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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 security= [SECURITY] Choose a security module to enable at boot.
370 If this boot parameter is not specified, only the first
371 security module asking for security registration will be
372 loaded. An invalid security module name will be treated
373 as if no module has been chosen.
375 capability.disable=
376 [SECURITY] Disable capabilities. This would normally
377 be used only if an alternative security model is to be
378 configured. Potentially dangerous and should only be
379 used if you are entirely sure of the consequences.
381 ccw_timeout_log [S390]
382 See Documentation/s390/CommonIO for details.
384 cgroup_disable= [KNL] Disable a particular controller
385 Format: {name of the controller(s) to disable}
386 {Currently supported controllers - "memory"}
388 checkreqprot [SELINUX] Set initial checkreqprot flag value.
389 Format: { "0" | "1" }
390 See security/selinux/Kconfig help text.
391 0 -- check protection applied by kernel (includes
392 any implied execute protection).
393 1 -- check protection requested by application.
394 Default value is set via a kernel config option.
395 Value can be changed at runtime via
396 /selinux/checkreqprot.
398 cio_ignore= [S390]
399 See Documentation/s390/CommonIO for details.
401 cio_msg= [S390]
402 See Documentation/s390/CommonIO for details.
404 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
405 [Deprecated]
406 Forces specified clocksource (if available) to be used
407 when calculating gettimeofday(). If specified
408 clocksource is not available, it defaults to PIT.
409 Format: { pit | tsc | cyclone | pmtmr }
411 clocksource= [GENERIC_TIME] Override the default clocksource
412 Format: <string>
413 Override the default clocksource and use the clocksource
414 with the name specified.
415 Some clocksource names to choose from, depending on
416 the platform:
417 [all] jiffies (this is the base, fallback clocksource)
418 [ACPI] acpi_pm
419 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
420 pxa_timer,timer3,32k_counter,timer0_1
421 [AVR32] avr32
422 [X86-32] pit,hpet,tsc,vmi-timer;
423 scx200_hrt on Geode; cyclone on IBM x440
424 [MIPS] MIPS
425 [PARISC] cr16
426 [S390] tod
427 [SH] SuperH
428 [SPARC64] tick
429 [X86-64] hpet,tsc
431 clearcpuid=BITNUM [X86]
432 Disable CPUID feature X for the kernel. See
433 include/asm-x86/cpufeature.h for the valid bit numbers.
434 Note the Linux specific bits are not necessarily
435 stable over kernel options, but the vendor specific
436 ones should be.
437 Also note that user programs calling CPUID directly
438 or using the feature without checking anything
439 will still see it. This just prevents it from
440 being used by the kernel or shown in /proc/cpuinfo.
441 Also note the kernel might malfunction if you disable
442 some critical bits.
444 code_bytes [IA32/X86_64] How many bytes of object code to print
445 in an oops report.
446 Range: 0 - 8192
447 Default: 64
449 disable_8254_timer
450 enable_8254_timer
451 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
452 over the 8254 in addition to over the IO-APIC. The
453 kernel tries to set a sensible default.
455 hpet= [X86-32,HPET] option to control HPET usage
456 Format: { enable (default) | disable | force }
457 disable: disable HPET and use PIT instead
458 force: allow force enabled of undocumented chips (ICH4,
459 VIA, nVidia)
461 com20020= [HW,NET] ARCnet - COM20020 chipset
462 Format:
463 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
465 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
466 Format: <io>[,<irq>]
468 com90xx= [HW,NET]
469 ARCnet - COM90xx chipset (memory-mapped buffers)
470 Format: <io>[,<irq>[,<memstart>]]
472 condev= [HW,S390] console device
473 conmode=
475 console= [KNL] Output console device and options.
477 tty<n> Use the virtual console device <n>.
479 ttyS<n>[,options]
480 ttyUSB0[,options]
481 Use the specified serial port. The options are of
482 the form "bbbbpnf", where "bbbb" is the baud rate,
483 "p" is parity ("n", "o", or "e"), "n" is number of
484 bits, and "f" is flow control ("r" for RTS or
485 omit it). Default is "9600n8".
487 See Documentation/serial-console.txt for more
488 information. See
489 Documentation/networking/netconsole.txt for an
490 alternative.
492 uart[8250],io,<addr>[,options]
493 uart[8250],mmio,<addr>[,options]
494 Start an early, polled-mode console on the 8250/16550
495 UART at the specified I/O port or MMIO address,
496 switching to the matching ttyS device later. The
497 options are the same as for ttyS, above.
499 earlycon= [KNL] Output early console device and options.
500 uart[8250],io,<addr>[,options]
501 uart[8250],mmio,<addr>[,options]
502 Start an early, polled-mode console on the 8250/16550
503 UART at the specified I/O port or MMIO address.
504 The options are the same as for ttyS, above.
506 no_console_suspend
507 [HW] Never suspend the console
508 Disable suspending of consoles during suspend and
509 hibernate operations. Once disabled, debugging
510 messages can reach various consoles while the rest
511 of the system is being put to sleep (ie, while
512 debugging driver suspend/resume hooks). This may
513 not work reliably with all consoles, but is known
514 to work with serial and VGA consoles.
516 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
517 Format:
518 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
520 crashkernel=nn[KMG]@ss[KMG]
521 [KNL] Reserve a chunk of physical memory to
522 hold a kernel to switch to with kexec on panic.
524 crashkernel=range1:size1[,range2:size2,...][@offset]
525 [KNL] Same as above, but depends on the memory
526 in the running system. The syntax of range is
527 start-[end] where start and end are both
528 a memory unit (amount[KMG]). See also
529 Documentation/kdump/kdump.txt for a example.
531 cs4232= [HW,OSS]
532 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
534 cs89x0_dma= [HW,NET]
535 Format: <dma>
537 cs89x0_media= [HW,NET]
538 Format: { rj45 | aui | bnc }
540 dasd= [HW,NET]
541 See header of drivers/s390/block/dasd_devmap.c.
543 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
544 (one device per port)
545 Format: <port#>,<type>
546 See also Documentation/input/joystick-parport.txt
548 debug [KNL] Enable kernel debugging (events log level).
550 debug_locks_verbose=
551 [KNL] verbose self-tests
552 Format=<0|1>
553 Print debugging info while doing the locking API
554 self-tests.
555 We default to 0 (no extra messages), setting it to
556 1 will print _a lot_ more information - normally
557 only useful to kernel developers.
559 decnet.addr= [HW,NET]
560 Format: <area>[,<node>]
561 See also Documentation/networking/decnet.txt.
563 vt.default_blu= [VT]
564 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
565 Change the default blue palette of the console.
566 This is a 16-member array composed of values
567 ranging from 0-255.
569 vt.default_grn= [VT]
570 Format: <green0>,<green1>,<green2>,...,<green15>
571 Change the default green palette of the console.
572 This is a 16-member array composed of values
573 ranging from 0-255.
575 vt.default_red= [VT]
576 Format: <red0>,<red1>,<red2>,...,<red15>
577 Change the default red palette of the console.
578 This is a 16-member array composed of values
579 ranging from 0-255.
581 vt.default_utf8=
582 [VT]
583 Format=<0|1>
584 Set system-wide default UTF-8 mode for all tty's.
585 Default is 1, i.e. UTF-8 mode is enabled for all
586 newly opened terminals.
588 dhash_entries= [KNL]
589 Set number of hash buckets for dentry cache.
591 digi= [HW,SERIAL]
592 IO parameters + enable/disable command.
594 digiepca= [HW,SERIAL]
595 See drivers/char/README.epca and
596 Documentation/digiepca.txt.
598 disable_mtrr_trim [X86, Intel and AMD only]
599 By default the kernel will trim any uncacheable
600 memory out of your available memory pool based on
601 MTRR settings. This parameter disables that behavior,
602 possibly causing your machine to run very slowly.
604 dmasound= [HW,OSS] Sound subsystem buffers
606 dscc4.setup= [NET]
608 dtc3181e= [HW,SCSI]
610 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
611 earlyprintk=vga
612 earlyprintk=serial[,ttySn[,baudrate]]
614 Append ",keep" to not disable it when the real console
615 takes over.
617 Only vga or serial at a time, not both.
619 Currently only ttyS0 and ttyS1 are supported.
621 Interaction with the standard serial driver is not
622 very good.
624 The VGA output is eventually overwritten by the real
625 console.
627 eata= [HW,SCSI]
629 edd= [EDD]
630 Format: {"off" | "on" | "skip[mbr]"}
632 eisa_irq_edge= [PARISC,HW]
633 See header of drivers/parisc/eisa.c.
635 elanfreq= [X86-32]
636 See comment before function elanfreq_setup() in
637 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
639 elevator= [IOSCHED]
640 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
641 See Documentation/block/as-iosched.txt and
642 Documentation/block/deadline-iosched.txt for details.
644 elfcorehdr= [X86-32, X86_64]
645 Specifies physical address of start of kernel core
646 image elf header. Generally kexec loader will
647 pass this option to capture kernel.
648 See Documentation/kdump/kdump.txt for details.
650 enforcing [SELINUX] Set initial enforcing status.
651 Format: {"0" | "1"}
652 See security/selinux/Kconfig help text.
653 0 -- permissive (log only, no denials).
654 1 -- enforcing (deny and log).
655 Default value is 0.
656 Value can be changed at runtime via /selinux/enforce.
658 es1371= [HW,OSS]
659 Format: <spdif>,[<nomix>,[<amplifier>]]
660 See also header of sound/oss/es1371.c.
662 ether= [HW,NET] Ethernet cards parameters
663 This option is obsoleted by the "netdev=" option, which
664 has equivalent usage. See its documentation for details.
666 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
667 Format: <io>[,<irq>]
669 failslab=
670 fail_page_alloc=
671 fail_make_request=[KNL]
672 General fault injection mechanism.
673 Format: <interval>,<probability>,<space>,<times>
674 See also /Documentation/fault-injection/.
676 fd_mcs= [HW,SCSI]
677 See header of drivers/scsi/fd_mcs.c.
679 fdomain= [HW,SCSI]
680 See header of drivers/scsi/fdomain.c.
682 floppy= [HW]
683 See Documentation/floppy.txt.
685 gamecon.map[2|3]=
686 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
687 support via parallel port (up to 5 devices per port)
688 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
689 See also Documentation/input/joystick-parport.txt
691 gamma= [HW,DRM]
693 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
694 Format: off | on
695 default: on
697 gdth= [HW,SCSI]
698 See header of drivers/scsi/gdth.c.
700 gpt [EFI] Forces disk with valid GPT signature but
701 invalid Protective MBR to be treated as GPT.
703 gvp11= [HW,SCSI]
705 hashdist= [KNL,NUMA] Large hashes allocated during boot
706 are distributed across NUMA nodes. Defaults on
707 for IA-64, off otherwise.
708 Format: 0 | 1 (for off | on)
710 hcl= [IA-64] SGI's Hardware Graph compatibility layer
712 hd= [EIDE] (E)IDE hard drive subsystem geometry
713 Format: <cyl>,<head>,<sect>
715 hd?= [HW] (E)IDE subsystem
716 hd?lun= See Documentation/ide/ide.txt.
718 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
719 size of <nn>. This works even on boxes that have no
720 highmem otherwise. This also works to reduce highmem
721 size on bigger boxes.
723 highres= [KNL] Enable/disable high resolution timer mode.
724 Valid parameters: "on", "off"
725 Default: "on"
727 hisax= [HW,ISDN]
728 See Documentation/isdn/README.HiSax.
730 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
731 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
733 i8042.direct [HW] Put keyboard port into non-translated mode
734 i8042.dumbkbd [HW] Pretend that controller can only read data from
735 keyboard and cannot control its state
736 (Don't attempt to blink the leds)
737 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
738 i8042.nokbd [HW] Don't check/create keyboard port
739 i8042.noloop [HW] Disable the AUX Loopback command while probing
740 for the AUX port
741 i8042.nomux [HW] Don't check presence of an active multiplexing
742 controller
743 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
744 controllers
745 i8042.panicblink=
746 [HW] Frequency with which keyboard LEDs should blink
747 when kernel panics (default is 0.5 sec)
748 i8042.reset [HW] Reset the controller during init and cleanup
749 i8042.unlock [HW] Unlock (ignore) the keylock
751 i810= [HW,DRM]
753 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
754 indicates that the driver is running on unsupported
755 hardware.
756 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
757 does not match list of supported models.
758 i8k.power_status
759 [HW] Report power status in /proc/i8k
760 (disabled by default)
761 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
762 capability is set.
764 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
765 See Documentation/mca.txt.
767 icn= [HW,ISDN]
768 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
770 ide= [HW] (E)IDE subsystem
771 Format: ide=nodma or ide=doubler
772 See Documentation/ide/ide.txt.
774 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
775 See Documentation/ide/ide.txt.
777 idle= [X86]
778 Format: idle=poll or idle=mwait
779 Poll forces a polling idle loop that can slightly improves the performance
780 of waking up a idle CPU, but will use a lot of power and make the system
781 run hot. Not recommended.
782 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
783 to not use it because it doesn't save as much power as a normal idle
784 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
785 as idle=poll.
787 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
788 Claim all unknown PCI IDE storage controllers.
790 ignore_loglevel [KNL]
791 Ignore loglevel setting - this will print /all/
792 kernel messages to the console. Useful for debugging.
794 ihash_entries= [KNL]
795 Set number of hash buckets for inode cache.
797 in2000= [HW,SCSI]
798 See header of drivers/scsi/in2000.c.
800 init= [KNL]
801 Format: <full_path>
802 Run specified binary instead of /sbin/init as init
803 process.
805 initcall_debug [KNL] Trace initcalls as they are executed. Useful
806 for working out where the kernel is dying during
807 startup.
809 initrd= [BOOT] Specify the location of the initial ramdisk
811 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
812 Format: <irq>
814 inttest= [IA64]
816 iommu= [x86]
817 off
818 force
819 noforce
820 biomerge
821 panic
822 nopanic
823 merge
824 nomerge
825 forcesac
826 soft
829 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
830 off
831 Disable intel iommu driver.
832 igfx_off [Default Off]
833 By default, gfx is mapped as normal device. If a gfx
834 device has a dedicated DMAR unit, the DMAR unit is
835 bypassed by not enabling DMAR with this option. In
836 this case, gfx device will use physical address for
837 DMA.
838 forcedac [x86_64]
839 With this option iommu will not optimize to look
840 for io virtual address below 32 bit forcing dual
841 address cycle on pci bus for cards supporting greater
842 than 32 bit addressing. The default is to look
843 for translation below 32 bit and if not available
844 then look in the higher range.
845 strict [Default Off]
846 With this option on every unmap_single operation will
847 result in a hardware IOTLB flush operation as opposed
848 to batching them for performance.
850 io_delay= [X86-32,X86-64] I/O delay method
851 0x80
852 Standard port 0x80 based delay
853 0xed
854 Alternate port 0xed based delay (needed on some systems)
855 udelay
856 Simple two microseconds delay
857 none
858 No delay
860 io7= [HW] IO7 for Marvel based alpha systems
861 See comment before marvel_specify_io7 in
862 arch/alpha/kernel/core_marvel.c.
864 ip= [IP_PNP]
865 See Documentation/filesystems/nfsroot.txt.
867 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
868 See comment before ip2_setup() in
869 drivers/char/ip2/ip2base.c.
871 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
872 See header of drivers/scsi/ips.c.
874 ports= [IP_VS_FTP] IPVS ftp helper module
875 Default is 21.
876 Up to 8 (IP_VS_APP_MAX_PORTS) ports
877 may be specified.
878 Format: <port>,<port>....
880 irqfixup [HW]
881 When an interrupt is not handled search all handlers
882 for it. Intended to get systems with badly broken
883 firmware running.
885 irqpoll [HW]
886 When an interrupt is not handled search all handlers
887 for it. Also check all handlers each timer
888 interrupt. Intended to get systems with badly broken
889 firmware running.
891 isapnp= [ISAPNP]
892 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
894 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
895 Format:
896 <cpu number>,...,<cpu number>
897 or
898 <cpu number>-<cpu number> (must be a positive range in ascending order)
899 or a mixture
900 <cpu number>,...,<cpu number>-<cpu number>
901 This option can be used to specify one or more CPUs
902 to isolate from the general SMP balancing and scheduling
903 algorithms. The only way to move a process onto or off
904 an "isolated" CPU is via the CPU affinity syscalls.
905 <cpu number> begins at 0 and the maximum value is
906 "number of CPUs in system - 1".
908 This option is the preferred way to isolate CPUs. The
909 alternative -- manually setting the CPU mask of all
910 tasks in the system -- can cause problems and
911 suboptimal load balancer performance.
913 iucv= [HW,NET]
915 js= [HW,JOY] Analog joystick
916 See Documentation/input/joystick.txt.
918 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
919 specifies the amount of memory usable by the kernel
920 for non-movable allocations. The requested amount is
921 spread evenly throughout all nodes in the system. The
922 remaining memory in each node is used for Movable
923 pages. In the event, a node is too small to have both
924 kernelcore and Movable pages, kernelcore pages will
925 take priority and other nodes will have a larger number
926 of kernelcore pages. The Movable zone is used for the
927 allocation of pages that may be reclaimed or moved
928 by the page migration subsystem. This means that
929 HugeTLB pages may not be allocated from this zone.
930 Note that allocations like PTEs-from-HighMem still
931 use the HighMem zone if it exists, and the Normal
932 zone if it does not.
934 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
935 is similar to kernelcore except it specifies the
936 amount of memory used for migratable allocations.
937 If both kernelcore and movablecore is specified,
938 then kernelcore will be at *least* the specified
939 value but may be more. If movablecore on its own
940 is specified, the administrator must be careful
941 that the amount of memory usable for all allocations
942 is not too small.
944 keepinitrd [HW,ARM]
946 kstack=N [X86-32,X86-64] Print N words from the kernel stack
947 in oops dumps.
949 kgdboc= [HW] kgdb over consoles.
950 Requires a tty driver that supports console polling.
951 (only serial suported for now)
952 Format: <serial_device>[,baud]
954 l2cr= [PPC]
956 l3cr= [PPC]
958 lapic [X86-32,APIC] Enable the local APIC even if BIOS
959 disabled it.
961 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
962 C2 power state.
964 libata.dma= [LIBATA] DMA control
965 libata.dma=0 Disable all PATA and SATA DMA
966 libata.dma=1 PATA and SATA Disk DMA only
967 libata.dma=2 ATAPI (CDROM) DMA only
968 libata.dma=4 Compact Flash DMA only
969 Combinations also work, so libata.dma=3 enables DMA
970 for disks and CDROMs, but not CFs.
972 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
973 when set.
974 Format: <int>
976 libata.force= [LIBATA] Force configurations. The format is comma
977 separated list of "[ID:]VAL" where ID is
978 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
979 matching port, link or device. Basically, it matches
980 the ATA ID string printed on console by libata. If
981 the whole ID part is omitted, the last PORT and DEVICE
982 values are used. If ID hasn't been specified yet, the
983 configuration applies to all ports, links and devices.
985 If only DEVICE is omitted, the parameter applies to
986 the port and all links and devices behind it. DEVICE
987 number of 0 either selects the first device or the
988 first fan-out link behind PMP device. It does not
989 select the host link. DEVICE number of 15 selects the
990 host link and device attached to it.
992 The VAL specifies the configuration to force. As long
993 as there's no ambiguity shortcut notation is allowed.
994 For example, both 1.5 and 1.5G would work for 1.5Gbps.
995 The following configurations can be forced.
997 * Cable type: 40c, 80c, short40c, unk, ign or sata.
998 Any ID with matching PORT is used.
1000 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1002 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1003 udma[/][16,25,33,44,66,100,133] notation is also
1004 allowed.
1006 * [no]ncq: Turn on or off NCQ.
1008 If there are multiple matching configurations changing
1009 the same attribute, the last one is used.
1011 load_ramdisk= [RAM] List of ramdisks to load from floppy
1012 See Documentation/ramdisk.txt.
1014 lockd.nlm_grace_period=P [NFS] Assign grace period.
1015 Format: <integer>
1017 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1018 Format: <integer>
1020 lockd.nlm_timeout=T [NFS] Assign timeout value.
1021 Format: <integer>
1023 lockd.nlm_udpport=M [NFS] Assign UDP port.
1024 Format: <integer>
1026 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1027 Format: <irq>
1029 loglevel= All Kernel Messages with a loglevel smaller than the
1030 console loglevel will be printed to the console. It can
1031 also be changed with klogd or other programs. The
1032 loglevels are defined as follows:
1034 0 (KERN_EMERG) system is unusable
1035 1 (KERN_ALERT) action must be taken immediately
1036 2 (KERN_CRIT) critical conditions
1037 3 (KERN_ERR) error conditions
1038 4 (KERN_WARNING) warning conditions
1039 5 (KERN_NOTICE) normal but significant condition
1040 6 (KERN_INFO) informational
1041 7 (KERN_DEBUG) debug-level messages
1043 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1044 Format: { n | nk | nM }
1045 n must be a power of two. The default size
1046 is set in the kernel config file.
1048 logo.nologo [FB] Disables display of the built-in Linux logo.
1049 This may be used to provide more screen space for
1050 kernel log messages and is useful when debugging
1051 kernel boot problems.
1053 lp=0 [LP] Specify parallel ports to use, e.g,
1054 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1055 lp=reset first parallel port). 'lp=0' disables the
1056 lp=auto printer driver. 'lp=reset' (which can be
1057 specified in addition to the ports) causes
1058 attached printers to be reset. Using
1059 lp=port1,port2,... specifies the parallel ports
1060 to associate lp devices with, starting with
1061 lp0. A port specification may be 'none' to skip
1062 that lp device, or a parport name such as
1063 'parport0'. Specifying 'lp=auto' instead of a
1064 port specification list means that device IDs
1065 from each port should be examined, to see if
1066 an IEEE 1284-compliant printer is attached; if
1067 so, the driver will manage that printer.
1068 See also header of drivers/char/lp.c.
1070 lpj=n [KNL]
1071 Sets loops_per_jiffy to given constant, thus avoiding
1072 time-consuming boot-time autodetection (up to 250 ms per
1073 CPU). 0 enables autodetection (default). To determine
1074 the correct value for your kernel, boot with normal
1075 autodetection and see what value is printed. Note that
1076 on SMP systems the preset will be applied to all CPUs,
1077 which is likely to cause problems if your CPUs need
1078 significantly divergent settings. An incorrect value
1079 will cause delays in the kernel to be wrong, leading to
1080 unpredictable I/O errors and other breakage. Although
1081 unlikely, in the extreme case this might damage your
1082 hardware.
1084 ltpc= [NET]
1085 Format: <io>,<irq>,<dma>
1087 mac5380= [HW,SCSI] Format:
1088 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1090 mac53c9x= [HW,SCSI] Format:
1091 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1093 machvec= [IA64] Force the use of a particular machine-vector
1094 (machvec) in a generic kernel.
1095 Example: machvec=hpzx1_swiotlb
1097 max_loop= [LOOP] Maximum number of loopback devices that can
1098 be mounted
1099 Format: <1-256>
1101 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1102 should make use of. maxcpus=n : n >= 0 limits the
1103 kernel to using 'n' processors. n=0 is a special case,
1104 it is equivalent to "nosmp", which also disables
1105 the IO APIC.
1107 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1108 equal to this physical address is ignored.
1110 max_luns= [SCSI] Maximum number of LUNs to probe.
1111 Should be between 1 and 2^32-1.
1113 max_report_luns=
1114 [SCSI] Maximum number of LUNs received.
1115 Should be between 1 and 16384.
1117 mcatest= [IA-64]
1119 mce [X86-32] Machine Check Exception
1121 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1123 md= [HW] RAID subsystems devices and level
1124 See Documentation/md.txt.
1126 mdacon= [MDA]
1127 Format: <first>,<last>
1128 Specifies range of consoles to be captured by the MDA.
1130 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1131 Amount of memory to be used when the kernel is not able
1132 to see the whole system memory or for test.
1133 [X86-32] Use together with memmap= to avoid physical
1134 address space collisions. Without memmap= PCI devices
1135 could be placed at addresses belonging to unused RAM.
1137 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1138 memory.
1140 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1141 E820 memory map, as specified by the user.
1142 Such memmap=exactmap lines can be constructed based on
1143 BIOS output or other requirements. See the memmap=nn@ss
1144 option description.
1146 memmap=nn[KMG]@ss[KMG]
1147 [KNL] Force usage of a specific region of memory
1148 Region of memory to be used, from ss to ss+nn.
1150 memmap=nn[KMG]#ss[KMG]
1151 [KNL,ACPI] Mark specific memory as ACPI data.
1152 Region of memory to be used, from ss to ss+nn.
1154 memmap=nn[KMG]$ss[KMG]
1155 [KNL,ACPI] Mark specific memory as reserved.
1156 Region of memory to be used, from ss to ss+nn.
1157 Example: Exclude memory from 0x18690000-0x1869ffff
1158 memmap=64K$0x18690000
1159 or
1160 memmap=0x10000$0x18690000
1162 memtest= [KNL,X86_64] Enable memtest
1163 Format: <integer>
1164 range: 0,4 : pattern number
1165 default : 0 <disable>
1167 meye.*= [HW] Set MotionEye Camera parameters
1168 See Documentation/video4linux/meye.txt.
1170 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1171 Multi-Function General Purpose Timers on AMD Geode
1172 platforms.
1174 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1175 the BIOS has incorrectly applied a workaround. TinyBIOS
1176 version 0.98 is known to be affected, 0.99 fixes the
1177 problem by letting the user disable the workaround.
1179 mga= [HW,DRM]
1181 mousedev.tap_time=
1182 [MOUSE] Maximum time between finger touching and
1183 leaving touchpad surface for touch to be considered
1184 a tap and be reported as a left button click (for
1185 touchpads working in absolute mode only).
1186 Format: <msecs>
1187 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1188 reporting absolute coordinates, such as tablets
1189 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1190 reporting absolute coordinates, such as tablets
1192 mpu401= [HW,OSS]
1193 Format: <io>,<irq>
1195 MTD_Partition= [MTD]
1196 Format: <name>,<region-number>,<size>,<offset>
1198 MTD_Region= [MTD] Format:
1199 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1201 mtdparts= [MTD]
1202 See drivers/mtd/cmdlinepart.c.
1204 mtouchusb.raw_coordinates=
1205 [HW] Make the MicroTouch USB driver use raw coordinates
1206 ('y', default) or cooked coordinates ('n')
1208 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1210 NCR_D700= [HW,SCSI]
1211 See header of drivers/scsi/NCR_D700.c.
1213 ncr5380= [HW,SCSI]
1215 ncr53c400= [HW,SCSI]
1217 ncr53c400a= [HW,SCSI]
1219 ncr53c406a= [HW,SCSI]
1221 ncr53c8xx= [HW,SCSI]
1223 netdev= [NET] Network devices parameters
1224 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1225 Note that mem_start is often overloaded to mean
1226 something different and driver-specific.
1227 This usage is only documented in each driver source
1228 file if at all.
1230 nfsaddrs= [NFS]
1231 See Documentation/filesystems/nfsroot.txt.
1233 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1234 See Documentation/filesystems/nfsroot.txt.
1236 nfs.callback_tcpport=
1237 [NFS] set the TCP port on which the NFSv4 callback
1238 channel should listen.
1240 nfs.idmap_cache_timeout=
1241 [NFS] set the maximum lifetime for idmapper cache
1242 entries.
1244 nfs.enable_ino64=
1245 [NFS] enable 64-bit inode numbers.
1246 If zero, the NFS client will fake up a 32-bit inode
1247 number for the readdir() and stat() syscalls instead
1248 of returning the full 64-bit number.
1249 The default is to return 64-bit inode numbers.
1251 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1252 when a NMI is triggered.
1253 Format: [state][,regs][,debounce][,die]
1255 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1257 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1258 emulation library even if a 387 maths coprocessor
1259 is present.
1261 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1262 caches in the slab allocator. Saves per-node memory,
1263 but will impact performance.
1265 noalign [KNL,ARM]
1267 noapic [SMP,APIC] Tells the kernel to not make use of any
1268 IOAPICs that may be present in the system.
1270 nobats [PPC] Do not use BATs for mapping kernel lowmem
1271 on "Classic" PPC cores.
1273 nocache [ARM]
1275 nodelayacct [KNL] Disable per-task delay accounting
1277 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1279 noefi [X86-32,X86-64] Disable EFI runtime services support.
1281 noexec [IA-64]
1283 noexec [X86-32,X86-64]
1284 On X86-32 available only on PAE configured kernels.
1285 noexec=on: enable non-executable mappings (default)
1286 noexec=off: disable non-executable mappings
1288 noexec32 [X86-64]
1289 This affects only 32-bit executables.
1290 noexec32=on: enable non-executable mappings (default)
1291 read doesn't imply executable mappings
1292 noexec32=off: disable non-executable mappings
1293 read implies executable mappings
1295 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1296 register save and restore. The kernel will only save
1297 legacy floating-point registers on task switch.
1299 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1301 nohlt [BUGS=ARM]
1303 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1304 instruction doesn't work correctly and not to
1305 use it.
1307 nohalt [IA-64] Tells the kernel not to use the power saving
1308 function PAL_HALT_LIGHT when idle. This increases
1309 power-consumption. On the positive side, it reduces
1310 interrupt wake-up latency, which may improve performance
1311 in certain environments such as networked servers or
1312 real-time systems.
1314 nohz= [KNL] Boottime enable/disable dynamic ticks
1315 Valid arguments: on, off
1316 Default: on
1318 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1320 noirqdebug [X86-32] Disables the code which attempts to detect and
1321 disable unhandled interrupt sources.
1323 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1324 broken timer IRQ sources.
1326 noisapnp [ISAPNP] Disables ISA PnP code.
1328 noinitrd [RAM] Tells the kernel not to load any configured
1329 initial RAM disk.
1331 nointroute [IA-64]
1333 nojitter [IA64] Disables jitter checking for ITC timers.
1335 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1337 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1339 noltlbs [PPC] Do not use large page/tlb entries for kernel
1340 lowmem mapping on PPC40x.
1342 nomca [IA-64] Disable machine check abort handling
1344 nomce [X86-32] Machine Check Exception
1346 nomfgpt [X86-32] Disable Multi-Function General Purpose
1347 Timer usage (for AMD Geode machines).
1349 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1351 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1352 with UP alternatives
1354 noresidual [PPC] Don't use residual data on PReP machines.
1356 noresume [SWSUSP] Disables resume and restores original swap
1357 space.
1359 no-scroll [VGA] Disables scrollback.
1360 This is required for the Braillex ib80-piezo Braille
1361 reader made by F.H. Papenmeier (Germany).
1363 nosbagart [IA-64]
1365 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1367 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1368 and disable the IO APIC. legacy for "maxcpus=0".
1370 nosoftlockup [KNL] Disable the soft-lockup detector.
1372 nosync [HW,M68K] Disables sync negotiation for all devices.
1374 notsc [BUGS=X86-32] Disable Time Stamp Counter
1376 nousb [USB] Disable the USB subsystem
1378 nowb [ARM]
1380 nptcg= [IA64] Override max number of concurrent global TLB
1381 purges which is reported from either PAL_VM_SUMMARY or
1382 SAL PALO.
1384 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1385 one of ['zone', 'node', 'default'] can be specified
1386 This can be set from sysctl after boot.
1387 See Documentation/sysctl/vm.txt for details.
1389 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1391 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1392 Rather than timing out after 20 ms if an EC
1393 command is not properly ACKed, override the length
1394 of the timeout. We have interrupts disabled while
1395 waiting for the ACK, so if this is set too high
1396 interrupts *may* be lost!
1398 opl3= [HW,OSS]
1399 Format: <io>
1401 oprofile.timer= [HW]
1402 Use timer interrupt instead of performance counters
1404 osst= [HW,SCSI] SCSI Tape Driver
1405 Format: <buffer_size>,<write_threshold>
1406 See also Documentation/scsi/st.txt.
1408 panic= [KNL] Kernel behaviour on panic
1409 Format: <timeout>
1411 parkbd.port= [HW] Parallel port number the keyboard adapter is
1412 connected to, default is 0.
1413 Format: <parport#>
1414 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1415 0 for XT, 1 for AT (default is AT).
1416 Format: <mode>
1418 parport= [HW,PPT] Specify parallel ports. 0 disables.
1419 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1420 Use 'auto' to force the driver to use any
1421 IRQ/DMA settings detected (the default is to
1422 ignore detected IRQ/DMA settings because of
1423 possible conflicts). You can specify the base
1424 address, IRQ, and DMA settings; IRQ and DMA
1425 should be numbers, or 'auto' (for using detected
1426 settings on that particular port), or 'nofifo'
1427 (to avoid using a FIFO even if it is detected).
1428 Parallel ports are assigned in the order they
1429 are specified on the command line, starting
1430 with parport0.
1432 parport_init_mode= [HW,PPT]
1433 Configure VIA parallel port to operate in
1434 a specific mode. This is necessary on Pegasos
1435 computer where firmware has no options for setting
1436 up parallel port mode and sets it to spp.
1437 Currently this function knows 686a and 8231 chips.
1438 Format: [spp|ps2|epp|ecp|ecpepp]
1440 pas2= [HW,OSS] Format:
1441 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1443 pas16= [HW,SCSI]
1444 See header of drivers/scsi/pas16.c.
1446 pause_on_oops=
1447 Halt all CPUs after the first oops has been printed for
1448 the specified number of seconds. This is to be used if
1449 your oopses keep scrolling off the screen.
1451 pcbit= [HW,ISDN]
1453 pcd. [PARIDE]
1454 See header of drivers/block/paride/pcd.c.
1455 See also Documentation/paride.txt.
1457 pci=option[,option...] [PCI] various PCI subsystem options:
1458 off [X86-32] don't probe for the PCI bus
1459 bios [X86-32] force use of PCI BIOS, don't access
1460 the hardware directly. Use this if your machine
1461 has a non-standard PCI host bridge.
1462 nobios [X86-32] disallow use of PCI BIOS, only direct
1463 hardware access methods are allowed. Use this
1464 if you experience crashes upon bootup and you
1465 suspect they are caused by the BIOS.
1466 conf1 [X86-32] Force use of PCI Configuration
1467 Mechanism 1.
1468 conf2 [X86-32] Force use of PCI Configuration
1469 Mechanism 2.
1470 noaer [PCIE] If the PCIEAER kernel config parameter is
1471 enabled, this kernel boot option can be used to
1472 disable the use of PCIE advanced error reporting.
1473 nodomains [PCI] Disable support for multiple PCI
1474 root domains (aka PCI segments, in ACPI-speak).
1475 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1476 Configuration
1477 nomsi [MSI] If the PCI_MSI kernel config parameter is
1478 enabled, this kernel boot option can be used to
1479 disable the use of MSI interrupts system-wide.
1480 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1481 routing table. These calls are known to be buggy
1482 on several machines and they hang the machine
1483 when used, but on other computers it's the only
1484 way to get the interrupt routing table. Try
1485 this option if the kernel is unable to allocate
1486 IRQs or discover secondary PCI buses on your
1487 motherboard.
1488 rom [X86-32] Assign address space to expansion ROMs.
1489 Use with caution as certain devices share
1490 address decoders between ROMs and other
1491 resources.
1492 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1493 assigned automatically to PCI devices. You can
1494 make the kernel exclude IRQs of your ISA cards
1495 this way.
1496 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1497 of the PIRQ table (normally generated
1498 by the BIOS) if it is outside the
1499 F0000h-100000h range.
1500 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1501 useful if the kernel is unable to find your
1502 secondary buses and you want to tell it
1503 explicitly which ones they are.
1504 assign-busses [X86-32] Always assign all PCI bus
1505 numbers ourselves, overriding
1506 whatever the firmware may have done.
1507 usepirqmask [X86-32] Honor the possible IRQ mask stored
1508 in the BIOS $PIR table. This is needed on
1509 some systems with broken BIOSes, notably
1510 some HP Pavilion N5400 and Omnibook XE3
1511 notebooks. This will have no effect if ACPI
1512 IRQ routing is enabled.
1513 noacpi [X86-32] Do not use ACPI for IRQ routing
1514 or for PCI scanning.
1515 use_crs [X86-32] Use _CRS for PCI resource
1516 allocation.
1517 routeirq Do IRQ routing for all PCI devices.
1518 This is normally done in pci_enable_device(),
1519 so this option is a temporary workaround
1520 for broken drivers that don't call it.
1521 firmware [ARM] Do not re-enumerate the bus but instead
1522 just use the configuration from the
1523 bootloader. This is currently used on
1524 IXP2000 systems where the bus has to be
1525 configured a certain way for adjunct CPUs.
1526 noearly [X86] Don't do any early type 1 scanning.
1527 This might help on some broken boards which
1528 machine check when some devices' config space
1529 is read. But various workarounds are disabled
1530 and some IOMMU drivers will not work.
1531 bfsort Sort PCI devices into breadth-first order.
1532 This sorting is done to get a device
1533 order compatible with older (<= 2.4) kernels.
1534 nobfsort Don't sort PCI devices into breadth-first order.
1535 cbiosize=nn[KMG] The fixed amount of bus space which is
1536 reserved for the CardBus bridge's IO window.
1537 The default value is 256 bytes.
1538 cbmemsize=nn[KMG] The fixed amount of bus space which is
1539 reserved for the CardBus bridge's memory
1540 window. The default value is 64 megabytes.
1542 pcmv= [HW,PCMCIA] BadgePAD 4
1544 pd. [PARIDE]
1545 See Documentation/paride.txt.
1547 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1548 boot time.
1549 Format: { 0 | 1 }
1550 See arch/parisc/kernel/pdc_chassis.c
1552 pf. [PARIDE]
1553 See Documentation/paride.txt.
1555 pg. [PARIDE]
1556 See Documentation/paride.txt.
1558 pirq= [SMP,APIC] Manual mp-table setup
1559 See Documentation/i386/IO-APIC.txt.
1561 plip= [PPT,NET] Parallel port network link
1562 Format: { parport<nr> | timid | 0 }
1563 See also Documentation/parport.txt.
1565 pnpacpi= [ACPI]
1566 { off }
1568 pnpbios= [ISAPNP]
1569 { on | off | curr | res | no-curr | no-res }
1571 pnp_reserve_irq=
1572 [ISAPNP] Exclude IRQs for the autoconfiguration
1574 pnp_reserve_dma=
1575 [ISAPNP] Exclude DMAs for the autoconfiguration
1577 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1578 Ranges are in pairs (I/O port base and size).
1580 pnp_reserve_mem=
1581 [ISAPNP] Exclude memory regions for the
1582 autoconfiguration.
1583 Ranges are in pairs (memory base and size).
1585 print-fatal-signals=
1586 [KNL] debug: print fatal signals
1587 print-fatal-signals=1: print segfault info to
1588 the kernel console.
1589 default: off.
1591 printk.time= Show timing data prefixed to each printk message line
1592 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1594 profile= [KNL] Enable kernel profiling via /proc/profile
1595 Format: [schedule,]<number>
1596 Param: "schedule" - profile schedule points.
1597 Param: <number> - step/bucket size as a power of 2 for
1598 statistical time based profiling.
1599 Param: "sleep" - profile D-state sleeping (millisecs).
1600 Requires CONFIG_SCHEDSTATS
1601 Param: "kvm" - profile VM exits.
1603 processor.max_cstate= [HW,ACPI]
1604 Limit processor to maximum C-state
1605 max_cstate=9 overrides any DMI blacklist limit.
1607 processor.nocst [HW,ACPI]
1608 Ignore the _CST method to determine C-states,
1609 instead using the legacy FADT method
1611 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1612 before loading.
1613 See Documentation/ramdisk.txt.
1615 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1616 probe for; one of (bare|imps|exps|lifebook|any).
1617 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1618 per second.
1619 psmouse.resetafter= [HW,MOUSE]
1620 Try to reset the device after so many bad packets
1621 (0 = never).
1622 psmouse.resolution=
1623 [HW,MOUSE] Set desired mouse resolution, in dpi.
1624 psmouse.smartscroll=
1625 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1626 0 = disabled, 1 = enabled (default).
1628 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1629 Format:
1630 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1632 pt. [PARIDE]
1633 See Documentation/paride.txt.
1635 pty.legacy_count=
1636 [KNL] Number of legacy pty's. Overwrites compiled-in
1637 default number.
1639 quiet [KNL] Disable most log messages
1641 r128= [HW,DRM]
1643 raid= [HW,RAID]
1644 See Documentation/md.txt.
1646 ramdisk_blocksize= [RAM]
1647 See Documentation/ramdisk.txt.
1649 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1650 See Documentation/ramdisk.txt.
1652 rcupdate.blimit= [KNL,BOOT]
1653 Set maximum number of finished RCU callbacks to process
1654 in one batch.
1656 rcupdate.qhimark= [KNL,BOOT]
1657 Set threshold of queued
1658 RCU callbacks over which batch limiting is disabled.
1660 rcupdate.qlowmark= [KNL,BOOT]
1661 Set threshold of queued RCU callbacks below which
1662 batch limiting is re-enabled.
1664 rdinit= [KNL]
1665 Format: <full_path>
1666 Run specified binary instead of /init from the ramdisk,
1667 used for early userspace startup. See initrd.
1669 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1670 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1671 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1673 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1675 reservetop= [X86-32]
1676 Format: nn[KMG]
1677 Reserves a hole at the top of the kernel virtual
1678 address space.
1680 reset_devices [KNL] Force drivers to reset the underlying device
1681 during initialization.
1683 resume= [SWSUSP]
1684 Specify the partition device for software suspend
1686 resume_offset= [SWSUSP]
1687 Specify the offset from the beginning of the partition
1688 given by "resume=" at which the swap header is located,
1689 in <PAGE_SIZE> units (needed only for swap files).
1690 See Documentation/power/swsusp-and-swap-files.txt
1692 retain_initrd [RAM] Keep initrd memory after extraction
1694 rhash_entries= [KNL,NET]
1695 Set number of hash buckets for route cache
1697 riscom8= [HW,SERIAL]
1698 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1700 ro [KNL] Mount root device read-only on boot
1702 root= [KNL] Root filesystem
1704 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1705 mount the root filesystem
1707 rootflags= [KNL] Set root filesystem mount option string
1709 rootfstype= [KNL] Set root filesystem type
1711 rootwait [KNL] Wait (indefinitely) for root device to show up.
1712 Useful for devices that are detected asynchronously
1713 (e.g. USB and MMC devices).
1715 root_plug.vendor_id=
1716 [ROOTPLUG] Override the default vendor ID
1718 root_plug.product_id=
1719 [ROOTPLUG] Override the default product ID
1721 root_plug.debug=
1722 [ROOTPLUG] Enable debugging output
1724 rw [KNL] Mount root device read-write on boot
1726 S [KNL] Run init in single mode
1728 sa1100ir [NET]
1729 See drivers/net/irda/sa1100_ir.c.
1731 sbni= [NET] Granch SBNI12 leased line adapter
1733 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1734 Format: <io>[,<timeout>[,<isapnp>]]
1736 scsi_debug_*= [SCSI]
1737 See drivers/scsi/scsi_debug.c.
1739 scsi_default_dev_flags=
1740 [SCSI] SCSI default device flags
1741 Format: <integer>
1743 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1744 Format: <vendor>:<model>:<flags>
1745 (flags are integer value)
1747 scsi_logging_level= [SCSI] a bit mask of logging levels
1748 See drivers/scsi/scsi_logging.h for bits. Also
1749 settable via sysctl at dev.scsi.logging_level
1750 (/proc/sys/dev/scsi/logging_level).
1751 There is also a nice 'scsi_logging_level' script in the
1752 S390-tools package, available for download at
1753 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1755 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1756 discovered. async scans them in kernel threads,
1757 allowing boot to proceed. none ignores them, expecting
1758 user space to do the scan.
1760 selinux [SELINUX] Disable or enable SELinux at boot time.
1761 Format: { "0" | "1" }
1762 See security/selinux/Kconfig help text.
1763 0 -- disable.
1764 1 -- enable.
1765 Default value is set via kernel config option.
1766 If enabled at boot time, /selinux/disable can be used
1767 later to disable prior to initial policy load.
1769 selinux_compat_net =
1770 [SELINUX] Set initial selinux_compat_net flag value.
1771 Format: { "0" | "1" }
1772 0 -- use new secmark-based packet controls
1773 1 -- use legacy packet controls
1774 Default value is 0 (preferred).
1775 Value can be changed at runtime via
1776 /selinux/compat_net.
1778 serialnumber [BUGS=X86-32]
1780 shapers= [NET]
1781 Maximal number of shapers.
1783 sim710= [SCSI,HW]
1784 See header of drivers/scsi/sim710.c.
1786 simeth= [IA-64]
1787 simscsi=
1789 slram= [HW,MTD]
1791 slub_debug[=options[,slabs]] [MM, SLUB]
1792 Enabling slub_debug allows one to determine the
1793 culprit if slab objects become corrupted. Enabling
1794 slub_debug can create guard zones around objects and
1795 may poison objects when not in use. Also tracks the
1796 last alloc / free. For more information see
1797 Documentation/vm/slub.txt.
1799 slub_max_order= [MM, SLUB]
1800 Determines the maximum allowed order for slabs.
1801 A high setting may cause OOMs due to memory
1802 fragmentation. For more information see
1803 Documentation/vm/slub.txt.
1805 slub_min_objects= [MM, SLUB]
1806 The minimum number of objects per slab. SLUB will
1807 increase the slab order up to slub_max_order to
1808 generate a sufficiently large slab able to contain
1809 the number of objects indicated. The higher the number
1810 of objects the smaller the overhead of tracking slabs
1811 and the less frequently locks need to be acquired.
1812 For more information see Documentation/vm/slub.txt.
1814 slub_min_order= [MM, SLUB]
1815 Determines the mininum page order for slabs. Must be
1816 lower than slub_max_order.
1817 For more information see Documentation/vm/slub.txt.
1819 slub_nomerge [MM, SLUB]
1820 Disable merging of slabs with similar size. May be
1821 necessary if there is some reason to distinguish
1822 allocs to different slabs. Debug options disable
1823 merging on their own.
1824 For more information see Documentation/vm/slub.txt.
1826 smart2= [HW]
1827 Format: <io1>[,<io2>[,...,<io8>]]
1829 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1830 attempt to substitute SMP alternatives once at boot.
1832 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1833 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1834 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1835 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1836 smsc-ircc2.ircc_irq= [HW] IRQ line
1837 smsc-ircc2.ircc_dma= [HW] DMA channel
1838 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1839 0: Toshiba Satellite 1800 (GP data pin select)
1840 1: Fast pin select (default)
1841 2: ATC IRMode
1843 snd-ad1816a= [HW,ALSA]
1845 snd-ad1848= [HW,ALSA]
1847 snd-ali5451= [HW,ALSA]
1849 snd-als100= [HW,ALSA]
1851 snd-als4000= [HW,ALSA]
1853 snd-azt2320= [HW,ALSA]
1855 snd-cmi8330= [HW,ALSA]
1857 snd-cmipci= [HW,ALSA]
1859 snd-cs4231= [HW,ALSA]
1861 snd-cs4232= [HW,ALSA]
1863 snd-cs4236= [HW,ALSA]
1865 snd-cs4281= [HW,ALSA]
1867 snd-cs46xx= [HW,ALSA]
1869 snd-dt019x= [HW,ALSA]
1871 snd-dummy= [HW,ALSA]
1873 snd-emu10k1= [HW,ALSA]
1875 snd-ens1370= [HW,ALSA]
1877 snd-ens1371= [HW,ALSA]
1879 snd-es968= [HW,ALSA]
1881 snd-es1688= [HW,ALSA]
1883 snd-es18xx= [HW,ALSA]
1885 snd-es1938= [HW,ALSA]
1887 snd-es1968= [HW,ALSA]
1889 snd-fm801= [HW,ALSA]
1891 snd-gusclassic= [HW,ALSA]
1893 snd-gusextreme= [HW,ALSA]
1895 snd-gusmax= [HW,ALSA]
1897 snd-hdsp= [HW,ALSA]
1899 snd-ice1712= [HW,ALSA]
1901 snd-intel8x0= [HW,ALSA]
1903 snd-interwave= [HW,ALSA]
1905 snd-interwave-stb=
1906 [HW,ALSA]
1908 snd-korg1212= [HW,ALSA]
1910 snd-maestro3= [HW,ALSA]
1912 snd-mpu401= [HW,ALSA]
1914 snd-mtpav= [HW,ALSA]
1916 snd-nm256= [HW,ALSA]
1918 snd-opl3sa2= [HW,ALSA]
1920 snd-opti92x-ad1848=
1921 [HW,ALSA]
1923 snd-opti92x-cs4231=
1924 [HW,ALSA]
1926 snd-opti93x= [HW,ALSA]
1928 snd-pmac= [HW,ALSA]
1930 snd-rme32= [HW,ALSA]
1932 snd-rme96= [HW,ALSA]
1934 snd-rme9652= [HW,ALSA]
1936 snd-sb8= [HW,ALSA]
1938 snd-sb16= [HW,ALSA]
1940 snd-sbawe= [HW,ALSA]
1942 snd-serial= [HW,ALSA]
1944 snd-sgalaxy= [HW,ALSA]
1946 snd-sonicvibes= [HW,ALSA]
1948 snd-sun-amd7930=
1949 [HW,ALSA]
1951 snd-sun-cs4231= [HW,ALSA]
1953 snd-trident= [HW,ALSA]
1955 snd-usb-audio= [HW,ALSA,USB]
1957 snd-via82xx= [HW,ALSA]
1959 snd-virmidi= [HW,ALSA]
1961 snd-wavefront= [HW,ALSA]
1963 snd-ymfpci= [HW,ALSA]
1965 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1966 See Documentation/sonypi.txt
1968 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1969 See Documentation/specialix.txt.
1971 spia_io_base= [HW,MTD]
1972 spia_fio_base=
1973 spia_pedr=
1974 spia_peddr=
1976 sscape= [HW,OSS]
1977 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1979 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1980 See Documentation/scsi/st.txt.
1982 sti= [PARISC,HW]
1983 Format: <num>
1984 Set the STI (builtin display/keyboard on the HP-PARISC
1985 machines) console (graphic card) which should be used
1986 as the initial boot-console.
1987 See also comment in drivers/video/console/sticore.c.
1989 sti_font= [HW]
1990 See comment in drivers/video/console/sticore.c.
1992 stifb= [HW]
1993 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1995 sunrpc.pool_mode=
1996 [NFS]
1997 Control how the NFS server code allocates CPUs to
1998 service thread pools. Depending on how many NICs
1999 you have and where their interrupts are bound, this
2000 option will affect which CPUs will do NFS serving.
2001 Note: this parameter cannot be changed while the
2002 NFS server is running.
2004 auto the server chooses an appropriate mode
2005 automatically using heuristics
2006 global a single global pool contains all CPUs
2007 percpu one pool for each CPU
2008 pernode one pool for each NUMA node (equivalent
2009 to global on non-NUMA machines)
2011 swiotlb= [IA-64] Number of I/O TLB slabs
2013 switches= [HW,M68k]
2015 sym53c416= [HW,SCSI]
2016 See header of drivers/scsi/sym53c416.c.
2018 sysrq_always_enabled
2019 [KNL]
2020 Ignore sysrq setting - this boot parameter will
2021 neutralize any effect of /proc/sys/kernel/sysrq.
2022 Useful for debugging.
2024 t128= [HW,SCSI]
2025 See header of drivers/scsi/t128.c.
2027 tdfx= [HW,DRM]
2029 thash_entries= [KNL,NET]
2030 Set number of hash buckets for TCP connection
2032 thermal.act= [HW,ACPI]
2033 -1: disable all active trip points in all thermal zones
2034 <degrees C>: override all lowest active trip points
2036 thermal.crt= [HW,ACPI]
2037 -1: disable all critical trip points in all thermal zones
2038 <degrees C>: lower all critical trip points
2040 thermal.nocrt= [HW,ACPI]
2041 Set to disable actions on ACPI thermal zone
2042 critical and hot trip points.
2044 thermal.off= [HW,ACPI]
2045 1: disable ACPI thermal control
2047 thermal.psv= [HW,ACPI]
2048 -1: disable all passive trip points
2049 <degrees C>: override all passive trip points to this value
2051 thermal.tzp= [HW,ACPI]
2052 Specify global default ACPI thermal zone polling rate
2053 <deci-seconds>: poll all this frequency
2054 0: no polling (default)
2056 tipar.timeout= [HW,PPT]
2057 Set communications timeout in tenths of a second
2058 (default 15).
2060 tipar.delay= [HW,PPT]
2061 Set inter-bit delay in microseconds (default 10).
2063 tmscsim= [HW,SCSI]
2064 See comment before function dc390_setup() in
2065 drivers/scsi/tmscsim.c.
2067 tp720= [HW,PS2]
2069 trix= [HW,OSS] MediaTrix AudioTrix Pro
2070 Format:
2071 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2073 turbografx.map[2|3]= [HW,JOY]
2074 TurboGraFX parallel port interface
2075 Format:
2076 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2077 See also Documentation/input/joystick-parport.txt
2079 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2080 See header of drivers/scsi/u14-34f.c.
2082 uart401= [HW,OSS]
2083 Format: <io>,<irq>
2085 uart6850= [HW,OSS]
2086 Format: <io>,<irq>
2088 uhci-hcd.ignore_oc=
2089 [USB] Ignore overcurrent events (default N).
2090 Some badly-designed motherboards generate lots of
2091 bogus events, for ports that aren't wired to
2092 anything. Set this parameter to avoid log spamming.
2093 Note that genuine overcurrent events won't be
2094 reported either.
2096 usbcore.autosuspend=
2097 [USB] The autosuspend time delay (in seconds) used
2098 for newly-detected USB devices (default 2). This
2099 is the time required before an idle device will be
2100 autosuspended. Devices for which the delay is set
2101 to a negative value won't be autosuspended at all.
2103 usbhid.mousepoll=
2104 [USBHID] The interval which mice are to be polled at.
2106 vdso= [X86-32,SH,x86-64]
2107 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2108 vdso=1: enable VDSO (default)
2109 vdso=0: disable VDSO mapping
2111 vdso32= [X86-32,X86-64]
2112 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2113 vdso32=1: enable 32-bit VDSO (default)
2114 vdso32=0: disable 32-bit VDSO mapping
2116 vector= [IA-64,SMP]
2117 vector=percpu: enable percpu vector domain
2119 video= [FB] Frame buffer configuration
2120 See Documentation/fb/modedb.txt.
2122 vga= [BOOT,X86-32] Select a particular video mode
2123 See Documentation/i386/boot.txt and
2124 Documentation/svga.txt.
2125 Use vga=ask for menu.
2126 This is actually a boot loader parameter; the value is
2127 passed to the kernel using a special protocol.
2129 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2130 size of <nn>. This can be used to increase the
2131 minimum size (128MB on x86). It can also be used to
2132 decrease the size and leave more room for directly
2133 mapped kernel RAM.
2135 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2136 Format: <command>
2138 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2139 Format: <command>
2141 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2142 Format: <command>
2144 waveartist= [HW,OSS]
2145 Format: <io>,<irq>,<dma>,<dma2>
2147 wd33c93= [HW,SCSI]
2148 See header of drivers/scsi/wd33c93.c.
2150 wd7000= [HW,SCSI]
2151 See header of drivers/scsi/wd7000.c.
2153 wdt= [WDT] Watchdog
2154 See Documentation/watchdog/wdt.txt.
2156 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2157 xd_geo= See header of drivers/block/xd.c.
2159 xirc2ps_cs= [NET,PCMCIA]
2160 Format:
2161 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2163 norandmaps Don't use address space randomization
2164 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2166 ______________________________________________________________________
2168 TODO:
2170 Add documentation for ALSA options.
2171 Add more DRM drivers.