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 IMA Integrity measurement architecture is enabled.
48 IOSCHED More than one I/O scheduler is enabled.
49 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
50 ISAPNP ISA PnP code is enabled.
51 ISDN Appropriate ISDN support is enabled.
52 JOY Appropriate joystick support 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 FTRACE Function tracing enabled.
94 TS Appropriate touchscreen support is enabled.
95 UMS USB Mass Storage support is enabled.
96 USB USB support is enabled.
97 USBHID USB Human Interface Device support is enabled.
98 V4L Video For Linux support is enabled.
99 VGA The VGA console has been enabled.
100 VT Virtual terminal support is enabled.
101 WDT Watchdog support is enabled.
102 XT IBM PC/XT MFM hard disk support is enabled.
103 X86-32 X86-32, aka i386 architecture is enabled.
104 X86-64 X86-64 architecture is enabled.
105 More X86-64 boot options can be found in
106 Documentation/x86/x86_64/boot-options.txt .
107 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
109 In addition, the following text indicates that the option:
111 BUGS= Relates to possible processor bugs on the said processor.
112 KNL Is a kernel start-up parameter.
113 BOOT Is a boot loader parameter.
115 Parameters denoted with BOOT are actually interpreted by the boot
116 loader, and have no meaning to the kernel directly.
117 Do not modify the syntax of boot loader parameters without extreme
118 need or coordination with <Documentation/x86/boot.txt>.
120 There are also arch-specific kernel-parameters not documented here.
121 See for example <Documentation/x86/x86_64/boot-options.txt>.
123 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
124 a trailing = on the name of any parameter states that that parameter will
125 be entered as an environment variable, whereas its absence indicates that
126 it will appear as a kernel argument readable via /proc/cmdline by programs
127 running once the system is up.
129 The number of kernel parameters is not limited, but the length of the
130 complete command line (parameters including spaces etc.) is limited to
131 a fixed number of characters. This limit depends on the architecture
132 and is between 256 and 4096 characters. It is defined in the file
133 ./include/asm/setup.h as COMMAND_LINE_SIZE.
136 acpi= [HW,ACPI,X86-64,i386]
137 Advanced Configuration and Power Interface
138 Format: { force | off | ht | strict | noirq | rsdt }
139 force -- enable ACPI if default was off
140 off -- disable ACPI if default was on
141 noirq -- do not use ACPI for IRQ routing
142 ht -- run only enough ACPI to enable Hyper Threading
143 strict -- Be less tolerant of platforms that are not
144 strictly ACPI specification compliant.
145 rsdt -- prefer RSDT over (default) XSDT
147 See also Documentation/power/pm.txt, pci=noacpi
149 acpi_apic_instance= [ACPI, IOAPIC]
151 2: use 2nd APIC table, if available
152 1,0: use 1st APIC table
155 acpi_sleep= [HW,ACPI] Sleep options
156 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
157 old_ordering, s4_nonvs }
158 See Documentation/power/video.txt for information on
160 s3_beep is for debugging; it makes the PC's speaker beep
161 as soon as the kernel's real-mode entry point is called.
162 s4_nohwsig prevents ACPI hardware signature from being
163 used during resume from hibernation.
164 old_ordering causes the ACPI 1.0 ordering of the _PTS
165 control method, with respect to putting devices into
166 low power states, to be enforced (the ACPI 2.0 ordering
167 of _PTS is used by default).
168 s4_nonvs prevents the kernel from saving/restoring the
169 ACPI NVS memory during hibernation.
171 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
172 Format: { level | edge | high | low }
174 acpi_irq_balance [HW,ACPI]
175 ACPI will balance active IRQs
178 acpi_irq_nobalance [HW,ACPI]
179 ACPI will not move active IRQs (default)
182 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
184 Format: <irq>,<irq>...
186 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
187 Format: <irq>,<irq>...
189 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
191 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
192 Format: To spoof as Windows 98: ="Microsoft Windows"
194 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
195 acpi_osi="string1" # add string1 -- only one string
196 acpi_osi="!string2" # remove built-in string2
197 acpi_osi= # disable all strings
199 acpi_serialize [HW,ACPI] force serialization of AML methods
201 acpi_skip_timer_override [HW,ACPI]
202 Recognize and ignore IRQ0/pin2 Interrupt Override.
203 For broken nForce2 BIOS resulting in XT-PIC timer.
204 acpi_use_timer_override [HW,ACPI]
205 Use timer override. For some broken Nvidia NF5 boards
206 that require a timer override, but don't have
209 acpi_backlight= [HW,ACPI]
210 acpi_backlight=vendor
212 If set to vendor, prefer vendor specific driver
213 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
214 of the ACPI video.ko driver.
216 acpi_display_output= [HW,ACPI]
217 acpi_display_output=vendor
218 acpi_display_output=video
221 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
222 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
224 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
225 debug output. Bits in debug_layer correspond to a
226 _COMPONENT in an ACPI source file, e.g.,
227 #define _COMPONENT ACPI_PCI_COMPONENT
228 Bits in debug_level correspond to a level in
229 ACPI_DEBUG_PRINT statements, e.g.,
230 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
231 The debug_level mask defaults to "info". See
232 Documentation/acpi/debug.txt for more information about
233 debug layers and levels.
235 Enable processor driver info messages:
236 acpi.debug_layer=0x20000000
237 Enable PCI/PCI interrupt routing info messages:
238 acpi.debug_layer=0x400000
239 Enable AML "Debug" output, i.e., stores to the Debug
240 object while interpreting AML:
241 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
242 Enable all messages related to ACPI hardware:
243 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
245 Some values produce so much output that the system is
246 unusable. The "log_buf_len" parameter may be useful
247 if you need to capture more output.
249 acpi.power_nocheck= [HW,ACPI]
250 Format: 1/0 enable/disable the check of power state.
251 On some bogus BIOS the _PSC object/_STA object of
252 power resource can't return the correct device power
253 state. In such case it is unneccessary to check its
254 power state again in power transition.
255 1 : disable the power state check
257 acpi_pm_good [X86-32,X86-64]
258 Override the pmtimer bug detection: force the kernel
259 to assume that this machine's pmtimer latches its value
260 and always returns good values.
263 { off | try_unsupported }
264 off: disable AGP support
265 try_unsupported: try to drive unsupported chipsets
266 (may crash computer or cause data corruption)
268 enable_timer_pin_1 [i386,x86-64]
269 Enable PIN 1 of APIC timer
270 Can be useful to work around chipset bugs
271 (in particular on some ATI chipsets).
272 The kernel tries to set a reasonable default.
274 disable_timer_pin_1 [i386,x86-64]
275 Disable PIN 1 of APIC timer
276 Can be useful to work around chipset bugs.
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
282 See header of drivers/scsi/advansys.c.
284 advwdt= [HW,WDT] Advantech WDT
285 Format: <iostart>,<iostop>
287 aedsp16= [HW,OSS] Audio Excel DSP 16
288 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
289 See also header of sound/oss/aedsp16.c.
292 See Documentation/scsi/aha152x.txt.
295 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
298 See Documentation/scsi/aic7xxx.txt.
301 See Documentation/scsi/aic79xx.txt.
303 amd_iommu= [HW,X86-84]
304 Pass parameters to the AMD IOMMU driver in the system.
306 isolate - enable device isolation (each device, as far
307 as possible, will get its own protection
309 share - put every device behind one IOMMU into the
310 same protection domain
311 fullflush - enable flushing of IO/TLB entries when
312 they are unmapped. Otherwise they are
313 flushed before they will be reused, which
316 amd_iommu_size= [HW,X86-64]
317 Define the size of the aperture for the AMD IOMMU
318 driver. Possible values are:
319 '32M', '64M' (default), '128M', '256M', '512M', '1G'
321 amijoy.map= [HW,JOY] Amiga joystick support
322 Map of devices attached to JOY0DAT and JOY1DAT
324 See also Documentation/kernel/input/joystick.txt
326 analog.map= [HW,JOY] Analog joystick and gamepad support
327 Specifies type or capabilities of an analog joystick
328 connected to one of 16 gameports
329 Format: <type1>,<type2>,..<type16>
332 Power management functions (SPARCstation-4/5 + deriv.)
334 Disable APC CPU standby support. SPARCstation-Fox does
335 not play well with APC CPU idle - disable it if you have
336 APC and your system crashes randomly.
338 apic= [APIC,i386] Advanced Programmable Interrupt Controller
339 Change the output verbosity whilst booting
340 Format: { quiet (default) | verbose | debug }
341 Change the amount of debugging information output
342 when initialising the APIC and IO-APIC components.
