4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IMA Integrity measurement architecture is enabled.
48 IOSCHED More than one I/O scheduler is enabled.
49 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
50 ISAPNP ISA PnP code is enabled.
51 ISDN Appropriate ISDN support is enabled.
52 JOY Appropriate joystick support is enabled.
53 LIBATA Libata driver is enabled
54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
62 MSI Message Signaled Interrupts (PCI).
63 MTD MTD (Memory Technology Device) support is enabled.
64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
66 GENERIC_TIME The generic timeofday code is enabled.
67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
73 PCIE PCI Express support is enabled.
74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
80 ROOTPLUG The example Root Plug LSM is enabled.
81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
85 SECURITY Different security models are enabled.
86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
88 SH SuperH architecture is enabled.
89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
91 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are enabled.
93 FTRACE Function tracing enabled.
94 TS Appropriate touchscreen support is enabled.
95 UMS USB Mass Storage support is enabled.
96 USB USB support is enabled.
97 USBHID USB Human Interface Device support is enabled.
98 V4L Video For Linux support is enabled.
99 VGA The VGA console has been enabled.
100 VT Virtual terminal support is enabled.
101 WDT Watchdog support is enabled.
102 XT IBM PC/XT MFM hard disk support is enabled.
103 X86-32 X86-32, aka i386 architecture is enabled.
104 X86-64 X86-64 architecture is enabled.
105 More X86-64 boot options can be found in
106 Documentation/x86/x86_64/boot-options.txt .
107 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
109 In addition, the following text indicates that the option:
111 BUGS= Relates to possible processor bugs on the said processor.
112 KNL Is a kernel start-up parameter.
113 BOOT Is a boot loader parameter.
115 Parameters denoted with BOOT are actually interpreted by the boot
116 loader, and have no meaning to the kernel directly.
117 Do not modify the syntax of boot loader parameters without extreme
118 need or coordination with <Documentation/x86/boot.txt>.
120 There are also arch-specific kernel-parameters not documented here.
121 See for example <Documentation/x86/x86_64/boot-options.txt>.
123 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
124 a trailing = on the name of any parameter states that that parameter will
125 be entered as an environment variable, whereas its absence indicates that
126 it will appear as a kernel argument readable via /proc/cmdline by programs
127 running once the system is up.
129 The number of kernel parameters is not limited, but the length of the
130 complete command line (parameters including spaces etc.) is limited to
131 a fixed number of characters. This limit depends on the architecture
132 and is between 256 and 4096 characters. It is defined in the file
133 ./include/asm/setup.h as COMMAND_LINE_SIZE.
136 acpi= [HW,ACPI,X86-64,i386]
137 Advanced Configuration and Power Interface
138 Format: { force | off | ht | strict | noirq | rsdt }
139 force -- enable ACPI if default was off
140 off -- disable ACPI if default was on
141 noirq -- do not use ACPI for IRQ routing
142 ht -- run only enough ACPI to enable Hyper Threading
143 strict -- Be less tolerant of platforms that are not
144 strictly ACPI specification compliant.
145 rsdt -- prefer RSDT over (default) XSDT
147 See also Documentation/power/pm.txt, pci=noacpi
149 acpi_apic_instance= [ACPI, IOAPIC]
151 2: use 2nd APIC table, if available
152 1,0: use 1st APIC table
155 acpi_sleep= [HW,ACPI] Sleep options
156 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
157 old_ordering, s4_nonvs }
158 See Documentation/power/video.txt for information on
160 s3_beep is for debugging; it makes the PC's speaker beep
161 as soon as the kernel's real-mode entry point is called.
162 s4_nohwsig prevents ACPI hardware signature from being
163 used during resume from hibernation.
164 old_ordering causes the ACPI 1.0 ordering of the _PTS
165 control method, with respect to putting devices into
166 low power states, to be enforced (the ACPI 2.0 ordering
167 of _PTS is used by default).
168 s4_nonvs prevents the kernel from saving/restoring the
169 ACPI NVS memory during hibernation.
171 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
172 Format: { level | edge | high | low }
174 acpi_irq_balance [HW,ACPI]
175 ACPI will balance active IRQs
178 acpi_irq_nobalance [HW,ACPI]
179 ACPI will not move active IRQs (default)
182 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
184 Format: <irq>,<irq>...
186 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
187 Format: <irq>,<irq>...
189 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
191 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
192 Format: To spoof as Windows 98: ="Microsoft Windows"
194 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
195 acpi_osi="string1" # add string1 -- only one string
196 acpi_osi="!string2" # remove built-in string2
197 acpi_osi= # disable all strings
199 acpi_serialize [HW,ACPI] force serialization of AML methods
201 acpi_skip_timer_override [HW,ACPI]
202 Recognize and ignore IRQ0/pin2 Interrupt Override.
203 For broken nForce2 BIOS resulting in XT-PIC timer.
204 acpi_use_timer_override [HW,ACPI]
205 Use timer override. For some broken Nvidia NF5 boards
206 that require a timer override, but don't have
209 acpi_backlight= [HW,ACPI]
210 acpi_backlight=vendor
212 If set to vendor, prefer vendor specific driver
213 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
214 of the ACPI video.ko driver.
216 acpi_display_output= [HW,ACPI]
217 acpi_display_output=vendor
218 acpi_display_output=video
221 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
222 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
224 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
225 debug output. Bits in debug_layer correspond to a
226 _COMPONENT in an ACPI source file, e.g.,
227 #define _COMPONENT ACPI_PCI_COMPONENT
228 Bits in debug_level correspond to a level in
229 ACPI_DEBUG_PRINT statements, e.g.,
230 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
231 The debug_level mask defaults to "info". See
232 Documentation/acpi/debug.txt for more information about
233 debug layers and levels.
235 Enable processor driver info messages:
236 acpi.debug_layer=0x20000000
237 Enable PCI/PCI interrupt routing info messages:
238 acpi.debug_layer=0x400000
239 Enable AML "Debug" output, i.e., stores to the Debug
240 object while interpreting AML:
241 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
242 Enable all messages related to ACPI hardware:
243 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
245 Some values produce so much output that the system is
246 unusable. The "log_buf_len" parameter may be useful
247 if you need to capture more output.
249 acpi.power_nocheck= [HW,ACPI]
250 Format: 1/0 enable/disable the check of power state.
251 On some bogus BIOS the _PSC object/_STA object of
252 power resource can't return the correct device power
253 state. In such case it is unneccessary to check its
254 power state again in power transition.
255 1 : disable the power state check
257 acpi_pm_good [X86-32,X86-64]
258 Override the pmtimer bug detection: force the kernel
259 to assume that this machine's pmtimer latches its value
260 and always returns good values.
263 { off | try_unsupported }
264 off: disable AGP support
265 try_unsupported: try to drive unsupported chipsets
266 (may crash computer or cause data corruption)
268 enable_timer_pin_1 [i386,x86-64]
269 Enable PIN 1 of APIC timer
270 Can be useful to work around chipset bugs
271 (in particular on some ATI chipsets).
272 The kernel tries to set a reasonable default.
274 disable_timer_pin_1 [i386,x86-64]
275 Disable PIN 1 of APIC timer
276 Can be useful to work around chipset bugs.
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
282 See header of drivers/scsi/advansys.c.
284 advwdt= [HW,WDT] Advantech WDT
285 Format: <iostart>,<iostop>
287 aedsp16= [HW,OSS] Audio Excel DSP 16
288 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
289 See also header of sound/oss/aedsp16.c.
292 See Documentation/scsi/aha152x.txt.
295 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
298 See Documentation/scsi/aic7xxx.txt.
301 See Documentation/scsi/aic79xx.txt.
303 amd_iommu= [HW,X86-84]
304 Pass parameters to the AMD IOMMU driver in the system.
306 isolate - enable device isolation (each device, as far
307 as possible, will get its own protection
309 share - put every device behind one IOMMU into the
310 same protection domain
311 fullflush - enable flushing of IO/TLB entries when
312 they are unmapped. Otherwise they are
313 flushed before they will be reused, which
316 amd_iommu_size= [HW,X86-64]
317 Define the size of the aperture for the AMD IOMMU
318 driver. Possible values are:
319 '32M', '64M' (default), '128M', '256M', '512M', '1G'
321 amijoy.map= [HW,JOY] Amiga joystick support
322 Map of devices attached to JOY0DAT and JOY1DAT
324 See also Documentation/kernel/input/joystick.txt
326 analog.map= [HW,JOY] Analog joystick and gamepad support
327 Specifies type or capabilities of an analog joystick
328 connected to one of 16 gameports
329 Format: <type1>,<type2>,..<type16>
332 Power management functions (SPARCstation-4/5 + deriv.)
334 Disable APC CPU standby support. SPARCstation-Fox does
335 not play well with APC CPU idle - disable it if you have
336 APC and your system crashes randomly.
338 apic= [APIC,i386] Advanced Programmable Interrupt Controller
339 Change the output verbosity whilst booting
340 Format: { quiet (default) | verbose | debug }
341 Change the amount of debugging information output
342 when initialising the APIC and IO-APIC components.
344 apm= [APM] Advanced Power Management
345 See header of arch/x86/kernel/apm_32.c.
347 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
348 Format: <io>,<irq>,<nodeID>
352 atarimouse= [HW,MOUSE] Atari Mouse
354 atascsi= [HW,SCSI] Atari SCSI
356 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
357 EzKey and similar keyboards
359 atkbd.reset= [HW] Reset keyboard during initialization
361 atkbd.set= [HW] Select keyboard code set
362 Format: <int> (2 = AT (default), 3 = PS/2)
364 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
367 atkbd.softraw= [HW] Choose between synthetic and real raw mode
368 Format: <bool> (0 = real, 1 = synthetic (default))
370 atkbd.softrepeat= [HW]
371 Use software keyboard repeat
375 baycom_epp= [HW,AX25]
378 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
380 See header of drivers/net/hamradio/baycom_par.c.
382 baycom_ser_fdx= [HW,AX25]
383 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
384 Format: <io>,<irq>,<mode>[,<baud>]
385 See header of drivers/net/hamradio/baycom_ser_fdx.c.
387 baycom_ser_hdx= [HW,AX25]
388 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
389 Format: <io>,<irq>,<mode>
390 See header of drivers/net/hamradio/baycom_ser_hdx.c.
392 boot_delay= Milliseconds to delay each printk during boot.
393 Values larger than 10 seconds (10000) are changed to
397 bootmem_debug [KNL] Enable bootmem allocator debug messages.
399 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
400 bttv.radio= Most important insmod options are available as
402 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
403 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
406 See drivers/scsi/BusLogic.c, comment before function
407 BusLogic_ParseDriverOptions().
409 c101= [NET] Moxa C101 synchronous serial card
411 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
412 Sometimes CPU hardware bugs make them report the cache
413 size incorrectly. The kernel will attempt work arounds
414 to fix known problems, but for some CPUs it is not
415 possible to determine what the correct size should be.
416 This option provides an override for these situations.
418 security= [SECURITY] Choose a security module to enable at boot.
419 If this boot parameter is not specified, only the first
420 security module asking for security registration will be
421 loaded. An invalid security module name will be treated
422 as if no module has been chosen.
425 [SECURITY] Disable capabilities. This would normally
426 be used only if an alternative security model is to be
427 configured. Potentially dangerous and should only be
428 used if you are entirely sure of the consequences.
430 ccw_timeout_log [S390]
431 See Documentation/s390/CommonIO for details.
433 cgroup_disable= [KNL] Disable a particular controller
434 Format: {name of the controller(s) to disable}
435 {Currently supported controllers - "memory"}
437 checkreqprot [SELINUX] Set initial checkreqprot flag value.
438 Format: { "0" | "1" }
439 See security/selinux/Kconfig help text.
440 0 -- check protection applied by kernel (includes
441 any implied execute protection).
442 1 -- check protection requested by application.
443 Default value is set via a kernel config option.
444 Value can be changed at runtime via
445 /selinux/checkreqprot.
448 See Documentation/s390/CommonIO for details.
450 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
452 Forces specified clocksource (if available) to be used
453 when calculating gettimeofday(). If specified
454 clocksource is not available, it defaults to PIT.
455 Format: { pit | tsc | cyclone | pmtmr }
457 clocksource= [GENERIC_TIME] Override the default clocksource
459 Override the default clocksource and use the clocksource
460 with the name specified.
461 Some clocksource names to choose from, depending on
463 [all] jiffies (this is the base, fallback clocksource)
465 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
466 pxa_timer,timer3,32k_counter,timer0_1
468 [X86-32] pit,hpet,tsc,vmi-timer;
469 scx200_hrt on Geode; cyclone on IBM x440
477 clearcpuid=BITNUM [X86]
478 Disable CPUID feature X for the kernel. See
479 arch/x86/include/asm/cpufeature.h for the valid bit
480 numbers. Note the Linux specific bits are not necessarily
481 stable over kernel options, but the vendor specific
483 Also note that user programs calling CPUID directly
484 or using the feature without checking anything
485 will still see it. This just prevents it from
486 being used by the kernel or shown in /proc/cpuinfo.
487 Also note the kernel might malfunction if you disable
490 code_bytes [IA32/X86_64] How many bytes of object code to print
495 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
496 this option disables the debugging code at boot.
498 dma_debug_entries=<number>
499 This option allows to tune the number of preallocated
500 entries for DMA-API debugging code. One entry is
501 required per DMA-API allocation. Use this if the
502 DMA-API debugging code disables itself because the
503 architectural default is too low.
505 hpet= [X86-32,HPET] option to control HPET usage
506 Format: { enable (default) | disable | force |
508 disable: disable HPET and use PIT instead
509 force: allow force enabled of undocumented chips (ICH4,
511 verbose: show contents of HPET registers during setup
513 com20020= [HW,NET] ARCnet - COM20020 chipset
515 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
517 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
521 ARCnet - COM90xx chipset (memory-mapped buffers)
522 Format: <io>[,<irq>[,<memstart>]]
524 condev= [HW,S390] console device
527 console= [KNL] Output console device and options.
529 tty<n> Use the virtual console device <n>.
533 Use the specified serial port. The options are of
534 the form "bbbbpnf", where "bbbb" is the baud rate,
535 "p" is parity ("n", "o", or "e"), "n" is number of
536 bits, and "f" is flow control ("r" for RTS or
537 omit it). Default is "9600n8".
539 See Documentation/serial-console.txt for more
541 Documentation/networking/netconsole.txt for an
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 switching to the matching ttyS device later. The
549 options are the same as for ttyS, above.
551 If the device connected to the port is not a TTY but a braille
552 device, prepend "brl," before the device type, for instance
554 For now, only VisioBraille is supported.
556 earlycon= [KNL] Output early console device and options.
557 uart[8250],io,<addr>[,options]
558 uart[8250],mmio,<addr>[,options]
559 Start an early, polled-mode console on the 8250/16550
560 UART at the specified I/O port or MMIO address.
561 The options are the same as for ttyS, above.
564 [HW] Never suspend the console
565 Disable suspending of consoles during suspend and
566 hibernate operations. Once disabled, debugging
567 messages can reach various consoles while the rest
568 of the system is being put to sleep (ie, while
569 debugging driver suspend/resume hooks). This may
570 not work reliably with all consoles, but is known
571 to work with serial and VGA consoles.
574 [KNL] Change the default value for
575 /proc/<pid>/coredump_filter.
576 See also Documentation/filesystems/proc.txt.
578 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
580 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
582 crashkernel=nn[KMG]@ss[KMG]
583 [KNL] Reserve a chunk of physical memory to
584 hold a kernel to switch to with kexec on panic.
586 crashkernel=range1:size1[,range2:size2,...][@offset]
587 [KNL] Same as above, but depends on the memory
588 in the running system. The syntax of range is
589 start-[end] where start and end are both
590 a memory unit (amount[KMG]). See also
591 Documentation/kdump/kdump.txt for a example.
596 cs89x0_media= [HW,NET]
597 Format: { rj45 | aui | bnc }
600 See header of drivers/s390/block/dasd_devmap.c.
602 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
603 (one device per port)
604 Format: <port#>,<type>
605 See also Documentation/input/joystick-parport.txt
607 debug [KNL] Enable kernel debugging (events log level).
610 [KNL] verbose self-tests
612 Print debugging info while doing the locking API
614 We default to 0 (no extra messages), setting it to
615 1 will print _a lot_ more information - normally
616 only useful to kernel developers.
618 debug_objects [KNL] Enable object debugging
621 [KNL] Disable object debugging
623 debugpat [X86] Enable PAT debugging
625 decnet.addr= [HW,NET]
626 Format: <area>[,<node>]
627 See also Documentation/networking/decnet.txt.
630 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
631 Change the default blue palette of the console.
632 This is a 16-member array composed of values
636 Format: <green0>,<green1>,<green2>,...,<green15>
637 Change the default green palette of the console.
638 This is a 16-member array composed of values
642 Format: <red0>,<red1>,<red2>,...,<red15>
643 Change the default red palette of the console.
644 This is a 16-member array composed of values
650 Set system-wide default UTF-8 mode for all tty's.
651 Default is 1, i.e. UTF-8 mode is enabled for all
652 newly opened terminals.
655 Set number of hash buckets for dentry cache.
658 IO parameters + enable/disable command.
660 digiepca= [HW,SERIAL]
661 See drivers/char/README.epca and
662 Documentation/serial/digiepca.txt.
664 disable_mtrr_cleanup [X86]
665 enable_mtrr_cleanup [X86]
666 The kernel tries to adjust MTRR layout from continuous
667 to discrete, to make X server driver able to add WB
668 entry later. This parameter enables/disables that.
670 mtrr_chunk_size=nn[KMG] [X86]
671 used for mtrr cleanup. It is largest continous chunk
672 that could hold holes aka. UC entries.
674 mtrr_gran_size=nn[KMG] [X86]
675 Used for mtrr cleanup. It is granularity of mtrr block.
677 Large value could prevent small alignment from
680 mtrr_spare_reg_nr=n [X86]
682 Range: 0,7 : spare reg number
684 Used for mtrr cleanup. It is spare mtrr entries number.
685 Set to 2 or more if your graphical card needs more.
687 disable_mtrr_trim [X86, Intel and AMD only]
688 By default the kernel will trim any uncacheable
689 memory out of your available memory pool based on
690 MTRR settings. This parameter disables that behavior,
691 possibly causing your machine to run very slowly.
693 dmasound= [HW,OSS] Sound subsystem buffers
699 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
701 earlyprintk=serial[,ttySn[,baudrate]]
704 Append ",keep" to not disable it when the real console
707 Only vga or serial or usb debug port at a time.
709 Currently only ttyS0 and ttyS1 are supported.
711 Interaction with the standard serial driver is not
714 The VGA output is eventually overwritten by the real
720 Format: {"off" | "on" | "skip[mbr]"}
722 eisa_irq_edge= [PARISC,HW]
723 See header of drivers/parisc/eisa.c.
726 See comment before function elanfreq_setup() in
727 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
730 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
731 See Documentation/block/as-iosched.txt and
732 Documentation/block/deadline-iosched.txt for details.
734 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
735 Specifies physical address of start of kernel core
736 image elf header. Generally kexec loader will
737 pass this option to capture kernel.
738 See Documentation/kdump/kdump.txt for details.
740 enforcing [SELINUX] Set initial enforcing status.
742 See security/selinux/Kconfig help text.
743 0 -- permissive (log only, no denials).
744 1 -- enforcing (deny and log).
746 Value can be changed at runtime via /selinux/enforce.
748 ether= [HW,NET] Ethernet cards parameters
749 This option is obsoleted by the "netdev=" option, which
750 has equivalent usage. See its documentation for details.
752 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
757 fail_make_request=[KNL]
758 General fault injection mechanism.
759 Format: <interval>,<probability>,<space>,<times>
760 See also /Documentation/fault-injection/.
763 See header of drivers/scsi/fd_mcs.c.
766 See header of drivers/scsi/fdomain.c.
769 See Documentation/blockdev/floppy.txt.
771 force_pal_cache_flush
772 [IA-64] Avoid check_sal_cache_flush which may hang on
773 buggy SAL_CACHE_FLUSH implementations. Using this
774 parameter will force ia64_sal_cache_flush to call
775 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
778 [ftrace] will set and start the specified tracer
779 as early as possible in order to facilitate early
783 [ftrace] will dump the trace buffers on oops.
786 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
787 support via parallel port (up to 5 devices per port)
788 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
789 See also Documentation/input/joystick-parport.txt
793 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
798 See header of drivers/scsi/gdth.c.
800 gpt [EFI] Forces disk with valid GPT signature but
801 invalid Protective MBR to be treated as GPT.
805 hashdist= [KNL,NUMA] Large hashes allocated during boot
806 are distributed across NUMA nodes. Defaults on
807 for IA-64, off otherwise.
808 Format: 0 | 1 (for off | on)
810 hcl= [IA-64] SGI's Hardware Graph compatibility layer
812 hd= [EIDE] (E)IDE hard drive subsystem geometry
813 Format: <cyl>,<head>,<sect>
815 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
816 size of <nn>. This works even on boxes that have no
817 highmem otherwise. This also works to reduce highmem
818 size on bigger boxes.
820 highres= [KNL] Enable/disable high resolution timer mode.
821 Valid parameters: "on", "off"
825 See Documentation/isdn/README.HiSax.
827 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
828 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
829 On x86-64 and powerpc, this option can be specified
830 multiple times interleaved with hugepages= to reserve
831 huge pages of different sizes. Valid pages sizes on
832 x86-64 are 2M (when the CPU supports "pse") and 1G
833 (when the CPU supports the "pdpe1gb" cpuinfo flag)
834 Note that 1GB pages can only be allocated at boot time
835 using hugepages= and not freed afterwards.
837 [same as hugepagesz=] The size of the default
838 HugeTLB page size. This is the size represented by
839 the legacy /proc/ hugepages APIs, used for SHM, and
840 default size when mounting hugetlbfs filesystems.
841 Defaults to the default architecture's huge page size
846 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
847 terminal devices. Valid values: 0..8
848 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
849 If specified, z/VM IUCV HVC accepts connections
850 from listed z/VM user IDs only.
852 i2c_bus= [HW] Override the default board specific I2C bus speed
853 or register an additional I2C bus that is not
854 registered from board initialization code.
858 i8042.debug [HW] Toggle i8042 debug mode
859 i8042.direct [HW] Put keyboard port into non-translated mode
860 i8042.dumbkbd [HW] Pretend that controller can only read data from
861 keyboard and cannot control its state
862 (Don't attempt to blink the leds)
863 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
864 i8042.nokbd [HW] Don't check/create keyboard port
865 i8042.noloop [HW] Disable the AUX Loopback command while probing
867 i8042.nomux [HW] Don't check presence of an active multiplexing
869 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
872 [HW] Frequency with which keyboard LEDs should blink
873 when kernel panics (default is 0.5 sec)
874 i8042.reset [HW] Reset the controller during init and cleanup
875 i8042.unlock [HW] Unlock (ignore) the keylock
879 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
880 indicates that the driver is running on unsupported
882 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
883 does not match list of supported models.
885 [HW] Report power status in /proc/i8k
886 (disabled by default)
887 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
890 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
891 See Documentation/mca.txt.
894 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
896 ide-core.nodma= [HW] (E)IDE subsystem
897 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
898 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
899 .chs .ignore_cable are additional options
900 See Documentation/ide/ide.txt.
902 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
903 See Documentation/ide/ide.txt.
906 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
907 Poll forces a polling idle loop that can slightly
908 improve the performance of waking up a idle CPU, but
909 will use a lot of power and make the system run hot.
911 idle=mwait: On systems which support MONITOR/MWAIT but
912 the kernel chose to not use it because it doesn't save
913 as much power as a normal idle loop, use the
914 MONITOR/MWAIT idle loop anyways. Performance should be
915 the same as idle=poll.
916 idle=halt: Halt is forced to be used for CPU idle.
917 In such case C2/C3 won't be used again.
918 idle=nomwait: Disable mwait for CPU C-states
920 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
921 Claim all unknown PCI IDE storage controllers.
923 ignore_loglevel [KNL]
924 Ignore loglevel setting - this will print /all/
925 kernel messages to the console. Useful for debugging.
928 Set number of hash buckets for inode cache.
931 Format: { "0" | "1" }
932 0 -- integrity auditing messages. (Default)
933 1 -- enable informational integrity auditing messages.
936 Formt: { "sha1" | "md5" }
940 See header of drivers/scsi/in2000.c.
944 Run specified binary instead of /sbin/init as init
947 initcall_debug [KNL] Trace initcalls as they are executed. Useful
948 for working out where the kernel is dying during
951 initrd= [BOOT] Specify the location of the initial ramdisk
953 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
958 iomem= Disable strict checking of access to MMIO memory
959 strict regions from userspace.
975 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
977 Enable intel iommu driver.
979 Disable intel iommu driver.
980 igfx_off [Default Off]
981 By default, gfx is mapped as normal device. If a gfx
982 device has a dedicated DMAR unit, the DMAR unit is
983 bypassed by not enabling DMAR with this option. In
984 this case, gfx device will use physical address for
987 With this option iommu will not optimize to look
988 for io virtual address below 32 bit forcing dual
989 address cycle on pci bus for cards supporting greater
990 than 32 bit addressing. The default is to look
991 for translation below 32 bit and if not available
992 then look in the higher range.
994 With this option on every unmap_single operation will
995 result in a hardware IOTLB flush operation as opposed
996 to batching them for performance.
998 io_delay= [X86-32,X86-64] I/O delay method
1000 Standard port 0x80 based delay
1002 Alternate port 0xed based delay (needed on some systems)
1004 Simple two microseconds delay
1008 io7= [HW] IO7 for Marvel based alpha systems
1009 See comment before marvel_specify_io7 in
1010 arch/alpha/kernel/core_marvel.c.
1013 See Documentation/filesystems/nfsroot.txt.
1015 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1016 See comment before ip2_setup() in
1017 drivers/char/ip2/ip2base.c.
1019 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1020 See header of drivers/scsi/ips.c.
1022 ports= [IP_VS_FTP] IPVS ftp helper module
1024 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1026 Format: <port>,<port>....
1029 When an interrupt is not handled search all handlers
1030 for it. Intended to get systems with badly broken
1034 When an interrupt is not handled search all handlers
1035 for it. Also check all handlers each timer
1036 interrupt. Intended to get systems with badly broken
1040 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1042 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1044 <cpu number>,...,<cpu number>
1046 <cpu number>-<cpu number>
1047 (must be a positive range in ascending order)
1049 <cpu number>,...,<cpu number>-<cpu number>
1051 This option can be used to specify one or more CPUs
1052 to isolate from the general SMP balancing and scheduling
1053 algorithms. You can move a process onto or off an
1054 "isolated" CPU via the CPU affinity syscalls or cpuset.
1055 <cpu number> begins at 0 and the maximum value is
1056 "number of CPUs in system - 1".
1058 This option is the preferred way to isolate CPUs. The
1059 alternative -- manually setting the CPU mask of all
1060 tasks in the system -- can cause problems and
1061 suboptimal load balancer performance.
1065 js= [HW,JOY] Analog joystick
1066 See Documentation/input/joystick.txt.
1068 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1069 specifies the amount of memory usable by the kernel
1070 for non-movable allocations. The requested amount is
1071 spread evenly throughout all nodes in the system. The
1072 remaining memory in each node is used for Movable
1073 pages. In the event, a node is too small to have both
1074 kernelcore and Movable pages, kernelcore pages will
1075 take priority and other nodes will have a larger number
1076 of kernelcore pages. The Movable zone is used for the
1077 allocation of pages that may be reclaimed or moved
1078 by the page migration subsystem. This means that
1079 HugeTLB pages may not be allocated from this zone.
1080 Note that allocations like PTEs-from-HighMem still
1081 use the HighMem zone if it exists, and the Normal
1082 zone if it does not.
1084 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1085 is similar to kernelcore except it specifies the
1086 amount of memory used for migratable allocations.
1087 If both kernelcore and movablecore is specified,
1088 then kernelcore will be at *least* the specified
1089 value but may be more. If movablecore on its own
1090 is specified, the administrator must be careful
1091 that the amount of memory usable for all allocations
1096 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1099 kgdboc= [HW] kgdb over consoles.
1100 Requires a tty driver that supports console polling.
1101 (only serial suported for now)
1102 Format: <serial_device>[,baud]
1104 kmac= [MIPS] korina ethernet MAC address.
1105 Configure the RouterBoard 532 series on-chip
1106 Ethernet adapter MAC address.
1112 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1115 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1118 libata.dma= [LIBATA] DMA control
1119 libata.dma=0 Disable all PATA and SATA DMA
1120 libata.dma=1 PATA and SATA Disk DMA only
1121 libata.dma=2 ATAPI (CDROM) DMA only
1122 libata.dma=4 Compact Flash DMA only
1123 Combinations also work, so libata.dma=3 enables DMA
1124 for disks and CDROMs, but not CFs.
1126 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1130 libata.force= [LIBATA] Force configurations. The format is comma
1131 separated list of "[ID:]VAL" where ID is
1132 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1133 matching port, link or device. Basically, it matches
1134 the ATA ID string printed on console by libata. If
1135 the whole ID part is omitted, the last PORT and DEVICE
1136 values are used. If ID hasn't been specified yet, the
1137 configuration applies to all ports, links and devices.
1139 If only DEVICE is omitted, the parameter applies to
1140 the port and all links and devices behind it. DEVICE
1141 number of 0 either selects the first device or the
1142 first fan-out link behind PMP device. It does not
1143 select the host link. DEVICE number of 15 selects the
1144 host link and device attached to it.
1146 The VAL specifies the configuration to force. As long
1147 as there's no ambiguity shortcut notation is allowed.
1148 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1149 The following configurations can be forced.
1151 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1152 Any ID with matching PORT is used.
1154 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1156 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1157 udma[/][16,25,33,44,66,100,133] notation is also
1160 * [no]ncq: Turn on or off NCQ.
1162 * nohrst, nosrst, norst: suppress hard, soft
1165 If there are multiple matching configurations changing
1166 the same attribute, the last one is used.
1168 lmb=debug [KNL] Enable lmb debug messages.
1170 load_ramdisk= [RAM] List of ramdisks to load from floppy
1171 See Documentation/blockdev/ramdisk.txt.
1173 lockd.nlm_grace_period=P [NFS] Assign grace period.
1176 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1179 lockd.nlm_timeout=T [NFS] Assign timeout value.
1182 lockd.nlm_udpport=M [NFS] Assign UDP port.
1185 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1188 loglevel= All Kernel Messages with a loglevel smaller than the
1189 console loglevel will be printed to the console. It can
1190 also be changed with klogd or other programs. The
1191 loglevels are defined as follows:
1193 0 (KERN_EMERG) system is unusable
1194 1 (KERN_ALERT) action must be taken immediately
1195 2 (KERN_CRIT) critical conditions
1196 3 (KERN_ERR) error conditions
1197 4 (KERN_WARNING) warning conditions
1198 5 (KERN_NOTICE) normal but significant condition
1199 6 (KERN_INFO) informational
1200 7 (KERN_DEBUG) debug-level messages
1202 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1203 Format: { n | nk | nM }
1204 n must be a power of two. The default size
1205 is set in the kernel config file.
1207 logo.nologo [FB] Disables display of the built-in Linux logo.
1208 This may be used to provide more screen space for
1209 kernel log messages and is useful when debugging
1210 kernel boot problems.
1212 lp=0 [LP] Specify parallel ports to use, e.g,
1213 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1214 lp=reset first parallel port). 'lp=0' disables the
1215 lp=auto printer driver. 'lp=reset' (which can be
1216 specified in addition to the ports) causes
1217 attached printers to be reset. Using
1218 lp=port1,port2,... specifies the parallel ports
1219 to associate lp devices with, starting with
1220 lp0. A port specification may be 'none' to skip
1221 that lp device, or a parport name such as
1222 'parport0'. Specifying 'lp=auto' instead of a
1223 port specification list means that device IDs
1224 from each port should be examined, to see if
1225 an IEEE 1284-compliant printer is attached; if
1226 so, the driver will manage that printer.
1227 See also header of drivers/char/lp.c.
1230 Sets loops_per_jiffy to given constant, thus avoiding
1231 time-consuming boot-time autodetection (up to 250 ms per
1232 CPU). 0 enables autodetection (default). To determine
1233 the correct value for your kernel, boot with normal
1234 autodetection and see what value is printed. Note that
1235 on SMP systems the preset will be applied to all CPUs,
1236 which is likely to cause problems if your CPUs need
1237 significantly divergent settings. An incorrect value
1238 will cause delays in the kernel to be wrong, leading to
1239 unpredictable I/O errors and other breakage. Although
1240 unlikely, in the extreme case this might damage your
1244 Format: <io>,<irq>,<dma>
1246 mac5380= [HW,SCSI] Format:
1247 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1249 machvec= [IA64] Force the use of a particular machine-vector
1250 (machvec) in a generic kernel.
1251 Example: machvec=hpzx1_swiotlb
1253 max_loop= [LOOP] Maximum number of loopback devices that can
1257 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1258 should make use of. maxcpus=n : n >= 0 limits the
1259 kernel to using 'n' processors. n=0 is a special case,
1260 it is equivalent to "nosmp", which also disables
1263 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1264 or equal to this physical address is ignored.
1266 max_luns= [SCSI] Maximum number of LUNs to probe.
1267 Should be between 1 and 2^32-1.
1270 [SCSI] Maximum number of LUNs received.
1271 Should be between 1 and 16384.
1275 mce [X86-32] Machine Check Exception
1277 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1279 md= [HW] RAID subsystems devices and level
1280 See Documentation/md.txt.
1283 Format: <first>,<last>
1284 Specifies range of consoles to be captured by the MDA.
1286 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1287 Amount of memory to be used when the kernel is not able
1288 to see the whole system memory or for test.
1289 [X86-32] Use together with memmap= to avoid physical
1290 address space collisions. Without memmap= PCI devices
1291 could be placed at addresses belonging to unused RAM.
1293 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1297 [KNL,SH] Allow user to override the default size for
1298 per-device physically contiguous DMA buffers.
1300 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1301 E820 memory map, as specified by the user.
1302 Such memmap=exactmap lines can be constructed based on
1303 BIOS output or other requirements. See the memmap=nn@ss
1306 memmap=nn[KMG]@ss[KMG]
1307 [KNL] Force usage of a specific region of memory
1308 Region of memory to be used, from ss to ss+nn.
1310 memmap=nn[KMG]#ss[KMG]
1311 [KNL,ACPI] Mark specific memory as ACPI data.
1312 Region of memory to be used, from ss to ss+nn.
1314 memmap=nn[KMG]$ss[KMG]
1315 [KNL,ACPI] Mark specific memory as reserved.
1316 Region of memory to be used, from ss to ss+nn.
1317 Example: Exclude memory from 0x18690000-0x1869ffff
1318 memmap=64K$0x18690000
1320 memmap=0x10000$0x18690000
1322 memory_corruption_check=0/1 [X86]
1323 Some BIOSes seem to corrupt the first 64k of
1324 memory when doing things like suspend/resume.
1325 Setting this option will scan the memory
1326 looking for corruption. Enabling this will
1327 both detect corruption and prevent the kernel
1328 from using the memory being corrupted.
1329 However, its intended as a diagnostic tool; if
1330 repeatable BIOS-originated corruption always
1331 affects the same memory, you can use memmap=
1332 to prevent the kernel from using that memory.
1334 memory_corruption_check_size=size [X86]
1335 By default it checks for corruption in the low
1336 64k, making this memory unavailable for normal
1337 use. Use this parameter to scan for
1338 corruption in more or less memory.
1340 memory_corruption_check_period=seconds [X86]
1341 By default it checks for corruption every 60
1342 seconds. Use this parameter to check at some
1343 other rate. 0 disables periodic checking.
1345 memtest= [KNL,X86] Enable memtest
1347 default : 0 <disable>
1348 Specifies the number of memtest passes to be
1349 performed. Each pass selects another test
1350 pattern from a given set of patterns. Memtest
1351 fills the memory with this pattern, validates
1352 memory contents and reserves bad memory
1353 regions that are detected.
1355 meye.*= [HW] Set MotionEye Camera parameters
1356 See Documentation/video4linux/meye.txt.
1358 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1359 Multi-Function General Purpose Timers on AMD Geode
1362 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1363 the BIOS has incorrectly applied a workaround. TinyBIOS
1364 version 0.98 is known to be affected, 0.99 fixes the
1365 problem by letting the user disable the workaround.
1369 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1370 physical address is ignored.
1373 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1374 parameter allows control of the logging verbosity for
1375 the additional memory initialisation checks. A value
1376 of 0 disables mminit logging and a level of 4 will
1377 log everything. Information is printed at KERN_DEBUG
1378 so loglevel=8 may also need to be specified.
1381 [MOUSE] Maximum time between finger touching and
1382 leaving touchpad surface for touch to be considered
1383 a tap and be reported as a left button click (for
1384 touchpads working in absolute mode only).
1386 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1387 reporting absolute coordinates, such as tablets
1388 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1389 reporting absolute coordinates, such as tablets
1394 MTD_Partition= [MTD]
1395 Format: <name>,<region-number>,<size>,<offset>
1397 MTD_Region= [MTD] Format:
1398 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1401 See drivers/mtd/cmdlinepart.c.
1404 ARM/S3C2412 JIVE boot control
1406 See arch/arm/mach-s3c2412/mach-jive.c
1408 mtouchusb.raw_coordinates=
1409 [HW] Make the MicroTouch USB driver use raw coordinates
1410 ('y', default) or cooked coordinates ('n')
1412 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1415 See header of drivers/scsi/NCR_D700.c.
1419 ncr53c400= [HW,SCSI]
1421 ncr53c400a= [HW,SCSI]
1423 ncr53c406a= [HW,SCSI]
1425 ncr53c8xx= [HW,SCSI]
1427 netdev= [NET] Network devices parameters
1428 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1429 Note that mem_start is often overloaded to mean
1430 something different and driver-specific.
1431 This usage is only documented in each driver source
1435 [NETFILTER] Enable connection tracking flow accounting
1436 0 to disable accounting
1437 1 to enable accounting
1438 Default value depends on CONFIG_NF_CT_ACCT that is
1439 going to be removed in 2.6.29.
1442 See Documentation/filesystems/nfsroot.txt.
1444 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1445 See Documentation/filesystems/nfsroot.txt.
1447 nfs.callback_tcpport=
1448 [NFS] set the TCP port on which the NFSv4 callback
1449 channel should listen.
1451 nfs.idmap_cache_timeout=
1452 [NFS] set the maximum lifetime for idmapper cache
1456 [NFS] enable 64-bit inode numbers.
1457 If zero, the NFS client will fake up a 32-bit inode
1458 number for the readdir() and stat() syscalls instead
1459 of returning the full 64-bit number.
1460 The default is to return 64-bit inode numbers.
1462 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1463 when a NMI is triggered.
1464 Format: [state][,regs][,debounce][,die]
1466 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1467 Format: [panic,][num]
1469 0 - turn nmi_watchdog off
1470 1 - use the IO-APIC timer for the NMI watchdog
1471 2 - use the local APIC for the NMI watchdog using
1472 a performance counter. Note: This will use one performance
1473 counter and the local APIC's performance vector.
1474 When panic is specified panic when an NMI watchdog timeout occurs.
1475 This is useful when you use a panic=... timeout and need the box
1477 Instead of 1 and 2 it is possible to use the following
1478 symbolic names: lapic and ioapic
1479 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1481 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1482 emulation library even if a 387 maths coprocessor
1485 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1486 caches in the slab allocator. Saves per-node memory,
1487 but will impact performance.
1491 noapic [SMP,APIC] Tells the kernel to not make use of any
1492 IOAPICs that may be present in the system.
1494 nobats [PPC] Do not use BATs for mapping kernel lowmem
1495 on "Classic" PPC cores.
1499 nodelayacct [KNL] Disable per-task delay accounting
1501 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1503 nodsp [SH] Disable hardware DSP at boot time.
1505 noefi [X86-32,X86-64] Disable EFI runtime services support.
1509 noexec [X86-32,X86-64]
1510 On X86-32 available only on PAE configured kernels.
1511 noexec=on: enable non-executable mappings (default)
1512 noexec=off: disable non-executable mappings
1515 This affects only 32-bit executables.
1516 noexec32=on: enable non-executable mappings (default)
1517 read doesn't imply executable mappings
1518 noexec32=off: disable non-executable mappings
1519 read implies executable mappings
1521 nofpu [SH] Disable hardware FPU at boot time.
1523 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1524 register save and restore. The kernel will only save
1525 legacy floating-point registers on task switch.
1527 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1529 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1530 wfi(ARM) instruction doesn't work correctly and not to
1531 use it. This is also useful when using JTAG debugger.
1533 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1534 instruction doesn't work correctly and not to
1537 no_file_caps Tells the kernel not to honor file capabilities. The
1538 only way then for a file to be executed with privilege
1539 is to be setuid root or executed by root.
1541 nohalt [IA-64] Tells the kernel not to use the power saving
1542 function PAL_HALT_LIGHT when idle. This increases
1543 power-consumption. On the positive side, it reduces
1544 interrupt wake-up latency, which may improve performance
1545 in certain environments such as networked servers or
1548 nohz= [KNL] Boottime enable/disable dynamic ticks
1549 Valid arguments: on, off
1552 noirqdebug [X86-32] Disables the code which attempts to detect and
1553 disable unhandled interrupt sources.
1555 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1556 broken timer IRQ sources.
1558 noisapnp [ISAPNP] Disables ISA PnP code.
1560 noinitrd [RAM] Tells the kernel not to load any configured
1565 nojitter [IA64] Disables jitter checking for ITC timers.
1567 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1569 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1571 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1573 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1574 default x2apic cluster mode on platforms
1577 noltlbs [PPC] Do not use large page/tlb entries for kernel
1578 lowmem mapping on PPC40x.
1580 nomca [IA-64] Disable machine check abort handling
1582 nomce [X86-32] Machine Check Exception
1584 nomfgpt [X86-32] Disable Multi-Function General Purpose
1585 Timer usage (for AMD Geode machines).
1587 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1589 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1590 with UP alternatives
1592 noresidual [PPC] Don't use residual data on PReP machines.
1594 noresume [SWSUSP] Disables resume and restores original swap
1597 no-scroll [VGA] Disables scrollback.
1598 This is required for the Braillex ib80-piezo Braille
1599 reader made by F.H. Papenmeier (Germany).
1603 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1605 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1606 and disable the IO APIC. legacy for "maxcpus=0".
1608 nosoftlockup [KNL] Disable the soft-lockup detector.
1610 noswapaccount [KNL] Disable accounting of swap in memory resource
1611 controller. (See Documentation/cgroups/memory.txt)
1613 nosync [HW,M68K] Disables sync negotiation for all devices.
1615 notsc [BUGS=X86-32] Disable Time Stamp Counter
1617 nousb [USB] Disable the USB subsystem
1621 nptcg= [IA64] Override max number of concurrent global TLB
1622 purges which is reported from either PAL_VM_SUMMARY or
1625 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1626 one of ['zone', 'node', 'default'] can be specified
1627 This can be set from sysctl after boot.
1628 See Documentation/sysctl/vm.txt for details.
1630 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1632 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1633 See Documentation/debugging-via-ohci1394.txt for more
1636 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1637 Rather than timing out after 20 ms if an EC
1638 command is not properly ACKed, override the length
1639 of the timeout. We have interrupts disabled while
1640 waiting for the ACK, so if this is set too high
1641 interrupts *may* be lost!
1646 oprofile.timer= [HW]
1647 Use timer interrupt instead of performance counters
1649 osst= [HW,SCSI] SCSI Tape Driver
1650 Format: <buffer_size>,<write_threshold>
1651 See also Documentation/scsi/st.txt.
1653 panic= [KNL] Kernel behaviour on panic
1656 parkbd.port= [HW] Parallel port number the keyboard adapter is
1657 connected to, default is 0.
1659 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1660 0 for XT, 1 for AT (default is AT).
1663 parport= [HW,PPT] Specify parallel ports. 0 disables.
1664 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1665 Use 'auto' to force the driver to use any
1666 IRQ/DMA settings detected (the default is to
1667 ignore detected IRQ/DMA settings because of
1668 possible conflicts). You can specify the base
1669 address, IRQ, and DMA settings; IRQ and DMA
1670 should be numbers, or 'auto' (for using detected
1671 settings on that particular port), or 'nofifo'
1672 (to avoid using a FIFO even if it is detected).
1673 Parallel ports are assigned in the order they
1674 are specified on the command line, starting
1677 parport_init_mode= [HW,PPT]
1678 Configure VIA parallel port to operate in
1679 a specific mode. This is necessary on Pegasos
1680 computer where firmware has no options for setting
1681 up parallel port mode and sets it to spp.
1682 Currently this function knows 686a and 8231 chips.
1683 Format: [spp|ps2|epp|ecp|ecpepp]
1685 pas2= [HW,OSS] Format:
1686 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1689 See header of drivers/scsi/pas16.c.
1692 Halt all CPUs after the first oops has been printed for
1693 the specified number of seconds. This is to be used if
1694 your oopses keep scrolling off the screen.
1699 See header of drivers/block/paride/pcd.c.
1700 See also Documentation/blockdev/paride.txt.
1702 pci=option[,option...] [PCI] various PCI subsystem options:
1703 earlydump [X86] dump PCI config space before the kernel
1705 off [X86] don't probe for the PCI bus
1706 bios [X86-32] force use of PCI BIOS, don't access
1707 the hardware directly. Use this if your machine
1708 has a non-standard PCI host bridge.
1709 nobios [X86-32] disallow use of PCI BIOS, only direct
1710 hardware access methods are allowed. Use this
1711 if you experience crashes upon bootup and you
1712 suspect they are caused by the BIOS.
1713 conf1 [X86] Force use of PCI Configuration
1715 conf2 [X86] Force use of PCI Configuration
1717 noaer [PCIE] If the PCIEAER kernel config parameter is
1718 enabled, this kernel boot option can be used to
1719 disable the use of PCIE advanced error reporting.
1720 nodomains [PCI] Disable support for multiple PCI
1721 root domains (aka PCI segments, in ACPI-speak).
1722 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1724 nomsi [MSI] If the PCI_MSI kernel config parameter is
1725 enabled, this kernel boot option can be used to
1726 disable the use of MSI interrupts system-wide.
1727 noioapicquirk [APIC] Disable all boot interrupt quirks.
1728 Safety option to keep boot IRQs enabled. This
1729 should never be necessary.
1730 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1731 primary IO-APIC for bridges that cannot disable
1732 boot IRQs. This fixes a source of spurious IRQs
1733 when the system masks IRQs.
1734 noioapicreroute [APIC] Disable workaround that uses the
1735 boot IRQ equivalent of an IRQ that connects to
1736 a chipset where boot IRQs cannot be disabled.
1737 The opposite of ioapicreroute.
1738 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1739 routing table. These calls are known to be buggy
1740 on several machines and they hang the machine
1741 when used, but on other computers it's the only
1742 way to get the interrupt routing table. Try
1743 this option if the kernel is unable to allocate
1744 IRQs or discover secondary PCI buses on your
1746 rom [X86] Assign address space to expansion ROMs.
1747 Use with caution as certain devices share
1748 address decoders between ROMs and other
1750 norom [X86] Do not assign address space to
1751 expansion ROMs that do not already have
1752 BIOS assigned address ranges.
1753 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1754 assigned automatically to PCI devices. You can
1755 make the kernel exclude IRQs of your ISA cards
1757 pirqaddr=0xAAAAA [X86] Specify the physical address
1758 of the PIRQ table (normally generated
1759 by the BIOS) if it is outside the
1760 F0000h-100000h range.
1761 lastbus=N [X86] Scan all buses thru bus #N. Can be
1762 useful if the kernel is unable to find your
1763 secondary buses and you want to tell it
1764 explicitly which ones they are.
1765 assign-busses [X86] Always assign all PCI bus
1766 numbers ourselves, overriding
1767 whatever the firmware may have done.
1768 usepirqmask [X86] Honor the possible IRQ mask stored
1769 in the BIOS $PIR table. This is needed on
1770 some systems with broken BIOSes, notably
1771 some HP Pavilion N5400 and Omnibook XE3
1772 notebooks. This will have no effect if ACPI
1773 IRQ routing is enabled.
1774 noacpi [X86] Do not use ACPI for IRQ routing
1775 or for PCI scanning.
1776 use_crs [X86] Use _CRS for PCI resource
1778 routeirq Do IRQ routing for all PCI devices.
1779 This is normally done in pci_enable_device(),
1780 so this option is a temporary workaround
1781 for broken drivers that don't call it.
1782 skip_isa_align [X86] do not align io start addr, so can
1783 handle more pci cards
1784 firmware [ARM] Do not re-enumerate the bus but instead
1785 just use the configuration from the
1786 bootloader. This is currently used on
1787 IXP2000 systems where the bus has to be
1788 configured a certain way for adjunct CPUs.
1789 noearly [X86] Don't do any early type 1 scanning.
1790 This might help on some broken boards which
1791 machine check when some devices' config space
1792 is read. But various workarounds are disabled
1793 and some IOMMU drivers will not work.
1794 bfsort Sort PCI devices into breadth-first order.
1795 This sorting is done to get a device
1796 order compatible with older (<= 2.4) kernels.
1797 nobfsort Don't sort PCI devices into breadth-first order.
1798 cbiosize=nn[KMG] The fixed amount of bus space which is
1799 reserved for the CardBus bridge's IO window.
1800 The default value is 256 bytes.
1801 cbmemsize=nn[KMG] The fixed amount of bus space which is
1802 reserved for the CardBus bridge's memory
1803 window. The default value is 64 megabytes.
1806 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1807 Specifies alignment and device to reassign
1808 aligned memory resources.
1809 If <order of align> is not specified,
1810 PAGE_SIZE is used as alignment.
1811 PCI-PCI bridge can be specified, if resource
1812 windows need to be expanded.
1814 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1817 force Enable ASPM even on devices that claim not to support it.
1818 WARNING: Forcing ASPM on may cause system lockups.
1820 pcmv= [HW,PCMCIA] BadgePAD 4
1823 See Documentation/blockdev/paride.txt.
1825 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1828 See arch/parisc/kernel/pdc_chassis.c
1831 See Documentation/blockdev/paride.txt.
1834 See Documentation/blockdev/paride.txt.
1836 pirq= [SMP,APIC] Manual mp-table setup
1837 See Documentation/x86/i386/IO-APIC.txt.
1839 plip= [PPT,NET] Parallel port network link
1840 Format: { parport<nr> | timid | 0 }
1841 See also Documentation/parport.txt.
1843 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1844 Override pmtimer IOPort with a hex value.
1848 Enable PNP debug messages. This depends on the
1849 CONFIG_PNP_DEBUG_MESSAGES option.
1855 { on | off | curr | res | no-curr | no-res }
1858 [ISAPNP] Exclude IRQs for the autoconfiguration
1861 [ISAPNP] Exclude DMAs for the autoconfiguration
1863 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1864 Ranges are in pairs (I/O port base and size).
1867 [ISAPNP] Exclude memory regions for the
1869 Ranges are in pairs (memory base and size).
1871 print-fatal-signals=
1872 [KNL] debug: print fatal signals
1873 print-fatal-signals=1: print segfault info to
1877 printk.time= Show timing data prefixed to each printk message line
1878 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1880 profile= [KNL] Enable kernel profiling via /proc/profile
1881 Format: [schedule,]<number>
1882 Param: "schedule" - profile schedule points.
1883 Param: <number> - step/bucket size as a power of 2 for
1884 statistical time based profiling.
1885 Param: "sleep" - profile D-state sleeping (millisecs).
1886 Requires CONFIG_SCHEDSTATS
1887 Param: "kvm" - profile VM exits.
1889 processor.max_cstate= [HW,ACPI]
1890 Limit processor to maximum C-state
1891 max_cstate=9 overrides any DMI blacklist limit.
1893 processor.nocst [HW,ACPI]
1894 Ignore the _CST method to determine C-states,
1895 instead using the legacy FADT method
1897 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1899 See Documentation/blockdev/ramdisk.txt.
1901 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1902 probe for; one of (bare|imps|exps|lifebook|any).
1903 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1905 psmouse.resetafter= [HW,MOUSE]
1906 Try to reset the device after so many bad packets
1909 [HW,MOUSE] Set desired mouse resolution, in dpi.
1910 psmouse.smartscroll=
1911 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1912 0 = disabled, 1 = enabled (default).
1914 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1916 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1919 See Documentation/blockdev/paride.txt.
1922 [KNL] Number of legacy pty's. Overwrites compiled-in
1925 quiet [KNL] Disable most log messages
1930 See Documentation/md.txt.
1932 ramdisk_blocksize= [RAM]
1933 See Documentation/blockdev/ramdisk.txt.
1935 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1936 See Documentation/blockdev/ramdisk.txt.
1938 rcupdate.blimit= [KNL,BOOT]
1939 Set maximum number of finished RCU callbacks to process
1942 rcupdate.qhimark= [KNL,BOOT]
1943 Set threshold of queued
1944 RCU callbacks over which batch limiting is disabled.
1946 rcupdate.qlowmark= [KNL,BOOT]
1947 Set threshold of queued RCU callbacks below which
1948 batch limiting is re-enabled.
1952 Run specified binary instead of /init from the ramdisk,
1953 used for early userspace startup. See initrd.
1955 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1956 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1957 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1960 [KNL, SMP] Set scheduler's default relax_domain_level.
1961 See Documentation/cgroups/cpusets.txt.
1963 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1965 reservetop= [X86-32]
1967 Reserves a hole at the top of the kernel virtual
1970 reset_devices [KNL] Force drivers to reset the underlying device
1971 during initialization.
1974 Specify the partition device for software suspend
1976 resume_offset= [SWSUSP]
1977 Specify the offset from the beginning of the partition
1978 given by "resume=" at which the swap header is located,
1979 in <PAGE_SIZE> units (needed only for swap files).
1980 See Documentation/power/swsusp-and-swap-files.txt
1982 retain_initrd [RAM] Keep initrd memory after extraction
1984 rhash_entries= [KNL,NET]
1985 Set number of hash buckets for route cache
1987 riscom8= [HW,SERIAL]
1988 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1990 ro [KNL] Mount root device read-only on boot
1992 root= [KNL] Root filesystem
1994 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1995 mount the root filesystem
1997 rootflags= [KNL] Set root filesystem mount option string
1999 rootfstype= [KNL] Set root filesystem type
2001 rootwait [KNL] Wait (indefinitely) for root device to show up.
2002 Useful for devices that are detected asynchronously
2003 (e.g. USB and MMC devices).
2005 root_plug.vendor_id=
2006 [ROOTPLUG] Override the default vendor ID
2008 root_plug.product_id=
2009 [ROOTPLUG] Override the default product ID
2012 [ROOTPLUG] Enable debugging output
2014 rw [KNL] Mount root device read-write on boot
2016 S [KNL] Run init in single mode
2019 See drivers/net/irda/sa1100_ir.c.
2021 sbni= [NET] Granch SBNI12 leased line adapter
2023 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2024 Format: <io>[,<timeout>[,<isapnp>]]
2026 scsi_debug_*= [SCSI]
2027 See drivers/scsi/scsi_debug.c.
2029 scsi_default_dev_flags=
2030 [SCSI] SCSI default device flags
2033 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2034 Format: <vendor>:<model>:<flags>
2035 (flags are integer value)
2037 scsi_logging_level= [SCSI] a bit mask of logging levels
2038 See drivers/scsi/scsi_logging.h for bits. Also
2039 settable via sysctl at dev.scsi.logging_level
2040 (/proc/sys/dev/scsi/logging_level).
2041 There is also a nice 'scsi_logging_level' script in the
2042 S390-tools package, available for download at
2043 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2045 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2046 discovered. async scans them in kernel threads,
2047 allowing boot to proceed. none ignores them, expecting
2048 user space to do the scan.
2050 selinux [SELINUX] Disable or enable SELinux at boot time.
2051 Format: { "0" | "1" }
2052 See security/selinux/Kconfig help text.
2055 Default value is set via kernel config option.
2056 If enabled at boot time, /selinux/disable can be used
2057 later to disable prior to initial policy load.
2059 serialnumber [BUGS=X86-32]
2062 Maximal number of shapers.
2064 show_msr= [x86] show boot-time MSR settings
2065 Format: { <integer> }
2066 Show boot-time (BIOS-initialized) MSR settings.
2067 The parameter means the number of CPUs to show,
2068 for example 1 means boot CPU only.
2071 See header of drivers/scsi/sim710.c.
2078 slub_debug[=options[,slabs]] [MM, SLUB]
2079 Enabling slub_debug allows one to determine the
2080 culprit if slab objects become corrupted. Enabling
2081 slub_debug can create guard zones around objects and
2082 may poison objects when not in use. Also tracks the
2083 last alloc / free. For more information see
2084 Documentation/vm/slub.txt.
2086 slub_max_order= [MM, SLUB]
2087 Determines the maximum allowed order for slabs.
2088 A high setting may cause OOMs due to memory
2089 fragmentation. For more information see
2090 Documentation/vm/slub.txt.
2092 slub_min_objects= [MM, SLUB]
2093 The minimum number of objects per slab. SLUB will
2094 increase the slab order up to slub_max_order to
2095 generate a sufficiently large slab able to contain
2096 the number of objects indicated. The higher the number
2097 of objects the smaller the overhead of tracking slabs
2098 and the less frequently locks need to be acquired.
2099 For more information see Documentation/vm/slub.txt.
2101 slub_min_order= [MM, SLUB]
2102 Determines the mininum page order for slabs. Must be
2103 lower than slub_max_order.
2104 For more information see Documentation/vm/slub.txt.
2106 slub_nomerge [MM, SLUB]
2107 Disable merging of slabs with similar size. May be
2108 necessary if there is some reason to distinguish
2109 allocs to different slabs. Debug options disable
2110 merging on their own.
2111 For more information see Documentation/vm/slub.txt.
2114 Format: <io1>[,<io2>[,...,<io8>]]
2116 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2117 attempt to substitute SMP alternatives once at boot.
2119 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2120 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2121 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2122 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2123 smsc-ircc2.ircc_irq= [HW] IRQ line
2124 smsc-ircc2.ircc_dma= [HW] DMA channel
2125 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2126 0: Toshiba Satellite 1800 (GP data pin select)
2127 1: Fast pin select (default)
2130 snd-ad1816a= [HW,ALSA]
2132 snd-ad1848= [HW,ALSA]
2134 snd-ali5451= [HW,ALSA]
2136 snd-als100= [HW,ALSA]
2138 snd-als4000= [HW,ALSA]
2140 snd-azt2320= [HW,ALSA]
2142 snd-cmi8330= [HW,ALSA]
2144 snd-cmipci= [HW,ALSA]
2146 snd-cs4231= [HW,ALSA]
2148 snd-cs4232= [HW,ALSA]
2150 snd-cs4236= [HW,ALSA]
2152 snd-cs4281= [HW,ALSA]
2154 snd-cs46xx= [HW,ALSA]
2156 snd-dt019x= [HW,ALSA]
2158 snd-dummy= [HW,ALSA]
2160 snd-emu10k1= [HW,ALSA]
2162 snd-ens1370= [HW,ALSA]
2164 snd-ens1371= [HW,ALSA]
2166 snd-es968= [HW,ALSA]
2168 snd-es1688= [HW,ALSA]
2170 snd-es18xx= [HW,ALSA]
2172 snd-es1938= [HW,ALSA]
2174 snd-es1968= [HW,ALSA]
2176 snd-fm801= [HW,ALSA]
2178 snd-gusclassic= [HW,ALSA]
2180 snd-gusextreme= [HW,ALSA]
2182 snd-gusmax= [HW,ALSA]
2186 snd-ice1712= [HW,ALSA]
2188 snd-intel8x0= [HW,ALSA]
2190 snd-interwave= [HW,ALSA]
2195 snd-korg1212= [HW,ALSA]
2197 snd-maestro3= [HW,ALSA]
2199 snd-mpu401= [HW,ALSA]
2201 snd-mtpav= [HW,ALSA]
2203 snd-nm256= [HW,ALSA]
2205 snd-opl3sa2= [HW,ALSA]
2213 snd-opti93x= [HW,ALSA]
2217 snd-rme32= [HW,ALSA]
2219 snd-rme96= [HW,ALSA]
2221 snd-rme9652= [HW,ALSA]
2227 snd-sbawe= [HW,ALSA]
2229 snd-serial= [HW,ALSA]
2231 snd-sgalaxy= [HW,ALSA]
2233 snd-sonicvibes= [HW,ALSA]
2238 snd-sun-cs4231= [HW,ALSA]
2240 snd-trident= [HW,ALSA]
2242 snd-usb-audio= [HW,ALSA,USB]
2244 snd-via82xx= [HW,ALSA]
2246 snd-virmidi= [HW,ALSA]
2248 snd-wavefront= [HW,ALSA]
2250 snd-ymfpci= [HW,ALSA]
2253 [KNL] Should the soft-lockup detector generate panics.
2255 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2256 See Documentation/sonypi.txt
2258 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2259 See Documentation/serial/specialix.txt.
2261 spia_io_base= [HW,MTD]
2267 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2269 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2270 See Documentation/scsi/st.txt.
2273 Enabled the stack tracer on boot up.
2277 Set the STI (builtin display/keyboard on the HP-PARISC
2278 machines) console (graphic card) which should be used
2279 as the initial boot-console.
2280 See also comment in drivers/video/console/sticore.c.
2283 See comment in drivers/video/console/sticore.c.
2286 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2290 Control how the NFS server code allocates CPUs to
2291 service thread pools. Depending on how many NICs
2292 you have and where their interrupts are bound, this
2293 option will affect which CPUs will do NFS serving.
2294 Note: this parameter cannot be changed while the
2295 NFS server is running.
2297 auto the server chooses an appropriate mode
2298 automatically using heuristics
2299 global a single global pool contains all CPUs
2300 percpu one pool for each CPU
2301 pernode one pool for each NUMA node (equivalent
2302 to global on non-NUMA machines)
2304 swiotlb= [IA-64] Number of I/O TLB slabs
2308 sym53c416= [HW,SCSI]
2309 See header of drivers/scsi/sym53c416.c.
2311 sysrq_always_enabled
2313 Ignore sysrq setting - this boot parameter will
2314 neutralize any effect of /proc/sys/kernel/sysrq.
2315 Useful for debugging.
2318 See header of drivers/scsi/t128.c.
2322 test_suspend= [SUSPEND]
2323 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2324 standby suspend) as the system sleep state to briefly
2325 enter during system startup. The system is woken from
2326 this state using a wakeup-capable RTC alarm.
2328 thash_entries= [KNL,NET]
2329 Set number of hash buckets for TCP connection
2331 thermal.act= [HW,ACPI]
2332 -1: disable all active trip points in all thermal zones
2333 <degrees C>: override all lowest active trip points
2335 thermal.crt= [HW,ACPI]
2336 -1: disable all critical trip points in all thermal zones
2337 <degrees C>: override all critical trip points
2339 thermal.nocrt= [HW,ACPI]
2340 Set to disable actions on ACPI thermal zone
2341 critical and hot trip points.
2343 thermal.off= [HW,ACPI]
2344 1: disable ACPI thermal control
2346 thermal.psv= [HW,ACPI]
2347 -1: disable all passive trip points
2348 <degrees C>: override all passive trip points to this
2351 thermal.tzp= [HW,ACPI]
2352 Specify global default ACPI thermal zone polling rate
2353 <deci-seconds>: poll all this frequency
2354 0: no polling (default)
2357 See comment before function dc390_setup() in
2358 drivers/scsi/tmscsim.c.
2362 Specify if the kernel should make use of the cpu
2363 topology informations if the hardware supports these.
2364 The scheduler will make use of these informations and
2365 e.g. base its process migration decisions on it.
2370 trix= [HW,OSS] MediaTrix AudioTrix Pro
2372 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2374 tsc= Disable clocksource-must-verify flag for TSC.
2376 [x86] reliable: mark tsc clocksource as reliable, this
2377 disables clocksource verification at runtime.
2378 Used to enable high-resolution timer mode on older
2379 hardware, and in virtualized environment.
2381 turbografx.map[2|3]= [HW,JOY]
2382 TurboGraFX parallel port interface
2384 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2385 See also Documentation/input/joystick-parport.txt
2387 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2388 See header of drivers/scsi/u14-34f.c.
2397 [USB] Ignore overcurrent events (default N).
2398 Some badly-designed motherboards generate lots of
2399 bogus events, for ports that aren't wired to
2400 anything. Set this parameter to avoid log spamming.
2401 Note that genuine overcurrent events won't be
2406 Set unknown_nmi_panic=1 early on boot.
2408 usbcore.autosuspend=
2409 [USB] The autosuspend time delay (in seconds) used
2410 for newly-detected USB devices (default 2). This
2411 is the time required before an idle device will be
2412 autosuspended. Devices for which the delay is set
2413 to a negative value won't be autosuspended at all.
2415 usbcore.usbfs_snoop=
2416 [USB] Set to log all usbfs traffic (default 0 = off).
2418 usbcore.blinkenlights=
2419 [USB] Set to cycle leds on hubs (default 0 = off).
2421 usbcore.old_scheme_first=
2422 [USB] Start with the old device initialization
2423 scheme (default 0 = off).
2425 usbcore.use_both_schemes=
2426 [USB] Try the other device initialization scheme
2427 if the first one fails (default 1 = enabled).
2429 usbcore.initial_descriptor_timeout=
2430 [USB] Specifies timeout for the initial 64-byte
2431 USB_REQ_GET_DESCRIPTOR request in milliseconds
2432 (default 5000 = 5.0 seconds).
2435 [USBHID] The interval which mice are to be polled at.
2437 usb-storage.delay_use=
2438 [UMS] The delay in seconds before a new device is
2439 scanned for Logical Units (default 5).
2442 [UMS] A list of quirks entries to supplement or
2443 override the built-in unusual_devs list. List
2444 entries are separated by commas. Each entry has
2445 the form VID:PID:Flags where VID and PID are Vendor
2446 and Product ID values (4-digit hex numbers) and
2447 Flags is a set of characters, each corresponding
2448 to a common usb-storage quirk flag as follows:
2449 a = SANE_SENSE (collect more than 18 bytes
2451 c = FIX_CAPACITY (decrease the reported
2452 device capacity by one sector);
2453 h = CAPACITY_HEURISTICS (decrease the
2454 reported device capacity by one
2455 sector if the number is odd);
2456 i = IGNORE_DEVICE (don't bind to this
2458 l = NOT_LOCKABLE (don't try to lock and
2459 unlock ejectable media);
2460 m = MAX_SECTORS_64 (don't transfer more
2461 than 64 sectors = 32 KB at a time);
2462 o = CAPACITY_OK (accept the capacity
2463 reported by the device);
2464 r = IGNORE_RESIDUE (the device reports
2465 bogus residue values);
2466 s = SINGLE_LUN (the device has only one
2468 w = NO_WP_DETECT (don't test whether the
2469 medium is write-protected).
2470 Example: quirks=0419:aaf5:rl,0421:0433:rc
2472 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2473 kernel's map of available physical RAM.
2475 vdso= [X86-32,SH,x86-64]
2476 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2477 vdso=1: enable VDSO (default)
2478 vdso=0: disable VDSO mapping
2480 vdso32= [X86-32,X86-64]
2481 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2482 vdso32=1: enable 32-bit VDSO (default)
2483 vdso32=0: disable 32-bit VDSO mapping
2486 vector=percpu: enable percpu vector domain
2488 video= [FB] Frame buffer configuration
2489 See Documentation/fb/modedb.txt.
2491 vga= [BOOT,X86-32] Select a particular video mode
2492 See Documentation/x86/boot.txt and
2493 Documentation/svga.txt.
2494 Use vga=ask for menu.
2495 This is actually a boot loader parameter; the value is
2496 passed to the kernel using a special protocol.
2498 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2499 size of <nn>. This can be used to increase the
2500 minimum size (128MB on x86). It can also be used to
2501 decrease the size and leave more room for directly
2504 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2507 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2510 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2513 waveartist= [HW,OSS]
2514 Format: <io>,<irq>,<dma>,<dma2>
2517 See header of drivers/scsi/wd33c93.c.
2520 See header of drivers/scsi/wd7000.c.
2523 See Documentation/watchdog/wdt.txt.
2525 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2526 xd_geo= See header of drivers/block/xd.c.
2528 xirc2ps_cs= [NET,PCMCIA]
2530 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2532 norandmaps Don't use address space randomization. Equivalent to
2533 echo 0 > /proc/sys/kernel/randomize_va_space
2535 ______________________________________________________________________
2539 Add documentation for ALSA options.
2540 Add more DRM drivers.
projects / linux-2.6 / blob