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 IMA Integrity measurement architecture is enabled.
48 IOSCHED More than one I/O scheduler is enabled.
49 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
50 ISAPNP ISA PnP code is enabled.
51 ISDN Appropriate ISDN support is enabled.
52 JOY Appropriate joystick support is enabled.
53 LIBATA Libata driver is enabled
54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
62 MSI Message Signaled Interrupts (PCI).
63 MTD MTD (Memory Technology Device) support is enabled.
64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
66 GENERIC_TIME The generic timeofday code is enabled.
67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
73 PCIE PCI Express support is enabled.
74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
80 ROOTPLUG The example Root Plug LSM is enabled.
81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
85 SECURITY Different security models are enabled.
86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
88 SH SuperH architecture is enabled.
89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
91 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are enabled.
93 FTRACE Function tracing enabled.
94 TS Appropriate touchscreen support is enabled.
95 UMS USB Mass Storage support is enabled.
96 USB USB support is enabled.
97 USBHID USB Human Interface Device support is enabled.
98 V4L Video For Linux support is enabled.
99 VGA The VGA console has been enabled.
100 VT Virtual terminal support is enabled.
101 WDT Watchdog support is enabled.
102 XT IBM PC/XT MFM hard disk support is enabled.
103 X86-32 X86-32, aka i386 architecture is enabled.
104 X86-64 X86-64 architecture is enabled.
105 More X86-64 boot options can be found in
106 Documentation/x86/x86_64/boot-options.txt .
107 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
109 In addition, the following text indicates that the option:
111 BUGS= Relates to possible processor bugs on the said processor.
112 KNL Is a kernel start-up parameter.
113 BOOT Is a boot loader parameter.
115 Parameters denoted with BOOT are actually interpreted by the boot
116 loader, and have no meaning to the kernel directly.
117 Do not modify the syntax of boot loader parameters without extreme
118 need or coordination with <Documentation/x86/boot.txt>.
120 There are also arch-specific kernel-parameters not documented here.
121 See for example <Documentation/x86/x86_64/boot-options.txt>.
123 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
124 a trailing = on the name of any parameter states that that parameter will
125 be entered as an environment variable, whereas its absence indicates that
126 it will appear as a kernel argument readable via /proc/cmdline by programs
127 running once the system is up.
129 The number of kernel parameters is not limited, but the length of the
130 complete command line (parameters including spaces etc.) is limited to
131 a fixed number of characters. This limit depends on the architecture
132 and is between 256 and 4096 characters. It is defined in the file
133 ./include/asm/setup.h as COMMAND_LINE_SIZE.
136 acpi= [HW,ACPI,X86-64,i386]
137 Advanced Configuration and Power Interface
138 Format: { force | off | ht | strict | noirq | rsdt }
139 force -- enable ACPI if default was off
140 off -- disable ACPI if default was on
141 noirq -- do not use ACPI for IRQ routing
142 ht -- run only enough ACPI to enable Hyper Threading
143 strict -- Be less tolerant of platforms that are not
144 strictly ACPI specification compliant.
145 rsdt -- prefer RSDT over (default) XSDT
147 See also Documentation/power/pm.txt, pci=noacpi
149 acpi_apic_instance= [ACPI, IOAPIC]
151 2: use 2nd APIC table, if available
152 1,0: use 1st APIC table
155 acpi_sleep= [HW,ACPI] Sleep options
156 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
157 old_ordering, s4_nonvs }
158 See Documentation/power/video.txt for information on
160 s3_beep is for debugging; it makes the PC's speaker beep
161 as soon as the kernel's real-mode entry point is called.
162 s4_nohwsig prevents ACPI hardware signature from being
163 used during resume from hibernation.
164 old_ordering causes the ACPI 1.0 ordering of the _PTS
165 control method, with respect to putting devices into
166 low power states, to be enforced (the ACPI 2.0 ordering
167 of _PTS is used by default).
168 s4_nonvs prevents the kernel from saving/restoring the
169 ACPI NVS memory during hibernation.
171 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
172 Format: { level | edge | high | low }
174 acpi_irq_balance [HW,ACPI]
175 ACPI will balance active IRQs
178 acpi_irq_nobalance [HW,ACPI]
179 ACPI will not move active IRQs (default)
182 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
184 Format: <irq>,<irq>...
186 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
187 Format: <irq>,<irq>...
189 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
191 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
192 Format: To spoof as Windows 98: ="Microsoft Windows"
194 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
195 acpi_osi="string1" # add string1 -- only one string
196 acpi_osi="!string2" # remove built-in string2
197 acpi_osi= # disable all strings
199 acpi_serialize [HW,ACPI] force serialization of AML methods
201 acpi_skip_timer_override [HW,ACPI]
202 Recognize and ignore IRQ0/pin2 Interrupt Override.
203 For broken nForce2 BIOS resulting in XT-PIC timer.
204 acpi_use_timer_override [HW,ACPI]
205 Use timer override. For some broken Nvidia NF5 boards
206 that require a timer override, but don't have
209 acpi_backlight= [HW,ACPI]
210 acpi_backlight=vendor
212 If set to vendor, prefer vendor specific driver
213 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
214 of the ACPI video.ko driver.
216 acpi_display_output= [HW,ACPI]
217 acpi_display_output=vendor
218 acpi_display_output=video
221 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
222 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
224 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
225 debug output. Bits in debug_layer correspond to a
226 _COMPONENT in an ACPI source file, e.g.,
227 #define _COMPONENT ACPI_PCI_COMPONENT
228 Bits in debug_level correspond to a level in
229 ACPI_DEBUG_PRINT statements, e.g.,
230 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
231 The debug_level mask defaults to "info". See
232 Documentation/acpi/debug.txt for more information about
233 debug layers and levels.
235 Enable processor driver info messages:
236 acpi.debug_layer=0x20000000
237 Enable PCI/PCI interrupt routing info messages:
238 acpi.debug_layer=0x400000
239 Enable AML "Debug" output, i.e., stores to the Debug
240 object while interpreting AML:
241 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
242 Enable all messages related to ACPI hardware:
243 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
245 Some values produce so much output that the system is
246 unusable. The "log_buf_len" parameter may be useful
247 if you need to capture more output.
249 acpi.power_nocheck= [HW,ACPI]
250 Format: 1/0 enable/disable the check of power state.
251 On some bogus BIOS the _PSC object/_STA object of
252 power resource can't return the correct device power
253 state. In such case it is unneccessary to check its
254 power state again in power transition.
255 1 : disable the power state check
257 acpi_pm_good [X86-32,X86-64]
258 Override the pmtimer bug detection: force the kernel
259 to assume that this machine's pmtimer latches its value
260 and always returns good values.
263 { off | try_unsupported }
264 off: disable AGP support
265 try_unsupported: try to drive unsupported chipsets
266 (may crash computer or cause data corruption)
268 enable_timer_pin_1 [i386,x86-64]
269 Enable PIN 1 of APIC timer
270 Can be useful to work around chipset bugs
271 (in particular on some ATI chipsets).
272 The kernel tries to set a reasonable default.
274 disable_timer_pin_1 [i386,x86-64]
275 Disable PIN 1 of APIC timer
276 Can be useful to work around chipset bugs.
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
282 See header of drivers/scsi/advansys.c.
284 advwdt= [HW,WDT] Advantech WDT
285 Format: <iostart>,<iostop>
287 aedsp16= [HW,OSS] Audio Excel DSP 16
288 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
289 See also header of sound/oss/aedsp16.c.
292 See Documentation/scsi/aha152x.txt.
295 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
298 See Documentation/scsi/aic7xxx.txt.
301 See Documentation/scsi/aic79xx.txt.
303 amd_iommu= [HW,X86-84]
304 Pass parameters to the AMD IOMMU driver in the system.
306 isolate - enable device isolation (each device, as far
307 as possible, will get its own protection
309 share - put every device behind one IOMMU into the
310 same protection domain
311 fullflush - enable flushing of IO/TLB entries when
312 they are unmapped. Otherwise they are
313 flushed before they will be reused, which
316 amd_iommu_size= [HW,X86-64]
317 Define the size of the aperture for the AMD IOMMU
318 driver. Possible values are:
319 '32M', '64M' (default), '128M', '256M', '512M', '1G'
321 amijoy.map= [HW,JOY] Amiga joystick support
322 Map of devices attached to JOY0DAT and JOY1DAT
324 See also Documentation/kernel/input/joystick.txt
326 analog.map= [HW,JOY] Analog joystick and gamepad support
327 Specifies type or capabilities of an analog joystick
328 connected to one of 16 gameports
329 Format: <type1>,<type2>,..<type16>
332 Power management functions (SPARCstation-4/5 + deriv.)
334 Disable APC CPU standby support. SPARCstation-Fox does
335 not play well with APC CPU idle - disable it if you have
336 APC and your system crashes randomly.
338 apic= [APIC,i386] Advanced Programmable Interrupt Controller
339 Change the output verbosity whilst booting
340 Format: { quiet (default) | verbose | debug }
341 Change the amount of debugging information output
342 when initialising the APIC and IO-APIC components.
344 apm= [APM] Advanced Power Management
345 See header of arch/x86/kernel/apm_32.c.
347 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
348 Format: <io>,<irq>,<nodeID>
352 atarimouse= [HW,MOUSE] Atari Mouse
354 atascsi= [HW,SCSI] Atari SCSI
356 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
357 EzKey and similar keyboards
359 atkbd.reset= [HW] Reset keyboard during initialization
361 atkbd.set= [HW] Select keyboard code set
362 Format: <int> (2 = AT (default), 3 = PS/2)
364 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
367 atkbd.softraw= [HW] Choose between synthetic and real raw mode
368 Format: <bool> (0 = real, 1 = synthetic (default))
370 atkbd.softrepeat= [HW]
371 Use software keyboard repeat
375 baycom_epp= [HW,AX25]
378 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
380 See header of drivers/net/hamradio/baycom_par.c.
382 baycom_ser_fdx= [HW,AX25]
383 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
384 Format: <io>,<irq>,<mode>[,<baud>]
385 See header of drivers/net/hamradio/baycom_ser_fdx.c.
387 baycom_ser_hdx= [HW,AX25]
388 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
389 Format: <io>,<irq>,<mode>
390 See header of drivers/net/hamradio/baycom_ser_hdx.c.
392 boot_delay= Milliseconds to delay each printk during boot.
393 Values larger than 10 seconds (10000) are changed to
397 bootmem_debug [KNL] Enable bootmem allocator debug messages.
399 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
400 bttv.radio= Most important insmod options are available as
402 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
403 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
406 See drivers/scsi/BusLogic.c, comment before function
407 BusLogic_ParseDriverOptions().
409 c101= [NET] Moxa C101 synchronous serial card
411 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
412 Sometimes CPU hardware bugs make them report the cache
413 size incorrectly. The kernel will attempt work arounds
414 to fix known problems, but for some CPUs it is not
415 possible to determine what the correct size should be.
416 This option provides an override for these situations.
418 security= [SECURITY] Choose a security module to enable at boot.
419 If this boot parameter is not specified, only the first
420 security module asking for security registration will be
421 loaded. An invalid security module name will be treated
422 as if no module has been chosen.
425 [SECURITY] Disable capabilities. This would normally
426 be used only if an alternative security model is to be
427 configured. Potentially dangerous and should only be
428 used if you are entirely sure of the consequences.
430 ccw_timeout_log [S390]
431 See Documentation/s390/CommonIO for details.
433 cgroup_disable= [KNL] Disable a particular controller
434 Format: {name of the controller(s) to disable}
435 {Currently supported controllers - "memory"}
437 checkreqprot [SELINUX] Set initial checkreqprot flag value.
438 Format: { "0" | "1" }
439 See security/selinux/Kconfig help text.
440 0 -- check protection applied by kernel (includes
441 any implied execute protection).
442 1 -- check protection requested by application.
443 Default value is set via a kernel config option.
444 Value can be changed at runtime via
445 /selinux/checkreqprot.
448 See Documentation/s390/CommonIO for details.
450 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
452 Forces specified clocksource (if available) to be used
453 when calculating gettimeofday(). If specified
454 clocksource is not available, it defaults to PIT.
455 Format: { pit | tsc | cyclone | pmtmr }
457 clocksource= [GENERIC_TIME] Override the default clocksource
459 Override the default clocksource and use the clocksource
460 with the name specified.
461 Some clocksource names to choose from, depending on
463 [all] jiffies (this is the base, fallback clocksource)
465 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
466 pxa_timer,timer3,32k_counter,timer0_1
468 [X86-32] pit,hpet,tsc,vmi-timer;
469 scx200_hrt on Geode; cyclone on IBM x440
477 clearcpuid=BITNUM [X86]
478 Disable CPUID feature X for the kernel. See
479 arch/x86/include/asm/cpufeature.h for the valid bit
480 numbers. Note the Linux specific bits are not necessarily
481 stable over kernel options, but the vendor specific
483 Also note that user programs calling CPUID directly
484 or using the feature without checking anything
485 will still see it. This just prevents it from
486 being used by the kernel or shown in /proc/cpuinfo.
487 Also note the kernel might malfunction if you disable
490 code_bytes [IA32/X86_64] How many bytes of object code to print
495 hpet= [X86-32,HPET] option to control HPET usage
496 Format: { enable (default) | disable | force }
497 disable: disable HPET and use PIT instead
498 force: allow force enabled of undocumented chips (ICH4,
501 com20020= [HW,NET] ARCnet - COM20020 chipset
503 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
505 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
509 ARCnet - COM90xx chipset (memory-mapped buffers)
510 Format: <io>[,<irq>[,<memstart>]]
512 condev= [HW,S390] console device
515 console= [KNL] Output console device and options.
517 tty<n> Use the virtual console device <n>.
521 Use the specified serial port. The options are of
522 the form "bbbbpnf", where "bbbb" is the baud rate,
523 "p" is parity ("n", "o", or "e"), "n" is number of
524 bits, and "f" is flow control ("r" for RTS or
525 omit it). Default is "9600n8".
527 See Documentation/serial-console.txt for more
529 Documentation/networking/netconsole.txt for an
532 uart[8250],io,<addr>[,options]
533 uart[8250],mmio,<addr>[,options]
534 Start an early, polled-mode console on the 8250/16550
535 UART at the specified I/O port or MMIO address,
536 switching to the matching ttyS device later. The
537 options are the same as for ttyS, above.
539 If the device connected to the port is not a TTY but a braille
540 device, prepend "brl," before the device type, for instance
542 For now, only VisioBraille is supported.
544 earlycon= [KNL] Output early console device and options.
545 uart[8250],io,<addr>[,options]
546 uart[8250],mmio,<addr>[,options]
547 Start an early, polled-mode console on the 8250/16550
548 UART at the specified I/O port or MMIO address.
549 The options are the same as for ttyS, above.
552 [HW] Never suspend the console
553 Disable suspending of consoles during suspend and
554 hibernate operations. Once disabled, debugging
555 messages can reach various consoles while the rest
556 of the system is being put to sleep (ie, while
557 debugging driver suspend/resume hooks). This may
558 not work reliably with all consoles, but is known
559 to work with serial and VGA consoles.
562 [KNL] Change the default value for
563 /proc/<pid>/coredump_filter.
564 See also Documentation/filesystems/proc.txt.
566 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
568 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
570 crashkernel=nn[KMG]@ss[KMG]
571 [KNL] Reserve a chunk of physical memory to
572 hold a kernel to switch to with kexec on panic.
574 crashkernel=range1:size1[,range2:size2,...][@offset]
575 [KNL] Same as above, but depends on the memory
576 in the running system. The syntax of range is
577 start-[end] where start and end are both
578 a memory unit (amount[KMG]). See also
579 Documentation/kdump/kdump.txt for a example.
584 cs89x0_media= [HW,NET]
585 Format: { rj45 | aui | bnc }
588 See header of drivers/s390/block/dasd_devmap.c.
590 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
591 (one device per port)
592 Format: <port#>,<type>
593 See also Documentation/input/joystick-parport.txt
595 debug [KNL] Enable kernel debugging (events log level).
598 [KNL] verbose self-tests
600 Print debugging info while doing the locking API
602 We default to 0 (no extra messages), setting it to
603 1 will print _a lot_ more information - normally
604 only useful to kernel developers.
606 debug_objects [KNL] Enable object debugging
608 debugpat [X86] Enable PAT debugging
610 decnet.addr= [HW,NET]
611 Format: <area>[,<node>]
612 See also Documentation/networking/decnet.txt.
615 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
616 Change the default blue palette of the console.
617 This is a 16-member array composed of values
621 Format: <green0>,<green1>,<green2>,...,<green15>
622 Change the default green palette of the console.
623 This is a 16-member array composed of values
627 Format: <red0>,<red1>,<red2>,...,<red15>
628 Change the default red palette of the console.
629 This is a 16-member array composed of values
635 Set system-wide default UTF-8 mode for all tty's.
636 Default is 1, i.e. UTF-8 mode is enabled for all
637 newly opened terminals.
640 Set number of hash buckets for dentry cache.
643 IO parameters + enable/disable command.
645 digiepca= [HW,SERIAL]
646 See drivers/char/README.epca and
647 Documentation/serial/digiepca.txt.
649 disable_mtrr_cleanup [X86]
650 enable_mtrr_cleanup [X86]
651 The kernel tries to adjust MTRR layout from continuous
652 to discrete, to make X server driver able to add WB
653 entry later. This parameter enables/disables that.
