4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
105 In addition, the following text indicates that the option:
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
111 Parameters denoted with BOOT are actually interpreted by the boot
112 loader, and have no meaning to the kernel directly.
113 Do not modify the syntax of boot loader parameters without extreme
114 need or coordination with <Documentation/i386/boot.txt>.
116 There are also arch-specific kernel-parameters not documented here.
117 See for example <Documentation/x86_64/boot-options.txt>.
119 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120 a trailing = on the name of any parameter states that that parameter will
121 be entered as an environment variable, whereas its absence indicates that
122 it will appear as a kernel argument readable via /proc/cmdline by programs
123 running once the system is up.
125 The number of kernel parameters is not limited, but the length of the
126 complete command line (parameters including spaces etc.) is limited to
127 a fixed number of characters. This limit depends on the architecture
128 and is between 256 and 4096 characters. It is defined in the file
129 ./include/asm/setup.h as COMMAND_LINE_SIZE.
132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
134 Format: { force | off | ht | strict | noirq }
135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
139 strict -- Be less tolerant of platforms that are not
140 strictly ACPI specification compliant.
142 See also Documentation/power/pm.txt, pci=noacpi
144 acpi_apic_instance= [ACPI, IOAPIC]
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
150 acpi_sleep= [HW,ACPI] Sleep options
151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
163 Format: { level | edge | high | low }
165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
175 Format: <irq>,<irq>...
177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
178 Format: <irq>,<irq>...
180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
190 acpi_serialize [HW,ACPI] force serialization of AML methods
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
200 acpi.debug_layer= [HW,ACPI]
202 Each bit of the <int> indicates an ACPI debug layer,
203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
217 acpi.debug_level= [HW,ACPI]
219 Each bit of the <int> indicates an ACPI debug level,
220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
235 acpi_pm_good [X86-32,X86-64]
236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
250 The kernel tries to set a reasonable default.
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
260 See header of drivers/scsi/advansys.c.
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
270 See Documentation/scsi/aha152x.txt.
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
276 See Documentation/scsi/aic7xxx.txt.
279 See Documentation/scsi/aic79xx.txt.
281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
287 amd_iommu_size= [HW,X86-64]
288 Define the size of the aperture for the AMD IOMMU
289 driver. Possible values are:
290 '32M', '64M' (default), '128M', '256M', '512M', '1G'
292 amijoy.map= [HW,JOY] Amiga joystick support
293 Map of devices attached to JOY0DAT and JOY1DAT
295 See also Documentation/kernel/input/joystick.txt
297 analog.map= [HW,JOY] Analog joystick and gamepad support
298 Specifies type or capabilities of an analog joystick
299 connected to one of 16 gameports
300 Format: <type1>,<type2>,..<type16>
303 Power management functions (SPARCstation-4/5 + deriv.)
305 Disable APC CPU standby support. SPARCstation-Fox does
306 not play well with APC CPU idle - disable it if you have
307 APC and your system crashes randomly.
309 apic= [APIC,i386] Advanced Programmable Interrupt Controller
310 Change the output verbosity whilst booting
311 Format: { quiet (default) | verbose | debug }
312 Change the amount of debugging information output
313 when initialising the APIC and IO-APIC components.
315 apm= [APM] Advanced Power Management
316 See header of arch/x86/kernel/apm_32.c.
318 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
319 Format: <io>,<irq>,<nodeID>
323 atarimouse= [HW,MOUSE] Atari Mouse
325 atascsi= [HW,SCSI] Atari SCSI
327 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
328 EzKey and similar keyboards
330 atkbd.reset= [HW] Reset keyboard during initialization
332 atkbd.set= [HW] Select keyboard code set
333 Format: <int> (2 = AT (default), 3 = PS/2)
335 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
338 atkbd.softraw= [HW] Choose between synthetic and real raw mode
339 Format: <bool> (0 = real, 1 = synthetic (default))
341 atkbd.softrepeat= [HW]
342 Use software keyboard repeat
346 baycom_epp= [HW,AX25]
349 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
351 See header of drivers/net/hamradio/baycom_par.c.
353 baycom_ser_fdx= [HW,AX25]
354 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
355 Format: <io>,<irq>,<mode>[,<baud>]
356 See header of drivers/net/hamradio/baycom_ser_fdx.c.
358 baycom_ser_hdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
360 Format: <io>,<irq>,<mode>
361 See header of drivers/net/hamradio/baycom_ser_hdx.c.
363 boot_delay= Milliseconds to delay each printk during boot.
364 Values larger than 10 seconds (10000) are changed to
368 bootmem_debug [KNL] Enable bootmem allocator debug messages.
370 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
371 bttv.radio= Most important insmod options are available as
373 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
374 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
377 See drivers/scsi/BusLogic.c, comment before function
378 BusLogic_ParseDriverOptions().
380 c101= [NET] Moxa C101 synchronous serial card
382 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
383 Sometimes CPU hardware bugs make them report the cache
384 size incorrectly. The kernel will attempt work arounds
385 to fix known problems, but for some CPUs it is not
386 possible to determine what the correct size should be.
387 This option provides an override for these situations.
389 security= [SECURITY] Choose a security module to enable at boot.
390 If this boot parameter is not specified, only the first
391 security module asking for security registration will be
392 loaded. An invalid security module name will be treated
393 as if no module has been chosen.
396 [SECURITY] Disable capabilities. This would normally
397 be used only if an alternative security model is to be
398 configured. Potentially dangerous and should only be
399 used if you are entirely sure of the consequences.
401 ccw_timeout_log [S390]
402 See Documentation/s390/CommonIO for details.
404 cgroup_disable= [KNL] Disable a particular controller
405 Format: {name of the controller(s) to disable}
406 {Currently supported controllers - "memory"}
408 checkreqprot [SELINUX] Set initial checkreqprot flag value.
409 Format: { "0" | "1" }
410 See security/selinux/Kconfig help text.
411 0 -- check protection applied by kernel (includes
412 any implied execute protection).
413 1 -- check protection requested by application.
414 Default value is set via a kernel config option.
415 Value can be changed at runtime via
416 /selinux/checkreqprot.
419 See Documentation/s390/CommonIO for details.
421 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
423 Forces specified clocksource (if available) to be used
424 when calculating gettimeofday(). If specified
425 clocksource is not available, it defaults to PIT.
426 Format: { pit | tsc | cyclone | pmtmr }
428 clocksource= [GENERIC_TIME] Override the default clocksource
430 Override the default clocksource and use the clocksource
431 with the name specified.
432 Some clocksource names to choose from, depending on
434 [all] jiffies (this is the base, fallback clocksource)
436 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
437 pxa_timer,timer3,32k_counter,timer0_1
439 [X86-32] pit,hpet,tsc,vmi-timer;
440 scx200_hrt on Geode; cyclone on IBM x440
448 clearcpuid=BITNUM [X86]
449 Disable CPUID feature X for the kernel. See
450 include/asm-x86/cpufeature.h for the valid bit numbers.
451 Note the Linux specific bits are not necessarily
452 stable over kernel options, but the vendor specific
454 Also note that user programs calling CPUID directly
455 or using the feature without checking anything
456 will still see it. This just prevents it from
457 being used by the kernel or shown in /proc/cpuinfo.
458 Also note the kernel might malfunction if you disable
461 code_bytes [IA32/X86_64] How many bytes of object code to print
468 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
469 over the 8254 in addition to over the IO-APIC. The
470 kernel tries to set a sensible default.
472 hpet= [X86-32,HPET] option to control HPET usage
473 Format: { enable (default) | disable | force }
474 disable: disable HPET and use PIT instead
475 force: allow force enabled of undocumented chips (ICH4,
478 com20020= [HW,NET] ARCnet - COM20020 chipset
480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
486 ARCnet - COM90xx chipset (memory-mapped buffers)
487 Format: <io>[,<irq>[,<memstart>]]
489 condev= [HW,S390] console device
492 console= [KNL] Output console device and options.
494 tty<n> Use the virtual console device <n>.
498 Use the specified serial port. The options are of
499 the form "bbbbpnf", where "bbbb" is the baud rate,
500 "p" is parity ("n", "o", or "e"), "n" is number of
501 bits, and "f" is flow control ("r" for RTS or
502 omit it). Default is "9600n8".
504 See Documentation/serial-console.txt for more
506 Documentation/networking/netconsole.txt for an
509 uart[8250],io,<addr>[,options]
510 uart[8250],mmio,<addr>[,options]
511 Start an early, polled-mode console on the 8250/16550
512 UART at the specified I/O port or MMIO address,
513 switching to the matching ttyS device later. The
514 options are the same as for ttyS, above.
516 If the device connected to the port is not a TTY but a braille
517 device, prepend "brl," before the device type, for instance
519 For now, only VisioBraille is supported.
521 earlycon= [KNL] Output early console device and options.
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address.
526 The options are the same as for ttyS, above.
529 [HW] Never suspend the console
530 Disable suspending of consoles during suspend and
531 hibernate operations. Once disabled, debugging
532 messages can reach various consoles while the rest
533 of the system is being put to sleep (ie, while
534 debugging driver suspend/resume hooks). This may
535 not work reliably with all consoles, but is known
536 to work with serial and VGA consoles.
538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
542 crashkernel=nn[KMG]@ss[KMG]
543 [KNL] Reserve a chunk of physical memory to
544 hold a kernel to switch to with kexec on panic.
546 crashkernel=range1:size1[,range2:size2,...][@offset]
547 [KNL] Same as above, but depends on the memory
548 in the running system. The syntax of range is
549 start-[end] where start and end are both
550 a memory unit (amount[KMG]). See also
551 Documentation/kdump/kdump.txt for a example.
554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
559 cs89x0_media= [HW,NET]
560 Format: { rj45 | aui | bnc }
563 See header of drivers/s390/block/dasd_devmap.c.
565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
566 (one device per port)
567 Format: <port#>,<type>
568 See also Documentation/input/joystick-parport.txt
570 debug [KNL] Enable kernel debugging (events log level).
573 [KNL] verbose self-tests
575 Print debugging info while doing the locking API
577 We default to 0 (no extra messages), setting it to
578 1 will print _a lot_ more information - normally
579 only useful to kernel developers.
581 debug_objects [KNL] Enable object debugging
583 debugpat [X86] Enable PAT debugging
585 decnet.addr= [HW,NET]
586 Format: <area>[,<node>]
587 See also Documentation/networking/decnet.txt.
590 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
591 Change the default blue palette of the console.
592 This is a 16-member array composed of values
596 Format: <green0>,<green1>,<green2>,...,<green15>
597 Change the default green palette of the console.
598 This is a 16-member array composed of values
602 Format: <red0>,<red1>,<red2>,...,<red15>
603 Change the default red palette of the console.
604 This is a 16-member array composed of values
610 Set system-wide default UTF-8 mode for all tty's.
611 Default is 1, i.e. UTF-8 mode is enabled for all
612 newly opened terminals.
615 Set number of hash buckets for dentry cache.
618 IO parameters + enable/disable command.
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/digiepca.txt.
624 disable_mtrr_cleanup [X86]
625 enable_mtrr_cleanup [X86]
626 The kernel tries to adjust MTRR layout from continuous
627 to discrete, to make X server driver able to add WB
628 entry later. This parameter enables/disables that.
630 mtrr_chunk_size=nn[KMG] [X86]
631 used for mtrr cleanup. It is largest continous chunk
632 that could hold holes aka. UC entries.
634 mtrr_gran_size=nn[KMG] [X86]
635 Used for mtrr cleanup. It is granularity of mtrr block.
637 Large value could prevent small alignment from
640 mtrr_spare_reg_nr=n [X86]
642 Range: 0,7 : spare reg number
644 Used for mtrr cleanup. It is spare mtrr entries number.
645 Set to 2 or more if your graphical card needs more.
647 disable_mtrr_trim [X86, Intel and AMD only]
648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
653 dmasound= [HW,OSS] Sound subsystem buffers
659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
661 earlyprintk=serial[,ttySn[,baudrate]]
663 Append ",keep" to not disable it when the real console
666 Only vga or serial at a time, not both.
668 Currently only ttyS0 and ttyS1 are supported.
670 Interaction with the standard serial driver is not
673 The VGA output is eventually overwritten by the real
679 Format: {"off" | "on" | "skip[mbr]"}
681 eisa_irq_edge= [PARISC,HW]
682 See header of drivers/parisc/eisa.c.
685 See comment before function elanfreq_setup() in
686 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
690 See Documentation/block/as-iosched.txt and
691 Documentation/block/deadline-iosched.txt for details.
693 elfcorehdr= [X86-32, X86_64]
694 Specifies physical address of start of kernel core
695 image elf header. Generally kexec loader will
696 pass this option to capture kernel.
697 See Documentation/kdump/kdump.txt for details.
699 enforcing [SELINUX] Set initial enforcing status.
701 See security/selinux/Kconfig help text.
702 0 -- permissive (log only, no denials).
703 1 -- enforcing (deny and log).
705 Value can be changed at runtime via /selinux/enforce.
708 Format: <spdif>,[<nomix>,[<amplifier>]]
709 See also header of sound/oss/es1371.c.
711 ether= [HW,NET] Ethernet cards parameters
712 This option is obsoleted by the "netdev=" option, which
713 has equivalent usage. See its documentation for details.
715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
720 fail_make_request=[KNL]
721 General fault injection mechanism.
722 Format: <interval>,<probability>,<space>,<times>
723 See also /Documentation/fault-injection/.
726 See header of drivers/scsi/fd_mcs.c.
729 See header of drivers/scsi/fdomain.c.
732 See Documentation/floppy.txt.
734 force_pal_cache_flush
735 [IA-64] Avoid check_sal_cache_flush which may hang on
736 buggy SAL_CACHE_FLUSH implementations. Using this
737 parameter will force ia64_sal_cache_flush to call
738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
742 support via parallel port (up to 5 devices per port)
743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
744 See also Documentation/input/joystick-parport.txt
748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
753 See header of drivers/scsi/gdth.c.
755 gpt [EFI] Forces disk with valid GPT signature but
756 invalid Protective MBR to be treated as GPT.
760 hashdist= [KNL,NUMA] Large hashes allocated during boot
761 are distributed across NUMA nodes. Defaults on
762 for IA-64, off otherwise.
763 Format: 0 | 1 (for off | on)
765 hcl= [IA-64] SGI's Hardware Graph compatibility layer
767 hd= [EIDE] (E)IDE hard drive subsystem geometry
768 Format: <cyl>,<head>,<sect>
770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
771 size of <nn>. This works even on boxes that have no
772 highmem otherwise. This also works to reduce highmem
773 size on bigger boxes.
775 highres= [KNL] Enable/disable high resolution timer mode.
776 Valid parameters: "on", "off"
780 See Documentation/isdn/README.HiSax.
782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
784 On x86-64 and powerpc, this option can be specified
785 multiple times interleaved with hugepages= to reserve
786 huge pages of different sizes. Valid pages sizes on
787 x86-64 are 2M (when the CPU supports "pse") and 1G
788 (when the CPU supports the "pdpe1gb" cpuinfo flag)
789 Note that 1GB pages can only be allocated at boot time
790 using hugepages= and not freed afterwards.
792 [same as hugepagesz=] The size of the default
793 HugeTLB page size. This is the size represented by
794 the legacy /proc/ hugepages APIs, used for SHM, and
795 default size when mounting hugetlbfs filesystems.
796 Defaults to the default architecture's huge page size
801 i8042.direct [HW] Put keyboard port into non-translated mode
802 i8042.dumbkbd [HW] Pretend that controller can only read data from
803 keyboard and cannot control its state
804 (Don't attempt to blink the leds)
805 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
806 i8042.nokbd [HW] Don't check/create keyboard port
807 i8042.noloop [HW] Disable the AUX Loopback command while probing
809 i8042.nomux [HW] Don't check presence of an active multiplexing
811 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
814 [HW] Frequency with which keyboard LEDs should blink
815 when kernel panics (default is 0.5 sec)
816 i8042.reset [HW] Reset the controller during init and cleanup
817 i8042.unlock [HW] Unlock (ignore) the keylock
821 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
822 indicates that the driver is running on unsupported
824 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
825 does not match list of supported models.
827 [HW] Report power status in /proc/i8k
828 (disabled by default)
829 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
832 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
833 See Documentation/mca.txt.
836 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
838 ide= [HW] (E)IDE subsystem
839 Format: ide=nodma or ide=doubler
840 See Documentation/ide/ide.txt.
842 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
843 See Documentation/ide/ide.txt.
846 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
847 Poll forces a polling idle loop that can slightly improves the performance
848 of waking up a idle CPU, but will use a lot of power and make the system
849 run hot. Not recommended.
850 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
851 to not use it because it doesn't save as much power as a normal idle
852 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
854 idle=halt. Halt is forced to be used for CPU idle.
855 In such case C2/C3 won't be used again.
856 idle=nomwait. Disable mwait for CPU C-states
858 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
859 Claim all unknown PCI IDE storage controllers.
861 ignore_loglevel [KNL]
862 Ignore loglevel setting - this will print /all/
863 kernel messages to the console. Useful for debugging.
866 Set number of hash buckets for inode cache.
869 See header of drivers/scsi/in2000.c.
873 Run specified binary instead of /sbin/init as init
876 initcall_debug [KNL] Trace initcalls as they are executed. Useful
877 for working out where the kernel is dying during
880 initrd= [BOOT] Specify the location of the initial ramdisk
882 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
900 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
902 Disable intel iommu driver.
903 igfx_off [Default Off]
904 By default, gfx is mapped as normal device. If a gfx
905 device has a dedicated DMAR unit, the DMAR unit is
906 bypassed by not enabling DMAR with this option. In
907 this case, gfx device will use physical address for
910 With this option iommu will not optimize to look
911 for io virtual address below 32 bit forcing dual
912 address cycle on pci bus for cards supporting greater
913 than 32 bit addressing. The default is to look
914 for translation below 32 bit and if not available
915 then look in the higher range.
917 With this option on every unmap_single operation will
918 result in a hardware IOTLB flush operation as opposed
919 to batching them for performance.
921 io_delay= [X86-32,X86-64] I/O delay method
923 Standard port 0x80 based delay
925 Alternate port 0xed based delay (needed on some systems)
927 Simple two microseconds delay
931 io7= [HW] IO7 for Marvel based alpha systems
932 See comment before marvel_specify_io7 in
933 arch/alpha/kernel/core_marvel.c.
936 See Documentation/filesystems/nfsroot.txt.
938 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
939 See comment before ip2_setup() in
940 drivers/char/ip2/ip2base.c.
942 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
943 See header of drivers/scsi/ips.c.
945 ports= [IP_VS_FTP] IPVS ftp helper module
947 Up to 8 (IP_VS_APP_MAX_PORTS) ports
949 Format: <port>,<port>....
952 When an interrupt is not handled search all handlers
953 for it. Intended to get systems with badly broken
957 When an interrupt is not handled search all handlers
958 for it. Also check all handlers each timer
959 interrupt. Intended to get systems with badly broken
963 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
965 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
967 <cpu number>,...,<cpu number>
969 <cpu number>-<cpu number> (must be a positive range in ascending order)
971 <cpu number>,...,<cpu number>-<cpu number>
972 This option can be used to specify one or more CPUs
973 to isolate from the general SMP balancing and scheduling
974 algorithms. The only way to move a process onto or off
975 an "isolated" CPU is via the CPU affinity syscalls.
976 <cpu number> begins at 0 and the maximum value is
977 "number of CPUs in system - 1".
979 This option is the preferred way to isolate CPUs. The
980 alternative -- manually setting the CPU mask of all
981 tasks in the system -- can cause problems and
982 suboptimal load balancer performance.
986 js= [HW,JOY] Analog joystick
987 See Documentation/input/joystick.txt.
989 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
990 specifies the amount of memory usable by the kernel
991 for non-movable allocations. The requested amount is
992 spread evenly throughout all nodes in the system. The
993 remaining memory in each node is used for Movable
994 pages. In the event, a node is too small to have both
995 kernelcore and Movable pages, kernelcore pages will
996 take priority and other nodes will have a larger number
997 of kernelcore pages. The Movable zone is used for the
998 allocation of pages that may be reclaimed or moved
999 by the page migration subsystem. This means that
1000 HugeTLB pages may not be allocated from this zone.
1001 Note that allocations like PTEs-from-HighMem still
1002 use the HighMem zone if it exists, and the Normal
1003 zone if it does not.
1005 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1006 is similar to kernelcore except it specifies the
1007 amount of memory used for migratable allocations.
1008 If both kernelcore and movablecore is specified,
1009 then kernelcore will be at *least* the specified
1010 value but may be more. If movablecore on its own
1011 is specified, the administrator must be careful
1012 that the amount of memory usable for all allocations
1017 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1020 kgdboc= [HW] kgdb over consoles.
1021 Requires a tty driver that supports console polling.
1022 (only serial suported for now)
1023 Format: <serial_device>[,baud]
1029 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1032 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1035 libata.dma= [LIBATA] DMA control
1036 libata.dma=0 Disable all PATA and SATA DMA
1037 libata.dma=1 PATA and SATA Disk DMA only
1038 libata.dma=2 ATAPI (CDROM) DMA only
1039 libata.dma=4 Compact Flash DMA only
1040 Combinations also work, so libata.dma=3 enables DMA
1041 for disks and CDROMs, but not CFs.
1043 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1047 libata.force= [LIBATA] Force configurations. The format is comma
1048 separated list of "[ID:]VAL" where ID is
1049 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1050 matching port, link or device. Basically, it matches
1051 the ATA ID string printed on console by libata. If
1052 the whole ID part is omitted, the last PORT and DEVICE
1053 values are used. If ID hasn't been specified yet, the
1054 configuration applies to all ports, links and devices.
1056 If only DEVICE is omitted, the parameter applies to
1057 the port and all links and devices behind it. DEVICE
1058 number of 0 either selects the first device or the
1059 first fan-out link behind PMP device. It does not
1060 select the host link. DEVICE number of 15 selects the
1061 host link and device attached to it.
1063 The VAL specifies the configuration to force. As long
1064 as there's no ambiguity shortcut notation is allowed.
1065 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1066 The following configurations can be forced.
1068 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1069 Any ID with matching PORT is used.
1071 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1073 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1074 udma[/][16,25,33,44,66,100,133] notation is also
1077 * [no]ncq: Turn on or off NCQ.
1079 * nohrst, nosrst, norst: suppress hard, soft
1082 If there are multiple matching configurations changing
1083 the same attribute, the last one is used.
1085 load_ramdisk= [RAM] List of ramdisks to load from floppy
1086 See Documentation/ramdisk.txt.
1088 lockd.nlm_grace_period=P [NFS] Assign grace period.
1091 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1094 lockd.nlm_timeout=T [NFS] Assign timeout value.
1097 lockd.nlm_udpport=M [NFS] Assign UDP port.
1100 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1103 loglevel= All Kernel Messages with a loglevel smaller than the
1104 console loglevel will be printed to the console. It can
1105 also be changed with klogd or other programs. The
1106 loglevels are defined as follows:
1108 0 (KERN_EMERG) system is unusable
1109 1 (KERN_ALERT) action must be taken immediately
1110 2 (KERN_CRIT) critical conditions
1111 3 (KERN_ERR) error conditions
1112 4 (KERN_WARNING) warning conditions
1113 5 (KERN_NOTICE) normal but significant condition
1114 6 (KERN_INFO) informational
1115 7 (KERN_DEBUG) debug-level messages
1117 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1118 Format: { n | nk | nM }
1119 n must be a power of two. The default size
1120 is set in the kernel config file.
1122 logo.nologo [FB] Disables display of the built-in Linux logo.
1123 This may be used to provide more screen space for
1124 kernel log messages and is useful when debugging
1125 kernel boot problems.
1127 lp=0 [LP] Specify parallel ports to use, e.g,
1128 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1129 lp=reset first parallel port). 'lp=0' disables the
1130 lp=auto printer driver. 'lp=reset' (which can be
1131 specified in addition to the ports) causes
1132 attached printers to be reset. Using
1133 lp=port1,port2,... specifies the parallel ports
1134 to associate lp devices with, starting with
1135 lp0. A port specification may be 'none' to skip
1136 that lp device, or a parport name such as
1137 'parport0'. Specifying 'lp=auto' instead of a
1138 port specification list means that device IDs
1139 from each port should be examined, to see if
1140 an IEEE 1284-compliant printer is attached; if
1141 so, the driver will manage that printer.
1142 See also header of drivers/char/lp.c.
1145 Sets loops_per_jiffy to given constant, thus avoiding
1146 time-consuming boot-time autodetection (up to 250 ms per
1147 CPU). 0 enables autodetection (default). To determine
1148 the correct value for your kernel, boot with normal
1149 autodetection and see what value is printed. Note that
1150 on SMP systems the preset will be applied to all CPUs,
1151 which is likely to cause problems if your CPUs need
1152 significantly divergent settings. An incorrect value
1153 will cause delays in the kernel to be wrong, leading to
1154 unpredictable I/O errors and other breakage. Although
1155 unlikely, in the extreme case this might damage your
1159 Format: <io>,<irq>,<dma>
1161 mac5380= [HW,SCSI] Format:
1162 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1164 machvec= [IA64] Force the use of a particular machine-vector
1165 (machvec) in a generic kernel.
1166 Example: machvec=hpzx1_swiotlb
1168 max_loop= [LOOP] Maximum number of loopback devices that can
1172 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1173 should make use of. maxcpus=n : n >= 0 limits the
1174 kernel to using 'n' processors. n=0 is a special case,
1175 it is equivalent to "nosmp", which also disables
1178 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1179 equal to this physical address is ignored.
1181 max_luns= [SCSI] Maximum number of LUNs to probe.
1182 Should be between 1 and 2^32-1.
1185 [SCSI] Maximum number of LUNs received.
1186 Should be between 1 and 16384.
1190 mce [X86-32] Machine Check Exception
1192 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1194 md= [HW] RAID subsystems devices and level
1195 See Documentation/md.txt.
1198 Format: <first>,<last>
1199 Specifies range of consoles to be captured by the MDA.
1201 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1202 Amount of memory to be used when the kernel is not able
1203 to see the whole system memory or for test.
1204 [X86-32] Use together with memmap= to avoid physical
1205 address space collisions. Without memmap= PCI devices
1206 could be placed at addresses belonging to unused RAM.
1208 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1212 [KNL,SH] Allow user to override the default size for
1213 per-device physically contiguous DMA buffers.
1215 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1216 E820 memory map, as specified by the user.
1217 Such memmap=exactmap lines can be constructed based on
1218 BIOS output or other requirements. See the memmap=nn@ss
1221 memmap=nn[KMG]@ss[KMG]
1222 [KNL] Force usage of a specific region of memory
1223 Region of memory to be used, from ss to ss+nn.
1225 memmap=nn[KMG]#ss[KMG]
1226 [KNL,ACPI] Mark specific memory as ACPI data.
1227 Region of memory to be used, from ss to ss+nn.
1229 memmap=nn[KMG]$ss[KMG]
1230 [KNL,ACPI] Mark specific memory as reserved.
1231 Region of memory to be used, from ss to ss+nn.
1232 Example: Exclude memory from 0x18690000-0x1869ffff
1233 memmap=64K$0x18690000
1235 memmap=0x10000$0x18690000
1237 memtest= [KNL,X86] Enable memtest
1239 range: 0,4 : pattern number
1240 default : 0 <disable>
1242 meye.*= [HW] Set MotionEye Camera parameters
1243 See Documentation/video4linux/meye.txt.
1245 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1246 Multi-Function General Purpose Timers on AMD Geode
1249 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1250 the BIOS has incorrectly applied a workaround. TinyBIOS
1251 version 0.98 is known to be affected, 0.99 fixes the
1252 problem by letting the user disable the workaround.
1257 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1258 parameter allows control of the logging verbosity for
1259 the additional memory initialisation checks. A value
1260 of 0 disables mminit logging and a level of 4 will
1261 log everything. Information is printed at KERN_DEBUG
1262 so loglevel=8 may also need to be specified.
1265 [MOUSE] Maximum time between finger touching and
1266 leaving touchpad surface for touch to be considered
1267 a tap and be reported as a left button click (for
1268 touchpads working in absolute mode only).
1270 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1271 reporting absolute coordinates, such as tablets
1272 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1273 reporting absolute coordinates, such as tablets
1278 MTD_Partition= [MTD]
1279 Format: <name>,<region-number>,<size>,<offset>
1281 MTD_Region= [MTD] Format:
1282 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1285 See drivers/mtd/cmdlinepart.c.
1288 ARM/S3C2412 JIVE boot control
1290 See arch/arm/mach-s3c2412/mach-jive.c
1292 mtouchusb.raw_coordinates=
1293 [HW] Make the MicroTouch USB driver use raw coordinates
1294 ('y', default) or cooked coordinates ('n')
1296 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1299 See header of drivers/scsi/NCR_D700.c.
1303 ncr53c400= [HW,SCSI]
1305 ncr53c400a= [HW,SCSI]
1307 ncr53c406a= [HW,SCSI]
1309 ncr53c8xx= [HW,SCSI]
1311 netdev= [NET] Network devices parameters
1312 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1313 Note that mem_start is often overloaded to mean
1314 something different and driver-specific.
1315 This usage is only documented in each driver source
1319 [NETFILTER] Enable connection tracking flow accounting
1320 0 to disable accounting
1321 1 to enable accounting
1322 Default value depends on CONFIG_NF_CT_ACCT that is
1323 going to be removed in 2.6.29.
1326 See Documentation/filesystems/nfsroot.txt.
1328 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1329 See Documentation/filesystems/nfsroot.txt.
1331 nfs.callback_tcpport=
1332 [NFS] set the TCP port on which the NFSv4 callback
1333 channel should listen.
1335 nfs.idmap_cache_timeout=
1336 [NFS] set the maximum lifetime for idmapper cache
1340 [NFS] enable 64-bit inode numbers.
1341 If zero, the NFS client will fake up a 32-bit inode
1342 number for the readdir() and stat() syscalls instead
1343 of returning the full 64-bit number.
1344 The default is to return 64-bit inode numbers.
1346 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1347 when a NMI is triggered.
1348 Format: [state][,regs][,debounce][,die]
1350 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1352 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1353 emulation library even if a 387 maths coprocessor
1356 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1357 caches in the slab allocator. Saves per-node memory,
1358 but will impact performance.
1362 noapic [SMP,APIC] Tells the kernel to not make use of any
1363 IOAPICs that may be present in the system.
1365 nobats [PPC] Do not use BATs for mapping kernel lowmem
1366 on "Classic" PPC cores.
1370 nodelayacct [KNL] Disable per-task delay accounting
1372 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1374 nodsp [SH] Disable hardware DSP at boot time.
1376 noefi [X86-32,X86-64] Disable EFI runtime services support.
1380 noexec [X86-32,X86-64]
1381 On X86-32 available only on PAE configured kernels.
1382 noexec=on: enable non-executable mappings (default)
1383 noexec=off: disable non-executable mappings
1386 This affects only 32-bit executables.
1387 noexec32=on: enable non-executable mappings (default)
1388 read doesn't imply executable mappings
1389 noexec32=off: disable non-executable mappings
1390 read implies executable mappings
1392 nofpu [SH] Disable hardware FPU at boot time.
1394 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1395 register save and restore. The kernel will only save
1396 legacy floating-point registers on task switch.
1398 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1402 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1403 instruction doesn't work correctly and not to
1406 nohalt [IA-64] Tells the kernel not to use the power saving
1407 function PAL_HALT_LIGHT when idle. This increases
1408 power-consumption. On the positive side, it reduces
1409 interrupt wake-up latency, which may improve performance
1410 in certain environments such as networked servers or
1413 nohz= [KNL] Boottime enable/disable dynamic ticks
1414 Valid arguments: on, off
1417 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1419 noirqdebug [X86-32] Disables the code which attempts to detect and
1420 disable unhandled interrupt sources.
1422 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1423 broken timer IRQ sources.
1425 noisapnp [ISAPNP] Disables ISA PnP code.
1427 noinitrd [RAM] Tells the kernel not to load any configured
1432 nojitter [IA64] Disables jitter checking for ITC timers.
1434 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1436 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1438 noltlbs [PPC] Do not use large page/tlb entries for kernel
1439 lowmem mapping on PPC40x.
1441 nomca [IA-64] Disable machine check abort handling
1443 nomce [X86-32] Machine Check Exception
1445 nomfgpt [X86-32] Disable Multi-Function General Purpose
1446 Timer usage (for AMD Geode machines).
1448 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1450 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1451 with UP alternatives
1453 noresidual [PPC] Don't use residual data on PReP machines.
1455 noresume [SWSUSP] Disables resume and restores original swap
1458 no-scroll [VGA] Disables scrollback.
1459 This is required for the Braillex ib80-piezo Braille
1460 reader made by F.H. Papenmeier (Germany).
1464 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1466 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1467 and disable the IO APIC. legacy for "maxcpus=0".
1469 nosoftlockup [KNL] Disable the soft-lockup detector.
1471 nosync [HW,M68K] Disables sync negotiation for all devices.
1473 notsc [BUGS=X86-32] Disable Time Stamp Counter
1475 nousb [USB] Disable the USB subsystem
1479 nptcg= [IA64] Override max number of concurrent global TLB
1480 purges which is reported from either PAL_VM_SUMMARY or
1483 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1484 one of ['zone', 'node', 'default'] can be specified
1485 This can be set from sysctl after boot.
1486 See Documentation/sysctl/vm.txt for details.
1488 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1490 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1491 Rather than timing out after 20 ms if an EC
1492 command is not properly ACKed, override the length
1493 of the timeout. We have interrupts disabled while
1494 waiting for the ACK, so if this is set too high
1495 interrupts *may* be lost!
1500 oprofile.timer= [HW]
1501 Use timer interrupt instead of performance counters
1503 osst= [HW,SCSI] SCSI Tape Driver
1504 Format: <buffer_size>,<write_threshold>
1505 See also Documentation/scsi/st.txt.
1507 panic= [KNL] Kernel behaviour on panic
1510 parkbd.port= [HW] Parallel port number the keyboard adapter is
1511 connected to, default is 0.
1513 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1514 0 for XT, 1 for AT (default is AT).
1517 parport= [HW,PPT] Specify parallel ports. 0 disables.
1518 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1519 Use 'auto' to force the driver to use any
1520 IRQ/DMA settings detected (the default is to
1521 ignore detected IRQ/DMA settings because of
1522 possible conflicts). You can specify the base
1523 address, IRQ, and DMA settings; IRQ and DMA
1524 should be numbers, or 'auto' (for using detected
1525 settings on that particular port), or 'nofifo'
1526 (to avoid using a FIFO even if it is detected).
1527 Parallel ports are assigned in the order they
1528 are specified on the command line, starting
1531 parport_init_mode= [HW,PPT]
1532 Configure VIA parallel port to operate in
1533 a specific mode. This is necessary on Pegasos
1534 computer where firmware has no options for setting
1535 up parallel port mode and sets it to spp.
1536 Currently this function knows 686a and 8231 chips.
1537 Format: [spp|ps2|epp|ecp|ecpepp]
1539 pas2= [HW,OSS] Format:
1540 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1543 See header of drivers/scsi/pas16.c.
1546 Halt all CPUs after the first oops has been printed for
1547 the specified number of seconds. This is to be used if
1548 your oopses keep scrolling off the screen.
1553 See header of drivers/block/paride/pcd.c.
1554 See also Documentation/paride.txt.
1556 pci=option[,option...] [PCI] various PCI subsystem options:
1557 off [X86-32] don't probe for the PCI bus
1558 bios [X86-32] force use of PCI BIOS, don't access
1559 the hardware directly. Use this if your machine
1560 has a non-standard PCI host bridge.
1561 nobios [X86-32] disallow use of PCI BIOS, only direct
1562 hardware access methods are allowed. Use this
1563 if you experience crashes upon bootup and you
1564 suspect they are caused by the BIOS.
1565 conf1 [X86-32] Force use of PCI Configuration
1567 conf2 [X86-32] Force use of PCI Configuration
1569 noaer [PCIE] If the PCIEAER kernel config parameter is
1570 enabled, this kernel boot option can be used to
1571 disable the use of PCIE advanced error reporting.
1572 nodomains [PCI] Disable support for multiple PCI
1573 root domains (aka PCI segments, in ACPI-speak).
1574 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1576 nomsi [MSI] If the PCI_MSI kernel config parameter is
1577 enabled, this kernel boot option can be used to
1578 disable the use of MSI interrupts system-wide.
1579 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1580 routing table. These calls are known to be buggy
1581 on several machines and they hang the machine
1582 when used, but on other computers it's the only
1583 way to get the interrupt routing table. Try
1584 this option if the kernel is unable to allocate
1585 IRQs or discover secondary PCI buses on your
1587 rom [X86-32] Assign address space to expansion ROMs.
1588 Use with caution as certain devices share
1589 address decoders between ROMs and other
1591 norom [X86-32,X86_64] Do not assign address space to
1592 expansion ROMs that do not already have
1593 BIOS assigned address ranges.
1594 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1595 assigned automatically to PCI devices. You can
1596 make the kernel exclude IRQs of your ISA cards
1598 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1599 of the PIRQ table (normally generated
1600 by the BIOS) if it is outside the
1601 F0000h-100000h range.
1602 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1603 useful if the kernel is unable to find your
1604 secondary buses and you want to tell it
1605 explicitly which ones they are.
1606 assign-busses [X86-32] Always assign all PCI bus
1607 numbers ourselves, overriding
1608 whatever the firmware may have done.
1609 usepirqmask [X86-32] Honor the possible IRQ mask stored
1610 in the BIOS $PIR table. This is needed on
1611 some systems with broken BIOSes, notably
1612 some HP Pavilion N5400 and Omnibook XE3
1613 notebooks. This will have no effect if ACPI
1614 IRQ routing is enabled.
1615 noacpi [X86-32] Do not use ACPI for IRQ routing
1616 or for PCI scanning.
1617 use_crs [X86-32] Use _CRS for PCI resource
1619 routeirq Do IRQ routing for all PCI devices.
1620 This is normally done in pci_enable_device(),
1621 so this option is a temporary workaround
1622 for broken drivers that don't call it.
1623 skip_isa_align [X86] do not align io start addr, so can
1624 handle more pci cards
1625 firmware [ARM] Do not re-enumerate the bus but instead
1626 just use the configuration from the
1627 bootloader. This is currently used on
1628 IXP2000 systems where the bus has to be
1629 configured a certain way for adjunct CPUs.
1630 noearly [X86] Don't do any early type 1 scanning.
1631 This might help on some broken boards which
1632 machine check when some devices' config space
1633 is read. But various workarounds are disabled
1634 and some IOMMU drivers will not work.
1635 bfsort Sort PCI devices into breadth-first order.
1636 This sorting is done to get a device
1637 order compatible with older (<= 2.4) kernels.
1638 nobfsort Don't sort PCI devices into breadth-first order.
1639 cbiosize=nn[KMG] The fixed amount of bus space which is
1640 reserved for the CardBus bridge's IO window.
1641 The default value is 256 bytes.
1642 cbmemsize=nn[KMG] The fixed amount of bus space which is
1643 reserved for the CardBus bridge's memory
1644 window. The default value is 64 megabytes.
1646 pcmv= [HW,PCMCIA] BadgePAD 4
1649 See Documentation/paride.txt.
1651 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1654 See arch/parisc/kernel/pdc_chassis.c
1657 See Documentation/paride.txt.
1660 See Documentation/paride.txt.
1662 pirq= [SMP,APIC] Manual mp-table setup
1663 See Documentation/i386/IO-APIC.txt.
1665 plip= [PPT,NET] Parallel port network link
1666 Format: { parport<nr> | timid | 0 }
1667 See also Documentation/parport.txt.
1669 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1670 Override pmtimer IOPort with a hex value.
1677 { on | off | curr | res | no-curr | no-res }
1680 [ISAPNP] Exclude IRQs for the autoconfiguration
1683 [ISAPNP] Exclude DMAs for the autoconfiguration
1685 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1686 Ranges are in pairs (I/O port base and size).
1689 [ISAPNP] Exclude memory regions for the
1691 Ranges are in pairs (memory base and size).
1693 print-fatal-signals=
1694 [KNL] debug: print fatal signals
1695 print-fatal-signals=1: print segfault info to
1699 printk.time= Show timing data prefixed to each printk message line
1700 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1702 profile= [KNL] Enable kernel profiling via /proc/profile
1703 Format: [schedule,]<number>
1704 Param: "schedule" - profile schedule points.
1705 Param: <number> - step/bucket size as a power of 2 for
1706 statistical time based profiling.
1707 Param: "sleep" - profile D-state sleeping (millisecs).
1708 Requires CONFIG_SCHEDSTATS
1709 Param: "kvm" - profile VM exits.
1711 processor.max_cstate= [HW,ACPI]
1712 Limit processor to maximum C-state
1713 max_cstate=9 overrides any DMI blacklist limit.
1715 processor.nocst [HW,ACPI]
1716 Ignore the _CST method to determine C-states,
1717 instead using the legacy FADT method
1719 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1721 See Documentation/ramdisk.txt.
1723 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1724 probe for; one of (bare|imps|exps|lifebook|any).
1725 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1727 psmouse.resetafter= [HW,MOUSE]
1728 Try to reset the device after so many bad packets
1731 [HW,MOUSE] Set desired mouse resolution, in dpi.
1732 psmouse.smartscroll=
1733 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1734 0 = disabled, 1 = enabled (default).
1736 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1738 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1741 See Documentation/paride.txt.
1744 [KNL] Number of legacy pty's. Overwrites compiled-in
1747 quiet [KNL] Disable most log messages
1752 See Documentation/md.txt.
1754 ramdisk_blocksize= [RAM]
1755 See Documentation/ramdisk.txt.
1757 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1758 See Documentation/ramdisk.txt.
1760 rcupdate.blimit= [KNL,BOOT]
1761 Set maximum number of finished RCU callbacks to process
1764 rcupdate.qhimark= [KNL,BOOT]
1765 Set threshold of queued
1766 RCU callbacks over which batch limiting is disabled.
1768 rcupdate.qlowmark= [KNL,BOOT]
1769 Set threshold of queued RCU callbacks below which
1770 batch limiting is re-enabled.
1774 Run specified binary instead of /init from the ramdisk,
1775 used for early userspace startup. See initrd.
1777 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1778 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1779 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1782 [KNL, SMP] Set scheduler's default relax_domain_level.
1783 See Documentation/cpusets.txt.
1785 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1787 reservetop= [X86-32]
1789 Reserves a hole at the top of the kernel virtual
1792 reset_devices [KNL] Force drivers to reset the underlying device
1793 during initialization.
1796 Specify the partition device for software suspend
1798 resume_offset= [SWSUSP]
1799 Specify the offset from the beginning of the partition
1800 given by "resume=" at which the swap header is located,
1801 in <PAGE_SIZE> units (needed only for swap files).
1802 See Documentation/power/swsusp-and-swap-files.txt
1804 retain_initrd [RAM] Keep initrd memory after extraction
1806 rhash_entries= [KNL,NET]
1807 Set number of hash buckets for route cache
1809 riscom8= [HW,SERIAL]
1810 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1812 ro [KNL] Mount root device read-only on boot
1814 root= [KNL] Root filesystem
1816 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1817 mount the root filesystem
1819 rootflags= [KNL] Set root filesystem mount option string
1821 rootfstype= [KNL] Set root filesystem type
1823 rootwait [KNL] Wait (indefinitely) for root device to show up.
1824 Useful for devices that are detected asynchronously
1825 (e.g. USB and MMC devices).
1827 root_plug.vendor_id=
1828 [ROOTPLUG] Override the default vendor ID
1830 root_plug.product_id=
1831 [ROOTPLUG] Override the default product ID
1834 [ROOTPLUG] Enable debugging output
1836 rw [KNL] Mount root device read-write on boot
1838 S [KNL] Run init in single mode
1841 See drivers/net/irda/sa1100_ir.c.
1843 sbni= [NET] Granch SBNI12 leased line adapter
1845 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1846 Format: <io>[,<timeout>[,<isapnp>]]
1848 scsi_debug_*= [SCSI]
1849 See drivers/scsi/scsi_debug.c.
1851 scsi_default_dev_flags=
1852 [SCSI] SCSI default device flags
1855 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1856 Format: <vendor>:<model>:<flags>
1857 (flags are integer value)
1859 scsi_logging_level= [SCSI] a bit mask of logging levels
1860 See drivers/scsi/scsi_logging.h for bits. Also
1861 settable via sysctl at dev.scsi.logging_level
1862 (/proc/sys/dev/scsi/logging_level).
1863 There is also a nice 'scsi_logging_level' script in the
1864 S390-tools package, available for download at
1865 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1867 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1868 discovered. async scans them in kernel threads,
1869 allowing boot to proceed. none ignores them, expecting
1870 user space to do the scan.
1872 selinux [SELINUX] Disable or enable SELinux at boot time.
1873 Format: { "0" | "1" }
1874 See security/selinux/Kconfig help text.
1877 Default value is set via kernel config option.
1878 If enabled at boot time, /selinux/disable can be used
1879 later to disable prior to initial policy load.
1881 selinux_compat_net =
1882 [SELINUX] Set initial selinux_compat_net flag value.
1883 Format: { "0" | "1" }
1884 0 -- use new secmark-based packet controls
1885 1 -- use legacy packet controls
1886 Default value is 0 (preferred).
1887 Value can be changed at runtime via
1888 /selinux/compat_net.
1890 serialnumber [BUGS=X86-32]
1893 Maximal number of shapers.
1896 See header of drivers/scsi/sim710.c.
1903 slub_debug[=options[,slabs]] [MM, SLUB]
1904 Enabling slub_debug allows one to determine the
1905 culprit if slab objects become corrupted. Enabling
1906 slub_debug can create guard zones around objects and
1907 may poison objects when not in use. Also tracks the
1908 last alloc / free. For more information see
1909 Documentation/vm/slub.txt.
1911 slub_max_order= [MM, SLUB]
1912 Determines the maximum allowed order for slabs.
1913 A high setting may cause OOMs due to memory
1914 fragmentation. For more information see
1915 Documentation/vm/slub.txt.
1917 slub_min_objects= [MM, SLUB]
1918 The minimum number of objects per slab. SLUB will
1919 increase the slab order up to slub_max_order to
1920 generate a sufficiently large slab able to contain
1921 the number of objects indicated. The higher the number
1922 of objects the smaller the overhead of tracking slabs
1923 and the less frequently locks need to be acquired.
1924 For more information see Documentation/vm/slub.txt.
1926 slub_min_order= [MM, SLUB]
1927 Determines the mininum page order for slabs. Must be
1928 lower than slub_max_order.
1929 For more information see Documentation/vm/slub.txt.
1931 slub_nomerge [MM, SLUB]
1932 Disable merging of slabs with similar size. May be
1933 necessary if there is some reason to distinguish
1934 allocs to different slabs. Debug options disable
1935 merging on their own.
1936 For more information see Documentation/vm/slub.txt.
1939 Format: <io1>[,<io2>[,...,<io8>]]
1941 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1942 attempt to substitute SMP alternatives once at boot.
1944 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1945 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1946 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1947 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1948 smsc-ircc2.ircc_irq= [HW] IRQ line
1949 smsc-ircc2.ircc_dma= [HW] DMA channel
1950 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1951 0: Toshiba Satellite 1800 (GP data pin select)
1952 1: Fast pin select (default)
1955 snd-ad1816a= [HW,ALSA]
1957 snd-ad1848= [HW,ALSA]
1959 snd-ali5451= [HW,ALSA]
1961 snd-als100= [HW,ALSA]
1963 snd-als4000= [HW,ALSA]
1965 snd-azt2320= [HW,ALSA]
1967 snd-cmi8330= [HW,ALSA]
1969 snd-cmipci= [HW,ALSA]
1971 snd-cs4231= [HW,ALSA]
1973 snd-cs4232= [HW,ALSA]
1975 snd-cs4236= [HW,ALSA]
1977 snd-cs4281= [HW,ALSA]
1979 snd-cs46xx= [HW,ALSA]
1981 snd-dt019x= [HW,ALSA]
1983 snd-dummy= [HW,ALSA]
1985 snd-emu10k1= [HW,ALSA]
1987 snd-ens1370= [HW,ALSA]
1989 snd-ens1371= [HW,ALSA]
1991 snd-es968= [HW,ALSA]
1993 snd-es1688= [HW,ALSA]
1995 snd-es18xx= [HW,ALSA]
1997 snd-es1938= [HW,ALSA]
1999 snd-es1968= [HW,ALSA]
2001 snd-fm801= [HW,ALSA]
2003 snd-gusclassic= [HW,ALSA]
2005 snd-gusextreme= [HW,ALSA]
2007 snd-gusmax= [HW,ALSA]
2011 snd-ice1712= [HW,ALSA]
2013 snd-intel8x0= [HW,ALSA]
2015 snd-interwave= [HW,ALSA]
2020 snd-korg1212= [HW,ALSA]
2022 snd-maestro3= [HW,ALSA]
2024 snd-mpu401= [HW,ALSA]
2026 snd-mtpav= [HW,ALSA]
2028 snd-nm256= [HW,ALSA]
2030 snd-opl3sa2= [HW,ALSA]
2038 snd-opti93x= [HW,ALSA]
2042 snd-rme32= [HW,ALSA]
2044 snd-rme96= [HW,ALSA]
2046 snd-rme9652= [HW,ALSA]
2052 snd-sbawe= [HW,ALSA]
2054 snd-serial= [HW,ALSA]
2056 snd-sgalaxy= [HW,ALSA]
2058 snd-sonicvibes= [HW,ALSA]
2063 snd-sun-cs4231= [HW,ALSA]
2065 snd-trident= [HW,ALSA]
2067 snd-usb-audio= [HW,ALSA,USB]
2069 snd-via82xx= [HW,ALSA]
2071 snd-virmidi= [HW,ALSA]
2073 snd-wavefront= [HW,ALSA]
2075 snd-ymfpci= [HW,ALSA]
2078 [KNL] Should the soft-lockup detector generate panics.
2080 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2081 See Documentation/sonypi.txt
2083 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2084 See Documentation/specialix.txt.
2086 spia_io_base= [HW,MTD]
2092 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2094 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2095 See Documentation/scsi/st.txt.
2099 Set the STI (builtin display/keyboard on the HP-PARISC
2100 machines) console (graphic card) which should be used
2101 as the initial boot-console.
2102 See also comment in drivers/video/console/sticore.c.
2105 See comment in drivers/video/console/sticore.c.
2108 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2112 Control how the NFS server code allocates CPUs to
2113 service thread pools. Depending on how many NICs
2114 you have and where their interrupts are bound, this
2115 option will affect which CPUs will do NFS serving.
2116 Note: this parameter cannot be changed while the
2117 NFS server is running.
2119 auto the server chooses an appropriate mode
2120 automatically using heuristics
2121 global a single global pool contains all CPUs
2122 percpu one pool for each CPU
2123 pernode one pool for each NUMA node (equivalent
2124 to global on non-NUMA machines)
2126 swiotlb= [IA-64] Number of I/O TLB slabs
2130 sym53c416= [HW,SCSI]
2131 See header of drivers/scsi/sym53c416.c.
2133 sysrq_always_enabled
2135 Ignore sysrq setting - this boot parameter will
2136 neutralize any effect of /proc/sys/kernel/sysrq.
2137 Useful for debugging.
2140 See header of drivers/scsi/t128.c.
2144 test_suspend= [SUSPEND]
2145 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2146 standby suspend) as the system sleep state to briefly
2147 enter during system startup. The system is woken from
2148 this state using a wakeup-capable RTC alarm.
2150 thash_entries= [KNL,NET]
2151 Set number of hash buckets for TCP connection
2153 thermal.act= [HW,ACPI]
2154 -1: disable all active trip points in all thermal zones
2155 <degrees C>: override all lowest active trip points
2157 thermal.crt= [HW,ACPI]
2158 -1: disable all critical trip points in all thermal zones
2159 <degrees C>: lower all critical trip points
2161 thermal.nocrt= [HW,ACPI]
2162 Set to disable actions on ACPI thermal zone
2163 critical and hot trip points.
2165 thermal.off= [HW,ACPI]
2166 1: disable ACPI thermal control
2168 thermal.psv= [HW,ACPI]
2169 -1: disable all passive trip points
2170 <degrees C>: override all passive trip points to this value
2172 thermal.tzp= [HW,ACPI]
2173 Specify global default ACPI thermal zone polling rate
2174 <deci-seconds>: poll all this frequency
2175 0: no polling (default)
2178 See comment before function dc390_setup() in
2179 drivers/scsi/tmscsim.c.
2183 trix= [HW,OSS] MediaTrix AudioTrix Pro
2185 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2187 turbografx.map[2|3]= [HW,JOY]
2188 TurboGraFX parallel port interface
2190 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2191 See also Documentation/input/joystick-parport.txt
2193 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2194 See header of drivers/scsi/u14-34f.c.
2203 [USB] Ignore overcurrent events (default N).
2204 Some badly-designed motherboards generate lots of
2205 bogus events, for ports that aren't wired to
2206 anything. Set this parameter to avoid log spamming.
2207 Note that genuine overcurrent events won't be
2212 Set unknown_nmi_panic=1 early on boot.
2214 usbcore.autosuspend=
2215 [USB] The autosuspend time delay (in seconds) used
2216 for newly-detected USB devices (default 2). This
2217 is the time required before an idle device will be
2218 autosuspended. Devices for which the delay is set
2219 to a negative value won't be autosuspended at all.
2222 [USBHID] The interval which mice are to be polled at.
2224 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2225 kernel's map of available physical RAM.
2227 vdso= [X86-32,SH,x86-64]
2228 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2229 vdso=1: enable VDSO (default)
2230 vdso=0: disable VDSO mapping
2232 vdso32= [X86-32,X86-64]
2233 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2234 vdso32=1: enable 32-bit VDSO (default)
2235 vdso32=0: disable 32-bit VDSO mapping
2238 vector=percpu: enable percpu vector domain
2240 video= [FB] Frame buffer configuration
2241 See Documentation/fb/modedb.txt.
2243 vga= [BOOT,X86-32] Select a particular video mode
2244 See Documentation/i386/boot.txt and
2245 Documentation/svga.txt.
2246 Use vga=ask for menu.
2247 This is actually a boot loader parameter; the value is
2248 passed to the kernel using a special protocol.
2250 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2251 size of <nn>. This can be used to increase the
2252 minimum size (128MB on x86). It can also be used to
2253 decrease the size and leave more room for directly
2256 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2259 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2262 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2265 waveartist= [HW,OSS]
2266 Format: <io>,<irq>,<dma>,<dma2>
2269 See header of drivers/scsi/wd33c93.c.
2272 See header of drivers/scsi/wd7000.c.
2275 See Documentation/watchdog/wdt.txt.
2277 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2278 xd_geo= See header of drivers/block/xd.c.
2280 xirc2ps_cs= [NET,PCMCIA]
2282 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2284 norandmaps Don't use address space randomization
2285 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2287 ______________________________________________________________________
2291 Add documentation for ALSA options.
2292 Add more DRM drivers.