4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 FTRACE Function tracing enabled.
93 TS Appropriate touchscreen support is enabled.
94 USB USB support is enabled.
95 USBHID USB Human Interface Device support is enabled.
96 V4L Video For Linux support is enabled.
97 VGA The VGA console has been enabled.
98 VT Virtual terminal support is enabled.
99 WDT Watchdog support is enabled.
100 XT IBM PC/XT MFM hard disk support is enabled.
101 X86-32 X86-32, aka i386 architecture is enabled.
102 X86-64 X86-64 architecture is enabled.
103 More X86-64 boot options can be found in
104 Documentation/x86/x86_64/boot-options.txt .
105 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
107 In addition, the following text indicates that the option:
109 BUGS= Relates to possible processor bugs on the said processor.
110 KNL Is a kernel start-up parameter.
111 BOOT Is a boot loader parameter.
113 Parameters denoted with BOOT are actually interpreted by the boot
114 loader, and have no meaning to the kernel directly.
115 Do not modify the syntax of boot loader parameters without extreme
116 need or coordination with <Documentation/x86/i386/boot.txt>.
118 There are also arch-specific kernel-parameters not documented here.
119 See for example <Documentation/x86/x86_64/boot-options.txt>.
121 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
122 a trailing = on the name of any parameter states that that parameter will
123 be entered as an environment variable, whereas its absence indicates that
124 it will appear as a kernel argument readable via /proc/cmdline by programs
125 running once the system is up.
127 The number of kernel parameters is not limited, but the length of the
128 complete command line (parameters including spaces etc.) is limited to
129 a fixed number of characters. This limit depends on the architecture
130 and is between 256 and 4096 characters. It is defined in the file
131 ./include/asm/setup.h as COMMAND_LINE_SIZE.
134 acpi= [HW,ACPI,X86-64,i386]
135 Advanced Configuration and Power Interface
136 Format: { force | off | ht | strict | noirq }
137 force -- enable ACPI if default was off
138 off -- disable ACPI if default was on
139 noirq -- do not use ACPI for IRQ routing
140 ht -- run only enough ACPI to enable Hyper Threading
141 strict -- Be less tolerant of platforms that are not
142 strictly ACPI specification compliant.
144 See also Documentation/power/pm.txt, pci=noacpi
146 acpi_apic_instance= [ACPI, IOAPIC]
148 2: use 2nd APIC table, if available
149 1,0: use 1st APIC table
152 acpi_sleep= [HW,ACPI] Sleep options
153 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
154 See Documentation/power/video.txt for s3_bios and s3_mode.
155 s3_beep is for debugging; it makes the PC's speaker beep
156 as soon as the kernel's real-mode entry point is called.
157 s4_nohwsig prevents ACPI hardware signature from being
158 used during resume from hibernation.
159 old_ordering causes the ACPI 1.0 ordering of the _PTS
160 control method, wrt putting devices into low power
161 states, to be enforced (the ACPI 2.0 ordering of _PTS is
164 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
165 Format: { level | edge | high | low }
167 acpi_irq_balance [HW,ACPI]
168 ACPI will balance active IRQs
171 acpi_irq_nobalance [HW,ACPI]
172 ACPI will not move active IRQs (default)
175 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
177 Format: <irq>,<irq>...
179 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
180 Format: <irq>,<irq>...
182 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
184 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
185 Format: To spoof as Windows 98: ="Microsoft Windows"
187 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
188 acpi_osi="string1" # add string1 -- only one string
189 acpi_osi="!string2" # remove built-in string2
190 acpi_osi= # disable all strings
192 acpi_serialize [HW,ACPI] force serialization of AML methods
194 acpi_skip_timer_override [HW,ACPI]
195 Recognize and ignore IRQ0/pin2 Interrupt Override.
196 For broken nForce2 BIOS resulting in XT-PIC timer.
197 acpi_use_timer_override [HW,ACPI}
198 Use timer override. For some broken Nvidia NF5 boards
199 that require a timer override, but don't have
202 acpi_backlight= [HW,ACPI]
203 acpi_backlight=vendor
205 If set to vendor, prefer vendor specific driver
206 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
207 of the ACPI video.ko driver.
209 acpi_display_output= [HW,ACPI]
210 acpi_display_output=vendor
211 acpi_display_output=video
214 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
215 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
217 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
218 debug output. Bits in debug_layer correspond to a
219 _COMPONENT in an ACPI source file, e.g.,
220 #define _COMPONENT ACPI_PCI_COMPONENT
221 Bits in debug_level correspond to a level in
222 ACPI_DEBUG_PRINT statements, e.g.,
223 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
224 The debug_level mask defaults to "info". See
225 Documentation/acpi/debug.txt for more information about
226 debug layers and levels.
228 Enable processor driver info messages:
229 acpi.debug_layer=0x20000000
230 Enable PCI/PCI interrupt routing info messages:
231 acpi.debug_layer=0x400000
232 Enable AML "Debug" output, i.e., stores to the Debug
233 object while interpreting AML:
234 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
235 Enable all messages related to ACPI hardware:
236 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
238 Some values produce so much output that the system is
239 unusable. The "log_buf_len" parameter may be useful
240 if you need to capture more output.
242 acpi.power_nocheck= [HW,ACPI]
243 Format: 1/0 enable/disable the check of power state.
244 On some bogus BIOS the _PSC object/_STA object of
245 power resource can't return the correct device power
246 state. In such case it is unneccessary to check its
247 power state again in power transition.
248 1 : disable the power state check
250 acpi_pm_good [X86-32,X86-64]
251 Override the pmtimer bug detection: force the kernel
252 to assume that this machine's pmtimer latches its value
253 and always returns good values.
256 { off | try_unsupported }
257 off: disable AGP support
258 try_unsupported: try to drive unsupported chipsets
259 (may crash computer or cause data corruption)
261 enable_timer_pin_1 [i386,x86-64]
262 Enable PIN 1 of APIC timer
263 Can be useful to work around chipset bugs
264 (in particular on some ATI chipsets).
265 The kernel tries to set a reasonable default.
267 disable_timer_pin_1 [i386,x86-64]
268 Disable PIN 1 of APIC timer
269 Can be useful to work around chipset bugs.
272 Format: <io>,<irq>,<dma>,<dma2>,<type>
275 See header of drivers/scsi/advansys.c.
277 advwdt= [HW,WDT] Advantech WDT
278 Format: <iostart>,<iostop>
280 aedsp16= [HW,OSS] Audio Excel DSP 16
281 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
282 See also header of sound/oss/aedsp16.c.
285 See Documentation/scsi/aha152x.txt.
288 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
291 See Documentation/scsi/aic7xxx.txt.
294 See Documentation/scsi/aic79xx.txt.
296 amd_iommu= [HW,X86-84]
297 Pass parameters to the AMD IOMMU driver in the system.
299 isolate - enable device isolation (each device, as far
300 as possible, will get its own protection
302 share - put every device behind one IOMMU into the
303 same protection domain
304 fullflush - enable flushing of IO/TLB entries when
305 they are unmapped. Otherwise they are
306 flushed before they will be reused, which
309 amd_iommu_size= [HW,X86-64]
310 Define the size of the aperture for the AMD IOMMU
311 driver. Possible values are:
312 '32M', '64M' (default), '128M', '256M', '512M', '1G'
314 amijoy.map= [HW,JOY] Amiga joystick support
315 Map of devices attached to JOY0DAT and JOY1DAT
317 See also Documentation/kernel/input/joystick.txt
319 analog.map= [HW,JOY] Analog joystick and gamepad support
320 Specifies type or capabilities of an analog joystick
321 connected to one of 16 gameports
322 Format: <type1>,<type2>,..<type16>
325 Power management functions (SPARCstation-4/5 + deriv.)
327 Disable APC CPU standby support. SPARCstation-Fox does
328 not play well with APC CPU idle - disable it if you have
329 APC and your system crashes randomly.
331 apic= [APIC,i386] Advanced Programmable Interrupt Controller
332 Change the output verbosity whilst booting
333 Format: { quiet (default) | verbose | debug }
334 Change the amount of debugging information output
335 when initialising the APIC and IO-APIC components.
337 apm= [APM] Advanced Power Management
338 See header of arch/x86/kernel/apm_32.c.
340 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
341 Format: <io>,<irq>,<nodeID>
345 atarimouse= [HW,MOUSE] Atari Mouse
347 atascsi= [HW,SCSI] Atari SCSI
349 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
350 EzKey and similar keyboards
352 atkbd.reset= [HW] Reset keyboard during initialization
354 atkbd.set= [HW] Select keyboard code set
355 Format: <int> (2 = AT (default), 3 = PS/2)
357 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
360 atkbd.softraw= [HW] Choose between synthetic and real raw mode
361 Format: <bool> (0 = real, 1 = synthetic (default))
363 atkbd.softrepeat= [HW]
364 Use software keyboard repeat
368 baycom_epp= [HW,AX25]
371 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
373 See header of drivers/net/hamradio/baycom_par.c.
375 baycom_ser_fdx= [HW,AX25]
376 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
377 Format: <io>,<irq>,<mode>[,<baud>]
378 See header of drivers/net/hamradio/baycom_ser_fdx.c.
380 baycom_ser_hdx= [HW,AX25]
381 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
382 Format: <io>,<irq>,<mode>
383 See header of drivers/net/hamradio/baycom_ser_hdx.c.
385 boot_delay= Milliseconds to delay each printk during boot.
386 Values larger than 10 seconds (10000) are changed to
390 bootmem_debug [KNL] Enable bootmem allocator debug messages.
392 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
393 bttv.radio= Most important insmod options are available as
395 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
396 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
399 See drivers/scsi/BusLogic.c, comment before function
400 BusLogic_ParseDriverOptions().
402 c101= [NET] Moxa C101 synchronous serial card
404 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
405 Sometimes CPU hardware bugs make them report the cache
406 size incorrectly. The kernel will attempt work arounds
407 to fix known problems, but for some CPUs it is not
408 possible to determine what the correct size should be.
409 This option provides an override for these situations.
411 security= [SECURITY] Choose a security module to enable at boot.
412 If this boot parameter is not specified, only the first
413 security module asking for security registration will be
414 loaded. An invalid security module name will be treated
415 as if no module has been chosen.
418 [SECURITY] Disable capabilities. This would normally
419 be used only if an alternative security model is to be
420 configured. Potentially dangerous and should only be
421 used if you are entirely sure of the consequences.
423 ccw_timeout_log [S390]
424 See Documentation/s390/CommonIO for details.
426 cgroup_disable= [KNL] Disable a particular controller
427 Format: {name of the controller(s) to disable}
428 {Currently supported controllers - "memory"}
430 checkreqprot [SELINUX] Set initial checkreqprot flag value.
431 Format: { "0" | "1" }
432 See security/selinux/Kconfig help text.
433 0 -- check protection applied by kernel (includes
434 any implied execute protection).
435 1 -- check protection requested by application.
436 Default value is set via a kernel config option.
437 Value can be changed at runtime via
438 /selinux/checkreqprot.
441 See Documentation/s390/CommonIO for details.
443 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
445 Forces specified clocksource (if available) to be used
446 when calculating gettimeofday(). If specified
447 clocksource is not available, it defaults to PIT.
448 Format: { pit | tsc | cyclone | pmtmr }
450 clocksource= [GENERIC_TIME] Override the default clocksource
452 Override the default clocksource and use the clocksource
453 with the name specified.
454 Some clocksource names to choose from, depending on
456 [all] jiffies (this is the base, fallback clocksource)
458 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
459 pxa_timer,timer3,32k_counter,timer0_1
461 [X86-32] pit,hpet,tsc,vmi-timer;
462 scx200_hrt on Geode; cyclone on IBM x440
470 clearcpuid=BITNUM [X86]
471 Disable CPUID feature X for the kernel. See
472 include/asm-x86/cpufeature.h for the valid bit numbers.
473 Note the Linux specific bits are not necessarily
474 stable over kernel options, but the vendor specific
476 Also note that user programs calling CPUID directly
477 or using the feature without checking anything
478 will still see it. This just prevents it from
479 being used by the kernel or shown in /proc/cpuinfo.
480 Also note the kernel might malfunction if you disable
483 code_bytes [IA32/X86_64] How many bytes of object code to print
488 hpet= [X86-32,HPET] option to control HPET usage
489 Format: { enable (default) | disable | force }
490 disable: disable HPET and use PIT instead
491 force: allow force enabled of undocumented chips (ICH4,
494 com20020= [HW,NET] ARCnet - COM20020 chipset
496 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
498 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
502 ARCnet - COM90xx chipset (memory-mapped buffers)
503 Format: <io>[,<irq>[,<memstart>]]
505 condev= [HW,S390] console device
508 console= [KNL] Output console device and options.
510 tty<n> Use the virtual console device <n>.
514 Use the specified serial port. The options are of
515 the form "bbbbpnf", where "bbbb" is the baud rate,
516 "p" is parity ("n", "o", or "e"), "n" is number of
517 bits, and "f" is flow control ("r" for RTS or
518 omit it). Default is "9600n8".
520 See Documentation/serial-console.txt for more
522 Documentation/networking/netconsole.txt for an
525 uart[8250],io,<addr>[,options]
526 uart[8250],mmio,<addr>[,options]
527 Start an early, polled-mode console on the 8250/16550
528 UART at the specified I/O port or MMIO address,
529 switching to the matching ttyS device later. The
530 options are the same as for ttyS, above.
532 If the device connected to the port is not a TTY but a braille
533 device, prepend "brl," before the device type, for instance
535 For now, only VisioBraille is supported.
537 earlycon= [KNL] Output early console device and options.
538 uart[8250],io,<addr>[,options]
539 uart[8250],mmio,<addr>[,options]
540 Start an early, polled-mode console on the 8250/16550
541 UART at the specified I/O port or MMIO address.
542 The options are the same as for ttyS, above.
545 [HW] Never suspend the console
546 Disable suspending of consoles during suspend and
547 hibernate operations. Once disabled, debugging
548 messages can reach various consoles while the rest
549 of the system is being put to sleep (ie, while
550 debugging driver suspend/resume hooks). This may
551 not work reliably with all consoles, but is known
552 to work with serial and VGA consoles.
554 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
556 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
558 crashkernel=nn[KMG]@ss[KMG]
559 [KNL] Reserve a chunk of physical memory to
560 hold a kernel to switch to with kexec on panic.
562 crashkernel=range1:size1[,range2:size2,...][@offset]
563 [KNL] Same as above, but depends on the memory
564 in the running system. The syntax of range is
565 start-[end] where start and end are both
566 a memory unit (amount[KMG]). See also
567 Documentation/kdump/kdump.txt for a example.
570 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
575 cs89x0_media= [HW,NET]
576 Format: { rj45 | aui | bnc }
579 See header of drivers/s390/block/dasd_devmap.c.
581 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
582 (one device per port)
583 Format: <port#>,<type>
584 See also Documentation/input/joystick-parport.txt
586 debug [KNL] Enable kernel debugging (events log level).
589 [KNL] verbose self-tests
591 Print debugging info while doing the locking API
593 We default to 0 (no extra messages), setting it to
594 1 will print _a lot_ more information - normally
595 only useful to kernel developers.
597 debug_objects [KNL] Enable object debugging
599 debugpat [X86] Enable PAT debugging
601 decnet.addr= [HW,NET]
602 Format: <area>[,<node>]
603 See also Documentation/networking/decnet.txt.
606 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
607 Change the default blue palette of the console.
608 This is a 16-member array composed of values
612 Format: <green0>,<green1>,<green2>,...,<green15>
613 Change the default green palette of the console.
614 This is a 16-member array composed of values
618 Format: <red0>,<red1>,<red2>,...,<red15>
619 Change the default red palette of the console.
620 This is a 16-member array composed of values
626 Set system-wide default UTF-8 mode for all tty's.
627 Default is 1, i.e. UTF-8 mode is enabled for all
628 newly opened terminals.
