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 KMEMTRACE kmemtrace is enabled.
53 LIBATA Libata driver is enabled
54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
62 MSI Message Signaled Interrupts (PCI).
63 MTD MTD (Memory Technology Device) support is enabled.
64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
66 GENERIC_TIME The generic timeofday code is enabled.
67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
73 PCIE PCI Express support is enabled.
74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
80 ROOTPLUG The example Root Plug LSM is enabled.
81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
85 SECURITY Different security models are enabled.
86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
88 SH SuperH architecture is enabled.
89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
91 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are 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 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
756 support via parallel port (up to 5 devices per port)
757 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
758 See also Documentation/input/joystick-parport.txt
762 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
767 See header of drivers/scsi/gdth.c.
769 gpt [EFI] Forces disk with valid GPT signature but
770 invalid Protective MBR to be treated as GPT.
774 hashdist= [KNL,NUMA] Large hashes allocated during boot
775 are distributed across NUMA nodes. Defaults on
776 for IA-64, off otherwise.
777 Format: 0 | 1 (for off | on)
779 hcl= [IA-64] SGI's Hardware Graph compatibility layer
781 hd= [EIDE] (E)IDE hard drive subsystem geometry
782 Format: <cyl>,<head>,<sect>
784 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
785 size of <nn>. This works even on boxes that have no
786 highmem otherwise. This also works to reduce highmem
787 size on bigger boxes.
789 highres= [KNL] Enable/disable high resolution timer mode.
790 Valid parameters: "on", "off"
794 See Documentation/isdn/README.HiSax.
796 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
797 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
798 On x86-64 and powerpc, this option can be specified
799 multiple times interleaved with hugepages= to reserve
800 huge pages of different sizes. Valid pages sizes on
801 x86-64 are 2M (when the CPU supports "pse") and 1G
802 (when the CPU supports the "pdpe1gb" cpuinfo flag)
803 Note that 1GB pages can only be allocated at boot time
804 using hugepages= and not freed afterwards.
806 [same as hugepagesz=] The size of the default
807 HugeTLB page size. This is the size represented by
808 the legacy /proc/ hugepages APIs, used for SHM, and
809 default size when mounting hugetlbfs filesystems.
810 Defaults to the default architecture's huge page size
815 i8042.debug [HW] Toggle i8042 debug mode
816 i8042.direct [HW] Put keyboard port into non-translated mode
817 i8042.dumbkbd [HW] Pretend that controller can only read data from
818 keyboard and cannot control its state
819 (Don't attempt to blink the leds)
820 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
821 i8042.nokbd [HW] Don't check/create keyboard port
822 i8042.noloop [HW] Disable the AUX Loopback command while probing
824 i8042.nomux [HW] Don't check presence of an active multiplexing
826 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
829 [HW] Frequency with which keyboard LEDs should blink
830 when kernel panics (default is 0.5 sec)
831 i8042.reset [HW] Reset the controller during init and cleanup
832 i8042.unlock [HW] Unlock (ignore) the keylock
836 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
837 indicates that the driver is running on unsupported
839 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
840 does not match list of supported models.
842 [HW] Report power status in /proc/i8k
843 (disabled by default)
844 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
847 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
848 See Documentation/mca.txt.
851 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
853 ide= [HW] (E)IDE subsystem
854 Format: ide=nodma or ide=doubler
855 See Documentation/ide/ide.txt.
857 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
858 See Documentation/ide/ide.txt.
861 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
862 Poll forces a polling idle loop that can slightly improves the performance
863 of waking up a idle CPU, but will use a lot of power and make the system
864 run hot. Not recommended.
865 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
866 to not use it because it doesn't save as much power as a normal idle
867 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
869 idle=halt. Halt is forced to be used for CPU idle.
870 In such case C2/C3 won't be used again.
871 idle=nomwait. Disable mwait for CPU C-states
873 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
874 Claim all unknown PCI IDE storage controllers.
876 ignore_loglevel [KNL]
877 Ignore loglevel setting - this will print /all/
878 kernel messages to the console. Useful for debugging.
881 Set number of hash buckets for inode cache.
884 See header of drivers/scsi/in2000.c.
888 Run specified binary instead of /sbin/init as init
891 initcall_debug [KNL] Trace initcalls as they are executed. Useful
892 for working out where the kernel is dying during
895 initrd= [BOOT] Specify the location of the initial ramdisk
897 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
915 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
917 Disable intel iommu driver.
918 igfx_off [Default Off]
919 By default, gfx is mapped as normal device. If a gfx
920 device has a dedicated DMAR unit, the DMAR unit is
921 bypassed by not enabling DMAR with this option. In
922 this case, gfx device will use physical address for
925 With this option iommu will not optimize to look
926 for io virtual address below 32 bit forcing dual
927 address cycle on pci bus for cards supporting greater
928 than 32 bit addressing. The default is to look
929 for translation below 32 bit and if not available
930 then look in the higher range.
932 With this option on every unmap_single operation will
933 result in a hardware IOTLB flush operation as opposed
934 to batching them for performance.
936 io_delay= [X86-32,X86-64] I/O delay method
938 Standard port 0x80 based delay
940 Alternate port 0xed based delay (needed on some systems)
942 Simple two microseconds delay
946 io7= [HW] IO7 for Marvel based alpha systems
947 See comment before marvel_specify_io7 in
948 arch/alpha/kernel/core_marvel.c.
951 See Documentation/filesystems/nfsroot.txt.
953 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
954 See comment before ip2_setup() in
955 drivers/char/ip2/ip2base.c.
957 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
958 See header of drivers/scsi/ips.c.
960 ports= [IP_VS_FTP] IPVS ftp helper module
962 Up to 8 (IP_VS_APP_MAX_PORTS) ports
964 Format: <port>,<port>....
967 When an interrupt is not handled search all handlers
968 for it. Intended to get systems with badly broken
972 When an interrupt is not handled search all handlers
973 for it. Also check all handlers each timer
974 interrupt. Intended to get systems with badly broken
978 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
980 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
982 <cpu number>,...,<cpu number>
984 <cpu number>-<cpu number>
985 (must be a positive range in ascending order)
987 <cpu number>,...,<cpu number>-<cpu number>
989 This option can be used to specify one or more CPUs
990 to isolate from the general SMP balancing and scheduling
991 algorithms. You can move a process onto or off an
992 "isolated" CPU via the CPU affinity syscalls or cpuset.
993 <cpu number> begins at 0 and the maximum value is
994 "number of CPUs in system - 1".
996 This option is the preferred way to isolate CPUs. The
997 alternative -- manually setting the CPU mask of all
998 tasks in the system -- can cause problems and
999 suboptimal load balancer performance.
1003 js= [HW,JOY] Analog joystick
1004 See Documentation/input/joystick.txt.
1006 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1007 specifies the amount of memory usable by the kernel
1008 for non-movable allocations. The requested amount is
1009 spread evenly throughout all nodes in the system. The
1010 remaining memory in each node is used for Movable
1011 pages. In the event, a node is too small to have both
1012 kernelcore and Movable pages, kernelcore pages will
1013 take priority and other nodes will have a larger number
1014 of kernelcore pages. The Movable zone is used for the
1015 allocation of pages that may be reclaimed or moved
1016 by the page migration subsystem. This means that
1017 HugeTLB pages may not be allocated from this zone.
1018 Note that allocations like PTEs-from-HighMem still
1019 use the HighMem zone if it exists, and the Normal
1020 zone if it does not.
1022 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1023 Controls whether kmemtrace is enabled
1026 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1027 subbufs kmemtrace's relay channel has. Set this
1028 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1029 you experience buffer overruns.
1031 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1032 is similar to kernelcore except it specifies the
1033 amount of memory used for migratable allocations.
1034 If both kernelcore and movablecore is specified,
1035 then kernelcore will be at *least* the specified
1036 value but may be more. If movablecore on its own
1037 is specified, the administrator must be careful
1038 that the amount of memory usable for all allocations
1043 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1046 kgdboc= [HW] kgdb over consoles.
1047 Requires a tty driver that supports console polling.
1048 (only serial suported for now)
1049 Format: <serial_device>[,baud]
1051 kmac= [MIPS] korina ethernet MAC address.
1052 Configure the RouterBoard 532 series on-chip
1053 Ethernet adapter MAC address.
1059 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1062 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1065 libata.dma= [LIBATA] DMA control
1066 libata.dma=0 Disable all PATA and SATA DMA
1067 libata.dma=1 PATA and SATA Disk DMA only
1068 libata.dma=2 ATAPI (CDROM) DMA only
1069 libata.dma=4 Compact Flash DMA only
1070 Combinations also work, so libata.dma=3 enables DMA
1071 for disks and CDROMs, but not CFs.
1073 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1077 libata.force= [LIBATA] Force configurations. The format is comma
1078 separated list of "[ID:]VAL" where ID is
1079 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1080 matching port, link or device. Basically, it matches
1081 the ATA ID string printed on console by libata. If
1082 the whole ID part is omitted, the last PORT and DEVICE
1083 values are used. If ID hasn't been specified yet, the
1084 configuration applies to all ports, links and devices.
1086 If only DEVICE is omitted, the parameter applies to
1087 the port and all links and devices behind it. DEVICE
1088 number of 0 either selects the first device or the
1089 first fan-out link behind PMP device. It does not
1090 select the host link. DEVICE number of 15 selects the
1091 host link and device attached to it.
1093 The VAL specifies the configuration to force. As long
1094 as there's no ambiguity shortcut notation is allowed.
1095 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1096 The following configurations can be forced.
1098 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1099 Any ID with matching PORT is used.
1101 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1103 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1104 udma[/][16,25,33,44,66,100,133] notation is also
1107 * [no]ncq: Turn on or off NCQ.
1109 * nohrst, nosrst, norst: suppress hard, soft
1112 If there are multiple matching configurations changing
1113 the same attribute, the last one is used.
1115 load_ramdisk= [RAM] List of ramdisks to load from floppy
1116 See Documentation/blockdev/ramdisk.txt.
1118 lockd.nlm_grace_period=P [NFS] Assign grace period.
1121 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1124 lockd.nlm_timeout=T [NFS] Assign timeout value.
1127 lockd.nlm_udpport=M [NFS] Assign UDP port.
1130 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1133 loglevel= All Kernel Messages with a loglevel smaller than the
1134 console loglevel will be printed to the console. It can
1135 also be changed with klogd or other programs. The
1136 loglevels are defined as follows:
1138 0 (KERN_EMERG) system is unusable
1139 1 (KERN_ALERT) action must be taken immediately
1140 2 (KERN_CRIT) critical conditions
1141 3 (KERN_ERR) error conditions
1142 4 (KERN_WARNING) warning conditions
1143 5 (KERN_NOTICE) normal but significant condition
1144 6 (KERN_INFO) informational
1145 7 (KERN_DEBUG) debug-level messages
1147 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1148 Format: { n | nk | nM }
1149 n must be a power of two. The default size
1150 is set in the kernel config file.
1152 logo.nologo [FB] Disables display of the built-in Linux logo.
1153 This may be used to provide more screen space for
1154 kernel log messages and is useful when debugging
1155 kernel boot problems.
1157 lp=0 [LP] Specify parallel ports to use, e.g,
1158 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1159 lp=reset first parallel port). 'lp=0' disables the
1160 lp=auto printer driver. 'lp=reset' (which can be
1161 specified in addition to the ports) causes
1162 attached printers to be reset. Using
1163 lp=port1,port2,... specifies the parallel ports
1164 to associate lp devices with, starting with
1165 lp0. A port specification may be 'none' to skip
1166 that lp device, or a parport name such as
1167 'parport0'. Specifying 'lp=auto' instead of a
1168 port specification list means that device IDs
1169 from each port should be examined, to see if
1170 an IEEE 1284-compliant printer is attached; if
1171 so, the driver will manage that printer.
1172 See also header of drivers/char/lp.c.
1175 Sets loops_per_jiffy to given constant, thus avoiding
1176 time-consuming boot-time autodetection (up to 250 ms per
1177 CPU). 0 enables autodetection (default). To determine
1178 the correct value for your kernel, boot with normal
1179 autodetection and see what value is printed. Note that
1180 on SMP systems the preset will be applied to all CPUs,
1181 which is likely to cause problems if your CPUs need
1182 significantly divergent settings. An incorrect value
1183 will cause delays in the kernel to be wrong, leading to
1184 unpredictable I/O errors and other breakage. Although
1185 unlikely, in the extreme case this might damage your
1189 Format: <io>,<irq>,<dma>
1191 mac5380= [HW,SCSI] Format:
1192 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1194 machvec= [IA64] Force the use of a particular machine-vector
1195 (machvec) in a generic kernel.
1196 Example: machvec=hpzx1_swiotlb
1198 max_loop= [LOOP] Maximum number of loopback devices that can
1202 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1203 should make use of. maxcpus=n : n >= 0 limits the
1204 kernel to using 'n' processors. n=0 is a special case,
1205 it is equivalent to "nosmp", which also disables
1208 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1209 or equal to this physical address is ignored.
1211 max_luns= [SCSI] Maximum number of LUNs to probe.
1212 Should be between 1 and 2^32-1.
1215 [SCSI] Maximum number of LUNs received.
1216 Should be between 1 and 16384.
1220 mce [X86-32] Machine Check Exception
1222 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1224 md= [HW] RAID subsystems devices and level
1225 See Documentation/md.txt.
1228 Format: <first>,<last>
1229 Specifies range of consoles to be captured by the MDA.
1231 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1232 Amount of memory to be used when the kernel is not able
1233 to see the whole system memory or for test.
1234 [X86-32] Use together with memmap= to avoid physical
1235 address space collisions. Without memmap= PCI devices
1236 could be placed at addresses belonging to unused RAM.
1238 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1242 [KNL,SH] Allow user to override the default size for
1243 per-device physically contiguous DMA buffers.
1245 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1246 E820 memory map, as specified by the user.
1247 Such memmap=exactmap lines can be constructed based on
1248 BIOS output or other requirements. See the memmap=nn@ss
1251 memmap=nn[KMG]@ss[KMG]
1252 [KNL] Force usage of a specific region of memory
1253 Region of memory to be used, from ss to ss+nn.
1255 memmap=nn[KMG]#ss[KMG]
1256 [KNL,ACPI] Mark specific memory as ACPI data.
1257 Region of memory to be used, from ss to ss+nn.
1259 memmap=nn[KMG]$ss[KMG]
1260 [KNL,ACPI] Mark specific memory as reserved.
1261 Region of memory to be used, from ss to ss+nn.
1262 Example: Exclude memory from 0x18690000-0x1869ffff
1263 memmap=64K$0x18690000
1265 memmap=0x10000$0x18690000
1267 memory_corruption_check=0/1 [X86]
1268 Some BIOSes seem to corrupt the first 64k of
1269 memory when doing things like suspend/resume.
1270 Setting this option will scan the memory
1271 looking for corruption. Enabling this will
1272 both detect corruption and prevent the kernel
1273 from using the memory being corrupted.
1274 However, its intended as a diagnostic tool; if
1275 repeatable BIOS-originated corruption always
1276 affects the same memory, you can use memmap=
1277 to prevent the kernel from using that memory.
1279 memory_corruption_check_size=size [X86]
1280 By default it checks for corruption in the low
1281 64k, making this memory unavailable for normal
1282 use. Use this parameter to scan for
1283 corruption in more or less memory.
1285 memory_corruption_check_period=seconds [X86]
1286 By default it checks for corruption every 60
1287 seconds. Use this parameter to check at some
1288 other rate. 0 disables periodic checking.
1290 memtest= [KNL,X86] Enable memtest
1292 range: 0,4 : pattern number
1293 default : 0 <disable>
1295 meye.*= [HW] Set MotionEye Camera parameters
1296 See Documentation/video4linux/meye.txt.
1298 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1299 Multi-Function General Purpose Timers on AMD Geode
1302 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1303 the BIOS has incorrectly applied a workaround. TinyBIOS
1304 version 0.98 is known to be affected, 0.99 fixes the
1305 problem by letting the user disable the workaround.
1309 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1310 physical address is ignored.
1313 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1314 parameter allows control of the logging verbosity for
1315 the additional memory initialisation checks. A value
1316 of 0 disables mminit logging and a level of 4 will
1317 log everything. Information is printed at KERN_DEBUG
1318 so loglevel=8 may also need to be specified.
1321 [MOUSE] Maximum time between finger touching and
1322 leaving touchpad surface for touch to be considered
1323 a tap and be reported as a left button click (for
1324 touchpads working in absolute mode only).
1326 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1327 reporting absolute coordinates, such as tablets
1328 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1329 reporting absolute coordinates, such as tablets
1334 MTD_Partition= [MTD]
1335 Format: <name>,<region-number>,<size>,<offset>
1337 MTD_Region= [MTD] Format:
1338 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1341 See drivers/mtd/cmdlinepart.c.
1344 ARM/S3C2412 JIVE boot control
1346 See arch/arm/mach-s3c2412/mach-jive.c
1348 mtouchusb.raw_coordinates=
1349 [HW] Make the MicroTouch USB driver use raw coordinates
1350 ('y', default) or cooked coordinates ('n')
1352 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1355 See header of drivers/scsi/NCR_D700.c.
1359 ncr53c400= [HW,SCSI]
1361 ncr53c400a= [HW,SCSI]
1363 ncr53c406a= [HW,SCSI]
1365 ncr53c8xx= [HW,SCSI]
1367 netdev= [NET] Network devices parameters
1368 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1369 Note that mem_start is often overloaded to mean
1370 something different and driver-specific.
1371 This usage is only documented in each driver source
1375 [NETFILTER] Enable connection tracking flow accounting
1376 0 to disable accounting
1377 1 to enable accounting
1378 Default value depends on CONFIG_NF_CT_ACCT that is
1379 going to be removed in 2.6.29.
1382 See Documentation/filesystems/nfsroot.txt.
1384 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1385 See Documentation/filesystems/nfsroot.txt.
1387 nfs.callback_tcpport=
1388 [NFS] set the TCP port on which the NFSv4 callback
1389 channel should listen.
1391 nfs.idmap_cache_timeout=
1392 [NFS] set the maximum lifetime for idmapper cache
1396 [NFS] enable 64-bit inode numbers.
1397 If zero, the NFS client will fake up a 32-bit inode
1398 number for the readdir() and stat() syscalls instead
1399 of returning the full 64-bit number.
1400 The default is to return 64-bit inode numbers.
1402 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1403 when a NMI is triggered.
1404 Format: [state][,regs][,debounce][,die]
1406 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1408 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1409 emulation library even if a 387 maths coprocessor
1412 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1413 caches in the slab allocator. Saves per-node memory,
1414 but will impact performance.
1418 noapic [SMP,APIC] Tells the kernel to not make use of any
1419 IOAPICs that may be present in the system.
1421 nobats [PPC] Do not use BATs for mapping kernel lowmem
1422 on "Classic" PPC cores.
1426 nodelayacct [KNL] Disable per-task delay accounting
1428 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1430 nodsp [SH] Disable hardware DSP at boot time.
1432 noefi [X86-32,X86-64] Disable EFI runtime services support.
1436 noexec [X86-32,X86-64]
1437 On X86-32 available only on PAE configured kernels.
1438 noexec=on: enable non-executable mappings (default)
1439 noexec=off: disable non-executable mappings
1442 This affects only 32-bit executables.
1443 noexec32=on: enable non-executable mappings (default)
1444 read doesn't imply executable mappings
1445 noexec32=off: disable non-executable mappings
1446 read implies executable mappings
1448 nofpu [SH] Disable hardware FPU at boot time.
1450 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1451 register save and restore. The kernel will only save
1452 legacy floating-point registers on task switch.
1454 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1458 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1459 instruction doesn't work correctly and not to
1462 nohalt [IA-64] Tells the kernel not to use the power saving
1463 function PAL_HALT_LIGHT when idle. This increases
1464 power-consumption. On the positive side, it reduces
1465 interrupt wake-up latency, which may improve performance
1466 in certain environments such as networked servers or
1469 nohz= [KNL] Boottime enable/disable dynamic ticks
1470 Valid arguments: on, off
1473 noirqdebug [X86-32] Disables the code which attempts to detect and
1474 disable unhandled interrupt sources.
1476 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1477 broken timer IRQ sources.
1479 noisapnp [ISAPNP] Disables ISA PnP code.
1481 noinitrd [RAM] Tells the kernel not to load any configured
1486 nojitter [IA64] Disables jitter checking for ITC timers.
1488 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1490 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1492 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1494 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1495 default x2apic cluster mode on platforms
1498 noltlbs [PPC] Do not use large page/tlb entries for kernel
1499 lowmem mapping on PPC40x.
1501 nomca [IA-64] Disable machine check abort handling
1503 nomce [X86-32] Machine Check Exception
1505 nomfgpt [X86-32] Disable Multi-Function General Purpose
1506 Timer usage (for AMD Geode machines).
1508 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1510 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1511 with UP alternatives
1513 noresidual [PPC] Don't use residual data on PReP machines.
1515 noresume [SWSUSP] Disables resume and restores original swap
1518 no-scroll [VGA] Disables scrollback.
1519 This is required for the Braillex ib80-piezo Braille
1520 reader made by F.H. Papenmeier (Germany).
1524 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1526 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1527 and disable the IO APIC. legacy for "maxcpus=0".
1529 nosoftlockup [KNL] Disable the soft-lockup detector.
1531 nosync [HW,M68K] Disables sync negotiation for all devices.
1533 notsc [BUGS=X86-32] Disable Time Stamp Counter
1535 nousb [USB] Disable the USB subsystem
1539 nptcg= [IA64] Override max number of concurrent global TLB
1540 purges which is reported from either PAL_VM_SUMMARY or
1543 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1544 one of ['zone', 'node', 'default'] can be specified
1545 This can be set from sysctl after boot.
1546 See Documentation/sysctl/vm.txt for details.
1548 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1550 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1551 Rather than timing out after 20 ms if an EC
1552 command is not properly ACKed, override the length
1553 of the timeout. We have interrupts disabled while
1554 waiting for the ACK, so if this is set too high
1555 interrupts *may* be lost!
1560 oprofile.timer= [HW]
1561 Use timer interrupt instead of performance counters
1563 osst= [HW,SCSI] SCSI Tape Driver
1564 Format: <buffer_size>,<write_threshold>
1565 See also Documentation/scsi/st.txt.
1567 panic= [KNL] Kernel behaviour on panic
1570 parkbd.port= [HW] Parallel port number the keyboard adapter is
1571 connected to, default is 0.
1573 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1574 0 for XT, 1 for AT (default is AT).
1577 parport= [HW,PPT] Specify parallel ports. 0 disables.
1578 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1579 Use 'auto' to force the driver to use any
1580 IRQ/DMA settings detected (the default is to
1581 ignore detected IRQ/DMA settings because of
1582 possible conflicts). You can specify the base
1583 address, IRQ, and DMA settings; IRQ and DMA
1584 should be numbers, or 'auto' (for using detected
1585 settings on that particular port), or 'nofifo'
1586 (to avoid using a FIFO even if it is detected).
1587 Parallel ports are assigned in the order they
1588 are specified on the command line, starting
1591 parport_init_mode= [HW,PPT]
1592 Configure VIA parallel port to operate in
1593 a specific mode. This is necessary on Pegasos
1594 computer where firmware has no options for setting
1595 up parallel port mode and sets it to spp.
1596 Currently this function knows 686a and 8231 chips.
1597 Format: [spp|ps2|epp|ecp|ecpepp]
1599 pas2= [HW,OSS] Format:
1600 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1603 See header of drivers/scsi/pas16.c.
1606 Halt all CPUs after the first oops has been printed for
1607 the specified number of seconds. This is to be used if
1608 your oopses keep scrolling off the screen.
1613 See header of drivers/block/paride/pcd.c.
1614 See also Documentation/blockdev/paride.txt.
1616 pci=option[,option...] [PCI] various PCI subsystem options:
1617 off [X86] don't probe for the PCI bus
1618 bios [X86-32] force use of PCI BIOS, don't access
1619 the hardware directly. Use this if your machine
1620 has a non-standard PCI host bridge.
1621 nobios [X86-32] disallow use of PCI BIOS, only direct
1622 hardware access methods are allowed. Use this
1623 if you experience crashes upon bootup and you
1624 suspect they are caused by the BIOS.
1625 conf1 [X86] Force use of PCI Configuration
1627 conf2 [X86] Force use of PCI Configuration
1629 noaer [PCIE] If the PCIEAER kernel config parameter is
1630 enabled, this kernel boot option can be used to
1631 disable the use of PCIE advanced error reporting.
1632 nodomains [PCI] Disable support for multiple PCI
1633 root domains (aka PCI segments, in ACPI-speak).
1634 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1636 nomsi [MSI] If the PCI_MSI kernel config parameter is
1637 enabled, this kernel boot option can be used to
1638 disable the use of MSI interrupts system-wide.
1639 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1640 routing table. These calls are known to be buggy
1641 on several machines and they hang the machine
1642 when used, but on other computers it's the only
1643 way to get the interrupt routing table. Try
1644 this option if the kernel is unable to allocate
1645 IRQs or discover secondary PCI buses on your
1647 rom [X86] Assign address space to expansion ROMs.
1648 Use with caution as certain devices share
1649 address decoders between ROMs and other
1651 norom [X86] Do not assign address space to
1652 expansion ROMs that do not already have
1653 BIOS assigned address ranges.
1654 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1655 assigned automatically to PCI devices. You can
1656 make the kernel exclude IRQs of your ISA cards
1658 pirqaddr=0xAAAAA [X86] Specify the physical address
1659 of the PIRQ table (normally generated
1660 by the BIOS) if it is outside the
1661 F0000h-100000h range.
1662 lastbus=N [X86] Scan all buses thru bus #N. Can be
1663 useful if the kernel is unable to find your
1664 secondary buses and you want to tell it
1665 explicitly which ones they are.
1666 assign-busses [X86] Always assign all PCI bus
1667 numbers ourselves, overriding
1668 whatever the firmware may have done.
1669 usepirqmask [X86] Honor the possible IRQ mask stored
1670 in the BIOS $PIR table. This is needed on
1671 some systems with broken BIOSes, notably
1672 some HP Pavilion N5400 and Omnibook XE3
1673 notebooks. This will have no effect if ACPI
1674 IRQ routing is enabled.
1675 noacpi [X86] Do not use ACPI for IRQ routing
1676 or for PCI scanning.
1677 use_crs [X86] Use _CRS for PCI resource
1679 routeirq Do IRQ routing for all PCI devices.
1680 This is normally done in pci_enable_device(),
1681 so this option is a temporary workaround
1682 for broken drivers that don't call it.
1683 skip_isa_align [X86] do not align io start addr, so can
1684 handle more pci cards
1685 firmware [ARM] Do not re-enumerate the bus but instead
1686 just use the configuration from the
1687 bootloader. This is currently used on
1688 IXP2000 systems where the bus has to be
1689 configured a certain way for adjunct CPUs.
1690 noearly [X86] Don't do any early type 1 scanning.
1691 This might help on some broken boards which
1692 machine check when some devices' config space
1693 is read. But various workarounds are disabled
1694 and some IOMMU drivers will not work.
1695 bfsort Sort PCI devices into breadth-first order.
1696 This sorting is done to get a device
1697 order compatible with older (<= 2.4) kernels.
1698 nobfsort Don't sort PCI devices into breadth-first order.
1699 cbiosize=nn[KMG] The fixed amount of bus space which is
1700 reserved for the CardBus bridge's IO window.
1701 The default value is 256 bytes.
1702 cbmemsize=nn[KMG] The fixed amount of bus space which is
1703 reserved for the CardBus bridge's memory
1704 window. The default value is 64 megabytes.
1706 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1709 force Enable ASPM even on devices that claim not to support it.
1710 WARNING: Forcing ASPM on may cause system lockups.
1712 pcmv= [HW,PCMCIA] BadgePAD 4
1715 See Documentation/blockdev/paride.txt.
1717 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1720 See arch/parisc/kernel/pdc_chassis.c
1723 See Documentation/blockdev/paride.txt.
1726 See Documentation/blockdev/paride.txt.
1728 pirq= [SMP,APIC] Manual mp-table setup
1729 See Documentation/x86/i386/IO-APIC.txt.
1731 plip= [PPT,NET] Parallel port network link
1732 Format: { parport<nr> | timid | 0 }
1733 See also Documentation/parport.txt.
1735 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1736 Override pmtimer IOPort with a hex value.
1740 Enable PNP debug messages. This depends on the
1741 CONFIG_PNP_DEBUG_MESSAGES option.
1747 { on | off | curr | res | no-curr | no-res }
1750 [ISAPNP] Exclude IRQs for the autoconfiguration
1753 [ISAPNP] Exclude DMAs for the autoconfiguration
1755 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1756 Ranges are in pairs (I/O port base and size).
1759 [ISAPNP] Exclude memory regions for the
1761 Ranges are in pairs (memory base and size).
1764 Enables pr_debug()/dev_dbg() calls if
1765 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1766 be switched on/off via <debugfs>/dynamic_printk/modules
1768 print-fatal-signals=
1769 [KNL] debug: print fatal signals
1770 print-fatal-signals=1: print segfault info to
1774 printk.time= Show timing data prefixed to each printk message line
1775 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1777 profile= [KNL] Enable kernel profiling via /proc/profile
1778 Format: [schedule,]<number>
1779 Param: "schedule" - profile schedule points.
1780 Param: <number> - step/bucket size as a power of 2 for
1781 statistical time based profiling.
1782 Param: "sleep" - profile D-state sleeping (millisecs).
1783 Requires CONFIG_SCHEDSTATS
1784 Param: "kvm" - profile VM exits.
1786 processor.max_cstate= [HW,ACPI]
1787 Limit processor to maximum C-state
1788 max_cstate=9 overrides any DMI blacklist limit.
1790 processor.nocst [HW,ACPI]
1791 Ignore the _CST method to determine C-states,
1792 instead using the legacy FADT method
1794 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1796 See Documentation/blockdev/ramdisk.txt.
1798 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1799 probe for; one of (bare|imps|exps|lifebook|any).
1800 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1802 psmouse.resetafter= [HW,MOUSE]
1803 Try to reset the device after so many bad packets
1806 [HW,MOUSE] Set desired mouse resolution, in dpi.
1807 psmouse.smartscroll=
1808 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1809 0 = disabled, 1 = enabled (default).
1811 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1813 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1816 See Documentation/blockdev/paride.txt.
1819 [KNL] Number of legacy pty's. Overwrites compiled-in
1822 quiet [KNL] Disable most log messages
1827 See Documentation/md.txt.
1829 ramdisk_blocksize= [RAM]
1830 See Documentation/blockdev/ramdisk.txt.
1832 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1833 See Documentation/blockdev/ramdisk.txt.
1835 rcupdate.blimit= [KNL,BOOT]
1836 Set maximum number of finished RCU callbacks to process
1839 rcupdate.qhimark= [KNL,BOOT]
1840 Set threshold of queued
1841 RCU callbacks over which batch limiting is disabled.
1843 rcupdate.qlowmark= [KNL,BOOT]
1844 Set threshold of queued RCU callbacks below which
1845 batch limiting is re-enabled.
1849 Run specified binary instead of /init from the ramdisk,
1850 used for early userspace startup. See initrd.
1852 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1853 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1854 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1857 [KNL, SMP] Set scheduler's default relax_domain_level.
1858 See Documentation/cpusets.txt.
1860 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1862 reservetop= [X86-32]
1864 Reserves a hole at the top of the kernel virtual
1867 reset_devices [KNL] Force drivers to reset the underlying device
1868 during initialization.
1871 Specify the partition device for software suspend
1873 resume_offset= [SWSUSP]
1874 Specify the offset from the beginning of the partition
1875 given by "resume=" at which the swap header is located,
1876 in <PAGE_SIZE> units (needed only for swap files).
1877 See Documentation/power/swsusp-and-swap-files.txt
1879 retain_initrd [RAM] Keep initrd memory after extraction
1881 rhash_entries= [KNL,NET]
1882 Set number of hash buckets for route cache
1884 riscom8= [HW,SERIAL]
1885 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1887 ro [KNL] Mount root device read-only on boot
1889 root= [KNL] Root filesystem
1891 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1892 mount the root filesystem
1894 rootflags= [KNL] Set root filesystem mount option string
1896 rootfstype= [KNL] Set root filesystem type
1898 rootwait [KNL] Wait (indefinitely) for root device to show up.
1899 Useful for devices that are detected asynchronously
1900 (e.g. USB and MMC devices).
1902 root_plug.vendor_id=
1903 [ROOTPLUG] Override the default vendor ID
1905 root_plug.product_id=
1906 [ROOTPLUG] Override the default product ID
1909 [ROOTPLUG] Enable debugging output
1911 rw [KNL] Mount root device read-write on boot
1913 S [KNL] Run init in single mode
1916 See drivers/net/irda/sa1100_ir.c.
1918 sbni= [NET] Granch SBNI12 leased line adapter
1920 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1921 Format: <io>[,<timeout>[,<isapnp>]]
1923 scsi_debug_*= [SCSI]
1924 See drivers/scsi/scsi_debug.c.
1926 scsi_default_dev_flags=
1927 [SCSI] SCSI default device flags
1930 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1931 Format: <vendor>:<model>:<flags>
1932 (flags are integer value)
1934 scsi_logging_level= [SCSI] a bit mask of logging levels
1935 See drivers/scsi/scsi_logging.h for bits. Also
1936 settable via sysctl at dev.scsi.logging_level
1937 (/proc/sys/dev/scsi/logging_level).
1938 There is also a nice 'scsi_logging_level' script in the
1939 S390-tools package, available for download at
1940 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1942 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1943 discovered. async scans them in kernel threads,
1944 allowing boot to proceed. none ignores them, expecting
1945 user space to do the scan.
1947 selinux [SELINUX] Disable or enable SELinux at boot time.
1948 Format: { "0" | "1" }
1949 See security/selinux/Kconfig help text.
1952 Default value is set via kernel config option.
1953 If enabled at boot time, /selinux/disable can be used
1954 later to disable prior to initial policy load.
1956 selinux_compat_net =
1957 [SELINUX] Set initial selinux_compat_net flag value.
1958 Format: { "0" | "1" }
1959 0 -- use new secmark-based packet controls
1960 1 -- use legacy packet controls
1961 Default value is 0 (preferred).
1962 Value can be changed at runtime via
1963 /selinux/compat_net.
1965 serialnumber [BUGS=X86-32]
1968 Maximal number of shapers.
1970 show_msr= [x86] show boot-time MSR settings
1971 Format: { <integer> }
1972 Show boot-time (BIOS-initialized) MSR settings.
1973 The parameter means the number of CPUs to show,
1974 for example 1 means boot CPU only.
1977 See header of drivers/scsi/sim710.c.
1984 slub_debug[=options[,slabs]] [MM, SLUB]
1985 Enabling slub_debug allows one to determine the
1986 culprit if slab objects become corrupted. Enabling
1987 slub_debug can create guard zones around objects and
1988 may poison objects when not in use. Also tracks the
1989 last alloc / free. For more information see
1990 Documentation/vm/slub.txt.
1992 slub_max_order= [MM, SLUB]
1993 Determines the maximum allowed order for slabs.
1994 A high setting may cause OOMs due to memory
1995 fragmentation. For more information see
1996 Documentation/vm/slub.txt.
1998 slub_min_objects= [MM, SLUB]
1999 The minimum number of objects per slab. SLUB will
2000 increase the slab order up to slub_max_order to
2001 generate a sufficiently large slab able to contain
2002 the number of objects indicated. The higher the number
2003 of objects the smaller the overhead of tracking slabs
2004 and the less frequently locks need to be acquired.
2005 For more information see Documentation/vm/slub.txt.
2007 slub_min_order= [MM, SLUB]
2008 Determines the mininum page order for slabs. Must be
2009 lower than slub_max_order.
2010 For more information see Documentation/vm/slub.txt.
2012 slub_nomerge [MM, SLUB]
2013 Disable merging of slabs with similar size. May be
2014 necessary if there is some reason to distinguish
2015 allocs to different slabs. Debug options disable
2016 merging on their own.
2017 For more information see Documentation/vm/slub.txt.
2020 Format: <io1>[,<io2>[,...,<io8>]]
2022 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2023 attempt to substitute SMP alternatives once at boot.
2025 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2026 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2027 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2028 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2029 smsc-ircc2.ircc_irq= [HW] IRQ line
2030 smsc-ircc2.ircc_dma= [HW] DMA channel
2031 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2032 0: Toshiba Satellite 1800 (GP data pin select)
2033 1: Fast pin select (default)
2036 snd-ad1816a= [HW,ALSA]
2038 snd-ad1848= [HW,ALSA]
2040 snd-ali5451= [HW,ALSA]
2042 snd-als100= [HW,ALSA]
2044 snd-als4000= [HW,ALSA]
2046 snd-azt2320= [HW,ALSA]
2048 snd-cmi8330= [HW,ALSA]
2050 snd-cmipci= [HW,ALSA]
2052 snd-cs4231= [HW,ALSA]
2054 snd-cs4232= [HW,ALSA]
2056 snd-cs4236= [HW,ALSA]
2058 snd-cs4281= [HW,ALSA]
2060 snd-cs46xx= [HW,ALSA]
2062 snd-dt019x= [HW,ALSA]
2064 snd-dummy= [HW,ALSA]
2066 snd-emu10k1= [HW,ALSA]
2068 snd-ens1370= [HW,ALSA]
2070 snd-ens1371= [HW,ALSA]
2072 snd-es968= [HW,ALSA]
2074 snd-es1688= [HW,ALSA]
2076 snd-es18xx= [HW,ALSA]
2078 snd-es1938= [HW,ALSA]
2080 snd-es1968= [HW,ALSA]
2082 snd-fm801= [HW,ALSA]
2084 snd-gusclassic= [HW,ALSA]
2086 snd-gusextreme= [HW,ALSA]
2088 snd-gusmax= [HW,ALSA]
2092 snd-ice1712= [HW,ALSA]
2094 snd-intel8x0= [HW,ALSA]
2096 snd-interwave= [HW,ALSA]
2101 snd-korg1212= [HW,ALSA]
2103 snd-maestro3= [HW,ALSA]
2105 snd-mpu401= [HW,ALSA]
2107 snd-mtpav= [HW,ALSA]
2109 snd-nm256= [HW,ALSA]
2111 snd-opl3sa2= [HW,ALSA]
2119 snd-opti93x= [HW,ALSA]
2123 snd-rme32= [HW,ALSA]
2125 snd-rme96= [HW,ALSA]
2127 snd-rme9652= [HW,ALSA]
2133 snd-sbawe= [HW,ALSA]
2135 snd-serial= [HW,ALSA]
2137 snd-sgalaxy= [HW,ALSA]
2139 snd-sonicvibes= [HW,ALSA]
2144 snd-sun-cs4231= [HW,ALSA]
2146 snd-trident= [HW,ALSA]
2148 snd-usb-audio= [HW,ALSA,USB]
2150 snd-via82xx= [HW,ALSA]
2152 snd-virmidi= [HW,ALSA]
2154 snd-wavefront= [HW,ALSA]
2156 snd-ymfpci= [HW,ALSA]
2159 [KNL] Should the soft-lockup detector generate panics.
2161 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2162 See Documentation/sonypi.txt
2164 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2165 See Documentation/serial/specialix.txt.
2167 spia_io_base= [HW,MTD]
2173 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2175 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2176 See Documentation/scsi/st.txt.
2180 Set the STI (builtin display/keyboard on the HP-PARISC
2181 machines) console (graphic card) which should be used
2182 as the initial boot-console.
2183 See also comment in drivers/video/console/sticore.c.
2186 See comment in drivers/video/console/sticore.c.
2189 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2193 Control how the NFS server code allocates CPUs to
2194 service thread pools. Depending on how many NICs
2195 you have and where their interrupts are bound, this
2196 option will affect which CPUs will do NFS serving.
2197 Note: this parameter cannot be changed while the
2198 NFS server is running.
2200 auto the server chooses an appropriate mode
2201 automatically using heuristics
2202 global a single global pool contains all CPUs
2203 percpu one pool for each CPU
2204 pernode one pool for each NUMA node (equivalent
2205 to global on non-NUMA machines)
2207 swiotlb= [IA-64] Number of I/O TLB slabs
2211 sym53c416= [HW,SCSI]
2212 See header of drivers/scsi/sym53c416.c.
2214 sysrq_always_enabled
2216 Ignore sysrq setting - this boot parameter will
2217 neutralize any effect of /proc/sys/kernel/sysrq.
2218 Useful for debugging.
2221 See header of drivers/scsi/t128.c.
2225 test_suspend= [SUSPEND]
2226 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2227 standby suspend) as the system sleep state to briefly
2228 enter during system startup. The system is woken from
2229 this state using a wakeup-capable RTC alarm.
2231 thash_entries= [KNL,NET]
2232 Set number of hash buckets for TCP connection
2234 thermal.act= [HW,ACPI]
2235 -1: disable all active trip points in all thermal zones
2236 <degrees C>: override all lowest active trip points
2238 thermal.crt= [HW,ACPI]
2239 -1: disable all critical trip points in all thermal zones
2240 <degrees C>: override all critical trip points
2242 thermal.nocrt= [HW,ACPI]
2243 Set to disable actions on ACPI thermal zone
2244 critical and hot trip points.
2246 thermal.off= [HW,ACPI]
2247 1: disable ACPI thermal control
2249 thermal.psv= [HW,ACPI]
2250 -1: disable all passive trip points
2251 <degrees C>: override all passive trip points to this value
2253 thermal.tzp= [HW,ACPI]
2254 Specify global default ACPI thermal zone polling rate
2255 <deci-seconds>: poll all this frequency
2256 0: no polling (default)
2259 See comment before function dc390_setup() in
2260 drivers/scsi/tmscsim.c.
2264 trix= [HW,OSS] MediaTrix AudioTrix Pro
2266 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2268 turbografx.map[2|3]= [HW,JOY]
2269 TurboGraFX parallel port interface
2271 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2272 See also Documentation/input/joystick-parport.txt
2274 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2275 See header of drivers/scsi/u14-34f.c.
2284 [USB] Ignore overcurrent events (default N).
2285 Some badly-designed motherboards generate lots of
2286 bogus events, for ports that aren't wired to
2287 anything. Set this parameter to avoid log spamming.
2288 Note that genuine overcurrent events won't be
2293 Set unknown_nmi_panic=1 early on boot.
2295 usbcore.autosuspend=
2296 [USB] The autosuspend time delay (in seconds) used
2297 for newly-detected USB devices (default 2). This
2298 is the time required before an idle device will be
2299 autosuspended. Devices for which the delay is set
2300 to a negative value won't be autosuspended at all.
2302 usbcore.usbfs_snoop=
2303 [USB] Set to log all usbfs traffic (default 0 = off).
2305 usbcore.blinkenlights=
2306 [USB] Set to cycle leds on hubs (default 0 = off).
2308 usbcore.old_scheme_first=
2309 [USB] Start with the old device initialization
2310 scheme (default 0 = off).
2312 usbcore.use_both_schemes=
2313 [USB] Try the other device initialization scheme
2314 if the first one fails (default 1 = enabled).
2316 usbcore.initial_descriptor_timeout=
2317 [USB] Specifies timeout for the initial 64-byte
2318 USB_REQ_GET_DESCRIPTOR request in milliseconds
2319 (default 5000 = 5.0 seconds).
2322 [USBHID] The interval which mice are to be polled at.
2324 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2325 kernel's map of available physical RAM.
2327 vdso= [X86-32,SH,x86-64]
2328 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2329 vdso=1: enable VDSO (default)
2330 vdso=0: disable VDSO mapping
2332 vdso32= [X86-32,X86-64]
2333 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2334 vdso32=1: enable 32-bit VDSO (default)
2335 vdso32=0: disable 32-bit VDSO mapping
2338 vector=percpu: enable percpu vector domain
2340 video= [FB] Frame buffer configuration
2341 See Documentation/fb/modedb.txt.
2343 vga= [BOOT,X86-32] Select a particular video mode
2344 See Documentation/x86/i386/boot.txt and
2345 Documentation/svga.txt.
2346 Use vga=ask for menu.
2347 This is actually a boot loader parameter; the value is
2348 passed to the kernel using a special protocol.
2350 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2351 size of <nn>. This can be used to increase the
2352 minimum size (128MB on x86). It can also be used to
2353 decrease the size and leave more room for directly
2356 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2359 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2362 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2365 waveartist= [HW,OSS]
2366 Format: <io>,<irq>,<dma>,<dma2>
2369 See header of drivers/scsi/wd33c93.c.
2372 See header of drivers/scsi/wd7000.c.
2375 See Documentation/watchdog/wdt.txt.
2377 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2378 xd_geo= See header of drivers/block/xd.c.
2380 xirc2ps_cs= [NET,PCMCIA]
2382 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2384 norandmaps Don't use address space randomization
2385 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2387 ______________________________________________________________________
2391 Add documentation for ALSA options.
2392 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob