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 See Documentation/acpi/debug.txt for more information
225 about debug layers and levels.
227 Enable AML "Debug" output, i.e., stores to the Debug
228 object while interpreting AML:
229 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
230 Enable PCI/PCI interrupt routing info messages:
231 acpi.debug_layer=0x400000 acpi.debug_level=0x4
232 Enable all messages related to ACPI hardware:
233 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
235 Some values produce so much output that the system is
236 unusable. The "log_buf_len" parameter may be useful
237 if you need to capture more output.
239 acpi.power_nocheck= [HW,ACPI]
240 Format: 1/0 enable/disable the check of power state.
241 On some bogus BIOS the _PSC object/_STA object of
242 power resource can't return the correct device power
243 state. In such case it is unneccessary to check its
244 power state again in power transition.
245 1 : disable the power state check
247 acpi_pm_good [X86-32,X86-64]
248 Override the pmtimer bug detection: force the kernel
249 to assume that this machine's pmtimer latches its value
250 and always returns good values.
253 { off | try_unsupported }
254 off: disable AGP support
255 try_unsupported: try to drive unsupported chipsets
256 (may crash computer or cause data corruption)
258 enable_timer_pin_1 [i386,x86-64]
259 Enable PIN 1 of APIC timer
260 Can be useful to work around chipset bugs
261 (in particular on some ATI chipsets).
262 The kernel tries to set a reasonable default.
264 disable_timer_pin_1 [i386,x86-64]
265 Disable PIN 1 of APIC timer
266 Can be useful to work around chipset bugs.
269 Format: <io>,<irq>,<dma>,<dma2>,<type>
272 See header of drivers/scsi/advansys.c.
274 advwdt= [HW,WDT] Advantech WDT
275 Format: <iostart>,<iostop>
277 aedsp16= [HW,OSS] Audio Excel DSP 16
278 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
279 See also header of sound/oss/aedsp16.c.
282 See Documentation/scsi/aha152x.txt.
285 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
288 See Documentation/scsi/aic7xxx.txt.
291 See Documentation/scsi/aic79xx.txt.
293 amd_iommu= [HW,X86-84]
294 Pass parameters to the AMD IOMMU driver in the system.
296 isolate - enable device isolation (each device, as far
297 as possible, will get its own protection
299 share - put every device behind one IOMMU into the
300 same protection domain
301 fullflush - enable flushing of IO/TLB entries when
302 they are unmapped. Otherwise they are
303 flushed before they will be reused, which
306 amd_iommu_size= [HW,X86-64]
307 Define the size of the aperture for the AMD IOMMU
308 driver. Possible values are:
309 '32M', '64M' (default), '128M', '256M', '512M', '1G'
311 amijoy.map= [HW,JOY] Amiga joystick support
312 Map of devices attached to JOY0DAT and JOY1DAT
314 See also Documentation/kernel/input/joystick.txt
316 analog.map= [HW,JOY] Analog joystick and gamepad support
317 Specifies type or capabilities of an analog joystick
318 connected to one of 16 gameports
319 Format: <type1>,<type2>,..<type16>
322 Power management functions (SPARCstation-4/5 + deriv.)
324 Disable APC CPU standby support. SPARCstation-Fox does
325 not play well with APC CPU idle - disable it if you have
326 APC and your system crashes randomly.
328 apic= [APIC,i386] Advanced Programmable Interrupt Controller
329 Change the output verbosity whilst booting
330 Format: { quiet (default) | verbose | debug }
331 Change the amount of debugging information output
332 when initialising the APIC and IO-APIC components.
334 apm= [APM] Advanced Power Management
335 See header of arch/x86/kernel/apm_32.c.
337 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
338 Format: <io>,<irq>,<nodeID>
342 atarimouse= [HW,MOUSE] Atari Mouse
344 atascsi= [HW,SCSI] Atari SCSI
346 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
347 EzKey and similar keyboards
349 atkbd.reset= [HW] Reset keyboard during initialization
351 atkbd.set= [HW] Select keyboard code set
352 Format: <int> (2 = AT (default), 3 = PS/2)
354 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
357 atkbd.softraw= [HW] Choose between synthetic and real raw mode
358 Format: <bool> (0 = real, 1 = synthetic (default))
360 atkbd.softrepeat= [HW]
361 Use software keyboard repeat
365 baycom_epp= [HW,AX25]
368 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
370 See header of drivers/net/hamradio/baycom_par.c.
372 baycom_ser_fdx= [HW,AX25]
373 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
374 Format: <io>,<irq>,<mode>[,<baud>]
375 See header of drivers/net/hamradio/baycom_ser_fdx.c.
377 baycom_ser_hdx= [HW,AX25]
378 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
379 Format: <io>,<irq>,<mode>
380 See header of drivers/net/hamradio/baycom_ser_hdx.c.
382 boot_delay= Milliseconds to delay each printk during boot.
383 Values larger than 10 seconds (10000) are changed to
387 bootmem_debug [KNL] Enable bootmem allocator debug messages.
389 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
390 bttv.radio= Most important insmod options are available as
392 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
393 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
396 See drivers/scsi/BusLogic.c, comment before function
397 BusLogic_ParseDriverOptions().
399 c101= [NET] Moxa C101 synchronous serial card
401 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
402 Sometimes CPU hardware bugs make them report the cache
403 size incorrectly. The kernel will attempt work arounds
404 to fix known problems, but for some CPUs it is not
405 possible to determine what the correct size should be.
406 This option provides an override for these situations.
408 security= [SECURITY] Choose a security module to enable at boot.
409 If this boot parameter is not specified, only the first
410 security module asking for security registration will be
411 loaded. An invalid security module name will be treated
412 as if no module has been chosen.
415 [SECURITY] Disable capabilities. This would normally
416 be used only if an alternative security model is to be
417 configured. Potentially dangerous and should only be
418 used if you are entirely sure of the consequences.
420 ccw_timeout_log [S390]
421 See Documentation/s390/CommonIO for details.
423 cgroup_disable= [KNL] Disable a particular controller
424 Format: {name of the controller(s) to disable}
425 {Currently supported controllers - "memory"}
427 checkreqprot [SELINUX] Set initial checkreqprot flag value.
428 Format: { "0" | "1" }
429 See security/selinux/Kconfig help text.
430 0 -- check protection applied by kernel (includes
431 any implied execute protection).
432 1 -- check protection requested by application.
433 Default value is set via a kernel config option.
434 Value can be changed at runtime via
435 /selinux/checkreqprot.
438 See Documentation/s390/CommonIO for details.
440 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
442 Forces specified clocksource (if available) to be used
443 when calculating gettimeofday(). If specified
444 clocksource is not available, it defaults to PIT.
445 Format: { pit | tsc | cyclone | pmtmr }
447 clocksource= [GENERIC_TIME] Override the default clocksource
449 Override the default clocksource and use the clocksource
450 with the name specified.
451 Some clocksource names to choose from, depending on
453 [all] jiffies (this is the base, fallback clocksource)
455 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
456 pxa_timer,timer3,32k_counter,timer0_1
458 [X86-32] pit,hpet,tsc,vmi-timer;
459 scx200_hrt on Geode; cyclone on IBM x440
467 clearcpuid=BITNUM [X86]
468 Disable CPUID feature X for the kernel. See
469 include/asm-x86/cpufeature.h for the valid bit numbers.
470 Note the Linux specific bits are not necessarily
471 stable over kernel options, but the vendor specific
473 Also note that user programs calling CPUID directly
474 or using the feature without checking anything
475 will still see it. This just prevents it from
476 being used by the kernel or shown in /proc/cpuinfo.
477 Also note the kernel might malfunction if you disable
480 code_bytes [IA32/X86_64] How many bytes of object code to print
485 hpet= [X86-32,HPET] option to control HPET usage
486 Format: { enable (default) | disable | force }
487 disable: disable HPET and use PIT instead
488 force: allow force enabled of undocumented chips (ICH4,
491 com20020= [HW,NET] ARCnet - COM20020 chipset
493 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
495 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
499 ARCnet - COM90xx chipset (memory-mapped buffers)
500 Format: <io>[,<irq>[,<memstart>]]
502 condev= [HW,S390] console device
505 console= [KNL] Output console device and options.
507 tty<n> Use the virtual console device <n>.
511 Use the specified serial port. The options are of
512 the form "bbbbpnf", where "bbbb" is the baud rate,
513 "p" is parity ("n", "o", or "e"), "n" is number of
514 bits, and "f" is flow control ("r" for RTS or
515 omit it). Default is "9600n8".
517 See Documentation/serial-console.txt for more
519 Documentation/networking/netconsole.txt for an
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address,
526 switching to the matching ttyS device later. The
527 options are the same as for ttyS, above.
529 If the device connected to the port is not a TTY but a braille
530 device, prepend "brl," before the device type, for instance
532 For now, only VisioBraille is supported.
534 earlycon= [KNL] Output early console device and options.
535 uart[8250],io,<addr>[,options]
536 uart[8250],mmio,<addr>[,options]
537 Start an early, polled-mode console on the 8250/16550
538 UART at the specified I/O port or MMIO address.
539 The options are the same as for ttyS, above.
542 [HW] Never suspend the console
543 Disable suspending of consoles during suspend and
544 hibernate operations. Once disabled, debugging
545 messages can reach various consoles while the rest
546 of the system is being put to sleep (ie, while
547 debugging driver suspend/resume hooks). This may
548 not work reliably with all consoles, but is known
549 to work with serial and VGA consoles.
551 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
553 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
555 crashkernel=nn[KMG]@ss[KMG]
556 [KNL] Reserve a chunk of physical memory to
557 hold a kernel to switch to with kexec on panic.
559 crashkernel=range1:size1[,range2:size2,...][@offset]
560 [KNL] Same as above, but depends on the memory
561 in the running system. The syntax of range is
562 start-[end] where start and end are both
563 a memory unit (amount[KMG]). See also
564 Documentation/kdump/kdump.txt for a example.
567 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
572 cs89x0_media= [HW,NET]
573 Format: { rj45 | aui | bnc }
576 See header of drivers/s390/block/dasd_devmap.c.
578 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
579 (one device per port)
580 Format: <port#>,<type>
581 See also Documentation/input/joystick-parport.txt
583 debug [KNL] Enable kernel debugging (events log level).
586 [KNL] verbose self-tests
588 Print debugging info while doing the locking API
590 We default to 0 (no extra messages), setting it to
591 1 will print _a lot_ more information - normally
592 only useful to kernel developers.
594 debug_objects [KNL] Enable object debugging
596 debugpat [X86] Enable PAT debugging
598 decnet.addr= [HW,NET]
599 Format: <area>[,<node>]
600 See also Documentation/networking/decnet.txt.
603 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
604 Change the default blue palette of the console.
605 This is a 16-member array composed of values
609 Format: <green0>,<green1>,<green2>,...,<green15>
610 Change the default green palette of the console.
611 This is a 16-member array composed of values
615 Format: <red0>,<red1>,<red2>,...,<red15>
616 Change the default red palette of the console.
617 This is a 16-member array composed of values
623 Set system-wide default UTF-8 mode for all tty's.
624 Default is 1, i.e. UTF-8 mode is enabled for all
625 newly opened terminals.
628 Set number of hash buckets for dentry cache.
631 IO parameters + enable/disable command.
633 digiepca= [HW,SERIAL]
634 See drivers/char/README.epca and
635 Documentation/serial/digiepca.txt.
637 disable_mtrr_cleanup [X86]
638 enable_mtrr_cleanup [X86]
639 The kernel tries to adjust MTRR layout from continuous
640 to discrete, to make X server driver able to add WB
641 entry later. This parameter enables/disables that.
643 mtrr_chunk_size=nn[KMG] [X86]
644 used for mtrr cleanup. It is largest continous chunk
645 that could hold holes aka. UC entries.
647 mtrr_gran_size=nn[KMG] [X86]
648 Used for mtrr cleanup. It is granularity of mtrr block.
650 Large value could prevent small alignment from
653 mtrr_spare_reg_nr=n [X86]
655 Range: 0,7 : spare reg number
657 Used for mtrr cleanup. It is spare mtrr entries number.
658 Set to 2 or more if your graphical card needs more.
660 disable_mtrr_trim [X86, Intel and AMD only]
661 By default the kernel will trim any uncacheable
662 memory out of your available memory pool based on
663 MTRR settings. This parameter disables that behavior,
664 possibly causing your machine to run very slowly.
666 dmasound= [HW,OSS] Sound subsystem buffers
672 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
674 earlyprintk=serial[,ttySn[,baudrate]]
677 Append ",keep" to not disable it when the real console
680 Only vga or serial or usb debug port at a time.
682 Currently only ttyS0 and ttyS1 are supported.
684 Interaction with the standard serial driver is not
687 The VGA output is eventually overwritten by the real
693 Format: {"off" | "on" | "skip[mbr]"}
695 eisa_irq_edge= [PARISC,HW]
696 See header of drivers/parisc/eisa.c.
699 See comment before function elanfreq_setup() in
700 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
703 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
704 See Documentation/block/as-iosched.txt and
705 Documentation/block/deadline-iosched.txt for details.
707 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
708 Specifies physical address of start of kernel core
709 image elf header. Generally kexec loader will
710 pass this option to capture kernel.
711 See Documentation/kdump/kdump.txt for details.
713 enforcing [SELINUX] Set initial enforcing status.
715 See security/selinux/Kconfig help text.
716 0 -- permissive (log only, no denials).
717 1 -- enforcing (deny and log).
719 Value can be changed at runtime via /selinux/enforce.
722 Format: <spdif>,[<nomix>,[<amplifier>]]
723 See also header of sound/oss/es1371.c.
725 ether= [HW,NET] Ethernet cards parameters
726 This option is obsoleted by the "netdev=" option, which
727 has equivalent usage. See its documentation for details.
729 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
734 fail_make_request=[KNL]
735 General fault injection mechanism.
736 Format: <interval>,<probability>,<space>,<times>
737 See also /Documentation/fault-injection/.
740 See header of drivers/scsi/fd_mcs.c.
743 See header of drivers/scsi/fdomain.c.
746 See Documentation/blockdev/floppy.txt.
748 force_pal_cache_flush
749 [IA-64] Avoid check_sal_cache_flush which may hang on
750 buggy SAL_CACHE_FLUSH implementations. Using this
751 parameter will force ia64_sal_cache_flush to call
752 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
755 [ftrace] will set and start the specified tracer
756 as early as possible in order to facilitate early
760 [ftrace] will dump the trace buffers on oops.
763 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
764 support via parallel port (up to 5 devices per port)
765 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
766 See also Documentation/input/joystick-parport.txt
770 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
775 See header of drivers/scsi/gdth.c.
777 gpt [EFI] Forces disk with valid GPT signature but
778 invalid Protective MBR to be treated as GPT.
782 hashdist= [KNL,NUMA] Large hashes allocated during boot
783 are distributed across NUMA nodes. Defaults on
784 for IA-64, off otherwise.
785 Format: 0 | 1 (for off | on)
787 hcl= [IA-64] SGI's Hardware Graph compatibility layer
789 hd= [EIDE] (E)IDE hard drive subsystem geometry
790 Format: <cyl>,<head>,<sect>
792 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
793 size of <nn>. This works even on boxes that have no
794 highmem otherwise. This also works to reduce highmem
795 size on bigger boxes.
797 highres= [KNL] Enable/disable high resolution timer mode.
798 Valid parameters: "on", "off"
802 See Documentation/isdn/README.HiSax.
804 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
805 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
806 On x86-64 and powerpc, this option can be specified
807 multiple times interleaved with hugepages= to reserve
808 huge pages of different sizes. Valid pages sizes on
809 x86-64 are 2M (when the CPU supports "pse") and 1G
810 (when the CPU supports the "pdpe1gb" cpuinfo flag)
811 Note that 1GB pages can only be allocated at boot time
812 using hugepages= and not freed afterwards.
814 [same as hugepagesz=] The size of the default
815 HugeTLB page size. This is the size represented by
816 the legacy /proc/ hugepages APIs, used for SHM, and
817 default size when mounting hugetlbfs filesystems.
818 Defaults to the default architecture's huge page size
823 i8042.debug [HW] Toggle i8042 debug mode
824 i8042.direct [HW] Put keyboard port into non-translated mode
825 i8042.dumbkbd [HW] Pretend that controller can only read data from
826 keyboard and cannot control its state
827 (Don't attempt to blink the leds)
828 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
829 i8042.nokbd [HW] Don't check/create keyboard port
830 i8042.noloop [HW] Disable the AUX Loopback command while probing
832 i8042.nomux [HW] Don't check presence of an active multiplexing
834 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
837 [HW] Frequency with which keyboard LEDs should blink
838 when kernel panics (default is 0.5 sec)
839 i8042.reset [HW] Reset the controller during init and cleanup
840 i8042.unlock [HW] Unlock (ignore) the keylock
844 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
845 indicates that the driver is running on unsupported
847 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
848 does not match list of supported models.
850 [HW] Report power status in /proc/i8k
851 (disabled by default)
852 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
855 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
856 See Documentation/mca.txt.
859 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
861 ide= [HW] (E)IDE subsystem
862 Format: ide=nodma or ide=doubler
863 See Documentation/ide/ide.txt.
865 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
866 See Documentation/ide/ide.txt.
869 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
870 Poll forces a polling idle loop that can slightly improves the performance
871 of waking up a idle CPU, but will use a lot of power and make the system
872 run hot. Not recommended.
873 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
874 to not use it because it doesn't save as much power as a normal idle
875 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
877 idle=halt. Halt is forced to be used for CPU idle.
878 In such case C2/C3 won't be used again.
879 idle=nomwait. Disable mwait for CPU C-states
881 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
882 Claim all unknown PCI IDE storage controllers.
884 ignore_loglevel [KNL]
885 Ignore loglevel setting - this will print /all/
886 kernel messages to the console. Useful for debugging.
889 Set number of hash buckets for inode cache.
892 See header of drivers/scsi/in2000.c.
896 Run specified binary instead of /sbin/init as init
899 initcall_debug [KNL] Trace initcalls as they are executed. Useful
900 for working out where the kernel is dying during
903 initrd= [BOOT] Specify the location of the initial ramdisk
905 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
923 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
925 Disable intel iommu driver.
926 igfx_off [Default Off]
927 By default, gfx is mapped as normal device. If a gfx
928 device has a dedicated DMAR unit, the DMAR unit is
929 bypassed by not enabling DMAR with this option. In
930 this case, gfx device will use physical address for
933 With this option iommu will not optimize to look
934 for io virtual address below 32 bit forcing dual
935 address cycle on pci bus for cards supporting greater
936 than 32 bit addressing. The default is to look
937 for translation below 32 bit and if not available
938 then look in the higher range.
940 With this option on every unmap_single operation will
941 result in a hardware IOTLB flush operation as opposed
942 to batching them for performance.
944 io_delay= [X86-32,X86-64] I/O delay method
946 Standard port 0x80 based delay
948 Alternate port 0xed based delay (needed on some systems)
950 Simple two microseconds delay
954 io7= [HW] IO7 for Marvel based alpha systems
955 See comment before marvel_specify_io7 in
956 arch/alpha/kernel/core_marvel.c.
959 See Documentation/filesystems/nfsroot.txt.
961 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
962 See comment before ip2_setup() in
963 drivers/char/ip2/ip2base.c.
965 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
966 See header of drivers/scsi/ips.c.
968 ports= [IP_VS_FTP] IPVS ftp helper module
970 Up to 8 (IP_VS_APP_MAX_PORTS) ports
972 Format: <port>,<port>....
975 When an interrupt is not handled search all handlers
976 for it. Intended to get systems with badly broken
980 When an interrupt is not handled search all handlers
981 for it. Also check all handlers each timer
982 interrupt. Intended to get systems with badly broken
986 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
988 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
990 <cpu number>,...,<cpu number>
992 <cpu number>-<cpu number>
993 (must be a positive range in ascending order)
995 <cpu number>,...,<cpu number>-<cpu number>
997 This option can be used to specify one or more CPUs
998 to isolate from the general SMP balancing and scheduling
999 algorithms. You can move a process onto or off an
1000 "isolated" CPU via the CPU affinity syscalls or cpuset.
1001 <cpu number> begins at 0 and the maximum value is
1002 "number of CPUs in system - 1".
1004 This option is the preferred way to isolate CPUs. The
1005 alternative -- manually setting the CPU mask of all
1006 tasks in the system -- can cause problems and
1007 suboptimal load balancer performance.
1011 js= [HW,JOY] Analog joystick
1012 See Documentation/input/joystick.txt.
1014 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1015 specifies the amount of memory usable by the kernel
1016 for non-movable allocations. The requested amount is
1017 spread evenly throughout all nodes in the system. The
1018 remaining memory in each node is used for Movable
1019 pages. In the event, a node is too small to have both
1020 kernelcore and Movable pages, kernelcore pages will
1021 take priority and other nodes will have a larger number
1022 of kernelcore pages. The Movable zone is used for the
1023 allocation of pages that may be reclaimed or moved
1024 by the page migration subsystem. This means that
1025 HugeTLB pages may not be allocated from this zone.
1026 Note that allocations like PTEs-from-HighMem still
1027 use the HighMem zone if it exists, and the Normal
1028 zone if it does not.
1030 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1031 is similar to kernelcore except it specifies the
1032 amount of memory used for migratable allocations.
1033 If both kernelcore and movablecore is specified,
1034 then kernelcore will be at *least* the specified
1035 value but may be more. If movablecore on its own
1036 is specified, the administrator must be careful
1037 that the amount of memory usable for all allocations
1042 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1045 kgdboc= [HW] kgdb over consoles.
1046 Requires a tty driver that supports console polling.
1047 (only serial suported for now)
1048 Format: <serial_device>[,baud]
1050 kmac= [MIPS] korina ethernet MAC address.
1051 Configure the RouterBoard 532 series on-chip
1052 Ethernet adapter MAC address.
1058 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1061 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1064 libata.dma= [LIBATA] DMA control
1065 libata.dma=0 Disable all PATA and SATA DMA
1066 libata.dma=1 PATA and SATA Disk DMA only
1067 libata.dma=2 ATAPI (CDROM) DMA only
1068 libata.dma=4 Compact Flash DMA only
1069 Combinations also work, so libata.dma=3 enables DMA
1070 for disks and CDROMs, but not CFs.
1072 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1076 libata.force= [LIBATA] Force configurations. The format is comma
1077 separated list of "[ID:]VAL" where ID is
1078 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1079 matching port, link or device. Basically, it matches
1080 the ATA ID string printed on console by libata. If
1081 the whole ID part is omitted, the last PORT and DEVICE
1082 values are used. If ID hasn't been specified yet, the
1083 configuration applies to all ports, links and devices.
1085 If only DEVICE is omitted, the parameter applies to
1086 the port and all links and devices behind it. DEVICE
1087 number of 0 either selects the first device or the
1088 first fan-out link behind PMP device. It does not
1089 select the host link. DEVICE number of 15 selects the
1090 host link and device attached to it.
1092 The VAL specifies the configuration to force. As long
1093 as there's no ambiguity shortcut notation is allowed.
1094 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1095 The following configurations can be forced.
1097 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1098 Any ID with matching PORT is used.
1100 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1102 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1103 udma[/][16,25,33,44,66,100,133] notation is also
1106 * [no]ncq: Turn on or off NCQ.
1108 * nohrst, nosrst, norst: suppress hard, soft
1111 If there are multiple matching configurations changing
1112 the same attribute, the last one is used.
1114 load_ramdisk= [RAM] List of ramdisks to load from floppy
1115 See Documentation/blockdev/ramdisk.txt.
1117 lockd.nlm_grace_period=P [NFS] Assign grace period.
1120 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1123 lockd.nlm_timeout=T [NFS] Assign timeout value.
1126 lockd.nlm_udpport=M [NFS] Assign UDP port.
1129 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1132 loglevel= All Kernel Messages with a loglevel smaller than the
1133 console loglevel will be printed to the console. It can
1134 also be changed with klogd or other programs. The
1135 loglevels are defined as follows:
1137 0 (KERN_EMERG) system is unusable
1138 1 (KERN_ALERT) action must be taken immediately
1139 2 (KERN_CRIT) critical conditions
1140 3 (KERN_ERR) error conditions
1141 4 (KERN_WARNING) warning conditions
1142 5 (KERN_NOTICE) normal but significant condition
1143 6 (KERN_INFO) informational
1144 7 (KERN_DEBUG) debug-level messages
1146 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1147 Format: { n | nk | nM }
1148 n must be a power of two. The default size
1149 is set in the kernel config file.
1151 logo.nologo [FB] Disables display of the built-in Linux logo.
1152 This may be used to provide more screen space for
1153 kernel log messages and is useful when debugging
1154 kernel boot problems.
1156 lp=0 [LP] Specify parallel ports to use, e.g,
1157 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1158 lp=reset first parallel port). 'lp=0' disables the
1159 lp=auto printer driver. 'lp=reset' (which can be
1160 specified in addition to the ports) causes
1161 attached printers to be reset. Using
1162 lp=port1,port2,... specifies the parallel ports
1163 to associate lp devices with, starting with
1164 lp0. A port specification may be 'none' to skip
1165 that lp device, or a parport name such as
1166 'parport0'. Specifying 'lp=auto' instead of a
1167 port specification list means that device IDs
1168 from each port should be examined, to see if
1169 an IEEE 1284-compliant printer is attached; if
1170 so, the driver will manage that printer.
1171 See also header of drivers/char/lp.c.
1174 Sets loops_per_jiffy to given constant, thus avoiding
1175 time-consuming boot-time autodetection (up to 250 ms per
1176 CPU). 0 enables autodetection (default). To determine
1177 the correct value for your kernel, boot with normal
1178 autodetection and see what value is printed. Note that
1179 on SMP systems the preset will be applied to all CPUs,
1180 which is likely to cause problems if your CPUs need
1181 significantly divergent settings. An incorrect value
1182 will cause delays in the kernel to be wrong, leading to
1183 unpredictable I/O errors and other breakage. Although
1184 unlikely, in the extreme case this might damage your
1188 Format: <io>,<irq>,<dma>
1190 mac5380= [HW,SCSI] Format:
1191 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1193 machvec= [IA64] Force the use of a particular machine-vector
1194 (machvec) in a generic kernel.
1195 Example: machvec=hpzx1_swiotlb
1197 max_loop= [LOOP] Maximum number of loopback devices that can
1201 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1202 should make use of. maxcpus=n : n >= 0 limits the
1203 kernel to using 'n' processors. n=0 is a special case,
1204 it is equivalent to "nosmp", which also disables
1207 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1208 or equal to this physical address is ignored.
1210 max_luns= [SCSI] Maximum number of LUNs to probe.
1211 Should be between 1 and 2^32-1.
1214 [SCSI] Maximum number of LUNs received.
1215 Should be between 1 and 16384.
1219 mce [X86-32] Machine Check Exception
1221 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1223 md= [HW] RAID subsystems devices and level
1224 See Documentation/md.txt.
1227 Format: <first>,<last>
1228 Specifies range of consoles to be captured by the MDA.
1230 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1231 Amount of memory to be used when the kernel is not able
1232 to see the whole system memory or for test.
1233 [X86-32] Use together with memmap= to avoid physical
1234 address space collisions. Without memmap= PCI devices
1235 could be placed at addresses belonging to unused RAM.
1237 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1241 [KNL,SH] Allow user to override the default size for
1242 per-device physically contiguous DMA buffers.
1244 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1245 E820 memory map, as specified by the user.
1246 Such memmap=exactmap lines can be constructed based on
1247 BIOS output or other requirements. See the memmap=nn@ss
1250 memmap=nn[KMG]@ss[KMG]
1251 [KNL] Force usage of a specific region of memory
1252 Region of memory to be used, from ss to ss+nn.
1254 memmap=nn[KMG]#ss[KMG]
1255 [KNL,ACPI] Mark specific memory as ACPI data.
1256 Region of memory to be used, from ss to ss+nn.
1258 memmap=nn[KMG]$ss[KMG]
1259 [KNL,ACPI] Mark specific memory as reserved.
1260 Region of memory to be used, from ss to ss+nn.
1261 Example: Exclude memory from 0x18690000-0x1869ffff
1262 memmap=64K$0x18690000
1264 memmap=0x10000$0x18690000
1266 memory_corruption_check=0/1 [X86]
1267 Some BIOSes seem to corrupt the first 64k of
1268 memory when doing things like suspend/resume.
1269 Setting this option will scan the memory
1270 looking for corruption. Enabling this will
1271 both detect corruption and prevent the kernel
1272 from using the memory being corrupted.
1273 However, its intended as a diagnostic tool; if
1274 repeatable BIOS-originated corruption always
1275 affects the same memory, you can use memmap=
1276 to prevent the kernel from using that memory.
1278 memory_corruption_check_size=size [X86]
1279 By default it checks for corruption in the low
1280 64k, making this memory unavailable for normal
1281 use. Use this parameter to scan for
1282 corruption in more or less memory.
1284 memory_corruption_check_period=seconds [X86]
1285 By default it checks for corruption every 60
1286 seconds. Use this parameter to check at some
1287 other rate. 0 disables periodic checking.
1289 memtest= [KNL,X86] Enable memtest
1291 range: 0,4 : pattern number
1292 default : 0 <disable>
1294 meye.*= [HW] Set MotionEye Camera parameters
1295 See Documentation/video4linux/meye.txt.
1297 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1298 Multi-Function General Purpose Timers on AMD Geode
1301 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1302 the BIOS has incorrectly applied a workaround. TinyBIOS
1303 version 0.98 is known to be affected, 0.99 fixes the
1304 problem by letting the user disable the workaround.
1308 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1309 physical address is ignored.
1312 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1313 parameter allows control of the logging verbosity for
1314 the additional memory initialisation checks. A value
1315 of 0 disables mminit logging and a level of 4 will
1316 log everything. Information is printed at KERN_DEBUG
1317 so loglevel=8 may also need to be specified.
1320 [MOUSE] Maximum time between finger touching and
1321 leaving touchpad surface for touch to be considered
1322 a tap and be reported as a left button click (for
1323 touchpads working in absolute mode only).
1325 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1326 reporting absolute coordinates, such as tablets
1327 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1328 reporting absolute coordinates, such as tablets
1333 MTD_Partition= [MTD]
1334 Format: <name>,<region-number>,<size>,<offset>
1336 MTD_Region= [MTD] Format:
1337 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1340 See drivers/mtd/cmdlinepart.c.
1343 ARM/S3C2412 JIVE boot control
1345 See arch/arm/mach-s3c2412/mach-jive.c
1347 mtouchusb.raw_coordinates=
1348 [HW] Make the MicroTouch USB driver use raw coordinates
1349 ('y', default) or cooked coordinates ('n')
1351 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1354 See header of drivers/scsi/NCR_D700.c.
1358 ncr53c400= [HW,SCSI]
1360 ncr53c400a= [HW,SCSI]
1362 ncr53c406a= [HW,SCSI]
1364 ncr53c8xx= [HW,SCSI]
1366 netdev= [NET] Network devices parameters
1367 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1368 Note that mem_start is often overloaded to mean
1369 something different and driver-specific.
1370 This usage is only documented in each driver source
1374 [NETFILTER] Enable connection tracking flow accounting
1375 0 to disable accounting
1376 1 to enable accounting
1377 Default value depends on CONFIG_NF_CT_ACCT that is
1378 going to be removed in 2.6.29.
1381 See Documentation/filesystems/nfsroot.txt.
1383 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1384 See Documentation/filesystems/nfsroot.txt.
1386 nfs.callback_tcpport=
1387 [NFS] set the TCP port on which the NFSv4 callback
1388 channel should listen.
1390 nfs.idmap_cache_timeout=
1391 [NFS] set the maximum lifetime for idmapper cache
1395 [NFS] enable 64-bit inode numbers.
1396 If zero, the NFS client will fake up a 32-bit inode
1397 number for the readdir() and stat() syscalls instead
1398 of returning the full 64-bit number.
1399 The default is to return 64-bit inode numbers.
1401 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1402 when a NMI is triggered.
1403 Format: [state][,regs][,debounce][,die]
1405 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1407 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1408 emulation library even if a 387 maths coprocessor
1411 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1412 caches in the slab allocator. Saves per-node memory,
1413 but will impact performance.
1417 noapic [SMP,APIC] Tells the kernel to not make use of any
1418 IOAPICs that may be present in the system.
1420 nobats [PPC] Do not use BATs for mapping kernel lowmem
1421 on "Classic" PPC cores.
1425 nodelayacct [KNL] Disable per-task delay accounting
1427 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1429 nodsp [SH] Disable hardware DSP at boot time.
1431 noefi [X86-32,X86-64] Disable EFI runtime services support.
1435 noexec [X86-32,X86-64]
1436 On X86-32 available only on PAE configured kernels.
1437 noexec=on: enable non-executable mappings (default)
1438 noexec=off: disable non-executable mappings
1441 This affects only 32-bit executables.
1442 noexec32=on: enable non-executable mappings (default)
1443 read doesn't imply executable mappings
1444 noexec32=off: disable non-executable mappings
1445 read implies executable mappings
1447 nofpu [SH] Disable hardware FPU at boot time.
1449 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1450 register save and restore. The kernel will only save
1451 legacy floating-point registers on task switch.
1453 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1457 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1458 instruction doesn't work correctly and not to
1461 nohalt [IA-64] Tells the kernel not to use the power saving
1462 function PAL_HALT_LIGHT when idle. This increases
1463 power-consumption. On the positive side, it reduces
1464 interrupt wake-up latency, which may improve performance
1465 in certain environments such as networked servers or
1468 nohz= [KNL] Boottime enable/disable dynamic ticks
1469 Valid arguments: on, off
1472 noirqdebug [X86-32] Disables the code which attempts to detect and
1473 disable unhandled interrupt sources.
1475 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1476 broken timer IRQ sources.
1478 noisapnp [ISAPNP] Disables ISA PnP code.
1480 noinitrd [RAM] Tells the kernel not to load any configured
1485 nojitter [IA64] Disables jitter checking for ITC timers.
1487 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1489 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1491 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1493 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1494 default x2apic cluster mode on platforms
1497 noltlbs [PPC] Do not use large page/tlb entries for kernel
1498 lowmem mapping on PPC40x.
1500 nomca [IA-64] Disable machine check abort handling
1502 nomce [X86-32] Machine Check Exception
1504 nomfgpt [X86-32] Disable Multi-Function General Purpose
1505 Timer usage (for AMD Geode machines).
1507 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1509 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1510 with UP alternatives
1512 noresidual [PPC] Don't use residual data on PReP machines.
1514 noresume [SWSUSP] Disables resume and restores original swap
1517 no-scroll [VGA] Disables scrollback.
1518 This is required for the Braillex ib80-piezo Braille
1519 reader made by F.H. Papenmeier (Germany).
1523 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1525 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1526 and disable the IO APIC. legacy for "maxcpus=0".
1528 nosoftlockup [KNL] Disable the soft-lockup detector.
1530 nosync [HW,M68K] Disables sync negotiation for all devices.
1532 notsc [BUGS=X86-32] Disable Time Stamp Counter
1534 nousb [USB] Disable the USB subsystem
1538 nptcg= [IA64] Override max number of concurrent global TLB
1539 purges which is reported from either PAL_VM_SUMMARY or
1542 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1543 one of ['zone', 'node', 'default'] can be specified
1544 This can be set from sysctl after boot.
1545 See Documentation/sysctl/vm.txt for details.
1547 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1549 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1550 Rather than timing out after 20 ms if an EC
1551 command is not properly ACKed, override the length
1552 of the timeout. We have interrupts disabled while
1553 waiting for the ACK, so if this is set too high
1554 interrupts *may* be lost!
1559 oprofile.timer= [HW]
1560 Use timer interrupt instead of performance counters
1562 osst= [HW,SCSI] SCSI Tape Driver
1563 Format: <buffer_size>,<write_threshold>
1564 See also Documentation/scsi/st.txt.
1566 panic= [KNL] Kernel behaviour on panic
1569 parkbd.port= [HW] Parallel port number the keyboard adapter is
1570 connected to, default is 0.
1572 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1573 0 for XT, 1 for AT (default is AT).
1576 parport= [HW,PPT] Specify parallel ports. 0 disables.
1577 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1578 Use 'auto' to force the driver to use any
1579 IRQ/DMA settings detected (the default is to
1580 ignore detected IRQ/DMA settings because of
1581 possible conflicts). You can specify the base
1582 address, IRQ, and DMA settings; IRQ and DMA
1583 should be numbers, or 'auto' (for using detected
1584 settings on that particular port), or 'nofifo'
1585 (to avoid using a FIFO even if it is detected).
1586 Parallel ports are assigned in the order they
1587 are specified on the command line, starting
1590 parport_init_mode= [HW,PPT]
1591 Configure VIA parallel port to operate in
1592 a specific mode. This is necessary on Pegasos
1593 computer where firmware has no options for setting
1594 up parallel port mode and sets it to spp.
1595 Currently this function knows 686a and 8231 chips.
1596 Format: [spp|ps2|epp|ecp|ecpepp]
1598 pas2= [HW,OSS] Format:
1599 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1602 See header of drivers/scsi/pas16.c.
1605 Halt all CPUs after the first oops has been printed for
1606 the specified number of seconds. This is to be used if
1607 your oopses keep scrolling off the screen.
1612 See header of drivers/block/paride/pcd.c.
1613 See also Documentation/blockdev/paride.txt.
1615 pci=option[,option...] [PCI] various PCI subsystem options:
1616 off [X86] don't probe for the PCI bus
1617 bios [X86-32] force use of PCI BIOS, don't access
1618 the hardware directly. Use this if your machine
1619 has a non-standard PCI host bridge.
1620 nobios [X86-32] disallow use of PCI BIOS, only direct
1621 hardware access methods are allowed. Use this
1622 if you experience crashes upon bootup and you
1623 suspect they are caused by the BIOS.
1624 conf1 [X86] Force use of PCI Configuration
1626 conf2 [X86] Force use of PCI Configuration
1628 noaer [PCIE] If the PCIEAER kernel config parameter is
1629 enabled, this kernel boot option can be used to
1630 disable the use of PCIE advanced error reporting.
1631 nodomains [PCI] Disable support for multiple PCI
1632 root domains (aka PCI segments, in ACPI-speak).
1633 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1635 nomsi [MSI] If the PCI_MSI kernel config parameter is
1636 enabled, this kernel boot option can be used to
1637 disable the use of MSI interrupts system-wide.
1638 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1639 routing table. These calls are known to be buggy
1640 on several machines and they hang the machine
1641 when used, but on other computers it's the only
1642 way to get the interrupt routing table. Try
1643 this option if the kernel is unable to allocate
1644 IRQs or discover secondary PCI buses on your
1646 rom [X86] Assign address space to expansion ROMs.
1647 Use with caution as certain devices share
1648 address decoders between ROMs and other
1650 norom [X86] Do not assign address space to
1651 expansion ROMs that do not already have
1652 BIOS assigned address ranges.
1653 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1654 assigned automatically to PCI devices. You can
1655 make the kernel exclude IRQs of your ISA cards
1657 pirqaddr=0xAAAAA [X86] Specify the physical address
1658 of the PIRQ table (normally generated
1659 by the BIOS) if it is outside the
1660 F0000h-100000h range.
1661 lastbus=N [X86] Scan all buses thru bus #N. Can be
1662 useful if the kernel is unable to find your
1663 secondary buses and you want to tell it
1664 explicitly which ones they are.
1665 assign-busses [X86] Always assign all PCI bus
1666 numbers ourselves, overriding
1667 whatever the firmware may have done.
1668 usepirqmask [X86] Honor the possible IRQ mask stored
1669 in the BIOS $PIR table. This is needed on
1670 some systems with broken BIOSes, notably
1671 some HP Pavilion N5400 and Omnibook XE3
1672 notebooks. This will have no effect if ACPI
1673 IRQ routing is enabled.
1674 noacpi [X86] Do not use ACPI for IRQ routing
1675 or for PCI scanning.
1676 use_crs [X86] Use _CRS for PCI resource
1678 routeirq Do IRQ routing for all PCI devices.
1679 This is normally done in pci_enable_device(),
1680 so this option is a temporary workaround
1681 for broken drivers that don't call it.
1682 skip_isa_align [X86] do not align io start addr, so can
1683 handle more pci cards
1684 firmware [ARM] Do not re-enumerate the bus but instead
1685 just use the configuration from the
1686 bootloader. This is currently used on
1687 IXP2000 systems where the bus has to be
1688 configured a certain way for adjunct CPUs.
1689 noearly [X86] Don't do any early type 1 scanning.
1690 This might help on some broken boards which
1691 machine check when some devices' config space
1692 is read. But various workarounds are disabled
1693 and some IOMMU drivers will not work.
1694 bfsort Sort PCI devices into breadth-first order.
1695 This sorting is done to get a device
1696 order compatible with older (<= 2.4) kernels.
1697 nobfsort Don't sort PCI devices into breadth-first order.
1698 cbiosize=nn[KMG] The fixed amount of bus space which is
1699 reserved for the CardBus bridge's IO window.
1700 The default value is 256 bytes.
1701 cbmemsize=nn[KMG] The fixed amount of bus space which is
1702 reserved for the CardBus bridge's memory
1703 window. The default value is 64 megabytes.
1705 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1708 force Enable ASPM even on devices that claim not to support it.
1709 WARNING: Forcing ASPM on may cause system lockups.
1711 pcmv= [HW,PCMCIA] BadgePAD 4
1714 See Documentation/blockdev/paride.txt.
1716 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1719 See arch/parisc/kernel/pdc_chassis.c
1722 See Documentation/blockdev/paride.txt.
1725 See Documentation/blockdev/paride.txt.
1727 pirq= [SMP,APIC] Manual mp-table setup
1728 See Documentation/x86/i386/IO-APIC.txt.
1730 plip= [PPT,NET] Parallel port network link
1731 Format: { parport<nr> | timid | 0 }
1732 See also Documentation/parport.txt.
1734 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1735 Override pmtimer IOPort with a hex value.
1739 Enable PNP debug messages. This depends on the
1740 CONFIG_PNP_DEBUG_MESSAGES option.
1746 { on | off | curr | res | no-curr | no-res }
1749 [ISAPNP] Exclude IRQs for the autoconfiguration
1752 [ISAPNP] Exclude DMAs for the autoconfiguration
1754 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1755 Ranges are in pairs (I/O port base and size).
1758 [ISAPNP] Exclude memory regions for the
1760 Ranges are in pairs (memory base and size).
1763 Enables pr_debug()/dev_dbg() calls if
1764 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1765 be switched on/off via <debugfs>/dynamic_printk/modules
1767 print-fatal-signals=
1768 [KNL] debug: print fatal signals
1769 print-fatal-signals=1: print segfault info to
1773 printk.time= Show timing data prefixed to each printk message line
1774 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1776 profile= [KNL] Enable kernel profiling via /proc/profile
1777 Format: [schedule,]<number>
1778 Param: "schedule" - profile schedule points.
1779 Param: <number> - step/bucket size as a power of 2 for
1780 statistical time based profiling.
1781 Param: "sleep" - profile D-state sleeping (millisecs).
1782 Requires CONFIG_SCHEDSTATS
1783 Param: "kvm" - profile VM exits.
1785 processor.max_cstate= [HW,ACPI]
1786 Limit processor to maximum C-state
1787 max_cstate=9 overrides any DMI blacklist limit.
1789 processor.nocst [HW,ACPI]
1790 Ignore the _CST method to determine C-states,
1791 instead using the legacy FADT method
1793 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1795 See Documentation/blockdev/ramdisk.txt.
1797 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1798 probe for; one of (bare|imps|exps|lifebook|any).
1799 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1801 psmouse.resetafter= [HW,MOUSE]
1802 Try to reset the device after so many bad packets
1805 [HW,MOUSE] Set desired mouse resolution, in dpi.
1806 psmouse.smartscroll=
1807 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1808 0 = disabled, 1 = enabled (default).
1810 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1812 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1815 See Documentation/blockdev/paride.txt.
1818 [KNL] Number of legacy pty's. Overwrites compiled-in
1821 quiet [KNL] Disable most log messages
1826 See Documentation/md.txt.
1828 ramdisk_blocksize= [RAM]
1829 See Documentation/blockdev/ramdisk.txt.
1831 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1832 See Documentation/blockdev/ramdisk.txt.
1834 rcupdate.blimit= [KNL,BOOT]
1835 Set maximum number of finished RCU callbacks to process
1838 rcupdate.qhimark= [KNL,BOOT]
1839 Set threshold of queued
1840 RCU callbacks over which batch limiting is disabled.
1842 rcupdate.qlowmark= [KNL,BOOT]
1843 Set threshold of queued RCU callbacks below which
1844 batch limiting is re-enabled.
1848 Run specified binary instead of /init from the ramdisk,
1849 used for early userspace startup. See initrd.
1851 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1852 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1853 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1856 [KNL, SMP] Set scheduler's default relax_domain_level.
1857 See Documentation/cpusets.txt.
1859 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1861 reservetop= [X86-32]
1863 Reserves a hole at the top of the kernel virtual
1866 reset_devices [KNL] Force drivers to reset the underlying device
1867 during initialization.
1870 Specify the partition device for software suspend
1872 resume_offset= [SWSUSP]
1873 Specify the offset from the beginning of the partition
1874 given by "resume=" at which the swap header is located,
1875 in <PAGE_SIZE> units (needed only for swap files).
1876 See Documentation/power/swsusp-and-swap-files.txt
1878 retain_initrd [RAM] Keep initrd memory after extraction
1880 rhash_entries= [KNL,NET]
1881 Set number of hash buckets for route cache
1883 riscom8= [HW,SERIAL]
1884 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1886 ro [KNL] Mount root device read-only on boot
1888 root= [KNL] Root filesystem
1890 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1891 mount the root filesystem
1893 rootflags= [KNL] Set root filesystem mount option string
1895 rootfstype= [KNL] Set root filesystem type
1897 rootwait [KNL] Wait (indefinitely) for root device to show up.
1898 Useful for devices that are detected asynchronously
1899 (e.g. USB and MMC devices).
1901 root_plug.vendor_id=
1902 [ROOTPLUG] Override the default vendor ID
1904 root_plug.product_id=
1905 [ROOTPLUG] Override the default product ID
1908 [ROOTPLUG] Enable debugging output
1910 rw [KNL] Mount root device read-write on boot
1912 S [KNL] Run init in single mode
1915 See drivers/net/irda/sa1100_ir.c.
1917 sbni= [NET] Granch SBNI12 leased line adapter
1919 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1920 Format: <io>[,<timeout>[,<isapnp>]]
1922 scsi_debug_*= [SCSI]
1923 See drivers/scsi/scsi_debug.c.
1925 scsi_default_dev_flags=
1926 [SCSI] SCSI default device flags
1929 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1930 Format: <vendor>:<model>:<flags>
1931 (flags are integer value)
1933 scsi_logging_level= [SCSI] a bit mask of logging levels
1934 See drivers/scsi/scsi_logging.h for bits. Also
1935 settable via sysctl at dev.scsi.logging_level
1936 (/proc/sys/dev/scsi/logging_level).
1937 There is also a nice 'scsi_logging_level' script in the
1938 S390-tools package, available for download at
1939 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1941 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1942 discovered. async scans them in kernel threads,
1943 allowing boot to proceed. none ignores them, expecting
1944 user space to do the scan.
1946 selinux [SELINUX] Disable or enable SELinux at boot time.
1947 Format: { "0" | "1" }
1948 See security/selinux/Kconfig help text.
1951 Default value is set via kernel config option.
1952 If enabled at boot time, /selinux/disable can be used
1953 later to disable prior to initial policy load.
1955 selinux_compat_net =
1956 [SELINUX] Set initial selinux_compat_net flag value.
1957 Format: { "0" | "1" }
1958 0 -- use new secmark-based packet controls
1959 1 -- use legacy packet controls
1960 Default value is 0 (preferred).
1961 Value can be changed at runtime via
1962 /selinux/compat_net.
1964 serialnumber [BUGS=X86-32]
1967 Maximal number of shapers.
1969 show_msr= [x86] show boot-time MSR settings
1970 Format: { <integer> }
1971 Show boot-time (BIOS-initialized) MSR settings.
1972 The parameter means the number of CPUs to show,
1973 for example 1 means boot CPU only.
1976 See header of drivers/scsi/sim710.c.
1983 slub_debug[=options[,slabs]] [MM, SLUB]
1984 Enabling slub_debug allows one to determine the
1985 culprit if slab objects become corrupted. Enabling
1986 slub_debug can create guard zones around objects and
1987 may poison objects when not in use. Also tracks the
1988 last alloc / free. For more information see
1989 Documentation/vm/slub.txt.
1991 slub_max_order= [MM, SLUB]
1992 Determines the maximum allowed order for slabs.
1993 A high setting may cause OOMs due to memory
1994 fragmentation. For more information see
1995 Documentation/vm/slub.txt.
1997 slub_min_objects= [MM, SLUB]
1998 The minimum number of objects per slab. SLUB will
1999 increase the slab order up to slub_max_order to
2000 generate a sufficiently large slab able to contain
2001 the number of objects indicated. The higher the number
2002 of objects the smaller the overhead of tracking slabs
2003 and the less frequently locks need to be acquired.
2004 For more information see Documentation/vm/slub.txt.
2006 slub_min_order= [MM, SLUB]
2007 Determines the mininum page order for slabs. Must be
2008 lower than slub_max_order.
2009 For more information see Documentation/vm/slub.txt.
2011 slub_nomerge [MM, SLUB]
2012 Disable merging of slabs with similar size. May be
2013 necessary if there is some reason to distinguish
2014 allocs to different slabs. Debug options disable
2015 merging on their own.
2016 For more information see Documentation/vm/slub.txt.
2019 Format: <io1>[,<io2>[,...,<io8>]]
2021 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2022 attempt to substitute SMP alternatives once at boot.
2024 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2025 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2026 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2027 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2028 smsc-ircc2.ircc_irq= [HW] IRQ line
2029 smsc-ircc2.ircc_dma= [HW] DMA channel
2030 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2031 0: Toshiba Satellite 1800 (GP data pin select)
2032 1: Fast pin select (default)
2035 snd-ad1816a= [HW,ALSA]
2037 snd-ad1848= [HW,ALSA]
2039 snd-ali5451= [HW,ALSA]
2041 snd-als100= [HW,ALSA]
2043 snd-als4000= [HW,ALSA]
2045 snd-azt2320= [HW,ALSA]
2047 snd-cmi8330= [HW,ALSA]
2049 snd-cmipci= [HW,ALSA]
2051 snd-cs4231= [HW,ALSA]
2053 snd-cs4232= [HW,ALSA]
2055 snd-cs4236= [HW,ALSA]
2057 snd-cs4281= [HW,ALSA]
2059 snd-cs46xx= [HW,ALSA]
2061 snd-dt019x= [HW,ALSA]
2063 snd-dummy= [HW,ALSA]
2065 snd-emu10k1= [HW,ALSA]
2067 snd-ens1370= [HW,ALSA]
2069 snd-ens1371= [HW,ALSA]
2071 snd-es968= [HW,ALSA]
2073 snd-es1688= [HW,ALSA]
2075 snd-es18xx= [HW,ALSA]
2077 snd-es1938= [HW,ALSA]
2079 snd-es1968= [HW,ALSA]
2081 snd-fm801= [HW,ALSA]
2083 snd-gusclassic= [HW,ALSA]
2085 snd-gusextreme= [HW,ALSA]
2087 snd-gusmax= [HW,ALSA]
2091 snd-ice1712= [HW,ALSA]
2093 snd-intel8x0= [HW,ALSA]
2095 snd-interwave= [HW,ALSA]
2100 snd-korg1212= [HW,ALSA]
2102 snd-maestro3= [HW,ALSA]
2104 snd-mpu401= [HW,ALSA]
2106 snd-mtpav= [HW,ALSA]
2108 snd-nm256= [HW,ALSA]
2110 snd-opl3sa2= [HW,ALSA]
2118 snd-opti93x= [HW,ALSA]
2122 snd-rme32= [HW,ALSA]
2124 snd-rme96= [HW,ALSA]
2126 snd-rme9652= [HW,ALSA]
2132 snd-sbawe= [HW,ALSA]
2134 snd-serial= [HW,ALSA]
2136 snd-sgalaxy= [HW,ALSA]
2138 snd-sonicvibes= [HW,ALSA]
2143 snd-sun-cs4231= [HW,ALSA]
2145 snd-trident= [HW,ALSA]
2147 snd-usb-audio= [HW,ALSA,USB]
2149 snd-via82xx= [HW,ALSA]
2151 snd-virmidi= [HW,ALSA]
2153 snd-wavefront= [HW,ALSA]
2155 snd-ymfpci= [HW,ALSA]
2158 [KNL] Should the soft-lockup detector generate panics.
2160 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2161 See Documentation/sonypi.txt
2163 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2164 See Documentation/serial/specialix.txt.
2166 spia_io_base= [HW,MTD]
2172 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2174 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2175 See Documentation/scsi/st.txt.
2178 Enabled the stack tracer on boot up.
2182 Set the STI (builtin display/keyboard on the HP-PARISC
2183 machines) console (graphic card) which should be used
2184 as the initial boot-console.
2185 See also comment in drivers/video/console/sticore.c.
2188 See comment in drivers/video/console/sticore.c.
2191 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2195 Control how the NFS server code allocates CPUs to
2196 service thread pools. Depending on how many NICs
2197 you have and where their interrupts are bound, this
2198 option will affect which CPUs will do NFS serving.
2199 Note: this parameter cannot be changed while the
2200 NFS server is running.
2202 auto the server chooses an appropriate mode
2203 automatically using heuristics
2204 global a single global pool contains all CPUs
2205 percpu one pool for each CPU
2206 pernode one pool for each NUMA node (equivalent
2207 to global on non-NUMA machines)
2209 swiotlb= [IA-64] Number of I/O TLB slabs
2213 sym53c416= [HW,SCSI]
2214 See header of drivers/scsi/sym53c416.c.
2216 sysrq_always_enabled
2218 Ignore sysrq setting - this boot parameter will
2219 neutralize any effect of /proc/sys/kernel/sysrq.
2220 Useful for debugging.
2223 See header of drivers/scsi/t128.c.
2227 test_suspend= [SUSPEND]
2228 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2229 standby suspend) as the system sleep state to briefly
2230 enter during system startup. The system is woken from
2231 this state using a wakeup-capable RTC alarm.
2233 thash_entries= [KNL,NET]
2234 Set number of hash buckets for TCP connection
2236 thermal.act= [HW,ACPI]
2237 -1: disable all active trip points in all thermal zones
2238 <degrees C>: override all lowest active trip points
2240 thermal.crt= [HW,ACPI]
2241 -1: disable all critical trip points in all thermal zones
2242 <degrees C>: override all critical trip points
2244 thermal.nocrt= [HW,ACPI]
2245 Set to disable actions on ACPI thermal zone
2246 critical and hot trip points.
2248 thermal.off= [HW,ACPI]
2249 1: disable ACPI thermal control
2251 thermal.psv= [HW,ACPI]
2252 -1: disable all passive trip points
2253 <degrees C>: override all passive trip points to this value
2255 thermal.tzp= [HW,ACPI]
2256 Specify global default ACPI thermal zone polling rate
2257 <deci-seconds>: poll all this frequency
2258 0: no polling (default)
2261 See comment before function dc390_setup() in
2262 drivers/scsi/tmscsim.c.
2266 trix= [HW,OSS] MediaTrix AudioTrix Pro
2268 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2270 turbografx.map[2|3]= [HW,JOY]
2271 TurboGraFX parallel port interface
2273 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2274 See also Documentation/input/joystick-parport.txt
2276 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2277 See header of drivers/scsi/u14-34f.c.
2286 [USB] Ignore overcurrent events (default N).
2287 Some badly-designed motherboards generate lots of
2288 bogus events, for ports that aren't wired to
2289 anything. Set this parameter to avoid log spamming.
2290 Note that genuine overcurrent events won't be
2295 Set unknown_nmi_panic=1 early on boot.
2297 usbcore.autosuspend=
2298 [USB] The autosuspend time delay (in seconds) used
2299 for newly-detected USB devices (default 2). This
2300 is the time required before an idle device will be
2301 autosuspended. Devices for which the delay is set
2302 to a negative value won't be autosuspended at all.
2304 usbcore.usbfs_snoop=
2305 [USB] Set to log all usbfs traffic (default 0 = off).
2307 usbcore.blinkenlights=
2308 [USB] Set to cycle leds on hubs (default 0 = off).
2310 usbcore.old_scheme_first=
2311 [USB] Start with the old device initialization
2312 scheme (default 0 = off).
2314 usbcore.use_both_schemes=
2315 [USB] Try the other device initialization scheme
2316 if the first one fails (default 1 = enabled).
2318 usbcore.initial_descriptor_timeout=
2319 [USB] Specifies timeout for the initial 64-byte
2320 USB_REQ_GET_DESCRIPTOR request in milliseconds
2321 (default 5000 = 5.0 seconds).
2324 [USBHID] The interval which mice are to be polled at.
2326 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2327 kernel's map of available physical RAM.
2329 vdso= [X86-32,SH,x86-64]
2330 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2331 vdso=1: enable VDSO (default)
2332 vdso=0: disable VDSO mapping
2334 vdso32= [X86-32,X86-64]
2335 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2336 vdso32=1: enable 32-bit VDSO (default)
2337 vdso32=0: disable 32-bit VDSO mapping
2340 vector=percpu: enable percpu vector domain
2342 video= [FB] Frame buffer configuration
2343 See Documentation/fb/modedb.txt.
2345 vga= [BOOT,X86-32] Select a particular video mode
2346 See Documentation/x86/i386/boot.txt and
2347 Documentation/svga.txt.
2348 Use vga=ask for menu.
2349 This is actually a boot loader parameter; the value is
2350 passed to the kernel using a special protocol.
2352 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2353 size of <nn>. This can be used to increase the
2354 minimum size (128MB on x86). It can also be used to
2355 decrease the size and leave more room for directly
2358 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2361 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2364 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2367 waveartist= [HW,OSS]
2368 Format: <io>,<irq>,<dma>,<dma2>
2371 See header of drivers/scsi/wd33c93.c.
2374 See header of drivers/scsi/wd7000.c.
2377 See Documentation/watchdog/wdt.txt.
2379 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2380 xd_geo= See header of drivers/block/xd.c.
2382 xirc2ps_cs= [NET,PCMCIA]
2384 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2386 norandmaps Don't use address space randomization
2387 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2389 ______________________________________________________________________
2393 Add documentation for ALSA options.
2394 Add more DRM drivers.