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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/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.addr= [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 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
784 Claim all unknown PCI IDE storage controllers.
786 ignore_loglevel [KNL]
787 Ignore loglevel setting - this will print /all/
788 kernel messages to the console. Useful for debugging.
790 ihash_entries= [KNL]
791 Set number of hash buckets for inode cache.
793 in2000= [HW,SCSI]
794 See header of drivers/scsi/in2000.c.
796 init= [KNL]
797 Format: <full_path>
798 Run specified binary instead of /sbin/init as init
799 process.
801 initcall_debug [KNL] Trace initcalls as they are executed. Useful
802 for working out where the kernel is dying during
803 startup.
805 initrd= [BOOT] Specify the location of the initial ramdisk
807 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
808 Format: <irq>
810 inttest= [IA64]
812 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
813 off
814 Disable intel iommu driver.
815 igfx_off [Default Off]
816 By default, gfx is mapped as normal device. If a gfx
817 device has a dedicated DMAR unit, the DMAR unit is
818 bypassed by not enabling DMAR with this option. In
819 this case, gfx device will use physical address for
820 DMA.
821 forcedac [x86_64]
822 With this option iommu will not optimize to look
823 for io virtual address below 32 bit forcing dual
824 address cycle on pci bus for cards supporting greater
825 than 32 bit addressing. The default is to look
826 for translation below 32 bit and if not available
827 then look in the higher range.
829 io_delay= [X86-32,X86-64] I/O delay method
830 0x80
831 Standard port 0x80 based delay
832 0xed
833 Alternate port 0xed based delay (needed on some systems)
834 udelay
835 Simple two microseconds delay
836 none
837 No delay
839 io7= [HW] IO7 for Marvel based alpha systems
840 See comment before marvel_specify_io7 in
841 arch/alpha/kernel/core_marvel.c.
843 ip= [IP_PNP]
844 See Documentation/nfsroot.txt.
846 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
847 See comment before ip2_setup() in
848 drivers/char/ip2/ip2base.c.
850 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
851 See header of drivers/scsi/ips.c.
853 ports= [IP_VS_FTP] IPVS ftp helper module
854 Default is 21.
855 Up to 8 (IP_VS_APP_MAX_PORTS) ports
856 may be specified.
857 Format: <port>,<port>....
859 irqfixup [HW]
860 When an interrupt is not handled search all handlers
861 for it. Intended to get systems with badly broken
862 firmware running.
864 irqpoll [HW]
865 When an interrupt is not handled search all handlers
866 for it. Also check all handlers each timer
867 interrupt. Intended to get systems with badly broken
868 firmware running.
870 isapnp= [ISAPNP]
871 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
873 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
874 Format:
875 <cpu number>,...,<cpu number>
876 or
877 <cpu number>-<cpu number> (must be a positive range in ascending order)
878 or a mixture
879 <cpu number>,...,<cpu number>-<cpu number>
880 This option can be used to specify one or more CPUs
881 to isolate from the general SMP balancing and scheduling
882 algorithms. The only way to move a process onto or off
883 an "isolated" CPU is via the CPU affinity syscalls.
884 <cpu number> begins at 0 and the maximum value is
885 "number of CPUs in system - 1".
887 This option is the preferred way to isolate CPUs. The
888 alternative -- manually setting the CPU mask of all
889 tasks in the system -- can cause problems and
890 suboptimal load balancer performance.
892 iucv= [HW,NET]
894 js= [HW,JOY] Analog joystick
895 See Documentation/input/joystick.txt.
897 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
898 specifies the amount of memory usable by the kernel
899 for non-movable allocations. The requested amount is
900 spread evenly throughout all nodes in the system. The
901 remaining memory in each node is used for Movable
902 pages. In the event, a node is too small to have both
903 kernelcore and Movable pages, kernelcore pages will
904 take priority and other nodes will have a larger number
905 of kernelcore pages. The Movable zone is used for the
906 allocation of pages that may be reclaimed or moved
907 by the page migration subsystem. This means that
908 HugeTLB pages may not be allocated from this zone.
909 Note that allocations like PTEs-from-HighMem still
910 use the HighMem zone if it exists, and the Normal
911 zone if it does not.
913 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
914 is similar to kernelcore except it specifies the
915 amount of memory used for migratable allocations.
916 If both kernelcore and movablecore is specified,
917 then kernelcore will be at *least* the specified
918 value but may be more. If movablecore on its own
919 is specified, the administrator must be careful
920 that the amount of memory usable for all allocations
921 is not too small.
923 keepinitrd [HW,ARM]
925 kstack=N [X86-32,X86-64] Print N words from the kernel stack
926 in oops dumps.
928 l2cr= [PPC]
930 lapic [X86-32,APIC] Enable the local APIC even if BIOS
931 disabled it.
