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.
142 rsdt -- prefer RSDT over (default) XSDT
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 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
759 support via parallel port (up to 5 devices per port)
760 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
761 See also Documentation/input/joystick-parport.txt
765 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
770 See header of drivers/scsi/gdth.c.
772 gpt [EFI] Forces disk with valid GPT signature but
773 invalid Protective MBR to be treated as GPT.
777 hashdist= [KNL,NUMA] Large hashes allocated during boot
778 are distributed across NUMA nodes. Defaults on
779 for IA-64, off otherwise.
780 Format: 0 | 1 (for off | on)
782 hcl= [IA-64] SGI's Hardware Graph compatibility layer
784 hd= [EIDE] (E)IDE hard drive subsystem geometry
785 Format: <cyl>,<head>,<sect>
787 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
788 size of <nn>. This works even on boxes that have no
789 highmem otherwise. This also works to reduce highmem
790 size on bigger boxes.
792 highres= [KNL] Enable/disable high resolution timer mode.
793 Valid parameters: "on", "off"
797 See Documentation/isdn/README.HiSax.
799 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
800 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
801 On x86-64 and powerpc, this option can be specified
802 multiple times interleaved with hugepages= to reserve
803 huge pages of different sizes. Valid pages sizes on
804 x86-64 are 2M (when the CPU supports "pse") and 1G
805 (when the CPU supports the "pdpe1gb" cpuinfo flag)
806 Note that 1GB pages can only be allocated at boot time
807 using hugepages= and not freed afterwards.
809 [same as hugepagesz=] The size of the default
810 HugeTLB page size. This is the size represented by
811 the legacy /proc/ hugepages APIs, used for SHM, and
812 default size when mounting hugetlbfs filesystems.
813 Defaults to the default architecture's huge page size
818 i8042.debug [HW] Toggle i8042 debug mode
819 i8042.direct [HW] Put keyboard port into non-translated mode
820 i8042.dumbkbd [HW] Pretend that controller can only read data from
821 keyboard and cannot control its state
822 (Don't attempt to blink the leds)
823 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
824 i8042.nokbd [HW] Don't check/create keyboard port
825 i8042.noloop [HW] Disable the AUX Loopback command while probing
827 i8042.nomux [HW] Don't check presence of an active multiplexing
829 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
832 [HW] Frequency with which keyboard LEDs should blink
833 when kernel panics (default is 0.5 sec)
834 i8042.reset [HW] Reset the controller during init and cleanup
835 i8042.unlock [HW] Unlock (ignore) the keylock
839 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
840 indicates that the driver is running on unsupported
842 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
843 does not match list of supported models.
845 [HW] Report power status in /proc/i8k
846 (disabled by default)
847 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
850 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
851 See Documentation/mca.txt.
854 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
856 ide= [HW] (E)IDE subsystem
857 Format: ide=nodma or ide=doubler
858 See Documentation/ide/ide.txt.
860 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
861 See Documentation/ide/ide.txt.
864 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
865 Poll forces a polling idle loop that can slightly improves the performance
866 of waking up a idle CPU, but will use a lot of power and make the system
867 run hot. Not recommended.
868 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
869 to not use it because it doesn't save as much power as a normal idle
870 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
872 idle=halt. Halt is forced to be used for CPU idle.
873 In such case C2/C3 won't be used again.
874 idle=nomwait. Disable mwait for CPU C-states
876 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
877 Claim all unknown PCI IDE storage controllers.
879 ignore_loglevel [KNL]
880 Ignore loglevel setting - this will print /all/
881 kernel messages to the console. Useful for debugging.
884 Set number of hash buckets for inode cache.
887 See header of drivers/scsi/in2000.c.
891 Run specified binary instead of /sbin/init as init
894 initcall_debug [KNL] Trace initcalls as they are executed. Useful
895 for working out where the kernel is dying during
898 initrd= [BOOT] Specify the location of the initial ramdisk
900 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
918 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
920 Disable intel iommu driver.
921 igfx_off [Default Off]
922 By default, gfx is mapped as normal device. If a gfx
923 device has a dedicated DMAR unit, the DMAR unit is
924 bypassed by not enabling DMAR with this option. In
925 this case, gfx device will use physical address for
928 With this option iommu will not optimize to look
929 for io virtual address below 32 bit forcing dual
930 address cycle on pci bus for cards supporting greater
931 than 32 bit addressing. The default is to look
932 for translation below 32 bit and if not available
933 then look in the higher range.
935 With this option on every unmap_single operation will
936 result in a hardware IOTLB flush operation as opposed
937 to batching them for performance.
939 io_delay= [X86-32,X86-64] I/O delay method
941 Standard port 0x80 based delay
943 Alternate port 0xed based delay (needed on some systems)
945 Simple two microseconds delay
949 io7= [HW] IO7 for Marvel based alpha systems
950 See comment before marvel_specify_io7 in
951 arch/alpha/kernel/core_marvel.c.
954 See Documentation/filesystems/nfsroot.txt.
956 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
957 See comment before ip2_setup() in
958 drivers/char/ip2/ip2base.c.
960 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
961 See header of drivers/scsi/ips.c.
963 ports= [IP_VS_FTP] IPVS ftp helper module
965 Up to 8 (IP_VS_APP_MAX_PORTS) ports
967 Format: <port>,<port>....
970 When an interrupt is not handled search all handlers
971 for it. Intended to get systems with badly broken
975 When an interrupt is not handled search all handlers
976 for it. Also check all handlers each timer
977 interrupt. Intended to get systems with badly broken
981 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
983 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
985 <cpu number>,...,<cpu number>
987 <cpu number>-<cpu number>
988 (must be a positive range in ascending order)
990 <cpu number>,...,<cpu number>-<cpu number>
992 This option can be used to specify one or more CPUs
993 to isolate from the general SMP balancing and scheduling
994 algorithms. You can move a process onto or off an
995 "isolated" CPU via the CPU affinity syscalls or cpuset.
996 <cpu number> begins at 0 and the maximum value is
997 "number of CPUs in system - 1".
999 This option is the preferred way to isolate CPUs. The
1000 alternative -- manually setting the CPU mask of all
1001 tasks in the system -- can cause problems and
1002 suboptimal load balancer performance.
1006 js= [HW,JOY] Analog joystick
1007 See Documentation/input/joystick.txt.
1009 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1010 specifies the amount of memory usable by the kernel
1011 for non-movable allocations. The requested amount is
1012 spread evenly throughout all nodes in the system. The
1013 remaining memory in each node is used for Movable
1014 pages. In the event, a node is too small to have both
1015 kernelcore and Movable pages, kernelcore pages will
1016 take priority and other nodes will have a larger number
1017 of kernelcore pages. The Movable zone is used for the
1018 allocation of pages that may be reclaimed or moved
1019 by the page migration subsystem. This means that
1020 HugeTLB pages may not be allocated from this zone.
1021 Note that allocations like PTEs-from-HighMem still
1022 use the HighMem zone if it exists, and the Normal
1023 zone if it does not.
1025 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1026 is similar to kernelcore except it specifies the
1027 amount of memory used for migratable allocations.
1028 If both kernelcore and movablecore is specified,
1029 then kernelcore will be at *least* the specified
1030 value but may be more. If movablecore on its own
1031 is specified, the administrator must be careful
1032 that the amount of memory usable for all allocations
1037 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1040 kgdboc= [HW] kgdb over consoles.
1041 Requires a tty driver that supports console polling.
1042 (only serial suported for now)
1043 Format: <serial_device>[,baud]
1045 kmac= [MIPS] korina ethernet MAC address.
1046 Configure the RouterBoard 532 series on-chip
1047 Ethernet adapter MAC address.
1053 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1056 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1059 libata.dma= [LIBATA] DMA control
1060 libata.dma=0 Disable all PATA and SATA DMA
1061 libata.dma=1 PATA and SATA Disk DMA only
1062 libata.dma=2 ATAPI (CDROM) DMA only
1063 libata.dma=4 Compact Flash DMA only
1064 Combinations also work, so libata.dma=3 enables DMA
1065 for disks and CDROMs, but not CFs.
1067 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1071 libata.force= [LIBATA] Force configurations. The format is comma
1072 separated list of "[ID:]VAL" where ID is
1073 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1074 matching port, link or device. Basically, it matches
1075 the ATA ID string printed on console by libata. If
1076 the whole ID part is omitted, the last PORT and DEVICE
1077 values are used. If ID hasn't been specified yet, the
1078 configuration applies to all ports, links and devices.
1080 If only DEVICE is omitted, the parameter applies to
1081 the port and all links and devices behind it. DEVICE
1082 number of 0 either selects the first device or the
1083 first fan-out link behind PMP device. It does not
1084 select the host link. DEVICE number of 15 selects the
1085 host link and device attached to it.
1087 The VAL specifies the configuration to force. As long
1088 as there's no ambiguity shortcut notation is allowed.
1089 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1090 The following configurations can be forced.
1092 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1093 Any ID with matching PORT is used.
1095 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1097 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1098 udma[/][16,25,33,44,66,100,133] notation is also
1101 * [no]ncq: Turn on or off NCQ.
1103 * nohrst, nosrst, norst: suppress hard, soft
1106 If there are multiple matching configurations changing
1107 the same attribute, the last one is used.
1109 load_ramdisk= [RAM] List of ramdisks to load from floppy
1110 See Documentation/blockdev/ramdisk.txt.
1112 lockd.nlm_grace_period=P [NFS] Assign grace period.
1115 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1118 lockd.nlm_timeout=T [NFS] Assign timeout value.
1121 lockd.nlm_udpport=M [NFS] Assign UDP port.
1124 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1127 loglevel= All Kernel Messages with a loglevel smaller than the
1128 console loglevel will be printed to the console. It can
1129 also be changed with klogd or other programs. The
1130 loglevels are defined as follows:
1132 0 (KERN_EMERG) system is unusable
1133 1 (KERN_ALERT) action must be taken immediately
1134 2 (KERN_CRIT) critical conditions
1135 3 (KERN_ERR) error conditions
1136 4 (KERN_WARNING) warning conditions
1137 5 (KERN_NOTICE) normal but significant condition
1138 6 (KERN_INFO) informational
1139 7 (KERN_DEBUG) debug-level messages
1141 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1142 Format: { n | nk | nM }
1143 n must be a power of two. The default size
1144 is set in the kernel config file.
1146 logo.nologo [FB] Disables display of the built-in Linux logo.
1147 This may be used to provide more screen space for
1148 kernel log messages and is useful when debugging
1149 kernel boot problems.
1151 lp=0 [LP] Specify parallel ports to use, e.g,
1152 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1153 lp=reset first parallel port). 'lp=0' disables the
1154 lp=auto printer driver. 'lp=reset' (which can be
1155 specified in addition to the ports) causes
1156 attached printers to be reset. Using
1157 lp=port1,port2,... specifies the parallel ports
1158 to associate lp devices with, starting with
1159 lp0. A port specification may be 'none' to skip
1160 that lp device, or a parport name such as
1161 'parport0'. Specifying 'lp=auto' instead of a
1162 port specification list means that device IDs
1163 from each port should be examined, to see if
1164 an IEEE 1284-compliant printer is attached; if
1165 so, the driver will manage that printer.
1166 See also header of drivers/char/lp.c.
1169 Sets loops_per_jiffy to given constant, thus avoiding
1170 time-consuming boot-time autodetection (up to 250 ms per
1171 CPU). 0 enables autodetection (default). To determine
1172 the correct value for your kernel, boot with normal
1173 autodetection and see what value is printed. Note that
1174 on SMP systems the preset will be applied to all CPUs,
1175 which is likely to cause problems if your CPUs need
1176 significantly divergent settings. An incorrect value
1177 will cause delays in the kernel to be wrong, leading to
1178 unpredictable I/O errors and other breakage. Although
1179 unlikely, in the extreme case this might damage your
1183 Format: <io>,<irq>,<dma>
1185 mac5380= [HW,SCSI] Format:
1186 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1188 machvec= [IA64] Force the use of a particular machine-vector
1189 (machvec) in a generic kernel.
1190 Example: machvec=hpzx1_swiotlb
1192 max_loop= [LOOP] Maximum number of loopback devices that can
1196 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1197 should make use of. maxcpus=n : n >= 0 limits the
1198 kernel to using 'n' processors. n=0 is a special case,
1199 it is equivalent to "nosmp", which also disables
1202 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1203 or equal to this physical address is ignored.
1205 max_luns= [SCSI] Maximum number of LUNs to probe.
1206 Should be between 1 and 2^32-1.
1209 [SCSI] Maximum number of LUNs received.
1210 Should be between 1 and 16384.
1214 mce [X86-32] Machine Check Exception
1216 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1218 md= [HW] RAID subsystems devices and level
1219 See Documentation/md.txt.
1222 Format: <first>,<last>
1223 Specifies range of consoles to be captured by the MDA.
1225 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1226 Amount of memory to be used when the kernel is not able
1227 to see the whole system memory or for test.
1228 [X86-32] Use together with memmap= to avoid physical
1229 address space collisions. Without memmap= PCI devices
1230 could be placed at addresses belonging to unused RAM.
1232 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1236 [KNL,SH] Allow user to override the default size for
1237 per-device physically contiguous DMA buffers.
1239 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1240 E820 memory map, as specified by the user.
1241 Such memmap=exactmap lines can be constructed based on
1242 BIOS output or other requirements. See the memmap=nn@ss
1245 memmap=nn[KMG]@ss[KMG]
1246 [KNL] Force usage of a specific region of memory
1247 Region of memory to be used, from ss to ss+nn.
1249 memmap=nn[KMG]#ss[KMG]
1250 [KNL,ACPI] Mark specific memory as ACPI data.
1251 Region of memory to be used, from ss to ss+nn.
1253 memmap=nn[KMG]$ss[KMG]
1254 [KNL,ACPI] Mark specific memory as reserved.
1255 Region of memory to be used, from ss to ss+nn.
1256 Example: Exclude memory from 0x18690000-0x1869ffff
1257 memmap=64K$0x18690000
1259 memmap=0x10000$0x18690000
1261 memory_corruption_check=0/1 [X86]
1262 Some BIOSes seem to corrupt the first 64k of
1263 memory when doing things like suspend/resume.
1264 Setting this option will scan the memory
1265 looking for corruption. Enabling this will
1266 both detect corruption and prevent the kernel
1267 from using the memory being corrupted.
1268 However, its intended as a diagnostic tool; if
1269 repeatable BIOS-originated corruption always
1270 affects the same memory, you can use memmap=
1271 to prevent the kernel from using that memory.
1273 memory_corruption_check_size=size [X86]
1274 By default it checks for corruption in the low
1275 64k, making this memory unavailable for normal
1276 use. Use this parameter to scan for
1277 corruption in more or less memory.
1279 memory_corruption_check_period=seconds [X86]
1280 By default it checks for corruption every 60
1281 seconds. Use this parameter to check at some
1282 other rate. 0 disables periodic checking.
1284 memtest= [KNL,X86] Enable memtest
1286 range: 0,4 : pattern number
1287 default : 0 <disable>
1289 meye.*= [HW] Set MotionEye Camera parameters
1290 See Documentation/video4linux/meye.txt.
1292 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1293 Multi-Function General Purpose Timers on AMD Geode
1296 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1297 the BIOS has incorrectly applied a workaround. TinyBIOS
1298 version 0.98 is known to be affected, 0.99 fixes the
1299 problem by letting the user disable the workaround.
1303 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1304 physical address is ignored.
1307 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1308 parameter allows control of the logging verbosity for
1309 the additional memory initialisation checks. A value
1310 of 0 disables mminit logging and a level of 4 will
1311 log everything. Information is printed at KERN_DEBUG
1312 so loglevel=8 may also need to be specified.
1315 [MOUSE] Maximum time between finger touching and
1316 leaving touchpad surface for touch to be considered
1317 a tap and be reported as a left button click (for
1318 touchpads working in absolute mode only).
1320 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1321 reporting absolute coordinates, such as tablets
1322 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1323 reporting absolute coordinates, such as tablets
1328 MTD_Partition= [MTD]
1329 Format: <name>,<region-number>,<size>,<offset>
1331 MTD_Region= [MTD] Format:
1332 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1335 See drivers/mtd/cmdlinepart.c.
1338 ARM/S3C2412 JIVE boot control
1340 See arch/arm/mach-s3c2412/mach-jive.c
1342 mtouchusb.raw_coordinates=
1343 [HW] Make the MicroTouch USB driver use raw coordinates
1344 ('y', default) or cooked coordinates ('n')
1346 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1349 See header of drivers/scsi/NCR_D700.c.
1353 ncr53c400= [HW,SCSI]
1355 ncr53c400a= [HW,SCSI]
1357 ncr53c406a= [HW,SCSI]
1359 ncr53c8xx= [HW,SCSI]
1361 netdev= [NET] Network devices parameters
1362 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1363 Note that mem_start is often overloaded to mean
1364 something different and driver-specific.
1365 This usage is only documented in each driver source
1369 [NETFILTER] Enable connection tracking flow accounting
1370 0 to disable accounting
1371 1 to enable accounting
1372 Default value depends on CONFIG_NF_CT_ACCT that is
1373 going to be removed in 2.6.29.
1376 See Documentation/filesystems/nfsroot.txt.
1378 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1379 See Documentation/filesystems/nfsroot.txt.
1381 nfs.callback_tcpport=
1382 [NFS] set the TCP port on which the NFSv4 callback
1383 channel should listen.
1385 nfs.idmap_cache_timeout=
1386 [NFS] set the maximum lifetime for idmapper cache
1390 [NFS] enable 64-bit inode numbers.
1391 If zero, the NFS client will fake up a 32-bit inode
1392 number for the readdir() and stat() syscalls instead
1393 of returning the full 64-bit number.
1394 The default is to return 64-bit inode numbers.
1396 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1397 when a NMI is triggered.
1398 Format: [state][,regs][,debounce][,die]
1400 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1402 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1403 emulation library even if a 387 maths coprocessor
1406 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1407 caches in the slab allocator. Saves per-node memory,
1408 but will impact performance.
1412 noapic [SMP,APIC] Tells the kernel to not make use of any
1413 IOAPICs that may be present in the system.
1415 nobats [PPC] Do not use BATs for mapping kernel lowmem
1416 on "Classic" PPC cores.
1420 nodelayacct [KNL] Disable per-task delay accounting
1422 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1424 nodsp [SH] Disable hardware DSP at boot time.
1426 noefi [X86-32,X86-64] Disable EFI runtime services support.
1430 noexec [X86-32,X86-64]
1431 On X86-32 available only on PAE configured kernels.
1432 noexec=on: enable non-executable mappings (default)
1433 noexec=off: disable non-executable mappings
1436 This affects only 32-bit executables.
1437 noexec32=on: enable non-executable mappings (default)
1438 read doesn't imply executable mappings
1439 noexec32=off: disable non-executable mappings
1440 read implies executable mappings
1442 nofpu [SH] Disable hardware FPU at boot time.
1444 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1445 register save and restore. The kernel will only save
1446 legacy floating-point registers on task switch.
1448 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1452 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1453 instruction doesn't work correctly and not to
1456 nohalt [IA-64] Tells the kernel not to use the power saving
1457 function PAL_HALT_LIGHT when idle. This increases
1458 power-consumption. On the positive side, it reduces
1459 interrupt wake-up latency, which may improve performance
1460 in certain environments such as networked servers or
1463 nohz= [KNL] Boottime enable/disable dynamic ticks
1464 Valid arguments: on, off
1467 noirqdebug [X86-32] Disables the code which attempts to detect and
1468 disable unhandled interrupt sources.
1470 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1471 broken timer IRQ sources.
1473 noisapnp [ISAPNP] Disables ISA PnP code.
1475 noinitrd [RAM] Tells the kernel not to load any configured
1480 nojitter [IA64] Disables jitter checking for ITC timers.
1482 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1484 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1486 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1488 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1489 default x2apic cluster mode on platforms
1492 noltlbs [PPC] Do not use large page/tlb entries for kernel
1493 lowmem mapping on PPC40x.
1495 nomca [IA-64] Disable machine check abort handling
1497 nomce [X86-32] Machine Check Exception
1499 nomfgpt [X86-32] Disable Multi-Function General Purpose
1500 Timer usage (for AMD Geode machines).
1502 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1504 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1505 with UP alternatives
1507 noresidual [PPC] Don't use residual data on PReP machines.
1509 noresume [SWSUSP] Disables resume and restores original swap
1512 no-scroll [VGA] Disables scrollback.
1513 This is required for the Braillex ib80-piezo Braille
1514 reader made by F.H. Papenmeier (Germany).
1518 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1520 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1521 and disable the IO APIC. legacy for "maxcpus=0".
1523 nosoftlockup [KNL] Disable the soft-lockup detector.
1525 nosync [HW,M68K] Disables sync negotiation for all devices.
1527 notsc [BUGS=X86-32] Disable Time Stamp Counter
1529 nousb [USB] Disable the USB subsystem
1533 nptcg= [IA64] Override max number of concurrent global TLB
1534 purges which is reported from either PAL_VM_SUMMARY or
1537 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1538 one of ['zone', 'node', 'default'] can be specified
1539 This can be set from sysctl after boot.
1540 See Documentation/sysctl/vm.txt for details.
1542 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1544 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1545 Rather than timing out after 20 ms if an EC
1546 command is not properly ACKed, override the length
1547 of the timeout. We have interrupts disabled while
1548 waiting for the ACK, so if this is set too high
1549 interrupts *may* be lost!
1554 oprofile.timer= [HW]
1555 Use timer interrupt instead of performance counters
1557 osst= [HW,SCSI] SCSI Tape Driver
1558 Format: <buffer_size>,<write_threshold>
1559 See also Documentation/scsi/st.txt.
1561 panic= [KNL] Kernel behaviour on panic
1564 parkbd.port= [HW] Parallel port number the keyboard adapter is
1565 connected to, default is 0.
1567 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1568 0 for XT, 1 for AT (default is AT).
1571 parport= [HW,PPT] Specify parallel ports. 0 disables.
1572 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1573 Use 'auto' to force the driver to use any
1574 IRQ/DMA settings detected (the default is to
1575 ignore detected IRQ/DMA settings because of
1576 possible conflicts). You can specify the base
1577 address, IRQ, and DMA settings; IRQ and DMA
1578 should be numbers, or 'auto' (for using detected
1579 settings on that particular port), or 'nofifo'
1580 (to avoid using a FIFO even if it is detected).
1581 Parallel ports are assigned in the order they
1582 are specified on the command line, starting
1585 parport_init_mode= [HW,PPT]
1586 Configure VIA parallel port to operate in
1587 a specific mode. This is necessary on Pegasos
1588 computer where firmware has no options for setting
1589 up parallel port mode and sets it to spp.
1590 Currently this function knows 686a and 8231 chips.
1591 Format: [spp|ps2|epp|ecp|ecpepp]
1593 pas2= [HW,OSS] Format:
1594 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1597 See header of drivers/scsi/pas16.c.
1600 Halt all CPUs after the first oops has been printed for
1601 the specified number of seconds. This is to be used if
1602 your oopses keep scrolling off the screen.
1607 See header of drivers/block/paride/pcd.c.
1608 See also Documentation/blockdev/paride.txt.
1610 pci=option[,option...] [PCI] various PCI subsystem options:
1611 off [X86] don't probe for the PCI bus
1612 bios [X86-32] force use of PCI BIOS, don't access
1613 the hardware directly. Use this if your machine
1614 has a non-standard PCI host bridge.
1615 nobios [X86-32] disallow use of PCI BIOS, only direct
1616 hardware access methods are allowed. Use this
1617 if you experience crashes upon bootup and you
1618 suspect they are caused by the BIOS.
1619 conf1 [X86] Force use of PCI Configuration
1621 conf2 [X86] Force use of PCI Configuration
1623 noaer [PCIE] If the PCIEAER kernel config parameter is
1624 enabled, this kernel boot option can be used to
1625 disable the use of PCIE advanced error reporting.
1626 nodomains [PCI] Disable support for multiple PCI
1627 root domains (aka PCI segments, in ACPI-speak).
1628 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1630 nomsi [MSI] If the PCI_MSI kernel config parameter is
1631 enabled, this kernel boot option can be used to
1632 disable the use of MSI interrupts system-wide.
1633 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1634 routing table. These calls are known to be buggy
1635 on several machines and they hang the machine
1636 when used, but on other computers it's the only
1637 way to get the interrupt routing table. Try
1638 this option if the kernel is unable to allocate
1639 IRQs or discover secondary PCI buses on your
1641 rom [X86] Assign address space to expansion ROMs.
1642 Use with caution as certain devices share
1643 address decoders between ROMs and other
1645 norom [X86] Do not assign address space to
1646 expansion ROMs that do not already have
1647 BIOS assigned address ranges.
1648 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1649 assigned automatically to PCI devices. You can
1650 make the kernel exclude IRQs of your ISA cards
1652 pirqaddr=0xAAAAA [X86] Specify the physical address
1653 of the PIRQ table (normally generated
1654 by the BIOS) if it is outside the
1655 F0000h-100000h range.
1656 lastbus=N [X86] Scan all buses thru bus #N. Can be
1657 useful if the kernel is unable to find your
1658 secondary buses and you want to tell it
1659 explicitly which ones they are.
1660 assign-busses [X86] Always assign all PCI bus
1661 numbers ourselves, overriding
1662 whatever the firmware may have done.
1663 usepirqmask [X86] Honor the possible IRQ mask stored
1664 in the BIOS $PIR table. This is needed on
1665 some systems with broken BIOSes, notably
1666 some HP Pavilion N5400 and Omnibook XE3
1667 notebooks. This will have no effect if ACPI
1668 IRQ routing is enabled.
1669 noacpi [X86] Do not use ACPI for IRQ routing
1670 or for PCI scanning.
1671 use_crs [X86] Use _CRS for PCI resource
1673 routeirq Do IRQ routing for all PCI devices.
1674 This is normally done in pci_enable_device(),
1675 so this option is a temporary workaround
1676 for broken drivers that don't call it.
1677 skip_isa_align [X86] do not align io start addr, so can
1678 handle more pci cards
1679 firmware [ARM] Do not re-enumerate the bus but instead
1680 just use the configuration from the
1681 bootloader. This is currently used on
1682 IXP2000 systems where the bus has to be
1683 configured a certain way for adjunct CPUs.
1684 noearly [X86] Don't do any early type 1 scanning.
1685 This might help on some broken boards which
1686 machine check when some devices' config space
1687 is read. But various workarounds are disabled
1688 and some IOMMU drivers will not work.
1689 bfsort Sort PCI devices into breadth-first order.
1690 This sorting is done to get a device
1691 order compatible with older (<= 2.4) kernels.
1692 nobfsort Don't sort PCI devices into breadth-first order.
1693 cbiosize=nn[KMG] The fixed amount of bus space which is
1694 reserved for the CardBus bridge's IO window.
1695 The default value is 256 bytes.
1696 cbmemsize=nn[KMG] The fixed amount of bus space which is
1697 reserved for the CardBus bridge's memory
1698 window. The default value is 64 megabytes.
1700 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1703 force Enable ASPM even on devices that claim not to support it.
1704 WARNING: Forcing ASPM on may cause system lockups.
1706 pcmv= [HW,PCMCIA] BadgePAD 4
1709 See Documentation/blockdev/paride.txt.
1711 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1714 See arch/parisc/kernel/pdc_chassis.c
1717 See Documentation/blockdev/paride.txt.
1720 See Documentation/blockdev/paride.txt.
1722 pirq= [SMP,APIC] Manual mp-table setup
1723 See Documentation/x86/i386/IO-APIC.txt.
1725 plip= [PPT,NET] Parallel port network link
1726 Format: { parport<nr> | timid | 0 }
1727 See also Documentation/parport.txt.
1729 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1730 Override pmtimer IOPort with a hex value.
1734 Enable PNP debug messages. This depends on the
1735 CONFIG_PNP_DEBUG_MESSAGES option.
1741 { on | off | curr | res | no-curr | no-res }
1744 [ISAPNP] Exclude IRQs for the autoconfiguration
1747 [ISAPNP] Exclude DMAs for the autoconfiguration
1749 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1750 Ranges are in pairs (I/O port base and size).
1753 [ISAPNP] Exclude memory regions for the
1755 Ranges are in pairs (memory base and size).
1758 Enables pr_debug()/dev_dbg() calls if
1759 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1760 be switched on/off via <debugfs>/dynamic_printk/modules
1762 print-fatal-signals=
1763 [KNL] debug: print fatal signals
1764 print-fatal-signals=1: print segfault info to
1768 printk.time= Show timing data prefixed to each printk message line
1769 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1771 profile= [KNL] Enable kernel profiling via /proc/profile
1772 Format: [schedule,]<number>
1773 Param: "schedule" - profile schedule points.
1774 Param: <number> - step/bucket size as a power of 2 for
1775 statistical time based profiling.
1776 Param: "sleep" - profile D-state sleeping (millisecs).
1777 Requires CONFIG_SCHEDSTATS
1778 Param: "kvm" - profile VM exits.
1780 processor.max_cstate= [HW,ACPI]
1781 Limit processor to maximum C-state
1782 max_cstate=9 overrides any DMI blacklist limit.
1784 processor.nocst [HW,ACPI]
1785 Ignore the _CST method to determine C-states,
1786 instead using the legacy FADT method
1788 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1790 See Documentation/blockdev/ramdisk.txt.
1792 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1793 probe for; one of (bare|imps|exps|lifebook|any).
1794 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1796 psmouse.resetafter= [HW,MOUSE]
1797 Try to reset the device after so many bad packets
1800 [HW,MOUSE] Set desired mouse resolution, in dpi.
1801 psmouse.smartscroll=
1802 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1803 0 = disabled, 1 = enabled (default).
1805 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1807 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1810 See Documentation/blockdev/paride.txt.
1813 [KNL] Number of legacy pty's. Overwrites compiled-in
1816 quiet [KNL] Disable most log messages
1821 See Documentation/md.txt.
1823 ramdisk_blocksize= [RAM]
1824 See Documentation/blockdev/ramdisk.txt.
1826 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1827 See Documentation/blockdev/ramdisk.txt.
1829 rcupdate.blimit= [KNL,BOOT]
1830 Set maximum number of finished RCU callbacks to process
1833 rcupdate.qhimark= [KNL,BOOT]
1834 Set threshold of queued
1835 RCU callbacks over which batch limiting is disabled.
1837 rcupdate.qlowmark= [KNL,BOOT]
1838 Set threshold of queued RCU callbacks below which
1839 batch limiting is re-enabled.
1843 Run specified binary instead of /init from the ramdisk,
1844 used for early userspace startup. See initrd.
1846 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1847 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1848 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1851 [KNL, SMP] Set scheduler's default relax_domain_level.
1852 See Documentation/cpusets.txt.
1854 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1856 reservetop= [X86-32]
1858 Reserves a hole at the top of the kernel virtual
1861 reset_devices [KNL] Force drivers to reset the underlying device
1862 during initialization.
1865 Specify the partition device for software suspend
1867 resume_offset= [SWSUSP]
1868 Specify the offset from the beginning of the partition
1869 given by "resume=" at which the swap header is located,
1870 in <PAGE_SIZE> units (needed only for swap files).
1871 See Documentation/power/swsusp-and-swap-files.txt
1873 retain_initrd [RAM] Keep initrd memory after extraction
1875 rhash_entries= [KNL,NET]
1876 Set number of hash buckets for route cache
1878 riscom8= [HW,SERIAL]
1879 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1881 ro [KNL] Mount root device read-only on boot
1883 root= [KNL] Root filesystem
1885 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1886 mount the root filesystem
1888 rootflags= [KNL] Set root filesystem mount option string
1890 rootfstype= [KNL] Set root filesystem type
1892 rootwait [KNL] Wait (indefinitely) for root device to show up.
1893 Useful for devices that are detected asynchronously
1894 (e.g. USB and MMC devices).
1896 root_plug.vendor_id=
1897 [ROOTPLUG] Override the default vendor ID
1899 root_plug.product_id=
1900 [ROOTPLUG] Override the default product ID
1903 [ROOTPLUG] Enable debugging output
1905 rw [KNL] Mount root device read-write on boot
1907 S [KNL] Run init in single mode
1910 See drivers/net/irda/sa1100_ir.c.
1912 sbni= [NET] Granch SBNI12 leased line adapter
1914 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1915 Format: <io>[,<timeout>[,<isapnp>]]
1917 scsi_debug_*= [SCSI]
1918 See drivers/scsi/scsi_debug.c.
1920 scsi_default_dev_flags=
1921 [SCSI] SCSI default device flags
1924 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1925 Format: <vendor>:<model>:<flags>
1926 (flags are integer value)
1928 scsi_logging_level= [SCSI] a bit mask of logging levels
1929 See drivers/scsi/scsi_logging.h for bits. Also
1930 settable via sysctl at dev.scsi.logging_level
1931 (/proc/sys/dev/scsi/logging_level).
1932 There is also a nice 'scsi_logging_level' script in the
1933 S390-tools package, available for download at
1934 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1936 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1937 discovered. async scans them in kernel threads,
1938 allowing boot to proceed. none ignores them, expecting
1939 user space to do the scan.
1941 selinux [SELINUX] Disable or enable SELinux at boot time.
1942 Format: { "0" | "1" }
1943 See security/selinux/Kconfig help text.
1946 Default value is set via kernel config option.
1947 If enabled at boot time, /selinux/disable can be used
1948 later to disable prior to initial policy load.
1950 selinux_compat_net =
1951 [SELINUX] Set initial selinux_compat_net flag value.
1952 Format: { "0" | "1" }
1953 0 -- use new secmark-based packet controls
1954 1 -- use legacy packet controls
1955 Default value is 0 (preferred).
1956 Value can be changed at runtime via
1957 /selinux/compat_net.
1959 serialnumber [BUGS=X86-32]
1962 Maximal number of shapers.
1964 show_msr= [x86] show boot-time MSR settings
1965 Format: { <integer> }
1966 Show boot-time (BIOS-initialized) MSR settings.
1967 The parameter means the number of CPUs to show,
1968 for example 1 means boot CPU only.
1971 See header of drivers/scsi/sim710.c.
1978 slub_debug[=options[,slabs]] [MM, SLUB]
1979 Enabling slub_debug allows one to determine the
1980 culprit if slab objects become corrupted. Enabling
1981 slub_debug can create guard zones around objects and
1982 may poison objects when not in use. Also tracks the
1983 last alloc / free. For more information see
1984 Documentation/vm/slub.txt.
1986 slub_max_order= [MM, SLUB]
1987 Determines the maximum allowed order for slabs.
1988 A high setting may cause OOMs due to memory
1989 fragmentation. For more information see
1990 Documentation/vm/slub.txt.
1992 slub_min_objects= [MM, SLUB]
1993 The minimum number of objects per slab. SLUB will
1994 increase the slab order up to slub_max_order to
1995 generate a sufficiently large slab able to contain
1996 the number of objects indicated. The higher the number
1997 of objects the smaller the overhead of tracking slabs
1998 and the less frequently locks need to be acquired.
1999 For more information see Documentation/vm/slub.txt.
2001 slub_min_order= [MM, SLUB]
2002 Determines the mininum page order for slabs. Must be
2003 lower than slub_max_order.
2004 For more information see Documentation/vm/slub.txt.
2006 slub_nomerge [MM, SLUB]
2007 Disable merging of slabs with similar size. May be
2008 necessary if there is some reason to distinguish
2009 allocs to different slabs. Debug options disable
2010 merging on their own.
2011 For more information see Documentation/vm/slub.txt.
2014 Format: <io1>[,<io2>[,...,<io8>]]
2016 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2017 attempt to substitute SMP alternatives once at boot.
2019 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2020 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2021 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2022 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2023 smsc-ircc2.ircc_irq= [HW] IRQ line
2024 smsc-ircc2.ircc_dma= [HW] DMA channel
2025 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2026 0: Toshiba Satellite 1800 (GP data pin select)
2027 1: Fast pin select (default)
2030 snd-ad1816a= [HW,ALSA]
2032 snd-ad1848= [HW,ALSA]
2034 snd-ali5451= [HW,ALSA]
2036 snd-als100= [HW,ALSA]
2038 snd-als4000= [HW,ALSA]
2040 snd-azt2320= [HW,ALSA]
2042 snd-cmi8330= [HW,ALSA]
2044 snd-cmipci= [HW,ALSA]
2046 snd-cs4231= [HW,ALSA]
2048 snd-cs4232= [HW,ALSA]
2050 snd-cs4236= [HW,ALSA]
2052 snd-cs4281= [HW,ALSA]
2054 snd-cs46xx= [HW,ALSA]
2056 snd-dt019x= [HW,ALSA]
2058 snd-dummy= [HW,ALSA]
2060 snd-emu10k1= [HW,ALSA]
2062 snd-ens1370= [HW,ALSA]
2064 snd-ens1371= [HW,ALSA]
2066 snd-es968= [HW,ALSA]
2068 snd-es1688= [HW,ALSA]
2070 snd-es18xx= [HW,ALSA]
2072 snd-es1938= [HW,ALSA]
2074 snd-es1968= [HW,ALSA]
2076 snd-fm801= [HW,ALSA]
2078 snd-gusclassic= [HW,ALSA]
2080 snd-gusextreme= [HW,ALSA]
2082 snd-gusmax= [HW,ALSA]
2086 snd-ice1712= [HW,ALSA]
2088 snd-intel8x0= [HW,ALSA]
2090 snd-interwave= [HW,ALSA]
2095 snd-korg1212= [HW,ALSA]
2097 snd-maestro3= [HW,ALSA]
2099 snd-mpu401= [HW,ALSA]
2101 snd-mtpav= [HW,ALSA]
2103 snd-nm256= [HW,ALSA]
2105 snd-opl3sa2= [HW,ALSA]
2113 snd-opti93x= [HW,ALSA]
2117 snd-rme32= [HW,ALSA]
2119 snd-rme96= [HW,ALSA]
2121 snd-rme9652= [HW,ALSA]
2127 snd-sbawe= [HW,ALSA]
2129 snd-serial= [HW,ALSA]
2131 snd-sgalaxy= [HW,ALSA]
2133 snd-sonicvibes= [HW,ALSA]
2138 snd-sun-cs4231= [HW,ALSA]
2140 snd-trident= [HW,ALSA]
2142 snd-usb-audio= [HW,ALSA,USB]
2144 snd-via82xx= [HW,ALSA]
2146 snd-virmidi= [HW,ALSA]
2148 snd-wavefront= [HW,ALSA]
2150 snd-ymfpci= [HW,ALSA]
2153 [KNL] Should the soft-lockup detector generate panics.
2155 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2156 See Documentation/sonypi.txt
2158 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2159 See Documentation/serial/specialix.txt.
2161 spia_io_base= [HW,MTD]
2167 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2169 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2170 See Documentation/scsi/st.txt.
2174 Set the STI (builtin display/keyboard on the HP-PARISC
2175 machines) console (graphic card) which should be used
2176 as the initial boot-console.
2177 See also comment in drivers/video/console/sticore.c.
2180 See comment in drivers/video/console/sticore.c.
2183 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2187 Control how the NFS server code allocates CPUs to
2188 service thread pools. Depending on how many NICs
2189 you have and where their interrupts are bound, this
2190 option will affect which CPUs will do NFS serving.
2191 Note: this parameter cannot be changed while the
2192 NFS server is running.
2194 auto the server chooses an appropriate mode
2195 automatically using heuristics
2196 global a single global pool contains all CPUs
2197 percpu one pool for each CPU
2198 pernode one pool for each NUMA node (equivalent
2199 to global on non-NUMA machines)
2201 swiotlb= [IA-64] Number of I/O TLB slabs
2205 sym53c416= [HW,SCSI]
2206 See header of drivers/scsi/sym53c416.c.
2208 sysrq_always_enabled
2210 Ignore sysrq setting - this boot parameter will
2211 neutralize any effect of /proc/sys/kernel/sysrq.
2212 Useful for debugging.
2215 See header of drivers/scsi/t128.c.
2219 test_suspend= [SUSPEND]
2220 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2221 standby suspend) as the system sleep state to briefly
2222 enter during system startup. The system is woken from
2223 this state using a wakeup-capable RTC alarm.
2225 thash_entries= [KNL,NET]
2226 Set number of hash buckets for TCP connection
2228 thermal.act= [HW,ACPI]
2229 -1: disable all active trip points in all thermal zones
2230 <degrees C>: override all lowest active trip points
2232 thermal.crt= [HW,ACPI]
2233 -1: disable all critical trip points in all thermal zones
2234 <degrees C>: override all critical trip points
2236 thermal.nocrt= [HW,ACPI]
2237 Set to disable actions on ACPI thermal zone
2238 critical and hot trip points.
2240 thermal.off= [HW,ACPI]
2241 1: disable ACPI thermal control
2243 thermal.psv= [HW,ACPI]
2244 -1: disable all passive trip points
2245 <degrees C>: override all passive trip points to this value
2247 thermal.tzp= [HW,ACPI]
2248 Specify global default ACPI thermal zone polling rate
2249 <deci-seconds>: poll all this frequency
2250 0: no polling (default)
2253 See comment before function dc390_setup() in
2254 drivers/scsi/tmscsim.c.
2258 trix= [HW,OSS] MediaTrix AudioTrix Pro
2260 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2262 turbografx.map[2|3]= [HW,JOY]
2263 TurboGraFX parallel port interface
2265 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2266 See also Documentation/input/joystick-parport.txt
2268 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2269 See header of drivers/scsi/u14-34f.c.
2278 [USB] Ignore overcurrent events (default N).
2279 Some badly-designed motherboards generate lots of
2280 bogus events, for ports that aren't wired to
2281 anything. Set this parameter to avoid log spamming.
2282 Note that genuine overcurrent events won't be
2287 Set unknown_nmi_panic=1 early on boot.
2289 usbcore.autosuspend=
2290 [USB] The autosuspend time delay (in seconds) used
2291 for newly-detected USB devices (default 2). This
2292 is the time required before an idle device will be
2293 autosuspended. Devices for which the delay is set
2294 to a negative value won't be autosuspended at all.
2296 usbcore.usbfs_snoop=
2297 [USB] Set to log all usbfs traffic (default 0 = off).
2299 usbcore.blinkenlights=
2300 [USB] Set to cycle leds on hubs (default 0 = off).
2302 usbcore.old_scheme_first=
2303 [USB] Start with the old device initialization
2304 scheme (default 0 = off).
2306 usbcore.use_both_schemes=
2307 [USB] Try the other device initialization scheme
2308 if the first one fails (default 1 = enabled).
2310 usbcore.initial_descriptor_timeout=
2311 [USB] Specifies timeout for the initial 64-byte
2312 USB_REQ_GET_DESCRIPTOR request in milliseconds
2313 (default 5000 = 5.0 seconds).
2316 [USBHID] The interval which mice are to be polled at.
2318 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2319 kernel's map of available physical RAM.
2321 vdso= [X86-32,SH,x86-64]
2322 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2323 vdso=1: enable VDSO (default)
2324 vdso=0: disable VDSO mapping
2326 vdso32= [X86-32,X86-64]
2327 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2328 vdso32=1: enable 32-bit VDSO (default)
2329 vdso32=0: disable 32-bit VDSO mapping
2332 vector=percpu: enable percpu vector domain
2334 video= [FB] Frame buffer configuration
2335 See Documentation/fb/modedb.txt.
2337 vga= [BOOT,X86-32] Select a particular video mode
2338 See Documentation/x86/i386/boot.txt and
2339 Documentation/svga.txt.
2340 Use vga=ask for menu.
2341 This is actually a boot loader parameter; the value is
2342 passed to the kernel using a special protocol.
2344 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2345 size of <nn>. This can be used to increase the
2346 minimum size (128MB on x86). It can also be used to
2347 decrease the size and leave more room for directly
2350 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2353 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2356 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2359 waveartist= [HW,OSS]
2360 Format: <io>,<irq>,<dma>,<dma2>
2363 See header of drivers/scsi/wd33c93.c.
2366 See header of drivers/scsi/wd7000.c.
2369 See Documentation/watchdog/wdt.txt.
2371 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2372 xd_geo= See header of drivers/block/xd.c.
2374 xirc2ps_cs= [NET,PCMCIA]
2376 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2378 norandmaps Don't use address space randomization
2379 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2381 ______________________________________________________________________
2385 Add documentation for ALSA options.
2386 Add more DRM drivers.