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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 If the device connected to the port is not a TTY but a braille
500 device, prepend "brl," before the device type, for instance
501 console=brl,ttyS0
502 For now, only VisioBraille is supported.
504 earlycon= [KNL] Output early console device and options.
505 uart[8250],io,<addr>[,options]
506 uart[8250],mmio,<addr>[,options]
507 Start an early, polled-mode console on the 8250/16550
508 UART at the specified I/O port or MMIO address.
509 The options are the same as for ttyS, above.
511 no_console_suspend
512 [HW] Never suspend the console
513 Disable suspending of consoles during suspend and
514 hibernate operations. Once disabled, debugging
515 messages can reach various consoles while the rest
516 of the system is being put to sleep (ie, while
517 debugging driver suspend/resume hooks). This may
518 not work reliably with all consoles, but is known
519 to work with serial and VGA consoles.
521 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
522 Format:
523 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
525 crashkernel=nn[KMG]@ss[KMG]
526 [KNL] Reserve a chunk of physical memory to
527 hold a kernel to switch to with kexec on panic.
529 crashkernel=range1:size1[,range2:size2,...][@offset]
530 [KNL] Same as above, but depends on the memory
531 in the running system. The syntax of range is
532 start-[end] where start and end are both
533 a memory unit (amount[KMG]). See also
534 Documentation/kdump/kdump.txt for a example.
536 cs4232= [HW,OSS]
537 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
539 cs89x0_dma= [HW,NET]
540 Format: <dma>
542 cs89x0_media= [HW,NET]
543 Format: { rj45 | aui | bnc }
545 dasd= [HW,NET]
546 See header of drivers/s390/block/dasd_devmap.c.
548 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
549 (one device per port)
550 Format: <port#>,<type>
551 See also Documentation/input/joystick-parport.txt
553 debug [KNL] Enable kernel debugging (events log level).
555 debug_locks_verbose=
556 [KNL] verbose self-tests
557 Format=<0|1>
558 Print debugging info while doing the locking API
559 self-tests.
560 We default to 0 (no extra messages), setting it to
561 1 will print _a lot_ more information - normally
562 only useful to kernel developers.
564 debug_objects [KNL] Enable object debugging
566 decnet.addr= [HW,NET]
567 Format: <area>[,<node>]
568 See also Documentation/networking/decnet.txt.
570 vt.default_blu= [VT]
571 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
572 Change the default blue palette of the console.
573 This is a 16-member array composed of values
574 ranging from 0-255.
576 vt.default_grn= [VT]
577 Format: <green0>,<green1>,<green2>,...,<green15>
578 Change the default green palette of the console.
579 This is a 16-member array composed of values
580 ranging from 0-255.
582 vt.default_red= [VT]
583 Format: <red0>,<red1>,<red2>,...,<red15>
584 Change the default red palette of the console.
585 This is a 16-member array composed of values
586 ranging from 0-255.
588 vt.default_utf8=
589 [VT]
590 Format=<0|1>
591 Set system-wide default UTF-8 mode for all tty's.
592 Default is 1, i.e. UTF-8 mode is enabled for all
593 newly opened terminals.
595 dhash_entries= [KNL]
596 Set number of hash buckets for dentry cache.
598 digi= [HW,SERIAL]
599 IO parameters + enable/disable command.
601 digiepca= [HW,SERIAL]
602 See drivers/char/README.epca and
603 Documentation/digiepca.txt.
605 disable_mtrr_trim [X86, Intel and AMD only]
606 By default the kernel will trim any uncacheable
607 memory out of your available memory pool based on
608 MTRR settings. This parameter disables that behavior,
609 possibly causing your machine to run very slowly.
611 dmasound= [HW,OSS] Sound subsystem buffers
613 dscc4.setup= [NET]
615 dtc3181e= [HW,SCSI]
617 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
618 earlyprintk=vga
619 earlyprintk=serial[,ttySn[,baudrate]]
621 Append ",keep" to not disable it when the real console
622 takes over.
624 Only vga or serial at a time, not both.
626 Currently only ttyS0 and ttyS1 are supported.
628 Interaction with the standard serial driver is not
629 very good.
631 The VGA output is eventually overwritten by the real
632 console.
634 eata= [HW,SCSI]
636 edd= [EDD]
637 Format: {"off" | "on" | "skip[mbr]"}
639 eisa_irq_edge= [PARISC,HW]
640 See header of drivers/parisc/eisa.c.
642 elanfreq= [X86-32]
643 See comment before function elanfreq_setup() in
644 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
646 elevator= [IOSCHED]
647 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
648 See Documentation/block/as-iosched.txt and
649 Documentation/block/deadline-iosched.txt for details.
651 elfcorehdr= [X86-32, X86_64]
652 Specifies physical address of start of kernel core
653 image elf header. Generally kexec loader will
654 pass this option to capture kernel.
655 See Documentation/kdump/kdump.txt for details.
657 enforcing [SELINUX] Set initial enforcing status.
658 Format: {"0" | "1"}
659 See security/selinux/Kconfig help text.
660 0 -- permissive (log only, no denials).
661 1 -- enforcing (deny and log).
662 Default value is 0.
663 Value can be changed at runtime via /selinux/enforce.
665 es1371= [HW,OSS]
666 Format: <spdif>,[<nomix>,[<amplifier>]]
667 See also header of sound/oss/es1371.c.
669 ether= [HW,NET] Ethernet cards parameters
670 This option is obsoleted by the "netdev=" option, which
671 has equivalent usage. See its documentation for details.
673 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
674 Format: <io>[,<irq>]
676 failslab=
677 fail_page_alloc=
678 fail_make_request=[KNL]
679 General fault injection mechanism.
680 Format: <interval>,<probability>,<space>,<times>
681 See also /Documentation/fault-injection/.
683 fd_mcs= [HW,SCSI]
684 See header of drivers/scsi/fd_mcs.c.
686 fdomain= [HW,SCSI]
687 See header of drivers/scsi/fdomain.c.
689 floppy= [HW]
690 See Documentation/floppy.txt.
692 gamecon.map[2|3]=
693 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
694 support via parallel port (up to 5 devices per port)
695 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
696 See also Documentation/input/joystick-parport.txt
698 gamma= [HW,DRM]
700 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
701 Format: off | on
702 default: on
704 gdth= [HW,SCSI]
705 See header of drivers/scsi/gdth.c.
707 gpt [EFI] Forces disk with valid GPT signature but
708 invalid Protective MBR to be treated as GPT.
710 gvp11= [HW,SCSI]
712 hashdist= [KNL,NUMA] Large hashes allocated during boot
713 are distributed across NUMA nodes. Defaults on
714 for IA-64, off otherwise.
715 Format: 0 | 1 (for off | on)
717 hcl= [IA-64] SGI's Hardware Graph compatibility layer
719 hd= [EIDE] (E)IDE hard drive subsystem geometry
720 Format: <cyl>,<head>,<sect>
722 hd?= [HW] (E)IDE subsystem
723 hd?lun= See Documentation/ide/ide.txt.
725 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
726 size of <nn>. This works even on boxes that have no
727 highmem otherwise. This also works to reduce highmem
728 size on bigger boxes.
730 highres= [KNL] Enable/disable high resolution timer mode.
731 Valid parameters: "on", "off"
732 Default: "on"
734 hisax= [HW,ISDN]
735 See Documentation/isdn/README.HiSax.
737 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
738 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
740 i8042.direct [HW] Put keyboard port into non-translated mode
741 i8042.dumbkbd [HW] Pretend that controller can only read data from
742 keyboard and cannot control its state
743 (Don't attempt to blink the leds)
744 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
745 i8042.nokbd [HW] Don't check/create keyboard port
746 i8042.noloop [HW] Disable the AUX Loopback command while probing
747 for the AUX port
748 i8042.nomux [HW] Don't check presence of an active multiplexing
749 controller
750 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
751 controllers
752 i8042.panicblink=
753 [HW] Frequency with which keyboard LEDs should blink
754 when kernel panics (default is 0.5 sec)
755 i8042.reset [HW] Reset the controller during init and cleanup
756 i8042.unlock [HW] Unlock (ignore) the keylock
758 i810= [HW,DRM]
760 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
761 indicates that the driver is running on unsupported
762 hardware.
763 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
764 does not match list of supported models.
765 i8k.power_status
766 [HW] Report power status in /proc/i8k
767 (disabled by default)
768 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
769 capability is set.
771 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
772 See Documentation/mca.txt.
774 icn= [HW,ISDN]
775 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
777 ide= [HW] (E)IDE subsystem
778 Format: ide=nodma or ide=doubler
779 See Documentation/ide/ide.txt.
781 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
782 See Documentation/ide/ide.txt.
784 idle= [X86]
785 Format: idle=poll or idle=mwait
786 Poll forces a polling idle loop that can slightly improves the performance
787 of waking up a idle CPU, but will use a lot of power and make the system
788 run hot. Not recommended.
789 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
790 to not use it because it doesn't save as much power as a normal idle
791 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
792 as idle=poll.
794 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
795 Claim all unknown PCI IDE storage controllers.
797 ignore_loglevel [KNL]
798 Ignore loglevel setting - this will print /all/
799 kernel messages to the console. Useful for debugging.
801 ihash_entries= [KNL]
802 Set number of hash buckets for inode cache.
804 in2000= [HW,SCSI]
805 See header of drivers/scsi/in2000.c.
807 init= [KNL]
808 Format: <full_path>
809 Run specified binary instead of /sbin/init as init
810 process.
812 initcall_debug [KNL] Trace initcalls as they are executed. Useful
813 for working out where the kernel is dying during
814 startup.
816 initrd= [BOOT] Specify the location of the initial ramdisk
818 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
819 Format: <irq>
821 inttest= [IA64]
823 iommu= [x86]
824 off
825 force
826 noforce
827 biomerge
828 panic
829 nopanic
830 merge
831 nomerge
832 forcesac
833 soft
836 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
837 off
838 Disable intel iommu driver.
839 igfx_off [Default Off]
840 By default, gfx is mapped as normal device. If a gfx
841 device has a dedicated DMAR unit, the DMAR unit is
842 bypassed by not enabling DMAR with this option. In
843 this case, gfx device will use physical address for
844 DMA.
845 forcedac [x86_64]
846 With this option iommu will not optimize to look
847 for io virtual address below 32 bit forcing dual
848 address cycle on pci bus for cards supporting greater
849 than 32 bit addressing. The default is to look
850 for translation below 32 bit and if not available
851 then look in the higher range.
852 strict [Default Off]
853 With this option on every unmap_single operation will
854 result in a hardware IOTLB flush operation as opposed
855 to batching them for performance.
857 io_delay= [X86-32,X86-64] I/O delay method
858 0x80
859 Standard port 0x80 based delay
860 0xed
861 Alternate port 0xed based delay (needed on some systems)
862 udelay
863 Simple two microseconds delay
864 none
865 No delay
867 io7= [HW] IO7 for Marvel based alpha systems
868 See comment before marvel_specify_io7 in
869 arch/alpha/kernel/core_marvel.c.
871 ip= [IP_PNP]
872 See Documentation/filesystems/nfsroot.txt.
874 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
875 See comment before ip2_setup() in
876 drivers/char/ip2/ip2base.c.
878 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
879 See header of drivers/scsi/ips.c.
881 ports= [IP_VS_FTP] IPVS ftp helper module
882 Default is 21.
883 Up to 8 (IP_VS_APP_MAX_PORTS) ports
884 may be specified.
885 Format: <port>,<port>....
887 irqfixup [HW]
888 When an interrupt is not handled search all handlers
889 for it. Intended to get systems with badly broken
890 firmware running.
892 irqpoll [HW]
893 When an interrupt is not handled search all handlers
894 for it. Also check all handlers each timer
895 interrupt. Intended to get systems with badly broken
896 firmware running.
898 isapnp= [ISAPNP]
899 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
901 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
902 Format:
903 <cpu number>,...,<cpu number>
904 or
905 <cpu number>-<cpu number> (must be a positive range in ascending order)
906 or a mixture
907 <cpu number>,...,<cpu number>-<cpu number>
908 This option can be used to specify one or more CPUs
909 to isolate from the general SMP balancing and scheduling
910 algorithms. The only way to move a process onto or off
911 an "isolated" CPU is via the CPU affinity syscalls.
912 <cpu number> begins at 0 and the maximum value is
913 "number of CPUs in system - 1".
915 This option is the preferred way to isolate CPUs. The
916 alternative -- manually setting the CPU mask of all
917 tasks in the system -- can cause problems and
918 suboptimal load balancer performance.
920 iucv= [HW,NET]
922 js= [HW,JOY] Analog joystick
923 See Documentation/input/joystick.txt.
925 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
926 specifies the amount of memory usable by the kernel
927 for non-movable allocations. The requested amount is
928 spread evenly throughout all nodes in the system. The
929 remaining memory in each node is used for Movable
930 pages. In the event, a node is too small to have both
931 kernelcore and Movable pages, kernelcore pages will
932 take priority and other nodes will have a larger number
933 of kernelcore pages. The Movable zone is used for the
934 allocation of pages that may be reclaimed or moved
935 by the page migration subsystem. This means that
936 HugeTLB pages may not be allocated from this zone.
937 Note that allocations like PTEs-from-HighMem still
938 use the HighMem zone if it exists, and the Normal
939 zone if it does not.
941 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
942 is similar to kernelcore except it specifies the
943 amount of memory used for migratable allocations.
944 If both kernelcore and movablecore is specified,
945 then kernelcore will be at *least* the specified
946 value but may be more. If movablecore on its own
947 is specified, the administrator must be careful
948 that the amount of memory usable for all allocations
949 is not too small.
951 keepinitrd [HW,ARM]
953 kstack=N [X86-32,X86-64] Print N words from the kernel stack
954 in oops dumps.
956 kgdboc= [HW] kgdb over consoles.
957 Requires a tty driver that supports console polling.
958 (only serial suported for now)
959 Format: <serial_device>[,baud]
961 l2cr= [PPC]
963 l3cr= [PPC]
965 lapic [X86-32,APIC] Enable the local APIC even if BIOS
966 disabled it.
968 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
969 C2 power state.
971 libata.dma= [LIBATA] DMA control
972 libata.dma=0 Disable all PATA and SATA DMA
973 libata.dma=1 PATA and SATA Disk DMA only
974 libata.dma=2 ATAPI (CDROM) DMA only
975 libata.dma=4 Compact Flash DMA only
976 Combinations also work, so libata.dma=3 enables DMA
977 for disks and CDROMs, but not CFs.
979 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
980 when set.
981 Format: <int>
983 libata.force= [LIBATA] Force configurations. The format is comma
984 separated list of "[ID:]VAL" where ID is
985 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
986 matching port, link or device. Basically, it matches
987 the ATA ID string printed on console by libata. If
988 the whole ID part is omitted, the last PORT and DEVICE
989 values are used. If ID hasn't been specified yet, the
990 configuration applies to all ports, links and devices.
992 If only DEVICE is omitted, the parameter applies to
993 the port and all links and devices behind it. DEVICE
994 number of 0 either selects the first device or the
995 first fan-out link behind PMP device. It does not
996 select the host link. DEVICE number of 15 selects the
997 host link and device attached to it.
999 The VAL specifies the configuration to force. As long
1000 as there's no ambiguity shortcut notation is allowed.
1001 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1002 The following configurations can be forced.
1004 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1005 Any ID with matching PORT is used.
1007 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1009 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1010 udma[/][16,25,33,44,66,100,133] notation is also
1011 allowed.
1013 * [no]ncq: Turn on or off NCQ.
1015 If there are multiple matching configurations changing
1016 the same attribute, the last one is used.
1018 load_ramdisk= [RAM] List of ramdisks to load from floppy
1019 See Documentation/ramdisk.txt.
1021 lockd.nlm_grace_period=P [NFS] Assign grace period.
1022 Format: <integer>
1024 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1025 Format: <integer>
1027 lockd.nlm_timeout=T [NFS] Assign timeout value.
1028 Format: <integer>
1030 lockd.nlm_udpport=M [NFS] Assign UDP port.
1031 Format: <integer>
1033 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1034 Format: <irq>
1036 loglevel= All Kernel Messages with a loglevel smaller than the
1037 console loglevel will be printed to the console. It can
1038 also be changed with klogd or other programs. The
1039 loglevels are defined as follows:
1041 0 (KERN_EMERG) system is unusable
1042 1 (KERN_ALERT) action must be taken immediately
1043 2 (KERN_CRIT) critical conditions
1044 3 (KERN_ERR) error conditions
1045 4 (KERN_WARNING) warning conditions
1046 5 (KERN_NOTICE) normal but significant condition
1047 6 (KERN_INFO) informational
1048 7 (KERN_DEBUG) debug-level messages
1050 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1051 Format: { n | nk | nM }
1052 n must be a power of two. The default size
1053 is set in the kernel config file.
1055 logo.nologo [FB] Disables display of the built-in Linux logo.
1056 This may be used to provide more screen space for
1057 kernel log messages and is useful when debugging
1058 kernel boot problems.
1060 lp=0 [LP] Specify parallel ports to use, e.g,
1061 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1062 lp=reset first parallel port). 'lp=0' disables the
1063 lp=auto printer driver. 'lp=reset' (which can be
1064 specified in addition to the ports) causes
1065 attached printers to be reset. Using
1066 lp=port1,port2,... specifies the parallel ports
1067 to associate lp devices with, starting with
1068 lp0. A port specification may be 'none' to skip
1069 that lp device, or a parport name such as
1070 'parport0'. Specifying 'lp=auto' instead of a
1071 port specification list means that device IDs
1072 from each port should be examined, to see if
1073 an IEEE 1284-compliant printer is attached; if
1074 so, the driver will manage that printer.
1075 See also header of drivers/char/lp.c.
1077 lpj=n [KNL]
1078 Sets loops_per_jiffy to given constant, thus avoiding
1079 time-consuming boot-time autodetection (up to 250 ms per
1080 CPU). 0 enables autodetection (default). To determine
1081 the correct value for your kernel, boot with normal
1082 autodetection and see what value is printed. Note that
1083 on SMP systems the preset will be applied to all CPUs,
1084 which is likely to cause problems if your CPUs need
1085 significantly divergent settings. An incorrect value
1086 will cause delays in the kernel to be wrong, leading to
1087 unpredictable I/O errors and other breakage. Although
1088 unlikely, in the extreme case this might damage your
1089 hardware.
1091 ltpc= [NET]
1092 Format: <io>,<irq>,<dma>
1094 mac5380= [HW,SCSI] Format:
1095 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1097 machvec= [IA64] Force the use of a particular machine-vector
1098 (machvec) in a generic kernel.
1099 Example: machvec=hpzx1_swiotlb
1101 max_loop= [LOOP] Maximum number of loopback devices that can
1102 be mounted
1103 Format: <1-256>
1105 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1106 should make use of. maxcpus=n : n >= 0 limits the
1107 kernel to using 'n' processors. n=0 is a special case,
1108 it is equivalent to "nosmp", which also disables
1109 the IO APIC.
1111 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1112 equal to this physical address is ignored.
1114 max_luns= [SCSI] Maximum number of LUNs to probe.
1115 Should be between 1 and 2^32-1.
1117 max_report_luns=
1118 [SCSI] Maximum number of LUNs received.
1119 Should be between 1 and 16384.
1121 mcatest= [IA-64]
1123 mce [X86-32] Machine Check Exception
1125 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1127 md= [HW] RAID subsystems devices and level
1128 See Documentation/md.txt.
1130 mdacon= [MDA]
1131 Format: <first>,<last>
1132 Specifies range of consoles to be captured by the MDA.
1134 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1135 Amount of memory to be used when the kernel is not able
1136 to see the whole system memory or for test.
1137 [X86-32] Use together with memmap= to avoid physical
1138 address space collisions. Without memmap= PCI devices
1139 could be placed at addresses belonging to unused RAM.
1141 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1142 memory.
1144 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1145 E820 memory map, as specified by the user.
1146 Such memmap=exactmap lines can be constructed based on
1147 BIOS output or other requirements. See the memmap=nn@ss
1148 option description.
1150 memmap=nn[KMG]@ss[KMG]
1151 [KNL] Force usage of a specific region of memory
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 ACPI data.
1156 Region of memory to be used, from ss to ss+nn.
1158 memmap=nn[KMG]$ss[KMG]
1159 [KNL,ACPI] Mark specific memory as reserved.
1160 Region of memory to be used, from ss to ss+nn.
1161 Example: Exclude memory from 0x18690000-0x1869ffff
1162 memmap=64K$0x18690000
1163 or
1164 memmap=0x10000$0x18690000
1166 memtest= [KNL,X86_64] Enable memtest
1167 Format: <integer>
1168 range: 0,4 : pattern number
1169 default : 0 <disable>
1171 meye.*= [HW] Set MotionEye Camera parameters
1172 See Documentation/video4linux/meye.txt.
1174 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1175 Multi-Function General Purpose Timers on AMD Geode
1176 platforms.
1178 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1179 the BIOS has incorrectly applied a workaround. TinyBIOS
1180 version 0.98 is known to be affected, 0.99 fixes the
1181 problem by letting the user disable the workaround.
1183 mga= [HW,DRM]
1185 mousedev.tap_time=
1186 [MOUSE] Maximum time between finger touching and
1187 leaving touchpad surface for touch to be considered
1188 a tap and be reported as a left button click (for
1189 touchpads working in absolute mode only).
1190 Format: <msecs>
1191 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1192 reporting absolute coordinates, such as tablets
1193 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1194 reporting absolute coordinates, such as tablets
1196 mpu401= [HW,OSS]
1197 Format: <io>,<irq>
1199 MTD_Partition= [MTD]
1200 Format: <name>,<region-number>,<size>,<offset>
1202 MTD_Region= [MTD] Format:
1203 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1205 mtdparts= [MTD]
1206 See drivers/mtd/cmdlinepart.c.
1208 mtouchusb.raw_coordinates=
1209 [HW] Make the MicroTouch USB driver use raw coordinates
1210 ('y', default) or cooked coordinates ('n')
1212 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1214 NCR_D700= [HW,SCSI]
1215 See header of drivers/scsi/NCR_D700.c.
1217 ncr5380= [HW,SCSI]
1219 ncr53c400= [HW,SCSI]
1221 ncr53c400a= [HW,SCSI]
1223 ncr53c406a= [HW,SCSI]
1225 ncr53c8xx= [HW,SCSI]
1227 netdev= [NET] Network devices parameters
1228 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1229 Note that mem_start is often overloaded to mean
1230 something different and driver-specific.
1231 This usage is only documented in each driver source
1232 file if at all.
1234 nfsaddrs= [NFS]
1235 See Documentation/filesystems/nfsroot.txt.
1237 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1238 See Documentation/filesystems/nfsroot.txt.
1240 nfs.callback_tcpport=
1241 [NFS] set the TCP port on which the NFSv4 callback
1242 channel should listen.
1244 nfs.idmap_cache_timeout=
1245 [NFS] set the maximum lifetime for idmapper cache
1246 entries.
1248 nfs.enable_ino64=
1249 [NFS] enable 64-bit inode numbers.
1250 If zero, the NFS client will fake up a 32-bit inode
1251 number for the readdir() and stat() syscalls instead
1252 of returning the full 64-bit number.
1253 The default is to return 64-bit inode numbers.
1255 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1256 when a NMI is triggered.
1257 Format: [state][,regs][,debounce][,die]
1259 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1261 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1262 emulation library even if a 387 maths coprocessor
1263 is present.
1265 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1266 caches in the slab allocator. Saves per-node memory,
1267 but will impact performance.
1269 noalign [KNL,ARM]
1271 noapic [SMP,APIC] Tells the kernel to not make use of any
1272 IOAPICs that may be present in the system.
1274 nobats [PPC] Do not use BATs for mapping kernel lowmem
1275 on "Classic" PPC cores.
1277 nocache [ARM]
1279 nodelayacct [KNL] Disable per-task delay accounting
1281 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1283 noefi [X86-32,X86-64] Disable EFI runtime services support.
1285 noexec [IA-64]
1287 noexec [X86-32,X86-64]
1288 On X86-32 available only on PAE configured kernels.
1289 noexec=on: enable non-executable mappings (default)
1290 noexec=off: disable non-executable mappings
1292 noexec32 [X86-64]
1293 This affects only 32-bit executables.
1294 noexec32=on: enable non-executable mappings (default)
1295 read doesn't imply executable mappings
1296 noexec32=off: disable non-executable mappings
1297 read implies executable mappings
1299 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1300 register save and restore. The kernel will only save
1301 legacy floating-point registers on task switch.
1303 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1305 nohlt [BUGS=ARM]
1307 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1308 instruction doesn't work correctly and not to
1309 use it.
1311 nohalt [IA-64] Tells the kernel not to use the power saving
1312 function PAL_HALT_LIGHT when idle. This increases
1313 power-consumption. On the positive side, it reduces
1314 interrupt wake-up latency, which may improve performance
1315 in certain environments such as networked servers or
1316 real-time systems.
1318 nohz= [KNL] Boottime enable/disable dynamic ticks
1319 Valid arguments: on, off
1320 Default: on
1322 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1324 noirqdebug [X86-32] Disables the code which attempts to detect and
1325 disable unhandled interrupt sources.
1327 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1328 broken timer IRQ sources.
1330 noisapnp [ISAPNP] Disables ISA PnP code.
1332 noinitrd [RAM] Tells the kernel not to load any configured
1333 initial RAM disk.
1335 nointroute [IA-64]
1337 nojitter [IA64] Disables jitter checking for ITC timers.
1339 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1341 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1343 noltlbs [PPC] Do not use large page/tlb entries for kernel
1344 lowmem mapping on PPC40x.
1346 nomca [IA-64] Disable machine check abort handling
1348 nomce [X86-32] Machine Check Exception
1350 nomfgpt [X86-32] Disable Multi-Function General Purpose
1351 Timer usage (for AMD Geode machines).
1353 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1355 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1356 with UP alternatives
1358 noresidual [PPC] Don't use residual data on PReP machines.
1360 noresume [SWSUSP] Disables resume and restores original swap
1361 space.
1363 no-scroll [VGA] Disables scrollback.
1364 This is required for the Braillex ib80-piezo Braille
1365 reader made by F.H. Papenmeier (Germany).
1367 nosbagart [IA-64]
1369 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1371 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1372 and disable the IO APIC. legacy for "maxcpus=0".
1374 nosoftlockup [KNL] Disable the soft-lockup detector.
1376 nosync [HW,M68K] Disables sync negotiation for all devices.
1378 notsc [BUGS=X86-32] Disable Time Stamp Counter
1380 nousb [USB] Disable the USB subsystem
1382 nowb [ARM]
1384 nptcg= [IA64] Override max number of concurrent global TLB
1385 purges which is reported from either PAL_VM_SUMMARY or
1386 SAL PALO.
1388 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1389 one of ['zone', 'node', 'default'] can be specified
1390 This can be set from sysctl after boot.
1391 See Documentation/sysctl/vm.txt for details.
1393 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1395 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1396 Rather than timing out after 20 ms if an EC
1397 command is not properly ACKed, override the length
1398 of the timeout. We have interrupts disabled while
1399 waiting for the ACK, so if this is set too high
1400 interrupts *may* be lost!
1402 opl3= [HW,OSS]
1403 Format: <io>
1405 oprofile.timer= [HW]
1406 Use timer interrupt instead of performance counters
1408 osst= [HW,SCSI] SCSI Tape Driver
1409 Format: <buffer_size>,<write_threshold>
1410 See also Documentation/scsi/st.txt.
1412 panic= [KNL] Kernel behaviour on panic
1413 Format: <timeout>
1415 parkbd.port= [HW] Parallel port number the keyboard adapter is
1416 connected to, default is 0.
1417 Format: <parport#>
1418 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1419 0 for XT, 1 for AT (default is AT).
1420 Format: <mode>
1422 parport= [HW,PPT] Specify parallel ports. 0 disables.
1423 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1424 Use 'auto' to force the driver to use any
1425 IRQ/DMA settings detected (the default is to
1426 ignore detected IRQ/DMA settings because of
1427 possible conflicts). You can specify the base
1428 address, IRQ, and DMA settings; IRQ and DMA
1429 should be numbers, or 'auto' (for using detected
1430 settings on that particular port), or 'nofifo'
1431 (to avoid using a FIFO even if it is detected).
1432 Parallel ports are assigned in the order they
1433 are specified on the command line, starting
1434 with parport0.
1436 parport_init_mode= [HW,PPT]
1437 Configure VIA parallel port to operate in
1438 a specific mode. This is necessary on Pegasos
1439 computer where firmware has no options for setting
1440 up parallel port mode and sets it to spp.
1441 Currently this function knows 686a and 8231 chips.
1442 Format: [spp|ps2|epp|ecp|ecpepp]
1444 pas2= [HW,OSS] Format:
1445 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1447 pas16= [HW,SCSI]
1448 See header of drivers/scsi/pas16.c.
1450 pause_on_oops=
1451 Halt all CPUs after the first oops has been printed for
1452 the specified number of seconds. This is to be used if
1453 your oopses keep scrolling off the screen.
1455 pcbit= [HW,ISDN]
1457 pcd. [PARIDE]
1458 See header of drivers/block/paride/pcd.c.
1459 See also Documentation/paride.txt.
1461 pci=option[,option...] [PCI] various PCI subsystem options:
1462 off [X86-32] don't probe for the PCI bus
1463 bios [X86-32] force use of PCI BIOS, don't access
1464 the hardware directly. Use this if your machine
1465 has a non-standard PCI host bridge.
1466 nobios [X86-32] disallow use of PCI BIOS, only direct
1467 hardware access methods are allowed. Use this
1468 if you experience crashes upon bootup and you
1469 suspect they are caused by the BIOS.
1470 conf1 [X86-32] Force use of PCI Configuration
1471 Mechanism 1.
1472 conf2 [X86-32] Force use of PCI Configuration
1473 Mechanism 2.
1474 noaer [PCIE] If the PCIEAER kernel config parameter is
1475 enabled, this kernel boot option can be used to
1476 disable the use of PCIE advanced error reporting.
1477 nodomains [PCI] Disable support for multiple PCI
1478 root domains (aka PCI segments, in ACPI-speak).
1479 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1480 Configuration
1481 nomsi [MSI] If the PCI_MSI kernel config parameter is
1482 enabled, this kernel boot option can be used to
1483 disable the use of MSI interrupts system-wide.
1484 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1485 routing table. These calls are known to be buggy
1486 on several machines and they hang the machine
1487 when used, but on other computers it's the only
1488 way to get the interrupt routing table. Try
1489 this option if the kernel is unable to allocate
1490 IRQs or discover secondary PCI buses on your
1491 motherboard.
1492 rom [X86-32] Assign address space to expansion ROMs.
1493 Use with caution as certain devices share
1494 address decoders between ROMs and other
1495 resources.
1496 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1497 assigned automatically to PCI devices. You can
1498 make the kernel exclude IRQs of your ISA cards
1499 this way.
1500 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1501 of the PIRQ table (normally generated
1502 by the BIOS) if it is outside the
1503 F0000h-100000h range.
1504 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1505 useful if the kernel is unable to find your
1506 secondary buses and you want to tell it
1507 explicitly which ones they are.
1508 assign-busses [X86-32] Always assign all PCI bus
1509 numbers ourselves, overriding
1510 whatever the firmware may have done.
1511 usepirqmask [X86-32] Honor the possible IRQ mask stored
1512 in the BIOS $PIR table. This is needed on
1513 some systems with broken BIOSes, notably
1514 some HP Pavilion N5400 and Omnibook XE3
1515 notebooks. This will have no effect if ACPI
1516 IRQ routing is enabled.
1517 noacpi [X86-32] Do not use ACPI for IRQ routing
1518 or for PCI scanning.
1519 use_crs [X86-32] Use _CRS for PCI resource
1520 allocation.
1521 routeirq Do IRQ routing for all PCI devices.
1522 This is normally done in pci_enable_device(),
1523 so this option is a temporary workaround
1524 for broken drivers that don't call it.
1525 firmware [ARM] Do not re-enumerate the bus but instead
1526 just use the configuration from the
1527 bootloader. This is currently used on
1528 IXP2000 systems where the bus has to be
1529 configured a certain way for adjunct CPUs.
1530 noearly [X86] Don't do any early type 1 scanning.
1531 This might help on some broken boards which
1532 machine check when some devices' config space
1533 is read. But various workarounds are disabled
1534 and some IOMMU drivers will not work.
1535 bfsort Sort PCI devices into breadth-first order.
1536 This sorting is done to get a device
1537 order compatible with older (<= 2.4) kernels.
1538 nobfsort Don't sort PCI devices into breadth-first order.
1539 cbiosize=nn[KMG] The fixed amount of bus space which is
1540 reserved for the CardBus bridge's IO window.
1541 The default value is 256 bytes.
1542 cbmemsize=nn[KMG] The fixed amount of bus space which is
1543 reserved for the CardBus bridge's memory
1544 window. The default value is 64 megabytes.
1546 pcmv= [HW,PCMCIA] BadgePAD 4
1548 pd. [PARIDE]
1549 See Documentation/paride.txt.
1551 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1552 boot time.
1553 Format: { 0 | 1 }
1554 See arch/parisc/kernel/pdc_chassis.c
1556 pf. [PARIDE]
1557 See Documentation/paride.txt.
1559 pg. [PARIDE]
1560 See Documentation/paride.txt.
1562 pirq= [SMP,APIC] Manual mp-table setup
1563 See Documentation/i386/IO-APIC.txt.
1565 plip= [PPT,NET] Parallel port network link
1566 Format: { parport<nr> | timid | 0 }
1567 See also Documentation/parport.txt.
1569 pnpacpi= [ACPI]
1570 { off }
1572 pnpbios= [ISAPNP]
1573 { on | off | curr | res | no-curr | no-res }
1575 pnp_reserve_irq=
1576 [ISAPNP] Exclude IRQs for the autoconfiguration
1578 pnp_reserve_dma=
1579 [ISAPNP] Exclude DMAs for the autoconfiguration
1581 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1582 Ranges are in pairs (I/O port base and size).
1584 pnp_reserve_mem=
1585 [ISAPNP] Exclude memory regions for the
1586 autoconfiguration.
1587 Ranges are in pairs (memory base and size).
1589 print-fatal-signals=
1590 [KNL] debug: print fatal signals
1591 print-fatal-signals=1: print segfault info to
1592 the kernel console.
1593 default: off.
1595 printk.time= Show timing data prefixed to each printk message line
1596 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1598 profile= [KNL] Enable kernel profiling via /proc/profile
1599 Format: [schedule,]<number>
1600 Param: "schedule" - profile schedule points.
1601 Param: <number> - step/bucket size as a power of 2 for
1602 statistical time based profiling.
1603 Param: "sleep" - profile D-state sleeping (millisecs).
1604 Requires CONFIG_SCHEDSTATS
1605 Param: "kvm" - profile VM exits.
1607 processor.max_cstate= [HW,ACPI]
1608 Limit processor to maximum C-state
1609 max_cstate=9 overrides any DMI blacklist limit.
1611 processor.nocst [HW,ACPI]
1612 Ignore the _CST method to determine C-states,
1613 instead using the legacy FADT method
1615 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1616 before loading.
1617 See Documentation/ramdisk.txt.
1619 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1620 probe for; one of (bare|imps|exps|lifebook|any).
1621 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1622 per second.
1623 psmouse.resetafter= [HW,MOUSE]
1624 Try to reset the device after so many bad packets
1625 (0 = never).
1626 psmouse.resolution=
1627 [HW,MOUSE] Set desired mouse resolution, in dpi.
1628 psmouse.smartscroll=
1629 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1630 0 = disabled, 1 = enabled (default).
1632 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1633 Format:
1634 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1636 pt. [PARIDE]
1637 See Documentation/paride.txt.
1639 pty.legacy_count=
1640 [KNL] Number of legacy pty's. Overwrites compiled-in
1641 default number.
1643 quiet [KNL] Disable most log messages
1645 r128= [HW,DRM]
1647 raid= [HW,RAID]
1648 See Documentation/md.txt.
1650 ramdisk_blocksize= [RAM]
1651 See Documentation/ramdisk.txt.
1653 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1654 See Documentation/ramdisk.txt.
1656 rcupdate.blimit= [KNL,BOOT]
1657 Set maximum number of finished RCU callbacks to process
1658 in one batch.
1660 rcupdate.qhimark= [KNL,BOOT]
1661 Set threshold of queued
1662 RCU callbacks over which batch limiting is disabled.
1664 rcupdate.qlowmark= [KNL,BOOT]
1665 Set threshold of queued RCU callbacks below which
1666 batch limiting is re-enabled.
1668 rdinit= [KNL]
1669 Format: <full_path>
1670 Run specified binary instead of /init from the ramdisk,
1671 used for early userspace startup. See initrd.
1673 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1674 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1675 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1677 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1679 reservetop= [X86-32]
1680 Format: nn[KMG]
1681 Reserves a hole at the top of the kernel virtual
1682 address space.
1684 reset_devices [KNL] Force drivers to reset the underlying device
1685 during initialization.
1687 resume= [SWSUSP]
1688 Specify the partition device for software suspend
1690 resume_offset= [SWSUSP]
1691 Specify the offset from the beginning of the partition
1692 given by "resume=" at which the swap header is located,
1693 in <PAGE_SIZE> units (needed only for swap files).
1694 See Documentation/power/swsusp-and-swap-files.txt
1696 retain_initrd [RAM] Keep initrd memory after extraction
1698 rhash_entries= [KNL,NET]
1699 Set number of hash buckets for route cache
1701 riscom8= [HW,SERIAL]
1702 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1704 ro [KNL] Mount root device read-only on boot
1706 root= [KNL] Root filesystem
1708 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1709 mount the root filesystem
1711 rootflags= [KNL] Set root filesystem mount option string
1713 rootfstype= [KNL] Set root filesystem type
1715 rootwait [KNL] Wait (indefinitely) for root device to show up.
1716 Useful for devices that are detected asynchronously
1717 (e.g. USB and MMC devices).
1719 root_plug.vendor_id=
1720 [ROOTPLUG] Override the default vendor ID
1722 root_plug.product_id=
1723 [ROOTPLUG] Override the default product ID
1725 root_plug.debug=
1726 [ROOTPLUG] Enable debugging output
1728 rw [KNL] Mount root device read-write on boot
1730 S [KNL] Run init in single mode
1732 sa1100ir [NET]
1733 See drivers/net/irda/sa1100_ir.c.
1735 sbni= [NET] Granch SBNI12 leased line adapter
1737 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1738 Format: <io>[,<timeout>[,<isapnp>]]
1740 scsi_debug_*= [SCSI]
1741 See drivers/scsi/scsi_debug.c.
1743 scsi_default_dev_flags=
1744 [SCSI] SCSI default device flags
1745 Format: <integer>
1747 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1748 Format: <vendor>:<model>:<flags>
1749 (flags are integer value)
1751 scsi_logging_level= [SCSI] a bit mask of logging levels
1752 See drivers/scsi/scsi_logging.h for bits. Also
1753 settable via sysctl at dev.scsi.logging_level
1754 (/proc/sys/dev/scsi/logging_level).
1755 There is also a nice 'scsi_logging_level' script in the
1756 S390-tools package, available for download at
1757 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1759 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1760 discovered. async scans them in kernel threads,
1761 allowing boot to proceed. none ignores them, expecting
1762 user space to do the scan.
1764 selinux [SELINUX] Disable or enable SELinux at boot time.
1765 Format: { "0" | "1" }
1766 See security/selinux/Kconfig help text.
1767 0 -- disable.
1768 1 -- enable.
1769 Default value is set via kernel config option.
1770 If enabled at boot time, /selinux/disable can be used
1771 later to disable prior to initial policy load.
1773 selinux_compat_net =
1774 [SELINUX] Set initial selinux_compat_net flag value.
1775 Format: { "0" | "1" }
1776 0 -- use new secmark-based packet controls
1777 1 -- use legacy packet controls
1778 Default value is 0 (preferred).
1779 Value can be changed at runtime via
1780 /selinux/compat_net.
1782 serialnumber [BUGS=X86-32]
1784 shapers= [NET]
1785 Maximal number of shapers.
1787 sim710= [SCSI,HW]
1788 See header of drivers/scsi/sim710.c.
1790 simeth= [IA-64]
1791 simscsi=
1793 slram= [HW,MTD]
1795 slub_debug[=options[,slabs]] [MM, SLUB]
1796 Enabling slub_debug allows one to determine the
1797 culprit if slab objects become corrupted. Enabling
1798 slub_debug can create guard zones around objects and
1799 may poison objects when not in use. Also tracks the
1800 last alloc / free. For more information see
1801 Documentation/vm/slub.txt.
1803 slub_max_order= [MM, SLUB]
1804 Determines the maximum allowed order for slabs.
1805 A high setting may cause OOMs due to memory
1806 fragmentation. For more information see
1807 Documentation/vm/slub.txt.
1809 slub_min_objects= [MM, SLUB]
1810 The minimum number of objects per slab. SLUB will
1811 increase the slab order up to slub_max_order to
1812 generate a sufficiently large slab able to contain
1813 the number of objects indicated. The higher the number
1814 of objects the smaller the overhead of tracking slabs
1815 and the less frequently locks need to be acquired.
1816 For more information see Documentation/vm/slub.txt.
1818 slub_min_order= [MM, SLUB]
1819 Determines the mininum page order for slabs. Must be
1820 lower than slub_max_order.
1821 For more information see Documentation/vm/slub.txt.
1823 slub_nomerge [MM, SLUB]
1824 Disable merging of slabs with similar size. May be
1825 necessary if there is some reason to distinguish
1826 allocs to different slabs. Debug options disable
1827 merging on their own.
1828 For more information see Documentation/vm/slub.txt.
1830 smart2= [HW]
1831 Format: <io1>[,<io2>[,...,<io8>]]
1833 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1834 attempt to substitute SMP alternatives once at boot.
1836 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1837 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1838 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1839 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1840 smsc-ircc2.ircc_irq= [HW] IRQ line
1841 smsc-ircc2.ircc_dma= [HW] DMA channel
1842 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1843 0: Toshiba Satellite 1800 (GP data pin select)
1844 1: Fast pin select (default)
1845 2: ATC IRMode
1847 snd-ad1816a= [HW,ALSA]
1849 snd-ad1848= [HW,ALSA]
1851 snd-ali5451= [HW,ALSA]
1853 snd-als100= [HW,ALSA]
1855 snd-als4000= [HW,ALSA]
1857 snd-azt2320= [HW,ALSA]
1859 snd-cmi8330= [HW,ALSA]
1861 snd-cmipci= [HW,ALSA]
1863 snd-cs4231= [HW,ALSA]
1865 snd-cs4232= [HW,ALSA]
1867 snd-cs4236= [HW,ALSA]
1869 snd-cs4281= [HW,ALSA]
1871 snd-cs46xx= [HW,ALSA]
1873 snd-dt019x= [HW,ALSA]
1875 snd-dummy= [HW,ALSA]
1877 snd-emu10k1= [HW,ALSA]
1879 snd-ens1370= [HW,ALSA]
1881 snd-ens1371= [HW,ALSA]
1883 snd-es968= [HW,ALSA]
1885 snd-es1688= [HW,ALSA]
1887 snd-es18xx= [HW,ALSA]
1889 snd-es1938= [HW,ALSA]
1891 snd-es1968= [HW,ALSA]
1893 snd-fm801= [HW,ALSA]
1895 snd-gusclassic= [HW,ALSA]
1897 snd-gusextreme= [HW,ALSA]
1899 snd-gusmax= [HW,ALSA]
1901 snd-hdsp= [HW,ALSA]
1903 snd-ice1712= [HW,ALSA]
1905 snd-intel8x0= [HW,ALSA]
1907 snd-interwave= [HW,ALSA]
1909 snd-interwave-stb=
1910 [HW,ALSA]
1912 snd-korg1212= [HW,ALSA]
1914 snd-maestro3= [HW,ALSA]
1916 snd-mpu401= [HW,ALSA]
1918 snd-mtpav= [HW,ALSA]
1920 snd-nm256= [HW,ALSA]
1922 snd-opl3sa2= [HW,ALSA]
1924 snd-opti92x-ad1848=
1925 [HW,ALSA]
1927 snd-opti92x-cs4231=
1928 [HW,ALSA]
1930 snd-opti93x= [HW,ALSA]
1932 snd-pmac= [HW,ALSA]
1934 snd-rme32= [HW,ALSA]
1936 snd-rme96= [HW,ALSA]
1938 snd-rme9652= [HW,ALSA]
1940 snd-sb8= [HW,ALSA]
1942 snd-sb16= [HW,ALSA]
1944 snd-sbawe= [HW,ALSA]
1946 snd-serial= [HW,ALSA]
1948 snd-sgalaxy= [HW,ALSA]
1950 snd-sonicvibes= [HW,ALSA]
1952 snd-sun-amd7930=
1953 [HW,ALSA]
1955 snd-sun-cs4231= [HW,ALSA]
1957 snd-trident= [HW,ALSA]
1959 snd-usb-audio= [HW,ALSA,USB]
1961 snd-via82xx= [HW,ALSA]
1963 snd-virmidi= [HW,ALSA]
1965 snd-wavefront= [HW,ALSA]
1967 snd-ymfpci= [HW,ALSA]
1969 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1970 See Documentation/sonypi.txt
1972 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1973 See Documentation/specialix.txt.
1975 spia_io_base= [HW,MTD]
1976 spia_fio_base=
1977 spia_pedr=
1978 spia_peddr=
1980 sscape= [HW,OSS]
1981 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1983 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1984 See Documentation/scsi/st.txt.
1986 sti= [PARISC,HW]
1987 Format: <num>
1988 Set the STI (builtin display/keyboard on the HP-PARISC
1989 machines) console (graphic card) which should be used
1990 as the initial boot-console.
1991 See also comment in drivers/video/console/sticore.c.
1993 sti_font= [HW]
1994 See comment in drivers/video/console/sticore.c.
1996 stifb= [HW]
1997 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1999 sunrpc.pool_mode=
2000 [NFS]
2001 Control how the NFS server code allocates CPUs to
2002 service thread pools. Depending on how many NICs
2003 you have and where their interrupts are bound, this
2004 option will affect which CPUs will do NFS serving.
2005 Note: this parameter cannot be changed while the
2006 NFS server is running.
2008 auto the server chooses an appropriate mode
2009 automatically using heuristics
2010 global a single global pool contains all CPUs
2011 percpu one pool for each CPU
2012 pernode one pool for each NUMA node (equivalent
2013 to global on non-NUMA machines)
2015 swiotlb= [IA-64] Number of I/O TLB slabs
2017 switches= [HW,M68k]
2019 sym53c416= [HW,SCSI]
2020 See header of drivers/scsi/sym53c416.c.
2022 sysrq_always_enabled
2023 [KNL]
2024 Ignore sysrq setting - this boot parameter will
2025 neutralize any effect of /proc/sys/kernel/sysrq.
2026 Useful for debugging.
2028 t128= [HW,SCSI]
2029 See header of drivers/scsi/t128.c.
2031 tdfx= [HW,DRM]
2033 thash_entries= [KNL,NET]
2034 Set number of hash buckets for TCP connection
2036 thermal.act= [HW,ACPI]
2037 -1: disable all active trip points in all thermal zones
2038 <degrees C>: override all lowest active trip points
2040 thermal.crt= [HW,ACPI]
2041 -1: disable all critical trip points in all thermal zones
2042 <degrees C>: lower all critical trip points
2044 thermal.nocrt= [HW,ACPI]
2045 Set to disable actions on ACPI thermal zone
2046 critical and hot trip points.
2048 thermal.off= [HW,ACPI]
2049 1: disable ACPI thermal control
2051 thermal.psv= [HW,ACPI]
2052 -1: disable all passive trip points
2053 <degrees C>: override all passive trip points to this value
2055 thermal.tzp= [HW,ACPI]
2056 Specify global default ACPI thermal zone polling rate
2057 <deci-seconds>: poll all this frequency
2058 0: no polling (default)
2060 tipar.timeout= [HW,PPT]
2061 Set communications timeout in tenths of a second
2062 (default 15).
2064 tipar.delay= [HW,PPT]
2065 Set inter-bit delay in microseconds (default 10).
2067 tmscsim= [HW,SCSI]
2068 See comment before function dc390_setup() in
2069 drivers/scsi/tmscsim.c.
2071 tp720= [HW,PS2]
2073 trix= [HW,OSS] MediaTrix AudioTrix Pro
2074 Format:
2075 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2077 turbografx.map[2|3]= [HW,JOY]
2078 TurboGraFX parallel port interface
2079 Format:
2080 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2081 See also Documentation/input/joystick-parport.txt
2083 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2084 See header of drivers/scsi/u14-34f.c.
2086 uart401= [HW,OSS]
2087 Format: <io>,<irq>
2089 uart6850= [HW,OSS]
2090 Format: <io>,<irq>
2092 uhci-hcd.ignore_oc=
2093 [USB] Ignore overcurrent events (default N).
2094 Some badly-designed motherboards generate lots of
2095 bogus events, for ports that aren't wired to
2096 anything. Set this parameter to avoid log spamming.
2097 Note that genuine overcurrent events won't be
2098 reported either.
2100 usbcore.autosuspend=
2101 [USB] The autosuspend time delay (in seconds) used
2102 for newly-detected USB devices (default 2). This
2103 is the time required before an idle device will be
2104 autosuspended. Devices for which the delay is set
2105 to a negative value won't be autosuspended at all.
2107 usbhid.mousepoll=
2108 [USBHID] The interval which mice are to be polled at.
2110 vdso= [X86-32,SH,x86-64]
2111 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2112 vdso=1: enable VDSO (default)
2113 vdso=0: disable VDSO mapping
2115 vdso32= [X86-32,X86-64]
2116 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2117 vdso32=1: enable 32-bit VDSO (default)
2118 vdso32=0: disable 32-bit VDSO mapping
2120 vector= [IA-64,SMP]
2121 vector=percpu: enable percpu vector domain
2123 video= [FB] Frame buffer configuration
2124 See Documentation/fb/modedb.txt.
2126 vga= [BOOT,X86-32] Select a particular video mode
2127 See Documentation/i386/boot.txt and
2128 Documentation/svga.txt.
2129 Use vga=ask for menu.
2130 This is actually a boot loader parameter; the value is
2131 passed to the kernel using a special protocol.
2133 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2134 size of <nn>. This can be used to increase the
2135 minimum size (128MB on x86). It can also be used to
2136 decrease the size and leave more room for directly
2137 mapped kernel RAM.
2139 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2140 Format: <command>
2142 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2143 Format: <command>
2145 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2146 Format: <command>
2148 waveartist= [HW,OSS]
2149 Format: <io>,<irq>,<dma>,<dma2>
2151 wd33c93= [HW,SCSI]
2152 See header of drivers/scsi/wd33c93.c.
2154 wd7000= [HW,SCSI]
2155 See header of drivers/scsi/wd7000.c.
2157 wdt= [WDT] Watchdog
2158 See Documentation/watchdog/wdt.txt.
2160 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2161 xd_geo= See header of drivers/block/xd.c.
2163 xirc2ps_cs= [NET,PCMCIA]
2164 Format:
2165 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2167 norandmaps Don't use address space randomization
2168 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2170 ______________________________________________________________________
2172 TODO:
2174 Add documentation for ALSA options.
2175 Add more DRM drivers.