933 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
934 C2 power state.
936 libata.dma= [LIBATA] DMA control
937 libata.dma=0 Disable all PATA and SATA DMA
938 libata.dma=1 PATA and SATA Disk DMA only
939 libata.dma=2 ATAPI (CDROM) DMA only
940 libata.dma=4 Compact Flash DMA only
941 Combinations also work, so libata.dma=3 enables DMA
942 for disks and CDROMs, but not CFs.
944 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
945 when set.
946 Format: <int>
948 load_ramdisk= [RAM] List of ramdisks to load from floppy
949 See Documentation/ramdisk.txt.
951 lockd.nlm_grace_period=P [NFS] Assign grace period.
952 Format: <integer>
954 lockd.nlm_tcpport=N [NFS] Assign TCP port.
955 Format: <integer>
957 lockd.nlm_timeout=T [NFS] Assign timeout value.
958 Format: <integer>
960 lockd.nlm_udpport=M [NFS] Assign UDP port.
961 Format: <integer>
963 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
964 Format: <irq>
966 loglevel= All Kernel Messages with a loglevel smaller than the
967 console loglevel will be printed to the console. It can
968 also be changed with klogd or other programs. The
969 loglevels are defined as follows:
971 0 (KERN_EMERG) system is unusable
972 1 (KERN_ALERT) action must be taken immediately
973 2 (KERN_CRIT) critical conditions
974 3 (KERN_ERR) error conditions
975 4 (KERN_WARNING) warning conditions
976 5 (KERN_NOTICE) normal but significant condition
977 6 (KERN_INFO) informational
978 7 (KERN_DEBUG) debug-level messages
980 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
981 Format: { n | nk | nM }
982 n must be a power of two. The default size
983 is set in the kernel config file.
985 logo.nologo [FB] Disables display of the built-in Linux logo.
986 This may be used to provide more screen space for
987 kernel log messages and is useful when debugging
988 kernel boot problems.
990 lp=0 [LP] Specify parallel ports to use, e.g,
991 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
992 lp=reset first parallel port). 'lp=0' disables the
993 lp=auto printer driver. 'lp=reset' (which can be
994 specified in addition to the ports) causes
995 attached printers to be reset. Using
996 lp=port1,port2,... specifies the parallel ports
997 to associate lp devices with, starting with
998 lp0. A port specification may be 'none' to skip
999 that lp device, or a parport name such as
1000 'parport0'. Specifying 'lp=auto' instead of a
1001 port specification list means that device IDs
1002 from each port should be examined, to see if
1003 an IEEE 1284-compliant printer is attached; if
1004 so, the driver will manage that printer.
1005 See also header of drivers/char/lp.c.
1007 lpj=n [KNL]
1008 Sets loops_per_jiffy to given constant, thus avoiding
1009 time-consuming boot-time autodetection (up to 250 ms per
1010 CPU). 0 enables autodetection (default). To determine
1011 the correct value for your kernel, boot with normal
1012 autodetection and see what value is printed. Note that
1013 on SMP systems the preset will be applied to all CPUs,
1014 which is likely to cause problems if your CPUs need
1015 significantly divergent settings. An incorrect value
1016 will cause delays in the kernel to be wrong, leading to
1017 unpredictable I/O errors and other breakage. Although
1018 unlikely, in the extreme case this might damage your
1019 hardware.
1021 ltpc= [NET]
1022 Format: <io>,<irq>,<dma>
1024 mac5380= [HW,SCSI] Format:
1025 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1027 mac53c9x= [HW,SCSI] Format:
1028 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1030 machvec= [IA64] Force the use of a particular machine-vector
1031 (machvec) in a generic kernel.
1032 Example: machvec=hpzx1_swiotlb
1034 max_loop= [LOOP] Maximum number of loopback devices that can
1035 be mounted
1036 Format: <1-256>
1038 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1039 should make use of. maxcpus=n : n >= 0 limits the
1040 kernel to using 'n' processors. n=0 is a special case,
1041 it is equivalent to "nosmp", which also disables
1042 the IO APIC.
1044 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1045 equal to this physical address is ignored.
1047 max_luns= [SCSI] Maximum number of LUNs to probe.
1048 Should be between 1 and 2^32-1.
1050 max_report_luns=
1051 [SCSI] Maximum number of LUNs received.
1052 Should be between 1 and 16384.
1054 mca-pentium [BUGS=X86-32]
1056 mcatest= [IA-64]
1058 mce [X86-32] Machine Check Exception
1060 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1062 md= [HW] RAID subsystems devices and level
1063 See Documentation/md.txt.
1065 mdacon= [MDA]
1066 Format: <first>,<last>
1067 Specifies range of consoles to be captured by the MDA.
1069 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1070 Amount of memory to be used when the kernel is not able
1071 to see the whole system memory or for test.
1072 [X86-32] Use together with memmap= to avoid physical
1073 address space collisions. Without memmap= PCI devices
1074 could be placed at addresses belonging to unused RAM.
1076 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1077 memory.
1079 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1080 E820 memory map, as specified by the user.
1081 Such memmap=exactmap lines can be constructed based on
1082 BIOS output or other requirements. See the memmap=nn@ss
1083 option description.
1085 memmap=nn[KMG]@ss[KMG]
1086 [KNL] Force usage of a specific region of memory
1087 Region of memory to be used, from ss to ss+nn.
1089 memmap=nn[KMG]#ss[KMG]
1090 [KNL,ACPI] Mark specific memory as ACPI data.
1091 Region of memory to be used, from ss to ss+nn.
1093 memmap=nn[KMG]$ss[KMG]
1094 [KNL,ACPI] Mark specific memory as reserved.
1095 Region of memory to be used, from ss to ss+nn.
1097 meye.*= [HW] Set MotionEye Camera parameters
1098 See Documentation/video4linux/meye.txt.
1100 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1101 Multi-Function General Purpose Timers on AMD Geode
1102 platforms.
1104 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1105 the BIOS has incorrectly applied a workaround. TinyBIOS
1106 version 0.98 is known to be affected, 0.99 fixes the
1107 problem by letting the user disable the workaround.
1109 mga= [HW,DRM]
1111 mousedev.tap_time=
1112 [MOUSE] Maximum time between finger touching and
1113 leaving touchpad surface for touch to be considered
1114 a tap and be reported as a left button click (for
1115 touchpads working in absolute mode only).
1116 Format: <msecs>
1117 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1118 reporting absolute coordinates, such as tablets
1119 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1120 reporting absolute coordinates, such as tablets
1122 mpu401= [HW,OSS]
1123 Format: <io>,<irq>
1125 MTD_Partition= [MTD]
1126 Format: <name>,<region-number>,<size>,<offset>
1128 MTD_Region= [MTD] Format:
1129 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1131 mtdparts= [MTD]
1132 See drivers/mtd/cmdlinepart.c.
1134 mtouchusb.raw_coordinates=
1135 [HW] Make the MicroTouch USB driver use raw coordinates
1136 ('y', default) or cooked coordinates ('n')
1138 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1140 NCR_D700= [HW,SCSI]
1141 See header of drivers/scsi/NCR_D700.c.
1143 ncr5380= [HW,SCSI]
1145 ncr53c400= [HW,SCSI]
1147 ncr53c400a= [HW,SCSI]
1149 ncr53c406a= [HW,SCSI]
1151 ncr53c8xx= [HW,SCSI]
1153 netdev= [NET] Network devices parameters
1154 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1155 Note that mem_start is often overloaded to mean
1156 something different and driver-specific.
1157 This usage is only documented in each driver source
1158 file if at all.
1160 nfsaddrs= [NFS]
1161 See Documentation/nfsroot.txt.
1163 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1164 See Documentation/nfsroot.txt.
1166 nfs.callback_tcpport=
1167 [NFS] set the TCP port on which the NFSv4 callback
1168 channel should listen.
1170 nfs.idmap_cache_timeout=
1171 [NFS] set the maximum lifetime for idmapper cache
1172 entries.
1174 nfs.enable_ino64=
1175 [NFS] enable 64-bit inode numbers.
1176 If zero, the NFS client will fake up a 32-bit inode
1177 number for the readdir() and stat() syscalls instead
1178 of returning the full 64-bit number.
1179 The default is to return 64-bit inode numbers.
1181 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1182 when a NMI is triggered.
1183 Format: [state][,regs][,debounce][,die]
1185 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1187 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1188 emulation library even if a 387 maths coprocessor
1189 is present.
1191 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1192 caches in the slab allocator. Saves per-node memory,
1193 but will impact performance.
1195 noalign [KNL,ARM]
1197 noapic [SMP,APIC] Tells the kernel to not make use of any
1198 IOAPICs that may be present in the system.
1200 nobats [PPC] Do not use BATs for mapping kernel lowmem
1201 on "Classic" PPC cores.
1203 nocache [ARM]
1205 nodelayacct [KNL] Disable per-task delay accounting
1207 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1209 noefi [X86-32,X86-64] Disable EFI runtime services support.
1211 noexec [IA-64]
1213 noexec [X86-32,X86-64]
1214 noexec=on: enable non-executable mappings (default)
1215 noexec=off: disable nn-executable mappings
1217 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1218 register save and restore. The kernel will only save
1219 legacy floating-point registers on task switch.
1221 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1223 nohlt [BUGS=ARM]
1225 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1226 instruction doesn't work correctly and not to
1227 use it.
1229 nohalt [IA-64] Tells the kernel not to use the power saving
1230 function PAL_HALT_LIGHT when idle. This increases
1231 power-consumption. On the positive side, it reduces
1232 interrupt wake-up latency, which may improve performance
1233 in certain environments such as networked servers or
1234 real-time systems.
1236 nohz= [KNL] Boottime enable/disable dynamic ticks
1237 Valid arguments: on, off
1238 Default: on
1240 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1242 noirqdebug [X86-32] Disables the code which attempts to detect and
1243 disable unhandled interrupt sources.
1245 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1246 broken timer IRQ sources.
1248 noisapnp [ISAPNP] Disables ISA PnP code.
1250 noinitrd [RAM] Tells the kernel not to load any configured
1251 initial RAM disk.
1253 nointroute [IA-64]
1255 nojitter [IA64] Disables jitter checking for ITC timers.
1257 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1259 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1261 noltlbs [PPC] Do not use large page/tlb entries for kernel
1262 lowmem mapping on PPC40x.
1264 nomca [IA-64] Disable machine check abort handling
1266 nomce [X86-32] Machine Check Exception
1268 nomfgpt [X86-32] Disable Multi-Function General Purpose
1269 Timer usage (for AMD Geode machines).
1271 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1273 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1274 with UP alternatives
1276 noresidual [PPC] Don't use residual data on PReP machines.
1278 noresume [SWSUSP] Disables resume and restores original swap
1279 space.
1281 no-scroll [VGA] Disables scrollback.
1282 This is required for the Braillex ib80-piezo Braille
1283 reader made by F.H. Papenmeier (Germany).
1285 nosbagart [IA-64]
1287 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1289 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1290 and disable the IO APIC. legacy for "maxcpus=0".
1292 nosoftlockup [KNL] Disable the soft-lockup detector.
1294 nosync [HW,M68K] Disables sync negotiation for all devices.
1296 notsc [BUGS=X86-32] Disable Time Stamp Counter
1298 nousb [USB] Disable the USB subsystem
1300 nowb [ARM]
1302 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1303 one of ['zone', 'node', 'default'] can be specified
1304 This can be set from sysctl after boot.
1305 See Documentation/sysctl/vm.txt for details.
1307 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1309 opl3= [HW,OSS]
1310 Format: <io>
1312 oprofile.timer= [HW]
1313 Use timer interrupt instead of performance counters
1315 osst= [HW,SCSI] SCSI Tape Driver
1316 Format: <buffer_size>,<write_threshold>
1317 See also Documentation/scsi/st.txt.
1319 panic= [KNL] Kernel behaviour on panic
1320 Format: <timeout>
1322 parkbd.port= [HW] Parallel port number the keyboard adapter is
1323 connected to, default is 0.
1324 Format: <parport#>
1325 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1326 0 for XT, 1 for AT (default is AT).
1327 Format: <mode>
1329 parport= [HW,PPT] Specify parallel ports. 0 disables.
1330 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1331 Use 'auto' to force the driver to use any
1332 IRQ/DMA settings detected (the default is to
1333 ignore detected IRQ/DMA settings because of
1334 possible conflicts). You can specify the base
1335 address, IRQ, and DMA settings; IRQ and DMA
1336 should be numbers, or 'auto' (for using detected
1337 settings on that particular port), or 'nofifo'
1338 (to avoid using a FIFO even if it is detected).
1339 Parallel ports are assigned in the order they
1340 are specified on the command line, starting
1341 with parport0.
1343 parport_init_mode= [HW,PPT]
1344 Configure VIA parallel port to operate in
1345 a specific mode. This is necessary on Pegasos
1346 computer where firmware has no options for setting
1347 up parallel port mode and sets it to spp.
1348 Currently this function knows 686a and 8231 chips.
1349 Format: [spp|ps2|epp|ecp|ecpepp]
1351 pas2= [HW,OSS] Format:
1352 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1354 pas16= [HW,SCSI]
1355 See header of drivers/scsi/pas16.c.
1357 pause_on_oops=
1358 Halt all CPUs after the first oops has been printed for
1359 the specified number of seconds. This is to be used if
1360 your oopses keep scrolling off the screen.
1362 pcbit= [HW,ISDN]
1364 pcd. [PARIDE]
1365 See header of drivers/block/paride/pcd.c.
1366 See also Documentation/paride.txt.
1368 pci=option[,option...] [PCI] various PCI subsystem options:
1369 off [X86-32] don't probe for the PCI bus
1370 bios [X86-32] force use of PCI BIOS, don't access
1371 the hardware directly. Use this if your machine
1372 has a non-standard PCI host bridge.
1373 nobios [X86-32] disallow use of PCI BIOS, only direct
1374 hardware access methods are allowed. Use this
1375 if you experience crashes upon bootup and you
1376 suspect they are caused by the BIOS.
1377 conf1 [X86-32] Force use of PCI Configuration
1378 Mechanism 1.
1379 conf2 [X86-32] Force use of PCI Configuration
1380 Mechanism 2.
1381 noaer [PCIE] If the PCIEAER kernel config parameter is
1382 enabled, this kernel boot option can be used to
1383 disable the use of PCIE advanced error reporting.
1384 nodomains [PCI] Disable support for multiple PCI
1385 root domains (aka PCI segments, in ACPI-speak).
1386 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1387 Configuration
1388 nomsi [MSI] If the PCI_MSI kernel config parameter is
1389 enabled, this kernel boot option can be used to
1390 disable the use of MSI interrupts system-wide.
1391 nosort [X86-32] Don't sort PCI devices according to
1392 order given by the PCI BIOS. This sorting is
1393 done to get a device order compatible with
1394 older kernels.
1395 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1396 routing table. These calls are known to be buggy
1397 on several machines and they hang the machine
1398 when used, but on other computers it's the only
1399 way to get the interrupt routing table. Try
1400 this option if the kernel is unable to allocate
1401 IRQs or discover secondary PCI buses on your
1402 motherboard.
1403 rom [X86-32] Assign address space to expansion ROMs.
1404 Use with caution as certain devices share
1405 address decoders between ROMs and other
1406 resources.
1407 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1408 assigned automatically to PCI devices. You can
1409 make the kernel exclude IRQs of your ISA cards
1410 this way.
1411 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1412 of the PIRQ table (normally generated
1413 by the BIOS) if it is outside the
1414 F0000h-100000h range.
1415 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1416 useful if the kernel is unable to find your
1417 secondary buses and you want to tell it
1418 explicitly which ones they are.
1419 assign-busses [X86-32] Always assign all PCI bus
1420 numbers ourselves, overriding
1421 whatever the firmware may have done.
1422 usepirqmask [X86-32] Honor the possible IRQ mask stored
1423 in the BIOS $PIR table. This is needed on
1424 some systems with broken BIOSes, notably
1425 some HP Pavilion N5400 and Omnibook XE3
1426 notebooks. This will have no effect if ACPI
1427 IRQ routing is enabled.
1428 noacpi [X86-32] Do not use ACPI for IRQ routing
1429 or for PCI scanning.
1430 use_crs [X86-32] Use _CRS for PCI resource
1431 allocation.
1432 routeirq Do IRQ routing for all PCI devices.
1433 This is normally done in pci_enable_device(),
1434 so this option is a temporary workaround
1435 for broken drivers that don't call it.
1436 firmware [ARM] Do not re-enumerate the bus but instead
1437 just use the configuration from the
1438 bootloader. This is currently used on
1439 IXP2000 systems where the bus has to be
1440 configured a certain way for adjunct CPUs.
1441 noearly [X86] Don't do any early type 1 scanning.
1442 This might help on some broken boards which
1443 machine check when some devices' config space
1444 is read. But various workarounds are disabled
1445 and some IOMMU drivers will not work.
1446 bfsort Sort PCI devices into breadth-first order.
1447 This sorting is done to get a device
1448 order compatible with older (<= 2.4) kernels.
1449 nobfsort Don't sort PCI devices into breadth-first order.
1450 cbiosize=nn[KMG] The fixed amount of bus space which is
1451 reserved for the CardBus bridge's IO window.
1452 The default value is 256 bytes.
1453 cbmemsize=nn[KMG] The fixed amount of bus space which is
1454 reserved for the CardBus bridge's memory
1455 window. The default value is 64 megabytes.
1457 pcmv= [HW,PCMCIA] BadgePAD 4
1459 pd. [PARIDE]
1460 See Documentation/paride.txt.
1462 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1463 boot time.
1464 Format: { 0 | 1 }
1465 See arch/parisc/kernel/pdc_chassis.c
1467 pf. [PARIDE]
1468 See Documentation/paride.txt.
1470 pg. [PARIDE]
1471 See Documentation/paride.txt.
1473 pirq= [SMP,APIC] Manual mp-table setup
1474 See Documentation/i386/IO-APIC.txt.
1476 plip= [PPT,NET] Parallel port network link
1477 Format: { parport<nr> | timid | 0 }
1478 See also Documentation/parport.txt.
1480 pnpacpi= [ACPI]
1481 { off }
1483 pnpbios= [ISAPNP]
1484 { on | off | curr | res | no-curr | no-res }
1486 pnp_reserve_irq=
1487 [ISAPNP] Exclude IRQs for the autoconfiguration
1489 pnp_reserve_dma=
1490 [ISAPNP] Exclude DMAs for the autoconfiguration
1492 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1493 Ranges are in pairs (I/O port base and size).
1495 pnp_reserve_mem=
1496 [ISAPNP] Exclude memory regions for the
1497 autoconfiguration.
1498 Ranges are in pairs (memory base and size).
1500 print-fatal-signals=
1501 [KNL] debug: print fatal signals
1502 print-fatal-signals=1: print segfault info to
1503 the kernel console.
1504 default: off.
1506 printk.time= Show timing data prefixed to each printk message line
1507 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1509 profile= [KNL] Enable kernel profiling via /proc/profile
1510 Format: [schedule,]<number>
1511 Param: "schedule" - profile schedule points.
1512 Param: <number> - step/bucket size as a power of 2 for
1513 statistical time based profiling.
1514 Param: "sleep" - profile D-state sleeping (millisecs).
1515 Requires CONFIG_SCHEDSTATS
1516 Param: "kvm" - profile VM exits.
1518 processor.max_cstate= [HW,ACPI]
1519 Limit processor to maximum C-state
1520 max_cstate=9 overrides any DMI blacklist limit.
1522 processor.nocst [HW,ACPI]
1523 Ignore the _CST method to determine C-states,
1524 instead using the legacy FADT method
1526 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1527 before loading.
1528 See Documentation/ramdisk.txt.
1530 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1531 probe for; one of (bare|imps|exps|lifebook|any).
1532 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1533 per second.
1534 psmouse.resetafter= [HW,MOUSE]
1535 Try to reset the device after so many bad packets
1536 (0 = never).
1537 psmouse.resolution=
1538 [HW,MOUSE] Set desired mouse resolution, in dpi.
1539 psmouse.smartscroll=
1540 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1541 0 = disabled, 1 = enabled (default).
1543 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1544 Format:
1545 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1547 pt. [PARIDE]
1548 See Documentation/paride.txt.
1550 pty.legacy_count=
1551 [KNL] Number of legacy pty's. Overwrites compiled-in
1552 default number.
1554 quiet [KNL] Disable most log messages
1556 r128= [HW,DRM]
1558 raid= [HW,RAID]
1559 See Documentation/md.txt.
1561 ramdisk_blocksize= [RAM]
1562 See Documentation/ramdisk.txt.
1564 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1565 See Documentation/ramdisk.txt.
1567 rcupdate.blimit= [KNL,BOOT]
1568 Set maximum number of finished RCU callbacks to process
1569 in one batch.
1571 rcupdate.qhimark= [KNL,BOOT]
1572 Set threshold of queued
1573 RCU callbacks over which batch limiting is disabled.
1575 rcupdate.qlowmark= [KNL,BOOT]
1576 Set threshold of queued RCU callbacks below which
1577 batch limiting is re-enabled.
1579 rdinit= [KNL]
1580 Format: <full_path>
1581 Run specified binary instead of /init from the ramdisk,
1582 used for early userspace startup. See initrd.
1584 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1585 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1586 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1588 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1590 reservetop= [X86-32]
1591 Format: nn[KMG]
1592 Reserves a hole at the top of the kernel virtual
1593 address space.
1595 reset_devices [KNL] Force drivers to reset the underlying device
1596 during initialization.
1598 resume= [SWSUSP]
1599 Specify the partition device for software suspend
1601 resume_offset= [SWSUSP]
1602 Specify the offset from the beginning of the partition
1603 given by "resume=" at which the swap header is located,
1604 in <PAGE_SIZE> units (needed only for swap files).
1605 See Documentation/power/swsusp-and-swap-files.txt
1607 retain_initrd [RAM] Keep initrd memory after extraction
1609 rhash_entries= [KNL,NET]
1610 Set number of hash buckets for route cache
1612 riscom8= [HW,SERIAL]
1613 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1615 ro [KNL] Mount root device read-only on boot
1617 root= [KNL] Root filesystem
1619 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1620 mount the root filesystem
1622 rootflags= [KNL] Set root filesystem mount option string
1624 rootfstype= [KNL] Set root filesystem type
1626 rootwait [KNL] Wait (indefinitely) for root device to show up.
1627 Useful for devices that are detected asynchronously
1628 (e.g. USB and MMC devices).
1630 root_plug.vendor_id=
1631 [ROOTPLUG] Override the default vendor ID
1633 root_plug.product_id=
1634 [ROOTPLUG] Override the default product ID
1636 root_plug.debug=
1637 [ROOTPLUG] Enable debugging output
1639 rw [KNL] Mount root device read-write on boot
1641 S [KNL] Run init in single mode
1643 sa1100ir [NET]
1644 See drivers/net/irda/sa1100_ir.c.
1646 sbni= [NET] Granch SBNI12 leased line adapter
1648 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1649 Format: <io>[,<timeout>[,<isapnp>]]
1651 scsi_debug_*= [SCSI]
1652 See drivers/scsi/scsi_debug.c.
1654 scsi_default_dev_flags=
1655 [SCSI] SCSI default device flags
1656 Format: <integer>
1658 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1659 Format: <vendor>:<model>:<flags>
1660 (flags are integer value)
1662 scsi_logging_level= [SCSI] a bit mask of logging levels
1663 See drivers/scsi/scsi_logging.h for bits. Also
1664 settable via sysctl at dev.scsi.logging_level
1665 (/proc/sys/dev/scsi/logging_level).
1666 There is also a nice 'scsi_logging_level' script in the
1667 S390-tools package, available for download at
1668 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1670 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1671 discovered. async scans them in kernel threads,
1672 allowing boot to proceed. none ignores them, expecting
1673 user space to do the scan.
1675 selinux [SELINUX] Disable or enable SELinux at boot time.
1676 Format: { "0" | "1" }
1677 See security/selinux/Kconfig help text.
1678 0 -- disable.
1679 1 -- enable.
1680 Default value is set via kernel config option.
1681 If enabled at boot time, /selinux/disable can be used
1682 later to disable prior to initial policy load.
1684 selinux_compat_net =
1685 [SELINUX] Set initial selinux_compat_net flag value.
1686 Format: { "0" | "1" }
1687 0 -- use new secmark-based packet controls
1688 1 -- use legacy packet controls
1689 Default value is 0 (preferred).
1690 Value can be changed at runtime via
1691 /selinux/compat_net.
1693 serialnumber [BUGS=X86-32]
1695 shapers= [NET]
1696 Maximal number of shapers.
1698 sim710= [SCSI,HW]
1699 See header of drivers/scsi/sim710.c.
1701 simeth= [IA-64]
1702 simscsi=
1704 slram= [HW,MTD]
1706 slub_debug[=options[,slabs]] [MM, SLUB]
1707 Enabling slub_debug allows one to determine the
1708 culprit if slab objects become corrupted. Enabling
1709 slub_debug can create guard zones around objects and
1710 may poison objects when not in use. Also tracks the
1711 last alloc / free. For more information see
1712 Documentation/vm/slub.txt.
1714 slub_max_order= [MM, SLUB]
1715 Determines the maximum allowed order for slabs.
1716 A high setting may cause OOMs due to memory
1717 fragmentation. For more information see
1718 Documentation/vm/slub.txt.
1720 slub_min_objects= [MM, SLUB]
1721 The minimum number of objects per slab. SLUB will
1722 increase the slab order up to slub_max_order to
1723 generate a sufficiently large slab able to contain
1724 the number of objects indicated. The higher the number
1725 of objects the smaller the overhead of tracking slabs
1726 and the less frequently locks need to be acquired.
1727 For more information see Documentation/vm/slub.txt.
1729 slub_min_order= [MM, SLUB]
1730 Determines the mininum page order for slabs. Must be
1731 lower than slub_max_order.
1732 For more information see Documentation/vm/slub.txt.
1734 slub_nomerge [MM, SLUB]
1735 Disable merging of slabs with similar size. May be
1736 necessary if there is some reason to distinguish
1737 allocs to different slabs. Debug options disable
1738 merging on their own.
1739 For more information see Documentation/vm/slub.txt.
1741 smart2= [HW]
1742 Format: <io1>[,<io2>[,...,<io8>]]
1744 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1745 attempt to substitute SMP alternatives once at boot.
1747 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1748 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1749 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1750 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1751 smsc-ircc2.ircc_irq= [HW] IRQ line
1752 smsc-ircc2.ircc_dma= [HW] DMA channel
1753 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1754 0: Toshiba Satellite 1800 (GP data pin select)
1755 1: Fast pin select (default)
1756 2: ATC IRMode
1758 snd-ad1816a= [HW,ALSA]
1760 snd-ad1848= [HW,ALSA]
1762 snd-ali5451= [HW,ALSA]
1764 snd-als100= [HW,ALSA]
1766 snd-als4000= [HW,ALSA]
1768 snd-azt2320= [HW,ALSA]
1770 snd-cmi8330= [HW,ALSA]
1772 snd-cmipci= [HW,ALSA]
1774 snd-cs4231= [HW,ALSA]
1776 snd-cs4232= [HW,ALSA]
1778 snd-cs4236= [HW,ALSA]
1780 snd-cs4281= [HW,ALSA]
1782 snd-cs46xx= [HW,ALSA]
1784 snd-dt019x= [HW,ALSA]
1786 snd-dummy= [HW,ALSA]
1788 snd-emu10k1= [HW,ALSA]
1790 snd-ens1370= [HW,ALSA]
1792 snd-ens1371= [HW,ALSA]
1794 snd-es968= [HW,ALSA]
1796 snd-es1688= [HW,ALSA]
1798 snd-es18xx= [HW,ALSA]
1800 snd-es1938= [HW,ALSA]
1802 snd-es1968= [HW,ALSA]
1804 snd-fm801= [HW,ALSA]
1806 snd-gusclassic= [HW,ALSA]
1808 snd-gusextreme= [HW,ALSA]
1810 snd-gusmax= [HW,ALSA]
1812 snd-hdsp= [HW,ALSA]
1814 snd-ice1712= [HW,ALSA]
1816 snd-intel8x0= [HW,ALSA]
1818 snd-interwave= [HW,ALSA]
1820 snd-interwave-stb=
1821 [HW,ALSA]
1823 snd-korg1212= [HW,ALSA]
1825 snd-maestro3= [HW,ALSA]
1827 snd-mpu401= [HW,ALSA]
1829 snd-mtpav= [HW,ALSA]
1831 snd-nm256= [HW,ALSA]
1833 snd-opl3sa2= [HW,ALSA]
1835 snd-opti92x-ad1848=
1836 [HW,ALSA]
1838 snd-opti92x-cs4231=
1839 [HW,ALSA]
1841 snd-opti93x= [HW,ALSA]
1843 snd-pmac= [HW,ALSA]
1845 snd-rme32= [HW,ALSA]
1847 snd-rme96= [HW,ALSA]
1849 snd-rme9652= [HW,ALSA]
1851 snd-sb8= [HW,ALSA]
1853 snd-sb16= [HW,ALSA]
1855 snd-sbawe= [HW,ALSA]
1857 snd-serial= [HW,ALSA]
1859 snd-sgalaxy= [HW,ALSA]
1861 snd-sonicvibes= [HW,ALSA]
1863 snd-sun-amd7930=
1864 [HW,ALSA]
1866 snd-sun-cs4231= [HW,ALSA]
1868 snd-trident= [HW,ALSA]
1870 snd-usb-audio= [HW,ALSA,USB]
1872 snd-via82xx= [HW,ALSA]
1874 snd-virmidi= [HW,ALSA]
1876 snd-wavefront= [HW,ALSA]
1878 snd-ymfpci= [HW,ALSA]
1880 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1881 See Documentation/sonypi.txt
1883 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1884 See Documentation/specialix.txt.
1886 spia_io_base= [HW,MTD]
1887 spia_fio_base=
1888 spia_pedr=
1889 spia_peddr=
1891 sscape= [HW,OSS]
1892 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1894 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1895 See Documentation/scsi/st.txt.
1897 sti= [PARISC,HW]
1898 Format: <num>
1899 Set the STI (builtin display/keyboard on the HP-PARISC
1900 machines) console (graphic card) which should be used
1901 as the initial boot-console.
1902 See also comment in drivers/video/console/sticore.c.
1904 sti_font= [HW]
1905 See comment in drivers/video/console/sticore.c.
1907 stifb= [HW]
1908 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1910 sunrpc.pool_mode=
1911 [NFS]
1912 Control how the NFS server code allocates CPUs to
1913 service thread pools. Depending on how many NICs
1914 you have and where their interrupts are bound, this
1915 option will affect which CPUs will do NFS serving.
1916 Note: this parameter cannot be changed while the
1917 NFS server is running.
1919 auto the server chooses an appropriate mode
1920 automatically using heuristics
1921 global a single global pool contains all CPUs
1922 percpu one pool for each CPU
1923 pernode one pool for each NUMA node (equivalent
1924 to global on non-NUMA machines)
1926 swiotlb= [IA-64] Number of I/O TLB slabs
1928 switches= [HW,M68k]
1930 sym53c416= [HW,SCSI]
1931 See header of drivers/scsi/sym53c416.c.
1933 sysrq_always_enabled
1934 [KNL]
1935 Ignore sysrq setting - this boot parameter will
1936 neutralize any effect of /proc/sys/kernel/sysrq.
1937 Useful for debugging.
1939 t128= [HW,SCSI]
1940 See header of drivers/scsi/t128.c.
1942 tdfx= [HW,DRM]
1944 thash_entries= [KNL,NET]
1945 Set number of hash buckets for TCP connection
1947 thermal.act= [HW,ACPI]
1948 -1: disable all active trip points in all thermal zones
1949 <degrees C>: override all lowest active trip points
1951 thermal.crt= [HW,ACPI]
1952 -1: disable all critical trip points in all thermal zones
1953 <degrees C>: lower all critical trip points
1955 thermal.nocrt= [HW,ACPI]
1956 Set to disable actions on ACPI thermal zone
1957 critical and hot trip points.
1959 thermal.off= [HW,ACPI]
1960 1: disable ACPI thermal control
1962 thermal.psv= [HW,ACPI]
1963 -1: disable all passive trip points
1964 <degrees C>: override all passive trip points to this value
1966 thermal.tzp= [HW,ACPI]
1967 Specify global default ACPI thermal zone polling rate
1968 <deci-seconds>: poll all this frequency
1969 0: no polling (default)
1971 time Show timing data prefixed to each printk message line
1972 [deprecated, see 'printk.time']
1974 tipar.timeout= [HW,PPT]
1975 Set communications timeout in tenths of a second
1976 (default 15).
1978 tipar.delay= [HW,PPT]
1979 Set inter-bit delay in microseconds (default 10).
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.