631 Set number of hash buckets for dentry cache.
634 IO parameters + enable/disable command.
636 digiepca= [HW,SERIAL]
637 See drivers/char/README.epca and
638 Documentation/serial/digiepca.txt.
640 disable_mtrr_cleanup [X86]
641 enable_mtrr_cleanup [X86]
642 The kernel tries to adjust MTRR layout from continuous
643 to discrete, to make X server driver able to add WB
644 entry later. This parameter enables/disables that.
646 mtrr_chunk_size=nn[KMG] [X86]
647 used for mtrr cleanup. It is largest continous chunk
648 that could hold holes aka. UC entries.
650 mtrr_gran_size=nn[KMG] [X86]
651 Used for mtrr cleanup. It is granularity of mtrr block.
653 Large value could prevent small alignment from
656 mtrr_spare_reg_nr=n [X86]
658 Range: 0,7 : spare reg number
660 Used for mtrr cleanup. It is spare mtrr entries number.
661 Set to 2 or more if your graphical card needs more.
663 disable_mtrr_trim [X86, Intel and AMD only]
664 By default the kernel will trim any uncacheable
665 memory out of your available memory pool based on
666 MTRR settings. This parameter disables that behavior,
667 possibly causing your machine to run very slowly.
669 dmasound= [HW,OSS] Sound subsystem buffers
675 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
677 earlyprintk=serial[,ttySn[,baudrate]]
680 Append ",keep" to not disable it when the real console
683 Only vga or serial or usb debug port at a time.
685 Currently only ttyS0 and ttyS1 are supported.
687 Interaction with the standard serial driver is not
690 The VGA output is eventually overwritten by the real
696 Format: {"off" | "on" | "skip[mbr]"}
698 eisa_irq_edge= [PARISC,HW]
699 See header of drivers/parisc/eisa.c.
702 See comment before function elanfreq_setup() in
703 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
706 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
707 See Documentation/block/as-iosched.txt and
708 Documentation/block/deadline-iosched.txt for details.
710 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
711 Specifies physical address of start of kernel core
712 image elf header. Generally kexec loader will
713 pass this option to capture kernel.
714 See Documentation/kdump/kdump.txt for details.
716 enforcing [SELINUX] Set initial enforcing status.
718 See security/selinux/Kconfig help text.
719 0 -- permissive (log only, no denials).
720 1 -- enforcing (deny and log).
722 Value can be changed at runtime via /selinux/enforce.
725 Format: <spdif>,[<nomix>,[<amplifier>]]
726 See also header of sound/oss/es1371.c.
728 ether= [HW,NET] Ethernet cards parameters
729 This option is obsoleted by the "netdev=" option, which
730 has equivalent usage. See its documentation for details.
732 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
737 fail_make_request=[KNL]
738 General fault injection mechanism.
739 Format: <interval>,<probability>,<space>,<times>
740 See also /Documentation/fault-injection/.
743 See header of drivers/scsi/fd_mcs.c.
746 See header of drivers/scsi/fdomain.c.
749 See Documentation/blockdev/floppy.txt.
751 force_pal_cache_flush
752 [IA-64] Avoid check_sal_cache_flush which may hang on
753 buggy SAL_CACHE_FLUSH implementations. Using this
754 parameter will force ia64_sal_cache_flush to call
755 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
758 [ftrace] will set and start the specified tracer
759 as early as possible in order to facilitate early
763 [ftrace] will dump the trace buffers on oops.
766 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
767 support via parallel port (up to 5 devices per port)
768 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
769 See also Documentation/input/joystick-parport.txt
773 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
778 See header of drivers/scsi/gdth.c.
780 gpt [EFI] Forces disk with valid GPT signature but
781 invalid Protective MBR to be treated as GPT.
785 hashdist= [KNL,NUMA] Large hashes allocated during boot
786 are distributed across NUMA nodes. Defaults on
787 for IA-64, off otherwise.
788 Format: 0 | 1 (for off | on)
790 hcl= [IA-64] SGI's Hardware Graph compatibility layer
792 hd= [EIDE] (E)IDE hard drive subsystem geometry
793 Format: <cyl>,<head>,<sect>
795 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
796 size of <nn>. This works even on boxes that have no
797 highmem otherwise. This also works to reduce highmem
798 size on bigger boxes.
800 highres= [KNL] Enable/disable high resolution timer mode.
801 Valid parameters: "on", "off"
805 See Documentation/isdn/README.HiSax.
807 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
808 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
809 On x86-64 and powerpc, this option can be specified
810 multiple times interleaved with hugepages= to reserve
811 huge pages of different sizes. Valid pages sizes on
812 x86-64 are 2M (when the CPU supports "pse") and 1G
813 (when the CPU supports the "pdpe1gb" cpuinfo flag)
814 Note that 1GB pages can only be allocated at boot time
815 using hugepages= and not freed afterwards.
817 [same as hugepagesz=] The size of the default
818 HugeTLB page size. This is the size represented by
819 the legacy /proc/ hugepages APIs, used for SHM, and
820 default size when mounting hugetlbfs filesystems.
821 Defaults to the default architecture's huge page size
826 i8042.debug [HW] Toggle i8042 debug mode
827 i8042.direct [HW] Put keyboard port into non-translated mode
828 i8042.dumbkbd [HW] Pretend that controller can only read data from
829 keyboard and cannot control its state
830 (Don't attempt to blink the leds)
831 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
832 i8042.nokbd [HW] Don't check/create keyboard port
833 i8042.noloop [HW] Disable the AUX Loopback command while probing
835 i8042.nomux [HW] Don't check presence of an active multiplexing
837 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
840 [HW] Frequency with which keyboard LEDs should blink
841 when kernel panics (default is 0.5 sec)
842 i8042.reset [HW] Reset the controller during init and cleanup
843 i8042.unlock [HW] Unlock (ignore) the keylock
847 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
848 indicates that the driver is running on unsupported
850 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
851 does not match list of supported models.
853 [HW] Report power status in /proc/i8k
854 (disabled by default)
855 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
858 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
859 See Documentation/mca.txt.
862 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
864 ide= [HW] (E)IDE subsystem
865 Format: ide=nodma or ide=doubler
866 See Documentation/ide/ide.txt.
868 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
869 See Documentation/ide/ide.txt.
872 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
873 Poll forces a polling idle loop that can slightly improves the performance
874 of waking up a idle CPU, but will use a lot of power and make the system
875 run hot. Not recommended.
876 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
877 to not use it because it doesn't save as much power as a normal idle
878 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
880 idle=halt. Halt is forced to be used for CPU idle.
881 In such case C2/C3 won't be used again.
882 idle=nomwait. Disable mwait for CPU C-states
884 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
885 Claim all unknown PCI IDE storage controllers.
887 ignore_loglevel [KNL]
888 Ignore loglevel setting - this will print /all/
889 kernel messages to the console. Useful for debugging.
892 Set number of hash buckets for inode cache.
895 See header of drivers/scsi/in2000.c.
899 Run specified binary instead of /sbin/init as init
902 initcall_debug [KNL] Trace initcalls as they are executed. Useful
903 for working out where the kernel is dying during
906 initrd= [BOOT] Specify the location of the initial ramdisk
908 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
926 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
928 Disable intel iommu driver.
929 igfx_off [Default Off]
930 By default, gfx is mapped as normal device. If a gfx
931 device has a dedicated DMAR unit, the DMAR unit is
932 bypassed by not enabling DMAR with this option. In
933 this case, gfx device will use physical address for
936 With this option iommu will not optimize to look
937 for io virtual address below 32 bit forcing dual
938 address cycle on pci bus for cards supporting greater
939 than 32 bit addressing. The default is to look
940 for translation below 32 bit and if not available
941 then look in the higher range.
943 With this option on every unmap_single operation will
944 result in a hardware IOTLB flush operation as opposed
945 to batching them for performance.
947 io_delay= [X86-32,X86-64] I/O delay method
949 Standard port 0x80 based delay
951 Alternate port 0xed based delay (needed on some systems)
953 Simple two microseconds delay
957 io7= [HW] IO7 for Marvel based alpha systems
958 See comment before marvel_specify_io7 in
959 arch/alpha/kernel/core_marvel.c.
962 See Documentation/filesystems/nfsroot.txt.
964 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
965 See comment before ip2_setup() in
966 drivers/char/ip2/ip2base.c.
968 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
969 See header of drivers/scsi/ips.c.
971 ports= [IP_VS_FTP] IPVS ftp helper module
973 Up to 8 (IP_VS_APP_MAX_PORTS) ports
975 Format: <port>,<port>....
978 When an interrupt is not handled search all handlers
979 for it. Intended to get systems with badly broken
983 When an interrupt is not handled search all handlers
984 for it. Also check all handlers each timer
985 interrupt. Intended to get systems with badly broken
989 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
991 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
993 <cpu number>,...,<cpu number>
995 <cpu number>-<cpu number>
996 (must be a positive range in ascending order)
998 <cpu number>,...,<cpu number>-<cpu number>
1000 This option can be used to specify one or more CPUs
1001 to isolate from the general SMP balancing and scheduling
1002 algorithms. You can move a process onto or off an
1003 "isolated" CPU via the CPU affinity syscalls or cpuset.
1004 <cpu number> begins at 0 and the maximum value is
1005 "number of CPUs in system - 1".
1007 This option is the preferred way to isolate CPUs. The
1008 alternative -- manually setting the CPU mask of all
1009 tasks in the system -- can cause problems and
1010 suboptimal load balancer performance.
1014 js= [HW,JOY] Analog joystick
1015 See Documentation/input/joystick.txt.
1017 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1018 specifies the amount of memory usable by the kernel
1019 for non-movable allocations. The requested amount is
1020 spread evenly throughout all nodes in the system. The
1021 remaining memory in each node is used for Movable
1022 pages. In the event, a node is too small to have both
1023 kernelcore and Movable pages, kernelcore pages will
1024 take priority and other nodes will have a larger number
1025 of kernelcore pages. The Movable zone is used for the
1026 allocation of pages that may be reclaimed or moved
1027 by the page migration subsystem. This means that
1028 HugeTLB pages may not be allocated from this zone.
1029 Note that allocations like PTEs-from-HighMem still
1030 use the HighMem zone if it exists, and the Normal
1031 zone if it does not.
1033 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1034 is similar to kernelcore except it specifies the
1035 amount of memory used for migratable allocations.
1036 If both kernelcore and movablecore is specified,
1037 then kernelcore will be at *least* the specified
1038 value but may be more. If movablecore on its own
1039 is specified, the administrator must be careful
1040 that the amount of memory usable for all allocations
1045 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1048 kgdboc= [HW] kgdb over consoles.
1049 Requires a tty driver that supports console polling.
1050 (only serial suported for now)
1051 Format: <serial_device>[,baud]
1053 kmac= [MIPS] korina ethernet MAC address.
1054 Configure the RouterBoard 532 series on-chip
1055 Ethernet adapter MAC address.
1061 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1064 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1067 libata.dma= [LIBATA] DMA control
1068 libata.dma=0 Disable all PATA and SATA DMA
1069 libata.dma=1 PATA and SATA Disk DMA only
1070 libata.dma=2 ATAPI (CDROM) DMA only
1071 libata.dma=4 Compact Flash DMA only
1072 Combinations also work, so libata.dma=3 enables DMA
1073 for disks and CDROMs, but not CFs.
1075 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1079 libata.force= [LIBATA] Force configurations. The format is comma
1080 separated list of "[ID:]VAL" where ID is
1081 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1082 matching port, link or device. Basically, it matches
1083 the ATA ID string printed on console by libata. If
1084 the whole ID part is omitted, the last PORT and DEVICE
1085 values are used. If ID hasn't been specified yet, the
1086 configuration applies to all ports, links and devices.
1088 If only DEVICE is omitted, the parameter applies to
1089 the port and all links and devices behind it. DEVICE
1090 number of 0 either selects the first device or the
1091 first fan-out link behind PMP device. It does not
1092 select the host link. DEVICE number of 15 selects the
1093 host link and device attached to it.
1095 The VAL specifies the configuration to force. As long
1096 as there's no ambiguity shortcut notation is allowed.
1097 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1098 The following configurations can be forced.
1100 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1101 Any ID with matching PORT is used.
1103 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1105 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1106 udma[/][16,25,33,44,66,100,133] notation is also
1109 * [no]ncq: Turn on or off NCQ.
1111 * nohrst, nosrst, norst: suppress hard, soft
1114 If there are multiple matching configurations changing
1115 the same attribute, the last one is used.
1117 load_ramdisk= [RAM] List of ramdisks to load from floppy
1118 See Documentation/blockdev/ramdisk.txt.
1120 lockd.nlm_grace_period=P [NFS] Assign grace period.
1123 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1126 lockd.nlm_timeout=T [NFS] Assign timeout value.
1129 lockd.nlm_udpport=M [NFS] Assign UDP port.
1132 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1135 loglevel= All Kernel Messages with a loglevel smaller than the
1136 console loglevel will be printed to the console. It can
1137 also be changed with klogd or other programs. The
1138 loglevels are defined as follows:
1140 0 (KERN_EMERG) system is unusable
1141 1 (KERN_ALERT) action must be taken immediately
1142 2 (KERN_CRIT) critical conditions
1143 3 (KERN_ERR) error conditions
1144 4 (KERN_WARNING) warning conditions
1145 5 (KERN_NOTICE) normal but significant condition
1146 6 (KERN_INFO) informational
1147 7 (KERN_DEBUG) debug-level messages
1149 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1150 Format: { n | nk | nM }
1151 n must be a power of two. The default size
1152 is set in the kernel config file.
1154 logo.nologo [FB] Disables display of the built-in Linux logo.
1155 This may be used to provide more screen space for
1156 kernel log messages and is useful when debugging
1157 kernel boot problems.
1159 lp=0 [LP] Specify parallel ports to use, e.g,
1160 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1161 lp=reset first parallel port). 'lp=0' disables the
1162 lp=auto printer driver. 'lp=reset' (which can be
1163 specified in addition to the ports) causes
1164 attached printers to be reset. Using
1165 lp=port1,port2,... specifies the parallel ports
1166 to associate lp devices with, starting with
1167 lp0. A port specification may be 'none' to skip
1168 that lp device, or a parport name such as
1169 'parport0'. Specifying 'lp=auto' instead of a
1170 port specification list means that device IDs
1171 from each port should be examined, to see if
1172 an IEEE 1284-compliant printer is attached; if
1173 so, the driver will manage that printer.
1174 See also header of drivers/char/lp.c.
1177 Sets loops_per_jiffy to given constant, thus avoiding
1178 time-consuming boot-time autodetection (up to 250 ms per
1179 CPU). 0 enables autodetection (default). To determine
1180 the correct value for your kernel, boot with normal
1181 autodetection and see what value is printed. Note that
1182 on SMP systems the preset will be applied to all CPUs,
1183 which is likely to cause problems if your CPUs need
1184 significantly divergent settings. An incorrect value
1185 will cause delays in the kernel to be wrong, leading to
1186 unpredictable I/O errors and other breakage. Although
1187 unlikely, in the extreme case this might damage your
1191 Format: <io>,<irq>,<dma>
1193 mac5380= [HW,SCSI] Format:
1194 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1196 machvec= [IA64] Force the use of a particular machine-vector
1197 (machvec) in a generic kernel.
1198 Example: machvec=hpzx1_swiotlb
1200 max_loop= [LOOP] Maximum number of loopback devices that can
1204 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1205 should make use of. maxcpus=n : n >= 0 limits the
1206 kernel to using 'n' processors. n=0 is a special case,
1207 it is equivalent to "nosmp", which also disables
1210 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1211 or equal to this physical address is ignored.
1213 max_luns= [SCSI] Maximum number of LUNs to probe.
1214 Should be between 1 and 2^32-1.
1217 [SCSI] Maximum number of LUNs received.
1218 Should be between 1 and 16384.
1222 mce [X86-32] Machine Check Exception
1224 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1226 md= [HW] RAID subsystems devices and level
1227 See Documentation/md.txt.
1230 Format: <first>,<last>
1231 Specifies range of consoles to be captured by the MDA.
1233 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1234 Amount of memory to be used when the kernel is not able
1235 to see the whole system memory or for test.
1236 [X86-32] Use together with memmap= to avoid physical
1237 address space collisions. Without memmap= PCI devices
1238 could be placed at addresses belonging to unused RAM.
1240 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1244 [KNL,SH] Allow user to override the default size for
1245 per-device physically contiguous DMA buffers.
1247 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1248 E820 memory map, as specified by the user.
1249 Such memmap=exactmap lines can be constructed based on
1250 BIOS output or other requirements. See the memmap=nn@ss
1253 memmap=nn[KMG]@ss[KMG]
1254 [KNL] Force usage of a specific region of memory
1255 Region of memory to be used, from ss to ss+nn.
1257 memmap=nn[KMG]#ss[KMG]
1258 [KNL,ACPI] Mark specific memory as ACPI data.
1259 Region of memory to be used, from ss to ss+nn.
1261 memmap=nn[KMG]$ss[KMG]
1262 [KNL,ACPI] Mark specific memory as reserved.
1263 Region of memory to be used, from ss to ss+nn.
1264 Example: Exclude memory from 0x18690000-0x1869ffff
1265 memmap=64K$0x18690000
1267 memmap=0x10000$0x18690000
1269 memory_corruption_check=0/1 [X86]
1270 Some BIOSes seem to corrupt the first 64k of
1271 memory when doing things like suspend/resume.
1272 Setting this option will scan the memory
1273 looking for corruption. Enabling this will
1274 both detect corruption and prevent the kernel
1275 from using the memory being corrupted.
1276 However, its intended as a diagnostic tool; if
1277 repeatable BIOS-originated corruption always
1278 affects the same memory, you can use memmap=
1279 to prevent the kernel from using that memory.
1281 memory_corruption_check_size=size [X86]
1282 By default it checks for corruption in the low
1283 64k, making this memory unavailable for normal
1284 use. Use this parameter to scan for
1285 corruption in more or less memory.
1287 memory_corruption_check_period=seconds [X86]
1288 By default it checks for corruption every 60
1289 seconds. Use this parameter to check at some
1290 other rate. 0 disables periodic checking.
1292 memtest= [KNL,X86] Enable memtest
1294 range: 0,4 : pattern number
1295 default : 0 <disable>
1297 meye.*= [HW] Set MotionEye Camera parameters
1298 See Documentation/video4linux/meye.txt.
1300 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1301 Multi-Function General Purpose Timers on AMD Geode
1304 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1305 the BIOS has incorrectly applied a workaround. TinyBIOS
1306 version 0.98 is known to be affected, 0.99 fixes the
1307 problem by letting the user disable the workaround.
1311 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1312 physical address is ignored.
1315 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1316 parameter allows control of the logging verbosity for
1317 the additional memory initialisation checks. A value
1318 of 0 disables mminit logging and a level of 4 will
1319 log everything. Information is printed at KERN_DEBUG
1320 so loglevel=8 may also need to be specified.
1323 [MOUSE] Maximum time between finger touching and
1324 leaving touchpad surface for touch to be considered
1325 a tap and be reported as a left button click (for
1326 touchpads working in absolute mode only).
1328 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1329 reporting absolute coordinates, such as tablets
1330 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1331 reporting absolute coordinates, such as tablets
1336 MTD_Partition= [MTD]
1337 Format: <name>,<region-number>,<size>,<offset>
1339 MTD_Region= [MTD] Format:
1340 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1343 See drivers/mtd/cmdlinepart.c.
1346 ARM/S3C2412 JIVE boot control
1348 See arch/arm/mach-s3c2412/mach-jive.c
1350 mtouchusb.raw_coordinates=
1351 [HW] Make the MicroTouch USB driver use raw coordinates
1352 ('y', default) or cooked coordinates ('n')
1354 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1357 See header of drivers/scsi/NCR_D700.c.
1361 ncr53c400= [HW,SCSI]
1363 ncr53c400a= [HW,SCSI]
1365 ncr53c406a= [HW,SCSI]
1367 ncr53c8xx= [HW,SCSI]
1369 netdev= [NET] Network devices parameters
1370 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1371 Note that mem_start is often overloaded to mean
1372 something different and driver-specific.
1373 This usage is only documented in each driver source
1377 [NETFILTER] Enable connection tracking flow accounting
1378 0 to disable accounting
1379 1 to enable accounting
1380 Default value depends on CONFIG_NF_CT_ACCT that is
1381 going to be removed in 2.6.29.
1384 See Documentation/filesystems/nfsroot.txt.
1386 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1387 See Documentation/filesystems/nfsroot.txt.
1389 nfs.callback_tcpport=
1390 [NFS] set the TCP port on which the NFSv4 callback
1391 channel should listen.
1393 nfs.idmap_cache_timeout=
1394 [NFS] set the maximum lifetime for idmapper cache
1398 [NFS] enable 64-bit inode numbers.
1399 If zero, the NFS client will fake up a 32-bit inode
1400 number for the readdir() and stat() syscalls instead
1401 of returning the full 64-bit number.
1402 The default is to return 64-bit inode numbers.
1404 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1405 when a NMI is triggered.
1406 Format: [state][,regs][,debounce][,die]
1408 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1410 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1411 emulation library even if a 387 maths coprocessor
1414 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1415 caches in the slab allocator. Saves per-node memory,
1416 but will impact performance.
1420 noapic [SMP,APIC] Tells the kernel to not make use of any
1421 IOAPICs that may be present in the system.
1423 nobats [PPC] Do not use BATs for mapping kernel lowmem
1424 on "Classic" PPC cores.
1428 nodelayacct [KNL] Disable per-task delay accounting
1430 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1432 nodsp [SH] Disable hardware DSP at boot time.
1434 noefi [X86-32,X86-64] Disable EFI runtime services support.
1438 noexec [X86-32,X86-64]
1439 On X86-32 available only on PAE configured kernels.
1440 noexec=on: enable non-executable mappings (default)
1441 noexec=off: disable non-executable mappings
1444 This affects only 32-bit executables.
1445 noexec32=on: enable non-executable mappings (default)
1446 read doesn't imply executable mappings
1447 noexec32=off: disable non-executable mappings
1448 read implies executable mappings
1450 nofpu [SH] Disable hardware FPU at boot time.
1452 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1453 register save and restore. The kernel will only save
1454 legacy floating-point registers on task switch.
1456 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1460 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1461 instruction doesn't work correctly and not to
1464 nohalt [IA-64] Tells the kernel not to use the power saving
1465 function PAL_HALT_LIGHT when idle. This increases
1466 power-consumption. On the positive side, it reduces
1467 interrupt wake-up latency, which may improve performance
1468 in certain environments such as networked servers or
1471 nohz= [KNL] Boottime enable/disable dynamic ticks
1472 Valid arguments: on, off
1475 noirqdebug [X86-32] Disables the code which attempts to detect and
1476 disable unhandled interrupt sources.
1478 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1479 broken timer IRQ sources.
1481 noisapnp [ISAPNP] Disables ISA PnP code.
1483 noinitrd [RAM] Tells the kernel not to load any configured
1488 nojitter [IA64] Disables jitter checking for ITC timers.
1490 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1492 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1494 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1496 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1497 default x2apic cluster mode on platforms
1500 noltlbs [PPC] Do not use large page/tlb entries for kernel
1501 lowmem mapping on PPC40x.
1503 nomca [IA-64] Disable machine check abort handling
1505 nomce [X86-32] Machine Check Exception
1507 nomfgpt [X86-32] Disable Multi-Function General Purpose
1508 Timer usage (for AMD Geode machines).
1510 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1512 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1513 with UP alternatives
1515 noresidual [PPC] Don't use residual data on PReP machines.
1517 noresume [SWSUSP] Disables resume and restores original swap
1520 no-scroll [VGA] Disables scrollback.
1521 This is required for the Braillex ib80-piezo Braille
1522 reader made by F.H. Papenmeier (Germany).
1526 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1528 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1529 and disable the IO APIC. legacy for "maxcpus=0".
1531 nosoftlockup [KNL] Disable the soft-lockup detector.
1533 nosync [HW,M68K] Disables sync negotiation for all devices.
1535 notsc [BUGS=X86-32] Disable Time Stamp Counter
1537 nousb [USB] Disable the USB subsystem
1541 nptcg= [IA64] Override max number of concurrent global TLB
1542 purges which is reported from either PAL_VM_SUMMARY or
1545 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1546 one of ['zone', 'node', 'default'] can be specified
1547 This can be set from sysctl after boot.
1548 See Documentation/sysctl/vm.txt for details.
1550 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1552 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1553 Rather than timing out after 20 ms if an EC
1554 command is not properly ACKed, override the length
1555 of the timeout. We have interrupts disabled while
1556 waiting for the ACK, so if this is set too high
1557 interrupts *may* be lost!
1562 oprofile.timer= [HW]
1563 Use timer interrupt instead of performance counters
1565 osst= [HW,SCSI] SCSI Tape Driver
1566 Format: <buffer_size>,<write_threshold>
1567 See also Documentation/scsi/st.txt.
1569 panic= [KNL] Kernel behaviour on panic
1572 parkbd.port= [HW] Parallel port number the keyboard adapter is
1573 connected to, default is 0.
1575 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1576 0 for XT, 1 for AT (default is AT).
1579 parport= [HW,PPT] Specify parallel ports. 0 disables.
1580 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1581 Use 'auto' to force the driver to use any
1582 IRQ/DMA settings detected (the default is to
1583 ignore detected IRQ/DMA settings because of
1584 possible conflicts). You can specify the base
1585 address, IRQ, and DMA settings; IRQ and DMA
1586 should be numbers, or 'auto' (for using detected
1587 settings on that particular port), or 'nofifo'
1588 (to avoid using a FIFO even if it is detected).
1589 Parallel ports are assigned in the order they
1590 are specified on the command line, starting
1593 parport_init_mode= [HW,PPT]
1594 Configure VIA parallel port to operate in
1595 a specific mode. This is necessary on Pegasos
1596 computer where firmware has no options for setting
1597 up parallel port mode and sets it to spp.
1598 Currently this function knows 686a and 8231 chips.
1599 Format: [spp|ps2|epp|ecp|ecpepp]
1601 pas2= [HW,OSS] Format:
1602 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1605 See header of drivers/scsi/pas16.c.
1608 Halt all CPUs after the first oops has been printed for
1609 the specified number of seconds. This is to be used if
1610 your oopses keep scrolling off the screen.
1615 See header of drivers/block/paride/pcd.c.
1616 See also Documentation/blockdev/paride.txt.
1618 pci=option[,option...] [PCI] various PCI subsystem options:
1619 off [X86] don't probe for the PCI bus
1620 bios [X86-32] force use of PCI BIOS, don't access
1621 the hardware directly. Use this if your machine
1622 has a non-standard PCI host bridge.
1623 nobios [X86-32] disallow use of PCI BIOS, only direct
1624 hardware access methods are allowed. Use this
1625 if you experience crashes upon bootup and you
1626 suspect they are caused by the BIOS.
1627 conf1 [X86] Force use of PCI Configuration
1629 conf2 [X86] Force use of PCI Configuration
1631 noaer [PCIE] If the PCIEAER kernel config parameter is
1632 enabled, this kernel boot option can be used to
1633 disable the use of PCIE advanced error reporting.
1634 nodomains [PCI] Disable support for multiple PCI
1635 root domains (aka PCI segments, in ACPI-speak).
1636 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1638 nomsi [MSI] If the PCI_MSI kernel config parameter is
1639 enabled, this kernel boot option can be used to
1640 disable the use of MSI interrupts system-wide.
1641 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1642 routing table. These calls are known to be buggy
1643 on several machines and they hang the machine
1644 when used, but on other computers it's the only
1645 way to get the interrupt routing table. Try
1646 this option if the kernel is unable to allocate
1647 IRQs or discover secondary PCI buses on your
1649 rom [X86] Assign address space to expansion ROMs.
1650 Use with caution as certain devices share
1651 address decoders between ROMs and other
1653 norom [X86] Do not assign address space to
1654 expansion ROMs that do not already have
1655 BIOS assigned address ranges.
1656 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1657 assigned automatically to PCI devices. You can
1658 make the kernel exclude IRQs of your ISA cards
1660 pirqaddr=0xAAAAA [X86] Specify the physical address
1661 of the PIRQ table (normally generated
1662 by the BIOS) if it is outside the
1663 F0000h-100000h range.
1664 lastbus=N [X86] Scan all buses thru bus #N. Can be
1665 useful if the kernel is unable to find your
1666 secondary buses and you want to tell it
1667 explicitly which ones they are.
1668 assign-busses [X86] Always assign all PCI bus
1669 numbers ourselves, overriding
1670 whatever the firmware may have done.
1671 usepirqmask [X86] Honor the possible IRQ mask stored
1672 in the BIOS $PIR table. This is needed on
1673 some systems with broken BIOSes, notably
1674 some HP Pavilion N5400 and Omnibook XE3
1675 notebooks. This will have no effect if ACPI
1676 IRQ routing is enabled.
1677 noacpi [X86] Do not use ACPI for IRQ routing
1678 or for PCI scanning.
1679 use_crs [X86] Use _CRS for PCI resource
1681 routeirq Do IRQ routing for all PCI devices.
1682 This is normally done in pci_enable_device(),
1683 so this option is a temporary workaround
1684 for broken drivers that don't call it.
1685 skip_isa_align [X86] do not align io start addr, so can
1686 handle more pci cards
1687 firmware [ARM] Do not re-enumerate the bus but instead
1688 just use the configuration from the
1689 bootloader. This is currently used on
1690 IXP2000 systems where the bus has to be
1691 configured a certain way for adjunct CPUs.
1692 noearly [X86] Don't do any early type 1 scanning.
1693 This might help on some broken boards which
1694 machine check when some devices' config space
1695 is read. But various workarounds are disabled
1696 and some IOMMU drivers will not work.
1697 bfsort Sort PCI devices into breadth-first order.
1698 This sorting is done to get a device
1699 order compatible with older (<= 2.4) kernels.
1700 nobfsort Don't sort PCI devices into breadth-first order.
1701 cbiosize=nn[KMG] The fixed amount of bus space which is
1702 reserved for the CardBus bridge's IO window.
1703 The default value is 256 bytes.
1704 cbmemsize=nn[KMG] The fixed amount of bus space which is
1705 reserved for the CardBus bridge's memory
1706 window. The default value is 64 megabytes.
1708 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1711 force Enable ASPM even on devices that claim not to support it.
1712 WARNING: Forcing ASPM on may cause system lockups.
1714 pcmv= [HW,PCMCIA] BadgePAD 4
1717 See Documentation/blockdev/paride.txt.
1719 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1722 See arch/parisc/kernel/pdc_chassis.c
1725 See Documentation/blockdev/paride.txt.
1728 See Documentation/blockdev/paride.txt.
1730 pirq= [SMP,APIC] Manual mp-table setup
1731 See Documentation/x86/i386/IO-APIC.txt.
1733 plip= [PPT,NET] Parallel port network link
1734 Format: { parport<nr> | timid | 0 }
1735 See also Documentation/parport.txt.
1737 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1738 Override pmtimer IOPort with a hex value.
1742 Enable PNP debug messages. This depends on the
1743 CONFIG_PNP_DEBUG_MESSAGES option.
1749 { on | off | curr | res | no-curr | no-res }
1752 [ISAPNP] Exclude IRQs for the autoconfiguration
1755 [ISAPNP] Exclude DMAs for the autoconfiguration
1757 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1758 Ranges are in pairs (I/O port base and size).
1761 [ISAPNP] Exclude memory regions for the
1763 Ranges are in pairs (memory base and size).
1766 Enables pr_debug()/dev_dbg() calls if
1767 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1768 be switched on/off via <debugfs>/dynamic_printk/modules
1770 print-fatal-signals=
1771 [KNL] debug: print fatal signals
1772 print-fatal-signals=1: print segfault info to
1776 printk.time= Show timing data prefixed to each printk message line
1777 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1779 profile= [KNL] Enable kernel profiling via /proc/profile
1780 Format: [schedule,]<number>
1781 Param: "schedule" - profile schedule points.
1782 Param: <number> - step/bucket size as a power of 2 for
1783 statistical time based profiling.
1784 Param: "sleep" - profile D-state sleeping (millisecs).
1785 Requires CONFIG_SCHEDSTATS
1786 Param: "kvm" - profile VM exits.
1788 processor.max_cstate= [HW,ACPI]
1789 Limit processor to maximum C-state
1790 max_cstate=9 overrides any DMI blacklist limit.
1792 processor.nocst [HW,ACPI]
1793 Ignore the _CST method to determine C-states,
1794 instead using the legacy FADT method
1796 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1798 See Documentation/blockdev/ramdisk.txt.
1800 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1801 probe for; one of (bare|imps|exps|lifebook|any).
1802 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1804 psmouse.resetafter= [HW,MOUSE]
1805 Try to reset the device after so many bad packets
1808 [HW,MOUSE] Set desired mouse resolution, in dpi.
1809 psmouse.smartscroll=
1810 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1811 0 = disabled, 1 = enabled (default).
1813 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1815 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1818 See Documentation/blockdev/paride.txt.
1821 [KNL] Number of legacy pty's. Overwrites compiled-in
1824 quiet [KNL] Disable most log messages
1829 See Documentation/md.txt.
1831 ramdisk_blocksize= [RAM]
1832 See Documentation/blockdev/ramdisk.txt.
1834 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1835 See Documentation/blockdev/ramdisk.txt.
1837 rcupdate.blimit= [KNL,BOOT]
1838 Set maximum number of finished RCU callbacks to process
1841 rcupdate.qhimark= [KNL,BOOT]
1842 Set threshold of queued
1843 RCU callbacks over which batch limiting is disabled.
1845 rcupdate.qlowmark= [KNL,BOOT]
1846 Set threshold of queued RCU callbacks below which
1847 batch limiting is re-enabled.
1851 Run specified binary instead of /init from the ramdisk,
1852 used for early userspace startup. See initrd.
1854 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1855 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1856 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1859 [KNL, SMP] Set scheduler's default relax_domain_level.
1860 See Documentation/cpusets.txt.
1862 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1864 reservetop= [X86-32]
1866 Reserves a hole at the top of the kernel virtual
1869 reset_devices [KNL] Force drivers to reset the underlying device
1870 during initialization.
1873 Specify the partition device for software suspend
1875 resume_offset= [SWSUSP]
1876 Specify the offset from the beginning of the partition
1877 given by "resume=" at which the swap header is located,
1878 in <PAGE_SIZE> units (needed only for swap files).
1879 See Documentation/power/swsusp-and-swap-files.txt
1881 retain_initrd [RAM] Keep initrd memory after extraction
1883 rhash_entries= [KNL,NET]
1884 Set number of hash buckets for route cache
1886 riscom8= [HW,SERIAL]
1887 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1889 ro [KNL] Mount root device read-only on boot
1891 root= [KNL] Root filesystem
1893 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1894 mount the root filesystem
1896 rootflags= [KNL] Set root filesystem mount option string
1898 rootfstype= [KNL] Set root filesystem type
1900 rootwait [KNL] Wait (indefinitely) for root device to show up.
1901 Useful for devices that are detected asynchronously
1902 (e.g. USB and MMC devices).
1904 root_plug.vendor_id=
1905 [ROOTPLUG] Override the default vendor ID
1907 root_plug.product_id=
1908 [ROOTPLUG] Override the default product ID
1911 [ROOTPLUG] Enable debugging output
1913 rw [KNL] Mount root device read-write on boot
1915 S [KNL] Run init in single mode
1918 See drivers/net/irda/sa1100_ir.c.
1920 sbni= [NET] Granch SBNI12 leased line adapter
1922 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1923 Format: <io>[,<timeout>[,<isapnp>]]
1925 scsi_debug_*= [SCSI]
1926 See drivers/scsi/scsi_debug.c.
1928 scsi_default_dev_flags=
1929 [SCSI] SCSI default device flags
1932 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1933 Format: <vendor>:<model>:<flags>
1934 (flags are integer value)
1936 scsi_logging_level= [SCSI] a bit mask of logging levels
1937 See drivers/scsi/scsi_logging.h for bits. Also
1938 settable via sysctl at dev.scsi.logging_level
1939 (/proc/sys/dev/scsi/logging_level).
1940 There is also a nice 'scsi_logging_level' script in the
1941 S390-tools package, available for download at
1942 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1944 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1945 discovered. async scans them in kernel threads,
1946 allowing boot to proceed. none ignores them, expecting
1947 user space to do the scan.
1949 selinux [SELINUX] Disable or enable SELinux at boot time.
1950 Format: { "0" | "1" }
1951 See security/selinux/Kconfig help text.
1954 Default value is set via kernel config option.
1955 If enabled at boot time, /selinux/disable can be used
1956 later to disable prior to initial policy load.
1958 selinux_compat_net =
1959 [SELINUX] Set initial selinux_compat_net flag value.
1960 Format: { "0" | "1" }
1961 0 -- use new secmark-based packet controls
1962 1 -- use legacy packet controls
1963 Default value is 0 (preferred).
1964 Value can be changed at runtime via
1965 /selinux/compat_net.
1967 serialnumber [BUGS=X86-32]
1970 Maximal number of shapers.
1972 show_msr= [x86] show boot-time MSR settings
1973 Format: { <integer> }
1974 Show boot-time (BIOS-initialized) MSR settings.
1975 The parameter means the number of CPUs to show,
1976 for example 1 means boot CPU only.
1979 See header of drivers/scsi/sim710.c.
1986 slub_debug[=options[,slabs]] [MM, SLUB]
1987 Enabling slub_debug allows one to determine the
1988 culprit if slab objects become corrupted. Enabling
1989 slub_debug can create guard zones around objects and
1990 may poison objects when not in use. Also tracks the
1991 last alloc / free. For more information see
1992 Documentation/vm/slub.txt.
1994 slub_max_order= [MM, SLUB]
1995 Determines the maximum allowed order for slabs.
1996 A high setting may cause OOMs due to memory
1997 fragmentation. For more information see
1998 Documentation/vm/slub.txt.
2000 slub_min_objects= [MM, SLUB]
2001 The minimum number of objects per slab. SLUB will
2002 increase the slab order up to slub_max_order to
2003 generate a sufficiently large slab able to contain
2004 the number of objects indicated. The higher the number
2005 of objects the smaller the overhead of tracking slabs
2006 and the less frequently locks need to be acquired.
2007 For more information see Documentation/vm/slub.txt.
2009 slub_min_order= [MM, SLUB]
2010 Determines the mininum page order for slabs. Must be
2011 lower than slub_max_order.
2012 For more information see Documentation/vm/slub.txt.
2014 slub_nomerge [MM, SLUB]
2015 Disable merging of slabs with similar size. May be
2016 necessary if there is some reason to distinguish
2017 allocs to different slabs. Debug options disable
2018 merging on their own.
2019 For more information see Documentation/vm/slub.txt.
2022 Format: <io1>[,<io2>[,...,<io8>]]
2024 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2025 attempt to substitute SMP alternatives once at boot.
2027 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2028 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2029 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2030 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2031 smsc-ircc2.ircc_irq= [HW] IRQ line
2032 smsc-ircc2.ircc_dma= [HW] DMA channel
2033 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2034 0: Toshiba Satellite 1800 (GP data pin select)
2035 1: Fast pin select (default)
2038 snd-ad1816a= [HW,ALSA]
2040 snd-ad1848= [HW,ALSA]
2042 snd-ali5451= [HW,ALSA]
2044 snd-als100= [HW,ALSA]
2046 snd-als4000= [HW,ALSA]
2048 snd-azt2320= [HW,ALSA]
2050 snd-cmi8330= [HW,ALSA]
2052 snd-cmipci= [HW,ALSA]
2054 snd-cs4231= [HW,ALSA]
2056 snd-cs4232= [HW,ALSA]
2058 snd-cs4236= [HW,ALSA]
2060 snd-cs4281= [HW,ALSA]
2062 snd-cs46xx= [HW,ALSA]
2064 snd-dt019x= [HW,ALSA]
2066 snd-dummy= [HW,ALSA]
2068 snd-emu10k1= [HW,ALSA]
2070 snd-ens1370= [HW,ALSA]
2072 snd-ens1371= [HW,ALSA]
2074 snd-es968= [HW,ALSA]
2076 snd-es1688= [HW,ALSA]
2078 snd-es18xx= [HW,ALSA]
2080 snd-es1938= [HW,ALSA]
2082 snd-es1968= [HW,ALSA]
2084 snd-fm801= [HW,ALSA]
2086 snd-gusclassic= [HW,ALSA]
2088 snd-gusextreme= [HW,ALSA]
2090 snd-gusmax= [HW,ALSA]
2094 snd-ice1712= [HW,ALSA]
2096 snd-intel8x0= [HW,ALSA]
2098 snd-interwave= [HW,ALSA]
2103 snd-korg1212= [HW,ALSA]
2105 snd-maestro3= [HW,ALSA]
2107 snd-mpu401= [HW,ALSA]
2109 snd-mtpav= [HW,ALSA]
2111 snd-nm256= [HW,ALSA]
2113 snd-opl3sa2= [HW,ALSA]
2121 snd-opti93x= [HW,ALSA]
2125 snd-rme32= [HW,ALSA]
2127 snd-rme96= [HW,ALSA]
2129 snd-rme9652= [HW,ALSA]
2135 snd-sbawe= [HW,ALSA]
2137 snd-serial= [HW,ALSA]
2139 snd-sgalaxy= [HW,ALSA]
2141 snd-sonicvibes= [HW,ALSA]
2146 snd-sun-cs4231= [HW,ALSA]
2148 snd-trident= [HW,ALSA]
2150 snd-usb-audio= [HW,ALSA,USB]
2152 snd-via82xx= [HW,ALSA]
2154 snd-virmidi= [HW,ALSA]
2156 snd-wavefront= [HW,ALSA]
2158 snd-ymfpci= [HW,ALSA]
2161 [KNL] Should the soft-lockup detector generate panics.
2163 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2164 See Documentation/sonypi.txt
2166 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2167 See Documentation/serial/specialix.txt.
2169 spia_io_base= [HW,MTD]
2175 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2177 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2178 See Documentation/scsi/st.txt.
2181 Enabled the stack tracer on boot up.
2185 Set the STI (builtin display/keyboard on the HP-PARISC
2186 machines) console (graphic card) which should be used
2187 as the initial boot-console.
2188 See also comment in drivers/video/console/sticore.c.
2191 See comment in drivers/video/console/sticore.c.
2194 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2198 Control how the NFS server code allocates CPUs to
2199 service thread pools. Depending on how many NICs
2200 you have and where their interrupts are bound, this
2201 option will affect which CPUs will do NFS serving.
2202 Note: this parameter cannot be changed while the
2203 NFS server is running.
2205 auto the server chooses an appropriate mode
2206 automatically using heuristics
2207 global a single global pool contains all CPUs
2208 percpu one pool for each CPU
2209 pernode one pool for each NUMA node (equivalent
2210 to global on non-NUMA machines)
2212 swiotlb= [IA-64] Number of I/O TLB slabs
2216 sym53c416= [HW,SCSI]
2217 See header of drivers/scsi/sym53c416.c.
2219 sysrq_always_enabled
2221 Ignore sysrq setting - this boot parameter will
2222 neutralize any effect of /proc/sys/kernel/sysrq.
2223 Useful for debugging.
2226 See header of drivers/scsi/t128.c.
2230 test_suspend= [SUSPEND]
2231 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2232 standby suspend) as the system sleep state to briefly
2233 enter during system startup. The system is woken from
2234 this state using a wakeup-capable RTC alarm.
2236 thash_entries= [KNL,NET]
2237 Set number of hash buckets for TCP connection
2239 thermal.act= [HW,ACPI]
2240 -1: disable all active trip points in all thermal zones
2241 <degrees C>: override all lowest active trip points
2243 thermal.crt= [HW,ACPI]
2244 -1: disable all critical trip points in all thermal zones
2245 <degrees C>: override all critical trip points
2247 thermal.nocrt= [HW,ACPI]
2248 Set to disable actions on ACPI thermal zone
2249 critical and hot trip points.
2251 thermal.off= [HW,ACPI]
2252 1: disable ACPI thermal control
2254 thermal.psv= [HW,ACPI]
2255 -1: disable all passive trip points
2256 <degrees C>: override all passive trip points to this value
2258 thermal.tzp= [HW,ACPI]
2259 Specify global default ACPI thermal zone polling rate
2260 <deci-seconds>: poll all this frequency
2261 0: no polling (default)
2264 See comment before function dc390_setup() in
2265 drivers/scsi/tmscsim.c.
2269 trix= [HW,OSS] MediaTrix AudioTrix Pro
2271 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2273 turbografx.map[2|3]= [HW,JOY]
2274 TurboGraFX parallel port interface
2276 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2277 See also Documentation/input/joystick-parport.txt
2279 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2280 See header of drivers/scsi/u14-34f.c.
2289 [USB] Ignore overcurrent events (default N).
2290 Some badly-designed motherboards generate lots of
2291 bogus events, for ports that aren't wired to
2292 anything. Set this parameter to avoid log spamming.
2293 Note that genuine overcurrent events won't be
2298 Set unknown_nmi_panic=1 early on boot.
2300 usbcore.autosuspend=
2301 [USB] The autosuspend time delay (in seconds) used
2302 for newly-detected USB devices (default 2). This
2303 is the time required before an idle device will be
2304 autosuspended. Devices for which the delay is set
2305 to a negative value won't be autosuspended at all.
2307 usbcore.usbfs_snoop=
2308 [USB] Set to log all usbfs traffic (default 0 = off).
2310 usbcore.blinkenlights=
2311 [USB] Set to cycle leds on hubs (default 0 = off).
2313 usbcore.old_scheme_first=
2314 [USB] Start with the old device initialization
2315 scheme (default 0 = off).
2317 usbcore.use_both_schemes=
2318 [USB] Try the other device initialization scheme
2319 if the first one fails (default 1 = enabled).
2321 usbcore.initial_descriptor_timeout=
2322 [USB] Specifies timeout for the initial 64-byte
2323 USB_REQ_GET_DESCRIPTOR request in milliseconds
2324 (default 5000 = 5.0 seconds).
2327 [USBHID] The interval which mice are to be polled at.
2329 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2330 kernel's map of available physical RAM.
2332 vdso= [X86-32,SH,x86-64]
2333 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2334 vdso=1: enable VDSO (default)
2335 vdso=0: disable VDSO mapping
2337 vdso32= [X86-32,X86-64]
2338 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2339 vdso32=1: enable 32-bit VDSO (default)
2340 vdso32=0: disable 32-bit VDSO mapping
2343 vector=percpu: enable percpu vector domain
2345 video= [FB] Frame buffer configuration
2346 See Documentation/fb/modedb.txt.
2348 vga= [BOOT,X86-32] Select a particular video mode
2349 See Documentation/x86/i386/boot.txt and
2350 Documentation/svga.txt.
2351 Use vga=ask for menu.
2352 This is actually a boot loader parameter; the value is
2353 passed to the kernel using a special protocol.
2355 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2356 size of <nn>. This can be used to increase the
2357 minimum size (128MB on x86). It can also be used to
2358 decrease the size and leave more room for directly
2361 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2364 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2367 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2370 waveartist= [HW,OSS]
2371 Format: <io>,<irq>,<dma>,<dma2>
2374 See header of drivers/scsi/wd33c93.c.
2377 See header of drivers/scsi/wd7000.c.
2380 See Documentation/watchdog/wdt.txt.
2382 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2383 xd_geo= See header of drivers/block/xd.c.
2385 xirc2ps_cs= [NET,PCMCIA]
2387 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2389 norandmaps Don't use address space randomization
2390 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2392 ______________________________________________________________________
2396 Add documentation for ALSA options.
2397 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob