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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 KVM Kernel Virtual Machine support is enabled.
61 LIBATA Libata driver is enabled
62 LP Printer support is enabled.
63 LOOP Loopback device support is enabled.
64 M68k M68k architecture is enabled.
65 These options have more detailed description inside of
66 Documentation/m68k/kernel-options.txt.
67 MCA MCA bus support is enabled.
68 MDA MDA console support is enabled.
69 MOUSE Appropriate mouse support is enabled.
70 MSI Message Signaled Interrupts (PCI).
71 MTD MTD (Memory Technology Device) support is enabled.
72 NET Appropriate network support is enabled.
73 NUMA NUMA support is enabled.
74 GENERIC_TIME The generic timeofday code is enabled.
75 NFS Appropriate NFS support is enabled.
76 OSS OSS sound support is enabled.
77 PV_OPS A paravirtualized kernel is enabled.
78 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
79 PARISC The PA-RISC architecture is enabled.
80 PCI PCI bus support is enabled.
81 PCIE PCI Express support is enabled.
82 PCMCIA The PCMCIA subsystem is enabled.
83 PNP Plug & Play support is enabled.
84 PPC PowerPC architecture is enabled.
85 PPT Parallel port support is enabled.
86 PS2 Appropriate PS/2 support is enabled.
87 RAM RAM disk support 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_early_pdc_eval [HW,ACPI] Evaluate processor _PDC methods
203 early. Needed on some platforms to properly
204 initialize the EC.
206 acpi_irq_balance [HW,ACPI]
207 ACPI will balance active IRQs
208 default in APIC mode
210 acpi_irq_nobalance [HW,ACPI]
211 ACPI will not move active IRQs (default)
212 default in PIC mode
214 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
215 Format: <irq>,<irq>...
217 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
218 use by PCI
219 Format: <irq>,<irq>...
221 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
223 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
224 Format: To spoof as Windows 98: ="Microsoft Windows"
226 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
227 acpi_osi="string1" # add string1 -- only one string
228 acpi_osi="!string2" # remove built-in string2
229 acpi_osi= # disable all strings
231 acpi_pm_good [X86]
232 Override the pmtimer bug detection: force the kernel
233 to assume that this machine's pmtimer latches its value
234 and always returns good values.
236 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
237 Format: { level | edge | high | low }
239 acpi_serialize [HW,ACPI] force serialization of AML methods
241 acpi_skip_timer_override [HW,ACPI]
242 Recognize and ignore IRQ0/pin2 Interrupt Override.
243 For broken nForce2 BIOS resulting in XT-PIC timer.
245 acpi_sleep= [HW,ACPI] Sleep options
246 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
247 old_ordering, s4_nonvs, sci_force_enable }
248 See Documentation/power/video.txt for information on
249 s3_bios and s3_mode.
250 s3_beep is for debugging; it makes the PC's speaker beep
251 as soon as the kernel's real-mode entry point is called.
252 s4_nohwsig prevents ACPI hardware signature from being
253 used during resume from hibernation.
254 old_ordering causes the ACPI 1.0 ordering of the _PTS
255 control method, with respect to putting devices into
256 low power states, to be enforced (the ACPI 2.0 ordering
257 of _PTS is used by default).
258 s4_nonvs prevents the kernel from saving/restoring the
259 ACPI NVS memory during hibernation.
260 sci_force_enable causes the kernel to set SCI_EN directly
261 on resume from S1/S3 (which is against the ACPI spec,
262 but some broken systems don't work without it).
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
284 ad1848= [HW,OSS]
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
290 advansys= [HW,SCSI]
291 See header of drivers/scsi/advansys.c.
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
300 agp= [AGP]
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
306 aha152x= [HW,SCSI]
307 See Documentation/scsi/aha152x.txt.
309 aha1542= [HW,SCSI]
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
312 aic7xxx= [HW,SCSI]
313 See Documentation/scsi/aic7xxx.txt.
315 aic79xx= [HW,SCSI]
316 See Documentation/scsi/aic79xx.txt.
318 alignment= [KNL,ARM]
319 Allow the default userspace alignment fault handler
320 behaviour to be specified. Bit 0 enables warnings,
321 bit 1 enables fixups, and bit 2 sends a segfault.
323 amd_iommu= [HW,X86-84]
324 Pass parameters to the AMD IOMMU driver in the system.
325 Possible values are:
326 isolate - enable device isolation (each device, as far
327 as possible, will get its own protection
328 domain) [default]
329 share - put every device behind one IOMMU into the
330 same protection domain
331 fullflush - enable flushing of IO/TLB entries when
332 they are unmapped. Otherwise they are
333 flushed before they will be reused, which
334 is a lot of faster
336 amijoy.map= [HW,JOY] Amiga joystick support
337 Map of devices attached to JOY0DAT and JOY1DAT
338 Format: <a>,<b>
339 See also Documentation/kernel/input/joystick.txt
341 analog.map= [HW,JOY] Analog joystick and gamepad support
342 Specifies type or capabilities of an analog joystick
343 connected to one of 16 gameports
344 Format: <type1>,<type2>,..<type16>
346 apc= [HW,SPARC]
347 Power management functions (SPARCstation-4/5 + deriv.)
348 Format: noidle
349 Disable APC CPU standby support. SPARCstation-Fox does
350 not play well with APC CPU idle - disable it if you have
351 APC and your system crashes randomly.
353 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
354 Change the output verbosity whilst booting
355 Format: { quiet (default) | verbose | debug }
356 Change the amount of debugging information output
357 when initialising the APIC and IO-APIC components.
359 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
360 Limit apic dumping. The parameter defines the maximal
361 number of local apics being dumped. Also it is possible
362 to set it to "all" by meaning -- no limit here.
363 Format: { 1 (default) | 2 | ... | all }.
364 The parameter valid if only apic=debug or
365 apic=verbose is specified.
366 Example: apic=debug show_lapic=all
368 apm= [APM] Advanced Power Management
369 See header of arch/x86/kernel/apm_32.c.
371 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
372 Format: <io>,<irq>,<nodeID>
374 ataflop= [HW,M68k]
376 atarimouse= [HW,MOUSE] Atari Mouse
378 atascsi= [HW,SCSI] Atari SCSI
380 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
381 EzKey and similar keyboards
383 atkbd.reset= [HW] Reset keyboard during initialization
385 atkbd.set= [HW] Select keyboard code set
386 Format: <int> (2 = AT (default), 3 = PS/2)
388 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
389 keyboards
391 atkbd.softraw= [HW] Choose between synthetic and real raw mode
392 Format: <bool> (0 = real, 1 = synthetic (default))
394 atkbd.softrepeat= [HW]
395 Use software keyboard repeat
397 autotest [IA64]
399 baycom_epp= [HW,AX25]
400 Format: <io>,<mode>
402 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
403 Format: <io>,<mode>
404 See header of drivers/net/hamradio/baycom_par.c.
406 baycom_ser_fdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
408 Format: <io>,<irq>,<mode>[,<baud>]
409 See header of drivers/net/hamradio/baycom_ser_fdx.c.
411 baycom_ser_hdx= [HW,AX25]
412 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
413 Format: <io>,<irq>,<mode>
414 See header of drivers/net/hamradio/baycom_ser_hdx.c.
416 boot_delay= Milliseconds to delay each printk during boot.
417 Values larger than 10 seconds (10000) are changed to
418 no delay (0).
419 Format: integer
421 bootmem_debug [KNL] Enable bootmem allocator debug messages.
423 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
424 bttv.radio= Most important insmod options are available as
425 kernel args too.
426 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
427 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
429 BusLogic= [HW,SCSI]
430 See drivers/scsi/BusLogic.c, comment before function
431 BusLogic_ParseDriverOptions().
433 c101= [NET] Moxa C101 synchronous serial card
435 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
436 Sometimes CPU hardware bugs make them report the cache
437 size incorrectly. The kernel will attempt work arounds
438 to fix known problems, but for some CPUs it is not
439 possible to determine what the correct size should be.
440 This option provides an override for these situations.
442 capability.disable=
443 [SECURITY] Disable capabilities. This would normally
444 be used only if an alternative security model is to be
445 configured. Potentially dangerous and should only be
446 used if you are entirely sure of the consequences.
448 ccw_timeout_log [S390]
449 See Documentation/s390/CommonIO for details.
451 cgroup_disable= [KNL] Disable a particular controller
452 Format: {name of the controller(s) to disable}
453 {Currently supported controllers - "memory"}
455 checkreqprot [SELINUX] Set initial checkreqprot flag value.
456 Format: { "0" | "1" }
457 See security/selinux/Kconfig help text.
458 0 -- check protection applied by kernel (includes
459 any implied execute protection).
460 1 -- check protection requested by application.
461 Default value is set via a kernel config option.
462 Value can be changed at runtime via
463 /selinux/checkreqprot.
465 cio_ignore= [S390]
466 See Documentation/s390/CommonIO for details.
468 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
469 [Deprecated]
470 Forces specified clocksource (if available) to be used
471 when calculating gettimeofday(). If specified
472 clocksource is not available, it defaults to PIT.
473 Format: { pit | tsc | cyclone | pmtmr }
475 clocksource= [GENERIC_TIME] Override the default clocksource
476 Format: <string>
477 Override the default clocksource and use the clocksource
478 with the name specified.
479 Some clocksource names to choose from, depending on
480 the platform:
481 [all] jiffies (this is the base, fallback clocksource)
482 [ACPI] acpi_pm
483 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
484 pxa_timer,timer3,32k_counter,timer0_1
485 [AVR32] avr32
486 [X86-32] pit,hpet,tsc,vmi-timer;
487 scx200_hrt on Geode; cyclone on IBM x440
488 [MIPS] MIPS
489 [PARISC] cr16
490 [S390] tod
491 [SH] SuperH
492 [SPARC64] tick
493 [X86-64] hpet,tsc
495 clearcpuid=BITNUM [X86]
496 Disable CPUID feature X for the kernel. See
497 arch/x86/include/asm/cpufeature.h for the valid bit
498 numbers. Note the Linux specific bits are not necessarily
499 stable over kernel options, but the vendor specific
500 ones should be.
501 Also note that user programs calling CPUID directly
502 or using the feature without checking anything
503 will still see it. This just prevents it from
504 being used by the kernel or shown in /proc/cpuinfo.
505 Also note the kernel might malfunction if you disable
506 some critical bits.
508 cmo_free_hint= [PPC] Format: { yes | no }
509 Specify whether pages are marked as being inactive
510 when they are freed. This is used in CMO environments
511 to determine OS memory pressure for page stealing by
512 a hypervisor.
513 Default: yes
515 code_bytes [X86] How many bytes of object code to print
516 in an oops report.
517 Range: 0 - 8192
518 Default: 64
520 com20020= [HW,NET] ARCnet - COM20020 chipset
521 Format:
522 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
524 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
525 Format: <io>[,<irq>]
527 com90xx= [HW,NET]
528 ARCnet - COM90xx chipset (memory-mapped buffers)
529 Format: <io>[,<irq>[,<memstart>]]
531 condev= [HW,S390] console device
532 conmode=
534 console= [KNL] Output console device and options.
536 tty<n> Use the virtual console device <n>.
538 ttyS<n>[,options]
539 ttyUSB0[,options]
540 Use the specified serial port. The options are of
541 the form "bbbbpnf", where "bbbb" is the baud rate,
542 "p" is parity ("n", "o", or "e"), "n" is number of
543 bits, and "f" is flow control ("r" for RTS or
544 omit it). Default is "9600n8".
546 See Documentation/serial-console.txt for more
547 information. See
548 Documentation/networking/netconsole.txt for an
549 alternative.
551 uart[8250],io,<addr>[,options]
552 uart[8250],mmio,<addr>[,options]
553 Start an early, polled-mode console on the 8250/16550
554 UART at the specified I/O port or MMIO address,
555 switching to the matching ttyS device later. The
556 options are the same as for ttyS, above.
558 If the device connected to the port is not a TTY but a braille
559 device, prepend "brl," before the device type, for instance
560 console=brl,ttyS0
561 For now, only VisioBraille is supported.
563 consoleblank= [KNL] The console blank (screen saver) timeout in
564 seconds. Defaults to 10*60 = 10mins. A value of 0
565 disables the blank timer.
567 coredump_filter=
568 [KNL] Change the default value for
569 /proc/<pid>/coredump_filter.
570 See also Documentation/filesystems/proc.txt.
572 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
573 Format:
574 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
576 crashkernel=nn[KMG]@ss[KMG]
577 [KNL] Reserve a chunk of physical memory to
578 hold a kernel to switch to with kexec on panic.
580 crashkernel=range1:size1[,range2:size2,...][@offset]
581 [KNL] Same as above, but depends on the memory
582 in the running system. The syntax of range is
583 start-[end] where start and end are both
584 a memory unit (amount[KMG]). See also
585 Documentation/kdump/kdump.txt for a example.
587 cs89x0_dma= [HW,NET]
588 Format: <dma>
590 cs89x0_media= [HW,NET]
591 Format: { rj45 | aui | bnc }
593 dasd= [HW,NET]
594 See header of drivers/s390/block/dasd_devmap.c.
596 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
597 (one device per port)
598 Format: <port#>,<type>
599 See also Documentation/input/joystick-parport.txt
601 debug [KNL] Enable kernel debugging (events log level).
603 debug_locks_verbose=
604 [KNL] verbose self-tests
605 Format=<0|1>
606 Print debugging info while doing the locking API
607 self-tests.
608 We default to 0 (no extra messages), setting it to
609 1 will print _a lot_ more information - normally
610 only useful to kernel developers.
612 debug_objects [KNL] Enable object debugging
614 no_debug_objects
615 [KNL] Disable object debugging
617 debugpat [X86] Enable PAT debugging
619 decnet.addr= [HW,NET]
620 Format: <area>[,<node>]
621 See also Documentation/networking/decnet.txt.
623 default_hugepagesz=
624 [same as hugepagesz=] The size of the default
625 HugeTLB page size. This is the size represented by
626 the legacy /proc/ hugepages APIs, used for SHM, and
627 default size when mounting hugetlbfs filesystems.
628 Defaults to the default architecture's huge page size
629 if not specified.
631 dhash_entries= [KNL]
632 Set number of hash buckets for dentry cache.
634 digi= [HW,SERIAL]
635 IO parameters + enable/disable command.
637 digiepca= [HW,SERIAL]
638 See drivers/char/README.epca and
639 Documentation/serial/digiepca.txt.
641 disable_mtrr_cleanup [X86]
642 The kernel tries to adjust MTRR layout from continuous
643 to discrete, to make X server driver able to add WB
644 entry later. This parameter disables that.
646 disable_mtrr_trim [X86, Intel and AMD only]
647 By default the kernel will trim any uncacheable
648 memory out of your available memory pool based on
649 MTRR settings. This parameter disables that behavior,
650 possibly causing your machine to run very slowly.
652 disable_timer_pin_1 [X86]
653 Disable PIN 1 of APIC timer
654 Can be useful to work around chipset bugs.
656 dmasound= [HW,OSS] Sound subsystem buffers
658 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
659 this option disables the debugging code at boot.
661 dma_debug_entries=<number>
662 This option allows to tune the number of preallocated
663 entries for DMA-API debugging code. One entry is
664 required per DMA-API allocation. Use this if the
665 DMA-API debugging code disables itself because the
666 architectural default is too low.
668 dma_debug_driver=<driver_name>
669 With this option the DMA-API debugging driver
670 filter feature can be enabled at boot time. Just
671 pass the driver to filter for as the parameter.
672 The filter can be disabled or changed to another
673 driver later using sysfs.
675 dscc4.setup= [NET]
677 dtc3181e= [HW,SCSI]
679 dynamic_printk Enables pr_debug()/dev_dbg() calls if
680 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
681 These can also be switched on/off via
682 <debugfs>/dynamic_printk/modules
684 earlycon= [KNL] Output early console device and options.
685 uart[8250],io,<addr>[,options]
686 uart[8250],mmio,<addr>[,options]
687 Start an early, polled-mode console on the 8250/16550
688 UART at the specified I/O port or MMIO address.
689 The options are the same as for ttyS, above.
691 earlyprintk= [X86,SH,BLACKFIN]
692 earlyprintk=vga
693 earlyprintk=serial[,ttySn[,baudrate]]
694 earlyprintk=ttySn[,baudrate]
695 earlyprintk=dbgp[debugController#]
697 Append ",keep" to not disable it when the real console
698 takes over.
700 Only vga or serial or usb debug port at a time.
702 Currently only ttyS0 and ttyS1 are supported.
704 Interaction with the standard serial driver is not
705 very good.
707 The VGA output is eventually overwritten by the real
708 console.
710 eata= [HW,SCSI]
712 edd= [EDD]
713 Format: {"off" | "on" | "skip[mbr]"}
715 eisa_irq_edge= [PARISC,HW]
716 See header of drivers/parisc/eisa.c.
718 elanfreq= [X86-32]
719 See comment before function elanfreq_setup() in
720 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
722 elevator= [IOSCHED]
723 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
724 See Documentation/block/as-iosched.txt and
725 Documentation/block/deadline-iosched.txt for details.
727 elfcorehdr= [IA64,PPC,SH,X86]
728 Specifies physical address of start of kernel core
729 image elf header. Generally kexec loader will
730 pass this option to capture kernel.
731 See Documentation/kdump/kdump.txt for details.
733 enable_mtrr_cleanup [X86]
734 The kernel tries to adjust MTRR layout from continuous
735 to discrete, to make X server driver able to add WB
736 entry later. This parameter enables that.
738 enable_timer_pin_1 [X86]
739 Enable PIN 1 of APIC timer
740 Can be useful to work around chipset bugs
741 (in particular on some ATI chipsets).
742 The kernel tries to set a reasonable default.
744 enforcing [SELINUX] Set initial enforcing status.
745 Format: {"0" | "1"}
746 See security/selinux/Kconfig help text.
747 0 -- permissive (log only, no denials).
748 1 -- enforcing (deny and log).
749 Default value is 0.
750 Value can be changed at runtime via /selinux/enforce.
752 ether= [HW,NET] Ethernet cards parameters
753 This option is obsoleted by the "netdev=" option, which
754 has equivalent usage. See its documentation for details.
756 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
757 Format: <io>[,<irq>]
759 failslab=
760 fail_page_alloc=
761 fail_make_request=[KNL]
762 General fault injection mechanism.
763 Format: <interval>,<probability>,<space>,<times>
764 See also /Documentation/fault-injection/.
766 fd_mcs= [HW,SCSI]
767 See header of drivers/scsi/fd_mcs.c.
769 fdomain= [HW,SCSI]
770 See header of drivers/scsi/fdomain.c.
772 floppy= [HW]
773 See Documentation/blockdev/floppy.txt.
775 force_pal_cache_flush
776 [IA-64] Avoid check_sal_cache_flush which may hang on
777 buggy SAL_CACHE_FLUSH implementations. Using this
778 parameter will force ia64_sal_cache_flush to call
779 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
781 ftrace=[tracer]
782 [FTRACE] will set and start the specified tracer
783 as early as possible in order to facilitate early
784 boot debugging.
786 ftrace_dump_on_oops
787 [FTRACE] will dump the trace buffers on oops.
789 ftrace_filter=[function-list]
790 [FTRACE] Limit the functions traced by the function
791 tracer at boot up. function-list is a comma separated
792 list of functions. This list can be changed at run
793 time by the set_ftrace_filter file in the debugfs
794 tracing directory.
796 ftrace_notrace=[function-list]
797 [FTRACE] Do not trace the functions specified in
798 function-list. This list can be changed at run time
799 by the set_ftrace_notrace file in the debugfs
800 tracing directory.
802 ftrace_graph_filter=[function-list]
803 [FTRACE] Limit the top level callers functions traced
804 by the function graph tracer at boot up.
805 function-list is a comma separated list of functions
806 that can be changed at run time by the
807 set_graph_function file in the debugfs tracing directory.
809 gamecon.map[2|3]=
810 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
811 support via parallel port (up to 5 devices per port)
812 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
813 See also Documentation/input/joystick-parport.txt
815 gamma= [HW,DRM]
817 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
818 Format: off | on
819 default: on
821 gcov_persist= [GCOV] When non-zero (default), profiling data for
822 kernel modules is saved and remains accessible via
823 debugfs, even when the module is unloaded/reloaded.
824 When zero, profiling data is discarded and associated
825 debugfs files are removed at module unload time.
827 gdth= [HW,SCSI]
828 See header of drivers/scsi/gdth.c.
830 gpt [EFI] Forces disk with valid GPT signature but
831 invalid Protective MBR to be treated as GPT.
833 gvp11= [HW,SCSI]
835 hashdist= [KNL,NUMA] Large hashes allocated during boot
836 are distributed across NUMA nodes. Defaults on
837 for 64bit NUMA, off otherwise.
838 Format: 0 | 1 (for off | on)
840 hcl= [IA-64] SGI's Hardware Graph compatibility layer
842 hd= [EIDE] (E)IDE hard drive subsystem geometry
843 Format: <cyl>,<head>,<sect>
845 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
846 size of <nn>. This works even on boxes that have no
847 highmem otherwise. This also works to reduce highmem
848 size on bigger boxes.
850 highres= [KNL] Enable/disable high resolution timer mode.
851 Valid parameters: "on", "off"
852 Default: "on"
854 hisax= [HW,ISDN]
855 See Documentation/isdn/README.HiSax.
857 hlt [BUGS=ARM,SH]
859 hpet= [X86-32,HPET] option to control HPET usage
860 Format: { enable (default) | disable | force |
861 verbose }
862 disable: disable HPET and use PIT instead
863 force: allow force enabled of undocumented chips (ICH4,
864 VIA, nVidia)
865 verbose: show contents of HPET registers during setup
867 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
868 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
869 On x86-64 and powerpc, this option can be specified
870 multiple times interleaved with hugepages= to reserve
871 huge pages of different sizes. Valid pages sizes on
872 x86-64 are 2M (when the CPU supports "pse") and 1G
873 (when the CPU supports the "pdpe1gb" cpuinfo flag)
874 Note that 1GB pages can only be allocated at boot time
875 using hugepages= and not freed afterwards.
877 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
878 terminal devices. Valid values: 0..8
879 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
880 If specified, z/VM IUCV HVC accepts connections
881 from listed z/VM user IDs only.
883 i2c_bus= [HW] Override the default board specific I2C bus speed
884 or register an additional I2C bus that is not
885 registered from board initialization code.
886 Format:
887 <bus_id>,<clkrate>
889 i8042.debug [HW] Toggle i8042 debug mode
890 i8042.direct [HW] Put keyboard port into non-translated mode
891 i8042.dumbkbd [HW] Pretend that controller can only read data from
892 keyboard and cannot control its state
893 (Don't attempt to blink the leds)
894 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
895 i8042.nokbd [HW] Don't check/create keyboard port
896 i8042.noloop [HW] Disable the AUX Loopback command while probing
897 for the AUX port
898 i8042.nomux [HW] Don't check presence of an active multiplexing
899 controller
900 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
901 controllers
902 i8042.panicblink=
903 [HW] Frequency with which keyboard LEDs should blink
904 when kernel panics (default is 0.5 sec)
905 i8042.reset [HW] Reset the controller during init and cleanup
906 i8042.unlock [HW] Unlock (ignore) the keylock
908 i810= [HW,DRM]
910 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
911 indicates that the driver is running on unsupported
912 hardware.
913 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
914 does not match list of supported models.
915 i8k.power_status
916 [HW] Report power status in /proc/i8k
917 (disabled by default)
918 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
919 capability is set.
921 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
922 See Documentation/mca.txt.
924 icn= [HW,ISDN]
925 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
927 ide-core.nodma= [HW] (E)IDE subsystem
928 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
929 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
930 .cdrom .chs .ignore_cable are additional options
931 See Documentation/ide/ide.txt.
933 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
934 Claim all unknown PCI IDE storage controllers.
936 idle= [X86]
937 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
938 Poll forces a polling idle loop that can slightly
939 improve the performance of waking up a idle CPU, but
940 will use a lot of power and make the system run hot.
941 Not recommended.
942 idle=mwait: On systems which support MONITOR/MWAIT but
943 the kernel chose to not use it because it doesn't save
944 as much power as a normal idle loop, use the
945 MONITOR/MWAIT idle loop anyways. Performance should be
946 the same as idle=poll.
947 idle=halt: Halt is forced to be used for CPU idle.
948 In such case C2/C3 won't be used again.
949 idle=nomwait: Disable mwait for CPU C-states
951 ignore_loglevel [KNL]
952 Ignore loglevel setting - this will print /all/
953 kernel messages to the console. Useful for debugging.
955 ihash_entries= [KNL]
956 Set number of hash buckets for inode cache.
958 ima_audit= [IMA]
959 Format: { "0" | "1" }
960 0 -- integrity auditing messages. (Default)
961 1 -- enable informational integrity auditing messages.
963 ima_hash= [IMA]
964 Format: { "sha1" | "md5" }
965 default: "sha1"
967 ima_tcb [IMA]
968 Load a policy which meets the needs of the Trusted
969 Computing Base. This means IMA will measure all
970 programs exec'd, files mmap'd for exec, and all files
971 opened for read by uid=0.
973 in2000= [HW,SCSI]
974 See header of drivers/scsi/in2000.c.
976 init= [KNL]
977 Format: <full_path>
978 Run specified binary instead of /sbin/init as init
979 process.
981 initcall_debug [KNL] Trace initcalls as they are executed. Useful
982 for working out where the kernel is dying during
983 startup.
985 initrd= [BOOT] Specify the location of the initial ramdisk
987 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
988 Format: <irq>
990 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
991 on
992 Enable intel iommu driver.
993 off
994 Disable intel iommu driver.
995 igfx_off [Default Off]
996 By default, gfx is mapped as normal device. If a gfx
997 device has a dedicated DMAR unit, the DMAR unit is
998 bypassed by not enabling DMAR with this option. In
999 this case, gfx device will use physical address for
1000 DMA.
1001 forcedac [x86_64]
1002 With this option iommu will not optimize to look
1003 for io virtual address below 32 bit forcing dual
1004 address cycle on pci bus for cards supporting greater
1005 than 32 bit addressing. The default is to look
1006 for translation below 32 bit and if not available
1007 then look in the higher range.
1008 strict [Default Off]
1009 With this option on every unmap_single operation will
1010 result in a hardware IOTLB flush operation as opposed
1011 to batching them for performance.
1013 inttest= [IA64]
1015 iomem= Disable strict checking of access to MMIO memory
1016 strict regions from userspace.
1017 relaxed
1019 iommu= [x86]
1020 off
1021 force
1022 noforce
1023 biomerge
1024 panic
1025 nopanic
1026 merge
1027 nomerge
1028 forcesac
1029 soft
1030 pt [x86, IA64]
1032 io7= [HW] IO7 for Marvel based alpha systems
1033 See comment before marvel_specify_io7 in
1034 arch/alpha/kernel/core_marvel.c.
1036 io_delay= [X86] I/O delay method
1037 0x80
1038 Standard port 0x80 based delay
1039 0xed
1040 Alternate port 0xed based delay (needed on some systems)
1041 udelay
1042 Simple two microseconds delay
1043 none
1044 No delay
1046 ip= [IP_PNP]
1047 See Documentation/filesystems/nfs/nfsroot.txt.
1049 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1050 See comment before ip2_setup() in
1051 drivers/char/ip2/ip2base.c.
1053 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1054 See header of drivers/scsi/ips.c.
1056 irqfixup [HW]
1057 When an interrupt is not handled search all handlers
1058 for it. Intended to get systems with badly broken
1059 firmware running.
1061 irqpoll [HW]
1062 When an interrupt is not handled search all handlers
1063 for it. Also check all handlers each timer
1064 interrupt. Intended to get systems with badly broken
1065 firmware running.
1067 isapnp= [ISAPNP]
1068 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1070 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1071 Format:
1072 <cpu number>,...,<cpu number>
1073 or
1074 <cpu number>-<cpu number>
1075 (must be a positive range in ascending order)
1076 or a mixture
1077 <cpu number>,...,<cpu number>-<cpu number>
1079 This option can be used to specify one or more CPUs
1080 to isolate from the general SMP balancing and scheduling
1081 algorithms. You can move a process onto or off an
1082 "isolated" CPU via the CPU affinity syscalls or cpuset.
1083 <cpu number> begins at 0 and the maximum value is
1084 "number of CPUs in system - 1".
1086 This option is the preferred way to isolate CPUs. The
1087 alternative -- manually setting the CPU mask of all
1088 tasks in the system -- can cause problems and
1089 suboptimal load balancer performance.
1091 iucv= [HW,NET]
1093 js= [HW,JOY] Analog joystick
1094 See Documentation/input/joystick.txt.
1096 keepinitrd [HW,ARM]
1098 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1099 specifies the amount of memory usable by the kernel
1100 for non-movable allocations. The requested amount is
1101 spread evenly throughout all nodes in the system. The
1102 remaining memory in each node is used for Movable
1103 pages. In the event, a node is too small to have both
1104 kernelcore and Movable pages, kernelcore pages will
1105 take priority and other nodes will have a larger number
1106 of kernelcore pages. The Movable zone is used for the
1107 allocation of pages that may be reclaimed or moved
1108 by the page migration subsystem. This means that
1109 HugeTLB pages may not be allocated from this zone.
1110 Note that allocations like PTEs-from-HighMem still
1111 use the HighMem zone if it exists, and the Normal
1112 zone if it does not.
1114 kgdboc= [HW] kgdb over consoles.
1115 Requires a tty driver that supports console polling.
1116 (only serial supported for now)
1117 Format: <serial_device>[,baud]
1119 kmac= [MIPS] korina ethernet MAC address.
1120 Configure the RouterBoard 532 series on-chip
1121 Ethernet adapter MAC address.
1123 kmemleak= [KNL] Boot-time kmemleak enable/disable
1124 Valid arguments: on, off
1125 Default: on
1127 kstack=N [X86] Print N words from the kernel stack
1128 in oops dumps.
1130 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1131 Default is 0 (don't ignore, but inject #GP)
1133 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1134 Default is 1 (enabled)
1136 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1137 Default is 0 (off)
1139 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1140 for all guests.
1141 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1143 kvm-intel.bypass_guest_pf=
1144 [KVM,Intel] Disables bypassing of guest page faults
1145 on Intel chips. Default is 1 (enabled)
1147 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1148 (virtualized MMU) support on capable Intel chips.
1149 Default is 1 (enabled)
1151 kvm-intel.emulate_invalid_guest_state=
1152 [KVM,Intel] Enable emulation of invalid guest states
1153 Default is 0 (disabled)
1155 kvm-intel.flexpriority=
1156 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1157 Default is 1 (enabled)
1159 kvm-intel.unrestricted_guest=
1160 [KVM,Intel] Disable unrestricted guest feature
1161 (virtualized real and unpaged mode) on capable
1162 Intel chips. Default is 1 (enabled)
1164 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1165 feature (tagged TLBs) on capable Intel chips.
1166 Default is 1 (enabled)
1168 l2cr= [PPC]
1170 l3cr= [PPC]
1172 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1173 disabled it.
1175 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1176 in C2 power state.
1178 libata.dma= [LIBATA] DMA control
1179 libata.dma=0 Disable all PATA and SATA DMA
1180 libata.dma=1 PATA and SATA Disk DMA only
1181 libata.dma=2 ATAPI (CDROM) DMA only
1182 libata.dma=4 Compact Flash DMA only
1183 Combinations also work, so libata.dma=3 enables DMA
1184 for disks and CDROMs, but not CFs.
1186 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1187 libata.ignore_hpa=0 keep BIOS limits (default)
1188 libata.ignore_hpa=1 ignore limits, using full disk
1190 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1191 when set.
1192 Format: <int>
1194 libata.force= [LIBATA] Force configurations. The format is comma
1195 separated list of "[ID:]VAL" where ID is
1196 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1197 matching port, link or device. Basically, it matches
1198 the ATA ID string printed on console by libata. If
1199 the whole ID part is omitted, the last PORT and DEVICE
1200 values are used. If ID hasn't been specified yet, the
1201 configuration applies to all ports, links and devices.
1203 If only DEVICE is omitted, the parameter applies to
1204 the port and all links and devices behind it. DEVICE
1205 number of 0 either selects the first device or the
1206 first fan-out link behind PMP device. It does not
1207 select the host link. DEVICE number of 15 selects the
1208 host link and device attached to it.
1210 The VAL specifies the configuration to force. As long
1211 as there's no ambiguity shortcut notation is allowed.
1212 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1213 The following configurations can be forced.
1215 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1216 Any ID with matching PORT is used.
1218 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1220 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1221 udma[/][16,25,33,44,66,100,133] notation is also
1222 allowed.
1224 * [no]ncq: Turn on or off NCQ.
1226 * nohrst, nosrst, norst: suppress hard, soft
1227 and both resets.
1229 If there are multiple matching configurations changing
1230 the same attribute, the last one is used.
1232 lmb=debug [KNL] Enable lmb debug messages.
1234 load_ramdisk= [RAM] List of ramdisks to load from floppy
1235 See Documentation/blockdev/ramdisk.txt.
1237 lockd.nlm_grace_period=P [NFS] Assign grace period.
1238 Format: <integer>
1240 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1241 Format: <integer>
1243 lockd.nlm_timeout=T [NFS] Assign timeout value.
1244 Format: <integer>
1246 lockd.nlm_udpport=M [NFS] Assign UDP port.
1247 Format: <integer>
1249 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1250 Format: <irq>
1252 loglevel= All Kernel Messages with a loglevel smaller than the
1253 console loglevel will be printed to the console. It can
1254 also be changed with klogd or other programs. The
1255 loglevels are defined as follows:
1257 0 (KERN_EMERG) system is unusable
1258 1 (KERN_ALERT) action must be taken immediately
1259 2 (KERN_CRIT) critical conditions
1260 3 (KERN_ERR) error conditions
1261 4 (KERN_WARNING) warning conditions
1262 5 (KERN_NOTICE) normal but significant condition
1263 6 (KERN_INFO) informational
1264 7 (KERN_DEBUG) debug-level messages
1266 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1267 Format: { n | nk | nM }
1268 n must be a power of two. The default size
1269 is set in the kernel config file.
1271 logo.nologo [FB] Disables display of the built-in Linux logo.
1272 This may be used to provide more screen space for
1273 kernel log messages and is useful when debugging
1274 kernel boot problems.
1276 lp=0 [LP] Specify parallel ports to use, e.g,
1277 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1278 lp=reset first parallel port). 'lp=0' disables the
1279 lp=auto printer driver. 'lp=reset' (which can be
1280 specified in addition to the ports) causes
1281 attached printers to be reset. Using
1282 lp=port1,port2,... specifies the parallel ports
1283 to associate lp devices with, starting with
1284 lp0. A port specification may be 'none' to skip
1285 that lp device, or a parport name such as
1286 'parport0'. Specifying 'lp=auto' instead of a
1287 port specification list means that device IDs
1288 from each port should be examined, to see if
1289 an IEEE 1284-compliant printer is attached; if
1290 so, the driver will manage that printer.
1291 See also header of drivers/char/lp.c.
1293 lpj=n [KNL]
1294 Sets loops_per_jiffy to given constant, thus avoiding
1295 time-consuming boot-time autodetection (up to 250 ms per
1296 CPU). 0 enables autodetection (default). To determine
1297 the correct value for your kernel, boot with normal
1298 autodetection and see what value is printed. Note that
1299 on SMP systems the preset will be applied to all CPUs,
1300 which is likely to cause problems if your CPUs need
1301 significantly divergent settings. An incorrect value
1302 will cause delays in the kernel to be wrong, leading to
1303 unpredictable I/O errors and other breakage. Although
1304 unlikely, in the extreme case this might damage your
1305 hardware.
1307 ltpc= [NET]
1308 Format: <io>,<irq>,<dma>
1310 mac5380= [HW,SCSI] Format:
1311 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1313 machvec= [IA64] Force the use of a particular machine-vector
1314 (machvec) in a generic kernel.
1315 Example: machvec=hpzx1_swiotlb
1317 machtype= [Loongson] Share the same kernel image file between different
1318 yeeloong laptop.
1319 Example: machtype=lemote-yeeloong-2f-7inch
1321 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1322 than or equal to this physical address is ignored.
1324 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1325 should make use of. maxcpus=n : n >= 0 limits the
1326 kernel to using 'n' processors. n=0 is a special case,
1327 it is equivalent to "nosmp", which also disables
1328 the IO APIC.
1330 max_loop= [LOOP] Maximum number of loopback devices that can
1331 be mounted
1332 Format: <1-256>
1334 max_luns= [SCSI] Maximum number of LUNs to probe.
1335 Should be between 1 and 2^32-1.
1337 max_report_luns=
1338 [SCSI] Maximum number of LUNs received.
1339 Should be between 1 and 16384.
1341 mcatest= [IA-64]
1343 mce [X86-32] Machine Check Exception
1345 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1347 md= [HW] RAID subsystems devices and level
1348 See Documentation/md.txt.
1350 mdacon= [MDA]
1351 Format: <first>,<last>
1352 Specifies range of consoles to be captured by the MDA.
1354 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1355 Amount of memory to be used when the kernel is not able
1356 to see the whole system memory or for test.
1357 [X86-32] Use together with memmap= to avoid physical
1358 address space collisions. Without memmap= PCI devices
1359 could be placed at addresses belonging to unused RAM.
1361 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1362 memory.
1364 memchunk=nn[KMG]
1365 [KNL,SH] Allow user to override the default size for
1366 per-device physically contiguous DMA buffers.
1368 memmap=exactmap [KNL,X86] Enable setting of an exact
1369 E820 memory map, as specified by the user.
1370 Such memmap=exactmap lines can be constructed based on
1371 BIOS output or other requirements. See the memmap=nn@ss
1372 option description.
1374 memmap=nn[KMG]@ss[KMG]
1375 [KNL] Force usage of a specific region of memory
1376 Region of memory to be used, from ss to ss+nn.
1378 memmap=nn[KMG]#ss[KMG]
1379 [KNL,ACPI] Mark specific memory as ACPI data.
1380 Region of memory to be used, from ss to ss+nn.
1382 memmap=nn[KMG]$ss[KMG]
1383 [KNL,ACPI] Mark specific memory as reserved.
1384 Region of memory to be used, from ss to ss+nn.
1385 Example: Exclude memory from 0x18690000-0x1869ffff
1386 memmap=64K$0x18690000
1387 or
1388 memmap=0x10000$0x18690000
1390 memory_corruption_check=0/1 [X86]
1391 Some BIOSes seem to corrupt the first 64k of
1392 memory when doing things like suspend/resume.
1393 Setting this option will scan the memory
1394 looking for corruption. Enabling this will
1395 both detect corruption and prevent the kernel
1396 from using the memory being corrupted.
1397 However, its intended as a diagnostic tool; if
1398 repeatable BIOS-originated corruption always
1399 affects the same memory, you can use memmap=
1400 to prevent the kernel from using that memory.
1402 memory_corruption_check_size=size [X86]
1403 By default it checks for corruption in the low
1404 64k, making this memory unavailable for normal
1405 use. Use this parameter to scan for
1406 corruption in more or less memory.
1408 memory_corruption_check_period=seconds [X86]
1409 By default it checks for corruption every 60
1410 seconds. Use this parameter to check at some
1411 other rate. 0 disables periodic checking.
1413 memtest= [KNL,X86] Enable memtest
1414 Format: <integer>
1415 default : 0 <disable>
1416 Specifies the number of memtest passes to be
1417 performed. Each pass selects another test
1418 pattern from a given set of patterns. Memtest
1419 fills the memory with this pattern, validates
1420 memory contents and reserves bad memory
1421 regions that are detected.
1423 meye.*= [HW] Set MotionEye Camera parameters
1424 See Documentation/video4linux/meye.txt.
1426 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1427 Multi-Function General Purpose Timers on AMD Geode
1428 platforms.
1430 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1431 the BIOS has incorrectly applied a workaround. TinyBIOS
1432 version 0.98 is known to be affected, 0.99 fixes the
1433 problem by letting the user disable the workaround.
1435 mga= [HW,DRM]
1437 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1438 physical address is ignored.
1440 mini2440= [ARM,HW,KNL]
1441 Format:[0..2][b][c][t]
1442 Default: "0tb"
1443 MINI2440 configuration specification:
1444 0 - The attached screen is the 3.5" TFT
1445 1 - The attached screen is the 7" TFT
1446 2 - The VGA Shield is attached (1024x768)
1447 Leaving out the screen size parameter will not load
1448 the TFT driver, and the framebuffer will be left
1449 unconfigured.
1450 b - Enable backlight. The TFT backlight pin will be
1451 linked to the kernel VESA blanking code and a GPIO
1452 LED. This parameter is not necessary when using the
1453 VGA shield.
1454 c - Enable the s3c camera interface.
1455 t - Reserved for enabling touchscreen support. The
1456 touchscreen support is not enabled in the mainstream
1457 kernel as of 2.6.30, a preliminary port can be found
1458 in the "bleeding edge" mini2440 support kernel at
1459 http://repo.or.cz/w/linux-2.6/mini2440.git
1461 mminit_loglevel=
1462 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1463 parameter allows control of the logging verbosity for
1464 the additional memory initialisation checks. A value
1465 of 0 disables mminit logging and a level of 4 will
1466 log everything. Information is printed at KERN_DEBUG
1467 so loglevel=8 may also need to be specified.
1469 mousedev.tap_time=
1470 [MOUSE] Maximum time between finger touching and
1471 leaving touchpad surface for touch to be considered
1472 a tap and be reported as a left button click (for
1473 touchpads working in absolute mode only).
1474 Format: <msecs>
1475 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1476 reporting absolute coordinates, such as tablets
1477 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1478 reporting absolute coordinates, such as tablets
1480 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1481 is similar to kernelcore except it specifies the
1482 amount of memory used for migratable allocations.
1483 If both kernelcore and movablecore is specified,
1484 then kernelcore will be at *least* the specified
1485 value but may be more. If movablecore on its own
1486 is specified, the administrator must be careful
1487 that the amount of memory usable for all allocations
1488 is not too small.
1490 mpu401= [HW,OSS]
1491 Format: <io>,<irq>
1493 MTD_Partition= [MTD]
1494 Format: <name>,<region-number>,<size>,<offset>
1496 MTD_Region= [MTD] Format:
1497 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1499 mtdparts= [MTD]
1500 See drivers/mtd/cmdlinepart.c.
1502 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1504 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1506 boundary - index of last SLC block on Flex-OneNAND.
1507 The remaining blocks are configured as MLC blocks.
1508 lock - Configure if Flex-OneNAND boundary should be locked.
1509 Once locked, the boundary cannot be changed.
1510 1 indicates lock status, 0 indicates unlock status.
1512 mtdset= [ARM]
1513 ARM/S3C2412 JIVE boot control
1515 See arch/arm/mach-s3c2412/mach-jive.c
1517 mtouchusb.raw_coordinates=
1518 [HW] Make the MicroTouch USB driver use raw coordinates
1519 ('y', default) or cooked coordinates ('n')
1521 mtrr_chunk_size=nn[KMG] [X86]
1522 used for mtrr cleanup. It is largest continuous chunk
1523 that could hold holes aka. UC entries.
1525 mtrr_gran_size=nn[KMG] [X86]
1526 Used for mtrr cleanup. It is granularity of mtrr block.
1527 Default is 1.
1528 Large value could prevent small alignment from
1529 using up MTRRs.
1531 mtrr_spare_reg_nr=n [X86]
1532 Format: <integer>
1533 Range: 0,7 : spare reg number
1534 Default : 1
1535 Used for mtrr cleanup. It is spare mtrr entries number.
1536 Set to 2 or more if your graphical card needs more.
1538 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1540 NCR_D700= [HW,SCSI]
1541 See header of drivers/scsi/NCR_D700.c.
1543 ncr5380= [HW,SCSI]
1545 ncr53c400= [HW,SCSI]
1547 ncr53c400a= [HW,SCSI]
1549 ncr53c406a= [HW,SCSI]
1551 ncr53c8xx= [HW,SCSI]
1553 netdev= [NET] Network devices parameters
1554 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1555 Note that mem_start is often overloaded to mean
1556 something different and driver-specific.
1557 This usage is only documented in each driver source
1558 file if at all.
1560 nf_conntrack.acct=
1561 [NETFILTER] Enable connection tracking flow accounting
1562 0 to disable accounting
1563 1 to enable accounting
1564 Default value depends on CONFIG_NF_CT_ACCT that is
1565 going to be removed in 2.6.29.
1567 nfsaddrs= [NFS]
1568 See Documentation/filesystems/nfs/nfsroot.txt.
1570 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1571 See Documentation/filesystems/nfs/nfsroot.txt.
1573 nfs.callback_tcpport=
1574 [NFS] set the TCP port on which the NFSv4 callback
1575 channel should listen.
1577 nfs.cache_getent=
1578 [NFS] sets the pathname to the program which is used
1579 to update the NFS client cache entries.
1581 nfs.cache_getent_timeout=
1582 [NFS] sets the timeout after which an attempt to
1583 update a cache entry is deemed to have failed.
1585 nfs.idmap_cache_timeout=
1586 [NFS] set the maximum lifetime for idmapper cache
1587 entries.
1589 nfs.enable_ino64=
1590 [NFS] enable 64-bit inode numbers.
1591 If zero, the NFS client will fake up a 32-bit inode
1592 number for the readdir() and stat() syscalls instead
1593 of returning the full 64-bit number.
1594 The default is to return 64-bit inode numbers.
1596 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1597 when a NMI is triggered.
1598 Format: [state][,regs][,debounce][,die]
1600 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1601 Format: [panic,][num]
1602 Valid num: 0,1,2
1603 0 - turn nmi_watchdog off
1604 1 - use the IO-APIC timer for the NMI watchdog
1605 2 - use the local APIC for the NMI watchdog using
1606 a performance counter. Note: This will use one
1607 performance counter and the local APIC's performance
1608 vector.
1609 When panic is specified, panic when an NMI watchdog
1610 timeout occurs.
1611 This is useful when you use a panic=... timeout and
1612 need the box quickly up again.
1613 Instead of 1 and 2 it is possible to use the following
1614 symbolic names: lapic and ioapic
1615 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1617 netpoll.carrier_timeout=
1618 [NET] Specifies amount of time (in seconds) that
1619 netpoll should wait for a carrier. By default netpoll
1620 waits 4 seconds.
1622 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1623 emulation library even if a 387 maths coprocessor
1624 is present.
1626 no_console_suspend
1627 [HW] Never suspend the console
1628 Disable suspending of consoles during suspend and
1629 hibernate operations. Once disabled, debugging
1630 messages can reach various consoles while the rest
1631 of the system is being put to sleep (ie, while
1632 debugging driver suspend/resume hooks). This may
1633 not work reliably with all consoles, but is known
1634 to work with serial and VGA consoles.
1636 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1637 caches in the slab allocator. Saves per-node memory,
1638 but will impact performance.
1640 noalign [KNL,ARM]
1642 noapic [SMP,APIC] Tells the kernel to not make use of any
1643 IOAPICs that may be present in the system.
1645 nobats [PPC] Do not use BATs for mapping kernel lowmem
1646 on "Classic" PPC cores.
1648 nocache [ARM]
1650 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1652 nodelayacct [KNL] Disable per-task delay accounting
1654 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1656 nodsp [SH] Disable hardware DSP at boot time.
1658 noefi [X86] Disable EFI runtime services support.
1660 noexec [IA-64]
1662 noexec [X86]
1663 On X86-32 available only on PAE configured kernels.
1664 noexec=on: enable non-executable mappings (default)
1665 noexec=off: disable non-executable mappings
1667 noexec32 [X86-64]
1668 This affects only 32-bit executables.
1669 noexec32=on: enable non-executable mappings (default)
1670 read doesn't imply executable mappings
1671 noexec32=off: disable non-executable mappings
1672 read implies executable mappings
1674 nofpu [SH] Disable hardware FPU at boot time.
1676 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1677 register save and restore. The kernel will only save
1678 legacy floating-point registers on task switch.
1680 noxsave [BUGS=X86] Disables x86 extended register state save
1681 and restore using xsave. The kernel will fallback to
1682 enabling legacy floating-point and sse state.
1684 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1685 wfi(ARM) instruction doesn't work correctly and not to
1686 use it. This is also useful when using JTAG debugger.
1688 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1689 instruction doesn't work correctly and not to
1690 use it.
1692 no_file_caps Tells the kernel not to honor file capabilities. The
1693 only way then for a file to be executed with privilege
1694 is to be setuid root or executed by root.
1696 nohalt [IA-64] Tells the kernel not to use the power saving
1697 function PAL_HALT_LIGHT when idle. This increases
1698 power-consumption. On the positive side, it reduces
1699 interrupt wake-up latency, which may improve performance
1700 in certain environments such as networked servers or
1701 real-time systems.
1703 nohz= [KNL] Boottime enable/disable dynamic ticks
1704 Valid arguments: on, off
1705 Default: on
1707 noiotrap [SH] Disables trapped I/O port accesses.
1709 noirqdebug [X86-32] Disables the code which attempts to detect and
1710 disable unhandled interrupt sources.
1712 no_timer_check [X86,APIC] Disables the code which tests for
1713 broken timer IRQ sources.
1715 noisapnp [ISAPNP] Disables ISA PnP code.
1717 noinitrd [RAM] Tells the kernel not to load any configured
1718 initial RAM disk.
1720 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1721 remapping.
1723 nointroute [IA-64]
1725 nojitter [IA64] Disables jitter checking for ITC timers.
1727 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1729 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1731 noltlbs [PPC] Do not use large page/tlb entries for kernel
1732 lowmem mapping on PPC40x.
1734 nomca [IA-64] Disable machine check abort handling
1736 nomce [X86-32] Machine Check Exception
1738 nomfgpt [X86-32] Disable Multi-Function General Purpose
1739 Timer usage (for AMD Geode machines).
1741 norandmaps Don't use address space randomization. Equivalent to
1742 echo 0 > /proc/sys/kernel/randomize_va_space
1744 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1746 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1747 with UP alternatives
1749 noresidual [PPC] Don't use residual data on PReP machines.
1751 noresume [SWSUSP] Disables resume and restores original swap
1752 space.
1754 no-scroll [VGA] Disables scrollback.
1755 This is required for the Braillex ib80-piezo Braille
1756 reader made by F.H. Papenmeier (Germany).
1758 nosbagart [IA-64]
1760 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1762 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1763 and disable the IO APIC. legacy for "maxcpus=0".
1765 nosoftlockup [KNL] Disable the soft-lockup detector.
1767 noswapaccount [KNL] Disable accounting of swap in memory resource
1768 controller. (See Documentation/cgroups/memory.txt)
1770 nosync [HW,M68K] Disables sync negotiation for all devices.
1772 notsc [BUGS=X86-32] Disable Time Stamp Counter
1774 nousb [USB] Disable the USB subsystem
1776 nowb [ARM]
1778 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1780 nptcg= [IA64] Override max number of concurrent global TLB
1781 purges which is reported from either PAL_VM_SUMMARY or
1782 SAL PALO.
1784 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1786 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1787 one of ['zone', 'node', 'default'] can be specified
1788 This can be set from sysctl after boot.
1789 See Documentation/sysctl/vm.txt for details.
1791 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1792 See Documentation/debugging-via-ohci1394.txt for more
1793 info.
1795 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1796 Rather than timing out after 20 ms if an EC
1797 command is not properly ACKed, override the length
1798 of the timeout. We have interrupts disabled while
1799 waiting for the ACK, so if this is set too high
1800 interrupts *may* be lost!
1802 omap_mux= [OMAP] Override bootloader pin multiplexing.
1803 Format: <mux_mode0.mode_name=value>...
1804 For example, to override I2C bus2:
1805 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1807 opl3= [HW,OSS]
1808 Format: <io>
1810 oprofile.timer= [HW]
1811 Use timer interrupt instead of performance counters
1813 oprofile.cpu_type= Force an oprofile cpu type
1814 This might be useful if you have an older oprofile
1815 userland or if you want common events.
1816 Format: { arch_perfmon }
1817 arch_perfmon: [X86] Force use of architectural
1818 perfmon on Intel CPUs instead of the
1819 CPU specific event set.
1821 osst= [HW,SCSI] SCSI Tape Driver
1822 Format: <buffer_size>,<write_threshold>
1823 See also Documentation/scsi/st.txt.
1825 panic= [KNL] Kernel behaviour on panic
1826 Format: <timeout>
1828 parkbd.port= [HW] Parallel port number the keyboard adapter is
1829 connected to, default is 0.
1830 Format: <parport#>
1831 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1832 0 for XT, 1 for AT (default is AT).
1833 Format: <mode>
1835 parport= [HW,PPT] Specify parallel ports. 0 disables.
1836 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1837 Use 'auto' to force the driver to use any
1838 IRQ/DMA settings detected (the default is to
1839 ignore detected IRQ/DMA settings because of
1840 possible conflicts). You can specify the base
1841 address, IRQ, and DMA settings; IRQ and DMA
1842 should be numbers, or 'auto' (for using detected
1843 settings on that particular port), or 'nofifo'
1844 (to avoid using a FIFO even if it is detected).
1845 Parallel ports are assigned in the order they
1846 are specified on the command line, starting
1847 with parport0.
1849 parport_init_mode= [HW,PPT]
1850 Configure VIA parallel port to operate in
1851 a specific mode. This is necessary on Pegasos
1852 computer where firmware has no options for setting
1853 up parallel port mode and sets it to spp.
1854 Currently this function knows 686a and 8231 chips.
1855 Format: [spp|ps2|epp|ecp|ecpepp]
1857 pas2= [HW,OSS] Format:
1858 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1860 pas16= [HW,SCSI]
1861 See header of drivers/scsi/pas16.c.
1863 pause_on_oops=
1864 Halt all CPUs after the first oops has been printed for
1865 the specified number of seconds. This is to be used if
1866 your oopses keep scrolling off the screen.
1868 pcbit= [HW,ISDN]
1870 pcd. [PARIDE]
1871 See header of drivers/block/paride/pcd.c.
1872 See also Documentation/blockdev/paride.txt.
1874 pci=option[,option...] [PCI] various PCI subsystem options:
1875 earlydump [X86] dump PCI config space before the kernel
1876 changes anything
1877 off [X86] don't probe for the PCI bus
1878 bios [X86-32] force use of PCI BIOS, don't access
1879 the hardware directly. Use this if your machine
1880 has a non-standard PCI host bridge.
1881 nobios [X86-32] disallow use of PCI BIOS, only direct
1882 hardware access methods are allowed. Use this
1883 if you experience crashes upon bootup and you
1884 suspect they are caused by the BIOS.
1885 conf1 [X86] Force use of PCI Configuration
1886 Mechanism 1.
1887 conf2 [X86] Force use of PCI Configuration
1888 Mechanism 2.
1889 noaer [PCIE] If the PCIEAER kernel config parameter is
1890 enabled, this kernel boot option can be used to
1891 disable the use of PCIE advanced error reporting.
1892 nodomains [PCI] Disable support for multiple PCI
1893 root domains (aka PCI segments, in ACPI-speak).
1894 nommconf [X86] Disable use of MMCONFIG for PCI
1895 Configuration
1896 check_enable_amd_mmconf [X86] check for and enable
1897 properly configured MMIO access to PCI
1898 config space on AMD family 10h CPU
1899 nomsi [MSI] If the PCI_MSI kernel config parameter is
1900 enabled, this kernel boot option can be used to
1901 disable the use of MSI interrupts system-wide.
1902 noioapicquirk [APIC] Disable all boot interrupt quirks.
1903 Safety option to keep boot IRQs enabled. This
1904 should never be necessary.
1905 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1906 primary IO-APIC for bridges that cannot disable
1907 boot IRQs. This fixes a source of spurious IRQs
1908 when the system masks IRQs.
1909 noioapicreroute [APIC] Disable workaround that uses the
1910 boot IRQ equivalent of an IRQ that connects to
1911 a chipset where boot IRQs cannot be disabled.
1912 The opposite of ioapicreroute.
1913 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1914 routing table. These calls are known to be buggy
1915 on several machines and they hang the machine
1916 when used, but on other computers it's the only
1917 way to get the interrupt routing table. Try
1918 this option if the kernel is unable to allocate
1919 IRQs or discover secondary PCI buses on your
1920 motherboard.
1921 rom [X86] Assign address space to expansion ROMs.
1922 Use with caution as certain devices share
1923 address decoders between ROMs and other
1924 resources.
1925 norom [X86] Do not assign address space to
1926 expansion ROMs that do not already have
1927 BIOS assigned address ranges.
1928 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1929 assigned automatically to PCI devices. You can
1930 make the kernel exclude IRQs of your ISA cards
1931 this way.
1932 pirqaddr=0xAAAAA [X86] Specify the physical address
1933 of the PIRQ table (normally generated
1934 by the BIOS) if it is outside the
1935 F0000h-100000h range.
1936 lastbus=N [X86] Scan all buses thru bus #N. Can be
1937 useful if the kernel is unable to find your
1938 secondary buses and you want to tell it
1939 explicitly which ones they are.
1940 assign-busses [X86] Always assign all PCI bus
1941 numbers ourselves, overriding
1942 whatever the firmware may have done.
1943 usepirqmask [X86] Honor the possible IRQ mask stored
1944 in the BIOS $PIR table. This is needed on
1945 some systems with broken BIOSes, notably
1946 some HP Pavilion N5400 and Omnibook XE3
1947 notebooks. This will have no effect if ACPI
1948 IRQ routing is enabled.
1949 noacpi [X86] Do not use ACPI for IRQ routing
1950 or for PCI scanning.
1951 use_crs [X86] Use _CRS for PCI resource
1952 allocation.
1953 routeirq Do IRQ routing for all PCI devices.
1954 This is normally done in pci_enable_device(),
1955 so this option is a temporary workaround
1956 for broken drivers that don't call it.
1957 skip_isa_align [X86] do not align io start addr, so can
1958 handle more pci cards
1959 firmware [ARM] Do not re-enumerate the bus but instead
1960 just use the configuration from the
1961 bootloader. This is currently used on
1962 IXP2000 systems where the bus has to be
1963 configured a certain way for adjunct CPUs.
1964 noearly [X86] Don't do any early type 1 scanning.
1965 This might help on some broken boards which
1966 machine check when some devices' config space
1967 is read. But various workarounds are disabled
1968 and some IOMMU drivers will not work.
1969 bfsort Sort PCI devices into breadth-first order.
1970 This sorting is done to get a device
1971 order compatible with older (<= 2.4) kernels.
1972 nobfsort Don't sort PCI devices into breadth-first order.
1973 cbiosize=nn[KMG] The fixed amount of bus space which is
1974 reserved for the CardBus bridge's IO window.
1975 The default value is 256 bytes.
1976 cbmemsize=nn[KMG] The fixed amount of bus space which is
1977 reserved for the CardBus bridge's memory
1978 window. The default value is 64 megabytes.
1979 resource_alignment=
1980 Format:
1981 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1982 Specifies alignment and device to reassign
1983 aligned memory resources.
1984 If <order of align> is not specified,
1985 PAGE_SIZE is used as alignment.
1986 PCI-PCI bridge can be specified, if resource
1987 windows need to be expanded.
1988 ecrc= Enable/disable PCIe ECRC (transaction layer
1989 end-to-end CRC checking).
1990 bios: Use BIOS/firmware settings. This is the
1991 the default.
1992 off: Turn ECRC off
1993 on: Turn ECRC on.
1995 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1996 Management.
1997 off Disable ASPM.
1998 force Enable ASPM even on devices that claim not to support it.
1999 WARNING: Forcing ASPM on may cause system lockups.
2001 pcmv= [HW,PCMCIA] BadgePAD 4
2003 pd. [PARIDE]
2004 See Documentation/blockdev/paride.txt.
2006 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2007 boot time.
2008 Format: { 0 | 1 }
2009 See arch/parisc/kernel/pdc_chassis.c
2011 percpu_alloc= Select which percpu first chunk allocator to use.
2012 Currently supported values are "embed" and "page".
2013 Archs may support subset or none of the selections.
2014 See comments in mm/percpu.c for details on each
2015 allocator. This parameter is primarily for debugging
2016 and performance comparison.
2018 pf. [PARIDE]
2019 See Documentation/blockdev/paride.txt.
2021 pg. [PARIDE]
2022 See Documentation/blockdev/paride.txt.
2024 pirq= [SMP,APIC] Manual mp-table setup
2025 See Documentation/x86/i386/IO-APIC.txt.
2027 plip= [PPT,NET] Parallel port network link
2028 Format: { parport<nr> | timid | 0 }
2029 See also Documentation/parport.txt.
2031 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2032 Override pmtimer IOPort with a hex value.
2033 e.g. pmtmr=0x508
2035 pnp.debug [PNP]
2036 Enable PNP debug messages. This depends on the
2037 CONFIG_PNP_DEBUG_MESSAGES option.
2039 pnpacpi= [ACPI]
2040 { off }
2042 pnpbios= [ISAPNP]
2043 { on | off | curr | res | no-curr | no-res }
2045 pnp_reserve_irq=
2046 [ISAPNP] Exclude IRQs for the autoconfiguration
2048 pnp_reserve_dma=
2049 [ISAPNP] Exclude DMAs for the autoconfiguration
2051 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2052 Ranges are in pairs (I/O port base and size).
2054 pnp_reserve_mem=
2055 [ISAPNP] Exclude memory regions for the
2056 autoconfiguration.
2057 Ranges are in pairs (memory base and size).
2059 ports= [IP_VS_FTP] IPVS ftp helper module
2060 Default is 21.
2061 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2062 may be specified.
2063 Format: <port>,<port>....
2065 print-fatal-signals=
2066 [KNL] debug: print fatal signals
2068 If enabled, warn about various signal handling
2069 related application anomalies: too many signals,
2070 too many POSIX.1 timers, fatal signals causing a
2071 coredump - etc.
2073 If you hit the warning due to signal overflow,
2074 you might want to try "ulimit -i unlimited".
2076 default: off.
2078 printk.time= Show timing data prefixed to each printk message line
2079 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2081 processor.max_cstate= [HW,ACPI]
2082 Limit processor to maximum C-state
2083 max_cstate=9 overrides any DMI blacklist limit.
2085 processor.nocst [HW,ACPI]
2086 Ignore the _CST method to determine C-states,
2087 instead using the legacy FADT method
2089 profile= [KNL] Enable kernel profiling via /proc/profile
2090 Format: [schedule,]<number>
2091 Param: "schedule" - profile schedule points.
2092 Param: <number> - step/bucket size as a power of 2 for
2093 statistical time based profiling.
2094 Param: "sleep" - profile D-state sleeping (millisecs).
2095 Requires CONFIG_SCHEDSTATS
2096 Param: "kvm" - profile VM exits.
2098 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2099 before loading.
2100 See Documentation/blockdev/ramdisk.txt.
2102 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2103 probe for; one of (bare|imps|exps|lifebook|any).
2104 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2105 per second.
2106 psmouse.resetafter= [HW,MOUSE]
2107 Try to reset the device after so many bad packets
2108 (0 = never).
2109 psmouse.resolution=
2110 [HW,MOUSE] Set desired mouse resolution, in dpi.
2111 psmouse.smartscroll=
2112 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2113 0 = disabled, 1 = enabled (default).
2115 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2116 Format:
2117 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2119 pt. [PARIDE]
2120 See Documentation/blockdev/paride.txt.
2122 pty.legacy_count=
2123 [KNL] Number of legacy pty's. Overwrites compiled-in
2124 default number.
2126 quiet [KNL] Disable most log messages
2128 r128= [HW,DRM]
2130 raid= [HW,RAID]
2131 See Documentation/md.txt.
2133 ramdisk_blocksize= [RAM]
2134 See Documentation/blockdev/ramdisk.txt.
2136 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2137 See Documentation/blockdev/ramdisk.txt.
2139 rcupdate.blimit= [KNL,BOOT]
2140 Set maximum number of finished RCU callbacks to process
2141 in one batch.
2143 rcupdate.qhimark= [KNL,BOOT]
2144 Set threshold of queued
2145 RCU callbacks over which batch limiting is disabled.
2147 rcupdate.qlowmark= [KNL,BOOT]
2148 Set threshold of queued RCU callbacks below which
2149 batch limiting is re-enabled.
2151 rdinit= [KNL]
2152 Format: <full_path>
2153 Run specified binary instead of /init from the ramdisk,
2154 used for early userspace startup. See initrd.
2156 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2157 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2158 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2160 relax_domain_level=
2161 [KNL, SMP] Set scheduler's default relax_domain_level.
2162 See Documentation/cgroups/cpusets.txt.
2164 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2166 reservetop= [X86-32]
2167 Format: nn[KMG]
2168 Reserves a hole at the top of the kernel virtual
2169 address space.
2171 reset_devices [KNL] Force drivers to reset the underlying device
2172 during initialization.
2174 resume= [SWSUSP]
2175 Specify the partition device for software suspend
2177 resume_offset= [SWSUSP]
2178 Specify the offset from the beginning of the partition
2179 given by "resume=" at which the swap header is located,
2180 in <PAGE_SIZE> units (needed only for swap files).
2181 See Documentation/power/swsusp-and-swap-files.txt
2183 retain_initrd [RAM] Keep initrd memory after extraction
2185 rhash_entries= [KNL,NET]
2186 Set number of hash buckets for route cache
2188 riscom8= [HW,SERIAL]
2189 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2191 ro [KNL] Mount root device read-only on boot
2193 root= [KNL] Root filesystem
2195 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2196 mount the root filesystem
2198 rootflags= [KNL] Set root filesystem mount option string
2200 rootfstype= [KNL] Set root filesystem type
2202 rootwait [KNL] Wait (indefinitely) for root device to show up.
2203 Useful for devices that are detected asynchronously
2204 (e.g. USB and MMC devices).
2206 rw [KNL] Mount root device read-write on boot
2208 S [KNL] Run init in single mode
2210 sa1100ir [NET]
2211 See drivers/net/irda/sa1100_ir.c.
2213 sbni= [NET] Granch SBNI12 leased line adapter
2215 sched_debug [KNL] Enables verbose scheduler debug messages.
2217 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2218 Format: <io>[,<timeout>[,<isapnp>]]
2220 scsi_debug_*= [SCSI]
2221 See drivers/scsi/scsi_debug.c.
2223 scsi_default_dev_flags=
2224 [SCSI] SCSI default device flags
2225 Format: <integer>
2227 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2228 Format: <vendor>:<model>:<flags>
2229 (flags are integer value)
2231 scsi_logging_level= [SCSI] a bit mask of logging levels
2232 See drivers/scsi/scsi_logging.h for bits. Also
2233 settable via sysctl at dev.scsi.logging_level
2234 (/proc/sys/dev/scsi/logging_level).
2235 There is also a nice 'scsi_logging_level' script in the
2236 S390-tools package, available for download at
2237 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2239 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2240 discovered. async scans them in kernel threads,
2241 allowing boot to proceed. none ignores them, expecting
2242 user space to do the scan.
2244 security= [SECURITY] Choose a security module to enable at boot.
2245 If this boot parameter is not specified, only the first
2246 security module asking for security registration will be
2247 loaded. An invalid security module name will be treated
2248 as if no module has been chosen.
2250 selinux= [SELINUX] Disable or enable SELinux at boot time.
2251 Format: { "0" | "1" }
2252 See security/selinux/Kconfig help text.
2253 0 -- disable.
2254 1 -- enable.
2255 Default value is set via kernel config option.
2256 If enabled at boot time, /selinux/disable can be used
2257 later to disable prior to initial policy load.
2259 serialnumber [BUGS=X86-32]
2261 shapers= [NET]
2262 Maximal number of shapers.
2264 show_msr= [x86] show boot-time MSR settings
2265 Format: { <integer> }
2266 Show boot-time (BIOS-initialized) MSR settings.
2267 The parameter means the number of CPUs to show,
2268 for example 1 means boot CPU only.
2270 sim710= [SCSI,HW]
2271 See header of drivers/scsi/sim710.c.
2273 simeth= [IA-64]
2274 simscsi=
2276 slram= [HW,MTD]
2278 slub_debug[=options[,slabs]] [MM, SLUB]
2279 Enabling slub_debug allows one to determine the
2280 culprit if slab objects become corrupted. Enabling
2281 slub_debug can create guard zones around objects and
2282 may poison objects when not in use. Also tracks the
2283 last alloc / free. For more information see
2284 Documentation/vm/slub.txt.
2286 slub_max_order= [MM, SLUB]
2287 Determines the maximum allowed order for slabs.
2288 A high setting may cause OOMs due to memory
2289 fragmentation. For more information see
2290 Documentation/vm/slub.txt.
2292 slub_min_objects= [MM, SLUB]
2293 The minimum number of objects per slab. SLUB will
2294 increase the slab order up to slub_max_order to
2295 generate a sufficiently large slab able to contain
2296 the number of objects indicated. The higher the number
2297 of objects the smaller the overhead of tracking slabs
2298 and the less frequently locks need to be acquired.
2299 For more information see Documentation/vm/slub.txt.
2301 slub_min_order= [MM, SLUB]
2302 Determines the mininum page order for slabs. Must be
2303 lower than slub_max_order.
2304 For more information see Documentation/vm/slub.txt.
2306 slub_nomerge [MM, SLUB]
2307 Disable merging of slabs with similar size. May be
2308 necessary if there is some reason to distinguish
2309 allocs to different slabs. Debug options disable
2310 merging on their own.
2311 For more information see Documentation/vm/slub.txt.
2313 smart2= [HW]
2314 Format: <io1>[,<io2>[,...,<io8>]]
2316 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2317 attempt to substitute SMP alternatives once at boot.
2319 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2320 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2321 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2322 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2323 smsc-ircc2.ircc_irq= [HW] IRQ line
2324 smsc-ircc2.ircc_dma= [HW] DMA channel
2325 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2326 0: Toshiba Satellite 1800 (GP data pin select)
2327 1: Fast pin select (default)
2328 2: ATC IRMode
2330 snd-ad1816a= [HW,ALSA]
2332 snd-ad1848= [HW,ALSA]
2334 snd-ali5451= [HW,ALSA]
2336 snd-als100= [HW,ALSA]
2338 snd-als4000= [HW,ALSA]
2340 snd-azt2320= [HW,ALSA]
2342 snd-cmi8330= [HW,ALSA]
2344 snd-cmipci= [HW,ALSA]
2346 snd-cs4231= [HW,ALSA]
2348 snd-cs4232= [HW,ALSA]
2350 snd-cs4236= [HW,ALSA]
2352 snd-cs4281= [HW,ALSA]
2354 snd-cs46xx= [HW,ALSA]
2356 snd-dt019x= [HW,ALSA]
2358 snd-dummy= [HW,ALSA]
2360 snd-emu10k1= [HW,ALSA]
2362 snd-ens1370= [HW,ALSA]
2364 snd-ens1371= [HW,ALSA]
2366 snd-es968= [HW,ALSA]
2368 snd-es1688= [HW,ALSA]
2370 snd-es18xx= [HW,ALSA]
2372 snd-es1938= [HW,ALSA]
2374 snd-es1968= [HW,ALSA]
2376 snd-fm801= [HW,ALSA]
2378 snd-gusclassic= [HW,ALSA]
2380 snd-gusextreme= [HW,ALSA]
2382 snd-gusmax= [HW,ALSA]
2384 snd-hdsp= [HW,ALSA]
2386 snd-ice1712= [HW,ALSA]
2388 snd-intel8x0= [HW,ALSA]
2390 snd-interwave= [HW,ALSA]
2392 snd-interwave-stb=
2393 [HW,ALSA]
2395 snd-korg1212= [HW,ALSA]
2397 snd-maestro3= [HW,ALSA]
2399 snd-mpu401= [HW,ALSA]
2401 snd-mtpav= [HW,ALSA]
2403 snd-nm256= [HW,ALSA]
2405 snd-opl3sa2= [HW,ALSA]
2407 snd-opti92x-ad1848=
2408 [HW,ALSA]
2410 snd-opti92x-cs4231=
2411 [HW,ALSA]
2413 snd-opti93x= [HW,ALSA]
2415 snd-pmac= [HW,ALSA]
2417 snd-rme32= [HW,ALSA]
2419 snd-rme96= [HW,ALSA]
2421 snd-rme9652= [HW,ALSA]
2423 snd-sb8= [HW,ALSA]
2425 snd-sb16= [HW,ALSA]
2427 snd-sbawe= [HW,ALSA]
2429 snd-serial= [HW,ALSA]
2431 snd-sgalaxy= [HW,ALSA]
2433 snd-sonicvibes= [HW,ALSA]
2435 snd-sun-amd7930=
2436 [HW,ALSA]
2438 snd-sun-cs4231= [HW,ALSA]
2440 snd-trident= [HW,ALSA]
2442 snd-usb-audio= [HW,ALSA,USB]
2444 snd-via82xx= [HW,ALSA]
2446 snd-virmidi= [HW,ALSA]
2448 snd-wavefront= [HW,ALSA]
2450 snd-ymfpci= [HW,ALSA]
2452 softlockup_panic=
2453 [KNL] Should the soft-lockup detector generate panics.
2455 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2456 See Documentation/sonypi.txt
2458 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2459 See Documentation/serial/specialix.txt.
2461 spia_io_base= [HW,MTD]
2462 spia_fio_base=
2463 spia_pedr=
2464 spia_peddr=
2466 sscape= [HW,OSS]
2467 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2469 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2470 See Documentation/scsi/st.txt.
2472 stacktrace [FTRACE]
2473 Enabled the stack tracer on boot up.
2475 sti= [PARISC,HW]
2476 Format: <num>
2477 Set the STI (builtin display/keyboard on the HP-PARISC
2478 machines) console (graphic card) which should be used
2479 as the initial boot-console.
2480 See also comment in drivers/video/console/sticore.c.
2482 sti_font= [HW]
2483 See comment in drivers/video/console/sticore.c.
2485 stifb= [HW]
2486 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2488 sunrpc.min_resvport=
2489 sunrpc.max_resvport=
2490 [NFS,SUNRPC]
2491 SunRPC servers often require that client requests
2492 originate from a privileged port (i.e. a port in the
2493 range 0 < portnr < 1024).
2494 An administrator who wishes to reserve some of these
2495 ports for other uses may adjust the range that the
2496 kernel's sunrpc client considers to be privileged
2497 using these two parameters to set the minimum and
2498 maximum port values.
2500 sunrpc.pool_mode=
2501 [NFS]
2502 Control how the NFS server code allocates CPUs to
2503 service thread pools. Depending on how many NICs
2504 you have and where their interrupts are bound, this
2505 option will affect which CPUs will do NFS serving.
2506 Note: this parameter cannot be changed while the
2507 NFS server is running.
2509 auto the server chooses an appropriate mode
2510 automatically using heuristics
2511 global a single global pool contains all CPUs
2512 percpu one pool for each CPU
2513 pernode one pool for each NUMA node (equivalent
2514 to global on non-NUMA machines)
2516 sunrpc.tcp_slot_table_entries=
2517 sunrpc.udp_slot_table_entries=
2518 [NFS,SUNRPC]
2519 Sets the upper limit on the number of simultaneous
2520 RPC calls that can be sent from the client to a
2521 server. Increasing these values may allow you to
2522 improve throughput, but will also increase the
2523 amount of memory reserved for use by the client.
2525 swiotlb= [IA-64] Number of I/O TLB slabs
2527 switches= [HW,M68k]
2529 sym53c416= [HW,SCSI]
2530 See header of drivers/scsi/sym53c416.c.
2532 sysrq_always_enabled
2533 [KNL]
2534 Ignore sysrq setting - this boot parameter will
2535 neutralize any effect of /proc/sys/kernel/sysrq.
2536 Useful for debugging.
2538 t128= [HW,SCSI]
2539 See header of drivers/scsi/t128.c.
2541 tdfx= [HW,DRM]
2543 test_suspend= [SUSPEND]
2544 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2545 standby suspend) as the system sleep state to briefly
2546 enter during system startup. The system is woken from
2547 this state using a wakeup-capable RTC alarm.
2549 thash_entries= [KNL,NET]
2550 Set number of hash buckets for TCP connection
2552 thermal.act= [HW,ACPI]
2553 -1: disable all active trip points in all thermal zones
2554 <degrees C>: override all lowest active trip points
2556 thermal.crt= [HW,ACPI]
2557 -1: disable all critical trip points in all thermal zones
2558 <degrees C>: override all critical trip points
2560 thermal.nocrt= [HW,ACPI]
2561 Set to disable actions on ACPI thermal zone
2562 critical and hot trip points.
2564 thermal.off= [HW,ACPI]
2565 1: disable ACPI thermal control
2567 thermal.psv= [HW,ACPI]
2568 -1: disable all passive trip points
2569 <degrees C>: override all passive trip points to this
2570 value
2572 thermal.tzp= [HW,ACPI]
2573 Specify global default ACPI thermal zone polling rate
2574 <deci-seconds>: poll all this frequency
2575 0: no polling (default)
2577 tmscsim= [HW,SCSI]
2578 See comment before function dc390_setup() in
2579 drivers/scsi/tmscsim.c.
2581 topology= [S390]
2582 Format: {off | on}
2583 Specify if the kernel should make use of the cpu
2584 topology informations if the hardware supports these.
2585 The scheduler will make use of these informations and
2586 e.g. base its process migration decisions on it.
2587 Default is off.
2589 tp720= [HW,PS2]
2591 trace_buf_size=nn[KMG]
2592 [FTRACE] will set tracing buffer size.
2594 trace_event=[event-list]
2595 [FTRACE] Set and start specified trace events in order
2596 to facilitate early boot debugging.
2597 See also Documentation/trace/events.txt
2599 trix= [HW,OSS] MediaTrix AudioTrix Pro
2600 Format:
2601 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2603 tsc= Disable clocksource-must-verify flag for TSC.
2604 Format: <string>
2605 [x86] reliable: mark tsc clocksource as reliable, this
2606 disables clocksource verification at runtime.
2607 Used to enable high-resolution timer mode on older
2608 hardware, and in virtualized environment.
2610 turbografx.map[2|3]= [HW,JOY]
2611 TurboGraFX parallel port interface
2612 Format:
2613 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2614 See also Documentation/input/joystick-parport.txt
2616 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2617 See header of drivers/scsi/u14-34f.c.
2619 uart401= [HW,OSS]
2620 Format: <io>,<irq>
2622 uart6850= [HW,OSS]
2623 Format: <io>,<irq>
2625 uhash_entries= [KNL,NET]
2626 Set number of hash buckets for UDP/UDP-Lite connections
2628 uhci-hcd.ignore_oc=
2629 [USB] Ignore overcurrent events (default N).
2630 Some badly-designed motherboards generate lots of
2631 bogus events, for ports that aren't wired to
2632 anything. Set this parameter to avoid log spamming.
2633 Note that genuine overcurrent events won't be
2634 reported either.
2636 unknown_nmi_panic
2637 [X86]
2638 Set unknown_nmi_panic=1 early on boot.
2640 usbcore.autosuspend=
2641 [USB] The autosuspend time delay (in seconds) used
2642 for newly-detected USB devices (default 2). This
2643 is the time required before an idle device will be
2644 autosuspended. Devices for which the delay is set
2645 to a negative value won't be autosuspended at all.
2647 usbcore.usbfs_snoop=
2648 [USB] Set to log all usbfs traffic (default 0 = off).
2650 usbcore.blinkenlights=
2651 [USB] Set to cycle leds on hubs (default 0 = off).
2653 usbcore.old_scheme_first=
2654 [USB] Start with the old device initialization
2655 scheme (default 0 = off).
2657 usbcore.use_both_schemes=
2658 [USB] Try the other device initialization scheme
2659 if the first one fails (default 1 = enabled).
2661 usbcore.initial_descriptor_timeout=
2662 [USB] Specifies timeout for the initial 64-byte
2663 USB_REQ_GET_DESCRIPTOR request in milliseconds
2664 (default 5000 = 5.0 seconds).
2666 usbhid.mousepoll=
2667 [USBHID] The interval which mice are to be polled at.
2669 usb-storage.delay_use=
2670 [UMS] The delay in seconds before a new device is
2671 scanned for Logical Units (default 5).
2673 usb-storage.quirks=
2674 [UMS] A list of quirks entries to supplement or
2675 override the built-in unusual_devs list. List
2676 entries are separated by commas. Each entry has
2677 the form VID:PID:Flags where VID and PID are Vendor
2678 and Product ID values (4-digit hex numbers) and
2679 Flags is a set of characters, each corresponding
2680 to a common usb-storage quirk flag as follows:
2681 a = SANE_SENSE (collect more than 18 bytes
2682 of sense data);
2683 b = BAD_SENSE (don't collect more than 18
2684 bytes of sense data);
2685 c = FIX_CAPACITY (decrease the reported
2686 device capacity by one sector);
2687 h = CAPACITY_HEURISTICS (decrease the
2688 reported device capacity by one
2689 sector if the number is odd);
2690 i = IGNORE_DEVICE (don't bind to this
2691 device);
2692 l = NOT_LOCKABLE (don't try to lock and
2693 unlock ejectable media);
2694 m = MAX_SECTORS_64 (don't transfer more
2695 than 64 sectors = 32 KB at a time);
2696 o = CAPACITY_OK (accept the capacity
2697 reported by the device);
2698 r = IGNORE_RESIDUE (the device reports
2699 bogus residue values);
2700 s = SINGLE_LUN (the device has only one
2701 Logical Unit);
2702 w = NO_WP_DETECT (don't test whether the
2703 medium is write-protected).
2704 Example: quirks=0419:aaf5:rl,0421:0433:rc
2706 vdso= [X86,SH]
2707 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2708 vdso=1: enable VDSO (default)
2709 vdso=0: disable VDSO mapping
2711 vdso32= [X86]
2712 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2713 vdso32=1: enable 32-bit VDSO (default)
2714 vdso32=0: disable 32-bit VDSO mapping
2716 vector= [IA-64,SMP]
2717 vector=percpu: enable percpu vector domain
2719 video= [FB] Frame buffer configuration
2720 See Documentation/fb/modedb.txt.
2722 vga= [BOOT,X86-32] Select a particular video mode
2723 See Documentation/x86/boot.txt and
2724 Documentation/svga.txt.
2725 Use vga=ask for menu.
2726 This is actually a boot loader parameter; the value is
2727 passed to the kernel using a special protocol.
2729 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2730 size of <nn>. This can be used to increase the
2731 minimum size (128MB on x86). It can also be used to
2732 decrease the size and leave more room for directly
2733 mapped kernel RAM.
2735 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2736 Format: <command>
2738 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2739 Format: <command>
2741 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2742 Format: <command>
2744 vt.cur_default= [VT] Default cursor shape.
2745 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2746 the parameters of the <Esc>[?A;B;Cc escape sequence;
2747 see VGA-softcursor.txt. Default: 2 = underline.
2749 vt.default_blu= [VT]
2750 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2751 Change the default blue palette of the console.
2752 This is a 16-member array composed of values
2753 ranging from 0-255.
2755 vt.default_grn= [VT]
2756 Format: <green0>,<green1>,<green2>,...,<green15>
2757 Change the default green palette of the console.
2758 This is a 16-member array composed of values
2759 ranging from 0-255.
2761 vt.default_red= [VT]
2762 Format: <red0>,<red1>,<red2>,...,<red15>
2763 Change the default red palette of the console.
2764 This is a 16-member array composed of values
2765 ranging from 0-255.
2767 vt.default_utf8=
2768 [VT]
2769 Format=<0|1>
2770 Set system-wide default UTF-8 mode for all tty's.
2771 Default is 1, i.e. UTF-8 mode is enabled for all
2772 newly opened terminals.
2774 vt.global_cursor_default=
2775 [VT]
2776 Format=<-1|0|1>
2777 Set system-wide default for whether a cursor
2778 is shown on new VTs. Default is -1,
2779 i.e. cursors will be created by default unless
2780 overridden by individual drivers. 0 will hide
2781 cursors, 1 will display them.
2783 waveartist= [HW,OSS]
2784 Format: <io>,<irq>,<dma>,<dma2>
2786 wd33c93= [HW,SCSI]
2787 See header of drivers/scsi/wd33c93.c.
2789 wd7000= [HW,SCSI]
2790 See header of drivers/scsi/wd7000.c.
2792 wdt= [WDT] Watchdog
2793 See Documentation/watchdog/wdt.txt.
2795 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2796 default x2apic cluster mode on platforms
2797 supporting x2apic.
2799 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2800 xd_geo= See header of drivers/block/xd.c.
2802 xirc2ps_cs= [NET,PCMCIA]
2803 Format:
2804 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2806 ______________________________________________________________________
2808 TODO:
2810 Add documentation for ALSA options.
2811 Add more DRM drivers.