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 .
105 In addition, the following text indicates that the option:
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
111 Parameters denoted with BOOT are actually interpreted by the boot
112 loader, and have no meaning to the kernel directly.
113 Do not modify the syntax of boot loader parameters without extreme
114 need or coordination with <Documentation/i386/boot.txt>.
116 There are also arch-specific kernel-parameters not documented here.
117 See for example <Documentation/x86_64/boot-options.txt>.
119 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120 a trailing = on the name of any parameter states that that parameter will
121 be entered as an environment variable, whereas its absence indicates that
122 it will appear as a kernel argument readable via /proc/cmdline by programs
123 running once the system is up.
125 The number of kernel parameters is not limited, but the length of the
126 complete command line (parameters including spaces etc.) is limited to
127 a fixed number of characters. This limit depends on the architecture
128 and is between 256 and 4096 characters. It is defined in the file
129 ./include/asm/setup.h as COMMAND_LINE_SIZE.
132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
134 Format: { force | off | ht | strict | noirq }
135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
139 strict -- Be less tolerant of platforms that are not
140 strictly ACPI specification compliant.
142 See also Documentation/power/pm.txt, pci=noacpi
144 acpi_apic_instance= [ACPI, IOAPIC]
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
150 acpi_sleep= [HW,ACPI] Sleep options
151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
163 Format: { level | edge | high | low }
165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
175 Format: <irq>,<irq>...
177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
178 Format: <irq>,<irq>...
180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
190 acpi_serialize [HW,ACPI] force serialization of AML methods
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
200 acpi.debug_layer= [HW,ACPI]
202 Each bit of the <int> indicates an ACPI debug layer,
203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
217 acpi.debug_level= [HW,ACPI]
219 Each bit of the <int> indicates an ACPI debug level,
220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
235 acpi_pm_good [X86-32,X86-64]
236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
250 The kernel tries to set a reasonable default.
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
260 See header of drivers/scsi/advansys.c.
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
270 See Documentation/scsi/aha152x.txt.
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
276 See Documentation/scsi/aic7xxx.txt.
279 See Documentation/scsi/aic79xx.txt.
281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
287 fullflush - enable flushing of IO/TLB entries when
288 they are unmapped. Otherwise they are
289 flushed before they will be reused, which
292 amd_iommu_size= [HW,X86-64]
293 Define the size of the aperture for the AMD IOMMU
294 driver. Possible values are:
295 '32M', '64M' (default), '128M', '256M', '512M', '1G'
297 amijoy.map= [HW,JOY] Amiga joystick support
298 Map of devices attached to JOY0DAT and JOY1DAT
300 See also Documentation/kernel/input/joystick.txt
302 analog.map= [HW,JOY] Analog joystick and gamepad support
303 Specifies type or capabilities of an analog joystick
304 connected to one of 16 gameports
305 Format: <type1>,<type2>,..<type16>
308 Power management functions (SPARCstation-4/5 + deriv.)
310 Disable APC CPU standby support. SPARCstation-Fox does
311 not play well with APC CPU idle - disable it if you have
312 APC and your system crashes randomly.
314 apic= [APIC,i386] Advanced Programmable Interrupt Controller
315 Change the output verbosity whilst booting
316 Format: { quiet (default) | verbose | debug }
317 Change the amount of debugging information output
318 when initialising the APIC and IO-APIC components.
320 apm= [APM] Advanced Power Management
321 See header of arch/x86/kernel/apm_32.c.
323 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
324 Format: <io>,<irq>,<nodeID>
328 atarimouse= [HW,MOUSE] Atari Mouse
330 atascsi= [HW,SCSI] Atari SCSI
332 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
333 EzKey and similar keyboards
335 atkbd.reset= [HW] Reset keyboard during initialization
337 atkbd.set= [HW] Select keyboard code set
338 Format: <int> (2 = AT (default), 3 = PS/2)
340 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
343 atkbd.softraw= [HW] Choose between synthetic and real raw mode
344 Format: <bool> (0 = real, 1 = synthetic (default))
346 atkbd.softrepeat= [HW]
347 Use software keyboard repeat
351 baycom_epp= [HW,AX25]
354 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
356 See header of drivers/net/hamradio/baycom_par.c.
358 baycom_ser_fdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
360 Format: <io>,<irq>,<mode>[,<baud>]
361 See header of drivers/net/hamradio/baycom_ser_fdx.c.
363 baycom_ser_hdx= [HW,AX25]
364 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
365 Format: <io>,<irq>,<mode>
366 See header of drivers/net/hamradio/baycom_ser_hdx.c.
368 boot_delay= Milliseconds to delay each printk during boot.
369 Values larger than 10 seconds (10000) are changed to
373 bootmem_debug [KNL] Enable bootmem allocator debug messages.
375 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
376 bttv.radio= Most important insmod options are available as
378 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
379 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
382 See drivers/scsi/BusLogic.c, comment before function
383 BusLogic_ParseDriverOptions().
385 c101= [NET] Moxa C101 synchronous serial card
387 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
388 Sometimes CPU hardware bugs make them report the cache
389 size incorrectly. The kernel will attempt work arounds
390 to fix known problems, but for some CPUs it is not
391 possible to determine what the correct size should be.
392 This option provides an override for these situations.
394 security= [SECURITY] Choose a security module to enable at boot.
395 If this boot parameter is not specified, only the first
396 security module asking for security registration will be
397 loaded. An invalid security module name will be treated
398 as if no module has been chosen.
401 [SECURITY] Disable capabilities. This would normally
402 be used only if an alternative security model is to be
403 configured. Potentially dangerous and should only be
404 used if you are entirely sure of the consequences.
406 ccw_timeout_log [S390]
407 See Documentation/s390/CommonIO for details.
409 cgroup_disable= [KNL] Disable a particular controller
410 Format: {name of the controller(s) to disable}
411 {Currently supported controllers - "memory"}
413 checkreqprot [SELINUX] Set initial checkreqprot flag value.
414 Format: { "0" | "1" }
415 See security/selinux/Kconfig help text.
416 0 -- check protection applied by kernel (includes
417 any implied execute protection).
418 1 -- check protection requested by application.
419 Default value is set via a kernel config option.
420 Value can be changed at runtime via
421 /selinux/checkreqprot.
424 See Documentation/s390/CommonIO for details.
426 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
428 Forces specified clocksource (if available) to be used
429 when calculating gettimeofday(). If specified
430 clocksource is not available, it defaults to PIT.
431 Format: { pit | tsc | cyclone | pmtmr }
433 clocksource= [GENERIC_TIME] Override the default clocksource
435 Override the default clocksource and use the clocksource
436 with the name specified.
437 Some clocksource names to choose from, depending on
439 [all] jiffies (this is the base, fallback clocksource)
441 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
442 pxa_timer,timer3,32k_counter,timer0_1
444 [X86-32] pit,hpet,tsc,vmi-timer;
445 scx200_hrt on Geode; cyclone on IBM x440
453 clearcpuid=BITNUM [X86]
454 Disable CPUID feature X for the kernel. See
455 include/asm-x86/cpufeature.h for the valid bit numbers.
456 Note the Linux specific bits are not necessarily
457 stable over kernel options, but the vendor specific
459 Also note that user programs calling CPUID directly
460 or using the feature without checking anything
461 will still see it. This just prevents it from
462 being used by the kernel or shown in /proc/cpuinfo.
463 Also note the kernel might malfunction if you disable
466 code_bytes [IA32/X86_64] How many bytes of object code to print
471 hpet= [X86-32,HPET] option to control HPET usage
472 Format: { enable (default) | disable | force }
473 disable: disable HPET and use PIT instead
474 force: allow force enabled of undocumented chips (ICH4,
477 com20020= [HW,NET] ARCnet - COM20020 chipset
479 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
481 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
485 ARCnet - COM90xx chipset (memory-mapped buffers)
486 Format: <io>[,<irq>[,<memstart>]]
488 condev= [HW,S390] console device
491 console= [KNL] Output console device and options.
493 tty<n> Use the virtual console device <n>.
497 Use the specified serial port. The options are of
498 the form "bbbbpnf", where "bbbb" is the baud rate,
499 "p" is parity ("n", "o", or "e"), "n" is number of
500 bits, and "f" is flow control ("r" for RTS or
501 omit it). Default is "9600n8".
503 See Documentation/serial-console.txt for more
505 Documentation/networking/netconsole.txt for an
508 uart[8250],io,<addr>[,options]
509 uart[8250],mmio,<addr>[,options]
510 Start an early, polled-mode console on the 8250/16550
511 UART at the specified I/O port or MMIO address,
512 switching to the matching ttyS device later. The
513 options are the same as for ttyS, above.
515 If the device connected to the port is not a TTY but a braille
516 device, prepend "brl," before the device type, for instance
518 For now, only VisioBraille is supported.
520 earlycon= [KNL] Output early console device and options.
521 uart[8250],io,<addr>[,options]
522 uart[8250],mmio,<addr>[,options]
523 Start an early, polled-mode console on the 8250/16550
524 UART at the specified I/O port or MMIO address.
525 The options are the same as for ttyS, above.
528 [HW] Never suspend the console
529 Disable suspending of consoles during suspend and
530 hibernate operations. Once disabled, debugging
531 messages can reach various consoles while the rest
532 of the system is being put to sleep (ie, while
533 debugging driver suspend/resume hooks). This may
534 not work reliably with all consoles, but is known
535 to work with serial and VGA consoles.
537 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
539 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
541 crashkernel=nn[KMG]@ss[KMG]
542 [KNL] Reserve a chunk of physical memory to
543 hold a kernel to switch to with kexec on panic.
545 crashkernel=range1:size1[,range2:size2,...][@offset]
546 [KNL] Same as above, but depends on the memory
547 in the running system. The syntax of range is
548 start-[end] where start and end are both
549 a memory unit (amount[KMG]). See also
550 Documentation/kdump/kdump.txt for a example.
553 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
558 cs89x0_media= [HW,NET]
559 Format: { rj45 | aui | bnc }
562 See header of drivers/s390/block/dasd_devmap.c.
564 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
565 (one device per port)
566 Format: <port#>,<type>
567 See also Documentation/input/joystick-parport.txt
569 debug [KNL] Enable kernel debugging (events log level).
572 [KNL] verbose self-tests
574 Print debugging info while doing the locking API
576 We default to 0 (no extra messages), setting it to
577 1 will print _a lot_ more information - normally
578 only useful to kernel developers.
580 debug_objects [KNL] Enable object debugging
582 debugpat [X86] Enable PAT debugging
584 decnet.addr= [HW,NET]
585 Format: <area>[,<node>]
586 See also Documentation/networking/decnet.txt.
589 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
590 Change the default blue palette of the console.
591 This is a 16-member array composed of values
595 Format: <green0>,<green1>,<green2>,...,<green15>
596 Change the default green palette of the console.
597 This is a 16-member array composed of values
601 Format: <red0>,<red1>,<red2>,...,<red15>
602 Change the default red palette of the console.
603 This is a 16-member array composed of values
609 Set system-wide default UTF-8 mode for all tty's.
610 Default is 1, i.e. UTF-8 mode is enabled for all
611 newly opened terminals.
614 Set number of hash buckets for dentry cache.
617 IO parameters + enable/disable command.
619 digiepca= [HW,SERIAL]
620 See drivers/char/README.epca and
621 Documentation/digiepca.txt.
623 disable_mtrr_cleanup [X86]
624 enable_mtrr_cleanup [X86]
625 The kernel tries to adjust MTRR layout from continuous
626 to discrete, to make X server driver able to add WB
627 entry later. This parameter enables/disables that.
629 mtrr_chunk_size=nn[KMG] [X86]
630 used for mtrr cleanup. It is largest continous chunk
631 that could hold holes aka. UC entries.
633 mtrr_gran_size=nn[KMG] [X86]
634 Used for mtrr cleanup. It is granularity of mtrr block.
636 Large value could prevent small alignment from
639 mtrr_spare_reg_nr=n [X86]
641 Range: 0,7 : spare reg number
643 Used for mtrr cleanup. It is spare mtrr entries number.
644 Set to 2 or more if your graphical card needs more.
646 disable_mtrr_trim [X86, Intel and AMD only]
647 By default the kernel will trim any uncacheable
648 memory out of your available memory pool based on
649 MTRR settings. This parameter disables that behavior,
650 possibly causing your machine to run very slowly.
652 dmasound= [HW,OSS] Sound subsystem buffers
658 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
660 earlyprintk=serial[,ttySn[,baudrate]]
663 Append ",keep" to not disable it when the real console
666 Only vga or serial or usb debug port at a time.
668 Currently only ttyS0 and ttyS1 are supported.
670 Interaction with the standard serial driver is not
673 The VGA output is eventually overwritten by the real
679 Format: {"off" | "on" | "skip[mbr]"}
681 eisa_irq_edge= [PARISC,HW]
682 See header of drivers/parisc/eisa.c.
685 See comment before function elanfreq_setup() in
686 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
690 See Documentation/block/as-iosched.txt and
691 Documentation/block/deadline-iosched.txt for details.
693 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
694 Specifies physical address of start of kernel core
695 image elf header. Generally kexec loader will
696 pass this option to capture kernel.
697 See Documentation/kdump/kdump.txt for details.
699 enforcing [SELINUX] Set initial enforcing status.
701 See security/selinux/Kconfig help text.
702 0 -- permissive (log only, no denials).
703 1 -- enforcing (deny and log).
705 Value can be changed at runtime via /selinux/enforce.
708 Format: <spdif>,[<nomix>,[<amplifier>]]
709 See also header of sound/oss/es1371.c.
711 ether= [HW,NET] Ethernet cards parameters
712 This option is obsoleted by the "netdev=" option, which
713 has equivalent usage. See its documentation for details.
715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
720 fail_make_request=[KNL]
721 General fault injection mechanism.
722 Format: <interval>,<probability>,<space>,<times>
723 See also /Documentation/fault-injection/.
726 See header of drivers/scsi/fd_mcs.c.
729 See header of drivers/scsi/fdomain.c.
732 See Documentation/floppy.txt.
734 force_pal_cache_flush
735 [IA-64] Avoid check_sal_cache_flush which may hang on
736 buggy SAL_CACHE_FLUSH implementations. Using this
737 parameter will force ia64_sal_cache_flush to call
738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
742 support via parallel port (up to 5 devices per port)
743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
744 See also Documentation/input/joystick-parport.txt
748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
753 See header of drivers/scsi/gdth.c.
755 gpt [EFI] Forces disk with valid GPT signature but
756 invalid Protective MBR to be treated as GPT.
760 hashdist= [KNL,NUMA] Large hashes allocated during boot
761 are distributed across NUMA nodes. Defaults on
762 for IA-64, off otherwise.
763 Format: 0 | 1 (for off | on)
765 hcl= [IA-64] SGI's Hardware Graph compatibility layer
767 hd= [EIDE] (E)IDE hard drive subsystem geometry
768 Format: <cyl>,<head>,<sect>
770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
771 size of <nn>. This works even on boxes that have no
772 highmem otherwise. This also works to reduce highmem
773 size on bigger boxes.
775 highres= [KNL] Enable/disable high resolution timer mode.
776 Valid parameters: "on", "off"
780 See Documentation/isdn/README.HiSax.
782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
784 On x86-64 and powerpc, this option can be specified
785 multiple times interleaved with hugepages= to reserve
786 huge pages of different sizes. Valid pages sizes on
787 x86-64 are 2M (when the CPU supports "pse") and 1G
788 (when the CPU supports the "pdpe1gb" cpuinfo flag)
789 Note that 1GB pages can only be allocated at boot time
790 using hugepages= and not freed afterwards.
792 [same as hugepagesz=] The size of the default
793 HugeTLB page size. This is the size represented by
794 the legacy /proc/ hugepages APIs, used for SHM, and
795 default size when mounting hugetlbfs filesystems.
796 Defaults to the default architecture's huge page size
801 i8042.debug [HW] Toggle i8042 debug mode
802 i8042.direct [HW] Put keyboard port into non-translated mode
803 i8042.dumbkbd [HW] Pretend that controller can only read data from
804 keyboard and cannot control its state
805 (Don't attempt to blink the leds)
806 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
807 i8042.nokbd [HW] Don't check/create keyboard port
808 i8042.noloop [HW] Disable the AUX Loopback command while probing
810 i8042.nomux [HW] Don't check presence of an active multiplexing
812 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
815 [HW] Frequency with which keyboard LEDs should blink
816 when kernel panics (default is 0.5 sec)
817 i8042.reset [HW] Reset the controller during init and cleanup
818 i8042.unlock [HW] Unlock (ignore) the keylock
822 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
823 indicates that the driver is running on unsupported
825 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
826 does not match list of supported models.
828 [HW] Report power status in /proc/i8k
829 (disabled by default)
830 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
833 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
834 See Documentation/mca.txt.
837 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
839 ide= [HW] (E)IDE subsystem
840 Format: ide=nodma or ide=doubler
841 See Documentation/ide/ide.txt.
843 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
844 See Documentation/ide/ide.txt.
847 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
848 Poll forces a polling idle loop that can slightly improves the performance
849 of waking up a idle CPU, but will use a lot of power and make the system
850 run hot. Not recommended.
851 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
852 to not use it because it doesn't save as much power as a normal idle
853 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
855 idle=halt. Halt is forced to be used for CPU idle.
856 In such case C2/C3 won't be used again.
857 idle=nomwait. Disable mwait for CPU C-states
859 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
860 Claim all unknown PCI IDE storage controllers.
862 ignore_loglevel [KNL]
863 Ignore loglevel setting - this will print /all/
864 kernel messages to the console. Useful for debugging.
867 Set number of hash buckets for inode cache.
870 See header of drivers/scsi/in2000.c.
874 Run specified binary instead of /sbin/init as init
877 initcall_debug [KNL] Trace initcalls as they are executed. Useful
878 for working out where the kernel is dying during
881 initrd= [BOOT] Specify the location of the initial ramdisk
883 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
901 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
903 Disable intel iommu driver.
904 igfx_off [Default Off]
905 By default, gfx is mapped as normal device. If a gfx
906 device has a dedicated DMAR unit, the DMAR unit is
907 bypassed by not enabling DMAR with this option. In
908 this case, gfx device will use physical address for
911 With this option iommu will not optimize to look
912 for io virtual address below 32 bit forcing dual
913 address cycle on pci bus for cards supporting greater
914 than 32 bit addressing. The default is to look
915 for translation below 32 bit and if not available
916 then look in the higher range.
918 With this option on every unmap_single operation will
919 result in a hardware IOTLB flush operation as opposed
920 to batching them for performance.
922 io_delay= [X86-32,X86-64] I/O delay method
924 Standard port 0x80 based delay
926 Alternate port 0xed based delay (needed on some systems)
928 Simple two microseconds delay
932 io7= [HW] IO7 for Marvel based alpha systems
933 See comment before marvel_specify_io7 in
934 arch/alpha/kernel/core_marvel.c.
937 See Documentation/filesystems/nfsroot.txt.
939 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
940 See comment before ip2_setup() in
941 drivers/char/ip2/ip2base.c.
943 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
944 See header of drivers/scsi/ips.c.
946 ports= [IP_VS_FTP] IPVS ftp helper module
948 Up to 8 (IP_VS_APP_MAX_PORTS) ports
950 Format: <port>,<port>....
953 When an interrupt is not handled search all handlers
954 for it. Intended to get systems with badly broken
958 When an interrupt is not handled search all handlers
959 for it. Also check all handlers each timer
960 interrupt. Intended to get systems with badly broken
964 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
966 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
968 <cpu number>,...,<cpu number>
970 <cpu number>-<cpu number> (must be a positive range in ascending order)
972 <cpu number>,...,<cpu number>-<cpu number>
973 This option can be used to specify one or more CPUs
974 to isolate from the general SMP balancing and scheduling
975 algorithms. The only way to move a process onto or off
976 an "isolated" CPU is via the CPU affinity syscalls.
977 <cpu number> begins at 0 and the maximum value is
978 "number of CPUs in system - 1".
980 This option is the preferred way to isolate CPUs. The
981 alternative -- manually setting the CPU mask of all
982 tasks in the system -- can cause problems and
983 suboptimal load balancer performance.
987 js= [HW,JOY] Analog joystick
988 See Documentation/input/joystick.txt.
990 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
991 specifies the amount of memory usable by the kernel
992 for non-movable allocations. The requested amount is
993 spread evenly throughout all nodes in the system. The
994 remaining memory in each node is used for Movable
995 pages. In the event, a node is too small to have both
996 kernelcore and Movable pages, kernelcore pages will
997 take priority and other nodes will have a larger number
998 of kernelcore pages. The Movable zone is used for the
999 allocation of pages that may be reclaimed or moved
1000 by the page migration subsystem. This means that
1001 HugeTLB pages may not be allocated from this zone.
1002 Note that allocations like PTEs-from-HighMem still
1003 use the HighMem zone if it exists, and the Normal
1004 zone if it does not.
1006 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1007 is similar to kernelcore except it specifies the
1008 amount of memory used for migratable allocations.
1009 If both kernelcore and movablecore is specified,
1010 then kernelcore will be at *least* the specified
1011 value but may be more. If movablecore on its own
1012 is specified, the administrator must be careful
1013 that the amount of memory usable for all allocations
1018 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1021 kgdboc= [HW] kgdb over consoles.
1022 Requires a tty driver that supports console polling.
1023 (only serial suported for now)
1024 Format: <serial_device>[,baud]
1026 kmac= [MIPS] korina ethernet MAC address.
1027 Configure the RouterBoard 532 series on-chip
1028 Ethernet adapter MAC address.
1034 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1037 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1040 libata.dma= [LIBATA] DMA control
1041 libata.dma=0 Disable all PATA and SATA DMA
1042 libata.dma=1 PATA and SATA Disk DMA only
1043 libata.dma=2 ATAPI (CDROM) DMA only
1044 libata.dma=4 Compact Flash DMA only
1045 Combinations also work, so libata.dma=3 enables DMA
1046 for disks and CDROMs, but not CFs.
1048 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1052 libata.force= [LIBATA] Force configurations. The format is comma
1053 separated list of "[ID:]VAL" where ID is
1054 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1055 matching port, link or device. Basically, it matches
1056 the ATA ID string printed on console by libata. If
1057 the whole ID part is omitted, the last PORT and DEVICE
1058 values are used. If ID hasn't been specified yet, the
1059 configuration applies to all ports, links and devices.
1061 If only DEVICE is omitted, the parameter applies to
1062 the port and all links and devices behind it. DEVICE
1063 number of 0 either selects the first device or the
1064 first fan-out link behind PMP device. It does not
1065 select the host link. DEVICE number of 15 selects the
1066 host link and device attached to it.
1068 The VAL specifies the configuration to force. As long
1069 as there's no ambiguity shortcut notation is allowed.
1070 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1071 The following configurations can be forced.
1073 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1074 Any ID with matching PORT is used.
1076 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1078 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1079 udma[/][16,25,33,44,66,100,133] notation is also
1082 * [no]ncq: Turn on or off NCQ.
1084 * nohrst, nosrst, norst: suppress hard, soft
1087 If there are multiple matching configurations changing
1088 the same attribute, the last one is used.
1090 load_ramdisk= [RAM] List of ramdisks to load from floppy
1091 See Documentation/ramdisk.txt.
1093 lockd.nlm_grace_period=P [NFS] Assign grace period.
1096 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1099 lockd.nlm_timeout=T [NFS] Assign timeout value.
1102 lockd.nlm_udpport=M [NFS] Assign UDP port.
1105 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1108 loglevel= All Kernel Messages with a loglevel smaller than the
1109 console loglevel will be printed to the console. It can
1110 also be changed with klogd or other programs. The
1111 loglevels are defined as follows:
1113 0 (KERN_EMERG) system is unusable
1114 1 (KERN_ALERT) action must be taken immediately
1115 2 (KERN_CRIT) critical conditions
1116 3 (KERN_ERR) error conditions
1117 4 (KERN_WARNING) warning conditions
1118 5 (KERN_NOTICE) normal but significant condition
1119 6 (KERN_INFO) informational
1120 7 (KERN_DEBUG) debug-level messages
1122 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1123 Format: { n | nk | nM }
1124 n must be a power of two. The default size
1125 is set in the kernel config file.
1127 logo.nologo [FB] Disables display of the built-in Linux logo.
1128 This may be used to provide more screen space for
1129 kernel log messages and is useful when debugging
1130 kernel boot problems.
1132 lp=0 [LP] Specify parallel ports to use, e.g,
1133 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1134 lp=reset first parallel port). 'lp=0' disables the
1135 lp=auto printer driver. 'lp=reset' (which can be
1136 specified in addition to the ports) causes
1137 attached printers to be reset. Using
1138 lp=port1,port2,... specifies the parallel ports
1139 to associate lp devices with, starting with
1140 lp0. A port specification may be 'none' to skip
1141 that lp device, or a parport name such as
1142 'parport0'. Specifying 'lp=auto' instead of a
1143 port specification list means that device IDs
1144 from each port should be examined, to see if
1145 an IEEE 1284-compliant printer is attached; if
1146 so, the driver will manage that printer.
1147 See also header of drivers/char/lp.c.
1150 Sets loops_per_jiffy to given constant, thus avoiding
1151 time-consuming boot-time autodetection (up to 250 ms per
1152 CPU). 0 enables autodetection (default). To determine
1153 the correct value for your kernel, boot with normal
1154 autodetection and see what value is printed. Note that
1155 on SMP systems the preset will be applied to all CPUs,
1156 which is likely to cause problems if your CPUs need
1157 significantly divergent settings. An incorrect value
1158 will cause delays in the kernel to be wrong, leading to
1159 unpredictable I/O errors and other breakage. Although
1160 unlikely, in the extreme case this might damage your
1164 Format: <io>,<irq>,<dma>
1166 mac5380= [HW,SCSI] Format:
1167 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1169 machvec= [IA64] Force the use of a particular machine-vector
1170 (machvec) in a generic kernel.
1171 Example: machvec=hpzx1_swiotlb
1173 max_loop= [LOOP] Maximum number of loopback devices that can
1177 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1178 should make use of. maxcpus=n : n >= 0 limits the
1179 kernel to using 'n' processors. n=0 is a special case,
1180 it is equivalent to "nosmp", which also disables
1183 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1184 equal to this physical address is ignored.
1186 max_luns= [SCSI] Maximum number of LUNs to probe.
1187 Should be between 1 and 2^32-1.
1190 [SCSI] Maximum number of LUNs received.
1191 Should be between 1 and 16384.
1195 mce [X86-32] Machine Check Exception
1197 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1199 md= [HW] RAID subsystems devices and level
1200 See Documentation/md.txt.
1203 Format: <first>,<last>
1204 Specifies range of consoles to be captured by the MDA.
1206 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1207 Amount of memory to be used when the kernel is not able
1208 to see the whole system memory or for test.
1209 [X86-32] Use together with memmap= to avoid physical
1210 address space collisions. Without memmap= PCI devices
1211 could be placed at addresses belonging to unused RAM.
1213 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1217 [KNL,SH] Allow user to override the default size for
1218 per-device physically contiguous DMA buffers.
1220 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1221 E820 memory map, as specified by the user.
1222 Such memmap=exactmap lines can be constructed based on
1223 BIOS output or other requirements. See the memmap=nn@ss
1226 memmap=nn[KMG]@ss[KMG]
1227 [KNL] Force usage of a specific region of memory
1228 Region of memory to be used, from ss to ss+nn.
1230 memmap=nn[KMG]#ss[KMG]
1231 [KNL,ACPI] Mark specific memory as ACPI data.
1232 Region of memory to be used, from ss to ss+nn.
1234 memmap=nn[KMG]$ss[KMG]
1235 [KNL,ACPI] Mark specific memory as reserved.
1236 Region of memory to be used, from ss to ss+nn.
1237 Example: Exclude memory from 0x18690000-0x1869ffff
1238 memmap=64K$0x18690000
1240 memmap=0x10000$0x18690000
1242 memory_corruption_check=0/1 [X86]
1243 Some BIOSes seem to corrupt the first 64k of
1244 memory when doing things like suspend/resume.
1245 Setting this option will scan the memory
1246 looking for corruption. Enabling this will
1247 both detect corruption and prevent the kernel
1248 from using the memory being corrupted.
1249 However, its intended as a diagnostic tool; if
1250 repeatable BIOS-originated corruption always
1251 affects the same memory, you can use memmap=
1252 to prevent the kernel from using that memory.
1254 memory_corruption_check_size=size [X86]
1255 By default it checks for corruption in the low
1256 64k, making this memory unavailable for normal
1257 use. Use this parameter to scan for
1258 corruption in more or less memory.
1260 memory_corruption_check_period=seconds [X86]
1261 By default it checks for corruption every 60
1262 seconds. Use this parameter to check at some
1263 other rate. 0 disables periodic checking.
1265 memtest= [KNL,X86] Enable memtest
1267 range: 0,4 : pattern number
1268 default : 0 <disable>
1270 meye.*= [HW] Set MotionEye Camera parameters
1271 See Documentation/video4linux/meye.txt.
1273 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1274 Multi-Function General Purpose Timers on AMD Geode
1277 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1278 the BIOS has incorrectly applied a workaround. TinyBIOS
1279 version 0.98 is known to be affected, 0.99 fixes the
1280 problem by letting the user disable the workaround.
1285 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1286 parameter allows control of the logging verbosity for
1287 the additional memory initialisation checks. A value
1288 of 0 disables mminit logging and a level of 4 will
1289 log everything. Information is printed at KERN_DEBUG
1290 so loglevel=8 may also need to be specified.
1293 [MOUSE] Maximum time between finger touching and
1294 leaving touchpad surface for touch to be considered
1295 a tap and be reported as a left button click (for
1296 touchpads working in absolute mode only).
1298 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1299 reporting absolute coordinates, such as tablets
1300 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1301 reporting absolute coordinates, such as tablets
1306 MTD_Partition= [MTD]
1307 Format: <name>,<region-number>,<size>,<offset>
1309 MTD_Region= [MTD] Format:
1310 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1313 See drivers/mtd/cmdlinepart.c.
1316 ARM/S3C2412 JIVE boot control
1318 See arch/arm/mach-s3c2412/mach-jive.c
1320 mtouchusb.raw_coordinates=
1321 [HW] Make the MicroTouch USB driver use raw coordinates
1322 ('y', default) or cooked coordinates ('n')
1324 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1327 See header of drivers/scsi/NCR_D700.c.
1331 ncr53c400= [HW,SCSI]
1333 ncr53c400a= [HW,SCSI]
1335 ncr53c406a= [HW,SCSI]
1337 ncr53c8xx= [HW,SCSI]
1339 netdev= [NET] Network devices parameters
1340 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1341 Note that mem_start is often overloaded to mean
1342 something different and driver-specific.
1343 This usage is only documented in each driver source
1347 [NETFILTER] Enable connection tracking flow accounting
1348 0 to disable accounting
1349 1 to enable accounting
1350 Default value depends on CONFIG_NF_CT_ACCT that is
1351 going to be removed in 2.6.29.
1354 See Documentation/filesystems/nfsroot.txt.
1356 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1357 See Documentation/filesystems/nfsroot.txt.
1359 nfs.callback_tcpport=
1360 [NFS] set the TCP port on which the NFSv4 callback
1361 channel should listen.
1363 nfs.idmap_cache_timeout=
1364 [NFS] set the maximum lifetime for idmapper cache
1368 [NFS] enable 64-bit inode numbers.
1369 If zero, the NFS client will fake up a 32-bit inode
1370 number for the readdir() and stat() syscalls instead
1371 of returning the full 64-bit number.
1372 The default is to return 64-bit inode numbers.
1374 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1375 when a NMI is triggered.
1376 Format: [state][,regs][,debounce][,die]
1378 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1380 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1381 emulation library even if a 387 maths coprocessor
1384 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1385 caches in the slab allocator. Saves per-node memory,
1386 but will impact performance.
1390 noapic [SMP,APIC] Tells the kernel to not make use of any
1391 IOAPICs that may be present in the system.
1393 nobats [PPC] Do not use BATs for mapping kernel lowmem
1394 on "Classic" PPC cores.
1398 nodelayacct [KNL] Disable per-task delay accounting
1400 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1402 nodsp [SH] Disable hardware DSP at boot time.
1404 noefi [X86-32,X86-64] Disable EFI runtime services support.
1408 noexec [X86-32,X86-64]
1409 On X86-32 available only on PAE configured kernels.
1410 noexec=on: enable non-executable mappings (default)
1411 noexec=off: disable non-executable mappings
1414 This affects only 32-bit executables.
1415 noexec32=on: enable non-executable mappings (default)
1416 read doesn't imply executable mappings
1417 noexec32=off: disable non-executable mappings
1418 read implies executable mappings
1420 nofpu [SH] Disable hardware FPU at boot time.
1422 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1423 register save and restore. The kernel will only save
1424 legacy floating-point registers on task switch.
1426 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1430 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1431 instruction doesn't work correctly and not to
1434 nohalt [IA-64] Tells the kernel not to use the power saving
1435 function PAL_HALT_LIGHT when idle. This increases
1436 power-consumption. On the positive side, it reduces
1437 interrupt wake-up latency, which may improve performance
1438 in certain environments such as networked servers or
1441 nohz= [KNL] Boottime enable/disable dynamic ticks
1442 Valid arguments: on, off
1445 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1447 noirqdebug [X86-32] Disables the code which attempts to detect and
1448 disable unhandled interrupt sources.
1450 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1451 broken timer IRQ sources.
1453 noisapnp [ISAPNP] Disables ISA PnP code.
1455 noinitrd [RAM] Tells the kernel not to load any configured
1460 nojitter [IA64] Disables jitter checking for ITC timers.
1462 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1464 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1466 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1468 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1469 default x2apic cluster mode on platforms
1472 noltlbs [PPC] Do not use large page/tlb entries for kernel
1473 lowmem mapping on PPC40x.
1475 nomca [IA-64] Disable machine check abort handling
1477 nomce [X86-32] Machine Check Exception
1479 nomfgpt [X86-32] Disable Multi-Function General Purpose
1480 Timer usage (for AMD Geode machines).
1482 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1484 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1485 with UP alternatives
1487 noresidual [PPC] Don't use residual data on PReP machines.
1489 noresume [SWSUSP] Disables resume and restores original swap
1492 no-scroll [VGA] Disables scrollback.
1493 This is required for the Braillex ib80-piezo Braille
1494 reader made by F.H. Papenmeier (Germany).
1498 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1500 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1501 and disable the IO APIC. legacy for "maxcpus=0".
1503 nosoftlockup [KNL] Disable the soft-lockup detector.
1505 nosync [HW,M68K] Disables sync negotiation for all devices.
1507 notsc [BUGS=X86-32] Disable Time Stamp Counter
1509 nousb [USB] Disable the USB subsystem
1513 nptcg= [IA64] Override max number of concurrent global TLB
1514 purges which is reported from either PAL_VM_SUMMARY or
1517 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1518 one of ['zone', 'node', 'default'] can be specified
1519 This can be set from sysctl after boot.
1520 See Documentation/sysctl/vm.txt for details.
1522 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1524 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1525 Rather than timing out after 20 ms if an EC
1526 command is not properly ACKed, override the length
1527 of the timeout. We have interrupts disabled while
1528 waiting for the ACK, so if this is set too high
1529 interrupts *may* be lost!
1534 oprofile.timer= [HW]
1535 Use timer interrupt instead of performance counters
1537 osst= [HW,SCSI] SCSI Tape Driver
1538 Format: <buffer_size>,<write_threshold>
1539 See also Documentation/scsi/st.txt.
1541 panic= [KNL] Kernel behaviour on panic
1544 parkbd.port= [HW] Parallel port number the keyboard adapter is
1545 connected to, default is 0.
1547 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1548 0 for XT, 1 for AT (default is AT).
1551 parport= [HW,PPT] Specify parallel ports. 0 disables.
1552 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1553 Use 'auto' to force the driver to use any
1554 IRQ/DMA settings detected (the default is to
1555 ignore detected IRQ/DMA settings because of
1556 possible conflicts). You can specify the base
1557 address, IRQ, and DMA settings; IRQ and DMA
1558 should be numbers, or 'auto' (for using detected
1559 settings on that particular port), or 'nofifo'
1560 (to avoid using a FIFO even if it is detected).
1561 Parallel ports are assigned in the order they
1562 are specified on the command line, starting
1565 parport_init_mode= [HW,PPT]
1566 Configure VIA parallel port to operate in
1567 a specific mode. This is necessary on Pegasos
1568 computer where firmware has no options for setting
1569 up parallel port mode and sets it to spp.
1570 Currently this function knows 686a and 8231 chips.
1571 Format: [spp|ps2|epp|ecp|ecpepp]
1573 pas2= [HW,OSS] Format:
1574 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1577 See header of drivers/scsi/pas16.c.
1580 Halt all CPUs after the first oops has been printed for
1581 the specified number of seconds. This is to be used if
1582 your oopses keep scrolling off the screen.
1587 See header of drivers/block/paride/pcd.c.
1588 See also Documentation/paride.txt.
1590 pci=option[,option...] [PCI] various PCI subsystem options:
1591 off [X86-32] don't probe for the PCI bus
1592 bios [X86-32] force use of PCI BIOS, don't access
1593 the hardware directly. Use this if your machine
1594 has a non-standard PCI host bridge.
1595 nobios [X86-32] disallow use of PCI BIOS, only direct
1596 hardware access methods are allowed. Use this
1597 if you experience crashes upon bootup and you
1598 suspect they are caused by the BIOS.
1599 conf1 [X86-32] Force use of PCI Configuration
1601 conf2 [X86-32] Force use of PCI Configuration
1603 noaer [PCIE] If the PCIEAER kernel config parameter is
1604 enabled, this kernel boot option can be used to
1605 disable the use of PCIE advanced error reporting.
1606 nodomains [PCI] Disable support for multiple PCI
1607 root domains (aka PCI segments, in ACPI-speak).
1608 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1610 nomsi [MSI] If the PCI_MSI kernel config parameter is
1611 enabled, this kernel boot option can be used to
1612 disable the use of MSI interrupts system-wide.
1613 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1614 routing table. These calls are known to be buggy
1615 on several machines and they hang the machine
1616 when used, but on other computers it's the only
1617 way to get the interrupt routing table. Try
1618 this option if the kernel is unable to allocate
1619 IRQs or discover secondary PCI buses on your
1621 rom [X86-32] Assign address space to expansion ROMs.
1622 Use with caution as certain devices share
1623 address decoders between ROMs and other
1625 norom [X86-32,X86_64] Do not assign address space to
1626 expansion ROMs that do not already have
1627 BIOS assigned address ranges.
1628 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1629 assigned automatically to PCI devices. You can
1630 make the kernel exclude IRQs of your ISA cards
1632 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1633 of the PIRQ table (normally generated
1634 by the BIOS) if it is outside the
1635 F0000h-100000h range.
1636 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1637 useful if the kernel is unable to find your
1638 secondary buses and you want to tell it
1639 explicitly which ones they are.
1640 assign-busses [X86-32] Always assign all PCI bus
1641 numbers ourselves, overriding
1642 whatever the firmware may have done.
1643 usepirqmask [X86-32] Honor the possible IRQ mask stored
1644 in the BIOS $PIR table. This is needed on
1645 some systems with broken BIOSes, notably
1646 some HP Pavilion N5400 and Omnibook XE3
1647 notebooks. This will have no effect if ACPI
1648 IRQ routing is enabled.
1649 noacpi [X86-32] Do not use ACPI for IRQ routing
1650 or for PCI scanning.
1651 use_crs [X86-32] Use _CRS for PCI resource
1653 routeirq Do IRQ routing for all PCI devices.
1654 This is normally done in pci_enable_device(),
1655 so this option is a temporary workaround
1656 for broken drivers that don't call it.
1657 skip_isa_align [X86] do not align io start addr, so can
1658 handle more pci cards
1659 firmware [ARM] Do not re-enumerate the bus but instead
1660 just use the configuration from the
1661 bootloader. This is currently used on
1662 IXP2000 systems where the bus has to be
1663 configured a certain way for adjunct CPUs.
1664 noearly [X86] Don't do any early type 1 scanning.
1665 This might help on some broken boards which
1666 machine check when some devices' config space
1667 is read. But various workarounds are disabled
1668 and some IOMMU drivers will not work.
1669 bfsort Sort PCI devices into breadth-first order.
1670 This sorting is done to get a device
1671 order compatible with older (<= 2.4) kernels.
1672 nobfsort Don't sort PCI devices into breadth-first order.
1673 cbiosize=nn[KMG] The fixed amount of bus space which is
1674 reserved for the CardBus bridge's IO window.
1675 The default value is 256 bytes.
1676 cbmemsize=nn[KMG] The fixed amount of bus space which is
1677 reserved for the CardBus bridge's memory
1678 window. The default value is 64 megabytes.
1680 pcmv= [HW,PCMCIA] BadgePAD 4
1683 See Documentation/paride.txt.
1685 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1688 See arch/parisc/kernel/pdc_chassis.c
1691 See Documentation/paride.txt.
1694 See Documentation/paride.txt.
1696 pirq= [SMP,APIC] Manual mp-table setup
1697 See Documentation/i386/IO-APIC.txt.
1699 plip= [PPT,NET] Parallel port network link
1700 Format: { parport<nr> | timid | 0 }
1701 See also Documentation/parport.txt.
1703 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1704 Override pmtimer IOPort with a hex value.
1711 { on | off | curr | res | no-curr | no-res }
1714 [ISAPNP] Exclude IRQs for the autoconfiguration
1717 [ISAPNP] Exclude DMAs for the autoconfiguration
1719 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1720 Ranges are in pairs (I/O port base and size).
1723 [ISAPNP] Exclude memory regions for the
1725 Ranges are in pairs (memory base and size).
1728 Enables pr_debug()/dev_dbg() calls if
1729 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1730 be switched on/off via <debugfs>/dynamic_printk/modules
1732 print-fatal-signals=
1733 [KNL] debug: print fatal signals
1734 print-fatal-signals=1: print segfault info to
1738 printk.time= Show timing data prefixed to each printk message line
1739 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1741 profile= [KNL] Enable kernel profiling via /proc/profile
1742 Format: [schedule,]<number>
1743 Param: "schedule" - profile schedule points.
1744 Param: <number> - step/bucket size as a power of 2 for
1745 statistical time based profiling.
1746 Param: "sleep" - profile D-state sleeping (millisecs).
1747 Requires CONFIG_SCHEDSTATS
1748 Param: "kvm" - profile VM exits.
1750 processor.max_cstate= [HW,ACPI]
1751 Limit processor to maximum C-state
1752 max_cstate=9 overrides any DMI blacklist limit.
1754 processor.nocst [HW,ACPI]
1755 Ignore the _CST method to determine C-states,
1756 instead using the legacy FADT method
1758 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1760 See Documentation/ramdisk.txt.
1762 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1763 probe for; one of (bare|imps|exps|lifebook|any).
1764 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1766 psmouse.resetafter= [HW,MOUSE]
1767 Try to reset the device after so many bad packets
1770 [HW,MOUSE] Set desired mouse resolution, in dpi.
1771 psmouse.smartscroll=
1772 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1773 0 = disabled, 1 = enabled (default).
1775 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1777 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1780 See Documentation/paride.txt.
1783 [KNL] Number of legacy pty's. Overwrites compiled-in
1786 quiet [KNL] Disable most log messages
1791 See Documentation/md.txt.
1793 ramdisk_blocksize= [RAM]
1794 See Documentation/ramdisk.txt.
1796 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1797 See Documentation/ramdisk.txt.
1799 rcupdate.blimit= [KNL,BOOT]
1800 Set maximum number of finished RCU callbacks to process
1803 rcupdate.qhimark= [KNL,BOOT]
1804 Set threshold of queued
1805 RCU callbacks over which batch limiting is disabled.
1807 rcupdate.qlowmark= [KNL,BOOT]
1808 Set threshold of queued RCU callbacks below which
1809 batch limiting is re-enabled.
1813 Run specified binary instead of /init from the ramdisk,
1814 used for early userspace startup. See initrd.
1816 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1817 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1818 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1821 [KNL, SMP] Set scheduler's default relax_domain_level.
1822 See Documentation/cpusets.txt.
1824 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1826 reservetop= [X86-32]
1828 Reserves a hole at the top of the kernel virtual
1831 reset_devices [KNL] Force drivers to reset the underlying device
1832 during initialization.
1835 Specify the partition device for software suspend
1837 resume_offset= [SWSUSP]
1838 Specify the offset from the beginning of the partition
1839 given by "resume=" at which the swap header is located,
1840 in <PAGE_SIZE> units (needed only for swap files).
1841 See Documentation/power/swsusp-and-swap-files.txt
1843 retain_initrd [RAM] Keep initrd memory after extraction
1845 rhash_entries= [KNL,NET]
1846 Set number of hash buckets for route cache
1848 riscom8= [HW,SERIAL]
1849 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1851 ro [KNL] Mount root device read-only on boot
1853 root= [KNL] Root filesystem
1855 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1856 mount the root filesystem
1858 rootflags= [KNL] Set root filesystem mount option string
1860 rootfstype= [KNL] Set root filesystem type
1862 rootwait [KNL] Wait (indefinitely) for root device to show up.
1863 Useful for devices that are detected asynchronously
1864 (e.g. USB and MMC devices).
1866 root_plug.vendor_id=
1867 [ROOTPLUG] Override the default vendor ID
1869 root_plug.product_id=
1870 [ROOTPLUG] Override the default product ID
1873 [ROOTPLUG] Enable debugging output
1875 rw [KNL] Mount root device read-write on boot
1877 S [KNL] Run init in single mode
1880 See drivers/net/irda/sa1100_ir.c.
1882 sbni= [NET] Granch SBNI12 leased line adapter
1884 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1885 Format: <io>[,<timeout>[,<isapnp>]]
1887 scsi_debug_*= [SCSI]
1888 See drivers/scsi/scsi_debug.c.
1890 scsi_default_dev_flags=
1891 [SCSI] SCSI default device flags
1894 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1895 Format: <vendor>:<model>:<flags>
1896 (flags are integer value)
1898 scsi_logging_level= [SCSI] a bit mask of logging levels
1899 See drivers/scsi/scsi_logging.h for bits. Also
1900 settable via sysctl at dev.scsi.logging_level
1901 (/proc/sys/dev/scsi/logging_level).
1902 There is also a nice 'scsi_logging_level' script in the
1903 S390-tools package, available for download at
1904 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1906 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1907 discovered. async scans them in kernel threads,
1908 allowing boot to proceed. none ignores them, expecting
1909 user space to do the scan.
1911 selinux [SELINUX] Disable or enable SELinux at boot time.
1912 Format: { "0" | "1" }
1913 See security/selinux/Kconfig help text.
1916 Default value is set via kernel config option.
1917 If enabled at boot time, /selinux/disable can be used
1918 later to disable prior to initial policy load.
1920 selinux_compat_net =
1921 [SELINUX] Set initial selinux_compat_net flag value.
1922 Format: { "0" | "1" }
1923 0 -- use new secmark-based packet controls
1924 1 -- use legacy packet controls
1925 Default value is 0 (preferred).
1926 Value can be changed at runtime via
1927 /selinux/compat_net.
1929 serialnumber [BUGS=X86-32]
1932 Maximal number of shapers.
1934 show_msr= [x86] show boot-time MSR settings
1935 Format: { <integer> }
1936 Show boot-time (BIOS-initialized) MSR settings.
1937 The parameter means the number of CPUs to show,
1938 for example 1 means boot CPU only.
1941 See header of drivers/scsi/sim710.c.
1948 slub_debug[=options[,slabs]] [MM, SLUB]
1949 Enabling slub_debug allows one to determine the
1950 culprit if slab objects become corrupted. Enabling
1951 slub_debug can create guard zones around objects and
1952 may poison objects when not in use. Also tracks the
1953 last alloc / free. For more information see
1954 Documentation/vm/slub.txt.
1956 slub_max_order= [MM, SLUB]
1957 Determines the maximum allowed order for slabs.
1958 A high setting may cause OOMs due to memory
1959 fragmentation. For more information see
1960 Documentation/vm/slub.txt.
1962 slub_min_objects= [MM, SLUB]
1963 The minimum number of objects per slab. SLUB will
1964 increase the slab order up to slub_max_order to
1965 generate a sufficiently large slab able to contain
1966 the number of objects indicated. The higher the number
1967 of objects the smaller the overhead of tracking slabs
1968 and the less frequently locks need to be acquired.
1969 For more information see Documentation/vm/slub.txt.
1971 slub_min_order= [MM, SLUB]
1972 Determines the mininum page order for slabs. Must be
1973 lower than slub_max_order.
1974 For more information see Documentation/vm/slub.txt.
1976 slub_nomerge [MM, SLUB]
1977 Disable merging of slabs with similar size. May be
1978 necessary if there is some reason to distinguish
1979 allocs to different slabs. Debug options disable
1980 merging on their own.
1981 For more information see Documentation/vm/slub.txt.
1984 Format: <io1>[,<io2>[,...,<io8>]]
1986 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1987 attempt to substitute SMP alternatives once at boot.
1989 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1990 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1991 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1992 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1993 smsc-ircc2.ircc_irq= [HW] IRQ line
1994 smsc-ircc2.ircc_dma= [HW] DMA channel
1995 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1996 0: Toshiba Satellite 1800 (GP data pin select)
1997 1: Fast pin select (default)
2000 snd-ad1816a= [HW,ALSA]
2002 snd-ad1848= [HW,ALSA]
2004 snd-ali5451= [HW,ALSA]
2006 snd-als100= [HW,ALSA]
2008 snd-als4000= [HW,ALSA]
2010 snd-azt2320= [HW,ALSA]
2012 snd-cmi8330= [HW,ALSA]
2014 snd-cmipci= [HW,ALSA]
2016 snd-cs4231= [HW,ALSA]
2018 snd-cs4232= [HW,ALSA]
2020 snd-cs4236= [HW,ALSA]
2022 snd-cs4281= [HW,ALSA]
2024 snd-cs46xx= [HW,ALSA]
2026 snd-dt019x= [HW,ALSA]
2028 snd-dummy= [HW,ALSA]
2030 snd-emu10k1= [HW,ALSA]
2032 snd-ens1370= [HW,ALSA]
2034 snd-ens1371= [HW,ALSA]
2036 snd-es968= [HW,ALSA]
2038 snd-es1688= [HW,ALSA]
2040 snd-es18xx= [HW,ALSA]
2042 snd-es1938= [HW,ALSA]
2044 snd-es1968= [HW,ALSA]
2046 snd-fm801= [HW,ALSA]
2048 snd-gusclassic= [HW,ALSA]
2050 snd-gusextreme= [HW,ALSA]
2052 snd-gusmax= [HW,ALSA]
2056 snd-ice1712= [HW,ALSA]
2058 snd-intel8x0= [HW,ALSA]
2060 snd-interwave= [HW,ALSA]
2065 snd-korg1212= [HW,ALSA]
2067 snd-maestro3= [HW,ALSA]
2069 snd-mpu401= [HW,ALSA]
2071 snd-mtpav= [HW,ALSA]
2073 snd-nm256= [HW,ALSA]
2075 snd-opl3sa2= [HW,ALSA]
2083 snd-opti93x= [HW,ALSA]
2087 snd-rme32= [HW,ALSA]
2089 snd-rme96= [HW,ALSA]
2091 snd-rme9652= [HW,ALSA]
2097 snd-sbawe= [HW,ALSA]
2099 snd-serial= [HW,ALSA]
2101 snd-sgalaxy= [HW,ALSA]
2103 snd-sonicvibes= [HW,ALSA]
2108 snd-sun-cs4231= [HW,ALSA]
2110 snd-trident= [HW,ALSA]
2112 snd-usb-audio= [HW,ALSA,USB]
2114 snd-via82xx= [HW,ALSA]
2116 snd-virmidi= [HW,ALSA]
2118 snd-wavefront= [HW,ALSA]
2120 snd-ymfpci= [HW,ALSA]
2123 [KNL] Should the soft-lockup detector generate panics.
2125 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2126 See Documentation/sonypi.txt
2128 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2129 See Documentation/specialix.txt.
2131 spia_io_base= [HW,MTD]
2137 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2139 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2140 See Documentation/scsi/st.txt.
2144 Set the STI (builtin display/keyboard on the HP-PARISC
2145 machines) console (graphic card) which should be used
2146 as the initial boot-console.
2147 See also comment in drivers/video/console/sticore.c.
2150 See comment in drivers/video/console/sticore.c.
2153 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2157 Control how the NFS server code allocates CPUs to
2158 service thread pools. Depending on how many NICs
2159 you have and where their interrupts are bound, this
2160 option will affect which CPUs will do NFS serving.
2161 Note: this parameter cannot be changed while the
2162 NFS server is running.
2164 auto the server chooses an appropriate mode
2165 automatically using heuristics
2166 global a single global pool contains all CPUs
2167 percpu one pool for each CPU
2168 pernode one pool for each NUMA node (equivalent
2169 to global on non-NUMA machines)
2171 swiotlb= [IA-64] Number of I/O TLB slabs
2175 sym53c416= [HW,SCSI]
2176 See header of drivers/scsi/sym53c416.c.
2178 sysrq_always_enabled
2180 Ignore sysrq setting - this boot parameter will
2181 neutralize any effect of /proc/sys/kernel/sysrq.
2182 Useful for debugging.
2185 See header of drivers/scsi/t128.c.
2189 test_suspend= [SUSPEND]
2190 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2191 standby suspend) as the system sleep state to briefly
2192 enter during system startup. The system is woken from
2193 this state using a wakeup-capable RTC alarm.
2195 thash_entries= [KNL,NET]
2196 Set number of hash buckets for TCP connection
2198 thermal.act= [HW,ACPI]
2199 -1: disable all active trip points in all thermal zones
2200 <degrees C>: override all lowest active trip points
2202 thermal.crt= [HW,ACPI]
2203 -1: disable all critical trip points in all thermal zones
2204 <degrees C>: lower all critical trip points
2206 thermal.nocrt= [HW,ACPI]
2207 Set to disable actions on ACPI thermal zone
2208 critical and hot trip points.
2210 thermal.off= [HW,ACPI]
2211 1: disable ACPI thermal control
2213 thermal.psv= [HW,ACPI]
2214 -1: disable all passive trip points
2215 <degrees C>: override all passive trip points to this value
2217 thermal.tzp= [HW,ACPI]
2218 Specify global default ACPI thermal zone polling rate
2219 <deci-seconds>: poll all this frequency
2220 0: no polling (default)
2223 See comment before function dc390_setup() in
2224 drivers/scsi/tmscsim.c.
2228 trix= [HW,OSS] MediaTrix AudioTrix Pro
2230 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2232 turbografx.map[2|3]= [HW,JOY]
2233 TurboGraFX parallel port interface
2235 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2236 See also Documentation/input/joystick-parport.txt
2238 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2239 See header of drivers/scsi/u14-34f.c.
2248 [USB] Ignore overcurrent events (default N).
2249 Some badly-designed motherboards generate lots of
2250 bogus events, for ports that aren't wired to
2251 anything. Set this parameter to avoid log spamming.
2252 Note that genuine overcurrent events won't be
2257 Set unknown_nmi_panic=1 early on boot.
2259 usbcore.autosuspend=
2260 [USB] The autosuspend time delay (in seconds) used
2261 for newly-detected USB devices (default 2). This
2262 is the time required before an idle device will be
2263 autosuspended. Devices for which the delay is set
2264 to a negative value won't be autosuspended at all.
2266 usbcore.usbfs_snoop=
2267 [USB] Set to log all usbfs traffic (default 0 = off).
2269 usbcore.blinkenlights=
2270 [USB] Set to cycle leds on hubs (default 0 = off).
2272 usbcore.old_scheme_first=
2273 [USB] Start with the old device initialization
2274 scheme (default 0 = off).
2276 usbcore.use_both_schemes=
2277 [USB] Try the other device initialization scheme
2278 if the first one fails (default 1 = enabled).
2280 usbcore.initial_descriptor_timeout=
2281 [USB] Specifies timeout for the initial 64-byte
2282 USB_REQ_GET_DESCRIPTOR request in milliseconds
2283 (default 5000 = 5.0 seconds).
2286 [USBHID] The interval which mice are to be polled at.
2288 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2289 kernel's map of available physical RAM.
2291 vdso= [X86-32,SH,x86-64]
2292 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2293 vdso=1: enable VDSO (default)
2294 vdso=0: disable VDSO mapping
2296 vdso32= [X86-32,X86-64]
2297 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2298 vdso32=1: enable 32-bit VDSO (default)
2299 vdso32=0: disable 32-bit VDSO mapping
2302 vector=percpu: enable percpu vector domain
2304 video= [FB] Frame buffer configuration
2305 See Documentation/fb/modedb.txt.
2307 vga= [BOOT,X86-32] Select a particular video mode
2308 See Documentation/i386/boot.txt and
2309 Documentation/svga.txt.
2310 Use vga=ask for menu.
2311 This is actually a boot loader parameter; the value is
2312 passed to the kernel using a special protocol.
2314 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2315 size of <nn>. This can be used to increase the
2316 minimum size (128MB on x86). It can also be used to
2317 decrease the size and leave more room for directly
2320 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2323 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2326 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2329 waveartist= [HW,OSS]
2330 Format: <io>,<irq>,<dma>,<dma2>
2333 See header of drivers/scsi/wd33c93.c.
2336 See header of drivers/scsi/wd7000.c.
2339 See Documentation/watchdog/wdt.txt.
2341 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2342 xd_geo= See header of drivers/block/xd.c.
2344 xirc2ps_cs= [NET,PCMCIA]
2346 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2348 norandmaps Don't use address space randomization
2349 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2351 ______________________________________________________________________
2355 Add documentation for ALSA options.
2356 Add more DRM drivers.