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
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 (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
106 In addition, the following text indicates that the option:
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
112 Parameters denoted with BOOT are actually interpreted by the boot
113 loader, and have no meaning to the kernel directly.
114 Do not modify the syntax of boot loader parameters without extreme
115 need or coordination with <Documentation/i386/boot.txt>.
117 There are also arch-specific kernel-parameters not documented here.
118 See for example <Documentation/x86_64/boot-options.txt>.
120 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121 a trailing = on the name of any parameter states that that parameter will
122 be entered as an environment variable, whereas its absence indicates that
123 it will appear as a kernel argument readable via /proc/cmdline by programs
124 running once the system is up.
126 The number of kernel parameters is not limited, but the length of the
127 complete command line (parameters including spaces etc.) is limited to
128 a fixed number of characters. This limit depends on the architecture
129 and is between 256 and 4096 characters. It is defined in the file
130 ./include/asm/setup.h as COMMAND_LINE_SIZE.
133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
135 Format: { force | off | ht | strict | noirq }
136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
140 strict -- Be less tolerant of platforms that are not
141 strictly ACPI specification compliant.
143 See also Documentation/power/pm.txt, pci=noacpi
145 acpi_apic_instance= [ACPI, IOAPIC]
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
151 acpi_sleep= [HW,ACPI] Sleep options
152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
164 Format: { level | edge | high | low }
166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
176 Format: <irq>,<irq>...
178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
179 Format: <irq>,<irq>...
181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
191 acpi_serialize [HW,ACPI] force serialization of AML methods
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
201 acpi.debug_layer= [HW,ACPI]
203 Each bit of the <int> indicates an ACPI debug layer,
204 1: enable, 0: disable. It is useful for boot time
205 debugging. After system has booted up, it can be set
206 via /sys/module/acpi/parameters/debug_layer.
207 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
208 Available bits (add the numbers together) to enable debug output
209 for specific parts of the ACPI subsystem:
210 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
211 0x10 namespace 0x20 parser 0x40 dispatcher
212 0x80 executer 0x100 resources 0x200 acpica debugger
213 0x400 os services 0x800 acpica disassembler.
214 The number can be in decimal or prefixed with 0x in hex.
215 Warning: Many of these options can produce a lot of
216 output and make your system unusable. Be very careful.
218 acpi.debug_level= [HW,ACPI]
220 Each bit of the <int> indicates an ACPI debug level,
221 1: enable, 0: disable. It is useful for boot time
222 debugging. After system has booted up, it can be set
223 via /sys/module/acpi/parameters/debug_level.
224 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
225 Available bits (add the numbers together) to enable different
226 debug output levels of the ACPI subsystem:
227 0x01 error 0x02 warn 0x04 init 0x08 debug object
228 0x10 info 0x20 init names 0x40 parse 0x80 load
229 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
230 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
231 0x10000 resources 0x20000 user requests 0x40000 package.
232 The number can be in decimal or prefixed with 0x in hex.
233 Warning: Many of these options can produce a lot of
234 output and make your system unusable. Be very careful.
236 acpi_pm_good [X86-32,X86-64]
237 Override the pmtimer bug detection: force the kernel
238 to assume that this machine's pmtimer latches its value
239 and always returns good values.
242 { off | try_unsupported }
243 off: disable AGP support
244 try_unsupported: try to drive unsupported chipsets
245 (may crash computer or cause data corruption)
247 enable_timer_pin_1 [i386,x86-64]
248 Enable PIN 1 of APIC timer
249 Can be useful to work around chipset bugs
250 (in particular on some ATI chipsets).
251 The kernel tries to set a reasonable default.
253 disable_timer_pin_1 [i386,x86-64]
254 Disable PIN 1 of APIC timer
255 Can be useful to work around chipset bugs.
258 Format: <io>,<irq>,<dma>,<dma2>,<type>
261 See header of drivers/scsi/advansys.c.
263 advwdt= [HW,WDT] Advantech WDT
264 Format: <iostart>,<iostop>
266 aedsp16= [HW,OSS] Audio Excel DSP 16
267 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
268 See also header of sound/oss/aedsp16.c.
271 See Documentation/scsi/aha152x.txt.
274 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
277 See Documentation/scsi/aic7xxx.txt.
280 See Documentation/scsi/aic79xx.txt.
282 amd_iommu= [HW,X86-84]
283 Pass parameters to the AMD IOMMU driver in the system.
285 isolate - enable device isolation (each device, as far
286 as possible, will get its own protection
288 fullflush - enable flushing of IO/TLB entries when
289 they are unmapped. Otherwise they are
290 flushed before they will be reused, which
293 amd_iommu_size= [HW,X86-64]
294 Define the size of the aperture for the AMD IOMMU
295 driver. Possible values are:
296 '32M', '64M' (default), '128M', '256M', '512M', '1G'
298 amijoy.map= [HW,JOY] Amiga joystick support
299 Map of devices attached to JOY0DAT and JOY1DAT
301 See also Documentation/kernel/input/joystick.txt
303 analog.map= [HW,JOY] Analog joystick and gamepad support
304 Specifies type or capabilities of an analog joystick
305 connected to one of 16 gameports
306 Format: <type1>,<type2>,..<type16>
309 Power management functions (SPARCstation-4/5 + deriv.)
311 Disable APC CPU standby support. SPARCstation-Fox does
312 not play well with APC CPU idle - disable it if you have
313 APC and your system crashes randomly.
315 apic= [APIC,i386] Advanced Programmable Interrupt Controller
316 Change the output verbosity whilst booting
317 Format: { quiet (default) | verbose | debug }
318 Change the amount of debugging information output
319 when initialising the APIC and IO-APIC components.
321 apm= [APM] Advanced Power Management
322 See header of arch/x86/kernel/apm_32.c.
324 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
325 Format: <io>,<irq>,<nodeID>
329 atarimouse= [HW,MOUSE] Atari Mouse
331 atascsi= [HW,SCSI] Atari SCSI
333 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
334 EzKey and similar keyboards
336 atkbd.reset= [HW] Reset keyboard during initialization
338 atkbd.set= [HW] Select keyboard code set
339 Format: <int> (2 = AT (default), 3 = PS/2)
341 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
344 atkbd.softraw= [HW] Choose between synthetic and real raw mode
345 Format: <bool> (0 = real, 1 = synthetic (default))
347 atkbd.softrepeat= [HW]
348 Use software keyboard repeat
352 baycom_epp= [HW,AX25]
355 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
357 See header of drivers/net/hamradio/baycom_par.c.
359 baycom_ser_fdx= [HW,AX25]
360 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
361 Format: <io>,<irq>,<mode>[,<baud>]
362 See header of drivers/net/hamradio/baycom_ser_fdx.c.
364 baycom_ser_hdx= [HW,AX25]
365 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
366 Format: <io>,<irq>,<mode>
367 See header of drivers/net/hamradio/baycom_ser_hdx.c.
369 boot_delay= Milliseconds to delay each printk during boot.
370 Values larger than 10 seconds (10000) are changed to
374 bootmem_debug [KNL] Enable bootmem allocator debug messages.
376 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
377 bttv.radio= Most important insmod options are available as
379 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
380 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
383 See drivers/scsi/BusLogic.c, comment before function
384 BusLogic_ParseDriverOptions().
386 c101= [NET] Moxa C101 synchronous serial card
388 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
389 Sometimes CPU hardware bugs make them report the cache
390 size incorrectly. The kernel will attempt work arounds
391 to fix known problems, but for some CPUs it is not
392 possible to determine what the correct size should be.
393 This option provides an override for these situations.
395 security= [SECURITY] Choose a security module to enable at boot.
396 If this boot parameter is not specified, only the first
397 security module asking for security registration will be
398 loaded. An invalid security module name will be treated
399 as if no module has been chosen.
402 [SECURITY] Disable capabilities. This would normally
403 be used only if an alternative security model is to be
404 configured. Potentially dangerous and should only be
405 used if you are entirely sure of the consequences.
407 ccw_timeout_log [S390]
408 See Documentation/s390/CommonIO for details.
410 cgroup_disable= [KNL] Disable a particular controller
411 Format: {name of the controller(s) to disable}
412 {Currently supported controllers - "memory"}
414 checkreqprot [SELINUX] Set initial checkreqprot flag value.
415 Format: { "0" | "1" }
416 See security/selinux/Kconfig help text.
417 0 -- check protection applied by kernel (includes
418 any implied execute protection).
419 1 -- check protection requested by application.
420 Default value is set via a kernel config option.
421 Value can be changed at runtime via
422 /selinux/checkreqprot.
425 See Documentation/s390/CommonIO for details.
427 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
429 Forces specified clocksource (if available) to be used
430 when calculating gettimeofday(). If specified
431 clocksource is not available, it defaults to PIT.
432 Format: { pit | tsc | cyclone | pmtmr }
434 clocksource= [GENERIC_TIME] Override the default clocksource
436 Override the default clocksource and use the clocksource
437 with the name specified.
438 Some clocksource names to choose from, depending on
440 [all] jiffies (this is the base, fallback clocksource)
442 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
443 pxa_timer,timer3,32k_counter,timer0_1
445 [X86-32] pit,hpet,tsc,vmi-timer;
446 scx200_hrt on Geode; cyclone on IBM x440
454 clearcpuid=BITNUM [X86]
455 Disable CPUID feature X for the kernel. See
456 include/asm-x86/cpufeature.h for the valid bit numbers.
457 Note the Linux specific bits are not necessarily
458 stable over kernel options, but the vendor specific
460 Also note that user programs calling CPUID directly
461 or using the feature without checking anything
462 will still see it. This just prevents it from
463 being used by the kernel or shown in /proc/cpuinfo.
464 Also note the kernel might malfunction if you disable
467 code_bytes [IA32/X86_64] How many bytes of object code to print
472 hpet= [X86-32,HPET] option to control HPET usage
473 Format: { enable (default) | disable | force }
474 disable: disable HPET and use PIT instead
475 force: allow force enabled of undocumented chips (ICH4,
478 com20020= [HW,NET] ARCnet - COM20020 chipset
480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
486 ARCnet - COM90xx chipset (memory-mapped buffers)
487 Format: <io>[,<irq>[,<memstart>]]
489 condev= [HW,S390] console device
492 console= [KNL] Output console device and options.
494 tty<n> Use the virtual console device <n>.
498 Use the specified serial port. The options are of
499 the form "bbbbpnf", where "bbbb" is the baud rate,
500 "p" is parity ("n", "o", or "e"), "n" is number of
501 bits, and "f" is flow control ("r" for RTS or
502 omit it). Default is "9600n8".
504 See Documentation/serial-console.txt for more
506 Documentation/networking/netconsole.txt for an
509 uart[8250],io,<addr>[,options]
510 uart[8250],mmio,<addr>[,options]
511 Start an early, polled-mode console on the 8250/16550
512 UART at the specified I/O port or MMIO address,
513 switching to the matching ttyS device later. The
514 options are the same as for ttyS, above.
516 If the device connected to the port is not a TTY but a braille
517 device, prepend "brl," before the device type, for instance
519 For now, only VisioBraille is supported.
521 earlycon= [KNL] Output early console device and options.
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address.
526 The options are the same as for ttyS, above.
529 [HW] Never suspend the console
530 Disable suspending of consoles during suspend and
531 hibernate operations. Once disabled, debugging
532 messages can reach various consoles while the rest
533 of the system is being put to sleep (ie, while
534 debugging driver suspend/resume hooks). This may
535 not work reliably with all consoles, but is known
536 to work with serial and VGA consoles.
538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
542 crashkernel=nn[KMG]@ss[KMG]
543 [KNL] Reserve a chunk of physical memory to
544 hold a kernel to switch to with kexec on panic.
546 crashkernel=range1:size1[,range2:size2,...][@offset]
547 [KNL] Same as above, but depends on the memory
548 in the running system. The syntax of range is
549 start-[end] where start and end are both
550 a memory unit (amount[KMG]). See also
551 Documentation/kdump/kdump.txt for a example.
554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
559 cs89x0_media= [HW,NET]
560 Format: { rj45 | aui | bnc }
563 See header of drivers/s390/block/dasd_devmap.c.
565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
566 (one device per port)
567 Format: <port#>,<type>
568 See also Documentation/input/joystick-parport.txt
570 debug [KNL] Enable kernel debugging (events log level).
573 [KNL] verbose self-tests
575 Print debugging info while doing the locking API
577 We default to 0 (no extra messages), setting it to
578 1 will print _a lot_ more information - normally
579 only useful to kernel developers.
581 debug_objects [KNL] Enable object debugging
583 debugpat [X86] Enable PAT debugging
585 decnet.addr= [HW,NET]
586 Format: <area>[,<node>]
587 See also Documentation/networking/decnet.txt.
590 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
591 Change the default blue palette of the console.
592 This is a 16-member array composed of values
596 Format: <green0>,<green1>,<green2>,...,<green15>
597 Change the default green palette of the console.
598 This is a 16-member array composed of values
602 Format: <red0>,<red1>,<red2>,...,<red15>
603 Change the default red palette of the console.
604 This is a 16-member array composed of values
610 Set system-wide default UTF-8 mode for all tty's.
611 Default is 1, i.e. UTF-8 mode is enabled for all
612 newly opened terminals.
615 Set number of hash buckets for dentry cache.
618 IO parameters + enable/disable command.
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/digiepca.txt.
624 disable_mtrr_cleanup [X86]
625 enable_mtrr_cleanup [X86]
626 The kernel tries to adjust MTRR layout from continuous
627 to discrete, to make X server driver able to add WB
628 entry later. This parameter enables/disables that.
630 mtrr_chunk_size=nn[KMG] [X86]
631 used for mtrr cleanup. It is largest continous chunk
632 that could hold holes aka. UC entries.
634 mtrr_gran_size=nn[KMG] [X86]
635 Used for mtrr cleanup. It is granularity of mtrr block.
637 Large value could prevent small alignment from
640 mtrr_spare_reg_nr=n [X86]
642 Range: 0,7 : spare reg number
644 Used for mtrr cleanup. It is spare mtrr entries number.
645 Set to 2 or more if your graphical card needs more.
647 disable_mtrr_trim [X86, Intel and AMD only]
648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
653 dmasound= [HW,OSS] Sound subsystem buffers
659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
661 earlyprintk=serial[,ttySn[,baudrate]]
664 Append ",keep" to not disable it when the real console
667 Only vga or serial or usb debug port at a time.
669 Currently only ttyS0 and ttyS1 are supported.
671 Interaction with the standard serial driver is not
674 The VGA output is eventually overwritten by the real
680 Format: {"off" | "on" | "skip[mbr]"}
682 eisa_irq_edge= [PARISC,HW]
683 See header of drivers/parisc/eisa.c.
686 See comment before function elanfreq_setup() in
687 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
690 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
691 See Documentation/block/as-iosched.txt and
692 Documentation/block/deadline-iosched.txt for details.
694 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
695 Specifies physical address of start of kernel core
696 image elf header. Generally kexec loader will
697 pass this option to capture kernel.
698 See Documentation/kdump/kdump.txt for details.
700 enforcing [SELINUX] Set initial enforcing status.
702 See security/selinux/Kconfig help text.
703 0 -- permissive (log only, no denials).
704 1 -- enforcing (deny and log).
706 Value can be changed at runtime via /selinux/enforce.
709 Format: <spdif>,[<nomix>,[<amplifier>]]
710 See also header of sound/oss/es1371.c.
712 ether= [HW,NET] Ethernet cards parameters
713 This option is obsoleted by the "netdev=" option, which
714 has equivalent usage. See its documentation for details.
716 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
721 fail_make_request=[KNL]
722 General fault injection mechanism.
723 Format: <interval>,<probability>,<space>,<times>
724 See also /Documentation/fault-injection/.
727 See header of drivers/scsi/fd_mcs.c.
730 See header of drivers/scsi/fdomain.c.
733 See Documentation/floppy.txt.
735 force_pal_cache_flush
736 [IA-64] Avoid check_sal_cache_flush which may hang on
737 buggy SAL_CACHE_FLUSH implementations. Using this
738 parameter will force ia64_sal_cache_flush to call
739 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
742 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
743 support via parallel port (up to 5 devices per port)
744 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
745 See also Documentation/input/joystick-parport.txt
749 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
754 See header of drivers/scsi/gdth.c.
756 gpt [EFI] Forces disk with valid GPT signature but
757 invalid Protective MBR to be treated as GPT.
761 hashdist= [KNL,NUMA] Large hashes allocated during boot
762 are distributed across NUMA nodes. Defaults on
763 for IA-64, off otherwise.
764 Format: 0 | 1 (for off | on)
766 hcl= [IA-64] SGI's Hardware Graph compatibility layer
768 hd= [EIDE] (E)IDE hard drive subsystem geometry
769 Format: <cyl>,<head>,<sect>
771 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
772 size of <nn>. This works even on boxes that have no
773 highmem otherwise. This also works to reduce highmem
774 size on bigger boxes.
776 highres= [KNL] Enable/disable high resolution timer mode.
777 Valid parameters: "on", "off"
781 See Documentation/isdn/README.HiSax.
783 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
784 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
785 On x86-64 and powerpc, this option can be specified
786 multiple times interleaved with hugepages= to reserve
787 huge pages of different sizes. Valid pages sizes on
788 x86-64 are 2M (when the CPU supports "pse") and 1G
789 (when the CPU supports the "pdpe1gb" cpuinfo flag)
790 Note that 1GB pages can only be allocated at boot time
791 using hugepages= and not freed afterwards.
793 [same as hugepagesz=] The size of the default
794 HugeTLB page size. This is the size represented by
795 the legacy /proc/ hugepages APIs, used for SHM, and
796 default size when mounting hugetlbfs filesystems.
797 Defaults to the default architecture's huge page size
802 i8042.debug [HW] Toggle i8042 debug mode
803 i8042.direct [HW] Put keyboard port into non-translated mode
804 i8042.dumbkbd [HW] Pretend that controller can only read data from
805 keyboard and cannot control its state
806 (Don't attempt to blink the leds)
807 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
808 i8042.nokbd [HW] Don't check/create keyboard port
809 i8042.noloop [HW] Disable the AUX Loopback command while probing
811 i8042.nomux [HW] Don't check presence of an active multiplexing
813 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
816 [HW] Frequency with which keyboard LEDs should blink
817 when kernel panics (default is 0.5 sec)
818 i8042.reset [HW] Reset the controller during init and cleanup
819 i8042.unlock [HW] Unlock (ignore) the keylock
823 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
824 indicates that the driver is running on unsupported
826 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
827 does not match list of supported models.
829 [HW] Report power status in /proc/i8k
830 (disabled by default)
831 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
834 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
835 See Documentation/mca.txt.
838 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
840 ide= [HW] (E)IDE subsystem
841 Format: ide=nodma or ide=doubler
842 See Documentation/ide/ide.txt.
844 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
845 See Documentation/ide/ide.txt.
848 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
849 Poll forces a polling idle loop that can slightly improves the performance
850 of waking up a idle CPU, but will use a lot of power and make the system
851 run hot. Not recommended.
852 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
853 to not use it because it doesn't save as much power as a normal idle
854 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
856 idle=halt. Halt is forced to be used for CPU idle.
857 In such case C2/C3 won't be used again.
858 idle=nomwait. Disable mwait for CPU C-states
860 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
861 Claim all unknown PCI IDE storage controllers.
863 ignore_loglevel [KNL]
864 Ignore loglevel setting - this will print /all/
865 kernel messages to the console. Useful for debugging.
868 Set number of hash buckets for inode cache.
871 See header of drivers/scsi/in2000.c.
875 Run specified binary instead of /sbin/init as init
878 initcall_debug [KNL] Trace initcalls as they are executed. Useful
879 for working out where the kernel is dying during
882 initrd= [BOOT] Specify the location of the initial ramdisk
884 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
902 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
904 Disable intel iommu driver.
905 igfx_off [Default Off]
906 By default, gfx is mapped as normal device. If a gfx
907 device has a dedicated DMAR unit, the DMAR unit is
908 bypassed by not enabling DMAR with this option. In
909 this case, gfx device will use physical address for
912 With this option iommu will not optimize to look
913 for io virtual address below 32 bit forcing dual
914 address cycle on pci bus for cards supporting greater
915 than 32 bit addressing. The default is to look
916 for translation below 32 bit and if not available
917 then look in the higher range.
919 With this option on every unmap_single operation will
920 result in a hardware IOTLB flush operation as opposed
921 to batching them for performance.
923 io_delay= [X86-32,X86-64] I/O delay method
925 Standard port 0x80 based delay
927 Alternate port 0xed based delay (needed on some systems)
929 Simple two microseconds delay
933 io7= [HW] IO7 for Marvel based alpha systems
934 See comment before marvel_specify_io7 in
935 arch/alpha/kernel/core_marvel.c.
938 See Documentation/filesystems/nfsroot.txt.
940 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
941 See comment before ip2_setup() in
942 drivers/char/ip2/ip2base.c.
944 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
945 See header of drivers/scsi/ips.c.
947 ports= [IP_VS_FTP] IPVS ftp helper module
949 Up to 8 (IP_VS_APP_MAX_PORTS) ports
951 Format: <port>,<port>....
954 When an interrupt is not handled search all handlers
955 for it. Intended to get systems with badly broken
959 When an interrupt is not handled search all handlers
960 for it. Also check all handlers each timer
961 interrupt. Intended to get systems with badly broken
965 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
967 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
969 <cpu number>,...,<cpu number>
971 <cpu number>-<cpu number> (must be a positive range in ascending order)
973 <cpu number>,...,<cpu number>-<cpu number>
974 This option can be used to specify one or more CPUs
975 to isolate from the general SMP balancing and scheduling
976 algorithms. The only way to move a process onto or off
977 an "isolated" CPU is via the CPU affinity syscalls.
978 <cpu number> begins at 0 and the maximum value is
979 "number of CPUs in system - 1".
981 This option is the preferred way to isolate CPUs. The
982 alternative -- manually setting the CPU mask of all
983 tasks in the system -- can cause problems and
984 suboptimal load balancer performance.
988 js= [HW,JOY] Analog joystick
989 See Documentation/input/joystick.txt.
991 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
992 specifies the amount of memory usable by the kernel
993 for non-movable allocations. The requested amount is
994 spread evenly throughout all nodes in the system. The
995 remaining memory in each node is used for Movable
996 pages. In the event, a node is too small to have both
997 kernelcore and Movable pages, kernelcore pages will
998 take priority and other nodes will have a larger number
999 of kernelcore pages. The Movable zone is used for the
1000 allocation of pages that may be reclaimed or moved
1001 by the page migration subsystem. This means that
1002 HugeTLB pages may not be allocated from this zone.
1003 Note that allocations like PTEs-from-HighMem still
1004 use the HighMem zone if it exists, and the Normal
1005 zone if it does not.
1007 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1008 is similar to kernelcore except it specifies the
1009 amount of memory used for migratable allocations.
1010 If both kernelcore and movablecore is specified,
1011 then kernelcore will be at *least* the specified
1012 value but may be more. If movablecore on its own
1013 is specified, the administrator must be careful
1014 that the amount of memory usable for all allocations
1019 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1022 kgdboc= [HW] kgdb over consoles.
1023 Requires a tty driver that supports console polling.
1024 (only serial suported for now)
1025 Format: <serial_device>[,baud]
1027 kmac= [MIPS] korina ethernet MAC address.
1028 Configure the RouterBoard 532 series on-chip
1029 Ethernet adapter MAC address.
1035 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1038 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1041 libata.dma= [LIBATA] DMA control
1042 libata.dma=0 Disable all PATA and SATA DMA
1043 libata.dma=1 PATA and SATA Disk DMA only
1044 libata.dma=2 ATAPI (CDROM) DMA only
1045 libata.dma=4 Compact Flash DMA only
1046 Combinations also work, so libata.dma=3 enables DMA
1047 for disks and CDROMs, but not CFs.
1049 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1053 libata.force= [LIBATA] Force configurations. The format is comma
1054 separated list of "[ID:]VAL" where ID is
1055 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1056 matching port, link or device. Basically, it matches
1057 the ATA ID string printed on console by libata. If
1058 the whole ID part is omitted, the last PORT and DEVICE
1059 values are used. If ID hasn't been specified yet, the
1060 configuration applies to all ports, links and devices.
1062 If only DEVICE is omitted, the parameter applies to
1063 the port and all links and devices behind it. DEVICE
1064 number of 0 either selects the first device or the
1065 first fan-out link behind PMP device. It does not
1066 select the host link. DEVICE number of 15 selects the
1067 host link and device attached to it.
1069 The VAL specifies the configuration to force. As long
1070 as there's no ambiguity shortcut notation is allowed.
1071 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1072 The following configurations can be forced.
1074 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1075 Any ID with matching PORT is used.
1077 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1079 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1080 udma[/][16,25,33,44,66,100,133] notation is also
1083 * [no]ncq: Turn on or off NCQ.
1085 * nohrst, nosrst, norst: suppress hard, soft
1088 If there are multiple matching configurations changing
1089 the same attribute, the last one is used.
1091 load_ramdisk= [RAM] List of ramdisks to load from floppy
1092 See Documentation/ramdisk.txt.
1094 lockd.nlm_grace_period=P [NFS] Assign grace period.
1097 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1100 lockd.nlm_timeout=T [NFS] Assign timeout value.
1103 lockd.nlm_udpport=M [NFS] Assign UDP port.
1106 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1109 loglevel= All Kernel Messages with a loglevel smaller than the
1110 console loglevel will be printed to the console. It can
1111 also be changed with klogd or other programs. The
1112 loglevels are defined as follows:
1114 0 (KERN_EMERG) system is unusable
1115 1 (KERN_ALERT) action must be taken immediately
1116 2 (KERN_CRIT) critical conditions
1117 3 (KERN_ERR) error conditions
1118 4 (KERN_WARNING) warning conditions
1119 5 (KERN_NOTICE) normal but significant condition
1120 6 (KERN_INFO) informational
1121 7 (KERN_DEBUG) debug-level messages
1123 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1124 Format: { n | nk | nM }
1125 n must be a power of two. The default size
1126 is set in the kernel config file.
1128 logo.nologo [FB] Disables display of the built-in Linux logo.
1129 This may be used to provide more screen space for
1130 kernel log messages and is useful when debugging
1131 kernel boot problems.
1133 lp=0 [LP] Specify parallel ports to use, e.g,
1134 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1135 lp=reset first parallel port). 'lp=0' disables the
1136 lp=auto printer driver. 'lp=reset' (which can be
1137 specified in addition to the ports) causes
1138 attached printers to be reset. Using
1139 lp=port1,port2,... specifies the parallel ports
1140 to associate lp devices with, starting with
1141 lp0. A port specification may be 'none' to skip
1142 that lp device, or a parport name such as
1143 'parport0'. Specifying 'lp=auto' instead of a
1144 port specification list means that device IDs
1145 from each port should be examined, to see if
1146 an IEEE 1284-compliant printer is attached; if
1147 so, the driver will manage that printer.
1148 See also header of drivers/char/lp.c.
1151 Sets loops_per_jiffy to given constant, thus avoiding
1152 time-consuming boot-time autodetection (up to 250 ms per
1153 CPU). 0 enables autodetection (default). To determine
1154 the correct value for your kernel, boot with normal
1155 autodetection and see what value is printed. Note that
1156 on SMP systems the preset will be applied to all CPUs,
1157 which is likely to cause problems if your CPUs need
1158 significantly divergent settings. An incorrect value
1159 will cause delays in the kernel to be wrong, leading to
1160 unpredictable I/O errors and other breakage. Although
1161 unlikely, in the extreme case this might damage your
1165 Format: <io>,<irq>,<dma>
1167 mac5380= [HW,SCSI] Format:
1168 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1170 machvec= [IA64] Force the use of a particular machine-vector
1171 (machvec) in a generic kernel.
1172 Example: machvec=hpzx1_swiotlb
1174 max_loop= [LOOP] Maximum number of loopback devices that can
1178 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1179 should make use of. maxcpus=n : n >= 0 limits the
1180 kernel to using 'n' processors. n=0 is a special case,
1181 it is equivalent to "nosmp", which also disables
1184 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1185 equal to this physical address is ignored.
1187 max_luns= [SCSI] Maximum number of LUNs to probe.
1188 Should be between 1 and 2^32-1.
1191 [SCSI] Maximum number of LUNs received.
1192 Should be between 1 and 16384.
1196 mce [X86-32] Machine Check Exception
1198 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1200 md= [HW] RAID subsystems devices and level
1201 See Documentation/md.txt.
1204 Format: <first>,<last>
1205 Specifies range of consoles to be captured by the MDA.
1207 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1208 Amount of memory to be used when the kernel is not able
1209 to see the whole system memory or for test.
1210 [X86-32] Use together with memmap= to avoid physical
1211 address space collisions. Without memmap= PCI devices
1212 could be placed at addresses belonging to unused RAM.
1214 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1218 [KNL,SH] Allow user to override the default size for
1219 per-device physically contiguous DMA buffers.
1221 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1222 E820 memory map, as specified by the user.
1223 Such memmap=exactmap lines can be constructed based on
1224 BIOS output or other requirements. See the memmap=nn@ss
1227 memmap=nn[KMG]@ss[KMG]
1228 [KNL] Force usage of a specific region of memory
1229 Region of memory to be used, from ss to ss+nn.
1231 memmap=nn[KMG]#ss[KMG]
1232 [KNL,ACPI] Mark specific memory as ACPI data.
1233 Region of memory to be used, from ss to ss+nn.
1235 memmap=nn[KMG]$ss[KMG]
1236 [KNL,ACPI] Mark specific memory as reserved.
1237 Region of memory to be used, from ss to ss+nn.
1238 Example: Exclude memory from 0x18690000-0x1869ffff
1239 memmap=64K$0x18690000
1241 memmap=0x10000$0x18690000
1243 memory_corruption_check=0/1 [X86]
1244 Some BIOSes seem to corrupt the first 64k of
1245 memory when doing things like suspend/resume.
1246 Setting this option will scan the memory
1247 looking for corruption. Enabling this will
1248 both detect corruption and prevent the kernel
1249 from using the memory being corrupted.
1250 However, its intended as a diagnostic tool; if
1251 repeatable BIOS-originated corruption always
1252 affects the same memory, you can use memmap=
1253 to prevent the kernel from using that memory.
1255 memory_corruption_check_size=size [X86]
1256 By default it checks for corruption in the low
1257 64k, making this memory unavailable for normal
1258 use. Use this parameter to scan for
1259 corruption in more or less memory.
1261 memory_corruption_check_period=seconds [X86]
1262 By default it checks for corruption every 60
1263 seconds. Use this parameter to check at some
1264 other rate. 0 disables periodic checking.
1266 memtest= [KNL,X86] Enable memtest
1268 range: 0,4 : pattern number
1269 default : 0 <disable>
1271 meye.*= [HW] Set MotionEye Camera parameters
1272 See Documentation/video4linux/meye.txt.
1274 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1275 Multi-Function General Purpose Timers on AMD Geode
1278 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1279 the BIOS has incorrectly applied a workaround. TinyBIOS
1280 version 0.98 is known to be affected, 0.99 fixes the
1281 problem by letting the user disable the workaround.
1286 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1287 parameter allows control of the logging verbosity for
1288 the additional memory initialisation checks. A value
1289 of 0 disables mminit logging and a level of 4 will
1290 log everything. Information is printed at KERN_DEBUG
1291 so loglevel=8 may also need to be specified.
1294 [MOUSE] Maximum time between finger touching and
1295 leaving touchpad surface for touch to be considered
1296 a tap and be reported as a left button click (for
1297 touchpads working in absolute mode only).
1299 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1300 reporting absolute coordinates, such as tablets
1301 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1302 reporting absolute coordinates, such as tablets
1307 MTD_Partition= [MTD]
1308 Format: <name>,<region-number>,<size>,<offset>
1310 MTD_Region= [MTD] Format:
1311 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1314 See drivers/mtd/cmdlinepart.c.
1317 ARM/S3C2412 JIVE boot control
1319 See arch/arm/mach-s3c2412/mach-jive.c
1321 mtouchusb.raw_coordinates=
1322 [HW] Make the MicroTouch USB driver use raw coordinates
1323 ('y', default) or cooked coordinates ('n')
1325 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1328 See header of drivers/scsi/NCR_D700.c.
1332 ncr53c400= [HW,SCSI]
1334 ncr53c400a= [HW,SCSI]
1336 ncr53c406a= [HW,SCSI]
1338 ncr53c8xx= [HW,SCSI]
1340 netdev= [NET] Network devices parameters
1341 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1342 Note that mem_start is often overloaded to mean
1343 something different and driver-specific.
1344 This usage is only documented in each driver source
1348 [NETFILTER] Enable connection tracking flow accounting
1349 0 to disable accounting
1350 1 to enable accounting
1351 Default value depends on CONFIG_NF_CT_ACCT that is
1352 going to be removed in 2.6.29.
1355 See Documentation/filesystems/nfsroot.txt.
1357 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1358 See Documentation/filesystems/nfsroot.txt.
1360 nfs.callback_tcpport=
1361 [NFS] set the TCP port on which the NFSv4 callback
1362 channel should listen.
1364 nfs.idmap_cache_timeout=
1365 [NFS] set the maximum lifetime for idmapper cache
1369 [NFS] enable 64-bit inode numbers.
1370 If zero, the NFS client will fake up a 32-bit inode
1371 number for the readdir() and stat() syscalls instead
1372 of returning the full 64-bit number.
1373 The default is to return 64-bit inode numbers.
1375 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1376 when a NMI is triggered.
1377 Format: [state][,regs][,debounce][,die]
1379 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1381 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1382 emulation library even if a 387 maths coprocessor
1385 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1386 caches in the slab allocator. Saves per-node memory,
1387 but will impact performance.
1391 noapic [SMP,APIC] Tells the kernel to not make use of any
1392 IOAPICs that may be present in the system.
1394 nobats [PPC] Do not use BATs for mapping kernel lowmem
1395 on "Classic" PPC cores.
1399 nodelayacct [KNL] Disable per-task delay accounting
1401 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1403 nodsp [SH] Disable hardware DSP at boot time.
1405 noefi [X86-32,X86-64] Disable EFI runtime services support.
1409 noexec [X86-32,X86-64]
1410 On X86-32 available only on PAE configured kernels.
1411 noexec=on: enable non-executable mappings (default)
1412 noexec=off: disable non-executable mappings
1415 This affects only 32-bit executables.
1416 noexec32=on: enable non-executable mappings (default)
1417 read doesn't imply executable mappings
1418 noexec32=off: disable non-executable mappings
1419 read implies executable mappings
1421 nofpu [SH] Disable hardware FPU at boot time.
1423 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1424 register save and restore. The kernel will only save
1425 legacy floating-point registers on task switch.
1427 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1431 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1432 instruction doesn't work correctly and not to
1435 nohalt [IA-64] Tells the kernel not to use the power saving
1436 function PAL_HALT_LIGHT when idle. This increases
1437 power-consumption. On the positive side, it reduces
1438 interrupt wake-up latency, which may improve performance
1439 in certain environments such as networked servers or
1442 nohz= [KNL] Boottime enable/disable dynamic ticks
1443 Valid arguments: on, off
1446 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1448 noirqdebug [X86-32] Disables the code which attempts to detect and
1449 disable unhandled interrupt sources.
1451 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1452 broken timer IRQ sources.
1454 noisapnp [ISAPNP] Disables ISA PnP code.
1456 noinitrd [RAM] Tells the kernel not to load any configured
1461 nojitter [IA64] Disables jitter checking for ITC timers.
1463 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1465 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1467 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1469 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1470 default x2apic cluster mode on platforms
1473 noltlbs [PPC] Do not use large page/tlb entries for kernel
1474 lowmem mapping on PPC40x.
1476 nomca [IA-64] Disable machine check abort handling
1478 nomce [X86-32] Machine Check Exception
1480 nomfgpt [X86-32] Disable Multi-Function General Purpose
1481 Timer usage (for AMD Geode machines).
1483 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1485 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1486 with UP alternatives
1488 noresidual [PPC] Don't use residual data on PReP machines.
1490 noresume [SWSUSP] Disables resume and restores original swap
1493 no-scroll [VGA] Disables scrollback.
1494 This is required for the Braillex ib80-piezo Braille
1495 reader made by F.H. Papenmeier (Germany).
1499 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1501 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1502 and disable the IO APIC. legacy for "maxcpus=0".
1504 nosoftlockup [KNL] Disable the soft-lockup detector.
1506 nosync [HW,M68K] Disables sync negotiation for all devices.
1508 notsc [BUGS=X86-32] Disable Time Stamp Counter
1510 nousb [USB] Disable the USB subsystem
1514 nptcg= [IA64] Override max number of concurrent global TLB
1515 purges which is reported from either PAL_VM_SUMMARY or
1518 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1519 one of ['zone', 'node', 'default'] can be specified
1520 This can be set from sysctl after boot.
1521 See Documentation/sysctl/vm.txt for details.
1523 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1525 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1526 Rather than timing out after 20 ms if an EC
1527 command is not properly ACKed, override the length
1528 of the timeout. We have interrupts disabled while
1529 waiting for the ACK, so if this is set too high
1530 interrupts *may* be lost!
1535 oprofile.timer= [HW]
1536 Use timer interrupt instead of performance counters
1538 osst= [HW,SCSI] SCSI Tape Driver
1539 Format: <buffer_size>,<write_threshold>
1540 See also Documentation/scsi/st.txt.
1542 panic= [KNL] Kernel behaviour on panic
1545 parkbd.port= [HW] Parallel port number the keyboard adapter is
1546 connected to, default is 0.
