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 [ftrace] will set and start the specified tracer
770 as early as possible in order to facilitate early
774 [ftrace] will dump the trace buffers on oops.
777 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
778 support via parallel port (up to 5 devices per port)
779 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
780 See also Documentation/input/joystick-parport.txt
784 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
789 See header of drivers/scsi/gdth.c.
791 gpt [EFI] Forces disk with valid GPT signature but
792 invalid Protective MBR to be treated as GPT.
796 hashdist= [KNL,NUMA] Large hashes allocated during boot
797 are distributed across NUMA nodes. Defaults on
798 for IA-64, off otherwise.
799 Format: 0 | 1 (for off | on)
801 hcl= [IA-64] SGI's Hardware Graph compatibility layer
803 hd= [EIDE] (E)IDE hard drive subsystem geometry
804 Format: <cyl>,<head>,<sect>
806 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
807 size of <nn>. This works even on boxes that have no
808 highmem otherwise. This also works to reduce highmem
809 size on bigger boxes.
811 highres= [KNL] Enable/disable high resolution timer mode.
812 Valid parameters: "on", "off"
816 See Documentation/isdn/README.HiSax.
818 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
819 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
820 On x86-64 and powerpc, this option can be specified
821 multiple times interleaved with hugepages= to reserve
822 huge pages of different sizes. Valid pages sizes on
823 x86-64 are 2M (when the CPU supports "pse") and 1G
824 (when the CPU supports the "pdpe1gb" cpuinfo flag)
825 Note that 1GB pages can only be allocated at boot time
826 using hugepages= and not freed afterwards.
828 [same as hugepagesz=] The size of the default
829 HugeTLB page size. This is the size represented by
830 the legacy /proc/ hugepages APIs, used for SHM, and
831 default size when mounting hugetlbfs filesystems.
832 Defaults to the default architecture's huge page size
837 i8042.debug [HW] Toggle i8042 debug mode
838 i8042.direct [HW] Put keyboard port into non-translated mode
839 i8042.dumbkbd [HW] Pretend that controller can only read data from
840 keyboard and cannot control its state
841 (Don't attempt to blink the leds)
842 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
843 i8042.nokbd [HW] Don't check/create keyboard port
844 i8042.noloop [HW] Disable the AUX Loopback command while probing
846 i8042.nomux [HW] Don't check presence of an active multiplexing
848 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
851 [HW] Frequency with which keyboard LEDs should blink
852 when kernel panics (default is 0.5 sec)
853 i8042.reset [HW] Reset the controller during init and cleanup
854 i8042.unlock [HW] Unlock (ignore) the keylock
858 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
859 indicates that the driver is running on unsupported
861 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
862 does not match list of supported models.
864 [HW] Report power status in /proc/i8k
865 (disabled by default)
866 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
869 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
870 See Documentation/mca.txt.
873 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
875 ide= [HW] (E)IDE subsystem
876 Format: ide=nodma or ide=doubler
877 See Documentation/ide/ide.txt.
879 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
880 See Documentation/ide/ide.txt.
883 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
884 Poll forces a polling idle loop that can slightly improves the performance
885 of waking up a idle CPU, but will use a lot of power and make the system
886 run hot. Not recommended.
887 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
888 to not use it because it doesn't save as much power as a normal idle
889 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
891 idle=halt. Halt is forced to be used for CPU idle.
892 In such case C2/C3 won't be used again.
893 idle=nomwait. Disable mwait for CPU C-states
895 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
896 Claim all unknown PCI IDE storage controllers.
898 ignore_loglevel [KNL]
899 Ignore loglevel setting - this will print /all/
900 kernel messages to the console. Useful for debugging.
903 Set number of hash buckets for inode cache.
906 See header of drivers/scsi/in2000.c.
910 Run specified binary instead of /sbin/init as init
913 initcall_debug [KNL] Trace initcalls as they are executed. Useful
914 for working out where the kernel is dying during
917 initrd= [BOOT] Specify the location of the initial ramdisk
919 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
937 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
939 Disable intel iommu driver.
940 igfx_off [Default Off]
941 By default, gfx is mapped as normal device. If a gfx
942 device has a dedicated DMAR unit, the DMAR unit is
943 bypassed by not enabling DMAR with this option. In
944 this case, gfx device will use physical address for
947 With this option iommu will not optimize to look
948 for io virtual address below 32 bit forcing dual
949 address cycle on pci bus for cards supporting greater
950 than 32 bit addressing. The default is to look
951 for translation below 32 bit and if not available
952 then look in the higher range.
954 With this option on every unmap_single operation will
955 result in a hardware IOTLB flush operation as opposed
956 to batching them for performance.
958 io_delay= [X86-32,X86-64] I/O delay method
960 Standard port 0x80 based delay
962 Alternate port 0xed based delay (needed on some systems)
964 Simple two microseconds delay
968 io7= [HW] IO7 for Marvel based alpha systems
969 See comment before marvel_specify_io7 in
970 arch/alpha/kernel/core_marvel.c.
973 See Documentation/filesystems/nfsroot.txt.
975 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
976 See comment before ip2_setup() in
977 drivers/char/ip2/ip2base.c.
979 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
980 See header of drivers/scsi/ips.c.
982 ports= [IP_VS_FTP] IPVS ftp helper module
984 Up to 8 (IP_VS_APP_MAX_PORTS) ports
986 Format: <port>,<port>....
989 When an interrupt is not handled search all handlers
990 for it. Intended to get systems with badly broken
994 When an interrupt is not handled search all handlers
995 for it. Also check all handlers each timer
996 interrupt. Intended to get systems with badly broken
1000 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1002 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1004 <cpu number>,...,<cpu number>
1006 <cpu number>-<cpu number> (must be a positive range in ascending order)
1008 <cpu number>,...,<cpu number>-<cpu number>
1009 This option can be used to specify one or more CPUs
1010 to isolate from the general SMP balancing and scheduling
1011 algorithms. The only way to move a process onto or off
1012 an "isolated" CPU is via the CPU affinity syscalls.
1013 <cpu number> begins at 0 and the maximum value is
1014 "number of CPUs in system - 1".
1016 This option is the preferred way to isolate CPUs. The
1017 alternative -- manually setting the CPU mask of all
1018 tasks in the system -- can cause problems and
1019 suboptimal load balancer performance.
1023 js= [HW,JOY] Analog joystick
1024 See Documentation/input/joystick.txt.
1026 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1027 specifies the amount of memory usable by the kernel
1028 for non-movable allocations. The requested amount is
1029 spread evenly throughout all nodes in the system. The
1030 remaining memory in each node is used for Movable
1031 pages. In the event, a node is too small to have both
1032 kernelcore and Movable pages, kernelcore pages will
1033 take priority and other nodes will have a larger number
1034 of kernelcore pages. The Movable zone is used for the
1035 allocation of pages that may be reclaimed or moved
1036 by the page migration subsystem. This means that
1037 HugeTLB pages may not be allocated from this zone.
1038 Note that allocations like PTEs-from-HighMem still
1039 use the HighMem zone if it exists, and the Normal
1040 zone if it does not.
1042 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1043 is similar to kernelcore except it specifies the
1044 amount of memory used for migratable allocations.
1045 If both kernelcore and movablecore is specified,
1046 then kernelcore will be at *least* the specified
1047 value but may be more. If movablecore on its own
1048 is specified, the administrator must be careful
1049 that the amount of memory usable for all allocations
1054 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1057 kgdboc= [HW] kgdb over consoles.
1058 Requires a tty driver that supports console polling.
1059 (only serial suported for now)
1060 Format: <serial_device>[,baud]
1062 kmac= [MIPS] korina ethernet MAC address.
1063 Configure the RouterBoard 532 series on-chip
1064 Ethernet adapter MAC address.
1070 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1073 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1076 libata.dma= [LIBATA] DMA control
1077 libata.dma=0 Disable all PATA and SATA DMA
1078 libata.dma=1 PATA and SATA Disk DMA only
1079 libata.dma=2 ATAPI (CDROM) DMA only
1080 libata.dma=4 Compact Flash DMA only
1081 Combinations also work, so libata.dma=3 enables DMA
1082 for disks and CDROMs, but not CFs.
1084 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1088 libata.force= [LIBATA] Force configurations. The format is comma
1089 separated list of "[ID:]VAL" where ID is
1090 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1091 matching port, link or device. Basically, it matches
1092 the ATA ID string printed on console by libata. If
1093 the whole ID part is omitted, the last PORT and DEVICE
1094 values are used. If ID hasn't been specified yet, the
1095 configuration applies to all ports, links and devices.
1097 If only DEVICE is omitted, the parameter applies to
1098 the port and all links and devices behind it. DEVICE
1099 number of 0 either selects the first device or the
1100 first fan-out link behind PMP device. It does not
1101 select the host link. DEVICE number of 15 selects the
1102 host link and device attached to it.
1104 The VAL specifies the configuration to force. As long
1105 as there's no ambiguity shortcut notation is allowed.
1106 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1107 The following configurations can be forced.
1109 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1110 Any ID with matching PORT is used.
1112 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1114 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1115 udma[/][16,25,33,44,66,100,133] notation is also
1118 * [no]ncq: Turn on or off NCQ.
1120 * nohrst, nosrst, norst: suppress hard, soft
1123 If there are multiple matching configurations changing
1124 the same attribute, the last one is used.
1126 load_ramdisk= [RAM] List of ramdisks to load from floppy
1127 See Documentation/ramdisk.txt.
1129 lockd.nlm_grace_period=P [NFS] Assign grace period.
1132 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1135 lockd.nlm_timeout=T [NFS] Assign timeout value.
1138 lockd.nlm_udpport=M [NFS] Assign UDP port.
1141 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1144 loglevel= All Kernel Messages with a loglevel smaller than the
1145 console loglevel will be printed to the console. It can
1146 also be changed with klogd or other programs. The
1147 loglevels are defined as follows:
1149 0 (KERN_EMERG) system is unusable
1150 1 (KERN_ALERT) action must be taken immediately
1151 2 (KERN_CRIT) critical conditions
1152 3 (KERN_ERR) error conditions
1153 4 (KERN_WARNING) warning conditions
1154 5 (KERN_NOTICE) normal but significant condition
1155 6 (KERN_INFO) informational
1156 7 (KERN_DEBUG) debug-level messages
1158 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1159 Format: { n | nk | nM }
1160 n must be a power of two. The default size
1161 is set in the kernel config file.
1163 logo.nologo [FB] Disables display of the built-in Linux logo.
1164 This may be used to provide more screen space for
1165 kernel log messages and is useful when debugging
1166 kernel boot problems.
1168 lp=0 [LP] Specify parallel ports to use, e.g,
1169 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1170 lp=reset first parallel port). 'lp=0' disables the
1171 lp=auto printer driver. 'lp=reset' (which can be
1172 specified in addition to the ports) causes
1173 attached printers to be reset. Using
1174 lp=port1,port2,... specifies the parallel ports
1175 to associate lp devices with, starting with
1176 lp0. A port specification may be 'none' to skip
1177 that lp device, or a parport name such as
1178 'parport0'. Specifying 'lp=auto' instead of a
1179 port specification list means that device IDs
1180 from each port should be examined, to see if
1181 an IEEE 1284-compliant printer is attached; if
1182 so, the driver will manage that printer.
1183 See also header of drivers/char/lp.c.
1186 Sets loops_per_jiffy to given constant, thus avoiding
1187 time-consuming boot-time autodetection (up to 250 ms per
1188 CPU). 0 enables autodetection (default). To determine
1189 the correct value for your kernel, boot with normal
1190 autodetection and see what value is printed. Note that
1191 on SMP systems the preset will be applied to all CPUs,
1192 which is likely to cause problems if your CPUs need
1193 significantly divergent settings. An incorrect value
1194 will cause delays in the kernel to be wrong, leading to
1195 unpredictable I/O errors and other breakage. Although
1196 unlikely, in the extreme case this might damage your
1200 Format: <io>,<irq>,<dma>
1202 mac5380= [HW,SCSI] Format:
1203 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1205 machvec= [IA64] Force the use of a particular machine-vector
1206 (machvec) in a generic kernel.
1207 Example: machvec=hpzx1_swiotlb
1209 max_loop= [LOOP] Maximum number of loopback devices that can
1213 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1214 should make use of. maxcpus=n : n >= 0 limits the
1215 kernel to using 'n' processors. n=0 is a special case,
1216 it is equivalent to "nosmp", which also disables
1219 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1220 equal to this physical address is ignored.
1222 max_luns= [SCSI] Maximum number of LUNs to probe.
1223 Should be between 1 and 2^32-1.
1226 [SCSI] Maximum number of LUNs received.
1227 Should be between 1 and 16384.
1231 mce [X86-32] Machine Check Exception
1233 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1235 md= [HW] RAID subsystems devices and level
1236 See Documentation/md.txt.
1239 Format: <first>,<last>
1240 Specifies range of consoles to be captured by the MDA.
1242 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1243 Amount of memory to be used when the kernel is not able
1244 to see the whole system memory or for test.
1245 [X86-32] Use together with memmap= to avoid physical
1246 address space collisions. Without memmap= PCI devices
1247 could be placed at addresses belonging to unused RAM.
1249 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1253 [KNL,SH] Allow user to override the default size for
1254 per-device physically contiguous DMA buffers.
1256 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1257 E820 memory map, as specified by the user.
1258 Such memmap=exactmap lines can be constructed based on
1259 BIOS output or other requirements. See the memmap=nn@ss
1262 memmap=nn[KMG]@ss[KMG]
1263 [KNL] Force usage of a specific region of memory
1264 Region of memory to be used, from ss to ss+nn.
1266 memmap=nn[KMG]#ss[KMG]
1267 [KNL,ACPI] Mark specific memory as ACPI data.
1268 Region of memory to be used, from ss to ss+nn.
1270 memmap=nn[KMG]$ss[KMG]
1271 [KNL,ACPI] Mark specific memory as reserved.
1272 Region of memory to be used, from ss to ss+nn.
1273 Example: Exclude memory from 0x18690000-0x1869ffff
1274 memmap=64K$0x18690000
1276 memmap=0x10000$0x18690000
1278 memory_corruption_check=0/1 [X86]
1279 Some BIOSes seem to corrupt the first 64k of
1280 memory when doing things like suspend/resume.
1281 Setting this option will scan the memory
1282 looking for corruption. Enabling this will
1283 both detect corruption and prevent the kernel
1284 from using the memory being corrupted.
1285 However, its intended as a diagnostic tool; if
1286 repeatable BIOS-originated corruption always
1287 affects the same memory, you can use memmap=
1288 to prevent the kernel from using that memory.
1290 memory_corruption_check_size=size [X86]
1291 By default it checks for corruption in the low
1292 64k, making this memory unavailable for normal
1293 use. Use this parameter to scan for
1294 corruption in more or less memory.
1296 memory_corruption_check_period=seconds [X86]
1297 By default it checks for corruption every 60
1298 seconds. Use this parameter to check at some
1299 other rate. 0 disables periodic checking.
1301 memtest= [KNL,X86] Enable memtest
1303 range: 0,4 : pattern number
1304 default : 0 <disable>
1306 meye.*= [HW] Set MotionEye Camera parameters
1307 See Documentation/video4linux/meye.txt.
1309 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1310 Multi-Function General Purpose Timers on AMD Geode
1313 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1314 the BIOS has incorrectly applied a workaround. TinyBIOS
1315 version 0.98 is known to be affected, 0.99 fixes the
1316 problem by letting the user disable the workaround.
1321 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1322 parameter allows control of the logging verbosity for
1323 the additional memory initialisation checks. A value
1324 of 0 disables mminit logging and a level of 4 will
1325 log everything. Information is printed at KERN_DEBUG
1326 so loglevel=8 may also need to be specified.
1329 [MOUSE] Maximum time between finger touching and
1330 leaving touchpad surface for touch to be considered
1331 a tap and be reported as a left button click (for
1332 touchpads working in absolute mode only).
1334 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1335 reporting absolute coordinates, such as tablets
1336 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1337 reporting absolute coordinates, such as tablets
1342 MTD_Partition= [MTD]
1343 Format: <name>,<region-number>,<size>,<offset>
1345 MTD_Region= [MTD] Format:
1346 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1349 See drivers/mtd/cmdlinepart.c.
1352 ARM/S3C2412 JIVE boot control
1354 See arch/arm/mach-s3c2412/mach-jive.c
1356 mtouchusb.raw_coordinates=
1357 [HW] Make the MicroTouch USB driver use raw coordinates
1358 ('y', default) or cooked coordinates ('n')
1360 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1363 See header of drivers/scsi/NCR_D700.c.
1367 ncr53c400= [HW,SCSI]
1369 ncr53c400a= [HW,SCSI]
1371 ncr53c406a= [HW,SCSI]
1373 ncr53c8xx= [HW,SCSI]
1375 netdev= [NET] Network devices parameters
1376 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1377 Note that mem_start is often overloaded to mean
1378 something different and driver-specific.
1379 This usage is only documented in each driver source
1383 [NETFILTER] Enable connection tracking flow accounting
1384 0 to disable accounting
1385 1 to enable accounting
1386 Default value depends on CONFIG_NF_CT_ACCT that is
1387 going to be removed in 2.6.29.
1390 See Documentation/filesystems/nfsroot.txt.
1392 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1393 See Documentation/filesystems/nfsroot.txt.
1395 nfs.callback_tcpport=
1396 [NFS] set the TCP port on which the NFSv4 callback
1397 channel should listen.
1399 nfs.idmap_cache_timeout=
1400 [NFS] set the maximum lifetime for idmapper cache
1404 [NFS] enable 64-bit inode numbers.
1405 If zero, the NFS client will fake up a 32-bit inode
1406 number for the readdir() and stat() syscalls instead
1407 of returning the full 64-bit number.
1408 The default is to return 64-bit inode numbers.
1410 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1411 when a NMI is triggered.
1412 Format: [state][,regs][,debounce][,die]
1414 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1416 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1417 emulation library even if a 387 maths coprocessor
1420 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1421 caches in the slab allocator. Saves per-node memory,
1422 but will impact performance.
1426 noapic [SMP,APIC] Tells the kernel to not make use of any
1427 IOAPICs that may be present in the system.
1429 nobats [PPC] Do not use BATs for mapping kernel lowmem
1430 on "Classic" PPC cores.
1434 nodelayacct [KNL] Disable per-task delay accounting
1436 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1438 nodsp [SH] Disable hardware DSP at boot time.
1440 noefi [X86-32,X86-64] Disable EFI runtime services support.
1444 noexec [X86-32,X86-64]
1445 On X86-32 available only on PAE configured kernels.
1446 noexec=on: enable non-executable mappings (default)
1447 noexec=off: disable non-executable mappings
1450 This affects only 32-bit executables.
1451 noexec32=on: enable non-executable mappings (default)
1452 read doesn't imply executable mappings
1453 noexec32=off: disable non-executable mappings
1454 read implies executable mappings
1456 nofpu [SH] Disable hardware FPU at boot time.
1458 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1459 register save and restore. The kernel will only save
1460 legacy floating-point registers on task switch.
1462 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1466 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1467 instruction doesn't work correctly and not to
1470 nohalt [IA-64] Tells the kernel not to use the power saving
1471 function PAL_HALT_LIGHT when idle. This increases
1472 power-consumption. On the positive side, it reduces
1473 interrupt wake-up latency, which may improve performance
1474 in certain environments such as networked servers or
1477 nohz= [KNL] Boottime enable/disable dynamic ticks
1478 Valid arguments: on, off
1481 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1483 noirqdebug [X86-32] Disables the code which attempts to detect and
1484 disable unhandled interrupt sources.
1486 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1487 broken timer IRQ sources.
1489 noisapnp [ISAPNP] Disables ISA PnP code.
1491 noinitrd [RAM] Tells the kernel not to load any configured
1496 nojitter [IA64] Disables jitter checking for ITC timers.
1498 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1500 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1502 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1504 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1505 default x2apic cluster mode on platforms
1508 noltlbs [PPC] Do not use large page/tlb entries for kernel
1509 lowmem mapping on PPC40x.
1511 nomca [IA-64] Disable machine check abort handling
1513 nomce [X86-32] Machine Check Exception
1515 nomfgpt [X86-32] Disable Multi-Function General Purpose
1516 Timer usage (for AMD Geode machines).
1518 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1520 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1521 with UP alternatives
1523 noresidual [PPC] Don't use residual data on PReP machines.
1525 noresume [SWSUSP] Disables resume and restores original swap
1528 no-scroll [VGA] Disables scrollback.
1529 This is required for the Braillex ib80-piezo Braille
1530 reader made by F.H. Papenmeier (Germany).
1534 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1536 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1537 and disable the IO APIC. legacy for "maxcpus=0".
1539 nosoftlockup [KNL] Disable the soft-lockup detector.
1541 nosync [HW,M68K] Disables sync negotiation for all devices.
1543 notsc [BUGS=X86-32] Disable Time Stamp Counter
1545 nousb [USB] Disable the USB subsystem
1549 nptcg= [IA64] Override max number of concurrent global TLB
1550 purges which is reported from either PAL_VM_SUMMARY or
1553 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1554 one of ['zone', 'node', 'default'] can be specified
1555 This can be set from sysctl after boot.
1556 See Documentation/sysctl/vm.txt for details.
1558 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1560 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1561 Rather than timing out after 20 ms if an EC
1562 command is not properly ACKed, override the length
1563 of the timeout. We have interrupts disabled while
1564 waiting for the ACK, so if this is set too high
1565 interrupts *may* be lost!
1570 oprofile.timer= [HW]
1571 Use timer interrupt instead of performance counters
1573 osst= [HW,SCSI] SCSI Tape Driver
1574 Format: <buffer_size>,<write_threshold>
1575 See also Documentation/scsi/st.txt.
1577 panic= [KNL] Kernel behaviour on panic
1580 parkbd.port= [HW] Parallel port number the keyboard adapter is
1581 connected to, default is 0.
1583 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1584 0 for XT, 1 for AT (default is AT).
1587 parport= [HW,PPT] Specify parallel ports. 0 disables.
1588 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1589 Use 'auto' to force the driver to use any
1590 IRQ/DMA settings detected (the default is to
1591 ignore detected IRQ/DMA settings because of
1592 possible conflicts). You can specify the base
1593 address, IRQ, and DMA settings; IRQ and DMA
1594 should be numbers, or 'auto' (for using detected
1595 settings on that particular port), or 'nofifo'
1596 (to avoid using a FIFO even if it is detected).
1597 Parallel ports are assigned in the order they
1598 are specified on the command line, starting
1601 parport_init_mode= [HW,PPT]
1602 Configure VIA parallel port to operate in
1603 a specific mode. This is necessary on Pegasos
1604 computer where firmware has no options for setting
1605 up parallel port mode and sets it to spp.
1606 Currently this function knows 686a and 8231 chips.
1607 Format: [spp|ps2|epp|ecp|ecpepp]
1609 pas2= [HW,OSS] Format:
1610 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1613 See header of drivers/scsi/pas16.c.
1616 Halt all CPUs after the first oops has been printed for
1617 the specified number of seconds. This is to be used if
1618 your oopses keep scrolling off the screen.
1623 See header of drivers/block/paride/pcd.c.
1624 See also Documentation/paride.txt.
1626 pci=option[,option...] [PCI] various PCI subsystem options:
1627 off [X86] don't probe for the PCI bus
1628 bios [X86-32] force use of PCI BIOS, don't access
1629 the hardware directly. Use this if your machine
1630 has a non-standard PCI host bridge.
1631 nobios [X86-32] disallow use of PCI BIOS, only direct
1632 hardware access methods are allowed. Use this
1633 if you experience crashes upon bootup and you
1634 suspect they are caused by the BIOS.
1635 conf1 [X86] Force use of PCI Configuration
1637 conf2 [X86] Force use of PCI Configuration
1639 noaer [PCIE] If the PCIEAER kernel config parameter is
1640 enabled, this kernel boot option can be used to
1641 disable the use of PCIE advanced error reporting.
1642 nodomains [PCI] Disable support for multiple PCI
1643 root domains (aka PCI segments, in ACPI-speak).
1644 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1646 nomsi [MSI] If the PCI_MSI kernel config parameter is
1647 enabled, this kernel boot option can be used to
1648 disable the use of MSI interrupts system-wide.
1649 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1650 routing table. These calls are known to be buggy
1651 on several machines and they hang the machine
1652 when used, but on other computers it's the only
1653 way to get the interrupt routing table. Try
1654 this option if the kernel is unable to allocate
1655 IRQs or discover secondary PCI buses on your
1657 rom [X86] Assign address space to expansion ROMs.
1658 Use with caution as certain devices share
1659 address decoders between ROMs and other
1661 norom [X86] Do not assign address space to
1662 expansion ROMs that do not already have
1663 BIOS assigned address ranges.
1664 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1665 assigned automatically to PCI devices. You can
1666 make the kernel exclude IRQs of your ISA cards
1668 pirqaddr=0xAAAAA [X86] Specify the physical address
1669 of the PIRQ table (normally generated
1670 by the BIOS) if it is outside the
1671 F0000h-100000h range.
1672 lastbus=N [X86] Scan all buses thru bus #N. Can be
1673 useful if the kernel is unable to find your
1674 secondary buses and you want to tell it
1675 explicitly which ones they are.
1676 assign-busses [X86] Always assign all PCI bus
1677 numbers ourselves, overriding
1678 whatever the firmware may have done.
1679 usepirqmask [X86] Honor the possible IRQ mask stored
1680 in the BIOS $PIR table. This is needed on
1681 some systems with broken BIOSes, notably
1682 some HP Pavilion N5400 and Omnibook XE3
1683 notebooks. This will have no effect if ACPI
1684 IRQ routing is enabled.
1685 noacpi [X86] Do not use ACPI for IRQ routing
1686 or for PCI scanning.
1687 use_crs [X86] Use _CRS for PCI resource
1689 routeirq Do IRQ routing for all PCI devices.
1690 This is normally done in pci_enable_device(),
1691 so this option is a temporary workaround
1692 for broken drivers that don't call it.
1693 skip_isa_align [X86] do not align io start addr, so can
1694 handle more pci cards
1695 firmware [ARM] Do not re-enumerate the bus but instead
1696 just use the configuration from the
1697 bootloader. This is currently used on
1698 IXP2000 systems where the bus has to be
1699 configured a certain way for adjunct CPUs.
1700 noearly [X86] Don't do any early type 1 scanning.
1701 This might help on some broken boards which
1702 machine check when some devices' config space
1703 is read. But various workarounds are disabled
1704 and some IOMMU drivers will not work.
1705 bfsort Sort PCI devices into breadth-first order.
1706 This sorting is done to get a device
1707 order compatible with older (<= 2.4) kernels.
1708 nobfsort Don't sort PCI devices into breadth-first order.
1709 cbiosize=nn[KMG] The fixed amount of bus space which is
1710 reserved for the CardBus bridge's IO window.
1711 The default value is 256 bytes.
1712 cbmemsize=nn[KMG] The fixed amount of bus space which is
1713 reserved for the CardBus bridge's memory
1714 window. The default value is 64 megabytes.
1716 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1719 force Enable ASPM even on devices that claim not to support it.
1720 WARNING: Forcing ASPM on may cause system lockups.
1722 pcmv= [HW,PCMCIA] BadgePAD 4
1725 See Documentation/paride.txt.
1727 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1730 See arch/parisc/kernel/pdc_chassis.c
1733 See Documentation/paride.txt.
1736 See Documentation/paride.txt.
1738 pirq= [SMP,APIC] Manual mp-table setup
1739 See Documentation/x86/i386/IO-APIC.txt.
1741 plip= [PPT,NET] Parallel port network link
1742 Format: { parport<nr> | timid | 0 }
1743 See also Documentation/parport.txt.
1745 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1746 Override pmtimer IOPort with a hex value.
1750 Enable PNP debug messages. This depends on the
1751 CONFIG_PNP_DEBUG_MESSAGES option.
1757 { on | off | curr | res | no-curr | no-res }
1760 [ISAPNP] Exclude IRQs for the autoconfiguration
1763 [ISAPNP] Exclude DMAs for the autoconfiguration
1765 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1766 Ranges are in pairs (I/O port base and size).
1769 [ISAPNP] Exclude memory regions for the
1771 Ranges are in pairs (memory base and size).
1774 Enables pr_debug()/dev_dbg() calls if
1775 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1776 be switched on/off via <debugfs>/dynamic_printk/modules
1778 print-fatal-signals=
1779 [KNL] debug: print fatal signals
1780 print-fatal-signals=1: print segfault info to
1784 printk.time= Show timing data prefixed to each printk message line
1785 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1787 profile= [KNL] Enable kernel profiling via /proc/profile
1788 Format: [schedule,]<number>
1789 Param: "schedule" - profile schedule points.
1790 Param: <number> - step/bucket size as a power of 2 for
1791 statistical time based profiling.
1792 Param: "sleep" - profile D-state sleeping (millisecs).
1793 Requires CONFIG_SCHEDSTATS
1794 Param: "kvm" - profile VM exits.
1796 processor.max_cstate= [HW,ACPI]
1797 Limit processor to maximum C-state
1798 max_cstate=9 overrides any DMI blacklist limit.
1800 processor.nocst [HW,ACPI]
1801 Ignore the _CST method to determine C-states,
1802 instead using the legacy FADT method
1804 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1806 See Documentation/ramdisk.txt.
1808 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1809 probe for; one of (bare|imps|exps|lifebook|any).
1810 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1812 psmouse.resetafter= [HW,MOUSE]
1813 Try to reset the device after so many bad packets
1816 [HW,MOUSE] Set desired mouse resolution, in dpi.
1817 psmouse.smartscroll=
1818 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1819 0 = disabled, 1 = enabled (default).
1821 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1823 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1826 See Documentation/paride.txt.
1829 [KNL] Number of legacy pty's. Overwrites compiled-in
1832 quiet [KNL] Disable most log messages
1837 See Documentation/md.txt.
1839 ramdisk_blocksize= [RAM]
1840 See Documentation/ramdisk.txt.
1842 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1843 See Documentation/ramdisk.txt.
1845 rcupdate.blimit= [KNL,BOOT]
1846 Set maximum number of finished RCU callbacks to process
1849 rcupdate.qhimark= [KNL,BOOT]
1850 Set threshold of queued
1851 RCU callbacks over which batch limiting is disabled.
1853 rcupdate.qlowmark= [KNL,BOOT]
1854 Set threshold of queued RCU callbacks below which
1855 batch limiting is re-enabled.
1859 Run specified binary instead of /init from the ramdisk,
1860 used for early userspace startup. See initrd.
1862 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1863 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1864 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1867 [KNL, SMP] Set scheduler's default relax_domain_level.
1868 See Documentation/cpusets.txt.
1870 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1872 reservetop= [X86-32]
1874 Reserves a hole at the top of the kernel virtual
1877 reset_devices [KNL] Force drivers to reset the underlying device
1878 during initialization.
1881 Specify the partition device for software suspend
1883 resume_offset= [SWSUSP]
1884 Specify the offset from the beginning of the partition
1885 given by "resume=" at which the swap header is located,
1886 in <PAGE_SIZE> units (needed only for swap files).
1887 See Documentation/power/swsusp-and-swap-files.txt
1889 retain_initrd [RAM] Keep initrd memory after extraction
1891 rhash_entries= [KNL,NET]
1892 Set number of hash buckets for route cache
1894 riscom8= [HW,SERIAL]
1895 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1897 ro [KNL] Mount root device read-only on boot
1899 root= [KNL] Root filesystem
1901 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1902 mount the root filesystem
1904 rootflags= [KNL] Set root filesystem mount option string
1906 rootfstype= [KNL] Set root filesystem type
1908 rootwait [KNL] Wait (indefinitely) for root device to show up.
1909 Useful for devices that are detected asynchronously
1910 (e.g. USB and MMC devices).
1912 root_plug.vendor_id=
1913 [ROOTPLUG] Override the default vendor ID
1915 root_plug.product_id=
1916 [ROOTPLUG] Override the default product ID
1919 [ROOTPLUG] Enable debugging output
1921 rw [KNL] Mount root device read-write on boot
1923 S [KNL] Run init in single mode
1926 See drivers/net/irda/sa1100_ir.c.
1928 sbni= [NET] Granch SBNI12 leased line adapter
1930 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1931 Format: <io>[,<timeout>[,<isapnp>]]
1933 scsi_debug_*= [SCSI]
1934 See drivers/scsi/scsi_debug.c.
1936 scsi_default_dev_flags=
1937 [SCSI] SCSI default device flags
1940 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1941 Format: <vendor>:<model>:<flags>
1942 (flags are integer value)
1944 scsi_logging_level= [SCSI] a bit mask of logging levels
1945 See drivers/scsi/scsi_logging.h for bits. Also
1946 settable via sysctl at dev.scsi.logging_level
1947 (/proc/sys/dev/scsi/logging_level).
1948 There is also a nice 'scsi_logging_level' script in the
1949 S390-tools package, available for download at
1950 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1952 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1953 discovered. async scans them in kernel threads,
1954 allowing boot to proceed. none ignores them, expecting
1955 user space to do the scan.
1957 selinux [SELINUX] Disable or enable SELinux at boot time.
1958 Format: { "0" | "1" }
1959 See security/selinux/Kconfig help text.
1962 Default value is set via kernel config option.
1963 If enabled at boot time, /selinux/disable can be used
1964 later to disable prior to initial policy load.
1966 selinux_compat_net =
1967 [SELINUX] Set initial selinux_compat_net flag value.
1968 Format: { "0" | "1" }
1969 0 -- use new secmark-based packet controls
1970 1 -- use legacy packet controls
1971 Default value is 0 (preferred).
1972 Value can be changed at runtime via
1973 /selinux/compat_net.
1975 serialnumber [BUGS=X86-32]
1978 Maximal number of shapers.
1980 show_msr= [x86] show boot-time MSR settings
1981 Format: { <integer> }
1982 Show boot-time (BIOS-initialized) MSR settings.
1983 The parameter means the number of CPUs to show,
1984 for example 1 means boot CPU only.
1987 See header of drivers/scsi/sim710.c.
1994 slub_debug[=options[,slabs]] [MM, SLUB]
1995 Enabling slub_debug allows one to determine the
1996 culprit if slab objects become corrupted. Enabling
1997 slub_debug can create guard zones around objects and
1998 may poison objects when not in use. Also tracks the
1999 last alloc / free. For more information see
2000 Documentation/vm/slub.txt.
2002 slub_max_order= [MM, SLUB]
2003 Determines the maximum allowed order for slabs.
2004 A high setting may cause OOMs due to memory
2005 fragmentation. For more information see
2006 Documentation/vm/slub.txt.
2008 slub_min_objects= [MM, SLUB]
2009 The minimum number of objects per slab. SLUB will
2010 increase the slab order up to slub_max_order to
2011 generate a sufficiently large slab able to contain
2012 the number of objects indicated. The higher the number
2013 of objects the smaller the overhead of tracking slabs
2014 and the less frequently locks need to be acquired.
2015 For more information see Documentation/vm/slub.txt.
2017 slub_min_order= [MM, SLUB]
2018 Determines the mininum page order for slabs. Must be
2019 lower than slub_max_order.
2020 For more information see Documentation/vm/slub.txt.
2022 slub_nomerge [MM, SLUB]
2023 Disable merging of slabs with similar size. May be
2024 necessary if there is some reason to distinguish
2025 allocs to different slabs. Debug options disable
2026 merging on their own.
2027 For more information see Documentation/vm/slub.txt.
2030 Format: <io1>[,<io2>[,...,<io8>]]
2032 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2033 attempt to substitute SMP alternatives once at boot.
2035 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2036 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2037 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2038 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2039 smsc-ircc2.ircc_irq= [HW] IRQ line
2040 smsc-ircc2.ircc_dma= [HW] DMA channel
2041 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2042 0: Toshiba Satellite 1800 (GP data pin select)
2043 1: Fast pin select (default)
2046 snd-ad1816a= [HW,ALSA]
2048 snd-ad1848= [HW,ALSA]
2050 snd-ali5451= [HW,ALSA]
2052 snd-als100= [HW,ALSA]
2054 snd-als4000= [HW,ALSA]
2056 snd-azt2320= [HW,ALSA]
2058 snd-cmi8330= [HW,ALSA]
2060 snd-cmipci= [HW,ALSA]
2062 snd-cs4231= [HW,ALSA]
2064 snd-cs4232= [HW,ALSA]
2066 snd-cs4236= [HW,ALSA]
2068 snd-cs4281= [HW,ALSA]
2070 snd-cs46xx= [HW,ALSA]
2072 snd-dt019x= [HW,ALSA]
2074 snd-dummy= [HW,ALSA]
2076 snd-emu10k1= [HW,ALSA]
2078 snd-ens1370= [HW,ALSA]
2080 snd-ens1371= [HW,ALSA]
2082 snd-es968= [HW,ALSA]
2084 snd-es1688= [HW,ALSA]
2086 snd-es18xx= [HW,ALSA]
2088 snd-es1938= [HW,ALSA]
2090 snd-es1968= [HW,ALSA]
2092 snd-fm801= [HW,ALSA]
2094 snd-gusclassic= [HW,ALSA]
2096 snd-gusextreme= [HW,ALSA]
2098 snd-gusmax= [HW,ALSA]
2102 snd-ice1712= [HW,ALSA]
2104 snd-intel8x0= [HW,ALSA]
2106 snd-interwave= [HW,ALSA]
2111 snd-korg1212= [HW,ALSA]
2113 snd-maestro3= [HW,ALSA]
2115 snd-mpu401= [HW,ALSA]
2117 snd-mtpav= [HW,ALSA]
2119 snd-nm256= [HW,ALSA]
2121 snd-opl3sa2= [HW,ALSA]
2129 snd-opti93x= [HW,ALSA]
2133 snd-rme32= [HW,ALSA]
2135 snd-rme96= [HW,ALSA]
2137 snd-rme9652= [HW,ALSA]
2143 snd-sbawe= [HW,ALSA]
2145 snd-serial= [HW,ALSA]
2147 snd-sgalaxy= [HW,ALSA]
2149 snd-sonicvibes= [HW,ALSA]
2154 snd-sun-cs4231= [HW,ALSA]
2156 snd-trident= [HW,ALSA]
2158 snd-usb-audio= [HW,ALSA,USB]
2160 snd-via82xx= [HW,ALSA]
2162 snd-virmidi= [HW,ALSA]
2164 snd-wavefront= [HW,ALSA]
2166 snd-ymfpci= [HW,ALSA]
2169 [KNL] Should the soft-lockup detector generate panics.
2171 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2172 See Documentation/sonypi.txt
2174 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2175 See Documentation/specialix.txt.
2177 spia_io_base= [HW,MTD]
2183 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2185 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2186 See Documentation/scsi/st.txt.
2190 Set the STI (builtin display/keyboard on the HP-PARISC
2191 machines) console (graphic card) which should be used
2192 as the initial boot-console.
2193 See also comment in drivers/video/console/sticore.c.
2196 See comment in drivers/video/console/sticore.c.
2199 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2203 Control how the NFS server code allocates CPUs to
2204 service thread pools. Depending on how many NICs
2205 you have and where their interrupts are bound, this
2206 option will affect which CPUs will do NFS serving.
2207 Note: this parameter cannot be changed while the
2208 NFS server is running.
2210 auto the server chooses an appropriate mode
2211 automatically using heuristics
2212 global a single global pool contains all CPUs
2213 percpu one pool for each CPU
2214 pernode one pool for each NUMA node (equivalent
2215 to global on non-NUMA machines)
2217 swiotlb= [IA-64] Number of I/O TLB slabs
2221 sym53c416= [HW,SCSI]
2222 See header of drivers/scsi/sym53c416.c.
2224 sysrq_always_enabled
2226 Ignore sysrq setting - this boot parameter will
2227 neutralize any effect of /proc/sys/kernel/sysrq.
2228 Useful for debugging.
2231 See header of drivers/scsi/t128.c.
2235 test_suspend= [SUSPEND]
2236 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2237 standby suspend) as the system sleep state to briefly
2238 enter during system startup. The system is woken from
2239 this state using a wakeup-capable RTC alarm.
2241 thash_entries= [KNL,NET]
2242 Set number of hash buckets for TCP connection
2244 thermal.act= [HW,ACPI]
2245 -1: disable all active trip points in all thermal zones
2246 <degrees C>: override all lowest active trip points
2248 thermal.crt= [HW,ACPI]
2249 -1: disable all critical trip points in all thermal zones
2250 <degrees C>: override all critical trip points
2252 thermal.nocrt= [HW,ACPI]
2253 Set to disable actions on ACPI thermal zone
2254 critical and hot trip points.
2256 thermal.off= [HW,ACPI]
2257 1: disable ACPI thermal control
2259 thermal.psv= [HW,ACPI]
2260 -1: disable all passive trip points
2261 <degrees C>: override all passive trip points to this value
2263 thermal.tzp= [HW,ACPI]
2264 Specify global default ACPI thermal zone polling rate
2265 <deci-seconds>: poll all this frequency
2266 0: no polling (default)
2269 See comment before function dc390_setup() in
2270 drivers/scsi/tmscsim.c.
2274 trix= [HW,OSS] MediaTrix AudioTrix Pro
2276 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2278 turbografx.map[2|3]= [HW,JOY]
2279 TurboGraFX parallel port interface
2281 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2282 See also Documentation/input/joystick-parport.txt
2284 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2285 See header of drivers/scsi/u14-34f.c.
2294 [USB] Ignore overcurrent events (default N).
2295 Some badly-designed motherboards generate lots of
2296 bogus events, for ports that aren't wired to
2297 anything. Set this parameter to avoid log spamming.
2298 Note that genuine overcurrent events won't be
2303 Set unknown_nmi_panic=1 early on boot.
2305 usbcore.autosuspend=
2306 [USB] The autosuspend time delay (in seconds) used
2307 for newly-detected USB devices (default 2). This
2308 is the time required before an idle device will be
2309 autosuspended. Devices for which the delay is set
2310 to a negative value won't be autosuspended at all.
2312 usbcore.usbfs_snoop=
2313 [USB] Set to log all usbfs traffic (default 0 = off).
2315 usbcore.blinkenlights=
2316 [USB] Set to cycle leds on hubs (default 0 = off).
2318 usbcore.old_scheme_first=
2319 [USB] Start with the old device initialization
2320 scheme (default 0 = off).
2322 usbcore.use_both_schemes=
2323 [USB] Try the other device initialization scheme
2324 if the first one fails (default 1 = enabled).
2326 usbcore.initial_descriptor_timeout=
2327 [USB] Specifies timeout for the initial 64-byte
2328 USB_REQ_GET_DESCRIPTOR request in milliseconds
2329 (default 5000 = 5.0 seconds).
2332 [USBHID] The interval which mice are to be polled at.
2334 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2335 kernel's map of available physical RAM.
2337 vdso= [X86-32,SH,x86-64]
2338 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2339 vdso=1: enable VDSO (default)
2340 vdso=0: disable VDSO mapping
2342 vdso32= [X86-32,X86-64]
2343 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2344 vdso32=1: enable 32-bit VDSO (default)
2345 vdso32=0: disable 32-bit VDSO mapping
2348 vector=percpu: enable percpu vector domain
2350 video= [FB] Frame buffer configuration
2351 See Documentation/fb/modedb.txt.
2353 vga= [BOOT,X86-32] Select a particular video mode
2354 See Documentation/x86/i386/boot.txt and
2355 Documentation/svga.txt.
2356 Use vga=ask for menu.
2357 This is actually a boot loader parameter; the value is
2358 passed to the kernel using a special protocol.
2360 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2361 size of <nn>. This can be used to increase the
2362 minimum size (128MB on x86). It can also be used to
2363 decrease the size and leave more room for directly
2366 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2369 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2372 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2375 waveartist= [HW,OSS]
2376 Format: <io>,<irq>,<dma>,<dma2>
2379 See header of drivers/scsi/wd33c93.c.
2382 See header of drivers/scsi/wd7000.c.
2385 See Documentation/watchdog/wdt.txt.
2387 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2388 xd_geo= See header of drivers/block/xd.c.
2390 xirc2ps_cs= [NET,PCMCIA]
2392 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2394 norandmaps Don't use address space randomization
2395 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2397 ______________________________________________________________________
2401 Add documentation for ALSA options.
2402 Add more DRM drivers.