4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 KMEMTRACE kmemtrace is enabled.
53 LIBATA Libata driver is enabled
54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
62 MSI Message Signaled Interrupts (PCI).
63 MTD MTD (Memory Technology Device) support is enabled.
64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
66 GENERIC_TIME The generic timeofday code is enabled.
67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
73 PCIE PCI Express support is enabled.
74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
80 ROOTPLUG The example Root Plug LSM is enabled.
81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
85 SECURITY Different security models are enabled.
86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
88 SH SuperH architecture is enabled.
89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
91 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are enabled.
93 FTRACE Function tracing enabled.
94 TS Appropriate touchscreen support is enabled.
95 UMS USB Mass Storage support is enabled.
96 USB USB support is enabled.
97 USBHID USB Human Interface Device support is enabled.
98 V4L Video For Linux support is enabled.
99 VGA The VGA console has been enabled.
100 VT Virtual terminal support is enabled.
101 WDT Watchdog support is enabled.
102 XT IBM PC/XT MFM hard disk support is enabled.
103 X86-32 X86-32, aka i386 architecture is enabled.
104 X86-64 X86-64 architecture is enabled.
105 More X86-64 boot options can be found in
106 Documentation/x86/x86_64/boot-options.txt .
107 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
109 In addition, the following text indicates that the option:
111 BUGS= Relates to possible processor bugs on the said processor.
112 KNL Is a kernel start-up parameter.
113 BOOT Is a boot loader parameter.
115 Parameters denoted with BOOT are actually interpreted by the boot
116 loader, and have no meaning to the kernel directly.
117 Do not modify the syntax of boot loader parameters without extreme
118 need or coordination with <Documentation/x86/i386/boot.txt>.
120 There are also arch-specific kernel-parameters not documented here.
121 See for example <Documentation/x86/x86_64/boot-options.txt>.
123 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
124 a trailing = on the name of any parameter states that that parameter will
125 be entered as an environment variable, whereas its absence indicates that
126 it will appear as a kernel argument readable via /proc/cmdline by programs
127 running once the system is up.
129 The number of kernel parameters is not limited, but the length of the
130 complete command line (parameters including spaces etc.) is limited to
131 a fixed number of characters. This limit depends on the architecture
132 and is between 256 and 4096 characters. It is defined in the file
133 ./include/asm/setup.h as COMMAND_LINE_SIZE.
136 acpi= [HW,ACPI,X86-64,i386]
137 Advanced Configuration and Power Interface
138 Format: { force | off | ht | strict | noirq | rsdt }
139 force -- enable ACPI if default was off
140 off -- disable ACPI if default was on
141 noirq -- do not use ACPI for IRQ routing
142 ht -- run only enough ACPI to enable Hyper Threading
143 strict -- Be less tolerant of platforms that are not
144 strictly ACPI specification compliant.
145 rsdt -- prefer RSDT over (default) XSDT
147 See also Documentation/power/pm.txt, pci=noacpi
149 acpi_apic_instance= [ACPI, IOAPIC]
151 2: use 2nd APIC table, if available
152 1,0: use 1st APIC table
155 acpi_sleep= [HW,ACPI] Sleep options
156 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
157 old_ordering, s4_nonvs }
158 See Documentation/power/video.txt for information on
160 s3_beep is for debugging; it makes the PC's speaker beep
161 as soon as the kernel's real-mode entry point is called.
162 s4_nohwsig prevents ACPI hardware signature from being
163 used during resume from hibernation.
164 old_ordering causes the ACPI 1.0 ordering of the _PTS
165 control method, with respect to putting devices into
166 low power states, to be enforced (the ACPI 2.0 ordering
167 of _PTS is used by default).
168 s4_nonvs prevents the kernel from saving/restoring the
169 ACPI NVS memory during hibernation.
171 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
172 Format: { level | edge | high | low }
174 acpi_irq_balance [HW,ACPI]
175 ACPI will balance active IRQs
178 acpi_irq_nobalance [HW,ACPI]
179 ACPI will not move active IRQs (default)
182 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
184 Format: <irq>,<irq>...
186 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
187 Format: <irq>,<irq>...
189 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
191 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
192 Format: To spoof as Windows 98: ="Microsoft Windows"
194 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
195 acpi_osi="string1" # add string1 -- only one string
196 acpi_osi="!string2" # remove built-in string2
197 acpi_osi= # disable all strings
199 acpi_serialize [HW,ACPI] force serialization of AML methods
201 acpi_skip_timer_override [HW,ACPI]
202 Recognize and ignore IRQ0/pin2 Interrupt Override.
203 For broken nForce2 BIOS resulting in XT-PIC timer.
204 acpi_use_timer_override [HW,ACPI]
205 Use timer override. For some broken Nvidia NF5 boards
206 that require a timer override, but don't have
209 acpi_backlight= [HW,ACPI]
210 acpi_backlight=vendor
212 If set to vendor, prefer vendor specific driver
213 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
214 of the ACPI video.ko driver.
216 acpi_display_output= [HW,ACPI]
217 acpi_display_output=vendor
218 acpi_display_output=video
221 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
222 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
224 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
225 debug output. Bits in debug_layer correspond to a
226 _COMPONENT in an ACPI source file, e.g.,
227 #define _COMPONENT ACPI_PCI_COMPONENT
228 Bits in debug_level correspond to a level in
229 ACPI_DEBUG_PRINT statements, e.g.,
230 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
231 The debug_level mask defaults to "info". See
232 Documentation/acpi/debug.txt for more information about
233 debug layers and levels.
235 Enable processor driver info messages:
236 acpi.debug_layer=0x20000000
237 Enable PCI/PCI interrupt routing info messages:
238 acpi.debug_layer=0x400000
239 Enable AML "Debug" output, i.e., stores to the Debug
240 object while interpreting AML:
241 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
242 Enable all messages related to ACPI hardware:
243 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
245 Some values produce so much output that the system is
246 unusable. The "log_buf_len" parameter may be useful
247 if you need to capture more output.
249 acpi.power_nocheck= [HW,ACPI]
250 Format: 1/0 enable/disable the check of power state.
251 On some bogus BIOS the _PSC object/_STA object of
252 power resource can't return the correct device power
253 state. In such case it is unneccessary to check its
254 power state again in power transition.
255 1 : disable the power state check
257 acpi_pm_good [X86-32,X86-64]
258 Override the pmtimer bug detection: force the kernel
259 to assume that this machine's pmtimer latches its value
260 and always returns good values.
263 { off | try_unsupported }
264 off: disable AGP support
265 try_unsupported: try to drive unsupported chipsets
266 (may crash computer or cause data corruption)
268 enable_timer_pin_1 [i386,x86-64]
269 Enable PIN 1 of APIC timer
270 Can be useful to work around chipset bugs
271 (in particular on some ATI chipsets).
272 The kernel tries to set a reasonable default.
274 disable_timer_pin_1 [i386,x86-64]
275 Disable PIN 1 of APIC timer
276 Can be useful to work around chipset bugs.
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
282 See header of drivers/scsi/advansys.c.
284 advwdt= [HW,WDT] Advantech WDT
285 Format: <iostart>,<iostop>
287 aedsp16= [HW,OSS] Audio Excel DSP 16
288 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
289 See also header of sound/oss/aedsp16.c.
292 See Documentation/scsi/aha152x.txt.
295 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
298 See Documentation/scsi/aic7xxx.txt.
301 See Documentation/scsi/aic79xx.txt.
303 amd_iommu= [HW,X86-84]
304 Pass parameters to the AMD IOMMU driver in the system.
306 isolate - enable device isolation (each device, as far
307 as possible, will get its own protection
309 share - put every device behind one IOMMU into the
310 same protection domain
311 fullflush - enable flushing of IO/TLB entries when
312 they are unmapped. Otherwise they are
313 flushed before they will be reused, which
316 amd_iommu_size= [HW,X86-64]
317 Define the size of the aperture for the AMD IOMMU
318 driver. Possible values are:
319 '32M', '64M' (default), '128M', '256M', '512M', '1G'
321 amijoy.map= [HW,JOY] Amiga joystick support
322 Map of devices attached to JOY0DAT and JOY1DAT
324 See also Documentation/kernel/input/joystick.txt
326 analog.map= [HW,JOY] Analog joystick and gamepad support
327 Specifies type or capabilities of an analog joystick
328 connected to one of 16 gameports
329 Format: <type1>,<type2>,..<type16>
332 Power management functions (SPARCstation-4/5 + deriv.)
334 Disable APC CPU standby support. SPARCstation-Fox does
335 not play well with APC CPU idle - disable it if you have
336 APC and your system crashes randomly.
338 apic= [APIC,i386] Advanced Programmable Interrupt Controller
339 Change the output verbosity whilst booting
340 Format: { quiet (default) | verbose | debug }
341 Change the amount of debugging information output
342 when initialising the APIC and IO-APIC components.