655 mtrr_chunk_size=nn[KMG] [X86]
656 used for mtrr cleanup. It is largest continous chunk
657 that could hold holes aka. UC entries.
659 mtrr_gran_size=nn[KMG] [X86]
660 Used for mtrr cleanup. It is granularity of mtrr block.
662 Large value could prevent small alignment from
665 mtrr_spare_reg_nr=n [X86]
667 Range: 0,7 : spare reg number
669 Used for mtrr cleanup. It is spare mtrr entries number.
670 Set to 2 or more if your graphical card needs more.
672 disable_mtrr_trim [X86, Intel and AMD only]
673 By default the kernel will trim any uncacheable
674 memory out of your available memory pool based on
675 MTRR settings. This parameter disables that behavior,
676 possibly causing your machine to run very slowly.
678 dmasound= [HW,OSS] Sound subsystem buffers
684 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
686 earlyprintk=serial[,ttySn[,baudrate]]
689 Append ",keep" to not disable it when the real console
692 Only vga or serial or usb debug port at a time.
694 Currently only ttyS0 and ttyS1 are supported.
696 Interaction with the standard serial driver is not
699 The VGA output is eventually overwritten by the real
705 Format: {"off" | "on" | "skip[mbr]"}
707 eisa_irq_edge= [PARISC,HW]
708 See header of drivers/parisc/eisa.c.
711 See comment before function elanfreq_setup() in
712 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
715 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
716 See Documentation/block/as-iosched.txt and
717 Documentation/block/deadline-iosched.txt for details.
719 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
720 Specifies physical address of start of kernel core
721 image elf header. Generally kexec loader will
722 pass this option to capture kernel.
723 See Documentation/kdump/kdump.txt for details.
725 enforcing [SELINUX] Set initial enforcing status.
727 See security/selinux/Kconfig help text.
728 0 -- permissive (log only, no denials).
729 1 -- enforcing (deny and log).
731 Value can be changed at runtime via /selinux/enforce.
733 ether= [HW,NET] Ethernet cards parameters
734 This option is obsoleted by the "netdev=" option, which
735 has equivalent usage. See its documentation for details.
737 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
742 fail_make_request=[KNL]
743 General fault injection mechanism.
744 Format: <interval>,<probability>,<space>,<times>
745 See also /Documentation/fault-injection/.
748 See header of drivers/scsi/fd_mcs.c.
751 See header of drivers/scsi/fdomain.c.
754 See Documentation/blockdev/floppy.txt.
756 force_pal_cache_flush
757 [IA-64] Avoid check_sal_cache_flush which may hang on
758 buggy SAL_CACHE_FLUSH implementations. Using this
759 parameter will force ia64_sal_cache_flush to call
760 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
763 [ftrace] will set and start the specified tracer
764 as early as possible in order to facilitate early
768 [ftrace] will dump the trace buffers on oops.
771 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
772 support via parallel port (up to 5 devices per port)
773 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
774 See also Documentation/input/joystick-parport.txt
778 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
783 See header of drivers/scsi/gdth.c.
785 gpt [EFI] Forces disk with valid GPT signature but
786 invalid Protective MBR to be treated as GPT.
790 hashdist= [KNL,NUMA] Large hashes allocated during boot
791 are distributed across NUMA nodes. Defaults on
792 for IA-64, off otherwise.
793 Format: 0 | 1 (for off | on)
795 hcl= [IA-64] SGI's Hardware Graph compatibility layer
797 hd= [EIDE] (E)IDE hard drive subsystem geometry
798 Format: <cyl>,<head>,<sect>
800 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
801 size of <nn>. This works even on boxes that have no
802 highmem otherwise. This also works to reduce highmem
803 size on bigger boxes.
805 highres= [KNL] Enable/disable high resolution timer mode.
806 Valid parameters: "on", "off"
810 See Documentation/isdn/README.HiSax.
812 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
813 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
814 On x86-64 and powerpc, this option can be specified
815 multiple times interleaved with hugepages= to reserve
816 huge pages of different sizes. Valid pages sizes on
817 x86-64 are 2M (when the CPU supports "pse") and 1G
818 (when the CPU supports the "pdpe1gb" cpuinfo flag)
819 Note that 1GB pages can only be allocated at boot time
820 using hugepages= and not freed afterwards.
822 [same as hugepagesz=] The size of the default
823 HugeTLB page size. This is the size represented by
824 the legacy /proc/ hugepages APIs, used for SHM, and
825 default size when mounting hugetlbfs filesystems.
826 Defaults to the default architecture's huge page size
831 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
832 terminal devices. Valid values: 0..8
834 i8042.debug [HW] Toggle i8042 debug mode
835 i8042.direct [HW] Put keyboard port into non-translated mode
836 i8042.dumbkbd [HW] Pretend that controller can only read data from
837 keyboard and cannot control its state
838 (Don't attempt to blink the leds)
839 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
840 i8042.nokbd [HW] Don't check/create keyboard port
841 i8042.noloop [HW] Disable the AUX Loopback command while probing
843 i8042.nomux [HW] Don't check presence of an active multiplexing
845 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
848 [HW] Frequency with which keyboard LEDs should blink
849 when kernel panics (default is 0.5 sec)
850 i8042.reset [HW] Reset the controller during init and cleanup
851 i8042.unlock [HW] Unlock (ignore) the keylock
855 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
856 indicates that the driver is running on unsupported
858 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
859 does not match list of supported models.
861 [HW] Report power status in /proc/i8k
862 (disabled by default)
863 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
866 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
867 See Documentation/mca.txt.
870 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
872 ide-core.nodma= [HW] (E)IDE subsystem
873 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
874 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
875 .chs .ignore_cable are additional options
876 See Documentation/ide/ide.txt.
878 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
879 See Documentation/ide/ide.txt.
882 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
883 Poll forces a polling idle loop that can slightly
884 improve the performance of waking up a idle CPU, but
885 will use a lot of power and make the system run hot.
887 idle=mwait: On systems which support MONITOR/MWAIT but
888 the kernel chose to not use it because it doesn't save
889 as much power as a normal idle loop, use the
890 MONITOR/MWAIT idle loop anyways. Performance should be
891 the same as idle=poll.
892 idle=halt: Halt is forced to be used for CPU idle.
893 In such case C2/C3 won't be used again.
894 idle=nomwait: Disable mwait for CPU C-states
896 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
897 Claim all unknown PCI IDE storage controllers.
899 ignore_loglevel [KNL]
900 Ignore loglevel setting - this will print /all/
901 kernel messages to the console. Useful for debugging.
904 Set number of hash buckets for inode cache.
907 Format: { "0" | "1" }
908 0 -- integrity auditing messages. (Default)
909 1 -- enable informational integrity auditing messages.
912 Formt: { "sha1" | "md5" }
916 See header of drivers/scsi/in2000.c.
920 Run specified binary instead of /sbin/init as init
923 initcall_debug [KNL] Trace initcalls as they are executed. Useful
924 for working out where the kernel is dying during
927 initrd= [BOOT] Specify the location of the initial ramdisk
929 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
934 iomem= Disable strict checking of access to MMIO memory
935 strict regions from userspace.
951 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
953 Enable intel iommu driver.
955 Disable intel iommu driver.
956 igfx_off [Default Off]
957 By default, gfx is mapped as normal device. If a gfx
958 device has a dedicated DMAR unit, the DMAR unit is
959 bypassed by not enabling DMAR with this option. In
960 this case, gfx device will use physical address for
963 With this option iommu will not optimize to look
964 for io virtual address below 32 bit forcing dual
965 address cycle on pci bus for cards supporting greater
966 than 32 bit addressing. The default is to look
967 for translation below 32 bit and if not available
968 then look in the higher range.
970 With this option on every unmap_single operation will
971 result in a hardware IOTLB flush operation as opposed
972 to batching them for performance.
974 io_delay= [X86-32,X86-64] I/O delay method
976 Standard port 0x80 based delay
978 Alternate port 0xed based delay (needed on some systems)
980 Simple two microseconds delay
984 io7= [HW] IO7 for Marvel based alpha systems
985 See comment before marvel_specify_io7 in
986 arch/alpha/kernel/core_marvel.c.
989 See Documentation/filesystems/nfsroot.txt.
991 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
992 See comment before ip2_setup() in
993 drivers/char/ip2/ip2base.c.
995 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
996 See header of drivers/scsi/ips.c.
998 ports= [IP_VS_FTP] IPVS ftp helper module
1000 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1002 Format: <port>,<port>....
1005 When an interrupt is not handled search all handlers
1006 for it. Intended to get systems with badly broken
1010 When an interrupt is not handled search all handlers
1011 for it. Also check all handlers each timer
1012 interrupt. Intended to get systems with badly broken
1016 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1018 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1020 <cpu number>,...,<cpu number>
1022 <cpu number>-<cpu number>
1023 (must be a positive range in ascending order)
1025 <cpu number>,...,<cpu number>-<cpu number>
1027 This option can be used to specify one or more CPUs
1028 to isolate from the general SMP balancing and scheduling
1029 algorithms. You can move a process onto or off an
1030 "isolated" CPU via the CPU affinity syscalls or cpuset.
1031 <cpu number> begins at 0 and the maximum value is
1032 "number of CPUs in system - 1".
1034 This option is the preferred way to isolate CPUs. The
1035 alternative -- manually setting the CPU mask of all
1036 tasks in the system -- can cause problems and
1037 suboptimal load balancer performance.
1041 js= [HW,JOY] Analog joystick
1042 See Documentation/input/joystick.txt.
1044 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1045 specifies the amount of memory usable by the kernel
1046 for non-movable allocations. The requested amount is
1047 spread evenly throughout all nodes in the system. The
1048 remaining memory in each node is used for Movable
1049 pages. In the event, a node is too small to have both
1050 kernelcore and Movable pages, kernelcore pages will
1051 take priority and other nodes will have a larger number
1052 of kernelcore pages. The Movable zone is used for the
1053 allocation of pages that may be reclaimed or moved
1054 by the page migration subsystem. This means that
1055 HugeTLB pages may not be allocated from this zone.
1056 Note that allocations like PTEs-from-HighMem still
1057 use the HighMem zone if it exists, and the Normal
1058 zone if it does not.
1060 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1061 is similar to kernelcore except it specifies the
1062 amount of memory used for migratable allocations.
1063 If both kernelcore and movablecore is specified,
1064 then kernelcore will be at *least* the specified
1065 value but may be more. If movablecore on its own
1066 is specified, the administrator must be careful
1067 that the amount of memory usable for all allocations
1072 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1075 kgdboc= [HW] kgdb over consoles.
1076 Requires a tty driver that supports console polling.
1077 (only serial suported for now)
1078 Format: <serial_device>[,baud]
1080 kmac= [MIPS] korina ethernet MAC address.
1081 Configure the RouterBoard 532 series on-chip
1082 Ethernet adapter MAC address.
1088 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1091 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1094 libata.dma= [LIBATA] DMA control
1095 libata.dma=0 Disable all PATA and SATA DMA
1096 libata.dma=1 PATA and SATA Disk DMA only
1097 libata.dma=2 ATAPI (CDROM) DMA only
1098 libata.dma=4 Compact Flash DMA only
1099 Combinations also work, so libata.dma=3 enables DMA
1100 for disks and CDROMs, but not CFs.
1102 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1106 libata.force= [LIBATA] Force configurations. The format is comma
1107 separated list of "[ID:]VAL" where ID is
1108 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1109 matching port, link or device. Basically, it matches
1110 the ATA ID string printed on console by libata. If
1111 the whole ID part is omitted, the last PORT and DEVICE
1112 values are used. If ID hasn't been specified yet, the
1113 configuration applies to all ports, links and devices.
1115 If only DEVICE is omitted, the parameter applies to
1116 the port and all links and devices behind it. DEVICE
1117 number of 0 either selects the first device or the
1118 first fan-out link behind PMP device. It does not
1119 select the host link. DEVICE number of 15 selects the
1120 host link and device attached to it.
1122 The VAL specifies the configuration to force. As long
1123 as there's no ambiguity shortcut notation is allowed.
1124 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1125 The following configurations can be forced.
1127 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1128 Any ID with matching PORT is used.
1130 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1132 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1133 udma[/][16,25,33,44,66,100,133] notation is also
1136 * [no]ncq: Turn on or off NCQ.
1138 * nohrst, nosrst, norst: suppress hard, soft
1141 If there are multiple matching configurations changing
1142 the same attribute, the last one is used.
1144 lmb=debug [KNL] Enable lmb debug messages.
1146 load_ramdisk= [RAM] List of ramdisks to load from floppy
1147 See Documentation/blockdev/ramdisk.txt.
1149 lockd.nlm_grace_period=P [NFS] Assign grace period.
1152 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1155 lockd.nlm_timeout=T [NFS] Assign timeout value.
1158 lockd.nlm_udpport=M [NFS] Assign UDP port.
1161 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1164 loglevel= All Kernel Messages with a loglevel smaller than the
1165 console loglevel will be printed to the console. It can
1166 also be changed with klogd or other programs. The
1167 loglevels are defined as follows:
1169 0 (KERN_EMERG) system is unusable
1170 1 (KERN_ALERT) action must be taken immediately
1171 2 (KERN_CRIT) critical conditions
1172 3 (KERN_ERR) error conditions
1173 4 (KERN_WARNING) warning conditions
1174 5 (KERN_NOTICE) normal but significant condition
1175 6 (KERN_INFO) informational
1176 7 (KERN_DEBUG) debug-level messages
1178 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1179 Format: { n | nk | nM }
1180 n must be a power of two. The default size
1181 is set in the kernel config file.
1183 logo.nologo [FB] Disables display of the built-in Linux logo.
1184 This may be used to provide more screen space for
1185 kernel log messages and is useful when debugging
1186 kernel boot problems.
1188 lp=0 [LP] Specify parallel ports to use, e.g,
1189 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1190 lp=reset first parallel port). 'lp=0' disables the
1191 lp=auto printer driver. 'lp=reset' (which can be
1192 specified in addition to the ports) causes
1193 attached printers to be reset. Using
1194 lp=port1,port2,... specifies the parallel ports
1195 to associate lp devices with, starting with
1196 lp0. A port specification may be 'none' to skip
1197 that lp device, or a parport name such as
1198 'parport0'. Specifying 'lp=auto' instead of a
1199 port specification list means that device IDs
1200 from each port should be examined, to see if
1201 an IEEE 1284-compliant printer is attached; if
1202 so, the driver will manage that printer.
1203 See also header of drivers/char/lp.c.
1206 Sets loops_per_jiffy to given constant, thus avoiding
1207 time-consuming boot-time autodetection (up to 250 ms per
1208 CPU). 0 enables autodetection (default). To determine
1209 the correct value for your kernel, boot with normal
1210 autodetection and see what value is printed. Note that
1211 on SMP systems the preset will be applied to all CPUs,
1212 which is likely to cause problems if your CPUs need
1213 significantly divergent settings. An incorrect value
1214 will cause delays in the kernel to be wrong, leading to
1215 unpredictable I/O errors and other breakage. Although
1216 unlikely, in the extreme case this might damage your
1220 Format: <io>,<irq>,<dma>
1222 mac5380= [HW,SCSI] Format:
1223 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1225 machvec= [IA64] Force the use of a particular machine-vector
1226 (machvec) in a generic kernel.
1227 Example: machvec=hpzx1_swiotlb
1229 max_loop= [LOOP] Maximum number of loopback devices that can
1233 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1234 should make use of. maxcpus=n : n >= 0 limits the
1235 kernel to using 'n' processors. n=0 is a special case,
1236 it is equivalent to "nosmp", which also disables
1239 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1240 or equal to this physical address is ignored.
1242 max_luns= [SCSI] Maximum number of LUNs to probe.
1243 Should be between 1 and 2^32-1.
1246 [SCSI] Maximum number of LUNs received.
1247 Should be between 1 and 16384.
1251 mce [X86-32] Machine Check Exception
1253 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1255 md= [HW] RAID subsystems devices and level
1256 See Documentation/md.txt.
1259 Format: <first>,<last>
1260 Specifies range of consoles to be captured by the MDA.
1262 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1263 Amount of memory to be used when the kernel is not able
1264 to see the whole system memory or for test.
1265 [X86-32] Use together with memmap= to avoid physical
1266 address space collisions. Without memmap= PCI devices
1267 could be placed at addresses belonging to unused RAM.
1269 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1273 [KNL,SH] Allow user to override the default size for
1274 per-device physically contiguous DMA buffers.
1276 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1277 E820 memory map, as specified by the user.
1278 Such memmap=exactmap lines can be constructed based on
1279 BIOS output or other requirements. See the memmap=nn@ss
1282 memmap=nn[KMG]@ss[KMG]
1283 [KNL] Force usage of a specific region of memory
1284 Region of memory to be used, from ss to ss+nn.
1286 memmap=nn[KMG]#ss[KMG]
1287 [KNL,ACPI] Mark specific memory as ACPI data.
1288 Region of memory to be used, from ss to ss+nn.
1290 memmap=nn[KMG]$ss[KMG]
1291 [KNL,ACPI] Mark specific memory as reserved.
1292 Region of memory to be used, from ss to ss+nn.
1293 Example: Exclude memory from 0x18690000-0x1869ffff
1294 memmap=64K$0x18690000
1296 memmap=0x10000$0x18690000
1298 memory_corruption_check=0/1 [X86]
1299 Some BIOSes seem to corrupt the first 64k of
1300 memory when doing things like suspend/resume.
1301 Setting this option will scan the memory
1302 looking for corruption. Enabling this will
1303 both detect corruption and prevent the kernel
1304 from using the memory being corrupted.
1305 However, its intended as a diagnostic tool; if
1306 repeatable BIOS-originated corruption always
1307 affects the same memory, you can use memmap=
1308 to prevent the kernel from using that memory.
1310 memory_corruption_check_size=size [X86]
1311 By default it checks for corruption in the low
1312 64k, making this memory unavailable for normal
1313 use. Use this parameter to scan for
1314 corruption in more or less memory.
1316 memory_corruption_check_period=seconds [X86]
1317 By default it checks for corruption every 60
1318 seconds. Use this parameter to check at some
1319 other rate. 0 disables periodic checking.
1321 memtest= [KNL,X86] Enable memtest
1323 range: 0,4 : pattern number
1324 default : 0 <disable>
1326 meye.*= [HW] Set MotionEye Camera parameters
1327 See Documentation/video4linux/meye.txt.
1329 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1330 Multi-Function General Purpose Timers on AMD Geode
1333 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1334 the BIOS has incorrectly applied a workaround. TinyBIOS
1335 version 0.98 is known to be affected, 0.99 fixes the
1336 problem by letting the user disable the workaround.
1340 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1341 physical address is ignored.
1344 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1345 parameter allows control of the logging verbosity for
1346 the additional memory initialisation checks. A value
1347 of 0 disables mminit logging and a level of 4 will
1348 log everything. Information is printed at KERN_DEBUG
1349 so loglevel=8 may also need to be specified.
1352 [MOUSE] Maximum time between finger touching and
1353 leaving touchpad surface for touch to be considered
1354 a tap and be reported as a left button click (for
1355 touchpads working in absolute mode only).
1357 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1358 reporting absolute coordinates, such as tablets
1359 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1360 reporting absolute coordinates, such as tablets
1365 MTD_Partition= [MTD]
1366 Format: <name>,<region-number>,<size>,<offset>
1368 MTD_Region= [MTD] Format:
1369 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1372 See drivers/mtd/cmdlinepart.c.
1375 ARM/S3C2412 JIVE boot control
1377 See arch/arm/mach-s3c2412/mach-jive.c
1379 mtouchusb.raw_coordinates=
1380 [HW] Make the MicroTouch USB driver use raw coordinates
1381 ('y', default) or cooked coordinates ('n')
1383 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1386 See header of drivers/scsi/NCR_D700.c.
1390 ncr53c400= [HW,SCSI]
1392 ncr53c400a= [HW,SCSI]
1394 ncr53c406a= [HW,SCSI]
1396 ncr53c8xx= [HW,SCSI]
1398 netdev= [NET] Network devices parameters
1399 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1400 Note that mem_start is often overloaded to mean
1401 something different and driver-specific.
1402 This usage is only documented in each driver source
1406 [NETFILTER] Enable connection tracking flow accounting
1407 0 to disable accounting
1408 1 to enable accounting
1409 Default value depends on CONFIG_NF_CT_ACCT that is
1410 going to be removed in 2.6.29.
1413 See Documentation/filesystems/nfsroot.txt.
1415 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1416 See Documentation/filesystems/nfsroot.txt.
1418 nfs.callback_tcpport=
1419 [NFS] set the TCP port on which the NFSv4 callback
1420 channel should listen.
1422 nfs.idmap_cache_timeout=
1423 [NFS] set the maximum lifetime for idmapper cache
1427 [NFS] enable 64-bit inode numbers.
1428 If zero, the NFS client will fake up a 32-bit inode
1429 number for the readdir() and stat() syscalls instead
1430 of returning the full 64-bit number.
1431 The default is to return 64-bit inode numbers.
1433 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1434 when a NMI is triggered.
1435 Format: [state][,regs][,debounce][,die]
1437 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1438 Format: [panic,][num]
1440 0 - turn nmi_watchdog off
1441 1 - use the IO-APIC timer for the NMI watchdog
1442 2 - use the local APIC for the NMI watchdog using
1443 a performance counter. Note: This will use one performance
1444 counter and the local APIC's performance vector.
1445 When panic is specified panic when an NMI watchdog timeout occurs.
1446 This is useful when you use a panic=... timeout and need the box
1448 Instead of 1 and 2 it is possible to use the following
1449 symbolic names: lapic and ioapic
1450 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1452 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1453 emulation library even if a 387 maths coprocessor
1456 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1457 caches in the slab allocator. Saves per-node memory,
1458 but will impact performance.
1462 noapic [SMP,APIC] Tells the kernel to not make use of any
1463 IOAPICs that may be present in the system.
1465 nobats [PPC] Do not use BATs for mapping kernel lowmem
1466 on "Classic" PPC cores.
1470 nodelayacct [KNL] Disable per-task delay accounting
1472 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1474 nodsp [SH] Disable hardware DSP at boot time.
1476 noefi [X86-32,X86-64] Disable EFI runtime services support.
1480 noexec [X86-32,X86-64]
1481 On X86-32 available only on PAE configured kernels.
1482 noexec=on: enable non-executable mappings (default)
1483 noexec=off: disable non-executable mappings
1486 This affects only 32-bit executables.
1487 noexec32=on: enable non-executable mappings (default)
1488 read doesn't imply executable mappings
1489 noexec32=off: disable non-executable mappings
1490 read implies executable mappings
1492 nofpu [SH] Disable hardware FPU at boot time.
1494 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1495 register save and restore. The kernel will only save
1496 legacy floating-point registers on task switch.
1498 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1502 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1503 instruction doesn't work correctly and not to
1506 no_file_caps Tells the kernel not to honor file capabilities. The
1507 only way then for a file to be executed with privilege
1508 is to be setuid root or executed by root.
1510 nohalt [IA-64] Tells the kernel not to use the power saving
1511 function PAL_HALT_LIGHT when idle. This increases
1512 power-consumption. On the positive side, it reduces
1513 interrupt wake-up latency, which may improve performance
1514 in certain environments such as networked servers or
1517 nohz= [KNL] Boottime enable/disable dynamic ticks
1518 Valid arguments: on, off
1521 noirqdebug [X86-32] Disables the code which attempts to detect and
1522 disable unhandled interrupt sources.
1524 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1525 broken timer IRQ sources.
1527 noisapnp [ISAPNP] Disables ISA PnP code.
1529 noinitrd [RAM] Tells the kernel not to load any configured
1534 nojitter [IA64] Disables jitter checking for ITC timers.
1536 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1538 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1540 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1542 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1543 default x2apic cluster mode on platforms
1546 noltlbs [PPC] Do not use large page/tlb entries for kernel
1547 lowmem mapping on PPC40x.
1549 nomca [IA-64] Disable machine check abort handling
1551 nomce [X86-32] Machine Check Exception
1553 nomfgpt [X86-32] Disable Multi-Function General Purpose
1554 Timer usage (for AMD Geode machines).
1556 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1558 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1559 with UP alternatives
1561 noresidual [PPC] Don't use residual data on PReP machines.
1563 noresume [SWSUSP] Disables resume and restores original swap
1566 no-scroll [VGA] Disables scrollback.
1567 This is required for the Braillex ib80-piezo Braille
1568 reader made by F.H. Papenmeier (Germany).
1572 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1574 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1575 and disable the IO APIC. legacy for "maxcpus=0".
1577 nosoftlockup [KNL] Disable the soft-lockup detector.
1579 noswapaccount [KNL] Disable accounting of swap in memory resource
1580 controller. (See Documentation/controllers/memory.txt)
1582 nosync [HW,M68K] Disables sync negotiation for all devices.
1584 notsc [BUGS=X86-32] Disable Time Stamp Counter
1586 nousb [USB] Disable the USB subsystem
1590 nptcg= [IA64] Override max number of concurrent global TLB
1591 purges which is reported from either PAL_VM_SUMMARY or
1594 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1595 one of ['zone', 'node', 'default'] can be specified
1596 This can be set from sysctl after boot.
1597 See Documentation/sysctl/vm.txt for details.
1599 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1601 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1602 See Documentation/debugging-via-ohci1394.txt for more
1605 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1606 Rather than timing out after 20 ms if an EC
1607 command is not properly ACKed, override the length
1608 of the timeout. We have interrupts disabled while
1609 waiting for the ACK, so if this is set too high
1610 interrupts *may* be lost!
1615 oprofile.timer= [HW]
1616 Use timer interrupt instead of performance counters
1618 osst= [HW,SCSI] SCSI Tape Driver
1619 Format: <buffer_size>,<write_threshold>
1620 See also Documentation/scsi/st.txt.
1622 panic= [KNL] Kernel behaviour on panic
1625 parkbd.port= [HW] Parallel port number the keyboard adapter is
1626 connected to, default is 0.
1628 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1629 0 for XT, 1 for AT (default is AT).
1632 parport= [HW,PPT] Specify parallel ports. 0 disables.
1633 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1634 Use 'auto' to force the driver to use any
1635 IRQ/DMA settings detected (the default is to
1636 ignore detected IRQ/DMA settings because of
1637 possible conflicts). You can specify the base
1638 address, IRQ, and DMA settings; IRQ and DMA
1639 should be numbers, or 'auto' (for using detected
1640 settings on that particular port), or 'nofifo'
1641 (to avoid using a FIFO even if it is detected).
1642 Parallel ports are assigned in the order they
1643 are specified on the command line, starting
1646 parport_init_mode= [HW,PPT]
1647 Configure VIA parallel port to operate in
1648 a specific mode. This is necessary on Pegasos
1649 computer where firmware has no options for setting
1650 up parallel port mode and sets it to spp.
1651 Currently this function knows 686a and 8231 chips.
1652 Format: [spp|ps2|epp|ecp|ecpepp]
1654 pas2= [HW,OSS] Format:
1655 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1658 See header of drivers/scsi/pas16.c.
1661 Halt all CPUs after the first oops has been printed for
1662 the specified number of seconds. This is to be used if
1663 your oopses keep scrolling off the screen.
1668 See header of drivers/block/paride/pcd.c.
1669 See also Documentation/blockdev/paride.txt.
1671 pci=option[,option...] [PCI] various PCI subsystem options:
1672 off [X86] don't probe for the PCI bus
1673 bios [X86-32] force use of PCI BIOS, don't access
1674 the hardware directly. Use this if your machine
1675 has a non-standard PCI host bridge.
1676 nobios [X86-32] disallow use of PCI BIOS, only direct
1677 hardware access methods are allowed. Use this
1678 if you experience crashes upon bootup and you
1679 suspect they are caused by the BIOS.
1680 conf1 [X86] Force use of PCI Configuration
1682 conf2 [X86] Force use of PCI Configuration
1684 noaer [PCIE] If the PCIEAER kernel config parameter is
1685 enabled, this kernel boot option can be used to
1686 disable the use of PCIE advanced error reporting.
1687 nodomains [PCI] Disable support for multiple PCI
1688 root domains (aka PCI segments, in ACPI-speak).
1689 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1691 nomsi [MSI] If the PCI_MSI kernel config parameter is
1692 enabled, this kernel boot option can be used to
1693 disable the use of MSI interrupts system-wide.
1694 noioapicquirk [APIC] Disable all boot interrupt quirks.
1695 Safety option to keep boot IRQs enabled. This
1696 should never be necessary.
1697 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1698 primary IO-APIC for bridges that cannot disable
1699 boot IRQs. This fixes a source of spurious IRQs
1700 when the system masks IRQs.
1701 noioapicreroute [APIC] Disable workaround that uses the
1702 boot IRQ equivalent of an IRQ that connects to
1703 a chipset where boot IRQs cannot be disabled.
1704 The opposite of ioapicreroute.
1705 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1706 routing table. These calls are known to be buggy
1707 on several machines and they hang the machine
1708 when used, but on other computers it's the only
1709 way to get the interrupt routing table. Try
1710 this option if the kernel is unable to allocate
1711 IRQs or discover secondary PCI buses on your
1713 rom [X86] Assign address space to expansion ROMs.
1714 Use with caution as certain devices share
1715 address decoders between ROMs and other
1717 norom [X86] Do not assign address space to
1718 expansion ROMs that do not already have
1719 BIOS assigned address ranges.
1720 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1721 assigned automatically to PCI devices. You can
1722 make the kernel exclude IRQs of your ISA cards
1724 pirqaddr=0xAAAAA [X86] Specify the physical address
1725 of the PIRQ table (normally generated
1726 by the BIOS) if it is outside the
1727 F0000h-100000h range.
1728 lastbus=N [X86] Scan all buses thru bus #N. Can be
1729 useful if the kernel is unable to find your
1730 secondary buses and you want to tell it
1731 explicitly which ones they are.
1732 assign-busses [X86] Always assign all PCI bus
1733 numbers ourselves, overriding
1734 whatever the firmware may have done.
1735 usepirqmask [X86] Honor the possible IRQ mask stored
1736 in the BIOS $PIR table. This is needed on
1737 some systems with broken BIOSes, notably
1738 some HP Pavilion N5400 and Omnibook XE3
1739 notebooks. This will have no effect if ACPI
1740 IRQ routing is enabled.
1741 noacpi [X86] Do not use ACPI for IRQ routing
1742 or for PCI scanning.
1743 use_crs [X86] Use _CRS for PCI resource
1745 routeirq Do IRQ routing for all PCI devices.
1746 This is normally done in pci_enable_device(),
1747 so this option is a temporary workaround
1748 for broken drivers that don't call it.
1749 skip_isa_align [X86] do not align io start addr, so can
1750 handle more pci cards
1751 firmware [ARM] Do not re-enumerate the bus but instead
1752 just use the configuration from the
1753 bootloader. This is currently used on
1754 IXP2000 systems where the bus has to be
1755 configured a certain way for adjunct CPUs.
1756 noearly [X86] Don't do any early type 1 scanning.
1757 This might help on some broken boards which
1758 machine check when some devices' config space
1759 is read. But various workarounds are disabled
1760 and some IOMMU drivers will not work.
1761 bfsort Sort PCI devices into breadth-first order.
1762 This sorting is done to get a device
1763 order compatible with older (<= 2.4) kernels.
1764 nobfsort Don't sort PCI devices into breadth-first order.
1765 cbiosize=nn[KMG] The fixed amount of bus space which is
1766 reserved for the CardBus bridge's IO window.
1767 The default value is 256 bytes.
1768 cbmemsize=nn[KMG] The fixed amount of bus space which is
1769 reserved for the CardBus bridge's memory
1770 window. The default value is 64 megabytes.
1772 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1775 force Enable ASPM even on devices that claim not to support it.
1776 WARNING: Forcing ASPM on may cause system lockups.
1778 pcmv= [HW,PCMCIA] BadgePAD 4
1781 See Documentation/blockdev/paride.txt.
1783 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1786 See arch/parisc/kernel/pdc_chassis.c
1789 See Documentation/blockdev/paride.txt.
1792 See Documentation/blockdev/paride.txt.
1794 pirq= [SMP,APIC] Manual mp-table setup
1795 See Documentation/x86/i386/IO-APIC.txt.
1797 plip= [PPT,NET] Parallel port network link
1798 Format: { parport<nr> | timid | 0 }
1799 See also Documentation/parport.txt.
1801 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1802 Override pmtimer IOPort with a hex value.
1806 Enable PNP debug messages. This depends on the
1807 CONFIG_PNP_DEBUG_MESSAGES option.
1813 { on | off | curr | res | no-curr | no-res }
1816 [ISAPNP] Exclude IRQs for the autoconfiguration
1819 [ISAPNP] Exclude DMAs for the autoconfiguration
1821 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1822 Ranges are in pairs (I/O port base and size).
1825 [ISAPNP] Exclude memory regions for the
1827 Ranges are in pairs (memory base and size).
1829 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1830 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1831 These can also be switched on/off via
1832 <debugfs>/dynamic_printk/modules
1834 print-fatal-signals=
1835 [KNL] debug: print fatal signals
1836 print-fatal-signals=1: print segfault info to
1840 printk.time= Show timing data prefixed to each printk message line
1841 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1843 profile= [KNL] Enable kernel profiling via /proc/profile
1844 Format: [schedule,]<number>
1845 Param: "schedule" - profile schedule points.
1846 Param: <number> - step/bucket size as a power of 2 for
1847 statistical time based profiling.
1848 Param: "sleep" - profile D-state sleeping (millisecs).
1849 Requires CONFIG_SCHEDSTATS
1850 Param: "kvm" - profile VM exits.
1852 processor.max_cstate= [HW,ACPI]
1853 Limit processor to maximum C-state
1854 max_cstate=9 overrides any DMI blacklist limit.
1856 processor.nocst [HW,ACPI]
1857 Ignore the _CST method to determine C-states,
1858 instead using the legacy FADT method
1860 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1862 See Documentation/blockdev/ramdisk.txt.
1864 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1865 probe for; one of (bare|imps|exps|lifebook|any).
1866 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1868 psmouse.resetafter= [HW,MOUSE]
1869 Try to reset the device after so many bad packets
1872 [HW,MOUSE] Set desired mouse resolution, in dpi.
1873 psmouse.smartscroll=
1874 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1875 0 = disabled, 1 = enabled (default).
1877 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1879 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1882 See Documentation/blockdev/paride.txt.
1885 [KNL] Number of legacy pty's. Overwrites compiled-in
1888 quiet [KNL] Disable most log messages
1893 See Documentation/md.txt.
1895 ramdisk_blocksize= [RAM]
1896 See Documentation/blockdev/ramdisk.txt.
1898 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1899 See Documentation/blockdev/ramdisk.txt.
1901 rcupdate.blimit= [KNL,BOOT]
1902 Set maximum number of finished RCU callbacks to process
1905 rcupdate.qhimark= [KNL,BOOT]
1906 Set threshold of queued
1907 RCU callbacks over which batch limiting is disabled.
1909 rcupdate.qlowmark= [KNL,BOOT]
1910 Set threshold of queued RCU callbacks below which
1911 batch limiting is re-enabled.
1915 Run specified binary instead of /init from the ramdisk,
1916 used for early userspace startup. See initrd.
1918 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1919 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1920 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1923 [KNL, SMP] Set scheduler's default relax_domain_level.
1924 See Documentation/cpusets.txt.
1926 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1928 reservetop= [X86-32]
1930 Reserves a hole at the top of the kernel virtual
1933 reset_devices [KNL] Force drivers to reset the underlying device
1934 during initialization.
1937 Specify the partition device for software suspend
1939 resume_offset= [SWSUSP]
1940 Specify the offset from the beginning of the partition
1941 given by "resume=" at which the swap header is located,
1942 in <PAGE_SIZE> units (needed only for swap files).
1943 See Documentation/power/swsusp-and-swap-files.txt
1945 retain_initrd [RAM] Keep initrd memory after extraction
1947 rhash_entries= [KNL,NET]
1948 Set number of hash buckets for route cache
1950 riscom8= [HW,SERIAL]
1951 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1953 ro [KNL] Mount root device read-only on boot
1955 root= [KNL] Root filesystem
1957 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1958 mount the root filesystem
1960 rootflags= [KNL] Set root filesystem mount option string
1962 rootfstype= [KNL] Set root filesystem type
1964 rootwait [KNL] Wait (indefinitely) for root device to show up.
1965 Useful for devices that are detected asynchronously
1966 (e.g. USB and MMC devices).
1968 root_plug.vendor_id=
1969 [ROOTPLUG] Override the default vendor ID
1971 root_plug.product_id=
1972 [ROOTPLUG] Override the default product ID
1975 [ROOTPLUG] Enable debugging output
1977 rw [KNL] Mount root device read-write on boot
1979 S [KNL] Run init in single mode
1982 See drivers/net/irda/sa1100_ir.c.
1984 sbni= [NET] Granch SBNI12 leased line adapter
1986 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1987 Format: <io>[,<timeout>[,<isapnp>]]
1989 scsi_debug_*= [SCSI]
1990 See drivers/scsi/scsi_debug.c.
1992 scsi_default_dev_flags=
1993 [SCSI] SCSI default device flags
1996 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1997 Format: <vendor>:<model>:<flags>
1998 (flags are integer value)
2000 scsi_logging_level= [SCSI] a bit mask of logging levels
2001 See drivers/scsi/scsi_logging.h for bits. Also
2002 settable via sysctl at dev.scsi.logging_level
2003 (/proc/sys/dev/scsi/logging_level).
2004 There is also a nice 'scsi_logging_level' script in the
2005 S390-tools package, available for download at
2006 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2008 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2009 discovered. async scans them in kernel threads,
2010 allowing boot to proceed. none ignores them, expecting
2011 user space to do the scan.
2013 selinux [SELINUX] Disable or enable SELinux at boot time.
2014 Format: { "0" | "1" }
2015 See security/selinux/Kconfig help text.
2018 Default value is set via kernel config option.
2019 If enabled at boot time, /selinux/disable can be used
2020 later to disable prior to initial policy load.
2022 selinux_compat_net =
2023 [SELINUX] Set initial selinux_compat_net flag value.
2024 Format: { "0" | "1" }
2025 0 -- use new secmark-based packet controls
2026 1 -- use legacy packet controls
2027 Default value is 0 (preferred).
2028 Value can be changed at runtime via
2029 /selinux/compat_net.
2031 serialnumber [BUGS=X86-32]
2034 Maximal number of shapers.
2036 show_msr= [x86] show boot-time MSR settings
2037 Format: { <integer> }
2038 Show boot-time (BIOS-initialized) MSR settings.
2039 The parameter means the number of CPUs to show,
2040 for example 1 means boot CPU only.
2043 See header of drivers/scsi/sim710.c.
2050 slub_debug[=options[,slabs]] [MM, SLUB]
2051 Enabling slub_debug allows one to determine the
2052 culprit if slab objects become corrupted. Enabling
2053 slub_debug can create guard zones around objects and
2054 may poison objects when not in use. Also tracks the
2055 last alloc / free. For more information see
2056 Documentation/vm/slub.txt.
2058 slub_max_order= [MM, SLUB]
2059 Determines the maximum allowed order for slabs.
2060 A high setting may cause OOMs due to memory
2061 fragmentation. For more information see
2062 Documentation/vm/slub.txt.
2064 slub_min_objects= [MM, SLUB]
2065 The minimum number of objects per slab. SLUB will
2066 increase the slab order up to slub_max_order to
2067 generate a sufficiently large slab able to contain
2068 the number of objects indicated. The higher the number
2069 of objects the smaller the overhead of tracking slabs
2070 and the less frequently locks need to be acquired.
2071 For more information see Documentation/vm/slub.txt.
2073 slub_min_order= [MM, SLUB]
2074 Determines the mininum page order for slabs. Must be
2075 lower than slub_max_order.
2076 For more information see Documentation/vm/slub.txt.
2078 slub_nomerge [MM, SLUB]
2079 Disable merging of slabs with similar size. May be
2080 necessary if there is some reason to distinguish
2081 allocs to different slabs. Debug options disable
2082 merging on their own.
2083 For more information see Documentation/vm/slub.txt.
2086 Format: <io1>[,<io2>[,...,<io8>]]
2088 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2089 attempt to substitute SMP alternatives once at boot.
2091 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2092 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2093 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2094 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2095 smsc-ircc2.ircc_irq= [HW] IRQ line
2096 smsc-ircc2.ircc_dma= [HW] DMA channel
2097 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2098 0: Toshiba Satellite 1800 (GP data pin select)
2099 1: Fast pin select (default)
2102 snd-ad1816a= [HW,ALSA]
2104 snd-ad1848= [HW,ALSA]
2106 snd-ali5451= [HW,ALSA]
2108 snd-als100= [HW,ALSA]
2110 snd-als4000= [HW,ALSA]
2112 snd-azt2320= [HW,ALSA]
2114 snd-cmi8330= [HW,ALSA]
2116 snd-cmipci= [HW,ALSA]
2118 snd-cs4231= [HW,ALSA]
2120 snd-cs4232= [HW,ALSA]
2122 snd-cs4236= [HW,ALSA]
2124 snd-cs4281= [HW,ALSA]
2126 snd-cs46xx= [HW,ALSA]
2128 snd-dt019x= [HW,ALSA]
2130 snd-dummy= [HW,ALSA]
2132 snd-emu10k1= [HW,ALSA]
2134 snd-ens1370= [HW,ALSA]
2136 snd-ens1371= [HW,ALSA]
2138 snd-es968= [HW,ALSA]
2140 snd-es1688= [HW,ALSA]
2142 snd-es18xx= [HW,ALSA]
2144 snd-es1938= [HW,ALSA]
2146 snd-es1968= [HW,ALSA]
2148 snd-fm801= [HW,ALSA]
2150 snd-gusclassic= [HW,ALSA]
2152 snd-gusextreme= [HW,ALSA]
2154 snd-gusmax= [HW,ALSA]
2158 snd-ice1712= [HW,ALSA]
2160 snd-intel8x0= [HW,ALSA]
2162 snd-interwave= [HW,ALSA]
2167 snd-korg1212= [HW,ALSA]
2169 snd-maestro3= [HW,ALSA]
2171 snd-mpu401= [HW,ALSA]
2173 snd-mtpav= [HW,ALSA]
2175 snd-nm256= [HW,ALSA]
2177 snd-opl3sa2= [HW,ALSA]
2185 snd-opti93x= [HW,ALSA]
2189 snd-rme32= [HW,ALSA]
2191 snd-rme96= [HW,ALSA]
2193 snd-rme9652= [HW,ALSA]
2199 snd-sbawe= [HW,ALSA]
2201 snd-serial= [HW,ALSA]
2203 snd-sgalaxy= [HW,ALSA]
2205 snd-sonicvibes= [HW,ALSA]
2210 snd-sun-cs4231= [HW,ALSA]
2212 snd-trident= [HW,ALSA]
2214 snd-usb-audio= [HW,ALSA,USB]
2216 snd-via82xx= [HW,ALSA]
2218 snd-virmidi= [HW,ALSA]
2220 snd-wavefront= [HW,ALSA]
2222 snd-ymfpci= [HW,ALSA]
2225 [KNL] Should the soft-lockup detector generate panics.
2227 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2228 See Documentation/sonypi.txt
2230 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2231 See Documentation/serial/specialix.txt.
2233 spia_io_base= [HW,MTD]
2239 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2241 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2242 See Documentation/scsi/st.txt.
2245 Enabled the stack tracer on boot up.
2249 Set the STI (builtin display/keyboard on the HP-PARISC
2250 machines) console (graphic card) which should be used
2251 as the initial boot-console.
2252 See also comment in drivers/video/console/sticore.c.
2255 See comment in drivers/video/console/sticore.c.
2258 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2262 Control how the NFS server code allocates CPUs to
2263 service thread pools. Depending on how many NICs
2264 you have and where their interrupts are bound, this
2265 option will affect which CPUs will do NFS serving.
2266 Note: this parameter cannot be changed while the
2267 NFS server is running.
2269 auto the server chooses an appropriate mode
2270 automatically using heuristics
2271 global a single global pool contains all CPUs
2272 percpu one pool for each CPU
2273 pernode one pool for each NUMA node (equivalent
2274 to global on non-NUMA machines)
2276 swiotlb= [IA-64] Number of I/O TLB slabs
2280 sym53c416= [HW,SCSI]
2281 See header of drivers/scsi/sym53c416.c.
2283 sysrq_always_enabled
2285 Ignore sysrq setting - this boot parameter will
2286 neutralize any effect of /proc/sys/kernel/sysrq.
2287 Useful for debugging.
2290 See header of drivers/scsi/t128.c.
2294 test_suspend= [SUSPEND]
2295 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2296 standby suspend) as the system sleep state to briefly
2297 enter during system startup. The system is woken from
2298 this state using a wakeup-capable RTC alarm.
2300 thash_entries= [KNL,NET]
2301 Set number of hash buckets for TCP connection
2303 thermal.act= [HW,ACPI]
2304 -1: disable all active trip points in all thermal zones
2305 <degrees C>: override all lowest active trip points
2307 thermal.crt= [HW,ACPI]
2308 -1: disable all critical trip points in all thermal zones
2309 <degrees C>: override all critical trip points
2311 thermal.nocrt= [HW,ACPI]
2312 Set to disable actions on ACPI thermal zone
2313 critical and hot trip points.
2315 thermal.off= [HW,ACPI]
2316 1: disable ACPI thermal control
2318 thermal.psv= [HW,ACPI]
2319 -1: disable all passive trip points
2320 <degrees C>: override all passive trip points to this
2323 thermal.tzp= [HW,ACPI]
2324 Specify global default ACPI thermal zone polling rate
2325 <deci-seconds>: poll all this frequency
2326 0: no polling (default)
2329 See comment before function dc390_setup() in
2330 drivers/scsi/tmscsim.c.
2334 Specify if the kernel should make use of the cpu
2335 topology informations if the hardware supports these.
2336 The scheduler will make use of these informations and
2337 e.g. base its process migration decisions on it.
2342 trix= [HW,OSS] MediaTrix AudioTrix Pro
2344 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2346 tsc= Disable clocksource-must-verify flag for TSC.
2348 [x86] reliable: mark tsc clocksource as reliable, this
2349 disables clocksource verification at runtime.
2350 Used to enable high-resolution timer mode on older
2351 hardware, and in virtualized environment.
2353 turbografx.map[2|3]= [HW,JOY]
2354 TurboGraFX parallel port interface
2356 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2357 See also Documentation/input/joystick-parport.txt
2359 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2360 See header of drivers/scsi/u14-34f.c.
2369 [USB] Ignore overcurrent events (default N).
2370 Some badly-designed motherboards generate lots of
2371 bogus events, for ports that aren't wired to
2372 anything. Set this parameter to avoid log spamming.
2373 Note that genuine overcurrent events won't be
2378 Set unknown_nmi_panic=1 early on boot.
2380 usbcore.autosuspend=
2381 [USB] The autosuspend time delay (in seconds) used
2382 for newly-detected USB devices (default 2). This
2383 is the time required before an idle device will be
2384 autosuspended. Devices for which the delay is set
2385 to a negative value won't be autosuspended at all.
2387 usbcore.usbfs_snoop=
2388 [USB] Set to log all usbfs traffic (default 0 = off).
2390 usbcore.blinkenlights=
2391 [USB] Set to cycle leds on hubs (default 0 = off).
2393 usbcore.old_scheme_first=
2394 [USB] Start with the old device initialization
2395 scheme (default 0 = off).
2397 usbcore.use_both_schemes=
2398 [USB] Try the other device initialization scheme
2399 if the first one fails (default 1 = enabled).
2401 usbcore.initial_descriptor_timeout=
2402 [USB] Specifies timeout for the initial 64-byte
2403 USB_REQ_GET_DESCRIPTOR request in milliseconds
2404 (default 5000 = 5.0 seconds).
2407 [USBHID] The interval which mice are to be polled at.
2409 usb-storage.delay_use=
2410 [UMS] The delay in seconds before a new device is
2411 scanned for Logical Units (default 5).
2414 [UMS] A list of quirks entries to supplement or
2415 override the built-in unusual_devs list. List
2416 entries are separated by commas. Each entry has
2417 the form VID:PID:Flags where VID and PID are Vendor
2418 and Product ID values (4-digit hex numbers) and
2419 Flags is a set of characters, each corresponding
2420 to a common usb-storage quirk flag as follows:
2421 a = SANE_SENSE (collect more than 18 bytes
2423 c = FIX_CAPACITY (decrease the reported
2424 device capacity by one sector);
2425 h = CAPACITY_HEURISTICS (decrease the
2426 reported device capacity by one
2427 sector if the number is odd);
2428 i = IGNORE_DEVICE (don't bind to this
2430 l = NOT_LOCKABLE (don't try to lock and
2431 unlock ejectable media);
2432 m = MAX_SECTORS_64 (don't transfer more
2433 than 64 sectors = 32 KB at a time);
2434 o = CAPACITY_OK (accept the capacity
2435 reported by the device);
2436 r = IGNORE_RESIDUE (the device reports
2437 bogus residue values);
2438 s = SINGLE_LUN (the device has only one
2440 w = NO_WP_DETECT (don't test whether the
2441 medium is write-protected).
2442 Example: quirks=0419:aaf5:rl,0421:0433:rc
2444 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2445 kernel's map of available physical RAM.
2447 vdso= [X86-32,SH,x86-64]
2448 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2449 vdso=1: enable VDSO (default)
2450 vdso=0: disable VDSO mapping
2452 vdso32= [X86-32,X86-64]
2453 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2454 vdso32=1: enable 32-bit VDSO (default)
2455 vdso32=0: disable 32-bit VDSO mapping
2458 vector=percpu: enable percpu vector domain
2460 video= [FB] Frame buffer configuration
2461 See Documentation/fb/modedb.txt.
2463 vga= [BOOT,X86-32] Select a particular video mode
2464 See Documentation/x86/boot.txt and
2465 Documentation/svga.txt.
2466 Use vga=ask for menu.
2467 This is actually a boot loader parameter; the value is
2468 passed to the kernel using a special protocol.
2470 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2471 size of <nn>. This can be used to increase the
2472 minimum size (128MB on x86). It can also be used to
2473 decrease the size and leave more room for directly
2476 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2479 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2482 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2485 waveartist= [HW,OSS]
2486 Format: <io>,<irq>,<dma>,<dma2>
2489 See header of drivers/scsi/wd33c93.c.
2492 See header of drivers/scsi/wd7000.c.
2495 See Documentation/watchdog/wdt.txt.
2497 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2498 xd_geo= See header of drivers/block/xd.c.
2500 xirc2ps_cs= [NET,PCMCIA]
2502 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2504 norandmaps Don't use address space randomization. Equivalent to
2505 echo 0 > /proc/sys/kernel/randomize_va_space
2507 ______________________________________________________________________
2511 Add documentation for ALSA options.
2512 Add more DRM drivers.