344 apm= [APM] Advanced Power Management
345 See header of arch/x86/kernel/apm_32.c.
347 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
348 Format: <io>,<irq>,<nodeID>
352 atarimouse= [HW,MOUSE] Atari Mouse
354 atascsi= [HW,SCSI] Atari SCSI
356 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
357 EzKey and similar keyboards
359 atkbd.reset= [HW] Reset keyboard during initialization
361 atkbd.set= [HW] Select keyboard code set
362 Format: <int> (2 = AT (default), 3 = PS/2)
364 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
367 atkbd.softraw= [HW] Choose between synthetic and real raw mode
368 Format: <bool> (0 = real, 1 = synthetic (default))
370 atkbd.softrepeat= [HW]
371 Use software keyboard repeat
375 baycom_epp= [HW,AX25]
378 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
380 See header of drivers/net/hamradio/baycom_par.c.
382 baycom_ser_fdx= [HW,AX25]
383 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
384 Format: <io>,<irq>,<mode>[,<baud>]
385 See header of drivers/net/hamradio/baycom_ser_fdx.c.
387 baycom_ser_hdx= [HW,AX25]
388 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
389 Format: <io>,<irq>,<mode>
390 See header of drivers/net/hamradio/baycom_ser_hdx.c.
392 boot_delay= Milliseconds to delay each printk during boot.
393 Values larger than 10 seconds (10000) are changed to
397 bootmem_debug [KNL] Enable bootmem allocator debug messages.
399 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
400 bttv.radio= Most important insmod options are available as
402 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
403 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
406 See drivers/scsi/BusLogic.c, comment before function
407 BusLogic_ParseDriverOptions().
409 c101= [NET] Moxa C101 synchronous serial card
411 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
412 Sometimes CPU hardware bugs make them report the cache
413 size incorrectly. The kernel will attempt work arounds
414 to fix known problems, but for some CPUs it is not
415 possible to determine what the correct size should be.
416 This option provides an override for these situations.
418 security= [SECURITY] Choose a security module to enable at boot.
419 If this boot parameter is not specified, only the first
420 security module asking for security registration will be
421 loaded. An invalid security module name will be treated
422 as if no module has been chosen.
425 [SECURITY] Disable capabilities. This would normally
426 be used only if an alternative security model is to be
427 configured. Potentially dangerous and should only be
428 used if you are entirely sure of the consequences.
430 ccw_timeout_log [S390]
431 See Documentation/s390/CommonIO for details.
433 cgroup_disable= [KNL] Disable a particular controller
434 Format: {name of the controller(s) to disable}
435 {Currently supported controllers - "memory"}
437 checkreqprot [SELINUX] Set initial checkreqprot flag value.
438 Format: { "0" | "1" }
439 See security/selinux/Kconfig help text.
440 0 -- check protection applied by kernel (includes
441 any implied execute protection).
442 1 -- check protection requested by application.
443 Default value is set via a kernel config option.
444 Value can be changed at runtime via
445 /selinux/checkreqprot.
448 See Documentation/s390/CommonIO for details.
450 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
452 Forces specified clocksource (if available) to be used
453 when calculating gettimeofday(). If specified
454 clocksource is not available, it defaults to PIT.
455 Format: { pit | tsc | cyclone | pmtmr }
457 clocksource= [GENERIC_TIME] Override the default clocksource
459 Override the default clocksource and use the clocksource
460 with the name specified.
461 Some clocksource names to choose from, depending on
463 [all] jiffies (this is the base, fallback clocksource)
465 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
466 pxa_timer,timer3,32k_counter,timer0_1
468 [X86-32] pit,hpet,tsc,vmi-timer;
469 scx200_hrt on Geode; cyclone on IBM x440
477 clearcpuid=BITNUM [X86]
478 Disable CPUID feature X for the kernel. See
479 arch/x86/include/asm/cpufeature.h for the valid bit
480 numbers. Note the Linux specific bits are not necessarily
481 stable over kernel options, but the vendor specific
483 Also note that user programs calling CPUID directly
484 or using the feature without checking anything
485 will still see it. This just prevents it from
486 being used by the kernel or shown in /proc/cpuinfo.
487 Also note the kernel might malfunction if you disable
490 code_bytes [IA32/X86_64] How many bytes of object code to print
495 hpet= [X86-32,HPET] option to control HPET usage
496 Format: { enable (default) | disable | force |
498 disable: disable HPET and use PIT instead
499 force: allow force enabled of undocumented chips (ICH4,
501 verbose: show contents of HPET registers during setup
503 com20020= [HW,NET] ARCnet - COM20020 chipset
505 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
507 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
511 ARCnet - COM90xx chipset (memory-mapped buffers)
512 Format: <io>[,<irq>[,<memstart>]]
514 condev= [HW,S390] console device
517 console= [KNL] Output console device and options.
519 tty<n> Use the virtual console device <n>.
523 Use the specified serial port. The options are of
524 the form "bbbbpnf", where "bbbb" is the baud rate,
525 "p" is parity ("n", "o", or "e"), "n" is number of
526 bits, and "f" is flow control ("r" for RTS or
527 omit it). Default is "9600n8".
529 See Documentation/serial-console.txt for more
531 Documentation/networking/netconsole.txt for an
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 switching to the matching ttyS device later. The
539 options are the same as for ttyS, above.
541 If the device connected to the port is not a TTY but a braille
542 device, prepend "brl," before the device type, for instance
544 For now, only VisioBraille is supported.
546 earlycon= [KNL] Output early console device and options.
547 uart[8250],io,<addr>[,options]
548 uart[8250],mmio,<addr>[,options]
549 Start an early, polled-mode console on the 8250/16550
550 UART at the specified I/O port or MMIO address.
551 The options are the same as for ttyS, above.
554 [HW] Never suspend the console
555 Disable suspending of consoles during suspend and
556 hibernate operations. Once disabled, debugging
557 messages can reach various consoles while the rest
558 of the system is being put to sleep (ie, while
559 debugging driver suspend/resume hooks). This may
560 not work reliably with all consoles, but is known
561 to work with serial and VGA consoles.
564 [KNL] Change the default value for
565 /proc/<pid>/coredump_filter.
566 See also Documentation/filesystems/proc.txt.
568 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
570 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
572 crashkernel=nn[KMG]@ss[KMG]
573 [KNL] Reserve a chunk of physical memory to
574 hold a kernel to switch to with kexec on panic.
576 crashkernel=range1:size1[,range2:size2,...][@offset]
577 [KNL] Same as above, but depends on the memory
578 in the running system. The syntax of range is
579 start-[end] where start and end are both
580 a memory unit (amount[KMG]). See also
581 Documentation/kdump/kdump.txt for a example.
586 cs89x0_media= [HW,NET]
587 Format: { rj45 | aui | bnc }
590 See header of drivers/s390/block/dasd_devmap.c.
592 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
593 (one device per port)
594 Format: <port#>,<type>
595 See also Documentation/input/joystick-parport.txt
597 debug [KNL] Enable kernel debugging (events log level).
600 [KNL] verbose self-tests
602 Print debugging info while doing the locking API
604 We default to 0 (no extra messages), setting it to
605 1 will print _a lot_ more information - normally
606 only useful to kernel developers.
608 debug_objects [KNL] Enable object debugging
610 debugpat [X86] Enable PAT debugging
612 decnet.addr= [HW,NET]
613 Format: <area>[,<node>]
614 See also Documentation/networking/decnet.txt.
617 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
618 Change the default blue palette of the console.
619 This is a 16-member array composed of values
623 Format: <green0>,<green1>,<green2>,...,<green15>
624 Change the default green palette of the console.
625 This is a 16-member array composed of values
629 Format: <red0>,<red1>,<red2>,...,<red15>
630 Change the default red palette of the console.
631 This is a 16-member array composed of values
637 Set system-wide default UTF-8 mode for all tty's.
638 Default is 1, i.e. UTF-8 mode is enabled for all
639 newly opened terminals.
642 Set number of hash buckets for dentry cache.
645 IO parameters + enable/disable command.
647 digiepca= [HW,SERIAL]
648 See drivers/char/README.epca and
649 Documentation/serial/digiepca.txt.
651 disable_mtrr_cleanup [X86]
652 enable_mtrr_cleanup [X86]
653 The kernel tries to adjust MTRR layout from continuous
654 to discrete, to make X server driver able to add WB
655 entry later. This parameter enables/disables that.
657 mtrr_chunk_size=nn[KMG] [X86]
658 used for mtrr cleanup. It is largest continous chunk
659 that could hold holes aka. UC entries.
661 mtrr_gran_size=nn[KMG] [X86]
662 Used for mtrr cleanup. It is granularity of mtrr block.
664 Large value could prevent small alignment from
667 mtrr_spare_reg_nr=n [X86]
669 Range: 0,7 : spare reg number
671 Used for mtrr cleanup. It is spare mtrr entries number.
672 Set to 2 or more if your graphical card needs more.
674 disable_mtrr_trim [X86, Intel and AMD only]
675 By default the kernel will trim any uncacheable
676 memory out of your available memory pool based on
677 MTRR settings. This parameter disables that behavior,
678 possibly causing your machine to run very slowly.
680 dmasound= [HW,OSS] Sound subsystem buffers
686 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
688 earlyprintk=serial[,ttySn[,baudrate]]
691 Append ",keep" to not disable it when the real console
694 Only vga or serial or usb debug port at a time.
696 Currently only ttyS0 and ttyS1 are supported.
698 Interaction with the standard serial driver is not
701 The VGA output is eventually overwritten by the real
707 Format: {"off" | "on" | "skip[mbr]"}
709 eisa_irq_edge= [PARISC,HW]
710 See header of drivers/parisc/eisa.c.
713 See comment before function elanfreq_setup() in
714 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
717 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
718 See Documentation/block/as-iosched.txt and
719 Documentation/block/deadline-iosched.txt for details.
721 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
722 Specifies physical address of start of kernel core
723 image elf header. Generally kexec loader will
724 pass this option to capture kernel.
725 See Documentation/kdump/kdump.txt for details.
727 enforcing [SELINUX] Set initial enforcing status.
729 See security/selinux/Kconfig help text.
730 0 -- permissive (log only, no denials).
731 1 -- enforcing (deny and log).
733 Value can be changed at runtime via /selinux/enforce.
735 ether= [HW,NET] Ethernet cards parameters
736 This option is obsoleted by the "netdev=" option, which
737 has equivalent usage. See its documentation for details.
739 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
744 fail_make_request=[KNL]
745 General fault injection mechanism.
746 Format: <interval>,<probability>,<space>,<times>
747 See also /Documentation/fault-injection/.
750 See header of drivers/scsi/fd_mcs.c.
753 See header of drivers/scsi/fdomain.c.
756 See Documentation/blockdev/floppy.txt.
758 force_pal_cache_flush
759 [IA-64] Avoid check_sal_cache_flush which may hang on
760 buggy SAL_CACHE_FLUSH implementations. Using this
761 parameter will force ia64_sal_cache_flush to call
762 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
765 [ftrace] will set and start the specified tracer
766 as early as possible in order to facilitate early
770 [ftrace] will dump the trace buffers on oops.
773 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
774 support via parallel port (up to 5 devices per port)
775 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
776 See also Documentation/input/joystick-parport.txt
780 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
785 See header of drivers/scsi/gdth.c.
787 gpt [EFI] Forces disk with valid GPT signature but
788 invalid Protective MBR to be treated as GPT.
792 hashdist= [KNL,NUMA] Large hashes allocated during boot
793 are distributed across NUMA nodes. Defaults on
794 for IA-64, off otherwise.
795 Format: 0 | 1 (for off | on)
797 hcl= [IA-64] SGI's Hardware Graph compatibility layer
799 hd= [EIDE] (E)IDE hard drive subsystem geometry
800 Format: <cyl>,<head>,<sect>
802 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
803 size of <nn>. This works even on boxes that have no
804 highmem otherwise. This also works to reduce highmem
805 size on bigger boxes.
807 highres= [KNL] Enable/disable high resolution timer mode.
808 Valid parameters: "on", "off"
812 See Documentation/isdn/README.HiSax.
814 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
815 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
816 On x86-64 and powerpc, this option can be specified
817 multiple times interleaved with hugepages= to reserve
818 huge pages of different sizes. Valid pages sizes on
819 x86-64 are 2M (when the CPU supports "pse") and 1G
820 (when the CPU supports the "pdpe1gb" cpuinfo flag)
821 Note that 1GB pages can only be allocated at boot time
822 using hugepages= and not freed afterwards.
824 [same as hugepagesz=] The size of the default
825 HugeTLB page size. This is the size represented by
826 the legacy /proc/ hugepages APIs, used for SHM, and
827 default size when mounting hugetlbfs filesystems.
828 Defaults to the default architecture's huge page size
833 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
834 terminal devices. Valid values: 0..8
835 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
836 If specified, z/VM IUCV HVC accepts connections
837 from listed z/VM user IDs only.
839 i8042.debug [HW] Toggle i8042 debug mode
840 i8042.direct [HW] Put keyboard port into non-translated mode
841 i8042.dumbkbd [HW] Pretend that controller can only read data from
842 keyboard and cannot control its state
843 (Don't attempt to blink the leds)
844 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
845 i8042.nokbd [HW] Don't check/create keyboard port
846 i8042.noloop [HW] Disable the AUX Loopback command while probing
848 i8042.nomux [HW] Don't check presence of an active multiplexing
850 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
853 [HW] Frequency with which keyboard LEDs should blink
854 when kernel panics (default is 0.5 sec)
855 i8042.reset [HW] Reset the controller during init and cleanup
856 i8042.unlock [HW] Unlock (ignore) the keylock
860 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
861 indicates that the driver is running on unsupported
863 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
864 does not match list of supported models.
866 [HW] Report power status in /proc/i8k
867 (disabled by default)
868 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
871 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
872 See Documentation/mca.txt.
875 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
877 ide-core.nodma= [HW] (E)IDE subsystem
878 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
879 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
880 .chs .ignore_cable are additional options
881 See Documentation/ide/ide.txt.
883 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
884 See Documentation/ide/ide.txt.
887 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
888 Poll forces a polling idle loop that can slightly
889 improve the performance of waking up a idle CPU, but
890 will use a lot of power and make the system run hot.
892 idle=mwait: On systems which support MONITOR/MWAIT but
893 the kernel chose to not use it because it doesn't save
894 as much power as a normal idle loop, use the
895 MONITOR/MWAIT idle loop anyways. Performance should be
896 the same as idle=poll.
897 idle=halt: Halt is forced to be used for CPU idle.
898 In such case C2/C3 won't be used again.
899 idle=nomwait: Disable mwait for CPU C-states
901 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
902 Claim all unknown PCI IDE storage controllers.
904 ignore_loglevel [KNL]
905 Ignore loglevel setting - this will print /all/
906 kernel messages to the console. Useful for debugging.
909 Set number of hash buckets for inode cache.
912 Format: { "0" | "1" }
913 0 -- integrity auditing messages. (Default)
914 1 -- enable informational integrity auditing messages.
917 Formt: { "sha1" | "md5" }
921 See header of drivers/scsi/in2000.c.
925 Run specified binary instead of /sbin/init as init
928 initcall_debug [KNL] Trace initcalls as they are executed. Useful
929 for working out where the kernel is dying during
932 initrd= [BOOT] Specify the location of the initial ramdisk
934 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
939 iomem= Disable strict checking of access to MMIO memory
940 strict regions from userspace.
956 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
958 Enable intel iommu driver.
960 Disable intel iommu driver.
961 igfx_off [Default Off]
962 By default, gfx is mapped as normal device. If a gfx
963 device has a dedicated DMAR unit, the DMAR unit is
964 bypassed by not enabling DMAR with this option. In
965 this case, gfx device will use physical address for
968 With this option iommu will not optimize to look
969 for io virtual address below 32 bit forcing dual
970 address cycle on pci bus for cards supporting greater
971 than 32 bit addressing. The default is to look
972 for translation below 32 bit and if not available
973 then look in the higher range.
975 With this option on every unmap_single operation will
976 result in a hardware IOTLB flush operation as opposed
977 to batching them for performance.
979 io_delay= [X86-32,X86-64] I/O delay method
981 Standard port 0x80 based delay
983 Alternate port 0xed based delay (needed on some systems)
985 Simple two microseconds delay
989 io7= [HW] IO7 for Marvel based alpha systems
990 See comment before marvel_specify_io7 in
991 arch/alpha/kernel/core_marvel.c.
994 See Documentation/filesystems/nfsroot.txt.
996 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
997 See comment before ip2_setup() in
998 drivers/char/ip2/ip2base.c.
1000 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1001 See header of drivers/scsi/ips.c.
1003 ports= [IP_VS_FTP] IPVS ftp helper module
1005 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1007 Format: <port>,<port>....
1010 When an interrupt is not handled search all handlers
1011 for it. Intended to get systems with badly broken
1015 When an interrupt is not handled search all handlers
1016 for it. Also check all handlers each timer
1017 interrupt. Intended to get systems with badly broken
1021 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1023 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1025 <cpu number>,...,<cpu number>
1027 <cpu number>-<cpu number>
1028 (must be a positive range in ascending order)
1030 <cpu number>,...,<cpu number>-<cpu number>
1032 This option can be used to specify one or more CPUs
1033 to isolate from the general SMP balancing and scheduling
1034 algorithms. You can move a process onto or off an
1035 "isolated" CPU via the CPU affinity syscalls or cpuset.
1036 <cpu number> begins at 0 and the maximum value is
1037 "number of CPUs in system - 1".
1039 This option is the preferred way to isolate CPUs. The
1040 alternative -- manually setting the CPU mask of all
1041 tasks in the system -- can cause problems and
1042 suboptimal load balancer performance.
1046 js= [HW,JOY] Analog joystick
1047 See Documentation/input/joystick.txt.
1049 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1050 specifies the amount of memory usable by the kernel
1051 for non-movable allocations. The requested amount is
1052 spread evenly throughout all nodes in the system. The
1053 remaining memory in each node is used for Movable
1054 pages. In the event, a node is too small to have both
1055 kernelcore and Movable pages, kernelcore pages will
1056 take priority and other nodes will have a larger number
1057 of kernelcore pages. The Movable zone is used for the
1058 allocation of pages that may be reclaimed or moved
1059 by the page migration subsystem. This means that
1060 HugeTLB pages may not be allocated from this zone.
1061 Note that allocations like PTEs-from-HighMem still
1062 use the HighMem zone if it exists, and the Normal
1063 zone if it does not.
1065 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1066 is similar to kernelcore except it specifies the
1067 amount of memory used for migratable allocations.
1068 If both kernelcore and movablecore is specified,
1069 then kernelcore will be at *least* the specified
1070 value but may be more. If movablecore on its own
1071 is specified, the administrator must be careful
1072 that the amount of memory usable for all allocations
1077 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1080 kgdboc= [HW] kgdb over consoles.
1081 Requires a tty driver that supports console polling.
1082 (only serial suported for now)
1083 Format: <serial_device>[,baud]
1085 kmac= [MIPS] korina ethernet MAC address.
1086 Configure the RouterBoard 532 series on-chip
1087 Ethernet adapter MAC address.
1093 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1096 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1099 libata.dma= [LIBATA] DMA control
1100 libata.dma=0 Disable all PATA and SATA DMA
1101 libata.dma=1 PATA and SATA Disk DMA only
1102 libata.dma=2 ATAPI (CDROM) DMA only
1103 libata.dma=4 Compact Flash DMA only
1104 Combinations also work, so libata.dma=3 enables DMA
1105 for disks and CDROMs, but not CFs.
1107 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1111 libata.force= [LIBATA] Force configurations. The format is comma
1112 separated list of "[ID:]VAL" where ID is
1113 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1114 matching port, link or device. Basically, it matches
1115 the ATA ID string printed on console by libata. If
1116 the whole ID part is omitted, the last PORT and DEVICE
1117 values are used. If ID hasn't been specified yet, the
1118 configuration applies to all ports, links and devices.
1120 If only DEVICE is omitted, the parameter applies to
1121 the port and all links and devices behind it. DEVICE
1122 number of 0 either selects the first device or the
1123 first fan-out link behind PMP device. It does not
1124 select the host link. DEVICE number of 15 selects the
1125 host link and device attached to it.
1127 The VAL specifies the configuration to force. As long
1128 as there's no ambiguity shortcut notation is allowed.
1129 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1130 The following configurations can be forced.
1132 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1133 Any ID with matching PORT is used.
1135 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1137 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1138 udma[/][16,25,33,44,66,100,133] notation is also
1141 * [no]ncq: Turn on or off NCQ.
1143 * nohrst, nosrst, norst: suppress hard, soft
1146 If there are multiple matching configurations changing
1147 the same attribute, the last one is used.
1149 lmb=debug [KNL] Enable lmb debug messages.
1151 load_ramdisk= [RAM] List of ramdisks to load from floppy
1152 See Documentation/blockdev/ramdisk.txt.
1154 lockd.nlm_grace_period=P [NFS] Assign grace period.
1157 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1160 lockd.nlm_timeout=T [NFS] Assign timeout value.
1163 lockd.nlm_udpport=M [NFS] Assign UDP port.
1166 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1169 loglevel= All Kernel Messages with a loglevel smaller than the
1170 console loglevel will be printed to the console. It can
1171 also be changed with klogd or other programs. The
1172 loglevels are defined as follows:
1174 0 (KERN_EMERG) system is unusable
1175 1 (KERN_ALERT) action must be taken immediately
1176 2 (KERN_CRIT) critical conditions
1177 3 (KERN_ERR) error conditions
1178 4 (KERN_WARNING) warning conditions
1179 5 (KERN_NOTICE) normal but significant condition
1180 6 (KERN_INFO) informational
1181 7 (KERN_DEBUG) debug-level messages
1183 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1184 Format: { n | nk | nM }
1185 n must be a power of two. The default size
1186 is set in the kernel config file.
1188 logo.nologo [FB] Disables display of the built-in Linux logo.
1189 This may be used to provide more screen space for
1190 kernel log messages and is useful when debugging
1191 kernel boot problems.
1193 lp=0 [LP] Specify parallel ports to use, e.g,
1194 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1195 lp=reset first parallel port). 'lp=0' disables the
1196 lp=auto printer driver. 'lp=reset' (which can be
1197 specified in addition to the ports) causes
1198 attached printers to be reset. Using
1199 lp=port1,port2,... specifies the parallel ports
1200 to associate lp devices with, starting with
1201 lp0. A port specification may be 'none' to skip
1202 that lp device, or a parport name such as
1203 'parport0'. Specifying 'lp=auto' instead of a
1204 port specification list means that device IDs
1205 from each port should be examined, to see if
1206 an IEEE 1284-compliant printer is attached; if
1207 so, the driver will manage that printer.
1208 See also header of drivers/char/lp.c.
1211 Sets loops_per_jiffy to given constant, thus avoiding
1212 time-consuming boot-time autodetection (up to 250 ms per
1213 CPU). 0 enables autodetection (default). To determine
1214 the correct value for your kernel, boot with normal
1215 autodetection and see what value is printed. Note that
1216 on SMP systems the preset will be applied to all CPUs,
1217 which is likely to cause problems if your CPUs need
1218 significantly divergent settings. An incorrect value
1219 will cause delays in the kernel to be wrong, leading to
1220 unpredictable I/O errors and other breakage. Although
1221 unlikely, in the extreme case this might damage your
1225 Format: <io>,<irq>,<dma>
1227 mac5380= [HW,SCSI] Format:
1228 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1230 machvec= [IA64] Force the use of a particular machine-vector
1231 (machvec) in a generic kernel.
1232 Example: machvec=hpzx1_swiotlb
1234 max_loop= [LOOP] Maximum number of loopback devices that can
1238 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1239 should make use of. maxcpus=n : n >= 0 limits the
1240 kernel to using 'n' processors. n=0 is a special case,
1241 it is equivalent to "nosmp", which also disables
1244 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1245 or equal to this physical address is ignored.
1247 max_luns= [SCSI] Maximum number of LUNs to probe.
1248 Should be between 1 and 2^32-1.
1251 [SCSI] Maximum number of LUNs received.
1252 Should be between 1 and 16384.
1256 mce [X86-32] Machine Check Exception
1258 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1260 md= [HW] RAID subsystems devices and level
1261 See Documentation/md.txt.
1264 Format: <first>,<last>
1265 Specifies range of consoles to be captured by the MDA.
1267 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1268 Amount of memory to be used when the kernel is not able
1269 to see the whole system memory or for test.
1270 [X86-32] Use together with memmap= to avoid physical
1271 address space collisions. Without memmap= PCI devices
1272 could be placed at addresses belonging to unused RAM.
1274 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1278 [KNL,SH] Allow user to override the default size for
1279 per-device physically contiguous DMA buffers.
1281 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1282 E820 memory map, as specified by the user.
1283 Such memmap=exactmap lines can be constructed based on
1284 BIOS output or other requirements. See the memmap=nn@ss
1287 memmap=nn[KMG]@ss[KMG]
1288 [KNL] Force usage of a specific region of memory
1289 Region of memory to be used, from ss to ss+nn.
1291 memmap=nn[KMG]#ss[KMG]
1292 [KNL,ACPI] Mark specific memory as ACPI data.
1293 Region of memory to be used, from ss to ss+nn.
1295 memmap=nn[KMG]$ss[KMG]
1296 [KNL,ACPI] Mark specific memory as reserved.
1297 Region of memory to be used, from ss to ss+nn.
1298 Example: Exclude memory from 0x18690000-0x1869ffff
1299 memmap=64K$0x18690000
1301 memmap=0x10000$0x18690000
1303 memory_corruption_check=0/1 [X86]
1304 Some BIOSes seem to corrupt the first 64k of
1305 memory when doing things like suspend/resume.
1306 Setting this option will scan the memory
1307 looking for corruption. Enabling this will
1308 both detect corruption and prevent the kernel
1309 from using the memory being corrupted.
1310 However, its intended as a diagnostic tool; if
1311 repeatable BIOS-originated corruption always
1312 affects the same memory, you can use memmap=
1313 to prevent the kernel from using that memory.
1315 memory_corruption_check_size=size [X86]
1316 By default it checks for corruption in the low
1317 64k, making this memory unavailable for normal
1318 use. Use this parameter to scan for
1319 corruption in more or less memory.
1321 memory_corruption_check_period=seconds [X86]
1322 By default it checks for corruption every 60
1323 seconds. Use this parameter to check at some
1324 other rate. 0 disables periodic checking.
1326 memtest= [KNL,X86] Enable memtest
1328 default : 0 <disable>
1329 Specifies the number of memtest passes to be
1330 performed. Each pass selects another test
1331 pattern from a given set of patterns. Memtest
1332 fills the memory with this pattern, validates
1333 memory contents and reserves bad memory
1334 regions that are detected.
1336 meye.*= [HW] Set MotionEye Camera parameters
1337 See Documentation/video4linux/meye.txt.
1339 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1340 Multi-Function General Purpose Timers on AMD Geode
1343 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1344 the BIOS has incorrectly applied a workaround. TinyBIOS
1345 version 0.98 is known to be affected, 0.99 fixes the
1346 problem by letting the user disable the workaround.
1350 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1351 physical address is ignored.
1354 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1355 parameter allows control of the logging verbosity for
1356 the additional memory initialisation checks. A value
1357 of 0 disables mminit logging and a level of 4 will
1358 log everything. Information is printed at KERN_DEBUG
1359 so loglevel=8 may also need to be specified.
1362 [MOUSE] Maximum time between finger touching and
1363 leaving touchpad surface for touch to be considered
1364 a tap and be reported as a left button click (for
1365 touchpads working in absolute mode only).
1367 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1368 reporting absolute coordinates, such as tablets
1369 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1370 reporting absolute coordinates, such as tablets
1375 MTD_Partition= [MTD]
1376 Format: <name>,<region-number>,<size>,<offset>
1378 MTD_Region= [MTD] Format:
1379 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1382 See drivers/mtd/cmdlinepart.c.
1385 ARM/S3C2412 JIVE boot control
1387 See arch/arm/mach-s3c2412/mach-jive.c
1389 mtouchusb.raw_coordinates=
1390 [HW] Make the MicroTouch USB driver use raw coordinates
1391 ('y', default) or cooked coordinates ('n')
1393 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1396 See header of drivers/scsi/NCR_D700.c.
1400 ncr53c400= [HW,SCSI]
1402 ncr53c400a= [HW,SCSI]
1404 ncr53c406a= [HW,SCSI]
1406 ncr53c8xx= [HW,SCSI]
1408 netdev= [NET] Network devices parameters
1409 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1410 Note that mem_start is often overloaded to mean
1411 something different and driver-specific.
1412 This usage is only documented in each driver source
1416 [NETFILTER] Enable connection tracking flow accounting
1417 0 to disable accounting
1418 1 to enable accounting
1419 Default value depends on CONFIG_NF_CT_ACCT that is
1420 going to be removed in 2.6.29.
1423 See Documentation/filesystems/nfsroot.txt.
1425 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1426 See Documentation/filesystems/nfsroot.txt.
1428 nfs.callback_tcpport=
1429 [NFS] set the TCP port on which the NFSv4 callback
1430 channel should listen.
1432 nfs.idmap_cache_timeout=
1433 [NFS] set the maximum lifetime for idmapper cache
1437 [NFS] enable 64-bit inode numbers.
1438 If zero, the NFS client will fake up a 32-bit inode
1439 number for the readdir() and stat() syscalls instead
1440 of returning the full 64-bit number.
1441 The default is to return 64-bit inode numbers.
1443 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1444 when a NMI is triggered.
1445 Format: [state][,regs][,debounce][,die]
1447 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1448 Format: [panic,][num]
1450 0 - turn nmi_watchdog off
1451 1 - use the IO-APIC timer for the NMI watchdog
1452 2 - use the local APIC for the NMI watchdog using
1453 a performance counter. Note: This will use one performance
1454 counter and the local APIC's performance vector.
1455 When panic is specified panic when an NMI watchdog timeout occurs.
1456 This is useful when you use a panic=... timeout and need the box
1458 Instead of 1 and 2 it is possible to use the following
1459 symbolic names: lapic and ioapic
1460 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1462 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1463 emulation library even if a 387 maths coprocessor
1466 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1467 caches in the slab allocator. Saves per-node memory,
1468 but will impact performance.
1472 noapic [SMP,APIC] Tells the kernel to not make use of any
1473 IOAPICs that may be present in the system.
1475 nobats [PPC] Do not use BATs for mapping kernel lowmem
1476 on "Classic" PPC cores.
1480 nodelayacct [KNL] Disable per-task delay accounting
1482 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1484 nodsp [SH] Disable hardware DSP at boot time.
1486 noefi [X86-32,X86-64] Disable EFI runtime services support.
1490 noexec [X86-32,X86-64]
1491 On X86-32 available only on PAE configured kernels.
1492 noexec=on: enable non-executable mappings (default)
1493 noexec=off: disable non-executable mappings
1496 This affects only 32-bit executables.
1497 noexec32=on: enable non-executable mappings (default)
1498 read doesn't imply executable mappings
1499 noexec32=off: disable non-executable mappings
1500 read implies executable mappings
1502 nofpu [SH] Disable hardware FPU at boot time.
1504 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1505 register save and restore. The kernel will only save
1506 legacy floating-point registers on task switch.
1508 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1512 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1513 instruction doesn't work correctly and not to
1516 no_file_caps Tells the kernel not to honor file capabilities. The
1517 only way then for a file to be executed with privilege
1518 is to be setuid root or executed by root.
1520 nohalt [IA-64] Tells the kernel not to use the power saving
1521 function PAL_HALT_LIGHT when idle. This increases
1522 power-consumption. On the positive side, it reduces
1523 interrupt wake-up latency, which may improve performance
1524 in certain environments such as networked servers or
1527 nohz= [KNL] Boottime enable/disable dynamic ticks
1528 Valid arguments: on, off
1531 noirqdebug [X86-32] Disables the code which attempts to detect and
1532 disable unhandled interrupt sources.
1534 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1535 broken timer IRQ sources.
1537 noisapnp [ISAPNP] Disables ISA PnP code.
1539 noinitrd [RAM] Tells the kernel not to load any configured
1544 nojitter [IA64] Disables jitter checking for ITC timers.
1546 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1548 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1550 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1552 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1553 default x2apic cluster mode on platforms
1556 noltlbs [PPC] Do not use large page/tlb entries for kernel
1557 lowmem mapping on PPC40x.
1559 nomca [IA-64] Disable machine check abort handling
1561 nomce [X86-32] Machine Check Exception
1563 nomfgpt [X86-32] Disable Multi-Function General Purpose
1564 Timer usage (for AMD Geode machines).
1566 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1568 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1569 with UP alternatives
1571 noresidual [PPC] Don't use residual data on PReP machines.
1573 noresume [SWSUSP] Disables resume and restores original swap
1576 no-scroll [VGA] Disables scrollback.
1577 This is required for the Braillex ib80-piezo Braille
1578 reader made by F.H. Papenmeier (Germany).
1582 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1584 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1585 and disable the IO APIC. legacy for "maxcpus=0".
1587 nosoftlockup [KNL] Disable the soft-lockup detector.
1589 noswapaccount [KNL] Disable accounting of swap in memory resource
1590 controller. (See Documentation/controllers/memory.txt)
1592 nosync [HW,M68K] Disables sync negotiation for all devices.
1594 notsc [BUGS=X86-32] Disable Time Stamp Counter
1596 nousb [USB] Disable the USB subsystem
1600 nptcg= [IA64] Override max number of concurrent global TLB
1601 purges which is reported from either PAL_VM_SUMMARY or
1604 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1605 one of ['zone', 'node', 'default'] can be specified
1606 This can be set from sysctl after boot.
1607 See Documentation/sysctl/vm.txt for details.
1609 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1611 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1612 See Documentation/debugging-via-ohci1394.txt for more
1615 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1616 Rather than timing out after 20 ms if an EC
1617 command is not properly ACKed, override the length
1618 of the timeout. We have interrupts disabled while
1619 waiting for the ACK, so if this is set too high
1620 interrupts *may* be lost!
1625 oprofile.timer= [HW]
1626 Use timer interrupt instead of performance counters
1628 osst= [HW,SCSI] SCSI Tape Driver
1629 Format: <buffer_size>,<write_threshold>
1630 See also Documentation/scsi/st.txt.
1632 panic= [KNL] Kernel behaviour on panic
1635 parkbd.port= [HW] Parallel port number the keyboard adapter is
1636 connected to, default is 0.
1638 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1639 0 for XT, 1 for AT (default is AT).
1642 parport= [HW,PPT] Specify parallel ports. 0 disables.
1643 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1644 Use 'auto' to force the driver to use any
1645 IRQ/DMA settings detected (the default is to
1646 ignore detected IRQ/DMA settings because of
1647 possible conflicts). You can specify the base
1648 address, IRQ, and DMA settings; IRQ and DMA
1649 should be numbers, or 'auto' (for using detected
1650 settings on that particular port), or 'nofifo'
1651 (to avoid using a FIFO even if it is detected).
1652 Parallel ports are assigned in the order they
1653 are specified on the command line, starting
1656 parport_init_mode= [HW,PPT]
1657 Configure VIA parallel port to operate in
1658 a specific mode. This is necessary on Pegasos
1659 computer where firmware has no options for setting
1660 up parallel port mode and sets it to spp.
1661 Currently this function knows 686a and 8231 chips.
1662 Format: [spp|ps2|epp|ecp|ecpepp]
1664 pas2= [HW,OSS] Format:
1665 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1668 See header of drivers/scsi/pas16.c.
1671 Halt all CPUs after the first oops has been printed for
1672 the specified number of seconds. This is to be used if
1673 your oopses keep scrolling off the screen.
1678 See header of drivers/block/paride/pcd.c.
1679 See also Documentation/blockdev/paride.txt.
1681 pci=option[,option...] [PCI] various PCI subsystem options:
1682 off [X86] don't probe for the PCI bus
1683 bios [X86-32] force use of PCI BIOS, don't access
1684 the hardware directly. Use this if your machine
1685 has a non-standard PCI host bridge.
1686 nobios [X86-32] disallow use of PCI BIOS, only direct
1687 hardware access methods are allowed. Use this
1688 if you experience crashes upon bootup and you
1689 suspect they are caused by the BIOS.
1690 conf1 [X86] Force use of PCI Configuration
1692 conf2 [X86] Force use of PCI Configuration
1694 noaer [PCIE] If the PCIEAER kernel config parameter is
1695 enabled, this kernel boot option can be used to
1696 disable the use of PCIE advanced error reporting.
1697 nodomains [PCI] Disable support for multiple PCI
1698 root domains (aka PCI segments, in ACPI-speak).
1699 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1701 nomsi [MSI] If the PCI_MSI kernel config parameter is
1702 enabled, this kernel boot option can be used to
1703 disable the use of MSI interrupts system-wide.
1704 noioapicquirk [APIC] Disable all boot interrupt quirks.
1705 Safety option to keep boot IRQs enabled. This
1706 should never be necessary.
1707 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1708 primary IO-APIC for bridges that cannot disable
1709 boot IRQs. This fixes a source of spurious IRQs
1710 when the system masks IRQs.
1711 noioapicreroute [APIC] Disable workaround that uses the
1712 boot IRQ equivalent of an IRQ that connects to
1713 a chipset where boot IRQs cannot be disabled.
1714 The opposite of ioapicreroute.
1715 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1716 routing table. These calls are known to be buggy
1717 on several machines and they hang the machine
1718 when used, but on other computers it's the only
1719 way to get the interrupt routing table. Try
1720 this option if the kernel is unable to allocate
1721 IRQs or discover secondary PCI buses on your
1723 rom [X86] Assign address space to expansion ROMs.
1724 Use with caution as certain devices share
1725 address decoders between ROMs and other
1727 norom [X86] Do not assign address space to
1728 expansion ROMs that do not already have
1729 BIOS assigned address ranges.
1730 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1731 assigned automatically to PCI devices. You can
1732 make the kernel exclude IRQs of your ISA cards
1734 pirqaddr=0xAAAAA [X86] Specify the physical address
1735 of the PIRQ table (normally generated
1736 by the BIOS) if it is outside the
1737 F0000h-100000h range.
1738 lastbus=N [X86] Scan all buses thru bus #N. Can be
1739 useful if the kernel is unable to find your
1740 secondary buses and you want to tell it
1741 explicitly which ones they are.
1742 assign-busses [X86] Always assign all PCI bus
1743 numbers ourselves, overriding
1744 whatever the firmware may have done.
1745 usepirqmask [X86] Honor the possible IRQ mask stored
1746 in the BIOS $PIR table. This is needed on
1747 some systems with broken BIOSes, notably
1748 some HP Pavilion N5400 and Omnibook XE3
1749 notebooks. This will have no effect if ACPI
1750 IRQ routing is enabled.
1751 noacpi [X86] Do not use ACPI for IRQ routing
1752 or for PCI scanning.
1753 use_crs [X86] Use _CRS for PCI resource
1755 routeirq Do IRQ routing for all PCI devices.
1756 This is normally done in pci_enable_device(),
1757 so this option is a temporary workaround
1758 for broken drivers that don't call it.
1759 skip_isa_align [X86] do not align io start addr, so can
1760 handle more pci cards
1761 firmware [ARM] Do not re-enumerate the bus but instead
1762 just use the configuration from the
1763 bootloader. This is currently used on
1764 IXP2000 systems where the bus has to be
1765 configured a certain way for adjunct CPUs.
1766 noearly [X86] Don't do any early type 1 scanning.
1767 This might help on some broken boards which
1768 machine check when some devices' config space
1769 is read. But various workarounds are disabled
1770 and some IOMMU drivers will not work.
1771 bfsort Sort PCI devices into breadth-first order.
1772 This sorting is done to get a device
1773 order compatible with older (<= 2.4) kernels.
1774 nobfsort Don't sort PCI devices into breadth-first order.
1775 cbiosize=nn[KMG] The fixed amount of bus space which is
1776 reserved for the CardBus bridge's IO window.
1777 The default value is 256 bytes.
1778 cbmemsize=nn[KMG] The fixed amount of bus space which is
1779 reserved for the CardBus bridge's memory
1780 window. The default value is 64 megabytes.
1782 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1785 force Enable ASPM even on devices that claim not to support it.
1786 WARNING: Forcing ASPM on may cause system lockups.
1788 pcmv= [HW,PCMCIA] BadgePAD 4
1791 See Documentation/blockdev/paride.txt.
1793 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1796 See arch/parisc/kernel/pdc_chassis.c
1799 See Documentation/blockdev/paride.txt.
1802 See Documentation/blockdev/paride.txt.
1804 pirq= [SMP,APIC] Manual mp-table setup
1805 See Documentation/x86/i386/IO-APIC.txt.
1807 plip= [PPT,NET] Parallel port network link
1808 Format: { parport<nr> | timid | 0 }
1809 See also Documentation/parport.txt.
1811 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1812 Override pmtimer IOPort with a hex value.
1816 Enable PNP debug messages. This depends on the
1817 CONFIG_PNP_DEBUG_MESSAGES option.
1823 { on | off | curr | res | no-curr | no-res }
1826 [ISAPNP] Exclude IRQs for the autoconfiguration
1829 [ISAPNP] Exclude DMAs for the autoconfiguration
1831 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1832 Ranges are in pairs (I/O port base and size).
1835 [ISAPNP] Exclude memory regions for the
1837 Ranges are in pairs (memory base and size).
1839 print-fatal-signals=
1840 [KNL] debug: print fatal signals
1841 print-fatal-signals=1: print segfault info to
1845 printk.time= Show timing data prefixed to each printk message line
1846 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1848 profile= [KNL] Enable kernel profiling via /proc/profile
1849 Format: [schedule,]<number>
1850 Param: "schedule" - profile schedule points.
1851 Param: <number> - step/bucket size as a power of 2 for
1852 statistical time based profiling.
1853 Param: "sleep" - profile D-state sleeping (millisecs).
1854 Requires CONFIG_SCHEDSTATS
1855 Param: "kvm" - profile VM exits.
1857 processor.max_cstate= [HW,ACPI]
1858 Limit processor to maximum C-state
1859 max_cstate=9 overrides any DMI blacklist limit.
1861 processor.nocst [HW,ACPI]
1862 Ignore the _CST method to determine C-states,
1863 instead using the legacy FADT method
1865 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1867 See Documentation/blockdev/ramdisk.txt.
1869 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1870 probe for; one of (bare|imps|exps|lifebook|any).
1871 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1873 psmouse.resetafter= [HW,MOUSE]
1874 Try to reset the device after so many bad packets
1877 [HW,MOUSE] Set desired mouse resolution, in dpi.
1878 psmouse.smartscroll=
1879 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1880 0 = disabled, 1 = enabled (default).
1882 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1884 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1887 See Documentation/blockdev/paride.txt.
1890 [KNL] Number of legacy pty's. Overwrites compiled-in
1893 quiet [KNL] Disable most log messages
1898 See Documentation/md.txt.
1900 ramdisk_blocksize= [RAM]
1901 See Documentation/blockdev/ramdisk.txt.
1903 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1904 See Documentation/blockdev/ramdisk.txt.
1906 rcupdate.blimit= [KNL,BOOT]
1907 Set maximum number of finished RCU callbacks to process
1910 rcupdate.qhimark= [KNL,BOOT]
1911 Set threshold of queued
1912 RCU callbacks over which batch limiting is disabled.
1914 rcupdate.qlowmark= [KNL,BOOT]
1915 Set threshold of queued RCU callbacks below which
1916 batch limiting is re-enabled.
1920 Run specified binary instead of /init from the ramdisk,
1921 used for early userspace startup. See initrd.
1923 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1924 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1925 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1928 [KNL, SMP] Set scheduler's default relax_domain_level.
1929 See Documentation/cpusets.txt.
1931 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1933 reservetop= [X86-32]
1935 Reserves a hole at the top of the kernel virtual
1938 reset_devices [KNL] Force drivers to reset the underlying device
1939 during initialization.
1942 Specify the partition device for software suspend
1944 resume_offset= [SWSUSP]
1945 Specify the offset from the beginning of the partition
1946 given by "resume=" at which the swap header is located,
1947 in <PAGE_SIZE> units (needed only for swap files).
1948 See Documentation/power/swsusp-and-swap-files.txt
1950 retain_initrd [RAM] Keep initrd memory after extraction
1952 rhash_entries= [KNL,NET]
1953 Set number of hash buckets for route cache
1955 riscom8= [HW,SERIAL]
1956 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1958 ro [KNL] Mount root device read-only on boot
1960 root= [KNL] Root filesystem
1962 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1963 mount the root filesystem
1965 rootflags= [KNL] Set root filesystem mount option string
1967 rootfstype= [KNL] Set root filesystem type
1969 rootwait [KNL] Wait (indefinitely) for root device to show up.
1970 Useful for devices that are detected asynchronously
1971 (e.g. USB and MMC devices).
1973 root_plug.vendor_id=
1974 [ROOTPLUG] Override the default vendor ID
1976 root_plug.product_id=
1977 [ROOTPLUG] Override the default product ID
1980 [ROOTPLUG] Enable debugging output
1982 rw [KNL] Mount root device read-write on boot
1984 S [KNL] Run init in single mode
1987 See drivers/net/irda/sa1100_ir.c.
1989 sbni= [NET] Granch SBNI12 leased line adapter
1991 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1992 Format: <io>[,<timeout>[,<isapnp>]]
1994 scsi_debug_*= [SCSI]
1995 See drivers/scsi/scsi_debug.c.
1997 scsi_default_dev_flags=
1998 [SCSI] SCSI default device flags
2001 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2002 Format: <vendor>:<model>:<flags>
2003 (flags are integer value)
2005 scsi_logging_level= [SCSI] a bit mask of logging levels
2006 See drivers/scsi/scsi_logging.h for bits. Also
2007 settable via sysctl at dev.scsi.logging_level
2008 (/proc/sys/dev/scsi/logging_level).
2009 There is also a nice 'scsi_logging_level' script in the
2010 S390-tools package, available for download at
2011 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2013 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2014 discovered. async scans them in kernel threads,
2015 allowing boot to proceed. none ignores them, expecting
2016 user space to do the scan.
2018 selinux [SELINUX] Disable or enable SELinux at boot time.
2019 Format: { "0" | "1" }
2020 See security/selinux/Kconfig help text.
2023 Default value is set via kernel config option.
2024 If enabled at boot time, /selinux/disable can be used
2025 later to disable prior to initial policy load.
2027 selinux_compat_net =
2028 [SELINUX] Set initial selinux_compat_net flag value.
2029 Format: { "0" | "1" }
2030 0 -- use new secmark-based packet controls
2031 1 -- use legacy packet controls
2032 Default value is 0 (preferred).
2033 Value can be changed at runtime via
2034 /selinux/compat_net.
2036 serialnumber [BUGS=X86-32]
2039 Maximal number of shapers.
2041 show_msr= [x86] show boot-time MSR settings
2042 Format: { <integer> }
2043 Show boot-time (BIOS-initialized) MSR settings.
2044 The parameter means the number of CPUs to show,
2045 for example 1 means boot CPU only.
2048 See header of drivers/scsi/sim710.c.
2055 slub_debug[=options[,slabs]] [MM, SLUB]
2056 Enabling slub_debug allows one to determine the
2057 culprit if slab objects become corrupted. Enabling
2058 slub_debug can create guard zones around objects and
2059 may poison objects when not in use. Also tracks the
2060 last alloc / free. For more information see
2061 Documentation/vm/slub.txt.
2063 slub_max_order= [MM, SLUB]
2064 Determines the maximum allowed order for slabs.
2065 A high setting may cause OOMs due to memory
2066 fragmentation. For more information see
2067 Documentation/vm/slub.txt.
2069 slub_min_objects= [MM, SLUB]
2070 The minimum number of objects per slab. SLUB will
2071 increase the slab order up to slub_max_order to
2072 generate a sufficiently large slab able to contain
2073 the number of objects indicated. The higher the number
2074 of objects the smaller the overhead of tracking slabs
2075 and the less frequently locks need to be acquired.
2076 For more information see Documentation/vm/slub.txt.
2078 slub_min_order= [MM, SLUB]
2079 Determines the mininum page order for slabs. Must be
2080 lower than slub_max_order.
2081 For more information see Documentation/vm/slub.txt.
2083 slub_nomerge [MM, SLUB]
2084 Disable merging of slabs with similar size. May be
2085 necessary if there is some reason to distinguish
2086 allocs to different slabs. Debug options disable
2087 merging on their own.
2088 For more information see Documentation/vm/slub.txt.
2091 Format: <io1>[,<io2>[,...,<io8>]]
2093 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2094 attempt to substitute SMP alternatives once at boot.
2096 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2097 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2098 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2099 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2100 smsc-ircc2.ircc_irq= [HW] IRQ line
2101 smsc-ircc2.ircc_dma= [HW] DMA channel
2102 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2103 0: Toshiba Satellite 1800 (GP data pin select)
2104 1: Fast pin select (default)
2107 snd-ad1816a= [HW,ALSA]
2109 snd-ad1848= [HW,ALSA]
2111 snd-ali5451= [HW,ALSA]
2113 snd-als100= [HW,ALSA]
2115 snd-als4000= [HW,ALSA]
2117 snd-azt2320= [HW,ALSA]
2119 snd-cmi8330= [HW,ALSA]
2121 snd-cmipci= [HW,ALSA]
2123 snd-cs4231= [HW,ALSA]
2125 snd-cs4232= [HW,ALSA]
2127 snd-cs4236= [HW,ALSA]
2129 snd-cs4281= [HW,ALSA]
2131 snd-cs46xx= [HW,ALSA]
2133 snd-dt019x= [HW,ALSA]
2135 snd-dummy= [HW,ALSA]
2137 snd-emu10k1= [HW,ALSA]
2139 snd-ens1370= [HW,ALSA]
2141 snd-ens1371= [HW,ALSA]
2143 snd-es968= [HW,ALSA]
2145 snd-es1688= [HW,ALSA]
2147 snd-es18xx= [HW,ALSA]
2149 snd-es1938= [HW,ALSA]
2151 snd-es1968= [HW,ALSA]
2153 snd-fm801= [HW,ALSA]
2155 snd-gusclassic= [HW,ALSA]
2157 snd-gusextreme= [HW,ALSA]
2159 snd-gusmax= [HW,ALSA]
2163 snd-ice1712= [HW,ALSA]
2165 snd-intel8x0= [HW,ALSA]
2167 snd-interwave= [HW,ALSA]
2172 snd-korg1212= [HW,ALSA]
2174 snd-maestro3= [HW,ALSA]
2176 snd-mpu401= [HW,ALSA]
2178 snd-mtpav= [HW,ALSA]
2180 snd-nm256= [HW,ALSA]
2182 snd-opl3sa2= [HW,ALSA]
2190 snd-opti93x= [HW,ALSA]
2194 snd-rme32= [HW,ALSA]
2196 snd-rme96= [HW,ALSA]
2198 snd-rme9652= [HW,ALSA]
2204 snd-sbawe= [HW,ALSA]
2206 snd-serial= [HW,ALSA]
2208 snd-sgalaxy= [HW,ALSA]
2210 snd-sonicvibes= [HW,ALSA]
2215 snd-sun-cs4231= [HW,ALSA]
2217 snd-trident= [HW,ALSA]
2219 snd-usb-audio= [HW,ALSA,USB]
2221 snd-via82xx= [HW,ALSA]
2223 snd-virmidi= [HW,ALSA]
2225 snd-wavefront= [HW,ALSA]
2227 snd-ymfpci= [HW,ALSA]
2230 [KNL] Should the soft-lockup detector generate panics.
2232 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2233 See Documentation/sonypi.txt
2235 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2236 See Documentation/serial/specialix.txt.
2238 spia_io_base= [HW,MTD]
2244 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2246 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2247 See Documentation/scsi/st.txt.
2250 Enabled the stack tracer on boot up.
2254 Set the STI (builtin display/keyboard on the HP-PARISC
2255 machines) console (graphic card) which should be used
2256 as the initial boot-console.
2257 See also comment in drivers/video/console/sticore.c.
2260 See comment in drivers/video/console/sticore.c.
2263 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2267 Control how the NFS server code allocates CPUs to
2268 service thread pools. Depending on how many NICs
2269 you have and where their interrupts are bound, this
2270 option will affect which CPUs will do NFS serving.
2271 Note: this parameter cannot be changed while the
2272 NFS server is running.
2274 auto the server chooses an appropriate mode
2275 automatically using heuristics
2276 global a single global pool contains all CPUs
2277 percpu one pool for each CPU
2278 pernode one pool for each NUMA node (equivalent
2279 to global on non-NUMA machines)
2281 swiotlb= [IA-64] Number of I/O TLB slabs
2285 sym53c416= [HW,SCSI]
2286 See header of drivers/scsi/sym53c416.c.
2288 sysrq_always_enabled
2290 Ignore sysrq setting - this boot parameter will
2291 neutralize any effect of /proc/sys/kernel/sysrq.
2292 Useful for debugging.
2295 See header of drivers/scsi/t128.c.
2299 test_suspend= [SUSPEND]
2300 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2301 standby suspend) as the system sleep state to briefly
2302 enter during system startup. The system is woken from
2303 this state using a wakeup-capable RTC alarm.
2305 thash_entries= [KNL,NET]
2306 Set number of hash buckets for TCP connection
2308 thermal.act= [HW,ACPI]
2309 -1: disable all active trip points in all thermal zones
2310 <degrees C>: override all lowest active trip points
2312 thermal.crt= [HW,ACPI]
2313 -1: disable all critical trip points in all thermal zones
2314 <degrees C>: override all critical trip points
2316 thermal.nocrt= [HW,ACPI]
2317 Set to disable actions on ACPI thermal zone
2318 critical and hot trip points.
2320 thermal.off= [HW,ACPI]
2321 1: disable ACPI thermal control
2323 thermal.psv= [HW,ACPI]
2324 -1: disable all passive trip points
2325 <degrees C>: override all passive trip points to this
2328 thermal.tzp= [HW,ACPI]
2329 Specify global default ACPI thermal zone polling rate
2330 <deci-seconds>: poll all this frequency
2331 0: no polling (default)
2334 See comment before function dc390_setup() in
2335 drivers/scsi/tmscsim.c.
2339 Specify if the kernel should make use of the cpu
2340 topology informations if the hardware supports these.
2341 The scheduler will make use of these informations and
2342 e.g. base its process migration decisions on it.
2347 trix= [HW,OSS] MediaTrix AudioTrix Pro
2349 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2351 tsc= Disable clocksource-must-verify flag for TSC.
2353 [x86] reliable: mark tsc clocksource as reliable, this
2354 disables clocksource verification at runtime.
2355 Used to enable high-resolution timer mode on older
2356 hardware, and in virtualized environment.
2358 turbografx.map[2|3]= [HW,JOY]
2359 TurboGraFX parallel port interface
2361 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2362 See also Documentation/input/joystick-parport.txt
2364 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2365 See header of drivers/scsi/u14-34f.c.
2374 [USB] Ignore overcurrent events (default N).
2375 Some badly-designed motherboards generate lots of
2376 bogus events, for ports that aren't wired to
2377 anything. Set this parameter to avoid log spamming.
2378 Note that genuine overcurrent events won't be
2383 Set unknown_nmi_panic=1 early on boot.
2385 usbcore.autosuspend=
2386 [USB] The autosuspend time delay (in seconds) used
2387 for newly-detected USB devices (default 2). This
2388 is the time required before an idle device will be
2389 autosuspended. Devices for which the delay is set
2390 to a negative value won't be autosuspended at all.
2392 usbcore.usbfs_snoop=
2393 [USB] Set to log all usbfs traffic (default 0 = off).
2395 usbcore.blinkenlights=
2396 [USB] Set to cycle leds on hubs (default 0 = off).
2398 usbcore.old_scheme_first=
2399 [USB] Start with the old device initialization
2400 scheme (default 0 = off).
2402 usbcore.use_both_schemes=
2403 [USB] Try the other device initialization scheme
2404 if the first one fails (default 1 = enabled).
2406 usbcore.initial_descriptor_timeout=
2407 [USB] Specifies timeout for the initial 64-byte
2408 USB_REQ_GET_DESCRIPTOR request in milliseconds
2409 (default 5000 = 5.0 seconds).
2412 [USBHID] The interval which mice are to be polled at.
2414 usb-storage.delay_use=
2415 [UMS] The delay in seconds before a new device is
2416 scanned for Logical Units (default 5).
2419 [UMS] A list of quirks entries to supplement or
2420 override the built-in unusual_devs list. List
2421 entries are separated by commas. Each entry has
2422 the form VID:PID:Flags where VID and PID are Vendor
2423 and Product ID values (4-digit hex numbers) and
2424 Flags is a set of characters, each corresponding
2425 to a common usb-storage quirk flag as follows:
2426 a = SANE_SENSE (collect more than 18 bytes
2428 c = FIX_CAPACITY (decrease the reported
2429 device capacity by one sector);
2430 h = CAPACITY_HEURISTICS (decrease the
2431 reported device capacity by one
2432 sector if the number is odd);
2433 i = IGNORE_DEVICE (don't bind to this
2435 l = NOT_LOCKABLE (don't try to lock and
2436 unlock ejectable media);
2437 m = MAX_SECTORS_64 (don't transfer more
2438 than 64 sectors = 32 KB at a time);
2439 o = CAPACITY_OK (accept the capacity
2440 reported by the device);
2441 r = IGNORE_RESIDUE (the device reports
2442 bogus residue values);
2443 s = SINGLE_LUN (the device has only one
2445 w = NO_WP_DETECT (don't test whether the
2446 medium is write-protected).
2447 Example: quirks=0419:aaf5:rl,0421:0433:rc
2449 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2450 kernel's map of available physical RAM.
2452 vdso= [X86-32,SH,x86-64]
2453 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2454 vdso=1: enable VDSO (default)
2455 vdso=0: disable VDSO mapping
2457 vdso32= [X86-32,X86-64]
2458 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2459 vdso32=1: enable 32-bit VDSO (default)
2460 vdso32=0: disable 32-bit VDSO mapping
2463 vector=percpu: enable percpu vector domain
2465 video= [FB] Frame buffer configuration
2466 See Documentation/fb/modedb.txt.
2468 vga= [BOOT,X86-32] Select a particular video mode
2469 See Documentation/x86/boot.txt and
2470 Documentation/svga.txt.
2471 Use vga=ask for menu.
2472 This is actually a boot loader parameter; the value is
2473 passed to the kernel using a special protocol.
2475 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2476 size of <nn>. This can be used to increase the
2477 minimum size (128MB on x86). It can also be used to
2478 decrease the size and leave more room for directly
2481 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2484 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2487 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2490 waveartist= [HW,OSS]
2491 Format: <io>,<irq>,<dma>,<dma2>
2494 See header of drivers/scsi/wd33c93.c.
2497 See header of drivers/scsi/wd7000.c.
2500 See Documentation/watchdog/wdt.txt.
2502 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2503 xd_geo= See header of drivers/block/xd.c.
2505 xirc2ps_cs= [NET,PCMCIA]
2507 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2509 norandmaps Don't use address space randomization. Equivalent to
2510 echo 0 > /proc/sys/kernel/randomize_va_space
2512 ______________________________________________________________________
2516 Add documentation for ALSA options.
2517 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob