4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 FTRACE Function tracing enabled.
93 TS Appropriate touchscreen support is enabled.
94 UMS USB Mass Storage support is enabled.
95 USB USB support is enabled.
96 USBHID USB Human Interface Device support is enabled.
97 V4L Video For Linux support is enabled.
98 VGA The VGA console has been enabled.
99 VT Virtual terminal support is enabled.
100 WDT Watchdog support is enabled.
101 XT IBM PC/XT MFM hard disk support is enabled.
102 X86-32 X86-32, aka i386 architecture is enabled.
103 X86-64 X86-64 architecture is enabled.
104 More X86-64 boot options can be found in
105 Documentation/x86/x86_64/boot-options.txt .
106 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
108 In addition, the following text indicates that the option:
110 BUGS= Relates to possible processor bugs on the said processor.
111 KNL Is a kernel start-up parameter.
112 BOOT Is a boot loader parameter.
114 Parameters denoted with BOOT are actually interpreted by the boot
115 loader, and have no meaning to the kernel directly.
116 Do not modify the syntax of boot loader parameters without extreme
117 need or coordination with <Documentation/x86/boot.txt>.
119 There are also arch-specific kernel-parameters not documented here.
120 See for example <Documentation/x86/x86_64/boot-options.txt>.
122 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
123 a trailing = on the name of any parameter states that that parameter will
124 be entered as an environment variable, whereas its absence indicates that
125 it will appear as a kernel argument readable via /proc/cmdline by programs
126 running once the system is up.
128 The number of kernel parameters is not limited, but the length of the
129 complete command line (parameters including spaces etc.) is limited to
130 a fixed number of characters. This limit depends on the architecture
131 and is between 256 and 4096 characters. It is defined in the file
132 ./include/asm/setup.h as COMMAND_LINE_SIZE.
135 acpi= [HW,ACPI,X86-64,i386]
136 Advanced Configuration and Power Interface
137 Format: { force | off | ht | strict | noirq | rsdt }
138 force -- enable ACPI if default was off
139 off -- disable ACPI if default was on
140 noirq -- do not use ACPI for IRQ routing
141 ht -- run only enough ACPI to enable Hyper Threading
142 strict -- Be less tolerant of platforms that are not
143 strictly ACPI specification compliant.
144 rsdt -- prefer RSDT over (default) XSDT
146 See also Documentation/power/pm.txt, pci=noacpi
148 acpi_apic_instance= [ACPI, IOAPIC]
150 2: use 2nd APIC table, if available
151 1,0: use 1st APIC table
154 acpi_sleep= [HW,ACPI] Sleep options
155 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
156 old_ordering, s4_nonvs }
157 See Documentation/power/video.txt for information on
159 s3_beep is for debugging; it makes the PC's speaker beep
160 as soon as the kernel's real-mode entry point is called.
161 s4_nohwsig prevents ACPI hardware signature from being
162 used during resume from hibernation.
163 old_ordering causes the ACPI 1.0 ordering of the _PTS
164 control method, with respect to putting devices into
165 low power states, to be enforced (the ACPI 2.0 ordering
166 of _PTS is used by default).
167 s4_nonvs prevents the kernel from saving/restoring the
168 ACPI NVS memory during hibernation.
170 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
171 Format: { level | edge | high | low }
173 acpi_irq_balance [HW,ACPI]
174 ACPI will balance active IRQs
177 acpi_irq_nobalance [HW,ACPI]
178 ACPI will not move active IRQs (default)
181 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
183 Format: <irq>,<irq>...
185 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
186 Format: <irq>,<irq>...
188 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
190 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
191 Format: To spoof as Windows 98: ="Microsoft Windows"
193 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
194 acpi_osi="string1" # add string1 -- only one string
195 acpi_osi="!string2" # remove built-in string2
196 acpi_osi= # disable all strings
198 acpi_serialize [HW,ACPI] force serialization of AML methods
200 acpi_skip_timer_override [HW,ACPI]
201 Recognize and ignore IRQ0/pin2 Interrupt Override.
202 For broken nForce2 BIOS resulting in XT-PIC timer.
203 acpi_use_timer_override [HW,ACPI]
204 Use timer override. For some broken Nvidia NF5 boards
205 that require a timer override, but don't have
208 acpi_backlight= [HW,ACPI]
209 acpi_backlight=vendor
211 If set to vendor, prefer vendor specific driver
212 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
213 of the ACPI video.ko driver.
215 acpi_display_output= [HW,ACPI]
216 acpi_display_output=vendor
217 acpi_display_output=video
220 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
221 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
223 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
224 debug output. Bits in debug_layer correspond to a
225 _COMPONENT in an ACPI source file, e.g.,
226 #define _COMPONENT ACPI_PCI_COMPONENT
227 Bits in debug_level correspond to a level in
228 ACPI_DEBUG_PRINT statements, e.g.,
229 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
230 The debug_level mask defaults to "info". See
231 Documentation/acpi/debug.txt for more information about
232 debug layers and levels.
234 Enable processor driver info messages:
235 acpi.debug_layer=0x20000000
236 Enable PCI/PCI interrupt routing info messages:
237 acpi.debug_layer=0x400000
238 Enable AML "Debug" output, i.e., stores to the Debug
239 object while interpreting AML:
240 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
241 Enable all messages related to ACPI hardware:
242 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
244 Some values produce so much output that the system is
245 unusable. The "log_buf_len" parameter may be useful
246 if you need to capture more output.
248 acpi.power_nocheck= [HW,ACPI]
249 Format: 1/0 enable/disable the check of power state.
250 On some bogus BIOS the _PSC object/_STA object of
251 power resource can't return the correct device power
252 state. In such case it is unneccessary to check its
253 power state again in power transition.
254 1 : disable the power state check
256 acpi_pm_good [X86-32,X86-64]
257 Override the pmtimer bug detection: force the kernel
258 to assume that this machine's pmtimer latches its value
259 and always returns good values.
262 { off | try_unsupported }
263 off: disable AGP support
264 try_unsupported: try to drive unsupported chipsets
265 (may crash computer or cause data corruption)
267 enable_timer_pin_1 [i386,x86-64]
268 Enable PIN 1 of APIC timer
269 Can be useful to work around chipset bugs
270 (in particular on some ATI chipsets).
271 The kernel tries to set a reasonable default.
273 disable_timer_pin_1 [i386,x86-64]
274 Disable PIN 1 of APIC timer
275 Can be useful to work around chipset bugs.
278 Format: <io>,<irq>,<dma>,<dma2>,<type>
281 See header of drivers/scsi/advansys.c.
283 advwdt= [HW,WDT] Advantech WDT
284 Format: <iostart>,<iostop>
286 aedsp16= [HW,OSS] Audio Excel DSP 16
287 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
288 See also header of sound/oss/aedsp16.c.
291 See Documentation/scsi/aha152x.txt.
294 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
297 See Documentation/scsi/aic7xxx.txt.
300 See Documentation/scsi/aic79xx.txt.
302 amd_iommu= [HW,X86-84]
303 Pass parameters to the AMD IOMMU driver in the system.
305 isolate - enable device isolation (each device, as far
306 as possible, will get its own protection
308 share - put every device behind one IOMMU into the
309 same protection domain
310 fullflush - enable flushing of IO/TLB entries when
311 they are unmapped. Otherwise they are
312 flushed before they will be reused, which
315 amd_iommu_size= [HW,X86-64]
316 Define the size of the aperture for the AMD IOMMU
317 driver. Possible values are:
318 '32M', '64M' (default), '128M', '256M', '512M', '1G'
320 amijoy.map= [HW,JOY] Amiga joystick support
321 Map of devices attached to JOY0DAT and JOY1DAT
323 See also Documentation/kernel/input/joystick.txt
325 analog.map= [HW,JOY] Analog joystick and gamepad support
326 Specifies type or capabilities of an analog joystick
327 connected to one of 16 gameports
328 Format: <type1>,<type2>,..<type16>
331 Power management functions (SPARCstation-4/5 + deriv.)
333 Disable APC CPU standby support. SPARCstation-Fox does
334 not play well with APC CPU idle - disable it if you have
335 APC and your system crashes randomly.
337 apic= [APIC,i386] Advanced Programmable Interrupt Controller
338 Change the output verbosity whilst booting
339 Format: { quiet (default) | verbose | debug }
340 Change the amount of debugging information output
341 when initialising the APIC and IO-APIC components.
343 apm= [APM] Advanced Power Management
344 See header of arch/x86/kernel/apm_32.c.
346 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
347 Format: <io>,<irq>,<nodeID>
351 atarimouse= [HW,MOUSE] Atari Mouse
353 atascsi= [HW,SCSI] Atari SCSI
355 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
356 EzKey and similar keyboards
358 atkbd.reset= [HW] Reset keyboard during initialization
360 atkbd.set= [HW] Select keyboard code set
361 Format: <int> (2 = AT (default), 3 = PS/2)
363 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
366 atkbd.softraw= [HW] Choose between synthetic and real raw mode
367 Format: <bool> (0 = real, 1 = synthetic (default))
369 atkbd.softrepeat= [HW]
370 Use software keyboard repeat
374 baycom_epp= [HW,AX25]
377 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
379 See header of drivers/net/hamradio/baycom_par.c.
381 baycom_ser_fdx= [HW,AX25]
382 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
383 Format: <io>,<irq>,<mode>[,<baud>]
384 See header of drivers/net/hamradio/baycom_ser_fdx.c.
386 baycom_ser_hdx= [HW,AX25]
387 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
388 Format: <io>,<irq>,<mode>
389 See header of drivers/net/hamradio/baycom_ser_hdx.c.
391 boot_delay= Milliseconds to delay each printk during boot.
392 Values larger than 10 seconds (10000) are changed to
396 bootmem_debug [KNL] Enable bootmem allocator debug messages.
398 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
399 bttv.radio= Most important insmod options are available as
401 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
402 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
405 See drivers/scsi/BusLogic.c, comment before function
406 BusLogic_ParseDriverOptions().
408 c101= [NET] Moxa C101 synchronous serial card
410 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
411 Sometimes CPU hardware bugs make them report the cache
412 size incorrectly. The kernel will attempt work arounds
413 to fix known problems, but for some CPUs it is not
414 possible to determine what the correct size should be.
415 This option provides an override for these situations.
417 security= [SECURITY] Choose a security module to enable at boot.
418 If this boot parameter is not specified, only the first
419 security module asking for security registration will be
420 loaded. An invalid security module name will be treated
421 as if no module has been chosen.
424 [SECURITY] Disable capabilities. This would normally
425 be used only if an alternative security model is to be
426 configured. Potentially dangerous and should only be
427 used if you are entirely sure of the consequences.
429 ccw_timeout_log [S390]
430 See Documentation/s390/CommonIO for details.
432 cgroup_disable= [KNL] Disable a particular controller
433 Format: {name of the controller(s) to disable}
434 {Currently supported controllers - "memory"}
436 checkreqprot [SELINUX] Set initial checkreqprot flag value.
437 Format: { "0" | "1" }
438 See security/selinux/Kconfig help text.
439 0 -- check protection applied by kernel (includes
440 any implied execute protection).
441 1 -- check protection requested by application.
442 Default value is set via a kernel config option.
443 Value can be changed at runtime via
444 /selinux/checkreqprot.
447 See Documentation/s390/CommonIO for details.
449 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
451 Forces specified clocksource (if available) to be used
452 when calculating gettimeofday(). If specified
453 clocksource is not available, it defaults to PIT.
454 Format: { pit | tsc | cyclone | pmtmr }
456 clocksource= [GENERIC_TIME] Override the default clocksource
458 Override the default clocksource and use the clocksource
459 with the name specified.
460 Some clocksource names to choose from, depending on
462 [all] jiffies (this is the base, fallback clocksource)
464 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
465 pxa_timer,timer3,32k_counter,timer0_1
467 [X86-32] pit,hpet,tsc,vmi-timer;
468 scx200_hrt on Geode; cyclone on IBM x440
476 clearcpuid=BITNUM [X86]
477 Disable CPUID feature X for the kernel. See
478 arch/x86/include/asm/cpufeature.h for the valid bit
479 numbers. Note the Linux specific bits are not necessarily
480 stable over kernel options, but the vendor specific
482 Also note that user programs calling CPUID directly
483 or using the feature without checking anything
484 will still see it. This just prevents it from
485 being used by the kernel or shown in /proc/cpuinfo.
486 Also note the kernel might malfunction if you disable
489 code_bytes [IA32/X86_64] How many bytes of object code to print
494 hpet= [X86-32,HPET] option to control HPET usage
495 Format: { enable (default) | disable | force }
496 disable: disable HPET and use PIT instead
497 force: allow force enabled of undocumented chips (ICH4,
500 com20020= [HW,NET] ARCnet - COM20020 chipset
502 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
504 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
508 ARCnet - COM90xx chipset (memory-mapped buffers)
509 Format: <io>[,<irq>[,<memstart>]]
511 condev= [HW,S390] console device
514 console= [KNL] Output console device and options.
516 tty<n> Use the virtual console device <n>.
520 Use the specified serial port. The options are of
521 the form "bbbbpnf", where "bbbb" is the baud rate,
522 "p" is parity ("n", "o", or "e"), "n" is number of
523 bits, and "f" is flow control ("r" for RTS or
524 omit it). Default is "9600n8".
526 See Documentation/serial-console.txt for more
528 Documentation/networking/netconsole.txt for an
531 uart[8250],io,<addr>[,options]
532 uart[8250],mmio,<addr>[,options]
533 Start an early, polled-mode console on the 8250/16550
534 UART at the specified I/O port or MMIO address,
535 switching to the matching ttyS device later. The
536 options are the same as for ttyS, above.
538 If the device connected to the port is not a TTY but a braille
539 device, prepend "brl," before the device type, for instance
541 For now, only VisioBraille is supported.
543 earlycon= [KNL] Output early console device and options.
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 The options are the same as for ttyS, above.
551 [HW] Never suspend the console
552 Disable suspending of consoles during suspend and
553 hibernate operations. Once disabled, debugging
554 messages can reach various consoles while the rest
555 of the system is being put to sleep (ie, while
556 debugging driver suspend/resume hooks). This may
557 not work reliably with all consoles, but is known
558 to work with serial and VGA consoles.
561 [KNL] Change the default value for
562 /proc/<pid>/coredump_filter.
563 See also Documentation/filesystems/proc.txt.
565 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
567 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
569 crashkernel=nn[KMG]@ss[KMG]
570 [KNL] Reserve a chunk of physical memory to
571 hold a kernel to switch to with kexec on panic.
573 crashkernel=range1:size1[,range2:size2,...][@offset]
574 [KNL] Same as above, but depends on the memory
575 in the running system. The syntax of range is
576 start-[end] where start and end are both
577 a memory unit (amount[KMG]). See also
578 Documentation/kdump/kdump.txt for a example.
583 cs89x0_media= [HW,NET]
584 Format: { rj45 | aui | bnc }
587 See header of drivers/s390/block/dasd_devmap.c.
589 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
590 (one device per port)
591 Format: <port#>,<type>
592 See also Documentation/input/joystick-parport.txt
594 debug [KNL] Enable kernel debugging (events log level).
597 [KNL] verbose self-tests
599 Print debugging info while doing the locking API
601 We default to 0 (no extra messages), setting it to
602 1 will print _a lot_ more information - normally
603 only useful to kernel developers.
605 debug_objects [KNL] Enable object debugging
607 debugpat [X86] Enable PAT debugging
609 decnet.addr= [HW,NET]
610 Format: <area>[,<node>]
611 See also Documentation/networking/decnet.txt.
614 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
615 Change the default blue palette of the console.
616 This is a 16-member array composed of values
620 Format: <green0>,<green1>,<green2>,...,<green15>
621 Change the default green palette of the console.
622 This is a 16-member array composed of values
626 Format: <red0>,<red1>,<red2>,...,<red15>
627 Change the default red palette of the console.
628 This is a 16-member array composed of values
634 Set system-wide default UTF-8 mode for all tty's.
635 Default is 1, i.e. UTF-8 mode is enabled for all
636 newly opened terminals.
639 Set number of hash buckets for dentry cache.
642 IO parameters + enable/disable command.
644 digiepca= [HW,SERIAL]
645 See drivers/char/README.epca and
646 Documentation/serial/digiepca.txt.
648 disable_mtrr_cleanup [X86]
649 enable_mtrr_cleanup [X86]
650 The kernel tries to adjust MTRR layout from continuous
651 to discrete, to make X server driver able to add WB
652 entry later. This parameter enables/disables that.
654 mtrr_chunk_size=nn[KMG] [X86]
655 used for mtrr cleanup. It is largest continous chunk
656 that could hold holes aka. UC entries.
658 mtrr_gran_size=nn[KMG] [X86]
659 Used for mtrr cleanup. It is granularity of mtrr block.
661 Large value could prevent small alignment from
664 mtrr_spare_reg_nr=n [X86]
666 Range: 0,7 : spare reg number
668 Used for mtrr cleanup. It is spare mtrr entries number.
669 Set to 2 or more if your graphical card needs more.
671 disable_mtrr_trim [X86, Intel and AMD only]
672 By default the kernel will trim any uncacheable
673 memory out of your available memory pool based on
674 MTRR settings. This parameter disables that behavior,
675 possibly causing your machine to run very slowly.
677 dmasound= [HW,OSS] Sound subsystem buffers
683 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
685 earlyprintk=serial[,ttySn[,baudrate]]
688 Append ",keep" to not disable it when the real console
691 Only vga or serial or usb debug port at a time.
693 Currently only ttyS0 and ttyS1 are supported.
695 Interaction with the standard serial driver is not
698 The VGA output is eventually overwritten by the real
704 Format: {"off" | "on" | "skip[mbr]"}
706 eisa_irq_edge= [PARISC,HW]
707 See header of drivers/parisc/eisa.c.
710 See comment before function elanfreq_setup() in
711 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
714 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
715 See Documentation/block/as-iosched.txt and
716 Documentation/block/deadline-iosched.txt for details.
718 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
719 Specifies physical address of start of kernel core
720 image elf header. Generally kexec loader will
721 pass this option to capture kernel.
722 See Documentation/kdump/kdump.txt for details.
724 enforcing [SELINUX] Set initial enforcing status.
726 See security/selinux/Kconfig help text.
727 0 -- permissive (log only, no denials).
728 1 -- enforcing (deny and log).
730 Value can be changed at runtime via /selinux/enforce.
732 ether= [HW,NET] Ethernet cards parameters
733 This option is obsoleted by the "netdev=" option, which
734 has equivalent usage. See its documentation for details.
736 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
741 fail_make_request=[KNL]
742 General fault injection mechanism.
743 Format: <interval>,<probability>,<space>,<times>
744 See also /Documentation/fault-injection/.
747 See header of drivers/scsi/fd_mcs.c.
750 See header of drivers/scsi/fdomain.c.
753 See Documentation/blockdev/floppy.txt.
755 force_pal_cache_flush
756 [IA-64] Avoid check_sal_cache_flush which may hang on
757 buggy SAL_CACHE_FLUSH implementations. Using this
758 parameter will force ia64_sal_cache_flush to call
759 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
762 [ftrace] will set and start the specified tracer
763 as early as possible in order to facilitate early
767 [ftrace] will dump the trace buffers on oops.
770 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
771 support via parallel port (up to 5 devices per port)
772 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
773 See also Documentation/input/joystick-parport.txt
777 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
782 See header of drivers/scsi/gdth.c.
784 gpt [EFI] Forces disk with valid GPT signature but
785 invalid Protective MBR to be treated as GPT.
789 hashdist= [KNL,NUMA] Large hashes allocated during boot
790 are distributed across NUMA nodes. Defaults on
791 for IA-64, off otherwise.
792 Format: 0 | 1 (for off | on)
794 hcl= [IA-64] SGI's Hardware Graph compatibility layer
796 hd= [EIDE] (E)IDE hard drive subsystem geometry
797 Format: <cyl>,<head>,<sect>
799 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
800 size of <nn>. This works even on boxes that have no
801 highmem otherwise. This also works to reduce highmem
802 size on bigger boxes.
804 highres= [KNL] Enable/disable high resolution timer mode.
805 Valid parameters: "on", "off"
809 See Documentation/isdn/README.HiSax.
811 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
812 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
813 On x86-64 and powerpc, this option can be specified
814 multiple times interleaved with hugepages= to reserve
815 huge pages of different sizes. Valid pages sizes on
816 x86-64 are 2M (when the CPU supports "pse") and 1G
817 (when the CPU supports the "pdpe1gb" cpuinfo flag)
818 Note that 1GB pages can only be allocated at boot time
819 using hugepages= and not freed afterwards.
821 [same as hugepagesz=] The size of the default
822 HugeTLB page size. This is the size represented by
823 the legacy /proc/ hugepages APIs, used for SHM, and
824 default size when mounting hugetlbfs filesystems.
825 Defaults to the default architecture's huge page size
830 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
831 terminal devices. Valid values: 0..8
833 i2c_bus= [HW] Override the default board specific I2C bus speed
834 or register an additional I2C bus that is not
835 registered from board initialization code.
839 i8042.debug [HW] Toggle i8042 debug mode
840 i8042.direct [HW] Put keyboard port into non-translated mode
841 i8042.dumbkbd [HW] Pretend that controller can only read data from
842 keyboard and cannot control its state
843 (Don't attempt to blink the leds)
844 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
845 i8042.nokbd [HW] Don't check/create keyboard port
846 i8042.noloop [HW] Disable the AUX Loopback command while probing
848 i8042.nomux [HW] Don't check presence of an active multiplexing
850 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
853 [HW] Frequency with which keyboard LEDs should blink
854 when kernel panics (default is 0.5 sec)
855 i8042.reset [HW] Reset the controller during init and cleanup
856 i8042.unlock [HW] Unlock (ignore) the keylock
860 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
861 indicates that the driver is running on unsupported
863 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
864 does not match list of supported models.
866 [HW] Report power status in /proc/i8k
867 (disabled by default)
868 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
871 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
872 See Documentation/mca.txt.
875 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
877 ide-core.nodma= [HW] (E)IDE subsystem
878 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
879 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
880 .chs .ignore_cable are additional options
881 See Documentation/ide/ide.txt.
883 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
884 See Documentation/ide/ide.txt.
887 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
888 Poll forces a polling idle loop that can slightly
889 improve the performance of waking up a idle CPU, but
890 will use a lot of power and make the system run hot.
892 idle=mwait: On systems which support MONITOR/MWAIT but
893 the kernel chose to not use it because it doesn't save
894 as much power as a normal idle loop, use the
895 MONITOR/MWAIT idle loop anyways. Performance should be
896 the same as idle=poll.
897 idle=halt: Halt is forced to be used for CPU idle.
898 In such case C2/C3 won't be used again.
899 idle=nomwait: Disable mwait for CPU C-states
901 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
902 Claim all unknown PCI IDE storage controllers.
904 ignore_loglevel [KNL]
905 Ignore loglevel setting - this will print /all/
906 kernel messages to the console. Useful for debugging.
909 Set number of hash buckets for inode cache.
912 See header of drivers/scsi/in2000.c.
916 Run specified binary instead of /sbin/init as init
919 initcall_debug [KNL] Trace initcalls as they are executed. Useful
920 for working out where the kernel is dying during
923 initrd= [BOOT] Specify the location of the initial ramdisk
925 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
930 iomem= Disable strict checking of access to MMIO memory
931 strict regions from userspace.
947 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
949 Enable intel iommu driver.
951 Disable intel iommu driver.
952 igfx_off [Default Off]
953 By default, gfx is mapped as normal device. If a gfx
954 device has a dedicated DMAR unit, the DMAR unit is
955 bypassed by not enabling DMAR with this option. In
956 this case, gfx device will use physical address for
959 With this option iommu will not optimize to look
960 for io virtual address below 32 bit forcing dual
961 address cycle on pci bus for cards supporting greater
962 than 32 bit addressing. The default is to look
963 for translation below 32 bit and if not available
964 then look in the higher range.
966 With this option on every unmap_single operation will
967 result in a hardware IOTLB flush operation as opposed
968 to batching them for performance.
970 io_delay= [X86-32,X86-64] I/O delay method
972 Standard port 0x80 based delay
974 Alternate port 0xed based delay (needed on some systems)
976 Simple two microseconds delay
980 io7= [HW] IO7 for Marvel based alpha systems
981 See comment before marvel_specify_io7 in
982 arch/alpha/kernel/core_marvel.c.
985 See Documentation/filesystems/nfsroot.txt.
987 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
988 See comment before ip2_setup() in
989 drivers/char/ip2/ip2base.c.
991 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
992 See header of drivers/scsi/ips.c.
994 ports= [IP_VS_FTP] IPVS ftp helper module
996 Up to 8 (IP_VS_APP_MAX_PORTS) ports
998 Format: <port>,<port>....
1001 When an interrupt is not handled search all handlers
1002 for it. Intended to get systems with badly broken
1006 When an interrupt is not handled search all handlers
1007 for it. Also check all handlers each timer
1008 interrupt. Intended to get systems with badly broken
1012 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1014 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1016 <cpu number>,...,<cpu number>
1018 <cpu number>-<cpu number>
1019 (must be a positive range in ascending order)
1021 <cpu number>,...,<cpu number>-<cpu number>
1023 This option can be used to specify one or more CPUs
1024 to isolate from the general SMP balancing and scheduling
1025 algorithms. You can move a process onto or off an
1026 "isolated" CPU via the CPU affinity syscalls or cpuset.
1027 <cpu number> begins at 0 and the maximum value is
1028 "number of CPUs in system - 1".
1030 This option is the preferred way to isolate CPUs. The
1031 alternative -- manually setting the CPU mask of all
1032 tasks in the system -- can cause problems and
1033 suboptimal load balancer performance.
1037 js= [HW,JOY] Analog joystick
1038 See Documentation/input/joystick.txt.
1040 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1041 specifies the amount of memory usable by the kernel
1042 for non-movable allocations. The requested amount is
1043 spread evenly throughout all nodes in the system. The
1044 remaining memory in each node is used for Movable
1045 pages. In the event, a node is too small to have both
1046 kernelcore and Movable pages, kernelcore pages will
1047 take priority and other nodes will have a larger number
1048 of kernelcore pages. The Movable zone is used for the
1049 allocation of pages that may be reclaimed or moved
1050 by the page migration subsystem. This means that
1051 HugeTLB pages may not be allocated from this zone.
1052 Note that allocations like PTEs-from-HighMem still
1053 use the HighMem zone if it exists, and the Normal
1054 zone if it does not.
1056 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1057 is similar to kernelcore except it specifies the
1058 amount of memory used for migratable allocations.
1059 If both kernelcore and movablecore is specified,
1060 then kernelcore will be at *least* the specified
1061 value but may be more. If movablecore on its own
1062 is specified, the administrator must be careful
1063 that the amount of memory usable for all allocations
1068 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1071 kgdboc= [HW] kgdb over consoles.
1072 Requires a tty driver that supports console polling.
1073 (only serial suported for now)
1074 Format: <serial_device>[,baud]
1076 kmac= [MIPS] korina ethernet MAC address.
1077 Configure the RouterBoard 532 series on-chip
1078 Ethernet adapter MAC address.
1084 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1087 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1090 libata.dma= [LIBATA] DMA control
1091 libata.dma=0 Disable all PATA and SATA DMA
1092 libata.dma=1 PATA and SATA Disk DMA only
1093 libata.dma=2 ATAPI (CDROM) DMA only
1094 libata.dma=4 Compact Flash DMA only
1095 Combinations also work, so libata.dma=3 enables DMA
1096 for disks and CDROMs, but not CFs.
1098 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1102 libata.force= [LIBATA] Force configurations. The format is comma
1103 separated list of "[ID:]VAL" where ID is
1104 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1105 matching port, link or device. Basically, it matches
1106 the ATA ID string printed on console by libata. If
1107 the whole ID part is omitted, the last PORT and DEVICE
1108 values are used. If ID hasn't been specified yet, the
1109 configuration applies to all ports, links and devices.
1111 If only DEVICE is omitted, the parameter applies to
1112 the port and all links and devices behind it. DEVICE
1113 number of 0 either selects the first device or the
1114 first fan-out link behind PMP device. It does not
1115 select the host link. DEVICE number of 15 selects the
1116 host link and device attached to it.
1118 The VAL specifies the configuration to force. As long
1119 as there's no ambiguity shortcut notation is allowed.
1120 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1121 The following configurations can be forced.
1123 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1124 Any ID with matching PORT is used.
1126 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1128 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1129 udma[/][16,25,33,44,66,100,133] notation is also
1132 * [no]ncq: Turn on or off NCQ.
1134 * nohrst, nosrst, norst: suppress hard, soft
1137 If there are multiple matching configurations changing
1138 the same attribute, the last one is used.
1140 lmb=debug [KNL] Enable lmb debug messages.
1142 load_ramdisk= [RAM] List of ramdisks to load from floppy
1143 See Documentation/blockdev/ramdisk.txt.
1145 lockd.nlm_grace_period=P [NFS] Assign grace period.
1148 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1151 lockd.nlm_timeout=T [NFS] Assign timeout value.
1154 lockd.nlm_udpport=M [NFS] Assign UDP port.
1157 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1160 loglevel= All Kernel Messages with a loglevel smaller than the
1161 console loglevel will be printed to the console. It can
1162 also be changed with klogd or other programs. The
1163 loglevels are defined as follows:
1165 0 (KERN_EMERG) system is unusable
1166 1 (KERN_ALERT) action must be taken immediately
1167 2 (KERN_CRIT) critical conditions
1168 3 (KERN_ERR) error conditions
1169 4 (KERN_WARNING) warning conditions
1170 5 (KERN_NOTICE) normal but significant condition
1171 6 (KERN_INFO) informational
1172 7 (KERN_DEBUG) debug-level messages
1174 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1175 Format: { n | nk | nM }
1176 n must be a power of two. The default size
1177 is set in the kernel config file.
1179 logo.nologo [FB] Disables display of the built-in Linux logo.
1180 This may be used to provide more screen space for
1181 kernel log messages and is useful when debugging
1182 kernel boot problems.
1184 lp=0 [LP] Specify parallel ports to use, e.g,
1185 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1186 lp=reset first parallel port). 'lp=0' disables the
1187 lp=auto printer driver. 'lp=reset' (which can be
1188 specified in addition to the ports) causes
1189 attached printers to be reset. Using
1190 lp=port1,port2,... specifies the parallel ports
1191 to associate lp devices with, starting with
1192 lp0. A port specification may be 'none' to skip
1193 that lp device, or a parport name such as
1194 'parport0'. Specifying 'lp=auto' instead of a
1195 port specification list means that device IDs
1196 from each port should be examined, to see if
1197 an IEEE 1284-compliant printer is attached; if
1198 so, the driver will manage that printer.
1199 See also header of drivers/char/lp.c.
1202 Sets loops_per_jiffy to given constant, thus avoiding
1203 time-consuming boot-time autodetection (up to 250 ms per
1204 CPU). 0 enables autodetection (default). To determine
1205 the correct value for your kernel, boot with normal
1206 autodetection and see what value is printed. Note that
1207 on SMP systems the preset will be applied to all CPUs,
1208 which is likely to cause problems if your CPUs need
1209 significantly divergent settings. An incorrect value
1210 will cause delays in the kernel to be wrong, leading to
1211 unpredictable I/O errors and other breakage. Although
1212 unlikely, in the extreme case this might damage your
1216 Format: <io>,<irq>,<dma>
1218 mac5380= [HW,SCSI] Format:
1219 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1221 machvec= [IA64] Force the use of a particular machine-vector
1222 (machvec) in a generic kernel.
1223 Example: machvec=hpzx1_swiotlb
1225 max_loop= [LOOP] Maximum number of loopback devices that can
1229 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1230 should make use of. maxcpus=n : n >= 0 limits the
1231 kernel to using 'n' processors. n=0 is a special case,
1232 it is equivalent to "nosmp", which also disables
1235 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1236 or equal to this physical address is ignored.
1238 max_luns= [SCSI] Maximum number of LUNs to probe.
1239 Should be between 1 and 2^32-1.
1242 [SCSI] Maximum number of LUNs received.
1243 Should be between 1 and 16384.
1247 mce [X86-32] Machine Check Exception
1249 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1251 md= [HW] RAID subsystems devices and level
1252 See Documentation/md.txt.
1255 Format: <first>,<last>
1256 Specifies range of consoles to be captured by the MDA.
1258 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1259 Amount of memory to be used when the kernel is not able
1260 to see the whole system memory or for test.
1261 [X86-32] Use together with memmap= to avoid physical
1262 address space collisions. Without memmap= PCI devices
1263 could be placed at addresses belonging to unused RAM.
1265 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1269 [KNL,SH] Allow user to override the default size for
1270 per-device physically contiguous DMA buffers.
1272 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1273 E820 memory map, as specified by the user.
1274 Such memmap=exactmap lines can be constructed based on
1275 BIOS output or other requirements. See the memmap=nn@ss
1278 memmap=nn[KMG]@ss[KMG]
1279 [KNL] Force usage of a specific region of memory
1280 Region of memory to be used, from ss to ss+nn.
1282 memmap=nn[KMG]#ss[KMG]
1283 [KNL,ACPI] Mark specific memory as ACPI data.
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 reserved.
1288 Region of memory to be used, from ss to ss+nn.
1289 Example: Exclude memory from 0x18690000-0x1869ffff
1290 memmap=64K$0x18690000
1292 memmap=0x10000$0x18690000
1294 memory_corruption_check=0/1 [X86]
1295 Some BIOSes seem to corrupt the first 64k of
1296 memory when doing things like suspend/resume.
1297 Setting this option will scan the memory
1298 looking for corruption. Enabling this will
1299 both detect corruption and prevent the kernel
1300 from using the memory being corrupted.
1301 However, its intended as a diagnostic tool; if
1302 repeatable BIOS-originated corruption always
1303 affects the same memory, you can use memmap=
1304 to prevent the kernel from using that memory.
1306 memory_corruption_check_size=size [X86]
1307 By default it checks for corruption in the low
1308 64k, making this memory unavailable for normal
1309 use. Use this parameter to scan for
1310 corruption in more or less memory.
1312 memory_corruption_check_period=seconds [X86]
1313 By default it checks for corruption every 60
1314 seconds. Use this parameter to check at some
1315 other rate. 0 disables periodic checking.
1317 memtest= [KNL,X86] Enable memtest
1319 range: 0,4 : pattern number
1320 default : 0 <disable>
1322 meye.*= [HW] Set MotionEye Camera parameters
1323 See Documentation/video4linux/meye.txt.
1325 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1326 Multi-Function General Purpose Timers on AMD Geode
1329 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1330 the BIOS has incorrectly applied a workaround. TinyBIOS
1331 version 0.98 is known to be affected, 0.99 fixes the
1332 problem by letting the user disable the workaround.
1336 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1337 physical address is ignored.
1340 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1341 parameter allows control of the logging verbosity for
1342 the additional memory initialisation checks. A value
1343 of 0 disables mminit logging and a level of 4 will
1344 log everything. Information is printed at KERN_DEBUG
1345 so loglevel=8 may also need to be specified.
1348 [MOUSE] Maximum time between finger touching and
1349 leaving touchpad surface for touch to be considered
1350 a tap and be reported as a left button click (for
1351 touchpads working in absolute mode only).
1353 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1354 reporting absolute coordinates, such as tablets
1355 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1356 reporting absolute coordinates, such as tablets
1361 MTD_Partition= [MTD]
1362 Format: <name>,<region-number>,<size>,<offset>
1364 MTD_Region= [MTD] Format:
1365 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1368 See drivers/mtd/cmdlinepart.c.
1371 ARM/S3C2412 JIVE boot control
1373 See arch/arm/mach-s3c2412/mach-jive.c
1375 mtouchusb.raw_coordinates=
1376 [HW] Make the MicroTouch USB driver use raw coordinates
1377 ('y', default) or cooked coordinates ('n')
1379 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1382 See header of drivers/scsi/NCR_D700.c.
1386 ncr53c400= [HW,SCSI]
1388 ncr53c400a= [HW,SCSI]
1390 ncr53c406a= [HW,SCSI]
1392 ncr53c8xx= [HW,SCSI]
1394 netdev= [NET] Network devices parameters
1395 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1396 Note that mem_start is often overloaded to mean
1397 something different and driver-specific.
1398 This usage is only documented in each driver source
1402 [NETFILTER] Enable connection tracking flow accounting
1403 0 to disable accounting
1404 1 to enable accounting
1405 Default value depends on CONFIG_NF_CT_ACCT that is
1406 going to be removed in 2.6.29.
1409 See Documentation/filesystems/nfsroot.txt.
1411 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1412 See Documentation/filesystems/nfsroot.txt.
1414 nfs.callback_tcpport=
1415 [NFS] set the TCP port on which the NFSv4 callback
1416 channel should listen.
1418 nfs.idmap_cache_timeout=
1419 [NFS] set the maximum lifetime for idmapper cache
1423 [NFS] enable 64-bit inode numbers.
1424 If zero, the NFS client will fake up a 32-bit inode
1425 number for the readdir() and stat() syscalls instead
1426 of returning the full 64-bit number.
1427 The default is to return 64-bit inode numbers.
1429 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1430 when a NMI is triggered.
1431 Format: [state][,regs][,debounce][,die]
1433 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1434 Format: [panic,][num]
1436 0 - turn nmi_watchdog off
1437 1 - use the IO-APIC timer for the NMI watchdog
1438 2 - use the local APIC for the NMI watchdog using
1439 a performance counter. Note: This will use one performance
1440 counter and the local APIC's performance vector.
1441 When panic is specified panic when an NMI watchdog timeout occurs.
1442 This is useful when you use a panic=... timeout and need the box
1444 Instead of 1 and 2 it is possible to use the following
1445 symbolic names: lapic and ioapic
1446 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1448 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1449 emulation library even if a 387 maths coprocessor
1452 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1453 caches in the slab allocator. Saves per-node memory,
1454 but will impact performance.
1458 noapic [SMP,APIC] Tells the kernel to not make use of any
1459 IOAPICs that may be present in the system.
1461 nobats [PPC] Do not use BATs for mapping kernel lowmem
1462 on "Classic" PPC cores.
1466 nodelayacct [KNL] Disable per-task delay accounting
1468 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1470 nodsp [SH] Disable hardware DSP at boot time.
1472 noefi [X86-32,X86-64] Disable EFI runtime services support.
1476 noexec [X86-32,X86-64]
1477 On X86-32 available only on PAE configured kernels.
1478 noexec=on: enable non-executable mappings (default)
1479 noexec=off: disable non-executable mappings
1482 This affects only 32-bit executables.
1483 noexec32=on: enable non-executable mappings (default)
1484 read doesn't imply executable mappings
1485 noexec32=off: disable non-executable mappings
1486 read implies executable mappings
1488 nofpu [SH] Disable hardware FPU at boot time.
1490 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1491 register save and restore. The kernel will only save
1492 legacy floating-point registers on task switch.
1494 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1498 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1499 instruction doesn't work correctly and not to
1502 no_file_caps Tells the kernel not to honor file capabilities. The
1503 only way then for a file to be executed with privilege
1504 is to be setuid root or executed by root.
1506 nohalt [IA-64] Tells the kernel not to use the power saving
1507 function PAL_HALT_LIGHT when idle. This increases
1508 power-consumption. On the positive side, it reduces
1509 interrupt wake-up latency, which may improve performance
1510 in certain environments such as networked servers or
1513 nohz= [KNL] Boottime enable/disable dynamic ticks
1514 Valid arguments: on, off
1517 noirqdebug [X86-32] Disables the code which attempts to detect and
1518 disable unhandled interrupt sources.
1520 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1521 broken timer IRQ sources.
1523 noisapnp [ISAPNP] Disables ISA PnP code.
1525 noinitrd [RAM] Tells the kernel not to load any configured
1530 nojitter [IA64] Disables jitter checking for ITC timers.
1532 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1534 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1536 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1538 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1539 default x2apic cluster mode on platforms
1542 noltlbs [PPC] Do not use large page/tlb entries for kernel
1543 lowmem mapping on PPC40x.
1545 nomca [IA-64] Disable machine check abort handling
1547 nomce [X86-32] Machine Check Exception
1549 nomfgpt [X86-32] Disable Multi-Function General Purpose
1550 Timer usage (for AMD Geode machines).
1552 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1554 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1555 with UP alternatives
1557 noresidual [PPC] Don't use residual data on PReP machines.
1559 noresume [SWSUSP] Disables resume and restores original swap
1562 no-scroll [VGA] Disables scrollback.
1563 This is required for the Braillex ib80-piezo Braille
1564 reader made by F.H. Papenmeier (Germany).
1568 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1570 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1571 and disable the IO APIC. legacy for "maxcpus=0".
1573 nosoftlockup [KNL] Disable the soft-lockup detector.
1575 noswapaccount [KNL] Disable accounting of swap in memory resource
1576 controller. (See Documentation/controllers/memory.txt)
1578 nosync [HW,M68K] Disables sync negotiation for all devices.
1580 notsc [BUGS=X86-32] Disable Time Stamp Counter
1582 nousb [USB] Disable the USB subsystem
1586 nptcg= [IA64] Override max number of concurrent global TLB
1587 purges which is reported from either PAL_VM_SUMMARY or
1590 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1591 one of ['zone', 'node', 'default'] can be specified
1592 This can be set from sysctl after boot.
1593 See Documentation/sysctl/vm.txt for details.
1595 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1597 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1598 See Documentation/debugging-via-ohci1394.txt for more
1601 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1602 Rather than timing out after 20 ms if an EC
1603 command is not properly ACKed, override the length
1604 of the timeout. We have interrupts disabled while
1605 waiting for the ACK, so if this is set too high
1606 interrupts *may* be lost!
1611 oprofile.timer= [HW]
1612 Use timer interrupt instead of performance counters
1614 osst= [HW,SCSI] SCSI Tape Driver
1615 Format: <buffer_size>,<write_threshold>
1616 See also Documentation/scsi/st.txt.
1618 panic= [KNL] Kernel behaviour on panic
1621 parkbd.port= [HW] Parallel port number the keyboard adapter is
1622 connected to, default is 0.
1624 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1625 0 for XT, 1 for AT (default is AT).
1628 parport= [HW,PPT] Specify parallel ports. 0 disables.
1629 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1630 Use 'auto' to force the driver to use any
1631 IRQ/DMA settings detected (the default is to
1632 ignore detected IRQ/DMA settings because of
1633 possible conflicts). You can specify the base
1634 address, IRQ, and DMA settings; IRQ and DMA
1635 should be numbers, or 'auto' (for using detected
1636 settings on that particular port), or 'nofifo'
1637 (to avoid using a FIFO even if it is detected).
1638 Parallel ports are assigned in the order they
1639 are specified on the command line, starting
1642 parport_init_mode= [HW,PPT]
1643 Configure VIA parallel port to operate in
1644 a specific mode. This is necessary on Pegasos
1645 computer where firmware has no options for setting
1646 up parallel port mode and sets it to spp.
1647 Currently this function knows 686a and 8231 chips.
1648 Format: [spp|ps2|epp|ecp|ecpepp]
1650 pas2= [HW,OSS] Format:
1651 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1654 See header of drivers/scsi/pas16.c.
1657 Halt all CPUs after the first oops has been printed for
1658 the specified number of seconds. This is to be used if
1659 your oopses keep scrolling off the screen.
1664 See header of drivers/block/paride/pcd.c.
1665 See also Documentation/blockdev/paride.txt.
1667 pci=option[,option...] [PCI] various PCI subsystem options:
1668 off [X86] don't probe for the PCI bus
1669 bios [X86-32] force use of PCI BIOS, don't access
1670 the hardware directly. Use this if your machine
1671 has a non-standard PCI host bridge.
1672 nobios [X86-32] disallow use of PCI BIOS, only direct
1673 hardware access methods are allowed. Use this
1674 if you experience crashes upon bootup and you
1675 suspect they are caused by the BIOS.
1676 conf1 [X86] Force use of PCI Configuration
1678 conf2 [X86] Force use of PCI Configuration
1680 noaer [PCIE] If the PCIEAER kernel config parameter is
1681 enabled, this kernel boot option can be used to
1682 disable the use of PCIE advanced error reporting.
1683 nodomains [PCI] Disable support for multiple PCI
1684 root domains (aka PCI segments, in ACPI-speak).
1685 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1687 nomsi [MSI] If the PCI_MSI kernel config parameter is
1688 enabled, this kernel boot option can be used to
1689 disable the use of MSI interrupts system-wide.
1690 noioapicquirk [APIC] Disable all boot interrupt quirks.
1691 Safety option to keep boot IRQs enabled. This
1692 should never be necessary.
1693 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1694 primary IO-APIC for bridges that cannot disable
1695 boot IRQs. This fixes a source of spurious IRQs
1696 when the system masks IRQs.
1697 noioapicreroute [APIC] Disable workaround that uses the
1698 boot IRQ equivalent of an IRQ that connects to
1699 a chipset where boot IRQs cannot be disabled.
1700 The opposite of ioapicreroute.
1701 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1702 routing table. These calls are known to be buggy
1703 on several machines and they hang the machine
1704 when used, but on other computers it's the only
1705 way to get the interrupt routing table. Try
1706 this option if the kernel is unable to allocate
1707 IRQs or discover secondary PCI buses on your
1709 rom [X86] Assign address space to expansion ROMs.
1710 Use with caution as certain devices share
1711 address decoders between ROMs and other
1713 norom [X86] Do not assign address space to
1714 expansion ROMs that do not already have
1715 BIOS assigned address ranges.
1716 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1717 assigned automatically to PCI devices. You can
1718 make the kernel exclude IRQs of your ISA cards
1720 pirqaddr=0xAAAAA [X86] Specify the physical address
1721 of the PIRQ table (normally generated
1722 by the BIOS) if it is outside the
1723 F0000h-100000h range.
1724 lastbus=N [X86] Scan all buses thru bus #N. Can be
1725 useful if the kernel is unable to find your
1726 secondary buses and you want to tell it
1727 explicitly which ones they are.
1728 assign-busses [X86] Always assign all PCI bus
1729 numbers ourselves, overriding
1730 whatever the firmware may have done.
1731 usepirqmask [X86] Honor the possible IRQ mask stored
1732 in the BIOS $PIR table. This is needed on
1733 some systems with broken BIOSes, notably
1734 some HP Pavilion N5400 and Omnibook XE3
1735 notebooks. This will have no effect if ACPI
1736 IRQ routing is enabled.
1737 noacpi [X86] Do not use ACPI for IRQ routing
1738 or for PCI scanning.
1739 use_crs [X86] Use _CRS for PCI resource
1741 routeirq Do IRQ routing for all PCI devices.
1742 This is normally done in pci_enable_device(),
1743 so this option is a temporary workaround
1744 for broken drivers that don't call it.
1745 skip_isa_align [X86] do not align io start addr, so can
1746 handle more pci cards
1747 firmware [ARM] Do not re-enumerate the bus but instead
1748 just use the configuration from the
1749 bootloader. This is currently used on
1750 IXP2000 systems where the bus has to be
1751 configured a certain way for adjunct CPUs.
1752 noearly [X86] Don't do any early type 1 scanning.
1753 This might help on some broken boards which
1754 machine check when some devices' config space
1755 is read. But various workarounds are disabled
1756 and some IOMMU drivers will not work.
1757 bfsort Sort PCI devices into breadth-first order.
1758 This sorting is done to get a device
1759 order compatible with older (<= 2.4) kernels.
1760 nobfsort Don't sort PCI devices into breadth-first order.
1761 cbiosize=nn[KMG] The fixed amount of bus space which is
1762 reserved for the CardBus bridge's IO window.
1763 The default value is 256 bytes.
1764 cbmemsize=nn[KMG] The fixed amount of bus space which is
1765 reserved for the CardBus bridge's memory
1766 window. The default value is 64 megabytes.
1768 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1771 force Enable ASPM even on devices that claim not to support it.
1772 WARNING: Forcing ASPM on may cause system lockups.
1774 pcmv= [HW,PCMCIA] BadgePAD 4
1777 See Documentation/blockdev/paride.txt.
1779 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1782 See arch/parisc/kernel/pdc_chassis.c
1785 See Documentation/blockdev/paride.txt.
1788 See Documentation/blockdev/paride.txt.
1790 pirq= [SMP,APIC] Manual mp-table setup
1791 See Documentation/x86/i386/IO-APIC.txt.
1793 plip= [PPT,NET] Parallel port network link
1794 Format: { parport<nr> | timid | 0 }
1795 See also Documentation/parport.txt.
1797 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1798 Override pmtimer IOPort with a hex value.
1802 Enable PNP debug messages. This depends on the
1803 CONFIG_PNP_DEBUG_MESSAGES option.
1809 { on | off | curr | res | no-curr | no-res }
1812 [ISAPNP] Exclude IRQs for the autoconfiguration
1815 [ISAPNP] Exclude DMAs for the autoconfiguration
1817 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1818 Ranges are in pairs (I/O port base and size).
1821 [ISAPNP] Exclude memory regions for the
1823 Ranges are in pairs (memory base and size).
1825 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1826 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1827 These can also be switched on/off via
1828 <debugfs>/dynamic_printk/modules
1830 print-fatal-signals=
1831 [KNL] debug: print fatal signals
1832 print-fatal-signals=1: print segfault info to
1836 printk.time= Show timing data prefixed to each printk message line
1837 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1839 profile= [KNL] Enable kernel profiling via /proc/profile
1840 Format: [schedule,]<number>
1841 Param: "schedule" - profile schedule points.
1842 Param: <number> - step/bucket size as a power of 2 for
1843 statistical time based profiling.
1844 Param: "sleep" - profile D-state sleeping (millisecs).
1845 Requires CONFIG_SCHEDSTATS
1846 Param: "kvm" - profile VM exits.
1848 processor.max_cstate= [HW,ACPI]
1849 Limit processor to maximum C-state
1850 max_cstate=9 overrides any DMI blacklist limit.
1852 processor.nocst [HW,ACPI]
1853 Ignore the _CST method to determine C-states,
1854 instead using the legacy FADT method
1856 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1858 See Documentation/blockdev/ramdisk.txt.
1860 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1861 probe for; one of (bare|imps|exps|lifebook|any).
1862 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1864 psmouse.resetafter= [HW,MOUSE]
1865 Try to reset the device after so many bad packets
1868 [HW,MOUSE] Set desired mouse resolution, in dpi.
1869 psmouse.smartscroll=
1870 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1871 0 = disabled, 1 = enabled (default).
1873 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1875 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1878 See Documentation/blockdev/paride.txt.
1881 [KNL] Number of legacy pty's. Overwrites compiled-in
1884 quiet [KNL] Disable most log messages
1889 See Documentation/md.txt.
1891 ramdisk_blocksize= [RAM]
1892 See Documentation/blockdev/ramdisk.txt.
1894 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1895 See Documentation/blockdev/ramdisk.txt.
1897 rcupdate.blimit= [KNL,BOOT]
1898 Set maximum number of finished RCU callbacks to process
1901 rcupdate.qhimark= [KNL,BOOT]
1902 Set threshold of queued
1903 RCU callbacks over which batch limiting is disabled.
1905 rcupdate.qlowmark= [KNL,BOOT]
1906 Set threshold of queued RCU callbacks below which
1907 batch limiting is re-enabled.
1911 Run specified binary instead of /init from the ramdisk,
1912 used for early userspace startup. See initrd.
1914 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1915 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1916 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1919 [KNL, SMP] Set scheduler's default relax_domain_level.
1920 See Documentation/cpusets.txt.
1922 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1924 reservetop= [X86-32]
1926 Reserves a hole at the top of the kernel virtual
1929 reset_devices [KNL] Force drivers to reset the underlying device
1930 during initialization.
1933 Specify the partition device for software suspend
1935 resume_offset= [SWSUSP]
1936 Specify the offset from the beginning of the partition
1937 given by "resume=" at which the swap header is located,
1938 in <PAGE_SIZE> units (needed only for swap files).
1939 See Documentation/power/swsusp-and-swap-files.txt
1941 retain_initrd [RAM] Keep initrd memory after extraction
1943 rhash_entries= [KNL,NET]
1944 Set number of hash buckets for route cache
1946 riscom8= [HW,SERIAL]
1947 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1949 ro [KNL] Mount root device read-only on boot
1951 root= [KNL] Root filesystem
1953 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1954 mount the root filesystem
1956 rootflags= [KNL] Set root filesystem mount option string
1958 rootfstype= [KNL] Set root filesystem type
1960 rootwait [KNL] Wait (indefinitely) for root device to show up.
1961 Useful for devices that are detected asynchronously
1962 (e.g. USB and MMC devices).
1964 root_plug.vendor_id=
1965 [ROOTPLUG] Override the default vendor ID
1967 root_plug.product_id=
1968 [ROOTPLUG] Override the default product ID
1971 [ROOTPLUG] Enable debugging output
1973 rw [KNL] Mount root device read-write on boot
1975 S [KNL] Run init in single mode
1978 See drivers/net/irda/sa1100_ir.c.
1980 sbni= [NET] Granch SBNI12 leased line adapter
1982 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1983 Format: <io>[,<timeout>[,<isapnp>]]
1985 scsi_debug_*= [SCSI]
1986 See drivers/scsi/scsi_debug.c.
1988 scsi_default_dev_flags=
1989 [SCSI] SCSI default device flags
1992 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1993 Format: <vendor>:<model>:<flags>
1994 (flags are integer value)
1996 scsi_logging_level= [SCSI] a bit mask of logging levels
1997 See drivers/scsi/scsi_logging.h for bits. Also
1998 settable via sysctl at dev.scsi.logging_level
1999 (/proc/sys/dev/scsi/logging_level).
2000 There is also a nice 'scsi_logging_level' script in the
2001 S390-tools package, available for download at
2002 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2004 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2005 discovered. async scans them in kernel threads,
2006 allowing boot to proceed. none ignores them, expecting
2007 user space to do the scan.
2009 selinux [SELINUX] Disable or enable SELinux at boot time.
2010 Format: { "0" | "1" }
2011 See security/selinux/Kconfig help text.
2014 Default value is set via kernel config option.
2015 If enabled at boot time, /selinux/disable can be used
2016 later to disable prior to initial policy load.
2018 selinux_compat_net =
2019 [SELINUX] Set initial selinux_compat_net flag value.
2020 Format: { "0" | "1" }
2021 0 -- use new secmark-based packet controls
2022 1 -- use legacy packet controls
2023 Default value is 0 (preferred).
2024 Value can be changed at runtime via
2025 /selinux/compat_net.
2027 serialnumber [BUGS=X86-32]
2030 Maximal number of shapers.
2032 show_msr= [x86] show boot-time MSR settings
2033 Format: { <integer> }
2034 Show boot-time (BIOS-initialized) MSR settings.
2035 The parameter means the number of CPUs to show,
2036 for example 1 means boot CPU only.
2039 See header of drivers/scsi/sim710.c.
2046 slub_debug[=options[,slabs]] [MM, SLUB]
2047 Enabling slub_debug allows one to determine the
2048 culprit if slab objects become corrupted. Enabling
2049 slub_debug can create guard zones around objects and
2050 may poison objects when not in use. Also tracks the
2051 last alloc / free. For more information see
2052 Documentation/vm/slub.txt.
2054 slub_max_order= [MM, SLUB]
2055 Determines the maximum allowed order for slabs.
2056 A high setting may cause OOMs due to memory
2057 fragmentation. For more information see
2058 Documentation/vm/slub.txt.
2060 slub_min_objects= [MM, SLUB]
2061 The minimum number of objects per slab. SLUB will
2062 increase the slab order up to slub_max_order to
2063 generate a sufficiently large slab able to contain
2064 the number of objects indicated. The higher the number
2065 of objects the smaller the overhead of tracking slabs
2066 and the less frequently locks need to be acquired.
2067 For more information see Documentation/vm/slub.txt.
2069 slub_min_order= [MM, SLUB]
2070 Determines the mininum page order for slabs. Must be
2071 lower than slub_max_order.
2072 For more information see Documentation/vm/slub.txt.
2074 slub_nomerge [MM, SLUB]
2075 Disable merging of slabs with similar size. May be
2076 necessary if there is some reason to distinguish
2077 allocs to different slabs. Debug options disable
2078 merging on their own.
2079 For more information see Documentation/vm/slub.txt.
2082 Format: <io1>[,<io2>[,...,<io8>]]
2084 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2085 attempt to substitute SMP alternatives once at boot.
2087 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2088 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2089 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2090 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2091 smsc-ircc2.ircc_irq= [HW] IRQ line
2092 smsc-ircc2.ircc_dma= [HW] DMA channel
2093 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2094 0: Toshiba Satellite 1800 (GP data pin select)
2095 1: Fast pin select (default)
2098 snd-ad1816a= [HW,ALSA]
2100 snd-ad1848= [HW,ALSA]
2102 snd-ali5451= [HW,ALSA]
2104 snd-als100= [HW,ALSA]
2106 snd-als4000= [HW,ALSA]
2108 snd-azt2320= [HW,ALSA]
2110 snd-cmi8330= [HW,ALSA]
2112 snd-cmipci= [HW,ALSA]
2114 snd-cs4231= [HW,ALSA]
2116 snd-cs4232= [HW,ALSA]
2118 snd-cs4236= [HW,ALSA]
2120 snd-cs4281= [HW,ALSA]
2122 snd-cs46xx= [HW,ALSA]
2124 snd-dt019x= [HW,ALSA]
2126 snd-dummy= [HW,ALSA]
2128 snd-emu10k1= [HW,ALSA]
2130 snd-ens1370= [HW,ALSA]
2132 snd-ens1371= [HW,ALSA]
2134 snd-es968= [HW,ALSA]
2136 snd-es1688= [HW,ALSA]
2138 snd-es18xx= [HW,ALSA]
2140 snd-es1938= [HW,ALSA]
2142 snd-es1968= [HW,ALSA]
2144 snd-fm801= [HW,ALSA]
2146 snd-gusclassic= [HW,ALSA]
2148 snd-gusextreme= [HW,ALSA]
2150 snd-gusmax= [HW,ALSA]
2154 snd-ice1712= [HW,ALSA]
2156 snd-intel8x0= [HW,ALSA]
2158 snd-interwave= [HW,ALSA]
2163 snd-korg1212= [HW,ALSA]
2165 snd-maestro3= [HW,ALSA]
2167 snd-mpu401= [HW,ALSA]
2169 snd-mtpav= [HW,ALSA]
2171 snd-nm256= [HW,ALSA]
2173 snd-opl3sa2= [HW,ALSA]
2181 snd-opti93x= [HW,ALSA]
2185 snd-rme32= [HW,ALSA]
2187 snd-rme96= [HW,ALSA]
2189 snd-rme9652= [HW,ALSA]
2195 snd-sbawe= [HW,ALSA]
2197 snd-serial= [HW,ALSA]
2199 snd-sgalaxy= [HW,ALSA]
2201 snd-sonicvibes= [HW,ALSA]
2206 snd-sun-cs4231= [HW,ALSA]
2208 snd-trident= [HW,ALSA]
2210 snd-usb-audio= [HW,ALSA,USB]
2212 snd-via82xx= [HW,ALSA]
2214 snd-virmidi= [HW,ALSA]
2216 snd-wavefront= [HW,ALSA]
2218 snd-ymfpci= [HW,ALSA]
2221 [KNL] Should the soft-lockup detector generate panics.
2223 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2224 See Documentation/sonypi.txt
2226 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2227 See Documentation/serial/specialix.txt.
2229 spia_io_base= [HW,MTD]
2235 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2237 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2238 See Documentation/scsi/st.txt.
2241 Enabled the stack tracer on boot up.
2245 Set the STI (builtin display/keyboard on the HP-PARISC
2246 machines) console (graphic card) which should be used
2247 as the initial boot-console.
2248 See also comment in drivers/video/console/sticore.c.
2251 See comment in drivers/video/console/sticore.c.
2254 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2258 Control how the NFS server code allocates CPUs to
2259 service thread pools. Depending on how many NICs
2260 you have and where their interrupts are bound, this
2261 option will affect which CPUs will do NFS serving.
2262 Note: this parameter cannot be changed while the
2263 NFS server is running.
2265 auto the server chooses an appropriate mode
2266 automatically using heuristics
2267 global a single global pool contains all CPUs
2268 percpu one pool for each CPU
2269 pernode one pool for each NUMA node (equivalent
2270 to global on non-NUMA machines)
2272 swiotlb= [IA-64] Number of I/O TLB slabs
2276 sym53c416= [HW,SCSI]
2277 See header of drivers/scsi/sym53c416.c.
2279 sysrq_always_enabled
2281 Ignore sysrq setting - this boot parameter will
2282 neutralize any effect of /proc/sys/kernel/sysrq.
2283 Useful for debugging.
2286 See header of drivers/scsi/t128.c.
2290 test_suspend= [SUSPEND]
2291 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2292 standby suspend) as the system sleep state to briefly
2293 enter during system startup. The system is woken from
2294 this state using a wakeup-capable RTC alarm.
2296 thash_entries= [KNL,NET]
2297 Set number of hash buckets for TCP connection
2299 thermal.act= [HW,ACPI]
2300 -1: disable all active trip points in all thermal zones
2301 <degrees C>: override all lowest active trip points
2303 thermal.crt= [HW,ACPI]
2304 -1: disable all critical trip points in all thermal zones
2305 <degrees C>: override all critical trip points
2307 thermal.nocrt= [HW,ACPI]
2308 Set to disable actions on ACPI thermal zone
2309 critical and hot trip points.
2311 thermal.off= [HW,ACPI]
2312 1: disable ACPI thermal control
2314 thermal.psv= [HW,ACPI]
2315 -1: disable all passive trip points
2316 <degrees C>: override all passive trip points to this
2319 thermal.tzp= [HW,ACPI]
2320 Specify global default ACPI thermal zone polling rate
2321 <deci-seconds>: poll all this frequency
2322 0: no polling (default)
2325 See comment before function dc390_setup() in
2326 drivers/scsi/tmscsim.c.
2330 Specify if the kernel should make use of the cpu
2331 topology informations if the hardware supports these.
2332 The scheduler will make use of these informations and
2333 e.g. base its process migration decisions on it.
2338 trix= [HW,OSS] MediaTrix AudioTrix Pro
2340 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2342 tsc= Disable clocksource-must-verify flag for TSC.
2344 [x86] reliable: mark tsc clocksource as reliable, this
2345 disables clocksource verification at runtime.
2346 Used to enable high-resolution timer mode on older
2347 hardware, and in virtualized environment.
2349 turbografx.map[2|3]= [HW,JOY]
2350 TurboGraFX parallel port interface
2352 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2353 See also Documentation/input/joystick-parport.txt
2355 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2356 See header of drivers/scsi/u14-34f.c.
2365 [USB] Ignore overcurrent events (default N).
2366 Some badly-designed motherboards generate lots of
2367 bogus events, for ports that aren't wired to
2368 anything. Set this parameter to avoid log spamming.
2369 Note that genuine overcurrent events won't be
2374 Set unknown_nmi_panic=1 early on boot.
2376 usbcore.autosuspend=
2377 [USB] The autosuspend time delay (in seconds) used
2378 for newly-detected USB devices (default 2). This
2379 is the time required before an idle device will be
2380 autosuspended. Devices for which the delay is set
2381 to a negative value won't be autosuspended at all.
2383 usbcore.usbfs_snoop=
2384 [USB] Set to log all usbfs traffic (default 0 = off).
2386 usbcore.blinkenlights=
2387 [USB] Set to cycle leds on hubs (default 0 = off).
2389 usbcore.old_scheme_first=
2390 [USB] Start with the old device initialization
2391 scheme (default 0 = off).
2393 usbcore.use_both_schemes=
2394 [USB] Try the other device initialization scheme
2395 if the first one fails (default 1 = enabled).
2397 usbcore.initial_descriptor_timeout=
2398 [USB] Specifies timeout for the initial 64-byte
2399 USB_REQ_GET_DESCRIPTOR request in milliseconds
2400 (default 5000 = 5.0 seconds).
2403 [USBHID] The interval which mice are to be polled at.
2405 usb-storage.delay_use=
2406 [UMS] The delay in seconds before a new device is
2407 scanned for Logical Units (default 5).
2410 [UMS] A list of quirks entries to supplement or
2411 override the built-in unusual_devs list. List
2412 entries are separated by commas. Each entry has
2413 the form VID:PID:Flags where VID and PID are Vendor
2414 and Product ID values (4-digit hex numbers) and
2415 Flags is a set of characters, each corresponding
2416 to a common usb-storage quirk flag as follows:
2417 a = SANE_SENSE (collect more than 18 bytes
2419 c = FIX_CAPACITY (decrease the reported
2420 device capacity by one sector);
2421 h = CAPACITY_HEURISTICS (decrease the
2422 reported device capacity by one
2423 sector if the number is odd);
2424 i = IGNORE_DEVICE (don't bind to this
2426 l = NOT_LOCKABLE (don't try to lock and
2427 unlock ejectable media);
2428 m = MAX_SECTORS_64 (don't transfer more
2429 than 64 sectors = 32 KB at a time);
2430 o = CAPACITY_OK (accept the capacity
2431 reported by the device);
2432 r = IGNORE_RESIDUE (the device reports
2433 bogus residue values);
2434 s = SINGLE_LUN (the device has only one
2436 w = NO_WP_DETECT (don't test whether the
2437 medium is write-protected).
2438 Example: quirks=0419:aaf5:rl,0421:0433:rc
2440 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2441 kernel's map of available physical RAM.
2443 vdso= [X86-32,SH,x86-64]
2444 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2445 vdso=1: enable VDSO (default)
2446 vdso=0: disable VDSO mapping
2448 vdso32= [X86-32,X86-64]
2449 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2450 vdso32=1: enable 32-bit VDSO (default)
2451 vdso32=0: disable 32-bit VDSO mapping
2454 vector=percpu: enable percpu vector domain
2456 video= [FB] Frame buffer configuration
2457 See Documentation/fb/modedb.txt.
2459 vga= [BOOT,X86-32] Select a particular video mode
2460 See Documentation/x86/boot.txt and
2461 Documentation/svga.txt.
2462 Use vga=ask for menu.
2463 This is actually a boot loader parameter; the value is
2464 passed to the kernel using a special protocol.
2466 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2467 size of <nn>. This can be used to increase the
2468 minimum size (128MB on x86). It can also be used to
2469 decrease the size and leave more room for directly
2472 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2475 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2478 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2481 waveartist= [HW,OSS]
2482 Format: <io>,<irq>,<dma>,<dma2>
2485 See header of drivers/scsi/wd33c93.c.
2488 See header of drivers/scsi/wd7000.c.
2491 See Documentation/watchdog/wdt.txt.
2493 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2494 xd_geo= See header of drivers/block/xd.c.
2496 xirc2ps_cs= [NET,PCMCIA]
2498 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2500 norandmaps Don't use address space randomization. Equivalent to
2501 echo 0 > /proc/sys/kernel/randomize_va_space
2503 ______________________________________________________________________
2507 Add documentation for ALSA options.
2508 Add more DRM drivers.
projects / linux-2.6 / blob