4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86/x86_64/boot-options.txt .
104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
106 In addition, the following text indicates that the option:
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
112 Parameters denoted with BOOT are actually interpreted by the boot
113 loader, and have no meaning to the kernel directly.
114 Do not modify the syntax of boot loader parameters without extreme
115 need or coordination with <Documentation/x86/i386/boot.txt>.
117 There are also arch-specific kernel-parameters not documented here.
118 See for example <Documentation/x86/x86_64/boot-options.txt>.
120 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121 a trailing = on the name of any parameter states that that parameter will
122 be entered as an environment variable, whereas its absence indicates that
123 it will appear as a kernel argument readable via /proc/cmdline by programs
124 running once the system is up.
126 The number of kernel parameters is not limited, but the length of the
127 complete command line (parameters including spaces etc.) is limited to
128 a fixed number of characters. This limit depends on the architecture
129 and is between 256 and 4096 characters. It is defined in the file
130 ./include/asm/setup.h as COMMAND_LINE_SIZE.
133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
135 Format: { force | off | ht | strict | noirq }
136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
140 strict -- Be less tolerant of platforms that are not
141 strictly ACPI specification compliant.
143 See also Documentation/power/pm.txt, pci=noacpi
145 acpi_apic_instance= [ACPI, IOAPIC]
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
151 acpi_sleep= [HW,ACPI] Sleep options
152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
164 Format: { level | edge | high | low }
166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
176 Format: <irq>,<irq>...
178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
179 Format: <irq>,<irq>...
181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
191 acpi_serialize [HW,ACPI] force serialization of AML methods
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
201 acpi_backlight= [HW,ACPI]
202 acpi_backlight=vendor
204 If set to vendor, prefer vendor specific driver
205 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
206 of the ACPI video.ko driver.
208 acpi_display_output= [HW,ACPI]
209 acpi_display_output=vendor
210 acpi_display_output=video
213 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
214 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
216 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
217 debug output. Bits in debug_layer correspond to a
218 _COMPONENT in an ACPI source file, e.g.,
219 #define _COMPONENT ACPI_PCI_COMPONENT
220 Bits in debug_level correspond to a level in
221 ACPI_DEBUG_PRINT statements, e.g.,
222 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
223 See Documentation/acpi/debug.txt for more information
224 about debug layers and levels.
226 Enable AML "Debug" output, i.e., stores to the Debug
227 object while interpreting AML:
228 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
229 Enable PCI/PCI interrupt routing info messages:
230 acpi.debug_layer=0x400000 acpi.debug_level=0x4
231 Enable all messages related to ACPI hardware:
232 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
234 Some values produce so much output that the system is
235 unusable. The "log_buf_len" parameter may be useful
236 if you need to capture more output.
238 acpi.power_nocheck= [HW,ACPI]
239 Format: 1/0 enable/disable the check of power state.
240 On some bogus BIOS the _PSC object/_STA object of
241 power resource can't return the correct device power
242 state. In such case it is unneccessary to check its
243 power state again in power transition.
244 1 : disable the power state check
246 acpi_pm_good [X86-32,X86-64]
247 Override the pmtimer bug detection: force the kernel
248 to assume that this machine's pmtimer latches its value
249 and always returns good values.
252 { off | try_unsupported }
253 off: disable AGP support
254 try_unsupported: try to drive unsupported chipsets
255 (may crash computer or cause data corruption)
257 enable_timer_pin_1 [i386,x86-64]
258 Enable PIN 1 of APIC timer
259 Can be useful to work around chipset bugs
260 (in particular on some ATI chipsets).
261 The kernel tries to set a reasonable default.
263 disable_timer_pin_1 [i386,x86-64]
264 Disable PIN 1 of APIC timer
265 Can be useful to work around chipset bugs.
268 Format: <io>,<irq>,<dma>,<dma2>,<type>
271 See header of drivers/scsi/advansys.c.
273 advwdt= [HW,WDT] Advantech WDT
274 Format: <iostart>,<iostop>
276 aedsp16= [HW,OSS] Audio Excel DSP 16
277 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
278 See also header of sound/oss/aedsp16.c.
281 See Documentation/scsi/aha152x.txt.
284 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
287 See Documentation/scsi/aic7xxx.txt.
290 See Documentation/scsi/aic79xx.txt.
292 amd_iommu= [HW,X86-84]
293 Pass parameters to the AMD IOMMU driver in the system.
295 isolate - enable device isolation (each device, as far
296 as possible, will get its own protection
298 share - put every device behind one IOMMU into the
299 same protection domain
300 fullflush - enable flushing of IO/TLB entries when
301 they are unmapped. Otherwise they are
302 flushed before they will be reused, which
305 amd_iommu_size= [HW,X86-64]
306 Define the size of the aperture for the AMD IOMMU
307 driver. Possible values are:
308 '32M', '64M' (default), '128M', '256M', '512M', '1G'
310 amijoy.map= [HW,JOY] Amiga joystick support
311 Map of devices attached to JOY0DAT and JOY1DAT
313 See also Documentation/kernel/input/joystick.txt
315 analog.map= [HW,JOY] Analog joystick and gamepad support
316 Specifies type or capabilities of an analog joystick
317 connected to one of 16 gameports
318 Format: <type1>,<type2>,..<type16>
321 Power management functions (SPARCstation-4/5 + deriv.)
323 Disable APC CPU standby support. SPARCstation-Fox does
324 not play well with APC CPU idle - disable it if you have
325 APC and your system crashes randomly.
327 apic= [APIC,i386] Advanced Programmable Interrupt Controller
328 Change the output verbosity whilst booting
329 Format: { quiet (default) | verbose | debug }
330 Change the amount of debugging information output
331 when initialising the APIC and IO-APIC components.
333 apm= [APM] Advanced Power Management
334 See header of arch/x86/kernel/apm_32.c.
336 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
337 Format: <io>,<irq>,<nodeID>
341 atarimouse= [HW,MOUSE] Atari Mouse
343 atascsi= [HW,SCSI] Atari SCSI
345 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
346 EzKey and similar keyboards
348 atkbd.reset= [HW] Reset keyboard during initialization
350 atkbd.set= [HW] Select keyboard code set
351 Format: <int> (2 = AT (default), 3 = PS/2)
353 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
356 atkbd.softraw= [HW] Choose between synthetic and real raw mode
357 Format: <bool> (0 = real, 1 = synthetic (default))
359 atkbd.softrepeat= [HW]
360 Use software keyboard repeat
364 baycom_epp= [HW,AX25]
367 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
369 See header of drivers/net/hamradio/baycom_par.c.
371 baycom_ser_fdx= [HW,AX25]
372 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
373 Format: <io>,<irq>,<mode>[,<baud>]
374 See header of drivers/net/hamradio/baycom_ser_fdx.c.
376 baycom_ser_hdx= [HW,AX25]
377 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
378 Format: <io>,<irq>,<mode>
379 See header of drivers/net/hamradio/baycom_ser_hdx.c.
381 boot_delay= Milliseconds to delay each printk during boot.
382 Values larger than 10 seconds (10000) are changed to
386 bootmem_debug [KNL] Enable bootmem allocator debug messages.
388 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
389 bttv.radio= Most important insmod options are available as
391 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
392 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
395 See drivers/scsi/BusLogic.c, comment before function
396 BusLogic_ParseDriverOptions().
398 c101= [NET] Moxa C101 synchronous serial card
400 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
401 Sometimes CPU hardware bugs make them report the cache
402 size incorrectly. The kernel will attempt work arounds
403 to fix known problems, but for some CPUs it is not
404 possible to determine what the correct size should be.
405 This option provides an override for these situations.
407 security= [SECURITY] Choose a security module to enable at boot.
408 If this boot parameter is not specified, only the first
409 security module asking for security registration will be
410 loaded. An invalid security module name will be treated
411 as if no module has been chosen.
414 [SECURITY] Disable capabilities. This would normally
415 be used only if an alternative security model is to be
416 configured. Potentially dangerous and should only be
417 used if you are entirely sure of the consequences.
419 ccw_timeout_log [S390]
420 See Documentation/s390/CommonIO for details.
422 cgroup_disable= [KNL] Disable a particular controller
423 Format: {name of the controller(s) to disable}
424 {Currently supported controllers - "memory"}
426 checkreqprot [SELINUX] Set initial checkreqprot flag value.
427 Format: { "0" | "1" }
428 See security/selinux/Kconfig help text.
429 0 -- check protection applied by kernel (includes
430 any implied execute protection).
431 1 -- check protection requested by application.
432 Default value is set via a kernel config option.
433 Value can be changed at runtime via
434 /selinux/checkreqprot.
437 See Documentation/s390/CommonIO for details.
439 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
441 Forces specified clocksource (if available) to be used
442 when calculating gettimeofday(). If specified
443 clocksource is not available, it defaults to PIT.
444 Format: { pit | tsc | cyclone | pmtmr }
446 clocksource= [GENERIC_TIME] Override the default clocksource
448 Override the default clocksource and use the clocksource
449 with the name specified.
450 Some clocksource names to choose from, depending on
452 [all] jiffies (this is the base, fallback clocksource)
454 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
455 pxa_timer,timer3,32k_counter,timer0_1
457 [X86-32] pit,hpet,tsc,vmi-timer;
458 scx200_hrt on Geode; cyclone on IBM x440
466 clearcpuid=BITNUM [X86]
467 Disable CPUID feature X for the kernel. See
468 include/asm-x86/cpufeature.h for the valid bit numbers.
469 Note the Linux specific bits are not necessarily
470 stable over kernel options, but the vendor specific
472 Also note that user programs calling CPUID directly
473 or using the feature without checking anything
474 will still see it. This just prevents it from
475 being used by the kernel or shown in /proc/cpuinfo.
476 Also note the kernel might malfunction if you disable
479 code_bytes [IA32/X86_64] How many bytes of object code to print
484 hpet= [X86-32,HPET] option to control HPET usage
485 Format: { enable (default) | disable | force }
486 disable: disable HPET and use PIT instead
487 force: allow force enabled of undocumented chips (ICH4,
490 com20020= [HW,NET] ARCnet - COM20020 chipset
492 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
494 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
498 ARCnet - COM90xx chipset (memory-mapped buffers)
499 Format: <io>[,<irq>[,<memstart>]]
501 condev= [HW,S390] console device
504 console= [KNL] Output console device and options.
506 tty<n> Use the virtual console device <n>.
510 Use the specified serial port. The options are of
511 the form "bbbbpnf", where "bbbb" is the baud rate,
512 "p" is parity ("n", "o", or "e"), "n" is number of
513 bits, and "f" is flow control ("r" for RTS or
514 omit it). Default is "9600n8".
516 See Documentation/serial-console.txt for more
518 Documentation/networking/netconsole.txt for an
521 uart[8250],io,<addr>[,options]
522 uart[8250],mmio,<addr>[,options]
523 Start an early, polled-mode console on the 8250/16550
524 UART at the specified I/O port or MMIO address,
525 switching to the matching ttyS device later. The
526 options are the same as for ttyS, above.
528 If the device connected to the port is not a TTY but a braille
529 device, prepend "brl," before the device type, for instance
531 For now, only VisioBraille is supported.
533 earlycon= [KNL] Output early console device and options.
534 uart[8250],io,<addr>[,options]
535 uart[8250],mmio,<addr>[,options]
536 Start an early, polled-mode console on the 8250/16550
537 UART at the specified I/O port or MMIO address.
538 The options are the same as for ttyS, above.
541 [HW] Never suspend the console
542 Disable suspending of consoles during suspend and
543 hibernate operations. Once disabled, debugging
544 messages can reach various consoles while the rest
545 of the system is being put to sleep (ie, while
546 debugging driver suspend/resume hooks). This may
547 not work reliably with all consoles, but is known
548 to work with serial and VGA consoles.
550 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
552 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
554 crashkernel=nn[KMG]@ss[KMG]
555 [KNL] Reserve a chunk of physical memory to
556 hold a kernel to switch to with kexec on panic.
558 crashkernel=range1:size1[,range2:size2,...][@offset]
559 [KNL] Same as above, but depends on the memory
560 in the running system. The syntax of range is
561 start-[end] where start and end are both
562 a memory unit (amount[KMG]). See also
563 Documentation/kdump/kdump.txt for a example.
566 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
571 cs89x0_media= [HW,NET]
572 Format: { rj45 | aui | bnc }
575 See header of drivers/s390/block/dasd_devmap.c.
577 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
578 (one device per port)
579 Format: <port#>,<type>
580 See also Documentation/input/joystick-parport.txt
582 debug [KNL] Enable kernel debugging (events log level).
585 [KNL] verbose self-tests
587 Print debugging info while doing the locking API
589 We default to 0 (no extra messages), setting it to
590 1 will print _a lot_ more information - normally
591 only useful to kernel developers.
593 debug_objects [KNL] Enable object debugging
595 debugpat [X86] Enable PAT debugging
597 decnet.addr= [HW,NET]
598 Format: <area>[,<node>]
599 See also Documentation/networking/decnet.txt.
602 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
603 Change the default blue palette of the console.
604 This is a 16-member array composed of values
608 Format: <green0>,<green1>,<green2>,...,<green15>
609 Change the default green palette of the console.
610 This is a 16-member array composed of values
614 Format: <red0>,<red1>,<red2>,...,<red15>
615 Change the default red palette of the console.
616 This is a 16-member array composed of values
622 Set system-wide default UTF-8 mode for all tty's.
623 Default is 1, i.e. UTF-8 mode is enabled for all
624 newly opened terminals.
627 Set number of hash buckets for dentry cache.
630 IO parameters + enable/disable command.
632 digiepca= [HW,SERIAL]
633 See drivers/char/README.epca and
634 Documentation/serial/digiepca.txt.
636 disable_mtrr_cleanup [X86]
637 enable_mtrr_cleanup [X86]
638 The kernel tries to adjust MTRR layout from continuous
639 to discrete, to make X server driver able to add WB
640 entry later. This parameter enables/disables that.
642 mtrr_chunk_size=nn[KMG] [X86]
643 used for mtrr cleanup. It is largest continous chunk
644 that could hold holes aka. UC entries.
646 mtrr_gran_size=nn[KMG] [X86]
647 Used for mtrr cleanup. It is granularity of mtrr block.
649 Large value could prevent small alignment from
652 mtrr_spare_reg_nr=n [X86]
654 Range: 0,7 : spare reg number
656 Used for mtrr cleanup. It is spare mtrr entries number.
657 Set to 2 or more if your graphical card needs more.
659 disable_mtrr_trim [X86, Intel and AMD only]
660 By default the kernel will trim any uncacheable
661 memory out of your available memory pool based on
662 MTRR settings. This parameter disables that behavior,
663 possibly causing your machine to run very slowly.
665 dmasound= [HW,OSS] Sound subsystem buffers
671 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
673 earlyprintk=serial[,ttySn[,baudrate]]
676 Append ",keep" to not disable it when the real console
679 Only vga or serial or usb debug port at a time.
681 Currently only ttyS0 and ttyS1 are supported.
683 Interaction with the standard serial driver is not
686 The VGA output is eventually overwritten by the real
692 Format: {"off" | "on" | "skip[mbr]"}
694 eisa_irq_edge= [PARISC,HW]
695 See header of drivers/parisc/eisa.c.
698 See comment before function elanfreq_setup() in
699 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
702 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
703 See Documentation/block/as-iosched.txt and
704 Documentation/block/deadline-iosched.txt for details.
706 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
707 Specifies physical address of start of kernel core
708 image elf header. Generally kexec loader will
709 pass this option to capture kernel.
710 See Documentation/kdump/kdump.txt for details.
712 enforcing [SELINUX] Set initial enforcing status.
714 See security/selinux/Kconfig help text.
715 0 -- permissive (log only, no denials).
716 1 -- enforcing (deny and log).
718 Value can be changed at runtime via /selinux/enforce.
721 Format: <spdif>,[<nomix>,[<amplifier>]]
722 See also header of sound/oss/es1371.c.
724 ether= [HW,NET] Ethernet cards parameters
725 This option is obsoleted by the "netdev=" option, which
726 has equivalent usage. See its documentation for details.
728 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
733 fail_make_request=[KNL]
734 General fault injection mechanism.
735 Format: <interval>,<probability>,<space>,<times>
736 See also /Documentation/fault-injection/.
739 See header of drivers/scsi/fd_mcs.c.
742 See header of drivers/scsi/fdomain.c.
745 See Documentation/blockdev/floppy.txt.
747 force_pal_cache_flush
748 [IA-64] Avoid check_sal_cache_flush which may hang on
749 buggy SAL_CACHE_FLUSH implementations. Using this
750 parameter will force ia64_sal_cache_flush to call
751 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
754 [ftrace] will set and start the specified tracer
755 as early as possible in order to facilitate early
759 [ftrace] will dump the trace buffers on oops.
762 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
763 support via parallel port (up to 5 devices per port)
764 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
765 See also Documentation/input/joystick-parport.txt
769 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
774 See header of drivers/scsi/gdth.c.
776 gpt [EFI] Forces disk with valid GPT signature but
777 invalid Protective MBR to be treated as GPT.
781 hashdist= [KNL,NUMA] Large hashes allocated during boot
782 are distributed across NUMA nodes. Defaults on
783 for IA-64, off otherwise.
784 Format: 0 | 1 (for off | on)
786 hcl= [IA-64] SGI's Hardware Graph compatibility layer
788 hd= [EIDE] (E)IDE hard drive subsystem geometry
789 Format: <cyl>,<head>,<sect>
791 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
792 size of <nn>. This works even on boxes that have no
793 highmem otherwise. This also works to reduce highmem
794 size on bigger boxes.
796 highres= [KNL] Enable/disable high resolution timer mode.
797 Valid parameters: "on", "off"
801 See Documentation/isdn/README.HiSax.
803 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
804 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
805 On x86-64 and powerpc, this option can be specified
806 multiple times interleaved with hugepages= to reserve
807 huge pages of different sizes. Valid pages sizes on
808 x86-64 are 2M (when the CPU supports "pse") and 1G
809 (when the CPU supports the "pdpe1gb" cpuinfo flag)
810 Note that 1GB pages can only be allocated at boot time
811 using hugepages= and not freed afterwards.
813 [same as hugepagesz=] The size of the default
814 HugeTLB page size. This is the size represented by
815 the legacy /proc/ hugepages APIs, used for SHM, and
816 default size when mounting hugetlbfs filesystems.
817 Defaults to the default architecture's huge page size
822 i8042.debug [HW] Toggle i8042 debug mode
823 i8042.direct [HW] Put keyboard port into non-translated mode
824 i8042.dumbkbd [HW] Pretend that controller can only read data from
825 keyboard and cannot control its state
826 (Don't attempt to blink the leds)
827 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
828 i8042.nokbd [HW] Don't check/create keyboard port
829 i8042.noloop [HW] Disable the AUX Loopback command while probing
831 i8042.nomux [HW] Don't check presence of an active multiplexing
833 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
836 [HW] Frequency with which keyboard LEDs should blink
837 when kernel panics (default is 0.5 sec)
838 i8042.reset [HW] Reset the controller during init and cleanup
839 i8042.unlock [HW] Unlock (ignore) the keylock
843 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
844 indicates that the driver is running on unsupported
846 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
847 does not match list of supported models.
849 [HW] Report power status in /proc/i8k
850 (disabled by default)
851 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
854 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
855 See Documentation/mca.txt.
858 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
860 ide= [HW] (E)IDE subsystem
861 Format: ide=nodma or ide=doubler
862 See Documentation/ide/ide.txt.
864 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
865 See Documentation/ide/ide.txt.
868 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
869 Poll forces a polling idle loop that can slightly improves the performance
870 of waking up a idle CPU, but will use a lot of power and make the system
871 run hot. Not recommended.
872 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
873 to not use it because it doesn't save as much power as a normal idle
874 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
876 idle=halt. Halt is forced to be used for CPU idle.
877 In such case C2/C3 won't be used again.
878 idle=nomwait. Disable mwait for CPU C-states
880 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
881 Claim all unknown PCI IDE storage controllers.
883 ignore_loglevel [KNL]
884 Ignore loglevel setting - this will print /all/
885 kernel messages to the console. Useful for debugging.
888 Set number of hash buckets for inode cache.
891 See header of drivers/scsi/in2000.c.
895 Run specified binary instead of /sbin/init as init
898 initcall_debug [KNL] Trace initcalls as they are executed. Useful
899 for working out where the kernel is dying during
902 initrd= [BOOT] Specify the location of the initial ramdisk
904 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
922 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
924 Disable intel iommu driver.
925 igfx_off [Default Off]
926 By default, gfx is mapped as normal device. If a gfx
927 device has a dedicated DMAR unit, the DMAR unit is
928 bypassed by not enabling DMAR with this option. In
929 this case, gfx device will use physical address for
932 With this option iommu will not optimize to look
933 for io virtual address below 32 bit forcing dual
934 address cycle on pci bus for cards supporting greater
935 than 32 bit addressing. The default is to look
936 for translation below 32 bit and if not available
937 then look in the higher range.
939 With this option on every unmap_single operation will
940 result in a hardware IOTLB flush operation as opposed
941 to batching them for performance.
943 io_delay= [X86-32,X86-64] I/O delay method
945 Standard port 0x80 based delay
947 Alternate port 0xed based delay (needed on some systems)
949 Simple two microseconds delay
953 io7= [HW] IO7 for Marvel based alpha systems
954 See comment before marvel_specify_io7 in
955 arch/alpha/kernel/core_marvel.c.
958 See Documentation/filesystems/nfsroot.txt.
960 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
961 See comment before ip2_setup() in
962 drivers/char/ip2/ip2base.c.
964 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
965 See header of drivers/scsi/ips.c.
967 ports= [IP_VS_FTP] IPVS ftp helper module
969 Up to 8 (IP_VS_APP_MAX_PORTS) ports
971 Format: <port>,<port>....
974 When an interrupt is not handled search all handlers
975 for it. Intended to get systems with badly broken
979 When an interrupt is not handled search all handlers
980 for it. Also check all handlers each timer
981 interrupt. Intended to get systems with badly broken
985 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
987 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
989 <cpu number>,...,<cpu number>
991 <cpu number>-<cpu number>
992 (must be a positive range in ascending order)
994 <cpu number>,...,<cpu number>-<cpu number>
996 This option can be used to specify one or more CPUs
997 to isolate from the general SMP balancing and scheduling
998 algorithms. You can move a process onto or off an
999 "isolated" CPU via the CPU affinity syscalls or cpuset.
1000 <cpu number> begins at 0 and the maximum value is
1001 "number of CPUs in system - 1".
1003 This option is the preferred way to isolate CPUs. The
1004 alternative -- manually setting the CPU mask of all
1005 tasks in the system -- can cause problems and
1006 suboptimal load balancer performance.
1010 js= [HW,JOY] Analog joystick
1011 See Documentation/input/joystick.txt.
1013 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1014 specifies the amount of memory usable by the kernel
1015 for non-movable allocations. The requested amount is
1016 spread evenly throughout all nodes in the system. The
1017 remaining memory in each node is used for Movable
1018 pages. In the event, a node is too small to have both
1019 kernelcore and Movable pages, kernelcore pages will
1020 take priority and other nodes will have a larger number
1021 of kernelcore pages. The Movable zone is used for the
1022 allocation of pages that may be reclaimed or moved
1023 by the page migration subsystem. This means that
1024 HugeTLB pages may not be allocated from this zone.
1025 Note that allocations like PTEs-from-HighMem still
1026 use the HighMem zone if it exists, and the Normal
1027 zone if it does not.
1029 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1030 is similar to kernelcore except it specifies the
1031 amount of memory used for migratable allocations.
1032 If both kernelcore and movablecore is specified,
1033 then kernelcore will be at *least* the specified
1034 value but may be more. If movablecore on its own
1035 is specified, the administrator must be careful
1036 that the amount of memory usable for all allocations
1041 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1044 kgdboc= [HW] kgdb over consoles.
1045 Requires a tty driver that supports console polling.
1046 (only serial suported for now)
1047 Format: <serial_device>[,baud]
1049 kmac= [MIPS] korina ethernet MAC address.
1050 Configure the RouterBoard 532 series on-chip
1051 Ethernet adapter MAC address.
1057 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1060 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1063 libata.dma= [LIBATA] DMA control
1064 libata.dma=0 Disable all PATA and SATA DMA
1065 libata.dma=1 PATA and SATA Disk DMA only
1066 libata.dma=2 ATAPI (CDROM) DMA only
1067 libata.dma=4 Compact Flash DMA only
1068 Combinations also work, so libata.dma=3 enables DMA
1069 for disks and CDROMs, but not CFs.
1071 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1075 libata.force= [LIBATA] Force configurations. The format is comma
1076 separated list of "[ID:]VAL" where ID is
1077 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1078 matching port, link or device. Basically, it matches
1079 the ATA ID string printed on console by libata. If
1080 the whole ID part is omitted, the last PORT and DEVICE
1081 values are used. If ID hasn't been specified yet, the
1082 configuration applies to all ports, links and devices.
1084 If only DEVICE is omitted, the parameter applies to
1085 the port and all links and devices behind it. DEVICE
1086 number of 0 either selects the first device or the
1087 first fan-out link behind PMP device. It does not
1088 select the host link. DEVICE number of 15 selects the
1089 host link and device attached to it.
1091 The VAL specifies the configuration to force. As long
1092 as there's no ambiguity shortcut notation is allowed.
1093 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1094 The following configurations can be forced.
1096 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1097 Any ID with matching PORT is used.
1099 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1101 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1102 udma[/][16,25,33,44,66,100,133] notation is also
1105 * [no]ncq: Turn on or off NCQ.
1107 * nohrst, nosrst, norst: suppress hard, soft
1110 If there are multiple matching configurations changing
1111 the same attribute, the last one is used.
1113 load_ramdisk= [RAM] List of ramdisks to load from floppy
1114 See Documentation/blockdev/ramdisk.txt.
1116 lockd.nlm_grace_period=P [NFS] Assign grace period.
1119 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1122 lockd.nlm_timeout=T [NFS] Assign timeout value.
1125 lockd.nlm_udpport=M [NFS] Assign UDP port.
1128 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1131 loglevel= All Kernel Messages with a loglevel smaller than the
1132 console loglevel will be printed to the console. It can
1133 also be changed with klogd or other programs. The
1134 loglevels are defined as follows:
1136 0 (KERN_EMERG) system is unusable
1137 1 (KERN_ALERT) action must be taken immediately
1138 2 (KERN_CRIT) critical conditions
1139 3 (KERN_ERR) error conditions
1140 4 (KERN_WARNING) warning conditions
1141 5 (KERN_NOTICE) normal but significant condition
1142 6 (KERN_INFO) informational
1143 7 (KERN_DEBUG) debug-level messages
1145 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1146 Format: { n | nk | nM }
1147 n must be a power of two. The default size
1148 is set in the kernel config file.
1150 logo.nologo [FB] Disables display of the built-in Linux logo.
1151 This may be used to provide more screen space for
1152 kernel log messages and is useful when debugging
1153 kernel boot problems.
1155 lp=0 [LP] Specify parallel ports to use, e.g,
1156 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1157 lp=reset first parallel port). 'lp=0' disables the
1158 lp=auto printer driver. 'lp=reset' (which can be
1159 specified in addition to the ports) causes
1160 attached printers to be reset. Using
1161 lp=port1,port2,... specifies the parallel ports
1162 to associate lp devices with, starting with
1163 lp0. A port specification may be 'none' to skip
1164 that lp device, or a parport name such as
1165 'parport0'. Specifying 'lp=auto' instead of a
1166 port specification list means that device IDs
1167 from each port should be examined, to see if
1168 an IEEE 1284-compliant printer is attached; if
1169 so, the driver will manage that printer.
1170 See also header of drivers/char/lp.c.
1173 Sets loops_per_jiffy to given constant, thus avoiding
1174 time-consuming boot-time autodetection (up to 250 ms per
1175 CPU). 0 enables autodetection (default). To determine
1176 the correct value for your kernel, boot with normal
1177 autodetection and see what value is printed. Note that
1178 on SMP systems the preset will be applied to all CPUs,
1179 which is likely to cause problems if your CPUs need
1180 significantly divergent settings. An incorrect value
1181 will cause delays in the kernel to be wrong, leading to
1182 unpredictable I/O errors and other breakage. Although
1183 unlikely, in the extreme case this might damage your
1187 Format: <io>,<irq>,<dma>
1189 mac5380= [HW,SCSI] Format:
1190 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1192 machvec= [IA64] Force the use of a particular machine-vector
1193 (machvec) in a generic kernel.
1194 Example: machvec=hpzx1_swiotlb
1196 max_loop= [LOOP] Maximum number of loopback devices that can
1200 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1201 should make use of. maxcpus=n : n >= 0 limits the
1202 kernel to using 'n' processors. n=0 is a special case,
1203 it is equivalent to "nosmp", which also disables
1206 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1207 or equal to this physical address is ignored.
1209 max_luns= [SCSI] Maximum number of LUNs to probe.
1210 Should be between 1 and 2^32-1.
1213 [SCSI] Maximum number of LUNs received.
1214 Should be between 1 and 16384.
1218 mce [X86-32] Machine Check Exception
1220 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1222 md= [HW] RAID subsystems devices and level
1223 See Documentation/md.txt.
1226 Format: <first>,<last>
1227 Specifies range of consoles to be captured by the MDA.
1229 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1230 Amount of memory to be used when the kernel is not able
1231 to see the whole system memory or for test.
1232 [X86-32] Use together with memmap= to avoid physical
1233 address space collisions. Without memmap= PCI devices
1234 could be placed at addresses belonging to unused RAM.
1236 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1240 [KNL,SH] Allow user to override the default size for
1241 per-device physically contiguous DMA buffers.
1243 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1244 E820 memory map, as specified by the user.
1245 Such memmap=exactmap lines can be constructed based on
1246 BIOS output or other requirements. See the memmap=nn@ss
1249 memmap=nn[KMG]@ss[KMG]
1250 [KNL] Force usage of a specific region of memory
1251 Region of memory to be used, from ss to ss+nn.
1253 memmap=nn[KMG]#ss[KMG]
1254 [KNL,ACPI] Mark specific memory as ACPI data.
1255 Region of memory to be used, from ss to ss+nn.
1257 memmap=nn[KMG]$ss[KMG]
1258 [KNL,ACPI] Mark specific memory as reserved.
1259 Region of memory to be used, from ss to ss+nn.
1260 Example: Exclude memory from 0x18690000-0x1869ffff
1261 memmap=64K$0x18690000
1263 memmap=0x10000$0x18690000
1265 memory_corruption_check=0/1 [X86]
1266 Some BIOSes seem to corrupt the first 64k of
1267 memory when doing things like suspend/resume.
1268 Setting this option will scan the memory
1269 looking for corruption. Enabling this will
1270 both detect corruption and prevent the kernel
1271 from using the memory being corrupted.
1272 However, its intended as a diagnostic tool; if
1273 repeatable BIOS-originated corruption always
1274 affects the same memory, you can use memmap=
1275 to prevent the kernel from using that memory.
1277 memory_corruption_check_size=size [X86]
1278 By default it checks for corruption in the low
1279 64k, making this memory unavailable for normal
1280 use. Use this parameter to scan for
1281 corruption in more or less memory.
1283 memory_corruption_check_period=seconds [X86]
1284 By default it checks for corruption every 60
1285 seconds. Use this parameter to check at some
1286 other rate. 0 disables periodic checking.
1288 memtest= [KNL,X86] Enable memtest
1290 range: 0,4 : pattern number
1291 default : 0 <disable>
1293 meye.*= [HW] Set MotionEye Camera parameters
1294 See Documentation/video4linux/meye.txt.
1296 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1297 Multi-Function General Purpose Timers on AMD Geode
1300 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1301 the BIOS has incorrectly applied a workaround. TinyBIOS
1302 version 0.98 is known to be affected, 0.99 fixes the
1303 problem by letting the user disable the workaround.
1307 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1308 physical address is ignored.
1311 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1312 parameter allows control of the logging verbosity for
1313 the additional memory initialisation checks. A value
1314 of 0 disables mminit logging and a level of 4 will
1315 log everything. Information is printed at KERN_DEBUG
1316 so loglevel=8 may also need to be specified.
1319 [MOUSE] Maximum time between finger touching and
1320 leaving touchpad surface for touch to be considered
1321 a tap and be reported as a left button click (for
1322 touchpads working in absolute mode only).
1324 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1325 reporting absolute coordinates, such as tablets
1326 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1327 reporting absolute coordinates, such as tablets
1332 MTD_Partition= [MTD]
1333 Format: <name>,<region-number>,<size>,<offset>
1335 MTD_Region= [MTD] Format:
1336 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1339 See drivers/mtd/cmdlinepart.c.
1342 ARM/S3C2412 JIVE boot control
1344 See arch/arm/mach-s3c2412/mach-jive.c
1346 mtouchusb.raw_coordinates=
1347 [HW] Make the MicroTouch USB driver use raw coordinates
1348 ('y', default) or cooked coordinates ('n')
1350 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1353 See header of drivers/scsi/NCR_D700.c.
1357 ncr53c400= [HW,SCSI]
1359 ncr53c400a= [HW,SCSI]
1361 ncr53c406a= [HW,SCSI]
1363 ncr53c8xx= [HW,SCSI]
1365 netdev= [NET] Network devices parameters
1366 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1367 Note that mem_start is often overloaded to mean
1368 something different and driver-specific.
1369 This usage is only documented in each driver source
1373 [NETFILTER] Enable connection tracking flow accounting
1374 0 to disable accounting
1375 1 to enable accounting
1376 Default value depends on CONFIG_NF_CT_ACCT that is
1377 going to be removed in 2.6.29.
1380 See Documentation/filesystems/nfsroot.txt.
1382 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1383 See Documentation/filesystems/nfsroot.txt.
1385 nfs.callback_tcpport=
1386 [NFS] set the TCP port on which the NFSv4 callback
1387 channel should listen.
1389 nfs.idmap_cache_timeout=
1390 [NFS] set the maximum lifetime for idmapper cache
1394 [NFS] enable 64-bit inode numbers.
1395 If zero, the NFS client will fake up a 32-bit inode
1396 number for the readdir() and stat() syscalls instead
1397 of returning the full 64-bit number.
1398 The default is to return 64-bit inode numbers.
1400 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1401 when a NMI is triggered.
1402 Format: [state][,regs][,debounce][,die]
1404 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1406 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1407 emulation library even if a 387 maths coprocessor
1410 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1411 caches in the slab allocator. Saves per-node memory,
1412 but will impact performance.
1416 noapic [SMP,APIC] Tells the kernel to not make use of any
1417 IOAPICs that may be present in the system.
1419 nobats [PPC] Do not use BATs for mapping kernel lowmem
1420 on "Classic" PPC cores.
1424 nodelayacct [KNL] Disable per-task delay accounting
1426 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1428 nodsp [SH] Disable hardware DSP at boot time.
1430 noefi [X86-32,X86-64] Disable EFI runtime services support.
1434 noexec [X86-32,X86-64]
1435 On X86-32 available only on PAE configured kernels.
1436 noexec=on: enable non-executable mappings (default)
1437 noexec=off: disable non-executable mappings
1440 This affects only 32-bit executables.
1441 noexec32=on: enable non-executable mappings (default)
1442 read doesn't imply executable mappings
1443 noexec32=off: disable non-executable mappings
1444 read implies executable mappings
1446 nofpu [SH] Disable hardware FPU at boot time.
1448 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1449 register save and restore. The kernel will only save
1450 legacy floating-point registers on task switch.
1452 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1456 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1457 instruction doesn't work correctly and not to
1460 nohalt [IA-64] Tells the kernel not to use the power saving
1461 function PAL_HALT_LIGHT when idle. This increases
1462 power-consumption. On the positive side, it reduces
1463 interrupt wake-up latency, which may improve performance
1464 in certain environments such as networked servers or
1467 nohz= [KNL] Boottime enable/disable dynamic ticks
1468 Valid arguments: on, off
1471 noirqdebug [X86-32] Disables the code which attempts to detect and
1472 disable unhandled interrupt sources.
1474 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1475 broken timer IRQ sources.
1477 noisapnp [ISAPNP] Disables ISA PnP code.
1479 noinitrd [RAM] Tells the kernel not to load any configured
1484 nojitter [IA64] Disables jitter checking for ITC timers.
1486 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1488 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1490 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1492 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1493 default x2apic cluster mode on platforms
1496 noltlbs [PPC] Do not use large page/tlb entries for kernel
1497 lowmem mapping on PPC40x.
1499 nomca [IA-64] Disable machine check abort handling
1501 nomce [X86-32] Machine Check Exception
1503 nomfgpt [X86-32] Disable Multi-Function General Purpose
1504 Timer usage (for AMD Geode machines).
1506 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1508 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1509 with UP alternatives
1511 noresidual [PPC] Don't use residual data on PReP machines.
1513 noresume [SWSUSP] Disables resume and restores original swap
1516 no-scroll [VGA] Disables scrollback.
1517 This is required for the Braillex ib80-piezo Braille
1518 reader made by F.H. Papenmeier (Germany).
1522 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1524 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1525 and disable the IO APIC. legacy for "maxcpus=0".
1527 nosoftlockup [KNL] Disable the soft-lockup detector.
1529 nosync [HW,M68K] Disables sync negotiation for all devices.
1531 notsc [BUGS=X86-32] Disable Time Stamp Counter
1533 nousb [USB] Disable the USB subsystem
1537 nptcg= [IA64] Override max number of concurrent global TLB
1538 purges which is reported from either PAL_VM_SUMMARY or
1541 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1542 one of ['zone', 'node', 'default'] can be specified
1543 This can be set from sysctl after boot.
1544 See Documentation/sysctl/vm.txt for details.
1546 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1548 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1549 Rather than timing out after 20 ms if an EC
1550 command is not properly ACKed, override the length
1551 of the timeout. We have interrupts disabled while
1552 waiting for the ACK, so if this is set too high
1553 interrupts *may* be lost!
1558 oprofile.timer= [HW]
1559 Use timer interrupt instead of performance counters
1561 osst= [HW,SCSI] SCSI Tape Driver
1562 Format: <buffer_size>,<write_threshold>
1563 See also Documentation/scsi/st.txt.
1565 panic= [KNL] Kernel behaviour on panic
1568 parkbd.port= [HW] Parallel port number the keyboard adapter is
1569 connected to, default is 0.
1571 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1572 0 for XT, 1 for AT (default is AT).
1575 parport= [HW,PPT] Specify parallel ports. 0 disables.
1576 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1577 Use 'auto' to force the driver to use any
1578 IRQ/DMA settings detected (the default is to
1579 ignore detected IRQ/DMA settings because of
1580 possible conflicts). You can specify the base
1581 address, IRQ, and DMA settings; IRQ and DMA
1582 should be numbers, or 'auto' (for using detected
1583 settings on that particular port), or 'nofifo'
1584 (to avoid using a FIFO even if it is detected).
1585 Parallel ports are assigned in the order they
1586 are specified on the command line, starting
1589 parport_init_mode= [HW,PPT]
1590 Configure VIA parallel port to operate in
1591 a specific mode. This is necessary on Pegasos
1592 computer where firmware has no options for setting
1593 up parallel port mode and sets it to spp.
1594 Currently this function knows 686a and 8231 chips.
1595 Format: [spp|ps2|epp|ecp|ecpepp]
1597 pas2= [HW,OSS] Format:
1598 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1601 See header of drivers/scsi/pas16.c.
1604 Halt all CPUs after the first oops has been printed for
1605 the specified number of seconds. This is to be used if
1606 your oopses keep scrolling off the screen.
1611 See header of drivers/block/paride/pcd.c.
1612 See also Documentation/blockdev/paride.txt.
1614 pci=option[,option...] [PCI] various PCI subsystem options:
1615 off [X86] don't probe for the PCI bus
1616 bios [X86-32] force use of PCI BIOS, don't access
1617 the hardware directly. Use this if your machine
1618 has a non-standard PCI host bridge.
1619 nobios [X86-32] disallow use of PCI BIOS, only direct
1620 hardware access methods are allowed. Use this
1621 if you experience crashes upon bootup and you
1622 suspect they are caused by the BIOS.
1623 conf1 [X86] Force use of PCI Configuration
1625 conf2 [X86] Force use of PCI Configuration
1627 noaer [PCIE] If the PCIEAER kernel config parameter is
1628 enabled, this kernel boot option can be used to
1629 disable the use of PCIE advanced error reporting.
1630 nodomains [PCI] Disable support for multiple PCI
1631 root domains (aka PCI segments, in ACPI-speak).
1632 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1634 nomsi [MSI] If the PCI_MSI kernel config parameter is
1635 enabled, this kernel boot option can be used to
1636 disable the use of MSI interrupts system-wide.
1637 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1638 routing table. These calls are known to be buggy
1639 on several machines and they hang the machine
1640 when used, but on other computers it's the only
1641 way to get the interrupt routing table. Try
1642 this option if the kernel is unable to allocate
1643 IRQs or discover secondary PCI buses on your
1645 rom [X86] Assign address space to expansion ROMs.
1646 Use with caution as certain devices share
1647 address decoders between ROMs and other
1649 norom [X86] Do not assign address space to
1650 expansion ROMs that do not already have
1651 BIOS assigned address ranges.
1652 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1653 assigned automatically to PCI devices. You can
1654 make the kernel exclude IRQs of your ISA cards
1656 pirqaddr=0xAAAAA [X86] Specify the physical address
1657 of the PIRQ table (normally generated
1658 by the BIOS) if it is outside the
1659 F0000h-100000h range.
1660 lastbus=N [X86] Scan all buses thru bus #N. Can be
1661 useful if the kernel is unable to find your
1662 secondary buses and you want to tell it
1663 explicitly which ones they are.
1664 assign-busses [X86] Always assign all PCI bus
1665 numbers ourselves, overriding
1666 whatever the firmware may have done.
1667 usepirqmask [X86] Honor the possible IRQ mask stored
1668 in the BIOS $PIR table. This is needed on
1669 some systems with broken BIOSes, notably
1670 some HP Pavilion N5400 and Omnibook XE3
1671 notebooks. This will have no effect if ACPI
1672 IRQ routing is enabled.
1673 noacpi [X86] Do not use ACPI for IRQ routing
1674 or for PCI scanning.
1675 use_crs [X86] Use _CRS for PCI resource
1677 routeirq Do IRQ routing for all PCI devices.
1678 This is normally done in pci_enable_device(),
1679 so this option is a temporary workaround
1680 for broken drivers that don't call it.
1681 skip_isa_align [X86] do not align io start addr, so can
1682 handle more pci cards
1683 firmware [ARM] Do not re-enumerate the bus but instead
1684 just use the configuration from the
1685 bootloader. This is currently used on
1686 IXP2000 systems where the bus has to be
1687 configured a certain way for adjunct CPUs.
1688 noearly [X86] Don't do any early type 1 scanning.
1689 This might help on some broken boards which
1690 machine check when some devices' config space
1691 is read. But various workarounds are disabled
1692 and some IOMMU drivers will not work.
1693 bfsort Sort PCI devices into breadth-first order.
1694 This sorting is done to get a device
1695 order compatible with older (<= 2.4) kernels.
1696 nobfsort Don't sort PCI devices into breadth-first order.
1697 cbiosize=nn[KMG] The fixed amount of bus space which is
1698 reserved for the CardBus bridge's IO window.
1699 The default value is 256 bytes.
1700 cbmemsize=nn[KMG] The fixed amount of bus space which is
1701 reserved for the CardBus bridge's memory
1702 window. The default value is 64 megabytes.
1704 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1707 force Enable ASPM even on devices that claim not to support it.
1708 WARNING: Forcing ASPM on may cause system lockups.
1710 pcmv= [HW,PCMCIA] BadgePAD 4
1713 See Documentation/blockdev/paride.txt.
1715 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1718 See arch/parisc/kernel/pdc_chassis.c
1721 See Documentation/blockdev/paride.txt.
1724 See Documentation/blockdev/paride.txt.
1726 pirq= [SMP,APIC] Manual mp-table setup
1727 See Documentation/x86/i386/IO-APIC.txt.
1729 plip= [PPT,NET] Parallel port network link
1730 Format: { parport<nr> | timid | 0 }
1731 See also Documentation/parport.txt.
1733 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1734 Override pmtimer IOPort with a hex value.
1738 Enable PNP debug messages. This depends on the
1739 CONFIG_PNP_DEBUG_MESSAGES option.
1745 { on | off | curr | res | no-curr | no-res }
1748 [ISAPNP] Exclude IRQs for the autoconfiguration
1751 [ISAPNP] Exclude DMAs for the autoconfiguration
1753 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1754 Ranges are in pairs (I/O port base and size).
1757 [ISAPNP] Exclude memory regions for the
1759 Ranges are in pairs (memory base and size).
1762 Enables pr_debug()/dev_dbg() calls if
1763 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1764 be switched on/off via <debugfs>/dynamic_printk/modules
1766 print-fatal-signals=
1767 [KNL] debug: print fatal signals
1768 print-fatal-signals=1: print segfault info to
1772 printk.time= Show timing data prefixed to each printk message line
1773 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1775 profile= [KNL] Enable kernel profiling via /proc/profile
1776 Format: [schedule,]<number>
1777 Param: "schedule" - profile schedule points.
1778 Param: <number> - step/bucket size as a power of 2 for
1779 statistical time based profiling.
1780 Param: "sleep" - profile D-state sleeping (millisecs).
1781 Requires CONFIG_SCHEDSTATS
1782 Param: "kvm" - profile VM exits.
1784 processor.max_cstate= [HW,ACPI]
1785 Limit processor to maximum C-state
1786 max_cstate=9 overrides any DMI blacklist limit.
1788 processor.nocst [HW,ACPI]
1789 Ignore the _CST method to determine C-states,
1790 instead using the legacy FADT method
1792 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1794 See Documentation/blockdev/ramdisk.txt.
1796 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1797 probe for; one of (bare|imps|exps|lifebook|any).
1798 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1800 psmouse.resetafter= [HW,MOUSE]
1801 Try to reset the device after so many bad packets
1804 [HW,MOUSE] Set desired mouse resolution, in dpi.
1805 psmouse.smartscroll=
1806 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1807 0 = disabled, 1 = enabled (default).
1809 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1811 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1814 See Documentation/blockdev/paride.txt.
1817 [KNL] Number of legacy pty's. Overwrites compiled-in
1820 quiet [KNL] Disable most log messages
1825 See Documentation/md.txt.
1827 ramdisk_blocksize= [RAM]
1828 See Documentation/blockdev/ramdisk.txt.
1830 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1831 See Documentation/blockdev/ramdisk.txt.
1833 rcupdate.blimit= [KNL,BOOT]
1834 Set maximum number of finished RCU callbacks to process
1837 rcupdate.qhimark= [KNL,BOOT]
1838 Set threshold of queued
1839 RCU callbacks over which batch limiting is disabled.
1841 rcupdate.qlowmark= [KNL,BOOT]
1842 Set threshold of queued RCU callbacks below which
1843 batch limiting is re-enabled.
1847 Run specified binary instead of /init from the ramdisk,
1848 used for early userspace startup. See initrd.
1850 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1851 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1852 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1855 [KNL, SMP] Set scheduler's default relax_domain_level.
1856 See Documentation/cpusets.txt.
1858 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1860 reservetop= [X86-32]
1862 Reserves a hole at the top of the kernel virtual
1865 reset_devices [KNL] Force drivers to reset the underlying device
1866 during initialization.
1869 Specify the partition device for software suspend
1871 resume_offset= [SWSUSP]
1872 Specify the offset from the beginning of the partition
1873 given by "resume=" at which the swap header is located,
1874 in <PAGE_SIZE> units (needed only for swap files).
1875 See Documentation/power/swsusp-and-swap-files.txt
1877 retain_initrd [RAM] Keep initrd memory after extraction
1879 rhash_entries= [KNL,NET]
1880 Set number of hash buckets for route cache
1882 riscom8= [HW,SERIAL]
1883 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1885 ro [KNL] Mount root device read-only on boot
1887 root= [KNL] Root filesystem
1889 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1890 mount the root filesystem
1892 rootflags= [KNL] Set root filesystem mount option string
1894 rootfstype= [KNL] Set root filesystem type
1896 rootwait [KNL] Wait (indefinitely) for root device to show up.
1897 Useful for devices that are detected asynchronously
1898 (e.g. USB and MMC devices).
1900 root_plug.vendor_id=
1901 [ROOTPLUG] Override the default vendor ID
1903 root_plug.product_id=
1904 [ROOTPLUG] Override the default product ID
1907 [ROOTPLUG] Enable debugging output
1909 rw [KNL] Mount root device read-write on boot
1911 S [KNL] Run init in single mode
1914 See drivers/net/irda/sa1100_ir.c.
1916 sbni= [NET] Granch SBNI12 leased line adapter
1918 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1919 Format: <io>[,<timeout>[,<isapnp>]]
1921 scsi_debug_*= [SCSI]
1922 See drivers/scsi/scsi_debug.c.
1924 scsi_default_dev_flags=
1925 [SCSI] SCSI default device flags
1928 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1929 Format: <vendor>:<model>:<flags>
1930 (flags are integer value)
1932 scsi_logging_level= [SCSI] a bit mask of logging levels
1933 See drivers/scsi/scsi_logging.h for bits. Also
1934 settable via sysctl at dev.scsi.logging_level
1935 (/proc/sys/dev/scsi/logging_level).
1936 There is also a nice 'scsi_logging_level' script in the
1937 S390-tools package, available for download at
1938 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1940 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1941 discovered. async scans them in kernel threads,
1942 allowing boot to proceed. none ignores them, expecting
1943 user space to do the scan.
1945 selinux [SELINUX] Disable or enable SELinux at boot time.
1946 Format: { "0" | "1" }
1947 See security/selinux/Kconfig help text.
1950 Default value is set via kernel config option.
1951 If enabled at boot time, /selinux/disable can be used
1952 later to disable prior to initial policy load.
1954 selinux_compat_net =
1955 [SELINUX] Set initial selinux_compat_net flag value.
1956 Format: { "0" | "1" }
1957 0 -- use new secmark-based packet controls
1958 1 -- use legacy packet controls
1959 Default value is 0 (preferred).
1960 Value can be changed at runtime via
1961 /selinux/compat_net.
1963 serialnumber [BUGS=X86-32]
1966 Maximal number of shapers.
1968 show_msr= [x86] show boot-time MSR settings
1969 Format: { <integer> }
1970 Show boot-time (BIOS-initialized) MSR settings.
1971 The parameter means the number of CPUs to show,
1972 for example 1 means boot CPU only.
1975 See header of drivers/scsi/sim710.c.
1982 slub_debug[=options[,slabs]] [MM, SLUB]
1983 Enabling slub_debug allows one to determine the
1984 culprit if slab objects become corrupted. Enabling
1985 slub_debug can create guard zones around objects and
1986 may poison objects when not in use. Also tracks the
1987 last alloc / free. For more information see
1988 Documentation/vm/slub.txt.
1990 slub_max_order= [MM, SLUB]
1991 Determines the maximum allowed order for slabs.
1992 A high setting may cause OOMs due to memory
1993 fragmentation. For more information see
1994 Documentation/vm/slub.txt.
1996 slub_min_objects= [MM, SLUB]
1997 The minimum number of objects per slab. SLUB will
1998 increase the slab order up to slub_max_order to
1999 generate a sufficiently large slab able to contain
2000 the number of objects indicated. The higher the number
2001 of objects the smaller the overhead of tracking slabs
2002 and the less frequently locks need to be acquired.
2003 For more information see Documentation/vm/slub.txt.
2005 slub_min_order= [MM, SLUB]
2006 Determines the mininum page order for slabs. Must be
2007 lower than slub_max_order.
2008 For more information see Documentation/vm/slub.txt.
2010 slub_nomerge [MM, SLUB]
2011 Disable merging of slabs with similar size. May be
2012 necessary if there is some reason to distinguish
2013 allocs to different slabs. Debug options disable
2014 merging on their own.
2015 For more information see Documentation/vm/slub.txt.
2018 Format: <io1>[,<io2>[,...,<io8>]]
2020 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2021 attempt to substitute SMP alternatives once at boot.
2023 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2024 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2025 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2026 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2027 smsc-ircc2.ircc_irq= [HW] IRQ line
2028 smsc-ircc2.ircc_dma= [HW] DMA channel
2029 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2030 0: Toshiba Satellite 1800 (GP data pin select)
2031 1: Fast pin select (default)
2034 snd-ad1816a= [HW,ALSA]
2036 snd-ad1848= [HW,ALSA]
2038 snd-ali5451= [HW,ALSA]
2040 snd-als100= [HW,ALSA]
2042 snd-als4000= [HW,ALSA]
2044 snd-azt2320= [HW,ALSA]
2046 snd-cmi8330= [HW,ALSA]
2048 snd-cmipci= [HW,ALSA]
2050 snd-cs4231= [HW,ALSA]
2052 snd-cs4232= [HW,ALSA]
2054 snd-cs4236= [HW,ALSA]
2056 snd-cs4281= [HW,ALSA]
2058 snd-cs46xx= [HW,ALSA]
2060 snd-dt019x= [HW,ALSA]
2062 snd-dummy= [HW,ALSA]
2064 snd-emu10k1= [HW,ALSA]
2066 snd-ens1370= [HW,ALSA]
2068 snd-ens1371= [HW,ALSA]
2070 snd-es968= [HW,ALSA]
2072 snd-es1688= [HW,ALSA]
2074 snd-es18xx= [HW,ALSA]
2076 snd-es1938= [HW,ALSA]
2078 snd-es1968= [HW,ALSA]
2080 snd-fm801= [HW,ALSA]
2082 snd-gusclassic= [HW,ALSA]
2084 snd-gusextreme= [HW,ALSA]
2086 snd-gusmax= [HW,ALSA]
2090 snd-ice1712= [HW,ALSA]
2092 snd-intel8x0= [HW,ALSA]
2094 snd-interwave= [HW,ALSA]
2099 snd-korg1212= [HW,ALSA]
2101 snd-maestro3= [HW,ALSA]
2103 snd-mpu401= [HW,ALSA]
2105 snd-mtpav= [HW,ALSA]
2107 snd-nm256= [HW,ALSA]
2109 snd-opl3sa2= [HW,ALSA]
2117 snd-opti93x= [HW,ALSA]
2121 snd-rme32= [HW,ALSA]
2123 snd-rme96= [HW,ALSA]
2125 snd-rme9652= [HW,ALSA]
2131 snd-sbawe= [HW,ALSA]
2133 snd-serial= [HW,ALSA]
2135 snd-sgalaxy= [HW,ALSA]
2137 snd-sonicvibes= [HW,ALSA]
2142 snd-sun-cs4231= [HW,ALSA]
2144 snd-trident= [HW,ALSA]
2146 snd-usb-audio= [HW,ALSA,USB]
2148 snd-via82xx= [HW,ALSA]
2150 snd-virmidi= [HW,ALSA]
2152 snd-wavefront= [HW,ALSA]
2154 snd-ymfpci= [HW,ALSA]
2157 [KNL] Should the soft-lockup detector generate panics.
2159 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2160 See Documentation/sonypi.txt
2162 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2163 See Documentation/serial/specialix.txt.
2165 spia_io_base= [HW,MTD]
2171 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2173 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2174 See Documentation/scsi/st.txt.
2178 Set the STI (builtin display/keyboard on the HP-PARISC
2179 machines) console (graphic card) which should be used
2180 as the initial boot-console.
2181 See also comment in drivers/video/console/sticore.c.
2184 See comment in drivers/video/console/sticore.c.
2187 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2191 Control how the NFS server code allocates CPUs to
2192 service thread pools. Depending on how many NICs
2193 you have and where their interrupts are bound, this
2194 option will affect which CPUs will do NFS serving.
2195 Note: this parameter cannot be changed while the
2196 NFS server is running.
2198 auto the server chooses an appropriate mode
2199 automatically using heuristics
2200 global a single global pool contains all CPUs
2201 percpu one pool for each CPU
2202 pernode one pool for each NUMA node (equivalent
2203 to global on non-NUMA machines)
2205 swiotlb= [IA-64] Number of I/O TLB slabs
2209 sym53c416= [HW,SCSI]
2210 See header of drivers/scsi/sym53c416.c.
2212 sysrq_always_enabled
2214 Ignore sysrq setting - this boot parameter will
2215 neutralize any effect of /proc/sys/kernel/sysrq.
2216 Useful for debugging.
2219 See header of drivers/scsi/t128.c.
2223 test_suspend= [SUSPEND]
2224 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2225 standby suspend) as the system sleep state to briefly
2226 enter during system startup. The system is woken from
2227 this state using a wakeup-capable RTC alarm.
2229 thash_entries= [KNL,NET]
2230 Set number of hash buckets for TCP connection
2232 thermal.act= [HW,ACPI]
2233 -1: disable all active trip points in all thermal zones
2234 <degrees C>: override all lowest active trip points
2236 thermal.crt= [HW,ACPI]
2237 -1: disable all critical trip points in all thermal zones
2238 <degrees C>: override all critical trip points
2240 thermal.nocrt= [HW,ACPI]
2241 Set to disable actions on ACPI thermal zone
2242 critical and hot trip points.
2244 thermal.off= [HW,ACPI]
2245 1: disable ACPI thermal control
2247 thermal.psv= [HW,ACPI]
2248 -1: disable all passive trip points
2249 <degrees C>: override all passive trip points to this value
2251 thermal.tzp= [HW,ACPI]
2252 Specify global default ACPI thermal zone polling rate
2253 <deci-seconds>: poll all this frequency
2254 0: no polling (default)
2257 See comment before function dc390_setup() in
2258 drivers/scsi/tmscsim.c.
2262 trix= [HW,OSS] MediaTrix AudioTrix Pro
2264 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2266 turbografx.map[2|3]= [HW,JOY]
2267 TurboGraFX parallel port interface
2269 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2270 See also Documentation/input/joystick-parport.txt
2272 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2273 See header of drivers/scsi/u14-34f.c.
2282 [USB] Ignore overcurrent events (default N).
2283 Some badly-designed motherboards generate lots of
2284 bogus events, for ports that aren't wired to
2285 anything. Set this parameter to avoid log spamming.
2286 Note that genuine overcurrent events won't be
2291 Set unknown_nmi_panic=1 early on boot.
2293 usbcore.autosuspend=
2294 [USB] The autosuspend time delay (in seconds) used
2295 for newly-detected USB devices (default 2). This
2296 is the time required before an idle device will be
2297 autosuspended. Devices for which the delay is set
2298 to a negative value won't be autosuspended at all.
2300 usbcore.usbfs_snoop=
2301 [USB] Set to log all usbfs traffic (default 0 = off).
2303 usbcore.blinkenlights=
2304 [USB] Set to cycle leds on hubs (default 0 = off).
2306 usbcore.old_scheme_first=
2307 [USB] Start with the old device initialization
2308 scheme (default 0 = off).
2310 usbcore.use_both_schemes=
2311 [USB] Try the other device initialization scheme
2312 if the first one fails (default 1 = enabled).
2314 usbcore.initial_descriptor_timeout=
2315 [USB] Specifies timeout for the initial 64-byte
2316 USB_REQ_GET_DESCRIPTOR request in milliseconds
2317 (default 5000 = 5.0 seconds).
2320 [USBHID] The interval which mice are to be polled at.
2322 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2323 kernel's map of available physical RAM.
2325 vdso= [X86-32,SH,x86-64]
2326 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2327 vdso=1: enable VDSO (default)
2328 vdso=0: disable VDSO mapping
2330 vdso32= [X86-32,X86-64]
2331 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2332 vdso32=1: enable 32-bit VDSO (default)
2333 vdso32=0: disable 32-bit VDSO mapping
2336 vector=percpu: enable percpu vector domain
2338 video= [FB] Frame buffer configuration
2339 See Documentation/fb/modedb.txt.
2341 vga= [BOOT,X86-32] Select a particular video mode
2342 See Documentation/x86/i386/boot.txt and
2343 Documentation/svga.txt.
2344 Use vga=ask for menu.
2345 This is actually a boot loader parameter; the value is
2346 passed to the kernel using a special protocol.
2348 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2349 size of <nn>. This can be used to increase the
2350 minimum size (128MB on x86). It can also be used to
2351 decrease the size and leave more room for directly
2354 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2357 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2360 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2363 waveartist= [HW,OSS]
2364 Format: <io>,<irq>,<dma>,<dma2>
2367 See header of drivers/scsi/wd33c93.c.
2370 See header of drivers/scsi/wd7000.c.
2373 See Documentation/watchdog/wdt.txt.
2375 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2376 xd_geo= See header of drivers/block/xd.c.
2378 xirc2ps_cs= [NET,PCMCIA]
2380 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2382 norandmaps Don't use address space randomization
2383 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2385 ______________________________________________________________________
2389 Add documentation for ALSA options.
2390 Add more DRM drivers.
projects / linux-2.6 / blob