| blob | cf3868956f1e852850fa7ac3a680f0b4b6e25ee6 |
1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend is enabled.
91 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
99 X86-32 X86-32, aka i386 architecture is enabled.
100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
104 In addition, the following text indicates that the option:
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
110 Parameters denoted with BOOT are actually interpreted by the boot
111 loader, and have no meaning to the kernel directly.
112 Do not modify the syntax of boot loader parameters without extreme
113 need or coordination with <Documentation/i386/boot.txt>.
115 There are also arch-specific kernel-parameters not documented here.
116 See for example <Documentation/x86_64/boot-options.txt>.
118 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119 a trailing = on the name of any parameter states that that parameter will
120 be entered as an environment variable, whereas its absence indicates that
121 it will appear as a kernel argument readable via /proc/cmdline by programs
122 running once the system is up.
124 The number of kernel parameters is not limited, but the length of the
125 complete command line (parameters including spaces etc.) is limited to
126 a fixed number of characters. This limit depends on the architecture
127 and is between 256 and 4096 characters. It is defined in the file
128 ./include/asm/setup.h as COMMAND_LINE_SIZE.
131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
133 Format: { force | off | ht | strict | noirq }
134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
138 strict -- Be less tolerant of platforms that are not
139 strictly ACPI specification compliant.
141 See also Documentation/pm.txt, pci=noacpi
143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
147 default: 0
149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode }
151 See Documentation/power/video.txt
153 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
154 Format: { level | edge | high | low }
156 acpi_irq_balance [HW,ACPI]
157 ACPI will balance active IRQs
158 default in APIC mode
160 acpi_irq_nobalance [HW,ACPI]
161 ACPI will not move active IRQs (default)
162 default in PIC mode
164 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
165 use by PCI
166 Format: <irq>,<irq>...
168 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
169 Format: <irq>,<irq>...
171 acpi_new_pts_ordering [HW,ACPI]
172 Enforce the ACPI 2.0 ordering of the _PTS control
173 method wrt putting devices into low power states
174 default: pre ACPI 2.0 ordering of _PTS
176 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
178 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
179 Format: To spoof as Windows 98: ="Microsoft Windows"
181 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
182 acpi_osi="string1" # add string1 -- only one string
183 acpi_osi="!string2" # remove built-in string2
184 acpi_osi= # disable all strings
186 acpi_serialize [HW,ACPI] force serialization of AML methods
188 acpi_skip_timer_override [HW,ACPI]
189 Recognize and ignore IRQ0/pin2 Interrupt Override.
190 For broken nForce2 BIOS resulting in XT-PIC timer.
191 acpi_use_timer_override [HW,ACPI}
192 Use timer override. For some broken Nvidia NF5 boards
193 that require a timer override, but don't have
194 HPET
196 acpi.debug_layer= [HW,ACPI]
197 Format: <int>
198 Each bit of the <int> indicates an ACPI debug layer,
199 1: enable, 0: disable. It is useful for boot time
200 debugging. After system has booted up, it can be set
201 via /sys/module/acpi/parameters/debug_layer.
202 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
203 Available bits (add the numbers together) to enable debug output
204 for specific parts of the ACPI subsystem:
205 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
206 0x10 namespace 0x20 parser 0x40 dispatcher
207 0x80 executer 0x100 resources 0x200 acpica debugger
208 0x400 os services 0x800 acpica disassembler.
209 The number can be in decimal or prefixed with 0x in hex.
210 Warning: Many of these options can produce a lot of
211 output and make your system unusable. Be very careful.
213 acpi.debug_level= [HW,ACPI]
214 Format: <int>
215 Each bit of the <int> indicates an ACPI debug level,
216 1: enable, 0: disable. It is useful for boot time
217 debugging. After system has booted up, it can be set
218 via /sys/module/acpi/parameters/debug_level.
219 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
220 Available bits (add the numbers together) to enable different
221 debug output levels of the ACPI subsystem:
222 0x01 error 0x02 warn 0x04 init 0x08 debug object
223 0x10 info 0x20 init names 0x40 parse 0x80 load
224 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
225 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
226 0x10000 resources 0x20000 user requests 0x40000 package.
227 The number can be in decimal or prefixed with 0x in hex.
228 Warning: Many of these options can produce a lot of
229 output and make your system unusable. Be very careful.
231 acpi_pm_good [X86-32,X86-64]
232 Override the pmtimer bug detection: force the kernel
233 to assume that this machine's pmtimer latches its value
234 and always returns good values.
236 agp= [AGP]
237 { off | try_unsupported }
238 off: disable AGP support
239 try_unsupported: try to drive unsupported chipsets
240 (may crash computer or cause data corruption)
242 enable_timer_pin_1 [i386,x86-64]
243 Enable PIN 1 of APIC timer
244 Can be useful to work around chipset bugs
245 (in particular on some ATI chipsets).
246 The kernel tries to set a reasonable default.
248 disable_timer_pin_1 [i386,x86-64]
249 Disable PIN 1 of APIC timer
250 Can be useful to work around chipset bugs.
252 ad1848= [HW,OSS]
253 Format: <io>,<irq>,<dma>,<dma2>,<type>
255 advansys= [HW,SCSI]
256 See header of drivers/scsi/advansys.c.
258 advwdt= [HW,WDT] Advantech WDT
259 Format: <iostart>,<iostop>
261 aedsp16= [HW,OSS] Audio Excel DSP 16
262 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
263 See also header of sound/oss/aedsp16.c.
265 aha152x= [HW,SCSI]
266 See Documentation/scsi/aha152x.txt.
268 aha1542= [HW,SCSI]
269 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
271 aic7xxx= [HW,SCSI]
272 See Documentation/scsi/aic7xxx.txt.
274 aic79xx= [HW,SCSI]
275 See Documentation/scsi/aic79xx.txt.
277 amijoy.map= [HW,JOY] Amiga joystick support
278 Map of devices attached to JOY0DAT and JOY1DAT
279 Format: <a>,<b>
280 See also Documentation/kernel/input/joystick.txt
282 analog.map= [HW,JOY] Analog joystick and gamepad support
283 Specifies type or capabilities of an analog joystick
284 connected to one of 16 gameports
285 Format: <type1>,<type2>,..<type16>
287 apc= [HW,SPARC]
288 Power management functions (SPARCstation-4/5 + deriv.)
289 Format: noidle
290 Disable APC CPU standby support. SPARCstation-Fox does
291 not play well with APC CPU idle - disable it if you have
292 APC and your system crashes randomly.
294 apic= [APIC,i386] Advanced Programmable Interrupt Controller
295 Change the output verbosity whilst booting
296 Format: { quiet (default) | verbose | debug }
297 Change the amount of debugging information output
298 when initialising the APIC and IO-APIC components.
300 apm= [APM] Advanced Power Management
301 See header of arch/i386/kernel/apm.c.
303 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
304 Format: <io>,<irq>,<nodeID>
306 ataflop= [HW,M68k]
308 atarimouse= [HW,MOUSE] Atari Mouse
310 atascsi= [HW,SCSI] Atari SCSI
312 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
313 EzKey and similar keyboards
315 atkbd.reset= [HW] Reset keyboard during initialization
317 atkbd.set= [HW] Select keyboard code set
318 Format: <int> (2 = AT (default), 3 = PS/2)
320 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
321 keyboards
323 atkbd.softraw= [HW] Choose between synthetic and real raw mode
324 Format: <bool> (0 = real, 1 = synthetic (default))
326 atkbd.softrepeat= [HW]
327 Use software keyboard repeat
329 autotest [IA64]
331 baycom_epp= [HW,AX25]
332 Format: <io>,<mode>
334 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
335 Format: <io>,<mode>
336 See header of drivers/net/hamradio/baycom_par.c.
338 baycom_ser_fdx= [HW,AX25]
339 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
340 Format: <io>,<irq>,<mode>[,<baud>]
341 See header of drivers/net/hamradio/baycom_ser_fdx.c.
343 baycom_ser_hdx= [HW,AX25]
344 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
345 Format: <io>,<irq>,<mode>
346 See header of drivers/net/hamradio/baycom_ser_hdx.c.
348 boot_delay= Milliseconds to delay each printk during boot.
349 Values larger than 10 seconds (10000) are changed to
350 no delay (0).
351 Format: integer
353 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
354 bttv.radio= Most important insmod options are available as
355 kernel args too.
356 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
357 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
359 BusLogic= [HW,SCSI]
360 See drivers/scsi/BusLogic.c, comment before function
361 BusLogic_ParseDriverOptions().
363 c101= [NET] Moxa C101 synchronous serial card
365 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
366 Sometimes CPU hardware bugs make them report the cache
367 size incorrectly. The kernel will attempt work arounds
368 to fix known problems, but for some CPUs it is not
369 possible to determine what the correct size should be.
370 This option provides an override for these situations.
372 capability.disable=
373 [SECURITY] Disable capabilities. This would normally
374 be used only if an alternative security model is to be
375 configured. Potentially dangerous and should only be
376 used if you are entirely sure of the consequences.
378 ccw_timeout_log [S390]
379 See Documentation/s390/CommonIO for details.
381 checkreqprot [SELINUX] Set initial checkreqprot flag value.
382 Format: { "0" | "1" }
383 See security/selinux/Kconfig help text.
384 0 -- check protection applied by kernel (includes
385 any implied execute protection).
386 1 -- check protection requested by application.
387 Default value is set via a kernel config option.
388 Value can be changed at runtime via
389 /selinux/checkreqprot.
391 cio_ignore= [S390]
392 See Documentation/s390/CommonIO for details.
394 cio_msg= [S390]
395 See Documentation/s390/CommonIO for details.
397 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
398 [Deprecated]
399 Forces specified clocksource (if available) to be used
400 when calculating gettimeofday(). If specified
401 clocksource is not available, it defaults to PIT.
402 Format: { pit | tsc | cyclone | pmtmr }
404 clocksource= [GENERIC_TIME] Override the default clocksource
405 Format: <string>
406 Override the default clocksource and use the clocksource
407 with the name specified.
408 Some clocksource names to choose from, depending on
409 the platform:
410 [all] jiffies (this is the base, fallback clocksource)
411 [ACPI] acpi_pm
412 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
413 pxa_timer,timer3,32k_counter,timer0_1
414 [AVR32] avr32
415 [X86-32] pit,hpet,tsc,vmi-timer;
416 scx200_hrt on Geode; cyclone on IBM x440
417 [MIPS] MIPS
418 [PARISC] cr16
419 [S390] tod
420 [SH] SuperH
421 [SPARC64] tick
422 [X86-64] hpet,tsc
424 clearcpuid=BITNUM [X86]
425 Disable CPUID feature X for the kernel. See
426 include/asm-x86/cpufeature.h for the valid bit numbers.
427 Note the Linux specific bits are not necessarily
428 stable over kernel options, but the vendor specific
429 ones should be.
430 Also note that user programs calling CPUID directly
431 or using the feature without checking anything
432 will still see it. This just prevents it from
433 being used by the kernel or shown in /proc/cpuinfo.
434 Also note the kernel might malfunction if you disable
435 some critical bits.
437 code_bytes [IA32/X86_64] How many bytes of object code to print
438 in an oops report.
439 Range: 0 - 8192
440 Default: 64
442 disable_8254_timer
443 enable_8254_timer
444 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
445 over the 8254 in addition to over the IO-APIC. The
446 kernel tries to set a sensible default.
448 hpet= [X86-32,HPET] option to control HPET usage
449 Format: { enable (default) | disable | force }
450 disable: disable HPET and use PIT instead
451 force: allow force enabled of undocumented chips (ICH4,
452 VIA, nVidia)
454 com20020= [HW,NET] ARCnet - COM20020 chipset
455 Format:
456 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
458 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
459 Format: <io>[,<irq>]
461 com90xx= [HW,NET]
462 ARCnet - COM90xx chipset (memory-mapped buffers)
463 Format: <io>[,<irq>[,<memstart>]]
465 condev= [HW,S390] console device
466 conmode=
468 console= [KNL] Output console device and options.
470 tty<n> Use the virtual console device <n>.
472 ttyS<n>[,options]
473 ttyUSB0[,options]
474 Use the specified serial port. The options are of
475 the form "bbbbpnf", where "bbbb" is the baud rate,
476 "p" is parity ("n", "o", or "e"), "n" is number of
477 bits, and "f" is flow control ("r" for RTS or
478 omit it). Default is "9600n8".
480 See Documentation/serial-console.txt for more
481 information. See
482 Documentation/networking/netconsole.txt for an
483 alternative.
485 uart[8250],io,<addr>[,options]
486 uart[8250],mmio,<addr>[,options]
487 Start an early, polled-mode console on the 8250/16550
488 UART at the specified I/O port or MMIO address,
489 switching to the matching ttyS device later. The
490 options are the same as for ttyS, above.
492 earlycon= [KNL] Output early console device and options.
493 uart[8250],io,<addr>[,options]
494 uart[8250],mmio,<addr>[,options]
495 Start an early, polled-mode console on the 8250/16550
496 UART at the specified I/O port or MMIO address.
497 The options are the same as for ttyS, above.
499 no_console_suspend
500 [HW] Never suspend the console
501 Disable suspending of consoles during suspend and
502 hibernate operations. Once disabled, debugging
503 messages can reach various consoles while the rest
504 of the system is being put to sleep (ie, while
505 debugging driver suspend/resume hooks). This may
506 not work reliably with all consoles, but is known
507 to work with serial and VGA consoles.
509 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
510 Format:
511 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
513 crashkernel=nn[KMG]@ss[KMG]
514 [KNL] Reserve a chunk of physical memory to
515 hold a kernel to switch to with kexec on panic.
517 crashkernel=range1:size1[,range2:size2,...][@offset]
518 [KNL] Same as above, but depends on the memory
519 in the running system. The syntax of range is
520 start-[end] where start and end are both
521 a memory unit (amount[KMG]). See also
522 Documentation/kdump/kdump.txt for a example.
524 cs4232= [HW,OSS]
525 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
527 cs89x0_dma= [HW,NET]
528 Format: <dma>
530 cs89x0_media= [HW,NET]
531 Format: { rj45 | aui | bnc }
533 dasd= [HW,NET]
534 See header of drivers/s390/block/dasd_devmap.c.
536 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
537 (one device per port)
538 Format: <port#>,<type>
539 See also Documentation/input/joystick-parport.txt
541 debug [KNL] Enable kernel debugging (events log level).
543 debug_locks_verbose=
544 [KNL] verbose self-tests
545 Format=<0|1>
546 Print debugging info while doing the locking API
547 self-tests.
548 We default to 0 (no extra messages), setting it to
549 1 will print _a lot_ more information - normally
550 only useful to kernel developers.
552 decnet= [HW,NET]
553 Format: <area>[,<node>]
554 See also Documentation/networking/decnet.txt.
556 vt.default_blu= [VT]
557 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
558 Change the default blue palette of the console.
559 This is a 16-member array composed of values
560 ranging from 0-255.
562 vt.default_grn= [VT]
563 Format: <green0>,<green1>,<green2>,...,<green15>
564 Change the default green palette of the console.
565 This is a 16-member array composed of values
566 ranging from 0-255.
568 vt.default_red= [VT]
569 Format: <red0>,<red1>,<red2>,...,<red15>
570 Change the default red palette of the console.
571 This is a 16-member array composed of values
572 ranging from 0-255.
574 vt.default_utf8=
575 [VT]
576 Format=<0|1>
577 Set system-wide default UTF-8 mode for all tty's.
578 Default is 1, i.e. UTF-8 mode is enabled for all
579 newly opened terminals.
581 dhash_entries= [KNL]
582 Set number of hash buckets for dentry cache.
584 digi= [HW,SERIAL]
585 IO parameters + enable/disable command.
587 digiepca= [HW,SERIAL]
588 See drivers/char/README.epca and
589 Documentation/digiepca.txt.
591 disable_mtrr_trim [X86, Intel and AMD only]
592 By default the kernel will trim any uncacheable
593 memory out of your available memory pool based on
594 MTRR settings. This parameter disables that behavior,
595 possibly causing your machine to run very slowly.
597 dmasound= [HW,OSS] Sound subsystem buffers
599 dscc4.setup= [NET]
601 dtc3181e= [HW,SCSI]
603 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
604 earlyprintk=vga
605 earlyprintk=serial[,ttySn[,baudrate]]
607 Append ",keep" to not disable it when the real console
608 takes over.
610 Only vga or serial at a time, not both.
612 Currently only ttyS0 and ttyS1 are supported.
614 Interaction with the standard serial driver is not
615 very good.
617 The VGA output is eventually overwritten by the real
618 console.
620 eata= [HW,SCSI]
622 edd= [EDD]
623 Format: {"of[f]" | "sk[ipmbr]"}
624 See comment in arch/i386/boot/edd.S
626 eisa_irq_edge= [PARISC,HW]
627 See header of drivers/parisc/eisa.c.
629 elanfreq= [X86-32]
630 See comment before function elanfreq_setup() in
631 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
633 elevator= [IOSCHED]
634 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
635 See Documentation/block/as-iosched.txt and
636 Documentation/block/deadline-iosched.txt for details.
638 elfcorehdr= [X86-32, X86_64]
639 Specifies physical address of start of kernel core
640 image elf header. Generally kexec loader will
641 pass this option to capture kernel.
642 See Documentation/kdump/kdump.txt for details.
644 enforcing [SELINUX] Set initial enforcing status.
645 Format: {"0" | "1"}
646 See security/selinux/Kconfig help text.
647 0 -- permissive (log only, no denials).
648 1 -- enforcing (deny and log).
649 Default value is 0.
650 Value can be changed at runtime via /selinux/enforce.
652 es1371= [HW,OSS]
653 Format: <spdif>,[<nomix>,[<amplifier>]]
654 See also header of sound/oss/es1371.c.
656 ether= [HW,NET] Ethernet cards parameters
657 This option is obsoleted by the "netdev=" option, which
658 has equivalent usage. See its documentation for details.
660 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
661 Format: <io>[,<irq>]
663 failslab=
664 fail_page_alloc=
665 fail_make_request=[KNL]
666 General fault injection mechanism.
667 Format: <interval>,<probability>,<space>,<times>
668 See also /Documentation/fault-injection/.
670 fd_mcs= [HW,SCSI]
671 See header of drivers/scsi/fd_mcs.c.
673 fdomain= [HW,SCSI]
674 See header of drivers/scsi/fdomain.c.
676 floppy= [HW]
677 See Documentation/floppy.txt.
679 gamecon.map[2|3]=
680 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
681 support via parallel port (up to 5 devices per port)
682 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
683 See also Documentation/input/joystick-parport.txt
685 gamma= [HW,DRM]
687 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
688 Format: off | on
689 default: on
691 gdth= [HW,SCSI]
692 See header of drivers/scsi/gdth.c.
694 gpt [EFI] Forces disk with valid GPT signature but
695 invalid Protective MBR to be treated as GPT.
697 gvp11= [HW,SCSI]
699 hashdist= [KNL,NUMA] Large hashes allocated during boot
700 are distributed across NUMA nodes. Defaults on
701 for IA-64, off otherwise.
702 Format: 0 | 1 (for off | on)
704 hcl= [IA-64] SGI's Hardware Graph compatibility layer
706 hd= [EIDE] (E)IDE hard drive subsystem geometry
707 Format: <cyl>,<head>,<sect>
709 hd?= [HW] (E)IDE subsystem
710 hd?lun= See Documentation/ide.txt.
712 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
713 size of <nn>. This works even on boxes that have no
714 highmem otherwise. This also works to reduce highmem
715 size on bigger boxes.
717 highres= [KNL] Enable/disable high resolution timer mode.
718 Valid parameters: "on", "off"
719 Default: "on"
721 hisax= [HW,ISDN]
722 See Documentation/isdn/README.HiSax.
724 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
725 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
727 i8042.direct [HW] Put keyboard port into non-translated mode
728 i8042.dumbkbd [HW] Pretend that controller can only read data from
729 keyboard and cannot control its state
730 (Don't attempt to blink the leds)
731 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
732 i8042.nokbd [HW] Don't check/create keyboard port
733 i8042.nomux [HW] Don't check presence of an active multiplexing
734 controller
735 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
736 controllers
737 i8042.panicblink=
738 [HW] Frequency with which keyboard LEDs should blink
739 when kernel panics (default is 0.5 sec)
740 i8042.reset [HW] Reset the controller during init and cleanup
741 i8042.unlock [HW] Unlock (ignore) the keylock
743 i810= [HW,DRM]
745 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
746 indicates that the driver is running on unsupported
747 hardware.
748 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
749 does not match list of supported models.
750 i8k.power_status
751 [HW] Report power status in /proc/i8k
752 (disabled by default)
753 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
754 capability is set.
756 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
757 See Documentation/mca.txt.
759 icn= [HW,ISDN]
760 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
762 ide= [HW] (E)IDE subsystem
763 Format: ide=nodma or ide=doubler or ide=reverse
764 See Documentation/ide.txt.
766 ide?= [HW] (E)IDE subsystem
767 Format: ide?=noprobe or chipset specific parameters.
768 See Documentation/ide.txt.
770 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
771 See Documentation/ide.txt.
773 idle= [X86]
774 Format: idle=poll or idle=mwait
775 Poll forces a polling idle loop that can slightly improves the performance
776 of waking up a idle CPU, but will use a lot of power and make the system
777 run hot. Not recommended.
778 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
779 to not use it because it doesn't save as much power as a normal idle
780 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
781 as idle=poll.
783 ignore_loglevel [KNL]
784 Ignore loglevel setting - this will print /all/
785 kernel messages to the console. Useful for debugging.
787 ihash_entries= [KNL]
788 Set number of hash buckets for inode cache.
790 in2000= [HW,SCSI]
791 See header of drivers/scsi/in2000.c.
793 init= [KNL]
794 Format: <full_path>
795 Run specified binary instead of /sbin/init as init
796 process.
798 initcall_debug [KNL] Trace initcalls as they are executed. Useful
799 for working out where the kernel is dying during
800 startup.
802 initrd= [BOOT] Specify the location of the initial ramdisk
804 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
805 Format: <irq>
807 inttest= [IA64]
809 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
810 off
811 Disable intel iommu driver.
812 igfx_off [Default Off]
813 By default, gfx is mapped as normal device. If a gfx
814 device has a dedicated DMAR unit, the DMAR unit is
815 bypassed by not enabling DMAR with this option. In
816 this case, gfx device will use physical address for
817 DMA.
818 forcedac [x86_64]
819 With this option iommu will not optimize to look
820 for io virtual address below 32 bit forcing dual
821 address cycle on pci bus for cards supporting greater
822 than 32 bit addressing. The default is to look
823 for translation below 32 bit and if not available
824 then look in the higher range.
826 io_delay= [X86-32,X86-64] I/O delay method
827 0x80
828 Standard port 0x80 based delay
829 0xed
830 Alternate port 0xed based delay (needed on some systems)
831 udelay
832 Simple two microseconds delay
833 none
834 No delay
836 io7= [HW] IO7 for Marvel based alpha systems
837 See comment before marvel_specify_io7 in
838 arch/alpha/kernel/core_marvel.c.
840 ip= [IP_PNP]
841 See Documentation/nfsroot.txt.
843 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
844 See comment before ip2_setup() in
845 drivers/char/ip2/ip2base.c.
847 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
848 See header of drivers/scsi/ips.c.
850 ports= [IP_VS_FTP] IPVS ftp helper module
851 Default is 21.
852 Up to 8 (IP_VS_APP_MAX_PORTS) ports
853 may be specified.
854 Format: <port>,<port>....
856 irqfixup [HW]
857 When an interrupt is not handled search all handlers
858 for it. Intended to get systems with badly broken
859 firmware running.
861 irqpoll [HW]
862 When an interrupt is not handled search all handlers
863 for it. Also check all handlers each timer
864 interrupt. Intended to get systems with badly broken
865 firmware running.
867 isapnp= [ISAPNP]
868 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
870 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
871 Format:
872 <cpu number>,...,<cpu number>
873 or
874 <cpu number>-<cpu number> (must be a positive range in ascending order)
875 or a mixture
876 <cpu number>,...,<cpu number>-<cpu number>
877 This option can be used to specify one or more CPUs
878 to isolate from the general SMP balancing and scheduling
879 algorithms. The only way to move a process onto or off
880 an "isolated" CPU is via the CPU affinity syscalls.
881 <cpu number> begins at 0 and the maximum value is
882 "number of CPUs in system - 1".
884 This option is the preferred way to isolate CPUs. The
885 alternative -- manually setting the CPU mask of all
886 tasks in the system -- can cause problems and
887 suboptimal load balancer performance.
889 iucv= [HW,NET]
891 js= [HW,JOY] Analog joystick
892 See Documentation/input/joystick.txt.
894 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
895 specifies the amount of memory usable by the kernel
896 for non-movable allocations. The requested amount is
897 spread evenly throughout all nodes in the system. The
898 remaining memory in each node is used for Movable
899 pages. In the event, a node is too small to have both
900 kernelcore and Movable pages, kernelcore pages will
901 take priority and other nodes will have a larger number
902 of kernelcore pages. The Movable zone is used for the
903 allocation of pages that may be reclaimed or moved
904 by the page migration subsystem. This means that
905 HugeTLB pages may not be allocated from this zone.
906 Note that allocations like PTEs-from-HighMem still
907 use the HighMem zone if it exists, and the Normal
908 zone if it does not.
910 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
911 is similar to kernelcore except it specifies the
912 amount of memory used for migratable allocations.
913 If both kernelcore and movablecore is specified,
914 then kernelcore will be at *least* the specified
915 value but may be more. If movablecore on its own
916 is specified, the administrator must be careful
917 that the amount of memory usable for all allocations
918 is not too small.
920 keepinitrd [HW,ARM]
922 kstack=N [X86-32,X86-64] Print N words from the kernel stack
923 in oops dumps.
925 l2cr= [PPC]
927 lapic [X86-32,APIC] Enable the local APIC even if BIOS
928 disabled it.
930 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
931 C2 power state.
933 libata.dma= [LIBATA] DMA control
934 libata.dma=0 Disable all PATA and SATA DMA
935 libata.dma=1 PATA and SATA Disk DMA only
936 libata.dma=2 ATAPI (CDROM) DMA only
937 libata.dma=4 Compact Flash DMA only
938 Combinations also work, so libata.dma=3 enables DMA
939 for disks and CDROMs, but not CFs.
941 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
942 when set.
943 Format: <int>
945 load_ramdisk= [RAM] List of ramdisks to load from floppy
946 See Documentation/ramdisk.txt.
948 lockd.nlm_grace_period=P [NFS] Assign grace period.
949 Format: <integer>
951 lockd.nlm_tcpport=N [NFS] Assign TCP port.
952 Format: <integer>
954 lockd.nlm_timeout=T [NFS] Assign timeout value.
955 Format: <integer>
957 lockd.nlm_udpport=M [NFS] Assign UDP port.
958 Format: <integer>
960 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
961 Format: <irq>
963 loglevel= All Kernel Messages with a loglevel smaller than the
964 console loglevel will be printed to the console. It can
965 also be changed with klogd or other programs. The
966 loglevels are defined as follows:
968 0 (KERN_EMERG) system is unusable
969 1 (KERN_ALERT) action must be taken immediately
970 2 (KERN_CRIT) critical conditions
971 3 (KERN_ERR) error conditions
972 4 (KERN_WARNING) warning conditions
973 5 (KERN_NOTICE) normal but significant condition
974 6 (KERN_INFO) informational
975 7 (KERN_DEBUG) debug-level messages
977 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
978 Format: { n | nk | nM }
979 n must be a power of two. The default size
980 is set in the kernel config file.
982 logo.nologo [FB] Disables display of the built-in Linux logo.
983 This may be used to provide more screen space for
984 kernel log messages and is useful when debugging
985 kernel boot problems.
987 lp=0 [LP] Specify parallel ports to use, e.g,
988 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
989 lp=reset first parallel port). 'lp=0' disables the
990 lp=auto printer driver. 'lp=reset' (which can be
991 specified in addition to the ports) causes
992 attached printers to be reset. Using
993 lp=port1,port2,... specifies the parallel ports
994 to associate lp devices with, starting with
995 lp0. A port specification may be 'none' to skip
996 that lp device, or a parport name such as
997 'parport0'. Specifying 'lp=auto' instead of a
998 port specification list means that device IDs
999 from each port should be examined, to see if
1000 an IEEE 1284-compliant printer is attached; if
1001 so, the driver will manage that printer.
1002 See also header of drivers/char/lp.c.
1004 lpj=n [KNL]
1005 Sets loops_per_jiffy to given constant, thus avoiding
1006 time-consuming boot-time autodetection (up to 250 ms per
1007 CPU). 0 enables autodetection (default). To determine
1008 the correct value for your kernel, boot with normal
1009 autodetection and see what value is printed. Note that
1010 on SMP systems the preset will be applied to all CPUs,
1011 which is likely to cause problems if your CPUs need
1012 significantly divergent settings. An incorrect value
1013 will cause delays in the kernel to be wrong, leading to
1014 unpredictable I/O errors and other breakage. Although
1015 unlikely, in the extreme case this might damage your
1016 hardware.
1018 ltpc= [NET]
1019 Format: <io>,<irq>,<dma>
1021 mac5380= [HW,SCSI] Format:
1022 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1024 mac53c9x= [HW,SCSI] Format:
1025 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1027 machvec= [IA64] Force the use of a particular machine-vector
1028 (machvec) in a generic kernel.
1029 Example: machvec=hpzx1_swiotlb
1031 max_loop= [LOOP] Maximum number of loopback devices that can
1032 be mounted
1033 Format: <1-256>
1035 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1036 should make use of. maxcpus=n : n >= 0 limits the
1037 kernel to using 'n' processors. n=0 is a special case,
1038 it is equivalent to "nosmp", which also disables
1039 the IO APIC.
1041 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1042 equal to this physical address is ignored.
1044 max_luns= [SCSI] Maximum number of LUNs to probe.
1045 Should be between 1 and 2^32-1.
1047 max_report_luns=
1048 [SCSI] Maximum number of LUNs received.
1049 Should be between 1 and 16384.
1051 mca-pentium [BUGS=X86-32]
1053 mcatest= [IA-64]
1055 mce [X86-32] Machine Check Exception
1057 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1059 md= [HW] RAID subsystems devices and level
1060 See Documentation/md.txt.
1062 mdacon= [MDA]
1063 Format: <first>,<last>
1064 Specifies range of consoles to be captured by the MDA.
1066 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1067 Amount of memory to be used when the kernel is not able
1068 to see the whole system memory or for test.
1069 [X86-32] Use together with memmap= to avoid physical
1070 address space collisions. Without memmap= PCI devices
1071 could be placed at addresses belonging to unused RAM.
1073 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1074 memory.
1076 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1077 E820 memory map, as specified by the user.
1078 Such memmap=exactmap lines can be constructed based on
1079 BIOS output or other requirements. See the memmap=nn@ss
1080 option description.
1082 memmap=nn[KMG]@ss[KMG]
1083 [KNL] Force usage of a specific region of memory
1084 Region of memory to be used, from ss to ss+nn.
1086 memmap=nn[KMG]#ss[KMG]
1087 [KNL,ACPI] Mark specific memory as ACPI data.
1088 Region of memory to be used, from ss to ss+nn.
1090 memmap=nn[KMG]$ss[KMG]
1091 [KNL,ACPI] Mark specific memory as reserved.
1092 Region of memory to be used, from ss to ss+nn.
1094 meye.*= [HW] Set MotionEye Camera parameters
1095 See Documentation/video4linux/meye.txt.
1097 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1098 Multi-Function General Purpose Timers on AMD Geode
1099 platforms.
1101 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1102 the BIOS has incorrectly applied a workaround. TinyBIOS
1103 version 0.98 is known to be affected, 0.99 fixes the
1104 problem by letting the user disable the workaround.
1106 mga= [HW,DRM]
1108 mousedev.tap_time=
1109 [MOUSE] Maximum time between finger touching and
1110 leaving touchpad surface for touch to be considered
1111 a tap and be reported as a left button click (for
1112 touchpads working in absolute mode only).
1113 Format: <msecs>
1114 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1115 reporting absolute coordinates, such as tablets
1116 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1117 reporting absolute coordinates, such as tablets
1119 mpu401= [HW,OSS]
1120 Format: <io>,<irq>
1122 MTD_Partition= [MTD]
1123 Format: <name>,<region-number>,<size>,<offset>
1125 MTD_Region= [MTD] Format:
1126 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1128 mtdparts= [MTD]
1129 See drivers/mtd/cmdlinepart.c.
1131 mtouchusb.raw_coordinates=
1132 [HW] Make the MicroTouch USB driver use raw coordinates
1133 ('y', default) or cooked coordinates ('n')
1135 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1137 NCR_D700= [HW,SCSI]
1138 See header of drivers/scsi/NCR_D700.c.
1140 ncr5380= [HW,SCSI]
1142 ncr53c400= [HW,SCSI]
1144 ncr53c400a= [HW,SCSI]
1146 ncr53c406a= [HW,SCSI]
1148 ncr53c8xx= [HW,SCSI]
1150 netdev= [NET] Network devices parameters
1151 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1152 Note that mem_start is often overloaded to mean
1153 something different and driver-specific.
1154 This usage is only documented in each driver source
1155 file if at all.
1157 nfsaddrs= [NFS]
1158 See Documentation/nfsroot.txt.
1160 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1161 See Documentation/nfsroot.txt.
1163 nfs.callback_tcpport=
1164 [NFS] set the TCP port on which the NFSv4 callback
1165 channel should listen.
1167 nfs.idmap_cache_timeout=
1168 [NFS] set the maximum lifetime for idmapper cache
1169 entries.
1171 nfs.enable_ino64=
1172 [NFS] enable 64-bit inode numbers.
1173 If zero, the NFS client will fake up a 32-bit inode
1174 number for the readdir() and stat() syscalls instead
1175 of returning the full 64-bit number.
1176 The default is to return 64-bit inode numbers.
1178 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1179 when a NMI is triggered.
1180 Format: [state][,regs][,debounce][,die]
1182 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1184 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1185 emulation library even if a 387 maths coprocessor
1186 is present.
1188 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1189 caches in the slab allocator. Saves per-node memory,
1190 but will impact performance.
1192 noalign [KNL,ARM]
1194 noapic [SMP,APIC] Tells the kernel to not make use of any
1195 IOAPICs that may be present in the system.
1197 nobats [PPC] Do not use BATs for mapping kernel lowmem
1198 on "Classic" PPC cores.
1200 nocache [ARM]
1202 nodelayacct [KNL] Disable per-task delay accounting
1204 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1206 noefi [X86-32,X86-64] Disable EFI runtime services support.
1208 noexec [IA-64]
1210 noexec [X86-32,X86-64]
1211 noexec=on: enable non-executable mappings (default)
1212 noexec=off: disable nn-executable mappings
1214 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1215 register save and restore. The kernel will only save
1216 legacy floating-point registers on task switch.
1218 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1220 nohlt [BUGS=ARM]
1222 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1223 instruction doesn't work correctly and not to
1224 use it.
1226 nohalt [IA-64] Tells the kernel not to use the power saving
1227 function PAL_HALT_LIGHT when idle. This increases
1228 power-consumption. On the positive side, it reduces
1229 interrupt wake-up latency, which may improve performance
1230 in certain environments such as networked servers or
1231 real-time systems.
1233 nohz= [KNL] Boottime enable/disable dynamic ticks
1234 Valid arguments: on, off
1235 Default: on
1237 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1239 noirqdebug [X86-32] Disables the code which attempts to detect and
1240 disable unhandled interrupt sources.
1242 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1243 broken timer IRQ sources.
1245 noisapnp [ISAPNP] Disables ISA PnP code.
1247 noinitrd [RAM] Tells the kernel not to load any configured
1248 initial RAM disk.
1250 nointroute [IA-64]
1252 nojitter [IA64] Disables jitter checking for ITC timers.
1254 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1256 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1258 noltlbs [PPC] Do not use large page/tlb entries for kernel
1259 lowmem mapping on PPC40x.
1261 nomca [IA-64] Disable machine check abort handling
1263 nomce [X86-32] Machine Check Exception
1265 nomfgpt [X86-32] Disable Multi-Function General Purpose
1266 Timer usage (for AMD Geode machines).
1268 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1270 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1271 with UP alternatives
1273 noresidual [PPC] Don't use residual data on PReP machines.
1275 noresume [SWSUSP] Disables resume and restores original swap
1276 space.
1278 no-scroll [VGA] Disables scrollback.
1279 This is required for the Braillex ib80-piezo Braille
1280 reader made by F.H. Papenmeier (Germany).
1282 nosbagart [IA-64]
1284 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1286 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1287 and disable the IO APIC. legacy for "maxcpus=0".
1289 nosoftlockup [KNL] Disable the soft-lockup detector.
1291 nosync [HW,M68K] Disables sync negotiation for all devices.
1293 notsc [BUGS=X86-32] Disable Time Stamp Counter
1295 nousb [USB] Disable the USB subsystem
1297 nowb [ARM]
1299 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1300 one of ['zone', 'node', 'default'] can be specified
1301 This can be set from sysctl after boot.
1302 See Documentation/sysctl/vm.txt for details.
1304 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1306 opl3= [HW,OSS]
1307 Format: <io>
1309 oprofile.timer= [HW]
1310 Use timer interrupt instead of performance counters
1312 osst= [HW,SCSI] SCSI Tape Driver
1313 Format: <buffer_size>,<write_threshold>
1314 See also Documentation/scsi/st.txt.
1316 panic= [KNL] Kernel behaviour on panic
1317 Format: <timeout>
1319 parkbd.port= [HW] Parallel port number the keyboard adapter is
1320 connected to, default is 0.
1321 Format: <parport#>
1322 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1323 0 for XT, 1 for AT (default is AT).
1324 Format: <mode>
1326 parport= [HW,PPT] Specify parallel ports. 0 disables.
1327 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1328 Use 'auto' to force the driver to use any
1329 IRQ/DMA settings detected (the default is to
1330 ignore detected IRQ/DMA settings because of
1331 possible conflicts). You can specify the base
1332 address, IRQ, and DMA settings; IRQ and DMA
1333 should be numbers, or 'auto' (for using detected
1334 settings on that particular port), or 'nofifo'
1335 (to avoid using a FIFO even if it is detected).
1336 Parallel ports are assigned in the order they
1337 are specified on the command line, starting
1338 with parport0.
1340 parport_init_mode= [HW,PPT]
1341 Configure VIA parallel port to operate in
1342 a specific mode. This is necessary on Pegasos
1343 computer where firmware has no options for setting
1344 up parallel port mode and sets it to spp.
1345 Currently this function knows 686a and 8231 chips.
1346 Format: [spp|ps2|epp|ecp|ecpepp]
1348 pas2= [HW,OSS] Format:
1349 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1351 pas16= [HW,SCSI]
1352 See header of drivers/scsi/pas16.c.
1354 pause_on_oops=
1355 Halt all CPUs after the first oops has been printed for
1356 the specified number of seconds. This is to be used if
1357 your oopses keep scrolling off the screen.
1359 pcbit= [HW,ISDN]
1361 pcd. [PARIDE]
1362 See header of drivers/block/paride/pcd.c.
1363 See also Documentation/paride.txt.
1365 pci=option[,option...] [PCI] various PCI subsystem options:
1366 off [X86-32] don't probe for the PCI bus
1367 bios [X86-32] force use of PCI BIOS, don't access
1368 the hardware directly. Use this if your machine
1369 has a non-standard PCI host bridge.
1370 nobios [X86-32] disallow use of PCI BIOS, only direct
1371 hardware access methods are allowed. Use this
1372 if you experience crashes upon bootup and you
1373 suspect they are caused by the BIOS.
1374 conf1 [X86-32] Force use of PCI Configuration
1375 Mechanism 1.
1376 conf2 [X86-32] Force use of PCI Configuration
1377 Mechanism 2.
1378 noaer [PCIE] If the PCIEAER kernel config parameter is
1379 enabled, this kernel boot option can be used to
1380 disable the use of PCIE advanced error reporting.
1381 nodomains [PCI] Disable support for multiple PCI
1382 root domains (aka PCI segments, in ACPI-speak).
1383 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1384 Configuration
1385 nomsi [MSI] If the PCI_MSI kernel config parameter is
1386 enabled, this kernel boot option can be used to
1387 disable the use of MSI interrupts system-wide.
1388 nosort [X86-32] Don't sort PCI devices according to
1389 order given by the PCI BIOS. This sorting is
1390 done to get a device order compatible with
1391 older kernels.
1392 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1393 routing table. These calls are known to be buggy
1394 on several machines and they hang the machine
1395 when used, but on other computers it's the only
1396 way to get the interrupt routing table. Try
1397 this option if the kernel is unable to allocate
1398 IRQs or discover secondary PCI buses on your
1399 motherboard.
1400 rom [X86-32] Assign address space to expansion ROMs.
1401 Use with caution as certain devices share
1402 address decoders between ROMs and other
1403 resources.
1404 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1405 assigned automatically to PCI devices. You can
1406 make the kernel exclude IRQs of your ISA cards
1407 this way.
1408 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1409 of the PIRQ table (normally generated
1410 by the BIOS) if it is outside the
1411 F0000h-100000h range.
1412 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1413 useful if the kernel is unable to find your
1414 secondary buses and you want to tell it
1415 explicitly which ones they are.
1416 assign-busses [X86-32] Always assign all PCI bus
1417 numbers ourselves, overriding
1418 whatever the firmware may have done.
1419 usepirqmask [X86-32] Honor the possible IRQ mask stored
1420 in the BIOS $PIR table. This is needed on
1421 some systems with broken BIOSes, notably
1422 some HP Pavilion N5400 and Omnibook XE3
1423 notebooks. This will have no effect if ACPI
1424 IRQ routing is enabled.
1425 noacpi [X86-32] Do not use ACPI for IRQ routing
1426 or for PCI scanning.
1427 use_crs [X86-32] Use _CRS for PCI resource
1428 allocation.
1429 routeirq Do IRQ routing for all PCI devices.
1430 This is normally done in pci_enable_device(),
1431 so this option is a temporary workaround
1432 for broken drivers that don't call it.
1433 firmware [ARM] Do not re-enumerate the bus but instead
1434 just use the configuration from the
1435 bootloader. This is currently used on
1436 IXP2000 systems where the bus has to be
1437 configured a certain way for adjunct CPUs.
1438 noearly [X86] Don't do any early type 1 scanning.
1439 This might help on some broken boards which
1440 machine check when some devices' config space
1441 is read. But various workarounds are disabled
1442 and some IOMMU drivers will not work.
1443 bfsort Sort PCI devices into breadth-first order.
1444 This sorting is done to get a device
1445 order compatible with older (<= 2.4) kernels.
1446 nobfsort Don't sort PCI devices into breadth-first order.
1447 cbiosize=nn[KMG] The fixed amount of bus space which is
1448 reserved for the CardBus bridge's IO window.
1449 The default value is 256 bytes.
1450 cbmemsize=nn[KMG] The fixed amount of bus space which is
1451 reserved for the CardBus bridge's memory
1452 window. The default value is 64 megabytes.
1454 pcmv= [HW,PCMCIA] BadgePAD 4
1456 pd. [PARIDE]
1457 See Documentation/paride.txt.
1459 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1460 boot time.
1461 Format: { 0 | 1 }
1462 See arch/parisc/kernel/pdc_chassis.c
1464 pf. [PARIDE]
1465 See Documentation/paride.txt.
1467 pg. [PARIDE]
1468 See Documentation/paride.txt.
1470 pirq= [SMP,APIC] Manual mp-table setup
1471 See Documentation/i386/IO-APIC.txt.
1473 plip= [PPT,NET] Parallel port network link
1474 Format: { parport<nr> | timid | 0 }
1475 See also Documentation/parport.txt.
1477 pnpacpi= [ACPI]
1478 { off }
1480 pnpbios= [ISAPNP]
1481 { on | off | curr | res | no-curr | no-res }
1483 pnp_reserve_irq=
1484 [ISAPNP] Exclude IRQs for the autoconfiguration
1486 pnp_reserve_dma=
1487 [ISAPNP] Exclude DMAs for the autoconfiguration
1489 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1490 Ranges are in pairs (I/O port base and size).
1492 pnp_reserve_mem=
1493 [ISAPNP] Exclude memory regions for the
1494 autoconfiguration.
1495 Ranges are in pairs (memory base and size).
1497 print-fatal-signals=
1498 [KNL] debug: print fatal signals
1499 print-fatal-signals=1: print segfault info to
1500 the kernel console.
1501 default: off.
1503 printk.time= Show timing data prefixed to each printk message line
1504 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1506 profile= [KNL] Enable kernel profiling via /proc/profile
1507 Format: [schedule,]<number>
1508 Param: "schedule" - profile schedule points.
1509 Param: <number> - step/bucket size as a power of 2 for
1510 statistical time based profiling.
1511 Param: "sleep" - profile D-state sleeping (millisecs).
1512 Requires CONFIG_SCHEDSTATS
1513 Param: "kvm" - profile VM exits.
1515 processor.max_cstate= [HW,ACPI]
1516 Limit processor to maximum C-state
1517 max_cstate=9 overrides any DMI blacklist limit.
1519 processor.nocst [HW,ACPI]
1520 Ignore the _CST method to determine C-states,
1521 instead using the legacy FADT method
1523 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1524 before loading.
1525 See Documentation/ramdisk.txt.
1527 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1528 probe for; one of (bare|imps|exps|lifebook|any).
1529 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1530 per second.
1531 psmouse.resetafter= [HW,MOUSE]
1532 Try to reset the device after so many bad packets
1533 (0 = never).
1534 psmouse.resolution=
1535 [HW,MOUSE] Set desired mouse resolution, in dpi.
1536 psmouse.smartscroll=
1537 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1538 0 = disabled, 1 = enabled (default).
1540 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1541 Format:
1542 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1544 pt. [PARIDE]
1545 See Documentation/paride.txt.
1547 pty.legacy_count=
1548 [KNL] Number of legacy pty's. Overwrites compiled-in
1549 default number.
1551 quiet [KNL] Disable most log messages
1553 r128= [HW,DRM]
1555 raid= [HW,RAID]
1556 See Documentation/md.txt.
1558 ramdisk_blocksize= [RAM]
1559 See Documentation/ramdisk.txt.
1561 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1562 See Documentation/ramdisk.txt.
1564 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1565 RCU callbacks to process in one batch.
1567 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1568 RCU callbacks over which batch limiting is disabled.
1570 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1571 RCU callbacks below which batch limiting is re-enabled.
1573 rdinit= [KNL]
1574 Format: <full_path>
1575 Run specified binary instead of /init from the ramdisk,
1576 used for early userspace startup. See initrd.
1578 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1579 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1580 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1582 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1584 reservetop= [X86-32]
1585 Format: nn[KMG]
1586 Reserves a hole at the top of the kernel virtual
1587 address space.
1589 reset_devices [KNL] Force drivers to reset the underlying device
1590 during initialization.
1592 resume= [SWSUSP]
1593 Specify the partition device for software suspend
1595 resume_offset= [SWSUSP]
1596 Specify the offset from the beginning of the partition
1597 given by "resume=" at which the swap header is located,
1598 in <PAGE_SIZE> units (needed only for swap files).
1599 See Documentation/power/swsusp-and-swap-files.txt
1601 retain_initrd [RAM] Keep initrd memory after extraction
1603 rhash_entries= [KNL,NET]
1604 Set number of hash buckets for route cache
1606 riscom8= [HW,SERIAL]
1607 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1609 ro [KNL] Mount root device read-only on boot
1611 root= [KNL] Root filesystem
1613 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1614 mount the root filesystem
1616 rootflags= [KNL] Set root filesystem mount option string
1618 rootfstype= [KNL] Set root filesystem type
1620 rootwait [KNL] Wait (indefinitely) for root device to show up.
1621 Useful for devices that are detected asynchronously
1622 (e.g. USB and MMC devices).
1624 root_plug.vendor_id=
1625 [ROOTPLUG] Override the default vendor ID
1627 root_plug.product_id=
1628 [ROOTPLUG] Override the default product ID
1630 root_plug.debug=
1631 [ROOTPLUG] Enable debugging output
1633 rw [KNL] Mount root device read-write on boot
1635 S [KNL] Run init in single mode
1637 sa1100ir [NET]
1638 See drivers/net/irda/sa1100_ir.c.
1640 sbni= [NET] Granch SBNI12 leased line adapter
1642 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1643 Format: <io>[,<timeout>[,<isapnp>]]
1645 scsi_debug_*= [SCSI]
1646 See drivers/scsi/scsi_debug.c.
1648 scsi_default_dev_flags=
1649 [SCSI] SCSI default device flags
1650 Format: <integer>
1652 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1653 Format: <vendor>:<model>:<flags>
1654 (flags are integer value)
1656 scsi_logging_level= [SCSI] a bit mask of logging levels
1657 See drivers/scsi/scsi_logging.h for bits. Also
1658 settable via sysctl at dev.scsi.logging_level
1659 (/proc/sys/dev/scsi/logging_level).
1660 There is also a nice 'scsi_logging_level' script in the
1661 S390-tools package, available for download at
1662 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1664 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1665 discovered. async scans them in kernel threads,
1666 allowing boot to proceed. none ignores them, expecting
1667 user space to do the scan.
1669 selinux [SELINUX] Disable or enable SELinux at boot time.
1670 Format: { "0" | "1" }
1671 See security/selinux/Kconfig help text.
1672 0 -- disable.
1673 1 -- enable.
1674 Default value is set via kernel config option.
1675 If enabled at boot time, /selinux/disable can be used
1676 later to disable prior to initial policy load.
1678 selinux_compat_net =
1679 [SELINUX] Set initial selinux_compat_net flag value.
1680 Format: { "0" | "1" }
1681 0 -- use new secmark-based packet controls
1682 1 -- use legacy packet controls
1683 Default value is 0 (preferred).
1684 Value can be changed at runtime via
1685 /selinux/compat_net.
1687 serialnumber [BUGS=X86-32]
1689 shapers= [NET]
1690 Maximal number of shapers.
1692 sim710= [SCSI,HW]
1693 See header of drivers/scsi/sim710.c.
1695 simeth= [IA-64]
1696 simscsi=
1698 slram= [HW,MTD]
1700 slub_debug[=options[,slabs]] [MM, SLUB]
1701 Enabling slub_debug allows one to determine the
1702 culprit if slab objects become corrupted. Enabling
1703 slub_debug can create guard zones around objects and
1704 may poison objects when not in use. Also tracks the
1705 last alloc / free. For more information see
1706 Documentation/vm/slub.txt.
1708 slub_max_order= [MM, SLUB]
1709 Determines the maximum allowed order for slabs.
1710 A high setting may cause OOMs due to memory
1711 fragmentation. For more information see
1712 Documentation/vm/slub.txt.
1714 slub_min_objects= [MM, SLUB]
1715 The minimum number of objects per slab. SLUB will
1716 increase the slab order up to slub_max_order to
1717 generate a sufficiently large slab able to contain
1718 the number of objects indicated. The higher the number
1719 of objects the smaller the overhead of tracking slabs
1720 and the less frequently locks need to be acquired.
1721 For more information see Documentation/vm/slub.txt.
1723 slub_min_order= [MM, SLUB]
1724 Determines the mininum page order for slabs. Must be
1725 lower than slub_max_order.
1726 For more information see Documentation/vm/slub.txt.
1728 slub_nomerge [MM, SLUB]
1729 Disable merging of slabs with similar size. May be
1730 necessary if there is some reason to distinguish
1731 allocs to different slabs. Debug options disable
1732 merging on their own.
1733 For more information see Documentation/vm/slub.txt.
1735 smart2= [HW]
1736 Format: <io1>[,<io2>[,...,<io8>]]
1738 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1739 attempt to substitute SMP alternatives once at boot.
1741 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1742 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1743 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1744 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1745 smsc-ircc2.ircc_irq= [HW] IRQ line
1746 smsc-ircc2.ircc_dma= [HW] DMA channel
1747 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1748 0: Toshiba Satellite 1800 (GP data pin select)
1749 1: Fast pin select (default)
1750 2: ATC IRMode
1752 snd-ad1816a= [HW,ALSA]
1754 snd-ad1848= [HW,ALSA]
1756 snd-ali5451= [HW,ALSA]
1758 snd-als100= [HW,ALSA]
1760 snd-als4000= [HW,ALSA]
1762 snd-azt2320= [HW,ALSA]
1764 snd-cmi8330= [HW,ALSA]
1766 snd-cmipci= [HW,ALSA]
1768 snd-cs4231= [HW,ALSA]
1770 snd-cs4232= [HW,ALSA]
1772 snd-cs4236= [HW,ALSA]
1774 snd-cs4281= [HW,ALSA]
1776 snd-cs46xx= [HW,ALSA]
1778 snd-dt019x= [HW,ALSA]
1780 snd-dummy= [HW,ALSA]
1782 snd-emu10k1= [HW,ALSA]
1784 snd-ens1370= [HW,ALSA]
1786 snd-ens1371= [HW,ALSA]
1788 snd-es968= [HW,ALSA]
1790 snd-es1688= [HW,ALSA]
1792 snd-es18xx= [HW,ALSA]
1794 snd-es1938= [HW,ALSA]
1796 snd-es1968= [HW,ALSA]
1798 snd-fm801= [HW,ALSA]
1800 snd-gusclassic= [HW,ALSA]
1802 snd-gusextreme= [HW,ALSA]
1804 snd-gusmax= [HW,ALSA]
1806 snd-hdsp= [HW,ALSA]
1808 snd-ice1712= [HW,ALSA]
1810 snd-intel8x0= [HW,ALSA]
1812 snd-interwave= [HW,ALSA]
1814 snd-interwave-stb=
1815 [HW,ALSA]
1817 snd-korg1212= [HW,ALSA]
1819 snd-maestro3= [HW,ALSA]
1821 snd-mpu401= [HW,ALSA]
1823 snd-mtpav= [HW,ALSA]
1825 snd-nm256= [HW,ALSA]
1827 snd-opl3sa2= [HW,ALSA]
1829 snd-opti92x-ad1848=
1830 [HW,ALSA]
1832 snd-opti92x-cs4231=
1833 [HW,ALSA]
1835 snd-opti93x= [HW,ALSA]
1837 snd-pmac= [HW,ALSA]
1839 snd-rme32= [HW,ALSA]
1841 snd-rme96= [HW,ALSA]
1843 snd-rme9652= [HW,ALSA]
1845 snd-sb8= [HW,ALSA]
1847 snd-sb16= [HW,ALSA]
1849 snd-sbawe= [HW,ALSA]
1851 snd-serial= [HW,ALSA]
1853 snd-sgalaxy= [HW,ALSA]
1855 snd-sonicvibes= [HW,ALSA]
1857 snd-sun-amd7930=
1858 [HW,ALSA]
1860 snd-sun-cs4231= [HW,ALSA]
1862 snd-trident= [HW,ALSA]
1864 snd-usb-audio= [HW,ALSA,USB]
1866 snd-via82xx= [HW,ALSA]
1868 snd-virmidi= [HW,ALSA]
1870 snd-wavefront= [HW,ALSA]
1872 snd-ymfpci= [HW,ALSA]
1874 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1875 See Documentation/sonypi.txt
1877 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1878 See Documentation/specialix.txt.
1880 spia_io_base= [HW,MTD]
1881 spia_fio_base=
1882 spia_pedr=
1883 spia_peddr=
1885 sscape= [HW,OSS]
1886 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1888 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1889 See Documentation/scsi/st.txt.
1891 st0x= [HW,SCSI]
1892 See header of drivers/scsi/seagate.c.
1894 sti= [PARISC,HW]
1895 Format: <num>
1896 Set the STI (builtin display/keyboard on the HP-PARISC
1897 machines) console (graphic card) which should be used
1898 as the initial boot-console.
1899 See also comment in drivers/video/console/sticore.c.
1901 sti_font= [HW]
1902 See comment in drivers/video/console/sticore.c.
1904 stifb= [HW]
1905 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1907 sunrpc.pool_mode=
1908 [NFS]
1909 Control how the NFS server code allocates CPUs to
1910 service thread pools. Depending on how many NICs
1911 you have and where their interrupts are bound, this
1912 option will affect which CPUs will do NFS serving.
1913 Note: this parameter cannot be changed while the
1914 NFS server is running.
1916 auto the server chooses an appropriate mode
1917 automatically using heuristics
1918 global a single global pool contains all CPUs
1919 percpu one pool for each CPU
1920 pernode one pool for each NUMA node (equivalent
1921 to global on non-NUMA machines)
1923 swiotlb= [IA-64] Number of I/O TLB slabs
1925 switches= [HW,M68k]
1927 sym53c416= [HW,SCSI]
1928 See header of drivers/scsi/sym53c416.c.
1930 sysrq_always_enabled
1931 [KNL]
1932 Ignore sysrq setting - this boot parameter will
1933 neutralize any effect of /proc/sys/kernel/sysrq.
1934 Useful for debugging.
1936 t128= [HW,SCSI]
1937 See header of drivers/scsi/t128.c.
1939 tdfx= [HW,DRM]
1941 thash_entries= [KNL,NET]
1942 Set number of hash buckets for TCP connection
1944 thermal.act= [HW,ACPI]
1945 -1: disable all active trip points in all thermal zones
1946 <degrees C>: override all lowest active trip points
1948 thermal.crt= [HW,ACPI]
1949 -1: disable all critical trip points in all thermal zones
1950 <degrees C>: lower all critical trip points
1952 thermal.nocrt= [HW,ACPI]
1953 Set to disable actions on ACPI thermal zone
1954 critical and hot trip points.
1956 thermal.off= [HW,ACPI]
1957 1: disable ACPI thermal control
1959 thermal.psv= [HW,ACPI]
1960 -1: disable all passive trip points
1961 <degrees C>: override all passive trip points to this value
1963 thermal.tzp= [HW,ACPI]
1964 Specify global default ACPI thermal zone polling rate
1965 <deci-seconds>: poll all this frequency
1966 0: no polling (default)
1968 time Show timing data prefixed to each printk message line
1969 [deprecated, see 'printk.time']
1971 tipar.timeout= [HW,PPT]
1972 Set communications timeout in tenths of a second
1973 (default 15).
1975 tipar.delay= [HW,PPT]
1976 Set inter-bit delay in microseconds (default 10).
1978 tmc8xx= [HW,SCSI]
1979 See header of drivers/scsi/seagate.c.
1981 tmscsim= [HW,SCSI]
1982 See comment before function dc390_setup() in
1983 drivers/scsi/tmscsim.c.
1985 tp720= [HW,PS2]
1987 trix= [HW,OSS] MediaTrix AudioTrix Pro
1988 Format:
1989 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1991 turbografx.map[2|3]= [HW,JOY]
1992 TurboGraFX parallel port interface
1993 Format:
1994 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1995 See also Documentation/input/joystick-parport.txt
1997 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1998 See header of drivers/scsi/u14-34f.c.
2000 uart401= [HW,OSS]
2001 Format: <io>,<irq>
2003 uart6850= [HW,OSS]
2004 Format: <io>,<irq>
2006 uhci-hcd.ignore_oc=
2007 [USB] Ignore overcurrent events (default N).
2008 Some badly-designed motherboards generate lots of
2009 bogus events, for ports that aren't wired to
2010 anything. Set this parameter to avoid log spamming.
2011 Note that genuine overcurrent events won't be
2012 reported either.
2014 usbcore.autosuspend=
2015 [USB] The autosuspend time delay (in seconds) used
2016 for newly-detected USB devices (default 2). This
2017 is the time required before an idle device will be
2018 autosuspended. Devices for which the delay is set
2019 to a negative value won't be autosuspended at all.
2021 usbhid.mousepoll=
2022 [USBHID] The interval which mice are to be polled at.
2024 vdso= [X86-32,SH,x86-64]
2025 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2026 vdso=1: enable VDSO (default)
2027 vdso=0: disable VDSO mapping
2029 vdso32= [X86-32,X86-64]
2030 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2031 vdso32=1: enable 32-bit VDSO (default)
2032 vdso32=0: disable 32-bit VDSO mapping
2034 vector= [IA-64,SMP]
2035 vector=percpu: enable percpu vector domain
2037 video= [FB] Frame buffer configuration
2038 See Documentation/fb/modedb.txt.
2040 vga= [BOOT,X86-32] Select a particular video mode
2041 See Documentation/i386/boot.txt and
2042 Documentation/svga.txt.
2043 Use vga=ask for menu.
2044 This is actually a boot loader parameter; the value is
2045 passed to the kernel using a special protocol.
2047 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2048 size of <nn>. This can be used to increase the
2049 minimum size (128MB on x86). It can also be used to
2050 decrease the size and leave more room for directly
2051 mapped kernel RAM.
2053 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2054 Format: <command>
2056 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2057 Format: <command>
2059 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2060 Format: <command>
2062 waveartist= [HW,OSS]
2063 Format: <io>,<irq>,<dma>,<dma2>
2065 wd33c93= [HW,SCSI]
2066 See header of drivers/scsi/wd33c93.c.
2068 wd7000= [HW,SCSI]
2069 See header of drivers/scsi/wd7000.c.
2071 wdt= [WDT] Watchdog
2072 See Documentation/watchdog/wdt.txt.
2074 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2075 xd_geo= See header of drivers/block/xd.c.
2077 xirc2ps_cs= [NET,PCMCIA]
2078 Format:
2079 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2081 norandmaps Don't use address space randomization
2082 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2084 ______________________________________________________________________
2086 TODO:
2088 Add documentation for ALSA options.
2089 Add more DRM drivers.