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 hvc_iucv= [S390] Number of z/VM IUCV Hypervisor console (HVC)
818 back-ends. Valid parameters: 0..8
820 i8042.debug [HW] Toggle i8042 debug mode
821 i8042.direct [HW] Put keyboard port into non-translated mode
822 i8042.dumbkbd [HW] Pretend that controller can only read data from
823 keyboard and cannot control its state
824 (Don't attempt to blink the leds)
825 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
826 i8042.nokbd [HW] Don't check/create keyboard port
827 i8042.noloop [HW] Disable the AUX Loopback command while probing
829 i8042.nomux [HW] Don't check presence of an active multiplexing
831 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
834 [HW] Frequency with which keyboard LEDs should blink
835 when kernel panics (default is 0.5 sec)
836 i8042.reset [HW] Reset the controller during init and cleanup
837 i8042.unlock [HW] Unlock (ignore) the keylock
841 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
842 indicates that the driver is running on unsupported
844 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
845 does not match list of supported models.
847 [HW] Report power status in /proc/i8k
848 (disabled by default)
849 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
852 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
853 See Documentation/mca.txt.
856 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
858 ide= [HW] (E)IDE subsystem
859 Format: ide=nodma or ide=doubler
860 See Documentation/ide/ide.txt.
862 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
863 See Documentation/ide/ide.txt.
866 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
867 Poll forces a polling idle loop that can slightly improves the performance
868 of waking up a idle CPU, but will use a lot of power and make the system
869 run hot. Not recommended.
870 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
871 to not use it because it doesn't save as much power as a normal idle
872 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
874 idle=halt. Halt is forced to be used for CPU idle.
875 In such case C2/C3 won't be used again.
876 idle=nomwait. Disable mwait for CPU C-states
878 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
879 Claim all unknown PCI IDE storage controllers.
881 ignore_loglevel [KNL]
882 Ignore loglevel setting - this will print /all/
883 kernel messages to the console. Useful for debugging.
886 Set number of hash buckets for inode cache.
889 See header of drivers/scsi/in2000.c.
893 Run specified binary instead of /sbin/init as init
896 initcall_debug [KNL] Trace initcalls as they are executed. Useful
897 for working out where the kernel is dying during
900 initrd= [BOOT] Specify the location of the initial ramdisk
902 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
920 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
922 Disable intel iommu driver.
923 igfx_off [Default Off]
924 By default, gfx is mapped as normal device. If a gfx
925 device has a dedicated DMAR unit, the DMAR unit is
926 bypassed by not enabling DMAR with this option. In
927 this case, gfx device will use physical address for
930 With this option iommu will not optimize to look
931 for io virtual address below 32 bit forcing dual
932 address cycle on pci bus for cards supporting greater
933 than 32 bit addressing. The default is to look
934 for translation below 32 bit and if not available
935 then look in the higher range.
937 With this option on every unmap_single operation will
938 result in a hardware IOTLB flush operation as opposed
939 to batching them for performance.
941 io_delay= [X86-32,X86-64] I/O delay method
943 Standard port 0x80 based delay
945 Alternate port 0xed based delay (needed on some systems)
947 Simple two microseconds delay
951 io7= [HW] IO7 for Marvel based alpha systems
952 See comment before marvel_specify_io7 in
953 arch/alpha/kernel/core_marvel.c.
956 See Documentation/filesystems/nfsroot.txt.
958 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
959 See comment before ip2_setup() in
960 drivers/char/ip2/ip2base.c.
962 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
963 See header of drivers/scsi/ips.c.
965 ports= [IP_VS_FTP] IPVS ftp helper module
967 Up to 8 (IP_VS_APP_MAX_PORTS) ports
969 Format: <port>,<port>....
972 When an interrupt is not handled search all handlers
973 for it. Intended to get systems with badly broken
977 When an interrupt is not handled search all handlers
978 for it. Also check all handlers each timer
979 interrupt. Intended to get systems with badly broken
983 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
985 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
987 <cpu number>,...,<cpu number>
989 <cpu number>-<cpu number>
990 (must be a positive range in ascending order)
992 <cpu number>,...,<cpu number>-<cpu number>
994 This option can be used to specify one or more CPUs
995 to isolate from the general SMP balancing and scheduling
996 algorithms. You can move a process onto or off an
997 "isolated" CPU via the CPU affinity syscalls or cpuset.
998 <cpu number> begins at 0 and the maximum value is
999 "number of CPUs in system - 1".
1001 This option is the preferred way to isolate CPUs. The
1002 alternative -- manually setting the CPU mask of all
1003 tasks in the system -- can cause problems and
1004 suboptimal load balancer performance.
1008 js= [HW,JOY] Analog joystick
1009 See Documentation/input/joystick.txt.
1011 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1012 specifies the amount of memory usable by the kernel
1013 for non-movable allocations. The requested amount is
1014 spread evenly throughout all nodes in the system. The
1015 remaining memory in each node is used for Movable
1016 pages. In the event, a node is too small to have both
1017 kernelcore and Movable pages, kernelcore pages will
1018 take priority and other nodes will have a larger number
1019 of kernelcore pages. The Movable zone is used for the
1020 allocation of pages that may be reclaimed or moved
1021 by the page migration subsystem. This means that
1022 HugeTLB pages may not be allocated from this zone.
1023 Note that allocations like PTEs-from-HighMem still
1024 use the HighMem zone if it exists, and the Normal
1025 zone if it does not.
1027 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1028 is similar to kernelcore except it specifies the
1029 amount of memory used for migratable allocations.
1030 If both kernelcore and movablecore is specified,
1031 then kernelcore will be at *least* the specified
1032 value but may be more. If movablecore on its own
1033 is specified, the administrator must be careful
1034 that the amount of memory usable for all allocations
1039 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1042 kgdboc= [HW] kgdb over consoles.
1043 Requires a tty driver that supports console polling.
1044 (only serial suported for now)
1045 Format: <serial_device>[,baud]
1047 kmac= [MIPS] korina ethernet MAC address.
1048 Configure the RouterBoard 532 series on-chip
1049 Ethernet adapter MAC address.
1055 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1058 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1061 libata.dma= [LIBATA] DMA control
1062 libata.dma=0 Disable all PATA and SATA DMA
1063 libata.dma=1 PATA and SATA Disk DMA only
1064 libata.dma=2 ATAPI (CDROM) DMA only
1065 libata.dma=4 Compact Flash DMA only
1066 Combinations also work, so libata.dma=3 enables DMA
1067 for disks and CDROMs, but not CFs.
1069 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1073 libata.force= [LIBATA] Force configurations. The format is comma
1074 separated list of "[ID:]VAL" where ID is
1075 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1076 matching port, link or device. Basically, it matches
1077 the ATA ID string printed on console by libata. If
1078 the whole ID part is omitted, the last PORT and DEVICE
1079 values are used. If ID hasn't been specified yet, the
1080 configuration applies to all ports, links and devices.
1082 If only DEVICE is omitted, the parameter applies to
1083 the port and all links and devices behind it. DEVICE
1084 number of 0 either selects the first device or the
1085 first fan-out link behind PMP device. It does not
1086 select the host link. DEVICE number of 15 selects the
1087 host link and device attached to it.
1089 The VAL specifies the configuration to force. As long
1090 as there's no ambiguity shortcut notation is allowed.
1091 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1092 The following configurations can be forced.
1094 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1095 Any ID with matching PORT is used.
1097 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1099 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1100 udma[/][16,25,33,44,66,100,133] notation is also
1103 * [no]ncq: Turn on or off NCQ.
1105 * nohrst, nosrst, norst: suppress hard, soft
1108 If there are multiple matching configurations changing
1109 the same attribute, the last one is used.
1111 load_ramdisk= [RAM] List of ramdisks to load from floppy
1112 See Documentation/blockdev/ramdisk.txt.
1114 lockd.nlm_grace_period=P [NFS] Assign grace period.
1117 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1120 lockd.nlm_timeout=T [NFS] Assign timeout value.
1123 lockd.nlm_udpport=M [NFS] Assign UDP port.
1126 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1129 loglevel= All Kernel Messages with a loglevel smaller than the
1130 console loglevel will be printed to the console. It can
1131 also be changed with klogd or other programs. The
1132 loglevels are defined as follows:
1134 0 (KERN_EMERG) system is unusable
1135 1 (KERN_ALERT) action must be taken immediately
1136 2 (KERN_CRIT) critical conditions
1137 3 (KERN_ERR) error conditions
1138 4 (KERN_WARNING) warning conditions
1139 5 (KERN_NOTICE) normal but significant condition
1140 6 (KERN_INFO) informational
1141 7 (KERN_DEBUG) debug-level messages
1143 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1144 Format: { n | nk | nM }
1145 n must be a power of two. The default size
1146 is set in the kernel config file.
1148 logo.nologo [FB] Disables display of the built-in Linux logo.
1149 This may be used to provide more screen space for
1150 kernel log messages and is useful when debugging
1151 kernel boot problems.
1153 lp=0 [LP] Specify parallel ports to use, e.g,
1154 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1155 lp=reset first parallel port). 'lp=0' disables the
1156 lp=auto printer driver. 'lp=reset' (which can be
1157 specified in addition to the ports) causes
1158 attached printers to be reset. Using
1159 lp=port1,port2,... specifies the parallel ports
1160 to associate lp devices with, starting with
1161 lp0. A port specification may be 'none' to skip
1162 that lp device, or a parport name such as
1163 'parport0'. Specifying 'lp=auto' instead of a
1164 port specification list means that device IDs
1165 from each port should be examined, to see if
1166 an IEEE 1284-compliant printer is attached; if
1167 so, the driver will manage that printer.
1168 See also header of drivers/char/lp.c.
1171 Sets loops_per_jiffy to given constant, thus avoiding
1172 time-consuming boot-time autodetection (up to 250 ms per
1173 CPU). 0 enables autodetection (default). To determine
1174 the correct value for your kernel, boot with normal
1175 autodetection and see what value is printed. Note that
1176 on SMP systems the preset will be applied to all CPUs,
1177 which is likely to cause problems if your CPUs need
1178 significantly divergent settings. An incorrect value
1179 will cause delays in the kernel to be wrong, leading to
1180 unpredictable I/O errors and other breakage. Although
1181 unlikely, in the extreme case this might damage your
1185 Format: <io>,<irq>,<dma>
1187 mac5380= [HW,SCSI] Format:
1188 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1190 machvec= [IA64] Force the use of a particular machine-vector
1191 (machvec) in a generic kernel.
1192 Example: machvec=hpzx1_swiotlb
1194 max_loop= [LOOP] Maximum number of loopback devices that can
1198 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1199 should make use of. maxcpus=n : n >= 0 limits the
1200 kernel to using 'n' processors. n=0 is a special case,
1201 it is equivalent to "nosmp", which also disables
1204 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1205 or equal to this physical address is ignored.
1207 max_luns= [SCSI] Maximum number of LUNs to probe.
1208 Should be between 1 and 2^32-1.
1211 [SCSI] Maximum number of LUNs received.
1212 Should be between 1 and 16384.
1216 mce [X86-32] Machine Check Exception
1218 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1220 md= [HW] RAID subsystems devices and level
1221 See Documentation/md.txt.
1224 Format: <first>,<last>
1225 Specifies range of consoles to be captured by the MDA.
1227 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1228 Amount of memory to be used when the kernel is not able
1229 to see the whole system memory or for test.
1230 [X86-32] Use together with memmap= to avoid physical
1231 address space collisions. Without memmap= PCI devices
1232 could be placed at addresses belonging to unused RAM.
1234 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1238 [KNL,SH] Allow user to override the default size for
1239 per-device physically contiguous DMA buffers.
1241 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1242 E820 memory map, as specified by the user.
1243 Such memmap=exactmap lines can be constructed based on
1244 BIOS output or other requirements. See the memmap=nn@ss
1247 memmap=nn[KMG]@ss[KMG]
1248 [KNL] Force usage of a specific region of memory
1249 Region of memory to be used, from ss to ss+nn.
1251 memmap=nn[KMG]#ss[KMG]
1252 [KNL,ACPI] Mark specific memory as ACPI data.
1253 Region of memory to be used, from ss to ss+nn.
1255 memmap=nn[KMG]$ss[KMG]
1256 [KNL,ACPI] Mark specific memory as reserved.
1257 Region of memory to be used, from ss to ss+nn.
1258 Example: Exclude memory from 0x18690000-0x1869ffff
1259 memmap=64K$0x18690000
1261 memmap=0x10000$0x18690000
1263 memory_corruption_check=0/1 [X86]
1264 Some BIOSes seem to corrupt the first 64k of
1265 memory when doing things like suspend/resume.
1266 Setting this option will scan the memory
1267 looking for corruption. Enabling this will
1268 both detect corruption and prevent the kernel
1269 from using the memory being corrupted.
1270 However, its intended as a diagnostic tool; if
1271 repeatable BIOS-originated corruption always
1272 affects the same memory, you can use memmap=
1273 to prevent the kernel from using that memory.
1275 memory_corruption_check_size=size [X86]
1276 By default it checks for corruption in the low
1277 64k, making this memory unavailable for normal
1278 use. Use this parameter to scan for
1279 corruption in more or less memory.
1281 memory_corruption_check_period=seconds [X86]
1282 By default it checks for corruption every 60
1283 seconds. Use this parameter to check at some
1284 other rate. 0 disables periodic checking.
1286 memtest= [KNL,X86] Enable memtest
1288 range: 0,4 : pattern number
1289 default : 0 <disable>
1291 meye.*= [HW] Set MotionEye Camera parameters
1292 See Documentation/video4linux/meye.txt.
1294 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1295 Multi-Function General Purpose Timers on AMD Geode
1298 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1299 the BIOS has incorrectly applied a workaround. TinyBIOS
1300 version 0.98 is known to be affected, 0.99 fixes the
1301 problem by letting the user disable the workaround.
1305 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1306 physical address is ignored.
1309 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1310 parameter allows control of the logging verbosity for
1311 the additional memory initialisation checks. A value
1312 of 0 disables mminit logging and a level of 4 will
1313 log everything. Information is printed at KERN_DEBUG
1314 so loglevel=8 may also need to be specified.
1317 [MOUSE] Maximum time between finger touching and
1318 leaving touchpad surface for touch to be considered
1319 a tap and be reported as a left button click (for
1320 touchpads working in absolute mode only).
1322 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1323 reporting absolute coordinates, such as tablets
1324 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1325 reporting absolute coordinates, such as tablets
1330 MTD_Partition= [MTD]
1331 Format: <name>,<region-number>,<size>,<offset>
1333 MTD_Region= [MTD] Format:
1334 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1337 See drivers/mtd/cmdlinepart.c.
1340 ARM/S3C2412 JIVE boot control
1342 See arch/arm/mach-s3c2412/mach-jive.c
1344 mtouchusb.raw_coordinates=
1345 [HW] Make the MicroTouch USB driver use raw coordinates
1346 ('y', default) or cooked coordinates ('n')
1348 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1351 See header of drivers/scsi/NCR_D700.c.
1355 ncr53c400= [HW,SCSI]
1357 ncr53c400a= [HW,SCSI]
1359 ncr53c406a= [HW,SCSI]
1361 ncr53c8xx= [HW,SCSI]
1363 netdev= [NET] Network devices parameters
1364 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1365 Note that mem_start is often overloaded to mean
1366 something different and driver-specific.
1367 This usage is only documented in each driver source
1371 [NETFILTER] Enable connection tracking flow accounting
1372 0 to disable accounting
1373 1 to enable accounting
1374 Default value depends on CONFIG_NF_CT_ACCT that is
1375 going to be removed in 2.6.29.
1378 See Documentation/filesystems/nfsroot.txt.
1380 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1381 See Documentation/filesystems/nfsroot.txt.
1383 nfs.callback_tcpport=
1384 [NFS] set the TCP port on which the NFSv4 callback
1385 channel should listen.
1387 nfs.idmap_cache_timeout=
1388 [NFS] set the maximum lifetime for idmapper cache
1392 [NFS] enable 64-bit inode numbers.
1393 If zero, the NFS client will fake up a 32-bit inode
1394 number for the readdir() and stat() syscalls instead
1395 of returning the full 64-bit number.
1396 The default is to return 64-bit inode numbers.
1398 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1399 when a NMI is triggered.
1400 Format: [state][,regs][,debounce][,die]
1402 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1404 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1405 emulation library even if a 387 maths coprocessor
1408 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1409 caches in the slab allocator. Saves per-node memory,
1410 but will impact performance.
1414 noapic [SMP,APIC] Tells the kernel to not make use of any
1415 IOAPICs that may be present in the system.
1417 nobats [PPC] Do not use BATs for mapping kernel lowmem
1418 on "Classic" PPC cores.
1422 nodelayacct [KNL] Disable per-task delay accounting
1424 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1426 nodsp [SH] Disable hardware DSP at boot time.
1428 noefi [X86-32,X86-64] Disable EFI runtime services support.
1432 noexec [X86-32,X86-64]
1433 On X86-32 available only on PAE configured kernels.
1434 noexec=on: enable non-executable mappings (default)
1435 noexec=off: disable non-executable mappings
1438 This affects only 32-bit executables.
1439 noexec32=on: enable non-executable mappings (default)
1440 read doesn't imply executable mappings
1441 noexec32=off: disable non-executable mappings
1442 read implies executable mappings
1444 nofpu [SH] Disable hardware FPU at boot time.
1446 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1447 register save and restore. The kernel will only save
1448 legacy floating-point registers on task switch.
1450 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1454 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1455 instruction doesn't work correctly and not to
1458 nohalt [IA-64] Tells the kernel not to use the power saving
1459 function PAL_HALT_LIGHT when idle. This increases
1460 power-consumption. On the positive side, it reduces
1461 interrupt wake-up latency, which may improve performance
1462 in certain environments such as networked servers or
1465 nohz= [KNL] Boottime enable/disable dynamic ticks
1466 Valid arguments: on, off
1469 noirqdebug [X86-32] Disables the code which attempts to detect and
1470 disable unhandled interrupt sources.
1472 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1473 broken timer IRQ sources.
1475 noisapnp [ISAPNP] Disables ISA PnP code.
1477 noinitrd [RAM] Tells the kernel not to load any configured
1482 nojitter [IA64] Disables jitter checking for ITC timers.
1484 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1486 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1488 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1490 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1491 default x2apic cluster mode on platforms
1494 noltlbs [PPC] Do not use large page/tlb entries for kernel
1495 lowmem mapping on PPC40x.
1497 nomca [IA-64] Disable machine check abort handling
1499 nomce [X86-32] Machine Check Exception
1501 nomfgpt [X86-32] Disable Multi-Function General Purpose
1502 Timer usage (for AMD Geode machines).
1504 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1506 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1507 with UP alternatives
1509 noresidual [PPC] Don't use residual data on PReP machines.
1511 noresume [SWSUSP] Disables resume and restores original swap
1514 no-scroll [VGA] Disables scrollback.
1515 This is required for the Braillex ib80-piezo Braille
1516 reader made by F.H. Papenmeier (Germany).
1520 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1522 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1523 and disable the IO APIC. legacy for "maxcpus=0".
1525 nosoftlockup [KNL] Disable the soft-lockup detector.
1527 nosync [HW,M68K] Disables sync negotiation for all devices.
1529 notsc [BUGS=X86-32] Disable Time Stamp Counter
1531 nousb [USB] Disable the USB subsystem
1535 nptcg= [IA64] Override max number of concurrent global TLB
1536 purges which is reported from either PAL_VM_SUMMARY or
1539 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1540 one of ['zone', 'node', 'default'] can be specified
1541 This can be set from sysctl after boot.
1542 See Documentation/sysctl/vm.txt for details.
1544 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1546 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1547 Rather than timing out after 20 ms if an EC
1548 command is not properly ACKed, override the length
1549 of the timeout. We have interrupts disabled while
1550 waiting for the ACK, so if this is set too high
1551 interrupts *may* be lost!
1556 oprofile.timer= [HW]
1557 Use timer interrupt instead of performance counters
1559 osst= [HW,SCSI] SCSI Tape Driver
1560 Format: <buffer_size>,<write_threshold>
1561 See also Documentation/scsi/st.txt.
1563 panic= [KNL] Kernel behaviour on panic
1566 parkbd.port= [HW] Parallel port number the keyboard adapter is
1567 connected to, default is 0.
1569 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1570 0 for XT, 1 for AT (default is AT).
1573 parport= [HW,PPT] Specify parallel ports. 0 disables.
1574 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1575 Use 'auto' to force the driver to use any
1576 IRQ/DMA settings detected (the default is to
1577 ignore detected IRQ/DMA settings because of
1578 possible conflicts). You can specify the base
1579 address, IRQ, and DMA settings; IRQ and DMA
1580 should be numbers, or 'auto' (for using detected
1581 settings on that particular port), or 'nofifo'
1582 (to avoid using a FIFO even if it is detected).
1583 Parallel ports are assigned in the order they
1584 are specified on the command line, starting
1587 parport_init_mode= [HW,PPT]
1588 Configure VIA parallel port to operate in
1589 a specific mode. This is necessary on Pegasos
1590 computer where firmware has no options for setting
1591 up parallel port mode and sets it to spp.
1592 Currently this function knows 686a and 8231 chips.
1593 Format: [spp|ps2|epp|ecp|ecpepp]
1595 pas2= [HW,OSS] Format:
1596 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1599 See header of drivers/scsi/pas16.c.
1602 Halt all CPUs after the first oops has been printed for
1603 the specified number of seconds. This is to be used if
1604 your oopses keep scrolling off the screen.
1609 See header of drivers/block/paride/pcd.c.
1610 See also Documentation/blockdev/paride.txt.
1612 pci=option[,option...] [PCI] various PCI subsystem options:
1613 off [X86] don't probe for the PCI bus
1614 bios [X86-32] force use of PCI BIOS, don't access
1615 the hardware directly. Use this if your machine
1616 has a non-standard PCI host bridge.
1617 nobios [X86-32] disallow use of PCI BIOS, only direct
1618 hardware access methods are allowed. Use this
1619 if you experience crashes upon bootup and you
1620 suspect they are caused by the BIOS.
1621 conf1 [X86] Force use of PCI Configuration
1623 conf2 [X86] Force use of PCI Configuration
1625 noaer [PCIE] If the PCIEAER kernel config parameter is
1626 enabled, this kernel boot option can be used to
1627 disable the use of PCIE advanced error reporting.
1628 nodomains [PCI] Disable support for multiple PCI
1629 root domains (aka PCI segments, in ACPI-speak).
1630 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1632 nomsi [MSI] If the PCI_MSI kernel config parameter is
1633 enabled, this kernel boot option can be used to
1634 disable the use of MSI interrupts system-wide.
1635 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1636 routing table. These calls are known to be buggy
1637 on several machines and they hang the machine
1638 when used, but on other computers it's the only
1639 way to get the interrupt routing table. Try
1640 this option if the kernel is unable to allocate
1641 IRQs or discover secondary PCI buses on your
1643 rom [X86] Assign address space to expansion ROMs.
1644 Use with caution as certain devices share
1645 address decoders between ROMs and other
1647 norom [X86] Do not assign address space to
1648 expansion ROMs that do not already have
1649 BIOS assigned address ranges.
1650 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1651 assigned automatically to PCI devices. You can
1652 make the kernel exclude IRQs of your ISA cards
1654 pirqaddr=0xAAAAA [X86] Specify the physical address
1655 of the PIRQ table (normally generated
1656 by the BIOS) if it is outside the
1657 F0000h-100000h range.
1658 lastbus=N [X86] Scan all buses thru bus #N. Can be
1659 useful if the kernel is unable to find your
1660 secondary buses and you want to tell it
1661 explicitly which ones they are.
1662 assign-busses [X86] Always assign all PCI bus
1663 numbers ourselves, overriding
1664 whatever the firmware may have done.
1665 usepirqmask [X86] Honor the possible IRQ mask stored
1666 in the BIOS $PIR table. This is needed on
1667 some systems with broken BIOSes, notably
1668 some HP Pavilion N5400 and Omnibook XE3
1669 notebooks. This will have no effect if ACPI
1670 IRQ routing is enabled.
1671 noacpi [X86] Do not use ACPI for IRQ routing
1672 or for PCI scanning.
1673 use_crs [X86] Use _CRS for PCI resource
1675 routeirq Do IRQ routing for all PCI devices.
1676 This is normally done in pci_enable_device(),
1677 so this option is a temporary workaround
1678 for broken drivers that don't call it.
1679 skip_isa_align [X86] do not align io start addr, so can
1680 handle more pci cards
1681 firmware [ARM] Do not re-enumerate the bus but instead
1682 just use the configuration from the
1683 bootloader. This is currently used on
1684 IXP2000 systems where the bus has to be
1685 configured a certain way for adjunct CPUs.
1686 noearly [X86] Don't do any early type 1 scanning.
1687 This might help on some broken boards which
1688 machine check when some devices' config space
1689 is read. But various workarounds are disabled
1690 and some IOMMU drivers will not work.
1691 bfsort Sort PCI devices into breadth-first order.
1692 This sorting is done to get a device
1693 order compatible with older (<= 2.4) kernels.
1694 nobfsort Don't sort PCI devices into breadth-first order.
1695 cbiosize=nn[KMG] The fixed amount of bus space which is
1696 reserved for the CardBus bridge's IO window.
1697 The default value is 256 bytes.
1698 cbmemsize=nn[KMG] The fixed amount of bus space which is
1699 reserved for the CardBus bridge's memory
1700 window. The default value is 64 megabytes.
1702 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1705 force Enable ASPM even on devices that claim not to support it.
1706 WARNING: Forcing ASPM on may cause system lockups.
1708 pcmv= [HW,PCMCIA] BadgePAD 4
1711 See Documentation/blockdev/paride.txt.
1713 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1716 See arch/parisc/kernel/pdc_chassis.c
1719 See Documentation/blockdev/paride.txt.
1722 See Documentation/blockdev/paride.txt.
1724 pirq= [SMP,APIC] Manual mp-table setup
1725 See Documentation/x86/i386/IO-APIC.txt.
1727 plip= [PPT,NET] Parallel port network link
1728 Format: { parport<nr> | timid | 0 }
1729 See also Documentation/parport.txt.
1731 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1732 Override pmtimer IOPort with a hex value.
1736 Enable PNP debug messages. This depends on the
1737 CONFIG_PNP_DEBUG_MESSAGES option.
1743 { on | off | curr | res | no-curr | no-res }
1746 [ISAPNP] Exclude IRQs for the autoconfiguration
1749 [ISAPNP] Exclude DMAs for the autoconfiguration
1751 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1752 Ranges are in pairs (I/O port base and size).
1755 [ISAPNP] Exclude memory regions for the
1757 Ranges are in pairs (memory base and size).
1760 Enables pr_debug()/dev_dbg() calls if
1761 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1762 be switched on/off via <debugfs>/dynamic_printk/modules
1764 print-fatal-signals=
1765 [KNL] debug: print fatal signals
1766 print-fatal-signals=1: print segfault info to
1770 printk.time= Show timing data prefixed to each printk message line
1771 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1773 profile= [KNL] Enable kernel profiling via /proc/profile
1774 Format: [schedule,]<number>
1775 Param: "schedule" - profile schedule points.
1776 Param: <number> - step/bucket size as a power of 2 for
1777 statistical time based profiling.
1778 Param: "sleep" - profile D-state sleeping (millisecs).
1779 Requires CONFIG_SCHEDSTATS
1780 Param: "kvm" - profile VM exits.
1782 processor.max_cstate= [HW,ACPI]
1783 Limit processor to maximum C-state
1784 max_cstate=9 overrides any DMI blacklist limit.
1786 processor.nocst [HW,ACPI]
1787 Ignore the _CST method to determine C-states,
1788 instead using the legacy FADT method
1790 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1792 See Documentation/blockdev/ramdisk.txt.
1794 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1795 probe for; one of (bare|imps|exps|lifebook|any).
1796 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1798 psmouse.resetafter= [HW,MOUSE]
1799 Try to reset the device after so many bad packets
1802 [HW,MOUSE] Set desired mouse resolution, in dpi.
1803 psmouse.smartscroll=
1804 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1805 0 = disabled, 1 = enabled (default).
1807 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1809 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1812 See Documentation/blockdev/paride.txt.
1815 [KNL] Number of legacy pty's. Overwrites compiled-in
1818 quiet [KNL] Disable most log messages
1823 See Documentation/md.txt.
1825 ramdisk_blocksize= [RAM]
1826 See Documentation/blockdev/ramdisk.txt.
1828 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1829 See Documentation/blockdev/ramdisk.txt.
1831 rcupdate.blimit= [KNL,BOOT]
1832 Set maximum number of finished RCU callbacks to process
1835 rcupdate.qhimark= [KNL,BOOT]
1836 Set threshold of queued
1837 RCU callbacks over which batch limiting is disabled.
1839 rcupdate.qlowmark= [KNL,BOOT]
1840 Set threshold of queued RCU callbacks below which
1841 batch limiting is re-enabled.
1845 Run specified binary instead of /init from the ramdisk,
1846 used for early userspace startup. See initrd.
1848 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1849 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1850 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1853 [KNL, SMP] Set scheduler's default relax_domain_level.
1854 See Documentation/cpusets.txt.
1856 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1858 reservetop= [X86-32]
1860 Reserves a hole at the top of the kernel virtual
1863 reset_devices [KNL] Force drivers to reset the underlying device
1864 during initialization.
1867 Specify the partition device for software suspend
1869 resume_offset= [SWSUSP]
1870 Specify the offset from the beginning of the partition
1871 given by "resume=" at which the swap header is located,
1872 in <PAGE_SIZE> units (needed only for swap files).
1873 See Documentation/power/swsusp-and-swap-files.txt
1875 retain_initrd [RAM] Keep initrd memory after extraction
1877 rhash_entries= [KNL,NET]
1878 Set number of hash buckets for route cache
1880 riscom8= [HW,SERIAL]
1881 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1883 ro [KNL] Mount root device read-only on boot
1885 root= [KNL] Root filesystem
1887 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1888 mount the root filesystem
1890 rootflags= [KNL] Set root filesystem mount option string
1892 rootfstype= [KNL] Set root filesystem type
1894 rootwait [KNL] Wait (indefinitely) for root device to show up.
1895 Useful for devices that are detected asynchronously
1896 (e.g. USB and MMC devices).
1898 root_plug.vendor_id=
1899 [ROOTPLUG] Override the default vendor ID
1901 root_plug.product_id=
1902 [ROOTPLUG] Override the default product ID
1905 [ROOTPLUG] Enable debugging output
1907 rw [KNL] Mount root device read-write on boot
1909 S [KNL] Run init in single mode
1912 See drivers/net/irda/sa1100_ir.c.
1914 sbni= [NET] Granch SBNI12 leased line adapter
1916 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1917 Format: <io>[,<timeout>[,<isapnp>]]
1919 scsi_debug_*= [SCSI]
1920 See drivers/scsi/scsi_debug.c.
1922 scsi_default_dev_flags=
1923 [SCSI] SCSI default device flags
1926 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1927 Format: <vendor>:<model>:<flags>
1928 (flags are integer value)
1930 scsi_logging_level= [SCSI] a bit mask of logging levels
1931 See drivers/scsi/scsi_logging.h for bits. Also
1932 settable via sysctl at dev.scsi.logging_level
1933 (/proc/sys/dev/scsi/logging_level).
1934 There is also a nice 'scsi_logging_level' script in the
1935 S390-tools package, available for download at
1936 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1938 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1939 discovered. async scans them in kernel threads,
1940 allowing boot to proceed. none ignores them, expecting
1941 user space to do the scan.
1943 selinux [SELINUX] Disable or enable SELinux at boot time.
1944 Format: { "0" | "1" }
1945 See security/selinux/Kconfig help text.
1948 Default value is set via kernel config option.
1949 If enabled at boot time, /selinux/disable can be used
1950 later to disable prior to initial policy load.
1952 selinux_compat_net =
1953 [SELINUX] Set initial selinux_compat_net flag value.
1954 Format: { "0" | "1" }
1955 0 -- use new secmark-based packet controls
1956 1 -- use legacy packet controls
1957 Default value is 0 (preferred).
1958 Value can be changed at runtime via
1959 /selinux/compat_net.
1961 serialnumber [BUGS=X86-32]
1964 Maximal number of shapers.
1966 show_msr= [x86] show boot-time MSR settings
1967 Format: { <integer> }
1968 Show boot-time (BIOS-initialized) MSR settings.
1969 The parameter means the number of CPUs to show,
1970 for example 1 means boot CPU only.
1973 See header of drivers/scsi/sim710.c.
1980 slub_debug[=options[,slabs]] [MM, SLUB]
1981 Enabling slub_debug allows one to determine the
1982 culprit if slab objects become corrupted. Enabling
1983 slub_debug can create guard zones around objects and
1984 may poison objects when not in use. Also tracks the
1985 last alloc / free. For more information see
1986 Documentation/vm/slub.txt.
1988 slub_max_order= [MM, SLUB]
1989 Determines the maximum allowed order for slabs.
1990 A high setting may cause OOMs due to memory
1991 fragmentation. For more information see
1992 Documentation/vm/slub.txt.
1994 slub_min_objects= [MM, SLUB]
1995 The minimum number of objects per slab. SLUB will
1996 increase the slab order up to slub_max_order to
1997 generate a sufficiently large slab able to contain
1998 the number of objects indicated. The higher the number
1999 of objects the smaller the overhead of tracking slabs
2000 and the less frequently locks need to be acquired.
2001 For more information see Documentation/vm/slub.txt.
2003 slub_min_order= [MM, SLUB]
2004 Determines the mininum page order for slabs. Must be
2005 lower than slub_max_order.
2006 For more information see Documentation/vm/slub.txt.
2008 slub_nomerge [MM, SLUB]
2009 Disable merging of slabs with similar size. May be
2010 necessary if there is some reason to distinguish
2011 allocs to different slabs. Debug options disable
2012 merging on their own.
2013 For more information see Documentation/vm/slub.txt.
2016 Format: <io1>[,<io2>[,...,<io8>]]
2018 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2019 attempt to substitute SMP alternatives once at boot.
2021 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2022 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2023 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2024 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2025 smsc-ircc2.ircc_irq= [HW] IRQ line
2026 smsc-ircc2.ircc_dma= [HW] DMA channel
2027 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2028 0: Toshiba Satellite 1800 (GP data pin select)
2029 1: Fast pin select (default)
2032 snd-ad1816a= [HW,ALSA]
2034 snd-ad1848= [HW,ALSA]
2036 snd-ali5451= [HW,ALSA]
2038 snd-als100= [HW,ALSA]
2040 snd-als4000= [HW,ALSA]
2042 snd-azt2320= [HW,ALSA]
2044 snd-cmi8330= [HW,ALSA]
2046 snd-cmipci= [HW,ALSA]
2048 snd-cs4231= [HW,ALSA]
2050 snd-cs4232= [HW,ALSA]
2052 snd-cs4236= [HW,ALSA]
2054 snd-cs4281= [HW,ALSA]
2056 snd-cs46xx= [HW,ALSA]
2058 snd-dt019x= [HW,ALSA]
2060 snd-dummy= [HW,ALSA]
2062 snd-emu10k1= [HW,ALSA]
2064 snd-ens1370= [HW,ALSA]
2066 snd-ens1371= [HW,ALSA]
2068 snd-es968= [HW,ALSA]
2070 snd-es1688= [HW,ALSA]
2072 snd-es18xx= [HW,ALSA]
2074 snd-es1938= [HW,ALSA]
2076 snd-es1968= [HW,ALSA]
2078 snd-fm801= [HW,ALSA]
2080 snd-gusclassic= [HW,ALSA]
2082 snd-gusextreme= [HW,ALSA]
2084 snd-gusmax= [HW,ALSA]
2088 snd-ice1712= [HW,ALSA]
2090 snd-intel8x0= [HW,ALSA]
2092 snd-interwave= [HW,ALSA]
2097 snd-korg1212= [HW,ALSA]
2099 snd-maestro3= [HW,ALSA]
2101 snd-mpu401= [HW,ALSA]
2103 snd-mtpav= [HW,ALSA]
2105 snd-nm256= [HW,ALSA]
2107 snd-opl3sa2= [HW,ALSA]
2115 snd-opti93x= [HW,ALSA]
2119 snd-rme32= [HW,ALSA]
2121 snd-rme96= [HW,ALSA]
2123 snd-rme9652= [HW,ALSA]
2129 snd-sbawe= [HW,ALSA]
2131 snd-serial= [HW,ALSA]
2133 snd-sgalaxy= [HW,ALSA]
2135 snd-sonicvibes= [HW,ALSA]
2140 snd-sun-cs4231= [HW,ALSA]
2142 snd-trident= [HW,ALSA]
2144 snd-usb-audio= [HW,ALSA,USB]
2146 snd-via82xx= [HW,ALSA]
2148 snd-virmidi= [HW,ALSA]
2150 snd-wavefront= [HW,ALSA]
2152 snd-ymfpci= [HW,ALSA]
2155 [KNL] Should the soft-lockup detector generate panics.
2157 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2158 See Documentation/sonypi.txt
2160 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2161 See Documentation/serial/specialix.txt.
2163 spia_io_base= [HW,MTD]
2169 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2171 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2172 See Documentation/scsi/st.txt.
2176 Set the STI (builtin display/keyboard on the HP-PARISC
2177 machines) console (graphic card) which should be used
2178 as the initial boot-console.
2179 See also comment in drivers/video/console/sticore.c.
2182 See comment in drivers/video/console/sticore.c.
2185 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2189 Control how the NFS server code allocates CPUs to
2190 service thread pools. Depending on how many NICs
2191 you have and where their interrupts are bound, this
2192 option will affect which CPUs will do NFS serving.
2193 Note: this parameter cannot be changed while the
2194 NFS server is running.
2196 auto the server chooses an appropriate mode
2197 automatically using heuristics
2198 global a single global pool contains all CPUs
2199 percpu one pool for each CPU
2200 pernode one pool for each NUMA node (equivalent
2201 to global on non-NUMA machines)
2203 swiotlb= [IA-64] Number of I/O TLB slabs
2207 sym53c416= [HW,SCSI]
2208 See header of drivers/scsi/sym53c416.c.
2210 sysrq_always_enabled
2212 Ignore sysrq setting - this boot parameter will
2213 neutralize any effect of /proc/sys/kernel/sysrq.
2214 Useful for debugging.
2217 See header of drivers/scsi/t128.c.
2221 test_suspend= [SUSPEND]
2222 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2223 standby suspend) as the system sleep state to briefly
2224 enter during system startup. The system is woken from
2225 this state using a wakeup-capable RTC alarm.
2227 thash_entries= [KNL,NET]
2228 Set number of hash buckets for TCP connection
2230 thermal.act= [HW,ACPI]
2231 -1: disable all active trip points in all thermal zones
2232 <degrees C>: override all lowest active trip points
2234 thermal.crt= [HW,ACPI]
2235 -1: disable all critical trip points in all thermal zones
2236 <degrees C>: override all critical trip points
2238 thermal.nocrt= [HW,ACPI]
2239 Set to disable actions on ACPI thermal zone
2240 critical and hot trip points.
2242 thermal.off= [HW,ACPI]
2243 1: disable ACPI thermal control
2245 thermal.psv= [HW,ACPI]
2246 -1: disable all passive trip points
2247 <degrees C>: override all passive trip points to this value
2249 thermal.tzp= [HW,ACPI]
2250 Specify global default ACPI thermal zone polling rate
2251 <deci-seconds>: poll all this frequency
2252 0: no polling (default)
2255 See comment before function dc390_setup() in
2256 drivers/scsi/tmscsim.c.
2260 Specify if the kernel should make use of the cpu
2261 topology informations if the hardware supports these.
2262 The scheduler will make use of these informations and
2263 e.g. base its process migration decisions on it.
2268 trix= [HW,OSS] MediaTrix AudioTrix Pro
2270 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2272 turbografx.map[2|3]= [HW,JOY]
2273 TurboGraFX parallel port interface
2275 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2276 See also Documentation/input/joystick-parport.txt
2278 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2279 See header of drivers/scsi/u14-34f.c.
2288 [USB] Ignore overcurrent events (default N).
2289 Some badly-designed motherboards generate lots of
2290 bogus events, for ports that aren't wired to
2291 anything. Set this parameter to avoid log spamming.
2292 Note that genuine overcurrent events won't be
2297 Set unknown_nmi_panic=1 early on boot.
2299 usbcore.autosuspend=
2300 [USB] The autosuspend time delay (in seconds) used
2301 for newly-detected USB devices (default 2). This
2302 is the time required before an idle device will be
2303 autosuspended. Devices for which the delay is set
2304 to a negative value won't be autosuspended at all.
2306 usbcore.usbfs_snoop=
2307 [USB] Set to log all usbfs traffic (default 0 = off).
2309 usbcore.blinkenlights=
2310 [USB] Set to cycle leds on hubs (default 0 = off).
2312 usbcore.old_scheme_first=
2313 [USB] Start with the old device initialization
2314 scheme (default 0 = off).
2316 usbcore.use_both_schemes=
2317 [USB] Try the other device initialization scheme
2318 if the first one fails (default 1 = enabled).
2320 usbcore.initial_descriptor_timeout=
2321 [USB] Specifies timeout for the initial 64-byte
2322 USB_REQ_GET_DESCRIPTOR request in milliseconds
2323 (default 5000 = 5.0 seconds).
2326 [USBHID] The interval which mice are to be polled at.
2328 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2329 kernel's map of available physical RAM.
2331 vdso= [X86-32,SH,x86-64]
2332 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2333 vdso=1: enable VDSO (default)
2334 vdso=0: disable VDSO mapping
2336 vdso32= [X86-32,X86-64]
2337 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2338 vdso32=1: enable 32-bit VDSO (default)
2339 vdso32=0: disable 32-bit VDSO mapping
2342 vector=percpu: enable percpu vector domain
2344 video= [FB] Frame buffer configuration
2345 See Documentation/fb/modedb.txt.
2347 vga= [BOOT,X86-32] Select a particular video mode
2348 See Documentation/x86/i386/boot.txt and
2349 Documentation/svga.txt.
2350 Use vga=ask for menu.
2351 This is actually a boot loader parameter; the value is
2352 passed to the kernel using a special protocol.
2354 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2355 size of <nn>. This can be used to increase the
2356 minimum size (128MB on x86). It can also be used to
2357 decrease the size and leave more room for directly
2360 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2363 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2366 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2369 waveartist= [HW,OSS]
2370 Format: <io>,<irq>,<dma>,<dma2>
2373 See header of drivers/scsi/wd33c93.c.
2376 See header of drivers/scsi/wd7000.c.
2379 See Documentation/watchdog/wdt.txt.
2381 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2382 xd_geo= See header of drivers/block/xd.c.
2384 xirc2ps_cs= [NET,PCMCIA]
2386 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2388 norandmaps Don't use address space randomization
2389 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2391 ______________________________________________________________________
2395 Add documentation for ALSA options.
2396 Add more DRM drivers.