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1 Kernel Parameters
2 ~~~~~~~~~~~~~~~~~
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 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 AVR32 AVR32 architecture is enabled.
44 AX25 Appropriate AX.25 support is enabled.
45 BLACKFIN Blackfin architecture is enabled.
46 DRM Direct Rendering Management support is enabled.
47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
51 GCOV GCOV profiling is enabled.
52 HW Appropriate hardware is enabled.
53 IA-64 IA-64 architecture is enabled.
54 IMA Integrity measurement architecture is enabled.
55 IOSCHED More than one I/O scheduler is enabled.
56 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
57 ISAPNP ISA PnP code is enabled.
58 ISDN Appropriate ISDN support is enabled.
59 JOY Appropriate joystick support is enabled.
60 LIBATA Libata driver is enabled
61 LP Printer support is enabled.
62 LOOP Loopback device support is enabled.
63 M68k M68k architecture is enabled.
64 These options have more detailed description inside of
65 Documentation/m68k/kernel-options.txt.
66 MCA MCA bus support is enabled.
67 MDA MDA console support is enabled.
68 MOUSE Appropriate mouse support is enabled.
69 MSI Message Signaled Interrupts (PCI).
70 MTD MTD (Memory Technology Device) support is enabled.
71 NET Appropriate network support is enabled.
72 NUMA NUMA support is enabled.
73 GENERIC_TIME The generic timeofday code is enabled.
74 NFS Appropriate NFS support is enabled.
75 OSS OSS sound support is enabled.
76 PV_OPS A paravirtualized kernel is enabled.
77 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
78 PARISC The PA-RISC architecture is enabled.
79 PCI PCI bus support is enabled.
80 PCIE PCI Express support is enabled.
81 PCMCIA The PCMCIA subsystem is enabled.
82 PNP Plug & Play support is enabled.
83 PPC PowerPC architecture is enabled.
84 PPT Parallel port support is enabled.
85 PS2 Appropriate PS/2 support is enabled.
86 RAM RAM disk support is enabled.
87 ROOTPLUG The example Root Plug LSM is enabled.
88 S390 S390 architecture is enabled.
89 SCSI Appropriate SCSI support is enabled.
90 A lot of drivers has their options described inside of
91 Documentation/scsi/.
92 SECURITY Different security models are enabled.
93 SELINUX SELinux support is enabled.
94 SERIAL Serial support is enabled.
95 SH SuperH architecture is enabled.
96 SMP The kernel is an SMP kernel.
97 SPARC Sparc architecture is enabled.
98 SWSUSP Software suspend (hibernation) is enabled.
99 SUSPEND System suspend states are enabled.
100 FTRACE Function tracing enabled.
101 TS Appropriate touchscreen support is enabled.
102 UMS USB Mass Storage support is enabled.
103 USB USB support is enabled.
104 USBHID USB Human Interface Device support is enabled.
105 V4L Video For Linux support is enabled.
106 VGA The VGA console has been enabled.
107 VT Virtual terminal support is enabled.
108 WDT Watchdog support is enabled.
109 XT IBM PC/XT MFM hard disk support is enabled.
110 X86-32 X86-32, aka i386 architecture is enabled.
111 X86-64 X86-64 architecture is enabled.
112 More X86-64 boot options can be found in
113 Documentation/x86/x86_64/boot-options.txt .
114 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
116 In addition, the following text indicates that the option:
118 BUGS= Relates to possible processor bugs on the said processor.
119 KNL Is a kernel start-up parameter.
120 BOOT Is a boot loader parameter.
122 Parameters denoted with BOOT are actually interpreted by the boot
123 loader, and have no meaning to the kernel directly.
124 Do not modify the syntax of boot loader parameters without extreme
125 need or coordination with <Documentation/x86/boot.txt>.
127 There are also arch-specific kernel-parameters not documented here.
128 See for example <Documentation/x86/x86_64/boot-options.txt>.
130 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
131 a trailing = on the name of any parameter states that that parameter will
132 be entered as an environment variable, whereas its absence indicates that
133 it will appear as a kernel argument readable via /proc/cmdline by programs
134 running once the system is up.
136 The number of kernel parameters is not limited, but the length of the
137 complete command line (parameters including spaces etc.) is limited to
138 a fixed number of characters. This limit depends on the architecture
139 and is between 256 and 4096 characters. It is defined in the file
140 ./include/asm/setup.h as COMMAND_LINE_SIZE.
143 acpi= [HW,ACPI,X86]
144 Advanced Configuration and Power Interface
145 Format: { force | off | ht | strict | noirq | rsdt }
146 force -- enable ACPI if default was off
147 off -- disable ACPI if default was on
148 noirq -- do not use ACPI for IRQ routing
149 ht -- run only enough ACPI to enable Hyper Threading
150 strict -- Be less tolerant of platforms that are not
151 strictly ACPI specification compliant.
152 rsdt -- prefer RSDT over (default) XSDT
154 See also Documentation/power/pm.txt, pci=noacpi
156 acpi_apic_instance= [ACPI, IOAPIC]
157 Format: <int>
158 2: use 2nd APIC table, if available
159 1,0: use 1st APIC table
160 default: 0
162 acpi_backlight= [HW,ACPI]
163 acpi_backlight=vendor
164 acpi_backlight=video
165 If set to vendor, prefer vendor specific driver
166 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
167 of the ACPI video.ko driver.
169 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
170 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
171 Format: <int>
172 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
173 debug output. Bits in debug_layer correspond to a
174 _COMPONENT in an ACPI source file, e.g.,
175 #define _COMPONENT ACPI_PCI_COMPONENT
176 Bits in debug_level correspond to a level in
177 ACPI_DEBUG_PRINT statements, e.g.,
178 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
179 The debug_level mask defaults to "info". See
180 Documentation/acpi/debug.txt for more information about
181 debug layers and levels.
183 Enable processor driver info messages:
184 acpi.debug_layer=0x20000000
185 Enable PCI/PCI interrupt routing info messages:
186 acpi.debug_layer=0x400000
187 Enable AML "Debug" output, i.e., stores to the Debug
188 object while interpreting AML:
189 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
190 Enable all messages related to ACPI hardware:
191 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
193 Some values produce so much output that the system is
194 unusable. The "log_buf_len" parameter may be useful
195 if you need to capture more output.
197 acpi_display_output= [HW,ACPI]
198 acpi_display_output=vendor
199 acpi_display_output=video
200 See above.
202 acpi_irq_balance [HW,ACPI]
203 ACPI will balance active IRQs
204 default in APIC mode
206 acpi_irq_nobalance [HW,ACPI]
207 ACPI will not move active IRQs (default)
208 default in PIC mode
210 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
211 Format: <irq>,<irq>...
213 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
214 use by PCI
215 Format: <irq>,<irq>...
217 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
219 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
220 Format: To spoof as Windows 98: ="Microsoft Windows"
222 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
223 acpi_osi="string1" # add string1 -- only one string
224 acpi_osi="!string2" # remove built-in string2
225 acpi_osi= # disable all strings
227 acpi_pm_good [X86]
228 Override the pmtimer bug detection: force the kernel
229 to assume that this machine's pmtimer latches its value
230 and always returns good values.
232 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
233 Format: { level | edge | high | low }
235 acpi_serialize [HW,ACPI] force serialization of AML methods
237 acpi_skip_timer_override [HW,ACPI]
238 Recognize and ignore IRQ0/pin2 Interrupt Override.
239 For broken nForce2 BIOS resulting in XT-PIC timer.
241 acpi_sleep= [HW,ACPI] Sleep options
242 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
243 old_ordering, s4_nonvs }
244 See Documentation/power/video.txt for information on
245 s3_bios and s3_mode.
246 s3_beep is for debugging; it makes the PC's speaker beep
247 as soon as the kernel's real-mode entry point is called.
248 s4_nohwsig prevents ACPI hardware signature from being
249 used during resume from hibernation.
250 old_ordering causes the ACPI 1.0 ordering of the _PTS
251 control method, with respect to putting devices into
252 low power states, to be enforced (the ACPI 2.0 ordering
253 of _PTS is used by default).
254 s4_nonvs prevents the kernel from saving/restoring the
255 ACPI NVS memory during hibernation.
257 acpi_use_timer_override [HW,ACPI]
258 Use timer override. For some broken Nvidia NF5 boards
259 that require a timer override, but don't have HPET
261 acpi_enforce_resources= [ACPI]
262 { strict | lax | no }
263 Check for resource conflicts between native drivers
264 and ACPI OperationRegions (SystemIO and SystemMemory
265 only). IO ports and memory declared in ACPI might be
266 used by the ACPI subsystem in arbitrary AML code and
267 can interfere with legacy drivers.
268 strict (default): access to resources claimed by ACPI
269 is denied; legacy drivers trying to access reserved
270 resources will fail to bind to device using them.
271 lax: access to resources claimed by ACPI is allowed;
272 legacy drivers trying to access reserved resources
273 will bind successfully but a warning message is logged.
274 no: ACPI OperationRegions are not marked as reserved,
275 no further checks are performed.
277 ad1848= [HW,OSS]
278 Format: <io>,<irq>,<dma>,<dma2>,<type>
280 add_efi_memmap [EFI; X86] Include EFI memory map in
281 kernel's map of available physical RAM.
283 advansys= [HW,SCSI]
284 See header of drivers/scsi/advansys.c.
286 advwdt= [HW,WDT] Advantech WDT
287 Format: <iostart>,<iostop>
289 aedsp16= [HW,OSS] Audio Excel DSP 16
290 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
291 See also header of sound/oss/aedsp16.c.
293 agp= [AGP]
294 { off | try_unsupported }
295 off: disable AGP support
296 try_unsupported: try to drive unsupported chipsets
297 (may crash computer or cause data corruption)
299 aha152x= [HW,SCSI]
300 See Documentation/scsi/aha152x.txt.
302 aha1542= [HW,SCSI]
303 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
305 aic7xxx= [HW,SCSI]
306 See Documentation/scsi/aic7xxx.txt.
308 aic79xx= [HW,SCSI]
309 See Documentation/scsi/aic79xx.txt.
311 amd_iommu= [HW,X86-84]
312 Pass parameters to the AMD IOMMU driver in the system.
313 Possible values are:
314 isolate - enable device isolation (each device, as far
315 as possible, will get its own protection
316 domain) [default]
317 share - put every device behind one IOMMU into the
318 same protection domain
319 fullflush - enable flushing of IO/TLB entries when
320 they are unmapped. Otherwise they are
321 flushed before they will be reused, which
322 is a lot of faster
324 amijoy.map= [HW,JOY] Amiga joystick support
325 Map of devices attached to JOY0DAT and JOY1DAT
326 Format: <a>,<b>
327 See also Documentation/kernel/input/joystick.txt
329 analog.map= [HW,JOY] Analog joystick and gamepad support
330 Specifies type or capabilities of an analog joystick
331 connected to one of 16 gameports
332 Format: <type1>,<type2>,..<type16>
334 apc= [HW,SPARC]
335 Power management functions (SPARCstation-4/5 + deriv.)
336 Format: noidle
337 Disable APC CPU standby support. SPARCstation-Fox does
338 not play well with APC CPU idle - disable it if you have
339 APC and your system crashes randomly.
341 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
342 Change the output verbosity whilst booting
343 Format: { quiet (default) | verbose | debug }
344 Change the amount of debugging information output
345 when initialising the APIC and IO-APIC components.
347 apm= [APM] Advanced Power Management
348 See header of arch/x86/kernel/apm_32.c.
350 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
351 Format: <io>,<irq>,<nodeID>
353 ataflop= [HW,M68k]
355 atarimouse= [HW,MOUSE] Atari Mouse
357 atascsi= [HW,SCSI] Atari SCSI
359 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
360 EzKey and similar keyboards
362 atkbd.reset= [HW] Reset keyboard during initialization
364 atkbd.set= [HW] Select keyboard code set
365 Format: <int> (2 = AT (default), 3 = PS/2)
367 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
368 keyboards
370 atkbd.softraw= [HW] Choose between synthetic and real raw mode
371 Format: <bool> (0 = real, 1 = synthetic (default))
373 atkbd.softrepeat= [HW]
374 Use software keyboard repeat
376 autotest [IA64]
378 baycom_epp= [HW,AX25]
379 Format: <io>,<mode>
381 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
382 Format: <io>,<mode>
383 See header of drivers/net/hamradio/baycom_par.c.
385 baycom_ser_fdx= [HW,AX25]
386 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
387 Format: <io>,<irq>,<mode>[,<baud>]
388 See header of drivers/net/hamradio/baycom_ser_fdx.c.
390 baycom_ser_hdx= [HW,AX25]
391 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
392 Format: <io>,<irq>,<mode>
393 See header of drivers/net/hamradio/baycom_ser_hdx.c.
395 boot_delay= Milliseconds to delay each printk during boot.
396 Values larger than 10 seconds (10000) are changed to
397 no delay (0).
398 Format: integer
400 bootmem_debug [KNL] Enable bootmem allocator debug messages.
402 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
403 bttv.radio= Most important insmod options are available as
404 kernel args too.
405 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
406 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
408 BusLogic= [HW,SCSI]
409 See drivers/scsi/BusLogic.c, comment before function
410 BusLogic_ParseDriverOptions().
412 c101= [NET] Moxa C101 synchronous serial card
414 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
415 Sometimes CPU hardware bugs make them report the cache
416 size incorrectly. The kernel will attempt work arounds
417 to fix known problems, but for some CPUs it is not
418 possible to determine what the correct size should be.
419 This option provides an override for these situations.
421 capability.disable=
422 [SECURITY] Disable capabilities. This would normally
423 be used only if an alternative security model is to be
424 configured. Potentially dangerous and should only be
425 used if you are entirely sure of the consequences.
427 ccw_timeout_log [S390]
428 See Documentation/s390/CommonIO for details.
430 cgroup_disable= [KNL] Disable a particular controller
431 Format: {name of the controller(s) to disable}
432 {Currently supported controllers - "memory"}
434 checkreqprot [SELINUX] Set initial checkreqprot flag value.
435 Format: { "0" | "1" }
436 See security/selinux/Kconfig help text.
437 0 -- check protection applied by kernel (includes
438 any implied execute protection).
439 1 -- check protection requested by application.
440 Default value is set via a kernel config option.
441 Value can be changed at runtime via
442 /selinux/checkreqprot.
444 cio_ignore= [S390]
445 See Documentation/s390/CommonIO for details.
447 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
448 [Deprecated]
449 Forces specified clocksource (if available) to be used
450 when calculating gettimeofday(). If specified
451 clocksource is not available, it defaults to PIT.
452 Format: { pit | tsc | cyclone | pmtmr }
454 clocksource= [GENERIC_TIME] Override the default clocksource
455 Format: <string>
456 Override the default clocksource and use the clocksource
457 with the name specified.
458 Some clocksource names to choose from, depending on
459 the platform:
460 [all] jiffies (this is the base, fallback clocksource)
461 [ACPI] acpi_pm
462 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
463 pxa_timer,timer3,32k_counter,timer0_1
464 [AVR32] avr32
465 [X86-32] pit,hpet,tsc,vmi-timer;
466 scx200_hrt on Geode; cyclone on IBM x440
467 [MIPS] MIPS
468 [PARISC] cr16
469 [S390] tod
470 [SH] SuperH
471 [SPARC64] tick
472 [X86-64] hpet,tsc
474 clearcpuid=BITNUM [X86]
475 Disable CPUID feature X for the kernel. See
476 arch/x86/include/asm/cpufeature.h for the valid bit
477 numbers. Note the Linux specific bits are not necessarily
478 stable over kernel options, but the vendor specific
479 ones should be.
480 Also note that user programs calling CPUID directly
481 or using the feature without checking anything
482 will still see it. This just prevents it from
483 being used by the kernel or shown in /proc/cpuinfo.
484 Also note the kernel might malfunction if you disable
485 some critical bits.
487 cmo_free_hint= [PPC] Format: { yes | no }
488 Specify whether pages are marked as being inactive
489 when they are freed. This is used in CMO environments
490 to determine OS memory pressure for page stealing by
491 a hypervisor.
492 Default: yes
494 code_bytes [X86] How many bytes of object code to print
495 in an oops report.
496 Range: 0 - 8192
497 Default: 64
499 com20020= [HW,NET] ARCnet - COM20020 chipset
500 Format:
501 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
503 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
504 Format: <io>[,<irq>]
506 com90xx= [HW,NET]
507 ARCnet - COM90xx chipset (memory-mapped buffers)
508 Format: <io>[,<irq>[,<memstart>]]
510 condev= [HW,S390] console device
511 conmode=
513 console= [KNL] Output console device and options.
515 tty<n> Use the virtual console device <n>.
517 ttyS<n>[,options]
518 ttyUSB0[,options]
519 Use the specified serial port. The options are of
520 the form "bbbbpnf", where "bbbb" is the baud rate,
521 "p" is parity ("n", "o", or "e"), "n" is number of
522 bits, and "f" is flow control ("r" for RTS or
523 omit it). Default is "9600n8".
525 See Documentation/serial-console.txt for more
526 information. See
527 Documentation/networking/netconsole.txt for an
528 alternative.
530 uart[8250],io,<addr>[,options]
531 uart[8250],mmio,<addr>[,options]
532 Start an early, polled-mode console on the 8250/16550
533 UART at the specified I/O port or MMIO address,
534 switching to the matching ttyS device later. The
535 options are the same as for ttyS, above.
537 If the device connected to the port is not a TTY but a braille
538 device, prepend "brl," before the device type, for instance
539 console=brl,ttyS0
540 For now, only VisioBraille is supported.
542 consoleblank= [KNL] The console blank (screen saver) timeout in
543 seconds. Defaults to 10*60 = 10mins. A value of 0
544 disables the blank timer.
546 coredump_filter=
547 [KNL] Change the default value for
548 /proc/<pid>/coredump_filter.
549 See also Documentation/filesystems/proc.txt.
551 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
552 Format:
553 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
555 crashkernel=nn[KMG]@ss[KMG]
556 [KNL] Reserve a chunk of physical memory to
557 hold a kernel to switch to with kexec on panic.
559 crashkernel=range1:size1[,range2:size2,...][@offset]
560 [KNL] Same as above, but depends on the memory
561 in the running system. The syntax of range is
562 start-[end] where start and end are both
563 a memory unit (amount[KMG]). See also
564 Documentation/kdump/kdump.txt for a example.
566 cs89x0_dma= [HW,NET]
567 Format: <dma>
569 cs89x0_media= [HW,NET]
570 Format: { rj45 | aui | bnc }
572 dasd= [HW,NET]
573 See header of drivers/s390/block/dasd_devmap.c.
575 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
576 (one device per port)
577 Format: <port#>,<type>
578 See also Documentation/input/joystick-parport.txt
580 debug [KNL] Enable kernel debugging (events log level).
582 debug_locks_verbose=
583 [KNL] verbose self-tests
584 Format=<0|1>
585 Print debugging info while doing the locking API
586 self-tests.
587 We default to 0 (no extra messages), setting it to
588 1 will print _a lot_ more information - normally
589 only useful to kernel developers.
591 debug_objects [KNL] Enable object debugging
593 no_debug_objects
594 [KNL] Disable object debugging
596 debugpat [X86] Enable PAT debugging
598 decnet.addr= [HW,NET]
599 Format: <area>[,<node>]
600 See also Documentation/networking/decnet.txt.
602 default_hugepagesz=
603 [same as hugepagesz=] The size of the default
604 HugeTLB page size. This is the size represented by
605 the legacy /proc/ hugepages APIs, used for SHM, and
606 default size when mounting hugetlbfs filesystems.
607 Defaults to the default architecture's huge page size
608 if not specified.
610 dhash_entries= [KNL]
611 Set number of hash buckets for dentry cache.
613 digi= [HW,SERIAL]
614 IO parameters + enable/disable command.
616 digiepca= [HW,SERIAL]
617 See drivers/char/README.epca and
618 Documentation/serial/digiepca.txt.
620 disable_mtrr_cleanup [X86]
621 The kernel tries to adjust MTRR layout from continuous
622 to discrete, to make X server driver able to add WB
623 entry later. This parameter disables that.
625 disable_mtrr_trim [X86, Intel and AMD only]
626 By default the kernel will trim any uncacheable
627 memory out of your available memory pool based on
628 MTRR settings. This parameter disables that behavior,
629 possibly causing your machine to run very slowly.
631 disable_timer_pin_1 [X86]
632 Disable PIN 1 of APIC timer
633 Can be useful to work around chipset bugs.
635 dmasound= [HW,OSS] Sound subsystem buffers
637 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
638 this option disables the debugging code at boot.
640 dma_debug_entries=<number>
641 This option allows to tune the number of preallocated
642 entries for DMA-API debugging code. One entry is
643 required per DMA-API allocation. Use this if the
644 DMA-API debugging code disables itself because the
645 architectural default is too low.
647 dma_debug_driver=<driver_name>
648 With this option the DMA-API debugging driver
649 filter feature can be enabled at boot time. Just
650 pass the driver to filter for as the parameter.
651 The filter can be disabled or changed to another
652 driver later using sysfs.
654 dscc4.setup= [NET]
656 dtc3181e= [HW,SCSI]
658 dynamic_printk Enables pr_debug()/dev_dbg() calls if
659 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
660 These can also be switched on/off via
661 <debugfs>/dynamic_printk/modules
663 earlycon= [KNL] Output early console device and options.
664 uart[8250],io,<addr>[,options]
665 uart[8250],mmio,<addr>[,options]
666 Start an early, polled-mode console on the 8250/16550
667 UART at the specified I/O port or MMIO address.
668 The options are the same as for ttyS, above.
670 earlyprintk= [X86,SH,BLACKFIN]
671 earlyprintk=vga
672 earlyprintk=serial[,ttySn[,baudrate]]
673 earlyprintk=dbgp
675 Append ",keep" to not disable it when the real console
676 takes over.
678 Only vga or serial or usb debug port at a time.
680 Currently only ttyS0 and ttyS1 are supported.
682 Interaction with the standard serial driver is not
683 very good.
685 The VGA output is eventually overwritten by the real
686 console.
688 eata= [HW,SCSI]
690 edd= [EDD]
691 Format: {"off" | "on" | "skip[mbr]"}
693 eisa_irq_edge= [PARISC,HW]
694 See header of drivers/parisc/eisa.c.
696 elanfreq= [X86-32]
697 See comment before function elanfreq_setup() in
698 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
700 elevator= [IOSCHED]
701 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
702 See Documentation/block/as-iosched.txt and
703 Documentation/block/deadline-iosched.txt for details.
705 elfcorehdr= [IA64,PPC,SH,X86]
706 Specifies physical address of start of kernel core
707 image elf header. Generally kexec loader will
708 pass this option to capture kernel.
709 See Documentation/kdump/kdump.txt for details.
711 enable_mtrr_cleanup [X86]
712 The kernel tries to adjust MTRR layout from continuous
713 to discrete, to make X server driver able to add WB
714 entry later. This parameter enables that.
716 enable_timer_pin_1 [X86]
717 Enable PIN 1 of APIC timer
718 Can be useful to work around chipset bugs
719 (in particular on some ATI chipsets).
720 The kernel tries to set a reasonable default.
722 enforcing [SELINUX] Set initial enforcing status.
723 Format: {"0" | "1"}
724 See security/selinux/Kconfig help text.
725 0 -- permissive (log only, no denials).
726 1 -- enforcing (deny and log).
727 Default value is 0.
728 Value can be changed at runtime via /selinux/enforce.
730 ether= [HW,NET] Ethernet cards parameters
731 This option is obsoleted by the "netdev=" option, which
732 has equivalent usage. See its documentation for details.
734 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
735 Format: <io>[,<irq>]
737 failslab=
738 fail_page_alloc=
739 fail_make_request=[KNL]
740 General fault injection mechanism.
741 Format: <interval>,<probability>,<space>,<times>
742 See also /Documentation/fault-injection/.
744 fd_mcs= [HW,SCSI]
745 See header of drivers/scsi/fd_mcs.c.
747 fdomain= [HW,SCSI]
748 See header of drivers/scsi/fdomain.c.
750 floppy= [HW]
751 See Documentation/blockdev/floppy.txt.
753 force_pal_cache_flush
754 [IA-64] Avoid check_sal_cache_flush which may hang on
755 buggy SAL_CACHE_FLUSH implementations. Using this
756 parameter will force ia64_sal_cache_flush to call
757 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
759 ftrace=[tracer]
760 [FTRACE] will set and start the specified tracer
761 as early as possible in order to facilitate early
762 boot debugging.
764 ftrace_dump_on_oops
765 [FTRACE] will dump the trace buffers on oops.
767 ftrace_filter=[function-list]
768 [FTRACE] Limit the functions traced by the function
769 tracer at boot up. function-list is a comma separated
770 list of functions. This list can be changed at run
771 time by the set_ftrace_filter file in the debugfs
772 tracing directory.
774 ftrace_notrace=[function-list]
775 [FTRACE] Do not trace the functions specified in
776 function-list. This list can be changed at run time
777 by the set_ftrace_notrace file in the debugfs
778 tracing directory.
780 gamecon.map[2|3]=
781 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
782 support via parallel port (up to 5 devices per port)
783 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
784 See also Documentation/input/joystick-parport.txt
786 gamma= [HW,DRM]
788 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
789 Format: off | on
790 default: on
792 gcov_persist= [GCOV] When non-zero (default), profiling data for
793 kernel modules is saved and remains accessible via
794 debugfs, even when the module is unloaded/reloaded.
795 When zero, profiling data is discarded and associated
796 debugfs files are removed at module unload time.
798 gdth= [HW,SCSI]
799 See header of drivers/scsi/gdth.c.
801 gpt [EFI] Forces disk with valid GPT signature but
802 invalid Protective MBR to be treated as GPT.
804 gvp11= [HW,SCSI]
806 hashdist= [KNL,NUMA] Large hashes allocated during boot
807 are distributed across NUMA nodes. Defaults on
808 for 64bit NUMA, off otherwise.
809 Format: 0 | 1 (for off | on)
811 hcl= [IA-64] SGI's Hardware Graph compatibility layer
813 hd= [EIDE] (E)IDE hard drive subsystem geometry
814 Format: <cyl>,<head>,<sect>
816 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
817 size of <nn>. This works even on boxes that have no
818 highmem otherwise. This also works to reduce highmem
819 size on bigger boxes.
821 highres= [KNL] Enable/disable high resolution timer mode.
822 Valid parameters: "on", "off"
823 Default: "on"
825 hisax= [HW,ISDN]
826 See Documentation/isdn/README.HiSax.
828 hlt [BUGS=ARM,SH]
830 hpet= [X86-32,HPET] option to control HPET usage
831 Format: { enable (default) | disable | force |
832 verbose }
833 disable: disable HPET and use PIT instead
834 force: allow force enabled of undocumented chips (ICH4,
835 VIA, nVidia)
836 verbose: show contents of HPET registers during setup
838 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
839 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
840 On x86-64 and powerpc, this option can be specified
841 multiple times interleaved with hugepages= to reserve
842 huge pages of different sizes. Valid pages sizes on
843 x86-64 are 2M (when the CPU supports "pse") and 1G
844 (when the CPU supports the "pdpe1gb" cpuinfo flag)
845 Note that 1GB pages can only be allocated at boot time
846 using hugepages= and not freed afterwards.
848 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
849 terminal devices. Valid values: 0..8
850 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
851 If specified, z/VM IUCV HVC accepts connections
852 from listed z/VM user IDs only.
854 i2c_bus= [HW] Override the default board specific I2C bus speed
855 or register an additional I2C bus that is not
856 registered from board initialization code.
857 Format:
858 <bus_id>,<clkrate>
860 i8042.debug [HW] Toggle i8042 debug mode
861 i8042.direct [HW] Put keyboard port into non-translated mode
862 i8042.dumbkbd [HW] Pretend that controller can only read data from
863 keyboard and cannot control its state
864 (Don't attempt to blink the leds)
865 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
866 i8042.nokbd [HW] Don't check/create keyboard port
867 i8042.noloop [HW] Disable the AUX Loopback command while probing
868 for the AUX port
869 i8042.nomux [HW] Don't check presence of an active multiplexing
870 controller
871 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
872 controllers
873 i8042.panicblink=
874 [HW] Frequency with which keyboard LEDs should blink
875 when kernel panics (default is 0.5 sec)
876 i8042.reset [HW] Reset the controller during init and cleanup
877 i8042.unlock [HW] Unlock (ignore) the keylock
879 i810= [HW,DRM]
881 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
882 indicates that the driver is running on unsupported
883 hardware.
884 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
885 does not match list of supported models.
886 i8k.power_status
887 [HW] Report power status in /proc/i8k
888 (disabled by default)
889 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
890 capability is set.
892 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
893 See Documentation/mca.txt.
895 icn= [HW,ISDN]
896 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
898 ide-core.nodma= [HW] (E)IDE subsystem
899 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
900 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
901 .cdrom .chs .ignore_cable are additional options
902 See Documentation/ide/ide.txt.
904 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
905 Claim all unknown PCI IDE storage controllers.
907 idle= [X86]
908 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
909 Poll forces a polling idle loop that can slightly
910 improve the performance of waking up a idle CPU, but
911 will use a lot of power and make the system run hot.
912 Not recommended.
913 idle=mwait: On systems which support MONITOR/MWAIT but
914 the kernel chose to not use it because it doesn't save
915 as much power as a normal idle loop, use the
916 MONITOR/MWAIT idle loop anyways. Performance should be
917 the same as idle=poll.
918 idle=halt: Halt is forced to be used for CPU idle.
919 In such case C2/C3 won't be used again.
920 idle=nomwait: Disable mwait for CPU C-states
922 ignore_loglevel [KNL]
923 Ignore loglevel setting - this will print /all/
924 kernel messages to the console. Useful for debugging.
926 ihash_entries= [KNL]
927 Set number of hash buckets for inode cache.
929 ima_audit= [IMA]
930 Format: { "0" | "1" }
931 0 -- integrity auditing messages. (Default)
932 1 -- enable informational integrity auditing messages.
934 ima_hash= [IMA]
935 Formt: { "sha1" | "md5" }
936 default: "sha1"
938 ima_tcb [IMA]
939 Load a policy which meets the needs of the Trusted
940 Computing Base. This means IMA will measure all
941 programs exec'd, files mmap'd for exec, and all files
942 opened for read by uid=0.
944 in2000= [HW,SCSI]
945 See header of drivers/scsi/in2000.c.
947 init= [KNL]
948 Format: <full_path>
949 Run specified binary instead of /sbin/init as init
950 process.
952 initcall_debug [KNL] Trace initcalls as they are executed. Useful
953 for working out where the kernel is dying during
954 startup.
956 initrd= [BOOT] Specify the location of the initial ramdisk
958 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
959 Format: <irq>
961 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
962 on
963 Enable intel iommu driver.
964 off
965 Disable intel iommu driver.
966 igfx_off [Default Off]
967 By default, gfx is mapped as normal device. If a gfx
968 device has a dedicated DMAR unit, the DMAR unit is
969 bypassed by not enabling DMAR with this option. In
970 this case, gfx device will use physical address for
971 DMA.
972 forcedac [x86_64]
973 With this option iommu will not optimize to look
974 for io virtual address below 32 bit forcing dual
975 address cycle on pci bus for cards supporting greater
976 than 32 bit addressing. The default is to look
977 for translation below 32 bit and if not available
978 then look in the higher range.
979 strict [Default Off]
980 With this option on every unmap_single operation will
981 result in a hardware IOTLB flush operation as opposed
982 to batching them for performance.
984 inttest= [IA64]
986 iomem= Disable strict checking of access to MMIO memory
987 strict regions from userspace.
988 relaxed
990 iommu= [x86]
991 off
992 force
993 noforce
994 biomerge
995 panic
996 nopanic
997 merge
998 nomerge
999 forcesac
1000 soft
1001 pt [x86, IA64]
1003 io7= [HW] IO7 for Marvel based alpha systems
1004 See comment before marvel_specify_io7 in
1005 arch/alpha/kernel/core_marvel.c.
1007 io_delay= [X86] I/O delay method
1008 0x80
1009 Standard port 0x80 based delay
1010 0xed
1011 Alternate port 0xed based delay (needed on some systems)
1012 udelay
1013 Simple two microseconds delay
1014 none
1015 No delay
1017 ip= [IP_PNP]
1018 See Documentation/filesystems/nfsroot.txt.
1020 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1021 See comment before ip2_setup() in
1022 drivers/char/ip2/ip2base.c.
1024 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1025 See header of drivers/scsi/ips.c.
1027 irqfixup [HW]
1028 When an interrupt is not handled search all handlers
1029 for it. Intended to get systems with badly broken
1030 firmware running.
1032 irqpoll [HW]
1033 When an interrupt is not handled search all handlers
1034 for it. Also check all handlers each timer
1035 interrupt. Intended to get systems with badly broken
1036 firmware running.
1038 isapnp= [ISAPNP]
1039 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1041 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1042 Format:
1043 <cpu number>,...,<cpu number>
1044 or
1045 <cpu number>-<cpu number>
1046 (must be a positive range in ascending order)
1047 or a mixture
1048 <cpu number>,...,<cpu number>-<cpu number>
1050 This option can be used to specify one or more CPUs
1051 to isolate from the general SMP balancing and scheduling
1052 algorithms. You can move a process onto or off an
1053 "isolated" CPU via the CPU affinity syscalls or cpuset.
1054 <cpu number> begins at 0 and the maximum value is
1055 "number of CPUs in system - 1".
1057 This option is the preferred way to isolate CPUs. The
1058 alternative -- manually setting the CPU mask of all
1059 tasks in the system -- can cause problems and
1060 suboptimal load balancer performance.
1062 iucv= [HW,NET]
1064 js= [HW,JOY] Analog joystick
1065 See Documentation/input/joystick.txt.
1067 keepinitrd [HW,ARM]
1069 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1070 specifies the amount of memory usable by the kernel
1071 for non-movable allocations. The requested amount is
1072 spread evenly throughout all nodes in the system. The
1073 remaining memory in each node is used for Movable
1074 pages. In the event, a node is too small to have both
1075 kernelcore and Movable pages, kernelcore pages will
1076 take priority and other nodes will have a larger number
1077 of kernelcore pages. The Movable zone is used for the
1078 allocation of pages that may be reclaimed or moved
1079 by the page migration subsystem. This means that
1080 HugeTLB pages may not be allocated from this zone.
1081 Note that allocations like PTEs-from-HighMem still
1082 use the HighMem zone if it exists, and the Normal
1083 zone if it does not.
1085 kgdboc= [HW] kgdb over consoles.
1086 Requires a tty driver that supports console polling.
1087 (only serial supported for now)
1088 Format: <serial_device>[,baud]
1090 kmac= [MIPS] korina ethernet MAC address.
1091 Configure the RouterBoard 532 series on-chip
1092 Ethernet adapter MAC address.
1094 kmemleak= [KNL] Boot-time kmemleak enable/disable
1095 Valid arguments: on, off
1096 Default: on
1098 kstack=N [X86] Print N words from the kernel stack
1099 in oops dumps.
1101 l2cr= [PPC]
1103 l3cr= [PPC]
1105 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1106 disabled it.
1108 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1109 in C2 power state.
1111 libata.dma= [LIBATA] DMA control
1112 libata.dma=0 Disable all PATA and SATA DMA
1113 libata.dma=1 PATA and SATA Disk DMA only
1114 libata.dma=2 ATAPI (CDROM) DMA only
1115 libata.dma=4 Compact Flash DMA only
1116 Combinations also work, so libata.dma=3 enables DMA
1117 for disks and CDROMs, but not CFs.
1119 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1120 libata.ignore_hpa=0 keep BIOS limits (default)
1121 libata.ignore_hpa=1 ignore limits, using full disk
1123 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1124 when set.
1125 Format: <int>
1127 libata.force= [LIBATA] Force configurations. The format is comma
1128 separated list of "[ID:]VAL" where ID is
1129 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1130 matching port, link or device. Basically, it matches
1131 the ATA ID string printed on console by libata. If
1132 the whole ID part is omitted, the last PORT and DEVICE
1133 values are used. If ID hasn't been specified yet, the
1134 configuration applies to all ports, links and devices.
1136 If only DEVICE is omitted, the parameter applies to
1137 the port and all links and devices behind it. DEVICE
1138 number of 0 either selects the first device or the
1139 first fan-out link behind PMP device. It does not
1140 select the host link. DEVICE number of 15 selects the
1141 host link and device attached to it.
1143 The VAL specifies the configuration to force. As long
1144 as there's no ambiguity shortcut notation is allowed.
1145 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1146 The following configurations can be forced.
1148 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1149 Any ID with matching PORT is used.
1151 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1153 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1154 udma[/][16,25,33,44,66,100,133] notation is also
1155 allowed.
1157 * [no]ncq: Turn on or off NCQ.
1159 * nohrst, nosrst, norst: suppress hard, soft
1160 and both resets.
1162 If there are multiple matching configurations changing
1163 the same attribute, the last one is used.
1165 lmb=debug [KNL] Enable lmb debug messages.
1167 load_ramdisk= [RAM] List of ramdisks to load from floppy
1168 See Documentation/blockdev/ramdisk.txt.
1170 lockd.nlm_grace_period=P [NFS] Assign grace period.
1171 Format: <integer>
1173 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1174 Format: <integer>
1176 lockd.nlm_timeout=T [NFS] Assign timeout value.
1177 Format: <integer>
1179 lockd.nlm_udpport=M [NFS] Assign UDP port.
1180 Format: <integer>
1182 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1183 Format: <irq>
1185 loglevel= All Kernel Messages with a loglevel smaller than the
1186 console loglevel will be printed to the console. It can
1187 also be changed with klogd or other programs. The
1188 loglevels are defined as follows:
1190 0 (KERN_EMERG) system is unusable
1191 1 (KERN_ALERT) action must be taken immediately
1192 2 (KERN_CRIT) critical conditions
1193 3 (KERN_ERR) error conditions
1194 4 (KERN_WARNING) warning conditions
1195 5 (KERN_NOTICE) normal but significant condition
1196 6 (KERN_INFO) informational
1197 7 (KERN_DEBUG) debug-level messages
1199 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1200 Format: { n | nk | nM }
1201 n must be a power of two. The default size
1202 is set in the kernel config file.
1204 logo.nologo [FB] Disables display of the built-in Linux logo.
1205 This may be used to provide more screen space for
1206 kernel log messages and is useful when debugging
1207 kernel boot problems.
1209 lp=0 [LP] Specify parallel ports to use, e.g,
1210 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1211 lp=reset first parallel port). 'lp=0' disables the
1212 lp=auto printer driver. 'lp=reset' (which can be
1213 specified in addition to the ports) causes
1214 attached printers to be reset. Using
1215 lp=port1,port2,... specifies the parallel ports
1216 to associate lp devices with, starting with
1217 lp0. A port specification may be 'none' to skip
1218 that lp device, or a parport name such as
1219 'parport0'. Specifying 'lp=auto' instead of a
1220 port specification list means that device IDs
1221 from each port should be examined, to see if
1222 an IEEE 1284-compliant printer is attached; if
1223 so, the driver will manage that printer.
1224 See also header of drivers/char/lp.c.
1226 lpj=n [KNL]
1227 Sets loops_per_jiffy to given constant, thus avoiding
1228 time-consuming boot-time autodetection (up to 250 ms per
1229 CPU). 0 enables autodetection (default). To determine
1230 the correct value for your kernel, boot with normal
1231 autodetection and see what value is printed. Note that
1232 on SMP systems the preset will be applied to all CPUs,
1233 which is likely to cause problems if your CPUs need
1234 significantly divergent settings. An incorrect value
1235 will cause delays in the kernel to be wrong, leading to
1236 unpredictable I/O errors and other breakage. Although
1237 unlikely, in the extreme case this might damage your
1238 hardware.
1240 ltpc= [NET]
1241 Format: <io>,<irq>,<dma>
1243 mac5380= [HW,SCSI] Format:
1244 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1246 machvec= [IA64] Force the use of a particular machine-vector
1247 (machvec) in a generic kernel.
1248 Example: machvec=hpzx1_swiotlb
1250 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1251 than or equal to this physical address is ignored.
1253 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1254 should make use of. maxcpus=n : n >= 0 limits the
1255 kernel to using 'n' processors. n=0 is a special case,
1256 it is equivalent to "nosmp", which also disables
1257 the IO APIC.
1259 max_loop= [LOOP] Maximum number of loopback devices that can
1260 be mounted
1261 Format: <1-256>
1263 max_luns= [SCSI] Maximum number of LUNs to probe.
1264 Should be between 1 and 2^32-1.
1266 max_report_luns=
1267 [SCSI] Maximum number of LUNs received.
1268 Should be between 1 and 16384.
1270 mcatest= [IA-64]
1272 mce [X86-32] Machine Check Exception
1274 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1276 md= [HW] RAID subsystems devices and level
1277 See Documentation/md.txt.
1279 mdacon= [MDA]
1280 Format: <first>,<last>
1281 Specifies range of consoles to be captured by the MDA.
1283 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1284 Amount of memory to be used when the kernel is not able
1285 to see the whole system memory or for test.
1286 [X86-32] Use together with memmap= to avoid physical
1287 address space collisions. Without memmap= PCI devices
1288 could be placed at addresses belonging to unused RAM.
1290 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1291 memory.
1293 memchunk=nn[KMG]
1294 [KNL,SH] Allow user to override the default size for
1295 per-device physically contiguous DMA buffers.
1297 memmap=exactmap [KNL,X86] Enable setting of an exact
1298 E820 memory map, as specified by the user.
1299 Such memmap=exactmap lines can be constructed based on
1300 BIOS output or other requirements. See the memmap=nn@ss
1301 option description.
1303 memmap=nn[KMG]@ss[KMG]
1304 [KNL] Force usage of a specific region of memory
1305 Region of memory to be used, from ss to ss+nn.
1307 memmap=nn[KMG]#ss[KMG]
1308 [KNL,ACPI] Mark specific memory as ACPI data.
1309 Region of memory to be used, from ss to ss+nn.
1311 memmap=nn[KMG]$ss[KMG]
1312 [KNL,ACPI] Mark specific memory as reserved.
1313 Region of memory to be used, from ss to ss+nn.
1314 Example: Exclude memory from 0x18690000-0x1869ffff
1315 memmap=64K$0x18690000
1316 or
1317 memmap=0x10000$0x18690000
1319 memory_corruption_check=0/1 [X86]
1320 Some BIOSes seem to corrupt the first 64k of
1321 memory when doing things like suspend/resume.
1322 Setting this option will scan the memory
1323 looking for corruption. Enabling this will
1324 both detect corruption and prevent the kernel
1325 from using the memory being corrupted.
1326 However, its intended as a diagnostic tool; if
1327 repeatable BIOS-originated corruption always
1328 affects the same memory, you can use memmap=
1329 to prevent the kernel from using that memory.
1331 memory_corruption_check_size=size [X86]
1332 By default it checks for corruption in the low
1333 64k, making this memory unavailable for normal
1334 use. Use this parameter to scan for
1335 corruption in more or less memory.
1337 memory_corruption_check_period=seconds [X86]
1338 By default it checks for corruption every 60
1339 seconds. Use this parameter to check at some
1340 other rate. 0 disables periodic checking.
1342 memtest= [KNL,X86] Enable memtest
1343 Format: <integer>
1344 default : 0 <disable>
1345 Specifies the number of memtest passes to be
1346 performed. Each pass selects another test
1347 pattern from a given set of patterns. Memtest
1348 fills the memory with this pattern, validates
1349 memory contents and reserves bad memory
1350 regions that are detected.
1352 meye.*= [HW] Set MotionEye Camera parameters
1353 See Documentation/video4linux/meye.txt.
1355 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1356 Multi-Function General Purpose Timers on AMD Geode
1357 platforms.
1359 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1360 the BIOS has incorrectly applied a workaround. TinyBIOS
1361 version 0.98 is known to be affected, 0.99 fixes the
1362 problem by letting the user disable the workaround.
1364 mga= [HW,DRM]
1366 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1367 physical address is ignored.
1369 mini2440= [ARM,HW,KNL]
1370 Format:[0..2][b][c][t]
1371 Default: "0tb"
1372 MINI2440 configuration specification:
1373 0 - The attached screen is the 3.5" TFT
1374 1 - The attached screen is the 7" TFT
1375 2 - The VGA Shield is attached (1024x768)
1376 Leaving out the screen size parameter will not load
1377 the TFT driver, and the framebuffer will be left
1378 unconfigured.
1379 b - Enable backlight. The TFT backlight pin will be
1380 linked to the kernel VESA blanking code and a GPIO
1381 LED. This parameter is not necessary when using the
1382 VGA shield.
1383 c - Enable the s3c camera interface.
1384 t - Reserved for enabling touchscreen support. The
1385 touchscreen support is not enabled in the mainstream
1386 kernel as of 2.6.30, a preliminary port can be found
1387 in the "bleeding edge" mini2440 support kernel at
1388 http://repo.or.cz/w/linux-2.6/mini2440.git
1390 mminit_loglevel=
1391 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1392 parameter allows control of the logging verbosity for
1393 the additional memory initialisation checks. A value
1394 of 0 disables mminit logging and a level of 4 will
1395 log everything. Information is printed at KERN_DEBUG
1396 so loglevel=8 may also need to be specified.
1398 mousedev.tap_time=
1399 [MOUSE] Maximum time between finger touching and
1400 leaving touchpad surface for touch to be considered
1401 a tap and be reported as a left button click (for
1402 touchpads working in absolute mode only).
1403 Format: <msecs>
1404 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1405 reporting absolute coordinates, such as tablets
1406 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1407 reporting absolute coordinates, such as tablets
1409 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1410 is similar to kernelcore except it specifies the
1411 amount of memory used for migratable allocations.
1412 If both kernelcore and movablecore is specified,
1413 then kernelcore will be at *least* the specified
1414 value but may be more. If movablecore on its own
1415 is specified, the administrator must be careful
1416 that the amount of memory usable for all allocations
1417 is not too small.
1419 mpu401= [HW,OSS]
1420 Format: <io>,<irq>
1422 MTD_Partition= [MTD]
1423 Format: <name>,<region-number>,<size>,<offset>
1425 MTD_Region= [MTD] Format:
1426 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1428 mtdparts= [MTD]
1429 See drivers/mtd/cmdlinepart.c.
1431 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1433 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1435 boundary - index of last SLC block on Flex-OneNAND.
1436 The remaining blocks are configured as MLC blocks.
1437 lock - Configure if Flex-OneNAND boundary should be locked.
1438 Once locked, the boundary cannot be changed.
1439 1 indicates lock status, 0 indicates unlock status.
1441 mtdset= [ARM]
1442 ARM/S3C2412 JIVE boot control
1444 See arch/arm/mach-s3c2412/mach-jive.c
1446 mtouchusb.raw_coordinates=
1447 [HW] Make the MicroTouch USB driver use raw coordinates
1448 ('y', default) or cooked coordinates ('n')
1450 mtrr_chunk_size=nn[KMG] [X86]
1451 used for mtrr cleanup. It is largest continuous chunk
1452 that could hold holes aka. UC entries.
1454 mtrr_gran_size=nn[KMG] [X86]
1455 Used for mtrr cleanup. It is granularity of mtrr block.
1456 Default is 1.
1457 Large value could prevent small alignment from
1458 using up MTRRs.
1460 mtrr_spare_reg_nr=n [X86]
1461 Format: <integer>
1462 Range: 0,7 : spare reg number
1463 Default : 1
1464 Used for mtrr cleanup. It is spare mtrr entries number.
1465 Set to 2 or more if your graphical card needs more.
1467 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1469 NCR_D700= [HW,SCSI]
1470 See header of drivers/scsi/NCR_D700.c.
1472 ncr5380= [HW,SCSI]
1474 ncr53c400= [HW,SCSI]
1476 ncr53c400a= [HW,SCSI]
1478 ncr53c406a= [HW,SCSI]
1480 ncr53c8xx= [HW,SCSI]
1482 netdev= [NET] Network devices parameters
1483 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1484 Note that mem_start is often overloaded to mean
1485 something different and driver-specific.
1486 This usage is only documented in each driver source
1487 file if at all.
1489 nf_conntrack.acct=
1490 [NETFILTER] Enable connection tracking flow accounting
1491 0 to disable accounting
1492 1 to enable accounting
1493 Default value depends on CONFIG_NF_CT_ACCT that is
1494 going to be removed in 2.6.29.
1496 nfsaddrs= [NFS]
1497 See Documentation/filesystems/nfsroot.txt.
1499 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1500 See Documentation/filesystems/nfsroot.txt.
1502 nfs.callback_tcpport=
1503 [NFS] set the TCP port on which the NFSv4 callback
1504 channel should listen.
1506 nfs.idmap_cache_timeout=
1507 [NFS] set the maximum lifetime for idmapper cache
1508 entries.
1510 nfs.enable_ino64=
1511 [NFS] enable 64-bit inode numbers.
1512 If zero, the NFS client will fake up a 32-bit inode
1513 number for the readdir() and stat() syscalls instead
1514 of returning the full 64-bit number.
1515 The default is to return 64-bit inode numbers.
1517 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1518 when a NMI is triggered.
1519 Format: [state][,regs][,debounce][,die]
1521 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1522 Format: [panic,][num]
1523 Valid num: 0,1,2
1524 0 - turn nmi_watchdog off
1525 1 - use the IO-APIC timer for the NMI watchdog
1526 2 - use the local APIC for the NMI watchdog using
1527 a performance counter. Note: This will use one
1528 performance counter and the local APIC's performance
1529 vector.
1530 When panic is specified, panic when an NMI watchdog
1531 timeout occurs.
1532 This is useful when you use a panic=... timeout and
1533 need the box quickly up again.
1534 Instead of 1 and 2 it is possible to use the following
1535 symbolic names: lapic and ioapic
1536 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1538 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1539 emulation library even if a 387 maths coprocessor
1540 is present.
1542 no_console_suspend
1543 [HW] Never suspend the console
1544 Disable suspending of consoles during suspend and
1545 hibernate operations. Once disabled, debugging
1546 messages can reach various consoles while the rest
1547 of the system is being put to sleep (ie, while
1548 debugging driver suspend/resume hooks). This may
1549 not work reliably with all consoles, but is known
1550 to work with serial and VGA consoles.
1552 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1553 caches in the slab allocator. Saves per-node memory,
1554 but will impact performance.
1556 noalign [KNL,ARM]
1558 noapic [SMP,APIC] Tells the kernel to not make use of any
1559 IOAPICs that may be present in the system.
1561 nobats [PPC] Do not use BATs for mapping kernel lowmem
1562 on "Classic" PPC cores.
1564 nocache [ARM]
1566 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1568 nodelayacct [KNL] Disable per-task delay accounting
1570 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1572 nodsp [SH] Disable hardware DSP at boot time.
1574 noefi [X86] Disable EFI runtime services support.
1576 noexec [IA-64]
1578 noexec [X86]
1579 On X86-32 available only on PAE configured kernels.
1580 noexec=on: enable non-executable mappings (default)
1581 noexec=off: disable non-executable mappings
1583 noexec32 [X86-64]
1584 This affects only 32-bit executables.
1585 noexec32=on: enable non-executable mappings (default)
1586 read doesn't imply executable mappings
1587 noexec32=off: disable non-executable mappings
1588 read implies executable mappings
1590 nofpu [SH] Disable hardware FPU at boot time.
1592 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1593 register save and restore. The kernel will only save
1594 legacy floating-point registers on task switch.
1596 noxsave [BUGS=X86] Disables x86 extended register state save
1597 and restore using xsave. The kernel will fallback to
1598 enabling legacy floating-point and sse state.
1600 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1601 wfi(ARM) instruction doesn't work correctly and not to
1602 use it. This is also useful when using JTAG debugger.
1604 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1605 instruction doesn't work correctly and not to
1606 use it.
1608 no_file_caps Tells the kernel not to honor file capabilities. The
1609 only way then for a file to be executed with privilege
1610 is to be setuid root or executed by root.
1612 nohalt [IA-64] Tells the kernel not to use the power saving
1613 function PAL_HALT_LIGHT when idle. This increases
1614 power-consumption. On the positive side, it reduces
1615 interrupt wake-up latency, which may improve performance
1616 in certain environments such as networked servers or
1617 real-time systems.
1619 nohz= [KNL] Boottime enable/disable dynamic ticks
1620 Valid arguments: on, off
1621 Default: on
1623 noiotrap [SH] Disables trapped I/O port accesses.
1625 noirqdebug [X86-32] Disables the code which attempts to detect and
1626 disable unhandled interrupt sources.
1628 no_timer_check [X86,APIC] Disables the code which tests for
1629 broken timer IRQ sources.
1631 noisapnp [ISAPNP] Disables ISA PnP code.
1633 noinitrd [RAM] Tells the kernel not to load any configured
1634 initial RAM disk.
1636 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1637 remapping.
1639 nointroute [IA-64]
1641 nojitter [IA64] Disables jitter checking for ITC timers.
1643 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1645 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1647 noltlbs [PPC] Do not use large page/tlb entries for kernel
1648 lowmem mapping on PPC40x.
1650 nomca [IA-64] Disable machine check abort handling
1652 nomce [X86-32] Machine Check Exception
1654 nomfgpt [X86-32] Disable Multi-Function General Purpose
1655 Timer usage (for AMD Geode machines).
1657 norandmaps Don't use address space randomization. Equivalent to
1658 echo 0 > /proc/sys/kernel/randomize_va_space
1660 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1662 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1663 with UP alternatives
1665 noresidual [PPC] Don't use residual data on PReP machines.
1667 noresume [SWSUSP] Disables resume and restores original swap
1668 space.
1670 no-scroll [VGA] Disables scrollback.
1671 This is required for the Braillex ib80-piezo Braille
1672 reader made by F.H. Papenmeier (Germany).
1674 nosbagart [IA-64]
1676 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1678 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1679 and disable the IO APIC. legacy for "maxcpus=0".
1681 nosoftlockup [KNL] Disable the soft-lockup detector.
1683 noswapaccount [KNL] Disable accounting of swap in memory resource
1684 controller. (See Documentation/cgroups/memory.txt)
1686 nosync [HW,M68K] Disables sync negotiation for all devices.
1688 notsc [BUGS=X86-32] Disable Time Stamp Counter
1690 nousb [USB] Disable the USB subsystem
1692 nowb [ARM]
1694 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1696 nptcg= [IA64] Override max number of concurrent global TLB
1697 purges which is reported from either PAL_VM_SUMMARY or
1698 SAL PALO.
1700 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1702 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1703 one of ['zone', 'node', 'default'] can be specified
1704 This can be set from sysctl after boot.
1705 See Documentation/sysctl/vm.txt for details.
1707 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1708 See Documentation/debugging-via-ohci1394.txt for more
1709 info.
1711 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1712 Rather than timing out after 20 ms if an EC
1713 command is not properly ACKed, override the length
1714 of the timeout. We have interrupts disabled while
1715 waiting for the ACK, so if this is set too high
1716 interrupts *may* be lost!
1718 opl3= [HW,OSS]
1719 Format: <io>
1721 oprofile.timer= [HW]
1722 Use timer interrupt instead of performance counters
1724 oprofile.cpu_type= Force an oprofile cpu type
1725 This might be useful if you have an older oprofile
1726 userland or if you want common events.
1727 Format: { arch_perfmon }
1728 arch_perfmon: [X86] Force use of architectural
1729 perfmon on Intel CPUs instead of the
1730 CPU specific event set.
1732 osst= [HW,SCSI] SCSI Tape Driver
1733 Format: <buffer_size>,<write_threshold>
1734 See also Documentation/scsi/st.txt.
1736 panic= [KNL] Kernel behaviour on panic
1737 Format: <timeout>
1739 parkbd.port= [HW] Parallel port number the keyboard adapter is
1740 connected to, default is 0.
1741 Format: <parport#>
1742 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1743 0 for XT, 1 for AT (default is AT).
1744 Format: <mode>
1746 parport= [HW,PPT] Specify parallel ports. 0 disables.
1747 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1748 Use 'auto' to force the driver to use any
1749 IRQ/DMA settings detected (the default is to
1750 ignore detected IRQ/DMA settings because of
1751 possible conflicts). You can specify the base
1752 address, IRQ, and DMA settings; IRQ and DMA
1753 should be numbers, or 'auto' (for using detected
1754 settings on that particular port), or 'nofifo'
1755 (to avoid using a FIFO even if it is detected).
1756 Parallel ports are assigned in the order they
1757 are specified on the command line, starting
1758 with parport0.
1760 parport_init_mode= [HW,PPT]
1761 Configure VIA parallel port to operate in
1762 a specific mode. This is necessary on Pegasos
1763 computer where firmware has no options for setting
1764 up parallel port mode and sets it to spp.
1765 Currently this function knows 686a and 8231 chips.
1766 Format: [spp|ps2|epp|ecp|ecpepp]
1768 pas2= [HW,OSS] Format:
1769 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1771 pas16= [HW,SCSI]
1772 See header of drivers/scsi/pas16.c.
1774 pause_on_oops=
1775 Halt all CPUs after the first oops has been printed for
1776 the specified number of seconds. This is to be used if
1777 your oopses keep scrolling off the screen.
1779 pcbit= [HW,ISDN]
1781 pcd. [PARIDE]
1782 See header of drivers/block/paride/pcd.c.
1783 See also Documentation/blockdev/paride.txt.
1785 pci=option[,option...] [PCI] various PCI subsystem options:
1786 earlydump [X86] dump PCI config space before the kernel
1787 changes anything
1788 off [X86] don't probe for the PCI bus
1789 bios [X86-32] force use of PCI BIOS, don't access
1790 the hardware directly. Use this if your machine
1791 has a non-standard PCI host bridge.
1792 nobios [X86-32] disallow use of PCI BIOS, only direct
1793 hardware access methods are allowed. Use this
1794 if you experience crashes upon bootup and you
1795 suspect they are caused by the BIOS.
1796 conf1 [X86] Force use of PCI Configuration
1797 Mechanism 1.
1798 conf2 [X86] Force use of PCI Configuration
1799 Mechanism 2.
1800 noaer [PCIE] If the PCIEAER kernel config parameter is
1801 enabled, this kernel boot option can be used to
1802 disable the use of PCIE advanced error reporting.
1803 nodomains [PCI] Disable support for multiple PCI
1804 root domains (aka PCI segments, in ACPI-speak).
1805 nommconf [X86] Disable use of MMCONFIG for PCI
1806 Configuration
1807 check_enable_amd_mmconf [X86] check for and enable
1808 properly configured MMIO access to PCI
1809 config space on AMD family 10h CPU
1810 nomsi [MSI] If the PCI_MSI kernel config parameter is
1811 enabled, this kernel boot option can be used to
1812 disable the use of MSI interrupts system-wide.
1813 noioapicquirk [APIC] Disable all boot interrupt quirks.
1814 Safety option to keep boot IRQs enabled. This
1815 should never be necessary.
1816 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1817 primary IO-APIC for bridges that cannot disable
1818 boot IRQs. This fixes a source of spurious IRQs
1819 when the system masks IRQs.
1820 noioapicreroute [APIC] Disable workaround that uses the
1821 boot IRQ equivalent of an IRQ that connects to
1822 a chipset where boot IRQs cannot be disabled.
1823 The opposite of ioapicreroute.
1824 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1825 routing table. These calls are known to be buggy
1826 on several machines and they hang the machine
1827 when used, but on other computers it's the only
1828 way to get the interrupt routing table. Try
1829 this option if the kernel is unable to allocate
1830 IRQs or discover secondary PCI buses on your
1831 motherboard.
1832 rom [X86] Assign address space to expansion ROMs.
1833 Use with caution as certain devices share
1834 address decoders between ROMs and other
1835 resources.
1836 norom [X86] Do not assign address space to
1837 expansion ROMs that do not already have
1838 BIOS assigned address ranges.
1839 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1840 assigned automatically to PCI devices. You can
1841 make the kernel exclude IRQs of your ISA cards
1842 this way.
1843 pirqaddr=0xAAAAA [X86] Specify the physical address
1844 of the PIRQ table (normally generated
1845 by the BIOS) if it is outside the
1846 F0000h-100000h range.
1847 lastbus=N [X86] Scan all buses thru bus #N. Can be
1848 useful if the kernel is unable to find your
1849 secondary buses and you want to tell it
1850 explicitly which ones they are.
1851 assign-busses [X86] Always assign all PCI bus
1852 numbers ourselves, overriding
1853 whatever the firmware may have done.
1854 usepirqmask [X86] Honor the possible IRQ mask stored
1855 in the BIOS $PIR table. This is needed on
1856 some systems with broken BIOSes, notably
1857 some HP Pavilion N5400 and Omnibook XE3
1858 notebooks. This will have no effect if ACPI
1859 IRQ routing is enabled.
1860 noacpi [X86] Do not use ACPI for IRQ routing
1861 or for PCI scanning.
1862 use_crs [X86] Use _CRS for PCI resource
1863 allocation.
1864 routeirq Do IRQ routing for all PCI devices.
1865 This is normally done in pci_enable_device(),
1866 so this option is a temporary workaround
1867 for broken drivers that don't call it.
1868 skip_isa_align [X86] do not align io start addr, so can
1869 handle more pci cards
1870 firmware [ARM] Do not re-enumerate the bus but instead
1871 just use the configuration from the
1872 bootloader. This is currently used on
1873 IXP2000 systems where the bus has to be
1874 configured a certain way for adjunct CPUs.
1875 noearly [X86] Don't do any early type 1 scanning.
1876 This might help on some broken boards which
1877 machine check when some devices' config space
1878 is read. But various workarounds are disabled
1879 and some IOMMU drivers will not work.
1880 bfsort Sort PCI devices into breadth-first order.
1881 This sorting is done to get a device
1882 order compatible with older (<= 2.4) kernels.
1883 nobfsort Don't sort PCI devices into breadth-first order.
1884 cbiosize=nn[KMG] The fixed amount of bus space which is
1885 reserved for the CardBus bridge's IO window.
1886 The default value is 256 bytes.
1887 cbmemsize=nn[KMG] The fixed amount of bus space which is
1888 reserved for the CardBus bridge's memory
1889 window. The default value is 64 megabytes.
1890 resource_alignment=
1891 Format:
1892 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1893 Specifies alignment and device to reassign
1894 aligned memory resources.
1895 If <order of align> is not specified,
1896 PAGE_SIZE is used as alignment.
1897 PCI-PCI bridge can be specified, if resource
1898 windows need to be expanded.
1899 ecrc= Enable/disable PCIe ECRC (transaction layer
1900 end-to-end CRC checking).
1901 bios: Use BIOS/firmware settings. This is the
1902 the default.
1903 off: Turn ECRC off
1904 on: Turn ECRC on.
1906 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1907 Management.
1908 off Disable ASPM.
1909 force Enable ASPM even on devices that claim not to support it.
1910 WARNING: Forcing ASPM on may cause system lockups.
1912 pcmv= [HW,PCMCIA] BadgePAD 4
1914 pd. [PARIDE]
1915 See Documentation/blockdev/paride.txt.
1917 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1918 boot time.
1919 Format: { 0 | 1 }
1920 See arch/parisc/kernel/pdc_chassis.c
1922 percpu_alloc= [X86] Select which percpu first chunk allocator to use.
1923 Allowed values are one of "lpage", "embed" and "4k".
1924 See comments in arch/x86/kernel/setup_percpu.c for
1925 details on each allocator. This parameter is primarily
1926 for debugging and performance comparison.
1928 pf. [PARIDE]
1929 See Documentation/blockdev/paride.txt.
1931 pg. [PARIDE]
1932 See Documentation/blockdev/paride.txt.
1934 pirq= [SMP,APIC] Manual mp-table setup
1935 See Documentation/x86/i386/IO-APIC.txt.
1937 plip= [PPT,NET] Parallel port network link
1938 Format: { parport<nr> | timid | 0 }
1939 See also Documentation/parport.txt.
1941 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1942 Override pmtimer IOPort with a hex value.
1943 e.g. pmtmr=0x508
1945 pnp.debug [PNP]
1946 Enable PNP debug messages. This depends on the
1947 CONFIG_PNP_DEBUG_MESSAGES option.
1949 pnpacpi= [ACPI]
1950 { off }
1952 pnpbios= [ISAPNP]
1953 { on | off | curr | res | no-curr | no-res }
1955 pnp_reserve_irq=
1956 [ISAPNP] Exclude IRQs for the autoconfiguration
1958 pnp_reserve_dma=
1959 [ISAPNP] Exclude DMAs for the autoconfiguration
1961 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1962 Ranges are in pairs (I/O port base and size).
1964 pnp_reserve_mem=
1965 [ISAPNP] Exclude memory regions for the
1966 autoconfiguration.
1967 Ranges are in pairs (memory base and size).
1969 ports= [IP_VS_FTP] IPVS ftp helper module
1970 Default is 21.
1971 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1972 may be specified.
1973 Format: <port>,<port>....
1975 print-fatal-signals=
1976 [KNL] debug: print fatal signals
1977 print-fatal-signals=1: print segfault info to
1978 the kernel console.
1979 default: off.
1981 printk.time= Show timing data prefixed to each printk message line
1982 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1984 processor.max_cstate= [HW,ACPI]
1985 Limit processor to maximum C-state
1986 max_cstate=9 overrides any DMI blacklist limit.
1988 processor.nocst [HW,ACPI]
1989 Ignore the _CST method to determine C-states,
1990 instead using the legacy FADT method
1992 profile= [KNL] Enable kernel profiling via /proc/profile
1993 Format: [schedule,]<number>
1994 Param: "schedule" - profile schedule points.
1995 Param: <number> - step/bucket size as a power of 2 for
1996 statistical time based profiling.
1997 Param: "sleep" - profile D-state sleeping (millisecs).
1998 Requires CONFIG_SCHEDSTATS
1999 Param: "kvm" - profile VM exits.
2001 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2002 before loading.
2003 See Documentation/blockdev/ramdisk.txt.
2005 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2006 probe for; one of (bare|imps|exps|lifebook|any).
2007 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2008 per second.
2009 psmouse.resetafter= [HW,MOUSE]
2010 Try to reset the device after so many bad packets
2011 (0 = never).
2012 psmouse.resolution=
2013 [HW,MOUSE] Set desired mouse resolution, in dpi.
2014 psmouse.smartscroll=
2015 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2016 0 = disabled, 1 = enabled (default).
2018 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2019 Format:
2020 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2022 pt. [PARIDE]
2023 See Documentation/blockdev/paride.txt.
2025 pty.legacy_count=
2026 [KNL] Number of legacy pty's. Overwrites compiled-in
2027 default number.
2029 quiet [KNL] Disable most log messages
2031 r128= [HW,DRM]
2033 raid= [HW,RAID]
2034 See Documentation/md.txt.
2036 ramdisk_blocksize= [RAM]
2037 See Documentation/blockdev/ramdisk.txt.
2039 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2040 See Documentation/blockdev/ramdisk.txt.
2042 rcupdate.blimit= [KNL,BOOT]
2043 Set maximum number of finished RCU callbacks to process
2044 in one batch.
2046 rcupdate.qhimark= [KNL,BOOT]
2047 Set threshold of queued
2048 RCU callbacks over which batch limiting is disabled.
2050 rcupdate.qlowmark= [KNL,BOOT]
2051 Set threshold of queued RCU callbacks below which
2052 batch limiting is re-enabled.
2054 rdinit= [KNL]
2055 Format: <full_path>
2056 Run specified binary instead of /init from the ramdisk,
2057 used for early userspace startup. See initrd.
2059 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2060 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2061 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2063 relax_domain_level=
2064 [KNL, SMP] Set scheduler's default relax_domain_level.
2065 See Documentation/cgroups/cpusets.txt.
2067 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2069 reservetop= [X86-32]
2070 Format: nn[KMG]
2071 Reserves a hole at the top of the kernel virtual
2072 address space.
2074 reset_devices [KNL] Force drivers to reset the underlying device
2075 during initialization.
2077 resume= [SWSUSP]
2078 Specify the partition device for software suspend
2080 resume_offset= [SWSUSP]
2081 Specify the offset from the beginning of the partition
2082 given by "resume=" at which the swap header is located,
2083 in <PAGE_SIZE> units (needed only for swap files).
2084 See Documentation/power/swsusp-and-swap-files.txt
2086 retain_initrd [RAM] Keep initrd memory after extraction
2088 rhash_entries= [KNL,NET]
2089 Set number of hash buckets for route cache
2091 riscom8= [HW,SERIAL]
2092 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2094 ro [KNL] Mount root device read-only on boot
2096 root= [KNL] Root filesystem
2098 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2099 mount the root filesystem
2101 rootflags= [KNL] Set root filesystem mount option string
2103 rootfstype= [KNL] Set root filesystem type
2105 rootwait [KNL] Wait (indefinitely) for root device to show up.
2106 Useful for devices that are detected asynchronously
2107 (e.g. USB and MMC devices).
2109 root_plug.vendor_id=
2110 [ROOTPLUG] Override the default vendor ID
2112 root_plug.product_id=
2113 [ROOTPLUG] Override the default product ID
2115 root_plug.debug=
2116 [ROOTPLUG] Enable debugging output
2118 rw [KNL] Mount root device read-write on boot
2120 S [KNL] Run init in single mode
2122 sa1100ir [NET]
2123 See drivers/net/irda/sa1100_ir.c.
2125 sbni= [NET] Granch SBNI12 leased line adapter
2127 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2128 Format: <io>[,<timeout>[,<isapnp>]]
2130 scsi_debug_*= [SCSI]
2131 See drivers/scsi/scsi_debug.c.
2133 scsi_default_dev_flags=
2134 [SCSI] SCSI default device flags
2135 Format: <integer>
2137 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2138 Format: <vendor>:<model>:<flags>
2139 (flags are integer value)
2141 scsi_logging_level= [SCSI] a bit mask of logging levels
2142 See drivers/scsi/scsi_logging.h for bits. Also
2143 settable via sysctl at dev.scsi.logging_level
2144 (/proc/sys/dev/scsi/logging_level).
2145 There is also a nice 'scsi_logging_level' script in the
2146 S390-tools package, available for download at
2147 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2149 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2150 discovered. async scans them in kernel threads,
2151 allowing boot to proceed. none ignores them, expecting
2152 user space to do the scan.
2154 security= [SECURITY] Choose a security module to enable at boot.
2155 If this boot parameter is not specified, only the first
2156 security module asking for security registration will be
2157 loaded. An invalid security module name will be treated
2158 as if no module has been chosen.
2160 selinux= [SELINUX] Disable or enable SELinux at boot time.
2161 Format: { "0" | "1" }
2162 See security/selinux/Kconfig help text.
2163 0 -- disable.
2164 1 -- enable.
2165 Default value is set via kernel config option.
2166 If enabled at boot time, /selinux/disable can be used
2167 later to disable prior to initial policy load.
2169 serialnumber [BUGS=X86-32]
2171 shapers= [NET]
2172 Maximal number of shapers.
2174 show_msr= [x86] show boot-time MSR settings
2175 Format: { <integer> }
2176 Show boot-time (BIOS-initialized) MSR settings.
2177 The parameter means the number of CPUs to show,
2178 for example 1 means boot CPU only.
2180 sim710= [SCSI,HW]
2181 See header of drivers/scsi/sim710.c.
2183 simeth= [IA-64]
2184 simscsi=
2186 slram= [HW,MTD]
2188 slub_debug[=options[,slabs]] [MM, SLUB]
2189 Enabling slub_debug allows one to determine the
2190 culprit if slab objects become corrupted. Enabling
2191 slub_debug can create guard zones around objects and
2192 may poison objects when not in use. Also tracks the
2193 last alloc / free. For more information see
2194 Documentation/vm/slub.txt.
2196 slub_max_order= [MM, SLUB]
2197 Determines the maximum allowed order for slabs.
2198 A high setting may cause OOMs due to memory
2199 fragmentation. For more information see
2200 Documentation/vm/slub.txt.
2202 slub_min_objects= [MM, SLUB]
2203 The minimum number of objects per slab. SLUB will
2204 increase the slab order up to slub_max_order to
2205 generate a sufficiently large slab able to contain
2206 the number of objects indicated. The higher the number
2207 of objects the smaller the overhead of tracking slabs
2208 and the less frequently locks need to be acquired.
2209 For more information see Documentation/vm/slub.txt.
2211 slub_min_order= [MM, SLUB]
2212 Determines the mininum page order for slabs. Must be
2213 lower than slub_max_order.
2214 For more information see Documentation/vm/slub.txt.
2216 slub_nomerge [MM, SLUB]
2217 Disable merging of slabs with similar size. May be
2218 necessary if there is some reason to distinguish
2219 allocs to different slabs. Debug options disable
2220 merging on their own.
2221 For more information see Documentation/vm/slub.txt.
2223 smart2= [HW]
2224 Format: <io1>[,<io2>[,...,<io8>]]
2226 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2227 attempt to substitute SMP alternatives once at boot.
2229 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2230 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2231 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2232 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2233 smsc-ircc2.ircc_irq= [HW] IRQ line
2234 smsc-ircc2.ircc_dma= [HW] DMA channel
2235 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2236 0: Toshiba Satellite 1800 (GP data pin select)
2237 1: Fast pin select (default)
2238 2: ATC IRMode
2240 snd-ad1816a= [HW,ALSA]
2242 snd-ad1848= [HW,ALSA]
2244 snd-ali5451= [HW,ALSA]
2246 snd-als100= [HW,ALSA]
2248 snd-als4000= [HW,ALSA]
2250 snd-azt2320= [HW,ALSA]
2252 snd-cmi8330= [HW,ALSA]
2254 snd-cmipci= [HW,ALSA]
2256 snd-cs4231= [HW,ALSA]
2258 snd-cs4232= [HW,ALSA]
2260 snd-cs4236= [HW,ALSA]
2262 snd-cs4281= [HW,ALSA]
2264 snd-cs46xx= [HW,ALSA]
2266 snd-dt019x= [HW,ALSA]
2268 snd-dummy= [HW,ALSA]
2270 snd-emu10k1= [HW,ALSA]
2272 snd-ens1370= [HW,ALSA]
2274 snd-ens1371= [HW,ALSA]
2276 snd-es968= [HW,ALSA]
2278 snd-es1688= [HW,ALSA]
2280 snd-es18xx= [HW,ALSA]
2282 snd-es1938= [HW,ALSA]
2284 snd-es1968= [HW,ALSA]
2286 snd-fm801= [HW,ALSA]
2288 snd-gusclassic= [HW,ALSA]
2290 snd-gusextreme= [HW,ALSA]
2292 snd-gusmax= [HW,ALSA]
2294 snd-hdsp= [HW,ALSA]
2296 snd-ice1712= [HW,ALSA]
2298 snd-intel8x0= [HW,ALSA]
2300 snd-interwave= [HW,ALSA]
2302 snd-interwave-stb=
2303 [HW,ALSA]
2305 snd-korg1212= [HW,ALSA]
2307 snd-maestro3= [HW,ALSA]
2309 snd-mpu401= [HW,ALSA]
2311 snd-mtpav= [HW,ALSA]
2313 snd-nm256= [HW,ALSA]
2315 snd-opl3sa2= [HW,ALSA]
2317 snd-opti92x-ad1848=
2318 [HW,ALSA]
2320 snd-opti92x-cs4231=
2321 [HW,ALSA]
2323 snd-opti93x= [HW,ALSA]
2325 snd-pmac= [HW,ALSA]
2327 snd-rme32= [HW,ALSA]
2329 snd-rme96= [HW,ALSA]
2331 snd-rme9652= [HW,ALSA]
2333 snd-sb8= [HW,ALSA]
2335 snd-sb16= [HW,ALSA]
2337 snd-sbawe= [HW,ALSA]
2339 snd-serial= [HW,ALSA]
2341 snd-sgalaxy= [HW,ALSA]
2343 snd-sonicvibes= [HW,ALSA]
2345 snd-sun-amd7930=
2346 [HW,ALSA]
2348 snd-sun-cs4231= [HW,ALSA]
2350 snd-trident= [HW,ALSA]
2352 snd-usb-audio= [HW,ALSA,USB]
2354 snd-via82xx= [HW,ALSA]
2356 snd-virmidi= [HW,ALSA]
2358 snd-wavefront= [HW,ALSA]
2360 snd-ymfpci= [HW,ALSA]
2362 softlockup_panic=
2363 [KNL] Should the soft-lockup detector generate panics.
2365 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2366 See Documentation/sonypi.txt
2368 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2369 See Documentation/serial/specialix.txt.
2371 spia_io_base= [HW,MTD]
2372 spia_fio_base=
2373 spia_pedr=
2374 spia_peddr=
2376 sscape= [HW,OSS]
2377 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2379 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2380 See Documentation/scsi/st.txt.
2382 stacktrace [FTRACE]
2383 Enabled the stack tracer on boot up.
2385 sti= [PARISC,HW]
2386 Format: <num>
2387 Set the STI (builtin display/keyboard on the HP-PARISC
2388 machines) console (graphic card) which should be used
2389 as the initial boot-console.
2390 See also comment in drivers/video/console/sticore.c.
2392 sti_font= [HW]
2393 See comment in drivers/video/console/sticore.c.
2395 stifb= [HW]
2396 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2398 sunrpc.pool_mode=
2399 [NFS]
2400 Control how the NFS server code allocates CPUs to
2401 service thread pools. Depending on how many NICs
2402 you have and where their interrupts are bound, this
2403 option will affect which CPUs will do NFS serving.
2404 Note: this parameter cannot be changed while the
2405 NFS server is running.
2407 auto the server chooses an appropriate mode
2408 automatically using heuristics
2409 global a single global pool contains all CPUs
2410 percpu one pool for each CPU
2411 pernode one pool for each NUMA node (equivalent
2412 to global on non-NUMA machines)
2414 swiotlb= [IA-64] Number of I/O TLB slabs
2416 switches= [HW,M68k]
2418 sym53c416= [HW,SCSI]
2419 See header of drivers/scsi/sym53c416.c.
2421 sysrq_always_enabled
2422 [KNL]
2423 Ignore sysrq setting - this boot parameter will
2424 neutralize any effect of /proc/sys/kernel/sysrq.
2425 Useful for debugging.
2427 t128= [HW,SCSI]
2428 See header of drivers/scsi/t128.c.
2430 tdfx= [HW,DRM]
2432 test_suspend= [SUSPEND]
2433 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2434 standby suspend) as the system sleep state to briefly
2435 enter during system startup. The system is woken from
2436 this state using a wakeup-capable RTC alarm.
2438 thash_entries= [KNL,NET]
2439 Set number of hash buckets for TCP connection
2441 thermal.act= [HW,ACPI]
2442 -1: disable all active trip points in all thermal zones
2443 <degrees C>: override all lowest active trip points
2445 thermal.crt= [HW,ACPI]
2446 -1: disable all critical trip points in all thermal zones
2447 <degrees C>: override all critical trip points
2449 thermal.nocrt= [HW,ACPI]
2450 Set to disable actions on ACPI thermal zone
2451 critical and hot trip points.
2453 thermal.off= [HW,ACPI]
2454 1: disable ACPI thermal control
2456 thermal.psv= [HW,ACPI]
2457 -1: disable all passive trip points
2458 <degrees C>: override all passive trip points to this
2459 value
2461 thermal.tzp= [HW,ACPI]
2462 Specify global default ACPI thermal zone polling rate
2463 <deci-seconds>: poll all this frequency
2464 0: no polling (default)
2466 tmscsim= [HW,SCSI]
2467 See comment before function dc390_setup() in
2468 drivers/scsi/tmscsim.c.
2470 topology= [S390]
2471 Format: {off | on}
2472 Specify if the kernel should make use of the cpu
2473 topology informations if the hardware supports these.
2474 The scheduler will make use of these informations and
2475 e.g. base its process migration decisions on it.
2476 Default is off.
2478 tp720= [HW,PS2]
2480 trace_buf_size=nn[KMG]
2481 [FTRACE] will set tracing buffer size.
2483 trix= [HW,OSS] MediaTrix AudioTrix Pro
2484 Format:
2485 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2487 tsc= Disable clocksource-must-verify flag for TSC.
2488 Format: <string>
2489 [x86] reliable: mark tsc clocksource as reliable, this
2490 disables clocksource verification at runtime.
2491 Used to enable high-resolution timer mode on older
2492 hardware, and in virtualized environment.
2494 turbografx.map[2|3]= [HW,JOY]
2495 TurboGraFX parallel port interface
2496 Format:
2497 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2498 See also Documentation/input/joystick-parport.txt
2500 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2501 See header of drivers/scsi/u14-34f.c.
2503 uart401= [HW,OSS]
2504 Format: <io>,<irq>
2506 uart6850= [HW,OSS]
2507 Format: <io>,<irq>
2509 uhci-hcd.ignore_oc=
2510 [USB] Ignore overcurrent events (default N).
2511 Some badly-designed motherboards generate lots of
2512 bogus events, for ports that aren't wired to
2513 anything. Set this parameter to avoid log spamming.
2514 Note that genuine overcurrent events won't be
2515 reported either.
2517 unknown_nmi_panic
2518 [X86]
2519 Set unknown_nmi_panic=1 early on boot.
2521 usbcore.autosuspend=
2522 [USB] The autosuspend time delay (in seconds) used
2523 for newly-detected USB devices (default 2). This
2524 is the time required before an idle device will be
2525 autosuspended. Devices for which the delay is set
2526 to a negative value won't be autosuspended at all.
2528 usbcore.usbfs_snoop=
2529 [USB] Set to log all usbfs traffic (default 0 = off).
2531 usbcore.blinkenlights=
2532 [USB] Set to cycle leds on hubs (default 0 = off).
2534 usbcore.old_scheme_first=
2535 [USB] Start with the old device initialization
2536 scheme (default 0 = off).
2538 usbcore.use_both_schemes=
2539 [USB] Try the other device initialization scheme
2540 if the first one fails (default 1 = enabled).
2542 usbcore.initial_descriptor_timeout=
2543 [USB] Specifies timeout for the initial 64-byte
2544 USB_REQ_GET_DESCRIPTOR request in milliseconds
2545 (default 5000 = 5.0 seconds).
2547 usbhid.mousepoll=
2548 [USBHID] The interval which mice are to be polled at.
2550 usb-storage.delay_use=
2551 [UMS] The delay in seconds before a new device is
2552 scanned for Logical Units (default 5).
2554 usb-storage.quirks=
2555 [UMS] A list of quirks entries to supplement or
2556 override the built-in unusual_devs list. List
2557 entries are separated by commas. Each entry has
2558 the form VID:PID:Flags where VID and PID are Vendor
2559 and Product ID values (4-digit hex numbers) and
2560 Flags is a set of characters, each corresponding
2561 to a common usb-storage quirk flag as follows:
2562 a = SANE_SENSE (collect more than 18 bytes
2563 of sense data);
2564 c = FIX_CAPACITY (decrease the reported
2565 device capacity by one sector);
2566 h = CAPACITY_HEURISTICS (decrease the
2567 reported device capacity by one
2568 sector if the number is odd);
2569 i = IGNORE_DEVICE (don't bind to this
2570 device);
2571 l = NOT_LOCKABLE (don't try to lock and
2572 unlock ejectable media);
2573 m = MAX_SECTORS_64 (don't transfer more
2574 than 64 sectors = 32 KB at a time);
2575 o = CAPACITY_OK (accept the capacity
2576 reported by the device);
2577 r = IGNORE_RESIDUE (the device reports
2578 bogus residue values);
2579 s = SINGLE_LUN (the device has only one
2580 Logical Unit);
2581 w = NO_WP_DETECT (don't test whether the
2582 medium is write-protected).
2583 Example: quirks=0419:aaf5:rl,0421:0433:rc
2585 vdso= [X86,SH]
2586 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2587 vdso=1: enable VDSO (default)
2588 vdso=0: disable VDSO mapping
2590 vdso32= [X86]
2591 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2592 vdso32=1: enable 32-bit VDSO (default)
2593 vdso32=0: disable 32-bit VDSO mapping
2595 vector= [IA-64,SMP]
2596 vector=percpu: enable percpu vector domain
2598 video= [FB] Frame buffer configuration
2599 See Documentation/fb/modedb.txt.
2601 vga= [BOOT,X86-32] Select a particular video mode
2602 See Documentation/x86/boot.txt and
2603 Documentation/svga.txt.
2604 Use vga=ask for menu.
2605 This is actually a boot loader parameter; the value is
2606 passed to the kernel using a special protocol.
2608 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2609 size of <nn>. This can be used to increase the
2610 minimum size (128MB on x86). It can also be used to
2611 decrease the size and leave more room for directly
2612 mapped kernel RAM.
2614 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2615 Format: <command>
2617 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2618 Format: <command>
2620 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2621 Format: <command>
2623 vt.default_blu= [VT]
2624 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2625 Change the default blue palette of the console.
2626 This is a 16-member array composed of values
2627 ranging from 0-255.
2629 vt.default_grn= [VT]
2630 Format: <green0>,<green1>,<green2>,...,<green15>
2631 Change the default green palette of the console.
2632 This is a 16-member array composed of values
2633 ranging from 0-255.
2635 vt.default_red= [VT]
2636 Format: <red0>,<red1>,<red2>,...,<red15>
2637 Change the default red palette of the console.
2638 This is a 16-member array composed of values
2639 ranging from 0-255.
2641 vt.default_utf8=
2642 [VT]
2643 Format=<0|1>
2644 Set system-wide default UTF-8 mode for all tty's.
2645 Default is 1, i.e. UTF-8 mode is enabled for all
2646 newly opened terminals.
2648 waveartist= [HW,OSS]
2649 Format: <io>,<irq>,<dma>,<dma2>
2651 wd33c93= [HW,SCSI]
2652 See header of drivers/scsi/wd33c93.c.
2654 wd7000= [HW,SCSI]
2655 See header of drivers/scsi/wd7000.c.
2657 wdt= [WDT] Watchdog
2658 See Documentation/watchdog/wdt.txt.
2660 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2661 default x2apic cluster mode on platforms
2662 supporting x2apic.
2664 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2665 xd_geo= See header of drivers/block/xd.c.
2667 xirc2ps_cs= [NET,PCMCIA]
2668 Format:
2669 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2671 ______________________________________________________________________
2673 TODO:
2675 Add documentation for ALSA options.
2676 Add more DRM drivers.