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
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.
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]
158 2: use 2nd APIC table, if available
159 1,0: use 1st APIC table
162 acpi_backlight= [HW,ACPI]
163 acpi_backlight=vendor
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]
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
202 acpi_early_pdc_eval [HW,ACPI] Evaluate processor _PDC methods
203 early. Needed on some platforms to properly
206 acpi_irq_balance [HW,ACPI]
207 ACPI will balance active IRQs
210 acpi_irq_nobalance [HW,ACPI]
211 ACPI will not move active IRQs (default)
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
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
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
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.
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.
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.
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)
307 See Documentation/scsi/aha152x.txt.
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
313 See Documentation/scsi/aic7xxx.txt.
316 See Documentation/scsi/aic79xx.txt.
318 amd_iommu= [HW,X86-84]
319 Pass parameters to the AMD IOMMU driver in the system.
321 isolate - enable device isolation (each device, as far
322 as possible, will get its own protection
324 share - put every device behind one IOMMU into the
325 same protection domain
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
331 amijoy.map= [HW,JOY] Amiga joystick support
332 Map of devices attached to JOY0DAT and JOY1DAT
334 See also Documentation/kernel/input/joystick.txt
336 analog.map= [HW,JOY] Analog joystick and gamepad support
337 Specifies type or capabilities of an analog joystick
338 connected to one of 16 gameports
339 Format: <type1>,<type2>,..<type16>
342 Power management functions (SPARCstation-4/5 + deriv.)
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
346 APC and your system crashes randomly.
348 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
349 Change the output verbosity whilst booting
350 Format: { quiet (default) | verbose | debug }
351 Change the amount of debugging information output
352 when initialising the APIC and IO-APIC components.
354 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
355 Limit apic dumping. The parameter defines the maximal
356 number of local apics being dumped. Also it is possible
357 to set it to "all" by meaning -- no limit here.
358 Format: { 1 (default) | 2 | ... | all }.
359 The parameter valid if only apic=debug or
360 apic=verbose is specified.
361 Example: apic=debug show_lapic=all
363 apm= [APM] Advanced Power Management
364 See header of arch/x86/kernel/apm_32.c.
366 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
367 Format: <io>,<irq>,<nodeID>
371 atarimouse= [HW,MOUSE] Atari Mouse
373 atascsi= [HW,SCSI] Atari SCSI
375 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
376 EzKey and similar keyboards
378 atkbd.reset= [HW] Reset keyboard during initialization
380 atkbd.set= [HW] Select keyboard code set
381 Format: <int> (2 = AT (default), 3 = PS/2)
383 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
386 atkbd.softraw= [HW] Choose between synthetic and real raw mode
387 Format: <bool> (0 = real, 1 = synthetic (default))
389 atkbd.softrepeat= [HW]
390 Use software keyboard repeat
394 baycom_epp= [HW,AX25]
397 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
399 See header of drivers/net/hamradio/baycom_par.c.
401 baycom_ser_fdx= [HW,AX25]
402 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
403 Format: <io>,<irq>,<mode>[,<baud>]
404 See header of drivers/net/hamradio/baycom_ser_fdx.c.
406 baycom_ser_hdx= [HW,AX25]
407 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
408 Format: <io>,<irq>,<mode>
409 See header of drivers/net/hamradio/baycom_ser_hdx.c.
411 boot_delay= Milliseconds to delay each printk during boot.
412 Values larger than 10 seconds (10000) are changed to
416 bootmem_debug [KNL] Enable bootmem allocator debug messages.
418 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
419 bttv.radio= Most important insmod options are available as
421 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
422 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
425 See drivers/scsi/BusLogic.c, comment before function
426 BusLogic_ParseDriverOptions().
428 c101= [NET] Moxa C101 synchronous serial card
430 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
431 Sometimes CPU hardware bugs make them report the cache
432 size incorrectly. The kernel will attempt work arounds
433 to fix known problems, but for some CPUs it is not
434 possible to determine what the correct size should be.
435 This option provides an override for these situations.
438 [SECURITY] Disable capabilities. This would normally
439 be used only if an alternative security model is to be
440 configured. Potentially dangerous and should only be
441 used if you are entirely sure of the consequences.
443 ccw_timeout_log [S390]
444 See Documentation/s390/CommonIO for details.
446 cgroup_disable= [KNL] Disable a particular controller
447 Format: {name of the controller(s) to disable}
448 {Currently supported controllers - "memory"}
450 checkreqprot [SELINUX] Set initial checkreqprot flag value.
451 Format: { "0" | "1" }
452 See security/selinux/Kconfig help text.
453 0 -- check protection applied by kernel (includes
454 any implied execute protection).
455 1 -- check protection requested by application.
456 Default value is set via a kernel config option.
457 Value can be changed at runtime via
458 /selinux/checkreqprot.
461 See Documentation/s390/CommonIO for details.
463 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
465 Forces specified clocksource (if available) to be used
466 when calculating gettimeofday(). If specified
467 clocksource is not available, it defaults to PIT.
468 Format: { pit | tsc | cyclone | pmtmr }
470 clocksource= [GENERIC_TIME] Override the default clocksource
472 Override the default clocksource and use the clocksource
473 with the name specified.
474 Some clocksource names to choose from, depending on
476 [all] jiffies (this is the base, fallback clocksource)
478 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
479 pxa_timer,timer3,32k_counter,timer0_1
481 [X86-32] pit,hpet,tsc,vmi-timer;
482 scx200_hrt on Geode; cyclone on IBM x440
490 clearcpuid=BITNUM [X86]
491 Disable CPUID feature X for the kernel. See
492 arch/x86/include/asm/cpufeature.h for the valid bit
493 numbers. Note the Linux specific bits are not necessarily
494 stable over kernel options, but the vendor specific
496 Also note that user programs calling CPUID directly
497 or using the feature without checking anything
498 will still see it. This just prevents it from
499 being used by the kernel or shown in /proc/cpuinfo.
500 Also note the kernel might malfunction if you disable
503 cmo_free_hint= [PPC] Format: { yes | no }
504 Specify whether pages are marked as being inactive
505 when they are freed. This is used in CMO environments
506 to determine OS memory pressure for page stealing by
510 code_bytes [X86] How many bytes of object code to print
515 com20020= [HW,NET] ARCnet - COM20020 chipset
517 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
519 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
523 ARCnet - COM90xx chipset (memory-mapped buffers)
524 Format: <io>[,<irq>[,<memstart>]]
526 condev= [HW,S390] console device
529 console= [KNL] Output console device and options.
531 tty<n> Use the virtual console device <n>.
