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 IPV6 IPv6 support is enabled.
58 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
61 KVM Kernel Virtual Machine support is enabled.
62 LIBATA Libata driver is enabled
63 LP Printer support is enabled.
64 LOOP Loopback device support is enabled.
65 M68k M68k architecture is enabled.
66 These options have more detailed description inside of
67 Documentation/m68k/kernel-options.txt.
68 MCA MCA bus support is enabled.
69 MDA MDA console support is enabled.
70 MOUSE Appropriate mouse support is enabled.
71 MSI Message Signaled Interrupts (PCI).
72 MTD MTD (Memory Technology Device) support is enabled.
73 NET Appropriate network support is enabled.
74 NUMA NUMA support is enabled.
75 GENERIC_TIME The generic timeofday code is enabled.
76 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
78 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
80 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
82 PCIE PCI Express support is enabled.
83 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
93 SECURITY Different security models are enabled.
94 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
96 SH SuperH architecture is enabled.
97 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
99 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
101 FTRACE Function tracing enabled.
102 TS Appropriate touchscreen support is enabled.
103 UMS USB Mass Storage support is enabled.
104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
111 X86-32 X86-32, aka i386 architecture is enabled.
112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
114 Documentation/x86/x86_64/boot-options.txt .
115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
117 In addition, the following text indicates that the option:
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
123 Parameters denoted with BOOT are actually interpreted by the boot
124 loader, and have no meaning to the kernel directly.
125 Do not modify the syntax of boot loader parameters without extreme
126 need or coordination with <Documentation/x86/boot.txt>.
128 There are also arch-specific kernel-parameters not documented here.
129 See for example <Documentation/x86/x86_64/boot-options.txt>.
131 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132 a trailing = on the name of any parameter states that that parameter will
133 be entered as an environment variable, whereas its absence indicates that
134 it will appear as a kernel argument readable via /proc/cmdline by programs
135 running once the system is up.
137 The number of kernel parameters is not limited, but the length of the
138 complete command line (parameters including spaces etc.) is limited to
139 a fixed number of characters. This limit depends on the architecture
140 and is between 256 and 4096 characters. It is defined in the file
141 ./include/asm/setup.h as COMMAND_LINE_SIZE.
145 Advanced Configuration and Power Interface
146 Format: { force | off | ht | strict | noirq | rsdt }
147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
151 strict -- Be less tolerant of platforms that are not
152 strictly ACPI specification compliant.
153 rsdt -- prefer RSDT over (default) XSDT
155 See also Documentation/power/pm.txt, pci=noacpi
157 acpi_apic_instance= [ACPI, IOAPIC]
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
203 acpi_early_pdc_eval [HW,ACPI] Evaluate processor _PDC methods
204 early. Needed on some platforms to properly
207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
220 Format: <irq>,<irq>...
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
240 acpi_serialize [HW,ACPI] force serialization of AML methods
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
248 old_ordering, s4_nonvs, sci_force_enable }
249 See Documentation/power/video.txt for information on
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
259 s4_nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during hibernation.
261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
286 Format: <io>,<irq>,<dma>,<dma2>,<type>
288 add_efi_memmap [EFI; X86] Include EFI memory map in
289 kernel's map of available physical RAM.
292 See header of drivers/scsi/advansys.c.
294 advwdt= [HW,WDT] Advantech WDT
295 Format: <iostart>,<iostop>
297 aedsp16= [HW,OSS] Audio Excel DSP 16
298 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
299 See also header of sound/oss/aedsp16.c.
302 { off | try_unsupported }
303 off: disable AGP support
304 try_unsupported: try to drive unsupported chipsets
305 (may crash computer or cause data corruption)
308 See Documentation/scsi/aha152x.txt.
311 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
314 See Documentation/scsi/aic7xxx.txt.
317 See Documentation/scsi/aic79xx.txt.
320 Allow the default userspace alignment fault handler
321 behaviour to be specified. Bit 0 enables warnings,
322 bit 1 enables fixups, and bit 2 sends a segfault.
324 amd_iommu= [HW,X86-84]
325 Pass parameters to the AMD IOMMU driver in the system.
327 isolate - enable device isolation (each device, as far
328 as possible, will get its own protection
330 share - put every device behind one IOMMU into the
331 same protection domain
332 fullflush - enable flushing of IO/TLB entries when
333 they are unmapped. Otherwise they are
334 flushed before they will be reused, which
337 amijoy.map= [HW,JOY] Amiga joystick support
338 Map of devices attached to JOY0DAT and JOY1DAT
340 See also Documentation/kernel/input/joystick.txt
342 analog.map= [HW,JOY] Analog joystick and gamepad support
343 Specifies type or capabilities of an analog joystick
344 connected to one of 16 gameports
345 Format: <type1>,<type2>,..<type16>
348 Power management functions (SPARCstation-4/5 + deriv.)
350 Disable APC CPU standby support. SPARCstation-Fox does
351 not play well with APC CPU idle - disable it if you have
352 APC and your system crashes randomly.
354 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
355 Change the output verbosity whilst booting
356 Format: { quiet (default) | verbose | debug }
357 Change the amount of debugging information output
358 when initialising the APIC and IO-APIC components.
361 See Documentation/networking/ipv6.txt.
363 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
364 Limit apic dumping. The parameter defines the maximal
365 number of local apics being dumped. Also it is possible
366 to set it to "all" by meaning -- no limit here.
367 Format: { 1 (default) | 2 | ... | all }.
368 The parameter valid if only apic=debug or
369 apic=verbose is specified.
370 Example: apic=debug show_lapic=all
372 apm= [APM] Advanced Power Management
373 See header of arch/x86/kernel/apm_32.c.
375 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
376 Format: <io>,<irq>,<nodeID>
380 atarimouse= [HW,MOUSE] Atari Mouse
382 atascsi= [HW,SCSI] Atari SCSI
384 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
385 EzKey and similar keyboards
387 atkbd.reset= [HW] Reset keyboard during initialization
389 atkbd.set= [HW] Select keyboard code set
390 Format: <int> (2 = AT (default), 3 = PS/2)
392 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
395 atkbd.softraw= [HW] Choose between synthetic and real raw mode
396 Format: <bool> (0 = real, 1 = synthetic (default))
398 atkbd.softrepeat= [HW]
399 Use software keyboard repeat
403 baycom_epp= [HW,AX25]
406 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
408 See header of drivers/net/hamradio/baycom_par.c.
410 baycom_ser_fdx= [HW,AX25]
411 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
412 Format: <io>,<irq>,<mode>[,<baud>]
413 See header of drivers/net/hamradio/baycom_ser_fdx.c.
415 baycom_ser_hdx= [HW,AX25]
416 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
417 Format: <io>,<irq>,<mode>
418 See header of drivers/net/hamradio/baycom_ser_hdx.c.
420 boot_delay= Milliseconds to delay each printk during boot.
421 Values larger than 10 seconds (10000) are changed to
425 bootmem_debug [KNL] Enable bootmem allocator debug messages.
427 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
428 bttv.radio= Most important insmod options are available as
430 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
431 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
434 See drivers/scsi/BusLogic.c, comment before function
435 BusLogic_ParseDriverOptions().
437 c101= [NET] Moxa C101 synchronous serial card
439 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
440 Sometimes CPU hardware bugs make them report the cache
441 size incorrectly. The kernel will attempt work arounds
442 to fix known problems, but for some CPUs it is not
443 possible to determine what the correct size should be.
444 This option provides an override for these situations.
447 [SECURITY] Disable capabilities. This would normally
448 be used only if an alternative security model is to be
449 configured. Potentially dangerous and should only be
450 used if you are entirely sure of the consequences.
452 ccw_timeout_log [S390]
453 See Documentation/s390/CommonIO for details.
455 cgroup_disable= [KNL] Disable a particular controller
456 cgroup_enable= [KNL] Enable a particular controller
457 For both cgroup_enable and cgroup_enable
458 Format: {name of the controller(s) to disable}
459 {Currently supported controllers - "memory"}
460 {Memory controller is disabled by default}
462 checkreqprot [SELINUX] Set initial checkreqprot flag value.
463 Format: { "0" | "1" }
464 See security/selinux/Kconfig help text.
465 0 -- check protection applied by kernel (includes
466 any implied execute protection).
467 1 -- check protection requested by application.
468 Default value is set via a kernel config option.
469 Value can be changed at runtime via
470 /selinux/checkreqprot.
473 See Documentation/s390/CommonIO for details.
475 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
477 Forces specified clocksource (if available) to be used
478 when calculating gettimeofday(). If specified
479 clocksource is not available, it defaults to PIT.
480 Format: { pit | tsc | cyclone | pmtmr }
482 clocksource= [GENERIC_TIME] Override the default clocksource
484 Override the default clocksource and use the clocksource
485 with the name specified.
486 Some clocksource names to choose from, depending on
488 [all] jiffies (this is the base, fallback clocksource)
490 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
491 pxa_timer,timer3,32k_counter,timer0_1
493 [X86-32] pit,hpet,tsc,vmi-timer;
494 scx200_hrt on Geode; cyclone on IBM x440
502 clearcpuid=BITNUM [X86]
503 Disable CPUID feature X for the kernel. See
504 arch/x86/include/asm/cpufeature.h for the valid bit
505 numbers. Note the Linux specific bits are not necessarily
506 stable over kernel options, but the vendor specific
508 Also note that user programs calling CPUID directly
509 or using the feature without checking anything
510 will still see it. This just prevents it from
511 being used by the kernel or shown in /proc/cpuinfo.
512 Also note the kernel might malfunction if you disable
515 cmo_free_hint= [PPC] Format: { yes | no }
516 Specify whether pages are marked as being inactive
517 when they are freed. This is used in CMO environments
518 to determine OS memory pressure for page stealing by
522 code_bytes [X86] How many bytes of object code to print
527 com20020= [HW,NET] ARCnet - COM20020 chipset
529 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
531 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
535 ARCnet - COM90xx chipset (memory-mapped buffers)
536 Format: <io>[,<irq>[,<memstart>]]
538 condev= [HW,S390] console device
541 console= [KNL] Output console device and options.
543 tty<n> Use the virtual console device <n>.
547 Use the specified serial port. The options are of
548 the form "bbbbpnf", where "bbbb" is the baud rate,
549 "p" is parity ("n", "o", or "e"), "n" is number of
550 bits, and "f" is flow control ("r" for RTS or
551 omit it). Default is "9600n8".
553 See Documentation/serial-console.txt for more
555 Documentation/networking/netconsole.txt for an
558 uart[8250],io,<addr>[,options]
559 uart[8250],mmio,<addr>[,options]
560 Start an early, polled-mode console on the 8250/16550
561 UART at the specified I/O port or MMIO address,
562 switching to the matching ttyS device later. The
563 options are the same as for ttyS, above.
565 If the device connected to the port is not a TTY but a braille
566 device, prepend "brl," before the device type, for instance
568 For now, only VisioBraille is supported.
570 consoleblank= [KNL] The console blank (screen saver) timeout in
571 seconds. Defaults to 10*60 = 10mins. A value of 0
572 disables the blank timer.
575 [KNL] Change the default value for
576 /proc/<pid>/coredump_filter.
577 See also Documentation/filesystems/proc.txt.
579 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
581 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
583 crashkernel=nn[KMG]@ss[KMG]
584 [KNL] Reserve a chunk of physical memory to
585 hold a kernel to switch to with kexec on panic.
587 crashkernel=range1:size1[,range2:size2,...][@offset]
588 [KNL] Same as above, but depends on the memory
589 in the running system. The syntax of range is
590 start-[end] where start and end are both
591 a memory unit (amount[KMG]). See also
592 Documentation/kdump/kdump.txt for a example.
597 cs89x0_media= [HW,NET]
598 Format: { rj45 | aui | bnc }
601 See header of drivers/s390/block/dasd_devmap.c.
603 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
604 (one device per port)
605 Format: <port#>,<type>
606 See also Documentation/input/joystick-parport.txt
608 debug [KNL] Enable kernel debugging (events log level).
611 [KNL] verbose self-tests
613 Print debugging info while doing the locking API
615 We default to 0 (no extra messages), setting it to
616 1 will print _a lot_ more information - normally
617 only useful to kernel developers.
619 debug_objects [KNL] Enable object debugging
622 [KNL] Disable object debugging
624 debugpat [X86] Enable PAT debugging
626 decnet.addr= [HW,NET]
627 Format: <area>[,<node>]
628 See also Documentation/networking/decnet.txt.
631 [same as hugepagesz=] The size of the default
632 HugeTLB page size. This is the size represented by
633 the legacy /proc/ hugepages APIs, used for SHM, and
634 default size when mounting hugetlbfs filesystems.
635 Defaults to the default architecture's huge page size
639 Set number of hash buckets for dentry cache.
642 IO parameters + enable/disable command.
644 digiepca= [HW,SERIAL]
645 See drivers/char/README.epca and
646 Documentation/serial/digiepca.txt.
649 See Documentation/networking/ipv6.txt.
652 See Documentation/networking/ipv6.txt.
654 disable_mtrr_cleanup [X86]
655 The kernel tries to adjust MTRR layout from continuous
656 to discrete, to make X server driver able to add WB
657 entry later. This parameter disables that.
659 disable_mtrr_trim [X86, Intel and AMD only]
660 By default the kernel will trim any uncacheable
661 memory out of your available memory pool based on
662 MTRR settings. This parameter disables that behavior,
663 possibly causing your machine to run very slowly.
665 disable_timer_pin_1 [X86]
666 Disable PIN 1 of APIC timer
667 Can be useful to work around chipset bugs.
669 dmasound= [HW,OSS] Sound subsystem buffers
671 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
672 this option disables the debugging code at boot.
674 dma_debug_entries=<number>
675 This option allows to tune the number of preallocated
676 entries for DMA-API debugging code. One entry is
677 required per DMA-API allocation. Use this if the
678 DMA-API debugging code disables itself because the
679 architectural default is too low.
681 dma_debug_driver=<driver_name>
682 With this option the DMA-API debugging driver
683 filter feature can be enabled at boot time. Just
684 pass the driver to filter for as the parameter.
685 The filter can be disabled or changed to another
686 driver later using sysfs.
692 dynamic_printk Enables pr_debug()/dev_dbg() calls if
693 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
694 These can also be switched on/off via
695 <debugfs>/dynamic_printk/modules
697 earlycon= [KNL] Output early console device and options.
698 uart[8250],io,<addr>[,options]
699 uart[8250],mmio,<addr>[,options]
700 Start an early, polled-mode console on the 8250/16550
701 UART at the specified I/O port or MMIO address.
702 The options are the same as for ttyS, above.
704 earlyprintk= [X86,SH,BLACKFIN]
706 earlyprintk=serial[,ttySn[,baudrate]]
707 earlyprintk=ttySn[,baudrate]
708 earlyprintk=dbgp[debugController#]
710 Append ",keep" to not disable it when the real console
713 Only vga or serial or usb debug port at a time.
715 Currently only ttyS0 and ttyS1 are supported.
717 Interaction with the standard serial driver is not
720 The VGA output is eventually overwritten by the real
726 Format: {"off" | "on" | "skip[mbr]"}
728 eisa_irq_edge= [PARISC,HW]
729 See header of drivers/parisc/eisa.c.
732 See comment before function elanfreq_setup() in
733 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
736 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
737 See Documentation/block/as-iosched.txt and
738 Documentation/block/deadline-iosched.txt for details.
740 elfcorehdr= [IA64,PPC,SH,X86]
741 Specifies physical address of start of kernel core
742 image elf header. Generally kexec loader will
743 pass this option to capture kernel.
744 See Documentation/kdump/kdump.txt for details.
746 enable_mtrr_cleanup [X86]
747 The kernel tries to adjust MTRR layout from continuous
748 to discrete, to make X server driver able to add WB
749 entry later. This parameter enables that.
751 enable_timer_pin_1 [X86]
752 Enable PIN 1 of APIC timer
753 Can be useful to work around chipset bugs
754 (in particular on some ATI chipsets).
755 The kernel tries to set a reasonable default.
757 enforcing [SELINUX] Set initial enforcing status.
759 See security/selinux/Kconfig help text.
760 0 -- permissive (log only, no denials).
761 1 -- enforcing (deny and log).
763 Value can be changed at runtime via /selinux/enforce.
765 ether= [HW,NET] Ethernet cards parameters
766 This option is obsoleted by the "netdev=" option, which
767 has equivalent usage. See its documentation for details.
769 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
774 fail_make_request=[KNL]
775 General fault injection mechanism.
776 Format: <interval>,<probability>,<space>,<times>
777 See also /Documentation/fault-injection/.
780 See header of drivers/scsi/fd_mcs.c.
783 See header of drivers/scsi/fdomain.c.
786 See Documentation/blockdev/floppy.txt.
788 force_pal_cache_flush
789 [IA-64] Avoid check_sal_cache_flush which may hang on
790 buggy SAL_CACHE_FLUSH implementations. Using this
791 parameter will force ia64_sal_cache_flush to call
792 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
795 [FTRACE] will set and start the specified tracer
796 as early as possible in order to facilitate early
800 [FTRACE] will dump the trace buffers on oops.
802 ftrace_filter=[function-list]
803 [FTRACE] Limit the functions traced by the function
804 tracer at boot up. function-list is a comma separated
805 list of functions. This list can be changed at run
806 time by the set_ftrace_filter file in the debugfs
809 ftrace_notrace=[function-list]
810 [FTRACE] Do not trace the functions specified in
811 function-list. This list can be changed at run time
812 by the set_ftrace_notrace file in the debugfs
815 ftrace_graph_filter=[function-list]
816 [FTRACE] Limit the top level callers functions traced
817 by the function graph tracer at boot up.
818 function-list is a comma separated list of functions
819 that can be changed at run time by the
820 set_graph_function file in the debugfs tracing directory.
823 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
824 support via parallel port (up to 5 devices per port)
825 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
826 See also Documentation/input/joystick-parport.txt
830 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
834 gcov_persist= [GCOV] When non-zero (default), profiling data for
835 kernel modules is saved and remains accessible via
836 debugfs, even when the module is unloaded/reloaded.
837 When zero, profiling data is discarded and associated
838 debugfs files are removed at module unload time.
841 See header of drivers/scsi/gdth.c.
843 gpt [EFI] Forces disk with valid GPT signature but
844 invalid Protective MBR to be treated as GPT.
848 hashdist= [KNL,NUMA] Large hashes allocated during boot
849 are distributed across NUMA nodes. Defaults on
850 for 64bit NUMA, off otherwise.
851 Format: 0 | 1 (for off | on)
853 hcl= [IA-64] SGI's Hardware Graph compatibility layer
855 hd= [EIDE] (E)IDE hard drive subsystem geometry
856 Format: <cyl>,<head>,<sect>
858 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
859 size of <nn>. This works even on boxes that have no
860 highmem otherwise. This also works to reduce highmem
861 size on bigger boxes.
863 highres= [KNL] Enable/disable high resolution timer mode.
864 Valid parameters: "on", "off"
868 See Documentation/isdn/README.HiSax.
872 hpet= [X86-32,HPET] option to control HPET usage
873 Format: { enable (default) | disable | force |
875 disable: disable HPET and use PIT instead
876 force: allow force enabled of undocumented chips (ICH4,
878 verbose: show contents of HPET registers during setup
880 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
881 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
882 On x86-64 and powerpc, this option can be specified
883 multiple times interleaved with hugepages= to reserve
884 huge pages of different sizes. Valid pages sizes on
885 x86-64 are 2M (when the CPU supports "pse") and 1G
886 (when the CPU supports the "pdpe1gb" cpuinfo flag)
887 Note that 1GB pages can only be allocated at boot time
888 using hugepages= and not freed afterwards.
890 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
891 terminal devices. Valid values: 0..8
892 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
893 If specified, z/VM IUCV HVC accepts connections
894 from listed z/VM user IDs only.
896 i2c_bus= [HW] Override the default board specific I2C bus speed
897 or register an additional I2C bus that is not
898 registered from board initialization code.
902 i8042.debug [HW] Toggle i8042 debug mode
903 i8042.direct [HW] Put keyboard port into non-translated mode
904 i8042.dumbkbd [HW] Pretend that controller can only read data from
905 keyboard and cannot control its state
906 (Don't attempt to blink the leds)
907 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
908 i8042.nokbd [HW] Don't check/create keyboard port
909 i8042.noloop [HW] Disable the AUX Loopback command while probing
911 i8042.nomux [HW] Don't check presence of an active multiplexing
913 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
916 [HW] Frequency with which keyboard LEDs should blink
917 when kernel panics (default is 0.5 sec)
918 i8042.reset [HW] Reset the controller during init and cleanup
919 i8042.unlock [HW] Unlock (ignore) the keylock
923 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
924 indicates that the driver is running on unsupported
926 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
927 does not match list of supported models.
929 [HW] Report power status in /proc/i8k
930 (disabled by default)
931 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
934 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
935 See Documentation/mca.txt.
938 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
940 ide-core.nodma= [HW] (E)IDE subsystem
941 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
942 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
943 .cdrom .chs .ignore_cable are additional options
944 See Documentation/ide/ide.txt.
946 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
947 Claim all unknown PCI IDE storage controllers.
950 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
951 Poll forces a polling idle loop that can slightly
952 improve the performance of waking up a idle CPU, but
953 will use a lot of power and make the system run hot.
955 idle=mwait: On systems which support MONITOR/MWAIT but
956 the kernel chose to not use it because it doesn't save
957 as much power as a normal idle loop, use the
958 MONITOR/MWAIT idle loop anyways. Performance should be
959 the same as idle=poll.
960 idle=halt: Halt is forced to be used for CPU idle.
961 In such case C2/C3 won't be used again.
962 idle=nomwait: Disable mwait for CPU C-states
964 ignore_loglevel [KNL]
965 Ignore loglevel setting - this will print /all/
966 kernel messages to the console. Useful for debugging.
969 Set number of hash buckets for inode cache.
972 Format: { "0" | "1" }
973 0 -- integrity auditing messages. (Default)
974 1 -- enable informational integrity auditing messages.
977 Format: { "sha1" | "md5" }
981 Load a policy which meets the needs of the Trusted
982 Computing Base. This means IMA will measure all
983 programs exec'd, files mmap'd for exec, and all files
984 opened for read by uid=0.
987 See header of drivers/scsi/in2000.c.
991 Run specified binary instead of /sbin/init as init
994 initcall_debug [KNL] Trace initcalls as they are executed. Useful
995 for working out where the kernel is dying during
998 initrd= [BOOT] Specify the location of the initial ramdisk
1000 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
1003 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
1005 Enable intel iommu driver.
1007 Disable intel iommu driver.
1008 igfx_off [Default Off]
1009 By default, gfx is mapped as normal device. If a gfx
1010 device has a dedicated DMAR unit, the DMAR unit is
1011 bypassed by not enabling DMAR with this option. In
1012 this case, gfx device will use physical address for
1015 With this option iommu will not optimize to look
1016 for io virtual address below 32 bit forcing dual
1017 address cycle on pci bus for cards supporting greater
1018 than 32 bit addressing. The default is to look
1019 for translation below 32 bit and if not available
1020 then look in the higher range.
1021 strict [Default Off]
1022 With this option on every unmap_single operation will
1023 result in a hardware IOTLB flush operation as opposed
1024 to batching them for performance.
1028 iomem= Disable strict checking of access to MMIO memory
1029 strict regions from userspace.
1045 io7= [HW] IO7 for Marvel based alpha systems
1046 See comment before marvel_specify_io7 in
1047 arch/alpha/kernel/core_marvel.c.
1049 io_delay= [X86] I/O delay method
1051 Standard port 0x80 based delay
1053 Alternate port 0xed based delay (needed on some systems)
1055 Simple two microseconds delay
1060 See Documentation/filesystems/nfs/nfsroot.txt.
1062 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1063 See comment before ip2_setup() in
1064 drivers/char/ip2/ip2base.c.
1066 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1067 See header of drivers/scsi/ips.c.
1070 When an interrupt is not handled search all handlers
1071 for it. Intended to get systems with badly broken
1075 When an interrupt is not handled search all handlers
1076 for it. Also check all handlers each timer
1077 interrupt. Intended to get systems with badly broken
1081 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1083 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1085 <cpu number>,...,<cpu number>
1087 <cpu number>-<cpu number>
1088 (must be a positive range in ascending order)
1090 <cpu number>,...,<cpu number>-<cpu number>
1092 This option can be used to specify one or more CPUs
1093 to isolate from the general SMP balancing and scheduling
1094 algorithms. You can move a process onto or off an
1095 "isolated" CPU via the CPU affinity syscalls or cpuset.
1096 <cpu number> begins at 0 and the maximum value is
1097 "number of CPUs in system - 1".
1099 This option is the preferred way to isolate CPUs. The
1100 alternative -- manually setting the CPU mask of all
1101 tasks in the system -- can cause problems and
1102 suboptimal load balancer performance.
1106 js= [HW,JOY] Analog joystick
1107 See Documentation/input/joystick.txt.
1111 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1112 specifies the amount of memory usable by the kernel
1113 for non-movable allocations. The requested amount is
1114 spread evenly throughout all nodes in the system. The
1115 remaining memory in each node is used for Movable
1116 pages. In the event, a node is too small to have both
1117 kernelcore and Movable pages, kernelcore pages will
1118 take priority and other nodes will have a larger number
1119 of kernelcore pages. The Movable zone is used for the
1120 allocation of pages that may be reclaimed or moved
1121 by the page migration subsystem. This means that
1122 HugeTLB pages may not be allocated from this zone.
1123 Note that allocations like PTEs-from-HighMem still
1124 use the HighMem zone if it exists, and the Normal
1125 zone if it does not.
1127 kgdboc= [HW] kgdb over consoles.
1128 Requires a tty driver that supports console polling.
1129 (only serial supported for now)
1130 Format: <serial_device>[,baud]
1132 kmac= [MIPS] korina ethernet MAC address.
1133 Configure the RouterBoard 532 series on-chip
1134 Ethernet adapter MAC address.
1136 kmemleak= [KNL] Boot-time kmemleak enable/disable
1137 Valid arguments: on, off
1140 kstack=N [X86] Print N words from the kernel stack
1143 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1144 Default is 0 (don't ignore, but inject #GP)
1146 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1147 Default is 1 (enabled)
1149 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1152 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1154 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1156 kvm-intel.bypass_guest_pf=
1157 [KVM,Intel] Disables bypassing of guest page faults
1158 on Intel chips. Default is 1 (enabled)
1160 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1161 (virtualized MMU) support on capable Intel chips.
1162 Default is 1 (enabled)
1164 kvm-intel.emulate_invalid_guest_state=
1165 [KVM,Intel] Enable emulation of invalid guest states
1166 Default is 0 (disabled)
1168 kvm-intel.flexpriority=
1169 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1170 Default is 1 (enabled)
1172 kvm-intel.unrestricted_guest=
1173 [KVM,Intel] Disable unrestricted guest feature
1174 (virtualized real and unpaged mode) on capable
1175 Intel chips. Default is 1 (enabled)
1177 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1178 feature (tagged TLBs) on capable Intel chips.
1179 Default is 1 (enabled)
1185 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1188 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1191 libata.dma= [LIBATA] DMA control
1192 libata.dma=0 Disable all PATA and SATA DMA
1193 libata.dma=1 PATA and SATA Disk DMA only
1194 libata.dma=2 ATAPI (CDROM) DMA only
1195 libata.dma=4 Compact Flash DMA only
1196 Combinations also work, so libata.dma=3 enables DMA
1197 for disks and CDROMs, but not CFs.
1199 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1200 libata.ignore_hpa=0 keep BIOS limits (default)
1201 libata.ignore_hpa=1 ignore limits, using full disk
1203 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1207 libata.force= [LIBATA] Force configurations. The format is comma
1208 separated list of "[ID:]VAL" where ID is
1209 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1210 matching port, link or device. Basically, it matches
1211 the ATA ID string printed on console by libata. If
1212 the whole ID part is omitted, the last PORT and DEVICE
1213 values are used. If ID hasn't been specified yet, the
1214 configuration applies to all ports, links and devices.
1216 If only DEVICE is omitted, the parameter applies to
1217 the port and all links and devices behind it. DEVICE
1218 number of 0 either selects the first device or the
1219 first fan-out link behind PMP device. It does not
1220 select the host link. DEVICE number of 15 selects the
1221 host link and device attached to it.
1223 The VAL specifies the configuration to force. As long
1224 as there's no ambiguity shortcut notation is allowed.
1225 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1226 The following configurations can be forced.
1228 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1229 Any ID with matching PORT is used.
1231 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1233 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1234 udma[/][16,25,33,44,66,100,133] notation is also
1237 * [no]ncq: Turn on or off NCQ.
1239 * nohrst, nosrst, norst: suppress hard, soft
1242 If there are multiple matching configurations changing
1243 the same attribute, the last one is used.
1245 lmb=debug [KNL] Enable lmb debug messages.
1247 load_ramdisk= [RAM] List of ramdisks to load from floppy
1248 See Documentation/blockdev/ramdisk.txt.
1250 lockd.nlm_grace_period=P [NFS] Assign grace period.
1253 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1256 lockd.nlm_timeout=T [NFS] Assign timeout value.
1259 lockd.nlm_udpport=M [NFS] Assign UDP port.
1262 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1265 loglevel= All Kernel Messages with a loglevel smaller than the
1266 console loglevel will be printed to the console. It can
1267 also be changed with klogd or other programs. The
1268 loglevels are defined as follows:
1270 0 (KERN_EMERG) system is unusable
1271 1 (KERN_ALERT) action must be taken immediately
1272 2 (KERN_CRIT) critical conditions
1273 3 (KERN_ERR) error conditions
1274 4 (KERN_WARNING) warning conditions
1275 5 (KERN_NOTICE) normal but significant condition
1276 6 (KERN_INFO) informational
1277 7 (KERN_DEBUG) debug-level messages
1279 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1280 Format: { n | nk | nM }
1281 n must be a power of two. The default size
1282 is set in the kernel config file.
1284 logo.nologo [FB] Disables display of the built-in Linux logo.
1285 This may be used to provide more screen space for
1286 kernel log messages and is useful when debugging
1287 kernel boot problems.
1289 lp=0 [LP] Specify parallel ports to use, e.g,
1290 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1291 lp=reset first parallel port). 'lp=0' disables the
1292 lp=auto printer driver. 'lp=reset' (which can be
1293 specified in addition to the ports) causes
1294 attached printers to be reset. Using
1295 lp=port1,port2,... specifies the parallel ports
1296 to associate lp devices with, starting with
1297 lp0. A port specification may be 'none' to skip
1298 that lp device, or a parport name such as
1299 'parport0'. Specifying 'lp=auto' instead of a
1300 port specification list means that device IDs
1301 from each port should be examined, to see if
1302 an IEEE 1284-compliant printer is attached; if
1303 so, the driver will manage that printer.
1304 See also header of drivers/char/lp.c.
1307 Sets loops_per_jiffy to given constant, thus avoiding
1308 time-consuming boot-time autodetection (up to 250 ms per
1309 CPU). 0 enables autodetection (default). To determine
1310 the correct value for your kernel, boot with normal
1311 autodetection and see what value is printed. Note that
1312 on SMP systems the preset will be applied to all CPUs,
1313 which is likely to cause problems if your CPUs need
1314 significantly divergent settings. An incorrect value
1315 will cause delays in the kernel to be wrong, leading to
1316 unpredictable I/O errors and other breakage. Although
1317 unlikely, in the extreme case this might damage your
1321 Format: <io>,<irq>,<dma>
1323 mac5380= [HW,SCSI] Format:
1324 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1326 machvec= [IA64] Force the use of a particular machine-vector
1327 (machvec) in a generic kernel.
1328 Example: machvec=hpzx1_swiotlb
1330 machtype= [Loongson] Share the same kernel image file between different
1332 Example: machtype=lemote-yeeloong-2f-7inch
1334 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1335 than or equal to this physical address is ignored.
1337 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1338 should make use of. maxcpus=n : n >= 0 limits the
1339 kernel to using 'n' processors. n=0 is a special case,
1340 it is equivalent to "nosmp", which also disables
1343 max_loop= [LOOP] Maximum number of loopback devices that can
1347 max_luns= [SCSI] Maximum number of LUNs to probe.
1348 Should be between 1 and 2^32-1.
1351 [SCSI] Maximum number of LUNs received.
1352 Should be between 1 and 16384.
1356 mce [X86-32] Machine Check Exception
1358 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1360 md= [HW] RAID subsystems devices and level
1361 See Documentation/md.txt.
1364 Format: <first>,<last>
1365 Specifies range of consoles to be captured by the MDA.
1367 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1368 Amount of memory to be used when the kernel is not able
1369 to see the whole system memory or for test.
1370 [X86-32] Use together with memmap= to avoid physical
1371 address space collisions. Without memmap= PCI devices
1372 could be placed at addresses belonging to unused RAM.
1374 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1378 [KNL,SH] Allow user to override the default size for
1379 per-device physically contiguous DMA buffers.
1381 memmap=exactmap [KNL,X86] Enable setting of an exact
1382 E820 memory map, as specified by the user.
1383 Such memmap=exactmap lines can be constructed based on
1384 BIOS output or other requirements. See the memmap=nn@ss
1387 memmap=nn[KMG]@ss[KMG]
1388 [KNL] Force usage of a specific region of memory
1389 Region of memory to be used, from ss to ss+nn.
1391 memmap=nn[KMG]#ss[KMG]
1392 [KNL,ACPI] Mark specific memory as ACPI data.
1393 Region of memory to be used, from ss to ss+nn.
1395 memmap=nn[KMG]$ss[KMG]
1396 [KNL,ACPI] Mark specific memory as reserved.
1397 Region of memory to be used, from ss to ss+nn.
1398 Example: Exclude memory from 0x18690000-0x1869ffff
1399 memmap=64K$0x18690000
1401 memmap=0x10000$0x18690000
1403 memory_corruption_check=0/1 [X86]
1404 Some BIOSes seem to corrupt the first 64k of
1405 memory when doing things like suspend/resume.
1406 Setting this option will scan the memory
1407 looking for corruption. Enabling this will
1408 both detect corruption and prevent the kernel
1409 from using the memory being corrupted.
1410 However, its intended as a diagnostic tool; if
1411 repeatable BIOS-originated corruption always
1412 affects the same memory, you can use memmap=
1413 to prevent the kernel from using that memory.
1415 memory_corruption_check_size=size [X86]
1416 By default it checks for corruption in the low
1417 64k, making this memory unavailable for normal
1418 use. Use this parameter to scan for
1419 corruption in more or less memory.
1421 memory_corruption_check_period=seconds [X86]
1422 By default it checks for corruption every 60
1423 seconds. Use this parameter to check at some
1424 other rate. 0 disables periodic checking.
1426 memtest= [KNL,X86] Enable memtest
1428 default : 0 <disable>
1429 Specifies the number of memtest passes to be
1430 performed. Each pass selects another test
1431 pattern from a given set of patterns. Memtest
1432 fills the memory with this pattern, validates
1433 memory contents and reserves bad memory
1434 regions that are detected.
1436 meye.*= [HW] Set MotionEye Camera parameters
1437 See Documentation/video4linux/meye.txt.
1439 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1440 Multi-Function General Purpose Timers on AMD Geode
1443 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1444 the BIOS has incorrectly applied a workaround. TinyBIOS
1445 version 0.98 is known to be affected, 0.99 fixes the
1446 problem by letting the user disable the workaround.
1450 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1451 physical address is ignored.
1453 mini2440= [ARM,HW,KNL]
1454 Format:[0..2][b][c][t]
1456 MINI2440 configuration specification:
1457 0 - The attached screen is the 3.5" TFT
1458 1 - The attached screen is the 7" TFT
1459 2 - The VGA Shield is attached (1024x768)
1460 Leaving out the screen size parameter will not load
1461 the TFT driver, and the framebuffer will be left
1463 b - Enable backlight. The TFT backlight pin will be
1464 linked to the kernel VESA blanking code and a GPIO
1465 LED. This parameter is not necessary when using the
1467 c - Enable the s3c camera interface.
1468 t - Reserved for enabling touchscreen support. The
1469 touchscreen support is not enabled in the mainstream
1470 kernel as of 2.6.30, a preliminary port can be found
1471 in the "bleeding edge" mini2440 support kernel at
1472 http://repo.or.cz/w/linux-2.6/mini2440.git
1475 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1476 parameter allows control of the logging verbosity for
1477 the additional memory initialisation checks. A value
1478 of 0 disables mminit logging and a level of 4 will
1479 log everything. Information is printed at KERN_DEBUG
1480 so loglevel=8 may also need to be specified.
1483 [MOUSE] Maximum time between finger touching and
1484 leaving touchpad surface for touch to be considered
1485 a tap and be reported as a left button click (for
1486 touchpads working in absolute mode only).
1488 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1489 reporting absolute coordinates, such as tablets
1490 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1491 reporting absolute coordinates, such as tablets
1493 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1494 is similar to kernelcore except it specifies the
1495 amount of memory used for migratable allocations.
1496 If both kernelcore and movablecore is specified,
1497 then kernelcore will be at *least* the specified
1498 value but may be more. If movablecore on its own
1499 is specified, the administrator must be careful
1500 that the amount of memory usable for all allocations
1506 MTD_Partition= [MTD]
1507 Format: <name>,<region-number>,<size>,<offset>
1509 MTD_Region= [MTD] Format:
1510 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1513 See drivers/mtd/cmdlinepart.c.
1515 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1517 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1519 boundary - index of last SLC block on Flex-OneNAND.
1520 The remaining blocks are configured as MLC blocks.
1521 lock - Configure if Flex-OneNAND boundary should be locked.
1522 Once locked, the boundary cannot be changed.
1523 1 indicates lock status, 0 indicates unlock status.
1526 ARM/S3C2412 JIVE boot control
1528 See arch/arm/mach-s3c2412/mach-jive.c
1530 mtouchusb.raw_coordinates=
1531 [HW] Make the MicroTouch USB driver use raw coordinates
1532 ('y', default) or cooked coordinates ('n')
1534 mtrr_chunk_size=nn[KMG] [X86]
1535 used for mtrr cleanup. It is largest continuous chunk
1536 that could hold holes aka. UC entries.
1538 mtrr_gran_size=nn[KMG] [X86]
1539 Used for mtrr cleanup. It is granularity of mtrr block.
1541 Large value could prevent small alignment from
1544 mtrr_spare_reg_nr=n [X86]
1546 Range: 0,7 : spare reg number
1548 Used for mtrr cleanup. It is spare mtrr entries number.
1549 Set to 2 or more if your graphical card needs more.
1551 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1554 See header of drivers/scsi/NCR_D700.c.
1558 ncr53c400= [HW,SCSI]
1560 ncr53c400a= [HW,SCSI]
1562 ncr53c406a= [HW,SCSI]
1564 ncr53c8xx= [HW,SCSI]
1566 netdev= [NET] Network devices parameters
1567 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1568 Note that mem_start is often overloaded to mean
1569 something different and driver-specific.
1570 This usage is only documented in each driver source
1574 [NETFILTER] Enable connection tracking flow accounting
1575 0 to disable accounting
1576 1 to enable accounting
1577 Default value depends on CONFIG_NF_CT_ACCT.
1580 See Documentation/filesystems/nfs/nfsroot.txt.
1582 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1583 See Documentation/filesystems/nfs/nfsroot.txt.
1585 nfs.callback_tcpport=
1586 [NFS] set the TCP port on which the NFSv4 callback
1587 channel should listen.
1590 [NFS] sets the pathname to the program which is used
1591 to update the NFS client cache entries.
1593 nfs.cache_getent_timeout=
1594 [NFS] sets the timeout after which an attempt to
1595 update a cache entry is deemed to have failed.
1597 nfs.idmap_cache_timeout=
1598 [NFS] set the maximum lifetime for idmapper cache
1602 [NFS] enable 64-bit inode numbers.
1603 If zero, the NFS client will fake up a 32-bit inode
1604 number for the readdir() and stat() syscalls instead
1605 of returning the full 64-bit number.
1606 The default is to return 64-bit inode numbers.
1608 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1609 when a NMI is triggered.
1610 Format: [state][,regs][,debounce][,die]
1612 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1613 Format: [panic,][num]
1615 0 - turn nmi_watchdog off
1616 1 - use the IO-APIC timer for the NMI watchdog
1617 2 - use the local APIC for the NMI watchdog using
1618 a performance counter. Note: This will use one
1619 performance counter and the local APIC's performance
1621 When panic is specified, panic when an NMI watchdog
1623 This is useful when you use a panic=... timeout and
1624 need the box quickly up again.
1625 Instead of 1 and 2 it is possible to use the following
1626 symbolic names: lapic and ioapic
1627 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1629 netpoll.carrier_timeout=
1630 [NET] Specifies amount of time (in seconds) that
1631 netpoll should wait for a carrier. By default netpoll
1634 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1635 emulation library even if a 387 maths coprocessor
1639 [HW] Never suspend the console
1640 Disable suspending of consoles during suspend and
1641 hibernate operations. Once disabled, debugging
1642 messages can reach various consoles while the rest
1643 of the system is being put to sleep (ie, while
1644 debugging driver suspend/resume hooks). This may
1645 not work reliably with all consoles, but is known
1646 to work with serial and VGA consoles.
1648 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1649 caches in the slab allocator. Saves per-node memory,
1650 but will impact performance.
1654 noapic [SMP,APIC] Tells the kernel to not make use of any
1655 IOAPICs that may be present in the system.
1657 nobats [PPC] Do not use BATs for mapping kernel lowmem
1658 on "Classic" PPC cores.
1662 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1664 nodelayacct [KNL] Disable per-task delay accounting
1666 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1668 nodsp [SH] Disable hardware DSP at boot time.
1670 noefi [X86] Disable EFI runtime services support.
1675 On X86-32 available only on PAE configured kernels.
1676 noexec=on: enable non-executable mappings (default)
1677 noexec=off: disable non-executable mappings
1680 This affects only 32-bit executables.
1681 noexec32=on: enable non-executable mappings (default)
1682 read doesn't imply executable mappings
1683 noexec32=off: disable non-executable mappings
1684 read implies executable mappings
1686 nofpu [SH] Disable hardware FPU at boot time.
1688 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1689 register save and restore. The kernel will only save
1690 legacy floating-point registers on task switch.
1692 noxsave [BUGS=X86] Disables x86 extended register state save
1693 and restore using xsave. The kernel will fallback to
1694 enabling legacy floating-point and sse state.
1696 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1697 wfi(ARM) instruction doesn't work correctly and not to
1698 use it. This is also useful when using JTAG debugger.
1700 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1701 instruction doesn't work correctly and not to
1704 no_file_caps Tells the kernel not to honor file capabilities. The
1705 only way then for a file to be executed with privilege
1706 is to be setuid root or executed by root. They
1707 default to disabled.
1709 file_caps Tells the kernel to honor file capabilities. The
1710 only way then for a file to be executed with privilege
1711 is to be setuid root or executed by root. They default
1714 nohalt [IA-64] Tells the kernel not to use the power saving
1715 function PAL_HALT_LIGHT when idle. This increases
1716 power-consumption. On the positive side, it reduces
1717 interrupt wake-up latency, which may improve performance
1718 in certain environments such as networked servers or
1721 nohz= [KNL] Boottime enable/disable dynamic ticks
1722 Valid arguments: on, off
1725 noiotrap [SH] Disables trapped I/O port accesses.
1727 noirqdebug [X86-32] Disables the code which attempts to detect and
1728 disable unhandled interrupt sources.
1730 no_timer_check [X86,APIC] Disables the code which tests for
1731 broken timer IRQ sources.
1733 noisapnp [ISAPNP] Disables ISA PnP code.
1735 noinitrd [RAM] Tells the kernel not to load any configured
1738 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1743 nojitter [IA64] Disables jitter checking for ITC timers.
1745 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1747 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1749 noltlbs [PPC] Do not use large page/tlb entries for kernel
1750 lowmem mapping on PPC40x.
1752 nomca [IA-64] Disable machine check abort handling
1754 nomce [X86-32] Machine Check Exception
1756 nomfgpt [X86-32] Disable Multi-Function General Purpose
1757 Timer usage (for AMD Geode machines).
1759 nopat [X86] Disable PAT (page attribute table extension of
1760 pagetables) support.
1762 norandmaps Don't use address space randomization. Equivalent to
1763 echo 0 > /proc/sys/kernel/randomize_va_space
1765 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1767 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1768 with UP alternatives
1770 noresidual [PPC] Don't use residual data on PReP machines.
1772 noresume [SWSUSP] Disables resume and restores original swap
1775 no-scroll [VGA] Disables scrollback.
1776 This is required for the Braillex ib80-piezo Braille
1777 reader made by F.H. Papenmeier (Germany).
1781 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1783 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1784 and disable the IO APIC. legacy for "maxcpus=0".
1786 nosoftlockup [KNL] Disable the soft-lockup detector.
1788 noswapaccount [KNL] Disable accounting of swap in memory resource
1789 controller. (See Documentation/cgroups/memory.txt)
1791 nosync [HW,M68K] Disables sync negotiation for all devices.
1793 notsc [BUGS=X86-32] Disable Time Stamp Counter
1795 nousb [USB] Disable the USB subsystem
1799 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1801 nptcg= [IA64] Override max number of concurrent global TLB
1802 purges which is reported from either PAL_VM_SUMMARY or
1805 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1806 could support. nr_cpus=n : n >= 1 limits the kernel to
1807 supporting 'n' processors. Later in runtime you can not
1808 use hotplug cpu feature to put more cpu back to online.
1809 just like you compile the kernel NR_CPUS=n
1811 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1813 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1814 one of ['zone', 'node', 'default'] can be specified
1815 This can be set from sysctl after boot.
1816 See Documentation/sysctl/vm.txt for details.
1818 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1819 See Documentation/debugging-via-ohci1394.txt for more
1822 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1823 Rather than timing out after 20 ms if an EC
1824 command is not properly ACKed, override the length
1825 of the timeout. We have interrupts disabled while
1826 waiting for the ACK, so if this is set too high
1827 interrupts *may* be lost!
1829 omap_mux= [OMAP] Override bootloader pin multiplexing.
1830 Format: <mux_mode0.mode_name=value>...
1831 For example, to override I2C bus2:
1832 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1837 oprofile.timer= [HW]
1838 Use timer interrupt instead of performance counters
1840 oprofile.cpu_type= Force an oprofile cpu type
1841 This might be useful if you have an older oprofile
1842 userland or if you want common events.
1843 Format: { arch_perfmon }
1844 arch_perfmon: [X86] Force use of architectural
1845 perfmon on Intel CPUs instead of the
1846 CPU specific event set.
1848 osst= [HW,SCSI] SCSI Tape Driver
1849 Format: <buffer_size>,<write_threshold>
1850 See also Documentation/scsi/st.txt.
1852 panic= [KNL] Kernel behaviour on panic
1855 parkbd.port= [HW] Parallel port number the keyboard adapter is
1856 connected to, default is 0.
1858 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1859 0 for XT, 1 for AT (default is AT).
1862 parport= [HW,PPT] Specify parallel ports. 0 disables.
1863 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1864 Use 'auto' to force the driver to use any
1865 IRQ/DMA settings detected (the default is to
1866 ignore detected IRQ/DMA settings because of
1867 possible conflicts). You can specify the base
1868 address, IRQ, and DMA settings; IRQ and DMA
1869 should be numbers, or 'auto' (for using detected
1870 settings on that particular port), or 'nofifo'
1871 (to avoid using a FIFO even if it is detected).
1872 Parallel ports are assigned in the order they
1873 are specified on the command line, starting
1876 parport_init_mode= [HW,PPT]
1877 Configure VIA parallel port to operate in
1878 a specific mode. This is necessary on Pegasos
1879 computer where firmware has no options for setting
1880 up parallel port mode and sets it to spp.
1881 Currently this function knows 686a and 8231 chips.
1882 Format: [spp|ps2|epp|ecp|ecpepp]
1884 pas2= [HW,OSS] Format:
1885 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1888 See header of drivers/scsi/pas16.c.
1891 Halt all CPUs after the first oops has been printed for
1892 the specified number of seconds. This is to be used if
1893 your oopses keep scrolling off the screen.
1898 See header of drivers/block/paride/pcd.c.
1899 See also Documentation/blockdev/paride.txt.
1901 pci=option[,option...] [PCI] various PCI subsystem options:
1902 earlydump [X86] dump PCI config space before the kernel
1904 off [X86] don't probe for the PCI bus
1905 bios [X86-32] force use of PCI BIOS, don't access
1906 the hardware directly. Use this if your machine
1907 has a non-standard PCI host bridge.
1908 nobios [X86-32] disallow use of PCI BIOS, only direct
1909 hardware access methods are allowed. Use this
1910 if you experience crashes upon bootup and you
1911 suspect they are caused by the BIOS.
1912 conf1 [X86] Force use of PCI Configuration
1914 conf2 [X86] Force use of PCI Configuration
1916 noaer [PCIE] If the PCIEAER kernel config parameter is
1917 enabled, this kernel boot option can be used to
1918 disable the use of PCIE advanced error reporting.
1919 nodomains [PCI] Disable support for multiple PCI
1920 root domains (aka PCI segments, in ACPI-speak).
1921 nommconf [X86] Disable use of MMCONFIG for PCI
1923 check_enable_amd_mmconf [X86] check for and enable
1924 properly configured MMIO access to PCI
1925 config space on AMD family 10h CPU
1926 nomsi [MSI] If the PCI_MSI kernel config parameter is
1927 enabled, this kernel boot option can be used to
1928 disable the use of MSI interrupts system-wide.
1929 noioapicquirk [APIC] Disable all boot interrupt quirks.
1930 Safety option to keep boot IRQs enabled. This
1931 should never be necessary.
1932 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1933 primary IO-APIC for bridges that cannot disable
1934 boot IRQs. This fixes a source of spurious IRQs
1935 when the system masks IRQs.
1936 noioapicreroute [APIC] Disable workaround that uses the
1937 boot IRQ equivalent of an IRQ that connects to
1938 a chipset where boot IRQs cannot be disabled.
1939 The opposite of ioapicreroute.
1940 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1941 routing table. These calls are known to be buggy
1942 on several machines and they hang the machine
1943 when used, but on other computers it's the only
1944 way to get the interrupt routing table. Try
1945 this option if the kernel is unable to allocate
1946 IRQs or discover secondary PCI buses on your
1948 rom [X86] Assign address space to expansion ROMs.
1949 Use with caution as certain devices share
1950 address decoders between ROMs and other
1952 norom [X86] Do not assign address space to
1953 expansion ROMs that do not already have
1954 BIOS assigned address ranges.
1955 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1956 assigned automatically to PCI devices. You can
1957 make the kernel exclude IRQs of your ISA cards
1959 pirqaddr=0xAAAAA [X86] Specify the physical address
1960 of the PIRQ table (normally generated
1961 by the BIOS) if it is outside the
1962 F0000h-100000h range.
1963 lastbus=N [X86] Scan all buses thru bus #N. Can be
1964 useful if the kernel is unable to find your
1965 secondary buses and you want to tell it
1966 explicitly which ones they are.
1967 assign-busses [X86] Always assign all PCI bus
1968 numbers ourselves, overriding
1969 whatever the firmware may have done.
1970 usepirqmask [X86] Honor the possible IRQ mask stored
1971 in the BIOS $PIR table. This is needed on
1972 some systems with broken BIOSes, notably
1973 some HP Pavilion N5400 and Omnibook XE3
1974 notebooks. This will have no effect if ACPI
1975 IRQ routing is enabled.
1976 noacpi [X86] Do not use ACPI for IRQ routing
1977 or for PCI scanning.
1978 use_crs [X86] Use PCI host bridge window information
1979 from ACPI. On BIOSes from 2008 or later, this
1980 is enabled by default. If you need to use this,
1981 please report a bug.
1982 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1983 If you need to use this, please report a bug.
1984 routeirq Do IRQ routing for all PCI devices.
1985 This is normally done in pci_enable_device(),
1986 so this option is a temporary workaround
1987 for broken drivers that don't call it.
1988 skip_isa_align [X86] do not align io start addr, so can
1989 handle more pci cards
1990 firmware [ARM] Do not re-enumerate the bus but instead
1991 just use the configuration from the
1992 bootloader. This is currently used on
1993 IXP2000 systems where the bus has to be
1994 configured a certain way for adjunct CPUs.
1995 noearly [X86] Don't do any early type 1 scanning.
1996 This might help on some broken boards which
1997 machine check when some devices' config space
1998 is read. But various workarounds are disabled
1999 and some IOMMU drivers will not work.
2000 bfsort Sort PCI devices into breadth-first order.
2001 This sorting is done to get a device
2002 order compatible with older (<= 2.4) kernels.
2003 nobfsort Don't sort PCI devices into breadth-first order.
2004 cbiosize=nn[KMG] The fixed amount of bus space which is
2005 reserved for the CardBus bridge's IO window.
2006 The default value is 256 bytes.
2007 cbmemsize=nn[KMG] The fixed amount of bus space which is
2008 reserved for the CardBus bridge's memory
2009 window. The default value is 64 megabytes.
2012 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2013 Specifies alignment and device to reassign
2014 aligned memory resources.
2015 If <order of align> is not specified,
2016 PAGE_SIZE is used as alignment.
2017 PCI-PCI bridge can be specified, if resource
2018 windows need to be expanded.
2019 ecrc= Enable/disable PCIe ECRC (transaction layer
2020 end-to-end CRC checking).
2021 bios: Use BIOS/firmware settings. This is the
2026 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2029 force Enable ASPM even on devices that claim not to support it.
2030 WARNING: Forcing ASPM on may cause system lockups.
2032 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2033 off Do not use native PCIe PME signaling.
2034 force Use native PCIe PME signaling even if the BIOS refuses
2035 to allow the kernel to control the relevant PCIe config
2037 nomsi Do not use MSI for native PCIe PME signaling (this makes
2038 all PCIe root ports use INTx for everything).
2040 pcmv= [HW,PCMCIA] BadgePAD 4
2043 See Documentation/blockdev/paride.txt.
2045 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2048 See arch/parisc/kernel/pdc_chassis.c
2050 percpu_alloc= Select which percpu first chunk allocator to use.
2051 Currently supported values are "embed" and "page".
2052 Archs may support subset or none of the selections.
2053 See comments in mm/percpu.c for details on each
2054 allocator. This parameter is primarily for debugging
2055 and performance comparison.
2058 See Documentation/blockdev/paride.txt.
2061 See Documentation/blockdev/paride.txt.
2063 pirq= [SMP,APIC] Manual mp-table setup
2064 See Documentation/x86/i386/IO-APIC.txt.
2066 plip= [PPT,NET] Parallel port network link
2067 Format: { parport<nr> | timid | 0 }
2068 See also Documentation/parport.txt.
2070 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2071 Override pmtimer IOPort with a hex value.
2075 Enable PNP debug messages. This depends on the
2076 CONFIG_PNP_DEBUG_MESSAGES option.
2082 { on | off | curr | res | no-curr | no-res }
2085 [ISAPNP] Exclude IRQs for the autoconfiguration
2088 [ISAPNP] Exclude DMAs for the autoconfiguration
2090 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2091 Ranges are in pairs (I/O port base and size).
2094 [ISAPNP] Exclude memory regions for the
2096 Ranges are in pairs (memory base and size).
2098 ports= [IP_VS_FTP] IPVS ftp helper module
2100 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2102 Format: <port>,<port>....
2104 print-fatal-signals=
2105 [KNL] debug: print fatal signals
2107 If enabled, warn about various signal handling
2108 related application anomalies: too many signals,
2109 too many POSIX.1 timers, fatal signals causing a
2112 If you hit the warning due to signal overflow,
2113 you might want to try "ulimit -i unlimited".
2117 printk.time= Show timing data prefixed to each printk message line
2118 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2120 processor.max_cstate= [HW,ACPI]
2121 Limit processor to maximum C-state
2122 max_cstate=9 overrides any DMI blacklist limit.
2124 processor.nocst [HW,ACPI]
2125 Ignore the _CST method to determine C-states,
2126 instead using the legacy FADT method
2128 profile= [KNL] Enable kernel profiling via /proc/profile
2129 Format: [schedule,]<number>
2130 Param: "schedule" - profile schedule points.
2131 Param: <number> - step/bucket size as a power of 2 for
2132 statistical time based profiling.
2133 Param: "sleep" - profile D-state sleeping (millisecs).
2134 Requires CONFIG_SCHEDSTATS
2135 Param: "kvm" - profile VM exits.
2137 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2139 See Documentation/blockdev/ramdisk.txt.
2141 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2142 probe for; one of (bare|imps|exps|lifebook|any).
2143 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2145 psmouse.resetafter= [HW,MOUSE]
2146 Try to reset the device after so many bad packets
2149 [HW,MOUSE] Set desired mouse resolution, in dpi.
2150 psmouse.smartscroll=
2151 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2152 0 = disabled, 1 = enabled (default).
2154 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2156 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2159 See Documentation/blockdev/paride.txt.
2162 [KNL] Number of legacy pty's. Overwrites compiled-in
2165 quiet [KNL] Disable most log messages
2170 See Documentation/md.txt.
2172 ramdisk_blocksize= [RAM]
2173 See Documentation/blockdev/ramdisk.txt.
2175 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2176 See Documentation/blockdev/ramdisk.txt.
2178 rcupdate.blimit= [KNL,BOOT]
2179 Set maximum number of finished RCU callbacks to process
2182 rcupdate.qhimark= [KNL,BOOT]
2183 Set threshold of queued
2184 RCU callbacks over which batch limiting is disabled.
2186 rcupdate.qlowmark= [KNL,BOOT]
2187 Set threshold of queued RCU callbacks below which
2188 batch limiting is re-enabled.
2192 Run specified binary instead of /init from the ramdisk,
2193 used for early userspace startup. See initrd.
2195 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2196 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2197 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2200 [KNL, SMP] Set scheduler's default relax_domain_level.
2201 See Documentation/cgroups/cpusets.txt.
2203 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2205 reservetop= [X86-32]
2207 Reserves a hole at the top of the kernel virtual
2210 reset_devices [KNL] Force drivers to reset the underlying device
2211 during initialization.
2214 Specify the partition device for software suspend
2216 resume_offset= [SWSUSP]
2217 Specify the offset from the beginning of the partition
2218 given by "resume=" at which the swap header is located,
2219 in <PAGE_SIZE> units (needed only for swap files).
2220 See Documentation/power/swsusp-and-swap-files.txt
2222 retain_initrd [RAM] Keep initrd memory after extraction
2224 rhash_entries= [KNL,NET]
2225 Set number of hash buckets for route cache
2227 riscom8= [HW,SERIAL]
2228 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2230 ro [KNL] Mount root device read-only on boot
2232 root= [KNL] Root filesystem
2234 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2235 mount the root filesystem
2237 rootflags= [KNL] Set root filesystem mount option string
2239 rootfstype= [KNL] Set root filesystem type
2241 rootwait [KNL] Wait (indefinitely) for root device to show up.
2242 Useful for devices that are detected asynchronously
2243 (e.g. USB and MMC devices).
2245 rw [KNL] Mount root device read-write on boot
2247 S [KNL] Run init in single mode
2250 See drivers/net/irda/sa1100_ir.c.
2252 sbni= [NET] Granch SBNI12 leased line adapter
2254 sched_debug [KNL] Enables verbose scheduler debug messages.
2256 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2257 Format: <io>[,<timeout>[,<isapnp>]]
2259 scsi_debug_*= [SCSI]
2260 See drivers/scsi/scsi_debug.c.
2262 scsi_default_dev_flags=
2263 [SCSI] SCSI default device flags
2266 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2267 Format: <vendor>:<model>:<flags>
2268 (flags are integer value)
2270 scsi_logging_level= [SCSI] a bit mask of logging levels
2271 See drivers/scsi/scsi_logging.h for bits. Also
2272 settable via sysctl at dev.scsi.logging_level
2273 (/proc/sys/dev/scsi/logging_level).
2274 There is also a nice 'scsi_logging_level' script in the
2275 S390-tools package, available for download at
2276 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2278 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2279 discovered. async scans them in kernel threads,
2280 allowing boot to proceed. none ignores them, expecting
2281 user space to do the scan.
2283 security= [SECURITY] Choose a security module to enable at boot.
2284 If this boot parameter is not specified, only the first
2285 security module asking for security registration will be
2286 loaded. An invalid security module name will be treated
2287 as if no module has been chosen.
2289 selinux= [SELINUX] Disable or enable SELinux at boot time.
2290 Format: { "0" | "1" }
2291 See security/selinux/Kconfig help text.
2294 Default value is set via kernel config option.
2295 If enabled at boot time, /selinux/disable can be used
2296 later to disable prior to initial policy load.
2298 serialnumber [BUGS=X86-32]
2301 Maximal number of shapers.
2303 show_msr= [x86] show boot-time MSR settings
2304 Format: { <integer> }
2305 Show boot-time (BIOS-initialized) MSR settings.
2306 The parameter means the number of CPUs to show,
2307 for example 1 means boot CPU only.
2310 See header of drivers/scsi/sim710.c.
2317 slub_debug[=options[,slabs]] [MM, SLUB]
2318 Enabling slub_debug allows one to determine the
2319 culprit if slab objects become corrupted. Enabling
2320 slub_debug can create guard zones around objects and
2321 may poison objects when not in use. Also tracks the
2322 last alloc / free. For more information see
2323 Documentation/vm/slub.txt.
2325 slub_max_order= [MM, SLUB]
2326 Determines the maximum allowed order for slabs.
2327 A high setting may cause OOMs due to memory
2328 fragmentation. For more information see
2329 Documentation/vm/slub.txt.
2331 slub_min_objects= [MM, SLUB]
2332 The minimum number of objects per slab. SLUB will
2333 increase the slab order up to slub_max_order to
2334 generate a sufficiently large slab able to contain
2335 the number of objects indicated. The higher the number
2336 of objects the smaller the overhead of tracking slabs
2337 and the less frequently locks need to be acquired.
2338 For more information see Documentation/vm/slub.txt.
2340 slub_min_order= [MM, SLUB]
2341 Determines the mininum page order for slabs. Must be
2342 lower than slub_max_order.
2343 For more information see Documentation/vm/slub.txt.
2345 slub_nomerge [MM, SLUB]
2346 Disable merging of slabs with similar size. May be
2347 necessary if there is some reason to distinguish
2348 allocs to different slabs. Debug options disable
2349 merging on their own.
2350 For more information see Documentation/vm/slub.txt.
2353 Format: <io1>[,<io2>[,...,<io8>]]
2355 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2356 attempt to substitute SMP alternatives once at boot.
2358 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2359 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2360 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2361 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2362 smsc-ircc2.ircc_irq= [HW] IRQ line
2363 smsc-ircc2.ircc_dma= [HW] DMA channel
2364 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2365 0: Toshiba Satellite 1800 (GP data pin select)
2366 1: Fast pin select (default)
2369 snd-ad1816a= [HW,ALSA]
2371 snd-ad1848= [HW,ALSA]
2373 snd-ali5451= [HW,ALSA]
2375 snd-als100= [HW,ALSA]
2377 snd-als4000= [HW,ALSA]
2379 snd-azt2320= [HW,ALSA]
2381 snd-cmi8330= [HW,ALSA]
2383 snd-cmipci= [HW,ALSA]
2385 snd-cs4231= [HW,ALSA]
2387 snd-cs4232= [HW,ALSA]
2389 snd-cs4236= [HW,ALSA]
2391 snd-cs4281= [HW,ALSA]
2393 snd-cs46xx= [HW,ALSA]
2395 snd-dt019x= [HW,ALSA]
2397 snd-dummy= [HW,ALSA]
2399 snd-emu10k1= [HW,ALSA]
2401 snd-ens1370= [HW,ALSA]
2403 snd-ens1371= [HW,ALSA]
2405 snd-es968= [HW,ALSA]
2407 snd-es1688= [HW,ALSA]
2409 snd-es18xx= [HW,ALSA]
2411 snd-es1938= [HW,ALSA]
2413 snd-es1968= [HW,ALSA]
2415 snd-fm801= [HW,ALSA]
2417 snd-gusclassic= [HW,ALSA]
2419 snd-gusextreme= [HW,ALSA]
2421 snd-gusmax= [HW,ALSA]
2425 snd-ice1712= [HW,ALSA]
2427 snd-intel8x0= [HW,ALSA]
2429 snd-interwave= [HW,ALSA]
2434 snd-korg1212= [HW,ALSA]
2436 snd-maestro3= [HW,ALSA]
2438 snd-mpu401= [HW,ALSA]
2440 snd-mtpav= [HW,ALSA]
2442 snd-nm256= [HW,ALSA]
2444 snd-opl3sa2= [HW,ALSA]
2452 snd-opti93x= [HW,ALSA]
2456 snd-rme32= [HW,ALSA]
2458 snd-rme96= [HW,ALSA]
2460 snd-rme9652= [HW,ALSA]
2466 snd-sbawe= [HW,ALSA]
2468 snd-serial= [HW,ALSA]
2470 snd-sgalaxy= [HW,ALSA]
2472 snd-sonicvibes= [HW,ALSA]
2477 snd-sun-cs4231= [HW,ALSA]
2479 snd-trident= [HW,ALSA]
2481 snd-usb-audio= [HW,ALSA,USB]
2483 snd-via82xx= [HW,ALSA]
2485 snd-virmidi= [HW,ALSA]
2487 snd-wavefront= [HW,ALSA]
2489 snd-ymfpci= [HW,ALSA]
2492 [KNL] Should the soft-lockup detector generate panics.
2494 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2495 See Documentation/sonypi.txt
2497 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2498 See Documentation/serial/specialix.txt.
2500 spia_io_base= [HW,MTD]
2506 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2508 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2509 See Documentation/scsi/st.txt.
2512 Enabled the stack tracer on boot up.
2516 Set the STI (builtin display/keyboard on the HP-PARISC
2517 machines) console (graphic card) which should be used
2518 as the initial boot-console.
2519 See also comment in drivers/video/console/sticore.c.
2522 See comment in drivers/video/console/sticore.c.
2525 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2527 sunrpc.min_resvport=
2528 sunrpc.max_resvport=
2530 SunRPC servers often require that client requests
2531 originate from a privileged port (i.e. a port in the
2532 range 0 < portnr < 1024).
2533 An administrator who wishes to reserve some of these
2534 ports for other uses may adjust the range that the
2535 kernel's sunrpc client considers to be privileged
2536 using these two parameters to set the minimum and
2537 maximum port values.
2541 Control how the NFS server code allocates CPUs to
2542 service thread pools. Depending on how many NICs
2543 you have and where their interrupts are bound, this
2544 option will affect which CPUs will do NFS serving.
2545 Note: this parameter cannot be changed while the
2546 NFS server is running.
2548 auto the server chooses an appropriate mode
2549 automatically using heuristics
2550 global a single global pool contains all CPUs
2551 percpu one pool for each CPU
2552 pernode one pool for each NUMA node (equivalent
2553 to global on non-NUMA machines)
2555 sunrpc.tcp_slot_table_entries=
2556 sunrpc.udp_slot_table_entries=
2558 Sets the upper limit on the number of simultaneous
2559 RPC calls that can be sent from the client to a
2560 server. Increasing these values may allow you to
2561 improve throughput, but will also increase the
2562 amount of memory reserved for use by the client.
2564 unsupported Allow loading of unsupported kernel modules:
2565 0 = only allow supported modules,
2566 1 = warn when loading unsupported modules,
2569 CONFIG_ENTERPRISE_SUPPORT must be enabled for this
2572 swiotlb= [IA-64] Number of I/O TLB slabs
2576 sym53c416= [HW,SCSI]
2577 See header of drivers/scsi/sym53c416.c.
2579 sysrq_always_enabled
2581 Ignore sysrq setting - this boot parameter will
2582 neutralize any effect of /proc/sys/kernel/sysrq.
2583 Useful for debugging.
2586 See header of drivers/scsi/t128.c.
2590 test_suspend= [SUSPEND]
2591 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2592 standby suspend) as the system sleep state to briefly
2593 enter during system startup. The system is woken from
2594 this state using a wakeup-capable RTC alarm.
2596 thash_entries= [KNL,NET]
2597 Set number of hash buckets for TCP connection
2599 thermal.act= [HW,ACPI]
2600 -1: disable all active trip points in all thermal zones
2601 <degrees C>: override all lowest active trip points
2603 thermal.crt= [HW,ACPI]
2604 -1: disable all critical trip points in all thermal zones
2605 <degrees C>: override all critical trip points
2607 thermal.nocrt= [HW,ACPI]
2608 Set to disable actions on ACPI thermal zone
2609 critical and hot trip points.
2611 thermal.off= [HW,ACPI]
2612 1: disable ACPI thermal control
2614 thermal.psv= [HW,ACPI]
2615 -1: disable all passive trip points
2616 <degrees C>: override all passive trip points to this
2619 thermal.tzp= [HW,ACPI]
2620 Specify global default ACPI thermal zone polling rate
2621 <deci-seconds>: poll all this frequency
2622 0: no polling (default)
2625 See comment before function dc390_setup() in
2626 drivers/scsi/tmscsim.c.
2630 Specify if the kernel should make use of the cpu
2631 topology informations if the hardware supports these.
2632 The scheduler will make use of these informations and
2633 e.g. base its process migration decisions on it.
2638 trace_buf_size=nn[KMG]
2639 [FTRACE] will set tracing buffer size.
2641 trace_event=[event-list]
2642 [FTRACE] Set and start specified trace events in order
2643 to facilitate early boot debugging.
2644 See also Documentation/trace/events.txt
2646 trix= [HW,OSS] MediaTrix AudioTrix Pro
2648 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2650 tsc= Disable clocksource-must-verify flag for TSC.
2652 [x86] reliable: mark tsc clocksource as reliable, this
2653 disables clocksource verification at runtime.
2654 Used to enable high-resolution timer mode on older
2655 hardware, and in virtualized environment.
2657 turbografx.map[2|3]= [HW,JOY]
2658 TurboGraFX parallel port interface
2660 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2661 See also Documentation/input/joystick-parport.txt
2663 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2664 See header of drivers/scsi/u14-34f.c.
2672 uhash_entries= [KNL,NET]
2673 Set number of hash buckets for UDP/UDP-Lite connections
2676 [USB] Ignore overcurrent events (default N).
2677 Some badly-designed motherboards generate lots of
2678 bogus events, for ports that aren't wired to
2679 anything. Set this parameter to avoid log spamming.
2680 Note that genuine overcurrent events won't be
2685 Set unknown_nmi_panic=1 early on boot.
2687 usbcore.autosuspend=
2688 [USB] The autosuspend time delay (in seconds) used
2689 for newly-detected USB devices (default 2). This
2690 is the time required before an idle device will be
2691 autosuspended. Devices for which the delay is set
2692 to a negative value won't be autosuspended at all.
2694 usbcore.usbfs_snoop=
2695 [USB] Set to log all usbfs traffic (default 0 = off).
2697 usbcore.blinkenlights=
2698 [USB] Set to cycle leds on hubs (default 0 = off).
2700 usbcore.old_scheme_first=
2701 [USB] Start with the old device initialization
2702 scheme (default 0 = off).
2704 usbcore.use_both_schemes=
2705 [USB] Try the other device initialization scheme
2706 if the first one fails (default 1 = enabled).
2708 usbcore.initial_descriptor_timeout=
2709 [USB] Specifies timeout for the initial 64-byte
2710 USB_REQ_GET_DESCRIPTOR request in milliseconds
2711 (default 5000 = 5.0 seconds).
2714 [USBHID] The interval which mice are to be polled at.
2716 usb-storage.delay_use=
2717 [UMS] The delay in seconds before a new device is
2718 scanned for Logical Units (default 5).
2721 [UMS] A list of quirks entries to supplement or
2722 override the built-in unusual_devs list. List
2723 entries are separated by commas. Each entry has
2724 the form VID:PID:Flags where VID and PID are Vendor
2725 and Product ID values (4-digit hex numbers) and
2726 Flags is a set of characters, each corresponding
2727 to a common usb-storage quirk flag as follows:
2728 a = SANE_SENSE (collect more than 18 bytes
2730 b = BAD_SENSE (don't collect more than 18
2731 bytes of sense data);
2732 c = FIX_CAPACITY (decrease the reported
2733 device capacity by one sector);
2734 h = CAPACITY_HEURISTICS (decrease the
2735 reported device capacity by one
2736 sector if the number is odd);
2737 i = IGNORE_DEVICE (don't bind to this
2739 l = NOT_LOCKABLE (don't try to lock and
2740 unlock ejectable media);
2741 m = MAX_SECTORS_64 (don't transfer more
2742 than 64 sectors = 32 KB at a time);
2743 o = CAPACITY_OK (accept the capacity
2744 reported by the device);
2745 r = IGNORE_RESIDUE (the device reports
2746 bogus residue values);
2747 s = SINGLE_LUN (the device has only one
2749 w = NO_WP_DETECT (don't test whether the
2750 medium is write-protected).
2751 Example: quirks=0419:aaf5:rl,0421:0433:rc
2754 [X86] Flags controlling user PTE allocations.
2756 nohigh = do not allocate PTE pages in
2757 HIGHMEM regardless of setting
2761 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2762 vdso=1: enable VDSO (default)
2763 vdso=0: disable VDSO mapping
2766 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2767 vdso32=1: enable 32-bit VDSO (default)
2768 vdso32=0: disable 32-bit VDSO mapping
2771 vector=percpu: enable percpu vector domain
2773 video= [FB] Frame buffer configuration
2774 See Documentation/fb/modedb.txt.
2776 vga= [BOOT,X86-32] Select a particular video mode
2777 See Documentation/x86/boot.txt and
2778 Documentation/svga.txt.
2779 Use vga=ask for menu.
2780 This is actually a boot loader parameter; the value is
2781 passed to the kernel using a special protocol.
2783 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2784 size of <nn>. This can be used to increase the
2785 minimum size (128MB on x86). It can also be used to
2786 decrease the size and leave more room for directly
2789 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2792 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2795 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2798 vt.cur_default= [VT] Default cursor shape.
2799 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2800 the parameters of the <Esc>[?A;B;Cc escape sequence;
2801 see VGA-softcursor.txt. Default: 2 = underline.
2803 vt.default_blu= [VT]
2804 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2805 Change the default blue palette of the console.
2806 This is a 16-member array composed of values
2809 vt.default_grn= [VT]
2810 Format: <green0>,<green1>,<green2>,...,<green15>
2811 Change the default green palette of the console.
2812 This is a 16-member array composed of values
2815 vt.default_red= [VT]
2816 Format: <red0>,<red1>,<red2>,...,<red15>
2817 Change the default red palette of the console.
2818 This is a 16-member array composed of values
2824 Set system-wide default UTF-8 mode for all tty's.
2825 Default is 1, i.e. UTF-8 mode is enabled for all
2826 newly opened terminals.
2828 vt.global_cursor_default=
2831 Set system-wide default for whether a cursor
2832 is shown on new VTs. Default is -1,
2833 i.e. cursors will be created by default unless
2834 overridden by individual drivers. 0 will hide
2835 cursors, 1 will display them.
2837 waveartist= [HW,OSS]
2838 Format: <io>,<irq>,<dma>,<dma2>
2841 See header of drivers/scsi/wd33c93.c.
2844 See header of drivers/scsi/wd7000.c.
2847 See Documentation/watchdog/wdt.txt.
2849 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2850 default x2apic cluster mode on platforms
2853 x86_mrst_timer= [X86-32,APBT]
2854 Choose timer option for x86 Moorestown MID platform.
2855 Two valid options are apbt timer only and lapic timer
2856 plus one apbt timer for broadcast timer.
2857 x86_mrst_timer=apbt_only | lapic_and_apbt
2859 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2860 xd_geo= See header of drivers/block/xd.c.
2862 xirc2ps_cs= [NET,PCMCIA]
2864 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2866 ______________________________________________________________________
2870 Add documentation for ALSA options.
2871 Add more DRM drivers.
projects / linux-flexiantxendom0-3.2.10.git / blob