344 apm= [APM] Advanced Power Management
345 See header of arch/x86/kernel/apm_32.c.
347 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
348 Format: <io>,<irq>,<nodeID>
352 atarimouse= [HW,MOUSE] Atari Mouse
354 atascsi= [HW,SCSI] Atari SCSI
356 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
357 EzKey and similar keyboards
359 atkbd.reset= [HW] Reset keyboard during initialization
361 atkbd.set= [HW] Select keyboard code set
362 Format: <int> (2 = AT (default), 3 = PS/2)
364 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
367 atkbd.softraw= [HW] Choose between synthetic and real raw mode
368 Format: <bool> (0 = real, 1 = synthetic (default))
370 atkbd.softrepeat= [HW]
371 Use software keyboard repeat
375 baycom_epp= [HW,AX25]
378 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
380 See header of drivers/net/hamradio/baycom_par.c.
382 baycom_ser_fdx= [HW,AX25]
383 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
384 Format: <io>,<irq>,<mode>[,<baud>]
385 See header of drivers/net/hamradio/baycom_ser_fdx.c.
387 baycom_ser_hdx= [HW,AX25]
388 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
389 Format: <io>,<irq>,<mode>
390 See header of drivers/net/hamradio/baycom_ser_hdx.c.
392 boot_delay= Milliseconds to delay each printk during boot.
393 Values larger than 10 seconds (10000) are changed to
397 bootmem_debug [KNL] Enable bootmem allocator debug messages.
399 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
400 bttv.radio= Most important insmod options are available as
402 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
403 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
406 See drivers/scsi/BusLogic.c, comment before function
407 BusLogic_ParseDriverOptions().
409 c101= [NET] Moxa C101 synchronous serial card
411 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
412 Sometimes CPU hardware bugs make them report the cache
413 size incorrectly. The kernel will attempt work arounds
414 to fix known problems, but for some CPUs it is not
415 possible to determine what the correct size should be.
416 This option provides an override for these situations.
418 security= [SECURITY] Choose a security module to enable at boot.
419 If this boot parameter is not specified, only the first
420 security module asking for security registration will be
421 loaded. An invalid security module name will be treated
422 as if no module has been chosen.
425 [SECURITY] Disable capabilities. This would normally
426 be used only if an alternative security model is to be
427 configured. Potentially dangerous and should only be
428 used if you are entirely sure of the consequences.
430 ccw_timeout_log [S390]
431 See Documentation/s390/CommonIO for details.
433 cgroup_disable= [KNL] Disable a particular controller
434 Format: {name of the controller(s) to disable}
435 {Currently supported controllers - "memory"}
437 checkreqprot [SELINUX] Set initial checkreqprot flag value.
438 Format: { "0" | "1" }
439 See security/selinux/Kconfig help text.
440 0 -- check protection applied by kernel (includes
441 any implied execute protection).
442 1 -- check protection requested by application.
443 Default value is set via a kernel config option.
444 Value can be changed at runtime via
445 /selinux/checkreqprot.
448 See Documentation/s390/CommonIO for details.
450 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
452 Forces specified clocksource (if available) to be used
453 when calculating gettimeofday(). If specified
454 clocksource is not available, it defaults to PIT.
455 Format: { pit | tsc | cyclone | pmtmr }
457 clocksource= [GENERIC_TIME] Override the default clocksource
459 Override the default clocksource and use the clocksource
460 with the name specified.
461 Some clocksource names to choose from, depending on
463 [all] jiffies (this is the base, fallback clocksource)
465 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
466 pxa_timer,timer3,32k_counter,timer0_1
468 [X86-32] pit,hpet,tsc,vmi-timer;
469 scx200_hrt on Geode; cyclone on IBM x440
477 clearcpuid=BITNUM [X86]
478 Disable CPUID feature X for the kernel. See
479 arch/x86/include/asm/cpufeature.h for the valid bit
480 numbers. Note the Linux specific bits are not necessarily
481 stable over kernel options, but the vendor specific
483 Also note that user programs calling CPUID directly
484 or using the feature without checking anything
485 will still see it. This just prevents it from
486 being used by the kernel or shown in /proc/cpuinfo.
487 Also note the kernel might malfunction if you disable
490 code_bytes [IA32/X86_64] How many bytes of object code to print
495 hpet= [X86-32,HPET] option to control HPET usage
496 Format: { enable (default) | disable | force }
497 disable: disable HPET and use PIT instead
498 force: allow force enabled of undocumented chips (ICH4,
501 com20020= [HW,NET] ARCnet - COM20020 chipset
503 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
505 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
509 ARCnet - COM90xx chipset (memory-mapped buffers)
510 Format: <io>[,<irq>[,<memstart>]]
512 condev= [HW,S390] console device
515 console= [KNL] Output console device and options.
517 tty<n> Use the virtual console device <n>.
521 Use the specified serial port. The options are of
522 the form "bbbbpnf", where "bbbb" is the baud rate,
523 "p" is parity ("n", "o", or "e"), "n" is number of
524 bits, and "f" is flow control ("r" for RTS or
525 omit it). Default is "9600n8".
527 See Documentation/serial-console.txt for more
529 Documentation/networking/netconsole.txt for an
532 uart[8250],io,<addr>[,options]
533 uart[8250],mmio,<addr>[,options]
534 Start an early, polled-mode console on the 8250/16550
535 UART at the specified I/O port or MMIO address,
536 switching to the matching ttyS device later. The
537 options are the same as for ttyS, above.
539 If the device connected to the port is not a TTY but a braille
540 device, prepend "brl," before the device type, for instance
542 For now, only VisioBraille is supported.
544 earlycon= [KNL] Output early console device and options.
545 uart[8250],io,<addr>[,options]
546 uart[8250],mmio,<addr>[,options]
547 Start an early, polled-mode console on the 8250/16550
548 UART at the specified I/O port or MMIO address.
549 The options are the same as for ttyS, above.
552 [HW] Never suspend the console
553 Disable suspending of consoles during suspend and
554 hibernate operations. Once disabled, debugging
555 messages can reach various consoles while the rest
556 of the system is being put to sleep (ie, while
557 debugging driver suspend/resume hooks). This may
558 not work reliably with all consoles, but is known
559 to work with serial and VGA consoles.
562 [KNL] Change the default value for
563 /proc/<pid>/coredump_filter.
564 See also Documentation/filesystems/proc.txt.
566 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
568 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
570 crashkernel=nn[KMG]@ss[KMG]
571 [KNL] Reserve a chunk of physical memory to
572 hold a kernel to switch to with kexec on panic.
574 crashkernel=range1:size1[,range2:size2,...][@offset]
575 [KNL] Same as above, but depends on the memory
576 in the running system. The syntax of range is
577 start-[end] where start and end are both
578 a memory unit (amount[KMG]). See also
579 Documentation/kdump/kdump.txt for a example.
584 cs89x0_media= [HW,NET]
585 Format: { rj45 | aui | bnc }
588 See header of drivers/s390/block/dasd_devmap.c.
590 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
591 (one device per port)
592 Format: <port#>,<type>
593 See also Documentation/input/joystick-parport.txt
595 debug [KNL] Enable kernel debugging (events log level).
598 [KNL] verbose self-tests
600 Print debugging info while doing the locking API
602 We default to 0 (no extra messages), setting it to
603 1 will print _a lot_ more information - normally
604 only useful to kernel developers.
606 debug_objects [KNL] Enable object debugging
608 debugpat [X86] Enable PAT debugging
610 decnet.addr= [HW,NET]
611 Format: <area>[,<node>]
612 See also Documentation/networking/decnet.txt.
615 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
616 Change the default blue palette of the console.
617 This is a 16-member array composed of values
621 Format: <green0>,<green1>,<green2>,...,<green15>
622 Change the default green palette of the console.
623 This is a 16-member array composed of values
627 Format: <red0>,<red1>,<red2>,...,<red15>
628 Change the default red palette of the console.
629 This is a 16-member array composed of values
635 Set system-wide default UTF-8 mode for all tty's.
636 Default is 1, i.e. UTF-8 mode is enabled for all
637 newly opened terminals.
640 Set number of hash buckets for dentry cache.
643 IO parameters + enable/disable command.
645 digiepca= [HW,SERIAL]
646 See drivers/char/README.epca and
647 Documentation/serial/digiepca.txt.
649 disable_mtrr_cleanup [X86]
650 enable_mtrr_cleanup [X86]
651 The kernel tries to adjust MTRR layout from continuous
652 to discrete, to make X server driver able to add WB
653 entry later. This parameter enables/disables that.
655 mtrr_chunk_size=nn[KMG] [X86]
656 used for mtrr cleanup. It is largest continous chunk
657 that could hold holes aka. UC entries.
659 mtrr_gran_size=nn[KMG] [X86]
660 Used for mtrr cleanup. It is granularity of mtrr block.
662 Large value could prevent small alignment from
665 mtrr_spare_reg_nr=n [X86]
667 Range: 0,7 : spare reg number
669 Used for mtrr cleanup. It is spare mtrr entries number.
670 Set to 2 or more if your graphical card needs more.
672 disable_mtrr_trim [X86, Intel and AMD only]
673 By default the kernel will trim any uncacheable
674 memory out of your available memory pool based on
675 MTRR settings. This parameter disables that behavior,
676 possibly causing your machine to run very slowly.
678 dmasound= [HW,OSS] Sound subsystem buffers
684 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
686 earlyprintk=serial[,ttySn[,baudrate]]
689 Append ",keep" to not disable it when the real console
692 Only vga or serial or usb debug port at a time.
694 Currently only ttyS0 and ttyS1 are supported.
696 Interaction with the standard serial driver is not
699 The VGA output is eventually overwritten by the real
705 Format: {"off" | "on" | "skip[mbr]"}
707 eisa_irq_edge= [PARISC,HW]
708 See header of drivers/parisc/eisa.c.
711 See comment before function elanfreq_setup() in
712 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
715 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
716 See Documentation/block/as-iosched.txt and
717 Documentation/block/deadline-iosched.txt for details.
719 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
720 Specifies physical address of start of kernel core
721 image elf header. Generally kexec loader will
722 pass this option to capture kernel.
723 See Documentation/kdump/kdump.txt for details.
725 enforcing [SELINUX] Set initial enforcing status.
727 See security/selinux/Kconfig help text.
728 0 -- permissive (log only, no denials).
729 1 -- enforcing (deny and log).
731 Value can be changed at runtime via /selinux/enforce.
733 ether= [HW,NET] Ethernet cards parameters
734 This option is obsoleted by the "netdev=" option, which
735 has equivalent usage. See its documentation for details.
737 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
742 fail_make_request=[KNL]
743 General fault injection mechanism.
744 Format: <interval>,<probability>,<space>,<times>
745 See also /Documentation/fault-injection/.
748 See header of drivers/scsi/fd_mcs.c.
751 See header of drivers/scsi/fdomain.c.
754 See Documentation/blockdev/floppy.txt.
756 force_pal_cache_flush
757 [IA-64] Avoid check_sal_cache_flush which may hang on
758 buggy SAL_CACHE_FLUSH implementations. Using this
759 parameter will force ia64_sal_cache_flush to call
760 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
763 [ftrace] will set and start the specified tracer
764 as early as possible in order to facilitate early
768 [ftrace] will dump the trace buffers on oops.
771 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
772 support via parallel port (up to 5 devices per port)
773 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
774 See also Documentation/input/joystick-parport.txt
778 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
783 See header of drivers/scsi/gdth.c.
785 gpt [EFI] Forces disk with valid GPT signature but
786 invalid Protective MBR to be treated as GPT.
790 hashdist= [KNL,NUMA] Large hashes allocated during boot
791 are distributed across NUMA nodes. Defaults on
792 for IA-64, off otherwise.
793 Format: 0 | 1 (for off | on)
795 hcl= [IA-64] SGI's Hardware Graph compatibility layer
797 hd= [EIDE] (E)IDE hard drive subsystem geometry
798 Format: <cyl>,<head>,<sect>
800 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
801 size of <nn>. This works even on boxes that have no
802 highmem otherwise. This also works to reduce highmem
803 size on bigger boxes.
805 highres= [KNL] Enable/disable high resolution timer mode.
806 Valid parameters: "on", "off"
810 See Documentation/isdn/README.HiSax.
812 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
813 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
814 On x86-64 and powerpc, this option can be specified
815 multiple times interleaved with hugepages= to reserve
816 huge pages of different sizes. Valid pages sizes on
817 x86-64 are 2M (when the CPU supports "pse") and 1G
818 (when the CPU supports the "pdpe1gb" cpuinfo flag)
819 Note that 1GB pages can only be allocated at boot time
820 using hugepages= and not freed afterwards.
822 [same as hugepagesz=] The size of the default
823 HugeTLB page size. This is the size represented by
824 the legacy /proc/ hugepages APIs, used for SHM, and
825 default size when mounting hugetlbfs filesystems.
826 Defaults to the default architecture's huge page size
831 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
832 terminal devices. Valid values: 0..8
834 i8042.debug [HW] Toggle i8042 debug mode
835 i8042.direct [HW] Put keyboard port into non-translated mode
836 i8042.dumbkbd [HW] Pretend that controller can only read data from
837 keyboard and cannot control its state
838 (Don't attempt to blink the leds)
839 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
840 i8042.nokbd [HW] Don't check/create keyboard port
841 i8042.noloop [HW] Disable the AUX Loopback command while probing
843 i8042.nomux [HW] Don't check presence of an active multiplexing
845 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
848 [HW] Frequency with which keyboard LEDs should blink
849 when kernel panics (default is 0.5 sec)
850 i8042.reset [HW] Reset the controller during init and cleanup
851 i8042.unlock [HW] Unlock (ignore) the keylock
855 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
856 indicates that the driver is running on unsupported
858 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
859 does not match list of supported models.
861 [HW] Report power status in /proc/i8k
862 (disabled by default)
863 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
866 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
867 See Documentation/mca.txt.
870 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
872 ide= [HW] (E)IDE subsystem
873 Format: ide=nodma or ide=doubler
874 See Documentation/ide/ide.txt.
876 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
877 See Documentation/ide/ide.txt.
880 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
881 Poll forces a polling idle loop that can slightly
882 improve the performance of waking up a idle CPU, but
883 will use a lot of power and make the system run hot.
885 idle=mwait: On systems which support MONITOR/MWAIT but
886 the kernel chose to not use it because it doesn't save
887 as much power as a normal idle loop, use the
888 MONITOR/MWAIT idle loop anyways. Performance should be
889 the same as idle=poll.
890 idle=halt: Halt is forced to be used for CPU idle.
891 In such case C2/C3 won't be used again.
892 idle=nomwait: Disable mwait for CPU C-states
894 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
895 Claim all unknown PCI IDE storage controllers.
897 ignore_loglevel [KNL]
898 Ignore loglevel setting - this will print /all/
899 kernel messages to the console. Useful for debugging.
902 Set number of hash buckets for inode cache.
905 See header of drivers/scsi/in2000.c.
909 Run specified binary instead of /sbin/init as init
912 initcall_debug [KNL] Trace initcalls as they are executed. Useful
913 for working out where the kernel is dying during
916 initrd= [BOOT] Specify the location of the initial ramdisk
918 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
923 iomem= Disable strict checking of access to MMIO memory
924 strict regions from userspace.
940 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
942 Enable intel iommu driver.
944 Disable intel iommu driver.
945 igfx_off [Default Off]
946 By default, gfx is mapped as normal device. If a gfx
947 device has a dedicated DMAR unit, the DMAR unit is
948 bypassed by not enabling DMAR with this option. In
949 this case, gfx device will use physical address for
952 With this option iommu will not optimize to look
953 for io virtual address below 32 bit forcing dual
954 address cycle on pci bus for cards supporting greater
955 than 32 bit addressing. The default is to look
956 for translation below 32 bit and if not available
957 then look in the higher range.
959 With this option on every unmap_single operation will
960 result in a hardware IOTLB flush operation as opposed
961 to batching them for performance.
963 io_delay= [X86-32,X86-64] I/O delay method
965 Standard port 0x80 based delay
967 Alternate port 0xed based delay (needed on some systems)
969 Simple two microseconds delay
973 io7= [HW] IO7 for Marvel based alpha systems
974 See comment before marvel_specify_io7 in
975 arch/alpha/kernel/core_marvel.c.
978 See Documentation/filesystems/nfsroot.txt.
980 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
981 See comment before ip2_setup() in
982 drivers/char/ip2/ip2base.c.
984 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
985 See header of drivers/scsi/ips.c.
987 ports= [IP_VS_FTP] IPVS ftp helper module
989 Up to 8 (IP_VS_APP_MAX_PORTS) ports
991 Format: <port>,<port>....
994 When an interrupt is not handled search all handlers
995 for it. Intended to get systems with badly broken
999 When an interrupt is not handled search all handlers
1000 for it. Also check all handlers each timer
1001 interrupt. Intended to get systems with badly broken
1005 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1007 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1009 <cpu number>,...,<cpu number>
1011 <cpu number>-<cpu number>
1012 (must be a positive range in ascending order)
1014 <cpu number>,...,<cpu number>-<cpu number>
1016 This option can be used to specify one or more CPUs
1017 to isolate from the general SMP balancing and scheduling
1018 algorithms. You can move a process onto or off an
1019 "isolated" CPU via the CPU affinity syscalls or cpuset.
1020 <cpu number> begins at 0 and the maximum value is
1021 "number of CPUs in system - 1".
1023 This option is the preferred way to isolate CPUs. The
1024 alternative -- manually setting the CPU mask of all
1025 tasks in the system -- can cause problems and
1026 suboptimal load balancer performance.
1030 js= [HW,JOY] Analog joystick
1031 See Documentation/input/joystick.txt.
1033 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1034 specifies the amount of memory usable by the kernel
1035 for non-movable allocations. The requested amount is
1036 spread evenly throughout all nodes in the system. The
1037 remaining memory in each node is used for Movable
1038 pages. In the event, a node is too small to have both
1039 kernelcore and Movable pages, kernelcore pages will
1040 take priority and other nodes will have a larger number
1041 of kernelcore pages. The Movable zone is used for the
1042 allocation of pages that may be reclaimed or moved
1043 by the page migration subsystem. This means that
1044 HugeTLB pages may not be allocated from this zone.
1045 Note that allocations like PTEs-from-HighMem still
1046 use the HighMem zone if it exists, and the Normal
1047 zone if it does not.
1049 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1050 Controls whether kmemtrace is enabled
1053 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1054 subbufs kmemtrace's relay channel has. Set this
1055 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1056 you experience buffer overruns.
1058 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1059 is similar to kernelcore except it specifies the
1060 amount of memory used for migratable allocations.
1061 If both kernelcore and movablecore is specified,
1062 then kernelcore will be at *least* the specified
1063 value but may be more. If movablecore on its own
1064 is specified, the administrator must be careful
1065 that the amount of memory usable for all allocations
1070 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1073 kgdboc= [HW] kgdb over consoles.
1074 Requires a tty driver that supports console polling.
1075 (only serial suported for now)
1076 Format: <serial_device>[,baud]
1078 kmac= [MIPS] korina ethernet MAC address.
1079 Configure the RouterBoard 532 series on-chip
1080 Ethernet adapter MAC address.
1086 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1089 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1092 libata.dma= [LIBATA] DMA control
1093 libata.dma=0 Disable all PATA and SATA DMA
1094 libata.dma=1 PATA and SATA Disk DMA only
1095 libata.dma=2 ATAPI (CDROM) DMA only
1096 libata.dma=4 Compact Flash DMA only
1097 Combinations also work, so libata.dma=3 enables DMA
1098 for disks and CDROMs, but not CFs.
1100 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1104 libata.force= [LIBATA] Force configurations. The format is comma
1105 separated list of "[ID:]VAL" where ID is
1106 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1107 matching port, link or device. Basically, it matches
1108 the ATA ID string printed on console by libata. If
1109 the whole ID part is omitted, the last PORT and DEVICE
1110 values are used. If ID hasn't been specified yet, the
1111 configuration applies to all ports, links and devices.
1113 If only DEVICE is omitted, the parameter applies to
1114 the port and all links and devices behind it. DEVICE
1115 number of 0 either selects the first device or the
1116 first fan-out link behind PMP device. It does not
1117 select the host link. DEVICE number of 15 selects the
1118 host link and device attached to it.
1120 The VAL specifies the configuration to force. As long
1121 as there's no ambiguity shortcut notation is allowed.
1122 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1123 The following configurations can be forced.
1125 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1126 Any ID with matching PORT is used.
1128 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1130 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1131 udma[/][16,25,33,44,66,100,133] notation is also
1134 * [no]ncq: Turn on or off NCQ.
1136 * nohrst, nosrst, norst: suppress hard, soft
1139 If there are multiple matching configurations changing
1140 the same attribute, the last one is used.
1142 lmb=debug [KNL] Enable lmb debug messages.
1144 load_ramdisk= [RAM] List of ramdisks to load from floppy
1145 See Documentation/blockdev/ramdisk.txt.
1147 lockd.nlm_grace_period=P [NFS] Assign grace period.
1150 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1153 lockd.nlm_timeout=T [NFS] Assign timeout value.
1156 lockd.nlm_udpport=M [NFS] Assign UDP port.
1159 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1162 loglevel= All Kernel Messages with a loglevel smaller than the
1163 console loglevel will be printed to the console. It can
1164 also be changed with klogd or other programs. The
1165 loglevels are defined as follows:
1167 0 (KERN_EMERG) system is unusable
1168 1 (KERN_ALERT) action must be taken immediately
1169 2 (KERN_CRIT) critical conditions
1170 3 (KERN_ERR) error conditions
1171 4 (KERN_WARNING) warning conditions
1172 5 (KERN_NOTICE) normal but significant condition
1173 6 (KERN_INFO) informational
1174 7 (KERN_DEBUG) debug-level messages
1176 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1177 Format: { n | nk | nM }
1178 n must be a power of two. The default size
1179 is set in the kernel config file.
1181 logo.nologo [FB] Disables display of the built-in Linux logo.
1182 This may be used to provide more screen space for
1183 kernel log messages and is useful when debugging
1184 kernel boot problems.
1186 lp=0 [LP] Specify parallel ports to use, e.g,
1187 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1188 lp=reset first parallel port). 'lp=0' disables the
1189 lp=auto printer driver. 'lp=reset' (which can be
1190 specified in addition to the ports) causes
1191 attached printers to be reset. Using
1192 lp=port1,port2,... specifies the parallel ports
1193 to associate lp devices with, starting with
1194 lp0. A port specification may be 'none' to skip
1195 that lp device, or a parport name such as
1196 'parport0'. Specifying 'lp=auto' instead of a
1197 port specification list means that device IDs
1198 from each port should be examined, to see if
1199 an IEEE 1284-compliant printer is attached; if
1200 so, the driver will manage that printer.
1201 See also header of drivers/char/lp.c.
1204 Sets loops_per_jiffy to given constant, thus avoiding
1205 time-consuming boot-time autodetection (up to 250 ms per
1206 CPU). 0 enables autodetection (default). To determine
1207 the correct value for your kernel, boot with normal
1208 autodetection and see what value is printed. Note that
1209 on SMP systems the preset will be applied to all CPUs,
1210 which is likely to cause problems if your CPUs need
1211 significantly divergent settings. An incorrect value
1212 will cause delays in the kernel to be wrong, leading to
1213 unpredictable I/O errors and other breakage. Although
1214 unlikely, in the extreme case this might damage your
1218 Format: <io>,<irq>,<dma>
1220 mac5380= [HW,SCSI] Format:
1221 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1223 machvec= [IA64] Force the use of a particular machine-vector
1224 (machvec) in a generic kernel.
1225 Example: machvec=hpzx1_swiotlb
1227 max_loop= [LOOP] Maximum number of loopback devices that can
1231 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1232 should make use of. maxcpus=n : n >= 0 limits the
1233 kernel to using 'n' processors. n=0 is a special case,
1234 it is equivalent to "nosmp", which also disables
1237 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1238 or equal to this physical address is ignored.
1240 max_luns= [SCSI] Maximum number of LUNs to probe.
1241 Should be between 1 and 2^32-1.
1244 [SCSI] Maximum number of LUNs received.
1245 Should be between 1 and 16384.
1249 mce [X86-32] Machine Check Exception
1251 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1253 md= [HW] RAID subsystems devices and level
1254 See Documentation/md.txt.
1257 Format: <first>,<last>
1258 Specifies range of consoles to be captured by the MDA.
1260 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1261 Amount of memory to be used when the kernel is not able
1262 to see the whole system memory or for test.
1263 [X86-32] Use together with memmap= to avoid physical
1264 address space collisions. Without memmap= PCI devices
1265 could be placed at addresses belonging to unused RAM.
1267 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1271 [KNL,SH] Allow user to override the default size for
1272 per-device physically contiguous DMA buffers.
1274 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1275 E820 memory map, as specified by the user.
1276 Such memmap=exactmap lines can be constructed based on
1277 BIOS output or other requirements. See the memmap=nn@ss
1280 memmap=nn[KMG]@ss[KMG]
1281 [KNL] Force usage of a specific region of memory
1282 Region of memory to be used, from ss to ss+nn.
1284 memmap=nn[KMG]#ss[KMG]
1285 [KNL,ACPI] Mark specific memory as ACPI data.
1286 Region of memory to be used, from ss to ss+nn.
1288 memmap=nn[KMG]$ss[KMG]
1289 [KNL,ACPI] Mark specific memory as reserved.
1290 Region of memory to be used, from ss to ss+nn.
1291 Example: Exclude memory from 0x18690000-0x1869ffff
1292 memmap=64K$0x18690000
1294 memmap=0x10000$0x18690000
1296 memory_corruption_check=0/1 [X86]
1297 Some BIOSes seem to corrupt the first 64k of
1298 memory when doing things like suspend/resume.
1299 Setting this option will scan the memory
1300 looking for corruption. Enabling this will
1301 both detect corruption and prevent the kernel
1302 from using the memory being corrupted.
1303 However, its intended as a diagnostic tool; if
1304 repeatable BIOS-originated corruption always
1305 affects the same memory, you can use memmap=
1306 to prevent the kernel from using that memory.
1308 memory_corruption_check_size=size [X86]
1309 By default it checks for corruption in the low
1310 64k, making this memory unavailable for normal
1311 use. Use this parameter to scan for
1312 corruption in more or less memory.
1314 memory_corruption_check_period=seconds [X86]
1315 By default it checks for corruption every 60
1316 seconds. Use this parameter to check at some
1317 other rate. 0 disables periodic checking.
1319 memtest= [KNL,X86] Enable memtest
1321 range: 0,4 : pattern number
1322 default : 0 <disable>
1324 meye.*= [HW] Set MotionEye Camera parameters
1325 See Documentation/video4linux/meye.txt.
1327 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1328 Multi-Function General Purpose Timers on AMD Geode
1331 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1332 the BIOS has incorrectly applied a workaround. TinyBIOS
1333 version 0.98 is known to be affected, 0.99 fixes the
1334 problem by letting the user disable the workaround.
1338 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1339 physical address is ignored.
1342 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1343 parameter allows control of the logging verbosity for
1344 the additional memory initialisation checks. A value
1345 of 0 disables mminit logging and a level of 4 will
1346 log everything. Information is printed at KERN_DEBUG
1347 so loglevel=8 may also need to be specified.
1350 [MOUSE] Maximum time between finger touching and
1351 leaving touchpad surface for touch to be considered
1352 a tap and be reported as a left button click (for
1353 touchpads working in absolute mode only).
1355 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1356 reporting absolute coordinates, such as tablets
1357 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1358 reporting absolute coordinates, such as tablets
1363 MTD_Partition= [MTD]
1364 Format: <name>,<region-number>,<size>,<offset>
1366 MTD_Region= [MTD] Format:
1367 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1370 See drivers/mtd/cmdlinepart.c.
1373 ARM/S3C2412 JIVE boot control
1375 See arch/arm/mach-s3c2412/mach-jive.c
1377 mtouchusb.raw_coordinates=
1378 [HW] Make the MicroTouch USB driver use raw coordinates
1379 ('y', default) or cooked coordinates ('n')
1381 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1384 See header of drivers/scsi/NCR_D700.c.
1388 ncr53c400= [HW,SCSI]
1390 ncr53c400a= [HW,SCSI]
1392 ncr53c406a= [HW,SCSI]
1394 ncr53c8xx= [HW,SCSI]
1396 netdev= [NET] Network devices parameters
1397 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1398 Note that mem_start is often overloaded to mean
1399 something different and driver-specific.
1400 This usage is only documented in each driver source
1404 [NETFILTER] Enable connection tracking flow accounting
1405 0 to disable accounting
1406 1 to enable accounting
1407 Default value depends on CONFIG_NF_CT_ACCT that is
1408 going to be removed in 2.6.29.
1411 See Documentation/filesystems/nfsroot.txt.
1413 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1414 See Documentation/filesystems/nfsroot.txt.
1416 nfs.callback_tcpport=
1417 [NFS] set the TCP port on which the NFSv4 callback
1418 channel should listen.
1420 nfs.idmap_cache_timeout=
1421 [NFS] set the maximum lifetime for idmapper cache
1425 [NFS] enable 64-bit inode numbers.
1426 If zero, the NFS client will fake up a 32-bit inode
1427 number for the readdir() and stat() syscalls instead
1428 of returning the full 64-bit number.
1429 The default is to return 64-bit inode numbers.
1431 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1432 when a NMI is triggered.
1433 Format: [state][,regs][,debounce][,die]
1435 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1436 Format: [panic,][num]
1438 0 - turn nmi_watchdog off
1439 1 - use the IO-APIC timer for the NMI watchdog
1440 2 - use the local APIC for the NMI watchdog using
1441 a performance counter. Note: This will use one performance
1442 counter and the local APIC's performance vector.
1443 When panic is specified panic when an NMI watchdog timeout occurs.
1444 This is useful when you use a panic=... timeout and need the box
1446 Instead of 1 and 2 it is possible to use the following
1447 symbolic names: lapic and ioapic
1448 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1450 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1451 emulation library even if a 387 maths coprocessor
1454 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1455 caches in the slab allocator. Saves per-node memory,
1456 but will impact performance.
1460 noapic [SMP,APIC] Tells the kernel to not make use of any
1461 IOAPICs that may be present in the system.
1463 nobats [PPC] Do not use BATs for mapping kernel lowmem
1464 on "Classic" PPC cores.
1468 nodelayacct [KNL] Disable per-task delay accounting
1470 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1472 nodsp [SH] Disable hardware DSP at boot time.
1474 noefi [X86-32,X86-64] Disable EFI runtime services support.
1478 noexec [X86-32,X86-64]
1479 On X86-32 available only on PAE configured kernels.
1480 noexec=on: enable non-executable mappings (default)
1481 noexec=off: disable non-executable mappings
1484 This affects only 32-bit executables.
1485 noexec32=on: enable non-executable mappings (default)
1486 read doesn't imply executable mappings
1487 noexec32=off: disable non-executable mappings
1488 read implies executable mappings
1490 nofpu [SH] Disable hardware FPU at boot time.
1492 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1493 register save and restore. The kernel will only save
1494 legacy floating-point registers on task switch.
1496 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1500 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1501 instruction doesn't work correctly and not to
1504 no_file_caps Tells the kernel not to honor file capabilities. The
1505 only way then for a file to be executed with privilege
1506 is to be setuid root or executed by root.
1508 nohalt [IA-64] Tells the kernel not to use the power saving
1509 function PAL_HALT_LIGHT when idle. This increases
1510 power-consumption. On the positive side, it reduces
1511 interrupt wake-up latency, which may improve performance
1512 in certain environments such as networked servers or
1515 nohz= [KNL] Boottime enable/disable dynamic ticks
1516 Valid arguments: on, off
1519 noirqdebug [X86-32] Disables the code which attempts to detect and
1520 disable unhandled interrupt sources.
1522 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1523 broken timer IRQ sources.
1525 noisapnp [ISAPNP] Disables ISA PnP code.
1527 noinitrd [RAM] Tells the kernel not to load any configured
1532 nojitter [IA64] Disables jitter checking for ITC timers.
1534 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1536 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1538 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1540 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1541 default x2apic cluster mode on platforms
1544 noltlbs [PPC] Do not use large page/tlb entries for kernel
1545 lowmem mapping on PPC40x.
1547 nomca [IA-64] Disable machine check abort handling
1549 nomce [X86-32] Machine Check Exception
1551 nomfgpt [X86-32] Disable Multi-Function General Purpose
1552 Timer usage (for AMD Geode machines).
1554 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1556 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1557 with UP alternatives
1559 noresidual [PPC] Don't use residual data on PReP machines.
1561 noresume [SWSUSP] Disables resume and restores original swap
1564 no-scroll [VGA] Disables scrollback.
1565 This is required for the Braillex ib80-piezo Braille
1566 reader made by F.H. Papenmeier (Germany).
1570 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1572 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1573 and disable the IO APIC. legacy for "maxcpus=0".
1575 nosoftlockup [KNL] Disable the soft-lockup detector.
1577 noswapaccount [KNL] Disable accounting of swap in memory resource
1578 controller. (See Documentation/controllers/memory.txt)
1580 nosync [HW,M68K] Disables sync negotiation for all devices.
1582 notsc [BUGS=X86-32] Disable Time Stamp Counter
1584 nousb [USB] Disable the USB subsystem
1588 nptcg= [IA64] Override max number of concurrent global TLB
1589 purges which is reported from either PAL_VM_SUMMARY or
1592 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1593 one of ['zone', 'node', 'default'] can be specified
1594 This can be set from sysctl after boot.
1595 See Documentation/sysctl/vm.txt for details.
1597 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1599 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1600 See Documentation/debugging-via-ohci1394.txt for more
1603 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1604 Rather than timing out after 20 ms if an EC
1605 command is not properly ACKed, override the length
1606 of the timeout. We have interrupts disabled while
1607 waiting for the ACK, so if this is set too high
1608 interrupts *may* be lost!
1613 oprofile.timer= [HW]
1614 Use timer interrupt instead of performance counters
1616 osst= [HW,SCSI] SCSI Tape Driver
1617 Format: <buffer_size>,<write_threshold>
1618 See also Documentation/scsi/st.txt.
1620 panic= [KNL] Kernel behaviour on panic
1623 parkbd.port= [HW] Parallel port number the keyboard adapter is
1624 connected to, default is 0.
1626 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1627 0 for XT, 1 for AT (default is AT).
1630 parport= [HW,PPT] Specify parallel ports. 0 disables.
1631 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1632 Use 'auto' to force the driver to use any
1633 IRQ/DMA settings detected (the default is to
1634 ignore detected IRQ/DMA settings because of
1635 possible conflicts). You can specify the base
1636 address, IRQ, and DMA settings; IRQ and DMA
1637 should be numbers, or 'auto' (for using detected
1638 settings on that particular port), or 'nofifo'
1639 (to avoid using a FIFO even if it is detected).
1640 Parallel ports are assigned in the order they
1641 are specified on the command line, starting
1644 parport_init_mode= [HW,PPT]
1645 Configure VIA parallel port to operate in
1646 a specific mode. This is necessary on Pegasos
1647 computer where firmware has no options for setting
1648 up parallel port mode and sets it to spp.
1649 Currently this function knows 686a and 8231 chips.
1650 Format: [spp|ps2|epp|ecp|ecpepp]
1652 pas2= [HW,OSS] Format:
1653 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1656 See header of drivers/scsi/pas16.c.
1659 Halt all CPUs after the first oops has been printed for
1660 the specified number of seconds. This is to be used if
1661 your oopses keep scrolling off the screen.
1666 See header of drivers/block/paride/pcd.c.
1667 See also Documentation/blockdev/paride.txt.
1669 pci=option[,option...] [PCI] various PCI subsystem options:
1670 off [X86] don't probe for the PCI bus
1671 bios [X86-32] force use of PCI BIOS, don't access
1672 the hardware directly. Use this if your machine
1673 has a non-standard PCI host bridge.
1674 nobios [X86-32] disallow use of PCI BIOS, only direct
1675 hardware access methods are allowed. Use this
1676 if you experience crashes upon bootup and you
1677 suspect they are caused by the BIOS.
1678 conf1 [X86] Force use of PCI Configuration
1680 conf2 [X86] Force use of PCI Configuration
1682 noaer [PCIE] If the PCIEAER kernel config parameter is
1683 enabled, this kernel boot option can be used to
1684 disable the use of PCIE advanced error reporting.
1685 nodomains [PCI] Disable support for multiple PCI
1686 root domains (aka PCI segments, in ACPI-speak).
1687 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1689 nomsi [MSI] If the PCI_MSI kernel config parameter is
1690 enabled, this kernel boot option can be used to
1691 disable the use of MSI interrupts system-wide.
1692 noioapicquirk [APIC] Disable all boot interrupt quirks.
1693 Safety option to keep boot IRQs enabled. This
1694 should never be necessary.
1695 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1696 primary IO-APIC for bridges that cannot disable
1697 boot IRQs. This fixes a source of spurious IRQs
1698 when the system masks IRQs.
1699 noioapicreroute [APIC] Disable workaround that uses the
1700 boot IRQ equivalent of an IRQ that connects to
1701 a chipset where boot IRQs cannot be disabled.
1702 The opposite of ioapicreroute.
1703 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1704 routing table. These calls are known to be buggy
1705 on several machines and they hang the machine
1706 when used, but on other computers it's the only
1707 way to get the interrupt routing table. Try
1708 this option if the kernel is unable to allocate
1709 IRQs or discover secondary PCI buses on your
1711 rom [X86] Assign address space to expansion ROMs.
1712 Use with caution as certain devices share
1713 address decoders between ROMs and other
1715 norom [X86] Do not assign address space to
1716 expansion ROMs that do not already have
1717 BIOS assigned address ranges.
1718 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1719 assigned automatically to PCI devices. You can
1720 make the kernel exclude IRQs of your ISA cards
1722 pirqaddr=0xAAAAA [X86] Specify the physical address
1723 of the PIRQ table (normally generated
1724 by the BIOS) if it is outside the
1725 F0000h-100000h range.
1726 lastbus=N [X86] Scan all buses thru bus #N. Can be
1727 useful if the kernel is unable to find your
1728 secondary buses and you want to tell it
1729 explicitly which ones they are.
1730 assign-busses [X86] Always assign all PCI bus
1731 numbers ourselves, overriding
1732 whatever the firmware may have done.
1733 usepirqmask [X86] Honor the possible IRQ mask stored
1734 in the BIOS $PIR table. This is needed on
1735 some systems with broken BIOSes, notably
1736 some HP Pavilion N5400 and Omnibook XE3
1737 notebooks. This will have no effect if ACPI
1738 IRQ routing is enabled.
1739 noacpi [X86] Do not use ACPI for IRQ routing
1740 or for PCI scanning.
1741 use_crs [X86] Use _CRS for PCI resource
1743 routeirq Do IRQ routing for all PCI devices.
1744 This is normally done in pci_enable_device(),
1745 so this option is a temporary workaround
1746 for broken drivers that don't call it.
1747 skip_isa_align [X86] do not align io start addr, so can
1748 handle more pci cards
1749 firmware [ARM] Do not re-enumerate the bus but instead
1750 just use the configuration from the
1751 bootloader. This is currently used on
1752 IXP2000 systems where the bus has to be
1753 configured a certain way for adjunct CPUs.
1754 noearly [X86] Don't do any early type 1 scanning.
1755 This might help on some broken boards which
1756 machine check when some devices' config space
1757 is read. But various workarounds are disabled
1758 and some IOMMU drivers will not work.
1759 bfsort Sort PCI devices into breadth-first order.
1760 This sorting is done to get a device
1761 order compatible with older (<= 2.4) kernels.
1762 nobfsort Don't sort PCI devices into breadth-first order.
1763 cbiosize=nn[KMG] The fixed amount of bus space which is
1764 reserved for the CardBus bridge's IO window.
1765 The default value is 256 bytes.
1766 cbmemsize=nn[KMG] The fixed amount of bus space which is
1767 reserved for the CardBus bridge's memory
1768 window. The default value is 64 megabytes.
1770 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1773 force Enable ASPM even on devices that claim not to support it.
1774 WARNING: Forcing ASPM on may cause system lockups.
1776 pcmv= [HW,PCMCIA] BadgePAD 4
1779 See Documentation/blockdev/paride.txt.
1781 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1784 See arch/parisc/kernel/pdc_chassis.c
1787 See Documentation/blockdev/paride.txt.
1790 See Documentation/blockdev/paride.txt.
1792 pirq= [SMP,APIC] Manual mp-table setup
1793 See Documentation/x86/i386/IO-APIC.txt.
1795 plip= [PPT,NET] Parallel port network link
1796 Format: { parport<nr> | timid | 0 }
1797 See also Documentation/parport.txt.
1799 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1800 Override pmtimer IOPort with a hex value.
1804 Enable PNP debug messages. This depends on the
1805 CONFIG_PNP_DEBUG_MESSAGES option.
1811 { on | off | curr | res | no-curr | no-res }
1814 [ISAPNP] Exclude IRQs for the autoconfiguration
1817 [ISAPNP] Exclude DMAs for the autoconfiguration
1819 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1820 Ranges are in pairs (I/O port base and size).
1823 [ISAPNP] Exclude memory regions for the
1825 Ranges are in pairs (memory base and size).
1827 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1828 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1829 These can also be switched on/off via
1830 <debugfs>/dynamic_printk/modules
1832 print-fatal-signals=
1833 [KNL] debug: print fatal signals
1834 print-fatal-signals=1: print segfault info to
1838 printk.time= Show timing data prefixed to each printk message line
1839 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1841 profile= [KNL] Enable kernel profiling via /proc/profile
1842 Format: [schedule,]<number>
1843 Param: "schedule" - profile schedule points.
1844 Param: <number> - step/bucket size as a power of 2 for
1845 statistical time based profiling.
1846 Param: "sleep" - profile D-state sleeping (millisecs).
1847 Requires CONFIG_SCHEDSTATS
1848 Param: "kvm" - profile VM exits.
1850 processor.max_cstate= [HW,ACPI]
1851 Limit processor to maximum C-state
1852 max_cstate=9 overrides any DMI blacklist limit.
1854 processor.nocst [HW,ACPI]
1855 Ignore the _CST method to determine C-states,
1856 instead using the legacy FADT method
1858 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1860 See Documentation/blockdev/ramdisk.txt.
1862 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1863 probe for; one of (bare|imps|exps|lifebook|any).
1864 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1866 psmouse.resetafter= [HW,MOUSE]
1867 Try to reset the device after so many bad packets
1870 [HW,MOUSE] Set desired mouse resolution, in dpi.
1871 psmouse.smartscroll=
1872 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1873 0 = disabled, 1 = enabled (default).
1875 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1877 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1880 See Documentation/blockdev/paride.txt.
1883 [KNL] Number of legacy pty's. Overwrites compiled-in
1886 quiet [KNL] Disable most log messages
1891 See Documentation/md.txt.
1893 ramdisk_blocksize= [RAM]
1894 See Documentation/blockdev/ramdisk.txt.
1896 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1897 See Documentation/blockdev/ramdisk.txt.
1899 rcupdate.blimit= [KNL,BOOT]
1900 Set maximum number of finished RCU callbacks to process
1903 rcupdate.qhimark= [KNL,BOOT]
1904 Set threshold of queued
1905 RCU callbacks over which batch limiting is disabled.
1907 rcupdate.qlowmark= [KNL,BOOT]
1908 Set threshold of queued RCU callbacks below which
1909 batch limiting is re-enabled.
1913 Run specified binary instead of /init from the ramdisk,
1914 used for early userspace startup. See initrd.
1916 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1917 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1918 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1921 [KNL, SMP] Set scheduler's default relax_domain_level.
1922 See Documentation/cpusets.txt.
1924 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1926 reservetop= [X86-32]
1928 Reserves a hole at the top of the kernel virtual
1931 reset_devices [KNL] Force drivers to reset the underlying device
1932 during initialization.
1935 Specify the partition device for software suspend
1937 resume_offset= [SWSUSP]
1938 Specify the offset from the beginning of the partition
1939 given by "resume=" at which the swap header is located,
1940 in <PAGE_SIZE> units (needed only for swap files).
1941 See Documentation/power/swsusp-and-swap-files.txt
1943 retain_initrd [RAM] Keep initrd memory after extraction
1945 rhash_entries= [KNL,NET]
1946 Set number of hash buckets for route cache
1948 riscom8= [HW,SERIAL]
1949 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1951 ro [KNL] Mount root device read-only on boot
1953 root= [KNL] Root filesystem
1955 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1956 mount the root filesystem
1958 rootflags= [KNL] Set root filesystem mount option string
1960 rootfstype= [KNL] Set root filesystem type
1962 rootwait [KNL] Wait (indefinitely) for root device to show up.
1963 Useful for devices that are detected asynchronously
1964 (e.g. USB and MMC devices).
1966 root_plug.vendor_id=
1967 [ROOTPLUG] Override the default vendor ID
1969 root_plug.product_id=
1970 [ROOTPLUG] Override the default product ID
1973 [ROOTPLUG] Enable debugging output
1975 rw [KNL] Mount root device read-write on boot
1977 S [KNL] Run init in single mode
1980 See drivers/net/irda/sa1100_ir.c.
1982 sbni= [NET] Granch SBNI12 leased line adapter
1984 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1985 Format: <io>[,<timeout>[,<isapnp>]]
1987 scsi_debug_*= [SCSI]
1988 See drivers/scsi/scsi_debug.c.
1990 scsi_default_dev_flags=
1991 [SCSI] SCSI default device flags
1994 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1995 Format: <vendor>:<model>:<flags>
1996 (flags are integer value)
1998 scsi_logging_level= [SCSI] a bit mask of logging levels
1999 See drivers/scsi/scsi_logging.h for bits. Also
2000 settable via sysctl at dev.scsi.logging_level
2001 (/proc/sys/dev/scsi/logging_level).
2002 There is also a nice 'scsi_logging_level' script in the
2003 S390-tools package, available for download at
2004 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2006 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2007 discovered. async scans them in kernel threads,
2008 allowing boot to proceed. none ignores them, expecting
2009 user space to do the scan.
2011 selinux [SELINUX] Disable or enable SELinux at boot time.
2012 Format: { "0" | "1" }
2013 See security/selinux/Kconfig help text.
2016 Default value is set via kernel config option.
2017 If enabled at boot time, /selinux/disable can be used
2018 later to disable prior to initial policy load.
2020 selinux_compat_net =
2021 [SELINUX] Set initial selinux_compat_net flag value.
2022 Format: { "0" | "1" }
2023 0 -- use new secmark-based packet controls
2024 1 -- use legacy packet controls
2025 Default value is 0 (preferred).
2026 Value can be changed at runtime via
2027 /selinux/compat_net.
2029 serialnumber [BUGS=X86-32]
2032 Maximal number of shapers.
2034 show_msr= [x86] show boot-time MSR settings
2035 Format: { <integer> }
2036 Show boot-time (BIOS-initialized) MSR settings.
2037 The parameter means the number of CPUs to show,
2038 for example 1 means boot CPU only.
2041 See header of drivers/scsi/sim710.c.
2048 slub_debug[=options[,slabs]] [MM, SLUB]
2049 Enabling slub_debug allows one to determine the
2050 culprit if slab objects become corrupted. Enabling
2051 slub_debug can create guard zones around objects and
2052 may poison objects when not in use. Also tracks the
2053 last alloc / free. For more information see
2054 Documentation/vm/slub.txt.
2056 slub_max_order= [MM, SLUB]
2057 Determines the maximum allowed order for slabs.
2058 A high setting may cause OOMs due to memory
2059 fragmentation. For more information see
2060 Documentation/vm/slub.txt.
2062 slub_min_objects= [MM, SLUB]
2063 The minimum number of objects per slab. SLUB will
2064 increase the slab order up to slub_max_order to
2065 generate a sufficiently large slab able to contain
2066 the number of objects indicated. The higher the number
2067 of objects the smaller the overhead of tracking slabs
2068 and the less frequently locks need to be acquired.
2069 For more information see Documentation/vm/slub.txt.
2071 slub_min_order= [MM, SLUB]
2072 Determines the mininum page order for slabs. Must be
2073 lower than slub_max_order.
2074 For more information see Documentation/vm/slub.txt.
2076 slub_nomerge [MM, SLUB]
2077 Disable merging of slabs with similar size. May be
2078 necessary if there is some reason to distinguish
2079 allocs to different slabs. Debug options disable
2080 merging on their own.
2081 For more information see Documentation/vm/slub.txt.
2084 Format: <io1>[,<io2>[,...,<io8>]]
2086 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2087 attempt to substitute SMP alternatives once at boot.
2089 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2090 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2091 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2092 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2093 smsc-ircc2.ircc_irq= [HW] IRQ line
2094 smsc-ircc2.ircc_dma= [HW] DMA channel
2095 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2096 0: Toshiba Satellite 1800 (GP data pin select)
2097 1: Fast pin select (default)
2100 snd-ad1816a= [HW,ALSA]
2102 snd-ad1848= [HW,ALSA]
2104 snd-ali5451= [HW,ALSA]
2106 snd-als100= [HW,ALSA]
2108 snd-als4000= [HW,ALSA]
2110 snd-azt2320= [HW,ALSA]
2112 snd-cmi8330= [HW,ALSA]
2114 snd-cmipci= [HW,ALSA]
2116 snd-cs4231= [HW,ALSA]
2118 snd-cs4232= [HW,ALSA]
2120 snd-cs4236= [HW,ALSA]
2122 snd-cs4281= [HW,ALSA]
2124 snd-cs46xx= [HW,ALSA]
2126 snd-dt019x= [HW,ALSA]
2128 snd-dummy= [HW,ALSA]
2130 snd-emu10k1= [HW,ALSA]
2132 snd-ens1370= [HW,ALSA]
2134 snd-ens1371= [HW,ALSA]
2136 snd-es968= [HW,ALSA]
2138 snd-es1688= [HW,ALSA]
2140 snd-es18xx= [HW,ALSA]
2142 snd-es1938= [HW,ALSA]
2144 snd-es1968= [HW,ALSA]
2146 snd-fm801= [HW,ALSA]
2148 snd-gusclassic= [HW,ALSA]
2150 snd-gusextreme= [HW,ALSA]
2152 snd-gusmax= [HW,ALSA]
2156 snd-ice1712= [HW,ALSA]
2158 snd-intel8x0= [HW,ALSA]
2160 snd-interwave= [HW,ALSA]
2165 snd-korg1212= [HW,ALSA]
2167 snd-maestro3= [HW,ALSA]
2169 snd-mpu401= [HW,ALSA]
2171 snd-mtpav= [HW,ALSA]
2173 snd-nm256= [HW,ALSA]
2175 snd-opl3sa2= [HW,ALSA]
2183 snd-opti93x= [HW,ALSA]
2187 snd-rme32= [HW,ALSA]
2189 snd-rme96= [HW,ALSA]
2191 snd-rme9652= [HW,ALSA]
2197 snd-sbawe= [HW,ALSA]
2199 snd-serial= [HW,ALSA]
2201 snd-sgalaxy= [HW,ALSA]
2203 snd-sonicvibes= [HW,ALSA]
2208 snd-sun-cs4231= [HW,ALSA]
2210 snd-trident= [HW,ALSA]
2212 snd-usb-audio= [HW,ALSA,USB]
2214 snd-via82xx= [HW,ALSA]
2216 snd-virmidi= [HW,ALSA]
2218 snd-wavefront= [HW,ALSA]
2220 snd-ymfpci= [HW,ALSA]
2223 [KNL] Should the soft-lockup detector generate panics.
2225 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2226 See Documentation/sonypi.txt
2228 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2229 See Documentation/serial/specialix.txt.
2231 spia_io_base= [HW,MTD]
2237 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2239 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2240 See Documentation/scsi/st.txt.
2243 Enabled the stack tracer on boot up.
2247 Set the STI (builtin display/keyboard on the HP-PARISC
2248 machines) console (graphic card) which should be used
2249 as the initial boot-console.
2250 See also comment in drivers/video/console/sticore.c.
2253 See comment in drivers/video/console/sticore.c.
2256 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2260 Control how the NFS server code allocates CPUs to
2261 service thread pools. Depending on how many NICs
2262 you have and where their interrupts are bound, this
2263 option will affect which CPUs will do NFS serving.
2264 Note: this parameter cannot be changed while the
2265 NFS server is running.
2267 auto the server chooses an appropriate mode
2268 automatically using heuristics
2269 global a single global pool contains all CPUs
2270 percpu one pool for each CPU
2271 pernode one pool for each NUMA node (equivalent
2272 to global on non-NUMA machines)
2274 swiotlb= [IA-64] Number of I/O TLB slabs
2278 sym53c416= [HW,SCSI]
2279 See header of drivers/scsi/sym53c416.c.
2281 sysrq_always_enabled
2283 Ignore sysrq setting - this boot parameter will
2284 neutralize any effect of /proc/sys/kernel/sysrq.
2285 Useful for debugging.
2288 See header of drivers/scsi/t128.c.
2292 test_suspend= [SUSPEND]
2293 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2294 standby suspend) as the system sleep state to briefly
2295 enter during system startup. The system is woken from
2296 this state using a wakeup-capable RTC alarm.
2298 thash_entries= [KNL,NET]
2299 Set number of hash buckets for TCP connection
2301 thermal.act= [HW,ACPI]
2302 -1: disable all active trip points in all thermal zones
2303 <degrees C>: override all lowest active trip points
2305 thermal.crt= [HW,ACPI]
2306 -1: disable all critical trip points in all thermal zones
2307 <degrees C>: override all critical trip points
2309 thermal.nocrt= [HW,ACPI]
2310 Set to disable actions on ACPI thermal zone
2311 critical and hot trip points.
2313 thermal.off= [HW,ACPI]
2314 1: disable ACPI thermal control
2316 thermal.psv= [HW,ACPI]
2317 -1: disable all passive trip points
2318 <degrees C>: override all passive trip points to this
2321 thermal.tzp= [HW,ACPI]
2322 Specify global default ACPI thermal zone polling rate
2323 <deci-seconds>: poll all this frequency
2324 0: no polling (default)
2327 See comment before function dc390_setup() in
2328 drivers/scsi/tmscsim.c.
2332 Specify if the kernel should make use of the cpu
2333 topology informations if the hardware supports these.
2334 The scheduler will make use of these informations and
2335 e.g. base its process migration decisions on it.
2340 trix= [HW,OSS] MediaTrix AudioTrix Pro
2342 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2344 tsc= Disable clocksource-must-verify flag for TSC.
2346 [x86] reliable: mark tsc clocksource as reliable, this
2347 disables clocksource verification at runtime.
2348 Used to enable high-resolution timer mode on older
2349 hardware, and in virtualized environment.
2351 turbografx.map[2|3]= [HW,JOY]
2352 TurboGraFX parallel port interface
2354 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2355 See also Documentation/input/joystick-parport.txt
2357 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2358 See header of drivers/scsi/u14-34f.c.
2367 [USB] Ignore overcurrent events (default N).
2368 Some badly-designed motherboards generate lots of
2369 bogus events, for ports that aren't wired to
2370 anything. Set this parameter to avoid log spamming.
2371 Note that genuine overcurrent events won't be
2376 Set unknown_nmi_panic=1 early on boot.
2378 usbcore.autosuspend=
2379 [USB] The autosuspend time delay (in seconds) used
2380 for newly-detected USB devices (default 2). This
2381 is the time required before an idle device will be
2382 autosuspended. Devices for which the delay is set
2383 to a negative value won't be autosuspended at all.
2385 usbcore.usbfs_snoop=
2386 [USB] Set to log all usbfs traffic (default 0 = off).
2388 usbcore.blinkenlights=
2389 [USB] Set to cycle leds on hubs (default 0 = off).
2391 usbcore.old_scheme_first=
2392 [USB] Start with the old device initialization
2393 scheme (default 0 = off).
2395 usbcore.use_both_schemes=
2396 [USB] Try the other device initialization scheme
2397 if the first one fails (default 1 = enabled).
2399 usbcore.initial_descriptor_timeout=
2400 [USB] Specifies timeout for the initial 64-byte
2401 USB_REQ_GET_DESCRIPTOR request in milliseconds
2402 (default 5000 = 5.0 seconds).
2405 [USBHID] The interval which mice are to be polled at.
2407 usb-storage.delay_use=
2408 [UMS] The delay in seconds before a new device is
2409 scanned for Logical Units (default 5).
2412 [UMS] A list of quirks entries to supplement or
2413 override the built-in unusual_devs list. List
2414 entries are separated by commas. Each entry has
2415 the form VID:PID:Flags where VID and PID are Vendor
2416 and Product ID values (4-digit hex numbers) and
2417 Flags is a set of characters, each corresponding
2418 to a common usb-storage quirk flag as follows:
2419 a = SANE_SENSE (collect more than 18 bytes
2421 c = FIX_CAPACITY (decrease the reported
2422 device capacity by one sector);
2423 h = CAPACITY_HEURISTICS (decrease the
2424 reported device capacity by one
2425 sector if the number is odd);
2426 i = IGNORE_DEVICE (don't bind to this
2428 l = NOT_LOCKABLE (don't try to lock and
2429 unlock ejectable media);
2430 m = MAX_SECTORS_64 (don't transfer more
2431 than 64 sectors = 32 KB at a time);
2432 o = CAPACITY_OK (accept the capacity
2433 reported by the device);
2434 r = IGNORE_RESIDUE (the device reports
2435 bogus residue values);
2436 s = SINGLE_LUN (the device has only one
2438 w = NO_WP_DETECT (don't test whether the
2439 medium is write-protected).
2440 Example: quirks=0419:aaf5:rl,0421:0433:rc
2442 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2443 kernel's map of available physical RAM.
2445 vdso= [X86-32,SH,x86-64]
2446 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2447 vdso=1: enable VDSO (default)
2448 vdso=0: disable VDSO mapping
2450 vdso32= [X86-32,X86-64]
2451 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2452 vdso32=1: enable 32-bit VDSO (default)
2453 vdso32=0: disable 32-bit VDSO mapping
2456 vector=percpu: enable percpu vector domain
2458 video= [FB] Frame buffer configuration
2459 See Documentation/fb/modedb.txt.
2461 vga= [BOOT,X86-32] Select a particular video mode
2462 See Documentation/x86/i386/boot.txt and
2463 Documentation/svga.txt.
2464 Use vga=ask for menu.
2465 This is actually a boot loader parameter; the value is
2466 passed to the kernel using a special protocol.
2468 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2469 size of <nn>. This can be used to increase the
2470 minimum size (128MB on x86). It can also be used to
2471 decrease the size and leave more room for directly
2474 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2477 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2480 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2483 waveartist= [HW,OSS]
2484 Format: <io>,<irq>,<dma>,<dma2>
2487 See header of drivers/scsi/wd33c93.c.
2490 See header of drivers/scsi/wd7000.c.
2493 See Documentation/watchdog/wdt.txt.
2495 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2496 xd_geo= See header of drivers/block/xd.c.
2498 xirc2ps_cs= [NET,PCMCIA]
2500 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2502 norandmaps Don't use address space randomization. Equivalent to
2503 echo 0 > /proc/sys/kernel/randomize_va_space
2505 ______________________________________________________________________
2509 Add documentation for ALSA options.
2510 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob