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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend is enabled.
91 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
99 X86-32 X86-32, aka i386 architecture is enabled.
100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
104 In addition, the following text indicates that the option:
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
110 Parameters denoted with BOOT are actually interpreted by the boot
111 loader, and have no meaning to the kernel directly.
112 Do not modify the syntax of boot loader parameters without extreme
113 need or coordination with <Documentation/i386/boot.txt>.
115 There are also arch-specific kernel-parameters not documented here.
116 See for example <Documentation/x86_64/boot-options.txt>.
118 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119 a trailing = on the name of any parameter states that that parameter will
120 be entered as an environment variable, whereas its absence indicates that
121 it will appear as a kernel argument readable via /proc/cmdline by programs
122 running once the system is up.
124 The number of kernel parameters is not limited, but the length of the
125 complete command line (parameters including spaces etc.) is limited to
126 a fixed number of characters. This limit depends on the architecture
127 and is between 256 and 4096 characters. It is defined in the file
128 ./include/asm/setup.h as COMMAND_LINE_SIZE.
131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
133 Format: { force | off | ht | strict | noirq }
134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
138 strict -- Be less tolerant of platforms that are not
139 strictly ACPI specification compliant.
141 See also Documentation/power/pm.txt, pci=noacpi
143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
147 default: 0
149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode, s3_beep }
151 See Documentation/power/video.txt for s3_bios and s3_mode.
152 s3_beep is for debugging; it makes the PC's speaker beep
153 as soon as the kernel's real-mode entry point is called.
155 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
156 Format: { level | edge | high | low }
158 acpi_irq_balance [HW,ACPI]
159 ACPI will balance active IRQs
160 default in APIC mode
162 acpi_irq_nobalance [HW,ACPI]
163 ACPI will not move active IRQs (default)
164 default in PIC mode
166 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
167 use by PCI
168 Format: <irq>,<irq>...
170 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
171 Format: <irq>,<irq>...
173 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
175 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
176 Format: To spoof as Windows 98: ="Microsoft Windows"
178 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
179 acpi_osi="string1" # add string1 -- only one string
180 acpi_osi="!string2" # remove built-in string2
181 acpi_osi= # disable all strings
183 acpi_serialize [HW,ACPI] force serialization of AML methods
185 acpi_skip_timer_override [HW,ACPI]
186 Recognize and ignore IRQ0/pin2 Interrupt Override.
187 For broken nForce2 BIOS resulting in XT-PIC timer.
188 acpi_use_timer_override [HW,ACPI}
189 Use timer override. For some broken Nvidia NF5 boards
190 that require a timer override, but don't have
191 HPET
193 acpi.debug_layer= [HW,ACPI]
194 Format: <int>
195 Each bit of the <int> indicates an ACPI debug layer,
196 1: enable, 0: disable. It is useful for boot time
197 debugging. After system has booted up, it can be set
198 via /sys/module/acpi/parameters/debug_layer.
199 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
200 Available bits (add the numbers together) to enable debug output
201 for specific parts of the ACPI subsystem:
202 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
203 0x10 namespace 0x20 parser 0x40 dispatcher
204 0x80 executer 0x100 resources 0x200 acpica debugger
205 0x400 os services 0x800 acpica disassembler.
206 The number can be in decimal or prefixed with 0x in hex.
207 Warning: Many of these options can produce a lot of
208 output and make your system unusable. Be very careful.
210 acpi.debug_level= [HW,ACPI]
211 Format: <int>
212 Each bit of the <int> indicates an ACPI debug level,
213 1: enable, 0: disable. It is useful for boot time
214 debugging. After system has booted up, it can be set
215 via /sys/module/acpi/parameters/debug_level.
216 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
217 Available bits (add the numbers together) to enable different
218 debug output levels of the ACPI subsystem:
219 0x01 error 0x02 warn 0x04 init 0x08 debug object
220 0x10 info 0x20 init names 0x40 parse 0x80 load
221 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
222 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
223 0x10000 resources 0x20000 user requests 0x40000 package.
224 The number can be in decimal or prefixed with 0x in hex.
225 Warning: Many of these options can produce a lot of
226 output and make your system unusable. Be very careful.
228 acpi_pm_good [X86-32,X86-64]
229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
233 agp= [AGP]
234 { off | try_unsupported }
235 off: disable AGP support
236 try_unsupported: try to drive unsupported chipsets
237 (may crash computer or cause data corruption)
239 enable_timer_pin_1 [i386,x86-64]
240 Enable PIN 1 of APIC timer
241 Can be useful to work around chipset bugs
242 (in particular on some ATI chipsets).
243 The kernel tries to set a reasonable default.
245 disable_timer_pin_1 [i386,x86-64]
246 Disable PIN 1 of APIC timer
247 Can be useful to work around chipset bugs.
249 ad1848= [HW,OSS]
250 Format: <io>,<irq>,<dma>,<dma2>,<type>
252 advansys= [HW,SCSI]
253 See header of drivers/scsi/advansys.c.
255 advwdt= [HW,WDT] Advantech WDT
256 Format: <iostart>,<iostop>
258 aedsp16= [HW,OSS] Audio Excel DSP 16
259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
260 See also header of sound/oss/aedsp16.c.
262 aha152x= [HW,SCSI]
263 See Documentation/scsi/aha152x.txt.
265 aha1542= [HW,SCSI]
266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
268 aic7xxx= [HW,SCSI]
269 See Documentation/scsi/aic7xxx.txt.
271 aic79xx= [HW,SCSI]
272 See Documentation/scsi/aic79xx.txt.
274 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT
276 Format: <a>,<b>
277 See also Documentation/kernel/input/joystick.txt
279 analog.map= [HW,JOY] Analog joystick and gamepad support
280 Specifies type or capabilities of an analog joystick
281 connected to one of 16 gameports
282 Format: <type1>,<type2>,..<type16>
284 apc= [HW,SPARC]
285 Power management functions (SPARCstation-4/5 + deriv.)
286 Format: noidle
287 Disable APC CPU standby support. SPARCstation-Fox does
288 not play well with APC CPU idle - disable it if you have
289 APC and your system crashes randomly.
291 apic= [APIC,i386] Advanced Programmable Interrupt Controller
292 Change the output verbosity whilst booting
293 Format: { quiet (default) | verbose | debug }
294 Change the amount of debugging information output
295 when initialising the APIC and IO-APIC components.
297 apm= [APM] Advanced Power Management
298 See header of arch/x86/kernel/apm_32.c.
300 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
301 Format: <io>,<irq>,<nodeID>
303 ataflop= [HW,M68k]
305 atarimouse= [HW,MOUSE] Atari Mouse
307 atascsi= [HW,SCSI] Atari SCSI
309 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
310 EzKey and similar keyboards
312 atkbd.reset= [HW] Reset keyboard during initialization
314 atkbd.set= [HW] Select keyboard code set
315 Format: <int> (2 = AT (default), 3 = PS/2)
317 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
318 keyboards
320 atkbd.softraw= [HW] Choose between synthetic and real raw mode
321 Format: <bool> (0 = real, 1 = synthetic (default))
323 atkbd.softrepeat= [HW]
324 Use software keyboard repeat
326 autotest [IA64]
328 baycom_epp= [HW,AX25]
329 Format: <io>,<mode>
331 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
332 Format: <io>,<mode>
333 See header of drivers/net/hamradio/baycom_par.c.
335 baycom_ser_fdx= [HW,AX25]
336 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
337 Format: <io>,<irq>,<mode>[,<baud>]
338 See header of drivers/net/hamradio/baycom_ser_fdx.c.
340 baycom_ser_hdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
342 Format: <io>,<irq>,<mode>
343 See header of drivers/net/hamradio/baycom_ser_hdx.c.
345 boot_delay= Milliseconds to delay each printk during boot.
346 Values larger than 10 seconds (10000) are changed to
347 no delay (0).
348 Format: integer
350 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
351 bttv.radio= Most important insmod options are available as
352 kernel args too.
353 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
354 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
356 BusLogic= [HW,SCSI]
357 See drivers/scsi/BusLogic.c, comment before function
358 BusLogic_ParseDriverOptions().
360 c101= [NET] Moxa C101 synchronous serial card
362 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
363 Sometimes CPU hardware bugs make them report the cache
364 size incorrectly. The kernel will attempt work arounds
365 to fix known problems, but for some CPUs it is not
366 possible to determine what the correct size should be.
367 This option provides an override for these situations.
369 security= [SECURITY] Choose a security module to enable at boot.
370 If this boot parameter is not specified, only the first
371 security module asking for security registration will be
372 loaded. An invalid security module name will be treated
373 as if no module has been chosen.
375 capability.disable=
376 [SECURITY] Disable capabilities. This would normally
377 be used only if an alternative security model is to be
378 configured. Potentially dangerous and should only be
379 used if you are entirely sure of the consequences.
381 ccw_timeout_log [S390]
382 See Documentation/s390/CommonIO for details.
384 cgroup_disable= [KNL] Disable a particular controller
385 Format: {name of the controller(s) to disable}
386 {Currently supported controllers - "memory"}
388 checkreqprot [SELINUX] Set initial checkreqprot flag value.
389 Format: { "0" | "1" }
390 See security/selinux/Kconfig help text.
391 0 -- check protection applied by kernel (includes
392 any implied execute protection).
393 1 -- check protection requested by application.
394 Default value is set via a kernel config option.
395 Value can be changed at runtime via
396 /selinux/checkreqprot.
398 cio_ignore= [S390]
399 See Documentation/s390/CommonIO for details.
401 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
402 [Deprecated]
403 Forces specified clocksource (if available) to be used
404 when calculating gettimeofday(). If specified
405 clocksource is not available, it defaults to PIT.
406 Format: { pit | tsc | cyclone | pmtmr }
408 clocksource= [GENERIC_TIME] Override the default clocksource
409 Format: <string>
410 Override the default clocksource and use the clocksource
411 with the name specified.
412 Some clocksource names to choose from, depending on
413 the platform:
414 [all] jiffies (this is the base, fallback clocksource)
415 [ACPI] acpi_pm
416 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
417 pxa_timer,timer3,32k_counter,timer0_1
418 [AVR32] avr32
419 [X86-32] pit,hpet,tsc,vmi-timer;
420 scx200_hrt on Geode; cyclone on IBM x440
421 [MIPS] MIPS
422 [PARISC] cr16
423 [S390] tod
424 [SH] SuperH
425 [SPARC64] tick
426 [X86-64] hpet,tsc
428 clearcpuid=BITNUM [X86]
429 Disable CPUID feature X for the kernel. See
430 include/asm-x86/cpufeature.h for the valid bit numbers.
431 Note the Linux specific bits are not necessarily
432 stable over kernel options, but the vendor specific
433 ones should be.
434 Also note that user programs calling CPUID directly
435 or using the feature without checking anything
436 will still see it. This just prevents it from
437 being used by the kernel or shown in /proc/cpuinfo.
438 Also note the kernel might malfunction if you disable
439 some critical bits.
441 code_bytes [IA32/X86_64] How many bytes of object code to print
442 in an oops report.
443 Range: 0 - 8192
444 Default: 64
446 disable_8254_timer
447 enable_8254_timer
448 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
449 over the 8254 in addition to over the IO-APIC. The
450 kernel tries to set a sensible default.
452 hpet= [X86-32,HPET] option to control HPET usage
453 Format: { enable (default) | disable | force }
454 disable: disable HPET and use PIT instead
455 force: allow force enabled of undocumented chips (ICH4,
456 VIA, nVidia)
458 com20020= [HW,NET] ARCnet - COM20020 chipset
459 Format:
460 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
462 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
463 Format: <io>[,<irq>]
465 com90xx= [HW,NET]
466 ARCnet - COM90xx chipset (memory-mapped buffers)
467 Format: <io>[,<irq>[,<memstart>]]
469 condev= [HW,S390] console device
470 conmode=
472 console= [KNL] Output console device and options.
474 tty<n> Use the virtual console device <n>.
476 ttyS<n>[,options]
477 ttyUSB0[,options]
478 Use the specified serial port. The options are of
479 the form "bbbbpnf", where "bbbb" is the baud rate,
480 "p" is parity ("n", "o", or "e"), "n" is number of
481 bits, and "f" is flow control ("r" for RTS or
482 omit it). Default is "9600n8".
484 See Documentation/serial-console.txt for more
485 information. See
486 Documentation/networking/netconsole.txt for an
487 alternative.
489 uart[8250],io,<addr>[,options]
490 uart[8250],mmio,<addr>[,options]
491 Start an early, polled-mode console on the 8250/16550
492 UART at the specified I/O port or MMIO address,
493 switching to the matching ttyS device later. The
494 options are the same as for ttyS, above.
496 If the device connected to the port is not a TTY but a braille
497 device, prepend "brl," before the device type, for instance
498 console=brl,ttyS0
499 For now, only VisioBraille is supported.
501 earlycon= [KNL] Output early console device and options.
502 uart[8250],io,<addr>[,options]
503 uart[8250],mmio,<addr>[,options]
504 Start an early, polled-mode console on the 8250/16550
505 UART at the specified I/O port or MMIO address.
506 The options are the same as for ttyS, above.
508 no_console_suspend
509 [HW] Never suspend the console
510 Disable suspending of consoles during suspend and
511 hibernate operations. Once disabled, debugging
512 messages can reach various consoles while the rest
513 of the system is being put to sleep (ie, while
514 debugging driver suspend/resume hooks). This may
515 not work reliably with all consoles, but is known
516 to work with serial and VGA consoles.
518 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
519 Format:
520 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
522 crashkernel=nn[KMG]@ss[KMG]
523 [KNL] Reserve a chunk of physical memory to
524 hold a kernel to switch to with kexec on panic.
526 crashkernel=range1:size1[,range2:size2,...][@offset]
527 [KNL] Same as above, but depends on the memory
528 in the running system. The syntax of range is
529 start-[end] where start and end are both
530 a memory unit (amount[KMG]). See also
531 Documentation/kdump/kdump.txt for a example.
533 cs4232= [HW,OSS]
534 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
536 cs89x0_dma= [HW,NET]
537 Format: <dma>
539 cs89x0_media= [HW,NET]
540 Format: { rj45 | aui | bnc }
542 dasd= [HW,NET]
543 See header of drivers/s390/block/dasd_devmap.c.
545 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
546 (one device per port)
547 Format: <port#>,<type>
548 See also Documentation/input/joystick-parport.txt
550 debug [KNL] Enable kernel debugging (events log level).
552 debug_locks_verbose=
553 [KNL] verbose self-tests
554 Format=<0|1>
555 Print debugging info while doing the locking API
556 self-tests.
557 We default to 0 (no extra messages), setting it to
558 1 will print _a lot_ more information - normally
559 only useful to kernel developers.
561 debug_objects [KNL] Enable object debugging
563 decnet.addr= [HW,NET]
564 Format: <area>[,<node>]
565 See also Documentation/networking/decnet.txt.
567 vt.default_blu= [VT]
568 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
569 Change the default blue palette of the console.
570 This is a 16-member array composed of values
571 ranging from 0-255.
573 vt.default_grn= [VT]
574 Format: <green0>,<green1>,<green2>,...,<green15>
575 Change the default green palette of the console.
576 This is a 16-member array composed of values
577 ranging from 0-255.
579 vt.default_red= [VT]
580 Format: <red0>,<red1>,<red2>,...,<red15>
581 Change the default red palette of the console.
582 This is a 16-member array composed of values
583 ranging from 0-255.
585 vt.default_utf8=
586 [VT]
587 Format=<0|1>
588 Set system-wide default UTF-8 mode for all tty's.
589 Default is 1, i.e. UTF-8 mode is enabled for all
590 newly opened terminals.
592 dhash_entries= [KNL]
593 Set number of hash buckets for dentry cache.
595 digi= [HW,SERIAL]
596 IO parameters + enable/disable command.
598 digiepca= [HW,SERIAL]
599 See drivers/char/README.epca and
600 Documentation/digiepca.txt.
602 disable_mtrr_cleanup [X86]
603 enable_mtrr_cleanup [X86]
604 The kernel tries to adjust MTRR layout from continuous
605 to discrete, to make X server driver able to add WB
606 entry later. This parameter enables/disables that.
608 mtrr_chunk_size=nn[KMG] [X86]
609 used for mtrr cleanup. It is largest continous chunk
610 that could hold holes aka. UC entries.
612 mtrr_gran_size=nn[KMG] [X86]
613 Used for mtrr cleanup. It is granularity of mtrr block.
614 Default is 1.
615 Large value could prevent small alignment from
616 using up MTRRs.
618 mtrr_spare_reg_nr=n [X86]
619 Format: <integer>
620 Range: 0,7 : spare reg number
621 Default : 1
622 Used for mtrr cleanup. It is spare mtrr entries number.
623 Set to 2 or more if your graphical card needs more.
625 disable_mtrr_trim [X86, Intel and AMD only]
626 By default the kernel will trim any uncacheable
627 memory out of your available memory pool based on
628 MTRR settings. This parameter disables that behavior,
629 possibly causing your machine to run very slowly.
631 dmasound= [HW,OSS] Sound subsystem buffers
633 dscc4.setup= [NET]
635 dtc3181e= [HW,SCSI]
637 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
638 earlyprintk=vga
639 earlyprintk=serial[,ttySn[,baudrate]]
641 Append ",keep" to not disable it when the real console
642 takes over.
644 Only vga or serial at a time, not both.
646 Currently only ttyS0 and ttyS1 are supported.
648 Interaction with the standard serial driver is not
649 very good.
651 The VGA output is eventually overwritten by the real
652 console.
654 eata= [HW,SCSI]
656 edd= [EDD]
657 Format: {"off" | "on" | "skip[mbr]"}
659 eisa_irq_edge= [PARISC,HW]
660 See header of drivers/parisc/eisa.c.
662 elanfreq= [X86-32]
663 See comment before function elanfreq_setup() in
664 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
666 elevator= [IOSCHED]
667 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
668 See Documentation/block/as-iosched.txt and
669 Documentation/block/deadline-iosched.txt for details.
671 elfcorehdr= [X86-32, X86_64]
672 Specifies physical address of start of kernel core
673 image elf header. Generally kexec loader will
674 pass this option to capture kernel.
675 See Documentation/kdump/kdump.txt for details.
677 enforcing [SELINUX] Set initial enforcing status.
678 Format: {"0" | "1"}
679 See security/selinux/Kconfig help text.
680 0 -- permissive (log only, no denials).
681 1 -- enforcing (deny and log).
682 Default value is 0.
683 Value can be changed at runtime via /selinux/enforce.
685 es1371= [HW,OSS]
686 Format: <spdif>,[<nomix>,[<amplifier>]]
687 See also header of sound/oss/es1371.c.
689 ether= [HW,NET] Ethernet cards parameters
690 This option is obsoleted by the "netdev=" option, which
691 has equivalent usage. See its documentation for details.
693 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
694 Format: <io>[,<irq>]
696 failslab=
697 fail_page_alloc=
698 fail_make_request=[KNL]
699 General fault injection mechanism.
700 Format: <interval>,<probability>,<space>,<times>
701 See also /Documentation/fault-injection/.
703 fd_mcs= [HW,SCSI]
704 See header of drivers/scsi/fd_mcs.c.
706 fdomain= [HW,SCSI]
707 See header of drivers/scsi/fdomain.c.
709 floppy= [HW]
710 See Documentation/floppy.txt.
712 force_pal_cache_flush
713 [IA-64] Avoid check_sal_cache_flush which may hang on
714 buggy SAL_CACHE_FLUSH implementations. Using this
715 parameter will force ia64_sal_cache_flush to call
716 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
718 gamecon.map[2|3]=
719 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
720 support via parallel port (up to 5 devices per port)
721 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
722 See also Documentation/input/joystick-parport.txt
724 gamma= [HW,DRM]
726 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
727 Format: off | on
728 default: on
730 gdth= [HW,SCSI]
731 See header of drivers/scsi/gdth.c.
733 gpt [EFI] Forces disk with valid GPT signature but
734 invalid Protective MBR to be treated as GPT.
736 gvp11= [HW,SCSI]
738 hashdist= [KNL,NUMA] Large hashes allocated during boot
739 are distributed across NUMA nodes. Defaults on
740 for IA-64, off otherwise.
741 Format: 0 | 1 (for off | on)
743 hcl= [IA-64] SGI's Hardware Graph compatibility layer
745 hd= [EIDE] (E)IDE hard drive subsystem geometry
746 Format: <cyl>,<head>,<sect>
748 hd?= [HW] (E)IDE subsystem
749 hd?lun= See Documentation/ide/ide.txt.
751 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
752 size of <nn>. This works even on boxes that have no
753 highmem otherwise. This also works to reduce highmem
754 size on bigger boxes.
756 highres= [KNL] Enable/disable high resolution timer mode.
757 Valid parameters: "on", "off"
758 Default: "on"
760 hisax= [HW,ISDN]
761 See Documentation/isdn/README.HiSax.
763 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
764 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
766 i8042.direct [HW] Put keyboard port into non-translated mode
767 i8042.dumbkbd [HW] Pretend that controller can only read data from
768 keyboard and cannot control its state
769 (Don't attempt to blink the leds)
770 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
771 i8042.nokbd [HW] Don't check/create keyboard port
772 i8042.noloop [HW] Disable the AUX Loopback command while probing
773 for the AUX port
774 i8042.nomux [HW] Don't check presence of an active multiplexing
775 controller
776 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
777 controllers
778 i8042.panicblink=
779 [HW] Frequency with which keyboard LEDs should blink
780 when kernel panics (default is 0.5 sec)
781 i8042.reset [HW] Reset the controller during init and cleanup
782 i8042.unlock [HW] Unlock (ignore) the keylock
784 i810= [HW,DRM]
786 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
787 indicates that the driver is running on unsupported
788 hardware.
789 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
790 does not match list of supported models.
791 i8k.power_status
792 [HW] Report power status in /proc/i8k
793 (disabled by default)
794 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
795 capability is set.
797 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
798 See Documentation/mca.txt.
800 icn= [HW,ISDN]
801 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
803 ide= [HW] (E)IDE subsystem
804 Format: ide=nodma or ide=doubler
805 See Documentation/ide/ide.txt.
807 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
808 See Documentation/ide/ide.txt.
810 idle= [X86]
811 Format: idle=poll or idle=mwait
812 Poll forces a polling idle loop that can slightly improves the performance
813 of waking up a idle CPU, but will use a lot of power and make the system
814 run hot. Not recommended.
815 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
816 to not use it because it doesn't save as much power as a normal idle
817 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
818 as idle=poll.
820 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
821 Claim all unknown PCI IDE storage controllers.
823 ignore_loglevel [KNL]
824 Ignore loglevel setting - this will print /all/
825 kernel messages to the console. Useful for debugging.
827 ihash_entries= [KNL]
828 Set number of hash buckets for inode cache.
830 in2000= [HW,SCSI]
831 See header of drivers/scsi/in2000.c.
833 init= [KNL]
834 Format: <full_path>
835 Run specified binary instead of /sbin/init as init
836 process.
838 initcall_debug [KNL] Trace initcalls as they are executed. Useful
839 for working out where the kernel is dying during
840 startup.
842 initrd= [BOOT] Specify the location of the initial ramdisk
844 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
845 Format: <irq>
847 inttest= [IA64]
849 iommu= [x86]
850 off
851 force
852 noforce
853 biomerge
854 panic
855 nopanic
856 merge
857 nomerge
858 forcesac
859 soft
862 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
863 off
864 Disable intel iommu driver.
865 igfx_off [Default Off]
866 By default, gfx is mapped as normal device. If a gfx
867 device has a dedicated DMAR unit, the DMAR unit is
868 bypassed by not enabling DMAR with this option. In
869 this case, gfx device will use physical address for
870 DMA.
871 forcedac [x86_64]
872 With this option iommu will not optimize to look
873 for io virtual address below 32 bit forcing dual
874 address cycle on pci bus for cards supporting greater
875 than 32 bit addressing. The default is to look
876 for translation below 32 bit and if not available
877 then look in the higher range.
878 strict [Default Off]
879 With this option on every unmap_single operation will
880 result in a hardware IOTLB flush operation as opposed
881 to batching them for performance.
883 io_delay= [X86-32,X86-64] I/O delay method
884 0x80
885 Standard port 0x80 based delay
886 0xed
887 Alternate port 0xed based delay (needed on some systems)
888 udelay
889 Simple two microseconds delay
890 none
891 No delay
893 io7= [HW] IO7 for Marvel based alpha systems
894 See comment before marvel_specify_io7 in
895 arch/alpha/kernel/core_marvel.c.
897 ip= [IP_PNP]
898 See Documentation/filesystems/nfsroot.txt.
900 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
901 See comment before ip2_setup() in
902 drivers/char/ip2/ip2base.c.
904 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
905 See header of drivers/scsi/ips.c.
907 ports= [IP_VS_FTP] IPVS ftp helper module
908 Default is 21.
909 Up to 8 (IP_VS_APP_MAX_PORTS) ports
910 may be specified.
911 Format: <port>,<port>....
913 irqfixup [HW]
914 When an interrupt is not handled search all handlers
915 for it. Intended to get systems with badly broken
916 firmware running.
918 irqpoll [HW]
919 When an interrupt is not handled search all handlers
920 for it. Also check all handlers each timer
921 interrupt. Intended to get systems with badly broken
922 firmware running.
924 isapnp= [ISAPNP]
925 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
927 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
928 Format:
929 <cpu number>,...,<cpu number>
930 or
931 <cpu number>-<cpu number> (must be a positive range in ascending order)
932 or a mixture
933 <cpu number>,...,<cpu number>-<cpu number>
934 This option can be used to specify one or more CPUs
935 to isolate from the general SMP balancing and scheduling
936 algorithms. The only way to move a process onto or off
937 an "isolated" CPU is via the CPU affinity syscalls.
938 <cpu number> begins at 0 and the maximum value is
939 "number of CPUs in system - 1".
941 This option is the preferred way to isolate CPUs. The
942 alternative -- manually setting the CPU mask of all
943 tasks in the system -- can cause problems and
944 suboptimal load balancer performance.
946 iucv= [HW,NET]
948 js= [HW,JOY] Analog joystick
949 See Documentation/input/joystick.txt.
951 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
952 specifies the amount of memory usable by the kernel
953 for non-movable allocations. The requested amount is
954 spread evenly throughout all nodes in the system. The
955 remaining memory in each node is used for Movable
956 pages. In the event, a node is too small to have both
957 kernelcore and Movable pages, kernelcore pages will
958 take priority and other nodes will have a larger number
959 of kernelcore pages. The Movable zone is used for the
960 allocation of pages that may be reclaimed or moved
961 by the page migration subsystem. This means that
962 HugeTLB pages may not be allocated from this zone.
963 Note that allocations like PTEs-from-HighMem still
964 use the HighMem zone if it exists, and the Normal
965 zone if it does not.
967 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
968 is similar to kernelcore except it specifies the
969 amount of memory used for migratable allocations.
970 If both kernelcore and movablecore is specified,
971 then kernelcore will be at *least* the specified
972 value but may be more. If movablecore on its own
973 is specified, the administrator must be careful
974 that the amount of memory usable for all allocations
975 is not too small.
977 keepinitrd [HW,ARM]
979 kstack=N [X86-32,X86-64] Print N words from the kernel stack
980 in oops dumps.
982 kgdboc= [HW] kgdb over consoles.
983 Requires a tty driver that supports console polling.
984 (only serial suported for now)
985 Format: <serial_device>[,baud]
987 l2cr= [PPC]
989 l3cr= [PPC]
991 lapic [X86-32,APIC] Enable the local APIC even if BIOS
992 disabled it.
994 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
995 C2 power state.
997 libata.dma= [LIBATA] DMA control
998 libata.dma=0 Disable all PATA and SATA DMA
999 libata.dma=1 PATA and SATA Disk DMA only
1000 libata.dma=2 ATAPI (CDROM) DMA only
1001 libata.dma=4 Compact Flash DMA only
1002 Combinations also work, so libata.dma=3 enables DMA
1003 for disks and CDROMs, but not CFs.
1005 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1006 when set.
1007 Format: <int>
1009 libata.force= [LIBATA] Force configurations. The format is comma
1010 separated list of "[ID:]VAL" where ID is
1011 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1012 matching port, link or device. Basically, it matches
1013 the ATA ID string printed on console by libata. If
1014 the whole ID part is omitted, the last PORT and DEVICE
1015 values are used. If ID hasn't been specified yet, the
1016 configuration applies to all ports, links and devices.
1018 If only DEVICE is omitted, the parameter applies to
1019 the port and all links and devices behind it. DEVICE
1020 number of 0 either selects the first device or the
1021 first fan-out link behind PMP device. It does not
1022 select the host link. DEVICE number of 15 selects the
1023 host link and device attached to it.
1025 The VAL specifies the configuration to force. As long
1026 as there's no ambiguity shortcut notation is allowed.
1027 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1028 The following configurations can be forced.
1030 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1031 Any ID with matching PORT is used.
1033 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1035 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1036 udma[/][16,25,33,44,66,100,133] notation is also
1037 allowed.
1039 * [no]ncq: Turn on or off NCQ.
1041 If there are multiple matching configurations changing
1042 the same attribute, the last one is used.
1044 load_ramdisk= [RAM] List of ramdisks to load from floppy
1045 See Documentation/ramdisk.txt.
1047 lockd.nlm_grace_period=P [NFS] Assign grace period.
1048 Format: <integer>
1050 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1051 Format: <integer>
1053 lockd.nlm_timeout=T [NFS] Assign timeout value.
1054 Format: <integer>
1056 lockd.nlm_udpport=M [NFS] Assign UDP port.
1057 Format: <integer>
1059 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1060 Format: <irq>
1062 loglevel= All Kernel Messages with a loglevel smaller than the
1063 console loglevel will be printed to the console. It can
1064 also be changed with klogd or other programs. The
1065 loglevels are defined as follows:
1067 0 (KERN_EMERG) system is unusable
1068 1 (KERN_ALERT) action must be taken immediately
1069 2 (KERN_CRIT) critical conditions
1070 3 (KERN_ERR) error conditions
1071 4 (KERN_WARNING) warning conditions
1072 5 (KERN_NOTICE) normal but significant condition
1073 6 (KERN_INFO) informational
1074 7 (KERN_DEBUG) debug-level messages
1076 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1077 Format: { n | nk | nM }
1078 n must be a power of two. The default size
1079 is set in the kernel config file.
1081 logo.nologo [FB] Disables display of the built-in Linux logo.
1082 This may be used to provide more screen space for
1083 kernel log messages and is useful when debugging
1084 kernel boot problems.
1086 lp=0 [LP] Specify parallel ports to use, e.g,
1087 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1088 lp=reset first parallel port). 'lp=0' disables the
1089 lp=auto printer driver. 'lp=reset' (which can be
1090 specified in addition to the ports) causes
1091 attached printers to be reset. Using
1092 lp=port1,port2,... specifies the parallel ports
1093 to associate lp devices with, starting with
1094 lp0. A port specification may be 'none' to skip
1095 that lp device, or a parport name such as
1096 'parport0'. Specifying 'lp=auto' instead of a
1097 port specification list means that device IDs
1098 from each port should be examined, to see if
1099 an IEEE 1284-compliant printer is attached; if
1100 so, the driver will manage that printer.
1101 See also header of drivers/char/lp.c.
1103 lpj=n [KNL]
1104 Sets loops_per_jiffy to given constant, thus avoiding
1105 time-consuming boot-time autodetection (up to 250 ms per
1106 CPU). 0 enables autodetection (default). To determine
1107 the correct value for your kernel, boot with normal
1108 autodetection and see what value is printed. Note that
1109 on SMP systems the preset will be applied to all CPUs,
1110 which is likely to cause problems if your CPUs need
1111 significantly divergent settings. An incorrect value
1112 will cause delays in the kernel to be wrong, leading to
1113 unpredictable I/O errors and other breakage. Although
1114 unlikely, in the extreme case this might damage your
1115 hardware.
1117 ltpc= [NET]
1118 Format: <io>,<irq>,<dma>
1120 mac5380= [HW,SCSI] Format:
1121 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1123 machvec= [IA64] Force the use of a particular machine-vector
1124 (machvec) in a generic kernel.
1125 Example: machvec=hpzx1_swiotlb
1127 max_loop= [LOOP] Maximum number of loopback devices that can
1128 be mounted
1129 Format: <1-256>
1131 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1132 should make use of. maxcpus=n : n >= 0 limits the
1133 kernel to using 'n' processors. n=0 is a special case,
1134 it is equivalent to "nosmp", which also disables
1135 the IO APIC.
1137 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1138 equal to this physical address is ignored.
1140 max_luns= [SCSI] Maximum number of LUNs to probe.
1141 Should be between 1 and 2^32-1.
1143 max_report_luns=
1144 [SCSI] Maximum number of LUNs received.
1145 Should be between 1 and 16384.
1147 mcatest= [IA-64]
1149 mce [X86-32] Machine Check Exception
1151 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1153 md= [HW] RAID subsystems devices and level
1154 See Documentation/md.txt.
1156 mdacon= [MDA]
1157 Format: <first>,<last>
1158 Specifies range of consoles to be captured by the MDA.
1160 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1161 Amount of memory to be used when the kernel is not able
1162 to see the whole system memory or for test.
1163 [X86-32] Use together with memmap= to avoid physical
1164 address space collisions. Without memmap= PCI devices
1165 could be placed at addresses belonging to unused RAM.
1167 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1168 memory.
1170 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1171 E820 memory map, as specified by the user.
1172 Such memmap=exactmap lines can be constructed based on
1173 BIOS output or other requirements. See the memmap=nn@ss
1174 option description.
1176 memmap=nn[KMG]@ss[KMG]
1177 [KNL] Force usage of a specific region of memory
1178 Region of memory to be used, from ss to ss+nn.
1180 memmap=nn[KMG]#ss[KMG]
1181 [KNL,ACPI] Mark specific memory as ACPI data.
1182 Region of memory to be used, from ss to ss+nn.
1184 memmap=nn[KMG]$ss[KMG]
1185 [KNL,ACPI] Mark specific memory as reserved.
1186 Region of memory to be used, from ss to ss+nn.
1187 Example: Exclude memory from 0x18690000-0x1869ffff
1188 memmap=64K$0x18690000
1189 or
1190 memmap=0x10000$0x18690000
1192 memtest= [KNL,X86_64] Enable memtest
1193 Format: <integer>
1194 range: 0,4 : pattern number
1195 default : 0 <disable>
1197 meye.*= [HW] Set MotionEye Camera parameters
1198 See Documentation/video4linux/meye.txt.
1200 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1201 Multi-Function General Purpose Timers on AMD Geode
1202 platforms.
1204 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1205 the BIOS has incorrectly applied a workaround. TinyBIOS
1206 version 0.98 is known to be affected, 0.99 fixes the
1207 problem by letting the user disable the workaround.
1209 mga= [HW,DRM]
1211 mousedev.tap_time=
1212 [MOUSE] Maximum time between finger touching and
1213 leaving touchpad surface for touch to be considered
1214 a tap and be reported as a left button click (for
1215 touchpads working in absolute mode only).
1216 Format: <msecs>
1217 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1218 reporting absolute coordinates, such as tablets
1219 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1220 reporting absolute coordinates, such as tablets
1222 mpu401= [HW,OSS]
1223 Format: <io>,<irq>
1225 MTD_Partition= [MTD]
1226 Format: <name>,<region-number>,<size>,<offset>
1228 MTD_Region= [MTD] Format:
1229 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1231 mtdparts= [MTD]
1232 See drivers/mtd/cmdlinepart.c.
1234 mtouchusb.raw_coordinates=
1235 [HW] Make the MicroTouch USB driver use raw coordinates
1236 ('y', default) or cooked coordinates ('n')
1238 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1240 NCR_D700= [HW,SCSI]
1241 See header of drivers/scsi/NCR_D700.c.
1243 ncr5380= [HW,SCSI]
1245 ncr53c400= [HW,SCSI]
1247 ncr53c400a= [HW,SCSI]
1249 ncr53c406a= [HW,SCSI]
1251 ncr53c8xx= [HW,SCSI]
1253 netdev= [NET] Network devices parameters
1254 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1255 Note that mem_start is often overloaded to mean
1256 something different and driver-specific.
1257 This usage is only documented in each driver source
1258 file if at all.
1260 nfsaddrs= [NFS]
1261 See Documentation/filesystems/nfsroot.txt.
1263 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1264 See Documentation/filesystems/nfsroot.txt.
1266 nfs.callback_tcpport=
1267 [NFS] set the TCP port on which the NFSv4 callback
1268 channel should listen.
1270 nfs.idmap_cache_timeout=
1271 [NFS] set the maximum lifetime for idmapper cache
1272 entries.
1274 nfs.enable_ino64=
1275 [NFS] enable 64-bit inode numbers.
1276 If zero, the NFS client will fake up a 32-bit inode
1277 number for the readdir() and stat() syscalls instead
1278 of returning the full 64-bit number.
1279 The default is to return 64-bit inode numbers.
1281 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1282 when a NMI is triggered.
1283 Format: [state][,regs][,debounce][,die]
1285 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1287 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1288 emulation library even if a 387 maths coprocessor
1289 is present.
1291 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1292 caches in the slab allocator. Saves per-node memory,
1293 but will impact performance.
1295 noalign [KNL,ARM]
1297 noapic [SMP,APIC] Tells the kernel to not make use of any
1298 IOAPICs that may be present in the system.
1300 nobats [PPC] Do not use BATs for mapping kernel lowmem
1301 on "Classic" PPC cores.
1303 nocache [ARM]
1305 nodelayacct [KNL] Disable per-task delay accounting
1307 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1309 noefi [X86-32,X86-64] Disable EFI runtime services support.
1311 noexec [IA-64]
1313 noexec [X86-32,X86-64]
1314 On X86-32 available only on PAE configured kernels.
1315 noexec=on: enable non-executable mappings (default)
1316 noexec=off: disable non-executable mappings
1318 noexec32 [X86-64]
1319 This affects only 32-bit executables.
1320 noexec32=on: enable non-executable mappings (default)
1321 read doesn't imply executable mappings
1322 noexec32=off: disable non-executable mappings
1323 read implies executable mappings
1325 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1326 register save and restore. The kernel will only save
1327 legacy floating-point registers on task switch.
1329 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1331 nohlt [BUGS=ARM]
1333 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1334 instruction doesn't work correctly and not to
1335 use it.
1337 nohalt [IA-64] Tells the kernel not to use the power saving
1338 function PAL_HALT_LIGHT when idle. This increases
1339 power-consumption. On the positive side, it reduces
1340 interrupt wake-up latency, which may improve performance
1341 in certain environments such as networked servers or
1342 real-time systems.
1344 nohz= [KNL] Boottime enable/disable dynamic ticks
1345 Valid arguments: on, off
1346 Default: on
1348 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1350 noirqdebug [X86-32] Disables the code which attempts to detect and
1351 disable unhandled interrupt sources.
1353 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1354 broken timer IRQ sources.
1356 noisapnp [ISAPNP] Disables ISA PnP code.
1358 noinitrd [RAM] Tells the kernel not to load any configured
1359 initial RAM disk.
1361 nointroute [IA-64]
1363 nojitter [IA64] Disables jitter checking for ITC timers.
1365 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1367 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1369 noltlbs [PPC] Do not use large page/tlb entries for kernel
1370 lowmem mapping on PPC40x.
1372 nomca [IA-64] Disable machine check abort handling
1374 nomce [X86-32] Machine Check Exception
1376 nomfgpt [X86-32] Disable Multi-Function General Purpose
1377 Timer usage (for AMD Geode machines).
1379 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1381 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1382 with UP alternatives
1384 noresidual [PPC] Don't use residual data on PReP machines.
1386 noresume [SWSUSP] Disables resume and restores original swap
1387 space.
1389 no-scroll [VGA] Disables scrollback.
1390 This is required for the Braillex ib80-piezo Braille
1391 reader made by F.H. Papenmeier (Germany).
1393 nosbagart [IA-64]
1395 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1397 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1398 and disable the IO APIC. legacy for "maxcpus=0".
1400 nosoftlockup [KNL] Disable the soft-lockup detector.
1402 nosync [HW,M68K] Disables sync negotiation for all devices.
1404 notsc [BUGS=X86-32] Disable Time Stamp Counter
1406 nousb [USB] Disable the USB subsystem
1408 nowb [ARM]
1410 nptcg= [IA64] Override max number of concurrent global TLB
1411 purges which is reported from either PAL_VM_SUMMARY or
1412 SAL PALO.
1414 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1415 one of ['zone', 'node', 'default'] can be specified
1416 This can be set from sysctl after boot.
1417 See Documentation/sysctl/vm.txt for details.
1419 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1421 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1422 Rather than timing out after 20 ms if an EC
1423 command is not properly ACKed, override the length
1424 of the timeout. We have interrupts disabled while
1425 waiting for the ACK, so if this is set too high
1426 interrupts *may* be lost!
1428 opl3= [HW,OSS]
1429 Format: <io>
1431 oprofile.timer= [HW]
1432 Use timer interrupt instead of performance counters
1434 osst= [HW,SCSI] SCSI Tape Driver
1435 Format: <buffer_size>,<write_threshold>
1436 See also Documentation/scsi/st.txt.
1438 panic= [KNL] Kernel behaviour on panic
1439 Format: <timeout>
1441 parkbd.port= [HW] Parallel port number the keyboard adapter is
1442 connected to, default is 0.
1443 Format: <parport#>
1444 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1445 0 for XT, 1 for AT (default is AT).
1446 Format: <mode>
1448 parport= [HW,PPT] Specify parallel ports. 0 disables.
1449 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1450 Use 'auto' to force the driver to use any
1451 IRQ/DMA settings detected (the default is to
1452 ignore detected IRQ/DMA settings because of
1453 possible conflicts). You can specify the base
1454 address, IRQ, and DMA settings; IRQ and DMA
1455 should be numbers, or 'auto' (for using detected
1456 settings on that particular port), or 'nofifo'
1457 (to avoid using a FIFO even if it is detected).
1458 Parallel ports are assigned in the order they
1459 are specified on the command line, starting
1460 with parport0.
1462 parport_init_mode= [HW,PPT]
1463 Configure VIA parallel port to operate in
1464 a specific mode. This is necessary on Pegasos
1465 computer where firmware has no options for setting
1466 up parallel port mode and sets it to spp.
1467 Currently this function knows 686a and 8231 chips.
1468 Format: [spp|ps2|epp|ecp|ecpepp]
1470 pas2= [HW,OSS] Format:
1471 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1473 pas16= [HW,SCSI]
1474 See header of drivers/scsi/pas16.c.
1476 pause_on_oops=
1477 Halt all CPUs after the first oops has been printed for
1478 the specified number of seconds. This is to be used if
1479 your oopses keep scrolling off the screen.
1481 pcbit= [HW,ISDN]
1483 pcd. [PARIDE]
1484 See header of drivers/block/paride/pcd.c.
1485 See also Documentation/paride.txt.
1487 pci=option[,option...] [PCI] various PCI subsystem options:
1488 off [X86-32] don't probe for the PCI bus
1489 bios [X86-32] force use of PCI BIOS, don't access
1490 the hardware directly. Use this if your machine
1491 has a non-standard PCI host bridge.
1492 nobios [X86-32] disallow use of PCI BIOS, only direct
1493 hardware access methods are allowed. Use this
1494 if you experience crashes upon bootup and you
1495 suspect they are caused by the BIOS.
1496 conf1 [X86-32] Force use of PCI Configuration
1497 Mechanism 1.
1498 conf2 [X86-32] Force use of PCI Configuration
1499 Mechanism 2.
1500 noaer [PCIE] If the PCIEAER kernel config parameter is
1501 enabled, this kernel boot option can be used to
1502 disable the use of PCIE advanced error reporting.
1503 nodomains [PCI] Disable support for multiple PCI
1504 root domains (aka PCI segments, in ACPI-speak).
1505 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1506 Configuration
1507 nomsi [MSI] If the PCI_MSI kernel config parameter is
1508 enabled, this kernel boot option can be used to
1509 disable the use of MSI interrupts system-wide.
1510 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1511 routing table. These calls are known to be buggy
1512 on several machines and they hang the machine
1513 when used, but on other computers it's the only
1514 way to get the interrupt routing table. Try
1515 this option if the kernel is unable to allocate
1516 IRQs or discover secondary PCI buses on your
1517 motherboard.
1518 rom [X86-32] Assign address space to expansion ROMs.
1519 Use with caution as certain devices share
1520 address decoders between ROMs and other
1521 resources.
1522 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1523 assigned automatically to PCI devices. You can
1524 make the kernel exclude IRQs of your ISA cards
1525 this way.
1526 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1527 of the PIRQ table (normally generated
1528 by the BIOS) if it is outside the
1529 F0000h-100000h range.
1530 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1531 useful if the kernel is unable to find your
1532 secondary buses and you want to tell it
1533 explicitly which ones they are.
1534 assign-busses [X86-32] Always assign all PCI bus
1535 numbers ourselves, overriding
1536 whatever the firmware may have done.
1537 usepirqmask [X86-32] Honor the possible IRQ mask stored
1538 in the BIOS $PIR table. This is needed on
1539 some systems with broken BIOSes, notably
1540 some HP Pavilion N5400 and Omnibook XE3
1541 notebooks. This will have no effect if ACPI
1542 IRQ routing is enabled.
1543 noacpi [X86-32] Do not use ACPI for IRQ routing
1544 or for PCI scanning.
1545 use_crs [X86-32] Use _CRS for PCI resource
1546 allocation.
1547 routeirq Do IRQ routing for all PCI devices.
1548 This is normally done in pci_enable_device(),
1549 so this option is a temporary workaround
1550 for broken drivers that don't call it.
1551 skip_isa_align [X86] do not align io start addr, so can
1552 handle more pci cards
1553 firmware [ARM] Do not re-enumerate the bus but instead
1554 just use the configuration from the
1555 bootloader. This is currently used on
1556 IXP2000 systems where the bus has to be
1557 configured a certain way for adjunct CPUs.
1558 noearly [X86] Don't do any early type 1 scanning.
1559 This might help on some broken boards which
1560 machine check when some devices' config space
1561 is read. But various workarounds are disabled
1562 and some IOMMU drivers will not work.
1563 bfsort Sort PCI devices into breadth-first order.
1564 This sorting is done to get a device
1565 order compatible with older (<= 2.4) kernels.
1566 nobfsort Don't sort PCI devices into breadth-first order.
1567 cbiosize=nn[KMG] The fixed amount of bus space which is
1568 reserved for the CardBus bridge's IO window.
1569 The default value is 256 bytes.
1570 cbmemsize=nn[KMG] The fixed amount of bus space which is
1571 reserved for the CardBus bridge's memory
1572 window. The default value is 64 megabytes.
1574 pcmv= [HW,PCMCIA] BadgePAD 4
1576 pd. [PARIDE]
1577 See Documentation/paride.txt.
1579 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1580 boot time.
1581 Format: { 0 | 1 }
1582 See arch/parisc/kernel/pdc_chassis.c
1584 pf. [PARIDE]
1585 See Documentation/paride.txt.
1587 pg. [PARIDE]
1588 See Documentation/paride.txt.
1590 pirq= [SMP,APIC] Manual mp-table setup
1591 See Documentation/i386/IO-APIC.txt.
1593 plip= [PPT,NET] Parallel port network link
1594 Format: { parport<nr> | timid | 0 }
1595 See also Documentation/parport.txt.
1597 pnpacpi= [ACPI]
1598 { off }
1600 pnpbios= [ISAPNP]
1601 { on | off | curr | res | no-curr | no-res }
1603 pnp_reserve_irq=
1604 [ISAPNP] Exclude IRQs for the autoconfiguration
1606 pnp_reserve_dma=
1607 [ISAPNP] Exclude DMAs for the autoconfiguration
1609 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1610 Ranges are in pairs (I/O port base and size).
1612 pnp_reserve_mem=
1613 [ISAPNP] Exclude memory regions for the
1614 autoconfiguration.
1615 Ranges are in pairs (memory base and size).
1617 print-fatal-signals=
1618 [KNL] debug: print fatal signals
1619 print-fatal-signals=1: print segfault info to
1620 the kernel console.
1621 default: off.
1623 printk.time= Show timing data prefixed to each printk message line
1624 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1626 profile= [KNL] Enable kernel profiling via /proc/profile
1627 Format: [schedule,]<number>
1628 Param: "schedule" - profile schedule points.
1629 Param: <number> - step/bucket size as a power of 2 for
1630 statistical time based profiling.
1631 Param: "sleep" - profile D-state sleeping (millisecs).
1632 Requires CONFIG_SCHEDSTATS
1633 Param: "kvm" - profile VM exits.
1635 processor.max_cstate= [HW,ACPI]
1636 Limit processor to maximum C-state
1637 max_cstate=9 overrides any DMI blacklist limit.
1639 processor.nocst [HW,ACPI]
1640 Ignore the _CST method to determine C-states,
1641 instead using the legacy FADT method
1643 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1644 before loading.
1645 See Documentation/ramdisk.txt.
1647 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1648 probe for; one of (bare|imps|exps|lifebook|any).
1649 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1650 per second.
1651 psmouse.resetafter= [HW,MOUSE]
1652 Try to reset the device after so many bad packets
1653 (0 = never).
1654 psmouse.resolution=
1655 [HW,MOUSE] Set desired mouse resolution, in dpi.
1656 psmouse.smartscroll=
1657 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1658 0 = disabled, 1 = enabled (default).
1660 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1661 Format:
1662 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1664 pt. [PARIDE]
1665 See Documentation/paride.txt.
1667 pty.legacy_count=
1668 [KNL] Number of legacy pty's. Overwrites compiled-in
1669 default number.
1671 quiet [KNL] Disable most log messages
1673 r128= [HW,DRM]
1675 raid= [HW,RAID]
1676 See Documentation/md.txt.
1678 ramdisk_blocksize= [RAM]
1679 See Documentation/ramdisk.txt.
1681 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1682 See Documentation/ramdisk.txt.
1684 rcupdate.blimit= [KNL,BOOT]
1685 Set maximum number of finished RCU callbacks to process
1686 in one batch.
1688 rcupdate.qhimark= [KNL,BOOT]
1689 Set threshold of queued
1690 RCU callbacks over which batch limiting is disabled.
1692 rcupdate.qlowmark= [KNL,BOOT]
1693 Set threshold of queued RCU callbacks below which
1694 batch limiting is re-enabled.
1696 rdinit= [KNL]
1697 Format: <full_path>
1698 Run specified binary instead of /init from the ramdisk,
1699 used for early userspace startup. See initrd.
1701 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1702 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1703 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1705 relax_domain_level=
1706 [KNL, SMP] Set scheduler's default relax_domain_level.
1707 See Documentation/cpusets.txt.
1709 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1711 reservetop= [X86-32]
1712 Format: nn[KMG]
1713 Reserves a hole at the top of the kernel virtual
1714 address space.
1716 reset_devices [KNL] Force drivers to reset the underlying device
1717 during initialization.
1719 resume= [SWSUSP]
1720 Specify the partition device for software suspend
1722 resume_offset= [SWSUSP]
1723 Specify the offset from the beginning of the partition
1724 given by "resume=" at which the swap header is located,
1725 in <PAGE_SIZE> units (needed only for swap files).
1726 See Documentation/power/swsusp-and-swap-files.txt
1728 retain_initrd [RAM] Keep initrd memory after extraction
1730 rhash_entries= [KNL,NET]
1731 Set number of hash buckets for route cache
1733 riscom8= [HW,SERIAL]
1734 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1736 ro [KNL] Mount root device read-only on boot
1738 root= [KNL] Root filesystem
1740 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1741 mount the root filesystem
1743 rootflags= [KNL] Set root filesystem mount option string
1745 rootfstype= [KNL] Set root filesystem type
1747 rootwait [KNL] Wait (indefinitely) for root device to show up.
1748 Useful for devices that are detected asynchronously
1749 (e.g. USB and MMC devices).
1751 root_plug.vendor_id=
1752 [ROOTPLUG] Override the default vendor ID
1754 root_plug.product_id=
1755 [ROOTPLUG] Override the default product ID
1757 root_plug.debug=
1758 [ROOTPLUG] Enable debugging output
1760 rw [KNL] Mount root device read-write on boot
1762 S [KNL] Run init in single mode
1764 sa1100ir [NET]
1765 See drivers/net/irda/sa1100_ir.c.
1767 sbni= [NET] Granch SBNI12 leased line adapter
1769 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1770 Format: <io>[,<timeout>[,<isapnp>]]
1772 scsi_debug_*= [SCSI]
1773 See drivers/scsi/scsi_debug.c.
1775 scsi_default_dev_flags=
1776 [SCSI] SCSI default device flags
1777 Format: <integer>
1779 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1780 Format: <vendor>:<model>:<flags>
1781 (flags are integer value)
1783 scsi_logging_level= [SCSI] a bit mask of logging levels
1784 See drivers/scsi/scsi_logging.h for bits. Also
1785 settable via sysctl at dev.scsi.logging_level
1786 (/proc/sys/dev/scsi/logging_level).
1787 There is also a nice 'scsi_logging_level' script in the
1788 S390-tools package, available for download at
1789 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1791 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1792 discovered. async scans them in kernel threads,
1793 allowing boot to proceed. none ignores them, expecting
1794 user space to do the scan.
1796 selinux [SELINUX] Disable or enable SELinux at boot time.
1797 Format: { "0" | "1" }
1798 See security/selinux/Kconfig help text.
1799 0 -- disable.
1800 1 -- enable.
1801 Default value is set via kernel config option.
1802 If enabled at boot time, /selinux/disable can be used
1803 later to disable prior to initial policy load.
1805 selinux_compat_net =
1806 [SELINUX] Set initial selinux_compat_net flag value.
1807 Format: { "0" | "1" }
1808 0 -- use new secmark-based packet controls
1809 1 -- use legacy packet controls
1810 Default value is 0 (preferred).
1811 Value can be changed at runtime via
1812 /selinux/compat_net.
1814 serialnumber [BUGS=X86-32]
1816 shapers= [NET]
1817 Maximal number of shapers.
1819 sim710= [SCSI,HW]
1820 See header of drivers/scsi/sim710.c.
1822 simeth= [IA-64]
1823 simscsi=
1825 slram= [HW,MTD]
1827 slub_debug[=options[,slabs]] [MM, SLUB]
1828 Enabling slub_debug allows one to determine the
1829 culprit if slab objects become corrupted. Enabling
1830 slub_debug can create guard zones around objects and
1831 may poison objects when not in use. Also tracks the
1832 last alloc / free. For more information see
1833 Documentation/vm/slub.txt.
1835 slub_max_order= [MM, SLUB]
1836 Determines the maximum allowed order for slabs.
1837 A high setting may cause OOMs due to memory
1838 fragmentation. For more information see
1839 Documentation/vm/slub.txt.
1841 slub_min_objects= [MM, SLUB]
1842 The minimum number of objects per slab. SLUB will
1843 increase the slab order up to slub_max_order to
1844 generate a sufficiently large slab able to contain
1845 the number of objects indicated. The higher the number
1846 of objects the smaller the overhead of tracking slabs
1847 and the less frequently locks need to be acquired.
1848 For more information see Documentation/vm/slub.txt.
1850 slub_min_order= [MM, SLUB]
1851 Determines the mininum page order for slabs. Must be
1852 lower than slub_max_order.
1853 For more information see Documentation/vm/slub.txt.
1855 slub_nomerge [MM, SLUB]
1856 Disable merging of slabs with similar size. May be
1857 necessary if there is some reason to distinguish
1858 allocs to different slabs. Debug options disable
1859 merging on their own.
1860 For more information see Documentation/vm/slub.txt.
1862 smart2= [HW]
1863 Format: <io1>[,<io2>[,...,<io8>]]
1865 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1866 attempt to substitute SMP alternatives once at boot.
1868 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1869 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1870 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1871 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1872 smsc-ircc2.ircc_irq= [HW] IRQ line
1873 smsc-ircc2.ircc_dma= [HW] DMA channel
1874 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1875 0: Toshiba Satellite 1800 (GP data pin select)
1876 1: Fast pin select (default)
1877 2: ATC IRMode
1879 snd-ad1816a= [HW,ALSA]
1881 snd-ad1848= [HW,ALSA]
1883 snd-ali5451= [HW,ALSA]
1885 snd-als100= [HW,ALSA]
1887 snd-als4000= [HW,ALSA]
1889 snd-azt2320= [HW,ALSA]
1891 snd-cmi8330= [HW,ALSA]
1893 snd-cmipci= [HW,ALSA]
1895 snd-cs4231= [HW,ALSA]
1897 snd-cs4232= [HW,ALSA]
1899 snd-cs4236= [HW,ALSA]
1901 snd-cs4281= [HW,ALSA]
1903 snd-cs46xx= [HW,ALSA]
1905 snd-dt019x= [HW,ALSA]
1907 snd-dummy= [HW,ALSA]
1909 snd-emu10k1= [HW,ALSA]
1911 snd-ens1370= [HW,ALSA]
1913 snd-ens1371= [HW,ALSA]
1915 snd-es968= [HW,ALSA]
1917 snd-es1688= [HW,ALSA]
1919 snd-es18xx= [HW,ALSA]
1921 snd-es1938= [HW,ALSA]
1923 snd-es1968= [HW,ALSA]
1925 snd-fm801= [HW,ALSA]
1927 snd-gusclassic= [HW,ALSA]
1929 snd-gusextreme= [HW,ALSA]
1931 snd-gusmax= [HW,ALSA]
1933 snd-hdsp= [HW,ALSA]
1935 snd-ice1712= [HW,ALSA]
1937 snd-intel8x0= [HW,ALSA]
1939 snd-interwave= [HW,ALSA]
1941 snd-interwave-stb=
1942 [HW,ALSA]
1944 snd-korg1212= [HW,ALSA]
1946 snd-maestro3= [HW,ALSA]
1948 snd-mpu401= [HW,ALSA]
1950 snd-mtpav= [HW,ALSA]
1952 snd-nm256= [HW,ALSA]
1954 snd-opl3sa2= [HW,ALSA]
1956 snd-opti92x-ad1848=
1957 [HW,ALSA]
1959 snd-opti92x-cs4231=
1960 [HW,ALSA]
1962 snd-opti93x= [HW,ALSA]
1964 snd-pmac= [HW,ALSA]
1966 snd-rme32= [HW,ALSA]
1968 snd-rme96= [HW,ALSA]
1970 snd-rme9652= [HW,ALSA]
1972 snd-sb8= [HW,ALSA]
1974 snd-sb16= [HW,ALSA]
1976 snd-sbawe= [HW,ALSA]
1978 snd-serial= [HW,ALSA]
1980 snd-sgalaxy= [HW,ALSA]
1982 snd-sonicvibes= [HW,ALSA]
1984 snd-sun-amd7930=
1985 [HW,ALSA]
1987 snd-sun-cs4231= [HW,ALSA]
1989 snd-trident= [HW,ALSA]
1991 snd-usb-audio= [HW,ALSA,USB]
1993 snd-via82xx= [HW,ALSA]
1995 snd-virmidi= [HW,ALSA]
1997 snd-wavefront= [HW,ALSA]
1999 snd-ymfpci= [HW,ALSA]
2001 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2002 See Documentation/sonypi.txt
2004 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2005 See Documentation/specialix.txt.
2007 spia_io_base= [HW,MTD]
2008 spia_fio_base=
2009 spia_pedr=
2010 spia_peddr=
2012 sscape= [HW,OSS]
2013 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2015 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2016 See Documentation/scsi/st.txt.
2018 sti= [PARISC,HW]
2019 Format: <num>
2020 Set the STI (builtin display/keyboard on the HP-PARISC
2021 machines) console (graphic card) which should be used
2022 as the initial boot-console.
2023 See also comment in drivers/video/console/sticore.c.
2025 sti_font= [HW]
2026 See comment in drivers/video/console/sticore.c.
2028 stifb= [HW]
2029 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2031 sunrpc.pool_mode=
2032 [NFS]
2033 Control how the NFS server code allocates CPUs to
2034 service thread pools. Depending on how many NICs
2035 you have and where their interrupts are bound, this
2036 option will affect which CPUs will do NFS serving.
2037 Note: this parameter cannot be changed while the
2038 NFS server is running.
2040 auto the server chooses an appropriate mode
2041 automatically using heuristics
2042 global a single global pool contains all CPUs
2043 percpu one pool for each CPU
2044 pernode one pool for each NUMA node (equivalent
2045 to global on non-NUMA machines)
2047 swiotlb= [IA-64] Number of I/O TLB slabs
2049 switches= [HW,M68k]
2051 sym53c416= [HW,SCSI]
2052 See header of drivers/scsi/sym53c416.c.
2054 sysrq_always_enabled
2055 [KNL]
2056 Ignore sysrq setting - this boot parameter will
2057 neutralize any effect of /proc/sys/kernel/sysrq.
2058 Useful for debugging.
2060 t128= [HW,SCSI]
2061 See header of drivers/scsi/t128.c.
2063 tdfx= [HW,DRM]
2065 thash_entries= [KNL,NET]
2066 Set number of hash buckets for TCP connection
2068 thermal.act= [HW,ACPI]
2069 -1: disable all active trip points in all thermal zones
2070 <degrees C>: override all lowest active trip points
2072 thermal.crt= [HW,ACPI]
2073 -1: disable all critical trip points in all thermal zones
2074 <degrees C>: lower all critical trip points
2076 thermal.nocrt= [HW,ACPI]
2077 Set to disable actions on ACPI thermal zone
2078 critical and hot trip points.
2080 thermal.off= [HW,ACPI]
2081 1: disable ACPI thermal control
2083 thermal.psv= [HW,ACPI]
2084 -1: disable all passive trip points
2085 <degrees C>: override all passive trip points to this value
2087 thermal.tzp= [HW,ACPI]
2088 Specify global default ACPI thermal zone polling rate
2089 <deci-seconds>: poll all this frequency
2090 0: no polling (default)
2092 tipar.timeout= [HW,PPT]
2093 Set communications timeout in tenths of a second
2094 (default 15).
2096 tipar.delay= [HW,PPT]
2097 Set inter-bit delay in microseconds (default 10).
2099 tmscsim= [HW,SCSI]
2100 See comment before function dc390_setup() in
2101 drivers/scsi/tmscsim.c.
2103 tp720= [HW,PS2]
2105 trix= [HW,OSS] MediaTrix AudioTrix Pro
2106 Format:
2107 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2109 turbografx.map[2|3]= [HW,JOY]
2110 TurboGraFX parallel port interface
2111 Format:
2112 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2113 See also Documentation/input/joystick-parport.txt
2115 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2116 See header of drivers/scsi/u14-34f.c.
2118 uart401= [HW,OSS]
2119 Format: <io>,<irq>
2121 uart6850= [HW,OSS]
2122 Format: <io>,<irq>
2124 uhci-hcd.ignore_oc=
2125 [USB] Ignore overcurrent events (default N).
2126 Some badly-designed motherboards generate lots of
2127 bogus events, for ports that aren't wired to
2128 anything. Set this parameter to avoid log spamming.
2129 Note that genuine overcurrent events won't be
2130 reported either.
2132 usbcore.autosuspend=
2133 [USB] The autosuspend time delay (in seconds) used
2134 for newly-detected USB devices (default 2). This
2135 is the time required before an idle device will be
2136 autosuspended. Devices for which the delay is set
2137 to a negative value won't be autosuspended at all.
2139 usbhid.mousepoll=
2140 [USBHID] The interval which mice are to be polled at.
2142 vdso= [X86-32,SH,x86-64]
2143 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2144 vdso=1: enable VDSO (default)
2145 vdso=0: disable VDSO mapping
2147 vdso32= [X86-32,X86-64]
2148 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2149 vdso32=1: enable 32-bit VDSO (default)
2150 vdso32=0: disable 32-bit VDSO mapping
2152 vector= [IA-64,SMP]
2153 vector=percpu: enable percpu vector domain
2155 video= [FB] Frame buffer configuration
2156 See Documentation/fb/modedb.txt.
2158 vga= [BOOT,X86-32] Select a particular video mode
2159 See Documentation/i386/boot.txt and
2160 Documentation/svga.txt.
2161 Use vga=ask for menu.
2162 This is actually a boot loader parameter; the value is
2163 passed to the kernel using a special protocol.
2165 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2166 size of <nn>. This can be used to increase the
2167 minimum size (128MB on x86). It can also be used to
2168 decrease the size and leave more room for directly
2169 mapped kernel RAM.
2171 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2172 Format: <command>
2174 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2175 Format: <command>
2177 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2178 Format: <command>
2180 waveartist= [HW,OSS]
2181 Format: <io>,<irq>,<dma>,<dma2>
2183 wd33c93= [HW,SCSI]
2184 See header of drivers/scsi/wd33c93.c.
2186 wd7000= [HW,SCSI]
2187 See header of drivers/scsi/wd7000.c.
2189 wdt= [WDT] Watchdog
2190 See Documentation/watchdog/wdt.txt.
2192 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2193 xd_geo= See header of drivers/block/xd.c.
2195 xirc2ps_cs= [NET,PCMCIA]
2196 Format:
2197 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2199 norandmaps Don't use address space randomization
2200 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2202 ______________________________________________________________________
2204 TODO:
2206 Add documentation for ALSA options.
2207 Add more DRM drivers.