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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 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
83 Documentation/scsi/.
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
105 In addition, the following text indicates that the option:
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
111 Parameters denoted with BOOT are actually interpreted by the boot
112 loader, and have no meaning to the kernel directly.
113 Do not modify the syntax of boot loader parameters without extreme
114 need or coordination with <Documentation/i386/boot.txt>.
116 There are also arch-specific kernel-parameters not documented here.
117 See for example <Documentation/x86_64/boot-options.txt>.
119 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120 a trailing = on the name of any parameter states that that parameter will
121 be entered as an environment variable, whereas its absence indicates that
122 it will appear as a kernel argument readable via /proc/cmdline by programs
123 running once the system is up.
125 The number of kernel parameters is not limited, but the length of the
126 complete command line (parameters including spaces etc.) is limited to
127 a fixed number of characters. This limit depends on the architecture
128 and is between 256 and 4096 characters. It is defined in the file
129 ./include/asm/setup.h as COMMAND_LINE_SIZE.
132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
134 Format: { force | off | ht | strict | noirq }
135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
139 strict -- Be less tolerant of platforms that are not
140 strictly ACPI specification compliant.
142 See also Documentation/power/pm.txt, pci=noacpi
144 acpi_apic_instance= [ACPI, IOAPIC]
145 Format: <int>
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
148 default: 0
150 acpi_sleep= [HW,ACPI] Sleep options
151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
160 used by default).
162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
163 Format: { level | edge | high | low }
165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
167 default in APIC mode
169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
171 default in PIC mode
173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
174 use by PCI
175 Format: <irq>,<irq>...
177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
178 Format: <irq>,<irq>...
180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
190 acpi_serialize [HW,ACPI] force serialization of AML methods
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
198 HPET
200 acpi.debug_layer= [HW,ACPI]
201 Format: <int>
202 Each bit of the <int> indicates an ACPI debug layer,
203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
217 acpi.debug_level= [HW,ACPI]
218 Format: <int>
219 Each bit of the <int> indicates an ACPI debug level,
220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
235 acpi_pm_good [X86-32,X86-64]
236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
240 agp= [AGP]
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
250 The kernel tries to set a reasonable default.
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
256 ad1848= [HW,OSS]
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
259 advansys= [HW,SCSI]
260 See header of drivers/scsi/advansys.c.
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
269 aha152x= [HW,SCSI]
270 See Documentation/scsi/aha152x.txt.
272 aha1542= [HW,SCSI]
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
275 aic7xxx= [HW,SCSI]
276 See Documentation/scsi/aic7xxx.txt.
278 aic79xx= [HW,SCSI]
279 See Documentation/scsi/aic79xx.txt.
281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
283 Possible values are:
284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
286 domain) [default]
287 amd_iommu_size= [HW,X86-64]
288 Define the size of the aperture for the AMD IOMMU
289 driver. Possible values are:
290 '32M', '64M' (default), '128M', '256M', '512M', '1G'
292 amijoy.map= [HW,JOY] Amiga joystick support
293 Map of devices attached to JOY0DAT and JOY1DAT
294 Format: <a>,<b>
295 See also Documentation/kernel/input/joystick.txt
297 analog.map= [HW,JOY] Analog joystick and gamepad support
298 Specifies type or capabilities of an analog joystick
299 connected to one of 16 gameports
300 Format: <type1>,<type2>,..<type16>
302 apc= [HW,SPARC]
303 Power management functions (SPARCstation-4/5 + deriv.)
304 Format: noidle
305 Disable APC CPU standby support. SPARCstation-Fox does
306 not play well with APC CPU idle - disable it if you have
307 APC and your system crashes randomly.
309 apic= [APIC,i386] Advanced Programmable Interrupt Controller
310 Change the output verbosity whilst booting
311 Format: { quiet (default) | verbose | debug }
312 Change the amount of debugging information output
313 when initialising the APIC and IO-APIC components.
315 apm= [APM] Advanced Power Management
316 See header of arch/x86/kernel/apm_32.c.
318 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
319 Format: <io>,<irq>,<nodeID>
321 ataflop= [HW,M68k]
323 atarimouse= [HW,MOUSE] Atari Mouse
325 atascsi= [HW,SCSI] Atari SCSI
327 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
328 EzKey and similar keyboards
330 atkbd.reset= [HW] Reset keyboard during initialization
332 atkbd.set= [HW] Select keyboard code set
333 Format: <int> (2 = AT (default), 3 = PS/2)
335 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
336 keyboards
338 atkbd.softraw= [HW] Choose between synthetic and real raw mode
339 Format: <bool> (0 = real, 1 = synthetic (default))
341 atkbd.softrepeat= [HW]
342 Use software keyboard repeat
344 autotest [IA64]
346 baycom_epp= [HW,AX25]
347 Format: <io>,<mode>
349 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
350 Format: <io>,<mode>
351 See header of drivers/net/hamradio/baycom_par.c.
353 baycom_ser_fdx= [HW,AX25]
354 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
355 Format: <io>,<irq>,<mode>[,<baud>]
356 See header of drivers/net/hamradio/baycom_ser_fdx.c.
358 baycom_ser_hdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
360 Format: <io>,<irq>,<mode>
361 See header of drivers/net/hamradio/baycom_ser_hdx.c.
363 boot_delay= Milliseconds to delay each printk during boot.
364 Values larger than 10 seconds (10000) are changed to
365 no delay (0).
366 Format: integer
368 bootmem_debug [KNL] Enable bootmem allocator debug messages.
370 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
371 bttv.radio= Most important insmod options are available as
372 kernel args too.
373 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
374 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
376 BusLogic= [HW,SCSI]
377 See drivers/scsi/BusLogic.c, comment before function
378 BusLogic_ParseDriverOptions().
380 c101= [NET] Moxa C101 synchronous serial card
382 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
383 Sometimes CPU hardware bugs make them report the cache
384 size incorrectly. The kernel will attempt work arounds
385 to fix known problems, but for some CPUs it is not
386 possible to determine what the correct size should be.
387 This option provides an override for these situations.
389 security= [SECURITY] Choose a security module to enable at boot.
390 If this boot parameter is not specified, only the first
391 security module asking for security registration will be
392 loaded. An invalid security module name will be treated
393 as if no module has been chosen.
395 capability.disable=
396 [SECURITY] Disable capabilities. This would normally
397 be used only if an alternative security model is to be
398 configured. Potentially dangerous and should only be
399 used if you are entirely sure of the consequences.
401 ccw_timeout_log [S390]
402 See Documentation/s390/CommonIO for details.
404 cgroup_disable= [KNL] Disable a particular controller
405 Format: {name of the controller(s) to disable}
406 {Currently supported controllers - "memory"}
408 checkreqprot [SELINUX] Set initial checkreqprot flag value.
409 Format: { "0" | "1" }
410 See security/selinux/Kconfig help text.
411 0 -- check protection applied by kernel (includes
412 any implied execute protection).
413 1 -- check protection requested by application.
414 Default value is set via a kernel config option.
415 Value can be changed at runtime via
416 /selinux/checkreqprot.
418 cio_ignore= [S390]
419 See Documentation/s390/CommonIO for details.
421 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
422 [Deprecated]
423 Forces specified clocksource (if available) to be used
424 when calculating gettimeofday(). If specified
425 clocksource is not available, it defaults to PIT.
426 Format: { pit | tsc | cyclone | pmtmr }
428 clocksource= [GENERIC_TIME] Override the default clocksource
429 Format: <string>
430 Override the default clocksource and use the clocksource
431 with the name specified.
432 Some clocksource names to choose from, depending on
433 the platform:
434 [all] jiffies (this is the base, fallback clocksource)
435 [ACPI] acpi_pm
436 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
437 pxa_timer,timer3,32k_counter,timer0_1
438 [AVR32] avr32
439 [X86-32] pit,hpet,tsc,vmi-timer;
440 scx200_hrt on Geode; cyclone on IBM x440
441 [MIPS] MIPS
442 [PARISC] cr16
443 [S390] tod
444 [SH] SuperH
445 [SPARC64] tick
446 [X86-64] hpet,tsc
448 clearcpuid=BITNUM [X86]
449 Disable CPUID feature X for the kernel. See
450 include/asm-x86/cpufeature.h for the valid bit numbers.
451 Note the Linux specific bits are not necessarily
452 stable over kernel options, but the vendor specific
453 ones should be.
454 Also note that user programs calling CPUID directly
455 or using the feature without checking anything
456 will still see it. This just prevents it from
457 being used by the kernel or shown in /proc/cpuinfo.
458 Also note the kernel might malfunction if you disable
459 some critical bits.
461 code_bytes [IA32/X86_64] How many bytes of object code to print
462 in an oops report.
463 Range: 0 - 8192
464 Default: 64
466 disable_8254_timer
467 enable_8254_timer
468 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
469 over the 8254 in addition to over the IO-APIC. The
470 kernel tries to set a sensible default.
472 hpet= [X86-32,HPET] option to control HPET usage
473 Format: { enable (default) | disable | force }
474 disable: disable HPET and use PIT instead
475 force: allow force enabled of undocumented chips (ICH4,
476 VIA, nVidia)
478 com20020= [HW,NET] ARCnet - COM20020 chipset
479 Format:
480 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
482 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
483 Format: <io>[,<irq>]
485 com90xx= [HW,NET]
486 ARCnet - COM90xx chipset (memory-mapped buffers)
487 Format: <io>[,<irq>[,<memstart>]]
489 condev= [HW,S390] console device
490 conmode=
492 console= [KNL] Output console device and options.
494 tty<n> Use the virtual console device <n>.
496 ttyS<n>[,options]
497 ttyUSB0[,options]
498 Use the specified serial port. The options are of
499 the form "bbbbpnf", where "bbbb" is the baud rate,
500 "p" is parity ("n", "o", or "e"), "n" is number of
501 bits, and "f" is flow control ("r" for RTS or
502 omit it). Default is "9600n8".
504 See Documentation/serial-console.txt for more
505 information. See
506 Documentation/networking/netconsole.txt for an
507 alternative.
509 uart[8250],io,<addr>[,options]
510 uart[8250],mmio,<addr>[,options]
511 Start an early, polled-mode console on the 8250/16550
512 UART at the specified I/O port or MMIO address,
513 switching to the matching ttyS device later. The
514 options are the same as for ttyS, above.
516 If the device connected to the port is not a TTY but a braille
517 device, prepend "brl," before the device type, for instance
518 console=brl,ttyS0
519 For now, only VisioBraille is supported.
521 earlycon= [KNL] Output early console device and options.
522 uart[8250],io,<addr>[,options]
523 uart[8250],mmio,<addr>[,options]
524 Start an early, polled-mode console on the 8250/16550
525 UART at the specified I/O port or MMIO address.
526 The options are the same as for ttyS, above.
528 no_console_suspend
529 [HW] Never suspend the console
530 Disable suspending of consoles during suspend and
531 hibernate operations. Once disabled, debugging
532 messages can reach various consoles while the rest
533 of the system is being put to sleep (ie, while
534 debugging driver suspend/resume hooks). This may
535 not work reliably with all consoles, but is known
536 to work with serial and VGA consoles.
538 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
539 Format:
540 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
542 crashkernel=nn[KMG]@ss[KMG]
543 [KNL] Reserve a chunk of physical memory to
544 hold a kernel to switch to with kexec on panic.
546 crashkernel=range1:size1[,range2:size2,...][@offset]
547 [KNL] Same as above, but depends on the memory
548 in the running system. The syntax of range is
549 start-[end] where start and end are both
550 a memory unit (amount[KMG]). See also
551 Documentation/kdump/kdump.txt for a example.
553 cs4232= [HW,OSS]
554 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
556 cs89x0_dma= [HW,NET]
557 Format: <dma>
559 cs89x0_media= [HW,NET]
560 Format: { rj45 | aui | bnc }
562 dasd= [HW,NET]
563 See header of drivers/s390/block/dasd_devmap.c.
565 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
566 (one device per port)
567 Format: <port#>,<type>
568 See also Documentation/input/joystick-parport.txt
570 debug [KNL] Enable kernel debugging (events log level).
572 debug_locks_verbose=
573 [KNL] verbose self-tests
574 Format=<0|1>
575 Print debugging info while doing the locking API
576 self-tests.
577 We default to 0 (no extra messages), setting it to
578 1 will print _a lot_ more information - normally
579 only useful to kernel developers.
581 debug_objects [KNL] Enable object debugging
583 debugpat [X86] Enable PAT debugging
585 decnet.addr= [HW,NET]
586 Format: <area>[,<node>]
587 See also Documentation/networking/decnet.txt.
589 vt.default_blu= [VT]
590 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
591 Change the default blue palette of the console.
592 This is a 16-member array composed of values
593 ranging from 0-255.
595 vt.default_grn= [VT]
596 Format: <green0>,<green1>,<green2>,...,<green15>
597 Change the default green palette of the console.
598 This is a 16-member array composed of values
599 ranging from 0-255.
601 vt.default_red= [VT]
602 Format: <red0>,<red1>,<red2>,...,<red15>
603 Change the default red palette of the console.
604 This is a 16-member array composed of values
605 ranging from 0-255.
607 vt.default_utf8=
608 [VT]
609 Format=<0|1>
610 Set system-wide default UTF-8 mode for all tty's.
611 Default is 1, i.e. UTF-8 mode is enabled for all
612 newly opened terminals.
614 dhash_entries= [KNL]
615 Set number of hash buckets for dentry cache.
617 digi= [HW,SERIAL]
618 IO parameters + enable/disable command.
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/digiepca.txt.
624 disable_mtrr_cleanup [X86]
625 enable_mtrr_cleanup [X86]
626 The kernel tries to adjust MTRR layout from continuous
627 to discrete, to make X server driver able to add WB
628 entry later. This parameter enables/disables that.
630 mtrr_chunk_size=nn[KMG] [X86]
631 used for mtrr cleanup. It is largest continous chunk
632 that could hold holes aka. UC entries.
634 mtrr_gran_size=nn[KMG] [X86]
635 Used for mtrr cleanup. It is granularity of mtrr block.
636 Default is 1.
637 Large value could prevent small alignment from
638 using up MTRRs.
640 mtrr_spare_reg_nr=n [X86]
641 Format: <integer>
642 Range: 0,7 : spare reg number
643 Default : 1
644 Used for mtrr cleanup. It is spare mtrr entries number.
645 Set to 2 or more if your graphical card needs more.
647 disable_mtrr_trim [X86, Intel and AMD only]
648 By default the kernel will trim any uncacheable
649 memory out of your available memory pool based on
650 MTRR settings. This parameter disables that behavior,
651 possibly causing your machine to run very slowly.
653 dmasound= [HW,OSS] Sound subsystem buffers
655 dscc4.setup= [NET]
657 dtc3181e= [HW,SCSI]
659 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
660 earlyprintk=vga
661 earlyprintk=serial[,ttySn[,baudrate]]
663 Append ",keep" to not disable it when the real console
664 takes over.
666 Only vga or serial at a time, not both.
668 Currently only ttyS0 and ttyS1 are supported.
670 Interaction with the standard serial driver is not
671 very good.
673 The VGA output is eventually overwritten by the real
674 console.
676 eata= [HW,SCSI]
678 edd= [EDD]
679 Format: {"off" | "on" | "skip[mbr]"}
681 eisa_irq_edge= [PARISC,HW]
682 See header of drivers/parisc/eisa.c.
684 elanfreq= [X86-32]
685 See comment before function elanfreq_setup() in
686 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
688 elevator= [IOSCHED]
689 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
690 See Documentation/block/as-iosched.txt and
691 Documentation/block/deadline-iosched.txt for details.
693 elfcorehdr= [X86-32, X86_64]
694 Specifies physical address of start of kernel core
695 image elf header. Generally kexec loader will
696 pass this option to capture kernel.
697 See Documentation/kdump/kdump.txt for details.
699 enforcing [SELINUX] Set initial enforcing status.
700 Format: {"0" | "1"}
701 See security/selinux/Kconfig help text.
702 0 -- permissive (log only, no denials).
703 1 -- enforcing (deny and log).
704 Default value is 0.
705 Value can be changed at runtime via /selinux/enforce.
707 es1371= [HW,OSS]
708 Format: <spdif>,[<nomix>,[<amplifier>]]
709 See also header of sound/oss/es1371.c.
711 ether= [HW,NET] Ethernet cards parameters
712 This option is obsoleted by the "netdev=" option, which
713 has equivalent usage. See its documentation for details.
715 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
716 Format: <io>[,<irq>]
718 failslab=
719 fail_page_alloc=
720 fail_make_request=[KNL]
721 General fault injection mechanism.
722 Format: <interval>,<probability>,<space>,<times>
723 See also /Documentation/fault-injection/.
725 fd_mcs= [HW,SCSI]
726 See header of drivers/scsi/fd_mcs.c.
728 fdomain= [HW,SCSI]
729 See header of drivers/scsi/fdomain.c.
731 floppy= [HW]
732 See Documentation/floppy.txt.
734 force_pal_cache_flush
735 [IA-64] Avoid check_sal_cache_flush which may hang on
736 buggy SAL_CACHE_FLUSH implementations. Using this
737 parameter will force ia64_sal_cache_flush to call
738 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
740 gamecon.map[2|3]=
741 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
742 support via parallel port (up to 5 devices per port)
743 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
744 See also Documentation/input/joystick-parport.txt
746 gamma= [HW,DRM]
748 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
749 Format: off | on
750 default: on
752 gdth= [HW,SCSI]
753 See header of drivers/scsi/gdth.c.
755 gpt [EFI] Forces disk with valid GPT signature but
756 invalid Protective MBR to be treated as GPT.
758 gvp11= [HW,SCSI]
760 hashdist= [KNL,NUMA] Large hashes allocated during boot
761 are distributed across NUMA nodes. Defaults on
762 for IA-64, off otherwise.
763 Format: 0 | 1 (for off | on)
765 hcl= [IA-64] SGI's Hardware Graph compatibility layer
767 hd= [EIDE] (E)IDE hard drive subsystem geometry
768 Format: <cyl>,<head>,<sect>
770 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
771 size of <nn>. This works even on boxes that have no
772 highmem otherwise. This also works to reduce highmem
773 size on bigger boxes.
775 highres= [KNL] Enable/disable high resolution timer mode.
776 Valid parameters: "on", "off"
777 Default: "on"
779 hisax= [HW,ISDN]
780 See Documentation/isdn/README.HiSax.
782 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
783 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
784 On x86-64 and powerpc, this option can be specified
785 multiple times interleaved with hugepages= to reserve
786 huge pages of different sizes. Valid pages sizes on
787 x86-64 are 2M (when the CPU supports "pse") and 1G
788 (when the CPU supports the "pdpe1gb" cpuinfo flag)
789 Note that 1GB pages can only be allocated at boot time
790 using hugepages= and not freed afterwards.
791 default_hugepagesz=
792 [same as hugepagesz=] The size of the default
793 HugeTLB page size. This is the size represented by
794 the legacy /proc/ hugepages APIs, used for SHM, and
795 default size when mounting hugetlbfs filesystems.
796 Defaults to the default architecture's huge page size
797 if not specified.
799 i8042.direct [HW] Put keyboard port into non-translated mode
800 i8042.dumbkbd [HW] Pretend that controller can only read data from
801 keyboard and cannot control its state
802 (Don't attempt to blink the leds)
803 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
804 i8042.nokbd [HW] Don't check/create keyboard port
805 i8042.noloop [HW] Disable the AUX Loopback command while probing
806 for the AUX port
807 i8042.nomux [HW] Don't check presence of an active multiplexing
808 controller
809 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
810 controllers
811 i8042.panicblink=
812 [HW] Frequency with which keyboard LEDs should blink
813 when kernel panics (default is 0.5 sec)
814 i8042.reset [HW] Reset the controller during init and cleanup
815 i8042.unlock [HW] Unlock (ignore) the keylock
817 i810= [HW,DRM]
819 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
820 indicates that the driver is running on unsupported
821 hardware.
822 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
823 does not match list of supported models.
824 i8k.power_status
825 [HW] Report power status in /proc/i8k
826 (disabled by default)
827 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
828 capability is set.
830 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
831 See Documentation/mca.txt.
833 icn= [HW,ISDN]
834 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
836 ide= [HW] (E)IDE subsystem
837 Format: ide=nodma or ide=doubler
838 See Documentation/ide/ide.txt.
840 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
841 See Documentation/ide/ide.txt.
843 idle= [X86]
844 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
845 Poll forces a polling idle loop that can slightly improves the performance
846 of waking up a idle CPU, but will use a lot of power and make the system
847 run hot. Not recommended.
848 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
849 to not use it because it doesn't save as much power as a normal idle
850 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
851 as idle=poll.
852 idle=halt. Halt is forced to be used for CPU idle.
853 In such case C2/C3 won't be used again.
854 idle=nomwait. Disable mwait for CPU C-states
856 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
857 Claim all unknown PCI IDE storage controllers.
859 ignore_loglevel [KNL]
860 Ignore loglevel setting - this will print /all/
861 kernel messages to the console. Useful for debugging.
863 ihash_entries= [KNL]
864 Set number of hash buckets for inode cache.
866 in2000= [HW,SCSI]
867 See header of drivers/scsi/in2000.c.
869 init= [KNL]
870 Format: <full_path>
871 Run specified binary instead of /sbin/init as init
872 process.
874 initcall_debug [KNL] Trace initcalls as they are executed. Useful
875 for working out where the kernel is dying during
876 startup.
878 initrd= [BOOT] Specify the location of the initial ramdisk
880 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
881 Format: <irq>
883 inttest= [IA64]
885 iommu= [x86]
886 off
887 force
888 noforce
889 biomerge
890 panic
891 nopanic
892 merge
893 nomerge
894 forcesac
895 soft
898 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
899 off
900 Disable intel iommu driver.
901 igfx_off [Default Off]
902 By default, gfx is mapped as normal device. If a gfx
903 device has a dedicated DMAR unit, the DMAR unit is
904 bypassed by not enabling DMAR with this option. In
905 this case, gfx device will use physical address for
906 DMA.
907 forcedac [x86_64]
908 With this option iommu will not optimize to look
909 for io virtual address below 32 bit forcing dual
910 address cycle on pci bus for cards supporting greater
911 than 32 bit addressing. The default is to look
912 for translation below 32 bit and if not available
913 then look in the higher range.
914 strict [Default Off]
915 With this option on every unmap_single operation will
916 result in a hardware IOTLB flush operation as opposed
917 to batching them for performance.
919 io_delay= [X86-32,X86-64] I/O delay method
920 0x80
921 Standard port 0x80 based delay
922 0xed
923 Alternate port 0xed based delay (needed on some systems)
924 udelay
925 Simple two microseconds delay
926 none
927 No delay
929 io7= [HW] IO7 for Marvel based alpha systems
930 See comment before marvel_specify_io7 in
931 arch/alpha/kernel/core_marvel.c.
933 ip= [IP_PNP]
934 See Documentation/filesystems/nfsroot.txt.
936 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
937 See comment before ip2_setup() in
938 drivers/char/ip2/ip2base.c.
940 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
941 See header of drivers/scsi/ips.c.
943 ports= [IP_VS_FTP] IPVS ftp helper module
944 Default is 21.
945 Up to 8 (IP_VS_APP_MAX_PORTS) ports
946 may be specified.
947 Format: <port>,<port>....
949 irqfixup [HW]
950 When an interrupt is not handled search all handlers
951 for it. Intended to get systems with badly broken
952 firmware running.
954 irqpoll [HW]
955 When an interrupt is not handled search all handlers
956 for it. Also check all handlers each timer
957 interrupt. Intended to get systems with badly broken
958 firmware running.
960 isapnp= [ISAPNP]
961 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
963 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
964 Format:
965 <cpu number>,...,<cpu number>
966 or
967 <cpu number>-<cpu number> (must be a positive range in ascending order)
968 or a mixture
969 <cpu number>,...,<cpu number>-<cpu number>
970 This option can be used to specify one or more CPUs
971 to isolate from the general SMP balancing and scheduling
972 algorithms. The only way to move a process onto or off
973 an "isolated" CPU is via the CPU affinity syscalls.
974 <cpu number> begins at 0 and the maximum value is
975 "number of CPUs in system - 1".
977 This option is the preferred way to isolate CPUs. The
978 alternative -- manually setting the CPU mask of all
979 tasks in the system -- can cause problems and
980 suboptimal load balancer performance.
982 iucv= [HW,NET]
984 js= [HW,JOY] Analog joystick
985 See Documentation/input/joystick.txt.
987 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
988 specifies the amount of memory usable by the kernel
989 for non-movable allocations. The requested amount is
990 spread evenly throughout all nodes in the system. The
991 remaining memory in each node is used for Movable
992 pages. In the event, a node is too small to have both
993 kernelcore and Movable pages, kernelcore pages will
994 take priority and other nodes will have a larger number
995 of kernelcore pages. The Movable zone is used for the
996 allocation of pages that may be reclaimed or moved
997 by the page migration subsystem. This means that
998 HugeTLB pages may not be allocated from this zone.
999 Note that allocations like PTEs-from-HighMem still
1000 use the HighMem zone if it exists, and the Normal
1001 zone if it does not.
1003 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1004 is similar to kernelcore except it specifies the
1005 amount of memory used for migratable allocations.
1006 If both kernelcore and movablecore is specified,
1007 then kernelcore will be at *least* the specified
1008 value but may be more. If movablecore on its own
1009 is specified, the administrator must be careful
1010 that the amount of memory usable for all allocations
1011 is not too small.
1013 keepinitrd [HW,ARM]
1015 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1016 in oops dumps.
1018 kgdboc= [HW] kgdb over consoles.
1019 Requires a tty driver that supports console polling.
1020 (only serial suported for now)
1021 Format: <serial_device>[,baud]
1023 l2cr= [PPC]
1025 l3cr= [PPC]
1027 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1028 disabled it.
1030 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1031 C2 power state.
1033 libata.dma= [LIBATA] DMA control
1034 libata.dma=0 Disable all PATA and SATA DMA
1035 libata.dma=1 PATA and SATA Disk DMA only
1036 libata.dma=2 ATAPI (CDROM) DMA only
1037 libata.dma=4 Compact Flash DMA only
1038 Combinations also work, so libata.dma=3 enables DMA
1039 for disks and CDROMs, but not CFs.
1041 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1042 when set.
1043 Format: <int>
1045 libata.force= [LIBATA] Force configurations. The format is comma
1046 separated list of "[ID:]VAL" where ID is
1047 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1048 matching port, link or device. Basically, it matches
1049 the ATA ID string printed on console by libata. If
1050 the whole ID part is omitted, the last PORT and DEVICE
1051 values are used. If ID hasn't been specified yet, the
1052 configuration applies to all ports, links and devices.
1054 If only DEVICE is omitted, the parameter applies to
1055 the port and all links and devices behind it. DEVICE
1056 number of 0 either selects the first device or the
1057 first fan-out link behind PMP device. It does not
1058 select the host link. DEVICE number of 15 selects the
1059 host link and device attached to it.
1061 The VAL specifies the configuration to force. As long
1062 as there's no ambiguity shortcut notation is allowed.
1063 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1064 The following configurations can be forced.
1066 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1067 Any ID with matching PORT is used.
1069 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1071 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1072 udma[/][16,25,33,44,66,100,133] notation is also
1073 allowed.
1075 * [no]ncq: Turn on or off NCQ.
1077 * nohrst, nosrst, norst: suppress hard, soft
1078 and both resets.
1080 If there are multiple matching configurations changing
1081 the same attribute, the last one is used.
1083 load_ramdisk= [RAM] List of ramdisks to load from floppy
1084 See Documentation/ramdisk.txt.
1086 lockd.nlm_grace_period=P [NFS] Assign grace period.
1087 Format: <integer>
1089 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1090 Format: <integer>
1092 lockd.nlm_timeout=T [NFS] Assign timeout value.
1093 Format: <integer>
1095 lockd.nlm_udpport=M [NFS] Assign UDP port.
1096 Format: <integer>
1098 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1099 Format: <irq>
1101 loglevel= All Kernel Messages with a loglevel smaller than the
1102 console loglevel will be printed to the console. It can
1103 also be changed with klogd or other programs. The
1104 loglevels are defined as follows:
1106 0 (KERN_EMERG) system is unusable
1107 1 (KERN_ALERT) action must be taken immediately
1108 2 (KERN_CRIT) critical conditions
1109 3 (KERN_ERR) error conditions
1110 4 (KERN_WARNING) warning conditions
1111 5 (KERN_NOTICE) normal but significant condition
1112 6 (KERN_INFO) informational
1113 7 (KERN_DEBUG) debug-level messages
1115 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1116 Format: { n | nk | nM }
1117 n must be a power of two. The default size
1118 is set in the kernel config file.
1120 logo.nologo [FB] Disables display of the built-in Linux logo.
1121 This may be used to provide more screen space for
1122 kernel log messages and is useful when debugging
1123 kernel boot problems.
1125 lp=0 [LP] Specify parallel ports to use, e.g,
1126 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1127 lp=reset first parallel port). 'lp=0' disables the
1128 lp=auto printer driver. 'lp=reset' (which can be
1129 specified in addition to the ports) causes
1130 attached printers to be reset. Using
1131 lp=port1,port2,... specifies the parallel ports
1132 to associate lp devices with, starting with
1133 lp0. A port specification may be 'none' to skip
1134 that lp device, or a parport name such as
1135 'parport0'. Specifying 'lp=auto' instead of a
1136 port specification list means that device IDs
1137 from each port should be examined, to see if
1138 an IEEE 1284-compliant printer is attached; if
1139 so, the driver will manage that printer.
1140 See also header of drivers/char/lp.c.
1142 lpj=n [KNL]
1143 Sets loops_per_jiffy to given constant, thus avoiding
1144 time-consuming boot-time autodetection (up to 250 ms per
1145 CPU). 0 enables autodetection (default). To determine
1146 the correct value for your kernel, boot with normal
1147 autodetection and see what value is printed. Note that
1148 on SMP systems the preset will be applied to all CPUs,
1149 which is likely to cause problems if your CPUs need
1150 significantly divergent settings. An incorrect value
1151 will cause delays in the kernel to be wrong, leading to
1152 unpredictable I/O errors and other breakage. Although
1153 unlikely, in the extreme case this might damage your
1154 hardware.
1156 ltpc= [NET]
1157 Format: <io>,<irq>,<dma>
1159 mac5380= [HW,SCSI] Format:
1160 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1162 machvec= [IA64] Force the use of a particular machine-vector
1163 (machvec) in a generic kernel.
1164 Example: machvec=hpzx1_swiotlb
1166 max_loop= [LOOP] Maximum number of loopback devices that can
1167 be mounted
1168 Format: <1-256>
1170 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1171 should make use of. maxcpus=n : n >= 0 limits the
1172 kernel to using 'n' processors. n=0 is a special case,
1173 it is equivalent to "nosmp", which also disables
1174 the IO APIC.
1176 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1177 equal to this physical address is ignored.
1179 max_luns= [SCSI] Maximum number of LUNs to probe.
1180 Should be between 1 and 2^32-1.
1182 max_report_luns=
1183 [SCSI] Maximum number of LUNs received.
1184 Should be between 1 and 16384.
1186 mcatest= [IA-64]
1188 mce [X86-32] Machine Check Exception
1190 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1192 md= [HW] RAID subsystems devices and level
1193 See Documentation/md.txt.
1195 mdacon= [MDA]
1196 Format: <first>,<last>
1197 Specifies range of consoles to be captured by the MDA.
1199 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1200 Amount of memory to be used when the kernel is not able
1201 to see the whole system memory or for test.
1202 [X86-32] Use together with memmap= to avoid physical
1203 address space collisions. Without memmap= PCI devices
1204 could be placed at addresses belonging to unused RAM.
1206 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1207 memory.
1209 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1210 E820 memory map, as specified by the user.
1211 Such memmap=exactmap lines can be constructed based on
1212 BIOS output or other requirements. See the memmap=nn@ss
1213 option description.
1215 memmap=nn[KMG]@ss[KMG]
1216 [KNL] Force usage of a specific region of memory
1217 Region of memory to be used, from ss to ss+nn.
1219 memmap=nn[KMG]#ss[KMG]
1220 [KNL,ACPI] Mark specific memory as ACPI data.
1221 Region of memory to be used, from ss to ss+nn.
1223 memmap=nn[KMG]$ss[KMG]
1224 [KNL,ACPI] Mark specific memory as reserved.
1225 Region of memory to be used, from ss to ss+nn.
1226 Example: Exclude memory from 0x18690000-0x1869ffff
1227 memmap=64K$0x18690000
1228 or
1229 memmap=0x10000$0x18690000
1231 memtest= [KNL,X86] Enable memtest
1232 Format: <integer>
1233 range: 0,4 : pattern number
1234 default : 0 <disable>
1236 meye.*= [HW] Set MotionEye Camera parameters
1237 See Documentation/video4linux/meye.txt.
1239 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1240 Multi-Function General Purpose Timers on AMD Geode
1241 platforms.
1243 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1244 the BIOS has incorrectly applied a workaround. TinyBIOS
1245 version 0.98 is known to be affected, 0.99 fixes the
1246 problem by letting the user disable the workaround.
1248 mga= [HW,DRM]
1250 mminit_loglevel=
1251 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1252 parameter allows control of the logging verbosity for
1253 the additional memory initialisation checks. A value
1254 of 0 disables mminit logging and a level of 4 will
1255 log everything. Information is printed at KERN_DEBUG
1256 so loglevel=8 may also need to be specified.
1258 mousedev.tap_time=
1259 [MOUSE] Maximum time between finger touching and
1260 leaving touchpad surface for touch to be considered
1261 a tap and be reported as a left button click (for
1262 touchpads working in absolute mode only).
1263 Format: <msecs>
1264 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1265 reporting absolute coordinates, such as tablets
1266 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1267 reporting absolute coordinates, such as tablets
1269 mpu401= [HW,OSS]
1270 Format: <io>,<irq>
1272 MTD_Partition= [MTD]
1273 Format: <name>,<region-number>,<size>,<offset>
1275 MTD_Region= [MTD] Format:
1276 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1278 mtdparts= [MTD]
1279 See drivers/mtd/cmdlinepart.c.
1281 mtdset= [ARM]
1282 ARM/S3C2412 JIVE boot control
1284 See arch/arm/mach-s3c2412/mach-jive.c
1286 mtouchusb.raw_coordinates=
1287 [HW] Make the MicroTouch USB driver use raw coordinates
1288 ('y', default) or cooked coordinates ('n')
1290 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1292 NCR_D700= [HW,SCSI]
1293 See header of drivers/scsi/NCR_D700.c.
1295 ncr5380= [HW,SCSI]
1297 ncr53c400= [HW,SCSI]
1299 ncr53c400a= [HW,SCSI]
1301 ncr53c406a= [HW,SCSI]
1303 ncr53c8xx= [HW,SCSI]
1305 netdev= [NET] Network devices parameters
1306 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1307 Note that mem_start is often overloaded to mean
1308 something different and driver-specific.
1309 This usage is only documented in each driver source
1310 file if at all.
1312 nf_conntrack.acct=
1313 [NETFILTER] Enable connection tracking flow accounting
1314 0 to disable accounting
1315 1 to enable accounting
1316 Default value depends on CONFIG_NF_CT_ACCT that is
1317 going to be removed in 2.6.29.
1319 nfsaddrs= [NFS]
1320 See Documentation/filesystems/nfsroot.txt.
1322 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1323 See Documentation/filesystems/nfsroot.txt.
1325 nfs.callback_tcpport=
1326 [NFS] set the TCP port on which the NFSv4 callback
1327 channel should listen.
1329 nfs.idmap_cache_timeout=
1330 [NFS] set the maximum lifetime for idmapper cache
1331 entries.
1333 nfs.enable_ino64=
1334 [NFS] enable 64-bit inode numbers.
1335 If zero, the NFS client will fake up a 32-bit inode
1336 number for the readdir() and stat() syscalls instead
1337 of returning the full 64-bit number.
1338 The default is to return 64-bit inode numbers.
1340 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1341 when a NMI is triggered.
1342 Format: [state][,regs][,debounce][,die]
1344 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1346 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1347 emulation library even if a 387 maths coprocessor
1348 is present.
1350 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1351 caches in the slab allocator. Saves per-node memory,
1352 but will impact performance.
1354 noalign [KNL,ARM]
1356 noapic [SMP,APIC] Tells the kernel to not make use of any
1357 IOAPICs that may be present in the system.
1359 nobats [PPC] Do not use BATs for mapping kernel lowmem
1360 on "Classic" PPC cores.
1362 nocache [ARM]
1364 nodelayacct [KNL] Disable per-task delay accounting
1366 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1368 noefi [X86-32,X86-64] Disable EFI runtime services support.
1370 noexec [IA-64]
1372 noexec [X86-32,X86-64]
1373 On X86-32 available only on PAE configured kernels.
1374 noexec=on: enable non-executable mappings (default)
1375 noexec=off: disable non-executable mappings
1377 noexec32 [X86-64]
1378 This affects only 32-bit executables.
1379 noexec32=on: enable non-executable mappings (default)
1380 read doesn't imply executable mappings
1381 noexec32=off: disable non-executable mappings
1382 read implies executable mappings
1384 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1385 register save and restore. The kernel will only save
1386 legacy floating-point registers on task switch.
1388 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1390 nohlt [BUGS=ARM]
1392 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1393 instruction doesn't work correctly and not to
1394 use it.
1396 nohalt [IA-64] Tells the kernel not to use the power saving
1397 function PAL_HALT_LIGHT when idle. This increases
1398 power-consumption. On the positive side, it reduces
1399 interrupt wake-up latency, which may improve performance
1400 in certain environments such as networked servers or
1401 real-time systems.
1403 nohz= [KNL] Boottime enable/disable dynamic ticks
1404 Valid arguments: on, off
1405 Default: on
1407 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1409 noirqdebug [X86-32] Disables the code which attempts to detect and
1410 disable unhandled interrupt sources.
1412 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1413 broken timer IRQ sources.
1415 noisapnp [ISAPNP] Disables ISA PnP code.
1417 noinitrd [RAM] Tells the kernel not to load any configured
1418 initial RAM disk.
1420 nointroute [IA-64]
1422 nojitter [IA64] Disables jitter checking for ITC timers.
1424 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1426 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1428 noltlbs [PPC] Do not use large page/tlb entries for kernel
1429 lowmem mapping on PPC40x.
1431 nomca [IA-64] Disable machine check abort handling
1433 nomce [X86-32] Machine Check Exception
1435 nomfgpt [X86-32] Disable Multi-Function General Purpose
1436 Timer usage (for AMD Geode machines).
1438 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1440 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1441 with UP alternatives
1443 noresidual [PPC] Don't use residual data on PReP machines.
1445 noresume [SWSUSP] Disables resume and restores original swap
1446 space.
1448 no-scroll [VGA] Disables scrollback.
1449 This is required for the Braillex ib80-piezo Braille
1450 reader made by F.H. Papenmeier (Germany).
1452 nosbagart [IA-64]
1454 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1456 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1457 and disable the IO APIC. legacy for "maxcpus=0".
1459 nosoftlockup [KNL] Disable the soft-lockup detector.
1461 nosync [HW,M68K] Disables sync negotiation for all devices.
1463 notsc [BUGS=X86-32] Disable Time Stamp Counter
1465 nousb [USB] Disable the USB subsystem
1467 nowb [ARM]
1469 nptcg= [IA64] Override max number of concurrent global TLB
1470 purges which is reported from either PAL_VM_SUMMARY or
1471 SAL PALO.
1473 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1474 one of ['zone', 'node', 'default'] can be specified
1475 This can be set from sysctl after boot.
1476 See Documentation/sysctl/vm.txt for details.
1478 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1480 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1481 Rather than timing out after 20 ms if an EC
1482 command is not properly ACKed, override the length
1483 of the timeout. We have interrupts disabled while
1484 waiting for the ACK, so if this is set too high
1485 interrupts *may* be lost!
1487 opl3= [HW,OSS]
1488 Format: <io>
1490 oprofile.timer= [HW]
1491 Use timer interrupt instead of performance counters
1493 osst= [HW,SCSI] SCSI Tape Driver
1494 Format: <buffer_size>,<write_threshold>
1495 See also Documentation/scsi/st.txt.
1497 panic= [KNL] Kernel behaviour on panic
1498 Format: <timeout>
1500 parkbd.port= [HW] Parallel port number the keyboard adapter is
1501 connected to, default is 0.
1502 Format: <parport#>
1503 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1504 0 for XT, 1 for AT (default is AT).
1505 Format: <mode>
1507 parport= [HW,PPT] Specify parallel ports. 0 disables.
1508 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1509 Use 'auto' to force the driver to use any
1510 IRQ/DMA settings detected (the default is to
1511 ignore detected IRQ/DMA settings because of
1512 possible conflicts). You can specify the base
1513 address, IRQ, and DMA settings; IRQ and DMA
1514 should be numbers, or 'auto' (for using detected
1515 settings on that particular port), or 'nofifo'
1516 (to avoid using a FIFO even if it is detected).
1517 Parallel ports are assigned in the order they
1518 are specified on the command line, starting
1519 with parport0.
1521 parport_init_mode= [HW,PPT]
1522 Configure VIA parallel port to operate in
1523 a specific mode. This is necessary on Pegasos
1524 computer where firmware has no options for setting
1525 up parallel port mode and sets it to spp.
1526 Currently this function knows 686a and 8231 chips.
1527 Format: [spp|ps2|epp|ecp|ecpepp]
1529 pas2= [HW,OSS] Format:
1530 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1532 pas16= [HW,SCSI]
1533 See header of drivers/scsi/pas16.c.
1535 pause_on_oops=
1536 Halt all CPUs after the first oops has been printed for
1537 the specified number of seconds. This is to be used if
1538 your oopses keep scrolling off the screen.
1540 pcbit= [HW,ISDN]
1542 pcd. [PARIDE]
1543 See header of drivers/block/paride/pcd.c.
1544 See also Documentation/paride.txt.
1546 pci=option[,option...] [PCI] various PCI subsystem options:
1547 off [X86-32] don't probe for the PCI bus
1548 bios [X86-32] force use of PCI BIOS, don't access
1549 the hardware directly. Use this if your machine
1550 has a non-standard PCI host bridge.
1551 nobios [X86-32] disallow use of PCI BIOS, only direct
1552 hardware access methods are allowed. Use this
1553 if you experience crashes upon bootup and you
1554 suspect they are caused by the BIOS.
1555 conf1 [X86-32] Force use of PCI Configuration
1556 Mechanism 1.
1557 conf2 [X86-32] Force use of PCI Configuration
1558 Mechanism 2.
1559 noaer [PCIE] If the PCIEAER kernel config parameter is
1560 enabled, this kernel boot option can be used to
1561 disable the use of PCIE advanced error reporting.
1562 nodomains [PCI] Disable support for multiple PCI
1563 root domains (aka PCI segments, in ACPI-speak).
1564 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1565 Configuration
1566 nomsi [MSI] If the PCI_MSI kernel config parameter is
1567 enabled, this kernel boot option can be used to
1568 disable the use of MSI interrupts system-wide.
1569 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1570 routing table. These calls are known to be buggy
1571 on several machines and they hang the machine
1572 when used, but on other computers it's the only
1573 way to get the interrupt routing table. Try
1574 this option if the kernel is unable to allocate
1575 IRQs or discover secondary PCI buses on your
1576 motherboard.
1577 rom [X86-32] Assign address space to expansion ROMs.
1578 Use with caution as certain devices share
1579 address decoders between ROMs and other
1580 resources.
1581 norom [X86-32,X86_64] Do not assign address space to
1582 expansion ROMs that do not already have
1583 BIOS assigned address ranges.
1584 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1585 assigned automatically to PCI devices. You can
1586 make the kernel exclude IRQs of your ISA cards
1587 this way.
1588 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1589 of the PIRQ table (normally generated
1590 by the BIOS) if it is outside the
1591 F0000h-100000h range.
1592 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1593 useful if the kernel is unable to find your
1594 secondary buses and you want to tell it
1595 explicitly which ones they are.
1596 assign-busses [X86-32] Always assign all PCI bus
1597 numbers ourselves, overriding
1598 whatever the firmware may have done.
1599 usepirqmask [X86-32] Honor the possible IRQ mask stored
1600 in the BIOS $PIR table. This is needed on
1601 some systems with broken BIOSes, notably
1602 some HP Pavilion N5400 and Omnibook XE3
1603 notebooks. This will have no effect if ACPI
1604 IRQ routing is enabled.
1605 noacpi [X86-32] Do not use ACPI for IRQ routing
1606 or for PCI scanning.
1607 use_crs [X86-32] Use _CRS for PCI resource
1608 allocation.
1609 routeirq Do IRQ routing for all PCI devices.
1610 This is normally done in pci_enable_device(),
1611 so this option is a temporary workaround
1612 for broken drivers that don't call it.
1613 skip_isa_align [X86] do not align io start addr, so can
1614 handle more pci cards
1615 firmware [ARM] Do not re-enumerate the bus but instead
1616 just use the configuration from the
1617 bootloader. This is currently used on
1618 IXP2000 systems where the bus has to be
1619 configured a certain way for adjunct CPUs.
1620 noearly [X86] Don't do any early type 1 scanning.
1621 This might help on some broken boards which
1622 machine check when some devices' config space
1623 is read. But various workarounds are disabled
1624 and some IOMMU drivers will not work.
1625 bfsort Sort PCI devices into breadth-first order.
1626 This sorting is done to get a device
1627 order compatible with older (<= 2.4) kernels.
1628 nobfsort Don't sort PCI devices into breadth-first order.
1629 cbiosize=nn[KMG] The fixed amount of bus space which is
1630 reserved for the CardBus bridge's IO window.
1631 The default value is 256 bytes.
1632 cbmemsize=nn[KMG] The fixed amount of bus space which is
1633 reserved for the CardBus bridge's memory
1634 window. The default value is 64 megabytes.
1636 pcmv= [HW,PCMCIA] BadgePAD 4
1638 pd. [PARIDE]
1639 See Documentation/paride.txt.
1641 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1642 boot time.
1643 Format: { 0 | 1 }
1644 See arch/parisc/kernel/pdc_chassis.c
1646 pf. [PARIDE]
1647 See Documentation/paride.txt.
1649 pg. [PARIDE]
1650 See Documentation/paride.txt.
1652 pirq= [SMP,APIC] Manual mp-table setup
1653 See Documentation/i386/IO-APIC.txt.
1655 plip= [PPT,NET] Parallel port network link
1656 Format: { parport<nr> | timid | 0 }
1657 See also Documentation/parport.txt.
1659 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1660 Override pmtimer IOPort with a hex value.
1661 e.g. pmtmr=0x508
1663 pnpacpi= [ACPI]
1664 { off }
1666 pnpbios= [ISAPNP]
1667 { on | off | curr | res | no-curr | no-res }
1669 pnp_reserve_irq=
1670 [ISAPNP] Exclude IRQs for the autoconfiguration
1672 pnp_reserve_dma=
1673 [ISAPNP] Exclude DMAs for the autoconfiguration
1675 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1676 Ranges are in pairs (I/O port base and size).
1678 pnp_reserve_mem=
1679 [ISAPNP] Exclude memory regions for the
1680 autoconfiguration.
1681 Ranges are in pairs (memory base and size).
1683 print-fatal-signals=
1684 [KNL] debug: print fatal signals
1685 print-fatal-signals=1: print segfault info to
1686 the kernel console.
1687 default: off.
1689 printk.time= Show timing data prefixed to each printk message line
1690 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1692 profile= [KNL] Enable kernel profiling via /proc/profile
1693 Format: [schedule,]<number>
1694 Param: "schedule" - profile schedule points.
1695 Param: <number> - step/bucket size as a power of 2 for
1696 statistical time based profiling.
1697 Param: "sleep" - profile D-state sleeping (millisecs).
1698 Requires CONFIG_SCHEDSTATS
1699 Param: "kvm" - profile VM exits.
1701 processor.max_cstate= [HW,ACPI]
1702 Limit processor to maximum C-state
1703 max_cstate=9 overrides any DMI blacklist limit.
1705 processor.nocst [HW,ACPI]
1706 Ignore the _CST method to determine C-states,
1707 instead using the legacy FADT method
1709 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1710 before loading.
1711 See Documentation/ramdisk.txt.
1713 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1714 probe for; one of (bare|imps|exps|lifebook|any).
1715 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1716 per second.
1717 psmouse.resetafter= [HW,MOUSE]
1718 Try to reset the device after so many bad packets
1719 (0 = never).
1720 psmouse.resolution=
1721 [HW,MOUSE] Set desired mouse resolution, in dpi.
1722 psmouse.smartscroll=
1723 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1724 0 = disabled, 1 = enabled (default).
1726 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1727 Format:
1728 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1730 pt. [PARIDE]
1731 See Documentation/paride.txt.
1733 pty.legacy_count=
1734 [KNL] Number of legacy pty's. Overwrites compiled-in
1735 default number.
1737 quiet [KNL] Disable most log messages
1739 r128= [HW,DRM]
1741 raid= [HW,RAID]
1742 See Documentation/md.txt.
1744 ramdisk_blocksize= [RAM]
1745 See Documentation/ramdisk.txt.
1747 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1748 See Documentation/ramdisk.txt.
1750 rcupdate.blimit= [KNL,BOOT]
1751 Set maximum number of finished RCU callbacks to process
1752 in one batch.
1754 rcupdate.qhimark= [KNL,BOOT]
1755 Set threshold of queued
1756 RCU callbacks over which batch limiting is disabled.
1758 rcupdate.qlowmark= [KNL,BOOT]
1759 Set threshold of queued RCU callbacks below which
1760 batch limiting is re-enabled.
1762 rdinit= [KNL]
1763 Format: <full_path>
1764 Run specified binary instead of /init from the ramdisk,
1765 used for early userspace startup. See initrd.
1767 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1768 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1769 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1771 relax_domain_level=
1772 [KNL, SMP] Set scheduler's default relax_domain_level.
1773 See Documentation/cpusets.txt.
1775 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1777 reservetop= [X86-32]
1778 Format: nn[KMG]
1779 Reserves a hole at the top of the kernel virtual
1780 address space.
1782 reset_devices [KNL] Force drivers to reset the underlying device
1783 during initialization.
1785 resume= [SWSUSP]
1786 Specify the partition device for software suspend
1788 resume_offset= [SWSUSP]
1789 Specify the offset from the beginning of the partition
1790 given by "resume=" at which the swap header is located,
1791 in <PAGE_SIZE> units (needed only for swap files).
1792 See Documentation/power/swsusp-and-swap-files.txt
1794 retain_initrd [RAM] Keep initrd memory after extraction
1796 rhash_entries= [KNL,NET]
1797 Set number of hash buckets for route cache
1799 riscom8= [HW,SERIAL]
1800 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1802 ro [KNL] Mount root device read-only on boot
1804 root= [KNL] Root filesystem
1806 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1807 mount the root filesystem
1809 rootflags= [KNL] Set root filesystem mount option string
1811 rootfstype= [KNL] Set root filesystem type
1813 rootwait [KNL] Wait (indefinitely) for root device to show up.
1814 Useful for devices that are detected asynchronously
1815 (e.g. USB and MMC devices).
1817 root_plug.vendor_id=
1818 [ROOTPLUG] Override the default vendor ID
1820 root_plug.product_id=
1821 [ROOTPLUG] Override the default product ID
1823 root_plug.debug=
1824 [ROOTPLUG] Enable debugging output
1826 rw [KNL] Mount root device read-write on boot
1828 S [KNL] Run init in single mode
1830 sa1100ir [NET]
1831 See drivers/net/irda/sa1100_ir.c.
1833 sbni= [NET] Granch SBNI12 leased line adapter
1835 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1836 Format: <io>[,<timeout>[,<isapnp>]]
1838 scsi_debug_*= [SCSI]
1839 See drivers/scsi/scsi_debug.c.
1841 scsi_default_dev_flags=
1842 [SCSI] SCSI default device flags
1843 Format: <integer>
1845 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1846 Format: <vendor>:<model>:<flags>
1847 (flags are integer value)
1849 scsi_logging_level= [SCSI] a bit mask of logging levels
1850 See drivers/scsi/scsi_logging.h for bits. Also
1851 settable via sysctl at dev.scsi.logging_level
1852 (/proc/sys/dev/scsi/logging_level).
1853 There is also a nice 'scsi_logging_level' script in the
1854 S390-tools package, available for download at
1855 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1857 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1858 discovered. async scans them in kernel threads,
1859 allowing boot to proceed. none ignores them, expecting
1860 user space to do the scan.
1862 selinux [SELINUX] Disable or enable SELinux at boot time.
1863 Format: { "0" | "1" }
1864 See security/selinux/Kconfig help text.
1865 0 -- disable.
1866 1 -- enable.
1867 Default value is set via kernel config option.
1868 If enabled at boot time, /selinux/disable can be used
1869 later to disable prior to initial policy load.
1871 selinux_compat_net =
1872 [SELINUX] Set initial selinux_compat_net flag value.
1873 Format: { "0" | "1" }
1874 0 -- use new secmark-based packet controls
1875 1 -- use legacy packet controls
1876 Default value is 0 (preferred).
1877 Value can be changed at runtime via
1878 /selinux/compat_net.
1880 serialnumber [BUGS=X86-32]
1882 shapers= [NET]
1883 Maximal number of shapers.
1885 sim710= [SCSI,HW]
1886 See header of drivers/scsi/sim710.c.
1888 simeth= [IA-64]
1889 simscsi=
1891 slram= [HW,MTD]
1893 slub_debug[=options[,slabs]] [MM, SLUB]
1894 Enabling slub_debug allows one to determine the
1895 culprit if slab objects become corrupted. Enabling
1896 slub_debug can create guard zones around objects and
1897 may poison objects when not in use. Also tracks the
1898 last alloc / free. For more information see
1899 Documentation/vm/slub.txt.
1901 slub_max_order= [MM, SLUB]
1902 Determines the maximum allowed order for slabs.
1903 A high setting may cause OOMs due to memory
1904 fragmentation. For more information see
1905 Documentation/vm/slub.txt.
1907 slub_min_objects= [MM, SLUB]
1908 The minimum number of objects per slab. SLUB will
1909 increase the slab order up to slub_max_order to
1910 generate a sufficiently large slab able to contain
1911 the number of objects indicated. The higher the number
1912 of objects the smaller the overhead of tracking slabs
1913 and the less frequently locks need to be acquired.
1914 For more information see Documentation/vm/slub.txt.
1916 slub_min_order= [MM, SLUB]
1917 Determines the mininum page order for slabs. Must be
1918 lower than slub_max_order.
1919 For more information see Documentation/vm/slub.txt.
1921 slub_nomerge [MM, SLUB]
1922 Disable merging of slabs with similar size. May be
1923 necessary if there is some reason to distinguish
1924 allocs to different slabs. Debug options disable
1925 merging on their own.
1926 For more information see Documentation/vm/slub.txt.
1928 smart2= [HW]
1929 Format: <io1>[,<io2>[,...,<io8>]]
1931 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1932 attempt to substitute SMP alternatives once at boot.
1934 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1935 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1936 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1937 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1938 smsc-ircc2.ircc_irq= [HW] IRQ line
1939 smsc-ircc2.ircc_dma= [HW] DMA channel
1940 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1941 0: Toshiba Satellite 1800 (GP data pin select)
1942 1: Fast pin select (default)
1943 2: ATC IRMode
1945 snd-ad1816a= [HW,ALSA]
1947 snd-ad1848= [HW,ALSA]
1949 snd-ali5451= [HW,ALSA]
1951 snd-als100= [HW,ALSA]
1953 snd-als4000= [HW,ALSA]
1955 snd-azt2320= [HW,ALSA]
1957 snd-cmi8330= [HW,ALSA]
1959 snd-cmipci= [HW,ALSA]
1961 snd-cs4231= [HW,ALSA]
1963 snd-cs4232= [HW,ALSA]
1965 snd-cs4236= [HW,ALSA]
1967 snd-cs4281= [HW,ALSA]
1969 snd-cs46xx= [HW,ALSA]
1971 snd-dt019x= [HW,ALSA]
1973 snd-dummy= [HW,ALSA]
1975 snd-emu10k1= [HW,ALSA]
1977 snd-ens1370= [HW,ALSA]
1979 snd-ens1371= [HW,ALSA]
1981 snd-es968= [HW,ALSA]
1983 snd-es1688= [HW,ALSA]
1985 snd-es18xx= [HW,ALSA]
1987 snd-es1938= [HW,ALSA]
1989 snd-es1968= [HW,ALSA]
1991 snd-fm801= [HW,ALSA]
1993 snd-gusclassic= [HW,ALSA]
1995 snd-gusextreme= [HW,ALSA]
1997 snd-gusmax= [HW,ALSA]
1999 snd-hdsp= [HW,ALSA]
2001 snd-ice1712= [HW,ALSA]
2003 snd-intel8x0= [HW,ALSA]
2005 snd-interwave= [HW,ALSA]
2007 snd-interwave-stb=
2008 [HW,ALSA]
2010 snd-korg1212= [HW,ALSA]
2012 snd-maestro3= [HW,ALSA]
2014 snd-mpu401= [HW,ALSA]
2016 snd-mtpav= [HW,ALSA]
2018 snd-nm256= [HW,ALSA]
2020 snd-opl3sa2= [HW,ALSA]
2022 snd-opti92x-ad1848=
2023 [HW,ALSA]
2025 snd-opti92x-cs4231=
2026 [HW,ALSA]
2028 snd-opti93x= [HW,ALSA]
2030 snd-pmac= [HW,ALSA]
2032 snd-rme32= [HW,ALSA]
2034 snd-rme96= [HW,ALSA]
2036 snd-rme9652= [HW,ALSA]
2038 snd-sb8= [HW,ALSA]
2040 snd-sb16= [HW,ALSA]
2042 snd-sbawe= [HW,ALSA]
2044 snd-serial= [HW,ALSA]
2046 snd-sgalaxy= [HW,ALSA]
2048 snd-sonicvibes= [HW,ALSA]
2050 snd-sun-amd7930=
2051 [HW,ALSA]
2053 snd-sun-cs4231= [HW,ALSA]
2055 snd-trident= [HW,ALSA]
2057 snd-usb-audio= [HW,ALSA,USB]
2059 snd-via82xx= [HW,ALSA]
2061 snd-virmidi= [HW,ALSA]
2063 snd-wavefront= [HW,ALSA]
2065 snd-ymfpci= [HW,ALSA]
2067 softlockup_panic=
2068 [KNL] Should the soft-lockup detector generate panics.
2070 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2071 See Documentation/sonypi.txt
2073 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2074 See Documentation/specialix.txt.
2076 spia_io_base= [HW,MTD]
2077 spia_fio_base=
2078 spia_pedr=
2079 spia_peddr=
2081 sscape= [HW,OSS]
2082 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2084 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2085 See Documentation/scsi/st.txt.
2087 sti= [PARISC,HW]
2088 Format: <num>
2089 Set the STI (builtin display/keyboard on the HP-PARISC
2090 machines) console (graphic card) which should be used
2091 as the initial boot-console.
2092 See also comment in drivers/video/console/sticore.c.
2094 sti_font= [HW]
2095 See comment in drivers/video/console/sticore.c.
2097 stifb= [HW]
2098 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2100 sunrpc.pool_mode=
2101 [NFS]
2102 Control how the NFS server code allocates CPUs to
2103 service thread pools. Depending on how many NICs
2104 you have and where their interrupts are bound, this
2105 option will affect which CPUs will do NFS serving.
2106 Note: this parameter cannot be changed while the
2107 NFS server is running.
2109 auto the server chooses an appropriate mode
2110 automatically using heuristics
2111 global a single global pool contains all CPUs
2112 percpu one pool for each CPU
2113 pernode one pool for each NUMA node (equivalent
2114 to global on non-NUMA machines)
2116 swiotlb= [IA-64] Number of I/O TLB slabs
2118 switches= [HW,M68k]
2120 sym53c416= [HW,SCSI]
2121 See header of drivers/scsi/sym53c416.c.
2123 sysrq_always_enabled
2124 [KNL]
2125 Ignore sysrq setting - this boot parameter will
2126 neutralize any effect of /proc/sys/kernel/sysrq.
2127 Useful for debugging.
2129 t128= [HW,SCSI]
2130 See header of drivers/scsi/t128.c.
2132 tdfx= [HW,DRM]
2134 test_suspend= [SUSPEND]
2135 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2136 standby suspend) as the system sleep state to briefly
2137 enter during system startup. The system is woken from
2138 this state using a wakeup-capable RTC alarm.
2140 thash_entries= [KNL,NET]
2141 Set number of hash buckets for TCP connection
2143 thermal.act= [HW,ACPI]
2144 -1: disable all active trip points in all thermal zones
2145 <degrees C>: override all lowest active trip points
2147 thermal.crt= [HW,ACPI]
2148 -1: disable all critical trip points in all thermal zones
2149 <degrees C>: lower all critical trip points
2151 thermal.nocrt= [HW,ACPI]
2152 Set to disable actions on ACPI thermal zone
2153 critical and hot trip points.
2155 thermal.off= [HW,ACPI]
2156 1: disable ACPI thermal control
2158 thermal.psv= [HW,ACPI]
2159 -1: disable all passive trip points
2160 <degrees C>: override all passive trip points to this value
2162 thermal.tzp= [HW,ACPI]
2163 Specify global default ACPI thermal zone polling rate
2164 <deci-seconds>: poll all this frequency
2165 0: no polling (default)
2167 tmscsim= [HW,SCSI]
2168 See comment before function dc390_setup() in
2169 drivers/scsi/tmscsim.c.
2171 tp720= [HW,PS2]
2173 trix= [HW,OSS] MediaTrix AudioTrix Pro
2174 Format:
2175 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2177 turbografx.map[2|3]= [HW,JOY]
2178 TurboGraFX parallel port interface
2179 Format:
2180 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2181 See also Documentation/input/joystick-parport.txt
2183 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2184 See header of drivers/scsi/u14-34f.c.
2186 uart401= [HW,OSS]
2187 Format: <io>,<irq>
2189 uart6850= [HW,OSS]
2190 Format: <io>,<irq>
2192 uhci-hcd.ignore_oc=
2193 [USB] Ignore overcurrent events (default N).
2194 Some badly-designed motherboards generate lots of
2195 bogus events, for ports that aren't wired to
2196 anything. Set this parameter to avoid log spamming.
2197 Note that genuine overcurrent events won't be
2198 reported either.
2200 unknown_nmi_panic
2201 [X86-32,X86-64]
2202 Set unknown_nmi_panic=1 early on boot.
2204 usbcore.autosuspend=
2205 [USB] The autosuspend time delay (in seconds) used
2206 for newly-detected USB devices (default 2). This
2207 is the time required before an idle device will be
2208 autosuspended. Devices for which the delay is set
2209 to a negative value won't be autosuspended at all.
2211 usbhid.mousepoll=
2212 [USBHID] The interval which mice are to be polled at.
2214 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2215 kernel's map of available physical RAM.
2217 vdso= [X86-32,SH,x86-64]
2218 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2219 vdso=1: enable VDSO (default)
2220 vdso=0: disable VDSO mapping
2222 vdso32= [X86-32,X86-64]
2223 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2224 vdso32=1: enable 32-bit VDSO (default)
2225 vdso32=0: disable 32-bit VDSO mapping
2227 vector= [IA-64,SMP]
2228 vector=percpu: enable percpu vector domain
2230 video= [FB] Frame buffer configuration
2231 See Documentation/fb/modedb.txt.
2233 vga= [BOOT,X86-32] Select a particular video mode
2234 See Documentation/i386/boot.txt and
2235 Documentation/svga.txt.
2236 Use vga=ask for menu.
2237 This is actually a boot loader parameter; the value is
2238 passed to the kernel using a special protocol.
2240 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2241 size of <nn>. This can be used to increase the
2242 minimum size (128MB on x86). It can also be used to
2243 decrease the size and leave more room for directly
2244 mapped kernel RAM.
2246 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2247 Format: <command>
2249 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2250 Format: <command>
2252 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2253 Format: <command>
2255 waveartist= [HW,OSS]
2256 Format: <io>,<irq>,<dma>,<dma2>
2258 wd33c93= [HW,SCSI]
2259 See header of drivers/scsi/wd33c93.c.
2261 wd7000= [HW,SCSI]
2262 See header of drivers/scsi/wd7000.c.
2264 wdt= [WDT] Watchdog
2265 See Documentation/watchdog/wdt.txt.
2267 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2268 xd_geo= See header of drivers/block/xd.c.
2270 xirc2ps_cs= [NET,PCMCIA]
2271 Format:
2272 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2274 norandmaps Don't use address space randomization
2275 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2277 ______________________________________________________________________
2279 TODO:
2281 Add documentation for ALSA options.
2282 Add more DRM drivers.