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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.power_nocheck= [HW,ACPI]
233 Format: 1/0 enable/disable the check of power state.
234 On some bogus BIOS the _PSC object/_STA object of
235 power resource can't return the correct device power
236 state. In such case it is unneccessary to check its
237 power state again in power transition.
238 1 : disable the power state check
240 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
241 Format: { level | edge | high | low }
243 acpi_serialize [HW,ACPI] force serialization of AML methods
245 acpi_skip_timer_override [HW,ACPI]
246 Recognize and ignore IRQ0/pin2 Interrupt Override.
247 For broken nForce2 BIOS resulting in XT-PIC timer.
249 acpi_sleep= [HW,ACPI] Sleep options
250 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
251 old_ordering, s4_nonvs }
252 See Documentation/power/video.txt for information on
253 s3_bios and s3_mode.
254 s3_beep is for debugging; it makes the PC's speaker beep
255 as soon as the kernel's real-mode entry point is called.
256 s4_nohwsig prevents ACPI hardware signature from being
257 used during resume from hibernation.
258 old_ordering causes the ACPI 1.0 ordering of the _PTS
259 control method, with respect to putting devices into
260 low power states, to be enforced (the ACPI 2.0 ordering
261 of _PTS is used by default).
262 s4_nonvs prevents the kernel from saving/restoring the
263 ACPI NVS memory during hibernation.
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
285 ad1848= [HW,OSS]
286 Format: <io>,<irq>,<dma>,<dma2>,<type>
288 add_efi_memmap [EFI; X86] Include EFI memory map in
289 kernel's map of available physical RAM.
291 advansys= [HW,SCSI]
292 See header of drivers/scsi/advansys.c.
294 advwdt= [HW,WDT] Advantech WDT
295 Format: <iostart>,<iostop>
297 aedsp16= [HW,OSS] Audio Excel DSP 16
298 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
299 See also header of sound/oss/aedsp16.c.
301 agp= [AGP]
302 { off | try_unsupported }
303 off: disable AGP support
304 try_unsupported: try to drive unsupported chipsets
305 (may crash computer or cause data corruption)
307 aha152x= [HW,SCSI]
308 See Documentation/scsi/aha152x.txt.
310 aha1542= [HW,SCSI]
311 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
313 aic7xxx= [HW,SCSI]
314 See Documentation/scsi/aic7xxx.txt.
316 aic79xx= [HW,SCSI]
317 See Documentation/scsi/aic79xx.txt.
319 amd_iommu= [HW,X86-84]
320 Pass parameters to the AMD IOMMU driver in the system.
321 Possible values are:
322 isolate - enable device isolation (each device, as far
323 as possible, will get its own protection
324 domain) [default]
325 share - put every device behind one IOMMU into the
326 same protection domain
327 fullflush - enable flushing of IO/TLB entries when
328 they are unmapped. Otherwise they are
329 flushed before they will be reused, which
330 is a lot of faster
332 amijoy.map= [HW,JOY] Amiga joystick support
333 Map of devices attached to JOY0DAT and JOY1DAT
334 Format: <a>,<b>
335 See also Documentation/kernel/input/joystick.txt
337 analog.map= [HW,JOY] Analog joystick and gamepad support
338 Specifies type or capabilities of an analog joystick
339 connected to one of 16 gameports
340 Format: <type1>,<type2>,..<type16>
342 apc= [HW,SPARC]
343 Power management functions (SPARCstation-4/5 + deriv.)
344 Format: noidle
345 Disable APC CPU standby support. SPARCstation-Fox does
346 not play well with APC CPU idle - disable it if you have
347 APC and your system crashes randomly.
349 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
350 Change the output verbosity whilst booting
351 Format: { quiet (default) | verbose | debug }
352 Change the amount of debugging information output
353 when initialising the APIC and IO-APIC components.
355 apm= [APM] Advanced Power Management
356 See header of arch/x86/kernel/apm_32.c.
358 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
359 Format: <io>,<irq>,<nodeID>
361 ataflop= [HW,M68k]
363 atarimouse= [HW,MOUSE] Atari Mouse
365 atascsi= [HW,SCSI] Atari SCSI
367 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
368 EzKey and similar keyboards
370 atkbd.reset= [HW] Reset keyboard during initialization
372 atkbd.set= [HW] Select keyboard code set
373 Format: <int> (2 = AT (default), 3 = PS/2)
375 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
376 keyboards
378 atkbd.softraw= [HW] Choose between synthetic and real raw mode
379 Format: <bool> (0 = real, 1 = synthetic (default))
381 atkbd.softrepeat= [HW]
382 Use software keyboard repeat
384 autotest [IA64]
386 baycom_epp= [HW,AX25]
387 Format: <io>,<mode>
389 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
390 Format: <io>,<mode>
391 See header of drivers/net/hamradio/baycom_par.c.
393 baycom_ser_fdx= [HW,AX25]
394 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
395 Format: <io>,<irq>,<mode>[,<baud>]
396 See header of drivers/net/hamradio/baycom_ser_fdx.c.
398 baycom_ser_hdx= [HW,AX25]
399 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
400 Format: <io>,<irq>,<mode>
401 See header of drivers/net/hamradio/baycom_ser_hdx.c.
403 boot_delay= Milliseconds to delay each printk during boot.
404 Values larger than 10 seconds (10000) are changed to
405 no delay (0).
406 Format: integer
408 bootmem_debug [KNL] Enable bootmem allocator debug messages.
410 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
411 bttv.radio= Most important insmod options are available as
412 kernel args too.
413 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
414 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
416 BusLogic= [HW,SCSI]
417 See drivers/scsi/BusLogic.c, comment before function
418 BusLogic_ParseDriverOptions().
420 c101= [NET] Moxa C101 synchronous serial card
422 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
423 Sometimes CPU hardware bugs make them report the cache
424 size incorrectly. The kernel will attempt work arounds
425 to fix known problems, but for some CPUs it is not
426 possible to determine what the correct size should be.
427 This option provides an override for these situations.
429 capability.disable=
430 [SECURITY] Disable capabilities. This would normally
431 be used only if an alternative security model is to be
432 configured. Potentially dangerous and should only be
433 used if you are entirely sure of the consequences.
435 ccw_timeout_log [S390]
436 See Documentation/s390/CommonIO for details.
438 cgroup_disable= [KNL] Disable a particular controller
439 Format: {name of the controller(s) to disable}
440 {Currently supported controllers - "memory"}
442 checkreqprot [SELINUX] Set initial checkreqprot flag value.
443 Format: { "0" | "1" }
444 See security/selinux/Kconfig help text.
445 0 -- check protection applied by kernel (includes
446 any implied execute protection).
447 1 -- check protection requested by application.
448 Default value is set via a kernel config option.
449 Value can be changed at runtime via
450 /selinux/checkreqprot.
452 cio_ignore= [S390]
453 See Documentation/s390/CommonIO for details.
455 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
456 [Deprecated]
457 Forces specified clocksource (if available) to be used
458 when calculating gettimeofday(). If specified
459 clocksource is not available, it defaults to PIT.
460 Format: { pit | tsc | cyclone | pmtmr }
462 clocksource= [GENERIC_TIME] Override the default clocksource
463 Format: <string>
464 Override the default clocksource and use the clocksource
465 with the name specified.
466 Some clocksource names to choose from, depending on
467 the platform:
468 [all] jiffies (this is the base, fallback clocksource)
469 [ACPI] acpi_pm
470 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
471 pxa_timer,timer3,32k_counter,timer0_1
472 [AVR32] avr32
473 [X86-32] pit,hpet,tsc,vmi-timer;
474 scx200_hrt on Geode; cyclone on IBM x440
475 [MIPS] MIPS
476 [PARISC] cr16
477 [S390] tod
478 [SH] SuperH
479 [SPARC64] tick
480 [X86-64] hpet,tsc
482 clearcpuid=BITNUM [X86]
483 Disable CPUID feature X for the kernel. See
484 arch/x86/include/asm/cpufeature.h for the valid bit
485 numbers. Note the Linux specific bits are not necessarily
486 stable over kernel options, but the vendor specific
487 ones should be.
488 Also note that user programs calling CPUID directly
489 or using the feature without checking anything
490 will still see it. This just prevents it from
491 being used by the kernel or shown in /proc/cpuinfo.
492 Also note the kernel might malfunction if you disable
493 some critical bits.
495 cmo_free_hint= [PPC] Format: { yes | no }
496 Specify whether pages are marked as being inactive
497 when they are freed. This is used in CMO environments
498 to determine OS memory pressure for page stealing by
499 a hypervisor.
500 Default: yes
502 code_bytes [X86] How many bytes of object code to print
503 in an oops report.
504 Range: 0 - 8192
505 Default: 64
507 com20020= [HW,NET] ARCnet - COM20020 chipset
508 Format:
509 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
511 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
512 Format: <io>[,<irq>]
514 com90xx= [HW,NET]
515 ARCnet - COM90xx chipset (memory-mapped buffers)
516 Format: <io>[,<irq>[,<memstart>]]
518 condev= [HW,S390] console device
519 conmode=
521 console= [KNL] Output console device and options.
523 tty<n> Use the virtual console device <n>.
525 ttyS<n>[,options]
526 ttyUSB0[,options]
527 Use the specified serial port. The options are of
528 the form "bbbbpnf", where "bbbb" is the baud rate,
529 "p" is parity ("n", "o", or "e"), "n" is number of
530 bits, and "f" is flow control ("r" for RTS or
531 omit it). Default is "9600n8".
533 See Documentation/serial-console.txt for more
534 information. See
535 Documentation/networking/netconsole.txt for an
536 alternative.
538 uart[8250],io,<addr>[,options]
539 uart[8250],mmio,<addr>[,options]
540 Start an early, polled-mode console on the 8250/16550
541 UART at the specified I/O port or MMIO address,
542 switching to the matching ttyS device later. The
543 options are the same as for ttyS, above.
545 If the device connected to the port is not a TTY but a braille
546 device, prepend "brl," before the device type, for instance
547 console=brl,ttyS0
548 For now, only VisioBraille is supported.
550 consoleblank= [KNL] The console blank (screen saver) timeout in
551 seconds. Defaults to 10*60 = 10mins. A value of 0
552 disables the blank timer.
554 coredump_filter=
555 [KNL] Change the default value for
556 /proc/<pid>/coredump_filter.
557 See also Documentation/filesystems/proc.txt.
559 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
560 Format:
561 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
563 crashkernel=nn[KMG]@ss[KMG]
564 [KNL] Reserve a chunk of physical memory to
565 hold a kernel to switch to with kexec on panic.
567 crashkernel=range1:size1[,range2:size2,...][@offset]
568 [KNL] Same as above, but depends on the memory
569 in the running system. The syntax of range is
570 start-[end] where start and end are both
571 a memory unit (amount[KMG]). See also
572 Documentation/kdump/kdump.txt for a example.
574 cs89x0_dma= [HW,NET]
575 Format: <dma>
577 cs89x0_media= [HW,NET]
578 Format: { rj45 | aui | bnc }
580 dasd= [HW,NET]
581 See header of drivers/s390/block/dasd_devmap.c.
583 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
584 (one device per port)
585 Format: <port#>,<type>
586 See also Documentation/input/joystick-parport.txt
588 debug [KNL] Enable kernel debugging (events log level).
590 debug_locks_verbose=
591 [KNL] verbose self-tests
592 Format=<0|1>
593 Print debugging info while doing the locking API
594 self-tests.
595 We default to 0 (no extra messages), setting it to
596 1 will print _a lot_ more information - normally
597 only useful to kernel developers.
599 debug_objects [KNL] Enable object debugging
601 no_debug_objects
602 [KNL] Disable object debugging
604 debugpat [X86] Enable PAT debugging
606 decnet.addr= [HW,NET]
607 Format: <area>[,<node>]
608 See also Documentation/networking/decnet.txt.
610 default_hugepagesz=
611 [same as hugepagesz=] The size of the default
612 HugeTLB page size. This is the size represented by
613 the legacy /proc/ hugepages APIs, used for SHM, and
614 default size when mounting hugetlbfs filesystems.
615 Defaults to the default architecture's huge page size
616 if not specified.
618 dhash_entries= [KNL]
619 Set number of hash buckets for dentry cache.
621 digi= [HW,SERIAL]
622 IO parameters + enable/disable command.
624 digiepca= [HW,SERIAL]
625 See drivers/char/README.epca and
626 Documentation/serial/digiepca.txt.
628 disable_mtrr_cleanup [X86]
629 The kernel tries to adjust MTRR layout from continuous
630 to discrete, to make X server driver able to add WB
631 entry later. This parameter disables that.
633 disable_mtrr_trim [X86, Intel and AMD only]
634 By default the kernel will trim any uncacheable
635 memory out of your available memory pool based on
636 MTRR settings. This parameter disables that behavior,
637 possibly causing your machine to run very slowly.
639 disable_timer_pin_1 [X86]
640 Disable PIN 1 of APIC timer
641 Can be useful to work around chipset bugs.
643 dmasound= [HW,OSS] Sound subsystem buffers
645 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
646 this option disables the debugging code at boot.
648 dma_debug_entries=<number>
649 This option allows to tune the number of preallocated
650 entries for DMA-API debugging code. One entry is
651 required per DMA-API allocation. Use this if the
652 DMA-API debugging code disables itself because the
653 architectural default is too low.
655 dma_debug_driver=<driver_name>
656 With this option the DMA-API debugging driver
657 filter feature can be enabled at boot time. Just
658 pass the driver to filter for as the parameter.
659 The filter can be disabled or changed to another
660 driver later using sysfs.
662 dscc4.setup= [NET]
664 dtc3181e= [HW,SCSI]
666 dynamic_printk Enables pr_debug()/dev_dbg() calls if
667 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
668 These can also be switched on/off via
669 <debugfs>/dynamic_printk/modules
671 earlycon= [KNL] Output early console device and options.
672 uart[8250],io,<addr>[,options]
673 uart[8250],mmio,<addr>[,options]
674 Start an early, polled-mode console on the 8250/16550
675 UART at the specified I/O port or MMIO address.
676 The options are the same as for ttyS, above.
678 earlyprintk= [X86,SH,BLACKFIN]
679 earlyprintk=vga
680 earlyprintk=serial[,ttySn[,baudrate]]
681 earlyprintk=dbgp
683 Append ",keep" to not disable it when the real console
684 takes over.
686 Only vga or serial or usb debug port at a time.
688 Currently only ttyS0 and ttyS1 are supported.
690 Interaction with the standard serial driver is not
691 very good.
693 The VGA output is eventually overwritten by the real
694 console.
696 eata= [HW,SCSI]
698 edd= [EDD]
699 Format: {"off" | "on" | "skip[mbr]"}
701 eisa_irq_edge= [PARISC,HW]
702 See header of drivers/parisc/eisa.c.
704 elanfreq= [X86-32]
705 See comment before function elanfreq_setup() in
706 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
708 elevator= [IOSCHED]
709 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
710 See Documentation/block/as-iosched.txt and
711 Documentation/block/deadline-iosched.txt for details.
713 elfcorehdr= [IA64,PPC,SH,X86]
714 Specifies physical address of start of kernel core
715 image elf header. Generally kexec loader will
716 pass this option to capture kernel.
717 See Documentation/kdump/kdump.txt for details.
719 enable_mtrr_cleanup [X86]
720 The kernel tries to adjust MTRR layout from continuous
721 to discrete, to make X server driver able to add WB
722 entry later. This parameter enables that.
724 enable_timer_pin_1 [X86]
725 Enable PIN 1 of APIC timer
726 Can be useful to work around chipset bugs
727 (in particular on some ATI chipsets).
728 The kernel tries to set a reasonable default.
730 enforcing [SELINUX] Set initial enforcing status.
731 Format: {"0" | "1"}
732 See security/selinux/Kconfig help text.
733 0 -- permissive (log only, no denials).
734 1 -- enforcing (deny and log).
735 Default value is 0.
736 Value can be changed at runtime via /selinux/enforce.
738 ether= [HW,NET] Ethernet cards parameters
739 This option is obsoleted by the "netdev=" option, which
740 has equivalent usage. See its documentation for details.
742 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
743 Format: <io>[,<irq>]
745 failslab=
746 fail_page_alloc=
747 fail_make_request=[KNL]
748 General fault injection mechanism.
749 Format: <interval>,<probability>,<space>,<times>
750 See also /Documentation/fault-injection/.
752 fd_mcs= [HW,SCSI]
753 See header of drivers/scsi/fd_mcs.c.
755 fdomain= [HW,SCSI]
756 See header of drivers/scsi/fdomain.c.
758 floppy= [HW]
759 See Documentation/blockdev/floppy.txt.
761 force_pal_cache_flush
762 [IA-64] Avoid check_sal_cache_flush which may hang on
763 buggy SAL_CACHE_FLUSH implementations. Using this
764 parameter will force ia64_sal_cache_flush to call
765 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
767 ftrace=[tracer]
768 [FTRACE] will set and start the specified tracer
769 as early as possible in order to facilitate early
770 boot debugging.
772 ftrace_dump_on_oops
773 [FTRACE] will dump the trace buffers on oops.
775 ftrace_filter=[function-list]
776 [FTRACE] Limit the functions traced by the function
777 tracer at boot up. function-list is a comma separated
778 list of functions. This list can be changed at run
779 time by the set_ftrace_filter file in the debugfs
780 tracing directory.
782 ftrace_notrace=[function-list]
783 [FTRACE] Do not trace the functions specified in
784 function-list. This list can be changed at run time
785 by the set_ftrace_notrace file in the debugfs
786 tracing directory.
788 gamecon.map[2|3]=
789 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
790 support via parallel port (up to 5 devices per port)
791 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
792 See also Documentation/input/joystick-parport.txt
794 gamma= [HW,DRM]
796 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
797 Format: off | on
798 default: on
800 gcov_persist= [GCOV] When non-zero (default), profiling data for
801 kernel modules is saved and remains accessible via
802 debugfs, even when the module is unloaded/reloaded.
803 When zero, profiling data is discarded and associated
804 debugfs files are removed at module unload time.
806 gdth= [HW,SCSI]
807 See header of drivers/scsi/gdth.c.
809 gpt [EFI] Forces disk with valid GPT signature but
810 invalid Protective MBR to be treated as GPT.
812 gvp11= [HW,SCSI]
814 hashdist= [KNL,NUMA] Large hashes allocated during boot
815 are distributed across NUMA nodes. Defaults on
816 for 64bit NUMA, off otherwise.
817 Format: 0 | 1 (for off | on)
819 hcl= [IA-64] SGI's Hardware Graph compatibility layer
821 hd= [EIDE] (E)IDE hard drive subsystem geometry
822 Format: <cyl>,<head>,<sect>
824 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
825 size of <nn>. This works even on boxes that have no
826 highmem otherwise. This also works to reduce highmem
827 size on bigger boxes.
829 highres= [KNL] Enable/disable high resolution timer mode.
830 Valid parameters: "on", "off"
831 Default: "on"
833 hisax= [HW,ISDN]
834 See Documentation/isdn/README.HiSax.
836 hlt [BUGS=ARM,SH]
838 hpet= [X86-32,HPET] option to control HPET usage
839 Format: { enable (default) | disable | force |
840 verbose }
841 disable: disable HPET and use PIT instead
842 force: allow force enabled of undocumented chips (ICH4,
843 VIA, nVidia)
844 verbose: show contents of HPET registers during setup
846 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
847 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
848 On x86-64 and powerpc, this option can be specified
849 multiple times interleaved with hugepages= to reserve
850 huge pages of different sizes. Valid pages sizes on
851 x86-64 are 2M (when the CPU supports "pse") and 1G
852 (when the CPU supports the "pdpe1gb" cpuinfo flag)
853 Note that 1GB pages can only be allocated at boot time
854 using hugepages= and not freed afterwards.
856 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
857 terminal devices. Valid values: 0..8
858 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
859 If specified, z/VM IUCV HVC accepts connections
860 from listed z/VM user IDs only.
862 i2c_bus= [HW] Override the default board specific I2C bus speed
863 or register an additional I2C bus that is not
864 registered from board initialization code.
865 Format:
866 <bus_id>,<clkrate>
868 i8042.debug [HW] Toggle i8042 debug mode
869 i8042.direct [HW] Put keyboard port into non-translated mode
870 i8042.dumbkbd [HW] Pretend that controller can only read data from
871 keyboard and cannot control its state
872 (Don't attempt to blink the leds)
873 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
874 i8042.nokbd [HW] Don't check/create keyboard port
875 i8042.noloop [HW] Disable the AUX Loopback command while probing
876 for the AUX port
877 i8042.nomux [HW] Don't check presence of an active multiplexing
878 controller
879 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
880 controllers
881 i8042.panicblink=
882 [HW] Frequency with which keyboard LEDs should blink
883 when kernel panics (default is 0.5 sec)
884 i8042.reset [HW] Reset the controller during init and cleanup
885 i8042.unlock [HW] Unlock (ignore) the keylock
887 i810= [HW,DRM]
889 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
890 indicates that the driver is running on unsupported
891 hardware.
892 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
893 does not match list of supported models.
894 i8k.power_status
895 [HW] Report power status in /proc/i8k
896 (disabled by default)
897 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
898 capability is set.
900 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
901 See Documentation/mca.txt.
903 icn= [HW,ISDN]
904 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
906 ide-core.nodma= [HW] (E)IDE subsystem
907 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
908 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
909 .cdrom .chs .ignore_cable are additional options
910 See Documentation/ide/ide.txt.
912 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
913 Claim all unknown PCI IDE storage controllers.
915 idle= [X86]
916 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
917 Poll forces a polling idle loop that can slightly
918 improve the performance of waking up a idle CPU, but
919 will use a lot of power and make the system run hot.
920 Not recommended.
921 idle=mwait: On systems which support MONITOR/MWAIT but
922 the kernel chose to not use it because it doesn't save
923 as much power as a normal idle loop, use the
924 MONITOR/MWAIT idle loop anyways. Performance should be
925 the same as idle=poll.
926 idle=halt: Halt is forced to be used for CPU idle.
927 In such case C2/C3 won't be used again.
928 idle=nomwait: Disable mwait for CPU C-states
930 ignore_loglevel [KNL]
931 Ignore loglevel setting - this will print /all/
932 kernel messages to the console. Useful for debugging.
934 ihash_entries= [KNL]
935 Set number of hash buckets for inode cache.
937 ima_audit= [IMA]
938 Format: { "0" | "1" }
939 0 -- integrity auditing messages. (Default)
940 1 -- enable informational integrity auditing messages.
942 ima_hash= [IMA]
943 Formt: { "sha1" | "md5" }
944 default: "sha1"
946 ima_tcb [IMA]
947 Load a policy which meets the needs of the Trusted
948 Computing Base. This means IMA will measure all
949 programs exec'd, files mmap'd for exec, and all files
950 opened for read by uid=0.
952 in2000= [HW,SCSI]
953 See header of drivers/scsi/in2000.c.
955 init= [KNL]
956 Format: <full_path>
957 Run specified binary instead of /sbin/init as init
958 process.
960 initcall_debug [KNL] Trace initcalls as they are executed. Useful
961 for working out where the kernel is dying during
962 startup.
964 initrd= [BOOT] Specify the location of the initial ramdisk
966 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
967 Format: <irq>
969 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
970 on
971 Enable intel iommu driver.
972 off
973 Disable intel iommu driver.
974 igfx_off [Default Off]
975 By default, gfx is mapped as normal device. If a gfx
976 device has a dedicated DMAR unit, the DMAR unit is
977 bypassed by not enabling DMAR with this option. In
978 this case, gfx device will use physical address for
979 DMA.
980 forcedac [x86_64]
981 With this option iommu will not optimize to look
982 for io virtual address below 32 bit forcing dual
983 address cycle on pci bus for cards supporting greater
984 than 32 bit addressing. The default is to look
985 for translation below 32 bit and if not available
986 then look in the higher range.
987 strict [Default Off]
988 With this option on every unmap_single operation will
989 result in a hardware IOTLB flush operation as opposed
990 to batching them for performance.
992 inttest= [IA64]
994 iomem= Disable strict checking of access to MMIO memory
995 strict regions from userspace.
996 relaxed
998 iommu= [x86]
999 off
1000 force
1001 noforce
1002 biomerge
1003 panic
1004 nopanic
1005 merge
1006 nomerge
1007 forcesac
1008 soft
1009 pt [x86, IA64]
1011 io7= [HW] IO7 for Marvel based alpha systems
1012 See comment before marvel_specify_io7 in
1013 arch/alpha/kernel/core_marvel.c.
1015 io_delay= [X86] I/O delay method
1016 0x80
1017 Standard port 0x80 based delay
1018 0xed
1019 Alternate port 0xed based delay (needed on some systems)
1020 udelay
1021 Simple two microseconds delay
1022 none
1023 No delay
1025 ip= [IP_PNP]
1026 See Documentation/filesystems/nfsroot.txt.
1028 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1029 See comment before ip2_setup() in
1030 drivers/char/ip2/ip2base.c.
1032 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1033 See header of drivers/scsi/ips.c.
1035 irqfixup [HW]
1036 When an interrupt is not handled search all handlers
1037 for it. Intended to get systems with badly broken
1038 firmware running.
1040 irqpoll [HW]
1041 When an interrupt is not handled search all handlers
1042 for it. Also check all handlers each timer
1043 interrupt. Intended to get systems with badly broken
1044 firmware running.
1046 isapnp= [ISAPNP]
1047 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1049 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1050 Format:
1051 <cpu number>,...,<cpu number>
1052 or
1053 <cpu number>-<cpu number>
1054 (must be a positive range in ascending order)
1055 or a mixture
1056 <cpu number>,...,<cpu number>-<cpu number>
1058 This option can be used to specify one or more CPUs
1059 to isolate from the general SMP balancing and scheduling
1060 algorithms. You can move a process onto or off an
1061 "isolated" CPU via the CPU affinity syscalls or cpuset.
1062 <cpu number> begins at 0 and the maximum value is
1063 "number of CPUs in system - 1".
1065 This option is the preferred way to isolate CPUs. The
1066 alternative -- manually setting the CPU mask of all
1067 tasks in the system -- can cause problems and
1068 suboptimal load balancer performance.
1070 iucv= [HW,NET]
1072 js= [HW,JOY] Analog joystick
1073 See Documentation/input/joystick.txt.
1075 keepinitrd [HW,ARM]
1077 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1078 specifies the amount of memory usable by the kernel
1079 for non-movable allocations. The requested amount is
1080 spread evenly throughout all nodes in the system. The
1081 remaining memory in each node is used for Movable
1082 pages. In the event, a node is too small to have both
1083 kernelcore and Movable pages, kernelcore pages will
1084 take priority and other nodes will have a larger number
1085 of kernelcore pages. The Movable zone is used for the
1086 allocation of pages that may be reclaimed or moved
1087 by the page migration subsystem. This means that
1088 HugeTLB pages may not be allocated from this zone.
1089 Note that allocations like PTEs-from-HighMem still
1090 use the HighMem zone if it exists, and the Normal
1091 zone if it does not.
1093 kgdboc= [HW] kgdb over consoles.
1094 Requires a tty driver that supports console polling.
1095 (only serial supported for now)
1096 Format: <serial_device>[,baud]
1098 kmac= [MIPS] korina ethernet MAC address.
1099 Configure the RouterBoard 532 series on-chip
1100 Ethernet adapter MAC address.
1102 kmemleak= [KNL] Boot-time kmemleak enable/disable
1103 Valid arguments: on, off
1104 Default: on
1106 kstack=N [X86] Print N words from the kernel stack
1107 in oops dumps.
1109 l2cr= [PPC]
1111 l3cr= [PPC]
1113 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1114 disabled it.
1116 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1117 in C2 power state.
1119 libata.dma= [LIBATA] DMA control
1120 libata.dma=0 Disable all PATA and SATA DMA
1121 libata.dma=1 PATA and SATA Disk DMA only
1122 libata.dma=2 ATAPI (CDROM) DMA only
1123 libata.dma=4 Compact Flash DMA only
1124 Combinations also work, so libata.dma=3 enables DMA
1125 for disks and CDROMs, but not CFs.
1127 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1128 when set.
1129 Format: <int>
1131 libata.force= [LIBATA] Force configurations. The format is comma
1132 separated list of "[ID:]VAL" where ID is
1133 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1134 matching port, link or device. Basically, it matches
1135 the ATA ID string printed on console by libata. If
1136 the whole ID part is omitted, the last PORT and DEVICE
1137 values are used. If ID hasn't been specified yet, the
1138 configuration applies to all ports, links and devices.
1140 If only DEVICE is omitted, the parameter applies to
1141 the port and all links and devices behind it. DEVICE
1142 number of 0 either selects the first device or the
1143 first fan-out link behind PMP device. It does not
1144 select the host link. DEVICE number of 15 selects the
1145 host link and device attached to it.
1147 The VAL specifies the configuration to force. As long
1148 as there's no ambiguity shortcut notation is allowed.
1149 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1150 The following configurations can be forced.
1152 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1153 Any ID with matching PORT is used.
1155 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1157 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1158 udma[/][16,25,33,44,66,100,133] notation is also
1159 allowed.
1161 * [no]ncq: Turn on or off NCQ.
1163 * nohrst, nosrst, norst: suppress hard, soft
1164 and both resets.
1166 If there are multiple matching configurations changing
1167 the same attribute, the last one is used.
1169 lmb=debug [KNL] Enable lmb debug messages.
1171 load_ramdisk= [RAM] List of ramdisks to load from floppy
1172 See Documentation/blockdev/ramdisk.txt.
1174 lockd.nlm_grace_period=P [NFS] Assign grace period.
1175 Format: <integer>
1177 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1178 Format: <integer>
1180 lockd.nlm_timeout=T [NFS] Assign timeout value.
1181 Format: <integer>
1183 lockd.nlm_udpport=M [NFS] Assign UDP port.
1184 Format: <integer>
1186 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1187 Format: <irq>
1189 loglevel= All Kernel Messages with a loglevel smaller than the
1190 console loglevel will be printed to the console. It can
1191 also be changed with klogd or other programs. The
1192 loglevels are defined as follows:
1194 0 (KERN_EMERG) system is unusable
1195 1 (KERN_ALERT) action must be taken immediately
1196 2 (KERN_CRIT) critical conditions
1197 3 (KERN_ERR) error conditions
1198 4 (KERN_WARNING) warning conditions
1199 5 (KERN_NOTICE) normal but significant condition
1200 6 (KERN_INFO) informational
1201 7 (KERN_DEBUG) debug-level messages
1203 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1204 Format: { n | nk | nM }
1205 n must be a power of two. The default size
1206 is set in the kernel config file.
1208 logo.nologo [FB] Disables display of the built-in Linux logo.
1209 This may be used to provide more screen space for
1210 kernel log messages and is useful when debugging
1211 kernel boot problems.
1213 lp=0 [LP] Specify parallel ports to use, e.g,
1214 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1215 lp=reset first parallel port). 'lp=0' disables the
1216 lp=auto printer driver. 'lp=reset' (which can be
1217 specified in addition to the ports) causes
1218 attached printers to be reset. Using
1219 lp=port1,port2,... specifies the parallel ports
1220 to associate lp devices with, starting with
1221 lp0. A port specification may be 'none' to skip
1222 that lp device, or a parport name such as
1223 'parport0'. Specifying 'lp=auto' instead of a
1224 port specification list means that device IDs
1225 from each port should be examined, to see if
1226 an IEEE 1284-compliant printer is attached; if
1227 so, the driver will manage that printer.
1228 See also header of drivers/char/lp.c.
1230 lpj=n [KNL]
1231 Sets loops_per_jiffy to given constant, thus avoiding
1232 time-consuming boot-time autodetection (up to 250 ms per
1233 CPU). 0 enables autodetection (default). To determine
1234 the correct value for your kernel, boot with normal
1235 autodetection and see what value is printed. Note that
1236 on SMP systems the preset will be applied to all CPUs,
1237 which is likely to cause problems if your CPUs need
1238 significantly divergent settings. An incorrect value
1239 will cause delays in the kernel to be wrong, leading to
1240 unpredictable I/O errors and other breakage. Although
1241 unlikely, in the extreme case this might damage your
1242 hardware.
1244 ltpc= [NET]
1245 Format: <io>,<irq>,<dma>
1247 mac5380= [HW,SCSI] Format:
1248 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1250 machvec= [IA64] Force the use of a particular machine-vector
1251 (machvec) in a generic kernel.
1252 Example: machvec=hpzx1_swiotlb
1254 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1255 than or equal to this physical address is ignored.
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
1261 the IO APIC.
1263 max_loop= [LOOP] Maximum number of loopback devices that can
1264 be mounted
1265 Format: <1-256>
1267 max_luns= [SCSI] Maximum number of LUNs to probe.
1268 Should be between 1 and 2^32-1.
1270 max_report_luns=
1271 [SCSI] Maximum number of LUNs received.
1272 Should be between 1 and 16384.
1274 mcatest= [IA-64]
1276 mce [X86-32] Machine Check Exception
1278 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1280 md= [HW] RAID subsystems devices and level
1281 See Documentation/md.txt.
1283 mdacon= [MDA]
1284 Format: <first>,<last>
1285 Specifies range of consoles to be captured by the MDA.
1287 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1288 Amount of memory to be used when the kernel is not able
1289 to see the whole system memory or for test.
1290 [X86-32] Use together with memmap= to avoid physical
1291 address space collisions. Without memmap= PCI devices
1292 could be placed at addresses belonging to unused RAM.
1294 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1295 memory.
1297 memchunk=nn[KMG]
1298 [KNL,SH] Allow user to override the default size for
1299 per-device physically contiguous DMA buffers.
1301 memmap=exactmap [KNL,X86] Enable setting of an exact
1302 E820 memory map, as specified by the user.
1303 Such memmap=exactmap lines can be constructed based on
1304 BIOS output or other requirements. See the memmap=nn@ss
1305 option description.
1307 memmap=nn[KMG]@ss[KMG]
1308 [KNL] Force usage of a specific region of memory
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 ACPI data.
1313 Region of memory to be used, from ss to ss+nn.
1315 memmap=nn[KMG]$ss[KMG]
1316 [KNL,ACPI] Mark specific memory as reserved.
1317 Region of memory to be used, from ss to ss+nn.
1318 Example: Exclude memory from 0x18690000-0x1869ffff
1319 memmap=64K$0x18690000
1320 or
1321 memmap=0x10000$0x18690000
1323 memory_corruption_check=0/1 [X86]
1324 Some BIOSes seem to corrupt the first 64k of
1325 memory when doing things like suspend/resume.
1326 Setting this option will scan the memory
1327 looking for corruption. Enabling this will
1328 both detect corruption and prevent the kernel
1329 from using the memory being corrupted.
1330 However, its intended as a diagnostic tool; if
1331 repeatable BIOS-originated corruption always
1332 affects the same memory, you can use memmap=
1333 to prevent the kernel from using that memory.
1335 memory_corruption_check_size=size [X86]
1336 By default it checks for corruption in the low
1337 64k, making this memory unavailable for normal
1338 use. Use this parameter to scan for
1339 corruption in more or less memory.
1341 memory_corruption_check_period=seconds [X86]
1342 By default it checks for corruption every 60
1343 seconds. Use this parameter to check at some
1344 other rate. 0 disables periodic checking.
1346 memtest= [KNL,X86] Enable memtest
1347 Format: <integer>
1348 default : 0 <disable>
1349 Specifies the number of memtest passes to be
1350 performed. Each pass selects another test
1351 pattern from a given set of patterns. Memtest
1352 fills the memory with this pattern, validates
1353 memory contents and reserves bad memory
1354 regions that are detected.
1356 meye.*= [HW] Set MotionEye Camera parameters
1357 See Documentation/video4linux/meye.txt.
1359 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1360 Multi-Function General Purpose Timers on AMD Geode
1361 platforms.
1363 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1364 the BIOS has incorrectly applied a workaround. TinyBIOS
1365 version 0.98 is known to be affected, 0.99 fixes the
1366 problem by letting the user disable the workaround.
1368 mga= [HW,DRM]
1370 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1371 physical address is ignored.
1373 mini2440= [ARM,HW,KNL]
1374 Format:[0..2][b][c][t]
1375 Default: "0tb"
1376 MINI2440 configuration specification:
1377 0 - The attached screen is the 3.5" TFT
1378 1 - The attached screen is the 7" TFT
1379 2 - The VGA Shield is attached (1024x768)
1380 Leaving out the screen size parameter will not load
1381 the TFT driver, and the framebuffer will be left
1382 unconfigured.
1383 b - Enable backlight. The TFT backlight pin will be
1384 linked to the kernel VESA blanking code and a GPIO
1385 LED. This parameter is not necessary when using the
1386 VGA shield.
1387 c - Enable the s3c camera interface.
1388 t - Reserved for enabling touchscreen support. The
1389 touchscreen support is not enabled in the mainstream
1390 kernel as of 2.6.30, a preliminary port can be found
1391 in the "bleeding edge" mini2440 support kernel at
1392 http://repo.or.cz/w/linux-2.6/mini2440.git
1394 mminit_loglevel=
1395 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1396 parameter allows control of the logging verbosity for
1397 the additional memory initialisation checks. A value
1398 of 0 disables mminit logging and a level of 4 will
1399 log everything. Information is printed at KERN_DEBUG
1400 so loglevel=8 may also need to be specified.
1402 mousedev.tap_time=
1403 [MOUSE] Maximum time between finger touching and
1404 leaving touchpad surface for touch to be considered
1405 a tap and be reported as a left button click (for
1406 touchpads working in absolute mode only).
1407 Format: <msecs>
1408 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1409 reporting absolute coordinates, such as tablets
1410 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1411 reporting absolute coordinates, such as tablets
1413 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1414 is similar to kernelcore except it specifies the
1415 amount of memory used for migratable allocations.
1416 If both kernelcore and movablecore is specified,
1417 then kernelcore will be at *least* the specified
1418 value but may be more. If movablecore on its own
1419 is specified, the administrator must be careful
1420 that the amount of memory usable for all allocations
1421 is not too small.
1423 mpu401= [HW,OSS]
1424 Format: <io>,<irq>
1426 MTD_Partition= [MTD]
1427 Format: <name>,<region-number>,<size>,<offset>
1429 MTD_Region= [MTD] Format:
1430 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1432 mtdparts= [MTD]
1433 See drivers/mtd/cmdlinepart.c.
1435 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1437 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1439 boundary - index of last SLC block on Flex-OneNAND.
1440 The remaining blocks are configured as MLC blocks.
1441 lock - Configure if Flex-OneNAND boundary should be locked.
1442 Once locked, the boundary cannot be changed.
1443 1 indicates lock status, 0 indicates unlock status.
1445 mtdset= [ARM]
1446 ARM/S3C2412 JIVE boot control
1448 See arch/arm/mach-s3c2412/mach-jive.c
1450 mtouchusb.raw_coordinates=
1451 [HW] Make the MicroTouch USB driver use raw coordinates
1452 ('y', default) or cooked coordinates ('n')
1454 mtrr_chunk_size=nn[KMG] [X86]
1455 used for mtrr cleanup. It is largest continuous chunk
1456 that could hold holes aka. UC entries.
1458 mtrr_gran_size=nn[KMG] [X86]
1459 Used for mtrr cleanup. It is granularity of mtrr block.
1460 Default is 1.
1461 Large value could prevent small alignment from
1462 using up MTRRs.
1464 mtrr_spare_reg_nr=n [X86]
1465 Format: <integer>
1466 Range: 0,7 : spare reg number
1467 Default : 1
1468 Used for mtrr cleanup. It is spare mtrr entries number.
1469 Set to 2 or more if your graphical card needs more.
1471 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1473 NCR_D700= [HW,SCSI]
1474 See header of drivers/scsi/NCR_D700.c.
1476 ncr5380= [HW,SCSI]
1478 ncr53c400= [HW,SCSI]
1480 ncr53c400a= [HW,SCSI]
1482 ncr53c406a= [HW,SCSI]
1484 ncr53c8xx= [HW,SCSI]
1486 netdev= [NET] Network devices parameters
1487 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1488 Note that mem_start is often overloaded to mean
1489 something different and driver-specific.
1490 This usage is only documented in each driver source
1491 file if at all.
1493 nf_conntrack.acct=
1494 [NETFILTER] Enable connection tracking flow accounting
1495 0 to disable accounting
1496 1 to enable accounting
1497 Default value depends on CONFIG_NF_CT_ACCT that is
1498 going to be removed in 2.6.29.
1500 nfsaddrs= [NFS]
1501 See Documentation/filesystems/nfsroot.txt.
1503 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1504 See Documentation/filesystems/nfsroot.txt.
1506 nfs.callback_tcpport=
1507 [NFS] set the TCP port on which the NFSv4 callback
1508 channel should listen.
1510 nfs.idmap_cache_timeout=
1511 [NFS] set the maximum lifetime for idmapper cache
1512 entries.
1514 nfs.enable_ino64=
1515 [NFS] enable 64-bit inode numbers.
1516 If zero, the NFS client will fake up a 32-bit inode
1517 number for the readdir() and stat() syscalls instead
1518 of returning the full 64-bit number.
1519 The default is to return 64-bit inode numbers.
1521 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1522 when a NMI is triggered.
1523 Format: [state][,regs][,debounce][,die]
1525 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1526 Format: [panic,][num]
1527 Valid num: 0,1,2
1528 0 - turn nmi_watchdog off
1529 1 - use the IO-APIC timer for the NMI watchdog
1530 2 - use the local APIC for the NMI watchdog using
1531 a performance counter. Note: This will use one
1532 performance counter and the local APIC's performance
1533 vector.
1534 When panic is specified, panic when an NMI watchdog
1535 timeout occurs.
1536 This is useful when you use a panic=... timeout and
1537 need the box quickly up again.
1538 Instead of 1 and 2 it is possible to use the following
1539 symbolic names: lapic and ioapic
1540 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1542 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1543 emulation library even if a 387 maths coprocessor
1544 is present.
1546 no_console_suspend
1547 [HW] Never suspend the console
1548 Disable suspending of consoles during suspend and
1549 hibernate operations. Once disabled, debugging
1550 messages can reach various consoles while the rest
1551 of the system is being put to sleep (ie, while
1552 debugging driver suspend/resume hooks). This may
1553 not work reliably with all consoles, but is known
1554 to work with serial and VGA consoles.
1556 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1557 caches in the slab allocator. Saves per-node memory,
1558 but will impact performance.
1560 noalign [KNL,ARM]
1562 noapic [SMP,APIC] Tells the kernel to not make use of any
1563 IOAPICs that may be present in the system.
1565 nobats [PPC] Do not use BATs for mapping kernel lowmem
1566 on "Classic" PPC cores.
1568 nocache [ARM]
1570 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1572 nodelayacct [KNL] Disable per-task delay accounting
1574 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1576 nodsp [SH] Disable hardware DSP at boot time.
1578 noefi [X86] Disable EFI runtime services support.
1580 noexec [IA-64]
1582 noexec [X86]
1583 On X86-32 available only on PAE configured kernels.
1584 noexec=on: enable non-executable mappings (default)
1585 noexec=off: disable non-executable mappings
1587 noexec32 [X86-64]
1588 This affects only 32-bit executables.
1589 noexec32=on: enable non-executable mappings (default)
1590 read doesn't imply executable mappings
1591 noexec32=off: disable non-executable mappings
1592 read implies executable mappings
1594 nofpu [SH] Disable hardware FPU at boot time.
1596 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1597 register save and restore. The kernel will only save
1598 legacy floating-point registers on task switch.
1600 noxsave [BUGS=X86] Disables x86 extended register state save
1601 and restore using xsave. The kernel will fallback to
1602 enabling legacy floating-point and sse state.
1604 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1605 wfi(ARM) instruction doesn't work correctly and not to
1606 use it. This is also useful when using JTAG debugger.
1608 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1609 instruction doesn't work correctly and not to
1610 use it.
1612 no_file_caps Tells the kernel not to honor file capabilities. The
1613 only way then for a file to be executed with privilege
1614 is to be setuid root or executed by root.
1616 nohalt [IA-64] Tells the kernel not to use the power saving
1617 function PAL_HALT_LIGHT when idle. This increases
1618 power-consumption. On the positive side, it reduces
1619 interrupt wake-up latency, which may improve performance
1620 in certain environments such as networked servers or
1621 real-time systems.
1623 nohz= [KNL] Boottime enable/disable dynamic ticks
1624 Valid arguments: on, off
1625 Default: on
1627 noiotrap [SH] Disables trapped I/O port accesses.
1629 noirqdebug [X86-32] Disables the code which attempts to detect and
1630 disable unhandled interrupt sources.
1632 no_timer_check [X86,APIC] Disables the code which tests for
1633 broken timer IRQ sources.
1635 noisapnp [ISAPNP] Disables ISA PnP code.
1637 noinitrd [RAM] Tells the kernel not to load any configured
1638 initial RAM disk.
1640 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1641 remapping.
1643 nointroute [IA-64]
1645 nojitter [IA64] Disables jitter checking for ITC timers.
1647 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1649 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1651 noltlbs [PPC] Do not use large page/tlb entries for kernel
1652 lowmem mapping on PPC40x.
1654 nomca [IA-64] Disable machine check abort handling
1656 nomce [X86-32] Machine Check Exception
1658 nomfgpt [X86-32] Disable Multi-Function General Purpose
1659 Timer usage (for AMD Geode machines).
1661 norandmaps Don't use address space randomization. Equivalent to
1662 echo 0 > /proc/sys/kernel/randomize_va_space
1664 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1666 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1667 with UP alternatives
1669 noresidual [PPC] Don't use residual data on PReP machines.
1671 noresume [SWSUSP] Disables resume and restores original swap
1672 space.
1674 no-scroll [VGA] Disables scrollback.
1675 This is required for the Braillex ib80-piezo Braille
1676 reader made by F.H. Papenmeier (Germany).
1678 nosbagart [IA-64]
1680 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1682 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1683 and disable the IO APIC. legacy for "maxcpus=0".
1685 nosoftlockup [KNL] Disable the soft-lockup detector.
1687 noswapaccount [KNL] Disable accounting of swap in memory resource
1688 controller. (See Documentation/cgroups/memory.txt)
1690 nosync [HW,M68K] Disables sync negotiation for all devices.
1692 notsc [BUGS=X86-32] Disable Time Stamp Counter
1694 nousb [USB] Disable the USB subsystem
1696 nowb [ARM]
1698 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1700 nptcg= [IA64] Override max number of concurrent global TLB
1701 purges which is reported from either PAL_VM_SUMMARY or
1702 SAL PALO.
1704 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1706 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1707 one of ['zone', 'node', 'default'] can be specified
1708 This can be set from sysctl after boot.
1709 See Documentation/sysctl/vm.txt for details.
1711 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1712 See Documentation/debugging-via-ohci1394.txt for more
1713 info.
1715 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1716 Rather than timing out after 20 ms if an EC
1717 command is not properly ACKed, override the length
1718 of the timeout. We have interrupts disabled while
1719 waiting for the ACK, so if this is set too high
1720 interrupts *may* be lost!
1722 opl3= [HW,OSS]
1723 Format: <io>
1725 oprofile.timer= [HW]
1726 Use timer interrupt instead of performance counters
1728 oprofile.cpu_type= Force an oprofile cpu type
1729 This might be useful if you have an older oprofile
1730 userland or if you want common events.
1731 Format: { archperfmon }
1732 archperfmon: [X86] Force use of architectural
1733 perfmon on Intel CPUs instead of the
1734 CPU specific event set.
1736 osst= [HW,SCSI] SCSI Tape Driver
1737 Format: <buffer_size>,<write_threshold>
1738 See also Documentation/scsi/st.txt.
1740 panic= [KNL] Kernel behaviour on panic
1741 Format: <timeout>
1743 parkbd.port= [HW] Parallel port number the keyboard adapter is
1744 connected to, default is 0.
1745 Format: <parport#>
1746 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1747 0 for XT, 1 for AT (default is AT).
1748 Format: <mode>
1750 parport= [HW,PPT] Specify parallel ports. 0 disables.
1751 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1752 Use 'auto' to force the driver to use any
1753 IRQ/DMA settings detected (the default is to
1754 ignore detected IRQ/DMA settings because of
1755 possible conflicts). You can specify the base
1756 address, IRQ, and DMA settings; IRQ and DMA
1757 should be numbers, or 'auto' (for using detected
1758 settings on that particular port), or 'nofifo'
1759 (to avoid using a FIFO even if it is detected).
1760 Parallel ports are assigned in the order they
1761 are specified on the command line, starting
1762 with parport0.
1764 parport_init_mode= [HW,PPT]
1765 Configure VIA parallel port to operate in
1766 a specific mode. This is necessary on Pegasos
1767 computer where firmware has no options for setting
1768 up parallel port mode and sets it to spp.
1769 Currently this function knows 686a and 8231 chips.
1770 Format: [spp|ps2|epp|ecp|ecpepp]
1772 pas2= [HW,OSS] Format:
1773 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1775 pas16= [HW,SCSI]
1776 See header of drivers/scsi/pas16.c.
1778 pause_on_oops=
1779 Halt all CPUs after the first oops has been printed for
1780 the specified number of seconds. This is to be used if
1781 your oopses keep scrolling off the screen.
1783 pcbit= [HW,ISDN]
1785 pcd. [PARIDE]
1786 See header of drivers/block/paride/pcd.c.
1787 See also Documentation/blockdev/paride.txt.
1789 pci=option[,option...] [PCI] various PCI subsystem options:
1790 earlydump [X86] dump PCI config space before the kernel
1791 changes anything
1792 off [X86] don't probe for the PCI bus
1793 bios [X86-32] force use of PCI BIOS, don't access
1794 the hardware directly. Use this if your machine
1795 has a non-standard PCI host bridge.
1796 nobios [X86-32] disallow use of PCI BIOS, only direct
1797 hardware access methods are allowed. Use this
1798 if you experience crashes upon bootup and you
1799 suspect they are caused by the BIOS.
1800 conf1 [X86] Force use of PCI Configuration
1801 Mechanism 1.
1802 conf2 [X86] Force use of PCI Configuration
1803 Mechanism 2.
1804 noaer [PCIE] If the PCIEAER kernel config parameter is
1805 enabled, this kernel boot option can be used to
1806 disable the use of PCIE advanced error reporting.
1807 nodomains [PCI] Disable support for multiple PCI
1808 root domains (aka PCI segments, in ACPI-speak).
1809 nommconf [X86] Disable use of MMCONFIG for PCI
1810 Configuration
1811 check_enable_amd_mmconf [X86] check for and enable
1812 properly configured MMIO access to PCI
1813 config space on AMD family 10h CPU
1814 nomsi [MSI] If the PCI_MSI kernel config parameter is
1815 enabled, this kernel boot option can be used to
1816 disable the use of MSI interrupts system-wide.
1817 noioapicquirk [APIC] Disable all boot interrupt quirks.
1818 Safety option to keep boot IRQs enabled. This
1819 should never be necessary.
1820 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1821 primary IO-APIC for bridges that cannot disable
1822 boot IRQs. This fixes a source of spurious IRQs
1823 when the system masks IRQs.
1824 noioapicreroute [APIC] Disable workaround that uses the
1825 boot IRQ equivalent of an IRQ that connects to
1826 a chipset where boot IRQs cannot be disabled.
1827 The opposite of ioapicreroute.
1828 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1829 routing table. These calls are known to be buggy
1830 on several machines and they hang the machine
1831 when used, but on other computers it's the only
1832 way to get the interrupt routing table. Try
1833 this option if the kernel is unable to allocate
1834 IRQs or discover secondary PCI buses on your
1835 motherboard.
1836 rom [X86] Assign address space to expansion ROMs.
1837 Use with caution as certain devices share
1838 address decoders between ROMs and other
1839 resources.
1840 norom [X86] Do not assign address space to
1841 expansion ROMs that do not already have
1842 BIOS assigned address ranges.
1843 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1844 assigned automatically to PCI devices. You can
1845 make the kernel exclude IRQs of your ISA cards
1846 this way.
1847 pirqaddr=0xAAAAA [X86] Specify the physical address
1848 of the PIRQ table (normally generated
1849 by the BIOS) if it is outside the
1850 F0000h-100000h range.
1851 lastbus=N [X86] Scan all buses thru bus #N. Can be
1852 useful if the kernel is unable to find your
1853 secondary buses and you want to tell it
1854 explicitly which ones they are.
1855 assign-busses [X86] Always assign all PCI bus
1856 numbers ourselves, overriding
1857 whatever the firmware may have done.
1858 usepirqmask [X86] Honor the possible IRQ mask stored
1859 in the BIOS $PIR table. This is needed on
1860 some systems with broken BIOSes, notably
1861 some HP Pavilion N5400 and Omnibook XE3
1862 notebooks. This will have no effect if ACPI
1863 IRQ routing is enabled.
1864 noacpi [X86] Do not use ACPI for IRQ routing
1865 or for PCI scanning.
1866 nocrs [X86] Don't use _CRS for PCI resource
1867 allocation.
1868 routeirq Do IRQ routing for all PCI devices.
1869 This is normally done in pci_enable_device(),
1870 so this option is a temporary workaround
1871 for broken drivers that don't call it.
1872 skip_isa_align [X86] do not align io start addr, so can
1873 handle more pci cards
1874 firmware [ARM] Do not re-enumerate the bus but instead
1875 just use the configuration from the
1876 bootloader. This is currently used on
1877 IXP2000 systems where the bus has to be
1878 configured a certain way for adjunct CPUs.
1879 noearly [X86] Don't do any early type 1 scanning.
1880 This might help on some broken boards which
1881 machine check when some devices' config space
1882 is read. But various workarounds are disabled
1883 and some IOMMU drivers will not work.
1884 bfsort Sort PCI devices into breadth-first order.
1885 This sorting is done to get a device
1886 order compatible with older (<= 2.4) kernels.
1887 nobfsort Don't sort PCI devices into breadth-first order.
1888 cbiosize=nn[KMG] The fixed amount of bus space which is
1889 reserved for the CardBus bridge's IO window.
1890 The default value is 256 bytes.
1891 cbmemsize=nn[KMG] The fixed amount of bus space which is
1892 reserved for the CardBus bridge's memory
1893 window. The default value is 64 megabytes.
1894 resource_alignment=
1895 Format:
1896 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1897 Specifies alignment and device to reassign
1898 aligned memory resources.
1899 If <order of align> is not specified,
1900 PAGE_SIZE is used as alignment.
1901 PCI-PCI bridge can be specified, if resource
1902 windows need to be expanded.
1903 ecrc= Enable/disable PCIe ECRC (transaction layer
1904 end-to-end CRC checking).
1905 bios: Use BIOS/firmware settings. This is the
1906 the default.
1907 off: Turn ECRC off
1908 on: Turn ECRC on.
1910 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1911 Management.
1912 off Disable ASPM.
1913 force Enable ASPM even on devices that claim not to support it.
1914 WARNING: Forcing ASPM on may cause system lockups.
1916 pcmv= [HW,PCMCIA] BadgePAD 4
1918 pd. [PARIDE]
1919 See Documentation/blockdev/paride.txt.
1921 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1922 boot time.
1923 Format: { 0 | 1 }
1924 See arch/parisc/kernel/pdc_chassis.c
1926 pf. [PARIDE]
1927 See Documentation/blockdev/paride.txt.
1929 pg. [PARIDE]
1930 See Documentation/blockdev/paride.txt.
1932 pirq= [SMP,APIC] Manual mp-table setup
1933 See Documentation/x86/i386/IO-APIC.txt.
1935 plip= [PPT,NET] Parallel port network link
1936 Format: { parport<nr> | timid | 0 }
1937 See also Documentation/parport.txt.
1939 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1940 Override pmtimer IOPort with a hex value.
1941 e.g. pmtmr=0x508
1943 pnp.debug [PNP]
1944 Enable PNP debug messages. This depends on the
1945 CONFIG_PNP_DEBUG_MESSAGES option.
1947 pnpacpi= [ACPI]
1948 { off }
1950 pnpbios= [ISAPNP]
1951 { on | off | curr | res | no-curr | no-res }
1953 pnp_reserve_irq=
1954 [ISAPNP] Exclude IRQs for the autoconfiguration
1956 pnp_reserve_dma=
1957 [ISAPNP] Exclude DMAs for the autoconfiguration
1959 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1960 Ranges are in pairs (I/O port base and size).
1962 pnp_reserve_mem=
1963 [ISAPNP] Exclude memory regions for the
1964 autoconfiguration.
1965 Ranges are in pairs (memory base and size).
1967 ports= [IP_VS_FTP] IPVS ftp helper module
1968 Default is 21.
1969 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1970 may be specified.
1971 Format: <port>,<port>....
1973 print-fatal-signals=
1974 [KNL] debug: print fatal signals
1975 print-fatal-signals=1: print segfault info to
1976 the kernel console.
1977 default: off.
1979 printk.time= Show timing data prefixed to each printk message line
1980 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1982 processor.max_cstate= [HW,ACPI]
1983 Limit processor to maximum C-state
1984 max_cstate=9 overrides any DMI blacklist limit.
1986 processor.nocst [HW,ACPI]
1987 Ignore the _CST method to determine C-states,
1988 instead using the legacy FADT method
1990 profile= [KNL] Enable kernel profiling via /proc/profile
1991 Format: [schedule,]<number>
1992 Param: "schedule" - profile schedule points.
1993 Param: <number> - step/bucket size as a power of 2 for
1994 statistical time based profiling.
1995 Param: "sleep" - profile D-state sleeping (millisecs).
1996 Requires CONFIG_SCHEDSTATS
1997 Param: "kvm" - profile VM exits.
1999 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2000 before loading.
2001 See Documentation/blockdev/ramdisk.txt.
2003 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2004 probe for; one of (bare|imps|exps|lifebook|any).
2005 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2006 per second.
2007 psmouse.resetafter= [HW,MOUSE]
2008 Try to reset the device after so many bad packets
2009 (0 = never).
2010 psmouse.resolution=
2011 [HW,MOUSE] Set desired mouse resolution, in dpi.
2012 psmouse.smartscroll=
2013 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2014 0 = disabled, 1 = enabled (default).
2016 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2017 Format:
2018 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2020 pt. [PARIDE]
2021 See Documentation/blockdev/paride.txt.
2023 pty.legacy_count=
2024 [KNL] Number of legacy pty's. Overwrites compiled-in
2025 default number.
2027 quiet [KNL] Disable most log messages
2029 r128= [HW,DRM]
2031 raid= [HW,RAID]
2032 See Documentation/md.txt.
2034 ramdisk_blocksize= [RAM]
2035 See Documentation/blockdev/ramdisk.txt.
2037 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2038 See Documentation/blockdev/ramdisk.txt.
2040 rcupdate.blimit= [KNL,BOOT]
2041 Set maximum number of finished RCU callbacks to process
2042 in one batch.
2044 rcupdate.qhimark= [KNL,BOOT]
2045 Set threshold of queued
2046 RCU callbacks over which batch limiting is disabled.
2048 rcupdate.qlowmark= [KNL,BOOT]
2049 Set threshold of queued RCU callbacks below which
2050 batch limiting is re-enabled.
2052 rdinit= [KNL]
2053 Format: <full_path>
2054 Run specified binary instead of /init from the ramdisk,
2055 used for early userspace startup. See initrd.
2057 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2058 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2059 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2061 relax_domain_level=
2062 [KNL, SMP] Set scheduler's default relax_domain_level.
2063 See Documentation/cgroups/cpusets.txt.
2065 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2067 reservetop= [X86-32]
2068 Format: nn[KMG]
2069 Reserves a hole at the top of the kernel virtual
2070 address space.
2072 reset_devices [KNL] Force drivers to reset the underlying device
2073 during initialization.
2075 resume= [SWSUSP]
2076 Specify the partition device for software suspend
2078 resume_offset= [SWSUSP]
2079 Specify the offset from the beginning of the partition
2080 given by "resume=" at which the swap header is located,
2081 in <PAGE_SIZE> units (needed only for swap files).
2082 See Documentation/power/swsusp-and-swap-files.txt
2084 retain_initrd [RAM] Keep initrd memory after extraction
2086 rhash_entries= [KNL,NET]
2087 Set number of hash buckets for route cache
2089 riscom8= [HW,SERIAL]
2090 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2092 ro [KNL] Mount root device read-only on boot
2094 root= [KNL] Root filesystem
2096 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2097 mount the root filesystem
2099 rootflags= [KNL] Set root filesystem mount option string
2101 rootfstype= [KNL] Set root filesystem type
2103 rootwait [KNL] Wait (indefinitely) for root device to show up.
2104 Useful for devices that are detected asynchronously
2105 (e.g. USB and MMC devices).
2107 root_plug.vendor_id=
2108 [ROOTPLUG] Override the default vendor ID
2110 root_plug.product_id=
2111 [ROOTPLUG] Override the default product ID
2113 root_plug.debug=
2114 [ROOTPLUG] Enable debugging output
2116 rw [KNL] Mount root device read-write on boot
2118 S [KNL] Run init in single mode
2120 sa1100ir [NET]
2121 See drivers/net/irda/sa1100_ir.c.
2123 sbni= [NET] Granch SBNI12 leased line adapter
2125 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2126 Format: <io>[,<timeout>[,<isapnp>]]
2128 scsi_debug_*= [SCSI]
2129 See drivers/scsi/scsi_debug.c.
2131 scsi_default_dev_flags=
2132 [SCSI] SCSI default device flags
2133 Format: <integer>
2135 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2136 Format: <vendor>:<model>:<flags>
2137 (flags are integer value)
2139 scsi_logging_level= [SCSI] a bit mask of logging levels
2140 See drivers/scsi/scsi_logging.h for bits. Also
2141 settable via sysctl at dev.scsi.logging_level
2142 (/proc/sys/dev/scsi/logging_level).
2143 There is also a nice 'scsi_logging_level' script in the
2144 S390-tools package, available for download at
2145 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2147 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2148 discovered. async scans them in kernel threads,
2149 allowing boot to proceed. none ignores them, expecting
2150 user space to do the scan.
2152 security= [SECURITY] Choose a security module to enable at boot.
2153 If this boot parameter is not specified, only the first
2154 security module asking for security registration will be
2155 loaded. An invalid security module name will be treated
2156 as if no module has been chosen.
2158 selinux= [SELINUX] Disable or enable SELinux at boot time.
2159 Format: { "0" | "1" }
2160 See security/selinux/Kconfig help text.
2161 0 -- disable.
2162 1 -- enable.
2163 Default value is set via kernel config option.
2164 If enabled at boot time, /selinux/disable can be used
2165 later to disable prior to initial policy load.
2167 serialnumber [BUGS=X86-32]
2169 shapers= [NET]
2170 Maximal number of shapers.
2172 show_msr= [x86] show boot-time MSR settings
2173 Format: { <integer> }
2174 Show boot-time (BIOS-initialized) MSR settings.
2175 The parameter means the number of CPUs to show,
2176 for example 1 means boot CPU only.
2178 sim710= [SCSI,HW]
2179 See header of drivers/scsi/sim710.c.
2181 simeth= [IA-64]
2182 simscsi=
2184 slram= [HW,MTD]
2186 slub_debug[=options[,slabs]] [MM, SLUB]
2187 Enabling slub_debug allows one to determine the
2188 culprit if slab objects become corrupted. Enabling
2189 slub_debug can create guard zones around objects and
2190 may poison objects when not in use. Also tracks the
2191 last alloc / free. For more information see
2192 Documentation/vm/slub.txt.
2194 slub_max_order= [MM, SLUB]
2195 Determines the maximum allowed order for slabs.
2196 A high setting may cause OOMs due to memory
2197 fragmentation. For more information see
2198 Documentation/vm/slub.txt.
2200 slub_min_objects= [MM, SLUB]
2201 The minimum number of objects per slab. SLUB will
2202 increase the slab order up to slub_max_order to
2203 generate a sufficiently large slab able to contain
2204 the number of objects indicated. The higher the number
2205 of objects the smaller the overhead of tracking slabs
2206 and the less frequently locks need to be acquired.
2207 For more information see Documentation/vm/slub.txt.
2209 slub_min_order= [MM, SLUB]
2210 Determines the mininum page order for slabs. Must be
2211 lower than slub_max_order.
2212 For more information see Documentation/vm/slub.txt.
2214 slub_nomerge [MM, SLUB]
2215 Disable merging of slabs with similar size. May be
2216 necessary if there is some reason to distinguish
2217 allocs to different slabs. Debug options disable
2218 merging on their own.
2219 For more information see Documentation/vm/slub.txt.
2221 smart2= [HW]
2222 Format: <io1>[,<io2>[,...,<io8>]]
2224 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2225 attempt to substitute SMP alternatives once at boot.
2227 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2228 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2229 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2230 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2231 smsc-ircc2.ircc_irq= [HW] IRQ line
2232 smsc-ircc2.ircc_dma= [HW] DMA channel
2233 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2234 0: Toshiba Satellite 1800 (GP data pin select)
2235 1: Fast pin select (default)
2236 2: ATC IRMode
2238 snd-ad1816a= [HW,ALSA]
2240 snd-ad1848= [HW,ALSA]
2242 snd-ali5451= [HW,ALSA]
2244 snd-als100= [HW,ALSA]
2246 snd-als4000= [HW,ALSA]
2248 snd-azt2320= [HW,ALSA]
2250 snd-cmi8330= [HW,ALSA]
2252 snd-cmipci= [HW,ALSA]
2254 snd-cs4231= [HW,ALSA]
2256 snd-cs4232= [HW,ALSA]
2258 snd-cs4236= [HW,ALSA]
2260 snd-cs4281= [HW,ALSA]
2262 snd-cs46xx= [HW,ALSA]
2264 snd-dt019x= [HW,ALSA]
2266 snd-dummy= [HW,ALSA]
2268 snd-emu10k1= [HW,ALSA]
2270 snd-ens1370= [HW,ALSA]
2272 snd-ens1371= [HW,ALSA]
2274 snd-es968= [HW,ALSA]
2276 snd-es1688= [HW,ALSA]
2278 snd-es18xx= [HW,ALSA]
2280 snd-es1938= [HW,ALSA]
2282 snd-es1968= [HW,ALSA]
2284 snd-fm801= [HW,ALSA]
2286 snd-gusclassic= [HW,ALSA]
2288 snd-gusextreme= [HW,ALSA]
2290 snd-gusmax= [HW,ALSA]
2292 snd-hdsp= [HW,ALSA]
2294 snd-ice1712= [HW,ALSA]
2296 snd-intel8x0= [HW,ALSA]
2298 snd-interwave= [HW,ALSA]
2300 snd-interwave-stb=
2301 [HW,ALSA]
2303 snd-korg1212= [HW,ALSA]
2305 snd-maestro3= [HW,ALSA]
2307 snd-mpu401= [HW,ALSA]
2309 snd-mtpav= [HW,ALSA]
2311 snd-nm256= [HW,ALSA]
2313 snd-opl3sa2= [HW,ALSA]
2315 snd-opti92x-ad1848=
2316 [HW,ALSA]
2318 snd-opti92x-cs4231=
2319 [HW,ALSA]
2321 snd-opti93x= [HW,ALSA]
2323 snd-pmac= [HW,ALSA]
2325 snd-rme32= [HW,ALSA]
2327 snd-rme96= [HW,ALSA]
2329 snd-rme9652= [HW,ALSA]
2331 snd-sb8= [HW,ALSA]
2333 snd-sb16= [HW,ALSA]
2335 snd-sbawe= [HW,ALSA]
2337 snd-serial= [HW,ALSA]
2339 snd-sgalaxy= [HW,ALSA]
2341 snd-sonicvibes= [HW,ALSA]
2343 snd-sun-amd7930=
2344 [HW,ALSA]
2346 snd-sun-cs4231= [HW,ALSA]
2348 snd-trident= [HW,ALSA]
2350 snd-usb-audio= [HW,ALSA,USB]
2352 snd-via82xx= [HW,ALSA]
2354 snd-virmidi= [HW,ALSA]
2356 snd-wavefront= [HW,ALSA]
2358 snd-ymfpci= [HW,ALSA]
2360 softlockup_panic=
2361 [KNL] Should the soft-lockup detector generate panics.
2363 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2364 See Documentation/sonypi.txt
2366 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2367 See Documentation/serial/specialix.txt.
2369 spia_io_base= [HW,MTD]
2370 spia_fio_base=
2371 spia_pedr=
2372 spia_peddr=
2374 sscape= [HW,OSS]
2375 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2377 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2378 See Documentation/scsi/st.txt.
2380 stacktrace [FTRACE]
2381 Enabled the stack tracer on boot up.
2383 sti= [PARISC,HW]
2384 Format: <num>
2385 Set the STI (builtin display/keyboard on the HP-PARISC
2386 machines) console (graphic card) which should be used
2387 as the initial boot-console.
2388 See also comment in drivers/video/console/sticore.c.
2390 sti_font= [HW]
2391 See comment in drivers/video/console/sticore.c.
2393 stifb= [HW]
2394 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2396 sunrpc.pool_mode=
2397 [NFS]
2398 Control how the NFS server code allocates CPUs to
2399 service thread pools. Depending on how many NICs
2400 you have and where their interrupts are bound, this
2401 option will affect which CPUs will do NFS serving.
2402 Note: this parameter cannot be changed while the
2403 NFS server is running.
2405 auto the server chooses an appropriate mode
2406 automatically using heuristics
2407 global a single global pool contains all CPUs
2408 percpu one pool for each CPU
2409 pernode one pool for each NUMA node (equivalent
2410 to global on non-NUMA machines)
2412 swiotlb= [IA-64] Number of I/O TLB slabs
2414 switches= [HW,M68k]
2416 sym53c416= [HW,SCSI]
2417 See header of drivers/scsi/sym53c416.c.
2419 sysrq_always_enabled
2420 [KNL]
2421 Ignore sysrq setting - this boot parameter will
2422 neutralize any effect of /proc/sys/kernel/sysrq.
2423 Useful for debugging.
2425 t128= [HW,SCSI]
2426 See header of drivers/scsi/t128.c.
2428 tdfx= [HW,DRM]
2430 test_suspend= [SUSPEND]
2431 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2432 standby suspend) as the system sleep state to briefly
2433 enter during system startup. The system is woken from
2434 this state using a wakeup-capable RTC alarm.
2436 thash_entries= [KNL,NET]
2437 Set number of hash buckets for TCP connection
2439 thermal.act= [HW,ACPI]
2440 -1: disable all active trip points in all thermal zones
2441 <degrees C>: override all lowest active trip points
2443 thermal.crt= [HW,ACPI]
2444 -1: disable all critical trip points in all thermal zones
2445 <degrees C>: override all critical trip points
2447 thermal.nocrt= [HW,ACPI]
2448 Set to disable actions on ACPI thermal zone
2449 critical and hot trip points.
2451 thermal.off= [HW,ACPI]
2452 1: disable ACPI thermal control
2454 thermal.psv= [HW,ACPI]
2455 -1: disable all passive trip points
2456 <degrees C>: override all passive trip points to this
2457 value
2459 thermal.tzp= [HW,ACPI]
2460 Specify global default ACPI thermal zone polling rate
2461 <deci-seconds>: poll all this frequency
2462 0: no polling (default)
2464 tmscsim= [HW,SCSI]
2465 See comment before function dc390_setup() in
2466 drivers/scsi/tmscsim.c.
2468 topology= [S390]
2469 Format: {off | on}
2470 Specify if the kernel should make use of the cpu
2471 topology informations if the hardware supports these.
2472 The scheduler will make use of these informations and
2473 e.g. base its process migration decisions on it.
2474 Default is off.
2476 tp720= [HW,PS2]
2478 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2480 trix= [HW,OSS] MediaTrix AudioTrix Pro
2481 Format:
2482 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2484 tsc= Disable clocksource-must-verify flag for TSC.
2485 Format: <string>
2486 [x86] reliable: mark tsc clocksource as reliable, this
2487 disables clocksource verification at runtime.
2488 Used to enable high-resolution timer mode on older
2489 hardware, and in virtualized environment.
2491 turbografx.map[2|3]= [HW,JOY]
2492 TurboGraFX parallel port interface
2493 Format:
2494 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2495 See also Documentation/input/joystick-parport.txt
2497 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2498 See header of drivers/scsi/u14-34f.c.
2500 uart401= [HW,OSS]
2501 Format: <io>,<irq>
2503 uart6850= [HW,OSS]
2504 Format: <io>,<irq>
2506 uhci-hcd.ignore_oc=
2507 [USB] Ignore overcurrent events (default N).
2508 Some badly-designed motherboards generate lots of
2509 bogus events, for ports that aren't wired to
2510 anything. Set this parameter to avoid log spamming.
2511 Note that genuine overcurrent events won't be
2512 reported either.
2514 unknown_nmi_panic
2515 [X86]
2516 Set unknown_nmi_panic=1 early on boot.
2518 usbcore.autosuspend=
2519 [USB] The autosuspend time delay (in seconds) used
2520 for newly-detected USB devices (default 2). This
2521 is the time required before an idle device will be
2522 autosuspended. Devices for which the delay is set
2523 to a negative value won't be autosuspended at all.
2525 usbcore.usbfs_snoop=
2526 [USB] Set to log all usbfs traffic (default 0 = off).
2528 usbcore.blinkenlights=
2529 [USB] Set to cycle leds on hubs (default 0 = off).
2531 usbcore.old_scheme_first=
2532 [USB] Start with the old device initialization
2533 scheme (default 0 = off).
2535 usbcore.use_both_schemes=
2536 [USB] Try the other device initialization scheme
2537 if the first one fails (default 1 = enabled).
2539 usbcore.initial_descriptor_timeout=
2540 [USB] Specifies timeout for the initial 64-byte
2541 USB_REQ_GET_DESCRIPTOR request in milliseconds
2542 (default 5000 = 5.0 seconds).
2544 usbhid.mousepoll=
2545 [USBHID] The interval which mice are to be polled at.
2547 usb-storage.delay_use=
2548 [UMS] The delay in seconds before a new device is
2549 scanned for Logical Units (default 5).
2551 usb-storage.quirks=
2552 [UMS] A list of quirks entries to supplement or
2553 override the built-in unusual_devs list. List
2554 entries are separated by commas. Each entry has
2555 the form VID:PID:Flags where VID and PID are Vendor
2556 and Product ID values (4-digit hex numbers) and
2557 Flags is a set of characters, each corresponding
2558 to a common usb-storage quirk flag as follows:
2559 a = SANE_SENSE (collect more than 18 bytes
2560 of sense data);
2561 c = FIX_CAPACITY (decrease the reported
2562 device capacity by one sector);
2563 h = CAPACITY_HEURISTICS (decrease the
2564 reported device capacity by one
2565 sector if the number is odd);
2566 i = IGNORE_DEVICE (don't bind to this
2567 device);
2568 l = NOT_LOCKABLE (don't try to lock and
2569 unlock ejectable media);
2570 m = MAX_SECTORS_64 (don't transfer more
2571 than 64 sectors = 32 KB at a time);
2572 o = CAPACITY_OK (accept the capacity
2573 reported by the device);
2574 r = IGNORE_RESIDUE (the device reports
2575 bogus residue values);
2576 s = SINGLE_LUN (the device has only one
2577 Logical Unit);
2578 w = NO_WP_DETECT (don't test whether the
2579 medium is write-protected).
2580 Example: quirks=0419:aaf5:rl,0421:0433:rc
2582 vdso= [X86,SH]
2583 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2584 vdso=1: enable VDSO (default)
2585 vdso=0: disable VDSO mapping
2587 vdso32= [X86]
2588 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2589 vdso32=1: enable 32-bit VDSO (default)
2590 vdso32=0: disable 32-bit VDSO mapping
2592 vector= [IA-64,SMP]
2593 vector=percpu: enable percpu vector domain
2595 video= [FB] Frame buffer configuration
2596 See Documentation/fb/modedb.txt.
2598 vga= [BOOT,X86-32] Select a particular video mode
2599 See Documentation/x86/boot.txt and
2600 Documentation/svga.txt.
2601 Use vga=ask for menu.
2602 This is actually a boot loader parameter; the value is
2603 passed to the kernel using a special protocol.
2605 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2606 size of <nn>. This can be used to increase the
2607 minimum size (128MB on x86). It can also be used to
2608 decrease the size and leave more room for directly
2609 mapped kernel RAM.
2611 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2612 Format: <command>
2614 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2615 Format: <command>
2617 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2618 Format: <command>
2620 vt.default_blu= [VT]
2621 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2622 Change the default blue palette of the console.
2623 This is a 16-member array composed of values
2624 ranging from 0-255.
2626 vt.default_grn= [VT]
2627 Format: <green0>,<green1>,<green2>,...,<green15>
2628 Change the default green palette of the console.
2629 This is a 16-member array composed of values
2630 ranging from 0-255.
2632 vt.default_red= [VT]
2633 Format: <red0>,<red1>,<red2>,...,<red15>
2634 Change the default red palette of the console.
2635 This is a 16-member array composed of values
2636 ranging from 0-255.
2638 vt.default_utf8=
2639 [VT]
2640 Format=<0|1>
2641 Set system-wide default UTF-8 mode for all tty's.
2642 Default is 1, i.e. UTF-8 mode is enabled for all
2643 newly opened terminals.
2645 waveartist= [HW,OSS]
2646 Format: <io>,<irq>,<dma>,<dma2>
2648 wd33c93= [HW,SCSI]
2649 See header of drivers/scsi/wd33c93.c.
2651 wd7000= [HW,SCSI]
2652 See header of drivers/scsi/wd7000.c.
2654 wdt= [WDT] Watchdog
2655 See Documentation/watchdog/wdt.txt.
2657 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2658 default x2apic cluster mode on platforms
2659 supporting x2apic.
2661 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2662 xd_geo= See header of drivers/block/xd.c.
2664 xirc2ps_cs= [NET,PCMCIA]
2665 Format:
2666 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2668 ______________________________________________________________________
2670 TODO:
2672 Add documentation for ALSA options.
2673 Add more DRM drivers.