1548 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1549 0 for XT, 1 for AT (default is AT).
1552 parport= [HW,PPT] Specify parallel ports. 0 disables.
1553 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1554 Use 'auto' to force the driver to use any
1555 IRQ/DMA settings detected (the default is to
1556 ignore detected IRQ/DMA settings because of
1557 possible conflicts). You can specify the base
1558 address, IRQ, and DMA settings; IRQ and DMA
1559 should be numbers, or 'auto' (for using detected
1560 settings on that particular port), or 'nofifo'
1561 (to avoid using a FIFO even if it is detected).
1562 Parallel ports are assigned in the order they
1563 are specified on the command line, starting
1566 parport_init_mode= [HW,PPT]
1567 Configure VIA parallel port to operate in
1568 a specific mode. This is necessary on Pegasos
1569 computer where firmware has no options for setting
1570 up parallel port mode and sets it to spp.
1571 Currently this function knows 686a and 8231 chips.
1572 Format: [spp|ps2|epp|ecp|ecpepp]
1574 pas2= [HW,OSS] Format:
1575 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1578 See header of drivers/scsi/pas16.c.
1581 Halt all CPUs after the first oops has been printed for
1582 the specified number of seconds. This is to be used if
1583 your oopses keep scrolling off the screen.
1588 See header of drivers/block/paride/pcd.c.
1589 See also Documentation/paride.txt.
1591 pci=option[,option...] [PCI] various PCI subsystem options:
1592 off [X86] don't probe for the PCI bus
1593 bios [X86-32] force use of PCI BIOS, don't access
1594 the hardware directly. Use this if your machine
1595 has a non-standard PCI host bridge.
1596 nobios [X86-32] disallow use of PCI BIOS, only direct
1597 hardware access methods are allowed. Use this
1598 if you experience crashes upon bootup and you
1599 suspect they are caused by the BIOS.
1600 conf1 [X86] Force use of PCI Configuration
1602 conf2 [X86] Force use of PCI Configuration
1604 noaer [PCIE] If the PCIEAER kernel config parameter is
1605 enabled, this kernel boot option can be used to
1606 disable the use of PCIE advanced error reporting.
1607 nodomains [PCI] Disable support for multiple PCI
1608 root domains (aka PCI segments, in ACPI-speak).
1609 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1611 nomsi [MSI] If the PCI_MSI kernel config parameter is
1612 enabled, this kernel boot option can be used to
1613 disable the use of MSI interrupts system-wide.
1614 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1615 routing table. These calls are known to be buggy
1616 on several machines and they hang the machine
1617 when used, but on other computers it's the only
1618 way to get the interrupt routing table. Try
1619 this option if the kernel is unable to allocate
1620 IRQs or discover secondary PCI buses on your
1622 rom [X86] Assign address space to expansion ROMs.
1623 Use with caution as certain devices share
1624 address decoders between ROMs and other
1626 norom [X86] Do not assign address space to
1627 expansion ROMs that do not already have
1628 BIOS assigned address ranges.
1629 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1630 assigned automatically to PCI devices. You can
1631 make the kernel exclude IRQs of your ISA cards
1633 pirqaddr=0xAAAAA [X86] Specify the physical address
1634 of the PIRQ table (normally generated
1635 by the BIOS) if it is outside the
1636 F0000h-100000h range.
1637 lastbus=N [X86] Scan all buses thru bus #N. Can be
1638 useful if the kernel is unable to find your
1639 secondary buses and you want to tell it
1640 explicitly which ones they are.
1641 assign-busses [X86] Always assign all PCI bus
1642 numbers ourselves, overriding
1643 whatever the firmware may have done.
1644 usepirqmask [X86] Honor the possible IRQ mask stored
1645 in the BIOS $PIR table. This is needed on
1646 some systems with broken BIOSes, notably
1647 some HP Pavilion N5400 and Omnibook XE3
1648 notebooks. This will have no effect if ACPI
1649 IRQ routing is enabled.
1650 noacpi [X86] Do not use ACPI for IRQ routing
1651 or for PCI scanning.
1652 use_crs [X86] Use _CRS for PCI resource
1654 routeirq Do IRQ routing for all PCI devices.
1655 This is normally done in pci_enable_device(),
1656 so this option is a temporary workaround
1657 for broken drivers that don't call it.
1658 skip_isa_align [X86] do not align io start addr, so can
1659 handle more pci cards
1660 firmware [ARM] Do not re-enumerate the bus but instead
1661 just use the configuration from the
1662 bootloader. This is currently used on
1663 IXP2000 systems where the bus has to be
1664 configured a certain way for adjunct CPUs.
1665 noearly [X86] Don't do any early type 1 scanning.
1666 This might help on some broken boards which
1667 machine check when some devices' config space
1668 is read. But various workarounds are disabled
1669 and some IOMMU drivers will not work.
1670 bfsort Sort PCI devices into breadth-first order.
1671 This sorting is done to get a device
1672 order compatible with older (<= 2.4) kernels.
1673 nobfsort Don't sort PCI devices into breadth-first order.
1674 cbiosize=nn[KMG] The fixed amount of bus space which is
1675 reserved for the CardBus bridge's IO window.
1676 The default value is 256 bytes.
1677 cbmemsize=nn[KMG] The fixed amount of bus space which is
1678 reserved for the CardBus bridge's memory
1679 window. The default value is 64 megabytes.
1681 pcmv= [HW,PCMCIA] BadgePAD 4
1684 See Documentation/paride.txt.
1686 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1689 See arch/parisc/kernel/pdc_chassis.c
1692 See Documentation/paride.txt.
1695 See Documentation/paride.txt.
1697 pirq= [SMP,APIC] Manual mp-table setup
1698 See Documentation/i386/IO-APIC.txt.
1700 plip= [PPT,NET] Parallel port network link
1701 Format: { parport<nr> | timid | 0 }
1702 See also Documentation/parport.txt.
1704 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1705 Override pmtimer IOPort with a hex value.
1712 { on | off | curr | res | no-curr | no-res }
1715 [ISAPNP] Exclude IRQs for the autoconfiguration
1718 [ISAPNP] Exclude DMAs for the autoconfiguration
1720 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1721 Ranges are in pairs (I/O port base and size).
1724 [ISAPNP] Exclude memory regions for the
1726 Ranges are in pairs (memory base and size).
1729 Enables pr_debug()/dev_dbg() calls if
1730 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1731 be switched on/off via <debugfs>/dynamic_printk/modules
1733 print-fatal-signals=
1734 [KNL] debug: print fatal signals
1735 print-fatal-signals=1: print segfault info to
1739 printk.time= Show timing data prefixed to each printk message line
1740 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1742 profile= [KNL] Enable kernel profiling via /proc/profile
1743 Format: [schedule,]<number>
1744 Param: "schedule" - profile schedule points.
1745 Param: <number> - step/bucket size as a power of 2 for
1746 statistical time based profiling.
1747 Param: "sleep" - profile D-state sleeping (millisecs).
1748 Requires CONFIG_SCHEDSTATS
1749 Param: "kvm" - profile VM exits.
1751 processor.max_cstate= [HW,ACPI]
1752 Limit processor to maximum C-state
1753 max_cstate=9 overrides any DMI blacklist limit.
1755 processor.nocst [HW,ACPI]
1756 Ignore the _CST method to determine C-states,
1757 instead using the legacy FADT method
1759 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1761 See Documentation/ramdisk.txt.
1763 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1764 probe for; one of (bare|imps|exps|lifebook|any).
1765 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1767 psmouse.resetafter= [HW,MOUSE]
1768 Try to reset the device after so many bad packets
1771 [HW,MOUSE] Set desired mouse resolution, in dpi.
1772 psmouse.smartscroll=
1773 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1774 0 = disabled, 1 = enabled (default).
1776 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1778 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1781 See Documentation/paride.txt.
1784 [KNL] Number of legacy pty's. Overwrites compiled-in
1787 quiet [KNL] Disable most log messages
1792 See Documentation/md.txt.
1794 ramdisk_blocksize= [RAM]
1795 See Documentation/ramdisk.txt.
1797 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1798 See Documentation/ramdisk.txt.
1800 rcupdate.blimit= [KNL,BOOT]
1801 Set maximum number of finished RCU callbacks to process
1804 rcupdate.qhimark= [KNL,BOOT]
1805 Set threshold of queued
1806 RCU callbacks over which batch limiting is disabled.
1808 rcupdate.qlowmark= [KNL,BOOT]
1809 Set threshold of queued RCU callbacks below which
1810 batch limiting is re-enabled.
1814 Run specified binary instead of /init from the ramdisk,
1815 used for early userspace startup. See initrd.
1817 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1818 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1819 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1822 [KNL, SMP] Set scheduler's default relax_domain_level.
1823 See Documentation/cpusets.txt.
1825 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1827 reservetop= [X86-32]
1829 Reserves a hole at the top of the kernel virtual
1832 reset_devices [KNL] Force drivers to reset the underlying device
1833 during initialization.
1836 Specify the partition device for software suspend
1838 resume_offset= [SWSUSP]
1839 Specify the offset from the beginning of the partition
1840 given by "resume=" at which the swap header is located,
1841 in <PAGE_SIZE> units (needed only for swap files).
1842 See Documentation/power/swsusp-and-swap-files.txt
1844 retain_initrd [RAM] Keep initrd memory after extraction
1846 rhash_entries= [KNL,NET]
1847 Set number of hash buckets for route cache
1849 riscom8= [HW,SERIAL]
1850 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1852 ro [KNL] Mount root device read-only on boot
1854 root= [KNL] Root filesystem
1856 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1857 mount the root filesystem
1859 rootflags= [KNL] Set root filesystem mount option string
1861 rootfstype= [KNL] Set root filesystem type
1863 rootwait [KNL] Wait (indefinitely) for root device to show up.
1864 Useful for devices that are detected asynchronously
1865 (e.g. USB and MMC devices).
1867 root_plug.vendor_id=
1868 [ROOTPLUG] Override the default vendor ID
1870 root_plug.product_id=
1871 [ROOTPLUG] Override the default product ID
1874 [ROOTPLUG] Enable debugging output
1876 rw [KNL] Mount root device read-write on boot
1878 S [KNL] Run init in single mode
1881 See drivers/net/irda/sa1100_ir.c.
1883 sbni= [NET] Granch SBNI12 leased line adapter
1885 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1886 Format: <io>[,<timeout>[,<isapnp>]]
1888 scsi_debug_*= [SCSI]
1889 See drivers/scsi/scsi_debug.c.
1891 scsi_default_dev_flags=
1892 [SCSI] SCSI default device flags
1895 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1896 Format: <vendor>:<model>:<flags>
1897 (flags are integer value)
1899 scsi_logging_level= [SCSI] a bit mask of logging levels
1900 See drivers/scsi/scsi_logging.h for bits. Also
1901 settable via sysctl at dev.scsi.logging_level
1902 (/proc/sys/dev/scsi/logging_level).
1903 There is also a nice 'scsi_logging_level' script in the
1904 S390-tools package, available for download at
1905 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1907 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1908 discovered. async scans them in kernel threads,
1909 allowing boot to proceed. none ignores them, expecting
1910 user space to do the scan.
1912 selinux [SELINUX] Disable or enable SELinux at boot time.
1913 Format: { "0" | "1" }
1914 See security/selinux/Kconfig help text.
1917 Default value is set via kernel config option.
1918 If enabled at boot time, /selinux/disable can be used
1919 later to disable prior to initial policy load.
1921 selinux_compat_net =
1922 [SELINUX] Set initial selinux_compat_net flag value.
1923 Format: { "0" | "1" }
1924 0 -- use new secmark-based packet controls
1925 1 -- use legacy packet controls
1926 Default value is 0 (preferred).
1927 Value can be changed at runtime via
1928 /selinux/compat_net.
1930 serialnumber [BUGS=X86-32]
1933 Maximal number of shapers.
1935 show_msr= [x86] show boot-time MSR settings
1936 Format: { <integer> }
1937 Show boot-time (BIOS-initialized) MSR settings.
1938 The parameter means the number of CPUs to show,
1939 for example 1 means boot CPU only.
1942 See header of drivers/scsi/sim710.c.
1949 slub_debug[=options[,slabs]] [MM, SLUB]
1950 Enabling slub_debug allows one to determine the
1951 culprit if slab objects become corrupted. Enabling
1952 slub_debug can create guard zones around objects and
1953 may poison objects when not in use. Also tracks the
1954 last alloc / free. For more information see
1955 Documentation/vm/slub.txt.
1957 slub_max_order= [MM, SLUB]
1958 Determines the maximum allowed order for slabs.
1959 A high setting may cause OOMs due to memory
1960 fragmentation. For more information see
1961 Documentation/vm/slub.txt.
1963 slub_min_objects= [MM, SLUB]
1964 The minimum number of objects per slab. SLUB will
1965 increase the slab order up to slub_max_order to
1966 generate a sufficiently large slab able to contain
1967 the number of objects indicated. The higher the number
1968 of objects the smaller the overhead of tracking slabs
1969 and the less frequently locks need to be acquired.
1970 For more information see Documentation/vm/slub.txt.
1972 slub_min_order= [MM, SLUB]
1973 Determines the mininum page order for slabs. Must be
1974 lower than slub_max_order.
1975 For more information see Documentation/vm/slub.txt.
1977 slub_nomerge [MM, SLUB]
1978 Disable merging of slabs with similar size. May be
1979 necessary if there is some reason to distinguish
1980 allocs to different slabs. Debug options disable
1981 merging on their own.
1982 For more information see Documentation/vm/slub.txt.
1985 Format: <io1>[,<io2>[,...,<io8>]]
1987 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1988 attempt to substitute SMP alternatives once at boot.
1990 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1991 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1992 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1993 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1994 smsc-ircc2.ircc_irq= [HW] IRQ line
1995 smsc-ircc2.ircc_dma= [HW] DMA channel
1996 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1997 0: Toshiba Satellite 1800 (GP data pin select)
1998 1: Fast pin select (default)
2001 snd-ad1816a= [HW,ALSA]
2003 snd-ad1848= [HW,ALSA]
2005 snd-ali5451= [HW,ALSA]
2007 snd-als100= [HW,ALSA]
2009 snd-als4000= [HW,ALSA]
2011 snd-azt2320= [HW,ALSA]
2013 snd-cmi8330= [HW,ALSA]
2015 snd-cmipci= [HW,ALSA]
2017 snd-cs4231= [HW,ALSA]
2019 snd-cs4232= [HW,ALSA]
2021 snd-cs4236= [HW,ALSA]
2023 snd-cs4281= [HW,ALSA]
2025 snd-cs46xx= [HW,ALSA]
2027 snd-dt019x= [HW,ALSA]
2029 snd-dummy= [HW,ALSA]
2031 snd-emu10k1= [HW,ALSA]
2033 snd-ens1370= [HW,ALSA]
2035 snd-ens1371= [HW,ALSA]
2037 snd-es968= [HW,ALSA]
2039 snd-es1688= [HW,ALSA]
2041 snd-es18xx= [HW,ALSA]
2043 snd-es1938= [HW,ALSA]
2045 snd-es1968= [HW,ALSA]
2047 snd-fm801= [HW,ALSA]
2049 snd-gusclassic= [HW,ALSA]
2051 snd-gusextreme= [HW,ALSA]
2053 snd-gusmax= [HW,ALSA]
2057 snd-ice1712= [HW,ALSA]
2059 snd-intel8x0= [HW,ALSA]
2061 snd-interwave= [HW,ALSA]
2066 snd-korg1212= [HW,ALSA]
2068 snd-maestro3= [HW,ALSA]
2070 snd-mpu401= [HW,ALSA]
2072 snd-mtpav= [HW,ALSA]
2074 snd-nm256= [HW,ALSA]
2076 snd-opl3sa2= [HW,ALSA]
2084 snd-opti93x= [HW,ALSA]
2088 snd-rme32= [HW,ALSA]
2090 snd-rme96= [HW,ALSA]
2092 snd-rme9652= [HW,ALSA]
2098 snd-sbawe= [HW,ALSA]
2100 snd-serial= [HW,ALSA]
2102 snd-sgalaxy= [HW,ALSA]
2104 snd-sonicvibes= [HW,ALSA]
2109 snd-sun-cs4231= [HW,ALSA]
2111 snd-trident= [HW,ALSA]
2113 snd-usb-audio= [HW,ALSA,USB]
2115 snd-via82xx= [HW,ALSA]
2117 snd-virmidi= [HW,ALSA]
2119 snd-wavefront= [HW,ALSA]
2121 snd-ymfpci= [HW,ALSA]
2124 [KNL] Should the soft-lockup detector generate panics.
2126 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2127 See Documentation/sonypi.txt
2129 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2130 See Documentation/specialix.txt.
2132 spia_io_base= [HW,MTD]
2138 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2140 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2141 See Documentation/scsi/st.txt.
2145 Set the STI (builtin display/keyboard on the HP-PARISC
2146 machines) console (graphic card) which should be used
2147 as the initial boot-console.
2148 See also comment in drivers/video/console/sticore.c.
2151 See comment in drivers/video/console/sticore.c.
2154 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2158 Control how the NFS server code allocates CPUs to
2159 service thread pools. Depending on how many NICs
2160 you have and where their interrupts are bound, this
2161 option will affect which CPUs will do NFS serving.
2162 Note: this parameter cannot be changed while the
2163 NFS server is running.
2165 auto the server chooses an appropriate mode
2166 automatically using heuristics
2167 global a single global pool contains all CPUs
2168 percpu one pool for each CPU
2169 pernode one pool for each NUMA node (equivalent
2170 to global on non-NUMA machines)
2172 swiotlb= [IA-64] Number of I/O TLB slabs
2176 sym53c416= [HW,SCSI]
2177 See header of drivers/scsi/sym53c416.c.
2179 sysrq_always_enabled
2181 Ignore sysrq setting - this boot parameter will
2182 neutralize any effect of /proc/sys/kernel/sysrq.
2183 Useful for debugging.
2186 See header of drivers/scsi/t128.c.
2190 test_suspend= [SUSPEND]
2191 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2192 standby suspend) as the system sleep state to briefly
2193 enter during system startup. The system is woken from
2194 this state using a wakeup-capable RTC alarm.
2196 thash_entries= [KNL,NET]
2197 Set number of hash buckets for TCP connection
2199 thermal.act= [HW,ACPI]
2200 -1: disable all active trip points in all thermal zones
2201 <degrees C>: override all lowest active trip points
2203 thermal.crt= [HW,ACPI]
2204 -1: disable all critical trip points in all thermal zones
2205 <degrees C>: lower all critical trip points
2207 thermal.nocrt= [HW,ACPI]
2208 Set to disable actions on ACPI thermal zone
2209 critical and hot trip points.
2211 thermal.off= [HW,ACPI]
2212 1: disable ACPI thermal control
2214 thermal.psv= [HW,ACPI]
2215 -1: disable all passive trip points
2216 <degrees C>: override all passive trip points to this value
2218 thermal.tzp= [HW,ACPI]
2219 Specify global default ACPI thermal zone polling rate
2220 <deci-seconds>: poll all this frequency
2221 0: no polling (default)
2224 See comment before function dc390_setup() in
2225 drivers/scsi/tmscsim.c.
2229 trix= [HW,OSS] MediaTrix AudioTrix Pro
2231 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2233 turbografx.map[2|3]= [HW,JOY]
2234 TurboGraFX parallel port interface
2236 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2237 See also Documentation/input/joystick-parport.txt
2239 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2240 See header of drivers/scsi/u14-34f.c.
2249 [USB] Ignore overcurrent events (default N).
2250 Some badly-designed motherboards generate lots of
2251 bogus events, for ports that aren't wired to
2252 anything. Set this parameter to avoid log spamming.
2253 Note that genuine overcurrent events won't be
2258 Set unknown_nmi_panic=1 early on boot.
2260 usbcore.autosuspend=
2261 [USB] The autosuspend time delay (in seconds) used
2262 for newly-detected USB devices (default 2). This
2263 is the time required before an idle device will be
2264 autosuspended. Devices for which the delay is set
2265 to a negative value won't be autosuspended at all.
2267 usbcore.usbfs_snoop=
2268 [USB] Set to log all usbfs traffic (default 0 = off).
2270 usbcore.blinkenlights=
2271 [USB] Set to cycle leds on hubs (default 0 = off).
2273 usbcore.old_scheme_first=
2274 [USB] Start with the old device initialization
2275 scheme (default 0 = off).
2277 usbcore.use_both_schemes=
2278 [USB] Try the other device initialization scheme
2279 if the first one fails (default 1 = enabled).
2281 usbcore.initial_descriptor_timeout=
2282 [USB] Specifies timeout for the initial 64-byte
2283 USB_REQ_GET_DESCRIPTOR request in milliseconds
2284 (default 5000 = 5.0 seconds).
2287 [USBHID] The interval which mice are to be polled at.
2289 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2290 kernel's map of available physical RAM.
2292 vdso= [X86-32,SH,x86-64]
2293 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2294 vdso=1: enable VDSO (default)
2295 vdso=0: disable VDSO mapping
2297 vdso32= [X86-32,X86-64]
2298 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2299 vdso32=1: enable 32-bit VDSO (default)
2300 vdso32=0: disable 32-bit VDSO mapping
2303 vector=percpu: enable percpu vector domain
2305 video= [FB] Frame buffer configuration
2306 See Documentation/fb/modedb.txt.
2308 vga= [BOOT,X86-32] Select a particular video mode
2309 See Documentation/i386/boot.txt and
2310 Documentation/svga.txt.
2311 Use vga=ask for menu.
2312 This is actually a boot loader parameter; the value is
2313 passed to the kernel using a special protocol.
2315 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2316 size of <nn>. This can be used to increase the
2317 minimum size (128MB on x86). It can also be used to
2318 decrease the size and leave more room for directly
2321 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2324 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2327 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2330 waveartist= [HW,OSS]
2331 Format: <io>,<irq>,<dma>,<dma2>
2334 See header of drivers/scsi/wd33c93.c.
2337 See header of drivers/scsi/wd7000.c.
2340 See Documentation/watchdog/wdt.txt.
2342 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2343 xd_geo= See header of drivers/block/xd.c.
2345 xirc2ps_cs= [NET,PCMCIA]
2347 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2349 norandmaps Don't use address space randomization
2350 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2352 ______________________________________________________________________
2356 Add documentation for ALSA options.
2357 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob