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 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
496 this option disables the debugging code at boot.
498 dma_debug_entries=<number>
499 This option allows to tune the number of preallocated
500 entries for DMA-API debugging code. One entry is
501 required per DMA-API allocation. Use this if the
502 DMA-API debugging code disables itself because the
503 architectural default is too low.
505 hpet= [X86-32,HPET] option to control HPET usage
506 Format: { enable (default) | disable | force |
508 disable: disable HPET and use PIT instead
509 force: allow force enabled of undocumented chips (ICH4,
511 verbose: show contents of HPET registers during setup
513 com20020= [HW,NET] ARCnet - COM20020 chipset
515 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
517 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
521 ARCnet - COM90xx chipset (memory-mapped buffers)
522 Format: <io>[,<irq>[,<memstart>]]
524 condev= [HW,S390] console device
527 console= [KNL] Output console device and options.
529 tty<n> Use the virtual console device <n>.
533 Use the specified serial port. The options are of
534 the form "bbbbpnf", where "bbbb" is the baud rate,
535 "p" is parity ("n", "o", or "e"), "n" is number of
536 bits, and "f" is flow control ("r" for RTS or
537 omit it). Default is "9600n8".
539 See Documentation/serial-console.txt for more
541 Documentation/networking/netconsole.txt for an
544 uart[8250],io,<addr>[,options]
545 uart[8250],mmio,<addr>[,options]
546 Start an early, polled-mode console on the 8250/16550
547 UART at the specified I/O port or MMIO address,
548 switching to the matching ttyS device later. The
549 options are the same as for ttyS, above.
551 If the device connected to the port is not a TTY but a braille
552 device, prepend "brl," before the device type, for instance
554 For now, only VisioBraille is supported.
556 earlycon= [KNL] Output early console device and options.
557 uart[8250],io,<addr>[,options]
558 uart[8250],mmio,<addr>[,options]
559 Start an early, polled-mode console on the 8250/16550
560 UART at the specified I/O port or MMIO address.
561 The options are the same as for ttyS, above.
564 [HW] Never suspend the console
565 Disable suspending of consoles during suspend and
566 hibernate operations. Once disabled, debugging
567 messages can reach various consoles while the rest
568 of the system is being put to sleep (ie, while
569 debugging driver suspend/resume hooks). This may
570 not work reliably with all consoles, but is known
571 to work with serial and VGA consoles.
574 [KNL] Change the default value for
575 /proc/<pid>/coredump_filter.
576 See also Documentation/filesystems/proc.txt.
578 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
580 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
582 crashkernel=nn[KMG]@ss[KMG]
583 [KNL] Reserve a chunk of physical memory to
584 hold a kernel to switch to with kexec on panic.
586 crashkernel=range1:size1[,range2:size2,...][@offset]
587 [KNL] Same as above, but depends on the memory
588 in the running system. The syntax of range is
589 start-[end] where start and end are both
590 a memory unit (amount[KMG]). See also
591 Documentation/kdump/kdump.txt for a example.
596 cs89x0_media= [HW,NET]
597 Format: { rj45 | aui | bnc }
600 See header of drivers/s390/block/dasd_devmap.c.
602 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
603 (one device per port)
604 Format: <port#>,<type>
605 See also Documentation/input/joystick-parport.txt
607 debug [KNL] Enable kernel debugging (events log level).
610 [KNL] verbose self-tests
612 Print debugging info while doing the locking API
614 We default to 0 (no extra messages), setting it to
615 1 will print _a lot_ more information - normally
616 only useful to kernel developers.
618 debug_objects [KNL] Enable object debugging
620 debugpat [X86] Enable PAT debugging
622 decnet.addr= [HW,NET]
623 Format: <area>[,<node>]
624 See also Documentation/networking/decnet.txt.
627 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
628 Change the default blue palette of the console.
629 This is a 16-member array composed of values
633 Format: <green0>,<green1>,<green2>,...,<green15>
634 Change the default green palette of the console.
635 This is a 16-member array composed of values
639 Format: <red0>,<red1>,<red2>,...,<red15>
640 Change the default red palette of the console.
641 This is a 16-member array composed of values
647 Set system-wide default UTF-8 mode for all tty's.
648 Default is 1, i.e. UTF-8 mode is enabled for all
649 newly opened terminals.
652 Set number of hash buckets for dentry cache.
655 IO parameters + enable/disable command.
657 digiepca= [HW,SERIAL]
658 See drivers/char/README.epca and
659 Documentation/serial/digiepca.txt.
661 disable_mtrr_cleanup [X86]
662 enable_mtrr_cleanup [X86]
663 The kernel tries to adjust MTRR layout from continuous
664 to discrete, to make X server driver able to add WB
665 entry later. This parameter enables/disables that.
667 mtrr_chunk_size=nn[KMG] [X86]
668 used for mtrr cleanup. It is largest continous chunk
669 that could hold holes aka. UC entries.
671 mtrr_gran_size=nn[KMG] [X86]
672 Used for mtrr cleanup. It is granularity of mtrr block.
674 Large value could prevent small alignment from
677 mtrr_spare_reg_nr=n [X86]
679 Range: 0,7 : spare reg number
681 Used for mtrr cleanup. It is spare mtrr entries number.
682 Set to 2 or more if your graphical card needs more.
684 disable_mtrr_trim [X86, Intel and AMD only]
685 By default the kernel will trim any uncacheable
686 memory out of your available memory pool based on
687 MTRR settings. This parameter disables that behavior,
688 possibly causing your machine to run very slowly.
690 dmasound= [HW,OSS] Sound subsystem buffers
696 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
698 earlyprintk=serial[,ttySn[,baudrate]]
701 Append ",keep" to not disable it when the real console
704 Only vga or serial or usb debug port at a time.
706 Currently only ttyS0 and ttyS1 are supported.
708 Interaction with the standard serial driver is not
711 The VGA output is eventually overwritten by the real
717 Format: {"off" | "on" | "skip[mbr]"}
719 eisa_irq_edge= [PARISC,HW]
720 See header of drivers/parisc/eisa.c.
723 See comment before function elanfreq_setup() in
724 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
727 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
728 See Documentation/block/as-iosched.txt and
729 Documentation/block/deadline-iosched.txt for details.
731 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
732 Specifies physical address of start of kernel core
733 image elf header. Generally kexec loader will
734 pass this option to capture kernel.
735 See Documentation/kdump/kdump.txt for details.
737 enforcing [SELINUX] Set initial enforcing status.
739 See security/selinux/Kconfig help text.
740 0 -- permissive (log only, no denials).
741 1 -- enforcing (deny and log).
743 Value can be changed at runtime via /selinux/enforce.
745 ether= [HW,NET] Ethernet cards parameters
746 This option is obsoleted by the "netdev=" option, which
747 has equivalent usage. See its documentation for details.
749 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
754 fail_make_request=[KNL]
755 General fault injection mechanism.
756 Format: <interval>,<probability>,<space>,<times>
757 See also /Documentation/fault-injection/.
760 See header of drivers/scsi/fd_mcs.c.
763 See header of drivers/scsi/fdomain.c.
766 See Documentation/blockdev/floppy.txt.
768 force_pal_cache_flush
769 [IA-64] Avoid check_sal_cache_flush which may hang on
770 buggy SAL_CACHE_FLUSH implementations. Using this
771 parameter will force ia64_sal_cache_flush to call
772 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
775 [ftrace] will set and start the specified tracer
776 as early as possible in order to facilitate early
780 [ftrace] will dump the trace buffers on oops.
783 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
784 support via parallel port (up to 5 devices per port)
785 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
786 See also Documentation/input/joystick-parport.txt
790 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
795 See header of drivers/scsi/gdth.c.
797 gpt [EFI] Forces disk with valid GPT signature but
798 invalid Protective MBR to be treated as GPT.
802 hashdist= [KNL,NUMA] Large hashes allocated during boot
803 are distributed across NUMA nodes. Defaults on
804 for IA-64, off otherwise.
805 Format: 0 | 1 (for off | on)
807 hcl= [IA-64] SGI's Hardware Graph compatibility layer
809 hd= [EIDE] (E)IDE hard drive subsystem geometry
810 Format: <cyl>,<head>,<sect>
812 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
813 size of <nn>. This works even on boxes that have no
814 highmem otherwise. This also works to reduce highmem
815 size on bigger boxes.
817 highres= [KNL] Enable/disable high resolution timer mode.
818 Valid parameters: "on", "off"
822 See Documentation/isdn/README.HiSax.
824 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
825 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
826 On x86-64 and powerpc, this option can be specified
827 multiple times interleaved with hugepages= to reserve
828 huge pages of different sizes. Valid pages sizes on
829 x86-64 are 2M (when the CPU supports "pse") and 1G
830 (when the CPU supports the "pdpe1gb" cpuinfo flag)
831 Note that 1GB pages can only be allocated at boot time
832 using hugepages= and not freed afterwards.
834 [same as hugepagesz=] The size of the default
835 HugeTLB page size. This is the size represented by
836 the legacy /proc/ hugepages APIs, used for SHM, and
837 default size when mounting hugetlbfs filesystems.
838 Defaults to the default architecture's huge page size
843 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
844 terminal devices. Valid values: 0..8
845 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
846 If specified, z/VM IUCV HVC accepts connections
847 from listed z/VM user IDs only.
849 i2c_bus= [HW] Override the default board specific I2C bus speed
850 or register an additional I2C bus that is not
851 registered from board initialization code.
855 i8042.debug [HW] Toggle i8042 debug mode
856 i8042.direct [HW] Put keyboard port into non-translated mode
857 i8042.dumbkbd [HW] Pretend that controller can only read data from
858 keyboard and cannot control its state
859 (Don't attempt to blink the leds)
860 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
861 i8042.nokbd [HW] Don't check/create keyboard port
862 i8042.noloop [HW] Disable the AUX Loopback command while probing
864 i8042.nomux [HW] Don't check presence of an active multiplexing
866 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
869 [HW] Frequency with which keyboard LEDs should blink
870 when kernel panics (default is 0.5 sec)
871 i8042.reset [HW] Reset the controller during init and cleanup
872 i8042.unlock [HW] Unlock (ignore) the keylock
876 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
877 indicates that the driver is running on unsupported
879 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
880 does not match list of supported models.
882 [HW] Report power status in /proc/i8k
883 (disabled by default)
884 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
887 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
888 See Documentation/mca.txt.
891 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
893 ide-core.nodma= [HW] (E)IDE subsystem
894 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
895 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
896 .chs .ignore_cable are additional options
897 See Documentation/ide/ide.txt.
899 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
900 See Documentation/ide/ide.txt.
903 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
904 Poll forces a polling idle loop that can slightly
905 improve the performance of waking up a idle CPU, but
906 will use a lot of power and make the system run hot.
908 idle=mwait: On systems which support MONITOR/MWAIT but
909 the kernel chose to not use it because it doesn't save
910 as much power as a normal idle loop, use the
911 MONITOR/MWAIT idle loop anyways. Performance should be
912 the same as idle=poll.
913 idle=halt: Halt is forced to be used for CPU idle.
914 In such case C2/C3 won't be used again.
915 idle=nomwait: Disable mwait for CPU C-states
917 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
918 Claim all unknown PCI IDE storage controllers.
920 ignore_loglevel [KNL]
921 Ignore loglevel setting - this will print /all/
922 kernel messages to the console. Useful for debugging.
925 Set number of hash buckets for inode cache.
928 Format: { "0" | "1" }
929 0 -- integrity auditing messages. (Default)
930 1 -- enable informational integrity auditing messages.
933 Formt: { "sha1" | "md5" }
937 See header of drivers/scsi/in2000.c.
941 Run specified binary instead of /sbin/init as init
944 initcall_debug [KNL] Trace initcalls as they are executed. Useful
945 for working out where the kernel is dying during
948 initrd= [BOOT] Specify the location of the initial ramdisk
950 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
955 iomem= Disable strict checking of access to MMIO memory
956 strict regions from userspace.
972 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
974 Enable intel iommu driver.
976 Disable intel iommu driver.
977 igfx_off [Default Off]
978 By default, gfx is mapped as normal device. If a gfx
979 device has a dedicated DMAR unit, the DMAR unit is
980 bypassed by not enabling DMAR with this option. In
981 this case, gfx device will use physical address for
984 With this option iommu will not optimize to look
985 for io virtual address below 32 bit forcing dual
986 address cycle on pci bus for cards supporting greater
987 than 32 bit addressing. The default is to look
988 for translation below 32 bit and if not available
989 then look in the higher range.
991 With this option on every unmap_single operation will
992 result in a hardware IOTLB flush operation as opposed
993 to batching them for performance.
995 io_delay= [X86-32,X86-64] I/O delay method
997 Standard port 0x80 based delay
999 Alternate port 0xed based delay (needed on some systems)
1001 Simple two microseconds delay
1005 io7= [HW] IO7 for Marvel based alpha systems
1006 See comment before marvel_specify_io7 in
1007 arch/alpha/kernel/core_marvel.c.
1010 See Documentation/filesystems/nfsroot.txt.
1012 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1013 See comment before ip2_setup() in
1014 drivers/char/ip2/ip2base.c.
1016 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1017 See header of drivers/scsi/ips.c.
1019 ports= [IP_VS_FTP] IPVS ftp helper module
1021 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1023 Format: <port>,<port>....
1026 When an interrupt is not handled search all handlers
1027 for it. Intended to get systems with badly broken
1031 When an interrupt is not handled search all handlers
1032 for it. Also check all handlers each timer
1033 interrupt. Intended to get systems with badly broken
1037 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1039 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1041 <cpu number>,...,<cpu number>
1043 <cpu number>-<cpu number>
1044 (must be a positive range in ascending order)
1046 <cpu number>,...,<cpu number>-<cpu number>
1048 This option can be used to specify one or more CPUs
1049 to isolate from the general SMP balancing and scheduling
1050 algorithms. You can move a process onto or off an
1051 "isolated" CPU via the CPU affinity syscalls or cpuset.
1052 <cpu number> begins at 0 and the maximum value is
1053 "number of CPUs in system - 1".
1055 This option is the preferred way to isolate CPUs. The
1056 alternative -- manually setting the CPU mask of all
1057 tasks in the system -- can cause problems and
1058 suboptimal load balancer performance.
1062 js= [HW,JOY] Analog joystick
1063 See Documentation/input/joystick.txt.
1065 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1066 specifies the amount of memory usable by the kernel
1067 for non-movable allocations. The requested amount is
1068 spread evenly throughout all nodes in the system. The
1069 remaining memory in each node is used for Movable
1070 pages. In the event, a node is too small to have both
1071 kernelcore and Movable pages, kernelcore pages will
1072 take priority and other nodes will have a larger number
1073 of kernelcore pages. The Movable zone is used for the
1074 allocation of pages that may be reclaimed or moved
1075 by the page migration subsystem. This means that
1076 HugeTLB pages may not be allocated from this zone.
1077 Note that allocations like PTEs-from-HighMem still
1078 use the HighMem zone if it exists, and the Normal
1079 zone if it does not.
1081 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1082 is similar to kernelcore except it specifies the
1083 amount of memory used for migratable allocations.
1084 If both kernelcore and movablecore is specified,
1085 then kernelcore will be at *least* the specified
1086 value but may be more. If movablecore on its own
1087 is specified, the administrator must be careful
1088 that the amount of memory usable for all allocations
1093 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1096 kgdboc= [HW] kgdb over consoles.
1097 Requires a tty driver that supports console polling.
1098 (only serial suported for now)
1099 Format: <serial_device>[,baud]
1101 kmac= [MIPS] korina ethernet MAC address.
1102 Configure the RouterBoard 532 series on-chip
1103 Ethernet adapter MAC address.
1109 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1112 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1115 libata.dma= [LIBATA] DMA control
1116 libata.dma=0 Disable all PATA and SATA DMA
1117 libata.dma=1 PATA and SATA Disk DMA only
1118 libata.dma=2 ATAPI (CDROM) DMA only
1119 libata.dma=4 Compact Flash DMA only
1120 Combinations also work, so libata.dma=3 enables DMA
1121 for disks and CDROMs, but not CFs.
1123 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1127 libata.force= [LIBATA] Force configurations. The format is comma
1128 separated list of "[ID:]VAL" where ID is
1129 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1130 matching port, link or device. Basically, it matches
1131 the ATA ID string printed on console by libata. If
1132 the whole ID part is omitted, the last PORT and DEVICE
1133 values are used. If ID hasn't been specified yet, the
1134 configuration applies to all ports, links and devices.
1136 If only DEVICE is omitted, the parameter applies to
1137 the port and all links and devices behind it. DEVICE
1138 number of 0 either selects the first device or the
1139 first fan-out link behind PMP device. It does not
1140 select the host link. DEVICE number of 15 selects the
1141 host link and device attached to it.
1143 The VAL specifies the configuration to force. As long
1144 as there's no ambiguity shortcut notation is allowed.
1145 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1146 The following configurations can be forced.
1148 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1149 Any ID with matching PORT is used.
1151 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1153 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1154 udma[/][16,25,33,44,66,100,133] notation is also
1157 * [no]ncq: Turn on or off NCQ.
1159 * nohrst, nosrst, norst: suppress hard, soft
1162 If there are multiple matching configurations changing
1163 the same attribute, the last one is used.
1165 lmb=debug [KNL] Enable lmb debug messages.
1167 load_ramdisk= [RAM] List of ramdisks to load from floppy
1168 See Documentation/blockdev/ramdisk.txt.
1170 lockd.nlm_grace_period=P [NFS] Assign grace period.
1173 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1176 lockd.nlm_timeout=T [NFS] Assign timeout value.
1179 lockd.nlm_udpport=M [NFS] Assign UDP port.
1182 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1185 loglevel= All Kernel Messages with a loglevel smaller than the
1186 console loglevel will be printed to the console. It can
1187 also be changed with klogd or other programs. The
1188 loglevels are defined as follows:
1190 0 (KERN_EMERG) system is unusable
1191 1 (KERN_ALERT) action must be taken immediately
1192 2 (KERN_CRIT) critical conditions
1193 3 (KERN_ERR) error conditions
1194 4 (KERN_WARNING) warning conditions
1195 5 (KERN_NOTICE) normal but significant condition
1196 6 (KERN_INFO) informational
1197 7 (KERN_DEBUG) debug-level messages
1199 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1200 Format: { n | nk | nM }
1201 n must be a power of two. The default size
1202 is set in the kernel config file.
1204 logo.nologo [FB] Disables display of the built-in Linux logo.
1205 This may be used to provide more screen space for
1206 kernel log messages and is useful when debugging
1207 kernel boot problems.
1209 lp=0 [LP] Specify parallel ports to use, e.g,
1210 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1211 lp=reset first parallel port). 'lp=0' disables the
1212 lp=auto printer driver. 'lp=reset' (which can be
1213 specified in addition to the ports) causes
1214 attached printers to be reset. Using
1215 lp=port1,port2,... specifies the parallel ports
1216 to associate lp devices with, starting with
1217 lp0. A port specification may be 'none' to skip
1218 that lp device, or a parport name such as
1219 'parport0'. Specifying 'lp=auto' instead of a
1220 port specification list means that device IDs
1221 from each port should be examined, to see if
1222 an IEEE 1284-compliant printer is attached; if
1223 so, the driver will manage that printer.
1224 See also header of drivers/char/lp.c.
1227 Sets loops_per_jiffy to given constant, thus avoiding
1228 time-consuming boot-time autodetection (up to 250 ms per
1229 CPU). 0 enables autodetection (default). To determine
1230 the correct value for your kernel, boot with normal
1231 autodetection and see what value is printed. Note that
1232 on SMP systems the preset will be applied to all CPUs,
1233 which is likely to cause problems if your CPUs need
1234 significantly divergent settings. An incorrect value
1235 will cause delays in the kernel to be wrong, leading to
1236 unpredictable I/O errors and other breakage. Although
1237 unlikely, in the extreme case this might damage your
1241 Format: <io>,<irq>,<dma>
1243 mac5380= [HW,SCSI] Format:
1244 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1246 machvec= [IA64] Force the use of a particular machine-vector
1247 (machvec) in a generic kernel.
1248 Example: machvec=hpzx1_swiotlb
1250 max_loop= [LOOP] Maximum number of loopback devices that can
1254 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1255 should make use of. maxcpus=n : n >= 0 limits the
1256 kernel to using 'n' processors. n=0 is a special case,
1257 it is equivalent to "nosmp", which also disables
1260 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1261 or equal to this physical address is ignored.
1263 max_luns= [SCSI] Maximum number of LUNs to probe.
1264 Should be between 1 and 2^32-1.
1267 [SCSI] Maximum number of LUNs received.
1268 Should be between 1 and 16384.
1272 mce [X86-32] Machine Check Exception
1274 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1276 md= [HW] RAID subsystems devices and level
1277 See Documentation/md.txt.
1280 Format: <first>,<last>
1281 Specifies range of consoles to be captured by the MDA.
1283 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1284 Amount of memory to be used when the kernel is not able
1285 to see the whole system memory or for test.
1286 [X86-32] Use together with memmap= to avoid physical
1287 address space collisions. Without memmap= PCI devices
1288 could be placed at addresses belonging to unused RAM.
1290 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1294 [KNL,SH] Allow user to override the default size for
1295 per-device physically contiguous DMA buffers.
1297 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1298 E820 memory map, as specified by the user.
1299 Such memmap=exactmap lines can be constructed based on
1300 BIOS output or other requirements. See the memmap=nn@ss
1303 memmap=nn[KMG]@ss[KMG]
1304 [KNL] Force usage of a specific region of memory
1305 Region of memory to be used, from ss to ss+nn.
1307 memmap=nn[KMG]#ss[KMG]
1308 [KNL,ACPI] Mark specific memory as ACPI data.
1309 Region of memory to be used, from ss to ss+nn.
1311 memmap=nn[KMG]$ss[KMG]
1312 [KNL,ACPI] Mark specific memory as reserved.
1313 Region of memory to be used, from ss to ss+nn.
1314 Example: Exclude memory from 0x18690000-0x1869ffff
1315 memmap=64K$0x18690000
1317 memmap=0x10000$0x18690000
1319 memory_corruption_check=0/1 [X86]
1320 Some BIOSes seem to corrupt the first 64k of
1321 memory when doing things like suspend/resume.
1322 Setting this option will scan the memory
1323 looking for corruption. Enabling this will
1324 both detect corruption and prevent the kernel
1325 from using the memory being corrupted.
1326 However, its intended as a diagnostic tool; if
1327 repeatable BIOS-originated corruption always
1328 affects the same memory, you can use memmap=
1329 to prevent the kernel from using that memory.
1331 memory_corruption_check_size=size [X86]
1332 By default it checks for corruption in the low
1333 64k, making this memory unavailable for normal
1334 use. Use this parameter to scan for
1335 corruption in more or less memory.
1337 memory_corruption_check_period=seconds [X86]
1338 By default it checks for corruption every 60
1339 seconds. Use this parameter to check at some
1340 other rate. 0 disables periodic checking.
1342 memtest= [KNL,X86] Enable memtest
1344 default : 0 <disable>
1345 Specifies the number of memtest passes to be
1346 performed. Each pass selects another test
1347 pattern from a given set of patterns. Memtest
1348 fills the memory with this pattern, validates
1349 memory contents and reserves bad memory
1350 regions that are detected.
1352 meye.*= [HW] Set MotionEye Camera parameters
1353 See Documentation/video4linux/meye.txt.
1355 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1356 Multi-Function General Purpose Timers on AMD Geode
1359 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1360 the BIOS has incorrectly applied a workaround. TinyBIOS
1361 version 0.98 is known to be affected, 0.99 fixes the
1362 problem by letting the user disable the workaround.
1366 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1367 physical address is ignored.
1370 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1371 parameter allows control of the logging verbosity for
1372 the additional memory initialisation checks. A value
1373 of 0 disables mminit logging and a level of 4 will
1374 log everything. Information is printed at KERN_DEBUG
1375 so loglevel=8 may also need to be specified.
1378 [MOUSE] Maximum time between finger touching and
1379 leaving touchpad surface for touch to be considered
1380 a tap and be reported as a left button click (for
1381 touchpads working in absolute mode only).
1383 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1384 reporting absolute coordinates, such as tablets
1385 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1386 reporting absolute coordinates, such as tablets
1391 MTD_Partition= [MTD]
1392 Format: <name>,<region-number>,<size>,<offset>
1394 MTD_Region= [MTD] Format:
1395 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1398 See drivers/mtd/cmdlinepart.c.
1401 ARM/S3C2412 JIVE boot control
1403 See arch/arm/mach-s3c2412/mach-jive.c
1405 mtouchusb.raw_coordinates=
1406 [HW] Make the MicroTouch USB driver use raw coordinates
1407 ('y', default) or cooked coordinates ('n')
1409 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1412 See header of drivers/scsi/NCR_D700.c.
1416 ncr53c400= [HW,SCSI]
1418 ncr53c400a= [HW,SCSI]
1420 ncr53c406a= [HW,SCSI]
1422 ncr53c8xx= [HW,SCSI]
1424 netdev= [NET] Network devices parameters
1425 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1426 Note that mem_start is often overloaded to mean
1427 something different and driver-specific.
1428 This usage is only documented in each driver source
1432 [NETFILTER] Enable connection tracking flow accounting
1433 0 to disable accounting
1434 1 to enable accounting
1435 Default value depends on CONFIG_NF_CT_ACCT that is
1436 going to be removed in 2.6.29.
1439 See Documentation/filesystems/nfsroot.txt.
1441 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1442 See Documentation/filesystems/nfsroot.txt.
1444 nfs.callback_tcpport=
1445 [NFS] set the TCP port on which the NFSv4 callback
1446 channel should listen.
1448 nfs.idmap_cache_timeout=
1449 [NFS] set the maximum lifetime for idmapper cache
1453 [NFS] enable 64-bit inode numbers.
1454 If zero, the NFS client will fake up a 32-bit inode
1455 number for the readdir() and stat() syscalls instead
1456 of returning the full 64-bit number.
1457 The default is to return 64-bit inode numbers.
1459 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1460 when a NMI is triggered.
1461 Format: [state][,regs][,debounce][,die]
1463 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1464 Format: [panic,][num]
1466 0 - turn nmi_watchdog off
1467 1 - use the IO-APIC timer for the NMI watchdog
1468 2 - use the local APIC for the NMI watchdog using
1469 a performance counter. Note: This will use one performance
1470 counter and the local APIC's performance vector.
1471 When panic is specified panic when an NMI watchdog timeout occurs.
1472 This is useful when you use a panic=... timeout and need the box
1474 Instead of 1 and 2 it is possible to use the following
1475 symbolic names: lapic and ioapic
1476 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1478 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1479 emulation library even if a 387 maths coprocessor
1482 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1483 caches in the slab allocator. Saves per-node memory,
1484 but will impact performance.
1488 noapic [SMP,APIC] Tells the kernel to not make use of any
1489 IOAPICs that may be present in the system.
1491 nobats [PPC] Do not use BATs for mapping kernel lowmem
1492 on "Classic" PPC cores.
1496 nodelayacct [KNL] Disable per-task delay accounting
1498 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1500 nodsp [SH] Disable hardware DSP at boot time.
1502 noefi [X86-32,X86-64] Disable EFI runtime services support.
1506 noexec [X86-32,X86-64]
1507 On X86-32 available only on PAE configured kernels.
1508 noexec=on: enable non-executable mappings (default)
1509 noexec=off: disable non-executable mappings
1512 This affects only 32-bit executables.
1513 noexec32=on: enable non-executable mappings (default)
1514 read doesn't imply executable mappings
1515 noexec32=off: disable non-executable mappings
1516 read implies executable mappings
1518 nofpu [SH] Disable hardware FPU at boot time.
1520 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1521 register save and restore. The kernel will only save
1522 legacy floating-point registers on task switch.
1524 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1526 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1527 wfi(ARM) instruction doesn't work correctly and not to
1528 use it. This is also useful when using JTAG debugger.
1530 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1531 instruction doesn't work correctly and not to
1534 no_file_caps Tells the kernel not to honor file capabilities. The
1535 only way then for a file to be executed with privilege
1536 is to be setuid root or executed by root.
1538 nohalt [IA-64] Tells the kernel not to use the power saving
1539 function PAL_HALT_LIGHT when idle. This increases
1540 power-consumption. On the positive side, it reduces
1541 interrupt wake-up latency, which may improve performance
1542 in certain environments such as networked servers or
1545 nohz= [KNL] Boottime enable/disable dynamic ticks
1546 Valid arguments: on, off
1549 noirqdebug [X86-32] Disables the code which attempts to detect and
1550 disable unhandled interrupt sources.
1552 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1553 broken timer IRQ sources.
1555 noisapnp [ISAPNP] Disables ISA PnP code.
1557 noinitrd [RAM] Tells the kernel not to load any configured
1562 nojitter [IA64] Disables jitter checking for ITC timers.
1564 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1566 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1568 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1570 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1571 default x2apic cluster mode on platforms
1574 noltlbs [PPC] Do not use large page/tlb entries for kernel
1575 lowmem mapping on PPC40x.
1577 nomca [IA-64] Disable machine check abort handling
1579 nomce [X86-32] Machine Check Exception
1581 nomfgpt [X86-32] Disable Multi-Function General Purpose
1582 Timer usage (for AMD Geode machines).
1584 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1586 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1587 with UP alternatives
1589 noresidual [PPC] Don't use residual data on PReP machines.
1591 noresume [SWSUSP] Disables resume and restores original swap
1594 no-scroll [VGA] Disables scrollback.
1595 This is required for the Braillex ib80-piezo Braille
1596 reader made by F.H. Papenmeier (Germany).
1600 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1602 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1603 and disable the IO APIC. legacy for "maxcpus=0".
1605 nosoftlockup [KNL] Disable the soft-lockup detector.
1607 noswapaccount [KNL] Disable accounting of swap in memory resource
1608 controller. (See Documentation/controllers/memory.txt)
1610 nosync [HW,M68K] Disables sync negotiation for all devices.
1612 notsc [BUGS=X86-32] Disable Time Stamp Counter
1614 nousb [USB] Disable the USB subsystem
1618 nptcg= [IA64] Override max number of concurrent global TLB
1619 purges which is reported from either PAL_VM_SUMMARY or
1622 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1623 one of ['zone', 'node', 'default'] can be specified
1624 This can be set from sysctl after boot.
1625 See Documentation/sysctl/vm.txt for details.
1627 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1629 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1630 See Documentation/debugging-via-ohci1394.txt for more
1633 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1634 Rather than timing out after 20 ms if an EC
1635 command is not properly ACKed, override the length
1636 of the timeout. We have interrupts disabled while
1637 waiting for the ACK, so if this is set too high
1638 interrupts *may* be lost!
1643 oprofile.timer= [HW]
1644 Use timer interrupt instead of performance counters
1646 osst= [HW,SCSI] SCSI Tape Driver
1647 Format: <buffer_size>,<write_threshold>
1648 See also Documentation/scsi/st.txt.
1650 panic= [KNL] Kernel behaviour on panic
1653 parkbd.port= [HW] Parallel port number the keyboard adapter is
1654 connected to, default is 0.
1656 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1657 0 for XT, 1 for AT (default is AT).
1660 parport= [HW,PPT] Specify parallel ports. 0 disables.
1661 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1662 Use 'auto' to force the driver to use any
1663 IRQ/DMA settings detected (the default is to
1664 ignore detected IRQ/DMA settings because of
1665 possible conflicts). You can specify the base
1666 address, IRQ, and DMA settings; IRQ and DMA
1667 should be numbers, or 'auto' (for using detected
1668 settings on that particular port), or 'nofifo'
1669 (to avoid using a FIFO even if it is detected).
1670 Parallel ports are assigned in the order they
1671 are specified on the command line, starting
1674 parport_init_mode= [HW,PPT]
1675 Configure VIA parallel port to operate in
1676 a specific mode. This is necessary on Pegasos
1677 computer where firmware has no options for setting
1678 up parallel port mode and sets it to spp.
1679 Currently this function knows 686a and 8231 chips.
1680 Format: [spp|ps2|epp|ecp|ecpepp]
1682 pas2= [HW,OSS] Format:
1683 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1686 See header of drivers/scsi/pas16.c.
1689 Halt all CPUs after the first oops has been printed for
1690 the specified number of seconds. This is to be used if
1691 your oopses keep scrolling off the screen.
1696 See header of drivers/block/paride/pcd.c.
1697 See also Documentation/blockdev/paride.txt.
1699 pci=option[,option...] [PCI] various PCI subsystem options:
1700 earlydump [X86] dump PCI config space before the kernel
1702 off [X86] don't probe for the PCI bus
1703 bios [X86-32] force use of PCI BIOS, don't access
1704 the hardware directly. Use this if your machine
1705 has a non-standard PCI host bridge.
1706 nobios [X86-32] disallow use of PCI BIOS, only direct
1707 hardware access methods are allowed. Use this
1708 if you experience crashes upon bootup and you
1709 suspect they are caused by the BIOS.
1710 conf1 [X86] Force use of PCI Configuration
1712 conf2 [X86] Force use of PCI Configuration
1714 noaer [PCIE] If the PCIEAER kernel config parameter is
1715 enabled, this kernel boot option can be used to
1716 disable the use of PCIE advanced error reporting.
1717 nodomains [PCI] Disable support for multiple PCI
1718 root domains (aka PCI segments, in ACPI-speak).
1719 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1721 nomsi [MSI] If the PCI_MSI kernel config parameter is
1722 enabled, this kernel boot option can be used to
1723 disable the use of MSI interrupts system-wide.
1724 noioapicquirk [APIC] Disable all boot interrupt quirks.
1725 Safety option to keep boot IRQs enabled. This
1726 should never be necessary.
1727 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1728 primary IO-APIC for bridges that cannot disable
1729 boot IRQs. This fixes a source of spurious IRQs
1730 when the system masks IRQs.
1731 noioapicreroute [APIC] Disable workaround that uses the
1732 boot IRQ equivalent of an IRQ that connects to
1733 a chipset where boot IRQs cannot be disabled.
1734 The opposite of ioapicreroute.
1735 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1736 routing table. These calls are known to be buggy
1737 on several machines and they hang the machine
1738 when used, but on other computers it's the only
1739 way to get the interrupt routing table. Try
1740 this option if the kernel is unable to allocate
1741 IRQs or discover secondary PCI buses on your
1743 rom [X86] Assign address space to expansion ROMs.
1744 Use with caution as certain devices share
1745 address decoders between ROMs and other
1747 norom [X86] Do not assign address space to
1748 expansion ROMs that do not already have
1749 BIOS assigned address ranges.
1750 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1751 assigned automatically to PCI devices. You can
1752 make the kernel exclude IRQs of your ISA cards
1754 pirqaddr=0xAAAAA [X86] Specify the physical address
1755 of the PIRQ table (normally generated
1756 by the BIOS) if it is outside the
1757 F0000h-100000h range.
1758 lastbus=N [X86] Scan all buses thru bus #N. Can be
1759 useful if the kernel is unable to find your
1760 secondary buses and you want to tell it
1761 explicitly which ones they are.
1762 assign-busses [X86] Always assign all PCI bus
1763 numbers ourselves, overriding
1764 whatever the firmware may have done.
1765 usepirqmask [X86] Honor the possible IRQ mask stored
1766 in the BIOS $PIR table. This is needed on
1767 some systems with broken BIOSes, notably
1768 some HP Pavilion N5400 and Omnibook XE3
1769 notebooks. This will have no effect if ACPI
1770 IRQ routing is enabled.
1771 noacpi [X86] Do not use ACPI for IRQ routing
1772 or for PCI scanning.
1773 use_crs [X86] Use _CRS for PCI resource
1775 routeirq Do IRQ routing for all PCI devices.
1776 This is normally done in pci_enable_device(),
1777 so this option is a temporary workaround
1778 for broken drivers that don't call it.
1779 skip_isa_align [X86] do not align io start addr, so can
1780 handle more pci cards
1781 firmware [ARM] Do not re-enumerate the bus but instead
1782 just use the configuration from the
1783 bootloader. This is currently used on
1784 IXP2000 systems where the bus has to be
1785 configured a certain way for adjunct CPUs.
1786 noearly [X86] Don't do any early type 1 scanning.
1787 This might help on some broken boards which
1788 machine check when some devices' config space
1789 is read. But various workarounds are disabled
1790 and some IOMMU drivers will not work.
1791 bfsort Sort PCI devices into breadth-first order.
1792 This sorting is done to get a device
1793 order compatible with older (<= 2.4) kernels.
1794 nobfsort Don't sort PCI devices into breadth-first order.
1795 cbiosize=nn[KMG] The fixed amount of bus space which is
1796 reserved for the CardBus bridge's IO window.
1797 The default value is 256 bytes.
1798 cbmemsize=nn[KMG] The fixed amount of bus space which is
1799 reserved for the CardBus bridge's memory
1800 window. The default value is 64 megabytes.
1803 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1804 Specifies alignment and device to reassign
1805 aligned memory resources.
1806 If <order of align> is not specified,
1807 PAGE_SIZE is used as alignment.
1808 PCI-PCI bridge can be specified, if resource
1809 windows need to be expanded.
1811 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1814 force Enable ASPM even on devices that claim not to support it.
1815 WARNING: Forcing ASPM on may cause system lockups.
1817 pcmv= [HW,PCMCIA] BadgePAD 4
1820 See Documentation/blockdev/paride.txt.
1822 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1825 See arch/parisc/kernel/pdc_chassis.c
1828 See Documentation/blockdev/paride.txt.
1831 See Documentation/blockdev/paride.txt.
1833 pirq= [SMP,APIC] Manual mp-table setup
1834 See Documentation/x86/i386/IO-APIC.txt.
1836 plip= [PPT,NET] Parallel port network link
1837 Format: { parport<nr> | timid | 0 }
1838 See also Documentation/parport.txt.
1840 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1841 Override pmtimer IOPort with a hex value.
1845 Enable PNP debug messages. This depends on the
1846 CONFIG_PNP_DEBUG_MESSAGES option.
1852 { on | off | curr | res | no-curr | no-res }
1855 [ISAPNP] Exclude IRQs for the autoconfiguration
1858 [ISAPNP] Exclude DMAs for the autoconfiguration
1860 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1861 Ranges are in pairs (I/O port base and size).
1864 [ISAPNP] Exclude memory regions for the
1866 Ranges are in pairs (memory base and size).
1868 print-fatal-signals=
1869 [KNL] debug: print fatal signals
1870 print-fatal-signals=1: print segfault info to
1874 printk.time= Show timing data prefixed to each printk message line
1875 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1877 profile= [KNL] Enable kernel profiling via /proc/profile
1878 Format: [schedule,]<number>
1879 Param: "schedule" - profile schedule points.
1880 Param: <number> - step/bucket size as a power of 2 for
1881 statistical time based profiling.
1882 Param: "sleep" - profile D-state sleeping (millisecs).
1883 Requires CONFIG_SCHEDSTATS
1884 Param: "kvm" - profile VM exits.
1886 processor.max_cstate= [HW,ACPI]
1887 Limit processor to maximum C-state
1888 max_cstate=9 overrides any DMI blacklist limit.
1890 processor.nocst [HW,ACPI]
1891 Ignore the _CST method to determine C-states,
1892 instead using the legacy FADT method
1894 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1896 See Documentation/blockdev/ramdisk.txt.
1898 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1899 probe for; one of (bare|imps|exps|lifebook|any).
1900 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1902 psmouse.resetafter= [HW,MOUSE]
1903 Try to reset the device after so many bad packets
1906 [HW,MOUSE] Set desired mouse resolution, in dpi.
1907 psmouse.smartscroll=
1908 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1909 0 = disabled, 1 = enabled (default).
1911 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1913 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1916 See Documentation/blockdev/paride.txt.
1919 [KNL] Number of legacy pty's. Overwrites compiled-in
1922 quiet [KNL] Disable most log messages
1927 See Documentation/md.txt.
1929 ramdisk_blocksize= [RAM]
1930 See Documentation/blockdev/ramdisk.txt.
1932 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1933 See Documentation/blockdev/ramdisk.txt.
1935 rcupdate.blimit= [KNL,BOOT]
1936 Set maximum number of finished RCU callbacks to process
1939 rcupdate.qhimark= [KNL,BOOT]
1940 Set threshold of queued
1941 RCU callbacks over which batch limiting is disabled.
1943 rcupdate.qlowmark= [KNL,BOOT]
1944 Set threshold of queued RCU callbacks below which
1945 batch limiting is re-enabled.
1949 Run specified binary instead of /init from the ramdisk,
1950 used for early userspace startup. See initrd.
1952 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1953 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1954 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1957 [KNL, SMP] Set scheduler's default relax_domain_level.
1958 See Documentation/cpusets.txt.
1960 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1962 reservetop= [X86-32]
1964 Reserves a hole at the top of the kernel virtual
1967 reset_devices [KNL] Force drivers to reset the underlying device
1968 during initialization.
1971 Specify the partition device for software suspend
1973 resume_offset= [SWSUSP]
1974 Specify the offset from the beginning of the partition
1975 given by "resume=" at which the swap header is located,
1976 in <PAGE_SIZE> units (needed only for swap files).
1977 See Documentation/power/swsusp-and-swap-files.txt
1979 retain_initrd [RAM] Keep initrd memory after extraction
1981 rhash_entries= [KNL,NET]
1982 Set number of hash buckets for route cache
1984 riscom8= [HW,SERIAL]
1985 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1987 ro [KNL] Mount root device read-only on boot
1989 root= [KNL] Root filesystem
1991 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1992 mount the root filesystem
1994 rootflags= [KNL] Set root filesystem mount option string
1996 rootfstype= [KNL] Set root filesystem type
1998 rootwait [KNL] Wait (indefinitely) for root device to show up.
1999 Useful for devices that are detected asynchronously
2000 (e.g. USB and MMC devices).
2002 root_plug.vendor_id=
2003 [ROOTPLUG] Override the default vendor ID
2005 root_plug.product_id=
2006 [ROOTPLUG] Override the default product ID
2009 [ROOTPLUG] Enable debugging output
2011 rw [KNL] Mount root device read-write on boot
2013 S [KNL] Run init in single mode
2016 See drivers/net/irda/sa1100_ir.c.
2018 sbni= [NET] Granch SBNI12 leased line adapter
2020 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2021 Format: <io>[,<timeout>[,<isapnp>]]
2023 scsi_debug_*= [SCSI]
2024 See drivers/scsi/scsi_debug.c.
2026 scsi_default_dev_flags=
2027 [SCSI] SCSI default device flags
2030 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2031 Format: <vendor>:<model>:<flags>
2032 (flags are integer value)
2034 scsi_logging_level= [SCSI] a bit mask of logging levels
2035 See drivers/scsi/scsi_logging.h for bits. Also
2036 settable via sysctl at dev.scsi.logging_level
2037 (/proc/sys/dev/scsi/logging_level).
2038 There is also a nice 'scsi_logging_level' script in the
2039 S390-tools package, available for download at
2040 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2042 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2043 discovered. async scans them in kernel threads,
2044 allowing boot to proceed. none ignores them, expecting
2045 user space to do the scan.
2047 selinux [SELINUX] Disable or enable SELinux at boot time.
2048 Format: { "0" | "1" }
2049 See security/selinux/Kconfig help text.
2052 Default value is set via kernel config option.
2053 If enabled at boot time, /selinux/disable can be used
2054 later to disable prior to initial policy load.
2056 serialnumber [BUGS=X86-32]
2059 Maximal number of shapers.
2061 show_msr= [x86] show boot-time MSR settings
2062 Format: { <integer> }
2063 Show boot-time (BIOS-initialized) MSR settings.
2064 The parameter means the number of CPUs to show,
2065 for example 1 means boot CPU only.
2068 See header of drivers/scsi/sim710.c.
2075 slub_debug[=options[,slabs]] [MM, SLUB]
2076 Enabling slub_debug allows one to determine the
2077 culprit if slab objects become corrupted. Enabling
2078 slub_debug can create guard zones around objects and
2079 may poison objects when not in use. Also tracks the
2080 last alloc / free. For more information see
2081 Documentation/vm/slub.txt.
2083 slub_max_order= [MM, SLUB]
2084 Determines the maximum allowed order for slabs.
2085 A high setting may cause OOMs due to memory
2086 fragmentation. For more information see
2087 Documentation/vm/slub.txt.
2089 slub_min_objects= [MM, SLUB]
2090 The minimum number of objects per slab. SLUB will
2091 increase the slab order up to slub_max_order to
2092 generate a sufficiently large slab able to contain
2093 the number of objects indicated. The higher the number
2094 of objects the smaller the overhead of tracking slabs
2095 and the less frequently locks need to be acquired.
2096 For more information see Documentation/vm/slub.txt.
2098 slub_min_order= [MM, SLUB]
2099 Determines the mininum page order for slabs. Must be
2100 lower than slub_max_order.
2101 For more information see Documentation/vm/slub.txt.
2103 slub_nomerge [MM, SLUB]
2104 Disable merging of slabs with similar size. May be
2105 necessary if there is some reason to distinguish
2106 allocs to different slabs. Debug options disable
2107 merging on their own.
2108 For more information see Documentation/vm/slub.txt.
2111 Format: <io1>[,<io2>[,...,<io8>]]
2113 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2114 attempt to substitute SMP alternatives once at boot.
2116 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2117 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2118 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2119 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2120 smsc-ircc2.ircc_irq= [HW] IRQ line
2121 smsc-ircc2.ircc_dma= [HW] DMA channel
2122 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2123 0: Toshiba Satellite 1800 (GP data pin select)
2124 1: Fast pin select (default)
2127 snd-ad1816a= [HW,ALSA]
2129 snd-ad1848= [HW,ALSA]
2131 snd-ali5451= [HW,ALSA]
2133 snd-als100= [HW,ALSA]
2135 snd-als4000= [HW,ALSA]
2137 snd-azt2320= [HW,ALSA]
2139 snd-cmi8330= [HW,ALSA]
2141 snd-cmipci= [HW,ALSA]
2143 snd-cs4231= [HW,ALSA]
2145 snd-cs4232= [HW,ALSA]
2147 snd-cs4236= [HW,ALSA]
2149 snd-cs4281= [HW,ALSA]
2151 snd-cs46xx= [HW,ALSA]
2153 snd-dt019x= [HW,ALSA]
2155 snd-dummy= [HW,ALSA]
2157 snd-emu10k1= [HW,ALSA]
2159 snd-ens1370= [HW,ALSA]
2161 snd-ens1371= [HW,ALSA]
2163 snd-es968= [HW,ALSA]
2165 snd-es1688= [HW,ALSA]
2167 snd-es18xx= [HW,ALSA]
2169 snd-es1938= [HW,ALSA]
2171 snd-es1968= [HW,ALSA]
2173 snd-fm801= [HW,ALSA]
2175 snd-gusclassic= [HW,ALSA]
2177 snd-gusextreme= [HW,ALSA]
2179 snd-gusmax= [HW,ALSA]
2183 snd-ice1712= [HW,ALSA]
2185 snd-intel8x0= [HW,ALSA]
2187 snd-interwave= [HW,ALSA]
2192 snd-korg1212= [HW,ALSA]
2194 snd-maestro3= [HW,ALSA]
2196 snd-mpu401= [HW,ALSA]
2198 snd-mtpav= [HW,ALSA]
2200 snd-nm256= [HW,ALSA]
2202 snd-opl3sa2= [HW,ALSA]
2210 snd-opti93x= [HW,ALSA]
2214 snd-rme32= [HW,ALSA]
2216 snd-rme96= [HW,ALSA]
2218 snd-rme9652= [HW,ALSA]
2224 snd-sbawe= [HW,ALSA]
2226 snd-serial= [HW,ALSA]
2228 snd-sgalaxy= [HW,ALSA]
2230 snd-sonicvibes= [HW,ALSA]
2235 snd-sun-cs4231= [HW,ALSA]
2237 snd-trident= [HW,ALSA]
2239 snd-usb-audio= [HW,ALSA,USB]
2241 snd-via82xx= [HW,ALSA]
2243 snd-virmidi= [HW,ALSA]
2245 snd-wavefront= [HW,ALSA]
2247 snd-ymfpci= [HW,ALSA]
2250 [KNL] Should the soft-lockup detector generate panics.
2252 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2253 See Documentation/sonypi.txt
2255 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2256 See Documentation/serial/specialix.txt.
2258 spia_io_base= [HW,MTD]
2264 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2266 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2267 See Documentation/scsi/st.txt.
2270 Enabled the stack tracer on boot up.
2274 Set the STI (builtin display/keyboard on the HP-PARISC
2275 machines) console (graphic card) which should be used
2276 as the initial boot-console.
2277 See also comment in drivers/video/console/sticore.c.
2280 See comment in drivers/video/console/sticore.c.
2283 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2287 Control how the NFS server code allocates CPUs to
2288 service thread pools. Depending on how many NICs
2289 you have and where their interrupts are bound, this
2290 option will affect which CPUs will do NFS serving.
2291 Note: this parameter cannot be changed while the
2292 NFS server is running.
2294 auto the server chooses an appropriate mode
2295 automatically using heuristics
2296 global a single global pool contains all CPUs
2297 percpu one pool for each CPU
2298 pernode one pool for each NUMA node (equivalent
2299 to global on non-NUMA machines)
2301 swiotlb= [IA-64] Number of I/O TLB slabs
2305 sym53c416= [HW,SCSI]
2306 See header of drivers/scsi/sym53c416.c.
2308 sysrq_always_enabled
2310 Ignore sysrq setting - this boot parameter will
2311 neutralize any effect of /proc/sys/kernel/sysrq.
2312 Useful for debugging.
2315 See header of drivers/scsi/t128.c.
2319 test_suspend= [SUSPEND]
2320 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2321 standby suspend) as the system sleep state to briefly
2322 enter during system startup. The system is woken from
2323 this state using a wakeup-capable RTC alarm.
2325 thash_entries= [KNL,NET]
2326 Set number of hash buckets for TCP connection
2328 thermal.act= [HW,ACPI]
2329 -1: disable all active trip points in all thermal zones
2330 <degrees C>: override all lowest active trip points
2332 thermal.crt= [HW,ACPI]
2333 -1: disable all critical trip points in all thermal zones
2334 <degrees C>: override all critical trip points
2336 thermal.nocrt= [HW,ACPI]
2337 Set to disable actions on ACPI thermal zone
2338 critical and hot trip points.
2340 thermal.off= [HW,ACPI]
2341 1: disable ACPI thermal control
2343 thermal.psv= [HW,ACPI]
2344 -1: disable all passive trip points
2345 <degrees C>: override all passive trip points to this
2348 thermal.tzp= [HW,ACPI]
2349 Specify global default ACPI thermal zone polling rate
2350 <deci-seconds>: poll all this frequency
2351 0: no polling (default)
2354 See comment before function dc390_setup() in
2355 drivers/scsi/tmscsim.c.
2359 Specify if the kernel should make use of the cpu
2360 topology informations if the hardware supports these.
2361 The scheduler will make use of these informations and
2362 e.g. base its process migration decisions on it.
2367 trix= [HW,OSS] MediaTrix AudioTrix Pro
2369 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2371 tsc= Disable clocksource-must-verify flag for TSC.
2373 [x86] reliable: mark tsc clocksource as reliable, this
2374 disables clocksource verification at runtime.
2375 Used to enable high-resolution timer mode on older
2376 hardware, and in virtualized environment.
2378 turbografx.map[2|3]= [HW,JOY]
2379 TurboGraFX parallel port interface
2381 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2382 See also Documentation/input/joystick-parport.txt
2384 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2385 See header of drivers/scsi/u14-34f.c.
2394 [USB] Ignore overcurrent events (default N).
2395 Some badly-designed motherboards generate lots of
2396 bogus events, for ports that aren't wired to
2397 anything. Set this parameter to avoid log spamming.
2398 Note that genuine overcurrent events won't be
2403 Set unknown_nmi_panic=1 early on boot.
2405 usbcore.autosuspend=
2406 [USB] The autosuspend time delay (in seconds) used
2407 for newly-detected USB devices (default 2). This
2408 is the time required before an idle device will be
2409 autosuspended. Devices for which the delay is set
2410 to a negative value won't be autosuspended at all.
2412 usbcore.usbfs_snoop=
2413 [USB] Set to log all usbfs traffic (default 0 = off).
2415 usbcore.blinkenlights=
2416 [USB] Set to cycle leds on hubs (default 0 = off).
2418 usbcore.old_scheme_first=
2419 [USB] Start with the old device initialization
2420 scheme (default 0 = off).
2422 usbcore.use_both_schemes=
2423 [USB] Try the other device initialization scheme
2424 if the first one fails (default 1 = enabled).
2426 usbcore.initial_descriptor_timeout=
2427 [USB] Specifies timeout for the initial 64-byte
2428 USB_REQ_GET_DESCRIPTOR request in milliseconds
2429 (default 5000 = 5.0 seconds).
2432 [USBHID] The interval which mice are to be polled at.
2434 usb-storage.delay_use=
2435 [UMS] The delay in seconds before a new device is
2436 scanned for Logical Units (default 5).
2439 [UMS] A list of quirks entries to supplement or
2440 override the built-in unusual_devs list. List
2441 entries are separated by commas. Each entry has
2442 the form VID:PID:Flags where VID and PID are Vendor
2443 and Product ID values (4-digit hex numbers) and
2444 Flags is a set of characters, each corresponding
2445 to a common usb-storage quirk flag as follows:
2446 a = SANE_SENSE (collect more than 18 bytes
2448 c = FIX_CAPACITY (decrease the reported
2449 device capacity by one sector);
2450 h = CAPACITY_HEURISTICS (decrease the
2451 reported device capacity by one
2452 sector if the number is odd);
2453 i = IGNORE_DEVICE (don't bind to this
2455 l = NOT_LOCKABLE (don't try to lock and
2456 unlock ejectable media);
2457 m = MAX_SECTORS_64 (don't transfer more
2458 than 64 sectors = 32 KB at a time);
2459 o = CAPACITY_OK (accept the capacity
2460 reported by the device);
2461 r = IGNORE_RESIDUE (the device reports
2462 bogus residue values);
2463 s = SINGLE_LUN (the device has only one
2465 w = NO_WP_DETECT (don't test whether the
2466 medium is write-protected).
2467 Example: quirks=0419:aaf5:rl,0421:0433:rc
2469 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2470 kernel's map of available physical RAM.
2472 vdso= [X86-32,SH,x86-64]
2473 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2474 vdso=1: enable VDSO (default)
2475 vdso=0: disable VDSO mapping
2477 vdso32= [X86-32,X86-64]
2478 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2479 vdso32=1: enable 32-bit VDSO (default)
2480 vdso32=0: disable 32-bit VDSO mapping
2483 vector=percpu: enable percpu vector domain
2485 video= [FB] Frame buffer configuration
2486 See Documentation/fb/modedb.txt.
2488 vga= [BOOT,X86-32] Select a particular video mode
2489 See Documentation/x86/boot.txt and
2490 Documentation/svga.txt.
2491 Use vga=ask for menu.
2492 This is actually a boot loader parameter; the value is
2493 passed to the kernel using a special protocol.
2495 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2496 size of <nn>. This can be used to increase the
2497 minimum size (128MB on x86). It can also be used to
2498 decrease the size and leave more room for directly
2501 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2504 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2507 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2510 waveartist= [HW,OSS]
2511 Format: <io>,<irq>,<dma>,<dma2>
2514 See header of drivers/scsi/wd33c93.c.
2517 See header of drivers/scsi/wd7000.c.
2520 See Documentation/watchdog/wdt.txt.
2522 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2523 xd_geo= See header of drivers/block/xd.c.
2525 xirc2ps_cs= [NET,PCMCIA]
2527 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2529 norandmaps Don't use address space randomization. Equivalent to
2530 echo 0 > /proc/sys/kernel/randomize_va_space
2532 ______________________________________________________________________
2536 Add documentation for ALSA options.
2537 Add more DRM drivers.
projects / linux-2.6 / blob