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/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/x86/i386/boot.txt>.
117 There are also arch-specific kernel-parameters not documented here.
118 See for example <Documentation/x86/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 which corresponds to the level in an ACPI_DEBUG_PRINT
222 statement. After system has booted up, this mask
223 can be set via /sys/module/acpi/parameters/debug_level.
225 CONFIG_ACPI_DEBUG must be enabled for this to produce
226 any output. The number can be in decimal or prefixed
227 with 0x in hex. Some of these options produce so much
228 output that the system is unusable.
230 The following global components are defined by the
243 0x800 operation region
249 0x20000 user requests
251 The number can be in decimal or prefixed with 0x in hex.
252 Warning: Many of these options can produce a lot of
253 output and make your system unusable. Be very careful.
255 acpi.power_nocheck= [HW,ACPI]
256 Format: 1/0 enable/disable the check of power state.
257 On some bogus BIOS the _PSC object/_STA object of
258 power resource can't return the correct device power
259 state. In such case it is unneccessary to check its
260 power state again in power transition.
261 1 : disable the power state check
263 acpi_pm_good [X86-32,X86-64]
264 Override the pmtimer bug detection: force the kernel
265 to assume that this machine's pmtimer latches its value
266 and always returns good values.
269 { off | try_unsupported }
270 off: disable AGP support
271 try_unsupported: try to drive unsupported chipsets
272 (may crash computer or cause data corruption)
274 enable_timer_pin_1 [i386,x86-64]
275 Enable PIN 1 of APIC timer
276 Can be useful to work around chipset bugs
277 (in particular on some ATI chipsets).
278 The kernel tries to set a reasonable default.
280 disable_timer_pin_1 [i386,x86-64]
281 Disable PIN 1 of APIC timer
282 Can be useful to work around chipset bugs.
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
288 See header of drivers/scsi/advansys.c.
290 advwdt= [HW,WDT] Advantech WDT
291 Format: <iostart>,<iostop>
293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
298 See Documentation/scsi/aha152x.txt.
301 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
304 See Documentation/scsi/aic7xxx.txt.
307 See Documentation/scsi/aic79xx.txt.
309 amd_iommu= [HW,X86-84]
310 Pass parameters to the AMD IOMMU driver in the system.
312 isolate - enable device isolation (each device, as far
313 as possible, will get its own protection
315 fullflush - enable flushing of IO/TLB entries when
316 they are unmapped. Otherwise they are
317 flushed before they will be reused, which
320 amd_iommu_size= [HW,X86-64]
321 Define the size of the aperture for the AMD IOMMU
322 driver. Possible values are:
323 '32M', '64M' (default), '128M', '256M', '512M', '1G'
325 amijoy.map= [HW,JOY] Amiga joystick support
326 Map of devices attached to JOY0DAT and JOY1DAT
328 See also Documentation/kernel/input/joystick.txt
330 analog.map= [HW,JOY] Analog joystick and gamepad support
331 Specifies type or capabilities of an analog joystick
332 connected to one of 16 gameports
333 Format: <type1>,<type2>,..<type16>
336 Power management functions (SPARCstation-4/5 + deriv.)
338 Disable APC CPU standby support. SPARCstation-Fox does
339 not play well with APC CPU idle - disable it if you have
340 APC and your system crashes randomly.
342 apic= [APIC,i386] Advanced Programmable Interrupt Controller
343 Change the output verbosity whilst booting
344 Format: { quiet (default) | verbose | debug }
345 Change the amount of debugging information output
346 when initialising the APIC and IO-APIC components.
348 apm= [APM] Advanced Power Management
349 See header of arch/x86/kernel/apm_32.c.
351 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
352 Format: <io>,<irq>,<nodeID>
356 atarimouse= [HW,MOUSE] Atari Mouse
358 atascsi= [HW,SCSI] Atari SCSI
360 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
361 EzKey and similar keyboards
363 atkbd.reset= [HW] Reset keyboard during initialization
365 atkbd.set= [HW] Select keyboard code set
366 Format: <int> (2 = AT (default), 3 = PS/2)
368 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
371 atkbd.softraw= [HW] Choose between synthetic and real raw mode
372 Format: <bool> (0 = real, 1 = synthetic (default))
374 atkbd.softrepeat= [HW]
375 Use software keyboard repeat
379 baycom_epp= [HW,AX25]
382 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
384 See header of drivers/net/hamradio/baycom_par.c.
386 baycom_ser_fdx= [HW,AX25]
387 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
388 Format: <io>,<irq>,<mode>[,<baud>]
389 See header of drivers/net/hamradio/baycom_ser_fdx.c.
391 baycom_ser_hdx= [HW,AX25]
392 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
393 Format: <io>,<irq>,<mode>
394 See header of drivers/net/hamradio/baycom_ser_hdx.c.
396 boot_delay= Milliseconds to delay each printk during boot.
397 Values larger than 10 seconds (10000) are changed to
401 bootmem_debug [KNL] Enable bootmem allocator debug messages.
403 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
404 bttv.radio= Most important insmod options are available as
406 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
407 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
410 See drivers/scsi/BusLogic.c, comment before function
411 BusLogic_ParseDriverOptions().
413 c101= [NET] Moxa C101 synchronous serial card
415 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
416 Sometimes CPU hardware bugs make them report the cache
417 size incorrectly. The kernel will attempt work arounds
418 to fix known problems, but for some CPUs it is not
419 possible to determine what the correct size should be.
420 This option provides an override for these situations.
422 security= [SECURITY] Choose a security module to enable at boot.
423 If this boot parameter is not specified, only the first
424 security module asking for security registration will be
425 loaded. An invalid security module name will be treated
426 as if no module has been chosen.
429 [SECURITY] Disable capabilities. This would normally
430 be used only if an alternative security model is to be
431 configured. Potentially dangerous and should only be
432 used if you are entirely sure of the consequences.
434 ccw_timeout_log [S390]
435 See Documentation/s390/CommonIO for details.
437 cgroup_disable= [KNL] Disable a particular controller
438 Format: {name of the controller(s) to disable}
439 {Currently supported controllers - "memory"}
441 checkreqprot [SELINUX] Set initial checkreqprot flag value.
442 Format: { "0" | "1" }
443 See security/selinux/Kconfig help text.
444 0 -- check protection applied by kernel (includes
445 any implied execute protection).
446 1 -- check protection requested by application.
447 Default value is set via a kernel config option.
448 Value can be changed at runtime via
449 /selinux/checkreqprot.
452 See Documentation/s390/CommonIO for details.
454 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
456 Forces specified clocksource (if available) to be used
457 when calculating gettimeofday(). If specified
458 clocksource is not available, it defaults to PIT.
459 Format: { pit | tsc | cyclone | pmtmr }
461 clocksource= [GENERIC_TIME] Override the default clocksource
463 Override the default clocksource and use the clocksource
464 with the name specified.
465 Some clocksource names to choose from, depending on
467 [all] jiffies (this is the base, fallback clocksource)
469 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
470 pxa_timer,timer3,32k_counter,timer0_1
472 [X86-32] pit,hpet,tsc,vmi-timer;
473 scx200_hrt on Geode; cyclone on IBM x440
481 clearcpuid=BITNUM [X86]
482 Disable CPUID feature X for the kernel. See
483 include/asm-x86/cpufeature.h for the valid bit numbers.
484 Note the Linux specific bits are not necessarily
485 stable over kernel options, but the vendor specific
487 Also note that user programs calling CPUID directly
488 or using the feature without checking anything
489 will still see it. This just prevents it from
490 being used by the kernel or shown in /proc/cpuinfo.
491 Also note the kernel might malfunction if you disable
494 code_bytes [IA32/X86_64] How many bytes of object code to print
499 hpet= [X86-32,HPET] option to control HPET usage
500 Format: { enable (default) | disable | force }
501 disable: disable HPET and use PIT instead
502 force: allow force enabled of undocumented chips (ICH4,
505 com20020= [HW,NET] ARCnet - COM20020 chipset
507 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
509 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
513 ARCnet - COM90xx chipset (memory-mapped buffers)
514 Format: <io>[,<irq>[,<memstart>]]
516 condev= [HW,S390] console device
519 console= [KNL] Output console device and options.
521 tty<n> Use the virtual console device <n>.
525 Use the specified serial port. The options are of
526 the form "bbbbpnf", where "bbbb" is the baud rate,
527 "p" is parity ("n", "o", or "e"), "n" is number of
528 bits, and "f" is flow control ("r" for RTS or
529 omit it). Default is "9600n8".
531 See Documentation/serial-console.txt for more
533 Documentation/networking/netconsole.txt for an
536 uart[8250],io,<addr>[,options]
537 uart[8250],mmio,<addr>[,options]
538 Start an early, polled-mode console on the 8250/16550
539 UART at the specified I/O port or MMIO address,
540 switching to the matching ttyS device later. The
541 options are the same as for ttyS, above.
543 If the device connected to the port is not a TTY but a braille
544 device, prepend "brl," before the device type, for instance
546 For now, only VisioBraille is supported.
548 earlycon= [KNL] Output early console device and options.
549 uart[8250],io,<addr>[,options]
550 uart[8250],mmio,<addr>[,options]
551 Start an early, polled-mode console on the 8250/16550
552 UART at the specified I/O port or MMIO address.
553 The options are the same as for ttyS, above.
556 [HW] Never suspend the console
557 Disable suspending of consoles during suspend and
558 hibernate operations. Once disabled, debugging
559 messages can reach various consoles while the rest
560 of the system is being put to sleep (ie, while
561 debugging driver suspend/resume hooks). This may
562 not work reliably with all consoles, but is known
563 to work with serial and VGA consoles.
565 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
567 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
569 crashkernel=nn[KMG]@ss[KMG]
570 [KNL] Reserve a chunk of physical memory to
571 hold a kernel to switch to with kexec on panic.
573 crashkernel=range1:size1[,range2:size2,...][@offset]
574 [KNL] Same as above, but depends on the memory
575 in the running system. The syntax of range is
576 start-[end] where start and end are both
577 a memory unit (amount[KMG]). See also
578 Documentation/kdump/kdump.txt for a example.
581 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
586 cs89x0_media= [HW,NET]
587 Format: { rj45 | aui | bnc }
590 See header of drivers/s390/block/dasd_devmap.c.
592 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
593 (one device per port)
594 Format: <port#>,<type>
595 See also Documentation/input/joystick-parport.txt
597 debug [KNL] Enable kernel debugging (events log level).
600 [KNL] verbose self-tests
602 Print debugging info while doing the locking API
604 We default to 0 (no extra messages), setting it to
605 1 will print _a lot_ more information - normally
606 only useful to kernel developers.
608 debug_objects [KNL] Enable object debugging
610 debugpat [X86] Enable PAT debugging
612 decnet.addr= [HW,NET]
613 Format: <area>[,<node>]
614 See also Documentation/networking/decnet.txt.
617 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
618 Change the default blue palette of the console.
619 This is a 16-member array composed of values
623 Format: <green0>,<green1>,<green2>,...,<green15>
624 Change the default green palette of the console.
625 This is a 16-member array composed of values
629 Format: <red0>,<red1>,<red2>,...,<red15>
630 Change the default red palette of the console.
631 This is a 16-member array composed of values
637 Set system-wide default UTF-8 mode for all tty's.
638 Default is 1, i.e. UTF-8 mode is enabled for all
639 newly opened terminals.
642 Set number of hash buckets for dentry cache.
645 IO parameters + enable/disable command.
647 digiepca= [HW,SERIAL]
648 See drivers/char/README.epca and
649 Documentation/digiepca.txt.
651 disable_mtrr_cleanup [X86]
652 enable_mtrr_cleanup [X86]
653 The kernel tries to adjust MTRR layout from continuous
654 to discrete, to make X server driver able to add WB
655 entry later. This parameter enables/disables that.
657 mtrr_chunk_size=nn[KMG] [X86]
658 used for mtrr cleanup. It is largest continous chunk
659 that could hold holes aka. UC entries.
661 mtrr_gran_size=nn[KMG] [X86]
662 Used for mtrr cleanup. It is granularity of mtrr block.
664 Large value could prevent small alignment from
667 mtrr_spare_reg_nr=n [X86]
669 Range: 0,7 : spare reg number
671 Used for mtrr cleanup. It is spare mtrr entries number.
672 Set to 2 or more if your graphical card needs more.
674 disable_mtrr_trim [X86, Intel and AMD only]
675 By default the kernel will trim any uncacheable
676 memory out of your available memory pool based on
677 MTRR settings. This parameter disables that behavior,
678 possibly causing your machine to run very slowly.
680 dmasound= [HW,OSS] Sound subsystem buffers
686 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
688 earlyprintk=serial[,ttySn[,baudrate]]
691 Append ",keep" to not disable it when the real console
694 Only vga or serial or usb debug port at a time.
696 Currently only ttyS0 and ttyS1 are supported.
698 Interaction with the standard serial driver is not
701 The VGA output is eventually overwritten by the real
707 Format: {"off" | "on" | "skip[mbr]"}
709 eisa_irq_edge= [PARISC,HW]
710 See header of drivers/parisc/eisa.c.
713 See comment before function elanfreq_setup() in
714 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
717 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
718 See Documentation/block/as-iosched.txt and
719 Documentation/block/deadline-iosched.txt for details.
721 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
722 Specifies physical address of start of kernel core
723 image elf header. Generally kexec loader will
724 pass this option to capture kernel.
725 See Documentation/kdump/kdump.txt for details.
727 enforcing [SELINUX] Set initial enforcing status.
729 See security/selinux/Kconfig help text.
730 0 -- permissive (log only, no denials).
731 1 -- enforcing (deny and log).
733 Value can be changed at runtime via /selinux/enforce.
736 Format: <spdif>,[<nomix>,[<amplifier>]]
737 See also header of sound/oss/es1371.c.
739 ether= [HW,NET] Ethernet cards parameters
740 This option is obsoleted by the "netdev=" option, which
741 has equivalent usage. See its documentation for details.
743 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
748 fail_make_request=[KNL]
749 General fault injection mechanism.
750 Format: <interval>,<probability>,<space>,<times>
751 See also /Documentation/fault-injection/.
754 See header of drivers/scsi/fd_mcs.c.
757 See header of drivers/scsi/fdomain.c.
760 See Documentation/floppy.txt.
762 force_pal_cache_flush
763 [IA-64] Avoid check_sal_cache_flush which may hang on
764 buggy SAL_CACHE_FLUSH implementations. Using this
765 parameter will force ia64_sal_cache_flush to call
766 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
769 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
770 support via parallel port (up to 5 devices per port)
771 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
772 See also Documentation/input/joystick-parport.txt
776 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
781 See header of drivers/scsi/gdth.c.
783 gpt [EFI] Forces disk with valid GPT signature but
784 invalid Protective MBR to be treated as GPT.
788 hashdist= [KNL,NUMA] Large hashes allocated during boot
789 are distributed across NUMA nodes. Defaults on
790 for IA-64, off otherwise.
791 Format: 0 | 1 (for off | on)
793 hcl= [IA-64] SGI's Hardware Graph compatibility layer
795 hd= [EIDE] (E)IDE hard drive subsystem geometry
796 Format: <cyl>,<head>,<sect>
798 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
799 size of <nn>. This works even on boxes that have no
800 highmem otherwise. This also works to reduce highmem
801 size on bigger boxes.
803 highres= [KNL] Enable/disable high resolution timer mode.
804 Valid parameters: "on", "off"
808 See Documentation/isdn/README.HiSax.
810 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
811 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
812 On x86-64 and powerpc, this option can be specified
813 multiple times interleaved with hugepages= to reserve
814 huge pages of different sizes. Valid pages sizes on
815 x86-64 are 2M (when the CPU supports "pse") and 1G
816 (when the CPU supports the "pdpe1gb" cpuinfo flag)
817 Note that 1GB pages can only be allocated at boot time
818 using hugepages= and not freed afterwards.
820 [same as hugepagesz=] The size of the default
821 HugeTLB page size. This is the size represented by
822 the legacy /proc/ hugepages APIs, used for SHM, and
823 default size when mounting hugetlbfs filesystems.
824 Defaults to the default architecture's huge page size
829 i8042.debug [HW] Toggle i8042 debug mode
830 i8042.direct [HW] Put keyboard port into non-translated mode
831 i8042.dumbkbd [HW] Pretend that controller can only read data from
832 keyboard and cannot control its state
833 (Don't attempt to blink the leds)
834 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
835 i8042.nokbd [HW] Don't check/create keyboard port
836 i8042.noloop [HW] Disable the AUX Loopback command while probing
838 i8042.nomux [HW] Don't check presence of an active multiplexing
840 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
843 [HW] Frequency with which keyboard LEDs should blink
844 when kernel panics (default is 0.5 sec)
845 i8042.reset [HW] Reset the controller during init and cleanup
846 i8042.unlock [HW] Unlock (ignore) the keylock
850 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
851 indicates that the driver is running on unsupported
853 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
854 does not match list of supported models.
856 [HW] Report power status in /proc/i8k
857 (disabled by default)
858 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
861 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
862 See Documentation/mca.txt.
865 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
867 ide= [HW] (E)IDE subsystem
868 Format: ide=nodma or ide=doubler
869 See Documentation/ide/ide.txt.
871 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
872 See Documentation/ide/ide.txt.
875 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
876 Poll forces a polling idle loop that can slightly improves the performance
877 of waking up a idle CPU, but will use a lot of power and make the system
878 run hot. Not recommended.
879 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
880 to not use it because it doesn't save as much power as a normal idle
881 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
883 idle=halt. Halt is forced to be used for CPU idle.
884 In such case C2/C3 won't be used again.
885 idle=nomwait. Disable mwait for CPU C-states
887 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
888 Claim all unknown PCI IDE storage controllers.
890 ignore_loglevel [KNL]
891 Ignore loglevel setting - this will print /all/
892 kernel messages to the console. Useful for debugging.
895 Set number of hash buckets for inode cache.
898 See header of drivers/scsi/in2000.c.
902 Run specified binary instead of /sbin/init as init
905 initcall_debug [KNL] Trace initcalls as they are executed. Useful
906 for working out where the kernel is dying during
909 initrd= [BOOT] Specify the location of the initial ramdisk
911 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
929 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
931 Disable intel iommu driver.
932 igfx_off [Default Off]
933 By default, gfx is mapped as normal device. If a gfx
934 device has a dedicated DMAR unit, the DMAR unit is
935 bypassed by not enabling DMAR with this option. In
936 this case, gfx device will use physical address for
939 With this option iommu will not optimize to look
940 for io virtual address below 32 bit forcing dual
941 address cycle on pci bus for cards supporting greater
942 than 32 bit addressing. The default is to look
943 for translation below 32 bit and if not available
944 then look in the higher range.
946 With this option on every unmap_single operation will
947 result in a hardware IOTLB flush operation as opposed
948 to batching them for performance.
950 io_delay= [X86-32,X86-64] I/O delay method
952 Standard port 0x80 based delay
954 Alternate port 0xed based delay (needed on some systems)
956 Simple two microseconds delay
960 io7= [HW] IO7 for Marvel based alpha systems
961 See comment before marvel_specify_io7 in
962 arch/alpha/kernel/core_marvel.c.
965 See Documentation/filesystems/nfsroot.txt.
967 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
968 See comment before ip2_setup() in
969 drivers/char/ip2/ip2base.c.
971 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
972 See header of drivers/scsi/ips.c.
974 ports= [IP_VS_FTP] IPVS ftp helper module
976 Up to 8 (IP_VS_APP_MAX_PORTS) ports
978 Format: <port>,<port>....
981 When an interrupt is not handled search all handlers
982 for it. Intended to get systems with badly broken
986 When an interrupt is not handled search all handlers
987 for it. Also check all handlers each timer
988 interrupt. Intended to get systems with badly broken
992 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
994 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
996 <cpu number>,...,<cpu number>
998 <cpu number>-<cpu number> (must be a positive range in ascending order)
1000 <cpu number>,...,<cpu number>-<cpu number>
1001 This option can be used to specify one or more CPUs
1002 to isolate from the general SMP balancing and scheduling
1003 algorithms. The only way to move a process onto or off
1004 an "isolated" CPU is via the CPU affinity syscalls.
1005 <cpu number> begins at 0 and the maximum value is
1006 "number of CPUs in system - 1".
1008 This option is the preferred way to isolate CPUs. The
1009 alternative -- manually setting the CPU mask of all
1010 tasks in the system -- can cause problems and
1011 suboptimal load balancer performance.
1015 js= [HW,JOY] Analog joystick
1016 See Documentation/input/joystick.txt.
1018 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1019 specifies the amount of memory usable by the kernel
1020 for non-movable allocations. The requested amount is
1021 spread evenly throughout all nodes in the system. The
1022 remaining memory in each node is used for Movable
1023 pages. In the event, a node is too small to have both
1024 kernelcore and Movable pages, kernelcore pages will
1025 take priority and other nodes will have a larger number
1026 of kernelcore pages. The Movable zone is used for the
1027 allocation of pages that may be reclaimed or moved
1028 by the page migration subsystem. This means that
1029 HugeTLB pages may not be allocated from this zone.
1030 Note that allocations like PTEs-from-HighMem still
1031 use the HighMem zone if it exists, and the Normal
1032 zone if it does not.
1034 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1035 is similar to kernelcore except it specifies the
1036 amount of memory used for migratable allocations.
1037 If both kernelcore and movablecore is specified,
1038 then kernelcore will be at *least* the specified
1039 value but may be more. If movablecore on its own
1040 is specified, the administrator must be careful
1041 that the amount of memory usable for all allocations
1046 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1049 kgdboc= [HW] kgdb over consoles.
1050 Requires a tty driver that supports console polling.
1051 (only serial suported for now)
1052 Format: <serial_device>[,baud]
1054 kmac= [MIPS] korina ethernet MAC address.
1055 Configure the RouterBoard 532 series on-chip
1056 Ethernet adapter MAC address.
1062 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1065 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1068 libata.dma= [LIBATA] DMA control
1069 libata.dma=0 Disable all PATA and SATA DMA
1070 libata.dma=1 PATA and SATA Disk DMA only
1071 libata.dma=2 ATAPI (CDROM) DMA only
1072 libata.dma=4 Compact Flash DMA only
1073 Combinations also work, so libata.dma=3 enables DMA
1074 for disks and CDROMs, but not CFs.
1076 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1080 libata.force= [LIBATA] Force configurations. The format is comma
1081 separated list of "[ID:]VAL" where ID is
1082 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1083 matching port, link or device. Basically, it matches
1084 the ATA ID string printed on console by libata. If
1085 the whole ID part is omitted, the last PORT and DEVICE
1086 values are used. If ID hasn't been specified yet, the
1087 configuration applies to all ports, links and devices.
1089 If only DEVICE is omitted, the parameter applies to
1090 the port and all links and devices behind it. DEVICE
1091 number of 0 either selects the first device or the
1092 first fan-out link behind PMP device. It does not
1093 select the host link. DEVICE number of 15 selects the
1094 host link and device attached to it.
1096 The VAL specifies the configuration to force. As long
1097 as there's no ambiguity shortcut notation is allowed.
1098 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1099 The following configurations can be forced.
1101 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1102 Any ID with matching PORT is used.
1104 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1106 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1107 udma[/][16,25,33,44,66,100,133] notation is also
1110 * [no]ncq: Turn on or off NCQ.
1112 * nohrst, nosrst, norst: suppress hard, soft
1115 If there are multiple matching configurations changing
1116 the same attribute, the last one is used.
1118 load_ramdisk= [RAM] List of ramdisks to load from floppy
1119 See Documentation/ramdisk.txt.
1121 lockd.nlm_grace_period=P [NFS] Assign grace period.
1124 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1127 lockd.nlm_timeout=T [NFS] Assign timeout value.
1130 lockd.nlm_udpport=M [NFS] Assign UDP port.
1133 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1136 loglevel= All Kernel Messages with a loglevel smaller than the
1137 console loglevel will be printed to the console. It can
1138 also be changed with klogd or other programs. The
1139 loglevels are defined as follows:
1141 0 (KERN_EMERG) system is unusable
1142 1 (KERN_ALERT) action must be taken immediately
1143 2 (KERN_CRIT) critical conditions
1144 3 (KERN_ERR) error conditions
1145 4 (KERN_WARNING) warning conditions
1146 5 (KERN_NOTICE) normal but significant condition
1147 6 (KERN_INFO) informational
1148 7 (KERN_DEBUG) debug-level messages
1150 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1151 Format: { n | nk | nM }
1152 n must be a power of two. The default size
1153 is set in the kernel config file.
1155 logo.nologo [FB] Disables display of the built-in Linux logo.
1156 This may be used to provide more screen space for
1157 kernel log messages and is useful when debugging
1158 kernel boot problems.
1160 lp=0 [LP] Specify parallel ports to use, e.g,
1161 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1162 lp=reset first parallel port). 'lp=0' disables the
1163 lp=auto printer driver. 'lp=reset' (which can be
1164 specified in addition to the ports) causes
1165 attached printers to be reset. Using
1166 lp=port1,port2,... specifies the parallel ports
1167 to associate lp devices with, starting with
1168 lp0. A port specification may be 'none' to skip
1169 that lp device, or a parport name such as
1170 'parport0'. Specifying 'lp=auto' instead of a
1171 port specification list means that device IDs
1172 from each port should be examined, to see if
1173 an IEEE 1284-compliant printer is attached; if
1174 so, the driver will manage that printer.
1175 See also header of drivers/char/lp.c.
1178 Sets loops_per_jiffy to given constant, thus avoiding
1179 time-consuming boot-time autodetection (up to 250 ms per
1180 CPU). 0 enables autodetection (default). To determine
1181 the correct value for your kernel, boot with normal
1182 autodetection and see what value is printed. Note that
1183 on SMP systems the preset will be applied to all CPUs,
1184 which is likely to cause problems if your CPUs need
1185 significantly divergent settings. An incorrect value
1186 will cause delays in the kernel to be wrong, leading to
1187 unpredictable I/O errors and other breakage. Although
1188 unlikely, in the extreme case this might damage your
1192 Format: <io>,<irq>,<dma>
1194 mac5380= [HW,SCSI] Format:
1195 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1197 machvec= [IA64] Force the use of a particular machine-vector
1198 (machvec) in a generic kernel.
1199 Example: machvec=hpzx1_swiotlb
1201 max_loop= [LOOP] Maximum number of loopback devices that can
1205 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1206 should make use of. maxcpus=n : n >= 0 limits the
1207 kernel to using 'n' processors. n=0 is a special case,
1208 it is equivalent to "nosmp", which also disables
1211 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1212 equal to this physical address is ignored.
1214 max_luns= [SCSI] Maximum number of LUNs to probe.
1215 Should be between 1 and 2^32-1.
1218 [SCSI] Maximum number of LUNs received.
1219 Should be between 1 and 16384.
1223 mce [X86-32] Machine Check Exception
1225 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1227 md= [HW] RAID subsystems devices and level
1228 See Documentation/md.txt.
1231 Format: <first>,<last>
1232 Specifies range of consoles to be captured by the MDA.
1234 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1235 Amount of memory to be used when the kernel is not able
1236 to see the whole system memory or for test.
1237 [X86-32] Use together with memmap= to avoid physical
1238 address space collisions. Without memmap= PCI devices
1239 could be placed at addresses belonging to unused RAM.
1241 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1245 [KNL,SH] Allow user to override the default size for
1246 per-device physically contiguous DMA buffers.
1248 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1249 E820 memory map, as specified by the user.
1250 Such memmap=exactmap lines can be constructed based on
1251 BIOS output or other requirements. See the memmap=nn@ss
1254 memmap=nn[KMG]@ss[KMG]
1255 [KNL] Force usage of a specific region of memory
1256 Region of memory to be used, from ss to ss+nn.
1258 memmap=nn[KMG]#ss[KMG]
1259 [KNL,ACPI] Mark specific memory as ACPI data.
1260 Region of memory to be used, from ss to ss+nn.
1262 memmap=nn[KMG]$ss[KMG]
1263 [KNL,ACPI] Mark specific memory as reserved.
1264 Region of memory to be used, from ss to ss+nn.
1265 Example: Exclude memory from 0x18690000-0x1869ffff
1266 memmap=64K$0x18690000
1268 memmap=0x10000$0x18690000
1270 memory_corruption_check=0/1 [X86]
1271 Some BIOSes seem to corrupt the first 64k of
1272 memory when doing things like suspend/resume.
1273 Setting this option will scan the memory
1274 looking for corruption. Enabling this will
1275 both detect corruption and prevent the kernel
1276 from using the memory being corrupted.
1277 However, its intended as a diagnostic tool; if
1278 repeatable BIOS-originated corruption always
1279 affects the same memory, you can use memmap=
1280 to prevent the kernel from using that memory.
1282 memory_corruption_check_size=size [X86]
1283 By default it checks for corruption in the low
1284 64k, making this memory unavailable for normal
1285 use. Use this parameter to scan for
1286 corruption in more or less memory.
1288 memory_corruption_check_period=seconds [X86]
1289 By default it checks for corruption every 60
1290 seconds. Use this parameter to check at some
1291 other rate. 0 disables periodic checking.
1293 memtest= [KNL,X86] Enable memtest
1295 range: 0,4 : pattern number
1296 default : 0 <disable>
1298 meye.*= [HW] Set MotionEye Camera parameters
1299 See Documentation/video4linux/meye.txt.
1301 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1302 Multi-Function General Purpose Timers on AMD Geode
1305 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1306 the BIOS has incorrectly applied a workaround. TinyBIOS
1307 version 0.98 is known to be affected, 0.99 fixes the
1308 problem by letting the user disable the workaround.
1313 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1314 parameter allows control of the logging verbosity for
1315 the additional memory initialisation checks. A value
1316 of 0 disables mminit logging and a level of 4 will
1317 log everything. Information is printed at KERN_DEBUG
1318 so loglevel=8 may also need to be specified.
1321 [MOUSE] Maximum time between finger touching and
1322 leaving touchpad surface for touch to be considered
1323 a tap and be reported as a left button click (for
1324 touchpads working in absolute mode only).
1326 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1327 reporting absolute coordinates, such as tablets
1328 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1329 reporting absolute coordinates, such as tablets
1334 MTD_Partition= [MTD]
1335 Format: <name>,<region-number>,<size>,<offset>
1337 MTD_Region= [MTD] Format:
1338 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1341 See drivers/mtd/cmdlinepart.c.
1344 ARM/S3C2412 JIVE boot control
1346 See arch/arm/mach-s3c2412/mach-jive.c
1348 mtouchusb.raw_coordinates=
1349 [HW] Make the MicroTouch USB driver use raw coordinates
1350 ('y', default) or cooked coordinates ('n')
1352 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1355 See header of drivers/scsi/NCR_D700.c.
1359 ncr53c400= [HW,SCSI]
1361 ncr53c400a= [HW,SCSI]
1363 ncr53c406a= [HW,SCSI]
1365 ncr53c8xx= [HW,SCSI]
1367 netdev= [NET] Network devices parameters
1368 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1369 Note that mem_start is often overloaded to mean
1370 something different and driver-specific.
1371 This usage is only documented in each driver source
1375 [NETFILTER] Enable connection tracking flow accounting
1376 0 to disable accounting
1377 1 to enable accounting
1378 Default value depends on CONFIG_NF_CT_ACCT that is
1379 going to be removed in 2.6.29.
1382 See Documentation/filesystems/nfsroot.txt.
1384 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1385 See Documentation/filesystems/nfsroot.txt.
1387 nfs.callback_tcpport=
1388 [NFS] set the TCP port on which the NFSv4 callback
1389 channel should listen.
1391 nfs.idmap_cache_timeout=
1392 [NFS] set the maximum lifetime for idmapper cache
1396 [NFS] enable 64-bit inode numbers.
1397 If zero, the NFS client will fake up a 32-bit inode
1398 number for the readdir() and stat() syscalls instead
1399 of returning the full 64-bit number.
1400 The default is to return 64-bit inode numbers.
1402 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1403 when a NMI is triggered.
1404 Format: [state][,regs][,debounce][,die]
1406 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1408 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1409 emulation library even if a 387 maths coprocessor
1412 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1413 caches in the slab allocator. Saves per-node memory,
1414 but will impact performance.
1418 noapic [SMP,APIC] Tells the kernel to not make use of any
1419 IOAPICs that may be present in the system.
1421 nobats [PPC] Do not use BATs for mapping kernel lowmem
1422 on "Classic" PPC cores.
1426 nodelayacct [KNL] Disable per-task delay accounting
1428 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1430 nodsp [SH] Disable hardware DSP at boot time.
1432 noefi [X86-32,X86-64] Disable EFI runtime services support.
1436 noexec [X86-32,X86-64]
1437 On X86-32 available only on PAE configured kernels.
1438 noexec=on: enable non-executable mappings (default)
1439 noexec=off: disable non-executable mappings
1442 This affects only 32-bit executables.
1443 noexec32=on: enable non-executable mappings (default)
1444 read doesn't imply executable mappings
1445 noexec32=off: disable non-executable mappings
1446 read implies executable mappings
1448 nofpu [SH] Disable hardware FPU at boot time.
1450 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1451 register save and restore. The kernel will only save
1452 legacy floating-point registers on task switch.
1454 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1458 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1459 instruction doesn't work correctly and not to
1462 nohalt [IA-64] Tells the kernel not to use the power saving
1463 function PAL_HALT_LIGHT when idle. This increases
1464 power-consumption. On the positive side, it reduces
1465 interrupt wake-up latency, which may improve performance
1466 in certain environments such as networked servers or
1469 nohz= [KNL] Boottime enable/disable dynamic ticks
1470 Valid arguments: on, off
1473 noirqdebug [X86-32] Disables the code which attempts to detect and
1474 disable unhandled interrupt sources.
1476 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1477 broken timer IRQ sources.
1479 noisapnp [ISAPNP] Disables ISA PnP code.
1481 noinitrd [RAM] Tells the kernel not to load any configured
1486 nojitter [IA64] Disables jitter checking for ITC timers.
1488 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1490 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1492 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1494 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1495 default x2apic cluster mode on platforms
1498 noltlbs [PPC] Do not use large page/tlb entries for kernel
1499 lowmem mapping on PPC40x.
1501 nomca [IA-64] Disable machine check abort handling
1503 nomce [X86-32] Machine Check Exception
1505 nomfgpt [X86-32] Disable Multi-Function General Purpose
1506 Timer usage (for AMD Geode machines).
1508 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1510 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1511 with UP alternatives
1513 noresidual [PPC] Don't use residual data on PReP machines.
1515 noresume [SWSUSP] Disables resume and restores original swap
1518 no-scroll [VGA] Disables scrollback.
1519 This is required for the Braillex ib80-piezo Braille
1520 reader made by F.H. Papenmeier (Germany).
1524 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1526 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1527 and disable the IO APIC. legacy for "maxcpus=0".
1529 nosoftlockup [KNL] Disable the soft-lockup detector.
1531 nosync [HW,M68K] Disables sync negotiation for all devices.
1533 notsc [BUGS=X86-32] Disable Time Stamp Counter
1535 nousb [USB] Disable the USB subsystem
1539 nptcg= [IA64] Override max number of concurrent global TLB
1540 purges which is reported from either PAL_VM_SUMMARY or
1543 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1544 one of ['zone', 'node', 'default'] can be specified
1545 This can be set from sysctl after boot.
1546 See Documentation/sysctl/vm.txt for details.
1548 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1550 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1551 Rather than timing out after 20 ms if an EC
1552 command is not properly ACKed, override the length
1553 of the timeout. We have interrupts disabled while
1554 waiting for the ACK, so if this is set too high
1555 interrupts *may* be lost!
1560 oprofile.timer= [HW]
1561 Use timer interrupt instead of performance counters
1563 osst= [HW,SCSI] SCSI Tape Driver
1564 Format: <buffer_size>,<write_threshold>
1565 See also Documentation/scsi/st.txt.
1567 panic= [KNL] Kernel behaviour on panic
1570 parkbd.port= [HW] Parallel port number the keyboard adapter is
1571 connected to, default is 0.
1573 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1574 0 for XT, 1 for AT (default is AT).
1577 parport= [HW,PPT] Specify parallel ports. 0 disables.
1578 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1579 Use 'auto' to force the driver to use any
1580 IRQ/DMA settings detected (the default is to
1581 ignore detected IRQ/DMA settings because of
1582 possible conflicts). You can specify the base
1583 address, IRQ, and DMA settings; IRQ and DMA
1584 should be numbers, or 'auto' (for using detected
1585 settings on that particular port), or 'nofifo'
1586 (to avoid using a FIFO even if it is detected).
1587 Parallel ports are assigned in the order they
1588 are specified on the command line, starting
1591 parport_init_mode= [HW,PPT]
1592 Configure VIA parallel port to operate in
1593 a specific mode. This is necessary on Pegasos
1594 computer where firmware has no options for setting
1595 up parallel port mode and sets it to spp.
1596 Currently this function knows 686a and 8231 chips.
1597 Format: [spp|ps2|epp|ecp|ecpepp]
1599 pas2= [HW,OSS] Format:
1600 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1603 See header of drivers/scsi/pas16.c.
1606 Halt all CPUs after the first oops has been printed for
1607 the specified number of seconds. This is to be used if
1608 your oopses keep scrolling off the screen.
1613 See header of drivers/block/paride/pcd.c.
1614 See also Documentation/paride.txt.
1616 pci=option[,option...] [PCI] various PCI subsystem options:
1617 off [X86] don't probe for the PCI bus
1618 bios [X86-32] force use of PCI BIOS, don't access
1619 the hardware directly. Use this if your machine
1620 has a non-standard PCI host bridge.
1621 nobios [X86-32] disallow use of PCI BIOS, only direct
1622 hardware access methods are allowed. Use this
1623 if you experience crashes upon bootup and you
1624 suspect they are caused by the BIOS.
1625 conf1 [X86] Force use of PCI Configuration
1627 conf2 [X86] Force use of PCI Configuration
1629 noaer [PCIE] If the PCIEAER kernel config parameter is
1630 enabled, this kernel boot option can be used to
1631 disable the use of PCIE advanced error reporting.
1632 nodomains [PCI] Disable support for multiple PCI
1633 root domains (aka PCI segments, in ACPI-speak).
1634 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1636 nomsi [MSI] If the PCI_MSI kernel config parameter is
1637 enabled, this kernel boot option can be used to
1638 disable the use of MSI interrupts system-wide.
1639 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1640 routing table. These calls are known to be buggy
1641 on several machines and they hang the machine
1642 when used, but on other computers it's the only
1643 way to get the interrupt routing table. Try
1644 this option if the kernel is unable to allocate
1645 IRQs or discover secondary PCI buses on your
1647 rom [X86] Assign address space to expansion ROMs.
1648 Use with caution as certain devices share
1649 address decoders between ROMs and other
1651 norom [X86] Do not assign address space to
1652 expansion ROMs that do not already have
1653 BIOS assigned address ranges.
1654 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1655 assigned automatically to PCI devices. You can
1656 make the kernel exclude IRQs of your ISA cards
1658 pirqaddr=0xAAAAA [X86] Specify the physical address
1659 of the PIRQ table (normally generated
1660 by the BIOS) if it is outside the
1661 F0000h-100000h range.
1662 lastbus=N [X86] Scan all buses thru bus #N. Can be
1663 useful if the kernel is unable to find your
1664 secondary buses and you want to tell it
1665 explicitly which ones they are.
1666 assign-busses [X86] Always assign all PCI bus
1667 numbers ourselves, overriding
1668 whatever the firmware may have done.
1669 usepirqmask [X86] Honor the possible IRQ mask stored
1670 in the BIOS $PIR table. This is needed on
1671 some systems with broken BIOSes, notably
1672 some HP Pavilion N5400 and Omnibook XE3
1673 notebooks. This will have no effect if ACPI
1674 IRQ routing is enabled.
1675 noacpi [X86] Do not use ACPI for IRQ routing
1676 or for PCI scanning.
1677 use_crs [X86] Use _CRS for PCI resource
1679 routeirq Do IRQ routing for all PCI devices.
1680 This is normally done in pci_enable_device(),
1681 so this option is a temporary workaround
1682 for broken drivers that don't call it.
1683 skip_isa_align [X86] do not align io start addr, so can
1684 handle more pci cards
1685 firmware [ARM] Do not re-enumerate the bus but instead
1686 just use the configuration from the
1687 bootloader. This is currently used on
1688 IXP2000 systems where the bus has to be
1689 configured a certain way for adjunct CPUs.
1690 noearly [X86] Don't do any early type 1 scanning.
1691 This might help on some broken boards which
1692 machine check when some devices' config space
1693 is read. But various workarounds are disabled
1694 and some IOMMU drivers will not work.
1695 bfsort Sort PCI devices into breadth-first order.
1696 This sorting is done to get a device
1697 order compatible with older (<= 2.4) kernels.
1698 nobfsort Don't sort PCI devices into breadth-first order.
1699 cbiosize=nn[KMG] The fixed amount of bus space which is
1700 reserved for the CardBus bridge's IO window.
1701 The default value is 256 bytes.
1702 cbmemsize=nn[KMG] The fixed amount of bus space which is
1703 reserved for the CardBus bridge's memory
1704 window. The default value is 64 megabytes.
1706 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1709 force Enable ASPM even on devices that claim not to support it.
1710 WARNING: Forcing ASPM on may cause system lockups.
1712 pcmv= [HW,PCMCIA] BadgePAD 4
1715 See Documentation/paride.txt.
1717 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1720 See arch/parisc/kernel/pdc_chassis.c
1723 See Documentation/paride.txt.
1726 See Documentation/paride.txt.
1728 pirq= [SMP,APIC] Manual mp-table setup
1729 See Documentation/x86/i386/IO-APIC.txt.
1731 plip= [PPT,NET] Parallel port network link
1732 Format: { parport<nr> | timid | 0 }
1733 See also Documentation/parport.txt.
1735 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1736 Override pmtimer IOPort with a hex value.
1740 Enable PNP debug messages. This depends on the
1741 CONFIG_PNP_DEBUG_MESSAGES option.
1747 { on | off | curr | res | no-curr | no-res }
1750 [ISAPNP] Exclude IRQs for the autoconfiguration
1753 [ISAPNP] Exclude DMAs for the autoconfiguration
1755 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1756 Ranges are in pairs (I/O port base and size).
1759 [ISAPNP] Exclude memory regions for the
1761 Ranges are in pairs (memory base and size).
1764 Enables pr_debug()/dev_dbg() calls if
1765 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1766 be switched on/off via <debugfs>/dynamic_printk/modules
1768 print-fatal-signals=
1769 [KNL] debug: print fatal signals
1770 print-fatal-signals=1: print segfault info to
1774 printk.time= Show timing data prefixed to each printk message line
1775 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1777 profile= [KNL] Enable kernel profiling via /proc/profile
1778 Format: [schedule,]<number>
1779 Param: "schedule" - profile schedule points.
1780 Param: <number> - step/bucket size as a power of 2 for
1781 statistical time based profiling.
1782 Param: "sleep" - profile D-state sleeping (millisecs).
1783 Requires CONFIG_SCHEDSTATS
1784 Param: "kvm" - profile VM exits.
1786 processor.max_cstate= [HW,ACPI]
1787 Limit processor to maximum C-state
1788 max_cstate=9 overrides any DMI blacklist limit.
1790 processor.nocst [HW,ACPI]
1791 Ignore the _CST method to determine C-states,
1792 instead using the legacy FADT method
1794 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1796 See Documentation/ramdisk.txt.
1798 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1799 probe for; one of (bare|imps|exps|lifebook|any).
1800 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1802 psmouse.resetafter= [HW,MOUSE]
1803 Try to reset the device after so many bad packets
1806 [HW,MOUSE] Set desired mouse resolution, in dpi.
1807 psmouse.smartscroll=
1808 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1809 0 = disabled, 1 = enabled (default).
1811 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1813 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1816 See Documentation/paride.txt.
1819 [KNL] Number of legacy pty's. Overwrites compiled-in
1822 quiet [KNL] Disable most log messages
1827 See Documentation/md.txt.
1829 ramdisk_blocksize= [RAM]
1830 See Documentation/ramdisk.txt.
1832 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1833 See Documentation/ramdisk.txt.
1835 rcupdate.blimit= [KNL,BOOT]
1836 Set maximum number of finished RCU callbacks to process
1839 rcupdate.qhimark= [KNL,BOOT]
1840 Set threshold of queued
1841 RCU callbacks over which batch limiting is disabled.
1843 rcupdate.qlowmark= [KNL,BOOT]
1844 Set threshold of queued RCU callbacks below which
1845 batch limiting is re-enabled.
1849 Run specified binary instead of /init from the ramdisk,
1850 used for early userspace startup. See initrd.
1852 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1853 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1854 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1857 [KNL, SMP] Set scheduler's default relax_domain_level.
1858 See Documentation/cpusets.txt.
1860 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1862 reservetop= [X86-32]
1864 Reserves a hole at the top of the kernel virtual
1867 reset_devices [KNL] Force drivers to reset the underlying device
1868 during initialization.
1871 Specify the partition device for software suspend
1873 resume_offset= [SWSUSP]
1874 Specify the offset from the beginning of the partition
1875 given by "resume=" at which the swap header is located,
1876 in <PAGE_SIZE> units (needed only for swap files).
1877 See Documentation/power/swsusp-and-swap-files.txt
1879 retain_initrd [RAM] Keep initrd memory after extraction
1881 rhash_entries= [KNL,NET]
1882 Set number of hash buckets for route cache
1884 riscom8= [HW,SERIAL]
1885 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1887 ro [KNL] Mount root device read-only on boot
1889 root= [KNL] Root filesystem
1891 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1892 mount the root filesystem
1894 rootflags= [KNL] Set root filesystem mount option string
1896 rootfstype= [KNL] Set root filesystem type
1898 rootwait [KNL] Wait (indefinitely) for root device to show up.
1899 Useful for devices that are detected asynchronously
1900 (e.g. USB and MMC devices).
1902 root_plug.vendor_id=
1903 [ROOTPLUG] Override the default vendor ID
1905 root_plug.product_id=
1906 [ROOTPLUG] Override the default product ID
1909 [ROOTPLUG] Enable debugging output
1911 rw [KNL] Mount root device read-write on boot
1913 S [KNL] Run init in single mode
1916 See drivers/net/irda/sa1100_ir.c.
1918 sbni= [NET] Granch SBNI12 leased line adapter
1920 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1921 Format: <io>[,<timeout>[,<isapnp>]]
1923 scsi_debug_*= [SCSI]
1924 See drivers/scsi/scsi_debug.c.
1926 scsi_default_dev_flags=
1927 [SCSI] SCSI default device flags
1930 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1931 Format: <vendor>:<model>:<flags>
1932 (flags are integer value)
1934 scsi_logging_level= [SCSI] a bit mask of logging levels
1935 See drivers/scsi/scsi_logging.h for bits. Also
1936 settable via sysctl at dev.scsi.logging_level
1937 (/proc/sys/dev/scsi/logging_level).
1938 There is also a nice 'scsi_logging_level' script in the
1939 S390-tools package, available for download at
1940 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1942 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1943 discovered. async scans them in kernel threads,
1944 allowing boot to proceed. none ignores them, expecting
1945 user space to do the scan.
1947 selinux [SELINUX] Disable or enable SELinux at boot time.
1948 Format: { "0" | "1" }
1949 See security/selinux/Kconfig help text.
1952 Default value is set via kernel config option.
1953 If enabled at boot time, /selinux/disable can be used
1954 later to disable prior to initial policy load.
1956 selinux_compat_net =
1957 [SELINUX] Set initial selinux_compat_net flag value.
1958 Format: { "0" | "1" }
1959 0 -- use new secmark-based packet controls
1960 1 -- use legacy packet controls
1961 Default value is 0 (preferred).
1962 Value can be changed at runtime via
1963 /selinux/compat_net.
1965 serialnumber [BUGS=X86-32]
1968 Maximal number of shapers.
1970 show_msr= [x86] show boot-time MSR settings
1971 Format: { <integer> }
1972 Show boot-time (BIOS-initialized) MSR settings.
1973 The parameter means the number of CPUs to show,
1974 for example 1 means boot CPU only.
1977 See header of drivers/scsi/sim710.c.
1984 slub_debug[=options[,slabs]] [MM, SLUB]
1985 Enabling slub_debug allows one to determine the
1986 culprit if slab objects become corrupted. Enabling
1987 slub_debug can create guard zones around objects and
1988 may poison objects when not in use. Also tracks the
1989 last alloc / free. For more information see
1990 Documentation/vm/slub.txt.
1992 slub_max_order= [MM, SLUB]
1993 Determines the maximum allowed order for slabs.
1994 A high setting may cause OOMs due to memory
1995 fragmentation. For more information see
1996 Documentation/vm/slub.txt.
1998 slub_min_objects= [MM, SLUB]
1999 The minimum number of objects per slab. SLUB will
2000 increase the slab order up to slub_max_order to
2001 generate a sufficiently large slab able to contain
2002 the number of objects indicated. The higher the number
2003 of objects the smaller the overhead of tracking slabs
2004 and the less frequently locks need to be acquired.
2005 For more information see Documentation/vm/slub.txt.
2007 slub_min_order= [MM, SLUB]
2008 Determines the mininum page order for slabs. Must be
2009 lower than slub_max_order.
2010 For more information see Documentation/vm/slub.txt.
2012 slub_nomerge [MM, SLUB]
2013 Disable merging of slabs with similar size. May be
2014 necessary if there is some reason to distinguish
2015 allocs to different slabs. Debug options disable
2016 merging on their own.
2017 For more information see Documentation/vm/slub.txt.
2020 Format: <io1>[,<io2>[,...,<io8>]]
2022 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2023 attempt to substitute SMP alternatives once at boot.
2025 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2026 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2027 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2028 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2029 smsc-ircc2.ircc_irq= [HW] IRQ line
2030 smsc-ircc2.ircc_dma= [HW] DMA channel
2031 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2032 0: Toshiba Satellite 1800 (GP data pin select)
2033 1: Fast pin select (default)
2036 snd-ad1816a= [HW,ALSA]
2038 snd-ad1848= [HW,ALSA]
2040 snd-ali5451= [HW,ALSA]
2042 snd-als100= [HW,ALSA]
2044 snd-als4000= [HW,ALSA]
2046 snd-azt2320= [HW,ALSA]
2048 snd-cmi8330= [HW,ALSA]
2050 snd-cmipci= [HW,ALSA]
2052 snd-cs4231= [HW,ALSA]
2054 snd-cs4232= [HW,ALSA]
2056 snd-cs4236= [HW,ALSA]
2058 snd-cs4281= [HW,ALSA]
2060 snd-cs46xx= [HW,ALSA]
2062 snd-dt019x= [HW,ALSA]
2064 snd-dummy= [HW,ALSA]
2066 snd-emu10k1= [HW,ALSA]
2068 snd-ens1370= [HW,ALSA]
2070 snd-ens1371= [HW,ALSA]
2072 snd-es968= [HW,ALSA]
2074 snd-es1688= [HW,ALSA]
2076 snd-es18xx= [HW,ALSA]
2078 snd-es1938= [HW,ALSA]
2080 snd-es1968= [HW,ALSA]
2082 snd-fm801= [HW,ALSA]
2084 snd-gusclassic= [HW,ALSA]
2086 snd-gusextreme= [HW,ALSA]
2088 snd-gusmax= [HW,ALSA]
2092 snd-ice1712= [HW,ALSA]
2094 snd-intel8x0= [HW,ALSA]
2096 snd-interwave= [HW,ALSA]
2101 snd-korg1212= [HW,ALSA]
2103 snd-maestro3= [HW,ALSA]
2105 snd-mpu401= [HW,ALSA]
2107 snd-mtpav= [HW,ALSA]
2109 snd-nm256= [HW,ALSA]
2111 snd-opl3sa2= [HW,ALSA]
2119 snd-opti93x= [HW,ALSA]
2123 snd-rme32= [HW,ALSA]
2125 snd-rme96= [HW,ALSA]
2127 snd-rme9652= [HW,ALSA]
2133 snd-sbawe= [HW,ALSA]
2135 snd-serial= [HW,ALSA]
2137 snd-sgalaxy= [HW,ALSA]
2139 snd-sonicvibes= [HW,ALSA]
2144 snd-sun-cs4231= [HW,ALSA]
2146 snd-trident= [HW,ALSA]
2148 snd-usb-audio= [HW,ALSA,USB]
2150 snd-via82xx= [HW,ALSA]
2152 snd-virmidi= [HW,ALSA]
2154 snd-wavefront= [HW,ALSA]
2156 snd-ymfpci= [HW,ALSA]
2159 [KNL] Should the soft-lockup detector generate panics.
2161 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2162 See Documentation/sonypi.txt
2164 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2165 See Documentation/specialix.txt.
2167 spia_io_base= [HW,MTD]
2173 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2175 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2176 See Documentation/scsi/st.txt.
2180 Set the STI (builtin display/keyboard on the HP-PARISC
2181 machines) console (graphic card) which should be used
2182 as the initial boot-console.
2183 See also comment in drivers/video/console/sticore.c.
2186 See comment in drivers/video/console/sticore.c.
2189 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2193 Control how the NFS server code allocates CPUs to
2194 service thread pools. Depending on how many NICs
2195 you have and where their interrupts are bound, this
2196 option will affect which CPUs will do NFS serving.
2197 Note: this parameter cannot be changed while the
2198 NFS server is running.
2200 auto the server chooses an appropriate mode
2201 automatically using heuristics
2202 global a single global pool contains all CPUs
2203 percpu one pool for each CPU
2204 pernode one pool for each NUMA node (equivalent
2205 to global on non-NUMA machines)
2207 swiotlb= [IA-64] Number of I/O TLB slabs
2211 sym53c416= [HW,SCSI]
2212 See header of drivers/scsi/sym53c416.c.
2214 sysrq_always_enabled
2216 Ignore sysrq setting - this boot parameter will
2217 neutralize any effect of /proc/sys/kernel/sysrq.
2218 Useful for debugging.
2221 See header of drivers/scsi/t128.c.
2225 test_suspend= [SUSPEND]
2226 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2227 standby suspend) as the system sleep state to briefly
2228 enter during system startup. The system is woken from
2229 this state using a wakeup-capable RTC alarm.
2231 thash_entries= [KNL,NET]
2232 Set number of hash buckets for TCP connection
2234 thermal.act= [HW,ACPI]
2235 -1: disable all active trip points in all thermal zones
2236 <degrees C>: override all lowest active trip points
2238 thermal.crt= [HW,ACPI]
2239 -1: disable all critical trip points in all thermal zones
2240 <degrees C>: override all critical trip points
2242 thermal.nocrt= [HW,ACPI]
2243 Set to disable actions on ACPI thermal zone
2244 critical and hot trip points.
2246 thermal.off= [HW,ACPI]
2247 1: disable ACPI thermal control
2249 thermal.psv= [HW,ACPI]
2250 -1: disable all passive trip points
2251 <degrees C>: override all passive trip points to this value
2253 thermal.tzp= [HW,ACPI]
2254 Specify global default ACPI thermal zone polling rate
2255 <deci-seconds>: poll all this frequency
2256 0: no polling (default)
2259 See comment before function dc390_setup() in
2260 drivers/scsi/tmscsim.c.
2264 trix= [HW,OSS] MediaTrix AudioTrix Pro
2266 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2268 turbografx.map[2|3]= [HW,JOY]
2269 TurboGraFX parallel port interface
2271 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2272 See also Documentation/input/joystick-parport.txt
2274 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2275 See header of drivers/scsi/u14-34f.c.
2284 [USB] Ignore overcurrent events (default N).
2285 Some badly-designed motherboards generate lots of
2286 bogus events, for ports that aren't wired to
2287 anything. Set this parameter to avoid log spamming.
2288 Note that genuine overcurrent events won't be
2293 Set unknown_nmi_panic=1 early on boot.
2295 usbcore.autosuspend=
2296 [USB] The autosuspend time delay (in seconds) used
2297 for newly-detected USB devices (default 2). This
2298 is the time required before an idle device will be
2299 autosuspended. Devices for which the delay is set
2300 to a negative value won't be autosuspended at all.
2302 usbcore.usbfs_snoop=
2303 [USB] Set to log all usbfs traffic (default 0 = off).
2305 usbcore.blinkenlights=
2306 [USB] Set to cycle leds on hubs (default 0 = off).
2308 usbcore.old_scheme_first=
2309 [USB] Start with the old device initialization
2310 scheme (default 0 = off).
2312 usbcore.use_both_schemes=
2313 [USB] Try the other device initialization scheme
2314 if the first one fails (default 1 = enabled).
2316 usbcore.initial_descriptor_timeout=
2317 [USB] Specifies timeout for the initial 64-byte
2318 USB_REQ_GET_DESCRIPTOR request in milliseconds
2319 (default 5000 = 5.0 seconds).
2322 [USBHID] The interval which mice are to be polled at.
2324 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2325 kernel's map of available physical RAM.
2327 vdso= [X86-32,SH,x86-64]
2328 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2329 vdso=1: enable VDSO (default)
2330 vdso=0: disable VDSO mapping
2332 vdso32= [X86-32,X86-64]
2333 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2334 vdso32=1: enable 32-bit VDSO (default)
2335 vdso32=0: disable 32-bit VDSO mapping
2338 vector=percpu: enable percpu vector domain
2340 video= [FB] Frame buffer configuration
2341 See Documentation/fb/modedb.txt.
2343 vga= [BOOT,X86-32] Select a particular video mode
2344 See Documentation/x86/i386/boot.txt and
2345 Documentation/svga.txt.
2346 Use vga=ask for menu.
2347 This is actually a boot loader parameter; the value is
2348 passed to the kernel using a special protocol.
2350 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2351 size of <nn>. This can be used to increase the
2352 minimum size (128MB on x86). It can also be used to
2353 decrease the size and leave more room for directly
2356 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2359 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2362 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2365 waveartist= [HW,OSS]
2366 Format: <io>,<irq>,<dma>,<dma2>
2369 See header of drivers/scsi/wd33c93.c.
2372 See header of drivers/scsi/wd7000.c.
2375 See Documentation/watchdog/wdt.txt.
2377 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2378 xd_geo= See header of drivers/block/xd.c.
2380 xirc2ps_cs= [NET,PCMCIA]
2382 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2384 norandmaps Don't use address space randomization
2385 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2387 ______________________________________________________________________
2391 Add documentation for ALSA options.
2392 Add more DRM drivers.
projects / linux-2.6 / blob