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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend is enabled.
91 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
99 X86-32 X86-32, aka i386 architecture is enabled.
100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
104 In addition, the following text indicates that the option:
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
110 Parameters denoted with BOOT are actually interpreted by the boot
111 loader, and have no meaning to the kernel directly.
112 Do not modify the syntax of boot loader parameters without extreme
113 need or coordination with <Documentation/i386/boot.txt>.
115 There are also arch-specific kernel-parameters not documented here.
116 See for example <Documentation/x86_64/boot-options.txt>.
118 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119 a trailing = on the name of any parameter states that that parameter will
120 be entered as an environment variable, whereas its absence indicates that
121 it will appear as a kernel argument readable via /proc/cmdline by programs
122 running once the system is up.
124 The number of kernel parameters is not limited, but the length of the
125 complete command line (parameters including spaces etc.) is limited to
126 a fixed number of characters. This limit depends on the architecture
127 and is between 256 and 4096 characters. It is defined in the file
128 ./include/asm/setup.h as COMMAND_LINE_SIZE.
131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
133 Format: { force | off | ht | strict | noirq }
134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
138 strict -- Be less tolerant of platforms that are not
139 strictly ACPI specification compliant.
141 See also Documentation/power/pm.txt, pci=noacpi
143 acpi_apic_instance= [ACPI, IOAPIC]
144 Format: <int>
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
147 default: 0
149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode, s3_beep }
151 See Documentation/power/video.txt for s3_bios and s3_mode.
152 s3_beep is for debugging; it makes the PC's speaker beep
153 as soon as the kernel's real-mode entry point is called.
155 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
156 Format: { level | edge | high | low }
158 acpi_irq_balance [HW,ACPI]
159 ACPI will balance active IRQs
160 default in APIC mode
162 acpi_irq_nobalance [HW,ACPI]
163 ACPI will not move active IRQs (default)
164 default in PIC mode
166 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
167 use by PCI
168 Format: <irq>,<irq>...
170 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
171 Format: <irq>,<irq>...
173 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
175 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
176 Format: To spoof as Windows 98: ="Microsoft Windows"
178 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
179 acpi_osi="string1" # add string1 -- only one string
180 acpi_osi="!string2" # remove built-in string2
181 acpi_osi= # disable all strings
183 acpi_serialize [HW,ACPI] force serialization of AML methods
185 acpi_skip_timer_override [HW,ACPI]
186 Recognize and ignore IRQ0/pin2 Interrupt Override.
187 For broken nForce2 BIOS resulting in XT-PIC timer.
188 acpi_use_timer_override [HW,ACPI}
189 Use timer override. For some broken Nvidia NF5 boards
190 that require a timer override, but don't have
191 HPET
193 acpi.debug_layer= [HW,ACPI]
194 Format: <int>
195 Each bit of the <int> indicates an ACPI debug layer,
196 1: enable, 0: disable. It is useful for boot time
197 debugging. After system has booted up, it can be set
198 via /sys/module/acpi/parameters/debug_layer.
199 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
200 Available bits (add the numbers together) to enable debug output
201 for specific parts of the ACPI subsystem:
202 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
203 0x10 namespace 0x20 parser 0x40 dispatcher
204 0x80 executer 0x100 resources 0x200 acpica debugger
205 0x400 os services 0x800 acpica disassembler.
206 The number can be in decimal or prefixed with 0x in hex.
207 Warning: Many of these options can produce a lot of
208 output and make your system unusable. Be very careful.
210 acpi.debug_level= [HW,ACPI]
211 Format: <int>
212 Each bit of the <int> indicates an ACPI debug level,
213 1: enable, 0: disable. It is useful for boot time
214 debugging. After system has booted up, it can be set
215 via /sys/module/acpi/parameters/debug_level.
216 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
217 Available bits (add the numbers together) to enable different
218 debug output levels of the ACPI subsystem:
219 0x01 error 0x02 warn 0x04 init 0x08 debug object
220 0x10 info 0x20 init names 0x40 parse 0x80 load
221 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
222 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
223 0x10000 resources 0x20000 user requests 0x40000 package.
224 The number can be in decimal or prefixed with 0x in hex.
225 Warning: Many of these options can produce a lot of
226 output and make your system unusable. Be very careful.
228 acpi_pm_good [X86-32,X86-64]
229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
233 agp= [AGP]
234 { off | try_unsupported }
235 off: disable AGP support
236 try_unsupported: try to drive unsupported chipsets
237 (may crash computer or cause data corruption)
239 enable_timer_pin_1 [i386,x86-64]
240 Enable PIN 1 of APIC timer
241 Can be useful to work around chipset bugs
242 (in particular on some ATI chipsets).
243 The kernel tries to set a reasonable default.
245 disable_timer_pin_1 [i386,x86-64]
246 Disable PIN 1 of APIC timer
247 Can be useful to work around chipset bugs.
249 ad1848= [HW,OSS]
250 Format: <io>,<irq>,<dma>,<dma2>,<type>
252 advansys= [HW,SCSI]
253 See header of drivers/scsi/advansys.c.
255 advwdt= [HW,WDT] Advantech WDT
256 Format: <iostart>,<iostop>
258 aedsp16= [HW,OSS] Audio Excel DSP 16
259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
260 See also header of sound/oss/aedsp16.c.
262 aha152x= [HW,SCSI]
263 See Documentation/scsi/aha152x.txt.
265 aha1542= [HW,SCSI]
266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
268 aic7xxx= [HW,SCSI]
269 See Documentation/scsi/aic7xxx.txt.
271 aic79xx= [HW,SCSI]
272 See Documentation/scsi/aic79xx.txt.
274 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT
276 Format: <a>,<b>
277 See also Documentation/kernel/input/joystick.txt
279 analog.map= [HW,JOY] Analog joystick and gamepad support
280 Specifies type or capabilities of an analog joystick
281 connected to one of 16 gameports
282 Format: <type1>,<type2>,..<type16>
284 apc= [HW,SPARC]
285 Power management functions (SPARCstation-4/5 + deriv.)
286 Format: noidle
287 Disable APC CPU standby support. SPARCstation-Fox does
288 not play well with APC CPU idle - disable it if you have
289 APC and your system crashes randomly.
291 apic= [APIC,i386] Advanced Programmable Interrupt Controller
292 Change the output verbosity whilst booting
293 Format: { quiet (default) | verbose | debug }
294 Change the amount of debugging information output
295 when initialising the APIC and IO-APIC components.
297 apm= [APM] Advanced Power Management
298 See header of arch/i386/kernel/apm.c.
300 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
301 Format: <io>,<irq>,<nodeID>
303 ataflop= [HW,M68k]
305 atarimouse= [HW,MOUSE] Atari Mouse
307 atascsi= [HW,SCSI] Atari SCSI
309 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
310 EzKey and similar keyboards
312 atkbd.reset= [HW] Reset keyboard during initialization
314 atkbd.set= [HW] Select keyboard code set
315 Format: <int> (2 = AT (default), 3 = PS/2)
317 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
318 keyboards
320 atkbd.softraw= [HW] Choose between synthetic and real raw mode
321 Format: <bool> (0 = real, 1 = synthetic (default))
323 atkbd.softrepeat= [HW]
324 Use software keyboard repeat
326 autotest [IA64]
328 baycom_epp= [HW,AX25]
329 Format: <io>,<mode>
331 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
332 Format: <io>,<mode>
333 See header of drivers/net/hamradio/baycom_par.c.
335 baycom_ser_fdx= [HW,AX25]
336 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
337 Format: <io>,<irq>,<mode>[,<baud>]
338 See header of drivers/net/hamradio/baycom_ser_fdx.c.
340 baycom_ser_hdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
342 Format: <io>,<irq>,<mode>
343 See header of drivers/net/hamradio/baycom_ser_hdx.c.
345 boot_delay= Milliseconds to delay each printk during boot.
346 Values larger than 10 seconds (10000) are changed to
347 no delay (0).
348 Format: integer
350 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
351 bttv.radio= Most important insmod options are available as
352 kernel args too.
353 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
354 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
356 BusLogic= [HW,SCSI]
357 See drivers/scsi/BusLogic.c, comment before function
358 BusLogic_ParseDriverOptions().
360 c101= [NET] Moxa C101 synchronous serial card
362 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
363 Sometimes CPU hardware bugs make them report the cache
364 size incorrectly. The kernel will attempt work arounds
365 to fix known problems, but for some CPUs it is not
366 possible to determine what the correct size should be.
367 This option provides an override for these situations.
369 capability.disable=
370 [SECURITY] Disable capabilities. This would normally
371 be used only if an alternative security model is to be
372 configured. Potentially dangerous and should only be
373 used if you are entirely sure of the consequences.
375 ccw_timeout_log [S390]
376 See Documentation/s390/CommonIO for details.
378 checkreqprot [SELINUX] Set initial checkreqprot flag value.
379 Format: { "0" | "1" }
380 See security/selinux/Kconfig help text.
381 0 -- check protection applied by kernel (includes
382 any implied execute protection).
383 1 -- check protection requested by application.
384 Default value is set via a kernel config option.
385 Value can be changed at runtime via
386 /selinux/checkreqprot.
388 cio_ignore= [S390]
389 See Documentation/s390/CommonIO for details.
391 cio_msg= [S390]
392 See Documentation/s390/CommonIO for details.
394 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
395 [Deprecated]
396 Forces specified clocksource (if available) to be used
397 when calculating gettimeofday(). If specified
398 clocksource is not available, it defaults to PIT.
399 Format: { pit | tsc | cyclone | pmtmr }
401 clocksource= [GENERIC_TIME] Override the default clocksource
402 Format: <string>
403 Override the default clocksource and use the clocksource
404 with the name specified.
405 Some clocksource names to choose from, depending on
406 the platform:
407 [all] jiffies (this is the base, fallback clocksource)
408 [ACPI] acpi_pm
409 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
410 pxa_timer,timer3,32k_counter,timer0_1
411 [AVR32] avr32
412 [X86-32] pit,hpet,tsc,vmi-timer;
413 scx200_hrt on Geode; cyclone on IBM x440
414 [MIPS] MIPS
415 [PARISC] cr16
416 [S390] tod
417 [SH] SuperH
418 [SPARC64] tick
419 [X86-64] hpet,tsc
421 clearcpuid=BITNUM [X86]
422 Disable CPUID feature X for the kernel. See
423 include/asm-x86/cpufeature.h for the valid bit numbers.
424 Note the Linux specific bits are not necessarily
425 stable over kernel options, but the vendor specific
426 ones should be.
427 Also note that user programs calling CPUID directly
428 or using the feature without checking anything
429 will still see it. This just prevents it from
430 being used by the kernel or shown in /proc/cpuinfo.
431 Also note the kernel might malfunction if you disable
432 some critical bits.
434 code_bytes [IA32/X86_64] How many bytes of object code to print
435 in an oops report.
436 Range: 0 - 8192
437 Default: 64
439 disable_8254_timer
440 enable_8254_timer
441 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
442 over the 8254 in addition to over the IO-APIC. The
443 kernel tries to set a sensible default.
445 hpet= [X86-32,HPET] option to control HPET usage
446 Format: { enable (default) | disable | force }
447 disable: disable HPET and use PIT instead
448 force: allow force enabled of undocumented chips (ICH4,
449 VIA, nVidia)
451 com20020= [HW,NET] ARCnet - COM20020 chipset
452 Format:
453 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
455 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
456 Format: <io>[,<irq>]
458 com90xx= [HW,NET]
459 ARCnet - COM90xx chipset (memory-mapped buffers)
460 Format: <io>[,<irq>[,<memstart>]]
462 condev= [HW,S390] console device
463 conmode=
465 console= [KNL] Output console device and options.
467 tty<n> Use the virtual console device <n>.
469 ttyS<n>[,options]
470 ttyUSB0[,options]
471 Use the specified serial port. The options are of
472 the form "bbbbpnf", where "bbbb" is the baud rate,
473 "p" is parity ("n", "o", or "e"), "n" is number of
474 bits, and "f" is flow control ("r" for RTS or
475 omit it). Default is "9600n8".
477 See Documentation/serial-console.txt for more
478 information. See
479 Documentation/networking/netconsole.txt for an
480 alternative.
482 uart[8250],io,<addr>[,options]
483 uart[8250],mmio,<addr>[,options]
484 Start an early, polled-mode console on the 8250/16550
485 UART at the specified I/O port or MMIO address,
486 switching to the matching ttyS device later. The
487 options are the same as for ttyS, above.
489 earlycon= [KNL] Output early console device and options.
490 uart[8250],io,<addr>[,options]
491 uart[8250],mmio,<addr>[,options]
492 Start an early, polled-mode console on the 8250/16550
493 UART at the specified I/O port or MMIO address.
494 The options are the same as for ttyS, above.
496 no_console_suspend
497 [HW] Never suspend the console
498 Disable suspending of consoles during suspend and
499 hibernate operations. Once disabled, debugging
500 messages can reach various consoles while the rest
501 of the system is being put to sleep (ie, while
502 debugging driver suspend/resume hooks). This may
503 not work reliably with all consoles, but is known
504 to work with serial and VGA consoles.
506 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
507 Format:
508 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
510 crashkernel=nn[KMG]@ss[KMG]
511 [KNL] Reserve a chunk of physical memory to
512 hold a kernel to switch to with kexec on panic.
514 crashkernel=range1:size1[,range2:size2,...][@offset]
515 [KNL] Same as above, but depends on the memory
516 in the running system. The syntax of range is
517 start-[end] where start and end are both
518 a memory unit (amount[KMG]). See also
519 Documentation/kdump/kdump.txt for a example.
521 cs4232= [HW,OSS]
522 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
524 cs89x0_dma= [HW,NET]
525 Format: <dma>
527 cs89x0_media= [HW,NET]
528 Format: { rj45 | aui | bnc }
530 dasd= [HW,NET]
531 See header of drivers/s390/block/dasd_devmap.c.
533 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
534 (one device per port)
535 Format: <port#>,<type>
536 See also Documentation/input/joystick-parport.txt
538 debug [KNL] Enable kernel debugging (events log level).
540 debug_locks_verbose=
541 [KNL] verbose self-tests
542 Format=<0|1>
543 Print debugging info while doing the locking API
544 self-tests.
545 We default to 0 (no extra messages), setting it to
546 1 will print _a lot_ more information - normally
547 only useful to kernel developers.
549 decnet.addr= [HW,NET]
550 Format: <area>[,<node>]
551 See also Documentation/networking/decnet.txt.
553 vt.default_blu= [VT]
554 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
555 Change the default blue palette of the console.
556 This is a 16-member array composed of values
557 ranging from 0-255.
559 vt.default_grn= [VT]
560 Format: <green0>,<green1>,<green2>,...,<green15>
561 Change the default green palette of the console.
562 This is a 16-member array composed of values
563 ranging from 0-255.
565 vt.default_red= [VT]
566 Format: <red0>,<red1>,<red2>,...,<red15>
567 Change the default red palette of the console.
568 This is a 16-member array composed of values
569 ranging from 0-255.
571 vt.default_utf8=
572 [VT]
573 Format=<0|1>
574 Set system-wide default UTF-8 mode for all tty's.
575 Default is 1, i.e. UTF-8 mode is enabled for all
576 newly opened terminals.
578 dhash_entries= [KNL]
579 Set number of hash buckets for dentry cache.
581 digi= [HW,SERIAL]
582 IO parameters + enable/disable command.
584 digiepca= [HW,SERIAL]
585 See drivers/char/README.epca and
586 Documentation/digiepca.txt.
588 disable_mtrr_trim [X86, Intel and AMD only]
589 By default the kernel will trim any uncacheable
590 memory out of your available memory pool based on
591 MTRR settings. This parameter disables that behavior,
592 possibly causing your machine to run very slowly.
594 dmasound= [HW,OSS] Sound subsystem buffers
596 dscc4.setup= [NET]
598 dtc3181e= [HW,SCSI]
600 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
601 earlyprintk=vga
602 earlyprintk=serial[,ttySn[,baudrate]]
604 Append ",keep" to not disable it when the real console
605 takes over.
607 Only vga or serial at a time, not both.
609 Currently only ttyS0 and ttyS1 are supported.
611 Interaction with the standard serial driver is not
612 very good.
614 The VGA output is eventually overwritten by the real
615 console.
617 eata= [HW,SCSI]
619 edd= [EDD]
620 Format: {"of[f]" | "sk[ipmbr]"}
621 See comment in arch/i386/boot/edd.S
623 eisa_irq_edge= [PARISC,HW]
624 See header of drivers/parisc/eisa.c.
626 elanfreq= [X86-32]
627 See comment before function elanfreq_setup() in
628 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
630 elevator= [IOSCHED]
631 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
632 See Documentation/block/as-iosched.txt and
633 Documentation/block/deadline-iosched.txt for details.
635 elfcorehdr= [X86-32, X86_64]
636 Specifies physical address of start of kernel core
637 image elf header. Generally kexec loader will
638 pass this option to capture kernel.
639 See Documentation/kdump/kdump.txt for details.
641 enforcing [SELINUX] Set initial enforcing status.
642 Format: {"0" | "1"}
643 See security/selinux/Kconfig help text.
644 0 -- permissive (log only, no denials).
645 1 -- enforcing (deny and log).
646 Default value is 0.
647 Value can be changed at runtime via /selinux/enforce.
649 es1371= [HW,OSS]
650 Format: <spdif>,[<nomix>,[<amplifier>]]
651 See also header of sound/oss/es1371.c.
653 ether= [HW,NET] Ethernet cards parameters
654 This option is obsoleted by the "netdev=" option, which
655 has equivalent usage. See its documentation for details.
657 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
658 Format: <io>[,<irq>]
660 failslab=
661 fail_page_alloc=
662 fail_make_request=[KNL]
663 General fault injection mechanism.
664 Format: <interval>,<probability>,<space>,<times>
665 See also /Documentation/fault-injection/.
667 fd_mcs= [HW,SCSI]
668 See header of drivers/scsi/fd_mcs.c.
670 fdomain= [HW,SCSI]
671 See header of drivers/scsi/fdomain.c.
673 floppy= [HW]
674 See Documentation/floppy.txt.
676 gamecon.map[2|3]=
677 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
678 support via parallel port (up to 5 devices per port)
679 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
680 See also Documentation/input/joystick-parport.txt
682 gamma= [HW,DRM]
684 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
685 Format: off | on
686 default: on
688 gdth= [HW,SCSI]
689 See header of drivers/scsi/gdth.c.
691 gpt [EFI] Forces disk with valid GPT signature but
692 invalid Protective MBR to be treated as GPT.
694 gvp11= [HW,SCSI]
696 hashdist= [KNL,NUMA] Large hashes allocated during boot
697 are distributed across NUMA nodes. Defaults on
698 for IA-64, off otherwise.
699 Format: 0 | 1 (for off | on)
701 hcl= [IA-64] SGI's Hardware Graph compatibility layer
703 hd= [EIDE] (E)IDE hard drive subsystem geometry
704 Format: <cyl>,<head>,<sect>
706 hd?= [HW] (E)IDE subsystem
707 hd?lun= See Documentation/ide/ide.txt.
709 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
710 size of <nn>. This works even on boxes that have no
711 highmem otherwise. This also works to reduce highmem
712 size on bigger boxes.
714 highres= [KNL] Enable/disable high resolution timer mode.
715 Valid parameters: "on", "off"
716 Default: "on"
718 hisax= [HW,ISDN]
719 See Documentation/isdn/README.HiSax.
721 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
722 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
724 i8042.direct [HW] Put keyboard port into non-translated mode
725 i8042.dumbkbd [HW] Pretend that controller can only read data from
726 keyboard and cannot control its state
727 (Don't attempt to blink the leds)
728 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
729 i8042.nokbd [HW] Don't check/create keyboard port
730 i8042.noloop [HW] Disable the AUX Loopback command while probing
731 for the AUX port
732 i8042.nomux [HW] Don't check presence of an active multiplexing
733 controller
734 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
735 controllers
736 i8042.panicblink=
737 [HW] Frequency with which keyboard LEDs should blink
738 when kernel panics (default is 0.5 sec)
739 i8042.reset [HW] Reset the controller during init and cleanup
740 i8042.unlock [HW] Unlock (ignore) the keylock
742 i810= [HW,DRM]
744 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
745 indicates that the driver is running on unsupported
746 hardware.
747 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
748 does not match list of supported models.
749 i8k.power_status
750 [HW] Report power status in /proc/i8k
751 (disabled by default)
752 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
753 capability is set.
755 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
756 See Documentation/mca.txt.
758 icn= [HW,ISDN]
759 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
761 ide= [HW] (E)IDE subsystem
762 Format: ide=nodma or ide=doubler or ide=reverse
763 See Documentation/ide/ide.txt.
765 ide?= [HW] (E)IDE subsystem
766 Format: ide?=noprobe or chipset specific parameters.
767 See Documentation/ide/ide.txt.
769 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
770 See Documentation/ide/ide.txt.
772 idle= [X86]
773 Format: idle=poll or idle=mwait
774 Poll forces a polling idle loop that can slightly improves the performance
775 of waking up a idle CPU, but will use a lot of power and make the system
776 run hot. Not recommended.
777 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
778 to not use it because it doesn't save as much power as a normal idle
779 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
780 as idle=poll.
782 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
783 Claim all unknown PCI IDE storage controllers.
785 ignore_loglevel [KNL]
786 Ignore loglevel setting - this will print /all/
787 kernel messages to the console. Useful for debugging.
789 ihash_entries= [KNL]
790 Set number of hash buckets for inode cache.
792 in2000= [HW,SCSI]
793 See header of drivers/scsi/in2000.c.
795 init= [KNL]
796 Format: <full_path>
797 Run specified binary instead of /sbin/init as init
798 process.
800 initcall_debug [KNL] Trace initcalls as they are executed. Useful
801 for working out where the kernel is dying during
802 startup.
804 initrd= [BOOT] Specify the location of the initial ramdisk
806 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
807 Format: <irq>
809 inttest= [IA64]
811 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
812 off
813 Disable intel iommu driver.
814 igfx_off [Default Off]
815 By default, gfx is mapped as normal device. If a gfx
816 device has a dedicated DMAR unit, the DMAR unit is
817 bypassed by not enabling DMAR with this option. In
818 this case, gfx device will use physical address for
819 DMA.
820 forcedac [x86_64]
821 With this option iommu will not optimize to look
822 for io virtual address below 32 bit forcing dual
823 address cycle on pci bus for cards supporting greater
824 than 32 bit addressing. The default is to look
825 for translation below 32 bit and if not available
826 then look in the higher range.
828 io_delay= [X86-32,X86-64] I/O delay method
829 0x80
830 Standard port 0x80 based delay
831 0xed
832 Alternate port 0xed based delay (needed on some systems)
833 udelay
834 Simple two microseconds delay
835 none
836 No delay
838 io7= [HW] IO7 for Marvel based alpha systems
839 See comment before marvel_specify_io7 in
840 arch/alpha/kernel/core_marvel.c.
842 ip= [IP_PNP]
843 See Documentation/nfsroot.txt.
845 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
846 See comment before ip2_setup() in
847 drivers/char/ip2/ip2base.c.
849 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
850 See header of drivers/scsi/ips.c.
852 ports= [IP_VS_FTP] IPVS ftp helper module
853 Default is 21.
854 Up to 8 (IP_VS_APP_MAX_PORTS) ports
855 may be specified.
856 Format: <port>,<port>....
858 irqfixup [HW]
859 When an interrupt is not handled search all handlers
860 for it. Intended to get systems with badly broken
861 firmware running.
863 irqpoll [HW]
864 When an interrupt is not handled search all handlers
865 for it. Also check all handlers each timer
866 interrupt. Intended to get systems with badly broken
867 firmware running.
869 isapnp= [ISAPNP]
870 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
872 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
873 Format:
874 <cpu number>,...,<cpu number>
875 or
876 <cpu number>-<cpu number> (must be a positive range in ascending order)
877 or a mixture
878 <cpu number>,...,<cpu number>-<cpu number>
879 This option can be used to specify one or more CPUs
880 to isolate from the general SMP balancing and scheduling
881 algorithms. The only way to move a process onto or off
882 an "isolated" CPU is via the CPU affinity syscalls.
883 <cpu number> begins at 0 and the maximum value is
884 "number of CPUs in system - 1".
886 This option is the preferred way to isolate CPUs. The
887 alternative -- manually setting the CPU mask of all
888 tasks in the system -- can cause problems and
889 suboptimal load balancer performance.
891 iucv= [HW,NET]
893 js= [HW,JOY] Analog joystick
894 See Documentation/input/joystick.txt.
896 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
897 specifies the amount of memory usable by the kernel
898 for non-movable allocations. The requested amount is
899 spread evenly throughout all nodes in the system. The
900 remaining memory in each node is used for Movable
901 pages. In the event, a node is too small to have both
902 kernelcore and Movable pages, kernelcore pages will
903 take priority and other nodes will have a larger number
904 of kernelcore pages. The Movable zone is used for the
905 allocation of pages that may be reclaimed or moved
906 by the page migration subsystem. This means that
907 HugeTLB pages may not be allocated from this zone.
908 Note that allocations like PTEs-from-HighMem still
909 use the HighMem zone if it exists, and the Normal
910 zone if it does not.
912 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
913 is similar to kernelcore except it specifies the
914 amount of memory used for migratable allocations.
915 If both kernelcore and movablecore is specified,
916 then kernelcore will be at *least* the specified
917 value but may be more. If movablecore on its own
918 is specified, the administrator must be careful
919 that the amount of memory usable for all allocations
920 is not too small.
922 keepinitrd [HW,ARM]
924 kstack=N [X86-32,X86-64] Print N words from the kernel stack
925 in oops dumps.
927 l2cr= [PPC]
929 lapic [X86-32,APIC] Enable the local APIC even if BIOS
930 disabled it.
932 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
933 C2 power state.
935 libata.dma= [LIBATA] DMA control
936 libata.dma=0 Disable all PATA and SATA DMA
937 libata.dma=1 PATA and SATA Disk DMA only
938 libata.dma=2 ATAPI (CDROM) DMA only
939 libata.dma=4 Compact Flash DMA only
940 Combinations also work, so libata.dma=3 enables DMA
941 for disks and CDROMs, but not CFs.
943 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
944 when set.
945 Format: <int>
947 libata.force= [LIBATA] Force configurations. The format is comma
948 separated list of "[ID:]VAL" where ID is
949 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
950 matching port, link or device. Basically, it matches
951 the ATA ID string printed on console by libata. If
952 the whole ID part is omitted, the last PORT and DEVICE
953 values are used. If ID hasn't been specified yet, the
954 configuration applies to all ports, links and devices.
956 If only DEVICE is omitted, the parameter applies to
957 the port and all links and devices behind it. DEVICE
958 number of 0 either selects the first device or the
959 first fan-out link behind PMP device. It does not
960 select the host link. DEVICE number of 15 selects the
961 host link and device attached to it.
963 The VAL specifies the configuration to force. As long
964 as there's no ambiguity shortcut notation is allowed.
965 For example, both 1.5 and 1.5G would work for 1.5Gbps.
966 The following configurations can be forced.
968 * Cable type: 40c, 80c, short40c, unk, ign or sata.
969 Any ID with matching PORT is used.
971 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
973 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
974 udma[/][16,25,33,44,66,100,133] notation is also
975 allowed.
977 * [no]ncq: Turn on or off NCQ.
979 If there are multiple matching configurations changing
980 the same attribute, the last one is used.
982 load_ramdisk= [RAM] List of ramdisks to load from floppy
983 See Documentation/ramdisk.txt.
985 lockd.nlm_grace_period=P [NFS] Assign grace period.
986 Format: <integer>
988 lockd.nlm_tcpport=N [NFS] Assign TCP port.
989 Format: <integer>
991 lockd.nlm_timeout=T [NFS] Assign timeout value.
992 Format: <integer>
994 lockd.nlm_udpport=M [NFS] Assign UDP port.
995 Format: <integer>
997 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
998 Format: <irq>
1000 loglevel= All Kernel Messages with a loglevel smaller than the
1001 console loglevel will be printed to the console. It can
1002 also be changed with klogd or other programs. The
1003 loglevels are defined as follows:
1005 0 (KERN_EMERG) system is unusable
1006 1 (KERN_ALERT) action must be taken immediately
1007 2 (KERN_CRIT) critical conditions
1008 3 (KERN_ERR) error conditions
1009 4 (KERN_WARNING) warning conditions
1010 5 (KERN_NOTICE) normal but significant condition
1011 6 (KERN_INFO) informational
1012 7 (KERN_DEBUG) debug-level messages
1014 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1015 Format: { n | nk | nM }
1016 n must be a power of two. The default size
1017 is set in the kernel config file.
1019 logo.nologo [FB] Disables display of the built-in Linux logo.
1020 This may be used to provide more screen space for
1021 kernel log messages and is useful when debugging
1022 kernel boot problems.
1024 lp=0 [LP] Specify parallel ports to use, e.g,
1025 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1026 lp=reset first parallel port). 'lp=0' disables the
1027 lp=auto printer driver. 'lp=reset' (which can be
1028 specified in addition to the ports) causes
1029 attached printers to be reset. Using
1030 lp=port1,port2,... specifies the parallel ports
1031 to associate lp devices with, starting with
1032 lp0. A port specification may be 'none' to skip
1033 that lp device, or a parport name such as
1034 'parport0'. Specifying 'lp=auto' instead of a
1035 port specification list means that device IDs
1036 from each port should be examined, to see if
1037 an IEEE 1284-compliant printer is attached; if
1038 so, the driver will manage that printer.
1039 See also header of drivers/char/lp.c.
1041 lpj=n [KNL]
1042 Sets loops_per_jiffy to given constant, thus avoiding
1043 time-consuming boot-time autodetection (up to 250 ms per
1044 CPU). 0 enables autodetection (default). To determine
1045 the correct value for your kernel, boot with normal
1046 autodetection and see what value is printed. Note that
1047 on SMP systems the preset will be applied to all CPUs,
1048 which is likely to cause problems if your CPUs need
1049 significantly divergent settings. An incorrect value
1050 will cause delays in the kernel to be wrong, leading to
1051 unpredictable I/O errors and other breakage. Although
1052 unlikely, in the extreme case this might damage your
1053 hardware.
1055 ltpc= [NET]
1056 Format: <io>,<irq>,<dma>
1058 mac5380= [HW,SCSI] Format:
1059 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1061 mac53c9x= [HW,SCSI] Format:
1062 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1064 machvec= [IA64] Force the use of a particular machine-vector
1065 (machvec) in a generic kernel.
1066 Example: machvec=hpzx1_swiotlb
1068 max_loop= [LOOP] Maximum number of loopback devices that can
1069 be mounted
1070 Format: <1-256>
1072 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1073 should make use of. maxcpus=n : n >= 0 limits the
1074 kernel to using 'n' processors. n=0 is a special case,
1075 it is equivalent to "nosmp", which also disables
1076 the IO APIC.
1078 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1079 equal to this physical address is ignored.
1081 max_luns= [SCSI] Maximum number of LUNs to probe.
1082 Should be between 1 and 2^32-1.
1084 max_report_luns=
1085 [SCSI] Maximum number of LUNs received.
1086 Should be between 1 and 16384.
1088 mcatest= [IA-64]
1090 mce [X86-32] Machine Check Exception
1092 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1094 md= [HW] RAID subsystems devices and level
1095 See Documentation/md.txt.
1097 mdacon= [MDA]
1098 Format: <first>,<last>
1099 Specifies range of consoles to be captured by the MDA.
1101 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1102 Amount of memory to be used when the kernel is not able
1103 to see the whole system memory or for test.
1104 [X86-32] Use together with memmap= to avoid physical
1105 address space collisions. Without memmap= PCI devices
1106 could be placed at addresses belonging to unused RAM.
1108 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1109 memory.
1111 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1112 E820 memory map, as specified by the user.
1113 Such memmap=exactmap lines can be constructed based on
1114 BIOS output or other requirements. See the memmap=nn@ss
1115 option description.
1117 memmap=nn[KMG]@ss[KMG]
1118 [KNL] Force usage of a specific region of memory
1119 Region of memory to be used, from ss to ss+nn.
1121 memmap=nn[KMG]#ss[KMG]
1122 [KNL,ACPI] Mark specific memory as ACPI data.
1123 Region of memory to be used, from ss to ss+nn.
1125 memmap=nn[KMG]$ss[KMG]
1126 [KNL,ACPI] Mark specific memory as reserved.
1127 Region of memory to be used, from ss to ss+nn.
1128 Example: Exclude memory from 0x18690000-0x1869ffff
1129 memmap=64K$0x18690000
1130 or
1131 memmap=0x10000$0x18690000
1133 meye.*= [HW] Set MotionEye Camera parameters
1134 See Documentation/video4linux/meye.txt.
1136 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1137 Multi-Function General Purpose Timers on AMD Geode
1138 platforms.
1140 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1141 the BIOS has incorrectly applied a workaround. TinyBIOS
1142 version 0.98 is known to be affected, 0.99 fixes the
1143 problem by letting the user disable the workaround.
1145 mga= [HW,DRM]
1147 mousedev.tap_time=
1148 [MOUSE] Maximum time between finger touching and
1149 leaving touchpad surface for touch to be considered
1150 a tap and be reported as a left button click (for
1151 touchpads working in absolute mode only).
1152 Format: <msecs>
1153 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1154 reporting absolute coordinates, such as tablets
1155 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1156 reporting absolute coordinates, such as tablets
1158 mpu401= [HW,OSS]
1159 Format: <io>,<irq>
1161 MTD_Partition= [MTD]
1162 Format: <name>,<region-number>,<size>,<offset>
1164 MTD_Region= [MTD] Format:
1165 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1167 mtdparts= [MTD]
1168 See drivers/mtd/cmdlinepart.c.
1170 mtouchusb.raw_coordinates=
1171 [HW] Make the MicroTouch USB driver use raw coordinates
1172 ('y', default) or cooked coordinates ('n')
1174 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1176 NCR_D700= [HW,SCSI]
1177 See header of drivers/scsi/NCR_D700.c.
1179 ncr5380= [HW,SCSI]
1181 ncr53c400= [HW,SCSI]
1183 ncr53c400a= [HW,SCSI]
1185 ncr53c406a= [HW,SCSI]
1187 ncr53c8xx= [HW,SCSI]
1189 netdev= [NET] Network devices parameters
1190 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1191 Note that mem_start is often overloaded to mean
1192 something different and driver-specific.
1193 This usage is only documented in each driver source
1194 file if at all.
1196 nfsaddrs= [NFS]
1197 See Documentation/nfsroot.txt.
1199 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1200 See Documentation/nfsroot.txt.
1202 nfs.callback_tcpport=
1203 [NFS] set the TCP port on which the NFSv4 callback
1204 channel should listen.
1206 nfs.idmap_cache_timeout=
1207 [NFS] set the maximum lifetime for idmapper cache
1208 entries.
1210 nfs.enable_ino64=
1211 [NFS] enable 64-bit inode numbers.
1212 If zero, the NFS client will fake up a 32-bit inode
1213 number for the readdir() and stat() syscalls instead
1214 of returning the full 64-bit number.
1215 The default is to return 64-bit inode numbers.
1217 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1218 when a NMI is triggered.
1219 Format: [state][,regs][,debounce][,die]
1221 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1223 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1224 emulation library even if a 387 maths coprocessor
1225 is present.
1227 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1228 caches in the slab allocator. Saves per-node memory,
1229 but will impact performance.
1231 noalign [KNL,ARM]
1233 noapic [SMP,APIC] Tells the kernel to not make use of any
1234 IOAPICs that may be present in the system.
1236 nobats [PPC] Do not use BATs for mapping kernel lowmem
1237 on "Classic" PPC cores.
1239 nocache [ARM]
1241 nodelayacct [KNL] Disable per-task delay accounting
1243 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1245 noefi [X86-32,X86-64] Disable EFI runtime services support.
1247 noexec [IA-64]
1249 noexec [X86-32,X86-64]
1250 noexec=on: enable non-executable mappings (default)
1251 noexec=off: disable nn-executable mappings
1253 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1254 register save and restore. The kernel will only save
1255 legacy floating-point registers on task switch.
1257 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1259 nohlt [BUGS=ARM]
1261 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1262 instruction doesn't work correctly and not to
1263 use it.
1265 nohalt [IA-64] Tells the kernel not to use the power saving
1266 function PAL_HALT_LIGHT when idle. This increases
1267 power-consumption. On the positive side, it reduces
1268 interrupt wake-up latency, which may improve performance
1269 in certain environments such as networked servers or
1270 real-time systems.
1272 nohz= [KNL] Boottime enable/disable dynamic ticks
1273 Valid arguments: on, off
1274 Default: on
1276 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1278 noirqdebug [X86-32] Disables the code which attempts to detect and
1279 disable unhandled interrupt sources.
1281 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1282 broken timer IRQ sources.
1284 noisapnp [ISAPNP] Disables ISA PnP code.
1286 noinitrd [RAM] Tells the kernel not to load any configured
1287 initial RAM disk.
1289 nointroute [IA-64]
1291 nojitter [IA64] Disables jitter checking for ITC timers.
1293 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1295 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1297 noltlbs [PPC] Do not use large page/tlb entries for kernel
1298 lowmem mapping on PPC40x.
1300 nomca [IA-64] Disable machine check abort handling
1302 nomce [X86-32] Machine Check Exception
1304 nomfgpt [X86-32] Disable Multi-Function General Purpose
1305 Timer usage (for AMD Geode machines).
1307 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1309 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1310 with UP alternatives
1312 noresidual [PPC] Don't use residual data on PReP machines.
1314 noresume [SWSUSP] Disables resume and restores original swap
1315 space.
1317 no-scroll [VGA] Disables scrollback.
1318 This is required for the Braillex ib80-piezo Braille
1319 reader made by F.H. Papenmeier (Germany).
1321 nosbagart [IA-64]
1323 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1325 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1326 and disable the IO APIC. legacy for "maxcpus=0".
1328 nosoftlockup [KNL] Disable the soft-lockup detector.
1330 nosync [HW,M68K] Disables sync negotiation for all devices.
1332 notsc [BUGS=X86-32] Disable Time Stamp Counter
1334 nousb [USB] Disable the USB subsystem
1336 nowb [ARM]
1338 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1339 one of ['zone', 'node', 'default'] can be specified
1340 This can be set from sysctl after boot.
1341 See Documentation/sysctl/vm.txt for details.
1343 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1345 opl3= [HW,OSS]
1346 Format: <io>
1348 oprofile.timer= [HW]
1349 Use timer interrupt instead of performance counters
1351 osst= [HW,SCSI] SCSI Tape Driver
1352 Format: <buffer_size>,<write_threshold>
1353 See also Documentation/scsi/st.txt.
1355 panic= [KNL] Kernel behaviour on panic
1356 Format: <timeout>
1358 parkbd.port= [HW] Parallel port number the keyboard adapter is
1359 connected to, default is 0.
1360 Format: <parport#>
1361 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1362 0 for XT, 1 for AT (default is AT).
1363 Format: <mode>
1365 parport= [HW,PPT] Specify parallel ports. 0 disables.
1366 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1367 Use 'auto' to force the driver to use any
1368 IRQ/DMA settings detected (the default is to
1369 ignore detected IRQ/DMA settings because of
1370 possible conflicts). You can specify the base
1371 address, IRQ, and DMA settings; IRQ and DMA
1372 should be numbers, or 'auto' (for using detected
1373 settings on that particular port), or 'nofifo'
1374 (to avoid using a FIFO even if it is detected).
1375 Parallel ports are assigned in the order they
1376 are specified on the command line, starting
1377 with parport0.
1379 parport_init_mode= [HW,PPT]
1380 Configure VIA parallel port to operate in
1381 a specific mode. This is necessary on Pegasos
1382 computer where firmware has no options for setting
1383 up parallel port mode and sets it to spp.
1384 Currently this function knows 686a and 8231 chips.
1385 Format: [spp|ps2|epp|ecp|ecpepp]
1387 pas2= [HW,OSS] Format:
1388 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1390 pas16= [HW,SCSI]
1391 See header of drivers/scsi/pas16.c.
1393 pause_on_oops=
1394 Halt all CPUs after the first oops has been printed for
1395 the specified number of seconds. This is to be used if
1396 your oopses keep scrolling off the screen.
1398 pcbit= [HW,ISDN]
1400 pcd. [PARIDE]
1401 See header of drivers/block/paride/pcd.c.
1402 See also Documentation/paride.txt.
1404 pci=option[,option...] [PCI] various PCI subsystem options:
1405 off [X86-32] don't probe for the PCI bus
1406 bios [X86-32] force use of PCI BIOS, don't access
1407 the hardware directly. Use this if your machine
1408 has a non-standard PCI host bridge.
1409 nobios [X86-32] disallow use of PCI BIOS, only direct
1410 hardware access methods are allowed. Use this
1411 if you experience crashes upon bootup and you
1412 suspect they are caused by the BIOS.
1413 conf1 [X86-32] Force use of PCI Configuration
1414 Mechanism 1.
1415 conf2 [X86-32] Force use of PCI Configuration
1416 Mechanism 2.
1417 noaer [PCIE] If the PCIEAER kernel config parameter is
1418 enabled, this kernel boot option can be used to
1419 disable the use of PCIE advanced error reporting.
1420 nodomains [PCI] Disable support for multiple PCI
1421 root domains (aka PCI segments, in ACPI-speak).
1422 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1423 Configuration
1424 nomsi [MSI] If the PCI_MSI kernel config parameter is
1425 enabled, this kernel boot option can be used to
1426 disable the use of MSI interrupts system-wide.
1427 nosort [X86-32] Don't sort PCI devices according to
1428 order given by the PCI BIOS. This sorting is
1429 done to get a device order compatible with
1430 older kernels.
1431 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1432 routing table. These calls are known to be buggy
1433 on several machines and they hang the machine
1434 when used, but on other computers it's the only
1435 way to get the interrupt routing table. Try
1436 this option if the kernel is unable to allocate
1437 IRQs or discover secondary PCI buses on your
1438 motherboard.
1439 rom [X86-32] Assign address space to expansion ROMs.
1440 Use with caution as certain devices share
1441 address decoders between ROMs and other
1442 resources.
1443 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1444 assigned automatically to PCI devices. You can
1445 make the kernel exclude IRQs of your ISA cards
1446 this way.
1447 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1448 of the PIRQ table (normally generated
1449 by the BIOS) if it is outside the
1450 F0000h-100000h range.
1451 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1452 useful if the kernel is unable to find your
1453 secondary buses and you want to tell it
1454 explicitly which ones they are.
1455 assign-busses [X86-32] Always assign all PCI bus
1456 numbers ourselves, overriding
1457 whatever the firmware may have done.
1458 usepirqmask [X86-32] Honor the possible IRQ mask stored
1459 in the BIOS $PIR table. This is needed on
1460 some systems with broken BIOSes, notably
1461 some HP Pavilion N5400 and Omnibook XE3
1462 notebooks. This will have no effect if ACPI
1463 IRQ routing is enabled.
1464 noacpi [X86-32] Do not use ACPI for IRQ routing
1465 or for PCI scanning.
1466 use_crs [X86-32] Use _CRS for PCI resource
1467 allocation.
1468 routeirq Do IRQ routing for all PCI devices.
1469 This is normally done in pci_enable_device(),
1470 so this option is a temporary workaround
1471 for broken drivers that don't call it.
1472 firmware [ARM] Do not re-enumerate the bus but instead
1473 just use the configuration from the
1474 bootloader. This is currently used on
1475 IXP2000 systems where the bus has to be
1476 configured a certain way for adjunct CPUs.
1477 noearly [X86] Don't do any early type 1 scanning.
1478 This might help on some broken boards which
1479 machine check when some devices' config space
1480 is read. But various workarounds are disabled
1481 and some IOMMU drivers will not work.
1482 bfsort Sort PCI devices into breadth-first order.
1483 This sorting is done to get a device
1484 order compatible with older (<= 2.4) kernels.
1485 nobfsort Don't sort PCI devices into breadth-first order.
1486 cbiosize=nn[KMG] The fixed amount of bus space which is
1487 reserved for the CardBus bridge's IO window.
1488 The default value is 256 bytes.
1489 cbmemsize=nn[KMG] The fixed amount of bus space which is
1490 reserved for the CardBus bridge's memory
1491 window. The default value is 64 megabytes.
1493 pcmv= [HW,PCMCIA] BadgePAD 4
1495 pd. [PARIDE]
1496 See Documentation/paride.txt.
1498 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1499 boot time.
1500 Format: { 0 | 1 }
1501 See arch/parisc/kernel/pdc_chassis.c
1503 pf. [PARIDE]
1504 See Documentation/paride.txt.
1506 pg. [PARIDE]
1507 See Documentation/paride.txt.
1509 pirq= [SMP,APIC] Manual mp-table setup
1510 See Documentation/i386/IO-APIC.txt.
1512 plip= [PPT,NET] Parallel port network link
1513 Format: { parport<nr> | timid | 0 }
1514 See also Documentation/parport.txt.
1516 pnpacpi= [ACPI]
1517 { off }
1519 pnpbios= [ISAPNP]
1520 { on | off | curr | res | no-curr | no-res }
1522 pnp_reserve_irq=
1523 [ISAPNP] Exclude IRQs for the autoconfiguration
1525 pnp_reserve_dma=
1526 [ISAPNP] Exclude DMAs for the autoconfiguration
1528 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1529 Ranges are in pairs (I/O port base and size).
1531 pnp_reserve_mem=
1532 [ISAPNP] Exclude memory regions for the
1533 autoconfiguration.
1534 Ranges are in pairs (memory base and size).
1536 print-fatal-signals=
1537 [KNL] debug: print fatal signals
1538 print-fatal-signals=1: print segfault info to
1539 the kernel console.
1540 default: off.
1542 printk.time= Show timing data prefixed to each printk message line
1543 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1545 profile= [KNL] Enable kernel profiling via /proc/profile
1546 Format: [schedule,]<number>
1547 Param: "schedule" - profile schedule points.
1548 Param: <number> - step/bucket size as a power of 2 for
1549 statistical time based profiling.
1550 Param: "sleep" - profile D-state sleeping (millisecs).
1551 Requires CONFIG_SCHEDSTATS
1552 Param: "kvm" - profile VM exits.
1554 processor.max_cstate= [HW,ACPI]
1555 Limit processor to maximum C-state
1556 max_cstate=9 overrides any DMI blacklist limit.
1558 processor.nocst [HW,ACPI]
1559 Ignore the _CST method to determine C-states,
1560 instead using the legacy FADT method
1562 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1563 before loading.
1564 See Documentation/ramdisk.txt.
1566 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1567 probe for; one of (bare|imps|exps|lifebook|any).
1568 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1569 per second.
1570 psmouse.resetafter= [HW,MOUSE]
1571 Try to reset the device after so many bad packets
1572 (0 = never).
1573 psmouse.resolution=
1574 [HW,MOUSE] Set desired mouse resolution, in dpi.
1575 psmouse.smartscroll=
1576 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1577 0 = disabled, 1 = enabled (default).
1579 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1580 Format:
1581 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1583 pt. [PARIDE]
1584 See Documentation/paride.txt.
1586 pty.legacy_count=
1587 [KNL] Number of legacy pty's. Overwrites compiled-in
1588 default number.
1590 quiet [KNL] Disable most log messages
1592 r128= [HW,DRM]
1594 raid= [HW,RAID]
1595 See Documentation/md.txt.
1597 ramdisk_blocksize= [RAM]
1598 See Documentation/ramdisk.txt.
1600 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1601 See Documentation/ramdisk.txt.
1603 rcupdate.blimit= [KNL,BOOT]
1604 Set maximum number of finished RCU callbacks to process
1605 in one batch.
1607 rcupdate.qhimark= [KNL,BOOT]
1608 Set threshold of queued
1609 RCU callbacks over which batch limiting is disabled.
1611 rcupdate.qlowmark= [KNL,BOOT]
1612 Set threshold of queued RCU callbacks below which
1613 batch limiting is re-enabled.
1615 rdinit= [KNL]
1616 Format: <full_path>
1617 Run specified binary instead of /init from the ramdisk,
1618 used for early userspace startup. See initrd.
1620 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1621 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1622 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1624 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1626 reservetop= [X86-32]
1627 Format: nn[KMG]
1628 Reserves a hole at the top of the kernel virtual
1629 address space.
1631 reset_devices [KNL] Force drivers to reset the underlying device
1632 during initialization.
1634 resume= [SWSUSP]
1635 Specify the partition device for software suspend
1637 resume_offset= [SWSUSP]
1638 Specify the offset from the beginning of the partition
1639 given by "resume=" at which the swap header is located,
1640 in <PAGE_SIZE> units (needed only for swap files).
1641 See Documentation/power/swsusp-and-swap-files.txt
1643 retain_initrd [RAM] Keep initrd memory after extraction
1645 rhash_entries= [KNL,NET]
1646 Set number of hash buckets for route cache
1648 riscom8= [HW,SERIAL]
1649 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1651 ro [KNL] Mount root device read-only on boot
1653 root= [KNL] Root filesystem
1655 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1656 mount the root filesystem
1658 rootflags= [KNL] Set root filesystem mount option string
1660 rootfstype= [KNL] Set root filesystem type
1662 rootwait [KNL] Wait (indefinitely) for root device to show up.
1663 Useful for devices that are detected asynchronously
1664 (e.g. USB and MMC devices).
1666 root_plug.vendor_id=
1667 [ROOTPLUG] Override the default vendor ID
1669 root_plug.product_id=
1670 [ROOTPLUG] Override the default product ID
1672 root_plug.debug=
1673 [ROOTPLUG] Enable debugging output
1675 rw [KNL] Mount root device read-write on boot
1677 S [KNL] Run init in single mode
1679 sa1100ir [NET]
1680 See drivers/net/irda/sa1100_ir.c.
1682 sbni= [NET] Granch SBNI12 leased line adapter
1684 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1685 Format: <io>[,<timeout>[,<isapnp>]]
1687 scsi_debug_*= [SCSI]
1688 See drivers/scsi/scsi_debug.c.
1690 scsi_default_dev_flags=
1691 [SCSI] SCSI default device flags
1692 Format: <integer>
1694 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1695 Format: <vendor>:<model>:<flags>
1696 (flags are integer value)
1698 scsi_logging_level= [SCSI] a bit mask of logging levels
1699 See drivers/scsi/scsi_logging.h for bits. Also
1700 settable via sysctl at dev.scsi.logging_level
1701 (/proc/sys/dev/scsi/logging_level).
1702 There is also a nice 'scsi_logging_level' script in the
1703 S390-tools package, available for download at
1704 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1706 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1707 discovered. async scans them in kernel threads,
1708 allowing boot to proceed. none ignores them, expecting
1709 user space to do the scan.
1711 selinux [SELINUX] Disable or enable SELinux at boot time.
1712 Format: { "0" | "1" }
1713 See security/selinux/Kconfig help text.
1714 0 -- disable.
1715 1 -- enable.
1716 Default value is set via kernel config option.
1717 If enabled at boot time, /selinux/disable can be used
1718 later to disable prior to initial policy load.
1720 selinux_compat_net =
1721 [SELINUX] Set initial selinux_compat_net flag value.
1722 Format: { "0" | "1" }
1723 0 -- use new secmark-based packet controls
1724 1 -- use legacy packet controls
1725 Default value is 0 (preferred).
1726 Value can be changed at runtime via
1727 /selinux/compat_net.
1729 serialnumber [BUGS=X86-32]
1731 shapers= [NET]
1732 Maximal number of shapers.
1734 sim710= [SCSI,HW]
1735 See header of drivers/scsi/sim710.c.
1737 simeth= [IA-64]
1738 simscsi=
1740 slram= [HW,MTD]
1742 slub_debug[=options[,slabs]] [MM, SLUB]
1743 Enabling slub_debug allows one to determine the
1744 culprit if slab objects become corrupted. Enabling
1745 slub_debug can create guard zones around objects and
1746 may poison objects when not in use. Also tracks the
1747 last alloc / free. For more information see
1748 Documentation/vm/slub.txt.
1750 slub_max_order= [MM, SLUB]
1751 Determines the maximum allowed order for slabs.
1752 A high setting may cause OOMs due to memory
1753 fragmentation. For more information see
1754 Documentation/vm/slub.txt.
1756 slub_min_objects= [MM, SLUB]
1757 The minimum number of objects per slab. SLUB will
1758 increase the slab order up to slub_max_order to
1759 generate a sufficiently large slab able to contain
1760 the number of objects indicated. The higher the number
1761 of objects the smaller the overhead of tracking slabs
1762 and the less frequently locks need to be acquired.
1763 For more information see Documentation/vm/slub.txt.
1765 slub_min_order= [MM, SLUB]
1766 Determines the mininum page order for slabs. Must be
1767 lower than slub_max_order.
1768 For more information see Documentation/vm/slub.txt.
1770 slub_nomerge [MM, SLUB]
1771 Disable merging of slabs with similar size. May be
1772 necessary if there is some reason to distinguish
1773 allocs to different slabs. Debug options disable
1774 merging on their own.
1775 For more information see Documentation/vm/slub.txt.
1777 smart2= [HW]
1778 Format: <io1>[,<io2>[,...,<io8>]]
1780 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1781 attempt to substitute SMP alternatives once at boot.
1783 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1784 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1785 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1786 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1787 smsc-ircc2.ircc_irq= [HW] IRQ line
1788 smsc-ircc2.ircc_dma= [HW] DMA channel
1789 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1790 0: Toshiba Satellite 1800 (GP data pin select)
1791 1: Fast pin select (default)
1792 2: ATC IRMode
1794 snd-ad1816a= [HW,ALSA]
1796 snd-ad1848= [HW,ALSA]
1798 snd-ali5451= [HW,ALSA]
1800 snd-als100= [HW,ALSA]
1802 snd-als4000= [HW,ALSA]
1804 snd-azt2320= [HW,ALSA]
1806 snd-cmi8330= [HW,ALSA]
1808 snd-cmipci= [HW,ALSA]
1810 snd-cs4231= [HW,ALSA]
1812 snd-cs4232= [HW,ALSA]
1814 snd-cs4236= [HW,ALSA]
1816 snd-cs4281= [HW,ALSA]
1818 snd-cs46xx= [HW,ALSA]
1820 snd-dt019x= [HW,ALSA]
1822 snd-dummy= [HW,ALSA]
1824 snd-emu10k1= [HW,ALSA]
1826 snd-ens1370= [HW,ALSA]
1828 snd-ens1371= [HW,ALSA]
1830 snd-es968= [HW,ALSA]
1832 snd-es1688= [HW,ALSA]
1834 snd-es18xx= [HW,ALSA]
1836 snd-es1938= [HW,ALSA]
1838 snd-es1968= [HW,ALSA]
1840 snd-fm801= [HW,ALSA]
1842 snd-gusclassic= [HW,ALSA]
1844 snd-gusextreme= [HW,ALSA]
1846 snd-gusmax= [HW,ALSA]
1848 snd-hdsp= [HW,ALSA]
1850 snd-ice1712= [HW,ALSA]
1852 snd-intel8x0= [HW,ALSA]
1854 snd-interwave= [HW,ALSA]
1856 snd-interwave-stb=
1857 [HW,ALSA]
1859 snd-korg1212= [HW,ALSA]
1861 snd-maestro3= [HW,ALSA]
1863 snd-mpu401= [HW,ALSA]
1865 snd-mtpav= [HW,ALSA]
1867 snd-nm256= [HW,ALSA]
1869 snd-opl3sa2= [HW,ALSA]
1871 snd-opti92x-ad1848=
1872 [HW,ALSA]
1874 snd-opti92x-cs4231=
1875 [HW,ALSA]
1877 snd-opti93x= [HW,ALSA]
1879 snd-pmac= [HW,ALSA]
1881 snd-rme32= [HW,ALSA]
1883 snd-rme96= [HW,ALSA]
1885 snd-rme9652= [HW,ALSA]
1887 snd-sb8= [HW,ALSA]
1889 snd-sb16= [HW,ALSA]
1891 snd-sbawe= [HW,ALSA]
1893 snd-serial= [HW,ALSA]
1895 snd-sgalaxy= [HW,ALSA]
1897 snd-sonicvibes= [HW,ALSA]
1899 snd-sun-amd7930=
1900 [HW,ALSA]
1902 snd-sun-cs4231= [HW,ALSA]
1904 snd-trident= [HW,ALSA]
1906 snd-usb-audio= [HW,ALSA,USB]
1908 snd-via82xx= [HW,ALSA]
1910 snd-virmidi= [HW,ALSA]
1912 snd-wavefront= [HW,ALSA]
1914 snd-ymfpci= [HW,ALSA]
1916 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1917 See Documentation/sonypi.txt
1919 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1920 See Documentation/specialix.txt.
1922 spia_io_base= [HW,MTD]
1923 spia_fio_base=
1924 spia_pedr=
1925 spia_peddr=
1927 sscape= [HW,OSS]
1928 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1930 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1931 See Documentation/scsi/st.txt.
1933 sti= [PARISC,HW]
1934 Format: <num>
1935 Set the STI (builtin display/keyboard on the HP-PARISC
1936 machines) console (graphic card) which should be used
1937 as the initial boot-console.
1938 See also comment in drivers/video/console/sticore.c.
1940 sti_font= [HW]
1941 See comment in drivers/video/console/sticore.c.
1943 stifb= [HW]
1944 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1946 sunrpc.pool_mode=
1947 [NFS]
1948 Control how the NFS server code allocates CPUs to
1949 service thread pools. Depending on how many NICs
1950 you have and where their interrupts are bound, this
1951 option will affect which CPUs will do NFS serving.
1952 Note: this parameter cannot be changed while the
1953 NFS server is running.
1955 auto the server chooses an appropriate mode
1956 automatically using heuristics
1957 global a single global pool contains all CPUs
1958 percpu one pool for each CPU
1959 pernode one pool for each NUMA node (equivalent
1960 to global on non-NUMA machines)
1962 swiotlb= [IA-64] Number of I/O TLB slabs
1964 switches= [HW,M68k]
1966 sym53c416= [HW,SCSI]
1967 See header of drivers/scsi/sym53c416.c.
1969 sysrq_always_enabled
1970 [KNL]
1971 Ignore sysrq setting - this boot parameter will
1972 neutralize any effect of /proc/sys/kernel/sysrq.
1973 Useful for debugging.
1975 t128= [HW,SCSI]
1976 See header of drivers/scsi/t128.c.
1978 tdfx= [HW,DRM]
1980 thash_entries= [KNL,NET]
1981 Set number of hash buckets for TCP connection
1983 thermal.act= [HW,ACPI]
1984 -1: disable all active trip points in all thermal zones
1985 <degrees C>: override all lowest active trip points
1987 thermal.crt= [HW,ACPI]
1988 -1: disable all critical trip points in all thermal zones
1989 <degrees C>: lower all critical trip points
1991 thermal.nocrt= [HW,ACPI]
1992 Set to disable actions on ACPI thermal zone
1993 critical and hot trip points.
1995 thermal.off= [HW,ACPI]
1996 1: disable ACPI thermal control
1998 thermal.psv= [HW,ACPI]
1999 -1: disable all passive trip points
2000 <degrees C>: override all passive trip points to this value
2002 thermal.tzp= [HW,ACPI]
2003 Specify global default ACPI thermal zone polling rate
2004 <deci-seconds>: poll all this frequency
2005 0: no polling (default)
2007 tipar.timeout= [HW,PPT]
2008 Set communications timeout in tenths of a second
2009 (default 15).
2011 tipar.delay= [HW,PPT]
2012 Set inter-bit delay in microseconds (default 10).
2014 tmscsim= [HW,SCSI]
2015 See comment before function dc390_setup() in
2016 drivers/scsi/tmscsim.c.
2018 tp720= [HW,PS2]
2020 trix= [HW,OSS] MediaTrix AudioTrix Pro
2021 Format:
2022 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2024 turbografx.map[2|3]= [HW,JOY]
2025 TurboGraFX parallel port interface
2026 Format:
2027 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2028 See also Documentation/input/joystick-parport.txt
2030 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2031 See header of drivers/scsi/u14-34f.c.
2033 uart401= [HW,OSS]
2034 Format: <io>,<irq>
2036 uart6850= [HW,OSS]
2037 Format: <io>,<irq>
2039 uhci-hcd.ignore_oc=
2040 [USB] Ignore overcurrent events (default N).
2041 Some badly-designed motherboards generate lots of
2042 bogus events, for ports that aren't wired to
2043 anything. Set this parameter to avoid log spamming.
2044 Note that genuine overcurrent events won't be
2045 reported either.
2047 usbcore.autosuspend=
2048 [USB] The autosuspend time delay (in seconds) used
2049 for newly-detected USB devices (default 2). This
2050 is the time required before an idle device will be
2051 autosuspended. Devices for which the delay is set
2052 to a negative value won't be autosuspended at all.
2054 usbhid.mousepoll=
2055 [USBHID] The interval which mice are to be polled at.
2057 vdso= [X86-32,SH,x86-64]
2058 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2059 vdso=1: enable VDSO (default)
2060 vdso=0: disable VDSO mapping
2062 vdso32= [X86-32,X86-64]
2063 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2064 vdso32=1: enable 32-bit VDSO (default)
2065 vdso32=0: disable 32-bit VDSO mapping
2067 vector= [IA-64,SMP]
2068 vector=percpu: enable percpu vector domain
2070 video= [FB] Frame buffer configuration
2071 See Documentation/fb/modedb.txt.
2073 vga= [BOOT,X86-32] Select a particular video mode
2074 See Documentation/i386/boot.txt and
2075 Documentation/svga.txt.
2076 Use vga=ask for menu.
2077 This is actually a boot loader parameter; the value is
2078 passed to the kernel using a special protocol.
2080 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2081 size of <nn>. This can be used to increase the
2082 minimum size (128MB on x86). It can also be used to
2083 decrease the size and leave more room for directly
2084 mapped kernel RAM.
2086 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2087 Format: <command>
2089 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2090 Format: <command>
2092 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2093 Format: <command>
2095 waveartist= [HW,OSS]
2096 Format: <io>,<irq>,<dma>,<dma2>
2098 wd33c93= [HW,SCSI]
2099 See header of drivers/scsi/wd33c93.c.
2101 wd7000= [HW,SCSI]
2102 See header of drivers/scsi/wd7000.c.
2104 wdt= [WDT] Watchdog
2105 See Documentation/watchdog/wdt.txt.
2107 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2108 xd_geo= See header of drivers/block/xd.c.
2110 xirc2ps_cs= [NET,PCMCIA]
2111 Format:
2112 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2114 norandmaps Don't use address space randomization
2115 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2117 ______________________________________________________________________
2119 TODO:
2121 Add documentation for ALSA options.
2122 Add more DRM drivers.