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/i386/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 }
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.
262 { off | try_unsupported }
263 off: disable AGP support
264 try_unsupported: try to drive unsupported chipsets
265 (may crash computer or cause data corruption)
267 enable_timer_pin_1 [i386,x86-64]
268 Enable PIN 1 of APIC timer
269 Can be useful to work around chipset bugs
270 (in particular on some ATI chipsets).
271 The kernel tries to set a reasonable default.
273 disable_timer_pin_1 [i386,x86-64]
274 Disable PIN 1 of APIC timer
275 Can be useful to work around chipset bugs.
278 Format: <io>,<irq>,<dma>,<dma2>,<type>
281 See header of drivers/scsi/advansys.c.
283 advwdt= [HW,WDT] Advantech WDT
284 Format: <iostart>,<iostop>
286 aedsp16= [HW,OSS] Audio Excel DSP 16
287 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
288 See also header of sound/oss/aedsp16.c.
291 See Documentation/scsi/aha152x.txt.
294 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
297 See Documentation/scsi/aic7xxx.txt.
300 See Documentation/scsi/aic79xx.txt.
302 amd_iommu= [HW,X86-84]
303 Pass parameters to the AMD IOMMU driver in the system.
305 isolate - enable device isolation (each device, as far
306 as possible, will get its own protection
308 share - put every device behind one IOMMU into the
309 same protection domain
310 fullflush - enable flushing of IO/TLB entries when
311 they are unmapped. Otherwise they are
312 flushed before they will be reused, which
315 amd_iommu_size= [HW,X86-64]
316 Define the size of the aperture for the AMD IOMMU
317 driver. Possible values are:
318 '32M', '64M' (default), '128M', '256M', '512M', '1G'
320 amijoy.map= [HW,JOY] Amiga joystick support
321 Map of devices attached to JOY0DAT and JOY1DAT
323 See also Documentation/kernel/input/joystick.txt
325 analog.map= [HW,JOY] Analog joystick and gamepad support
326 Specifies type or capabilities of an analog joystick
327 connected to one of 16 gameports
328 Format: <type1>,<type2>,..<type16>
331 Power management functions (SPARCstation-4/5 + deriv.)
333 Disable APC CPU standby support. SPARCstation-Fox does
334 not play well with APC CPU idle - disable it if you have
335 APC and your system crashes randomly.
337 apic= [APIC,i386] Advanced Programmable Interrupt Controller
338 Change the output verbosity whilst booting
339 Format: { quiet (default) | verbose | debug }
340 Change the amount of debugging information output
341 when initialising the APIC and IO-APIC components.
343 apm= [APM] Advanced Power Management
344 See header of arch/x86/kernel/apm_32.c.
346 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
347 Format: <io>,<irq>,<nodeID>
351 atarimouse= [HW,MOUSE] Atari Mouse
353 atascsi= [HW,SCSI] Atari SCSI
355 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
356 EzKey and similar keyboards
358 atkbd.reset= [HW] Reset keyboard during initialization
360 atkbd.set= [HW] Select keyboard code set
361 Format: <int> (2 = AT (default), 3 = PS/2)
363 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
366 atkbd.softraw= [HW] Choose between synthetic and real raw mode
367 Format: <bool> (0 = real, 1 = synthetic (default))
369 atkbd.softrepeat= [HW]
370 Use software keyboard repeat
374 baycom_epp= [HW,AX25]
377 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
379 See header of drivers/net/hamradio/baycom_par.c.
381 baycom_ser_fdx= [HW,AX25]
382 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
383 Format: <io>,<irq>,<mode>[,<baud>]
384 See header of drivers/net/hamradio/baycom_ser_fdx.c.
386 baycom_ser_hdx= [HW,AX25]
387 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
388 Format: <io>,<irq>,<mode>
389 See header of drivers/net/hamradio/baycom_ser_hdx.c.
391 boot_delay= Milliseconds to delay each printk during boot.
392 Values larger than 10 seconds (10000) are changed to
396 bootmem_debug [KNL] Enable bootmem allocator debug messages.
398 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
399 bttv.radio= Most important insmod options are available as
401 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
402 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
405 See drivers/scsi/BusLogic.c, comment before function
406 BusLogic_ParseDriverOptions().
408 c101= [NET] Moxa C101 synchronous serial card
410 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
411 Sometimes CPU hardware bugs make them report the cache
412 size incorrectly. The kernel will attempt work arounds
413 to fix known problems, but for some CPUs it is not
414 possible to determine what the correct size should be.
415 This option provides an override for these situations.
417 security= [SECURITY] Choose a security module to enable at boot.
418 If this boot parameter is not specified, only the first
419 security module asking for security registration will be
420 loaded. An invalid security module name will be treated
421 as if no module has been chosen.
424 [SECURITY] Disable capabilities. This would normally
425 be used only if an alternative security model is to be
426 configured. Potentially dangerous and should only be
427 used if you are entirely sure of the consequences.
429 ccw_timeout_log [S390]
430 See Documentation/s390/CommonIO for details.
432 cgroup_disable= [KNL] Disable a particular controller
433 Format: {name of the controller(s) to disable}
434 {Currently supported controllers - "memory"}
436 checkreqprot [SELINUX] Set initial checkreqprot flag value.
437 Format: { "0" | "1" }
438 See security/selinux/Kconfig help text.
439 0 -- check protection applied by kernel (includes
440 any implied execute protection).
441 1 -- check protection requested by application.
442 Default value is set via a kernel config option.
443 Value can be changed at runtime via
444 /selinux/checkreqprot.
447 See Documentation/s390/CommonIO for details.
449 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
451 Forces specified clocksource (if available) to be used
452 when calculating gettimeofday(). If specified
453 clocksource is not available, it defaults to PIT.
454 Format: { pit | tsc | cyclone | pmtmr }
456 clocksource= [GENERIC_TIME] Override the default clocksource
458 Override the default clocksource and use the clocksource
459 with the name specified.
460 Some clocksource names to choose from, depending on
462 [all] jiffies (this is the base, fallback clocksource)
464 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
465 pxa_timer,timer3,32k_counter,timer0_1
467 [X86-32] pit,hpet,tsc,vmi-timer;
468 scx200_hrt on Geode; cyclone on IBM x440
476 clearcpuid=BITNUM [X86]
477 Disable CPUID feature X for the kernel. See
478 arch/x86/include/asm/cpufeature.h for the valid bit
479 numbers. Note the Linux specific bits are not necessarily
480 stable over kernel options, but the vendor specific
482 Also note that user programs calling CPUID directly
483 or using the feature without checking anything
484 will still see it. This just prevents it from
485 being used by the kernel or shown in /proc/cpuinfo.
486 Also note the kernel might malfunction if you disable
489 code_bytes [IA32/X86_64] How many bytes of object code to print
494 hpet= [X86-32,HPET] option to control HPET usage
495 Format: { enable (default) | disable | force }
496 disable: disable HPET and use PIT instead
497 force: allow force enabled of undocumented chips (ICH4,
500 com20020= [HW,NET] ARCnet - COM20020 chipset
502 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
504 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
508 ARCnet - COM90xx chipset (memory-mapped buffers)
509 Format: <io>[,<irq>[,<memstart>]]
511 condev= [HW,S390] console device
514 console= [KNL] Output console device and options.
516 tty<n> Use the virtual console device <n>.
520 Use the specified serial port. The options are of
521 the form "bbbbpnf", where "bbbb" is the baud rate,
522 "p" is parity ("n", "o", or "e"), "n" is number of
523 bits, and "f" is flow control ("r" for RTS or
524 omit it). Default is "9600n8".
526 See Documentation/serial-console.txt for more
528 Documentation/networking/netconsole.txt for an
531 uart[8250],io,<addr>[,options]
532 uart[8250],mmio,<addr>[,options]
533 Start an early, polled-mode console on the 8250/16550
534 UART at the specified I/O port or MMIO address,
535 switching to the matching ttyS device later. The
536 options are the same as for ttyS, above.
538 If the device connected to the port is not a TTY but a braille
539 device, prepend "brl," before the device type, for instance
541 For now, only VisioBraille is supported.
543 earlycon= [KNL] Output early console device and options.
544 uart[8250],io,<addr>[,options]
545 uart[8250],mmio,<addr>[,options]
546 Start an early, polled-mode console on the 8250/16550
547 UART at the specified I/O port or MMIO address.
548 The options are the same as for ttyS, above.
551 [HW] Never suspend the console
552 Disable suspending of consoles during suspend and
553 hibernate operations. Once disabled, debugging
554 messages can reach various consoles while the rest
555 of the system is being put to sleep (ie, while
556 debugging driver suspend/resume hooks). This may
557 not work reliably with all consoles, but is known
558 to work with serial and VGA consoles.
561 [KNL] Change the default value for
562 /proc/<pid>/coredump_filter.
563 See also Documentation/filesystems/proc.txt.
565 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
567 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
569 crashkernel=nn[KMG]@ss[KMG]
570 [KNL] Reserve a chunk of physical memory to
571 hold a kernel to switch to with kexec on panic.
573 crashkernel=range1:size1[,range2:size2,...][@offset]
574 [KNL] Same as above, but depends on the memory
575 in the running system. The syntax of range is
576 start-[end] where start and end are both
577 a memory unit (amount[KMG]). See also
578 Documentation/kdump/kdump.txt for a example.
581 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
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.
736 Format: <spdif>,[<nomix>,[<amplifier>]]
737 See also header of sound/oss/es1371.c.
739 ether= [HW,NET] Ethernet cards parameters
740 This option is obsoleted by the "netdev=" option, which
741 has equivalent usage. See its documentation for details.
743 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
748 fail_make_request=[KNL]
749 General fault injection mechanism.
750 Format: <interval>,<probability>,<space>,<times>
751 See also /Documentation/fault-injection/.
754 See header of drivers/scsi/fd_mcs.c.
757 See header of drivers/scsi/fdomain.c.
760 See Documentation/blockdev/floppy.txt.
762 force_pal_cache_flush
763 [IA-64] Avoid check_sal_cache_flush which may hang on
764 buggy SAL_CACHE_FLUSH implementations. Using this
765 parameter will force ia64_sal_cache_flush to call
766 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
769 [ftrace] will set and start the specified tracer
770 as early as possible in order to facilitate early
774 [ftrace] will dump the trace buffers on oops.
777 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
778 support via parallel port (up to 5 devices per port)
779 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
780 See also Documentation/input/joystick-parport.txt
784 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
789 See header of drivers/scsi/gdth.c.
791 gpt [EFI] Forces disk with valid GPT signature but
792 invalid Protective MBR to be treated as GPT.
796 hashdist= [KNL,NUMA] Large hashes allocated during boot
797 are distributed across NUMA nodes. Defaults on
798 for IA-64, off otherwise.
799 Format: 0 | 1 (for off | on)
801 hcl= [IA-64] SGI's Hardware Graph compatibility layer
803 hd= [EIDE] (E)IDE hard drive subsystem geometry
804 Format: <cyl>,<head>,<sect>
806 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
807 size of <nn>. This works even on boxes that have no
808 highmem otherwise. This also works to reduce highmem
809 size on bigger boxes.
811 highres= [KNL] Enable/disable high resolution timer mode.
812 Valid parameters: "on", "off"
816 See Documentation/isdn/README.HiSax.
818 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
819 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
820 On x86-64 and powerpc, this option can be specified
821 multiple times interleaved with hugepages= to reserve
822 huge pages of different sizes. Valid pages sizes on
823 x86-64 are 2M (when the CPU supports "pse") and 1G
824 (when the CPU supports the "pdpe1gb" cpuinfo flag)
825 Note that 1GB pages can only be allocated at boot time
826 using hugepages= and not freed afterwards.
828 [same as hugepagesz=] The size of the default
829 HugeTLB page size. This is the size represented by
830 the legacy /proc/ hugepages APIs, used for SHM, and
831 default size when mounting hugetlbfs filesystems.
832 Defaults to the default architecture's huge page size
837 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
838 terminal devices. Valid values: 0..8
840 i8042.debug [HW] Toggle i8042 debug mode
841 i8042.direct [HW] Put keyboard port into non-translated mode
842 i8042.dumbkbd [HW] Pretend that controller can only read data from
843 keyboard and cannot control its state
844 (Don't attempt to blink the leds)
845 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
846 i8042.nokbd [HW] Don't check/create keyboard port
847 i8042.noloop [HW] Disable the AUX Loopback command while probing
849 i8042.nomux [HW] Don't check presence of an active multiplexing
851 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
854 [HW] Frequency with which keyboard LEDs should blink
855 when kernel panics (default is 0.5 sec)
856 i8042.reset [HW] Reset the controller during init and cleanup
857 i8042.unlock [HW] Unlock (ignore) the keylock
861 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
862 indicates that the driver is running on unsupported
864 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
865 does not match list of supported models.
867 [HW] Report power status in /proc/i8k
868 (disabled by default)
869 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
872 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
873 See Documentation/mca.txt.
876 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
878 ide= [HW] (E)IDE subsystem
879 Format: ide=nodma or ide=doubler
880 See Documentation/ide/ide.txt.
882 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
883 See Documentation/ide/ide.txt.
886 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
887 Poll forces a polling idle loop that can slightly
888 improve the performance of waking up a idle CPU, but
889 will use a lot of power and make the system run hot.
891 idle=mwait: On systems which support MONITOR/MWAIT but
892 the kernel chose to not use it because it doesn't save
893 as much power as a normal idle loop, use the
894 MONITOR/MWAIT idle loop anyways. Performance should be
895 the same as idle=poll.
896 idle=halt: Halt is forced to be used for CPU idle.
897 In such case C2/C3 won't be used again.
898 idle=nomwait: Disable mwait for CPU C-states
900 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
901 Claim all unknown PCI IDE storage controllers.
903 ignore_loglevel [KNL]
904 Ignore loglevel setting - this will print /all/
905 kernel messages to the console. Useful for debugging.
908 Set number of hash buckets for inode cache.
911 See header of drivers/scsi/in2000.c.
915 Run specified binary instead of /sbin/init as init
918 initcall_debug [KNL] Trace initcalls as they are executed. Useful
919 for working out where the kernel is dying during
922 initrd= [BOOT] Specify the location of the initial ramdisk
924 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
929 iomem= Disable strict checking of access to MMIO memory
930 strict regions from userspace.
946 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
948 Disable intel iommu driver.
949 igfx_off [Default Off]
950 By default, gfx is mapped as normal device. If a gfx
951 device has a dedicated DMAR unit, the DMAR unit is
952 bypassed by not enabling DMAR with this option. In
953 this case, gfx device will use physical address for
956 With this option iommu will not optimize to look
957 for io virtual address below 32 bit forcing dual
958 address cycle on pci bus for cards supporting greater
959 than 32 bit addressing. The default is to look
960 for translation below 32 bit and if not available
961 then look in the higher range.
963 With this option on every unmap_single operation will
964 result in a hardware IOTLB flush operation as opposed
965 to batching them for performance.
967 io_delay= [X86-32,X86-64] I/O delay method
969 Standard port 0x80 based delay
971 Alternate port 0xed based delay (needed on some systems)
973 Simple two microseconds delay
977 io7= [HW] IO7 for Marvel based alpha systems
978 See comment before marvel_specify_io7 in
979 arch/alpha/kernel/core_marvel.c.
982 See Documentation/filesystems/nfsroot.txt.
984 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
985 See comment before ip2_setup() in
986 drivers/char/ip2/ip2base.c.
988 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
989 See header of drivers/scsi/ips.c.
991 ports= [IP_VS_FTP] IPVS ftp helper module
993 Up to 8 (IP_VS_APP_MAX_PORTS) ports
995 Format: <port>,<port>....
998 When an interrupt is not handled search all handlers
999 for it. Intended to get systems with badly broken
1003 When an interrupt is not handled search all handlers
1004 for it. Also check all handlers each timer
1005 interrupt. Intended to get systems with badly broken
1009 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1011 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1013 <cpu number>,...,<cpu number>
1015 <cpu number>-<cpu number>
1016 (must be a positive range in ascending order)
1018 <cpu number>,...,<cpu number>-<cpu number>
1020 This option can be used to specify one or more CPUs
1021 to isolate from the general SMP balancing and scheduling
1022 algorithms. You can move a process onto or off an
1023 "isolated" CPU via the CPU affinity syscalls or cpuset.
1024 <cpu number> begins at 0 and the maximum value is
1025 "number of CPUs in system - 1".
1027 This option is the preferred way to isolate CPUs. The
1028 alternative -- manually setting the CPU mask of all
1029 tasks in the system -- can cause problems and
1030 suboptimal load balancer performance.
1034 js= [HW,JOY] Analog joystick
1035 See Documentation/input/joystick.txt.
1037 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1038 specifies the amount of memory usable by the kernel
1039 for non-movable allocations. The requested amount is
1040 spread evenly throughout all nodes in the system. The
1041 remaining memory in each node is used for Movable
1042 pages. In the event, a node is too small to have both
1043 kernelcore and Movable pages, kernelcore pages will
1044 take priority and other nodes will have a larger number
1045 of kernelcore pages. The Movable zone is used for the
1046 allocation of pages that may be reclaimed or moved
1047 by the page migration subsystem. This means that
1048 HugeTLB pages may not be allocated from this zone.
1049 Note that allocations like PTEs-from-HighMem still
1050 use the HighMem zone if it exists, and the Normal
1051 zone if it does not.
1053 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1054 is similar to kernelcore except it specifies the
1055 amount of memory used for migratable allocations.
1056 If both kernelcore and movablecore is specified,
1057 then kernelcore will be at *least* the specified
1058 value but may be more. If movablecore on its own
1059 is specified, the administrator must be careful
1060 that the amount of memory usable for all allocations
1065 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1068 kgdboc= [HW] kgdb over consoles.
1069 Requires a tty driver that supports console polling.
1070 (only serial suported for now)
1071 Format: <serial_device>[,baud]
1073 kmac= [MIPS] korina ethernet MAC address.
1074 Configure the RouterBoard 532 series on-chip
1075 Ethernet adapter MAC address.
1081 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1084 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1087 libata.dma= [LIBATA] DMA control
1088 libata.dma=0 Disable all PATA and SATA DMA
1089 libata.dma=1 PATA and SATA Disk DMA only
1090 libata.dma=2 ATAPI (CDROM) DMA only
1091 libata.dma=4 Compact Flash DMA only
1092 Combinations also work, so libata.dma=3 enables DMA
1093 for disks and CDROMs, but not CFs.
1095 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1099 libata.force= [LIBATA] Force configurations. The format is comma
1100 separated list of "[ID:]VAL" where ID is
1101 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1102 matching port, link or device. Basically, it matches
1103 the ATA ID string printed on console by libata. If
1104 the whole ID part is omitted, the last PORT and DEVICE
1105 values are used. If ID hasn't been specified yet, the
1106 configuration applies to all ports, links and devices.
1108 If only DEVICE is omitted, the parameter applies to
1109 the port and all links and devices behind it. DEVICE
1110 number of 0 either selects the first device or the
1111 first fan-out link behind PMP device. It does not
1112 select the host link. DEVICE number of 15 selects the
1113 host link and device attached to it.
1115 The VAL specifies the configuration to force. As long
1116 as there's no ambiguity shortcut notation is allowed.
1117 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1118 The following configurations can be forced.
1120 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1121 Any ID with matching PORT is used.
1123 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1125 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1126 udma[/][16,25,33,44,66,100,133] notation is also
1129 * [no]ncq: Turn on or off NCQ.
1131 * nohrst, nosrst, norst: suppress hard, soft
1134 If there are multiple matching configurations changing
1135 the same attribute, the last one is used.
1137 lmb=debug [KNL] Enable lmb debug messages.
1139 load_ramdisk= [RAM] List of ramdisks to load from floppy
1140 See Documentation/blockdev/ramdisk.txt.
1142 lockd.nlm_grace_period=P [NFS] Assign grace period.
1145 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1148 lockd.nlm_timeout=T [NFS] Assign timeout value.
1151 lockd.nlm_udpport=M [NFS] Assign UDP port.
1154 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1157 loglevel= All Kernel Messages with a loglevel smaller than the
1158 console loglevel will be printed to the console. It can
1159 also be changed with klogd or other programs. The
1160 loglevels are defined as follows:
1162 0 (KERN_EMERG) system is unusable
1163 1 (KERN_ALERT) action must be taken immediately
1164 2 (KERN_CRIT) critical conditions
1165 3 (KERN_ERR) error conditions
1166 4 (KERN_WARNING) warning conditions
1167 5 (KERN_NOTICE) normal but significant condition
1168 6 (KERN_INFO) informational
1169 7 (KERN_DEBUG) debug-level messages
1171 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1172 Format: { n | nk | nM }
1173 n must be a power of two. The default size
1174 is set in the kernel config file.
1176 logo.nologo [FB] Disables display of the built-in Linux logo.
1177 This may be used to provide more screen space for
1178 kernel log messages and is useful when debugging
1179 kernel boot problems.
1181 lp=0 [LP] Specify parallel ports to use, e.g,
1182 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1183 lp=reset first parallel port). 'lp=0' disables the
1184 lp=auto printer driver. 'lp=reset' (which can be
1185 specified in addition to the ports) causes
1186 attached printers to be reset. Using
1187 lp=port1,port2,... specifies the parallel ports
1188 to associate lp devices with, starting with
1189 lp0. A port specification may be 'none' to skip
1190 that lp device, or a parport name such as
1191 'parport0'. Specifying 'lp=auto' instead of a
1192 port specification list means that device IDs
1193 from each port should be examined, to see if
1194 an IEEE 1284-compliant printer is attached; if
1195 so, the driver will manage that printer.
1196 See also header of drivers/char/lp.c.
1199 Sets loops_per_jiffy to given constant, thus avoiding
1200 time-consuming boot-time autodetection (up to 250 ms per
1201 CPU). 0 enables autodetection (default). To determine
1202 the correct value for your kernel, boot with normal
1203 autodetection and see what value is printed. Note that
1204 on SMP systems the preset will be applied to all CPUs,
1205 which is likely to cause problems if your CPUs need
1206 significantly divergent settings. An incorrect value
1207 will cause delays in the kernel to be wrong, leading to
1208 unpredictable I/O errors and other breakage. Although
1209 unlikely, in the extreme case this might damage your
1213 Format: <io>,<irq>,<dma>
1215 mac5380= [HW,SCSI] Format:
1216 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1218 machvec= [IA64] Force the use of a particular machine-vector
1219 (machvec) in a generic kernel.
1220 Example: machvec=hpzx1_swiotlb
1222 max_loop= [LOOP] Maximum number of loopback devices that can
1226 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1227 should make use of. maxcpus=n : n >= 0 limits the
1228 kernel to using 'n' processors. n=0 is a special case,
1229 it is equivalent to "nosmp", which also disables
1232 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1233 or equal to this physical address is ignored.
1235 max_luns= [SCSI] Maximum number of LUNs to probe.
1236 Should be between 1 and 2^32-1.
1239 [SCSI] Maximum number of LUNs received.
1240 Should be between 1 and 16384.
1244 mce [X86-32] Machine Check Exception
1246 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1248 md= [HW] RAID subsystems devices and level
1249 See Documentation/md.txt.
1252 Format: <first>,<last>
1253 Specifies range of consoles to be captured by the MDA.
1255 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1256 Amount of memory to be used when the kernel is not able
1257 to see the whole system memory or for test.
1258 [X86-32] Use together with memmap= to avoid physical
1259 address space collisions. Without memmap= PCI devices
1260 could be placed at addresses belonging to unused RAM.
1262 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1266 [KNL,SH] Allow user to override the default size for
1267 per-device physically contiguous DMA buffers.
1269 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1270 E820 memory map, as specified by the user.
1271 Such memmap=exactmap lines can be constructed based on
1272 BIOS output or other requirements. See the memmap=nn@ss
1275 memmap=nn[KMG]@ss[KMG]
1276 [KNL] Force usage of a specific region of memory
1277 Region of memory to be used, from ss to ss+nn.
1279 memmap=nn[KMG]#ss[KMG]
1280 [KNL,ACPI] Mark specific memory as ACPI data.
1281 Region of memory to be used, from ss to ss+nn.
1283 memmap=nn[KMG]$ss[KMG]
1284 [KNL,ACPI] Mark specific memory as reserved.
1285 Region of memory to be used, from ss to ss+nn.
1286 Example: Exclude memory from 0x18690000-0x1869ffff
1287 memmap=64K$0x18690000
1289 memmap=0x10000$0x18690000
1291 memory_corruption_check=0/1 [X86]
1292 Some BIOSes seem to corrupt the first 64k of
1293 memory when doing things like suspend/resume.
1294 Setting this option will scan the memory
1295 looking for corruption. Enabling this will
1296 both detect corruption and prevent the kernel
1297 from using the memory being corrupted.
1298 However, its intended as a diagnostic tool; if
1299 repeatable BIOS-originated corruption always
1300 affects the same memory, you can use memmap=
1301 to prevent the kernel from using that memory.
1303 memory_corruption_check_size=size [X86]
1304 By default it checks for corruption in the low
1305 64k, making this memory unavailable for normal
1306 use. Use this parameter to scan for
1307 corruption in more or less memory.
1309 memory_corruption_check_period=seconds [X86]
1310 By default it checks for corruption every 60
1311 seconds. Use this parameter to check at some
1312 other rate. 0 disables periodic checking.
1314 memtest= [KNL,X86] Enable memtest
1316 range: 0,4 : pattern number
1317 default : 0 <disable>
1319 meye.*= [HW] Set MotionEye Camera parameters
1320 See Documentation/video4linux/meye.txt.
1322 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1323 Multi-Function General Purpose Timers on AMD Geode
1326 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1327 the BIOS has incorrectly applied a workaround. TinyBIOS
1328 version 0.98 is known to be affected, 0.99 fixes the
1329 problem by letting the user disable the workaround.
1333 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1334 physical address is ignored.
1337 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1338 parameter allows control of the logging verbosity for
1339 the additional memory initialisation checks. A value
1340 of 0 disables mminit logging and a level of 4 will
1341 log everything. Information is printed at KERN_DEBUG
1342 so loglevel=8 may also need to be specified.
1345 [MOUSE] Maximum time between finger touching and
1346 leaving touchpad surface for touch to be considered
1347 a tap and be reported as a left button click (for
1348 touchpads working in absolute mode only).
1350 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1351 reporting absolute coordinates, such as tablets
1352 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1353 reporting absolute coordinates, such as tablets
1358 MTD_Partition= [MTD]
1359 Format: <name>,<region-number>,<size>,<offset>
1361 MTD_Region= [MTD] Format:
1362 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1365 See drivers/mtd/cmdlinepart.c.
1368 ARM/S3C2412 JIVE boot control
1370 See arch/arm/mach-s3c2412/mach-jive.c
1372 mtouchusb.raw_coordinates=
1373 [HW] Make the MicroTouch USB driver use raw coordinates
1374 ('y', default) or cooked coordinates ('n')
1376 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1379 See header of drivers/scsi/NCR_D700.c.
1383 ncr53c400= [HW,SCSI]
1385 ncr53c400a= [HW,SCSI]
1387 ncr53c406a= [HW,SCSI]
1389 ncr53c8xx= [HW,SCSI]
1391 netdev= [NET] Network devices parameters
1392 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1393 Note that mem_start is often overloaded to mean
1394 something different and driver-specific.
1395 This usage is only documented in each driver source
1399 [NETFILTER] Enable connection tracking flow accounting
1400 0 to disable accounting
1401 1 to enable accounting
1402 Default value depends on CONFIG_NF_CT_ACCT that is
1403 going to be removed in 2.6.29.
1406 See Documentation/filesystems/nfsroot.txt.
1408 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1409 See Documentation/filesystems/nfsroot.txt.
1411 nfs.callback_tcpport=
1412 [NFS] set the TCP port on which the NFSv4 callback
1413 channel should listen.
1415 nfs.idmap_cache_timeout=
1416 [NFS] set the maximum lifetime for idmapper cache
1420 [NFS] enable 64-bit inode numbers.
1421 If zero, the NFS client will fake up a 32-bit inode
1422 number for the readdir() and stat() syscalls instead
1423 of returning the full 64-bit number.
1424 The default is to return 64-bit inode numbers.
1426 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1427 when a NMI is triggered.
1428 Format: [state][,regs][,debounce][,die]
1430 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1431 Format: [panic,][num]
1433 0 - turn nmi_watchdog off
1434 1 - use the IO-APIC timer for the NMI watchdog
1435 2 - use the local APIC for the NMI watchdog using
1436 a performance counter. Note: This will use one performance
1437 counter and the local APIC's performance vector.
1438 When panic is specified panic when an NMI watchdog timeout occurs.
1439 This is useful when you use a panic=... timeout and need the box
1441 Instead of 1 and 2 it is possible to use the following
1442 symbolic names: lapic and ioapic
1443 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1445 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1446 emulation library even if a 387 maths coprocessor
1449 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1450 caches in the slab allocator. Saves per-node memory,
1451 but will impact performance.
1455 noapic [SMP,APIC] Tells the kernel to not make use of any
1456 IOAPICs that may be present in the system.
1458 nobats [PPC] Do not use BATs for mapping kernel lowmem
1459 on "Classic" PPC cores.
1463 nodelayacct [KNL] Disable per-task delay accounting
1465 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1467 nodsp [SH] Disable hardware DSP at boot time.
1469 noefi [X86-32,X86-64] Disable EFI runtime services support.
1473 noexec [X86-32,X86-64]
1474 On X86-32 available only on PAE configured kernels.
1475 noexec=on: enable non-executable mappings (default)
1476 noexec=off: disable non-executable mappings
1479 This affects only 32-bit executables.
1480 noexec32=on: enable non-executable mappings (default)
1481 read doesn't imply executable mappings
1482 noexec32=off: disable non-executable mappings
1483 read implies executable mappings
1485 nofpu [SH] Disable hardware FPU at boot time.
1487 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1488 register save and restore. The kernel will only save
1489 legacy floating-point registers on task switch.
1491 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1495 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1496 instruction doesn't work correctly and not to
1499 no_file_caps Tells the kernel not to honor file capabilities. The
1500 only way then for a file to be executed with privilege
1501 is to be setuid root or executed by root.
1503 nohalt [IA-64] Tells the kernel not to use the power saving
1504 function PAL_HALT_LIGHT when idle. This increases
1505 power-consumption. On the positive side, it reduces
1506 interrupt wake-up latency, which may improve performance
1507 in certain environments such as networked servers or
1510 nohz= [KNL] Boottime enable/disable dynamic ticks
1511 Valid arguments: on, off
1514 noirqdebug [X86-32] Disables the code which attempts to detect and
1515 disable unhandled interrupt sources.
1517 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1518 broken timer IRQ sources.
1520 noisapnp [ISAPNP] Disables ISA PnP code.
1522 noinitrd [RAM] Tells the kernel not to load any configured
1527 nojitter [IA64] Disables jitter checking for ITC timers.
1529 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1531 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1533 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1535 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1536 default x2apic cluster mode on platforms
1539 noltlbs [PPC] Do not use large page/tlb entries for kernel
1540 lowmem mapping on PPC40x.
1542 nomca [IA-64] Disable machine check abort handling
1544 nomce [X86-32] Machine Check Exception
1546 nomfgpt [X86-32] Disable Multi-Function General Purpose
1547 Timer usage (for AMD Geode machines).
1549 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1551 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1552 with UP alternatives
1554 noresidual [PPC] Don't use residual data on PReP machines.
1556 noresume [SWSUSP] Disables resume and restores original swap
1559 no-scroll [VGA] Disables scrollback.
1560 This is required for the Braillex ib80-piezo Braille
1561 reader made by F.H. Papenmeier (Germany).
1565 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1567 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1568 and disable the IO APIC. legacy for "maxcpus=0".
1570 nosoftlockup [KNL] Disable the soft-lockup detector.
1572 noswapaccount [KNL] Disable accounting of swap in memory resource
1573 controller. (See Documentation/controllers/memory.txt)
1575 nosync [HW,M68K] Disables sync negotiation for all devices.
1577 notsc [BUGS=X86-32] Disable Time Stamp Counter
1579 nousb [USB] Disable the USB subsystem
1583 nptcg= [IA64] Override max number of concurrent global TLB
1584 purges which is reported from either PAL_VM_SUMMARY or
1587 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1588 one of ['zone', 'node', 'default'] can be specified
1589 This can be set from sysctl after boot.
1590 See Documentation/sysctl/vm.txt for details.
1592 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1594 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1595 See Documentation/debugging-via-ohci1394.txt for more
1598 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1599 Rather than timing out after 20 ms if an EC
1600 command is not properly ACKed, override the length
1601 of the timeout. We have interrupts disabled while
1602 waiting for the ACK, so if this is set too high
1603 interrupts *may* be lost!
1608 oprofile.timer= [HW]
1609 Use timer interrupt instead of performance counters
1611 osst= [HW,SCSI] SCSI Tape Driver
1612 Format: <buffer_size>,<write_threshold>
1613 See also Documentation/scsi/st.txt.
1615 panic= [KNL] Kernel behaviour on panic
1618 parkbd.port= [HW] Parallel port number the keyboard adapter is
1619 connected to, default is 0.
1621 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1622 0 for XT, 1 for AT (default is AT).
1625 parport= [HW,PPT] Specify parallel ports. 0 disables.
1626 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1627 Use 'auto' to force the driver to use any
1628 IRQ/DMA settings detected (the default is to
1629 ignore detected IRQ/DMA settings because of
1630 possible conflicts). You can specify the base
1631 address, IRQ, and DMA settings; IRQ and DMA
1632 should be numbers, or 'auto' (for using detected
1633 settings on that particular port), or 'nofifo'
1634 (to avoid using a FIFO even if it is detected).
1635 Parallel ports are assigned in the order they
1636 are specified on the command line, starting
1639 parport_init_mode= [HW,PPT]
1640 Configure VIA parallel port to operate in
1641 a specific mode. This is necessary on Pegasos
1642 computer where firmware has no options for setting
1643 up parallel port mode and sets it to spp.
1644 Currently this function knows 686a and 8231 chips.
1645 Format: [spp|ps2|epp|ecp|ecpepp]
1647 pas2= [HW,OSS] Format:
1648 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1651 See header of drivers/scsi/pas16.c.
1654 Halt all CPUs after the first oops has been printed for
1655 the specified number of seconds. This is to be used if
1656 your oopses keep scrolling off the screen.
1661 See header of drivers/block/paride/pcd.c.
1662 See also Documentation/blockdev/paride.txt.
1664 pci=option[,option...] [PCI] various PCI subsystem options:
1665 off [X86] don't probe for the PCI bus
1666 bios [X86-32] force use of PCI BIOS, don't access
1667 the hardware directly. Use this if your machine
1668 has a non-standard PCI host bridge.
1669 nobios [X86-32] disallow use of PCI BIOS, only direct
1670 hardware access methods are allowed. Use this
1671 if you experience crashes upon bootup and you
1672 suspect they are caused by the BIOS.
1673 conf1 [X86] Force use of PCI Configuration
1675 conf2 [X86] Force use of PCI Configuration
1677 noaer [PCIE] If the PCIEAER kernel config parameter is
1678 enabled, this kernel boot option can be used to
1679 disable the use of PCIE advanced error reporting.
1680 nodomains [PCI] Disable support for multiple PCI
1681 root domains (aka PCI segments, in ACPI-speak).
1682 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1684 nomsi [MSI] If the PCI_MSI kernel config parameter is
1685 enabled, this kernel boot option can be used to
1686 disable the use of MSI interrupts system-wide.
1687 noioapicquirk [APIC] Disable all boot interrupt quirks.
1688 Safety option to keep boot IRQs enabled. This
1689 should never be necessary.
1690 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1691 primary IO-APIC for bridges that cannot disable
1692 boot IRQs. This fixes a source of spurious IRQs
1693 when the system masks IRQs.
1694 noioapicreroute [APIC] Disable workaround that uses the
1695 boot IRQ equivalent of an IRQ that connects to
1696 a chipset where boot IRQs cannot be disabled.
1697 The opposite of ioapicreroute.
1698 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1699 routing table. These calls are known to be buggy
1700 on several machines and they hang the machine
1701 when used, but on other computers it's the only
1702 way to get the interrupt routing table. Try
1703 this option if the kernel is unable to allocate
1704 IRQs or discover secondary PCI buses on your
1706 rom [X86] Assign address space to expansion ROMs.
1707 Use with caution as certain devices share
1708 address decoders between ROMs and other
1710 norom [X86] Do not assign address space to
1711 expansion ROMs that do not already have
1712 BIOS assigned address ranges.
1713 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1714 assigned automatically to PCI devices. You can
1715 make the kernel exclude IRQs of your ISA cards
1717 pirqaddr=0xAAAAA [X86] Specify the physical address
1718 of the PIRQ table (normally generated
1719 by the BIOS) if it is outside the
1720 F0000h-100000h range.
1721 lastbus=N [X86] Scan all buses thru bus #N. Can be
1722 useful if the kernel is unable to find your
1723 secondary buses and you want to tell it
1724 explicitly which ones they are.
1725 assign-busses [X86] Always assign all PCI bus
1726 numbers ourselves, overriding
1727 whatever the firmware may have done.
1728 usepirqmask [X86] Honor the possible IRQ mask stored
1729 in the BIOS $PIR table. This is needed on
1730 some systems with broken BIOSes, notably
1731 some HP Pavilion N5400 and Omnibook XE3
1732 notebooks. This will have no effect if ACPI
1733 IRQ routing is enabled.
1734 noacpi [X86] Do not use ACPI for IRQ routing
1735 or for PCI scanning.
1736 use_crs [X86] Use _CRS for PCI resource
1738 routeirq Do IRQ routing for all PCI devices.
1739 This is normally done in pci_enable_device(),
1740 so this option is a temporary workaround
1741 for broken drivers that don't call it.
1742 skip_isa_align [X86] do not align io start addr, so can
1743 handle more pci cards
1744 firmware [ARM] Do not re-enumerate the bus but instead
1745 just use the configuration from the
1746 bootloader. This is currently used on
1747 IXP2000 systems where the bus has to be
1748 configured a certain way for adjunct CPUs.
1749 noearly [X86] Don't do any early type 1 scanning.
1750 This might help on some broken boards which
1751 machine check when some devices' config space
1752 is read. But various workarounds are disabled
1753 and some IOMMU drivers will not work.
1754 bfsort Sort PCI devices into breadth-first order.
1755 This sorting is done to get a device
1756 order compatible with older (<= 2.4) kernels.
1757 nobfsort Don't sort PCI devices into breadth-first order.
1758 cbiosize=nn[KMG] The fixed amount of bus space which is
1759 reserved for the CardBus bridge's IO window.
1760 The default value is 256 bytes.
1761 cbmemsize=nn[KMG] The fixed amount of bus space which is
1762 reserved for the CardBus bridge's memory
1763 window. The default value is 64 megabytes.
1765 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1768 force Enable ASPM even on devices that claim not to support it.
1769 WARNING: Forcing ASPM on may cause system lockups.
1771 pcmv= [HW,PCMCIA] BadgePAD 4
1774 See Documentation/blockdev/paride.txt.
1776 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1779 See arch/parisc/kernel/pdc_chassis.c
1782 See Documentation/blockdev/paride.txt.
1785 See Documentation/blockdev/paride.txt.
1787 pirq= [SMP,APIC] Manual mp-table setup
1788 See Documentation/x86/i386/IO-APIC.txt.
1790 plip= [PPT,NET] Parallel port network link
1791 Format: { parport<nr> | timid | 0 }
1792 See also Documentation/parport.txt.
1794 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1795 Override pmtimer IOPort with a hex value.
1799 Enable PNP debug messages. This depends on the
1800 CONFIG_PNP_DEBUG_MESSAGES option.
1806 { on | off | curr | res | no-curr | no-res }
1809 [ISAPNP] Exclude IRQs for the autoconfiguration
1812 [ISAPNP] Exclude DMAs for the autoconfiguration
1814 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1815 Ranges are in pairs (I/O port base and size).
1818 [ISAPNP] Exclude memory regions for the
1820 Ranges are in pairs (memory base and size).
1822 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1823 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1824 These can also be switched on/off via
1825 <debugfs>/dynamic_printk/modules
1827 print-fatal-signals=
1828 [KNL] debug: print fatal signals
1829 print-fatal-signals=1: print segfault info to
1833 printk.time= Show timing data prefixed to each printk message line
1834 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1836 profile= [KNL] Enable kernel profiling via /proc/profile
1837 Format: [schedule,]<number>
1838 Param: "schedule" - profile schedule points.
1839 Param: <number> - step/bucket size as a power of 2 for
1840 statistical time based profiling.
1841 Param: "sleep" - profile D-state sleeping (millisecs).
1842 Requires CONFIG_SCHEDSTATS
1843 Param: "kvm" - profile VM exits.
1845 processor.max_cstate= [HW,ACPI]
1846 Limit processor to maximum C-state
1847 max_cstate=9 overrides any DMI blacklist limit.
1849 processor.nocst [HW,ACPI]
1850 Ignore the _CST method to determine C-states,
1851 instead using the legacy FADT method
1853 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1855 See Documentation/blockdev/ramdisk.txt.
1857 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1858 probe for; one of (bare|imps|exps|lifebook|any).
1859 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1861 psmouse.resetafter= [HW,MOUSE]
1862 Try to reset the device after so many bad packets
1865 [HW,MOUSE] Set desired mouse resolution, in dpi.
1866 psmouse.smartscroll=
1867 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1868 0 = disabled, 1 = enabled (default).
1870 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1872 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1875 See Documentation/blockdev/paride.txt.
1878 [KNL] Number of legacy pty's. Overwrites compiled-in
1881 quiet [KNL] Disable most log messages
1886 See Documentation/md.txt.
1888 ramdisk_blocksize= [RAM]
1889 See Documentation/blockdev/ramdisk.txt.
1891 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1892 See Documentation/blockdev/ramdisk.txt.
1894 rcupdate.blimit= [KNL,BOOT]
1895 Set maximum number of finished RCU callbacks to process
1898 rcupdate.qhimark= [KNL,BOOT]
1899 Set threshold of queued
1900 RCU callbacks over which batch limiting is disabled.
1902 rcupdate.qlowmark= [KNL,BOOT]
1903 Set threshold of queued RCU callbacks below which
1904 batch limiting is re-enabled.
1908 Run specified binary instead of /init from the ramdisk,
1909 used for early userspace startup. See initrd.
1911 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1912 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1913 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1916 [KNL, SMP] Set scheduler's default relax_domain_level.
1917 See Documentation/cpusets.txt.
1919 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1921 reservetop= [X86-32]
1923 Reserves a hole at the top of the kernel virtual
1926 reset_devices [KNL] Force drivers to reset the underlying device
1927 during initialization.
1930 Specify the partition device for software suspend
1932 resume_offset= [SWSUSP]
1933 Specify the offset from the beginning of the partition
1934 given by "resume=" at which the swap header is located,
1935 in <PAGE_SIZE> units (needed only for swap files).
1936 See Documentation/power/swsusp-and-swap-files.txt
1938 retain_initrd [RAM] Keep initrd memory after extraction
1940 rhash_entries= [KNL,NET]
1941 Set number of hash buckets for route cache
1943 riscom8= [HW,SERIAL]
1944 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1946 ro [KNL] Mount root device read-only on boot
1948 root= [KNL] Root filesystem
1950 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1951 mount the root filesystem
1953 rootflags= [KNL] Set root filesystem mount option string
1955 rootfstype= [KNL] Set root filesystem type
1957 rootwait [KNL] Wait (indefinitely) for root device to show up.
1958 Useful for devices that are detected asynchronously
1959 (e.g. USB and MMC devices).
1961 root_plug.vendor_id=
1962 [ROOTPLUG] Override the default vendor ID
1964 root_plug.product_id=
1965 [ROOTPLUG] Override the default product ID
1968 [ROOTPLUG] Enable debugging output
1970 rw [KNL] Mount root device read-write on boot
1972 S [KNL] Run init in single mode
1975 See drivers/net/irda/sa1100_ir.c.
1977 sbni= [NET] Granch SBNI12 leased line adapter
1979 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1980 Format: <io>[,<timeout>[,<isapnp>]]
1982 scsi_debug_*= [SCSI]
1983 See drivers/scsi/scsi_debug.c.
1985 scsi_default_dev_flags=
1986 [SCSI] SCSI default device flags
1989 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1990 Format: <vendor>:<model>:<flags>
1991 (flags are integer value)
1993 scsi_logging_level= [SCSI] a bit mask of logging levels
1994 See drivers/scsi/scsi_logging.h for bits. Also
1995 settable via sysctl at dev.scsi.logging_level
1996 (/proc/sys/dev/scsi/logging_level).
1997 There is also a nice 'scsi_logging_level' script in the
1998 S390-tools package, available for download at
1999 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2001 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2002 discovered. async scans them in kernel threads,
2003 allowing boot to proceed. none ignores them, expecting
2004 user space to do the scan.
2006 selinux [SELINUX] Disable or enable SELinux at boot time.
2007 Format: { "0" | "1" }
2008 See security/selinux/Kconfig help text.
2011 Default value is set via kernel config option.
2012 If enabled at boot time, /selinux/disable can be used
2013 later to disable prior to initial policy load.
2015 selinux_compat_net =
2016 [SELINUX] Set initial selinux_compat_net flag value.
2017 Format: { "0" | "1" }
2018 0 -- use new secmark-based packet controls
2019 1 -- use legacy packet controls
2020 Default value is 0 (preferred).
2021 Value can be changed at runtime via
2022 /selinux/compat_net.
2024 serialnumber [BUGS=X86-32]
2027 Maximal number of shapers.
2029 show_msr= [x86] show boot-time MSR settings
2030 Format: { <integer> }
2031 Show boot-time (BIOS-initialized) MSR settings.
2032 The parameter means the number of CPUs to show,
2033 for example 1 means boot CPU only.
2036 See header of drivers/scsi/sim710.c.
2043 slub_debug[=options[,slabs]] [MM, SLUB]
2044 Enabling slub_debug allows one to determine the
2045 culprit if slab objects become corrupted. Enabling
2046 slub_debug can create guard zones around objects and
2047 may poison objects when not in use. Also tracks the
2048 last alloc / free. For more information see
2049 Documentation/vm/slub.txt.
2051 slub_max_order= [MM, SLUB]
2052 Determines the maximum allowed order for slabs.
2053 A high setting may cause OOMs due to memory
2054 fragmentation. For more information see
2055 Documentation/vm/slub.txt.
2057 slub_min_objects= [MM, SLUB]
2058 The minimum number of objects per slab. SLUB will
2059 increase the slab order up to slub_max_order to
2060 generate a sufficiently large slab able to contain
2061 the number of objects indicated. The higher the number
2062 of objects the smaller the overhead of tracking slabs
2063 and the less frequently locks need to be acquired.
2064 For more information see Documentation/vm/slub.txt.
2066 slub_min_order= [MM, SLUB]
2067 Determines the mininum page order for slabs. Must be
2068 lower than slub_max_order.
2069 For more information see Documentation/vm/slub.txt.
2071 slub_nomerge [MM, SLUB]
2072 Disable merging of slabs with similar size. May be
2073 necessary if there is some reason to distinguish
2074 allocs to different slabs. Debug options disable
2075 merging on their own.
2076 For more information see Documentation/vm/slub.txt.
2079 Format: <io1>[,<io2>[,...,<io8>]]
2081 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2082 attempt to substitute SMP alternatives once at boot.
2084 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2085 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2086 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2087 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2088 smsc-ircc2.ircc_irq= [HW] IRQ line
2089 smsc-ircc2.ircc_dma= [HW] DMA channel
2090 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2091 0: Toshiba Satellite 1800 (GP data pin select)
2092 1: Fast pin select (default)
2095 snd-ad1816a= [HW,ALSA]
2097 snd-ad1848= [HW,ALSA]
2099 snd-ali5451= [HW,ALSA]
2101 snd-als100= [HW,ALSA]
2103 snd-als4000= [HW,ALSA]
2105 snd-azt2320= [HW,ALSA]
2107 snd-cmi8330= [HW,ALSA]
2109 snd-cmipci= [HW,ALSA]
2111 snd-cs4231= [HW,ALSA]
2113 snd-cs4232= [HW,ALSA]
2115 snd-cs4236= [HW,ALSA]
2117 snd-cs4281= [HW,ALSA]
2119 snd-cs46xx= [HW,ALSA]
2121 snd-dt019x= [HW,ALSA]
2123 snd-dummy= [HW,ALSA]
2125 snd-emu10k1= [HW,ALSA]
2127 snd-ens1370= [HW,ALSA]
2129 snd-ens1371= [HW,ALSA]
2131 snd-es968= [HW,ALSA]
2133 snd-es1688= [HW,ALSA]
2135 snd-es18xx= [HW,ALSA]
2137 snd-es1938= [HW,ALSA]
2139 snd-es1968= [HW,ALSA]
2141 snd-fm801= [HW,ALSA]
2143 snd-gusclassic= [HW,ALSA]
2145 snd-gusextreme= [HW,ALSA]
2147 snd-gusmax= [HW,ALSA]
2151 snd-ice1712= [HW,ALSA]
2153 snd-intel8x0= [HW,ALSA]
2155 snd-interwave= [HW,ALSA]
2160 snd-korg1212= [HW,ALSA]
2162 snd-maestro3= [HW,ALSA]
2164 snd-mpu401= [HW,ALSA]
2166 snd-mtpav= [HW,ALSA]
2168 snd-nm256= [HW,ALSA]
2170 snd-opl3sa2= [HW,ALSA]
2178 snd-opti93x= [HW,ALSA]
2182 snd-rme32= [HW,ALSA]
2184 snd-rme96= [HW,ALSA]
2186 snd-rme9652= [HW,ALSA]
2192 snd-sbawe= [HW,ALSA]
2194 snd-serial= [HW,ALSA]
2196 snd-sgalaxy= [HW,ALSA]
2198 snd-sonicvibes= [HW,ALSA]
2203 snd-sun-cs4231= [HW,ALSA]
2205 snd-trident= [HW,ALSA]
2207 snd-usb-audio= [HW,ALSA,USB]
2209 snd-via82xx= [HW,ALSA]
2211 snd-virmidi= [HW,ALSA]
2213 snd-wavefront= [HW,ALSA]
2215 snd-ymfpci= [HW,ALSA]
2218 [KNL] Should the soft-lockup detector generate panics.
2220 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2221 See Documentation/sonypi.txt
2223 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2224 See Documentation/serial/specialix.txt.
2226 spia_io_base= [HW,MTD]
2232 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2234 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2235 See Documentation/scsi/st.txt.
2238 Enabled the stack tracer on boot up.
2242 Set the STI (builtin display/keyboard on the HP-PARISC
2243 machines) console (graphic card) which should be used
2244 as the initial boot-console.
2245 See also comment in drivers/video/console/sticore.c.
2248 See comment in drivers/video/console/sticore.c.
2251 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2255 Control how the NFS server code allocates CPUs to
2256 service thread pools. Depending on how many NICs
2257 you have and where their interrupts are bound, this
2258 option will affect which CPUs will do NFS serving.
2259 Note: this parameter cannot be changed while the
2260 NFS server is running.
2262 auto the server chooses an appropriate mode
2263 automatically using heuristics
2264 global a single global pool contains all CPUs
2265 percpu one pool for each CPU
2266 pernode one pool for each NUMA node (equivalent
2267 to global on non-NUMA machines)
2269 swiotlb= [IA-64] Number of I/O TLB slabs
2273 sym53c416= [HW,SCSI]
2274 See header of drivers/scsi/sym53c416.c.
2276 sysrq_always_enabled
2278 Ignore sysrq setting - this boot parameter will
2279 neutralize any effect of /proc/sys/kernel/sysrq.
2280 Useful for debugging.
2283 See header of drivers/scsi/t128.c.
2287 test_suspend= [SUSPEND]
2288 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2289 standby suspend) as the system sleep state to briefly
2290 enter during system startup. The system is woken from
2291 this state using a wakeup-capable RTC alarm.
2293 thash_entries= [KNL,NET]
2294 Set number of hash buckets for TCP connection
2296 thermal.act= [HW,ACPI]
2297 -1: disable all active trip points in all thermal zones
2298 <degrees C>: override all lowest active trip points
2300 thermal.crt= [HW,ACPI]
2301 -1: disable all critical trip points in all thermal zones
2302 <degrees C>: override all critical trip points
2304 thermal.nocrt= [HW,ACPI]
2305 Set to disable actions on ACPI thermal zone
2306 critical and hot trip points.
2308 thermal.off= [HW,ACPI]
2309 1: disable ACPI thermal control
2311 thermal.psv= [HW,ACPI]
2312 -1: disable all passive trip points
2313 <degrees C>: override all passive trip points to this
2316 thermal.tzp= [HW,ACPI]
2317 Specify global default ACPI thermal zone polling rate
2318 <deci-seconds>: poll all this frequency
2319 0: no polling (default)
2322 See comment before function dc390_setup() in
2323 drivers/scsi/tmscsim.c.
2327 Specify if the kernel should make use of the cpu
2328 topology informations if the hardware supports these.
2329 The scheduler will make use of these informations and
2330 e.g. base its process migration decisions on it.
2335 trix= [HW,OSS] MediaTrix AudioTrix Pro
2337 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2339 tsc= Disable clocksource-must-verify flag for TSC.
2341 [x86] reliable: mark tsc clocksource as reliable, this
2342 disables clocksource verification at runtime.
2343 Used to enable high-resolution timer mode on older
2344 hardware, and in virtualized environment.
2346 turbografx.map[2|3]= [HW,JOY]
2347 TurboGraFX parallel port interface
2349 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2350 See also Documentation/input/joystick-parport.txt
2352 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2353 See header of drivers/scsi/u14-34f.c.
2362 [USB] Ignore overcurrent events (default N).
2363 Some badly-designed motherboards generate lots of
2364 bogus events, for ports that aren't wired to
2365 anything. Set this parameter to avoid log spamming.
2366 Note that genuine overcurrent events won't be
2371 Set unknown_nmi_panic=1 early on boot.
2373 usbcore.autosuspend=
2374 [USB] The autosuspend time delay (in seconds) used
2375 for newly-detected USB devices (default 2). This
2376 is the time required before an idle device will be
2377 autosuspended. Devices for which the delay is set
2378 to a negative value won't be autosuspended at all.
2380 usbcore.usbfs_snoop=
2381 [USB] Set to log all usbfs traffic (default 0 = off).
2383 usbcore.blinkenlights=
2384 [USB] Set to cycle leds on hubs (default 0 = off).
2386 usbcore.old_scheme_first=
2387 [USB] Start with the old device initialization
2388 scheme (default 0 = off).
2390 usbcore.use_both_schemes=
2391 [USB] Try the other device initialization scheme
2392 if the first one fails (default 1 = enabled).
2394 usbcore.initial_descriptor_timeout=
2395 [USB] Specifies timeout for the initial 64-byte
2396 USB_REQ_GET_DESCRIPTOR request in milliseconds
2397 (default 5000 = 5.0 seconds).
2400 [USBHID] The interval which mice are to be polled at.
2402 usb-storage.delay_use=
2403 [UMS] The delay in seconds before a new device is
2404 scanned for Logical Units (default 5).
2407 [UMS] A list of quirks entries to supplement or
2408 override the built-in unusual_devs list. List
2409 entries are separated by commas. Each entry has
2410 the form VID:PID:Flags where VID and PID are Vendor
2411 and Product ID values (4-digit hex numbers) and
2412 Flags is a set of characters, each corresponding
2413 to a common usb-storage quirk flag as follows:
2414 a = SANE_SENSE (collect more than 18 bytes
2416 c = FIX_CAPACITY (decrease the reported
2417 device capacity by one sector);
2418 h = CAPACITY_HEURISTICS (decrease the
2419 reported device capacity by one
2420 sector if the number is odd);
2421 i = IGNORE_DEVICE (don't bind to this
2423 l = NOT_LOCKABLE (don't try to lock and
2424 unlock ejectable media);
2425 m = MAX_SECTORS_64 (don't transfer more
2426 than 64 sectors = 32 KB at a time);
2427 o = CAPACITY_OK (accept the capacity
2428 reported by the device);
2429 r = IGNORE_RESIDUE (the device reports
2430 bogus residue values);
2431 s = SINGLE_LUN (the device has only one
2433 w = NO_WP_DETECT (don't test whether the
2434 medium is write-protected).
2435 Example: quirks=0419:aaf5:rl,0421:0433:rc
2437 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2438 kernel's map of available physical RAM.
2440 vdso= [X86-32,SH,x86-64]
2441 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2442 vdso=1: enable VDSO (default)
2443 vdso=0: disable VDSO mapping
2445 vdso32= [X86-32,X86-64]
2446 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2447 vdso32=1: enable 32-bit VDSO (default)
2448 vdso32=0: disable 32-bit VDSO mapping
2451 vector=percpu: enable percpu vector domain
2453 video= [FB] Frame buffer configuration
2454 See Documentation/fb/modedb.txt.
2456 vga= [BOOT,X86-32] Select a particular video mode
2457 See Documentation/x86/i386/boot.txt and
2458 Documentation/svga.txt.
2459 Use vga=ask for menu.
2460 This is actually a boot loader parameter; the value is
2461 passed to the kernel using a special protocol.
2463 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2464 size of <nn>. This can be used to increase the
2465 minimum size (128MB on x86). It can also be used to
2466 decrease the size and leave more room for directly
2469 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2472 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2475 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2478 waveartist= [HW,OSS]
2479 Format: <io>,<irq>,<dma>,<dma2>
2482 See header of drivers/scsi/wd33c93.c.
2485 See header of drivers/scsi/wd7000.c.
2488 See Documentation/watchdog/wdt.txt.
2490 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2491 xd_geo= See header of drivers/block/xd.c.
2493 xirc2ps_cs= [NET,PCMCIA]
2495 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2497 norandmaps Don't use address space randomization. Equivalent to
2498 echo 0 > /proc/sys/kernel/randomize_va_space
2500 ______________________________________________________________________
2504 Add documentation for ALSA options.
2505 Add more DRM drivers.
projects / linux-2.6 / blob