4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 FTRACE Function tracing enabled.
93 TS Appropriate touchscreen support is enabled.
94 UMS USB Mass Storage support is enabled.
95 USB USB support is enabled.
96 USBHID USB Human Interface Device support is enabled.
97 V4L Video For Linux support is enabled.
98 VGA The VGA console has been enabled.
99 VT Virtual terminal support is enabled.
100 WDT Watchdog support is enabled.
101 XT IBM PC/XT MFM hard disk support is enabled.
102 X86-32 X86-32, aka i386 architecture is enabled.
103 X86-64 X86-64 architecture is enabled.
104 More X86-64 boot options can be found in
105 Documentation/x86/x86_64/boot-options.txt .
106 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
108 In addition, the following text indicates that the option:
110 BUGS= Relates to possible processor bugs on the said processor.
111 KNL Is a kernel start-up parameter.
112 BOOT Is a boot loader parameter.
114 Parameters denoted with BOOT are actually interpreted by the boot
115 loader, and have no meaning to the kernel directly.
116 Do not modify the syntax of boot loader parameters without extreme
117 need or coordination with <Documentation/x86/boot.txt>.
119 There are also arch-specific kernel-parameters not documented here.
120 See for example <Documentation/x86/x86_64/boot-options.txt>.
122 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
123 a trailing = on the name of any parameter states that that parameter will
124 be entered as an environment variable, whereas its absence indicates that
125 it will appear as a kernel argument readable via /proc/cmdline by programs
126 running once the system is up.
128 The number of kernel parameters is not limited, but the length of the
129 complete command line (parameters including spaces etc.) is limited to
130 a fixed number of characters. This limit depends on the architecture
131 and is between 256 and 4096 characters. It is defined in the file
132 ./include/asm/setup.h as COMMAND_LINE_SIZE.
135 acpi= [HW,ACPI,X86-64,i386]
136 Advanced Configuration and Power Interface
137 Format: { force | off | ht | strict | noirq | rsdt }
138 force -- enable ACPI if default was off
139 off -- disable ACPI if default was on
140 noirq -- do not use ACPI for IRQ routing
141 ht -- run only enough ACPI to enable Hyper Threading
142 strict -- Be less tolerant of platforms that are not
143 strictly ACPI specification compliant.
144 rsdt -- prefer RSDT over (default) XSDT
146 See also Documentation/power/pm.txt, pci=noacpi
148 acpi_apic_instance= [ACPI, IOAPIC]
150 2: use 2nd APIC table, if available
151 1,0: use 1st APIC table
154 acpi_sleep= [HW,ACPI] Sleep options
155 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
156 old_ordering, s4_nonvs }
157 See Documentation/power/video.txt for information on
159 s3_beep is for debugging; it makes the PC's speaker beep
160 as soon as the kernel's real-mode entry point is called.
161 s4_nohwsig prevents ACPI hardware signature from being
162 used during resume from hibernation.
163 old_ordering causes the ACPI 1.0 ordering of the _PTS
164 control method, with respect to putting devices into
165 low power states, to be enforced (the ACPI 2.0 ordering
166 of _PTS is used by default).
167 s4_nonvs prevents the kernel from saving/restoring the
168 ACPI NVS memory during hibernation.
170 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
171 Format: { level | edge | high | low }
173 acpi_irq_balance [HW,ACPI]
174 ACPI will balance active IRQs
177 acpi_irq_nobalance [HW,ACPI]
178 ACPI will not move active IRQs (default)
181 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
183 Format: <irq>,<irq>...
185 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
186 Format: <irq>,<irq>...
188 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
190 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
191 Format: To spoof as Windows 98: ="Microsoft Windows"
193 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
194 acpi_osi="string1" # add string1 -- only one string
195 acpi_osi="!string2" # remove built-in string2
196 acpi_osi= # disable all strings
198 acpi_serialize [HW,ACPI] force serialization of AML methods
200 acpi_skip_timer_override [HW,ACPI]
201 Recognize and ignore IRQ0/pin2 Interrupt Override.
202 For broken nForce2 BIOS resulting in XT-PIC timer.
203 acpi_use_timer_override [HW,ACPI]
204 Use timer override. For some broken Nvidia NF5 boards
205 that require a timer override, but don't have
208 acpi_backlight= [HW,ACPI]
209 acpi_backlight=vendor
211 If set to vendor, prefer vendor specific driver
212 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
213 of the ACPI video.ko driver.
215 acpi_display_output= [HW,ACPI]
216 acpi_display_output=vendor
217 acpi_display_output=video
220 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
221 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
223 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
224 debug output. Bits in debug_layer correspond to a
225 _COMPONENT in an ACPI source file, e.g.,
226 #define _COMPONENT ACPI_PCI_COMPONENT
227 Bits in debug_level correspond to a level in
228 ACPI_DEBUG_PRINT statements, e.g.,
229 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
230 The debug_level mask defaults to "info". See
231 Documentation/acpi/debug.txt for more information about
232 debug layers and levels.
234 Enable processor driver info messages:
235 acpi.debug_layer=0x20000000
236 Enable PCI/PCI interrupt routing info messages:
237 acpi.debug_layer=0x400000
238 Enable AML "Debug" output, i.e., stores to the Debug
239 object while interpreting AML:
240 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
241 Enable all messages related to ACPI hardware:
242 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
244 Some values produce so much output that the system is
245 unusable. The "log_buf_len" parameter may be useful
246 if you need to capture more output.
248 acpi.power_nocheck= [HW,ACPI]
249 Format: 1/0 enable/disable the check of power state.
250 On some bogus BIOS the _PSC object/_STA object of
251 power resource can't return the correct device power
252 state. In such case it is unneccessary to check its
253 power state again in power transition.
254 1 : disable the power state check
256 acpi_pm_good [X86-32,X86-64]
257 Override the pmtimer bug detection: force the kernel
258 to assume that this machine's pmtimer latches its value
259 and always returns good values.
261 acpi_enforce_resources= [ACPI]
262 { strict | lax | no }
263 Check for resource conflicts between native drivers
264 and ACPI OperationRegions (SystemIO and SystemMemory
265 only). IO ports and memory declared in ACPI might be
266 used by the ACPI subsystem in arbitrary AML code and
267 can interfere with legacy drivers.
268 strict (default): access to resources claimed by ACPI
269 is denied; legacy drivers trying to access reserved
270 resources will fail to bind to device using them.
271 lax: access to resources claimed by ACPI is allowed;
272 legacy drivers trying to access reserved resources
273 will bind successfully but a warning message is logged.
274 no: ACPI OperationRegions are not marked as reserved,
275 no further checks are performed.
278 { off | try_unsupported }
279 off: disable AGP support
280 try_unsupported: try to drive unsupported chipsets
281 (may crash computer or cause data corruption)
283 enable_timer_pin_1 [i386,x86-64]
284 Enable PIN 1 of APIC timer
285 Can be useful to work around chipset bugs
286 (in particular on some ATI chipsets).
287 The kernel tries to set a reasonable default.
289 disable_timer_pin_1 [i386,x86-64]
290 Disable PIN 1 of APIC timer
291 Can be useful to work around chipset bugs.
294 Format: <io>,<irq>,<dma>,<dma2>,<type>
297 See header of drivers/scsi/advansys.c.
299 advwdt= [HW,WDT] Advantech WDT
300 Format: <iostart>,<iostop>
302 aedsp16= [HW,OSS] Audio Excel DSP 16
303 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
304 See also header of sound/oss/aedsp16.c.
307 See Documentation/scsi/aha152x.txt.
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
313 See Documentation/scsi/aic7xxx.txt.
316 See Documentation/scsi/aic79xx.txt.
318 amd_iommu= [HW,X86-84]
319 Pass parameters to the AMD IOMMU driver in the system.
321 isolate - enable device isolation (each device, as far
322 as possible, will get its own protection
324 share - put every device behind one IOMMU into the
325 same protection domain
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
331 amd_iommu_size= [HW,X86-64]
332 Define the size of the aperture for the AMD IOMMU
333 driver. Possible values are:
334 '32M', '64M' (default), '128M', '256M', '512M', '1G'
336 amijoy.map= [HW,JOY] Amiga joystick support
337 Map of devices attached to JOY0DAT and JOY1DAT
339 See also Documentation/kernel/input/joystick.txt
341 analog.map= [HW,JOY] Analog joystick and gamepad support
342 Specifies type or capabilities of an analog joystick
343 connected to one of 16 gameports
344 Format: <type1>,<type2>,..<type16>
347 Power management functions (SPARCstation-4/5 + deriv.)
349 Disable APC CPU standby support. SPARCstation-Fox does
350 not play well with APC CPU idle - disable it if you have
351 APC and your system crashes randomly.
353 apic= [APIC,i386] Advanced Programmable Interrupt Controller
354 Change the output verbosity whilst booting
355 Format: { quiet (default) | verbose | debug }
356 Change the amount of debugging information output
357 when initialising the APIC and IO-APIC components.
359 apm= [APM] Advanced Power Management
360 See header of arch/x86/kernel/apm_32.c.
362 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
363 Format: <io>,<irq>,<nodeID>
367 atarimouse= [HW,MOUSE] Atari Mouse
369 atascsi= [HW,SCSI] Atari SCSI
371 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
372 EzKey and similar keyboards
374 atkbd.reset= [HW] Reset keyboard during initialization
376 atkbd.set= [HW] Select keyboard code set
377 Format: <int> (2 = AT (default), 3 = PS/2)
379 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
382 atkbd.softraw= [HW] Choose between synthetic and real raw mode
383 Format: <bool> (0 = real, 1 = synthetic (default))
385 atkbd.softrepeat= [HW]
386 Use software keyboard repeat
390 baycom_epp= [HW,AX25]
393 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
395 See header of drivers/net/hamradio/baycom_par.c.
397 baycom_ser_fdx= [HW,AX25]
398 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
399 Format: <io>,<irq>,<mode>[,<baud>]
400 See header of drivers/net/hamradio/baycom_ser_fdx.c.
402 baycom_ser_hdx= [HW,AX25]
403 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
404 Format: <io>,<irq>,<mode>
405 See header of drivers/net/hamradio/baycom_ser_hdx.c.
407 boot_delay= Milliseconds to delay each printk during boot.
408 Values larger than 10 seconds (10000) are changed to
412 bootmem_debug [KNL] Enable bootmem allocator debug messages.
414 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
415 bttv.radio= Most important insmod options are available as
417 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
418 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
421 See drivers/scsi/BusLogic.c, comment before function
422 BusLogic_ParseDriverOptions().
424 c101= [NET] Moxa C101 synchronous serial card
426 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
427 Sometimes CPU hardware bugs make them report the cache
428 size incorrectly. The kernel will attempt work arounds
429 to fix known problems, but for some CPUs it is not
430 possible to determine what the correct size should be.
431 This option provides an override for these situations.
433 security= [SECURITY] Choose a security module to enable at boot.
434 If this boot parameter is not specified, only the first
435 security module asking for security registration will be
436 loaded. An invalid security module name will be treated
437 as if no module has been chosen.
440 [SECURITY] Disable capabilities. This would normally
441 be used only if an alternative security model is to be
442 configured. Potentially dangerous and should only be
443 used if you are entirely sure of the consequences.
445 ccw_timeout_log [S390]
446 See Documentation/s390/CommonIO for details.
448 cgroup_disable= [KNL] Disable a particular controller
449 Format: {name of the controller(s) to disable}
450 {Currently supported controllers - "memory"}
452 checkreqprot [SELINUX] Set initial checkreqprot flag value.
453 Format: { "0" | "1" }
454 See security/selinux/Kconfig help text.
455 0 -- check protection applied by kernel (includes
456 any implied execute protection).
457 1 -- check protection requested by application.
458 Default value is set via a kernel config option.
459 Value can be changed at runtime via
460 /selinux/checkreqprot.
463 See Documentation/s390/CommonIO for details.
465 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
467 Forces specified clocksource (if available) to be used
468 when calculating gettimeofday(). If specified
469 clocksource is not available, it defaults to PIT.
470 Format: { pit | tsc | cyclone | pmtmr }
472 clocksource= [GENERIC_TIME] Override the default clocksource
474 Override the default clocksource and use the clocksource
475 with the name specified.
476 Some clocksource names to choose from, depending on
478 [all] jiffies (this is the base, fallback clocksource)
480 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
481 pxa_timer,timer3,32k_counter,timer0_1
483 [X86-32] pit,hpet,tsc,vmi-timer;
484 scx200_hrt on Geode; cyclone on IBM x440
492 clearcpuid=BITNUM [X86]
493 Disable CPUID feature X for the kernel. See
494 arch/x86/include/asm/cpufeature.h for the valid bit
495 numbers. Note the Linux specific bits are not necessarily
496 stable over kernel options, but the vendor specific
498 Also note that user programs calling CPUID directly
499 or using the feature without checking anything
500 will still see it. This just prevents it from
501 being used by the kernel or shown in /proc/cpuinfo.
502 Also note the kernel might malfunction if you disable
505 code_bytes [IA32/X86_64] How many bytes of object code to print
510 hpet= [X86-32,HPET] option to control HPET usage
511 Format: { enable (default) | disable | force }
512 disable: disable HPET and use PIT instead
513 force: allow force enabled of undocumented chips (ICH4,
516 com20020= [HW,NET] ARCnet - COM20020 chipset
518 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
520 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
524 ARCnet - COM90xx chipset (memory-mapped buffers)
525 Format: <io>[,<irq>[,<memstart>]]
527 condev= [HW,S390] console device
530 console= [KNL] Output console device and options.
532 tty<n> Use the virtual console device <n>.
536 Use the specified serial port. The options are of
537 the form "bbbbpnf", where "bbbb" is the baud rate,
538 "p" is parity ("n", "o", or "e"), "n" is number of
539 bits, and "f" is flow control ("r" for RTS or
540 omit it). Default is "9600n8".
542 See Documentation/serial-console.txt for more
544 Documentation/networking/netconsole.txt for an
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 switching to the matching ttyS device later. The
552 options are the same as for ttyS, above.
554 If the device connected to the port is not a TTY but a braille
555 device, prepend "brl," before the device type, for instance
557 For now, only VisioBraille is supported.
559 earlycon= [KNL] Output early console device and options.
560 uart[8250],io,<addr>[,options]
561 uart[8250],mmio,<addr>[,options]
562 Start an early, polled-mode console on the 8250/16550
563 UART at the specified I/O port or MMIO address.
564 The options are the same as for ttyS, above.
567 [HW] Never suspend the console
568 Disable suspending of consoles during suspend and
569 hibernate operations. Once disabled, debugging
570 messages can reach various consoles while the rest
571 of the system is being put to sleep (ie, while
572 debugging driver suspend/resume hooks). This may
573 not work reliably with all consoles, but is known
574 to work with serial and VGA consoles.
577 [KNL] Change the default value for
578 /proc/<pid>/coredump_filter.
579 See also Documentation/filesystems/proc.txt.
581 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
583 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
585 crashkernel=nn[KMG]@ss[KMG]
586 [KNL] Reserve a chunk of physical memory to
587 hold a kernel to switch to with kexec on panic.
589 crashkernel=range1:size1[,range2:size2,...][@offset]
590 [KNL] Same as above, but depends on the memory
591 in the running system. The syntax of range is
592 start-[end] where start and end are both
593 a memory unit (amount[KMG]). See also
594 Documentation/kdump/kdump.txt for a example.
599 cs89x0_media= [HW,NET]
600 Format: { rj45 | aui | bnc }
603 See header of drivers/s390/block/dasd_devmap.c.
605 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
606 (one device per port)
607 Format: <port#>,<type>
608 See also Documentation/input/joystick-parport.txt
610 debug [KNL] Enable kernel debugging (events log level).
613 [KNL] verbose self-tests
615 Print debugging info while doing the locking API
617 We default to 0 (no extra messages), setting it to
618 1 will print _a lot_ more information - normally
619 only useful to kernel developers.
621 debug_objects [KNL] Enable object debugging
623 debugpat [X86] Enable PAT debugging
625 decnet.addr= [HW,NET]
626 Format: <area>[,<node>]
627 See also Documentation/networking/decnet.txt.
630 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
631 Change the default blue palette of the console.
632 This is a 16-member array composed of values
636 Format: <green0>,<green1>,<green2>,...,<green15>
637 Change the default green palette of the console.
638 This is a 16-member array composed of values
642 Format: <red0>,<red1>,<red2>,...,<red15>
643 Change the default red palette of the console.
644 This is a 16-member array composed of values
650 Set system-wide default UTF-8 mode for all tty's.
651 Default is 1, i.e. UTF-8 mode is enabled for all
652 newly opened terminals.
655 Set number of hash buckets for dentry cache.
658 IO parameters + enable/disable command.
660 digiepca= [HW,SERIAL]
661 See drivers/char/README.epca and
662 Documentation/serial/digiepca.txt.
664 disable_mtrr_cleanup [X86]
665 enable_mtrr_cleanup [X86]
666 The kernel tries to adjust MTRR layout from continuous
667 to discrete, to make X server driver able to add WB
668 entry later. This parameter enables/disables that.
670 mtrr_chunk_size=nn[KMG] [X86]
671 used for mtrr cleanup. It is largest continous chunk
672 that could hold holes aka. UC entries.
674 mtrr_gran_size=nn[KMG] [X86]
675 Used for mtrr cleanup. It is granularity of mtrr block.
677 Large value could prevent small alignment from
680 mtrr_spare_reg_nr=n [X86]
682 Range: 0,7 : spare reg number
684 Used for mtrr cleanup. It is spare mtrr entries number.
685 Set to 2 or more if your graphical card needs more.
687 disable_mtrr_trim [X86, Intel and AMD only]
688 By default the kernel will trim any uncacheable
689 memory out of your available memory pool based on
690 MTRR settings. This parameter disables that behavior,
691 possibly causing your machine to run very slowly.
693 dmasound= [HW,OSS] Sound subsystem buffers
699 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
701 earlyprintk=serial[,ttySn[,baudrate]]
704 Append ",keep" to not disable it when the real console
707 Only vga or serial or usb debug port at a time.
709 Currently only ttyS0 and ttyS1 are supported.
711 Interaction with the standard serial driver is not
714 The VGA output is eventually overwritten by the real
720 Format: {"off" | "on" | "skip[mbr]"}
722 eisa_irq_edge= [PARISC,HW]
723 See header of drivers/parisc/eisa.c.
726 See comment before function elanfreq_setup() in
727 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
730 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
731 See Documentation/block/as-iosched.txt and
732 Documentation/block/deadline-iosched.txt for details.
734 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
735 Specifies physical address of start of kernel core
736 image elf header. Generally kexec loader will
737 pass this option to capture kernel.
738 See Documentation/kdump/kdump.txt for details.
740 enforcing [SELINUX] Set initial enforcing status.
742 See security/selinux/Kconfig help text.
743 0 -- permissive (log only, no denials).
744 1 -- enforcing (deny and log).
746 Value can be changed at runtime via /selinux/enforce.
748 ether= [HW,NET] Ethernet cards parameters
749 This option is obsoleted by the "netdev=" option, which
750 has equivalent usage. See its documentation for details.
752 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
757 fail_make_request=[KNL]
758 General fault injection mechanism.
759 Format: <interval>,<probability>,<space>,<times>
760 See also /Documentation/fault-injection/.
763 See header of drivers/scsi/fd_mcs.c.
766 See header of drivers/scsi/fdomain.c.
769 See Documentation/blockdev/floppy.txt.
771 force_pal_cache_flush
772 [IA-64] Avoid check_sal_cache_flush which may hang on
773 buggy SAL_CACHE_FLUSH implementations. Using this
774 parameter will force ia64_sal_cache_flush to call
775 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
778 [ftrace] will set and start the specified tracer
779 as early as possible in order to facilitate early
783 [ftrace] will dump the trace buffers on oops.
786 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
787 support via parallel port (up to 5 devices per port)
788 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
789 See also Documentation/input/joystick-parport.txt
793 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
798 See header of drivers/scsi/gdth.c.
800 gpt [EFI] Forces disk with valid GPT signature but
801 invalid Protective MBR to be treated as GPT.
805 hashdist= [KNL,NUMA] Large hashes allocated during boot
806 are distributed across NUMA nodes. Defaults on
807 for IA-64, off otherwise.
808 Format: 0 | 1 (for off | on)
810 hcl= [IA-64] SGI's Hardware Graph compatibility layer
812 hd= [EIDE] (E)IDE hard drive subsystem geometry
813 Format: <cyl>,<head>,<sect>
815 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
816 size of <nn>. This works even on boxes that have no
817 highmem otherwise. This also works to reduce highmem
818 size on bigger boxes.
820 highres= [KNL] Enable/disable high resolution timer mode.
821 Valid parameters: "on", "off"
825 See Documentation/isdn/README.HiSax.
827 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
828 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
829 On x86-64 and powerpc, this option can be specified
830 multiple times interleaved with hugepages= to reserve
831 huge pages of different sizes. Valid pages sizes on
832 x86-64 are 2M (when the CPU supports "pse") and 1G
833 (when the CPU supports the "pdpe1gb" cpuinfo flag)
834 Note that 1GB pages can only be allocated at boot time
835 using hugepages= and not freed afterwards.
837 [same as hugepagesz=] The size of the default
838 HugeTLB page size. This is the size represented by
839 the legacy /proc/ hugepages APIs, used for SHM, and
840 default size when mounting hugetlbfs filesystems.
841 Defaults to the default architecture's huge page size
846 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
847 terminal devices. Valid values: 0..8
849 i8042.debug [HW] Toggle i8042 debug mode
850 i8042.direct [HW] Put keyboard port into non-translated mode
851 i8042.dumbkbd [HW] Pretend that controller can only read data from
852 keyboard and cannot control its state
853 (Don't attempt to blink the leds)
854 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
855 i8042.nokbd [HW] Don't check/create keyboard port
856 i8042.noloop [HW] Disable the AUX Loopback command while probing
858 i8042.nomux [HW] Don't check presence of an active multiplexing
860 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
863 [HW] Frequency with which keyboard LEDs should blink
864 when kernel panics (default is 0.5 sec)
865 i8042.reset [HW] Reset the controller during init and cleanup
866 i8042.unlock [HW] Unlock (ignore) the keylock
870 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
871 indicates that the driver is running on unsupported
873 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
874 does not match list of supported models.
876 [HW] Report power status in /proc/i8k
877 (disabled by default)
878 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
881 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
882 See Documentation/mca.txt.
885 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
887 ide-core.nodma= [HW] (E)IDE subsystem
888 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
889 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
890 .chs .ignore_cable are additional options
891 See Documentation/ide/ide.txt.
893 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
894 See Documentation/ide/ide.txt.
897 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
898 Poll forces a polling idle loop that can slightly
899 improve the performance of waking up a idle CPU, but
900 will use a lot of power and make the system run hot.
902 idle=mwait: On systems which support MONITOR/MWAIT but
903 the kernel chose to not use it because it doesn't save
904 as much power as a normal idle loop, use the
905 MONITOR/MWAIT idle loop anyways. Performance should be
906 the same as idle=poll.
907 idle=halt: Halt is forced to be used for CPU idle.
908 In such case C2/C3 won't be used again.
909 idle=nomwait: Disable mwait for CPU C-states
911 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
912 Claim all unknown PCI IDE storage controllers.
914 ignore_loglevel [KNL]
915 Ignore loglevel setting - this will print /all/
916 kernel messages to the console. Useful for debugging.
919 Set number of hash buckets for inode cache.
922 See header of drivers/scsi/in2000.c.
926 Run specified binary instead of /sbin/init as init
929 initcall_debug [KNL] Trace initcalls as they are executed. Useful
930 for working out where the kernel is dying during
933 initrd= [BOOT] Specify the location of the initial ramdisk
935 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
940 iomem= Disable strict checking of access to MMIO memory
941 strict regions from userspace.
957 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
959 Enable intel iommu driver.
961 Disable intel iommu driver.
962 igfx_off [Default Off]
963 By default, gfx is mapped as normal device. If a gfx
964 device has a dedicated DMAR unit, the DMAR unit is
965 bypassed by not enabling DMAR with this option. In
966 this case, gfx device will use physical address for
969 With this option iommu will not optimize to look
970 for io virtual address below 32 bit forcing dual
971 address cycle on pci bus for cards supporting greater
972 than 32 bit addressing. The default is to look
973 for translation below 32 bit and if not available
974 then look in the higher range.
976 With this option on every unmap_single operation will
977 result in a hardware IOTLB flush operation as opposed
978 to batching them for performance.
980 io_delay= [X86-32,X86-64] I/O delay method
982 Standard port 0x80 based delay
984 Alternate port 0xed based delay (needed on some systems)
986 Simple two microseconds delay
990 io7= [HW] IO7 for Marvel based alpha systems
991 See comment before marvel_specify_io7 in
992 arch/alpha/kernel/core_marvel.c.
995 See Documentation/filesystems/nfsroot.txt.
997 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
998 See comment before ip2_setup() in
999 drivers/char/ip2/ip2base.c.
1001 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1002 See header of drivers/scsi/ips.c.
1004 ports= [IP_VS_FTP] IPVS ftp helper module
1006 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1008 Format: <port>,<port>....
1011 When an interrupt is not handled search all handlers
1012 for it. Intended to get systems with badly broken
1016 When an interrupt is not handled search all handlers
1017 for it. Also check all handlers each timer
1018 interrupt. Intended to get systems with badly broken
1022 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1024 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1026 <cpu number>,...,<cpu number>
1028 <cpu number>-<cpu number>
1029 (must be a positive range in ascending order)
1031 <cpu number>,...,<cpu number>-<cpu number>
1033 This option can be used to specify one or more CPUs
1034 to isolate from the general SMP balancing and scheduling
1035 algorithms. You can move a process onto or off an
1036 "isolated" CPU via the CPU affinity syscalls or cpuset.
1037 <cpu number> begins at 0 and the maximum value is
1038 "number of CPUs in system - 1".
1040 This option is the preferred way to isolate CPUs. The
1041 alternative -- manually setting the CPU mask of all
1042 tasks in the system -- can cause problems and
1043 suboptimal load balancer performance.
1047 js= [HW,JOY] Analog joystick
1048 See Documentation/input/joystick.txt.
1050 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1051 specifies the amount of memory usable by the kernel
1052 for non-movable allocations. The requested amount is
1053 spread evenly throughout all nodes in the system. The
1054 remaining memory in each node is used for Movable
1055 pages. In the event, a node is too small to have both
1056 kernelcore and Movable pages, kernelcore pages will
1057 take priority and other nodes will have a larger number
1058 of kernelcore pages. The Movable zone is used for the
1059 allocation of pages that may be reclaimed or moved
1060 by the page migration subsystem. This means that
1061 HugeTLB pages may not be allocated from this zone.
1062 Note that allocations like PTEs-from-HighMem still
1063 use the HighMem zone if it exists, and the Normal
1064 zone if it does not.
1066 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1067 is similar to kernelcore except it specifies the
1068 amount of memory used for migratable allocations.
1069 If both kernelcore and movablecore is specified,
1070 then kernelcore will be at *least* the specified
1071 value but may be more. If movablecore on its own
1072 is specified, the administrator must be careful
1073 that the amount of memory usable for all allocations
1078 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1081 kgdboc= [HW] kgdb over consoles.
1082 Requires a tty driver that supports console polling.
1083 (only serial suported for now)
1084 Format: <serial_device>[,baud]
1086 kmac= [MIPS] korina ethernet MAC address.
1087 Configure the RouterBoard 532 series on-chip
1088 Ethernet adapter MAC address.
1094 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1097 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1100 libata.dma= [LIBATA] DMA control
1101 libata.dma=0 Disable all PATA and SATA DMA
1102 libata.dma=1 PATA and SATA Disk DMA only
1103 libata.dma=2 ATAPI (CDROM) DMA only
1104 libata.dma=4 Compact Flash DMA only
1105 Combinations also work, so libata.dma=3 enables DMA
1106 for disks and CDROMs, but not CFs.
1108 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1112 libata.force= [LIBATA] Force configurations. The format is comma
1113 separated list of "[ID:]VAL" where ID is
1114 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1115 matching port, link or device. Basically, it matches
1116 the ATA ID string printed on console by libata. If
1117 the whole ID part is omitted, the last PORT and DEVICE
1118 values are used. If ID hasn't been specified yet, the
1119 configuration applies to all ports, links and devices.
1121 If only DEVICE is omitted, the parameter applies to
1122 the port and all links and devices behind it. DEVICE
1123 number of 0 either selects the first device or the
1124 first fan-out link behind PMP device. It does not
1125 select the host link. DEVICE number of 15 selects the
1126 host link and device attached to it.
1128 The VAL specifies the configuration to force. As long
1129 as there's no ambiguity shortcut notation is allowed.
1130 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1131 The following configurations can be forced.
1133 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1134 Any ID with matching PORT is used.
1136 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1138 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1139 udma[/][16,25,33,44,66,100,133] notation is also
1142 * [no]ncq: Turn on or off NCQ.
1144 * nohrst, nosrst, norst: suppress hard, soft
1147 If there are multiple matching configurations changing
1148 the same attribute, the last one is used.
1150 lmb=debug [KNL] Enable lmb debug messages.
1152 load_ramdisk= [RAM] List of ramdisks to load from floppy
1153 See Documentation/blockdev/ramdisk.txt.
1155 lockd.nlm_grace_period=P [NFS] Assign grace period.
1158 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1161 lockd.nlm_timeout=T [NFS] Assign timeout value.
1164 lockd.nlm_udpport=M [NFS] Assign UDP port.
1167 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1170 loglevel= All Kernel Messages with a loglevel smaller than the
1171 console loglevel will be printed to the console. It can
1172 also be changed with klogd or other programs. The
1173 loglevels are defined as follows:
1175 0 (KERN_EMERG) system is unusable
1176 1 (KERN_ALERT) action must be taken immediately
1177 2 (KERN_CRIT) critical conditions
1178 3 (KERN_ERR) error conditions
1179 4 (KERN_WARNING) warning conditions
1180 5 (KERN_NOTICE) normal but significant condition
1181 6 (KERN_INFO) informational
1182 7 (KERN_DEBUG) debug-level messages
1184 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1185 Format: { n | nk | nM }
1186 n must be a power of two. The default size
1187 is set in the kernel config file.
1189 logo.nologo [FB] Disables display of the built-in Linux logo.
1190 This may be used to provide more screen space for
1191 kernel log messages and is useful when debugging
1192 kernel boot problems.
1194 lp=0 [LP] Specify parallel ports to use, e.g,
1195 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1196 lp=reset first parallel port). 'lp=0' disables the
1197 lp=auto printer driver. 'lp=reset' (which can be
1198 specified in addition to the ports) causes
1199 attached printers to be reset. Using
1200 lp=port1,port2,... specifies the parallel ports
1201 to associate lp devices with, starting with
1202 lp0. A port specification may be 'none' to skip
1203 that lp device, or a parport name such as
1204 'parport0'. Specifying 'lp=auto' instead of a
1205 port specification list means that device IDs
1206 from each port should be examined, to see if
1207 an IEEE 1284-compliant printer is attached; if
1208 so, the driver will manage that printer.
1209 See also header of drivers/char/lp.c.
1212 Sets loops_per_jiffy to given constant, thus avoiding
1213 time-consuming boot-time autodetection (up to 250 ms per
1214 CPU). 0 enables autodetection (default). To determine
1215 the correct value for your kernel, boot with normal
1216 autodetection and see what value is printed. Note that
1217 on SMP systems the preset will be applied to all CPUs,
1218 which is likely to cause problems if your CPUs need
1219 significantly divergent settings. An incorrect value
1220 will cause delays in the kernel to be wrong, leading to
1221 unpredictable I/O errors and other breakage. Although
1222 unlikely, in the extreme case this might damage your
1226 Format: <io>,<irq>,<dma>
1228 mac5380= [HW,SCSI] Format:
1229 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1231 machvec= [IA64] Force the use of a particular machine-vector
1232 (machvec) in a generic kernel.
1233 Example: machvec=hpzx1_swiotlb
1235 max_loop= [LOOP] Maximum number of loopback devices that can
1239 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1240 should make use of. maxcpus=n : n >= 0 limits the
1241 kernel to using 'n' processors. n=0 is a special case,
1242 it is equivalent to "nosmp", which also disables
1245 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1246 or equal to this physical address is ignored.
1248 max_luns= [SCSI] Maximum number of LUNs to probe.
1249 Should be between 1 and 2^32-1.
1252 [SCSI] Maximum number of LUNs received.
1253 Should be between 1 and 16384.
1257 mce [X86-32] Machine Check Exception
1259 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1261 md= [HW] RAID subsystems devices and level
1262 See Documentation/md.txt.
1265 Format: <first>,<last>
1266 Specifies range of consoles to be captured by the MDA.
1268 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1269 Amount of memory to be used when the kernel is not able
1270 to see the whole system memory or for test.
1271 [X86-32] Use together with memmap= to avoid physical
1272 address space collisions. Without memmap= PCI devices
1273 could be placed at addresses belonging to unused RAM.
1275 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1279 [KNL,SH] Allow user to override the default size for
1280 per-device physically contiguous DMA buffers.
1282 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1283 E820 memory map, as specified by the user.
1284 Such memmap=exactmap lines can be constructed based on
1285 BIOS output or other requirements. See the memmap=nn@ss
1288 memmap=nn[KMG]@ss[KMG]
1289 [KNL] Force usage of a specific region of memory
1290 Region of memory to be used, from ss to ss+nn.
1292 memmap=nn[KMG]#ss[KMG]
1293 [KNL,ACPI] Mark specific memory as ACPI data.
1294 Region of memory to be used, from ss to ss+nn.
1296 memmap=nn[KMG]$ss[KMG]
1297 [KNL,ACPI] Mark specific memory as reserved.
1298 Region of memory to be used, from ss to ss+nn.
1299 Example: Exclude memory from 0x18690000-0x1869ffff
1300 memmap=64K$0x18690000
1302 memmap=0x10000$0x18690000
1304 memory_corruption_check=0/1 [X86]
1305 Some BIOSes seem to corrupt the first 64k of
1306 memory when doing things like suspend/resume.
1307 Setting this option will scan the memory
1308 looking for corruption. Enabling this will
1309 both detect corruption and prevent the kernel
1310 from using the memory being corrupted.
1311 However, its intended as a diagnostic tool; if
1312 repeatable BIOS-originated corruption always
1313 affects the same memory, you can use memmap=
1314 to prevent the kernel from using that memory.
1316 memory_corruption_check_size=size [X86]
1317 By default it checks for corruption in the low
1318 64k, making this memory unavailable for normal
1319 use. Use this parameter to scan for
1320 corruption in more or less memory.
1322 memory_corruption_check_period=seconds [X86]
1323 By default it checks for corruption every 60
1324 seconds. Use this parameter to check at some
1325 other rate. 0 disables periodic checking.
1327 memtest= [KNL,X86] Enable memtest
1329 range: 0,4 : pattern number
1330 default : 0 <disable>
1332 meye.*= [HW] Set MotionEye Camera parameters
1333 See Documentation/video4linux/meye.txt.
1335 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1336 Multi-Function General Purpose Timers on AMD Geode
1339 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1340 the BIOS has incorrectly applied a workaround. TinyBIOS
1341 version 0.98 is known to be affected, 0.99 fixes the
1342 problem by letting the user disable the workaround.
1346 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1347 physical address is ignored.
1350 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1351 parameter allows control of the logging verbosity for
1352 the additional memory initialisation checks. A value
1353 of 0 disables mminit logging and a level of 4 will
1354 log everything. Information is printed at KERN_DEBUG
1355 so loglevel=8 may also need to be specified.
1358 [MOUSE] Maximum time between finger touching and
1359 leaving touchpad surface for touch to be considered
1360 a tap and be reported as a left button click (for
1361 touchpads working in absolute mode only).
1363 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1364 reporting absolute coordinates, such as tablets
1365 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1366 reporting absolute coordinates, such as tablets
1371 MTD_Partition= [MTD]
1372 Format: <name>,<region-number>,<size>,<offset>
1374 MTD_Region= [MTD] Format:
1375 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1378 See drivers/mtd/cmdlinepart.c.
1381 ARM/S3C2412 JIVE boot control
1383 See arch/arm/mach-s3c2412/mach-jive.c
1385 mtouchusb.raw_coordinates=
1386 [HW] Make the MicroTouch USB driver use raw coordinates
1387 ('y', default) or cooked coordinates ('n')
1389 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1392 See header of drivers/scsi/NCR_D700.c.
1396 ncr53c400= [HW,SCSI]
1398 ncr53c400a= [HW,SCSI]
1400 ncr53c406a= [HW,SCSI]
1402 ncr53c8xx= [HW,SCSI]
1404 netdev= [NET] Network devices parameters
1405 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1406 Note that mem_start is often overloaded to mean
1407 something different and driver-specific.
1408 This usage is only documented in each driver source
1412 [NETFILTER] Enable connection tracking flow accounting
1413 0 to disable accounting
1414 1 to enable accounting
1415 Default value depends on CONFIG_NF_CT_ACCT that is
1416 going to be removed in 2.6.29.
1419 See Documentation/filesystems/nfsroot.txt.
1421 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1422 See Documentation/filesystems/nfsroot.txt.
1424 nfs.callback_tcpport=
1425 [NFS] set the TCP port on which the NFSv4 callback
1426 channel should listen.
1428 nfs.idmap_cache_timeout=
1429 [NFS] set the maximum lifetime for idmapper cache
1433 [NFS] enable 64-bit inode numbers.
1434 If zero, the NFS client will fake up a 32-bit inode
1435 number for the readdir() and stat() syscalls instead
1436 of returning the full 64-bit number.
1437 The default is to return 64-bit inode numbers.
1439 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1440 when a NMI is triggered.
1441 Format: [state][,regs][,debounce][,die]
1443 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1444 Format: [panic,][num]
1446 0 - turn nmi_watchdog off
1447 1 - use the IO-APIC timer for the NMI watchdog
1448 2 - use the local APIC for the NMI watchdog using
1449 a performance counter. Note: This will use one performance
1450 counter and the local APIC's performance vector.
1451 When panic is specified panic when an NMI watchdog timeout occurs.
1452 This is useful when you use a panic=... timeout and need the box
1454 Instead of 1 and 2 it is possible to use the following
1455 symbolic names: lapic and ioapic
1456 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1458 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1459 emulation library even if a 387 maths coprocessor
1462 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1463 caches in the slab allocator. Saves per-node memory,
1464 but will impact performance.
1468 noapic [SMP,APIC] Tells the kernel to not make use of any
1469 IOAPICs that may be present in the system.
1471 nobats [PPC] Do not use BATs for mapping kernel lowmem
1472 on "Classic" PPC cores.
1476 nodelayacct [KNL] Disable per-task delay accounting
1478 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1480 nodsp [SH] Disable hardware DSP at boot time.
1482 noefi [X86-32,X86-64] Disable EFI runtime services support.
1486 noexec [X86-32,X86-64]
1487 On X86-32 available only on PAE configured kernels.
1488 noexec=on: enable non-executable mappings (default)
1489 noexec=off: disable non-executable mappings
1492 This affects only 32-bit executables.
1493 noexec32=on: enable non-executable mappings (default)
1494 read doesn't imply executable mappings
1495 noexec32=off: disable non-executable mappings
1496 read implies executable mappings
1498 nofpu [SH] Disable hardware FPU at boot time.
1500 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1501 register save and restore. The kernel will only save
1502 legacy floating-point registers on task switch.
1504 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1508 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1509 instruction doesn't work correctly and not to
1512 no_file_caps Tells the kernel not to honor file capabilities. The
1513 only way then for a file to be executed with privilege
1514 is to be setuid root or executed by root.
1516 nohalt [IA-64] Tells the kernel not to use the power saving
1517 function PAL_HALT_LIGHT when idle. This increases
1518 power-consumption. On the positive side, it reduces
1519 interrupt wake-up latency, which may improve performance
1520 in certain environments such as networked servers or
1523 nohz= [KNL] Boottime enable/disable dynamic ticks
1524 Valid arguments: on, off
1527 noirqdebug [X86-32] Disables the code which attempts to detect and
1528 disable unhandled interrupt sources.
1530 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1531 broken timer IRQ sources.
1533 noisapnp [ISAPNP] Disables ISA PnP code.
1535 noinitrd [RAM] Tells the kernel not to load any configured
1540 nojitter [IA64] Disables jitter checking for ITC timers.
1542 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1544 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1546 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1548 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1549 default x2apic cluster mode on platforms
1552 noltlbs [PPC] Do not use large page/tlb entries for kernel
1553 lowmem mapping on PPC40x.
1555 nomca [IA-64] Disable machine check abort handling
1557 nomce [X86-32] Machine Check Exception
1559 nomfgpt [X86-32] Disable Multi-Function General Purpose
1560 Timer usage (for AMD Geode machines).
1562 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1564 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1565 with UP alternatives
1567 noresidual [PPC] Don't use residual data on PReP machines.
1569 noresume [SWSUSP] Disables resume and restores original swap
1572 no-scroll [VGA] Disables scrollback.
1573 This is required for the Braillex ib80-piezo Braille
1574 reader made by F.H. Papenmeier (Germany).
1578 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1580 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1581 and disable the IO APIC. legacy for "maxcpus=0".
1583 nosoftlockup [KNL] Disable the soft-lockup detector.
1585 noswapaccount [KNL] Disable accounting of swap in memory resource
1586 controller. (See Documentation/controllers/memory.txt)
1588 nosync [HW,M68K] Disables sync negotiation for all devices.
1590 notsc [BUGS=X86-32] Disable Time Stamp Counter
1592 nousb [USB] Disable the USB subsystem
1596 nptcg= [IA64] Override max number of concurrent global TLB
1597 purges which is reported from either PAL_VM_SUMMARY or
1600 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1601 one of ['zone', 'node', 'default'] can be specified
1602 This can be set from sysctl after boot.
1603 See Documentation/sysctl/vm.txt for details.
1605 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1607 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1608 See Documentation/debugging-via-ohci1394.txt for more
1611 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1612 Rather than timing out after 20 ms if an EC
1613 command is not properly ACKed, override the length
1614 of the timeout. We have interrupts disabled while
1615 waiting for the ACK, so if this is set too high
1616 interrupts *may* be lost!
1621 oprofile.timer= [HW]
1622 Use timer interrupt instead of performance counters
1624 osst= [HW,SCSI] SCSI Tape Driver
1625 Format: <buffer_size>,<write_threshold>
1626 See also Documentation/scsi/st.txt.
1628 panic= [KNL] Kernel behaviour on panic
1631 parkbd.port= [HW] Parallel port number the keyboard adapter is
1632 connected to, default is 0.
1634 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1635 0 for XT, 1 for AT (default is AT).
1638 parport= [HW,PPT] Specify parallel ports. 0 disables.
1639 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1640 Use 'auto' to force the driver to use any
1641 IRQ/DMA settings detected (the default is to
1642 ignore detected IRQ/DMA settings because of
1643 possible conflicts). You can specify the base
1644 address, IRQ, and DMA settings; IRQ and DMA
1645 should be numbers, or 'auto' (for using detected
1646 settings on that particular port), or 'nofifo'
1647 (to avoid using a FIFO even if it is detected).
1648 Parallel ports are assigned in the order they
1649 are specified on the command line, starting
1652 parport_init_mode= [HW,PPT]
1653 Configure VIA parallel port to operate in
1654 a specific mode. This is necessary on Pegasos
1655 computer where firmware has no options for setting
1656 up parallel port mode and sets it to spp.
1657 Currently this function knows 686a and 8231 chips.
1658 Format: [spp|ps2|epp|ecp|ecpepp]
1660 pas2= [HW,OSS] Format:
1661 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1664 See header of drivers/scsi/pas16.c.
1667 Halt all CPUs after the first oops has been printed for
1668 the specified number of seconds. This is to be used if
1669 your oopses keep scrolling off the screen.
1674 See header of drivers/block/paride/pcd.c.
1675 See also Documentation/blockdev/paride.txt.
1677 pci=option[,option...] [PCI] various PCI subsystem options:
1678 off [X86] don't probe for the PCI bus
1679 bios [X86-32] force use of PCI BIOS, don't access
1680 the hardware directly. Use this if your machine
1681 has a non-standard PCI host bridge.
1682 nobios [X86-32] disallow use of PCI BIOS, only direct
1683 hardware access methods are allowed. Use this
1684 if you experience crashes upon bootup and you
1685 suspect they are caused by the BIOS.
1686 conf1 [X86] Force use of PCI Configuration
1688 conf2 [X86] Force use of PCI Configuration
1690 noaer [PCIE] If the PCIEAER kernel config parameter is
1691 enabled, this kernel boot option can be used to
1692 disable the use of PCIE advanced error reporting.
1693 nodomains [PCI] Disable support for multiple PCI
1694 root domains (aka PCI segments, in ACPI-speak).
1695 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1697 nomsi [MSI] If the PCI_MSI kernel config parameter is
1698 enabled, this kernel boot option can be used to
1699 disable the use of MSI interrupts system-wide.
1700 noioapicquirk [APIC] Disable all boot interrupt quirks.
1701 Safety option to keep boot IRQs enabled. This
1702 should never be necessary.
1703 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1704 primary IO-APIC for bridges that cannot disable
1705 boot IRQs. This fixes a source of spurious IRQs
1706 when the system masks IRQs.
1707 noioapicreroute [APIC] Disable workaround that uses the
1708 boot IRQ equivalent of an IRQ that connects to
1709 a chipset where boot IRQs cannot be disabled.
1710 The opposite of ioapicreroute.
1711 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1712 routing table. These calls are known to be buggy
1713 on several machines and they hang the machine
1714 when used, but on other computers it's the only
1715 way to get the interrupt routing table. Try
1716 this option if the kernel is unable to allocate
1717 IRQs or discover secondary PCI buses on your
1719 rom [X86] Assign address space to expansion ROMs.
1720 Use with caution as certain devices share
1721 address decoders between ROMs and other
1723 norom [X86] Do not assign address space to
1724 expansion ROMs that do not already have
1725 BIOS assigned address ranges.
1726 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1727 assigned automatically to PCI devices. You can
1728 make the kernel exclude IRQs of your ISA cards
1730 pirqaddr=0xAAAAA [X86] Specify the physical address
1731 of the PIRQ table (normally generated
1732 by the BIOS) if it is outside the
1733 F0000h-100000h range.
1734 lastbus=N [X86] Scan all buses thru bus #N. Can be
1735 useful if the kernel is unable to find your
1736 secondary buses and you want to tell it
1737 explicitly which ones they are.
1738 assign-busses [X86] Always assign all PCI bus
1739 numbers ourselves, overriding
1740 whatever the firmware may have done.
1741 usepirqmask [X86] Honor the possible IRQ mask stored
1742 in the BIOS $PIR table. This is needed on
1743 some systems with broken BIOSes, notably
1744 some HP Pavilion N5400 and Omnibook XE3
1745 notebooks. This will have no effect if ACPI
1746 IRQ routing is enabled.
1747 noacpi [X86] Do not use ACPI for IRQ routing
1748 or for PCI scanning.
1749 use_crs [X86] Use _CRS for PCI resource
1751 routeirq Do IRQ routing for all PCI devices.
1752 This is normally done in pci_enable_device(),
1753 so this option is a temporary workaround
1754 for broken drivers that don't call it.
1755 skip_isa_align [X86] do not align io start addr, so can
1756 handle more pci cards
1757 firmware [ARM] Do not re-enumerate the bus but instead
1758 just use the configuration from the
1759 bootloader. This is currently used on
1760 IXP2000 systems where the bus has to be
1761 configured a certain way for adjunct CPUs.
1762 noearly [X86] Don't do any early type 1 scanning.
1763 This might help on some broken boards which
1764 machine check when some devices' config space
1765 is read. But various workarounds are disabled
1766 and some IOMMU drivers will not work.
1767 bfsort Sort PCI devices into breadth-first order.
1768 This sorting is done to get a device
1769 order compatible with older (<= 2.4) kernels.
1770 nobfsort Don't sort PCI devices into breadth-first order.
1771 cbiosize=nn[KMG] The fixed amount of bus space which is
1772 reserved for the CardBus bridge's IO window.
1773 The default value is 256 bytes.
1774 cbmemsize=nn[KMG] The fixed amount of bus space which is
1775 reserved for the CardBus bridge's memory
1776 window. The default value is 64 megabytes.
1778 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1781 force Enable ASPM even on devices that claim not to support it.
1782 WARNING: Forcing ASPM on may cause system lockups.
1784 pcmv= [HW,PCMCIA] BadgePAD 4
1787 See Documentation/blockdev/paride.txt.
1789 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1792 See arch/parisc/kernel/pdc_chassis.c
1795 See Documentation/blockdev/paride.txt.
1798 See Documentation/blockdev/paride.txt.
1800 pirq= [SMP,APIC] Manual mp-table setup
1801 See Documentation/x86/i386/IO-APIC.txt.
1803 plip= [PPT,NET] Parallel port network link
1804 Format: { parport<nr> | timid | 0 }
1805 See also Documentation/parport.txt.
1807 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1808 Override pmtimer IOPort with a hex value.
1812 Enable PNP debug messages. This depends on the
1813 CONFIG_PNP_DEBUG_MESSAGES option.
1819 { on | off | curr | res | no-curr | no-res }
1822 [ISAPNP] Exclude IRQs for the autoconfiguration
1825 [ISAPNP] Exclude DMAs for the autoconfiguration
1827 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1828 Ranges are in pairs (I/O port base and size).
1831 [ISAPNP] Exclude memory regions for the
1833 Ranges are in pairs (memory base and size).
1835 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1836 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1837 These can also be switched on/off via
1838 <debugfs>/dynamic_printk/modules
1840 print-fatal-signals=
1841 [KNL] debug: print fatal signals
1842 print-fatal-signals=1: print segfault info to
1846 printk.time= Show timing data prefixed to each printk message line
1847 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1849 profile= [KNL] Enable kernel profiling via /proc/profile
1850 Format: [schedule,]<number>
1851 Param: "schedule" - profile schedule points.
1852 Param: <number> - step/bucket size as a power of 2 for
1853 statistical time based profiling.
1854 Param: "sleep" - profile D-state sleeping (millisecs).
1855 Requires CONFIG_SCHEDSTATS
1856 Param: "kvm" - profile VM exits.
1858 processor.max_cstate= [HW,ACPI]
1859 Limit processor to maximum C-state
1860 max_cstate=9 overrides any DMI blacklist limit.
1862 processor.nocst [HW,ACPI]
1863 Ignore the _CST method to determine C-states,
1864 instead using the legacy FADT method
1866 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1868 See Documentation/blockdev/ramdisk.txt.
1870 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1871 probe for; one of (bare|imps|exps|lifebook|any).
1872 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1874 psmouse.resetafter= [HW,MOUSE]
1875 Try to reset the device after so many bad packets
1878 [HW,MOUSE] Set desired mouse resolution, in dpi.
1879 psmouse.smartscroll=
1880 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1881 0 = disabled, 1 = enabled (default).
1883 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1885 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1888 See Documentation/blockdev/paride.txt.
1891 [KNL] Number of legacy pty's. Overwrites compiled-in
1894 quiet [KNL] Disable most log messages
1899 See Documentation/md.txt.
1901 ramdisk_blocksize= [RAM]
1902 See Documentation/blockdev/ramdisk.txt.
1904 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1905 See Documentation/blockdev/ramdisk.txt.
1907 rcupdate.blimit= [KNL,BOOT]
1908 Set maximum number of finished RCU callbacks to process
1911 rcupdate.qhimark= [KNL,BOOT]
1912 Set threshold of queued
1913 RCU callbacks over which batch limiting is disabled.
1915 rcupdate.qlowmark= [KNL,BOOT]
1916 Set threshold of queued RCU callbacks below which
1917 batch limiting is re-enabled.
1921 Run specified binary instead of /init from the ramdisk,
1922 used for early userspace startup. See initrd.
1924 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1925 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1926 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1929 [KNL, SMP] Set scheduler's default relax_domain_level.
1930 See Documentation/cpusets.txt.
1932 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1934 reservetop= [X86-32]
1936 Reserves a hole at the top of the kernel virtual
1939 reset_devices [KNL] Force drivers to reset the underlying device
1940 during initialization.
1943 Specify the partition device for software suspend
1945 resume_offset= [SWSUSP]
1946 Specify the offset from the beginning of the partition
1947 given by "resume=" at which the swap header is located,
1948 in <PAGE_SIZE> units (needed only for swap files).
1949 See Documentation/power/swsusp-and-swap-files.txt
1951 retain_initrd [RAM] Keep initrd memory after extraction
1953 rhash_entries= [KNL,NET]
1954 Set number of hash buckets for route cache
1956 riscom8= [HW,SERIAL]
1957 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1959 ro [KNL] Mount root device read-only on boot
1961 root= [KNL] Root filesystem
1963 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1964 mount the root filesystem
1966 rootflags= [KNL] Set root filesystem mount option string
1968 rootfstype= [KNL] Set root filesystem type
1970 rootwait [KNL] Wait (indefinitely) for root device to show up.
1971 Useful for devices that are detected asynchronously
1972 (e.g. USB and MMC devices).
1974 root_plug.vendor_id=
1975 [ROOTPLUG] Override the default vendor ID
1977 root_plug.product_id=
1978 [ROOTPLUG] Override the default product ID
1981 [ROOTPLUG] Enable debugging output
1983 rw [KNL] Mount root device read-write on boot
1985 S [KNL] Run init in single mode
1988 See drivers/net/irda/sa1100_ir.c.
1990 sbni= [NET] Granch SBNI12 leased line adapter
1992 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1993 Format: <io>[,<timeout>[,<isapnp>]]
1995 scsi_debug_*= [SCSI]
1996 See drivers/scsi/scsi_debug.c.
1998 scsi_default_dev_flags=
1999 [SCSI] SCSI default device flags
2002 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2003 Format: <vendor>:<model>:<flags>
2004 (flags are integer value)
2006 scsi_logging_level= [SCSI] a bit mask of logging levels
2007 See drivers/scsi/scsi_logging.h for bits. Also
2008 settable via sysctl at dev.scsi.logging_level
2009 (/proc/sys/dev/scsi/logging_level).
2010 There is also a nice 'scsi_logging_level' script in the
2011 S390-tools package, available for download at
2012 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2014 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2015 discovered. async scans them in kernel threads,
2016 allowing boot to proceed. none ignores them, expecting
2017 user space to do the scan.
2019 selinux [SELINUX] Disable or enable SELinux at boot time.
2020 Format: { "0" | "1" }
2021 See security/selinux/Kconfig help text.
2024 Default value is set via kernel config option.
2025 If enabled at boot time, /selinux/disable can be used
2026 later to disable prior to initial policy load.
2028 selinux_compat_net =
2029 [SELINUX] Set initial selinux_compat_net flag value.
2030 Format: { "0" | "1" }
2031 0 -- use new secmark-based packet controls
2032 1 -- use legacy packet controls
2033 Default value is 0 (preferred).
2034 Value can be changed at runtime via
2035 /selinux/compat_net.
2037 serialnumber [BUGS=X86-32]
2040 Maximal number of shapers.
2042 show_msr= [x86] show boot-time MSR settings
2043 Format: { <integer> }
2044 Show boot-time (BIOS-initialized) MSR settings.
2045 The parameter means the number of CPUs to show,
2046 for example 1 means boot CPU only.
2049 See header of drivers/scsi/sim710.c.
2056 slub_debug[=options[,slabs]] [MM, SLUB]
2057 Enabling slub_debug allows one to determine the
2058 culprit if slab objects become corrupted. Enabling
2059 slub_debug can create guard zones around objects and
2060 may poison objects when not in use. Also tracks the
2061 last alloc / free. For more information see
2062 Documentation/vm/slub.txt.
2064 slub_max_order= [MM, SLUB]
2065 Determines the maximum allowed order for slabs.
2066 A high setting may cause OOMs due to memory
2067 fragmentation. For more information see
2068 Documentation/vm/slub.txt.
2070 slub_min_objects= [MM, SLUB]
2071 The minimum number of objects per slab. SLUB will
2072 increase the slab order up to slub_max_order to
2073 generate a sufficiently large slab able to contain
2074 the number of objects indicated. The higher the number
2075 of objects the smaller the overhead of tracking slabs
2076 and the less frequently locks need to be acquired.
2077 For more information see Documentation/vm/slub.txt.
2079 slub_min_order= [MM, SLUB]
2080 Determines the mininum page order for slabs. Must be
2081 lower than slub_max_order.
2082 For more information see Documentation/vm/slub.txt.
2084 slub_nomerge [MM, SLUB]
2085 Disable merging of slabs with similar size. May be
2086 necessary if there is some reason to distinguish
2087 allocs to different slabs. Debug options disable
2088 merging on their own.
2089 For more information see Documentation/vm/slub.txt.
2092 Format: <io1>[,<io2>[,...,<io8>]]
2094 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2095 attempt to substitute SMP alternatives once at boot.
2097 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2098 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2099 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2100 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2101 smsc-ircc2.ircc_irq= [HW] IRQ line
2102 smsc-ircc2.ircc_dma= [HW] DMA channel
2103 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2104 0: Toshiba Satellite 1800 (GP data pin select)
2105 1: Fast pin select (default)
2108 snd-ad1816a= [HW,ALSA]
2110 snd-ad1848= [HW,ALSA]
2112 snd-ali5451= [HW,ALSA]
2114 snd-als100= [HW,ALSA]
2116 snd-als4000= [HW,ALSA]
2118 snd-azt2320= [HW,ALSA]
2120 snd-cmi8330= [HW,ALSA]
2122 snd-cmipci= [HW,ALSA]
2124 snd-cs4231= [HW,ALSA]
2126 snd-cs4232= [HW,ALSA]
2128 snd-cs4236= [HW,ALSA]
2130 snd-cs4281= [HW,ALSA]
2132 snd-cs46xx= [HW,ALSA]
2134 snd-dt019x= [HW,ALSA]
2136 snd-dummy= [HW,ALSA]
2138 snd-emu10k1= [HW,ALSA]
2140 snd-ens1370= [HW,ALSA]
2142 snd-ens1371= [HW,ALSA]
2144 snd-es968= [HW,ALSA]
2146 snd-es1688= [HW,ALSA]
2148 snd-es18xx= [HW,ALSA]
2150 snd-es1938= [HW,ALSA]
2152 snd-es1968= [HW,ALSA]
2154 snd-fm801= [HW,ALSA]
2156 snd-gusclassic= [HW,ALSA]
2158 snd-gusextreme= [HW,ALSA]
2160 snd-gusmax= [HW,ALSA]
2164 snd-ice1712= [HW,ALSA]
2166 snd-intel8x0= [HW,ALSA]
2168 snd-interwave= [HW,ALSA]
2173 snd-korg1212= [HW,ALSA]
2175 snd-maestro3= [HW,ALSA]
2177 snd-mpu401= [HW,ALSA]
2179 snd-mtpav= [HW,ALSA]
2181 snd-nm256= [HW,ALSA]
2183 snd-opl3sa2= [HW,ALSA]
2191 snd-opti93x= [HW,ALSA]
2195 snd-rme32= [HW,ALSA]
2197 snd-rme96= [HW,ALSA]
2199 snd-rme9652= [HW,ALSA]
2205 snd-sbawe= [HW,ALSA]
2207 snd-serial= [HW,ALSA]
2209 snd-sgalaxy= [HW,ALSA]
2211 snd-sonicvibes= [HW,ALSA]
2216 snd-sun-cs4231= [HW,ALSA]
2218 snd-trident= [HW,ALSA]
2220 snd-usb-audio= [HW,ALSA,USB]
2222 snd-via82xx= [HW,ALSA]
2224 snd-virmidi= [HW,ALSA]
2226 snd-wavefront= [HW,ALSA]
2228 snd-ymfpci= [HW,ALSA]
2231 [KNL] Should the soft-lockup detector generate panics.
2233 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2234 See Documentation/sonypi.txt
2236 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2237 See Documentation/serial/specialix.txt.
2239 spia_io_base= [HW,MTD]
2245 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2247 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2248 See Documentation/scsi/st.txt.
2251 Enabled the stack tracer on boot up.
2255 Set the STI (builtin display/keyboard on the HP-PARISC
2256 machines) console (graphic card) which should be used
2257 as the initial boot-console.
2258 See also comment in drivers/video/console/sticore.c.
2261 See comment in drivers/video/console/sticore.c.
2264 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2268 Control how the NFS server code allocates CPUs to
2269 service thread pools. Depending on how many NICs
2270 you have and where their interrupts are bound, this
2271 option will affect which CPUs will do NFS serving.
2272 Note: this parameter cannot be changed while the
2273 NFS server is running.
2275 auto the server chooses an appropriate mode
2276 automatically using heuristics
2277 global a single global pool contains all CPUs
2278 percpu one pool for each CPU
2279 pernode one pool for each NUMA node (equivalent
2280 to global on non-NUMA machines)
2282 swiotlb= [IA-64] Number of I/O TLB slabs
2286 sym53c416= [HW,SCSI]
2287 See header of drivers/scsi/sym53c416.c.
2289 sysrq_always_enabled
2291 Ignore sysrq setting - this boot parameter will
2292 neutralize any effect of /proc/sys/kernel/sysrq.
2293 Useful for debugging.
2296 See header of drivers/scsi/t128.c.
2300 test_suspend= [SUSPEND]
2301 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2302 standby suspend) as the system sleep state to briefly
2303 enter during system startup. The system is woken from
2304 this state using a wakeup-capable RTC alarm.
2306 thash_entries= [KNL,NET]
2307 Set number of hash buckets for TCP connection
2309 thermal.act= [HW,ACPI]
2310 -1: disable all active trip points in all thermal zones
2311 <degrees C>: override all lowest active trip points
2313 thermal.crt= [HW,ACPI]
2314 -1: disable all critical trip points in all thermal zones
2315 <degrees C>: override all critical trip points
2317 thermal.nocrt= [HW,ACPI]
2318 Set to disable actions on ACPI thermal zone
2319 critical and hot trip points.
2321 thermal.off= [HW,ACPI]
2322 1: disable ACPI thermal control
2324 thermal.psv= [HW,ACPI]
2325 -1: disable all passive trip points
2326 <degrees C>: override all passive trip points to this
2329 thermal.tzp= [HW,ACPI]
2330 Specify global default ACPI thermal zone polling rate
2331 <deci-seconds>: poll all this frequency
2332 0: no polling (default)
2335 See comment before function dc390_setup() in
2336 drivers/scsi/tmscsim.c.
2340 Specify if the kernel should make use of the cpu
2341 topology informations if the hardware supports these.
2342 The scheduler will make use of these informations and
2343 e.g. base its process migration decisions on it.
2348 trix= [HW,OSS] MediaTrix AudioTrix Pro
2350 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2352 tsc= Disable clocksource-must-verify flag for TSC.
2354 [x86] reliable: mark tsc clocksource as reliable, this
2355 disables clocksource verification at runtime.
2356 Used to enable high-resolution timer mode on older
2357 hardware, and in virtualized environment.
2359 turbografx.map[2|3]= [HW,JOY]
2360 TurboGraFX parallel port interface
2362 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2363 See also Documentation/input/joystick-parport.txt
2365 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2366 See header of drivers/scsi/u14-34f.c.
2375 [USB] Ignore overcurrent events (default N).
2376 Some badly-designed motherboards generate lots of
2377 bogus events, for ports that aren't wired to
2378 anything. Set this parameter to avoid log spamming.
2379 Note that genuine overcurrent events won't be
2384 Set unknown_nmi_panic=1 early on boot.
2386 usbcore.autosuspend=
2387 [USB] The autosuspend time delay (in seconds) used
2388 for newly-detected USB devices (default 2). This
2389 is the time required before an idle device will be
2390 autosuspended. Devices for which the delay is set
2391 to a negative value won't be autosuspended at all.
2393 usbcore.usbfs_snoop=
2394 [USB] Set to log all usbfs traffic (default 0 = off).
2396 usbcore.blinkenlights=
2397 [USB] Set to cycle leds on hubs (default 0 = off).
2399 usbcore.old_scheme_first=
2400 [USB] Start with the old device initialization
2401 scheme (default 0 = off).
2403 usbcore.use_both_schemes=
2404 [USB] Try the other device initialization scheme
2405 if the first one fails (default 1 = enabled).
2407 usbcore.initial_descriptor_timeout=
2408 [USB] Specifies timeout for the initial 64-byte
2409 USB_REQ_GET_DESCRIPTOR request in milliseconds
2410 (default 5000 = 5.0 seconds).
2413 [USBHID] The interval which mice are to be polled at.
2415 usb-storage.delay_use=
2416 [UMS] The delay in seconds before a new device is
2417 scanned for Logical Units (default 5).
2420 [UMS] A list of quirks entries to supplement or
2421 override the built-in unusual_devs list. List
2422 entries are separated by commas. Each entry has
2423 the form VID:PID:Flags where VID and PID are Vendor
2424 and Product ID values (4-digit hex numbers) and
2425 Flags is a set of characters, each corresponding
2426 to a common usb-storage quirk flag as follows:
2427 a = SANE_SENSE (collect more than 18 bytes
2429 c = FIX_CAPACITY (decrease the reported
2430 device capacity by one sector);
2431 h = CAPACITY_HEURISTICS (decrease the
2432 reported device capacity by one
2433 sector if the number is odd);
2434 i = IGNORE_DEVICE (don't bind to this
2436 l = NOT_LOCKABLE (don't try to lock and
2437 unlock ejectable media);
2438 m = MAX_SECTORS_64 (don't transfer more
2439 than 64 sectors = 32 KB at a time);
2440 o = CAPACITY_OK (accept the capacity
2441 reported by the device);
2442 r = IGNORE_RESIDUE (the device reports
2443 bogus residue values);
2444 s = SINGLE_LUN (the device has only one
2446 w = NO_WP_DETECT (don't test whether the
2447 medium is write-protected).
2448 Example: quirks=0419:aaf5:rl,0421:0433:rc
2450 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2451 kernel's map of available physical RAM.
2453 vdso= [X86-32,SH,x86-64]
2454 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2455 vdso=1: enable VDSO (default)
2456 vdso=0: disable VDSO mapping
2458 vdso32= [X86-32,X86-64]
2459 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2460 vdso32=1: enable 32-bit VDSO (default)
2461 vdso32=0: disable 32-bit VDSO mapping
2464 vector=percpu: enable percpu vector domain
2466 video= [FB] Frame buffer configuration
2467 See Documentation/fb/modedb.txt.
2469 vga= [BOOT,X86-32] Select a particular video mode
2470 See Documentation/x86/boot.txt and
2471 Documentation/svga.txt.
2472 Use vga=ask for menu.
2473 This is actually a boot loader parameter; the value is
2474 passed to the kernel using a special protocol.
2476 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2477 size of <nn>. This can be used to increase the
2478 minimum size (128MB on x86). It can also be used to
2479 decrease the size and leave more room for directly
2482 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2485 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2488 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2491 waveartist= [HW,OSS]
2492 Format: <io>,<irq>,<dma>,<dma2>
2495 See header of drivers/scsi/wd33c93.c.
2498 See header of drivers/scsi/wd7000.c.
2501 See Documentation/watchdog/wdt.txt.
2503 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2504 xd_geo= See header of drivers/block/xd.c.
2506 xirc2ps_cs= [NET,PCMCIA]
2508 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2510 norandmaps Don't use address space randomization. Equivalent to
2511 echo 0 > /proc/sys/kernel/randomize_va_space
2513 ______________________________________________________________________
2517 Add documentation for ALSA options.
2518 Add more DRM drivers.
projects / linux-2.6 / blob