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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_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
173 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
174 Format: To spoof as Windows 98: ="Microsoft Windows"
176 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
177 acpi_osi="string1" # add string1 -- only one string
178 acpi_osi="!string2" # remove built-in string2
179 acpi_osi= # disable all strings
181 acpi_serialize [HW,ACPI] force serialization of AML methods
183 acpi_skip_timer_override [HW,ACPI]
184 Recognize and ignore IRQ0/pin2 Interrupt Override.
185 For broken nForce2 BIOS resulting in XT-PIC timer.
186 acpi_use_timer_override [HW,ACPI}
187 Use timer override. For some broken Nvidia NF5 boards
188 that require a timer override, but don't have
189 HPET
191 acpi.debug_layer= [HW,ACPI]
192 Format: <int>
193 Each bit of the <int> indicates an ACPI debug layer,
194 1: enable, 0: disable. It is useful for boot time
195 debugging. After system has booted up, it can be set
196 via /sys/module/acpi/parameters/debug_layer.
197 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
198 Available bits (add the numbers together) to enable debug output
199 for specific parts of the ACPI subsystem:
200 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
201 0x10 namespace 0x20 parser 0x40 dispatcher
202 0x80 executer 0x100 resources 0x200 acpica debugger
203 0x400 os services 0x800 acpica disassembler.
204 The number can be in decimal or prefixed with 0x in hex.
205 Warning: Many of these options can produce a lot of
206 output and make your system unusable. Be very careful.
208 acpi.debug_level= [HW,ACPI]
209 Format: <int>
210 Each bit of the <int> indicates an ACPI debug level,
211 1: enable, 0: disable. It is useful for boot time
212 debugging. After system has booted up, it can be set
213 via /sys/module/acpi/parameters/debug_level.
214 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
215 Available bits (add the numbers together) to enable different
216 debug output levels of the ACPI subsystem:
217 0x01 error 0x02 warn 0x04 init 0x08 debug object
218 0x10 info 0x20 init names 0x40 parse 0x80 load
219 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
220 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
221 0x10000 resources 0x20000 user requests 0x40000 package.
222 The number can be in decimal or prefixed with 0x in hex.
223 Warning: Many of these options can produce a lot of
224 output and make your system unusable. Be very careful.
226 acpi_pm_good [X86-32,X86-64]
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
231 agp= [AGP]
232 { off | try_unsupported }
233 off: disable AGP support
234 try_unsupported: try to drive unsupported chipsets
235 (may crash computer or cause data corruption)
237 enable_timer_pin_1 [i386,x86-64]
238 Enable PIN 1 of APIC timer
239 Can be useful to work around chipset bugs
240 (in particular on some ATI chipsets).
241 The kernel tries to set a reasonable default.
243 disable_timer_pin_1 [i386,x86-64]
244 Disable PIN 1 of APIC timer
245 Can be useful to work around chipset bugs.
247 ad1848= [HW,OSS]
248 Format: <io>,<irq>,<dma>,<dma2>,<type>
250 advansys= [HW,SCSI]
251 See header of drivers/scsi/advansys.c.
253 advwdt= [HW,WDT] Advantech WDT
254 Format: <iostart>,<iostop>
256 aedsp16= [HW,OSS] Audio Excel DSP 16
257 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
258 See also header of sound/oss/aedsp16.c.
260 aha152x= [HW,SCSI]
261 See Documentation/scsi/aha152x.txt.
263 aha1542= [HW,SCSI]
264 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
266 aic7xxx= [HW,SCSI]
267 See Documentation/scsi/aic7xxx.txt.
269 aic79xx= [HW,SCSI]
270 See Documentation/scsi/aic79xx.txt.
272 amijoy.map= [HW,JOY] Amiga joystick support
273 Map of devices attached to JOY0DAT and JOY1DAT
274 Format: <a>,<b>
275 See also Documentation/kernel/input/joystick.txt
277 analog.map= [HW,JOY] Analog joystick and gamepad support
278 Specifies type or capabilities of an analog joystick
279 connected to one of 16 gameports
280 Format: <type1>,<type2>,..<type16>
282 apc= [HW,SPARC]
283 Power management functions (SPARCstation-4/5 + deriv.)
284 Format: noidle
285 Disable APC CPU standby support. SPARCstation-Fox does
286 not play well with APC CPU idle - disable it if you have
287 APC and your system crashes randomly.
289 apic= [APIC,i386] Advanced Programmable Interrupt Controller
290 Change the output verbosity whilst booting
291 Format: { quiet (default) | verbose | debug }
292 Change the amount of debugging information output
293 when initialising the APIC and IO-APIC components.
295 apm= [APM] Advanced Power Management
296 See header of arch/i386/kernel/apm.c.
298 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
299 Format: <io>,<irq>,<nodeID>
301 ataflop= [HW,M68k]
303 atarimouse= [HW,MOUSE] Atari Mouse
305 atascsi= [HW,SCSI] Atari SCSI
307 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
308 EzKey and similar keyboards
310 atkbd.reset= [HW] Reset keyboard during initialization
312 atkbd.set= [HW] Select keyboard code set
313 Format: <int> (2 = AT (default), 3 = PS/2)
315 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
316 keyboards
318 atkbd.softraw= [HW] Choose between synthetic and real raw mode
319 Format: <bool> (0 = real, 1 = synthetic (default))
321 atkbd.softrepeat= [HW]
322 Use software keyboard repeat
324 autotest [IA64]
326 baycom_epp= [HW,AX25]
327 Format: <io>,<mode>
329 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
330 Format: <io>,<mode>
331 See header of drivers/net/hamradio/baycom_par.c.
333 baycom_ser_fdx= [HW,AX25]
334 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
335 Format: <io>,<irq>,<mode>[,<baud>]
336 See header of drivers/net/hamradio/baycom_ser_fdx.c.
338 baycom_ser_hdx= [HW,AX25]
339 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
340 Format: <io>,<irq>,<mode>
341 See header of drivers/net/hamradio/baycom_ser_hdx.c.
343 boot_delay= Milliseconds to delay each printk during boot.
344 Values larger than 10 seconds (10000) are changed to
345 no delay (0).
346 Format: integer
348 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
349 bttv.radio= Most important insmod options are available as
350 kernel args too.
351 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
352 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
354 BusLogic= [HW,SCSI]
355 See drivers/scsi/BusLogic.c, comment before function
356 BusLogic_ParseDriverOptions().
358 c101= [NET] Moxa C101 synchronous serial card
360 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
361 Sometimes CPU hardware bugs make them report the cache
362 size incorrectly. The kernel will attempt work arounds
363 to fix known problems, but for some CPUs it is not
364 possible to determine what the correct size should be.
365 This option provides an override for these situations.
367 capability.disable=
368 [SECURITY] Disable capabilities. This would normally
369 be used only if an alternative security model is to be
370 configured. Potentially dangerous and should only be
371 used if you are entirely sure of the consequences.
373 ccw_timeout_log [S390]
374 See Documentation/s390/CommonIO for details.
376 checkreqprot [SELINUX] Set initial checkreqprot flag value.
377 Format: { "0" | "1" }
378 See security/selinux/Kconfig help text.
379 0 -- check protection applied by kernel (includes
380 any implied execute protection).
381 1 -- check protection requested by application.
382 Default value is set via a kernel config option.
383 Value can be changed at runtime via
384 /selinux/checkreqprot.
386 cio_ignore= [S390]
387 See Documentation/s390/CommonIO for details.
389 cio_msg= [S390]
390 See Documentation/s390/CommonIO for details.
392 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
393 [Deprecated]
394 Forces specified clocksource (if available) to be used
395 when calculating gettimeofday(). If specified
396 clocksource is not available, it defaults to PIT.
397 Format: { pit | tsc | cyclone | pmtmr }
399 clocksource= [GENERIC_TIME] Override the default clocksource
400 Format: <string>
401 Override the default clocksource and use the clocksource
402 with the name specified.
403 Some clocksource names to choose from, depending on
404 the platform:
405 [all] jiffies (this is the base, fallback clocksource)
406 [ACPI] acpi_pm
407 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
408 pxa_timer,timer3,32k_counter,timer0_1
409 [AVR32] avr32
410 [X86-32] pit,hpet,tsc,vmi-timer;
411 scx200_hrt on Geode; cyclone on IBM x440
412 [MIPS] MIPS
413 [PARISC] cr16
414 [S390] tod
415 [SH] SuperH
416 [SPARC64] tick
417 [X86-64] hpet,tsc
419 code_bytes [IA32/X86_64] How many bytes of object code to print
420 in an oops report.
421 Range: 0 - 8192
422 Default: 64
424 disable_8254_timer
425 enable_8254_timer
426 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
427 over the 8254 in addition to over the IO-APIC. The
428 kernel tries to set a sensible default.
430 hpet= [X86-32,HPET] option to control HPET usage
431 Format: { enable (default) | disable | force }
432 disable: disable HPET and use PIT instead
433 force: allow force enabled of undocumented chips (ICH4,
434 VIA, nVidia)
436 com20020= [HW,NET] ARCnet - COM20020 chipset
437 Format:
438 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
440 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
441 Format: <io>[,<irq>]
443 com90xx= [HW,NET]
444 ARCnet - COM90xx chipset (memory-mapped buffers)
445 Format: <io>[,<irq>[,<memstart>]]
447 condev= [HW,S390] console device
448 conmode=
450 console= [KNL] Output console device and options.
452 tty<n> Use the virtual console device <n>.
454 ttyS<n>[,options]
455 ttyUSB0[,options]
456 Use the specified serial port. The options are of
457 the form "bbbbpnf", where "bbbb" is the baud rate,
458 "p" is parity ("n", "o", or "e"), "n" is number of
459 bits, and "f" is flow control ("r" for RTS or
460 omit it). Default is "9600n8".
462 See Documentation/serial-console.txt for more
463 information. See
464 Documentation/networking/netconsole.txt for an
465 alternative.
467 uart[8250],io,<addr>[,options]
468 uart[8250],mmio,<addr>[,options]
469 Start an early, polled-mode console on the 8250/16550
470 UART at the specified I/O port or MMIO address,
471 switching to the matching ttyS device later. The
472 options are the same as for ttyS, above.
474 earlycon= [KNL] Output early console device and options.
475 uart[8250],io,<addr>[,options]
476 uart[8250],mmio,<addr>[,options]
477 Start an early, polled-mode console on the 8250/16550
478 UART at the specified I/O port or MMIO address.
479 The options are the same as for ttyS, above.
481 no_console_suspend
482 [HW] Never suspend the console
483 Disable suspending of consoles during suspend and
484 hibernate operations. Once disabled, debugging
485 messages can reach various consoles while the rest
486 of the system is being put to sleep (ie, while
487 debugging driver suspend/resume hooks). This may
488 not work reliably with all consoles, but is known
489 to work with serial and VGA consoles.
491 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
492 Format:
493 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
495 crashkernel=nn[KMG]@ss[KMG]
496 [KNL] Reserve a chunk of physical memory to
497 hold a kernel to switch to with kexec on panic.
499 crashkernel=range1:size1[,range2:size2,...][@offset]
500 [KNL] Same as above, but depends on the memory
501 in the running system. The syntax of range is
502 start-[end] where start and end are both
503 a memory unit (amount[KMG]). See also
504 Documentation/kdump/kdump.txt for a example.
506 cs4232= [HW,OSS]
507 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
509 cs89x0_dma= [HW,NET]
510 Format: <dma>
512 cs89x0_media= [HW,NET]
513 Format: { rj45 | aui | bnc }
515 dasd= [HW,NET]
516 See header of drivers/s390/block/dasd_devmap.c.
518 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
519 (one device per port)
520 Format: <port#>,<type>
521 See also Documentation/input/joystick-parport.txt
523 debug [KNL] Enable kernel debugging (events log level).
525 debug_locks_verbose=
526 [KNL] verbose self-tests
527 Format=<0|1>
528 Print debugging info while doing the locking API
529 self-tests.
530 We default to 0 (no extra messages), setting it to
531 1 will print _a lot_ more information - normally
532 only useful to kernel developers.
534 decnet= [HW,NET]
535 Format: <area>[,<node>]
536 See also Documentation/networking/decnet.txt.
538 vt.default_blu= [VT]
539 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
540 Change the default blue palette of the console.
541 This is a 16-member array composed of values
542 ranging from 0-255.
544 vt.default_grn= [VT]
545 Format: <green0>,<green1>,<green2>,...,<green15>
546 Change the default green palette of the console.
547 This is a 16-member array composed of values
548 ranging from 0-255.
550 vt.default_red= [VT]
551 Format: <red0>,<red1>,<red2>,...,<red15>
552 Change the default red palette of the console.
553 This is a 16-member array composed of values
554 ranging from 0-255.
556 vt.default_utf8=
557 [VT]
558 Format=<0|1>
559 Set system-wide default UTF-8 mode for all tty's.
560 Default is 1, i.e. UTF-8 mode is enabled for all
561 newly opened terminals.
563 dhash_entries= [KNL]
564 Set number of hash buckets for dentry cache.
566 digi= [HW,SERIAL]
567 IO parameters + enable/disable command.
569 digiepca= [HW,SERIAL]
570 See drivers/char/README.epca and
571 Documentation/digiepca.txt.
573 dmasound= [HW,OSS] Sound subsystem buffers
575 dscc4.setup= [NET]
577 dtc3181e= [HW,SCSI]
579 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
580 earlyprintk=vga
581 earlyprintk=serial[,ttySn[,baudrate]]
583 Append ",keep" to not disable it when the real console
584 takes over.
586 Only vga or serial at a time, not both.
588 Currently only ttyS0 and ttyS1 are supported.
590 Interaction with the standard serial driver is not
591 very good.
593 The VGA output is eventually overwritten by the real
594 console.
596 eata= [HW,SCSI]
598 edd= [EDD]
599 Format: {"of[f]" | "sk[ipmbr]"}
600 See comment in arch/i386/boot/edd.S
602 eisa_irq_edge= [PARISC,HW]
603 See header of drivers/parisc/eisa.c.
605 elanfreq= [X86-32]
606 See comment before function elanfreq_setup() in
607 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
609 elevator= [IOSCHED]
610 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
611 See Documentation/block/as-iosched.txt and
612 Documentation/block/deadline-iosched.txt for details.
614 elfcorehdr= [X86-32, X86_64]
615 Specifies physical address of start of kernel core
616 image elf header. Generally kexec loader will
617 pass this option to capture kernel.
618 See Documentation/kdump/kdump.txt for details.
620 enforcing [SELINUX] Set initial enforcing status.
621 Format: {"0" | "1"}
622 See security/selinux/Kconfig help text.
623 0 -- permissive (log only, no denials).
624 1 -- enforcing (deny and log).
625 Default value is 0.
626 Value can be changed at runtime via /selinux/enforce.
628 es1371= [HW,OSS]
629 Format: <spdif>,[<nomix>,[<amplifier>]]
630 See also header of sound/oss/es1371.c.
632 ether= [HW,NET] Ethernet cards parameters
633 This option is obsoleted by the "netdev=" option, which
634 has equivalent usage. See its documentation for details.
636 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
637 Format: <io>[,<irq>]
639 failslab=
640 fail_page_alloc=
641 fail_make_request=[KNL]
642 General fault injection mechanism.
643 Format: <interval>,<probability>,<space>,<times>
644 See also /Documentation/fault-injection/.
646 fd_mcs= [HW,SCSI]
647 See header of drivers/scsi/fd_mcs.c.
649 fdomain= [HW,SCSI]
650 See header of drivers/scsi/fdomain.c.
652 floppy= [HW]
653 See Documentation/floppy.txt.
655 gamecon.map[2|3]=
656 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
657 support via parallel port (up to 5 devices per port)
658 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
659 See also Documentation/input/joystick-parport.txt
661 gamma= [HW,DRM]
663 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
664 Format: off | on
665 default: on
667 gdth= [HW,SCSI]
668 See header of drivers/scsi/gdth.c.
670 gpt [EFI] Forces disk with valid GPT signature but
671 invalid Protective MBR to be treated as GPT.
673 gvp11= [HW,SCSI]
675 hashdist= [KNL,NUMA] Large hashes allocated during boot
676 are distributed across NUMA nodes. Defaults on
677 for IA-64, off otherwise.
678 Format: 0 | 1 (for off | on)
680 hcl= [IA-64] SGI's Hardware Graph compatibility layer
682 hd= [EIDE] (E)IDE hard drive subsystem geometry
683 Format: <cyl>,<head>,<sect>
685 hd?= [HW] (E)IDE subsystem
686 hd?lun= See Documentation/ide.txt.
688 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
689 size of <nn>. This works even on boxes that have no
690 highmem otherwise. This also works to reduce highmem
691 size on bigger boxes.
693 highres= [KNL] Enable/disable high resolution timer mode.
694 Valid parameters: "on", "off"
695 Default: "on"
697 hisax= [HW,ISDN]
698 See Documentation/isdn/README.HiSax.
700 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
702 i8042.direct [HW] Put keyboard port into non-translated mode
703 i8042.dumbkbd [HW] Pretend that controller can only read data from
704 keyboard and cannot control its state
705 (Don't attempt to blink the leds)
706 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
707 i8042.nokbd [HW] Don't check/create keyboard port
708 i8042.nomux [HW] Don't check presence of an active multiplexing
709 controller
710 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
711 controllers
712 i8042.panicblink=
713 [HW] Frequency with which keyboard LEDs should blink
714 when kernel panics (default is 0.5 sec)
715 i8042.reset [HW] Reset the controller during init and cleanup
716 i8042.unlock [HW] Unlock (ignore) the keylock
718 i810= [HW,DRM]
720 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
721 indicates that the driver is running on unsupported
722 hardware.
723 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
724 does not match list of supported models.
725 i8k.power_status
726 [HW] Report power status in /proc/i8k
727 (disabled by default)
728 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
729 capability is set.
731 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
732 See Documentation/mca.txt.
734 icn= [HW,ISDN]
735 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
737 ide= [HW] (E)IDE subsystem
738 Format: ide=nodma or ide=doubler or ide=reverse
739 See Documentation/ide.txt.
741 ide?= [HW] (E)IDE subsystem
742 Format: ide?=noprobe or chipset specific parameters.
743 See Documentation/ide.txt.
745 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
746 See Documentation/ide.txt.
748 idle= [X86]
749 Format: idle=poll or idle=mwait
750 Poll forces a polling idle loop that can slightly improves the performance
751 of waking up a idle CPU, but will use a lot of power and make the system
752 run hot. Not recommended.
753 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
754 to not use it because it doesn't save as much power as a normal idle
755 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
756 as idle=poll.
758 ignore_loglevel [KNL]
759 Ignore loglevel setting - this will print /all/
760 kernel messages to the console. Useful for debugging.
762 ihash_entries= [KNL]
763 Set number of hash buckets for inode cache.
765 in2000= [HW,SCSI]
766 See header of drivers/scsi/in2000.c.
768 init= [KNL]
769 Format: <full_path>
770 Run specified binary instead of /sbin/init as init
771 process.
773 initcall_debug [KNL] Trace initcalls as they are executed. Useful
774 for working out where the kernel is dying during
775 startup.
777 initrd= [BOOT] Specify the location of the initial ramdisk
779 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
780 Format: <irq>
782 inttest= [IA64]
784 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
785 off
786 Disable intel iommu driver.
787 igfx_off [Default Off]
788 By default, gfx is mapped as normal device. If a gfx
789 device has a dedicated DMAR unit, the DMAR unit is
790 bypassed by not enabling DMAR with this option. In
791 this case, gfx device will use physical address for
792 DMA.
793 forcedac [x86_64]
794 With this option iommu will not optimize to look
795 for io virtual address below 32 bit forcing dual
796 address cycle on pci bus for cards supporting greater
797 than 32 bit addressing. The default is to look
798 for translation below 32 bit and if not available
799 then look in the higher range.
801 io_delay= [X86-32,X86-64] I/O delay method
802 0x80
803 Standard port 0x80 based delay
804 0xed
805 Alternate port 0xed based delay (needed on some systems)
806 udelay
807 Simple two microseconds delay
808 none
809 No delay
811 io7= [HW] IO7 for Marvel based alpha systems
812 See comment before marvel_specify_io7 in
813 arch/alpha/kernel/core_marvel.c.
815 ip= [IP_PNP]
816 See Documentation/nfsroot.txt.
818 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
819 See comment before ip2_setup() in
820 drivers/char/ip2/ip2base.c.
822 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
823 See header of drivers/scsi/ips.c.
825 ports= [IP_VS_FTP] IPVS ftp helper module
826 Default is 21.
827 Up to 8 (IP_VS_APP_MAX_PORTS) ports
828 may be specified.
829 Format: <port>,<port>....
831 irqfixup [HW]
832 When an interrupt is not handled search all handlers
833 for it. Intended to get systems with badly broken
834 firmware running.
836 irqpoll [HW]
837 When an interrupt is not handled search all handlers
838 for it. Also check all handlers each timer
839 interrupt. Intended to get systems with badly broken
840 firmware running.
842 isapnp= [ISAPNP]
843 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
845 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
846 Format:
847 <cpu number>,...,<cpu number>
848 or
849 <cpu number>-<cpu number> (must be a positive range in ascending order)
850 or a mixture
851 <cpu number>,...,<cpu number>-<cpu number>
852 This option can be used to specify one or more CPUs
853 to isolate from the general SMP balancing and scheduling
854 algorithms. The only way to move a process onto or off
855 an "isolated" CPU is via the CPU affinity syscalls.
856 <cpu number> begins at 0 and the maximum value is
857 "number of CPUs in system - 1".
859 This option is the preferred way to isolate CPUs. The
860 alternative -- manually setting the CPU mask of all
861 tasks in the system -- can cause problems and
862 suboptimal load balancer performance.
864 iucv= [HW,NET]
866 js= [HW,JOY] Analog joystick
867 See Documentation/input/joystick.txt.
869 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
870 specifies the amount of memory usable by the kernel
871 for non-movable allocations. The requested amount is
872 spread evenly throughout all nodes in the system. The
873 remaining memory in each node is used for Movable
874 pages. In the event, a node is too small to have both
875 kernelcore and Movable pages, kernelcore pages will
876 take priority and other nodes will have a larger number
877 of kernelcore pages. The Movable zone is used for the
878 allocation of pages that may be reclaimed or moved
879 by the page migration subsystem. This means that
880 HugeTLB pages may not be allocated from this zone.
881 Note that allocations like PTEs-from-HighMem still
882 use the HighMem zone if it exists, and the Normal
883 zone if it does not.
885 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
886 is similar to kernelcore except it specifies the
887 amount of memory used for migratable allocations.
888 If both kernelcore and movablecore is specified,
889 then kernelcore will be at *least* the specified
890 value but may be more. If movablecore on its own
891 is specified, the administrator must be careful
892 that the amount of memory usable for all allocations
893 is not too small.
895 keepinitrd [HW,ARM]
897 kstack=N [X86-32,X86-64] Print N words from the kernel stack
898 in oops dumps.
900 l2cr= [PPC]
902 lapic [X86-32,APIC] Enable the local APIC even if BIOS
903 disabled it.
905 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
906 C2 power state.
908 libata.dma= [LIBATA] DMA control
909 libata.dma=0 Disable all PATA and SATA DMA
910 libata.dma=1 PATA and SATA Disk DMA only
911 libata.dma=2 ATAPI (CDROM) DMA only
912 libata.dma=4 Compact Flash DMA only
913 Combinations also work, so libata.dma=3 enables DMA
914 for disks and CDROMs, but not CFs.
916 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
917 when set.
918 Format: <int>
920 load_ramdisk= [RAM] List of ramdisks to load from floppy
921 See Documentation/ramdisk.txt.
923 lockd.nlm_grace_period=P [NFS] Assign grace period.
924 Format: <integer>
926 lockd.nlm_tcpport=N [NFS] Assign TCP port.
927 Format: <integer>
929 lockd.nlm_timeout=T [NFS] Assign timeout value.
930 Format: <integer>
932 lockd.nlm_udpport=M [NFS] Assign UDP port.
933 Format: <integer>
935 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
936 Format: <irq>
938 loglevel= All Kernel Messages with a loglevel smaller than the
939 console loglevel will be printed to the console. It can
940 also be changed with klogd or other programs. The
941 loglevels are defined as follows:
943 0 (KERN_EMERG) system is unusable
944 1 (KERN_ALERT) action must be taken immediately
945 2 (KERN_CRIT) critical conditions
946 3 (KERN_ERR) error conditions
947 4 (KERN_WARNING) warning conditions
948 5 (KERN_NOTICE) normal but significant condition
949 6 (KERN_INFO) informational
950 7 (KERN_DEBUG) debug-level messages
952 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
953 Format: { n | nk | nM }
954 n must be a power of two. The default size
955 is set in the kernel config file.
957 logo.nologo [FB] Disables display of the built-in Linux logo.
958 This may be used to provide more screen space for
959 kernel log messages and is useful when debugging
960 kernel boot problems.
962 lp=0 [LP] Specify parallel ports to use, e.g,
963 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
964 lp=reset first parallel port). 'lp=0' disables the
965 lp=auto printer driver. 'lp=reset' (which can be
966 specified in addition to the ports) causes
967 attached printers to be reset. Using
968 lp=port1,port2,... specifies the parallel ports
969 to associate lp devices with, starting with
970 lp0. A port specification may be 'none' to skip
971 that lp device, or a parport name such as
972 'parport0'. Specifying 'lp=auto' instead of a
973 port specification list means that device IDs
974 from each port should be examined, to see if
975 an IEEE 1284-compliant printer is attached; if
976 so, the driver will manage that printer.
977 See also header of drivers/char/lp.c.
979 lpj=n [KNL]
980 Sets loops_per_jiffy to given constant, thus avoiding
981 time-consuming boot-time autodetection (up to 250 ms per
982 CPU). 0 enables autodetection (default). To determine
983 the correct value for your kernel, boot with normal
984 autodetection and see what value is printed. Note that
985 on SMP systems the preset will be applied to all CPUs,
986 which is likely to cause problems if your CPUs need
987 significantly divergent settings. An incorrect value
988 will cause delays in the kernel to be wrong, leading to
989 unpredictable I/O errors and other breakage. Although
990 unlikely, in the extreme case this might damage your
991 hardware.
993 ltpc= [NET]
994 Format: <io>,<irq>,<dma>
996 mac5380= [HW,SCSI] Format:
997 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
999 mac53c9x= [HW,SCSI] Format:
1000 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1002 machvec= [IA64] Force the use of a particular machine-vector
1003 (machvec) in a generic kernel.
1004 Example: machvec=hpzx1_swiotlb
1006 max_loop= [LOOP] Maximum number of loopback devices that can
1007 be mounted
1008 Format: <1-256>
1010 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1011 should make use of. maxcpus=n : n >= 0 limits the
1012 kernel to using 'n' processors. n=0 is a special case,
1013 it is equivalent to "nosmp", which also disables
1014 the IO APIC.
1016 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1017 equal to this physical address is ignored.
1019 max_luns= [SCSI] Maximum number of LUNs to probe.
1020 Should be between 1 and 2^32-1.
1022 max_report_luns=
1023 [SCSI] Maximum number of LUNs received.
1024 Should be between 1 and 16384.
1026 mca-pentium [BUGS=X86-32]
1028 mcatest= [IA-64]
1030 mce [X86-32] Machine Check Exception
1032 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1034 md= [HW] RAID subsystems devices and level
1035 See Documentation/md.txt.
1037 mdacon= [MDA]
1038 Format: <first>,<last>
1039 Specifies range of consoles to be captured by the MDA.
1041 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1042 Amount of memory to be used when the kernel is not able
1043 to see the whole system memory or for test.
1044 [X86-32] Use together with memmap= to avoid physical
1045 address space collisions. Without memmap= PCI devices
1046 could be placed at addresses belonging to unused RAM.
1048 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1049 memory.
1051 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1052 E820 memory map, as specified by the user.
1053 Such memmap=exactmap lines can be constructed based on
1054 BIOS output or other requirements. See the memmap=nn@ss
1055 option description.
1057 memmap=nn[KMG]@ss[KMG]
1058 [KNL] Force usage of a specific region of memory
1059 Region of memory to be used, from ss to ss+nn.
1061 memmap=nn[KMG]#ss[KMG]
1062 [KNL,ACPI] Mark specific memory as ACPI data.
1063 Region of memory to be used, from ss to ss+nn.
1065 memmap=nn[KMG]$ss[KMG]
1066 [KNL,ACPI] Mark specific memory as reserved.
1067 Region of memory to be used, from ss to ss+nn.
1069 meye.*= [HW] Set MotionEye Camera parameters
1070 See Documentation/video4linux/meye.txt.
1072 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1073 Multi-Function General Purpose Timers on AMD Geode
1074 platforms.
1076 mga= [HW,DRM]
1078 mousedev.tap_time=
1079 [MOUSE] Maximum time between finger touching and
1080 leaving touchpad surface for touch to be considered
1081 a tap and be reported as a left button click (for
1082 touchpads working in absolute mode only).
1083 Format: <msecs>
1084 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1085 reporting absolute coordinates, such as tablets
1086 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1087 reporting absolute coordinates, such as tablets
1089 mpu401= [HW,OSS]
1090 Format: <io>,<irq>
1092 MTD_Partition= [MTD]
1093 Format: <name>,<region-number>,<size>,<offset>
1095 MTD_Region= [MTD] Format:
1096 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1098 mtdparts= [MTD]
1099 See drivers/mtd/cmdlinepart.c.
1101 mtouchusb.raw_coordinates=
1102 [HW] Make the MicroTouch USB driver use raw coordinates
1103 ('y', default) or cooked coordinates ('n')
1105 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1107 NCR_D700= [HW,SCSI]
1108 See header of drivers/scsi/NCR_D700.c.
1110 ncr5380= [HW,SCSI]
1112 ncr53c400= [HW,SCSI]
1114 ncr53c400a= [HW,SCSI]
1116 ncr53c406a= [HW,SCSI]
1118 ncr53c8xx= [HW,SCSI]
1120 netdev= [NET] Network devices parameters
1121 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1122 Note that mem_start is often overloaded to mean
1123 something different and driver-specific.
1124 This usage is only documented in each driver source
1125 file if at all.
1127 nfsaddrs= [NFS]
1128 See Documentation/nfsroot.txt.
1130 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1131 See Documentation/nfsroot.txt.
1133 nfs.callback_tcpport=
1134 [NFS] set the TCP port on which the NFSv4 callback
1135 channel should listen.
1137 nfs.idmap_cache_timeout=
1138 [NFS] set the maximum lifetime for idmapper cache
1139 entries.
1141 nfs.enable_ino64=
1142 [NFS] enable 64-bit inode numbers.
1143 If zero, the NFS client will fake up a 32-bit inode
1144 number for the readdir() and stat() syscalls instead
1145 of returning the full 64-bit number.
1146 The default is to return 64-bit inode numbers.
1148 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1149 when a NMI is triggered.
1150 Format: [state][,regs][,debounce][,die]
1152 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1154 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1155 emulation library even if a 387 maths coprocessor
1156 is present.
1158 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1159 caches in the slab allocator. Saves per-node memory,
1160 but will impact performance.
1162 noalign [KNL,ARM]
1164 noapic [SMP,APIC] Tells the kernel to not make use of any
1165 IOAPICs that may be present in the system.
1167 nobats [PPC] Do not use BATs for mapping kernel lowmem
1168 on "Classic" PPC cores.
1170 nocache [ARM]
1172 nodelayacct [KNL] Disable per-task delay accounting
1174 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1176 noefi [X86-32,X86-64] Disable EFI runtime services support.
1178 noexec [IA-64]
1180 noexec [X86-32,X86-64]
1181 noexec=on: enable non-executable mappings (default)
1182 noexec=off: disable nn-executable mappings
1184 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1185 register save and restore. The kernel will only save
1186 legacy floating-point registers on task switch.
1188 nohlt [BUGS=ARM]
1190 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1191 instruction doesn't work correctly and not to
1192 use it.
1194 nohalt [IA-64] Tells the kernel not to use the power saving
1195 function PAL_HALT_LIGHT when idle. This increases
1196 power-consumption. On the positive side, it reduces
1197 interrupt wake-up latency, which may improve performance
1198 in certain environments such as networked servers or
1199 real-time systems.
1201 nohz= [KNL] Boottime enable/disable dynamic ticks
1202 Valid arguments: on, off
1203 Default: on
1205 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1207 noirqdebug [X86-32] Disables the code which attempts to detect and
1208 disable unhandled interrupt sources.
1210 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1211 broken timer IRQ sources.
1213 noisapnp [ISAPNP] Disables ISA PnP code.
1215 noinitrd [RAM] Tells the kernel not to load any configured
1216 initial RAM disk.
1218 nointroute [IA-64]
1220 nojitter [IA64] Disables jitter checking for ITC timers.
1222 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1224 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1226 noltlbs [PPC] Do not use large page/tlb entries for kernel
1227 lowmem mapping on PPC40x.
1229 nomca [IA-64] Disable machine check abort handling
1231 nomce [X86-32] Machine Check Exception
1233 nomfgpt [X86-32] Disable Multi-Function General Purpose
1234 Timer usage (for AMD Geode machines).
1236 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1238 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1239 with UP alternatives
1241 noresidual [PPC] Don't use residual data on PReP machines.
1243 noresume [SWSUSP] Disables resume and restores original swap
1244 space.
1246 no-scroll [VGA] Disables scrollback.
1247 This is required for the Braillex ib80-piezo Braille
1248 reader made by F.H. Papenmeier (Germany).
1250 nosbagart [IA-64]
1252 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1254 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1255 and disable the IO APIC. legacy for "maxcpus=0".
1257 nosoftlockup [KNL] Disable the soft-lockup detector.
1259 nosync [HW,M68K] Disables sync negotiation for all devices.
1261 notsc [BUGS=X86-32] Disable Time Stamp Counter
1263 nousb [USB] Disable the USB subsystem
1265 nowb [ARM]
1267 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1268 one of ['zone', 'node', 'default'] can be specified
1269 This can be set from sysctl after boot.
1270 See Documentation/sysctl/vm.txt for details.
1272 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1274 opl3= [HW,OSS]
1275 Format: <io>
1277 oprofile.timer= [HW]
1278 Use timer interrupt instead of performance counters
1280 osst= [HW,SCSI] SCSI Tape Driver
1281 Format: <buffer_size>,<write_threshold>
1282 See also Documentation/scsi/st.txt.
1284 panic= [KNL] Kernel behaviour on panic
1285 Format: <timeout>
1287 parkbd.port= [HW] Parallel port number the keyboard adapter is
1288 connected to, default is 0.
1289 Format: <parport#>
1290 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1291 0 for XT, 1 for AT (default is AT).
1292 Format: <mode>
1294 parport= [HW,PPT] Specify parallel ports. 0 disables.
1295 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1296 Use 'auto' to force the driver to use any
1297 IRQ/DMA settings detected (the default is to
1298 ignore detected IRQ/DMA settings because of
1299 possible conflicts). You can specify the base
1300 address, IRQ, and DMA settings; IRQ and DMA
1301 should be numbers, or 'auto' (for using detected
1302 settings on that particular port), or 'nofifo'
1303 (to avoid using a FIFO even if it is detected).
1304 Parallel ports are assigned in the order they
1305 are specified on the command line, starting
1306 with parport0.
1308 parport_init_mode= [HW,PPT]
1309 Configure VIA parallel port to operate in
1310 a specific mode. This is necessary on Pegasos
1311 computer where firmware has no options for setting
1312 up parallel port mode and sets it to spp.
1313 Currently this function knows 686a and 8231 chips.
1314 Format: [spp|ps2|epp|ecp|ecpepp]
1316 pas2= [HW,OSS] Format:
1317 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1319 pas16= [HW,SCSI]
1320 See header of drivers/scsi/pas16.c.
1322 pause_on_oops=
1323 Halt all CPUs after the first oops has been printed for
1324 the specified number of seconds. This is to be used if
1325 your oopses keep scrolling off the screen.
1327 pcbit= [HW,ISDN]
1329 pcd. [PARIDE]
1330 See header of drivers/block/paride/pcd.c.
1331 See also Documentation/paride.txt.
1333 pci=option[,option...] [PCI] various PCI subsystem options:
1334 off [X86-32] don't probe for the PCI bus
1335 bios [X86-32] force use of PCI BIOS, don't access
1336 the hardware directly. Use this if your machine
1337 has a non-standard PCI host bridge.
1338 nobios [X86-32] disallow use of PCI BIOS, only direct
1339 hardware access methods are allowed. Use this
1340 if you experience crashes upon bootup and you
1341 suspect they are caused by the BIOS.
1342 conf1 [X86-32] Force use of PCI Configuration
1343 Mechanism 1.
1344 conf2 [X86-32] Force use of PCI Configuration
1345 Mechanism 2.
1346 noaer [PCIE] If the PCIEAER kernel config parameter is
1347 enabled, this kernel boot option can be used to
1348 disable the use of PCIE advanced error reporting.
1349 nodomains [PCI] Disable support for multiple PCI
1350 root domains (aka PCI segments, in ACPI-speak).
1351 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1352 Configuration
1353 nomsi [MSI] If the PCI_MSI kernel config parameter is
1354 enabled, this kernel boot option can be used to
1355 disable the use of MSI interrupts system-wide.
1356 nosort [X86-32] Don't sort PCI devices according to
1357 order given by the PCI BIOS. This sorting is
1358 done to get a device order compatible with
1359 older kernels.
1360 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1361 routing table. These calls are known to be buggy
1362 on several machines and they hang the machine
1363 when used, but on other computers it's the only
1364 way to get the interrupt routing table. Try
1365 this option if the kernel is unable to allocate
1366 IRQs or discover secondary PCI buses on your
1367 motherboard.
1368 rom [X86-32] Assign address space to expansion ROMs.
1369 Use with caution as certain devices share
1370 address decoders between ROMs and other
1371 resources.
1372 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1373 assigned automatically to PCI devices. You can
1374 make the kernel exclude IRQs of your ISA cards
1375 this way.
1376 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1377 of the PIRQ table (normally generated
1378 by the BIOS) if it is outside the
1379 F0000h-100000h range.
1380 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1381 useful if the kernel is unable to find your
1382 secondary buses and you want to tell it
1383 explicitly which ones they are.
1384 assign-busses [X86-32] Always assign all PCI bus
1385 numbers ourselves, overriding
1386 whatever the firmware may have done.
1387 usepirqmask [X86-32] Honor the possible IRQ mask stored
1388 in the BIOS $PIR table. This is needed on
1389 some systems with broken BIOSes, notably
1390 some HP Pavilion N5400 and Omnibook XE3
1391 notebooks. This will have no effect if ACPI
1392 IRQ routing is enabled.
1393 noacpi [X86-32] Do not use ACPI for IRQ routing
1394 or for PCI scanning.
1395 use_crs [X86-32] Use _CRS for PCI resource
1396 allocation.
1397 routeirq Do IRQ routing for all PCI devices.
1398 This is normally done in pci_enable_device(),
1399 so this option is a temporary workaround
1400 for broken drivers that don't call it.
1401 firmware [ARM] Do not re-enumerate the bus but instead
1402 just use the configuration from the
1403 bootloader. This is currently used on
1404 IXP2000 systems where the bus has to be
1405 configured a certain way for adjunct CPUs.
1406 noearly [X86] Don't do any early type 1 scanning.
1407 This might help on some broken boards which
1408 machine check when some devices' config space
1409 is read. But various workarounds are disabled
1410 and some IOMMU drivers will not work.
1411 bfsort Sort PCI devices into breadth-first order.
1412 This sorting is done to get a device
1413 order compatible with older (<= 2.4) kernels.
1414 nobfsort Don't sort PCI devices into breadth-first order.
1415 cbiosize=nn[KMG] The fixed amount of bus space which is
1416 reserved for the CardBus bridge's IO window.
1417 The default value is 256 bytes.
1418 cbmemsize=nn[KMG] The fixed amount of bus space which is
1419 reserved for the CardBus bridge's memory
1420 window. The default value is 64 megabytes.
1422 pcmv= [HW,PCMCIA] BadgePAD 4
1424 pd. [PARIDE]
1425 See Documentation/paride.txt.
1427 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1428 boot time.
1429 Format: { 0 | 1 }
1430 See arch/parisc/kernel/pdc_chassis.c
1432 pf. [PARIDE]
1433 See Documentation/paride.txt.
1435 pg. [PARIDE]
1436 See Documentation/paride.txt.
1438 pirq= [SMP,APIC] Manual mp-table setup
1439 See Documentation/i386/IO-APIC.txt.
1441 plip= [PPT,NET] Parallel port network link
1442 Format: { parport<nr> | timid | 0 }
1443 See also Documentation/parport.txt.
1445 pnpacpi= [ACPI]
1446 { off }
1448 pnpbios= [ISAPNP]
1449 { on | off | curr | res | no-curr | no-res }
1451 pnp_reserve_irq=
1452 [ISAPNP] Exclude IRQs for the autoconfiguration
1454 pnp_reserve_dma=
1455 [ISAPNP] Exclude DMAs for the autoconfiguration
1457 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1458 Ranges are in pairs (I/O port base and size).
1460 pnp_reserve_mem=
1461 [ISAPNP] Exclude memory regions for the
1462 autoconfiguration.
1463 Ranges are in pairs (memory base and size).
1465 print-fatal-signals=
1466 [KNL] debug: print fatal signals
1467 print-fatal-signals=1: print segfault info to
1468 the kernel console.
1469 default: off.
1471 printk.time= Show timing data prefixed to each printk message line
1472 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1474 profile= [KNL] Enable kernel profiling via /proc/profile
1475 Format: [schedule,]<number>
1476 Param: "schedule" - profile schedule points.
1477 Param: <number> - step/bucket size as a power of 2 for
1478 statistical time based profiling.
1479 Param: "sleep" - profile D-state sleeping (millisecs).
1480 Requires CONFIG_SCHEDSTATS
1481 Param: "kvm" - profile VM exits.
1483 processor.max_cstate= [HW,ACPI]
1484 Limit processor to maximum C-state
1485 max_cstate=9 overrides any DMI blacklist limit.
1487 processor.nocst [HW,ACPI]
1488 Ignore the _CST method to determine C-states,
1489 instead using the legacy FADT method
1491 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1492 before loading.
1493 See Documentation/ramdisk.txt.
1495 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1496 probe for; one of (bare|imps|exps|lifebook|any).
1497 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1498 per second.
1499 psmouse.resetafter= [HW,MOUSE]
1500 Try to reset the device after so many bad packets
1501 (0 = never).
1502 psmouse.resolution=
1503 [HW,MOUSE] Set desired mouse resolution, in dpi.
1504 psmouse.smartscroll=
1505 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1506 0 = disabled, 1 = enabled (default).
1508 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1509 Format:
1510 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1512 pt. [PARIDE]
1513 See Documentation/paride.txt.
1515 pty.legacy_count=
1516 [KNL] Number of legacy pty's. Overwrites compiled-in
1517 default number.
1519 quiet [KNL] Disable most log messages
1521 r128= [HW,DRM]
1523 raid= [HW,RAID]
1524 See Documentation/md.txt.
1526 ramdisk_blocksize= [RAM]
1527 See Documentation/ramdisk.txt.
1529 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1530 See Documentation/ramdisk.txt.
1532 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1533 RCU callbacks to process in one batch.
1535 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1536 RCU callbacks over which batch limiting is disabled.
1538 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1539 RCU callbacks below which batch limiting is re-enabled.
1541 rdinit= [KNL]
1542 Format: <full_path>
1543 Run specified binary instead of /init from the ramdisk,
1544 used for early userspace startup. See initrd.
1546 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1547 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1548 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1550 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1552 reservetop= [X86-32]
1553 Format: nn[KMG]
1554 Reserves a hole at the top of the kernel virtual
1555 address space.
1557 reset_devices [KNL] Force drivers to reset the underlying device
1558 during initialization.
1560 resume= [SWSUSP]
1561 Specify the partition device for software suspend
1563 resume_offset= [SWSUSP]
1564 Specify the offset from the beginning of the partition
1565 given by "resume=" at which the swap header is located,
1566 in <PAGE_SIZE> units (needed only for swap files).
1567 See Documentation/power/swsusp-and-swap-files.txt
1569 retain_initrd [RAM] Keep initrd memory after extraction
1571 rhash_entries= [KNL,NET]
1572 Set number of hash buckets for route cache
1574 riscom8= [HW,SERIAL]
1575 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1577 ro [KNL] Mount root device read-only on boot
1579 root= [KNL] Root filesystem
1581 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1582 mount the root filesystem
1584 rootflags= [KNL] Set root filesystem mount option string
1586 rootfstype= [KNL] Set root filesystem type
1588 rootwait [KNL] Wait (indefinitely) for root device to show up.
1589 Useful for devices that are detected asynchronously
1590 (e.g. USB and MMC devices).
1592 root_plug.vendor_id=
1593 [ROOTPLUG] Override the default vendor ID
1595 root_plug.product_id=
1596 [ROOTPLUG] Override the default product ID
1598 root_plug.debug=
1599 [ROOTPLUG] Enable debugging output
1601 rw [KNL] Mount root device read-write on boot
1603 S [KNL] Run init in single mode
1605 sa1100ir [NET]
1606 See drivers/net/irda/sa1100_ir.c.
1608 sbni= [NET] Granch SBNI12 leased line adapter
1610 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1611 Format: <io>[,<timeout>[,<isapnp>]]
1613 scsi_debug_*= [SCSI]
1614 See drivers/scsi/scsi_debug.c.
1616 scsi_default_dev_flags=
1617 [SCSI] SCSI default device flags
1618 Format: <integer>
1620 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1621 Format: <vendor>:<model>:<flags>
1622 (flags are integer value)
1624 scsi_logging_level= [SCSI] a bit mask of logging levels
1625 See drivers/scsi/scsi_logging.h for bits. Also
1626 settable via sysctl at dev.scsi.logging_level
1627 (/proc/sys/dev/scsi/logging_level).
1628 There is also a nice 'scsi_logging_level' script in the
1629 S390-tools package, available for download at
1630 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1632 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1633 discovered. async scans them in kernel threads,
1634 allowing boot to proceed. none ignores them, expecting
1635 user space to do the scan.
1637 selinux [SELINUX] Disable or enable SELinux at boot time.
1638 Format: { "0" | "1" }
1639 See security/selinux/Kconfig help text.
1640 0 -- disable.
1641 1 -- enable.
1642 Default value is set via kernel config option.
1643 If enabled at boot time, /selinux/disable can be used
1644 later to disable prior to initial policy load.
1646 selinux_compat_net =
1647 [SELINUX] Set initial selinux_compat_net flag value.
1648 Format: { "0" | "1" }
1649 0 -- use new secmark-based packet controls
1650 1 -- use legacy packet controls
1651 Default value is 0 (preferred).
1652 Value can be changed at runtime via
1653 /selinux/compat_net.
1655 serialnumber [BUGS=X86-32]
1657 shapers= [NET]
1658 Maximal number of shapers.
1660 sim710= [SCSI,HW]
1661 See header of drivers/scsi/sim710.c.
1663 simeth= [IA-64]
1664 simscsi=
1666 slram= [HW,MTD]
1668 slub_debug[=options[,slabs]] [MM, SLUB]
1669 Enabling slub_debug allows one to determine the
1670 culprit if slab objects become corrupted. Enabling
1671 slub_debug can create guard zones around objects and
1672 may poison objects when not in use. Also tracks the
1673 last alloc / free. For more information see
1674 Documentation/vm/slub.txt.
1676 slub_max_order= [MM, SLUB]
1677 Determines the maximum allowed order for slabs.
1678 A high setting may cause OOMs due to memory
1679 fragmentation. For more information see
1680 Documentation/vm/slub.txt.
1682 slub_min_objects= [MM, SLUB]
1683 The minimum number of objects per slab. SLUB will
1684 increase the slab order up to slub_max_order to
1685 generate a sufficiently large slab able to contain
1686 the number of objects indicated. The higher the number
1687 of objects the smaller the overhead of tracking slabs
1688 and the less frequently locks need to be acquired.
1689 For more information see Documentation/vm/slub.txt.
1691 slub_min_order= [MM, SLUB]
1692 Determines the mininum page order for slabs. Must be
1693 lower than slub_max_order.
1694 For more information see Documentation/vm/slub.txt.
1696 slub_nomerge [MM, SLUB]
1697 Disable merging of slabs with similar size. May be
1698 necessary if there is some reason to distinguish
1699 allocs to different slabs. Debug options disable
1700 merging on their own.
1701 For more information see Documentation/vm/slub.txt.
1703 smart2= [HW]
1704 Format: <io1>[,<io2>[,...,<io8>]]
1706 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1707 attempt to substitute SMP alternatives once at boot.
1709 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1710 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1711 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1712 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1713 smsc-ircc2.ircc_irq= [HW] IRQ line
1714 smsc-ircc2.ircc_dma= [HW] DMA channel
1715 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1716 0: Toshiba Satellite 1800 (GP data pin select)
1717 1: Fast pin select (default)
1718 2: ATC IRMode
1720 snd-ad1816a= [HW,ALSA]
1722 snd-ad1848= [HW,ALSA]
1724 snd-ali5451= [HW,ALSA]
1726 snd-als100= [HW,ALSA]
1728 snd-als4000= [HW,ALSA]
1730 snd-azt2320= [HW,ALSA]
1732 snd-cmi8330= [HW,ALSA]
1734 snd-cmipci= [HW,ALSA]
1736 snd-cs4231= [HW,ALSA]
1738 snd-cs4232= [HW,ALSA]
1740 snd-cs4236= [HW,ALSA]
1742 snd-cs4281= [HW,ALSA]
1744 snd-cs46xx= [HW,ALSA]
1746 snd-dt019x= [HW,ALSA]
1748 snd-dummy= [HW,ALSA]
1750 snd-emu10k1= [HW,ALSA]
1752 snd-ens1370= [HW,ALSA]
1754 snd-ens1371= [HW,ALSA]
1756 snd-es968= [HW,ALSA]
1758 snd-es1688= [HW,ALSA]
1760 snd-es18xx= [HW,ALSA]
1762 snd-es1938= [HW,ALSA]
1764 snd-es1968= [HW,ALSA]
1766 snd-fm801= [HW,ALSA]
1768 snd-gusclassic= [HW,ALSA]
1770 snd-gusextreme= [HW,ALSA]
1772 snd-gusmax= [HW,ALSA]
1774 snd-hdsp= [HW,ALSA]
1776 snd-ice1712= [HW,ALSA]
1778 snd-intel8x0= [HW,ALSA]
1780 snd-interwave= [HW,ALSA]
1782 snd-interwave-stb=
1783 [HW,ALSA]
1785 snd-korg1212= [HW,ALSA]
1787 snd-maestro3= [HW,ALSA]
1789 snd-mpu401= [HW,ALSA]
1791 snd-mtpav= [HW,ALSA]
1793 snd-nm256= [HW,ALSA]
1795 snd-opl3sa2= [HW,ALSA]
1797 snd-opti92x-ad1848=
1798 [HW,ALSA]
1800 snd-opti92x-cs4231=
1801 [HW,ALSA]
1803 snd-opti93x= [HW,ALSA]
1805 snd-pmac= [HW,ALSA]
1807 snd-rme32= [HW,ALSA]
1809 snd-rme96= [HW,ALSA]
1811 snd-rme9652= [HW,ALSA]
1813 snd-sb8= [HW,ALSA]
1815 snd-sb16= [HW,ALSA]
1817 snd-sbawe= [HW,ALSA]
1819 snd-serial= [HW,ALSA]
1821 snd-sgalaxy= [HW,ALSA]
1823 snd-sonicvibes= [HW,ALSA]
1825 snd-sun-amd7930=
1826 [HW,ALSA]
1828 snd-sun-cs4231= [HW,ALSA]
1830 snd-trident= [HW,ALSA]
1832 snd-usb-audio= [HW,ALSA,USB]
1834 snd-via82xx= [HW,ALSA]
1836 snd-virmidi= [HW,ALSA]
1838 snd-wavefront= [HW,ALSA]
1840 snd-ymfpci= [HW,ALSA]
1842 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1843 See Documentation/sonypi.txt
1845 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1846 See Documentation/specialix.txt.
1848 spia_io_base= [HW,MTD]
1849 spia_fio_base=
1850 spia_pedr=
1851 spia_peddr=
1853 sscape= [HW,OSS]
1854 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1856 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1857 See Documentation/scsi/st.txt.
1859 st0x= [HW,SCSI]
1860 See header of drivers/scsi/seagate.c.
1862 sti= [PARISC,HW]
1863 Format: <num>
1864 Set the STI (builtin display/keyboard on the HP-PARISC
1865 machines) console (graphic card) which should be used
1866 as the initial boot-console.
1867 See also comment in drivers/video/console/sticore.c.
1869 sti_font= [HW]
1870 See comment in drivers/video/console/sticore.c.
1872 stifb= [HW]
1873 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1875 sunrpc.pool_mode=
1876 [NFS]
1877 Control how the NFS server code allocates CPUs to
1878 service thread pools. Depending on how many NICs
1879 you have and where their interrupts are bound, this
1880 option will affect which CPUs will do NFS serving.
1881 Note: this parameter cannot be changed while the
1882 NFS server is running.
1884 auto the server chooses an appropriate mode
1885 automatically using heuristics
1886 global a single global pool contains all CPUs
1887 percpu one pool for each CPU
1888 pernode one pool for each NUMA node (equivalent
1889 to global on non-NUMA machines)
1891 swiotlb= [IA-64] Number of I/O TLB slabs
1893 switches= [HW,M68k]
1895 sym53c416= [HW,SCSI]
1896 See header of drivers/scsi/sym53c416.c.
1898 sysrq_always_enabled
1899 [KNL]
1900 Ignore sysrq setting - this boot parameter will
1901 neutralize any effect of /proc/sys/kernel/sysrq.
1902 Useful for debugging.
1904 t128= [HW,SCSI]
1905 See header of drivers/scsi/t128.c.
1907 tdfx= [HW,DRM]
1909 thash_entries= [KNL,NET]
1910 Set number of hash buckets for TCP connection
1912 thermal.act= [HW,ACPI]
1913 -1: disable all active trip points in all thermal zones
1914 <degrees C>: override all lowest active trip points
1916 thermal.crt= [HW,ACPI]
1917 -1: disable all critical trip points in all thermal zones
1918 <degrees C>: lower all critical trip points
1920 thermal.nocrt= [HW,ACPI]
1921 Set to disable actions on ACPI thermal zone
1922 critical and hot trip points.
1924 thermal.off= [HW,ACPI]
1925 1: disable ACPI thermal control
1927 thermal.psv= [HW,ACPI]
1928 -1: disable all passive trip points
1929 <degrees C>: override all passive trip points to this value
1931 thermal.tzp= [HW,ACPI]
1932 Specify global default ACPI thermal zone polling rate
1933 <deci-seconds>: poll all this frequency
1934 0: no polling (default)
1936 time Show timing data prefixed to each printk message line
1937 [deprecated, see 'printk.time']
1939 tipar.timeout= [HW,PPT]
1940 Set communications timeout in tenths of a second
1941 (default 15).
1943 tipar.delay= [HW,PPT]
1944 Set inter-bit delay in microseconds (default 10).
1946 tmc8xx= [HW,SCSI]
1947 See header of drivers/scsi/seagate.c.
1949 tmscsim= [HW,SCSI]
1950 See comment before function dc390_setup() in
1951 drivers/scsi/tmscsim.c.
1953 tp720= [HW,PS2]
1955 trix= [HW,OSS] MediaTrix AudioTrix Pro
1956 Format:
1957 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1959 turbografx.map[2|3]= [HW,JOY]
1960 TurboGraFX parallel port interface
1961 Format:
1962 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1963 See also Documentation/input/joystick-parport.txt
1965 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1966 See header of drivers/scsi/u14-34f.c.
1968 uart401= [HW,OSS]
1969 Format: <io>,<irq>
1971 uart6850= [HW,OSS]
1972 Format: <io>,<irq>
1974 uhci-hcd.ignore_oc=
1975 [USB] Ignore overcurrent events (default N).
1976 Some badly-designed motherboards generate lots of
1977 bogus events, for ports that aren't wired to
1978 anything. Set this parameter to avoid log spamming.
1979 Note that genuine overcurrent events won't be
1980 reported either.
1982 usbcore.autosuspend=
1983 [USB] The autosuspend time delay (in seconds) used
1984 for newly-detected USB devices (default 2). This
1985 is the time required before an idle device will be
1986 autosuspended. Devices for which the delay is set
1987 to a negative value won't be autosuspended at all.
1989 usbhid.mousepoll=
1990 [USBHID] The interval which mice are to be polled at.
1992 vdso= [X86-32,SH,x86-64]
1993 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1994 vdso=1: enable VDSO (default)
1995 vdso=0: disable VDSO mapping
1997 vdso32= [X86-32,X86-64]
1998 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
1999 vdso32=1: enable 32-bit VDSO (default)
2000 vdso32=0: disable 32-bit VDSO mapping
2002 vector= [IA-64,SMP]
2003 vector=percpu: enable percpu vector domain
2005 video= [FB] Frame buffer configuration
2006 See Documentation/fb/modedb.txt.
2008 vga= [BOOT,X86-32] Select a particular video mode
2009 See Documentation/i386/boot.txt and
2010 Documentation/svga.txt.
2011 Use vga=ask for menu.
2012 This is actually a boot loader parameter; the value is
2013 passed to the kernel using a special protocol.
2015 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2016 size of <nn>. This can be used to increase the
2017 minimum size (128MB on x86). It can also be used to
2018 decrease the size and leave more room for directly
2019 mapped kernel RAM.
2021 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2022 Format: <command>
2024 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2025 Format: <command>
2027 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2028 Format: <command>
2030 waveartist= [HW,OSS]
2031 Format: <io>,<irq>,<dma>,<dma2>
2033 wd33c93= [HW,SCSI]
2034 See header of drivers/scsi/wd33c93.c.
2036 wd7000= [HW,SCSI]
2037 See header of drivers/scsi/wd7000.c.
2039 wdt= [WDT] Watchdog
2040 See Documentation/watchdog/wdt.txt.
2042 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2043 xd_geo= See header of drivers/block/xd.c.
2045 xirc2ps_cs= [NET,PCMCIA]
2046 Format:
2047 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2049 norandmaps Don't use address space randomization
2050 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2052 ______________________________________________________________________
2054 TODO:
2056 Add documentation for ALSA options.
2057 Add more DRM drivers.