4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86/x86_64/boot-options.txt .
104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
106 In addition, the following text indicates that the option:
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
112 Parameters denoted with BOOT are actually interpreted by the boot
113 loader, and have no meaning to the kernel directly.
114 Do not modify the syntax of boot loader parameters without extreme
115 need or coordination with <Documentation/x86/i386/boot.txt>.
117 There are also arch-specific kernel-parameters not documented here.
118 See for example <Documentation/x86/x86_64/boot-options.txt>.
120 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121 a trailing = on the name of any parameter states that that parameter will
122 be entered as an environment variable, whereas its absence indicates that
123 it will appear as a kernel argument readable via /proc/cmdline by programs
124 running once the system is up.
126 The number of kernel parameters is not limited, but the length of the
127 complete command line (parameters including spaces etc.) is limited to
128 a fixed number of characters. This limit depends on the architecture
129 and is between 256 and 4096 characters. It is defined in the file
130 ./include/asm/setup.h as COMMAND_LINE_SIZE.
133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
135 Format: { force | off | ht | strict | noirq }
136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
140 strict -- Be less tolerant of platforms that are not
141 strictly ACPI specification compliant.
143 See also Documentation/power/pm.txt, pci=noacpi
145 acpi_apic_instance= [ACPI, IOAPIC]
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
151 acpi_sleep= [HW,ACPI] Sleep options
152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
164 Format: { level | edge | high | low }
166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
176 Format: <irq>,<irq>...
178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
179 Format: <irq>,<irq>...
181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
191 acpi_serialize [HW,ACPI] force serialization of AML methods
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
201 acpi_backlight= [HW,ACPI]
202 acpi_backlight=vendor
204 If set to vendor, prefer vendor specific driver
205 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
206 of the ACPI video.ko driver.
208 acpi_display_output= [HW,ACPI]
209 acpi_display_output=vendor
210 acpi_display_output=video
213 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
214 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
216 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
217 debug output. Bits in debug_layer correspond to a
218 _COMPONENT in an ACPI source file, e.g.,
219 #define _COMPONENT ACPI_PCI_COMPONENT
220 Bits in debug_level correspond to a level in
221 ACPI_DEBUG_PRINT statements, e.g.,
222 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
223 The debug_level mask defaults to "info". See
224 Documentation/acpi/debug.txt for more information about
225 debug layers and levels.
227 Enable processor driver info messages:
228 acpi.debug_layer=0x20000000
229 Enable PCI/PCI interrupt routing info messages:
230 acpi.debug_layer=0x400000
231 Enable AML "Debug" output, i.e., stores to the Debug
232 object while interpreting AML:
233 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
234 Enable all messages related to ACPI hardware:
235 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
237 Some values produce so much output that the system is
238 unusable. The "log_buf_len" parameter may be useful
239 if you need to capture more output.
241 acpi.power_nocheck= [HW,ACPI]
242 Format: 1/0 enable/disable the check of power state.
243 On some bogus BIOS the _PSC object/_STA object of
244 power resource can't return the correct device power
245 state. In such case it is unneccessary to check its
246 power state again in power transition.
247 1 : disable the power state check
249 acpi_pm_good [X86-32,X86-64]
250 Override the pmtimer bug detection: force the kernel
251 to assume that this machine's pmtimer latches its value
252 and always returns good values.
255 { off | try_unsupported }
256 off: disable AGP support
257 try_unsupported: try to drive unsupported chipsets
258 (may crash computer or cause data corruption)
260 enable_timer_pin_1 [i386,x86-64]
261 Enable PIN 1 of APIC timer
262 Can be useful to work around chipset bugs
263 (in particular on some ATI chipsets).
264 The kernel tries to set a reasonable default.
266 disable_timer_pin_1 [i386,x86-64]
267 Disable PIN 1 of APIC timer
268 Can be useful to work around chipset bugs.
271 Format: <io>,<irq>,<dma>,<dma2>,<type>
274 See header of drivers/scsi/advansys.c.
276 advwdt= [HW,WDT] Advantech WDT
277 Format: <iostart>,<iostop>
279 aedsp16= [HW,OSS] Audio Excel DSP 16
280 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
281 See also header of sound/oss/aedsp16.c.
284 See Documentation/scsi/aha152x.txt.
287 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
290 See Documentation/scsi/aic7xxx.txt.
293 See Documentation/scsi/aic79xx.txt.
295 amd_iommu= [HW,X86-84]
296 Pass parameters to the AMD IOMMU driver in the system.
298 isolate - enable device isolation (each device, as far
299 as possible, will get its own protection
301 share - put every device behind one IOMMU into the
302 same protection domain
303 fullflush - enable flushing of IO/TLB entries when
304 they are unmapped. Otherwise they are
305 flushed before they will be reused, which
308 amd_iommu_size= [HW,X86-64]
309 Define the size of the aperture for the AMD IOMMU
310 driver. Possible values are:
311 '32M', '64M' (default), '128M', '256M', '512M', '1G'
313 amijoy.map= [HW,JOY] Amiga joystick support
314 Map of devices attached to JOY0DAT and JOY1DAT
316 See also Documentation/kernel/input/joystick.txt
318 analog.map= [HW,JOY] Analog joystick and gamepad support
319 Specifies type or capabilities of an analog joystick
320 connected to one of 16 gameports
321 Format: <type1>,<type2>,..<type16>
324 Power management functions (SPARCstation-4/5 + deriv.)
326 Disable APC CPU standby support. SPARCstation-Fox does
327 not play well with APC CPU idle - disable it if you have
328 APC and your system crashes randomly.
330 apic= [APIC,i386] Advanced Programmable Interrupt Controller
331 Change the output verbosity whilst booting
332 Format: { quiet (default) | verbose | debug }
333 Change the amount of debugging information output
334 when initialising the APIC and IO-APIC components.
336 apm= [APM] Advanced Power Management
337 See header of arch/x86/kernel/apm_32.c.
339 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
340 Format: <io>,<irq>,<nodeID>
344 atarimouse= [HW,MOUSE] Atari Mouse
346 atascsi= [HW,SCSI] Atari SCSI
348 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
349 EzKey and similar keyboards
351 atkbd.reset= [HW] Reset keyboard during initialization
353 atkbd.set= [HW] Select keyboard code set
354 Format: <int> (2 = AT (default), 3 = PS/2)
356 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
359 atkbd.softraw= [HW] Choose between synthetic and real raw mode
360 Format: <bool> (0 = real, 1 = synthetic (default))
362 atkbd.softrepeat= [HW]
363 Use software keyboard repeat
367 baycom_epp= [HW,AX25]
370 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
372 See header of drivers/net/hamradio/baycom_par.c.
374 baycom_ser_fdx= [HW,AX25]
375 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
376 Format: <io>,<irq>,<mode>[,<baud>]
377 See header of drivers/net/hamradio/baycom_ser_fdx.c.
379 baycom_ser_hdx= [HW,AX25]
380 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
381 Format: <io>,<irq>,<mode>
382 See header of drivers/net/hamradio/baycom_ser_hdx.c.
384 boot_delay= Milliseconds to delay each printk during boot.
385 Values larger than 10 seconds (10000) are changed to
389 bootmem_debug [KNL] Enable bootmem allocator debug messages.
391 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
392 bttv.radio= Most important insmod options are available as
394 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
395 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
398 See drivers/scsi/BusLogic.c, comment before function
399 BusLogic_ParseDriverOptions().
401 c101= [NET] Moxa C101 synchronous serial card
403 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
404 Sometimes CPU hardware bugs make them report the cache
405 size incorrectly. The kernel will attempt work arounds
406 to fix known problems, but for some CPUs it is not
407 possible to determine what the correct size should be.
408 This option provides an override for these situations.
410 security= [SECURITY] Choose a security module to enable at boot.
411 If this boot parameter is not specified, only the first
412 security module asking for security registration will be
413 loaded. An invalid security module name will be treated
414 as if no module has been chosen.
417 [SECURITY] Disable capabilities. This would normally
418 be used only if an alternative security model is to be
419 configured. Potentially dangerous and should only be
420 used if you are entirely sure of the consequences.
422 ccw_timeout_log [S390]
423 See Documentation/s390/CommonIO for details.
425 cgroup_disable= [KNL] Disable a particular controller
426 Format: {name of the controller(s) to disable}
427 {Currently supported controllers - "memory"}
429 checkreqprot [SELINUX] Set initial checkreqprot flag value.
430 Format: { "0" | "1" }
431 See security/selinux/Kconfig help text.
432 0 -- check protection applied by kernel (includes
433 any implied execute protection).
434 1 -- check protection requested by application.
435 Default value is set via a kernel config option.
436 Value can be changed at runtime via
437 /selinux/checkreqprot.
440 See Documentation/s390/CommonIO for details.
442 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
444 Forces specified clocksource (if available) to be used
445 when calculating gettimeofday(). If specified
446 clocksource is not available, it defaults to PIT.
447 Format: { pit | tsc | cyclone | pmtmr }
449 clocksource= [GENERIC_TIME] Override the default clocksource
451 Override the default clocksource and use the clocksource
452 with the name specified.
453 Some clocksource names to choose from, depending on
455 [all] jiffies (this is the base, fallback clocksource)
457 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
458 pxa_timer,timer3,32k_counter,timer0_1
460 [X86-32] pit,hpet,tsc,vmi-timer;
461 scx200_hrt on Geode; cyclone on IBM x440
469 clearcpuid=BITNUM [X86]
470 Disable CPUID feature X for the kernel. See
471 include/asm-x86/cpufeature.h for the valid bit numbers.
472 Note the Linux specific bits are not necessarily
473 stable over kernel options, but the vendor specific
475 Also note that user programs calling CPUID directly
476 or using the feature without checking anything
477 will still see it. This just prevents it from
478 being used by the kernel or shown in /proc/cpuinfo.
479 Also note the kernel might malfunction if you disable
482 code_bytes [IA32/X86_64] How many bytes of object code to print
487 hpet= [X86-32,HPET] option to control HPET usage
488 Format: { enable (default) | disable | force }
489 disable: disable HPET and use PIT instead
490 force: allow force enabled of undocumented chips (ICH4,
493 com20020= [HW,NET] ARCnet - COM20020 chipset
495 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
497 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
501 ARCnet - COM90xx chipset (memory-mapped buffers)
502 Format: <io>[,<irq>[,<memstart>]]
504 condev= [HW,S390] console device
507 console= [KNL] Output console device and options.
509 tty<n> Use the virtual console device <n>.
513 Use the specified serial port. The options are of
514 the form "bbbbpnf", where "bbbb" is the baud rate,
515 "p" is parity ("n", "o", or "e"), "n" is number of
516 bits, and "f" is flow control ("r" for RTS or
517 omit it). Default is "9600n8".
519 See Documentation/serial-console.txt for more
521 Documentation/networking/netconsole.txt for an
524 uart[8250],io,<addr>[,options]
525 uart[8250],mmio,<addr>[,options]
526 Start an early, polled-mode console on the 8250/16550
527 UART at the specified I/O port or MMIO address,
528 switching to the matching ttyS device later. The
529 options are the same as for ttyS, above.
531 If the device connected to the port is not a TTY but a braille
532 device, prepend "brl," before the device type, for instance
534 For now, only VisioBraille is supported.
536 earlycon= [KNL] Output early console device and options.
537 uart[8250],io,<addr>[,options]
538 uart[8250],mmio,<addr>[,options]
539 Start an early, polled-mode console on the 8250/16550
540 UART at the specified I/O port or MMIO address.
541 The options are the same as for ttyS, above.
544 [HW] Never suspend the console
545 Disable suspending of consoles during suspend and
546 hibernate operations. Once disabled, debugging
547 messages can reach various consoles while the rest
548 of the system is being put to sleep (ie, while
549 debugging driver suspend/resume hooks). This may
550 not work reliably with all consoles, but is known
551 to work with serial and VGA consoles.
553 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
555 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
557 crashkernel=nn[KMG]@ss[KMG]
558 [KNL] Reserve a chunk of physical memory to
559 hold a kernel to switch to with kexec on panic.
561 crashkernel=range1:size1[,range2:size2,...][@offset]
562 [KNL] Same as above, but depends on the memory
563 in the running system. The syntax of range is
564 start-[end] where start and end are both
565 a memory unit (amount[KMG]). See also
566 Documentation/kdump/kdump.txt for a example.
569 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
574 cs89x0_media= [HW,NET]
575 Format: { rj45 | aui | bnc }
578 See header of drivers/s390/block/dasd_devmap.c.
580 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
581 (one device per port)
582 Format: <port#>,<type>
583 See also Documentation/input/joystick-parport.txt
585 debug [KNL] Enable kernel debugging (events log level).
588 [KNL] verbose self-tests
590 Print debugging info while doing the locking API
592 We default to 0 (no extra messages), setting it to
593 1 will print _a lot_ more information - normally
594 only useful to kernel developers.
596 debug_objects [KNL] Enable object debugging
598 debugpat [X86] Enable PAT debugging
600 decnet.addr= [HW,NET]
601 Format: <area>[,<node>]
602 See also Documentation/networking/decnet.txt.
605 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
606 Change the default blue palette of the console.
607 This is a 16-member array composed of values
611 Format: <green0>,<green1>,<green2>,...,<green15>
612 Change the default green palette of the console.
613 This is a 16-member array composed of values
617 Format: <red0>,<red1>,<red2>,...,<red15>
618 Change the default red palette of the console.
619 This is a 16-member array composed of values
625 Set system-wide default UTF-8 mode for all tty's.
626 Default is 1, i.e. UTF-8 mode is enabled for all
627 newly opened terminals.
630 Set number of hash buckets for dentry cache.
633 IO parameters + enable/disable command.
635 digiepca= [HW,SERIAL]
636 See drivers/char/README.epca and
637 Documentation/serial/digiepca.txt.
639 disable_mtrr_cleanup [X86]
640 enable_mtrr_cleanup [X86]
641 The kernel tries to adjust MTRR layout from continuous
642 to discrete, to make X server driver able to add WB
643 entry later. This parameter enables/disables that.
645 mtrr_chunk_size=nn[KMG] [X86]
646 used for mtrr cleanup. It is largest continous chunk
647 that could hold holes aka. UC entries.
649 mtrr_gran_size=nn[KMG] [X86]
650 Used for mtrr cleanup. It is granularity of mtrr block.
652 Large value could prevent small alignment from
655 mtrr_spare_reg_nr=n [X86]
657 Range: 0,7 : spare reg number
659 Used for mtrr cleanup. It is spare mtrr entries number.
660 Set to 2 or more if your graphical card needs more.
662 disable_mtrr_trim [X86, Intel and AMD only]
663 By default the kernel will trim any uncacheable
664 memory out of your available memory pool based on
665 MTRR settings. This parameter disables that behavior,
666 possibly causing your machine to run very slowly.
668 dmasound= [HW,OSS] Sound subsystem buffers
674 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
676 earlyprintk=serial[,ttySn[,baudrate]]
679 Append ",keep" to not disable it when the real console
682 Only vga or serial or usb debug port at a time.
684 Currently only ttyS0 and ttyS1 are supported.
686 Interaction with the standard serial driver is not
689 The VGA output is eventually overwritten by the real
695 Format: {"off" | "on" | "skip[mbr]"}
697 eisa_irq_edge= [PARISC,HW]
698 See header of drivers/parisc/eisa.c.
701 See comment before function elanfreq_setup() in
702 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
705 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
706 See Documentation/block/as-iosched.txt and
707 Documentation/block/deadline-iosched.txt for details.
709 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
710 Specifies physical address of start of kernel core
711 image elf header. Generally kexec loader will
712 pass this option to capture kernel.
713 See Documentation/kdump/kdump.txt for details.
715 enforcing [SELINUX] Set initial enforcing status.
717 See security/selinux/Kconfig help text.
718 0 -- permissive (log only, no denials).
719 1 -- enforcing (deny and log).
721 Value can be changed at runtime via /selinux/enforce.
724 Format: <spdif>,[<nomix>,[<amplifier>]]
725 See also header of sound/oss/es1371.c.
727 ether= [HW,NET] Ethernet cards parameters
728 This option is obsoleted by the "netdev=" option, which
729 has equivalent usage. See its documentation for details.
731 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
736 fail_make_request=[KNL]
737 General fault injection mechanism.
738 Format: <interval>,<probability>,<space>,<times>
739 See also /Documentation/fault-injection/.
742 See header of drivers/scsi/fd_mcs.c.
745 See header of drivers/scsi/fdomain.c.
748 See Documentation/blockdev/floppy.txt.
750 force_pal_cache_flush
751 [IA-64] Avoid check_sal_cache_flush which may hang on
752 buggy SAL_CACHE_FLUSH implementations. Using this
753 parameter will force ia64_sal_cache_flush to call
754 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
757 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
758 support via parallel port (up to 5 devices per port)
759 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
760 See also Documentation/input/joystick-parport.txt
764 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
769 See header of drivers/scsi/gdth.c.
771 gpt [EFI] Forces disk with valid GPT signature but
772 invalid Protective MBR to be treated as GPT.
776 hashdist= [KNL,NUMA] Large hashes allocated during boot
777 are distributed across NUMA nodes. Defaults on
778 for IA-64, off otherwise.
779 Format: 0 | 1 (for off | on)
781 hcl= [IA-64] SGI's Hardware Graph compatibility layer
783 hd= [EIDE] (E)IDE hard drive subsystem geometry
784 Format: <cyl>,<head>,<sect>
786 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
787 size of <nn>. This works even on boxes that have no
788 highmem otherwise. This also works to reduce highmem
789 size on bigger boxes.
791 highres= [KNL] Enable/disable high resolution timer mode.
792 Valid parameters: "on", "off"
796 See Documentation/isdn/README.HiSax.
798 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
799 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
800 On x86-64 and powerpc, this option can be specified
801 multiple times interleaved with hugepages= to reserve
802 huge pages of different sizes. Valid pages sizes on
803 x86-64 are 2M (when the CPU supports "pse") and 1G
804 (when the CPU supports the "pdpe1gb" cpuinfo flag)
805 Note that 1GB pages can only be allocated at boot time
806 using hugepages= and not freed afterwards.
808 [same as hugepagesz=] The size of the default
809 HugeTLB page size. This is the size represented by
810 the legacy /proc/ hugepages APIs, used for SHM, and
811 default size when mounting hugetlbfs filesystems.
812 Defaults to the default architecture's huge page size
817 i8042.debug [HW] Toggle i8042 debug mode
818 i8042.direct [HW] Put keyboard port into non-translated mode
819 i8042.dumbkbd [HW] Pretend that controller can only read data from
820 keyboard and cannot control its state
821 (Don't attempt to blink the leds)
822 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
823 i8042.nokbd [HW] Don't check/create keyboard port
824 i8042.noloop [HW] Disable the AUX Loopback command while probing
826 i8042.nomux [HW] Don't check presence of an active multiplexing
828 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
831 [HW] Frequency with which keyboard LEDs should blink
832 when kernel panics (default is 0.5 sec)
833 i8042.reset [HW] Reset the controller during init and cleanup
834 i8042.unlock [HW] Unlock (ignore) the keylock
838 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
839 indicates that the driver is running on unsupported
841 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
842 does not match list of supported models.
844 [HW] Report power status in /proc/i8k
845 (disabled by default)
846 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
849 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
850 See Documentation/mca.txt.
853 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
855 ide= [HW] (E)IDE subsystem
856 Format: ide=nodma or ide=doubler
857 See Documentation/ide/ide.txt.
859 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
860 See Documentation/ide/ide.txt.
863 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
864 Poll forces a polling idle loop that can slightly improves the performance
865 of waking up a idle CPU, but will use a lot of power and make the system
866 run hot. Not recommended.
867 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
868 to not use it because it doesn't save as much power as a normal idle
869 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
871 idle=halt. Halt is forced to be used for CPU idle.
872 In such case C2/C3 won't be used again.
873 idle=nomwait. Disable mwait for CPU C-states
875 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
876 Claim all unknown PCI IDE storage controllers.
878 ignore_loglevel [KNL]
879 Ignore loglevel setting - this will print /all/
880 kernel messages to the console. Useful for debugging.
883 Set number of hash buckets for inode cache.
886 See header of drivers/scsi/in2000.c.
890 Run specified binary instead of /sbin/init as init
893 initcall_debug [KNL] Trace initcalls as they are executed. Useful
894 for working out where the kernel is dying during
897 initrd= [BOOT] Specify the location of the initial ramdisk
899 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
917 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
919 Disable intel iommu driver.
920 igfx_off [Default Off]
921 By default, gfx is mapped as normal device. If a gfx
922 device has a dedicated DMAR unit, the DMAR unit is
923 bypassed by not enabling DMAR with this option. In
924 this case, gfx device will use physical address for
927 With this option iommu will not optimize to look
928 for io virtual address below 32 bit forcing dual
929 address cycle on pci bus for cards supporting greater
930 than 32 bit addressing. The default is to look
931 for translation below 32 bit and if not available
932 then look in the higher range.
934 With this option on every unmap_single operation will
935 result in a hardware IOTLB flush operation as opposed
936 to batching them for performance.
938 io_delay= [X86-32,X86-64] I/O delay method
940 Standard port 0x80 based delay
942 Alternate port 0xed based delay (needed on some systems)
944 Simple two microseconds delay
948 io7= [HW] IO7 for Marvel based alpha systems
949 See comment before marvel_specify_io7 in
950 arch/alpha/kernel/core_marvel.c.
953 See Documentation/filesystems/nfsroot.txt.
955 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
956 See comment before ip2_setup() in
957 drivers/char/ip2/ip2base.c.
959 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
960 See header of drivers/scsi/ips.c.
962 ports= [IP_VS_FTP] IPVS ftp helper module
964 Up to 8 (IP_VS_APP_MAX_PORTS) ports
966 Format: <port>,<port>....
969 When an interrupt is not handled search all handlers
970 for it. Intended to get systems with badly broken
974 When an interrupt is not handled search all handlers
975 for it. Also check all handlers each timer
976 interrupt. Intended to get systems with badly broken
980 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
982 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
984 <cpu number>,...,<cpu number>
986 <cpu number>-<cpu number>
987 (must be a positive range in ascending order)
989 <cpu number>,...,<cpu number>-<cpu number>
991 This option can be used to specify one or more CPUs
992 to isolate from the general SMP balancing and scheduling
993 algorithms. You can move a process onto or off an
994 "isolated" CPU via the CPU affinity syscalls or cpuset.
995 <cpu number> begins at 0 and the maximum value is
996 "number of CPUs in system - 1".
998 This option is the preferred way to isolate CPUs. The
999 alternative -- manually setting the CPU mask of all
1000 tasks in the system -- can cause problems and
1001 suboptimal load balancer performance.
1005 js= [HW,JOY] Analog joystick
1006 See Documentation/input/joystick.txt.
1008 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1009 specifies the amount of memory usable by the kernel
1010 for non-movable allocations. The requested amount is
1011 spread evenly throughout all nodes in the system. The
1012 remaining memory in each node is used for Movable
1013 pages. In the event, a node is too small to have both
1014 kernelcore and Movable pages, kernelcore pages will
1015 take priority and other nodes will have a larger number
1016 of kernelcore pages. The Movable zone is used for the
1017 allocation of pages that may be reclaimed or moved
1018 by the page migration subsystem. This means that
1019 HugeTLB pages may not be allocated from this zone.
1020 Note that allocations like PTEs-from-HighMem still
1021 use the HighMem zone if it exists, and the Normal
1022 zone if it does not.
1024 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1025 is similar to kernelcore except it specifies the
1026 amount of memory used for migratable allocations.
1027 If both kernelcore and movablecore is specified,
1028 then kernelcore will be at *least* the specified
1029 value but may be more. If movablecore on its own
1030 is specified, the administrator must be careful
1031 that the amount of memory usable for all allocations
1036 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1039 kgdboc= [HW] kgdb over consoles.
1040 Requires a tty driver that supports console polling.
1041 (only serial suported for now)
1042 Format: <serial_device>[,baud]
1044 kmac= [MIPS] korina ethernet MAC address.
1045 Configure the RouterBoard 532 series on-chip
1046 Ethernet adapter MAC address.
1052 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1055 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1058 libata.dma= [LIBATA] DMA control
1059 libata.dma=0 Disable all PATA and SATA DMA
1060 libata.dma=1 PATA and SATA Disk DMA only
1061 libata.dma=2 ATAPI (CDROM) DMA only
1062 libata.dma=4 Compact Flash DMA only
1063 Combinations also work, so libata.dma=3 enables DMA
1064 for disks and CDROMs, but not CFs.
1066 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1070 libata.force= [LIBATA] Force configurations. The format is comma
1071 separated list of "[ID:]VAL" where ID is
1072 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1073 matching port, link or device. Basically, it matches
1074 the ATA ID string printed on console by libata. If
1075 the whole ID part is omitted, the last PORT and DEVICE
1076 values are used. If ID hasn't been specified yet, the
1077 configuration applies to all ports, links and devices.
1079 If only DEVICE is omitted, the parameter applies to
1080 the port and all links and devices behind it. DEVICE
1081 number of 0 either selects the first device or the
1082 first fan-out link behind PMP device. It does not
1083 select the host link. DEVICE number of 15 selects the
1084 host link and device attached to it.
1086 The VAL specifies the configuration to force. As long
1087 as there's no ambiguity shortcut notation is allowed.
1088 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1089 The following configurations can be forced.
1091 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1092 Any ID with matching PORT is used.
1094 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1096 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1097 udma[/][16,25,33,44,66,100,133] notation is also
1100 * [no]ncq: Turn on or off NCQ.
1102 * nohrst, nosrst, norst: suppress hard, soft
1105 If there are multiple matching configurations changing
1106 the same attribute, the last one is used.
1108 load_ramdisk= [RAM] List of ramdisks to load from floppy
1109 See Documentation/blockdev/ramdisk.txt.
1111 lockd.nlm_grace_period=P [NFS] Assign grace period.
1114 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1117 lockd.nlm_timeout=T [NFS] Assign timeout value.
1120 lockd.nlm_udpport=M [NFS] Assign UDP port.
1123 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1126 loglevel= All Kernel Messages with a loglevel smaller than the
1127 console loglevel will be printed to the console. It can
1128 also be changed with klogd or other programs. The
1129 loglevels are defined as follows:
1131 0 (KERN_EMERG) system is unusable
1132 1 (KERN_ALERT) action must be taken immediately
1133 2 (KERN_CRIT) critical conditions
1134 3 (KERN_ERR) error conditions
1135 4 (KERN_WARNING) warning conditions
1136 5 (KERN_NOTICE) normal but significant condition
1137 6 (KERN_INFO) informational
1138 7 (KERN_DEBUG) debug-level messages
1140 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1141 Format: { n | nk | nM }
1142 n must be a power of two. The default size
1143 is set in the kernel config file.
1145 logo.nologo [FB] Disables display of the built-in Linux logo.
1146 This may be used to provide more screen space for
1147 kernel log messages and is useful when debugging
1148 kernel boot problems.
1150 lp=0 [LP] Specify parallel ports to use, e.g,
1151 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1152 lp=reset first parallel port). 'lp=0' disables the
1153 lp=auto printer driver. 'lp=reset' (which can be
1154 specified in addition to the ports) causes
1155 attached printers to be reset. Using
1156 lp=port1,port2,... specifies the parallel ports
1157 to associate lp devices with, starting with
1158 lp0. A port specification may be 'none' to skip
1159 that lp device, or a parport name such as
1160 'parport0'. Specifying 'lp=auto' instead of a
1161 port specification list means that device IDs
1162 from each port should be examined, to see if
1163 an IEEE 1284-compliant printer is attached; if
1164 so, the driver will manage that printer.
1165 See also header of drivers/char/lp.c.
1168 Sets loops_per_jiffy to given constant, thus avoiding
1169 time-consuming boot-time autodetection (up to 250 ms per
1170 CPU). 0 enables autodetection (default). To determine
1171 the correct value for your kernel, boot with normal
1172 autodetection and see what value is printed. Note that
1173 on SMP systems the preset will be applied to all CPUs,
1174 which is likely to cause problems if your CPUs need
1175 significantly divergent settings. An incorrect value
1176 will cause delays in the kernel to be wrong, leading to
1177 unpredictable I/O errors and other breakage. Although
1178 unlikely, in the extreme case this might damage your
1182 Format: <io>,<irq>,<dma>
1184 mac5380= [HW,SCSI] Format:
1185 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1187 machvec= [IA64] Force the use of a particular machine-vector
1188 (machvec) in a generic kernel.
1189 Example: machvec=hpzx1_swiotlb
1191 max_loop= [LOOP] Maximum number of loopback devices that can
1195 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1196 should make use of. maxcpus=n : n >= 0 limits the
1197 kernel to using 'n' processors. n=0 is a special case,
1198 it is equivalent to "nosmp", which also disables
1201 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1202 or equal to this physical address is ignored.
1204 max_luns= [SCSI] Maximum number of LUNs to probe.
1205 Should be between 1 and 2^32-1.
1208 [SCSI] Maximum number of LUNs received.
1209 Should be between 1 and 16384.
1213 mce [X86-32] Machine Check Exception
1215 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1217 md= [HW] RAID subsystems devices and level
1218 See Documentation/md.txt.
1221 Format: <first>,<last>
1222 Specifies range of consoles to be captured by the MDA.
1224 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1225 Amount of memory to be used when the kernel is not able
1226 to see the whole system memory or for test.
1227 [X86-32] Use together with memmap= to avoid physical
1228 address space collisions. Without memmap= PCI devices
1229 could be placed at addresses belonging to unused RAM.
1231 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1235 [KNL,SH] Allow user to override the default size for
1236 per-device physically contiguous DMA buffers.
1238 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1239 E820 memory map, as specified by the user.
1240 Such memmap=exactmap lines can be constructed based on
1241 BIOS output or other requirements. See the memmap=nn@ss
1244 memmap=nn[KMG]@ss[KMG]
1245 [KNL] Force usage of a specific region of memory
1246 Region of memory to be used, from ss to ss+nn.
1248 memmap=nn[KMG]#ss[KMG]
1249 [KNL,ACPI] Mark specific memory as ACPI data.
1250 Region of memory to be used, from ss to ss+nn.
1252 memmap=nn[KMG]$ss[KMG]
1253 [KNL,ACPI] Mark specific memory as reserved.
1254 Region of memory to be used, from ss to ss+nn.
1255 Example: Exclude memory from 0x18690000-0x1869ffff
1256 memmap=64K$0x18690000
1258 memmap=0x10000$0x18690000
1260 memory_corruption_check=0/1 [X86]
1261 Some BIOSes seem to corrupt the first 64k of
1262 memory when doing things like suspend/resume.
1263 Setting this option will scan the memory
1264 looking for corruption. Enabling this will
1265 both detect corruption and prevent the kernel
1266 from using the memory being corrupted.
1267 However, its intended as a diagnostic tool; if
1268 repeatable BIOS-originated corruption always
1269 affects the same memory, you can use memmap=
1270 to prevent the kernel from using that memory.
1272 memory_corruption_check_size=size [X86]
1273 By default it checks for corruption in the low
1274 64k, making this memory unavailable for normal
1275 use. Use this parameter to scan for
1276 corruption in more or less memory.
1278 memory_corruption_check_period=seconds [X86]
1279 By default it checks for corruption every 60
1280 seconds. Use this parameter to check at some
1281 other rate. 0 disables periodic checking.
1283 memtest= [KNL,X86] Enable memtest
1285 range: 0,4 : pattern number
1286 default : 0 <disable>
1288 meye.*= [HW] Set MotionEye Camera parameters
1289 See Documentation/video4linux/meye.txt.
1291 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1292 Multi-Function General Purpose Timers on AMD Geode
1295 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1296 the BIOS has incorrectly applied a workaround. TinyBIOS
1297 version 0.98 is known to be affected, 0.99 fixes the
1298 problem by letting the user disable the workaround.
1302 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1303 physical address is ignored.
1306 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1307 parameter allows control of the logging verbosity for
1308 the additional memory initialisation checks. A value
1309 of 0 disables mminit logging and a level of 4 will
1310 log everything. Information is printed at KERN_DEBUG
1311 so loglevel=8 may also need to be specified.
1314 [MOUSE] Maximum time between finger touching and
1315 leaving touchpad surface for touch to be considered
1316 a tap and be reported as a left button click (for
1317 touchpads working in absolute mode only).
1319 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1320 reporting absolute coordinates, such as tablets
1321 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1322 reporting absolute coordinates, such as tablets
1327 MTD_Partition= [MTD]
1328 Format: <name>,<region-number>,<size>,<offset>
1330 MTD_Region= [MTD] Format:
1331 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1334 See drivers/mtd/cmdlinepart.c.
1337 ARM/S3C2412 JIVE boot control
1339 See arch/arm/mach-s3c2412/mach-jive.c
1341 mtouchusb.raw_coordinates=
1342 [HW] Make the MicroTouch USB driver use raw coordinates
1343 ('y', default) or cooked coordinates ('n')
1345 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1348 See header of drivers/scsi/NCR_D700.c.
1352 ncr53c400= [HW,SCSI]
1354 ncr53c400a= [HW,SCSI]
1356 ncr53c406a= [HW,SCSI]
1358 ncr53c8xx= [HW,SCSI]
1360 netdev= [NET] Network devices parameters
1361 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1362 Note that mem_start is often overloaded to mean
1363 something different and driver-specific.
1364 This usage is only documented in each driver source
1368 [NETFILTER] Enable connection tracking flow accounting
1369 0 to disable accounting
1370 1 to enable accounting
1371 Default value depends on CONFIG_NF_CT_ACCT that is
1372 going to be removed in 2.6.29.
1375 See Documentation/filesystems/nfsroot.txt.
1377 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1378 See Documentation/filesystems/nfsroot.txt.
1380 nfs.callback_tcpport=
1381 [NFS] set the TCP port on which the NFSv4 callback
1382 channel should listen.
1384 nfs.idmap_cache_timeout=
1385 [NFS] set the maximum lifetime for idmapper cache
1389 [NFS] enable 64-bit inode numbers.
1390 If zero, the NFS client will fake up a 32-bit inode
1391 number for the readdir() and stat() syscalls instead
1392 of returning the full 64-bit number.
1393 The default is to return 64-bit inode numbers.
1395 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1396 when a NMI is triggered.
1397 Format: [state][,regs][,debounce][,die]
1399 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1400 Format: [panic,][num]
1402 0 - turn nmi_watchdog off
1403 1 - use the IO-APIC timer for the NMI watchdog
1404 2 - use the local APIC for the NMI watchdog using
1405 a performance counter. Note: This will use one performance
1406 counter and the local APIC's performance vector.
1407 When panic is specified panic when an NMI watchdog timeout occurs.
1408 This is useful when you use a panic=... timeout and need the box
1410 Instead of 1 and 2 it is possible to use the following
1411 symbolic names: lapic and ioapic
1412 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1414 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1415 emulation library even if a 387 maths coprocessor
1418 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1419 caches in the slab allocator. Saves per-node memory,
1420 but will impact performance.
1424 noapic [SMP,APIC] Tells the kernel to not make use of any
1425 IOAPICs that may be present in the system.
1427 nobats [PPC] Do not use BATs for mapping kernel lowmem
1428 on "Classic" PPC cores.
1432 nodelayacct [KNL] Disable per-task delay accounting
1434 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1436 nodsp [SH] Disable hardware DSP at boot time.
1438 noefi [X86-32,X86-64] Disable EFI runtime services support.
1442 noexec [X86-32,X86-64]
1443 On X86-32 available only on PAE configured kernels.
1444 noexec=on: enable non-executable mappings (default)
1445 noexec=off: disable non-executable mappings
1448 This affects only 32-bit executables.
1449 noexec32=on: enable non-executable mappings (default)
1450 read doesn't imply executable mappings
1451 noexec32=off: disable non-executable mappings
1452 read implies executable mappings
1454 nofpu [SH] Disable hardware FPU at boot time.
1456 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1457 register save and restore. The kernel will only save
1458 legacy floating-point registers on task switch.
1460 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1464 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1465 instruction doesn't work correctly and not to
1468 no_file_caps Tells the kernel not to honor file capabilities. The
1469 only way then for a file to be executed with privilege
1470 is to be setuid root or executed by root.
1472 nohalt [IA-64] Tells the kernel not to use the power saving
1473 function PAL_HALT_LIGHT when idle. This increases
1474 power-consumption. On the positive side, it reduces
1475 interrupt wake-up latency, which may improve performance
1476 in certain environments such as networked servers or
1479 nohz= [KNL] Boottime enable/disable dynamic ticks
1480 Valid arguments: on, off
1483 noirqdebug [X86-32] Disables the code which attempts to detect and
1484 disable unhandled interrupt sources.
1486 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1487 broken timer IRQ sources.
1489 noisapnp [ISAPNP] Disables ISA PnP code.
1491 noinitrd [RAM] Tells the kernel not to load any configured
1496 nojitter [IA64] Disables jitter checking for ITC timers.
1498 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1500 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1502 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1504 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1505 default x2apic cluster mode on platforms
1508 noltlbs [PPC] Do not use large page/tlb entries for kernel
1509 lowmem mapping on PPC40x.
1511 nomca [IA-64] Disable machine check abort handling
1513 nomce [X86-32] Machine Check Exception
1515 nomfgpt [X86-32] Disable Multi-Function General Purpose
1516 Timer usage (for AMD Geode machines).
1518 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1520 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1521 with UP alternatives
1523 noresidual [PPC] Don't use residual data on PReP machines.
1525 noresume [SWSUSP] Disables resume and restores original swap
1528 no-scroll [VGA] Disables scrollback.
1529 This is required for the Braillex ib80-piezo Braille
1530 reader made by F.H. Papenmeier (Germany).
1534 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1536 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1537 and disable the IO APIC. legacy for "maxcpus=0".
1539 nosoftlockup [KNL] Disable the soft-lockup detector.
1541 nosync [HW,M68K] Disables sync negotiation for all devices.
1543 notsc [BUGS=X86-32] Disable Time Stamp Counter
1545 nousb [USB] Disable the USB subsystem
1549 nptcg= [IA64] Override max number of concurrent global TLB
1550 purges which is reported from either PAL_VM_SUMMARY or
1553 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1554 one of ['zone', 'node', 'default'] can be specified
1555 This can be set from sysctl after boot.
1556 See Documentation/sysctl/vm.txt for details.
1558 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1560 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1561 Rather than timing out after 20 ms if an EC
1562 command is not properly ACKed, override the length
1563 of the timeout. We have interrupts disabled while
1564 waiting for the ACK, so if this is set too high
1565 interrupts *may* be lost!
1570 oprofile.timer= [HW]
1571 Use timer interrupt instead of performance counters
1573 osst= [HW,SCSI] SCSI Tape Driver
1574 Format: <buffer_size>,<write_threshold>
1575 See also Documentation/scsi/st.txt.
1577 panic= [KNL] Kernel behaviour on panic
1580 parkbd.port= [HW] Parallel port number the keyboard adapter is
1581 connected to, default is 0.
1583 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1584 0 for XT, 1 for AT (default is AT).
1587 parport= [HW,PPT] Specify parallel ports. 0 disables.
1588 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1589 Use 'auto' to force the driver to use any
1590 IRQ/DMA settings detected (the default is to
1591 ignore detected IRQ/DMA settings because of
1592 possible conflicts). You can specify the base
1593 address, IRQ, and DMA settings; IRQ and DMA
1594 should be numbers, or 'auto' (for using detected
1595 settings on that particular port), or 'nofifo'
1596 (to avoid using a FIFO even if it is detected).
1597 Parallel ports are assigned in the order they
1598 are specified on the command line, starting
1601 parport_init_mode= [HW,PPT]
1602 Configure VIA parallel port to operate in
1603 a specific mode. This is necessary on Pegasos
1604 computer where firmware has no options for setting
1605 up parallel port mode and sets it to spp.
1606 Currently this function knows 686a and 8231 chips.
1607 Format: [spp|ps2|epp|ecp|ecpepp]
1609 pas2= [HW,OSS] Format:
1610 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1613 See header of drivers/scsi/pas16.c.
1616 Halt all CPUs after the first oops has been printed for
1617 the specified number of seconds. This is to be used if
1618 your oopses keep scrolling off the screen.
1623 See header of drivers/block/paride/pcd.c.
1624 See also Documentation/blockdev/paride.txt.
1626 pci=option[,option...] [PCI] various PCI subsystem options:
1627 off [X86] don't probe for the PCI bus
1628 bios [X86-32] force use of PCI BIOS, don't access
1629 the hardware directly. Use this if your machine
1630 has a non-standard PCI host bridge.
1631 nobios [X86-32] disallow use of PCI BIOS, only direct
1632 hardware access methods are allowed. Use this
1633 if you experience crashes upon bootup and you
1634 suspect they are caused by the BIOS.
1635 conf1 [X86] Force use of PCI Configuration
1637 conf2 [X86] Force use of PCI Configuration
1639 noaer [PCIE] If the PCIEAER kernel config parameter is
1640 enabled, this kernel boot option can be used to
1641 disable the use of PCIE advanced error reporting.
1642 nodomains [PCI] Disable support for multiple PCI
1643 root domains (aka PCI segments, in ACPI-speak).
1644 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1646 nomsi [MSI] If the PCI_MSI kernel config parameter is
1647 enabled, this kernel boot option can be used to
1648 disable the use of MSI interrupts system-wide.
1649 noioapicquirk [APIC] Disable all boot interrupt quirks.
1650 Safety option to keep boot IRQs enabled. This
1651 should never be necessary.
1652 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1653 primary IO-APIC for bridges that cannot disable
1654 boot IRQs. This fixes a source of spurious IRQs
1655 when the system masks IRQs.
1656 noioapicreroute [APIC] Disable workaround that uses the
1657 boot IRQ equivalent of an IRQ that connects to
1658 a chipset where boot IRQs cannot be disabled.
1659 The opposite of ioapicreroute.
1660 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1661 routing table. These calls are known to be buggy
1662 on several machines and they hang the machine
1663 when used, but on other computers it's the only
1664 way to get the interrupt routing table. Try
1665 this option if the kernel is unable to allocate
1666 IRQs or discover secondary PCI buses on your
1668 rom [X86] Assign address space to expansion ROMs.
1669 Use with caution as certain devices share
1670 address decoders between ROMs and other
1672 norom [X86] Do not assign address space to
1673 expansion ROMs that do not already have
1674 BIOS assigned address ranges.
1675 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1676 assigned automatically to PCI devices. You can
1677 make the kernel exclude IRQs of your ISA cards
1679 pirqaddr=0xAAAAA [X86] Specify the physical address
1680 of the PIRQ table (normally generated
1681 by the BIOS) if it is outside the
1682 F0000h-100000h range.
1683 lastbus=N [X86] Scan all buses thru bus #N. Can be
1684 useful if the kernel is unable to find your
1685 secondary buses and you want to tell it
1686 explicitly which ones they are.
1687 assign-busses [X86] Always assign all PCI bus
1688 numbers ourselves, overriding
1689 whatever the firmware may have done.
1690 usepirqmask [X86] Honor the possible IRQ mask stored
1691 in the BIOS $PIR table. This is needed on
1692 some systems with broken BIOSes, notably
1693 some HP Pavilion N5400 and Omnibook XE3
1694 notebooks. This will have no effect if ACPI
1695 IRQ routing is enabled.
1696 noacpi [X86] Do not use ACPI for IRQ routing
1697 or for PCI scanning.
1698 use_crs [X86] Use _CRS for PCI resource
1700 routeirq Do IRQ routing for all PCI devices.
1701 This is normally done in pci_enable_device(),
1702 so this option is a temporary workaround
1703 for broken drivers that don't call it.
1704 skip_isa_align [X86] do not align io start addr, so can
1705 handle more pci cards
1706 firmware [ARM] Do not re-enumerate the bus but instead
1707 just use the configuration from the
1708 bootloader. This is currently used on
1709 IXP2000 systems where the bus has to be
1710 configured a certain way for adjunct CPUs.
1711 noearly [X86] Don't do any early type 1 scanning.
1712 This might help on some broken boards which
1713 machine check when some devices' config space
1714 is read. But various workarounds are disabled
1715 and some IOMMU drivers will not work.
1716 bfsort Sort PCI devices into breadth-first order.
1717 This sorting is done to get a device
1718 order compatible with older (<= 2.4) kernels.
1719 nobfsort Don't sort PCI devices into breadth-first order.
1720 cbiosize=nn[KMG] The fixed amount of bus space which is
1721 reserved for the CardBus bridge's IO window.
1722 The default value is 256 bytes.
1723 cbmemsize=nn[KMG] The fixed amount of bus space which is
1724 reserved for the CardBus bridge's memory
1725 window. The default value is 64 megabytes.
1727 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1730 force Enable ASPM even on devices that claim not to support it.
1731 WARNING: Forcing ASPM on may cause system lockups.
1733 pcmv= [HW,PCMCIA] BadgePAD 4
1736 See Documentation/blockdev/paride.txt.
1738 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1741 See arch/parisc/kernel/pdc_chassis.c
1744 See Documentation/blockdev/paride.txt.
1747 See Documentation/blockdev/paride.txt.
1749 pirq= [SMP,APIC] Manual mp-table setup
1750 See Documentation/x86/i386/IO-APIC.txt.
1752 plip= [PPT,NET] Parallel port network link
1753 Format: { parport<nr> | timid | 0 }
1754 See also Documentation/parport.txt.
1756 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1757 Override pmtimer IOPort with a hex value.
1761 Enable PNP debug messages. This depends on the
1762 CONFIG_PNP_DEBUG_MESSAGES option.
1768 { on | off | curr | res | no-curr | no-res }
1771 [ISAPNP] Exclude IRQs for the autoconfiguration
1774 [ISAPNP] Exclude DMAs for the autoconfiguration
1776 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1777 Ranges are in pairs (I/O port base and size).
1780 [ISAPNP] Exclude memory regions for the
1782 Ranges are in pairs (memory base and size).
1785 Enables pr_debug()/dev_dbg() calls if
1786 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1787 be switched on/off via <debugfs>/dynamic_printk/modules
1789 print-fatal-signals=
1790 [KNL] debug: print fatal signals
1791 print-fatal-signals=1: print segfault info to
1795 printk.time= Show timing data prefixed to each printk message line
1796 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1798 profile= [KNL] Enable kernel profiling via /proc/profile
1799 Format: [schedule,]<number>
1800 Param: "schedule" - profile schedule points.
1801 Param: <number> - step/bucket size as a power of 2 for
1802 statistical time based profiling.
1803 Param: "sleep" - profile D-state sleeping (millisecs).
1804 Requires CONFIG_SCHEDSTATS
1805 Param: "kvm" - profile VM exits.
1807 processor.max_cstate= [HW,ACPI]
1808 Limit processor to maximum C-state
1809 max_cstate=9 overrides any DMI blacklist limit.
1811 processor.nocst [HW,ACPI]
1812 Ignore the _CST method to determine C-states,
1813 instead using the legacy FADT method
1815 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1817 See Documentation/blockdev/ramdisk.txt.
1819 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1820 probe for; one of (bare|imps|exps|lifebook|any).
1821 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1823 psmouse.resetafter= [HW,MOUSE]
1824 Try to reset the device after so many bad packets
1827 [HW,MOUSE] Set desired mouse resolution, in dpi.
1828 psmouse.smartscroll=
1829 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1830 0 = disabled, 1 = enabled (default).
1832 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1834 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1837 See Documentation/blockdev/paride.txt.
1840 [KNL] Number of legacy pty's. Overwrites compiled-in
1843 quiet [KNL] Disable most log messages
1848 See Documentation/md.txt.
1850 ramdisk_blocksize= [RAM]
1851 See Documentation/blockdev/ramdisk.txt.
1853 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1854 See Documentation/blockdev/ramdisk.txt.
1856 rcupdate.blimit= [KNL,BOOT]
1857 Set maximum number of finished RCU callbacks to process
1860 rcupdate.qhimark= [KNL,BOOT]
1861 Set threshold of queued
1862 RCU callbacks over which batch limiting is disabled.
1864 rcupdate.qlowmark= [KNL,BOOT]
1865 Set threshold of queued RCU callbacks below which
1866 batch limiting is re-enabled.
1870 Run specified binary instead of /init from the ramdisk,
1871 used for early userspace startup. See initrd.
1873 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1874 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1875 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1878 [KNL, SMP] Set scheduler's default relax_domain_level.
1879 See Documentation/cpusets.txt.
1881 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1883 reservetop= [X86-32]
1885 Reserves a hole at the top of the kernel virtual
1888 reset_devices [KNL] Force drivers to reset the underlying device
1889 during initialization.
1892 Specify the partition device for software suspend
1894 resume_offset= [SWSUSP]
1895 Specify the offset from the beginning of the partition
1896 given by "resume=" at which the swap header is located,
1897 in <PAGE_SIZE> units (needed only for swap files).
1898 See Documentation/power/swsusp-and-swap-files.txt
1900 retain_initrd [RAM] Keep initrd memory after extraction
1902 rhash_entries= [KNL,NET]
1903 Set number of hash buckets for route cache
1905 riscom8= [HW,SERIAL]
1906 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1908 ro [KNL] Mount root device read-only on boot
1910 root= [KNL] Root filesystem
1912 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1913 mount the root filesystem
1915 rootflags= [KNL] Set root filesystem mount option string
1917 rootfstype= [KNL] Set root filesystem type
1919 rootwait [KNL] Wait (indefinitely) for root device to show up.
1920 Useful for devices that are detected asynchronously
1921 (e.g. USB and MMC devices).
1923 root_plug.vendor_id=
1924 [ROOTPLUG] Override the default vendor ID
1926 root_plug.product_id=
1927 [ROOTPLUG] Override the default product ID
1930 [ROOTPLUG] Enable debugging output
1932 rw [KNL] Mount root device read-write on boot
1934 S [KNL] Run init in single mode
1937 See drivers/net/irda/sa1100_ir.c.
1939 sbni= [NET] Granch SBNI12 leased line adapter
1941 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1942 Format: <io>[,<timeout>[,<isapnp>]]
1944 scsi_debug_*= [SCSI]
1945 See drivers/scsi/scsi_debug.c.
1947 scsi_default_dev_flags=
1948 [SCSI] SCSI default device flags
1951 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1952 Format: <vendor>:<model>:<flags>
1953 (flags are integer value)
1955 scsi_logging_level= [SCSI] a bit mask of logging levels
1956 See drivers/scsi/scsi_logging.h for bits. Also
1957 settable via sysctl at dev.scsi.logging_level
1958 (/proc/sys/dev/scsi/logging_level).
1959 There is also a nice 'scsi_logging_level' script in the
1960 S390-tools package, available for download at
1961 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1963 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1964 discovered. async scans them in kernel threads,
1965 allowing boot to proceed. none ignores them, expecting
1966 user space to do the scan.
1968 selinux [SELINUX] Disable or enable SELinux at boot time.
1969 Format: { "0" | "1" }
1970 See security/selinux/Kconfig help text.
1973 Default value is set via kernel config option.
1974 If enabled at boot time, /selinux/disable can be used
1975 later to disable prior to initial policy load.
1977 selinux_compat_net =
1978 [SELINUX] Set initial selinux_compat_net flag value.
1979 Format: { "0" | "1" }
1980 0 -- use new secmark-based packet controls
1981 1 -- use legacy packet controls
1982 Default value is 0 (preferred).
1983 Value can be changed at runtime via
1984 /selinux/compat_net.
1986 serialnumber [BUGS=X86-32]
1989 Maximal number of shapers.
1991 show_msr= [x86] show boot-time MSR settings
1992 Format: { <integer> }
1993 Show boot-time (BIOS-initialized) MSR settings.
1994 The parameter means the number of CPUs to show,
1995 for example 1 means boot CPU only.
1998 See header of drivers/scsi/sim710.c.
2005 slub_debug[=options[,slabs]] [MM, SLUB]
2006 Enabling slub_debug allows one to determine the
2007 culprit if slab objects become corrupted. Enabling
2008 slub_debug can create guard zones around objects and
2009 may poison objects when not in use. Also tracks the
2010 last alloc / free. For more information see
2011 Documentation/vm/slub.txt.
2013 slub_max_order= [MM, SLUB]
2014 Determines the maximum allowed order for slabs.
2015 A high setting may cause OOMs due to memory
2016 fragmentation. For more information see
2017 Documentation/vm/slub.txt.
2019 slub_min_objects= [MM, SLUB]
2020 The minimum number of objects per slab. SLUB will
2021 increase the slab order up to slub_max_order to
2022 generate a sufficiently large slab able to contain
2023 the number of objects indicated. The higher the number
2024 of objects the smaller the overhead of tracking slabs
2025 and the less frequently locks need to be acquired.
2026 For more information see Documentation/vm/slub.txt.
2028 slub_min_order= [MM, SLUB]
2029 Determines the mininum page order for slabs. Must be
2030 lower than slub_max_order.
2031 For more information see Documentation/vm/slub.txt.
2033 slub_nomerge [MM, SLUB]
2034 Disable merging of slabs with similar size. May be
2035 necessary if there is some reason to distinguish
2036 allocs to different slabs. Debug options disable
2037 merging on their own.
2038 For more information see Documentation/vm/slub.txt.
2041 Format: <io1>[,<io2>[,...,<io8>]]
2043 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2044 attempt to substitute SMP alternatives once at boot.
2046 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2047 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2048 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2049 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2050 smsc-ircc2.ircc_irq= [HW] IRQ line
2051 smsc-ircc2.ircc_dma= [HW] DMA channel
2052 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2053 0: Toshiba Satellite 1800 (GP data pin select)
2054 1: Fast pin select (default)
2057 snd-ad1816a= [HW,ALSA]
2059 snd-ad1848= [HW,ALSA]
2061 snd-ali5451= [HW,ALSA]
2063 snd-als100= [HW,ALSA]
2065 snd-als4000= [HW,ALSA]
2067 snd-azt2320= [HW,ALSA]
2069 snd-cmi8330= [HW,ALSA]
2071 snd-cmipci= [HW,ALSA]
2073 snd-cs4231= [HW,ALSA]
2075 snd-cs4232= [HW,ALSA]
2077 snd-cs4236= [HW,ALSA]
2079 snd-cs4281= [HW,ALSA]
2081 snd-cs46xx= [HW,ALSA]
2083 snd-dt019x= [HW,ALSA]
2085 snd-dummy= [HW,ALSA]
2087 snd-emu10k1= [HW,ALSA]
2089 snd-ens1370= [HW,ALSA]
2091 snd-ens1371= [HW,ALSA]
2093 snd-es968= [HW,ALSA]
2095 snd-es1688= [HW,ALSA]
2097 snd-es18xx= [HW,ALSA]
2099 snd-es1938= [HW,ALSA]
2101 snd-es1968= [HW,ALSA]
2103 snd-fm801= [HW,ALSA]
2105 snd-gusclassic= [HW,ALSA]
2107 snd-gusextreme= [HW,ALSA]
2109 snd-gusmax= [HW,ALSA]
2113 snd-ice1712= [HW,ALSA]
2115 snd-intel8x0= [HW,ALSA]
2117 snd-interwave= [HW,ALSA]
2122 snd-korg1212= [HW,ALSA]
2124 snd-maestro3= [HW,ALSA]
2126 snd-mpu401= [HW,ALSA]
2128 snd-mtpav= [HW,ALSA]
2130 snd-nm256= [HW,ALSA]
2132 snd-opl3sa2= [HW,ALSA]
2140 snd-opti93x= [HW,ALSA]
2144 snd-rme32= [HW,ALSA]
2146 snd-rme96= [HW,ALSA]
2148 snd-rme9652= [HW,ALSA]
2154 snd-sbawe= [HW,ALSA]
2156 snd-serial= [HW,ALSA]
2158 snd-sgalaxy= [HW,ALSA]
2160 snd-sonicvibes= [HW,ALSA]
2165 snd-sun-cs4231= [HW,ALSA]
2167 snd-trident= [HW,ALSA]
2169 snd-usb-audio= [HW,ALSA,USB]
2171 snd-via82xx= [HW,ALSA]
2173 snd-virmidi= [HW,ALSA]
2175 snd-wavefront= [HW,ALSA]
2177 snd-ymfpci= [HW,ALSA]
2180 [KNL] Should the soft-lockup detector generate panics.
2182 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2183 See Documentation/sonypi.txt
2185 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2186 See Documentation/serial/specialix.txt.
2188 spia_io_base= [HW,MTD]
2194 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2196 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2197 See Documentation/scsi/st.txt.
2201 Set the STI (builtin display/keyboard on the HP-PARISC
2202 machines) console (graphic card) which should be used
2203 as the initial boot-console.
2204 See also comment in drivers/video/console/sticore.c.
2207 See comment in drivers/video/console/sticore.c.
2210 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2214 Control how the NFS server code allocates CPUs to
2215 service thread pools. Depending on how many NICs
2216 you have and where their interrupts are bound, this
2217 option will affect which CPUs will do NFS serving.
2218 Note: this parameter cannot be changed while the
2219 NFS server is running.
2221 auto the server chooses an appropriate mode
2222 automatically using heuristics
2223 global a single global pool contains all CPUs
2224 percpu one pool for each CPU
2225 pernode one pool for each NUMA node (equivalent
2226 to global on non-NUMA machines)
2228 swiotlb= [IA-64] Number of I/O TLB slabs
2232 sym53c416= [HW,SCSI]
2233 See header of drivers/scsi/sym53c416.c.
2235 sysrq_always_enabled
2237 Ignore sysrq setting - this boot parameter will
2238 neutralize any effect of /proc/sys/kernel/sysrq.
2239 Useful for debugging.
2242 See header of drivers/scsi/t128.c.
2246 test_suspend= [SUSPEND]
2247 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2248 standby suspend) as the system sleep state to briefly
2249 enter during system startup. The system is woken from
2250 this state using a wakeup-capable RTC alarm.
2252 thash_entries= [KNL,NET]
2253 Set number of hash buckets for TCP connection
2255 thermal.act= [HW,ACPI]
2256 -1: disable all active trip points in all thermal zones
2257 <degrees C>: override all lowest active trip points
2259 thermal.crt= [HW,ACPI]
2260 -1: disable all critical trip points in all thermal zones
2261 <degrees C>: override all critical trip points
2263 thermal.nocrt= [HW,ACPI]
2264 Set to disable actions on ACPI thermal zone
2265 critical and hot trip points.
2267 thermal.off= [HW,ACPI]
2268 1: disable ACPI thermal control
2270 thermal.psv= [HW,ACPI]
2271 -1: disable all passive trip points
2272 <degrees C>: override all passive trip points to this value
2274 thermal.tzp= [HW,ACPI]
2275 Specify global default ACPI thermal zone polling rate
2276 <deci-seconds>: poll all this frequency
2277 0: no polling (default)
2280 See comment before function dc390_setup() in
2281 drivers/scsi/tmscsim.c.
2285 trix= [HW,OSS] MediaTrix AudioTrix Pro
2287 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2289 tsc= Disable clocksource-must-verify flag for TSC.
2291 [x86] reliable: mark tsc clocksource as reliable, this
2292 disables clocksource verification at runtime.
2293 Used to enable high-resolution timer mode on older
2294 hardware, and in virtualized environment.
2296 turbografx.map[2|3]= [HW,JOY]
2297 TurboGraFX parallel port interface
2299 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2300 See also Documentation/input/joystick-parport.txt
2302 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2303 See header of drivers/scsi/u14-34f.c.
2312 [USB] Ignore overcurrent events (default N).
2313 Some badly-designed motherboards generate lots of
2314 bogus events, for ports that aren't wired to
2315 anything. Set this parameter to avoid log spamming.
2316 Note that genuine overcurrent events won't be
2321 Set unknown_nmi_panic=1 early on boot.
2323 usbcore.autosuspend=
2324 [USB] The autosuspend time delay (in seconds) used
2325 for newly-detected USB devices (default 2). This
2326 is the time required before an idle device will be
2327 autosuspended. Devices for which the delay is set
2328 to a negative value won't be autosuspended at all.
2330 usbcore.usbfs_snoop=
2331 [USB] Set to log all usbfs traffic (default 0 = off).
2333 usbcore.blinkenlights=
2334 [USB] Set to cycle leds on hubs (default 0 = off).
2336 usbcore.old_scheme_first=
2337 [USB] Start with the old device initialization
2338 scheme (default 0 = off).
2340 usbcore.use_both_schemes=
2341 [USB] Try the other device initialization scheme
2342 if the first one fails (default 1 = enabled).
2344 usbcore.initial_descriptor_timeout=
2345 [USB] Specifies timeout for the initial 64-byte
2346 USB_REQ_GET_DESCRIPTOR request in milliseconds
2347 (default 5000 = 5.0 seconds).
2350 [USBHID] The interval which mice are to be polled at.
2352 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2353 kernel's map of available physical RAM.
2355 vdso= [X86-32,SH,x86-64]
2356 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2357 vdso=1: enable VDSO (default)
2358 vdso=0: disable VDSO mapping
2360 vdso32= [X86-32,X86-64]
2361 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2362 vdso32=1: enable 32-bit VDSO (default)
2363 vdso32=0: disable 32-bit VDSO mapping
2366 vector=percpu: enable percpu vector domain
2368 video= [FB] Frame buffer configuration
2369 See Documentation/fb/modedb.txt.
2371 vga= [BOOT,X86-32] Select a particular video mode
2372 See Documentation/x86/i386/boot.txt and
2373 Documentation/svga.txt.
2374 Use vga=ask for menu.
2375 This is actually a boot loader parameter; the value is
2376 passed to the kernel using a special protocol.
2378 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2379 size of <nn>. This can be used to increase the
2380 minimum size (128MB on x86). It can also be used to
2381 decrease the size and leave more room for directly
2384 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2387 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2390 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2393 waveartist= [HW,OSS]
2394 Format: <io>,<irq>,<dma>,<dma2>
2397 See header of drivers/scsi/wd33c93.c.
2400 See header of drivers/scsi/wd7000.c.
2403 See Documentation/watchdog/wdt.txt.
2405 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2406 xd_geo= See header of drivers/block/xd.c.
2408 xirc2ps_cs= [NET,PCMCIA]
2410 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2412 norandmaps Don't use address space randomization
2413 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2415 ______________________________________________________________________
2419 Add documentation for ALSA options.
2420 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob