible with older (<= 2.4) kernels.
1613 nobfsort Don't sort PCI devices into breadth-first order.
1614 cbiosize=nn[KMG] The fixed amount of bus space which is
1615 reserved for the CardBus bridge's IO window.
1616 The default value is 256 bytes.
1617 cbmemsize=nn[KMG] The fixed amount of bus space which is
1618 reserved for the CardBus bridge's memory
1619 window. The default value is 64 megabytes.
1621 pcmv= [HW,PCMCIA] BadgePAD 4
1623 pd. [PARIDE]
1624 See Documentation/paride.txt.
1626 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1627 boot time.
1628 Format: { 0 | 1 }
1629 See arch/parisc/kernel/pdc_chassis.c
1631 pf. [PARIDE]
1632 See Documentation/paride.txt.
1634 pg. [PARIDE]
1635 See Documentation/paride.txt.
1637 pirq= [SMP,APIC] Manual mp-table setup
1638 See Documentation/i386/IO-APIC.txt.
1640 plip= [PPT,NET] Parallel port network link
1641 Format: { parport<nr> | timid | 0 }
1642 See also Documentation/parport.txt.
1644 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1645 Override pmtimer IOPort with a hex value.
1646 e.g. pmtmr=0x508
1648 pnpacpi= [ACPI]
1649 { off }
1651 pnpbios= [ISAPNP]
1652 { on | off | curr | res | no-curr | no-res }
1654 pnp_reserve_irq=
1655 [ISAPNP] Exclude IRQs for the autoconfiguration
1657 pnp_reserve_dma=
1658 [ISAPNP] Exclude DMAs for the autoconfiguration
1660 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1661 Ranges are in pairs (I/O port base and size).
1663 pnp_reserve_mem=
1664 [ISAPNP] Exclude memory regions for the
1665 autoconfiguration.
1666 Ranges are in pairs (memory base and size).
1668 print-fatal-signals=
1669 [KNL] debug: print fatal signals
1670 print-fatal-signals=1: print segfault info to
1671 the kernel console.
1672 default: off.
1674 printk.time= Show timing data prefixed to each printk message line
1675 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1677 profile= [KNL] Enable kernel profiling via /proc/profile
1678 Format: [schedule,]<number>
1679 Param: "schedule" - profile schedule points.
1680 Param: <number> - step/bucket size as a power of 2 for
1681 statistical time based profiling.
1682 Param: "sleep" - profile D-state sleeping (millisecs).
1683 Requires CONFIG_SCHEDSTATS
1684 Param: "kvm" - profile VM exits.
1686 processor.max_cstate= [HW,ACPI]
1687 Limit processor to maximum C-state
1688 max_cstate=9 overrides any DMI blacklist limit.
1690 processor.nocst [HW,ACPI]
1691 Ignore the _CST method to determine C-states,
1692 instead using the legacy FADT method
1694 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1695 before loading.
1696 See Documentation/ramdisk.txt.
1698 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1699 probe for; one of (bare|imps|exps|lifebook|any).
1700 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1701 per second.
1702 psmouse.resetafter= [HW,MOUSE]
1703 Try to reset the device after so many bad packets
1704 (0 = never).
1705 psmouse.resolution=
1706 [HW,MOUSE] Set desired mouse resolution, in dpi.
1707 psmouse.smartscroll=
1708 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1709 0 = disabled, 1 = enabled (default).
1711 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1712 Format:
1713 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1715 pt. [PARIDE]
1716 See Documentation/paride.txt.
1718 pty.legacy_count=
1719 [KNL] Number of legacy pty's. Overwrites compiled-in
1720 default number.
1722 quiet [KNL] Disable most log messages
1724 r128= [HW,DRM]
1726 raid= [HW,RAID]
1727 See Documentation/md.txt.
1729 ramdisk_blocksize= [RAM]
1730 See Documentation/ramdisk.txt.
1732 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1733 See Documentation/ramdisk.txt.
1735 rcupdate.blimit= [KNL,BOOT]
1736 Set maximum number of finished RCU callbacks to process
1737 in one batch.
1739 rcupdate.qhimark= [KNL,BOOT]
1740 Set threshold of queued
1741 RCU callbacks over which batch limiting is disabled.
1743 rcupdate.qlowmark= [KNL,BOOT]
1744 Set threshold of queued RCU callbacks below which
1745 batch limiting is re-enabled.
1747 rdinit= [KNL]
1748 Format: <full_path>
1749 Run specified binary instead of /init from the ramdisk,
1750 used for early userspace startup. See initrd.
1752 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1753 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1754 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1756 relax_domain_level=
1757 [KNL, SMP] Set scheduler's default relax_domain_level.
1758 See Documentation/cpusets.txt.
1760 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1762 reservetop= [X86-32]
1763 Format: nn[KMG]
1764 Reserves a hole at the top of the kernel virtual
1765 address space.
1767 reset_devices [KNL] Force drivers to reset the underlying device
1768 during initialization.
1770 resume= [SWSUSP]
1771 Specify the partition device for software suspend
1773 resume_offset= [SWSUSP]
1774 Specify the offset from the beginning of the partition
1775 given by "resume=" at which the swap header is located,
1776 in <PAGE_SIZE> units (needed only for swap files).
1777 See Documentation/power/swsusp-and-swap-files.txt
1779 retain_initrd [RAM] Keep initrd memory after extraction
1781 rhash_entries= [KNL,NET]
1782 Set number of hash buckets for route cache
1784 riscom8= [HW,SERIAL]
1785 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1787 ro [KNL] Mount root device read-only on boot
1789 root= [KNL] Root filesystem
1791 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1792 mount the root filesystem
1794 rootflags= [KNL] Set root filesystem mount option string
1796 rootfstype= [KNL] Set root filesystem type
1798 rootwait [KNL] Wait (indefinitely) for root device to show up.
1799 Useful for devices that are detected asynchronously
1800 (e.g. USB and MMC devices).
1802 root_plug.vendor_id=
1803 [ROOTPLUG] Override the default vendor ID
1805 root_plug.product_id=
1806 [ROOTPLUG] Override the default product ID
1808 root_plug.debug=
1809 [ROOTPLUG] Enable debugging output
1811 rw [KNL] Mount root device read-write on boot
1813 S [KNL] Run init in single mode
1815 sa1100ir [NET]
1816 See drivers/net/irda/sa1100_ir.c.
1818 sbni= [NET] Granch SBNI12 leased line adapter
1820 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1821 Format: <io>[,<timeout>[,<isapnp>]]
1823 scsi_debug_*= [SCSI]
1824 See drivers/scsi/scsi_debug.c.
1826 scsi_default_dev_flags=
1827 [SCSI] SCSI default device flags
1828 Format: <integer>
1830 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1831 Format: <vendor>:<model>:<flags>
1832 (flags are integer value)
1834 scsi_logging_level= [SCSI] a bit mask of logging levels
1835 See drivers/scsi/scsi_logging.h for bits. Also
1836 settable via sysctl at dev.scsi.logging_level
1837 (/proc/sys/dev/scsi/logging_level).
1838 There is also a nice 'scsi_logging_level' script in the
1839 S390-tools package, available for download at
1840 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1842 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1843 discovered. async scans them in kernel threads,
1844 allowing boot to proceed. none ignores them, expecting
1845 user space to do the scan.
1847 selinux [SELINUX] Disable or enable SELinux at boot time.
1848 Format: { "0" | "1" }
1849 See security/selinux/Kconfig help text.
1850 0 -- disable.
1851 1 -- enable.
1852 Default value is set via kernel config option.
1853 If enabled at boot time, /selinux/disable can be used
1854 later to disable prior to initial policy load.
1856 selinux_compat_net =
1857 [SELINUX] Set initial selinux_compat_net flag value.
1858 Format: { "0" | "1" }
1859 0 -- use new secmark-based packet controls
1860 1 -- use legacy packet controls
1861 Default value is 0 (preferred).
1862 Value can be changed at runtime via
1863 /selinux/compat_net.
1865 serialnumber [BUGS=X86-32]
1867 shapers= [NET]
1868 Maximal number of shapers.
1870 sim710= [SCSI,HW]
1871 See header of drivers/scsi/sim710.c.
1873 simeth= [IA-64]
1874 simscsi=
1876 slram= [HW,MTD]
1878 slub_debug[=options[,slabs]] [MM, SLUB]
1879 Enabling slub_debug allows one to determine the
1880 culprit if slab objects become corrupted. Enabling
1881 slub_debug can create guard zones around objects and
1882 may poison objects when not in use. Also tracks the
1883 last alloc / free. For more information see
1884 Documentation/vm/slub.txt.
1886 slub_max_order= [MM, SLUB]
1887 Determines the maximum allowed order for slabs.
1888 A high setting may cause OOMs due to memory
1889 fragmentation. For more information see
1890 Documentation/vm/slub.txt.
1892 slub_min_objects= [MM, SLUB]
1893 The minimum number of objects per slab. SLUB will
1894 increase the slab order up to slub_max_order to
1895 generate a sufficiently large slab able to contain
1896 the number of objects indicated. The higher the number
1897 of objects the smaller the overhead of tracking slabs
1898 and the less frequently locks need to be acquired.
1899 For more information see Documentation/vm/slub.txt.
1901 slub_min_order= [MM, SLUB]
1902 Determines the mininum page order for slabs. Must be
1903 lower than slub_max_order.
1904 For more information see Documentation/vm/slub.txt.
1906 slub_nomerge [MM, SLUB]
1907 Disable merging of slabs with similar size. May be
1908 necessary if there is some reason to distinguish
1909 allocs to different slabs. Debug options disable
1910 merging on their own.
1911 For more information see Documentation/vm/slub.txt.
1913 smart2= [HW]
1914 Format: <io1>[,<io2>[,...,<io8>]]
1916 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1917 attempt to substitute SMP alternatives once at boot.
1919 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1920 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1921 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1922 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1923 smsc-ircc2.ircc_irq= [HW] IRQ line
1924 smsc-ircc2.ircc_dma= [HW] DMA channel
1925 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1926 0: Toshiba Satellite 1800 (GP data pin select)
1927 1: Fast pin select (default)
1928 2: ATC IRMode
1930 snd-ad1816a= [HW,ALSA]
1932 snd-ad1848= [HW,ALSA]
1934 snd-ali5451= [HW,ALSA]
1936 snd-als100= [HW,ALSA]
1938 snd-als4000= [HW,ALSA]
1940 snd-azt2320= [HW,ALSA]
1942 snd-cmi8330= [HW,ALSA]
1944 snd-cmipci= [HW,ALSA]
1946 snd-cs4231= [HW,ALSA]
1948 snd-cs4232= [HW,ALSA]
1950 snd-cs4236= [HW,ALSA]
1952 snd-cs4281= [HW,ALSA]
1954 snd-cs46xx= [HW,ALSA]
1956 snd-dt019x= [HW,ALSA]
1958 snd-dummy= [HW,ALSA]
1960 snd-emu10k1= [HW,ALSA]
1962 snd-ens1370= [HW,ALSA]
1964 snd-ens1371= [HW,ALSA]
1966 snd-es968= [HW,ALSA]
1968 snd-es1688= [HW,ALSA]
1970 snd-es18xx= [HW,ALSA]
1972 snd-es1938= [HW,ALSA]
1974 snd-es1968= [HW,ALSA]
1976 snd-fm801= [HW,ALSA]
1978 snd-gusclassic= [HW,ALSA]
1980 snd-gusextreme= [HW,ALSA]
1982 snd-gusmax= [HW,ALSA]
1984 snd-hdsp= [HW,ALSA]
1986 snd-ice1712= [HW,ALSA]
1988 snd-intel8x0= [HW,ALSA]
1990 snd-interwave= [HW,ALSA]
1992 snd-interwave-stb=
1993 [HW,ALSA]
1995 snd-korg1212= [HW,ALSA]
1997 snd-maestro3= [HW,ALSA]
1999 snd-mpu401= [HW,ALSA]
2001 snd-mtpav= [HW,ALSA]
2003 snd-nm256= [HW,ALSA]
2005 snd-opl3sa2= [HW,ALSA]
2007 snd-opti92x-ad1848=
2008 [HW,ALSA]
2010 snd-opti92x-cs4231=
2011 [HW,ALSA]
2013 snd-opti93x= [HW,ALSA]
2015 snd-pmac= [HW,ALSA]
2017 snd-rme32= [HW,ALSA]
2019 snd-rme96= [HW,ALSA]
2021 snd-rme9652= [HW,ALSA]
2023 snd-sb8= [HW,ALSA]
2025 snd-sb16= [HW,ALSA]
2027 snd-sbawe= [HW,ALSA]
2029 snd-serial= [HW,ALSA]
2031 snd-sgalaxy= [HW,ALSA]
2033 snd-sonicvibes= [HW,ALSA]
2035 snd-sun-amd7930=
2036 [HW,ALSA]
2038 snd-sun-cs4231= [HW,ALSA]
2040 snd-trident= [HW,ALSA]
2042 snd-usb-audio= [HW,ALSA,USB]
2044 snd-via82xx= [HW,ALSA]
2046 snd-virmidi= [HW,ALSA]
2048 snd-wavefront= [HW,ALSA]
2050 snd-ymfpci= [HW,ALSA]
2052 softlockup_panic=
2053 [KNL] Should the soft-lockup detector generate panics.
2055 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2056 See Documentation/sonypi.txt
2058 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2059 See Documentation/specialix.txt.
2061 spia_io_base= [HW,MTD]
2062 spia_fio_base=
2063 spia_pedr=
2064 spia_peddr=
2066 sscape= [HW,OSS]
2067 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2069 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2070 See Documentation/scsi/st.txt.
2072 sti= [PARISC,HW]
2073 Format: <num>
2074 Set the STI (builtin display/keyboard on the HP-PARISC
2075 machines) console (graphic card) which should be used
2076 as the initial boot-console.
2077 See also comment in drivers/video/console/sticore.c.
2079 sti_font= [HW]
2080 See comment in drivers/video/console/sticore.c.
2082 stifb= [HW]
2083 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2085 sunrpc.pool_mode=
2086 [NFS]
2087 Control how the NFS server code allocates CPUs to
2088 service thread pools. Depending on how many NICs
2089 you have and where their interrupts are bound, this
2090 option will affect which CPUs will do NFS serving.
2091 Note: this parameter cannot be changed while the
2092 NFS server is running.
2094 auto the server chooses an appropriate mode
2095 automatically using heuristics
2096 global a single global pool contains all CPUs
2097 percpu one pool for each CPU
2098 pernode one pool for each NUMA node (equivalent
2099 to global on non-NUMA machines)
2101 swiotlb= [IA-64] Number of I/O TLB slabs
2103 switches= [HW,M68k]
2105 sym53c416= [HW,SCSI]
2106 See header of drivers/scsi/sym53c416.c.
2108 sysrq_always_enabled
2109 [KNL]
2110 Ignore sysrq setting - this boot parameter will
2111 neutralize any effect of /proc/sys/kernel/sysrq.
2112 Useful for debugging.
2114 t128= [HW,SCSI]
2115 See header of drivers/scsi/t128.c.
2117 tdfx= [HW,DRM]
2119 thash_entries= [KNL,NET]
2120 Set number of hash buckets for TCP connection
2122 thermal.act= [HW,ACPI]
2123 -1: disable all active trip points in all thermal zones
2124 <degrees C>: override all lowest active trip points
2126 thermal.crt= [HW,ACPI]
2127 -1: disable all critical trip points in all thermal zones
2128 <degrees C>: lower all critical trip points
2130 thermal.nocrt= [HW,ACPI]
2131 Set to disable actions on ACPI thermal zone
2132 critical and hot trip points.
2134 thermal.off= [HW,ACPI]
2135 1: disable ACPI thermal control
2137 thermal.psv= [HW,ACPI]
2138 -1: disable all passive trip points
2139 <degrees C>: override all passive trip points to this value
2141 thermal.tzp= [HW,ACPI]
2142 Specify global default ACPI thermal zone polling rate
2143 <deci-seconds>: poll all this frequency
2144 0: no polling (default)
2146 tipar.timeout= [HW,PPT]
2147 Set communications timeout in tenths of a second
2148 (default 15).
2150 tipar.delay= [HW,PPT]
2151 Set inter-bit delay in microseconds (default 10).
2153 tmscsim= [HW,SCSI]
2154 See comment before function dc390_setup() in
2155 drivers/scsi/tmscsim.c.
2157 tp720= [HW,PS2]
2159 trix= [HW,OSS] MediaTrix AudioTrix Pro
2160 Format:
2161 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2163 turbografx.map[2|3]= [HW,JOY]
2164 TurboGraFX parallel port interface
2165 Format:
2166 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2167 See also Documentation/input/joystick-parport.txt
2169 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2170 See header of drivers/scsi/u14-34f.c.
2172 uart401= [HW,OSS]
2173 Format: <io>,<irq>
2175 uart6850= [HW,OSS]
2176 Format: <io>,<irq>
2178 uhci-hcd.ignore_oc=
2179 [USB] Ignore overcurrent events (default N).
2180 Some badly-designed motherboards generate lots of
2181 bogus events, for ports that aren't wired to
2182 anything. Set this parameter to avoid log spamming.
2183 Note that genuine overcurrent events won't be
2184 reported either.
2186 unknown_nmi_panic
2187 [X86-32,X86-64]
2188 Set unknown_nmi_panic=1 early on boot.
2190 usbcore.autosuspend=
2191 [USB] The autosuspend time delay (in seconds) used
2192 for newly-detected USB devices (default 2). This
2193 is the time required before an idle device will be
2194 autosuspended. Devices for which the delay is set
2195 to a negative value won't be autosuspended at all.
2197 usbhid.mousepoll=
2198 [USBHID] The interval which mice are to be polled at.
2200 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2201 kernel's map of available physical RAM.
2203 vdso= [X86-32,SH,x86-64]
2204 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2205 vdso=1: enable VDSO (default)
2206 vdso=0: disable VDSO mapping
2208 vdso32= [X86-32,X86-64]
2209 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2210 vdso32=1: enable 32-bit VDSO (default)
2211 vdso32=0: disable 32-bit VDSO mapping
2213 vector= [IA-64,SMP]
2214 vector=percpu: enable percpu vector domain
2216 video= [FB] Frame buffer configuration
2217 See Documentation/fb/modedb.txt.
2219 vga= [BOOT,X86-32] Select a particular video mode
2220 See Documentation/i386/boot.txt and
2221 Documentation/svga.txt.
2222 Use vga=ask for menu.
2223 This is actually a boot loader parameter; the value is
2224 passed to the kernel using a special protocol.
2226 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2227 size of <nn>. This can be used to increase the
2228 minimum size (128MB on x86). It can also be used to
2229 decrease the size and leave more room for directly
2230 mapped kernel RAM.
2232 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2233 Format: <command>
2235 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2236 Format: <command>
2238 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2239 Format: <command>
2241 waveartist= [HW,OSS]
2242 Format: <io>,<irq>,<dma>,<dma2>
2244 wd33c93= [HW,SCSI]
2245 See header of drivers/scsi/wd33c93.c.
2247 wd7000= [HW,SCSI]
2248 See header of drivers/scsi/wd7000.c.
2250 wdt= [WDT] Watchdog
2251 See Documentation/watchdog/wdt.txt.
2253 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2254 xd_geo= See header of drivers/block/xd.c.
2256 xirc2ps_cs= [NET,PCMCIA]
2257 Format:
2258 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2260 norandmaps Don't use address space randomization
2261 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2263 ______________________________________________________________________
2265 TODO:
2267 Add documentation for ALSA options.
2268 Add more DRM drivers.