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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: {"of[f]" | "sk[ipmbr]"}
631 See comment in arch/i386/boot/edd.S
633 eisa_irq_edge= [PARISC,HW]
634 See header of drivers/parisc/eisa.c.
636 elanfreq= [X86-32]
637 See comment before function elanfreq_setup() in
638 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
640 elevator= [IOSCHED]
641 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
642 See Documentation/block/as-iosched.txt and
643 Documentation/block/deadline-iosched.txt for details.
645 elfcorehdr= [X86-32, X86_64]
646 Specifies physical address of start of kernel core
647 image elf header. Generally kexec loader will
648 pass this option to capture kernel.
649 See Documentation/kdump/kdump.txt for details.
651 enforcing [SELINUX] Set initial enforcing status.
652 Format: {"0" | "1"}
653 See security/selinux/Kconfig help text.
654 0 -- permissive (log only, no denials).
655 1 -- enforcing (deny and log).
656 Default value is 0.
657 Value can be changed at runtime via /selinux/enforce.
659 es1371= [HW,OSS]
660 Format: <spdif>,[<nomix>,[<amplifier>]]
661 See also header of sound/oss/es1371.c.
663 ether= [HW,NET] Ethernet cards parameters
664 This option is obsoleted by the "netdev=" option, which
665 has equivalent usage. See its documentation for details.
667 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
668 Format: <io>[,<irq>]
670 failslab=
671 fail_page_alloc=
672 fail_make_request=[KNL]
673 General fault injection mechanism.
674 Format: <interval>,<probability>,<space>,<times>
675 See also /Documentation/fault-injection/.
677 fd_mcs= [HW,SCSI]
678 See header of drivers/scsi/fd_mcs.c.
680 fdomain= [HW,SCSI]
681 See header of drivers/scsi/fdomain.c.
683 floppy= [HW]
684 See Documentation/floppy.txt.
686 gamecon.map[2|3]=
687 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
688 support via parallel port (up to 5 devices per port)
689 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
690 See also Documentation/input/joystick-parport.txt
692 gamma= [HW,DRM]
694 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
695 Format: off | on
696 default: on
698 gdth= [HW,SCSI]
699 See header of drivers/scsi/gdth.c.
701 gpt [EFI] Forces disk with valid GPT signature but
702 invalid Protective MBR to be treated as GPT.
704 gvp11= [HW,SCSI]
706 hashdist= [KNL,NUMA] Large hashes allocated during boot
707 are distributed across NUMA nodes. Defaults on
708 for IA-64, off otherwise.
709 Format: 0 | 1 (for off | on)
711 hcl= [IA-64] SGI's Hardware Graph compatibility layer
713 hd= [EIDE] (E)IDE hard drive subsystem geometry
714 Format: <cyl>,<head>,<sect>
716 hd?= [HW] (E)IDE subsystem
717 hd?lun= See Documentation/ide/ide.txt.
719 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
720 size of <nn>. This works even on boxes that have no
721 highmem otherwise. This also works to reduce highmem
722 size on bigger boxes.
724 highres= [KNL] Enable/disable high resolution timer mode.
725 Valid parameters: "on", "off"
726 Default: "on"
728 hisax= [HW,ISDN]
729 See Documentation/isdn/README.HiSax.
731 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
732 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
734 i8042.direct [HW] Put keyboard port into non-translated mode
735 i8042.dumbkbd [HW] Pretend that controller can only read data from
736 keyboard and cannot control its state
737 (Don't attempt to blink the leds)
738 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
739 i8042.nokbd [HW] Don't check/create keyboard port
740 i8042.noloop [HW] Disable the AUX Loopback command while probing
741 for the AUX port
742 i8042.nomux [HW] Don't check presence of an active multiplexing
743 controller
744 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
745 controllers
746 i8042.panicblink=
747 [HW] Frequency with which keyboard LEDs should blink
748 when kernel panics (default is 0.5 sec)
749 i8042.reset [HW] Reset the controller during init and cleanup
750 i8042.unlock [HW] Unlock (ignore) the keylock
752 i810= [HW,DRM]
754 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
755 indicates that the driver is running on unsupported
756 hardware.
757 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
758 does not match list of supported models.
759 i8k.power_status
760 [HW] Report power status in /proc/i8k
761 (disabled by default)
762 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
763 capability is set.
765 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
766 See Documentation/mca.txt.
768 icn= [HW,ISDN]
769 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
771 ide= [HW] (E)IDE subsystem
772 Format: ide=nodma or ide=doubler
773 See Documentation/ide/ide.txt.
775 ide?= [HW] (E)IDE subsystem
776 Format: ide?=ata66 or chipset specific parameters.
777 See Documentation/ide/ide.txt.
779 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
780 See Documentation/ide/ide.txt.
782 idle= [X86]
783 Format: idle=poll or idle=mwait
784 Poll forces a polling idle loop that can slightly improves the performance
785 of waking up a idle CPU, but will use a lot of power and make the system
786 run hot. Not recommended.
787 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
788 to not use it because it doesn't save as much power as a normal idle
789 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
790 as idle=poll.
792 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
793 Claim all unknown PCI IDE storage controllers.
795 ignore_loglevel [KNL]
796 Ignore loglevel setting - this will print /all/
797 kernel messages to the console. Useful for debugging.
799 ihash_entries= [KNL]
800 Set number of hash buckets for inode cache.
802 in2000= [HW,SCSI]
803 See header of drivers/scsi/in2000.c.
805 init= [KNL]
806 Format: <full_path>
807 Run specified binary instead of /sbin/init as init
808 process.
810 initcall_debug [KNL] Trace initcalls as they are executed. Useful
811 for working out where the kernel is dying during
812 startup.
814 initrd= [BOOT] Specify the location of the initial ramdisk
816 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
817 Format: <irq>
819 inttest= [IA64]
821 iommu= [x86]
822 off
823 force
824 noforce
825 biomerge
826 panic
827 nopanic
828 merge
829 nomerge
830 forcesac
831 soft
834 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
835 off
836 Disable intel iommu driver.
837 igfx_off [Default Off]
838 By default, gfx is mapped as normal device. If a gfx
839 device has a dedicated DMAR unit, the DMAR unit is
840 bypassed by not enabling DMAR with this option. In
841 this case, gfx device will use physical address for
842 DMA.
843 forcedac [x86_64]
844 With this option iommu will not optimize to look
845 for io virtual address below 32 bit forcing dual
846 address cycle on pci bus for cards supporting greater
847 than 32 bit addressing. The default is to look
848 for translation below 32 bit and if not available
849 then look in the higher range.
850 strict [Default Off]
851 With this option on every unmap_single operation will
852 result in a hardware IOTLB flush operation as opposed
853 to batching them for performance.
855 io_delay= [X86-32,X86-64] I/O delay method
856 0x80
857 Standard port 0x80 based delay
858 0xed
859 Alternate port 0xed based delay (needed on some systems)
860 udelay
861 Simple two microseconds delay
862 none
863 No delay
865 io7= [HW] IO7 for Marvel based alpha systems
866 See comment before marvel_specify_io7 in
867 arch/alpha/kernel/core_marvel.c.
869 ip= [IP_PNP]
870 See Documentation/filesystems/nfsroot.txt.
872 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
873 See comment before ip2_setup() in
874 drivers/char/ip2/ip2base.c.
876 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
877 See header of drivers/scsi/ips.c.
879 ports= [IP_VS_FTP] IPVS ftp helper module
880 Default is 21.
881 Up to 8 (IP_VS_APP_MAX_PORTS) ports
882 may be specified.
883 Format: <port>,<port>....
885 irqfixup [HW]
886 When an interrupt is not handled search all handlers
887 for it. Intended to get systems with badly broken
888 firmware running.
890 irqpoll [HW]
891 When an interrupt is not handled search all handlers
892 for it. Also check all handlers each timer
893 interrupt. Intended to get systems with badly broken
894 firmware running.
896 isapnp= [ISAPNP]
897 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
899 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
900 Format:
901 <cpu number>,...,<cpu number>
902 or
903 <cpu number>-<cpu number> (must be a positive range in ascending order)
904 or a mixture
905 <cpu number>,...,<cpu number>-<cpu number>
906 This option can be used to specify one or more CPUs
907 to isolate from the general SMP balancing and scheduling
908 algorithms. The only way to move a process onto or off
909 an "isolated" CPU is via the CPU affinity syscalls.
910 <cpu number> begins at 0 and the maximum value is
911 "number of CPUs in system - 1".
913 This option is the preferred way to isolate CPUs. The
914 alternative -- manually setting the CPU mask of all
915 tasks in the system -- can cause problems and
916 suboptimal load balancer performance.
918 iucv= [HW,NET]
920 js= [HW,JOY] Analog joystick
921 See Documentation/input/joystick.txt.
923 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
924 specifies the amount of memory usable by the kernel
925 for non-movable allocations. The requested amount is
926 spread evenly throughout all nodes in the system. The
927 remaining memory in each node is used for Movable
928 pages. In the event, a node is too small to have both
929 kernelcore and Movable pages, kernelcore pages will
930 take priority and other nodes will have a larger number
931 of kernelcore pages. The Movable zone is used for the
932 allocation of pages that may be reclaimed or moved
933 by the page migration subsystem. This means that
934 HugeTLB pages may not be allocated from this zone.
935 Note that allocations like PTEs-from-HighMem still
936 use the HighMem zone if it exists, and the Normal
937 zone if it does not.
939 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
940 is similar to kernelcore except it specifies the
941 amount of memory used for migratable allocations.
942 If both kernelcore and movablecore is specified,
943 then kernelcore will be at *least* the specified
944 value but may be more. If movablecore on its own
945 is specified, the administrator must be careful
946 that the amount of memory usable for all allocations
947 is not too small.
949 keepinitrd [HW,ARM]
951 kstack=N [X86-32,X86-64] Print N words from the kernel stack
952 in oops dumps.
954 kgdboc= [HW] kgdb over consoles.
955 Requires a tty driver that supports console polling.
956 (only serial suported for now)
957 Format: <serial_device>[,baud]
959 l2cr= [PPC]
961 l3cr= [PPC]
963 lapic [X86-32,APIC] Enable the local APIC even if BIOS
964 disabled it.
966 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
967 C2 power state.
969 libata.dma= [LIBATA] DMA control
970 libata.dma=0 Disable all PATA and SATA DMA
971 libata.dma=1 PATA and SATA Disk DMA only
972 libata.dma=2 ATAPI (CDROM) DMA only
973 libata.dma=4 Compact Flash DMA only
974 Combinations also work, so libata.dma=3 enables DMA
975 for disks and CDROMs, but not CFs.
977 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
978 when set.
979 Format: <int>
981 libata.force= [LIBATA] Force configurations. The format is comma
982 separated list of "[ID:]VAL" where ID is
983 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
984 matching port, link or device. Basically, it matches
985 the ATA ID string printed on console by libata. If
986 the whole ID part is omitted, the last PORT and DEVICE
987 values are used. If ID hasn't been specified yet, the
988 configuration applies to all ports, links and devices.
990 If only DEVICE is omitted, the parameter applies to
991 the port and all links and devices behind it. DEVICE
992 number of 0 either selects the first device or the
993 first fan-out link behind PMP device. It does not
994 select the host link. DEVICE number of 15 selects the
995 host link and device attached to it.
997 The VAL specifies the configuration to force. As long
998 as there's no ambiguity shortcut notation is allowed.
999 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1000 The following configurations can be forced.
1002 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1003 Any ID with matching PORT is used.
1005 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1007 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1008 udma[/][16,25,33,44,66,100,133] notation is also
1009 allowed.
1011 * [no]ncq: Turn on or off NCQ.
1013 If there are multiple matching configurations changing
1014 the same attribute, the last one is used.
1016 load_ramdisk= [RAM] List of ramdisks to load from floppy
1017 See Documentation/ramdisk.txt.
1019 lockd.nlm_grace_period=P [NFS] Assign grace period.
1020 Format: <integer>
1022 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1023 Format: <integer>
1025 lockd.nlm_timeout=T [NFS] Assign timeout value.
1026 Format: <integer>
1028 lockd.nlm_udpport=M [NFS] Assign UDP port.
1029 Format: <integer>
1031 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1032 Format: <irq>
1034 loglevel= All Kernel Messages with a loglevel smaller than the
1035 console loglevel will be printed to the console. It can
1036 also be changed with klogd or other programs. The
1037 loglevels are defined as follows:
1039 0 (KERN_EMERG) system is unusable
1040 1 (KERN_ALERT) action must be taken immediately
1041 2 (KERN_CRIT) critical conditions
1042 3 (KERN_ERR) error conditions
1043 4 (KERN_WARNING) warning conditions
1044 5 (KERN_NOTICE) normal but significant condition
1045 6 (KERN_INFO) informational
1046 7 (KERN_DEBUG) debug-level messages
1048 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1049 Format: { n | nk | nM }
1050 n must be a power of two. The default size
1051 is set in the kernel config file.
1053 logo.nologo [FB] Disables display of the built-in Linux logo.
1054 This may be used to provide more screen space for
1055 kernel log messages and is useful when debugging
1056 kernel boot problems.
1058 lp=0 [LP] Specify parallel ports to use, e.g,
1059 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1060 lp=reset first parallel port). 'lp=0' disables the
1061 lp=auto printer driver. 'lp=reset' (which can be
1062 specified in addition to the ports) causes
1063 attached printers to be reset. Using
1064 lp=port1,port2,... specifies the parallel ports
1065 to associate lp devices with, starting with
1066 lp0. A port specification may be 'none' to skip
1067 that lp device, or a parport name such as
1068 'parport0'. Specifying 'lp=auto' instead of a
1069 port specification list means that device IDs
1070 from each port should be examined, to see if
1071 an IEEE 1284-compliant printer is attached; if
1072 so, the driver will manage that printer.
1073 See also header of drivers/char/lp.c.
1075 lpj=n [KNL]
1076 Sets loops_per_jiffy to given constant, thus avoiding
1077 time-consuming boot-time autodetection (up to 250 ms per
1078 CPU). 0 enables autodetection (default). To determine
1079 the correct value for your kernel, boot with normal
1080 autodetection and see what value is printed. Note that
1081 on SMP systems the preset will be applied to all CPUs,
1082 which is likely to cause problems if your CPUs need
1083 significantly divergent settings. An incorrect value
1084 will cause delays in the kernel to be wrong, leading to
1085 unpredictable I/O errors and other breakage. Although
1086 unlikely, in the extreme case this might damage your
1087 hardware.
1089 ltpc= [NET]
1090 Format: <io>,<irq>,<dma>
1092 mac5380= [HW,SCSI] Format:
1093 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1095 mac53c9x= [HW,SCSI] Format:
1096 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1098 machvec= [IA64] Force the use of a particular machine-vector
1099 (machvec) in a generic kernel.
1100 Example: machvec=hpzx1_swiotlb
1102 max_loop= [LOOP] Maximum number of loopback devices that can
1103 be mounted
1104 Format: <1-256>
1106 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1107 should make use of. maxcpus=n : n >= 0 limits the
1108 kernel to using 'n' processors. n=0 is a special case,
1109 it is equivalent to "nosmp", which also disables
1110 the IO APIC.
1112 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1113 equal to this physical address is ignored.
1115 max_luns= [SCSI] Maximum number of LUNs to probe.
1116 Should be between 1 and 2^32-1.
1118 max_report_luns=
1119 [SCSI] Maximum number of LUNs received.
1120 Should be between 1 and 16384.
1122 mcatest= [IA-64]
1124 mce [X86-32] Machine Check Exception
1126 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1128 md= [HW] RAID subsystems devices and level
1129 See Documentation/md.txt.
1131 mdacon= [MDA]
1132 Format: <first>,<last>
1133 Specifies range of consoles to be captured by the MDA.
1135 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1136 Amount of memory to be used when the kernel is not able
1137 to see the whole system memory or for test.
1138 [X86-32] Use together with memmap= to avoid physical
1139 address space collisions. Without memmap= PCI devices
1140 could be placed at addresses belonging to unused RAM.
1142 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1143 memory.
1145 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1146 E820 memory map, as specified by the user.
1147 Such memmap=exactmap lines can be constructed based on
1148 BIOS output or other requirements. See the memmap=nn@ss
1149 option description.
1151 memmap=nn[KMG]@ss[KMG]
1152 [KNL] Force usage of a specific region of memory
1153 Region of memory to be used, from ss to ss+nn.
1155 memmap=nn[KMG]#ss[KMG]
1156 [KNL,ACPI] Mark specific memory as ACPI data.
1157 Region of memory to be used, from ss to ss+nn.
1159 memmap=nn[KMG]$ss[KMG]
1160 [KNL,ACPI] Mark specific memory as reserved.
1161 Region of memory to be used, from ss to ss+nn.
1162 Example: Exclude memory from 0x18690000-0x1869ffff
1163 memmap=64K$0x18690000
1164 or
1165 memmap=0x10000$0x18690000
1167 memtest= [KNL,X86_64] Enable memtest
1168 Format: <integer>
1169 range: 0,4 : pattern number
1170 default : 0 <disable>
1172 meye.*= [HW] Set MotionEye Camera parameters
1173 See Documentation/video4linux/meye.txt.
1175 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1176 Multi-Function General Purpose Timers on AMD Geode
1177 platforms.
1179 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1180 the BIOS has incorrectly applied a workaround. TinyBIOS
1181 version 0.98 is known to be affected, 0.99 fixes the
1182 problem by letting the user disable the workaround.
1184 mga= [HW,DRM]
1186 mousedev.tap_time=
1187 [MOUSE] Maximum time between finger touching and
1188 leaving touchpad surface for touch to be considered
1189 a tap and be reported as a left button click (for
1190 touchpads working in absolute mode only).
1191 Format: <msecs>
1192 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1193 reporting absolute coordinates, such as tablets
1194 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1195 reporting absolute coordinates, such as tablets
1197 mpu401= [HW,OSS]
1198 Format: <io>,<irq>
1200 MTD_Partition= [MTD]
1201 Format: <name>,<region-number>,<size>,<offset>
1203 MTD_Region= [MTD] Format:
1204 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1206 mtdparts= [MTD]
1207 See drivers/mtd/cmdlinepart.c.
1209 mtouchusb.raw_coordinates=
1210 [HW] Make the MicroTouch USB driver use raw coordinates
1211 ('y', default) or cooked coordinates ('n')
1213 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1215 NCR_D700= [HW,SCSI]
1216 See header of drivers/scsi/NCR_D700.c.
1218 ncr5380= [HW,SCSI]
1220 ncr53c400= [HW,SCSI]
1222 ncr53c400a= [HW,SCSI]
1224 ncr53c406a= [HW,SCSI]
1226 ncr53c8xx= [HW,SCSI]
1228 netdev= [NET] Network devices parameters
1229 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1230 Note that mem_start is often overloaded to mean
1231 something different and driver-specific.
1232 This usage is only documented in each driver source
1233 file if at all.
1235 nfsaddrs= [NFS]
1236 See Documentation/filesystems/nfsroot.txt.
1238 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1239 See Documentation/filesystems/nfsroot.txt.
1241 nfs.callback_tcpport=
1242 [NFS] set the TCP port on which the NFSv4 callback
1243 channel should listen.
1245 nfs.idmap_cache_timeout=
1246 [NFS] set the maximum lifetime for idmapper cache
1247 entries.
1249 nfs.enable_ino64=
1250 [NFS] enable 64-bit inode numbers.
1251 If zero, the NFS client will fake up a 32-bit inode
1252 number for the readdir() and stat() syscalls instead
1253 of returning the full 64-bit number.
1254 The default is to return 64-bit inode numbers.
1256 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1257 when a NMI is triggered.
1258 Format: [state][,regs][,debounce][,die]
1260 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1262 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1263 emulation library even if a 387 maths coprocessor
1264 is present.
1266 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1267 caches in the slab allocator. Saves per-node memory,
1268 but will impact performance.
1270 noalign [KNL,ARM]
1272 noapic [SMP,APIC] Tells the kernel to not make use of any
1273 IOAPICs that may be present in the system.
1275 nobats [PPC] Do not use BATs for mapping kernel lowmem
1276 on "Classic" PPC cores.
1278 nocache [ARM]
1280 nodelayacct [KNL] Disable per-task delay accounting
1282 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1284 noefi [X86-32,X86-64] Disable EFI runtime services support.
1286 noexec [IA-64]
1288 noexec [X86-32,X86-64]
1289 On X86-32 available only on PAE configured kernels.
1290 noexec=on: enable non-executable mappings (default)
1291 noexec=off: disable non-executable mappings
1293 noexec32 [X86-64]
1294 This affects only 32-bit executables.
1295 noexec32=on: enable non-executable mappings (default)
1296 read doesn't imply executable mappings
1297 noexec32=off: disable non-executable mappings
1298 read implies executable mappings
1300 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1301 register save and restore. The kernel will only save
1302 legacy floating-point registers on task switch.
1304 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1306 nohlt [BUGS=ARM]
1308 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1309 instruction doesn't work correctly and not to
1310 use it.
1312 nohalt [IA-64] Tells the kernel not to use the power saving
1313 function PAL_HALT_LIGHT when idle. This increases
1314 power-consumption. On the positive side, it reduces
1315 interrupt wake-up latency, which may improve performance
1316 in certain environments such as networked servers or
1317 real-time systems.
1319 nohz= [KNL] Boottime enable/disable dynamic ticks
1320 Valid arguments: on, off
1321 Default: on
1323 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1325 noirqdebug [X86-32] Disables the code which attempts to detect and
1326 disable unhandled interrupt sources.
1328 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1329 broken timer IRQ sources.
1331 noisapnp [ISAPNP] Disables ISA PnP code.
1333 noinitrd [RAM] Tells the kernel not to load any configured
1334 initial RAM disk.
1336 nointroute [IA-64]
1338 nojitter [IA64] Disables jitter checking for ITC timers.
1340 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1342 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1344 noltlbs [PPC] Do not use large page/tlb entries for kernel
1345 lowmem mapping on PPC40x.
1347 nomca [IA-64] Disable machine check abort handling
1349 nomce [X86-32] Machine Check Exception
1351 nomfgpt [X86-32] Disable Multi-Function General Purpose
1352 Timer usage (for AMD Geode machines).
1354 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1356 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1357 with UP alternatives
1359 noresidual [PPC] Don't use residual data on PReP machines.
1361 noresume [SWSUSP] Disables resume and restores original swap
1362 space.
1364 no-scroll [VGA] Disables scrollback.
1365 This is required for the Braillex ib80-piezo Braille
1366 reader made by F.H. Papenmeier (Germany).
1368 nosbagart [IA-64]
1370 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1372 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1373 and disable the IO APIC. legacy for "maxcpus=0".
1375 nosoftlockup [KNL] Disable the soft-lockup detector.
1377 nosync [HW,M68K] Disables sync negotiation for all devices.
1379 notsc [BUGS=X86-32] Disable Time Stamp Counter
1381 nousb [USB] Disable the USB subsystem
1383 nowb [ARM]
1385 nptcg= [IA64] Override max number of concurrent global TLB
1386 purges which is reported from either PAL_VM_SUMMARY or
1387 SAL PALO.
1389 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1390 one of ['zone', 'node', 'default'] can be specified
1391 This can be set from sysctl after boot.
1392 See Documentation/sysctl/vm.txt for details.
1394 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1396 opl3= [HW,OSS]
1397 Format: <io>
1399 oprofile.timer= [HW]
1400 Use timer interrupt instead of performance counters
1402 osst= [HW,SCSI] SCSI Tape Driver
1403 Format: <buffer_size>,<write_threshold>
1404 See also Documentation/scsi/st.txt.
1406 panic= [KNL] Kernel behaviour on panic
1407 Format: <timeout>
1409 parkbd.port= [HW] Parallel port number the keyboard adapter is
1410 connected to, default is 0.
1411 Format: <parport#>
1412 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1413 0 for XT, 1 for AT (default is AT).
1414 Format: <mode>
1416 parport= [HW,PPT] Specify parallel ports. 0 disables.
1417 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1418 Use 'auto' to force the driver to use any
1419 IRQ/DMA settings detected (the default is to
1420 ignore detected IRQ/DMA settings because of
1421 possible conflicts). You can specify the base
1422 address, IRQ, and DMA settings; IRQ and DMA
1423 should be numbers, or 'auto' (for using detected
1424 settings on that particular port), or 'nofifo'
1425 (to avoid using a FIFO even if it is detected).
1426 Parallel ports are assigned in the order they
1427 are specified on the command line, starting
1428 with parport0.
1430 parport_init_mode= [HW,PPT]
1431 Configure VIA parallel port to operate in
1432 a specific mode. This is necessary on Pegasos
1433 computer where firmware has no options for setting
1434 up parallel port mode and sets it to spp.
1435 Currently this function knows 686a and 8231 chips.
1436 Format: [spp|ps2|epp|ecp|ecpepp]
1438 pas2= [HW,OSS] Format:
1439 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1441 pas16= [HW,SCSI]
1442 See header of drivers/scsi/pas16.c.
1444 pause_on_oops=
1445 Halt all CPUs after the first oops has been printed for
1446 the specified number of seconds. This is to be used if
1447 your oopses keep scrolling off the screen.
1449 pcbit= [HW,ISDN]
1451 pcd. [PARIDE]
1452 See header of drivers/block/paride/pcd.c.
1453 See also Documentation/paride.txt.
1455 pci=option[,option...] [PCI] various PCI subsystem options:
1456 off [X86-32] don't probe for the PCI bus
1457 bios [X86-32] force use of PCI BIOS, don't access
1458 the hardware directly. Use this if your machine
1459 has a non-standard PCI host bridge.
1460 nobios [X86-32] disallow use of PCI BIOS, only direct
1461 hardware access methods are allowed. Use this
1462 if you experience crashes upon bootup and you
1463 suspect they are caused by the BIOS.
1464 conf1 [X86-32] Force use of PCI Configuration
1465 Mechanism 1.
1466 conf2 [X86-32] Force use of PCI Configuration
1467 Mechanism 2.
1468 noaer [PCIE] If the PCIEAER kernel config parameter is
1469 enabled, this kernel boot option can be used to
1470 disable the use of PCIE advanced error reporting.
1471 nodomains [PCI] Disable support for multiple PCI
1472 root domains (aka PCI segments, in ACPI-speak).
1473 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1474 Configuration
1475 nomsi [MSI] If the PCI_MSI kernel config parameter is
1476 enabled, this kernel boot option can be used to
1477 disable the use of MSI interrupts system-wide.
1478 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1479 routing table. These calls are known to be buggy
1480 on several machines and they hang the machine
1481 when used, but on other computers it's the only
1482 way to get the interrupt routing table. Try
1483 this option if the kernel is unable to allocate
1484 IRQs or discover secondary PCI buses on your
1485 motherboard.
1486 rom [X86-32] Assign address space to expansion ROMs.
1487 Use with caution as certain devices share
1488 address decoders between ROMs and other
1489 resources.
1490 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1491 assigned automatically to PCI devices. You can
1492 make the kernel exclude IRQs of your ISA cards
1493 this way.
1494 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1495 of the PIRQ table (normally generated
1496 by the BIOS) if it is outside the
1497 F0000h-100000h range.
1498 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1499 useful if the kernel is unable to find your
1500 secondary buses and you want to tell it
1501 explicitly which ones they are.
1502 assign-busses [X86-32] Always assign all PCI bus
1503 numbers ourselves, overriding
1504 whatever the firmware may have done.
1505 usepirqmask [X86-32] Honor the possible IRQ mask stored
1506 in the BIOS $PIR table. This is needed on
1507 some systems with broken BIOSes, notably
1508 some HP Pavilion N5400 and Omnibook XE3
1509 notebooks. This will have no effect if ACPI
1510 IRQ routing is enabled.
1511 noacpi [X86-32] Do not use ACPI for IRQ routing
1512 or for PCI scanning.
1513 use_crs [X86-32] Use _CRS for PCI resource
1514 allocation.
1515 routeirq Do IRQ routing for all PCI devices.
1516 This is normally done in pci_enable_device(),
1517 so this option is a temporary workaround
1518 for broken drivers that don't call it.
1519 firmware [ARM] Do not re-enumerate the bus but instead
1520 just use the configuration from the
1521 bootloader. This is currently used on
1522 IXP2000 systems where the bus has to be
1523 configured a certain way for adjunct CPUs.
1524 noearly [X86] Don't do any early type 1 scanning.
1525 This might help on some broken boards which
1526 machine check when some devices' config space
1527 is read. But various workarounds are disabled
1528 and some IOMMU drivers will not work.
1529 bfsort Sort PCI devices into breadth-first order.
1530 This sorting is done to get a device
1531 order compatible with older (<= 2.4) kernels.
1532 nobfsort Don't sort PCI devices into breadth-first order.
1533 cbiosize=nn[KMG] The fixed amount of bus space which is
1534 reserved for the CardBus bridge's IO window.
1535 The default value is 256 bytes.
1536 cbmemsize=nn[KMG] The fixed amount of bus space which is
1537 reserved for the CardBus bridge's memory
1538 window. The default value is 64 megabytes.
1540 pcmv= [HW,PCMCIA] BadgePAD 4
1542 pd. [PARIDE]
1543 See Documentation/paride.txt.
1545 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1546 boot time.
1547 Format: { 0 | 1 }
1548 See arch/parisc/kernel/pdc_chassis.c
1550 pf. [PARIDE]
1551 See Documentation/paride.txt.
1553 pg. [PARIDE]
1554 See Documentation/paride.txt.
1556 pirq= [SMP,APIC] Manual mp-table setup
1557 See Documentation/i386/IO-APIC.txt.
1559 plip= [PPT,NET] Parallel port network link
1560 Format: { parport<nr> | timid | 0 }
1561 See also Documentation/parport.txt.
1563 pnpacpi= [ACPI]
1564 { off }
1566 pnpbios= [ISAPNP]
1567 { on | off | curr | res | no-curr | no-res }
1569 pnp_reserve_irq=
1570 [ISAPNP] Exclude IRQs for the autoconfiguration
1572 pnp_reserve_dma=
1573 [ISAPNP] Exclude DMAs for the autoconfiguration
1575 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1576 Ranges are in pairs (I/O port base and size).
1578 pnp_reserve_mem=
1579 [ISAPNP] Exclude memory regions for the
1580 autoconfiguration.
1581 Ranges are in pairs (memory base and size).
1583 print-fatal-signals=
1584 [KNL] debug: print fatal signals
1585 print-fatal-signals=1: print segfault info to
1586 the kernel console.
1587 default: off.
1589 printk.time= Show timing data prefixed to each printk message line
1590 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1592 profile= [KNL] Enable kernel profiling via /proc/profile
1593 Format: [schedule,]<number>
1594 Param: "schedule" - profile schedule points.
1595 Param: <number> - step/bucket size as a power of 2 for
1596 statistical time based profiling.
1597 Param: "sleep" - profile D-state sleeping (millisecs).
1598 Requires CONFIG_SCHEDSTATS
1599 Param: "kvm" - profile VM exits.
1601 processor.max_cstate= [HW,ACPI]
1602 Limit processor to maximum C-state
1603 max_cstate=9 overrides any DMI blacklist limit.
1605 processor.nocst [HW,ACPI]
1606 Ignore the _CST method to determine C-states,
1607 instead using the legacy FADT method
1609 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1610 before loading.
1611 See Documentation/ramdisk.txt.
1613 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1614 probe for; one of (bare|imps|exps|lifebook|any).
1615 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1616 per second.
1617 psmouse.resetafter= [HW,MOUSE]
1618 Try to reset the device after so many bad packets
1619 (0 = never).
1620 psmouse.resolution=
1621 [HW,MOUSE] Set desired mouse resolution, in dpi.
1622 psmouse.smartscroll=
1623 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1624 0 = disabled, 1 = enabled (default).
1626 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1627 Format:
1628 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1630 pt. [PARIDE]
1631 See Documentation/paride.txt.
1633 pty.legacy_count=
1634 [KNL] Number of legacy pty's. Overwrites compiled-in
1635 default number.
1637 quiet [KNL] Disable most log messages
1639 r128= [HW,DRM]
1641 raid= [HW,RAID]
1642 See Documentation/md.txt.
1644 ramdisk_blocksize= [RAM]
1645 See Documentation/ramdisk.txt.
1647 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1648 See Documentation/ramdisk.txt.
1650 rcupdate.blimit= [KNL,BOOT]
1651 Set maximum number of finished RCU callbacks to process
1652 in one batch.
1654 rcupdate.qhimark= [KNL,BOOT]
1655 Set threshold of queued
1656 RCU callbacks over which batch limiting is disabled.
1658 rcupdate.qlowmark= [KNL,BOOT]
1659 Set threshold of queued RCU callbacks below which
1660 batch limiting is re-enabled.
1662 rdinit= [KNL]
1663 Format: <full_path>
1664 Run specified binary instead of /init from the ramdisk,
1665 used for early userspace startup. See initrd.
1667 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1668 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1669 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1671 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1673 reservetop= [X86-32]
1674 Format: nn[KMG]
1675 Reserves a hole at the top of the kernel virtual
1676 address space.
1678 reset_devices [KNL] Force drivers to reset the underlying device
1679 during initialization.
1681 resume= [SWSUSP]
1682 Specify the partition device for software suspend
1684 resume_offset= [SWSUSP]
1685 Specify the offset from the beginning of the partition
1686 given by "resume=" at which the swap header is located,
1687 in <PAGE_SIZE> units (needed only for swap files).
1688 See Documentation/power/swsusp-and-swap-files.txt
1690 retain_initrd [RAM] Keep initrd memory after extraction
1692 rhash_entries= [KNL,NET]
1693 Set number of hash buckets for route cache
1695 riscom8= [HW,SERIAL]
1696 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1698 ro [KNL] Mount root device read-only on boot
1700 root= [KNL] Root filesystem
1702 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1703 mount the root filesystem
1705 rootflags= [KNL] Set root filesystem mount option string
1707 rootfstype= [KNL] Set root filesystem type
1709 rootwait [KNL] Wait (indefinitely) for root device to show up.
1710 Useful for devices that are detected asynchronously
1711 (e.g. USB and MMC devices).
1713 root_plug.vendor_id=
1714 [ROOTPLUG] Override the default vendor ID
1716 root_plug.product_id=
1717 [ROOTPLUG] Override the default product ID
1719 root_plug.debug=
1720 [ROOTPLUG] Enable debugging output
1722 rw [KNL] Mount root device read-write on boot
1724 S [KNL] Run init in single mode
1726 sa1100ir [NET]
1727 See drivers/net/irda/sa1100_ir.c.
1729 sbni= [NET] Granch SBNI12 leased line adapter
1731 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1732 Format: <io>[,<timeout>[,<isapnp>]]
1734 scsi_debug_*= [SCSI]
1735 See drivers/scsi/scsi_debug.c.
1737 scsi_default_dev_flags=
1738 [SCSI] SCSI default device flags
1739 Format: <integer>
1741 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1742 Format: <vendor>:<model>:<flags>
1743 (flags are integer value)
1745 scsi_logging_level= [SCSI] a bit mask of logging levels
1746 See drivers/scsi/scsi_logging.h for bits. Also
1747 settable via sysctl at dev.scsi.logging_level
1748 (/proc/sys/dev/scsi/logging_level).
1749 There is also a nice 'scsi_logging_level' script in the
1750 S390-tools package, available for download at
1751 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1753 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1754 discovered. async scans them in kernel threads,
1755 allowing boot to proceed. none ignores them, expecting
1756 user space to do the scan.
1758 selinux [SELINUX] Disable or enable SELinux at boot time.
1759 Format: { "0" | "1" }
1760 See security/selinux/Kconfig help text.
1761 0 -- disable.
1762 1 -- enable.
1763 Default value is set via kernel config option.
1764 If enabled at boot time, /selinux/disable can be used
1765 later to disable prior to initial policy load.
1767 selinux_compat_net =
1768 [SELINUX] Set initial selinux_compat_net flag value.
1769 Format: { "0" | "1" }
1770 0 -- use new secmark-based packet controls
1771 1 -- use legacy packet controls
1772 Default value is 0 (preferred).
1773 Value can be changed at runtime via
1774 /selinux/compat_net.
1776 serialnumber [BUGS=X86-32]
1778 shapers= [NET]
1779 Maximal number of shapers.
1781 sim710= [SCSI,HW]
1782 See header of drivers/scsi/sim710.c.
1784 simeth= [IA-64]
1785 simscsi=
1787 slram= [HW,MTD]
1789 slub_debug[=options[,slabs]] [MM, SLUB]
1790 Enabling slub_debug allows one to determine the
1791 culprit if slab objects become corrupted. Enabling
1792 slub_debug can create guard zones around objects and
1793 may poison objects when not in use. Also tracks the
1794 last alloc / free. For more information see
1795 Documentation/vm/slub.txt.
1797 slub_max_order= [MM, SLUB]
1798 Determines the maximum allowed order for slabs.
1799 A high setting may cause OOMs due to memory
1800 fragmentation. For more information see
1801 Documentation/vm/slub.txt.
1803 slub_min_objects= [MM, SLUB]
1804 The minimum number of objects per slab. SLUB will
1805 increase the slab order up to slub_max_order to
1806 generate a sufficiently large slab able to contain
1807 the number of objects indicated. The higher the number
1808 of objects the smaller the overhead of tracking slabs
1809 and the less frequently locks need to be acquired.
1810 For more information see Documentation/vm/slub.txt.
1812 slub_min_order= [MM, SLUB]
1813 Determines the mininum page order for slabs. Must be
1814 lower than slub_max_order.
1815 For more information see Documentation/vm/slub.txt.
1817 slub_nomerge [MM, SLUB]
1818 Disable merging of slabs with similar size. May be
1819 necessary if there is some reason to distinguish
1820 allocs to different slabs. Debug options disable
1821 merging on their own.
1822 For more information see Documentation/vm/slub.txt.
1824 smart2= [HW]
1825 Format: <io1>[,<io2>[,...,<io8>]]
1827 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1828 attempt to substitute SMP alternatives once at boot.
1830 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1831 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1832 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1833 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1834 smsc-ircc2.ircc_irq= [HW] IRQ line
1835 smsc-ircc2.ircc_dma= [HW] DMA channel
1836 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1837 0: Toshiba Satellite 1800 (GP data pin select)
1838 1: Fast pin select (default)
1839 2: ATC IRMode
1841 snd-ad1816a= [HW,ALSA]
1843 snd-ad1848= [HW,ALSA]
1845 snd-ali5451= [HW,ALSA]
1847 snd-als100= [HW,ALSA]
1849 snd-als4000= [HW,ALSA]
1851 snd-azt2320= [HW,ALSA]
1853 snd-cmi8330= [HW,ALSA]
1855 snd-cmipci= [HW,ALSA]
1857 snd-cs4231= [HW,ALSA]
1859 snd-cs4232= [HW,ALSA]
1861 snd-cs4236= [HW,ALSA]
1863 snd-cs4281= [HW,ALSA]
1865 snd-cs46xx= [HW,ALSA]
1867 snd-dt019x= [HW,ALSA]
1869 snd-dummy= [HW,ALSA]
1871 snd-emu10k1= [HW,ALSA]
1873 snd-ens1370= [HW,ALSA]
1875 snd-ens1371= [HW,ALSA]
1877 snd-es968= [HW,ALSA]
1879 snd-es1688= [HW,ALSA]
1881 snd-es18xx= [HW,ALSA]
1883 snd-es1938= [HW,ALSA]
1885 snd-es1968= [HW,ALSA]
1887 snd-fm801= [HW,ALSA]
1889 snd-gusclassic= [HW,ALSA]
1891 snd-gusextreme= [HW,ALSA]
1893 snd-gusmax= [HW,ALSA]
1895 snd-hdsp= [HW,ALSA]
1897 snd-ice1712= [HW,ALSA]
1899 snd-intel8x0= [HW,ALSA]
1901 snd-interwave= [HW,ALSA]
1903 snd-interwave-stb=
1904 [HW,ALSA]
1906 snd-korg1212= [HW,ALSA]
1908 snd-maestro3= [HW,ALSA]
1910 snd-mpu401= [HW,ALSA]
1912 snd-mtpav= [HW,ALSA]
1914 snd-nm256= [HW,ALSA]
1916 snd-opl3sa2= [HW,ALSA]
1918 snd-opti92x-ad1848=
1919 [HW,ALSA]
1921 snd-opti92x-cs4231=
1922 [HW,ALSA]
1924 snd-opti93x= [HW,ALSA]
1926 snd-pmac= [HW,ALSA]
1928 snd-rme32= [HW,ALSA]
1930 snd-rme96= [HW,ALSA]
1932 snd-rme9652= [HW,ALSA]
1934 snd-sb8= [HW,ALSA]
1936 snd-sb16= [HW,ALSA]
1938 snd-sbawe= [HW,ALSA]
1940 snd-serial= [HW,ALSA]
1942 snd-sgalaxy= [HW,ALSA]
1944 snd-sonicvibes= [HW,ALSA]
1946 snd-sun-amd7930=
1947 [HW,ALSA]
1949 snd-sun-cs4231= [HW,ALSA]
1951 snd-trident= [HW,ALSA]
1953 snd-usb-audio= [HW,ALSA,USB]
1955 snd-via82xx= [HW,ALSA]
1957 snd-virmidi= [HW,ALSA]
1959 snd-wavefront= [HW,ALSA]
1961 snd-ymfpci= [HW,ALSA]
1963 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1964 See Documentation/sonypi.txt
1966 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1967 See Documentation/specialix.txt.
1969 spia_io_base= [HW,MTD]
1970 spia_fio_base=
1971 spia_pedr=
1972 spia_peddr=
1974 sscape= [HW,OSS]
1975 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1977 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1978 See Documentation/scsi/st.txt.
1980 sti= [PARISC,HW]
1981 Format: <num>
1982 Set the STI (builtin display/keyboard on the HP-PARISC
1983 machines) console (graphic card) which should be used
1984 as the initial boot-console.
1985 See also comment in drivers/video/console/sticore.c.
1987 sti_font= [HW]
1988 See comment in drivers/video/console/sticore.c.
1990 stifb= [HW]
1991 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1993 sunrpc.pool_mode=
1994 [NFS]
1995 Control how the NFS server code allocates CPUs to
1996 service thread pools. Depending on how many NICs
1997 you have and where their interrupts are bound, this
1998 option will affect which CPUs will do NFS serving.
1999 Note: this parameter cannot be changed while the
2000 NFS server is running.
2002 auto the server chooses an appropriate mode
2003 automatically using heuristics
2004 global a single global pool contains all CPUs
2005 percpu one pool for each CPU
2006 pernode one pool for each NUMA node (equivalent
2007 to global on non-NUMA machines)
2009 swiotlb= [IA-64] Number of I/O TLB slabs
2011 switches= [HW,M68k]
2013 sym53c416= [HW,SCSI]
2014 See header of drivers/scsi/sym53c416.c.
2016 sysrq_always_enabled
2017 [KNL]
2018 Ignore sysrq setting - this boot parameter will
2019 neutralize any effect of /proc/sys/kernel/sysrq.
2020 Useful for debugging.
2022 t128= [HW,SCSI]
2023 See header of drivers/scsi/t128.c.
2025 tdfx= [HW,DRM]
2027 thash_entries= [KNL,NET]
2028 Set number of hash buckets for TCP connection
2030 thermal.act= [HW,ACPI]
2031 -1: disable all active trip points in all thermal zones
2032 <degrees C>: override all lowest active trip points
2034 thermal.crt= [HW,ACPI]
2035 -1: disable all critical trip points in all thermal zones
2036 <degrees C>: lower all critical trip points
2038 thermal.nocrt= [HW,ACPI]
2039 Set to disable actions on ACPI thermal zone
2040 critical and hot trip points.
2042 thermal.off= [HW,ACPI]
2043 1: disable ACPI thermal control
2045 thermal.psv= [HW,ACPI]
2046 -1: disable all passive trip points
2047 <degrees C>: override all passive trip points to this value
2049 thermal.tzp= [HW,ACPI]
2050 Specify global default ACPI thermal zone polling rate
2051 <deci-seconds>: poll all this frequency
2052 0: no polling (default)
2054 tipar.timeout= [HW,PPT]
2055 Set communications timeout in tenths of a second
2056 (default 15).
2058 tipar.delay= [HW,PPT]
2059 Set inter-bit delay in microseconds (default 10).
2061 tmscsim= [HW,SCSI]
2062 See comment before function dc390_setup() in
2063 drivers/scsi/tmscsim.c.
2065 tp720= [HW,PS2]
2067 trix= [HW,OSS] MediaTrix AudioTrix Pro
2068 Format:
2069 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2071 turbografx.map[2|3]= [HW,JOY]
2072 TurboGraFX parallel port interface
2073 Format:
2074 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2075 See also Documentation/input/joystick-parport.txt
2077 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2078 See header of drivers/scsi/u14-34f.c.
2080 uart401= [HW,OSS]
2081 Format: <io>,<irq>
2083 uart6850= [HW,OSS]
2084 Format: <io>,<irq>
2086 uhci-hcd.ignore_oc=
2087 [USB] Ignore overcurrent events (default N).
2088 Some badly-designed motherboards generate lots of
2089 bogus events, for ports that aren't wired to
2090 anything. Set this parameter to avoid log spamming.
2091 Note that genuine overcurrent events won't be
2092 reported either.
2094 usbcore.autosuspend=
2095 [USB] The autosuspend time delay (in seconds) used
2096 for newly-detected USB devices (default 2). This
2097 is the time required before an idle device will be
2098 autosuspended. Devices for which the delay is set
2099 to a negative value won't be autosuspended at all.
2101 usbhid.mousepoll=
2102 [USBHID] The interval which mice are to be polled at.
2104 vdso= [X86-32,SH,x86-64]
2105 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2106 vdso=1: enable VDSO (default)
2107 vdso=0: disable VDSO mapping
2109 vdso32= [X86-32,X86-64]
2110 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2111 vdso32=1: enable 32-bit VDSO (default)
2112 vdso32=0: disable 32-bit VDSO mapping
2114 vector= [IA-64,SMP]
2115 vector=percpu: enable percpu vector domain
2117 video= [FB] Frame buffer configuration
2118 See Documentation/fb/modedb.txt.
2120 vga= [BOOT,X86-32] Select a particular video mode
2121 See Documentation/i386/boot.txt and
2122 Documentation/svga.txt.
2123 Use vga=ask for menu.
2124 This is actually a boot loader parameter; the value is
2125 passed to the kernel using a special protocol.
2127 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2128 size of <nn>. This can be used to increase the
2129 minimum size (128MB on x86). It can also be used to
2130 decrease the size and leave more room for directly
2131 mapped kernel RAM.
2133 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2134 Format: <command>
2136 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2137 Format: <command>
2139 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2140 Format: <command>
2142 waveartist= [HW,OSS]
2143 Format: <io>,<irq>,<dma>,<dma2>
2145 wd33c93= [HW,SCSI]
2146 See header of drivers/scsi/wd33c93.c.
2148 wd7000= [HW,SCSI]
2149 See header of drivers/scsi/wd7000.c.
2151 wdt= [WDT] Watchdog
2152 See Documentation/watchdog/wdt.txt.
2154 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2155 xd_geo= See header of drivers/block/xd.c.
2157 xirc2ps_cs= [NET,PCMCIA]
2158 Format:
2159 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2161 norandmaps Don't use address space randomization
2162 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2164 ______________________________________________________________________
2166 TODO:
2168 Add documentation for ALSA options.
2169 Add more DRM drivers.