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 AX25 Appropriate AX.25 support is enabled.
38 BLACKFIN Blackfin architecture is enabled.
39 DRM Direct Rendering Management support is enabled.
40 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
41 EFI EFI Partitioning (GPT) is enabled
42 EIDE EIDE/ATAPI support is enabled.
43 FB The frame buffer device is enabled.
44 HW Appropriate hardware is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LIBATA Libata driver is enabled
52 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
60 MSI Message Signaled Interrupts (PCI).
61 MTD MTD (Memory Technology Device) support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
64 GENERIC_TIME The generic timeofday code is enabled.
65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PV_OPS A paravirtualized kernel is enabled.
68 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCIE PCI Express support is enabled.
72 PCMCIA The PCMCIA subsystem is enabled.
73 PNP Plug & Play support is enabled.
74 PPC PowerPC architecture is enabled.
75 PPT Parallel port support is enabled.
76 PS2 Appropriate PS/2 support is enabled.
77 RAM RAM disk support is enabled.
78 ROOTPLUG The example Root Plug LSM is enabled.
79 S390 S390 architecture is enabled.
80 SCSI Appropriate SCSI support is enabled.
81 A lot of drivers has their options described inside of
83 SECURITY Different security models are enabled.
84 SELINUX SELinux support is enabled.
85 SERIAL Serial support is enabled.
86 SH SuperH architecture is enabled.
87 SMP The kernel is an SMP kernel.
88 SPARC Sparc architecture is enabled.
89 SWSUSP Software suspend is enabled.
90 TS Appropriate touchscreen support is enabled.
91 USB USB support is enabled.
92 USBHID USB Human Interface Device support is enabled.
93 V4L Video For Linux support is enabled.
94 VGA The VGA console has been enabled.
95 VT Virtual terminal support is enabled.
96 WDT Watchdog support is enabled.
97 XT IBM PC/XT MFM hard disk support is enabled.
98 X86-32 X86-32, aka i386 architecture is enabled.
99 X86-64 X86-64 architecture is enabled.
100 More X86-64 boot options can be found in
101 Documentation/x86_64/boot-options.txt .
103 In addition, the following text indicates that the option:
105 BUGS= Relates to possible processor bugs on the said processor.
106 KNL Is a kernel start-up parameter.
107 BOOT Is a boot loader parameter.
109 Parameters denoted with BOOT are actually interpreted by the boot
110 loader, and have no meaning to the kernel directly.
111 Do not modify the syntax of boot loader parameters without extreme
112 need or coordination with <Documentation/i386/boot.txt>.
114 There are also arch-specific kernel-parameters not documented here.
115 See for example <Documentation/x86_64/boot-options.txt>.
117 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
118 a trailing = on the name of any parameter states that that parameter will
119 be entered as an environment variable, whereas its absence indicates that
120 it will appear as a kernel argument readable via /proc/cmdline by programs
121 running once the system is up.
123 The number of kernel parameters is not limited, but the length of the
124 complete command line (parameters including spaces etc.) is limited to
125 a fixed number of characters. This limit depends on the architecture
126 and is between 256 and 4096 characters. It is defined in the file
127 ./include/asm/setup.h as COMMAND_LINE_SIZE.
130 acpi= [HW,ACPI,X86-64,i386]
131 Advanced Configuration and Power Interface
132 Format: { force | off | ht | strict | noirq }
133 force -- enable ACPI if default was off
134 off -- disable ACPI if default was on
135 noirq -- do not use ACPI for IRQ routing
136 ht -- run only enough ACPI to enable Hyper Threading
137 strict -- Be less tolerant of platforms that are not
138 strictly ACPI specification compliant.
140 See also Documentation/pm.txt, pci=noacpi
142 acpi_apic_instance= [ACPI, IOAPIC]
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
148 acpi_sleep= [HW,ACPI] Sleep options
149 Format: { s3_bios, s3_mode }
150 See Documentation/power/video.txt
152 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
153 Format: { level | edge | high | low }
155 acpi_irq_balance [HW,ACPI]
156 ACPI will balance active IRQs
159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
165 Format: <irq>,<irq>...
167 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
168 Format: <irq>,<irq>...
170 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
172 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
173 Format: To spoof as Windows 98: ="Microsoft Windows"
175 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
176 acpi_osi="string1" # add string1 -- only one string
177 acpi_osi="!string2" # remove built-in string2
178 acpi_osi= # disable all strings
180 acpi_serialize [HW,ACPI] force serialization of AML methods
182 acpi_skip_timer_override [HW,ACPI]
183 Recognize and ignore IRQ0/pin2 Interrupt Override.
184 For broken nForce2 BIOS resulting in XT-PIC timer.
185 acpi_use_timer_override [HW,ACPI}
186 Use timer override. For some broken Nvidia NF5 boards
187 that require a timer override, but don't have
190 acpi.debug_layer= [HW,ACPI]
192 Each bit of the <int> indicates an ACPI debug layer,
193 1: enable, 0: disable. It is useful for boot time
194 debugging. After system has booted up, it can be set
195 via /sys/module/acpi/parameters/debug_layer.
196 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
197 Available bits (add the numbers together) to enable debug output
198 for specific parts of the ACPI subsystem:
199 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
200 0x10 namespace 0x20 parser 0x40 dispatcher
201 0x80 executer 0x100 resources 0x200 acpica debugger
202 0x400 os services 0x800 acpica disassembler.
203 The number can be in decimal or prefixed with 0x in hex.
204 Warning: Many of these options can produce a lot of
205 output and make your system unusable. Be very careful.
207 acpi.debug_level= [HW,ACPI]
209 Each bit of the <int> indicates an ACPI debug level,
210 1: enable, 0: disable. It is useful for boot time
211 debugging. After system has booted up, it can be set
212 via /sys/module/acpi/parameters/debug_level.
213 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
214 Available bits (add the numbers together) to enable different
215 debug output levels of the ACPI subsystem:
216 0x01 error 0x02 warn 0x04 init 0x08 debug object
217 0x10 info 0x20 init names 0x40 parse 0x80 load
218 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
219 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
220 0x10000 resources 0x20000 user requests 0x40000 package.
221 The number can be in decimal or prefixed with 0x in hex.
222 Warning: Many of these options can produce a lot of
223 output and make your system unusable. Be very careful.
225 acpi_pm_good [X86-32,X86-64]
226 Override the pmtimer bug detection: force the kernel
227 to assume that this machine's pmtimer latches its value
228 and always returns good values.
231 { off | try_unsupported }
232 off: disable AGP support
233 try_unsupported: try to drive unsupported chipsets
234 (may crash computer or cause data corruption)
236 enable_timer_pin_1 [i386,x86-64]
237 Enable PIN 1 of APIC timer
238 Can be useful to work around chipset bugs
239 (in particular on some ATI chipsets).
240 The kernel tries to set a reasonable default.
242 disable_timer_pin_1 [i386,x86-64]
243 Disable PIN 1 of APIC timer
244 Can be useful to work around chipset bugs.
247 Format: <io>,<irq>,<dma>,<dma2>,<type>
250 See header of drivers/scsi/advansys.c.
252 advwdt= [HW,WDT] Advantech WDT
253 Format: <iostart>,<iostop>
255 aedsp16= [HW,OSS] Audio Excel DSP 16
256 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
257 See also header of sound/oss/aedsp16.c.
260 See Documentation/scsi/aha152x.txt.
263 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
266 See Documentation/scsi/aic7xxx.txt.
269 See Documentation/scsi/aic79xx.txt.
271 amijoy.map= [HW,JOY] Amiga joystick support
272 Map of devices attached to JOY0DAT and JOY1DAT
274 See also Documentation/kernel/input/joystick.txt
276 analog.map= [HW,JOY] Analog joystick and gamepad support
277 Specifies type or capabilities of an analog joystick
278 connected to one of 16 gameports
279 Format: <type1>,<type2>,..<type16>
282 Power management functions (SPARCstation-4/5 + deriv.)
284 Disable APC CPU standby support. SPARCstation-Fox does
285 not play well with APC CPU idle - disable it if you have
286 APC and your system crashes randomly.
288 apic= [APIC,i386] Advanced Programmable Interrupt Controller
289 Change the output verbosity whilst booting
290 Format: { quiet (default) | verbose | debug }
291 Change the amount of debugging information output
292 when initialising the APIC and IO-APIC components.
294 apm= [APM] Advanced Power Management
295 See header of arch/i386/kernel/apm.c.
297 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
298 Format: <io>,<irq>,<nodeID>
302 atarimouse= [HW,MOUSE] Atari Mouse
304 atascsi= [HW,SCSI] Atari SCSI
306 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
307 EzKey and similar keyboards
309 atkbd.reset= [HW] Reset keyboard during initialization
311 atkbd.set= [HW] Select keyboard code set
312 Format: <int> (2 = AT (default), 3 = PS/2)
314 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
317 atkbd.softraw= [HW] Choose between synthetic and real raw mode
318 Format: <bool> (0 = real, 1 = synthetic (default))
320 atkbd.softrepeat= [HW]
321 Use software keyboard repeat
325 baycom_epp= [HW,AX25]
328 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
330 See header of drivers/net/hamradio/baycom_par.c.
332 baycom_ser_fdx= [HW,AX25]
333 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
334 Format: <io>,<irq>,<mode>[,<baud>]
335 See header of drivers/net/hamradio/baycom_ser_fdx.c.
337 baycom_ser_hdx= [HW,AX25]
338 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
339 Format: <io>,<irq>,<mode>
340 See header of drivers/net/hamradio/baycom_ser_hdx.c.
342 boot_delay= Milliseconds to delay each printk during boot.
343 Values larger than 10 seconds (10000) are changed to
347 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
348 bttv.radio= Most important insmod options are available as
350 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
351 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
354 See drivers/scsi/BusLogic.c, comment before function
355 BusLogic_ParseDriverOptions().
357 c101= [NET] Moxa C101 synchronous serial card
359 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
360 Sometimes CPU hardware bugs make them report the cache
361 size incorrectly. The kernel will attempt work arounds
362 to fix known problems, but for some CPUs it is not
363 possible to determine what the correct size should be.
364 This option provides an override for these situations.
367 [SECURITY] Disable capabilities. This would normally
368 be used only if an alternative security model is to be
369 configured. Potentially dangerous and should only be
370 used if you are entirely sure of the consequences.
372 chandev= [HW,NET] Generic channel device initialisation
374 checkreqprot [SELINUX] Set initial checkreqprot flag value.
375 Format: { "0" | "1" }
376 See security/selinux/Kconfig help text.
377 0 -- check protection applied by kernel (includes
378 any implied execute protection).
379 1 -- check protection requested by application.
380 Default value is set via a kernel config option.
381 Value can be changed at runtime via
382 /selinux/checkreqprot.
384 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
386 Forces specified clocksource (if available) to be used
387 when calculating gettimeofday(). If specified
388 clocksource is not available, it defaults to PIT.
389 Format: { pit | tsc | cyclone | pmtmr }
391 clocksource= [GENERIC_TIME] Override the default clocksource
393 Override the default clocksource and use the clocksource
394 with the name specified.
395 Some clocksource names to choose from, depending on
397 [all] jiffies (this is the base, fallback clocksource)
399 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
400 pxa_timer,timer3,32k_counter,timer0_1
402 [X86-32] pit,hpet,tsc,vmi-timer;
403 scx200_hrt on Geode; cyclone on IBM x440
411 code_bytes [IA32] How many bytes of object code to print in an
418 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
419 over the 8254 in addition to over the IO-APIC. The
420 kernel tries to set a sensible default.
422 hpet= [X86-32,HPET] option to control HPET usage
423 Format: { enable (default) | disable | force }
424 disable: disable HPET and use PIT instead
425 force: allow force enabled of undocumented chips (ICH4, VIA)
427 com20020= [HW,NET] ARCnet - COM20020 chipset
429 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
431 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
435 ARCnet - COM90xx chipset (memory-mapped buffers)
436 Format: <io>[,<irq>[,<memstart>]]
438 condev= [HW,S390] console device
441 console= [KNL] Output console device and options.
443 tty<n> Use the virtual console device <n>.
447 Use the specified serial port. The options are of
448 the form "bbbbpnf", where "bbbb" is the baud rate,
449 "p" is parity ("n", "o", or "e"), "n" is number of
450 bits, and "f" is flow control ("r" for RTS or
451 omit it). Default is "9600n8".
453 See Documentation/serial-console.txt for more
455 Documentation/networking/netconsole.txt for an
458 uart[8250],io,<addr>[,options]
459 uart[8250],mmio,<addr>[,options]
460 Start an early, polled-mode console on the 8250/16550
461 UART at the specified I/O port or MMIO address,
462 switching to the matching ttyS device later. The
463 options are the same as for ttyS, above.
465 earlycon= [KNL] Output early console device and options.
466 uart[8250],io,<addr>[,options]
467 uart[8250],mmio,<addr>[,options]
468 Start an early, polled-mode console on the 8250/16550
469 UART at the specified I/O port or MMIO address.
470 The options are the same as for ttyS, above.
473 [HW] Never suspend the console
474 Disable suspending of consoles during suspend and
475 hibernate operations. Once disabled, debugging
476 messages can reach various consoles while the rest
477 of the system is being put to sleep (ie, while
478 debugging driver suspend/resume hooks). This may
479 not work reliably with all consoles, but is known
480 to work with serial and VGA consoles.
482 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
484 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
486 crashkernel=nn[KMG]@ss[KMG]
487 [KNL] Reserve a chunk of physical memory to
488 hold a kernel to switch to with kexec on panic.
490 crashkernel=range1:size1[,range2:size2,...][@offset]
491 [KNL] Same as above, but depends on the memory
492 in the running system. The syntax of range is
493 start-[end] where start and end are both
494 a memory unit (amount[KMG]). See also
495 Documentation/kdump/kdump.txt for a example.
498 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
503 cs89x0_media= [HW,NET]
504 Format: { rj45 | aui | bnc }
507 See header of drivers/s390/block/dasd_devmap.c.
509 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
510 (one device per port)
511 Format: <port#>,<type>
512 See also Documentation/input/joystick-parport.txt
514 debug [KNL] Enable kernel debugging (events log level).
517 [KNL] verbose self-tests
519 Print debugging info while doing the locking API
521 We default to 0 (no extra messages), setting it to
522 1 will print _a lot_ more information - normally
523 only useful to kernel developers.
526 Format: <area>[,<node>]
527 See also Documentation/networking/decnet.txt.
530 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
531 Change the default blue palette of the console.
532 This is a 16-member array composed of values
536 Format: <green0>,<green1>,<green2>,...,<green15>
537 Change the default green palette of the console.
538 This is a 16-member array composed of values
542 Format: <red0>,<red1>,<red2>,...,<red15>
543 Change the default red palette of the console.
544 This is a 16-member array composed of values
549 Set system-wide default UTF-8 mode for all tty's.
550 Default is 0 and by setting to 1, it enables UTF-8
551 mode for all newly opened or allocated terminals.
554 Set number of hash buckets for dentry cache.
557 IO parameters + enable/disable command.
559 digiepca= [HW,SERIAL]
560 See drivers/char/README.epca and
561 Documentation/digiepca.txt.
563 dmasound= [HW,OSS] Sound subsystem buffers
569 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
571 earlyprintk=serial[,ttySn[,baudrate]]
573 Append ",keep" to not disable it when the real console
576 Only vga or serial at a time, not both.
578 Currently only ttyS0 and ttyS1 are supported.
580 Interaction with the standard serial driver is not
583 The VGA output is eventually overwritten by the real
588 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
591 non-0: interrupt mode (default)
594 Format: {"of[f]" | "sk[ipmbr]"}
595 See comment in arch/i386/boot/edd.S
597 eisa_irq_edge= [PARISC,HW]
598 See header of drivers/parisc/eisa.c.
601 See comment before function elanfreq_setup() in
602 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
605 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
606 See Documentation/block/as-iosched.txt and
607 Documentation/block/deadline-iosched.txt for details.
609 elfcorehdr= [X86-32, X86_64]
610 Specifies physical address of start of kernel core
611 image elf header. Generally kexec loader will
612 pass this option to capture kernel.
613 See Documentation/kdump/kdump.txt for details.
615 enforcing [SELINUX] Set initial enforcing status.
617 See security/selinux/Kconfig help text.
618 0 -- permissive (log only, no denials).
619 1 -- enforcing (deny and log).
621 Value can be changed at runtime via /selinux/enforce.
624 Format: <spdif>,[<nomix>,[<amplifier>]]
625 See also header of sound/oss/es1371.c.
627 ether= [HW,NET] Ethernet cards parameters
628 This option is obsoleted by the "netdev=" option, which
629 has equivalent usage. See its documentation for details.
631 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
636 fail_make_request=[KNL]
637 General fault injection mechanism.
638 Format: <interval>,<probability>,<space>,<times>
639 See also /Documentation/fault-injection/.
642 See header of drivers/scsi/fd_mcs.c.
645 See header of drivers/scsi/fdomain.c.
648 See Documentation/floppy.txt.
651 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
652 support via parallel port (up to 5 devices per port)
653 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
654 See also Documentation/input/joystick-parport.txt
659 See header of drivers/scsi/gdth.c.
661 gpt [EFI] Forces disk with valid GPT signature but
662 invalid Protective MBR to be treated as GPT.
666 hashdist= [KNL,NUMA] Large hashes allocated during boot
667 are distributed across NUMA nodes. Defaults on
668 for IA-64, off otherwise.
669 Format: 0 | 1 (for off | on)
671 hcl= [IA-64] SGI's Hardware Graph compatibility layer
673 hd= [EIDE] (E)IDE hard drive subsystem geometry
674 Format: <cyl>,<head>,<sect>
676 hd?= [HW] (E)IDE subsystem
677 hd?lun= See Documentation/ide.txt.
679 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
680 size of <nn>. This works even on boxes that have no
681 highmem otherwise. This also works to reduce highmem
682 size on bigger boxes.
684 highres= [KNL] Enable/disable high resolution timer mode.
685 Valid parameters: "on", "off"
689 See Documentation/isdn/README.HiSax.
691 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
693 i8042.direct [HW] Put keyboard port into non-translated mode
694 i8042.dumbkbd [HW] Pretend that controller can only read data from
695 keyboard and cannot control its state
696 (Don't attempt to blink the leds)
697 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
698 i8042.nokbd [HW] Don't check/create keyboard port
699 i8042.nomux [HW] Don't check presence of an active multiplexing
701 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
704 [HW] Frequency with which keyboard LEDs should blink
705 when kernel panics (default is 0.5 sec)
706 i8042.reset [HW] Reset the controller during init and cleanup
707 i8042.unlock [HW] Unlock (ignore) the keylock
711 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
712 indicates that the driver is running on unsupported
714 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
715 does not match list of supported models.
717 [HW] Report power status in /proc/i8k
718 (disabled by default)
719 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
722 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
723 See Documentation/mca.txt.
726 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
728 ide= [HW] (E)IDE subsystem
729 Format: ide=nodma or ide=doubler or ide=reverse
730 See Documentation/ide.txt.
732 ide?= [HW] (E)IDE subsystem
733 Format: ide?=noprobe or chipset specific parameters.
734 See Documentation/ide.txt.
736 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
737 See Documentation/ide.txt.
740 Format: idle=poll or idle=mwait
741 Poll forces a polling idle loop that can slightly improves the performance
742 of waking up a idle CPU, but will use a lot of power and make the system
743 run hot. Not recommended.
744 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
745 to not use it because it doesn't save as much power as a normal idle
746 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
749 ignore_loglevel [KNL]
750 Ignore loglevel setting - this will print /all/
751 kernel messages to the console. Useful for debugging.
754 Set number of hash buckets for inode cache.
757 See header of drivers/scsi/in2000.c.
761 Run specified binary instead of /sbin/init as init
764 initcall_debug [KNL] Trace initcalls as they are executed. Useful
765 for working out where the kernel is dying during
768 initrd= [BOOT] Specify the location of the initial ramdisk
770 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
775 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
777 Disable intel iommu driver.
778 igfx_off [Default Off]
779 By default, gfx is mapped as normal device. If a gfx
780 device has a dedicated DMAR unit, the DMAR unit is
781 bypassed by not enabling DMAR with this option. In
782 this case, gfx device will use physical address for
785 io7= [HW] IO7 for Marvel based alpha systems
786 See comment before marvel_specify_io7 in
787 arch/alpha/kernel/core_marvel.c.
790 See Documentation/nfsroot.txt.
792 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
793 See comment before ip2_setup() in
794 drivers/char/ip2/ip2base.c.
796 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
797 See header of drivers/scsi/ips.c.
799 ports= [IP_VS_FTP] IPVS ftp helper module
801 Up to 8 (IP_VS_APP_MAX_PORTS) ports
803 Format: <port>,<port>....
806 When an interrupt is not handled search all handlers
807 for it. Intended to get systems with badly broken
811 When an interrupt is not handled search all handlers
812 for it. Also check all handlers each timer
813 interrupt. Intended to get systems with badly broken
817 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
819 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
821 <cpu number>,...,<cpu number>
823 <cpu number>-<cpu number> (must be a positive range in ascending order)
825 <cpu number>,...,<cpu number>-<cpu number>
826 This option can be used to specify one or more CPUs
827 to isolate from the general SMP balancing and scheduling
828 algorithms. The only way to move a process onto or off
829 an "isolated" CPU is via the CPU affinity syscalls.
830 <cpu number> begins at 0 and the maximum value is
831 "number of CPUs in system - 1".
833 This option is the preferred way to isolate CPUs. The
834 alternative -- manually setting the CPU mask of all
835 tasks in the system -- can cause problems and
836 suboptimal load balancer performance.
840 js= [HW,JOY] Analog joystick
841 See Documentation/input/joystick.txt.
843 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
844 specifies the amount of memory usable by the kernel
845 for non-movable allocations. The requested amount is
846 spread evenly throughout all nodes in the system. The
847 remaining memory in each node is used for Movable
848 pages. In the event, a node is too small to have both
849 kernelcore and Movable pages, kernelcore pages will
850 take priority and other nodes will have a larger number
851 of kernelcore pages. The Movable zone is used for the
852 allocation of pages that may be reclaimed or moved
853 by the page migration subsystem. This means that
854 HugeTLB pages may not be allocated from this zone.
855 Note that allocations like PTEs-from-HighMem still
856 use the HighMem zone if it exists, and the Normal
859 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
860 is similar to kernelcore except it specifies the
861 amount of memory used for migratable allocations.
862 If both kernelcore and movablecore is specified,
863 then kernelcore will be at *least* the specified
864 value but may be more. If movablecore on its own
865 is specified, the administrator must be careful
866 that the amount of memory usable for all allocations
871 kstack=N [X86-32,X86-64] Print N words from the kernel stack
876 lapic [X86-32,APIC] Enable the local APIC even if BIOS
879 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
882 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
886 load_ramdisk= [RAM] List of ramdisks to load from floppy
887 See Documentation/ramdisk.txt.
889 lockd.nlm_grace_period=P [NFS] Assign grace period.
892 lockd.nlm_tcpport=N [NFS] Assign TCP port.
895 lockd.nlm_timeout=T [NFS] Assign timeout value.
898 lockd.nlm_udpport=M [NFS] Assign UDP port.
901 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
904 loglevel= All Kernel Messages with a loglevel smaller than the
905 console loglevel will be printed to the console. It can
906 also be changed with klogd or other programs. The
907 loglevels are defined as follows:
909 0 (KERN_EMERG) system is unusable
910 1 (KERN_ALERT) action must be taken immediately
911 2 (KERN_CRIT) critical conditions
912 3 (KERN_ERR) error conditions
913 4 (KERN_WARNING) warning conditions
914 5 (KERN_NOTICE) normal but significant condition
915 6 (KERN_INFO) informational
916 7 (KERN_DEBUG) debug-level messages
918 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
919 Format: { n | nk | nM }
920 n must be a power of two. The default size
921 is set in the kernel config file.
923 logo.nologo [FB] Disables display of the built-in Linux logo.
924 This may be used to provide more screen space for
925 kernel log messages and is useful when debugging
926 kernel boot problems.
928 lp=0 [LP] Specify parallel ports to use, e.g,
929 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
930 lp=reset first parallel port). 'lp=0' disables the
931 lp=auto printer driver. 'lp=reset' (which can be
932 specified in addition to the ports) causes
933 attached printers to be reset. Using
934 lp=port1,port2,... specifies the parallel ports
935 to associate lp devices with, starting with
936 lp0. A port specification may be 'none' to skip
937 that lp device, or a parport name such as
938 'parport0'. Specifying 'lp=auto' instead of a
939 port specification list means that device IDs
940 from each port should be examined, to see if
941 an IEEE 1284-compliant printer is attached; if
942 so, the driver will manage that printer.
943 See also header of drivers/char/lp.c.
946 Sets loops_per_jiffy to given constant, thus avoiding
947 time-consuming boot-time autodetection (up to 250 ms per
948 CPU). 0 enables autodetection (default). To determine
949 the correct value for your kernel, boot with normal
950 autodetection and see what value is printed. Note that
951 on SMP systems the preset will be applied to all CPUs,
952 which is likely to cause problems if your CPUs need
953 significantly divergent settings. An incorrect value
954 will cause delays in the kernel to be wrong, leading to
955 unpredictable I/O errors and other breakage. Although
956 unlikely, in the extreme case this might damage your
960 Format: <io>,<irq>,<dma>
962 mac5380= [HW,SCSI] Format:
963 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
965 mac53c9x= [HW,SCSI] Format:
966 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
968 machvec= [IA64] Force the use of a particular machine-vector
969 (machvec) in a generic kernel.
970 Example: machvec=hpzx1_swiotlb
972 max_loop= [LOOP] Maximum number of loopback devices that can
976 maxcpus= [SMP] Maximum number of processors that an SMP kernel
977 should make use of. maxcpus=n : n >= 0 limits the
978 kernel to using 'n' processors. n=0 is a special case,
979 it is equivalent to "nosmp", which also disables
982 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
983 equal to this physical address is ignored.
985 max_luns= [SCSI] Maximum number of LUNs to probe.
986 Should be between 1 and 2^32-1.
989 [SCSI] Maximum number of LUNs received.
990 Should be between 1 and 16384.
992 mca-pentium [BUGS=X86-32]
996 mce [X86-32] Machine Check Exception
998 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1000 md= [HW] RAID subsystems devices and level
1001 See Documentation/md.txt.
1004 Format: <first>,<last>
1005 Specifies range of consoles to be captured by the MDA.
1007 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1008 Amount of memory to be used when the kernel is not able
1009 to see the whole system memory or for test.
1010 [X86-32] Use together with memmap= to avoid physical
1011 address space collisions. Without memmap= PCI devices
1012 could be placed at addresses belonging to unused RAM.
1014 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1017 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1018 E820 memory map, as specified by the user.
1019 Such memmap=exactmap lines can be constructed based on
1020 BIOS output or other requirements. See the memmap=nn@ss
1023 memmap=nn[KMG]@ss[KMG]
1024 [KNL] Force usage of a specific region of memory
1025 Region of memory to be used, from ss to ss+nn.
1027 memmap=nn[KMG]#ss[KMG]
1028 [KNL,ACPI] Mark specific memory as ACPI data.
1029 Region of memory to be used, from ss to ss+nn.
1031 memmap=nn[KMG]$ss[KMG]
1032 [KNL,ACPI] Mark specific memory as reserved.
1033 Region of memory to be used, from ss to ss+nn.
1035 meye.*= [HW] Set MotionEye Camera parameters
1036 See Documentation/video4linux/meye.txt.
1038 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1039 Multi-Function General Purpose Timers on AMD Geode
1045 [MOUSE] Maximum time between finger touching and
1046 leaving touchpad surface for touch to be considered
1047 a tap and be reported as a left button click (for
1048 touchpads working in absolute mode only).
1050 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1051 reporting absolute coordinates, such as tablets
1052 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1053 reporting absolute coordinates, such as tablets
1058 MTD_Partition= [MTD]
1059 Format: <name>,<region-number>,<size>,<offset>
1061 MTD_Region= [MTD] Format:
1062 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1065 See drivers/mtd/cmdlinepart.c.
1067 mtouchusb.raw_coordinates=
1068 [HW] Make the MicroTouch USB driver use raw coordinates
1069 ('y', default) or cooked coordinates ('n')
1071 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1074 See header of drivers/scsi/NCR_D700.c.
1078 ncr53c400= [HW,SCSI]
1080 ncr53c400a= [HW,SCSI]
1082 ncr53c406a= [HW,SCSI]
1084 ncr53c8xx= [HW,SCSI]
1086 netdev= [NET] Network devices parameters
1087 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1088 Note that mem_start is often overloaded to mean
1089 something different and driver-specific.
1090 This usage is only documented in each driver source
1094 See Documentation/nfsroot.txt.
1096 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1097 See Documentation/nfsroot.txt.
1099 nfs.callback_tcpport=
1100 [NFS] set the TCP port on which the NFSv4 callback
1101 channel should listen.
1103 nfs.idmap_cache_timeout=
1104 [NFS] set the maximum lifetime for idmapper cache
1108 [NFS] enable 64-bit inode numbers.
1109 If zero, the NFS client will fake up a 32-bit inode
1110 number for the readdir() and stat() syscalls instead
1111 of returning the full 64-bit number.
1112 The default is to return 64-bit inode numbers.
1114 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1116 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1117 emulation library even if a 387 maths coprocessor
1120 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1121 caches in the slab allocator. Saves per-node memory,
1122 but will impact performance.
1126 noapic [SMP,APIC] Tells the kernel to not make use of any
1127 IOAPICs that may be present in the system.
1129 nobats [PPC] Do not use BATs for mapping kernel lowmem
1130 on "Classic" PPC cores.
1134 nodelayacct [KNL] Disable per-task delay accounting
1136 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1140 noexec [X86-32,X86-64]
1141 noexec=on: enable non-executable mappings (default)
1142 noexec=off: disable nn-executable mappings
1144 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1145 register save and restore. The kernel will only save
1146 legacy floating-point registers on task switch.
1150 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1151 instruction doesn't work correctly and not to
1154 nohalt [IA-64] Tells the kernel not to use the power saving
1155 function PAL_HALT_LIGHT when idle. This increases
1156 power-consumption. On the positive side, it reduces
1157 interrupt wake-up latency, which may improve performance
1158 in certain environments such as networked servers or
1161 nohz= [KNL] Boottime enable/disable dynamic ticks
1162 Valid arguments: on, off
1165 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1167 noirqdebug [X86-32] Disables the code which attempts to detect and
1168 disable unhandled interrupt sources.
1170 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1171 broken timer IRQ sources.
1173 noisapnp [ISAPNP] Disables ISA PnP code.
1175 noinitrd [RAM] Tells the kernel not to load any configured
1180 nojitter [IA64] Disables jitter checking for ITC timers.
1182 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1184 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1186 noltlbs [PPC] Do not use large page/tlb entries for kernel
1187 lowmem mapping on PPC40x.
1189 nomca [IA-64] Disable machine check abort handling
1191 nomce [X86-32] Machine Check Exception
1193 nomfgpt [X86-32] Disable Multi-Function General Purpose
1194 Timer usage (for AMD Geode machines).
1196 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1198 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1199 with UP alternatives
1201 noresidual [PPC] Don't use residual data on PReP machines.
1203 noresume [SWSUSP] Disables resume and restores original swap
1206 no-scroll [VGA] Disables scrollback.
1207 This is required for the Braillex ib80-piezo Braille
1208 reader made by F.H. Papenmeier (Germany).
1212 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1214 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1215 and disable the IO APIC. legacy for "maxcpus=0".
1217 nosoftlockup [KNL] Disable the soft-lockup detector.
1219 nosync [HW,M68K] Disables sync negotiation for all devices.
1221 notsc [BUGS=X86-32] Disable Time Stamp Counter
1223 nousb [USB] Disable the USB subsystem
1227 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1228 one of ['zone', 'node', 'default'] can be specified
1229 This can be set from sysctl after boot.
1230 See Documentation/sysctl/vm.txt for details.
1232 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1237 oprofile.timer= [HW]
1238 Use timer interrupt instead of performance counters
1240 osst= [HW,SCSI] SCSI Tape Driver
1241 Format: <buffer_size>,<write_threshold>
1242 See also Documentation/scsi/st.txt.
1244 panic= [KNL] Kernel behaviour on panic
1247 parkbd.port= [HW] Parallel port number the keyboard adapter is
1248 connected to, default is 0.
1250 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1251 0 for XT, 1 for AT (default is AT).
1254 parport= [HW,PPT] Specify parallel ports. 0 disables.
1255 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1256 Use 'auto' to force the driver to use any
1257 IRQ/DMA settings detected (the default is to
1258 ignore detected IRQ/DMA settings because of
1259 possible conflicts). You can specify the base
1260 address, IRQ, and DMA settings; IRQ and DMA
1261 should be numbers, or 'auto' (for using detected
1262 settings on that particular port), or 'nofifo'
1263 (to avoid using a FIFO even if it is detected).
1264 Parallel ports are assigned in the order they
1265 are specified on the command line, starting
1268 parport_init_mode= [HW,PPT]
1269 Configure VIA parallel port to operate in
1270 a specific mode. This is necessary on Pegasos
1271 computer where firmware has no options for setting
1272 up parallel port mode and sets it to spp.
1273 Currently this function knows 686a and 8231 chips.
1274 Format: [spp|ps2|epp|ecp|ecpepp]
1276 pas2= [HW,OSS] Format:
1277 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1280 See header of drivers/scsi/pas16.c.
1283 Halt all CPUs after the first oops has been printed for
1284 the specified number of seconds. This is to be used if
1285 your oopses keep scrolling off the screen.
1290 See header of drivers/block/paride/pcd.c.
1291 See also Documentation/paride.txt.
1293 pci=option[,option...] [PCI] various PCI subsystem options:
1294 off [X86-32] don't probe for the PCI bus
1295 bios [X86-32] force use of PCI BIOS, don't access
1296 the hardware directly. Use this if your machine
1297 has a non-standard PCI host bridge.
1298 nobios [X86-32] disallow use of PCI BIOS, only direct
1299 hardware access methods are allowed. Use this
1300 if you experience crashes upon bootup and you
1301 suspect they are caused by the BIOS.
1302 conf1 [X86-32] Force use of PCI Configuration
1304 conf2 [X86-32] Force use of PCI Configuration
1306 noaer [PCIE] If the PCIEAER kernel config parameter is
1307 enabled, this kernel boot option can be used to
1308 disable the use of PCIE advanced error reporting.
1309 nodomains [PCI] Disable support for multiple PCI
1310 root domains (aka PCI segments, in ACPI-speak).
1311 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1313 nomsi [MSI] If the PCI_MSI kernel config parameter is
1314 enabled, this kernel boot option can be used to
1315 disable the use of MSI interrupts system-wide.
1316 nosort [X86-32] Don't sort PCI devices according to
1317 order given by the PCI BIOS. This sorting is
1318 done to get a device order compatible with
1320 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1321 routing table. These calls are known to be buggy
1322 on several machines and they hang the machine
1323 when used, but on other computers it's the only
1324 way to get the interrupt routing table. Try
1325 this option if the kernel is unable to allocate
1326 IRQs or discover secondary PCI buses on your
1328 rom [X86-32] Assign address space to expansion ROMs.
1329 Use with caution as certain devices share
1330 address decoders between ROMs and other
1332 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1333 assigned automatically to PCI devices. You can
1334 make the kernel exclude IRQs of your ISA cards
1336 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1337 of the PIRQ table (normally generated
1338 by the BIOS) if it is outside the
1339 F0000h-100000h range.
1340 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1341 useful if the kernel is unable to find your
1342 secondary buses and you want to tell it
1343 explicitly which ones they are.
1344 assign-busses [X86-32] Always assign all PCI bus
1345 numbers ourselves, overriding
1346 whatever the firmware may have done.
1347 usepirqmask [X86-32] Honor the possible IRQ mask stored
1348 in the BIOS $PIR table. This is needed on
1349 some systems with broken BIOSes, notably
1350 some HP Pavilion N5400 and Omnibook XE3
1351 notebooks. This will have no effect if ACPI
1352 IRQ routing is enabled.
1353 noacpi [X86-32] Do not use ACPI for IRQ routing
1354 or for PCI scanning.
1355 use_crs [X86-32] Use _CRS for PCI resource
1357 routeirq Do IRQ routing for all PCI devices.
1358 This is normally done in pci_enable_device(),
1359 so this option is a temporary workaround
1360 for broken drivers that don't call it.
1361 firmware [ARM] Do not re-enumerate the bus but instead
1362 just use the configuration from the
1363 bootloader. This is currently used on
1364 IXP2000 systems where the bus has to be
1365 configured a certain way for adjunct CPUs.
1366 noearly [X86] Don't do any early type 1 scanning.
1367 This might help on some broken boards which
1368 machine check when some devices' config space
1369 is read. But various workarounds are disabled
1370 and some IOMMU drivers will not work.
1371 bfsort Sort PCI devices into breadth-first order.
1372 This sorting is done to get a device
1373 order compatible with older (<= 2.4) kernels.
1374 nobfsort Don't sort PCI devices into breadth-first order.
1375 cbiosize=nn[KMG] The fixed amount of bus space which is
1376 reserved for the CardBus bridge's IO window.
1377 The default value is 256 bytes.
1378 cbmemsize=nn[KMG] The fixed amount of bus space which is
1379 reserved for the CardBus bridge's memory
1380 window. The default value is 64 megabytes.
1382 pcmv= [HW,PCMCIA] BadgePAD 4
1385 See Documentation/paride.txt.
1387 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1390 See arch/parisc/kernel/pdc_chassis.c
1393 See Documentation/paride.txt.
1396 See Documentation/paride.txt.
1398 pirq= [SMP,APIC] Manual mp-table setup
1399 See Documentation/i386/IO-APIC.txt.
1401 plip= [PPT,NET] Parallel port network link
1402 Format: { parport<nr> | timid | 0 }
1403 See also Documentation/parport.txt.
1409 { on | off | curr | res | no-curr | no-res }
1412 [ISAPNP] Exclude IRQs for the autoconfiguration
1415 [ISAPNP] Exclude DMAs for the autoconfiguration
1417 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1418 Ranges are in pairs (I/O port base and size).
1421 [ISAPNP] Exclude memory regions for the
1423 Ranges are in pairs (memory base and size).
1425 print-fatal-signals=
1426 [KNL] debug: print fatal signals
1427 print-fatal-signals=1: print segfault info to
1431 printk.time= Show timing data prefixed to each printk message line
1432 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1434 profile= [KNL] Enable kernel profiling via /proc/profile
1435 Format: [schedule,]<number>
1436 Param: "schedule" - profile schedule points.
1437 Param: <number> - step/bucket size as a power of 2 for
1438 statistical time based profiling.
1439 Param: "sleep" - profile D-state sleeping (millisecs)
1440 Param: "kvm" - profile VM exits.
1442 processor.max_cstate= [HW,ACPI]
1443 Limit processor to maximum C-state
1444 max_cstate=9 overrides any DMI blacklist limit.
1446 processor.nocst [HW,ACPI]
1447 Ignore the _CST method to determine C-states,
1448 instead using the legacy FADT method
1450 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1452 See Documentation/ramdisk.txt.
1454 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1455 probe for; one of (bare|imps|exps|lifebook|any).
1456 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1458 psmouse.resetafter= [HW,MOUSE]
1459 Try to reset the device after so many bad packets
1462 [HW,MOUSE] Set desired mouse resolution, in dpi.
1463 psmouse.smartscroll=
1464 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1465 0 = disabled, 1 = enabled (default).
1467 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1469 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1472 See Documentation/paride.txt.
1475 [KNL] Number of legacy pty's. Overwrites compiled-in
1478 quiet [KNL] Disable most log messages
1483 See Documentation/md.txt.
1485 ramdisk_blocksize= [RAM]
1486 See Documentation/ramdisk.txt.
1488 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1489 See Documentation/ramdisk.txt.
1491 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1492 RCU callbacks to process in one batch.
1494 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1495 RCU callbacks over which batch limiting is disabled.
1497 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1498 RCU callbacks below which batch limiting is re-enabled.
1502 Run specified binary instead of /init from the ramdisk,
1503 used for early userspace startup. See initrd.
1505 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1506 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1507 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1509 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1511 reservetop= [X86-32]
1513 Reserves a hole at the top of the kernel virtual
1516 reset_devices [KNL] Force drivers to reset the underlying device
1517 during initialization.
1520 Specify the partition device for software suspend
1522 resume_offset= [SWSUSP]
1523 Specify the offset from the beginning of the partition
1524 given by "resume=" at which the swap header is located,
1525 in <PAGE_SIZE> units (needed only for swap files).
1526 See Documentation/power/swsusp-and-swap-files.txt
1528 retain_initrd [RAM] Keep initrd memory after extraction
1530 rhash_entries= [KNL,NET]
1531 Set number of hash buckets for route cache
1533 riscom8= [HW,SERIAL]
1534 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1536 ro [KNL] Mount root device read-only on boot
1538 root= [KNL] Root filesystem
1540 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1541 mount the root filesystem
1543 rootflags= [KNL] Set root filesystem mount option string
1545 rootfstype= [KNL] Set root filesystem type
1547 rootwait [KNL] Wait (indefinitely) for root device to show up.
1548 Useful for devices that are detected asynchronously
1549 (e.g. USB and MMC devices).
1551 root_plug.vendor_id=
1552 [ROOTPLUG] Override the default vendor ID
1554 root_plug.product_id=
1555 [ROOTPLUG] Override the default product ID
1558 [ROOTPLUG] Enable debugging output
1560 rw [KNL] Mount root device read-write on boot
1562 S [KNL] Run init in single mode
1565 See drivers/net/irda/sa1100_ir.c.
1567 sbni= [NET] Granch SBNI12 leased line adapter
1569 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1570 Format: <io>[,<timeout>[,<isapnp>]]
1572 scsi_debug_*= [SCSI]
1573 See drivers/scsi/scsi_debug.c.
1575 scsi_default_dev_flags=
1576 [SCSI] SCSI default device flags
1579 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1580 Format: <vendor>:<model>:<flags>
1581 (flags are integer value)
1583 scsi_logging= [SCSI]
1585 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1586 discovered. async scans them in kernel threads,
1587 allowing boot to proceed. none ignores them, expecting
1588 user space to do the scan.
1590 selinux [SELINUX] Disable or enable SELinux at boot time.
1591 Format: { "0" | "1" }
1592 See security/selinux/Kconfig help text.
1595 Default value is set via kernel config option.
1596 If enabled at boot time, /selinux/disable can be used
1597 later to disable prior to initial policy load.
1599 selinux_compat_net =
1600 [SELINUX] Set initial selinux_compat_net flag value.
1601 Format: { "0" | "1" }
1602 0 -- use new secmark-based packet controls
1603 1 -- use legacy packet controls
1604 Default value is 0 (preferred).
1605 Value can be changed at runtime via
1606 /selinux/compat_net.
1608 serialnumber [BUGS=X86-32]
1611 Maximal number of shapers.
1614 See header of drivers/scsi/sim710.c.
1621 slub_debug[=options[,slabs]] [MM, SLUB]
1622 Enabling slub_debug allows one to determine the
1623 culprit if slab objects become corrupted. Enabling
1624 slub_debug can create guard zones around objects and
1625 may poison objects when not in use. Also tracks the
1626 last alloc / free. For more information see
1627 Documentation/vm/slub.txt.
1629 slub_max_order= [MM, SLUB]
1630 Determines the maximum allowed order for slabs.
1631 A high setting may cause OOMs due to memory
1632 fragmentation. For more information see
1633 Documentation/vm/slub.txt.
1635 slub_min_objects= [MM, SLUB]
1636 The minimum number of objects per slab. SLUB will
1637 increase the slab order up to slub_max_order to
1638 generate a sufficiently large slab able to contain
1639 the number of objects indicated. The higher the number
1640 of objects the smaller the overhead of tracking slabs
1641 and the less frequently locks need to be acquired.
1642 For more information see Documentation/vm/slub.txt.
1644 slub_min_order= [MM, SLUB]
1645 Determines the mininum page order for slabs. Must be
1646 lower than slub_max_order.
1647 For more information see Documentation/vm/slub.txt.
1649 slub_nomerge [MM, SLUB]
1650 Disable merging of slabs with similar size. May be
1651 necessary if there is some reason to distinguish
1652 allocs to different slabs. Debug options disable
1653 merging on their own.
1654 For more information see Documentation/vm/slub.txt.
1657 Format: <io1>[,<io2>[,...,<io8>]]
1659 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1660 attempt to substitute SMP alternatives once at boot.
1662 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1663 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1664 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1665 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1666 smsc-ircc2.ircc_irq= [HW] IRQ line
1667 smsc-ircc2.ircc_dma= [HW] DMA channel
1668 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1669 0: Toshiba Satellite 1800 (GP data pin select)
1670 1: Fast pin select (default)
1673 snd-ad1816a= [HW,ALSA]
1675 snd-ad1848= [HW,ALSA]
1677 snd-ali5451= [HW,ALSA]
1679 snd-als100= [HW,ALSA]
1681 snd-als4000= [HW,ALSA]
1683 snd-azt2320= [HW,ALSA]
1685 snd-cmi8330= [HW,ALSA]
1687 snd-cmipci= [HW,ALSA]
1689 snd-cs4231= [HW,ALSA]
1691 snd-cs4232= [HW,ALSA]
1693 snd-cs4236= [HW,ALSA]
1695 snd-cs4281= [HW,ALSA]
1697 snd-cs46xx= [HW,ALSA]
1699 snd-dt019x= [HW,ALSA]
1701 snd-dummy= [HW,ALSA]
1703 snd-emu10k1= [HW,ALSA]
1705 snd-ens1370= [HW,ALSA]
1707 snd-ens1371= [HW,ALSA]
1709 snd-es968= [HW,ALSA]
1711 snd-es1688= [HW,ALSA]
1713 snd-es18xx= [HW,ALSA]
1715 snd-es1938= [HW,ALSA]
1717 snd-es1968= [HW,ALSA]
1719 snd-fm801= [HW,ALSA]
1721 snd-gusclassic= [HW,ALSA]
1723 snd-gusextreme= [HW,ALSA]
1725 snd-gusmax= [HW,ALSA]
1729 snd-ice1712= [HW,ALSA]
1731 snd-intel8x0= [HW,ALSA]
1733 snd-interwave= [HW,ALSA]
1738 snd-korg1212= [HW,ALSA]
1740 snd-maestro3= [HW,ALSA]
1742 snd-mpu401= [HW,ALSA]
1744 snd-mtpav= [HW,ALSA]
1746 snd-nm256= [HW,ALSA]
1748 snd-opl3sa2= [HW,ALSA]
1756 snd-opti93x= [HW,ALSA]
1760 snd-rme32= [HW,ALSA]
1762 snd-rme96= [HW,ALSA]
1764 snd-rme9652= [HW,ALSA]
1770 snd-sbawe= [HW,ALSA]
1772 snd-serial= [HW,ALSA]
1774 snd-sgalaxy= [HW,ALSA]
1776 snd-sonicvibes= [HW,ALSA]
1781 snd-sun-cs4231= [HW,ALSA]
1783 snd-trident= [HW,ALSA]
1785 snd-usb-audio= [HW,ALSA,USB]
1787 snd-via82xx= [HW,ALSA]
1789 snd-virmidi= [HW,ALSA]
1791 snd-wavefront= [HW,ALSA]
1793 snd-ymfpci= [HW,ALSA]
1795 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1796 See Documentation/sonypi.txt
1798 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1799 See Documentation/specialix.txt.
1801 spia_io_base= [HW,MTD]
1807 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1809 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1810 See Documentation/scsi/st.txt.
1813 See header of drivers/scsi/seagate.c.
1817 Set the STI (builtin display/keyboard on the HP-PARISC
1818 machines) console (graphic card) which should be used
1819 as the initial boot-console.
1820 See also comment in drivers/video/console/sticore.c.
1823 See comment in drivers/video/console/sticore.c.
1826 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1830 Control how the NFS server code allocates CPUs to
1831 service thread pools. Depending on how many NICs
1832 you have and where their interrupts are bound, this
1833 option will affect which CPUs will do NFS serving.
1834 Note: this parameter cannot be changed while the
1835 NFS server is running.
1837 auto the server chooses an appropriate mode
1838 automatically using heuristics
1839 global a single global pool contains all CPUs
1840 percpu one pool for each CPU
1841 pernode one pool for each NUMA node (equivalent
1842 to global on non-NUMA machines)
1844 swiotlb= [IA-64] Number of I/O TLB slabs
1848 sym53c416= [HW,SCSI]
1849 See header of drivers/scsi/sym53c416.c.
1851 sysrq_always_enabled
1853 Ignore sysrq setting - this boot parameter will
1854 neutralize any effect of /proc/sys/kernel/sysrq.
1855 Useful for debugging.
1858 See header of drivers/scsi/t128.c.
1862 thash_entries= [KNL,NET]
1863 Set number of hash buckets for TCP connection
1865 thermal.act= [HW,ACPI]
1866 -1: disable all active trip points in all thermal zones
1867 <degrees C>: override all lowest active trip points
1869 thermal.crt= [HW,ACPI]
1870 -1: disable all critical trip points in all thermal zones
1871 <degrees C>: lower all critical trip points
1873 thermal.nocrt= [HW,ACPI]
1874 Set to disable actions on ACPI thermal zone
1875 critical and hot trip points.
1877 thermal.off= [HW,ACPI]
1878 1: disable ACPI thermal control
1880 thermal.psv= [HW,ACPI]
1881 -1: disable all passive trip points
1882 <degrees C>: override all passive trip points to this value
1884 thermal.tzp= [HW,ACPI]
1885 Specify global default ACPI thermal zone polling rate
1886 <deci-seconds>: poll all this frequency
1887 0: no polling (default)
1889 time Show timing data prefixed to each printk message line
1890 [deprecated, see 'printk.time']
1892 tipar.timeout= [HW,PPT]
1893 Set communications timeout in tenths of a second
1896 tipar.delay= [HW,PPT]
1897 Set inter-bit delay in microseconds (default 10).
1900 See header of drivers/scsi/seagate.c.
1903 See comment before function dc390_setup() in
1904 drivers/scsi/tmscsim.c.
1908 trix= [HW,OSS] MediaTrix AudioTrix Pro
1910 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1912 turbografx.map[2|3]= [HW,JOY]
1913 TurboGraFX parallel port interface
1915 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1916 See also Documentation/input/joystick-parport.txt
1918 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1919 See header of drivers/scsi/u14-34f.c.
1928 [USB] Ignore overcurrent events (default N).
1929 Some badly-designed motherboards generate lots of
1930 bogus events, for ports that aren't wired to
1931 anything. Set this parameter to avoid log spamming.
1932 Note that genuine overcurrent events won't be
1935 usbcore.autosuspend=
1936 [USB] The autosuspend time delay (in seconds) used
1937 for newly-detected USB devices (default 2). This
1938 is the time required before an idle device will be
1939 autosuspended. Devices for which the delay is set
1940 to a negative value won't be autosuspended at all.
1943 [USBHID] The interval which mice are to be polled at.
1945 vdso= [X86-32,SH,x86-64]
1946 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1947 vdso=1: enable VDSO (default)
1948 vdso=0: disable VDSO mapping
1951 vector=percpu: enable percpu vector domain
1953 video= [FB] Frame buffer configuration
1954 See Documentation/fb/modedb.txt.
1956 vga= [BOOT,X86-32] Select a particular video mode
1957 See Documentation/i386/boot.txt and
1958 Documentation/svga.txt.
1959 Use vga=ask for menu.
1960 This is actually a boot loader parameter; the value is
1961 passed to the kernel using a special protocol.
1963 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1964 size of <nn>. This can be used to increase the
1965 minimum size (128MB on x86). It can also be used to
1966 decrease the size and leave more room for directly
1969 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1972 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1975 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1978 waveartist= [HW,OSS]
1979 Format: <io>,<irq>,<dma>,<dma2>
1982 See header of drivers/scsi/wd33c93.c.
1985 See header of drivers/scsi/wd7000.c.
1988 See Documentation/watchdog/wdt.txt.
1990 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1991 xd_geo= See header of drivers/block/xd.c.
1993 xirc2ps_cs= [NET,PCMCIA]
1995 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1997 norandmaps Don't use address space randomization
1998 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2000 ______________________________________________________________________
2004 Add documentation for ALSA options.
2005 Add more DRM drivers.