535 Use the specified serial port. The options are of
536 the form "bbbbpnf", where "bbbb" is the baud rate,
537 "p" is parity ("n", "o", or "e"), "n" is number of
538 bits, and "f" is flow control ("r" for RTS or
539 omit it). Default is "9600n8".
541 See Documentation/serial-console.txt for more
543 Documentation/networking/netconsole.txt for an
546 uart[8250],io,<addr>[,options]
547 uart[8250],mmio,<addr>[,options]
548 Start an early, polled-mode console on the 8250/16550
549 UART at the specified I/O port or MMIO address,
550 switching to the matching ttyS device later. The
551 options are the same as for ttyS, above.
553 If the device connected to the port is not a TTY but a braille
554 device, prepend "brl," before the device type, for instance
556 For now, only VisioBraille is supported.
558 consoleblank= [KNL] The console blank (screen saver) timeout in
559 seconds. Defaults to 10*60 = 10mins. A value of 0
560 disables the blank timer.
563 [KNL] Change the default value for
564 /proc/<pid>/coredump_filter.
565 See also Documentation/filesystems/proc.txt.
567 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
569 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
571 crashkernel=nn[KMG]@ss[KMG]
572 [KNL] Reserve a chunk of physical memory to
573 hold a kernel to switch to with kexec on panic.
575 crashkernel=range1:size1[,range2:size2,...][@offset]
576 [KNL] Same as above, but depends on the memory
577 in the running system. The syntax of range is
578 start-[end] where start and end are both
579 a memory unit (amount[KMG]). See also
580 Documentation/kdump/kdump.txt for a example.
585 cs89x0_media= [HW,NET]
586 Format: { rj45 | aui | bnc }
589 See header of drivers/s390/block/dasd_devmap.c.
591 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
592 (one device per port)
593 Format: <port#>,<type>
594 See also Documentation/input/joystick-parport.txt
596 debug [KNL] Enable kernel debugging (events log level).
599 [KNL] verbose self-tests
601 Print debugging info while doing the locking API
603 We default to 0 (no extra messages), setting it to
604 1 will print _a lot_ more information - normally
605 only useful to kernel developers.
607 debug_objects [KNL] Enable object debugging
610 [KNL] Disable object debugging
612 debugpat [X86] Enable PAT debugging
614 decnet.addr= [HW,NET]
615 Format: <area>[,<node>]
616 See also Documentation/networking/decnet.txt.
619 [same as hugepagesz=] The size of the default
620 HugeTLB page size. This is the size represented by
621 the legacy /proc/ hugepages APIs, used for SHM, and
622 default size when mounting hugetlbfs filesystems.
623 Defaults to the default architecture's huge page size
627 Set number of hash buckets for dentry cache.
630 IO parameters + enable/disable command.
632 digiepca= [HW,SERIAL]
633 See drivers/char/README.epca and
634 Documentation/serial/digiepca.txt.
636 disable_mtrr_cleanup [X86]
637 The kernel tries to adjust MTRR layout from continuous
638 to discrete, to make X server driver able to add WB
639 entry later. This parameter disables that.
641 disable_mtrr_trim [X86, Intel and AMD only]
642 By default the kernel will trim any uncacheable
643 memory out of your available memory pool based on
644 MTRR settings. This parameter disables that behavior,
645 possibly causing your machine to run very slowly.
647 disable_timer_pin_1 [X86]
648 Disable PIN 1 of APIC timer
649 Can be useful to work around chipset bugs.
651 dmasound= [HW,OSS] Sound subsystem buffers
653 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
654 this option disables the debugging code at boot.
656 dma_debug_entries=<number>
657 This option allows to tune the number of preallocated
658 entries for DMA-API debugging code. One entry is
659 required per DMA-API allocation. Use this if the
660 DMA-API debugging code disables itself because the
661 architectural default is too low.
663 dma_debug_driver=<driver_name>
664 With this option the DMA-API debugging driver
665 filter feature can be enabled at boot time. Just
666 pass the driver to filter for as the parameter.
667 The filter can be disabled or changed to another
668 driver later using sysfs.
674 dynamic_printk Enables pr_debug()/dev_dbg() calls if
675 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
676 These can also be switched on/off via
677 <debugfs>/dynamic_printk/modules
679 earlycon= [KNL] Output early console device and options.
680 uart[8250],io,<addr>[,options]
681 uart[8250],mmio,<addr>[,options]
682 Start an early, polled-mode console on the 8250/16550
683 UART at the specified I/O port or MMIO address.
684 The options are the same as for ttyS, above.
686 earlyprintk= [X86,SH,BLACKFIN]
688 earlyprintk=serial[,ttySn[,baudrate]]
689 earlyprintk=ttySn[,baudrate]
690 earlyprintk=dbgp[debugController#]
692 Append ",keep" to not disable it when the real console
695 Only vga or serial or usb debug port at a time.
697 Currently only ttyS0 and ttyS1 are supported.
699 Interaction with the standard serial driver is not
702 The VGA output is eventually overwritten by the real
708 Format: {"off" | "on" | "skip[mbr]"}
710 eisa_irq_edge= [PARISC,HW]
711 See header of drivers/parisc/eisa.c.
714 See comment before function elanfreq_setup() in
715 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
718 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
719 See Documentation/block/as-iosched.txt and
720 Documentation/block/deadline-iosched.txt for details.
722 elfcorehdr= [IA64,PPC,SH,X86]
723 Specifies physical address of start of kernel core
724 image elf header. Generally kexec loader will
725 pass this option to capture kernel.
726 See Documentation/kdump/kdump.txt for details.
728 enable_mtrr_cleanup [X86]
729 The kernel tries to adjust MTRR layout from continuous
730 to discrete, to make X server driver able to add WB
731 entry later. This parameter enables that.
733 enable_timer_pin_1 [X86]
734 Enable PIN 1 of APIC timer
735 Can be useful to work around chipset bugs
736 (in particular on some ATI chipsets).
737 The kernel tries to set a reasonable default.
739 enforcing [SELINUX] Set initial enforcing status.
741 See security/selinux/Kconfig help text.
742 0 -- permissive (log only, no denials).
743 1 -- enforcing (deny and log).
745 Value can be changed at runtime via /selinux/enforce.
747 ether= [HW,NET] Ethernet cards parameters
748 This option is obsoleted by the "netdev=" option, which
749 has equivalent usage. See its documentation for details.
751 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
756 fail_make_request=[KNL]
757 General fault injection mechanism.
758 Format: <interval>,<probability>,<space>,<times>
759 See also /Documentation/fault-injection/.
762 See header of drivers/scsi/fd_mcs.c.
765 See header of drivers/scsi/fdomain.c.
768 See Documentation/blockdev/floppy.txt.
770 force_pal_cache_flush
771 [IA-64] Avoid check_sal_cache_flush which may hang on
772 buggy SAL_CACHE_FLUSH implementations. Using this
773 parameter will force ia64_sal_cache_flush to call
774 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
777 [FTRACE] will set and start the specified tracer
778 as early as possible in order to facilitate early
782 [FTRACE] will dump the trace buffers on oops.
784 ftrace_filter=[function-list]
785 [FTRACE] Limit the functions traced by the function
786 tracer at boot up. function-list is a comma separated
787 list of functions. This list can be changed at run
788 time by the set_ftrace_filter file in the debugfs
791 ftrace_notrace=[function-list]
792 [FTRACE] Do not trace the functions specified in
793 function-list. This list can be changed at run time
794 by the set_ftrace_notrace file in the debugfs
797 ftrace_graph_filter=[function-list]
798 [FTRACE] Limit the top level callers functions traced
799 by the function graph tracer at boot up.
800 function-list is a comma separated list of functions
801 that can be changed at run time by the
802 set_graph_function file in the debugfs tracing directory.
805 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
806 support via parallel port (up to 5 devices per port)
807 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
808 See also Documentation/input/joystick-parport.txt
812 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
816 gcov_persist= [GCOV] When non-zero (default), profiling data for
817 kernel modules is saved and remains accessible via
818 debugfs, even when the module is unloaded/reloaded.
819 When zero, profiling data is discarded and associated
820 debugfs files are removed at module unload time.
823 See header of drivers/scsi/gdth.c.
825 gpt [EFI] Forces disk with valid GPT signature but
826 invalid Protective MBR to be treated as GPT.
830 hashdist= [KNL,NUMA] Large hashes allocated during boot
831 are distributed across NUMA nodes. Defaults on
832 for 64bit NUMA, off otherwise.
833 Format: 0 | 1 (for off | on)
835 hcl= [IA-64] SGI's Hardware Graph compatibility layer
837 hd= [EIDE] (E)IDE hard drive subsystem geometry
838 Format: <cyl>,<head>,<sect>
840 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
841 size of <nn>. This works even on boxes that have no
842 highmem otherwise. This also works to reduce highmem
843 size on bigger boxes.
845 highres= [KNL] Enable/disable high resolution timer mode.
846 Valid parameters: "on", "off"
850 See Documentation/isdn/README.HiSax.
854 hpet= [X86-32,HPET] option to control HPET usage
855 Format: { enable (default) | disable | force |
857 disable: disable HPET and use PIT instead
858 force: allow force enabled of undocumented chips (ICH4,
860 verbose: show contents of HPET registers during setup
862 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
863 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
864 On x86-64 and powerpc, this option can be specified
865 multiple times interleaved with hugepages= to reserve
866 huge pages of different sizes. Valid pages sizes on
867 x86-64 are 2M (when the CPU supports "pse") and 1G
868 (when the CPU supports the "pdpe1gb" cpuinfo flag)
869 Note that 1GB pages can only be allocated at boot time
870 using hugepages= and not freed afterwards.
872 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
873 terminal devices. Valid values: 0..8
874 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
875 If specified, z/VM IUCV HVC accepts connections
876 from listed z/VM user IDs only.
878 i2c_bus= [HW] Override the default board specific I2C bus speed
879 or register an additional I2C bus that is not
880 registered from board initialization code.
884 i8042.debug [HW] Toggle i8042 debug mode
885 i8042.direct [HW] Put keyboard port into non-translated mode
886 i8042.dumbkbd [HW] Pretend that controller can only read data from
887 keyboard and cannot control its state
888 (Don't attempt to blink the leds)
889 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
890 i8042.nokbd [HW] Don't check/create keyboard port
891 i8042.noloop [HW] Disable the AUX Loopback command while probing
893 i8042.nomux [HW] Don't check presence of an active multiplexing
895 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
898 [HW] Frequency with which keyboard LEDs should blink
899 when kernel panics (default is 0.5 sec)
900 i8042.reset [HW] Reset the controller during init and cleanup
901 i8042.unlock [HW] Unlock (ignore) the keylock
905 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
906 indicates that the driver is running on unsupported
908 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
909 does not match list of supported models.
911 [HW] Report power status in /proc/i8k
912 (disabled by default)
913 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
916 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
917 See Documentation/mca.txt.
920 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
922 ide-core.nodma= [HW] (E)IDE subsystem
923 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
924 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
925 .cdrom .chs .ignore_cable are additional options
926 See Documentation/ide/ide.txt.
928 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
929 Claim all unknown PCI IDE storage controllers.
932 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
933 Poll forces a polling idle loop that can slightly
934 improve the performance of waking up a idle CPU, but
935 will use a lot of power and make the system run hot.
937 idle=mwait: On systems which support MONITOR/MWAIT but
938 the kernel chose to not use it because it doesn't save
939 as much power as a normal idle loop, use the
940 MONITOR/MWAIT idle loop anyways. Performance should be
941 the same as idle=poll.
942 idle=halt: Halt is forced to be used for CPU idle.
943 In such case C2/C3 won't be used again.
944 idle=nomwait: Disable mwait for CPU C-states
946 ignore_loglevel [KNL]
947 Ignore loglevel setting - this will print /all/
948 kernel messages to the console. Useful for debugging.
951 Set number of hash buckets for inode cache.
954 Format: { "0" | "1" }
955 0 -- integrity auditing messages. (Default)
956 1 -- enable informational integrity auditing messages.
959 Format: { "sha1" | "md5" }
963 Load a policy which meets the needs of the Trusted
964 Computing Base. This means IMA will measure all
965 programs exec'd, files mmap'd for exec, and all files
966 opened for read by uid=0.
969 See header of drivers/scsi/in2000.c.
973 Run specified binary instead of /sbin/init as init
976 initcall_debug [KNL] Trace initcalls as they are executed. Useful
977 for working out where the kernel is dying during
980 initrd= [BOOT] Specify the location of the initial ramdisk
982 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
985 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
987 Enable intel iommu driver.
989 Disable intel iommu driver.
990 igfx_off [Default Off]
991 By default, gfx is mapped as normal device. If a gfx
992 device has a dedicated DMAR unit, the DMAR unit is
993 bypassed by not enabling DMAR with this option. In
994 this case, gfx device will use physical address for
997 With this option iommu will not optimize to look
998 for io virtual address below 32 bit forcing dual
999 address cycle on pci bus for cards supporting greater
1000 than 32 bit addressing. The default is to look
1001 for translation below 32 bit and if not available
1002 then look in the higher range.
1003 strict [Default Off]
1004 With this option on every unmap_single operation will
1005 result in a hardware IOTLB flush operation as opposed
1006 to batching them for performance.
1010 iomem= Disable strict checking of access to MMIO memory
1011 strict regions from userspace.
1027 io7= [HW] IO7 for Marvel based alpha systems
1028 See comment before marvel_specify_io7 in
1029 arch/alpha/kernel/core_marvel.c.
1031 io_delay= [X86] I/O delay method
1033 Standard port 0x80 based delay
1035 Alternate port 0xed based delay (needed on some systems)
1037 Simple two microseconds delay
1042 See Documentation/filesystems/nfs/nfsroot.txt.
1044 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1045 See comment before ip2_setup() in
1046 drivers/char/ip2/ip2base.c.
1048 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1049 See header of drivers/scsi/ips.c.
1052 When an interrupt is not handled search all handlers
1053 for it. Intended to get systems with badly broken
1057 When an interrupt is not handled search all handlers
1058 for it. Also check all handlers each timer
1059 interrupt. Intended to get systems with badly broken
1063 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1065 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1067 <cpu number>,...,<cpu number>
1069 <cpu number>-<cpu number>
1070 (must be a positive range in ascending order)
1072 <cpu number>,...,<cpu number>-<cpu number>
1074 This option can be used to specify one or more CPUs
1075 to isolate from the general SMP balancing and scheduling
1076 algorithms. You can move a process onto or off an
1077 "isolated" CPU via the CPU affinity syscalls or cpuset.
1078 <cpu number> begins at 0 and the maximum value is
1079 "number of CPUs in system - 1".
1081 This option is the preferred way to isolate CPUs. The
1082 alternative -- manually setting the CPU mask of all
1083 tasks in the system -- can cause problems and
1084 suboptimal load balancer performance.
1088 js= [HW,JOY] Analog joystick
1089 See Documentation/input/joystick.txt.
1093 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1094 specifies the amount of memory usable by the kernel
1095 for non-movable allocations. The requested amount is
1096 spread evenly throughout all nodes in the system. The
1097 remaining memory in each node is used for Movable
1098 pages. In the event, a node is too small to have both
1099 kernelcore and Movable pages, kernelcore pages will
1100 take priority and other nodes will have a larger number
1101 of kernelcore pages. The Movable zone is used for the
1102 allocation of pages that may be reclaimed or moved
1103 by the page migration subsystem. This means that
1104 HugeTLB pages may not be allocated from this zone.
1105 Note that allocations like PTEs-from-HighMem still
1106 use the HighMem zone if it exists, and the Normal
1107 zone if it does not.
1109 kgdboc= [HW] kgdb over consoles.
1110 Requires a tty driver that supports console polling.
1111 (only serial supported for now)
1112 Format: <serial_device>[,baud]
1114 kmac= [MIPS] korina ethernet MAC address.
1115 Configure the RouterBoard 532 series on-chip
1116 Ethernet adapter MAC address.
1118 kmemleak= [KNL] Boot-time kmemleak enable/disable
1119 Valid arguments: on, off
1122 kstack=N [X86] Print N words from the kernel stack
1125 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1126 Default is 0 (don't ignore, but inject #GP)
1128 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1129 Default is 1 (enabled)
1131 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1134 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1136 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1138 kvm-intel.bypass_guest_pf=
1139 [KVM,Intel] Disables bypassing of guest page faults
1140 on Intel chips. Default is 1 (enabled)
1142 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1143 (virtualized MMU) support on capable Intel chips.
1144 Default is 1 (enabled)
1146 kvm-intel.emulate_invalid_guest_state=
1147 [KVM,Intel] Enable emulation of invalid guest states
1148 Default is 0 (disabled)
1150 kvm-intel.flexpriority=
1151 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1152 Default is 1 (enabled)
1154 kvm-intel.unrestricted_guest=
1155 [KVM,Intel] Disable unrestricted guest feature
1156 (virtualized real and unpaged mode) on capable
1157 Intel chips. Default is 1 (enabled)
1159 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1160 feature (tagged TLBs) on capable Intel chips.
1161 Default is 1 (enabled)
1167 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1170 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1173 libata.dma= [LIBATA] DMA control
1174 libata.dma=0 Disable all PATA and SATA DMA
1175 libata.dma=1 PATA and SATA Disk DMA only
1176 libata.dma=2 ATAPI (CDROM) DMA only
1177 libata.dma=4 Compact Flash DMA only
1178 Combinations also work, so libata.dma=3 enables DMA
1179 for disks and CDROMs, but not CFs.
1181 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1182 libata.ignore_hpa=0 keep BIOS limits (default)
1183 libata.ignore_hpa=1 ignore limits, using full disk
1185 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1189 libata.force= [LIBATA] Force configurations. The format is comma
1190 separated list of "[ID:]VAL" where ID is
1191 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1192 matching port, link or device. Basically, it matches
1193 the ATA ID string printed on console by libata. If
1194 the whole ID part is omitted, the last PORT and DEVICE
1195 values are used. If ID hasn't been specified yet, the
1196 configuration applies to all ports, links and devices.
1198 If only DEVICE is omitted, the parameter applies to
1199 the port and all links and devices behind it. DEVICE
1200 number of 0 either selects the first device or the
1201 first fan-out link behind PMP device. It does not
1202 select the host link. DEVICE number of 15 selects the
1203 host link and device attached to it.
1205 The VAL specifies the configuration to force. As long
1206 as there's no ambiguity shortcut notation is allowed.
1207 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1208 The following configurations can be forced.
1210 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1211 Any ID with matching PORT is used.
1213 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1215 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1216 udma[/][16,25,33,44,66,100,133] notation is also
1219 * [no]ncq: Turn on or off NCQ.
1221 * nohrst, nosrst, norst: suppress hard, soft
1224 If there are multiple matching configurations changing
1225 the same attribute, the last one is used.
1227 lmb=debug [KNL] Enable lmb debug messages.
1229 load_ramdisk= [RAM] List of ramdisks to load from floppy
1230 See Documentation/blockdev/ramdisk.txt.
1232 lockd.nlm_grace_period=P [NFS] Assign grace period.
1235 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1238 lockd.nlm_timeout=T [NFS] Assign timeout value.
1241 lockd.nlm_udpport=M [NFS] Assign UDP port.
1244 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1247 loglevel= All Kernel Messages with a loglevel smaller than the
1248 console loglevel will be printed to the console. It can
1249 also be changed with klogd or other programs. The
1250 loglevels are defined as follows:
1252 0 (KERN_EMERG) system is unusable
1253 1 (KERN_ALERT) action must be taken immediately
1254 2 (KERN_CRIT) critical conditions
1255 3 (KERN_ERR) error conditions
1256 4 (KERN_WARNING) warning conditions
1257 5 (KERN_NOTICE) normal but significant condition
1258 6 (KERN_INFO) informational
1259 7 (KERN_DEBUG) debug-level messages
1261 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1262 Format: { n | nk | nM }
1263 n must be a power of two. The default size
1264 is set in the kernel config file.
1266 logo.nologo [FB] Disables display of the built-in Linux logo.
1267 This may be used to provide more screen space for
1268 kernel log messages and is useful when debugging
1269 kernel boot problems.
1271 lp=0 [LP] Specify parallel ports to use, e.g,
1272 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1273 lp=reset first parallel port). 'lp=0' disables the
1274 lp=auto printer driver. 'lp=reset' (which can be
1275 specified in addition to the ports) causes
1276 attached printers to be reset. Using
1277 lp=port1,port2,... specifies the parallel ports
1278 to associate lp devices with, starting with
1279 lp0. A port specification may be 'none' to skip
1280 that lp device, or a parport name such as
1281 'parport0'. Specifying 'lp=auto' instead of a
1282 port specification list means that device IDs
1283 from each port should be examined, to see if
1284 an IEEE 1284-compliant printer is attached; if
1285 so, the driver will manage that printer.
1286 See also header of drivers/char/lp.c.
1289 Sets loops_per_jiffy to given constant, thus avoiding
1290 time-consuming boot-time autodetection (up to 250 ms per
1291 CPU). 0 enables autodetection (default). To determine
1292 the correct value for your kernel, boot with normal
1293 autodetection and see what value is printed. Note that
1294 on SMP systems the preset will be applied to all CPUs,
1295 which is likely to cause problems if your CPUs need
1296 significantly divergent settings. An incorrect value
1297 will cause delays in the kernel to be wrong, leading to
1298 unpredictable I/O errors and other breakage. Although
1299 unlikely, in the extreme case this might damage your
1303 Format: <io>,<irq>,<dma>
1305 mac5380= [HW,SCSI] Format:
1306 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1308 machvec= [IA64] Force the use of a particular machine-vector
1309 (machvec) in a generic kernel.
1310 Example: machvec=hpzx1_swiotlb
1312 machtype= [Loongson] Share the same kernel image file between different
1314 Example: machtype=lemote-yeeloong-2f-7inch
1316 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1317 than or equal to this physical address is ignored.
1319 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1320 should make use of. maxcpus=n : n >= 0 limits the
1321 kernel to using 'n' processors. n=0 is a special case,
1322 it is equivalent to "nosmp", which also disables
1325 max_loop= [LOOP] Maximum number of loopback devices that can
1329 max_luns= [SCSI] Maximum number of LUNs to probe.
1330 Should be between 1 and 2^32-1.
1333 [SCSI] Maximum number of LUNs received.
1334 Should be between 1 and 16384.
1338 mce [X86-32] Machine Check Exception
1340 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1342 md= [HW] RAID subsystems devices and level
1343 See Documentation/md.txt.
1346 Format: <first>,<last>
1347 Specifies range of consoles to be captured by the MDA.
1349 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1350 Amount of memory to be used when the kernel is not able
1351 to see the whole system memory or for test.
1352 [X86-32] Use together with memmap= to avoid physical
1353 address space collisions. Without memmap= PCI devices
1354 could be placed at addresses belonging to unused RAM.
1356 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1360 [KNL,SH] Allow user to override the default size for
1361 per-device physically contiguous DMA buffers.
1363 memmap=exactmap [KNL,X86] Enable setting of an exact
1364 E820 memory map, as specified by the user.
1365 Such memmap=exactmap lines can be constructed based on
1366 BIOS output or other requirements. See the memmap=nn@ss
1369 memmap=nn[KMG]@ss[KMG]
1370 [KNL] Force usage of a specific region of memory
1371 Region of memory to be used, from ss to ss+nn.
1373 memmap=nn[KMG]#ss[KMG]
1374 [KNL,ACPI] Mark specific memory as ACPI data.
1375 Region of memory to be used, from ss to ss+nn.
1377 memmap=nn[KMG]$ss[KMG]
1378 [KNL,ACPI] Mark specific memory as reserved.
1379 Region of memory to be used, from ss to ss+nn.
1380 Example: Exclude memory from 0x18690000-0x1869ffff
1381 memmap=64K$0x18690000
1383 memmap=0x10000$0x18690000
1385 memory_corruption_check=0/1 [X86]
1386 Some BIOSes seem to corrupt the first 64k of
1387 memory when doing things like suspend/resume.
1388 Setting this option will scan the memory
1389 looking for corruption. Enabling this will
1390 both detect corruption and prevent the kernel
1391 from using the memory being corrupted.
1392 However, its intended as a diagnostic tool; if
1393 repeatable BIOS-originated corruption always
1394 affects the same memory, you can use memmap=
1395 to prevent the kernel from using that memory.
1397 memory_corruption_check_size=size [X86]
1398 By default it checks for corruption in the low
1399 64k, making this memory unavailable for normal
1400 use. Use this parameter to scan for
1401 corruption in more or less memory.
1403 memory_corruption_check_period=seconds [X86]
1404 By default it checks for corruption every 60
1405 seconds. Use this parameter to check at some
1406 other rate. 0 disables periodic checking.
1408 memtest= [KNL,X86] Enable memtest
1410 default : 0 <disable>
1411 Specifies the number of memtest passes to be
1412 performed. Each pass selects another test
1413 pattern from a given set of patterns. Memtest
1414 fills the memory with this pattern, validates
1415 memory contents and reserves bad memory
1416 regions that are detected.
1418 meye.*= [HW] Set MotionEye Camera parameters
1419 See Documentation/video4linux/meye.txt.
1421 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1422 Multi-Function General Purpose Timers on AMD Geode
1425 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1426 the BIOS has incorrectly applied a workaround. TinyBIOS
1427 version 0.98 is known to be affected, 0.99 fixes the
1428 problem by letting the user disable the workaround.
1432 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1433 physical address is ignored.
1435 mini2440= [ARM,HW,KNL]
1436 Format:[0..2][b][c][t]
1438 MINI2440 configuration specification:
1439 0 - The attached screen is the 3.5" TFT
1440 1 - The attached screen is the 7" TFT
1441 2 - The VGA Shield is attached (1024x768)
1442 Leaving out the screen size parameter will not load
1443 the TFT driver, and the framebuffer will be left
1445 b - Enable backlight. The TFT backlight pin will be
1446 linked to the kernel VESA blanking code and a GPIO
1447 LED. This parameter is not necessary when using the
1449 c - Enable the s3c camera interface.
1450 t - Reserved for enabling touchscreen support. The
1451 touchscreen support is not enabled in the mainstream
1452 kernel as of 2.6.30, a preliminary port can be found
1453 in the "bleeding edge" mini2440 support kernel at
1454 http://repo.or.cz/w/linux-2.6/mini2440.git
1457 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1458 parameter allows control of the logging verbosity for
1459 the additional memory initialisation checks. A value
1460 of 0 disables mminit logging and a level of 4 will
1461 log everything. Information is printed at KERN_DEBUG
1462 so loglevel=8 may also need to be specified.
1465 [MOUSE] Maximum time between finger touching and
1466 leaving touchpad surface for touch to be considered
1467 a tap and be reported as a left button click (for
1468 touchpads working in absolute mode only).
1470 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1471 reporting absolute coordinates, such as tablets
1472 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1473 reporting absolute coordinates, such as tablets
1475 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1476 is similar to kernelcore except it specifies the
1477 amount of memory used for migratable allocations.
1478 If both kernelcore and movablecore is specified,
1479 then kernelcore will be at *least* the specified
1480 value but may be more. If movablecore on its own
1481 is specified, the administrator must be careful
1482 that the amount of memory usable for all allocations
1488 MTD_Partition= [MTD]
1489 Format: <name>,<region-number>,<size>,<offset>
1491 MTD_Region= [MTD] Format:
1492 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1495 See drivers/mtd/cmdlinepart.c.
1497 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1499 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1501 boundary - index of last SLC block on Flex-OneNAND.
1502 The remaining blocks are configured as MLC blocks.
1503 lock - Configure if Flex-OneNAND boundary should be locked.
1504 Once locked, the boundary cannot be changed.
1505 1 indicates lock status, 0 indicates unlock status.
1508 ARM/S3C2412 JIVE boot control
1510 See arch/arm/mach-s3c2412/mach-jive.c
1512 mtouchusb.raw_coordinates=
1513 [HW] Make the MicroTouch USB driver use raw coordinates
1514 ('y', default) or cooked coordinates ('n')
1516 mtrr_chunk_size=nn[KMG] [X86]
1517 used for mtrr cleanup. It is largest continuous chunk
1518 that could hold holes aka. UC entries.
1520 mtrr_gran_size=nn[KMG] [X86]
1521 Used for mtrr cleanup. It is granularity of mtrr block.
1523 Large value could prevent small alignment from
1526 mtrr_spare_reg_nr=n [X86]
1528 Range: 0,7 : spare reg number
1530 Used for mtrr cleanup. It is spare mtrr entries number.
1531 Set to 2 or more if your graphical card needs more.
1533 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1536 See header of drivers/scsi/NCR_D700.c.
1540 ncr53c400= [HW,SCSI]
1542 ncr53c400a= [HW,SCSI]
1544 ncr53c406a= [HW,SCSI]
1546 ncr53c8xx= [HW,SCSI]
1548 netdev= [NET] Network devices parameters
1549 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1550 Note that mem_start is often overloaded to mean
1551 something different and driver-specific.
1552 This usage is only documented in each driver source
1556 [NETFILTER] Enable connection tracking flow accounting
1557 0 to disable accounting
1558 1 to enable accounting
1559 Default value depends on CONFIG_NF_CT_ACCT that is
1560 going to be removed in 2.6.29.
1563 See Documentation/filesystems/nfs/nfsroot.txt.
1565 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1566 See Documentation/filesystems/nfs/nfsroot.txt.
1568 nfs.callback_tcpport=
1569 [NFS] set the TCP port on which the NFSv4 callback
1570 channel should listen.
1573 [NFS] sets the pathname to the program which is used
1574 to update the NFS client cache entries.
1576 nfs.cache_getent_timeout=
1577 [NFS] sets the timeout after which an attempt to
1578 update a cache entry is deemed to have failed.
1580 nfs.idmap_cache_timeout=
1581 [NFS] set the maximum lifetime for idmapper cache
1585 [NFS] enable 64-bit inode numbers.
1586 If zero, the NFS client will fake up a 32-bit inode
1587 number for the readdir() and stat() syscalls instead
1588 of returning the full 64-bit number.
1589 The default is to return 64-bit inode numbers.
1591 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1592 when a NMI is triggered.
1593 Format: [state][,regs][,debounce][,die]
1595 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1596 Format: [panic,][num]
1598 0 - turn nmi_watchdog off
1599 1 - use the IO-APIC timer for the NMI watchdog
1600 2 - use the local APIC for the NMI watchdog using
1601 a performance counter. Note: This will use one
1602 performance counter and the local APIC's performance
1604 When panic is specified, panic when an NMI watchdog
1606 This is useful when you use a panic=... timeout and
1607 need the box quickly up again.
1608 Instead of 1 and 2 it is possible to use the following
1609 symbolic names: lapic and ioapic
1610 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1612 netpoll.carrier_timeout=
1613 [NET] Specifies amount of time (in seconds) that
1614 netpoll should wait for a carrier. By default netpoll
1617 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1618 emulation library even if a 387 maths coprocessor
1622 [HW] Never suspend the console
1623 Disable suspending of consoles during suspend and
1624 hibernate operations. Once disabled, debugging
1625 messages can reach various consoles while the rest
1626 of the system is being put to sleep (ie, while
1627 debugging driver suspend/resume hooks). This may
1628 not work reliably with all consoles, but is known
1629 to work with serial and VGA consoles.
1631 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1632 caches in the slab allocator. Saves per-node memory,
1633 but will impact performance.
1637 noapic [SMP,APIC] Tells the kernel to not make use of any
1638 IOAPICs that may be present in the system.
1640 nobats [PPC] Do not use BATs for mapping kernel lowmem
1641 on "Classic" PPC cores.
1645 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1647 nodelayacct [KNL] Disable per-task delay accounting
1649 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1651 nodsp [SH] Disable hardware DSP at boot time.
1653 noefi [X86] Disable EFI runtime services support.
1658 On X86-32 available only on PAE configured kernels.
1659 noexec=on: enable non-executable mappings (default)
1660 noexec=off: disable non-executable mappings
1663 This affects only 32-bit executables.
1664 noexec32=on: enable non-executable mappings (default)
1665 read doesn't imply executable mappings
1666 noexec32=off: disable non-executable mappings
1667 read implies executable mappings
1669 nofpu [SH] Disable hardware FPU at boot time.
1671 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1672 register save and restore. The kernel will only save
1673 legacy floating-point registers on task switch.
1675 noxsave [BUGS=X86] Disables x86 extended register state save
1676 and restore using xsave. The kernel will fallback to
1677 enabling legacy floating-point and sse state.
1679 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1680 wfi(ARM) instruction doesn't work correctly and not to
1681 use it. This is also useful when using JTAG debugger.
1683 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1684 instruction doesn't work correctly and not to
1687 no_file_caps Tells the kernel not to honor file capabilities. The
1688 only way then for a file to be executed with privilege
1689 is to be setuid root or executed by root.
1691 nohalt [IA-64] Tells the kernel not to use the power saving
1692 function PAL_HALT_LIGHT when idle. This increases
1693 power-consumption. On the positive side, it reduces
1694 interrupt wake-up latency, which may improve performance
1695 in certain environments such as networked servers or
1698 nohz= [KNL] Boottime enable/disable dynamic ticks
1699 Valid arguments: on, off
1702 noiotrap [SH] Disables trapped I/O port accesses.
1704 noirqdebug [X86-32] Disables the code which attempts to detect and
1705 disable unhandled interrupt sources.
1707 no_timer_check [X86,APIC] Disables the code which tests for
1708 broken timer IRQ sources.
1710 noisapnp [ISAPNP] Disables ISA PnP code.
1712 noinitrd [RAM] Tells the kernel not to load any configured
1715 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1720 nojitter [IA64] Disables jitter checking for ITC timers.
1722 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1724 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1726 noltlbs [PPC] Do not use large page/tlb entries for kernel
1727 lowmem mapping on PPC40x.
1729 nomca [IA-64] Disable machine check abort handling
1731 nomce [X86-32] Machine Check Exception
1733 nomfgpt [X86-32] Disable Multi-Function General Purpose
1734 Timer usage (for AMD Geode machines).
1736 norandmaps Don't use address space randomization. Equivalent to
1737 echo 0 > /proc/sys/kernel/randomize_va_space
1739 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1741 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1742 with UP alternatives
1744 noresidual [PPC] Don't use residual data on PReP machines.
1746 noresume [SWSUSP] Disables resume and restores original swap
1749 no-scroll [VGA] Disables scrollback.
1750 This is required for the Braillex ib80-piezo Braille
1751 reader made by F.H. Papenmeier (Germany).
1755 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1757 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1758 and disable the IO APIC. legacy for "maxcpus=0".
1760 nosoftlockup [KNL] Disable the soft-lockup detector.
1762 noswapaccount [KNL] Disable accounting of swap in memory resource
1763 controller. (See Documentation/cgroups/memory.txt)
1765 nosync [HW,M68K] Disables sync negotiation for all devices.
1767 notsc [BUGS=X86-32] Disable Time Stamp Counter
1769 nousb [USB] Disable the USB subsystem
1773 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1775 nptcg= [IA64] Override max number of concurrent global TLB
1776 purges which is reported from either PAL_VM_SUMMARY or
1779 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1781 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1782 one of ['zone', 'node', 'default'] can be specified
1783 This can be set from sysctl after boot.
1784 See Documentation/sysctl/vm.txt for details.
1786 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1787 See Documentation/debugging-via-ohci1394.txt for more
1790 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1791 Rather than timing out after 20 ms if an EC
1792 command is not properly ACKed, override the length
1793 of the timeout. We have interrupts disabled while
1794 waiting for the ACK, so if this is set too high
1795 interrupts *may* be lost!
1797 omap_mux= [OMAP] Override bootloader pin multiplexing.
1798 Format: <mux_mode0.mode_name=value>...
1799 For example, to override I2C bus2:
1800 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1805 oprofile.timer= [HW]
1806 Use timer interrupt instead of performance counters
1808 oprofile.cpu_type= Force an oprofile cpu type
1809 This might be useful if you have an older oprofile
1810 userland or if you want common events.
1811 Format: { arch_perfmon }
1812 arch_perfmon: [X86] Force use of architectural
1813 perfmon on Intel CPUs instead of the
1814 CPU specific event set.
1816 osst= [HW,SCSI] SCSI Tape Driver
1817 Format: <buffer_size>,<write_threshold>
1818 See also Documentation/scsi/st.txt.
1820 panic= [KNL] Kernel behaviour on panic
1823 parkbd.port= [HW] Parallel port number the keyboard adapter is
1824 connected to, default is 0.
1826 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1827 0 for XT, 1 for AT (default is AT).
1830 parport= [HW,PPT] Specify parallel ports. 0 disables.
1831 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1832 Use 'auto' to force the driver to use any
1833 IRQ/DMA settings detected (the default is to
1834 ignore detected IRQ/DMA settings because of
1835 possible conflicts). You can specify the base
1836 address, IRQ, and DMA settings; IRQ and DMA
1837 should be numbers, or 'auto' (for using detected
1838 settings on that particular port), or 'nofifo'
1839 (to avoid using a FIFO even if it is detected).
1840 Parallel ports are assigned in the order they
1841 are specified on the command line, starting
1844 parport_init_mode= [HW,PPT]
1845 Configure VIA parallel port to operate in
1846 a specific mode. This is necessary on Pegasos
1847 computer where firmware has no options for setting
1848 up parallel port mode and sets it to spp.
1849 Currently this function knows 686a and 8231 chips.
1850 Format: [spp|ps2|epp|ecp|ecpepp]
1852 pas2= [HW,OSS] Format:
1853 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1856 See header of drivers/scsi/pas16.c.
1859 Halt all CPUs after the first oops has been printed for
1860 the specified number of seconds. This is to be used if
1861 your oopses keep scrolling off the screen.
1866 See header of drivers/block/paride/pcd.c.
1867 See also Documentation/blockdev/paride.txt.
1869 pci=option[,option...] [PCI] various PCI subsystem options:
1870 earlydump [X86] dump PCI config space before the kernel
1872 off [X86] don't probe for the PCI bus
1873 bios [X86-32] force use of PCI BIOS, don't access
1874 the hardware directly. Use this if your machine
1875 has a non-standard PCI host bridge.
1876 nobios [X86-32] disallow use of PCI BIOS, only direct
1877 hardware access methods are allowed. Use this
1878 if you experience crashes upon bootup and you
1879 suspect they are caused by the BIOS.
1880 conf1 [X86] Force use of PCI Configuration
1882 conf2 [X86] Force use of PCI Configuration
1884 noaer [PCIE] If the PCIEAER kernel config parameter is
1885 enabled, this kernel boot option can be used to
1886 disable the use of PCIE advanced error reporting.
1887 nodomains [PCI] Disable support for multiple PCI
1888 root domains (aka PCI segments, in ACPI-speak).
1889 nommconf [X86] Disable use of MMCONFIG for PCI
1891 check_enable_amd_mmconf [X86] check for and enable
1892 properly configured MMIO access to PCI
1893 config space on AMD family 10h CPU
1894 nomsi [MSI] If the PCI_MSI kernel config parameter is
1895 enabled, this kernel boot option can be used to
1896 disable the use of MSI interrupts system-wide.
1897 noioapicquirk [APIC] Disable all boot interrupt quirks.
1898 Safety option to keep boot IRQs enabled. This
1899 should never be necessary.
1900 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1901 primary IO-APIC for bridges that cannot disable
1902 boot IRQs. This fixes a source of spurious IRQs
1903 when the system masks IRQs.
1904 noioapicreroute [APIC] Disable workaround that uses the
1905 boot IRQ equivalent of an IRQ that connects to
1906 a chipset where boot IRQs cannot be disabled.
1907 The opposite of ioapicreroute.
1908 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1909 routing table. These calls are known to be buggy
1910 on several machines and they hang the machine
1911 when used, but on other computers it's the only
1912 way to get the interrupt routing table. Try
1913 this option if the kernel is unable to allocate
1914 IRQs or discover secondary PCI buses on your
1916 rom [X86] Assign address space to expansion ROMs.
1917 Use with caution as certain devices share
1918 address decoders between ROMs and other
1920 norom [X86] Do not assign address space to
1921 expansion ROMs that do not already have
1922 BIOS assigned address ranges.
1923 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1924 assigned automatically to PCI devices. You can
1925 make the kernel exclude IRQs of your ISA cards
1927 pirqaddr=0xAAAAA [X86] Specify the physical address
1928 of the PIRQ table (normally generated
1929 by the BIOS) if it is outside the
1930 F0000h-100000h range.
1931 lastbus=N [X86] Scan all buses thru bus #N. Can be
1932 useful if the kernel is unable to find your
1933 secondary buses and you want to tell it
1934 explicitly which ones they are.
1935 assign-busses [X86] Always assign all PCI bus
1936 numbers ourselves, overriding
1937 whatever the firmware may have done.
1938 usepirqmask [X86] Honor the possible IRQ mask stored
1939 in the BIOS $PIR table. This is needed on
1940 some systems with broken BIOSes, notably
1941 some HP Pavilion N5400 and Omnibook XE3
1942 notebooks. This will have no effect if ACPI
1943 IRQ routing is enabled.
1944 noacpi [X86] Do not use ACPI for IRQ routing
1945 or for PCI scanning.
1946 use_crs [X86] Use _CRS for PCI resource
1948 routeirq Do IRQ routing for all PCI devices.
1949 This is normally done in pci_enable_device(),
1950 so this option is a temporary workaround
1951 for broken drivers that don't call it.
1952 skip_isa_align [X86] do not align io start addr, so can
1953 handle more pci cards
1954 firmware [ARM] Do not re-enumerate the bus but instead
1955 just use the configuration from the
1956 bootloader. This is currently used on
1957 IXP2000 systems where the bus has to be
1958 configured a certain way for adjunct CPUs.
1959 noearly [X86] Don't do any early type 1 scanning.
1960 This might help on some broken boards which
1961 machine check when some devices' config space
1962 is read. But various workarounds are disabled
1963 and some IOMMU drivers will not work.
1964 bfsort Sort PCI devices into breadth-first order.
1965 This sorting is done to get a device
1966 order compatible with older (<= 2.4) kernels.
1967 nobfsort Don't sort PCI devices into breadth-first order.
1968 cbiosize=nn[KMG] The fixed amount of bus space which is
1969 reserved for the CardBus bridge's IO window.
1970 The default value is 256 bytes.
1971 cbmemsize=nn[KMG] The fixed amount of bus space which is
1972 reserved for the CardBus bridge's memory
1973 window. The default value is 64 megabytes.
1976 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1977 Specifies alignment and device to reassign
1978 aligned memory resources.
1979 If <order of align> is not specified,
1980 PAGE_SIZE is used as alignment.
1981 PCI-PCI bridge can be specified, if resource
1982 windows need to be expanded.
1983 ecrc= Enable/disable PCIe ECRC (transaction layer
1984 end-to-end CRC checking).
1985 bios: Use BIOS/firmware settings. This is the
1990 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1993 force Enable ASPM even on devices that claim not to support it.
1994 WARNING: Forcing ASPM on may cause system lockups.
1996 pcmv= [HW,PCMCIA] BadgePAD 4
1999 See Documentation/blockdev/paride.txt.
2001 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2004 See arch/parisc/kernel/pdc_chassis.c
2006 percpu_alloc= Select which percpu first chunk allocator to use.
2007 Currently supported values are "embed" and "page".
2008 Archs may support subset or none of the selections.
2009 See comments in mm/percpu.c for details on each
2010 allocator. This parameter is primarily for debugging
2011 and performance comparison.
2014 See Documentation/blockdev/paride.txt.
2017 See Documentation/blockdev/paride.txt.
2019 pirq= [SMP,APIC] Manual mp-table setup
2020 See Documentation/x86/i386/IO-APIC.txt.
2022 plip= [PPT,NET] Parallel port network link
2023 Format: { parport<nr> | timid | 0 }
2024 See also Documentation/parport.txt.
2026 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2027 Override pmtimer IOPort with a hex value.
2031 Enable PNP debug messages. This depends on the
2032 CONFIG_PNP_DEBUG_MESSAGES option.
2038 { on | off | curr | res | no-curr | no-res }
2041 [ISAPNP] Exclude IRQs for the autoconfiguration
2044 [ISAPNP] Exclude DMAs for the autoconfiguration
2046 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2047 Ranges are in pairs (I/O port base and size).
2050 [ISAPNP] Exclude memory regions for the
2052 Ranges are in pairs (memory base and size).
2054 ports= [IP_VS_FTP] IPVS ftp helper module
2056 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2058 Format: <port>,<port>....
2060 print-fatal-signals=
2061 [KNL] debug: print fatal signals
2063 If enabled, warn about various signal handling
2064 related application anomalies: too many signals,
2065 too many POSIX.1 timers, fatal signals causing a
2068 If you hit the warning due to signal overflow,
2069 you might want to try "ulimit -i unlimited".
2073 printk.time= Show timing data prefixed to each printk message line
2074 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2076 processor.max_cstate= [HW,ACPI]
2077 Limit processor to maximum C-state
2078 max_cstate=9 overrides any DMI blacklist limit.
2080 processor.nocst [HW,ACPI]
2081 Ignore the _CST method to determine C-states,
2082 instead using the legacy FADT method
2084 profile= [KNL] Enable kernel profiling via /proc/profile
2085 Format: [schedule,]<number>
2086 Param: "schedule" - profile schedule points.
2087 Param: <number> - step/bucket size as a power of 2 for
2088 statistical time based profiling.
2089 Param: "sleep" - profile D-state sleeping (millisecs).
2090 Requires CONFIG_SCHEDSTATS
2091 Param: "kvm" - profile VM exits.
2093 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2095 See Documentation/blockdev/ramdisk.txt.
2097 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2098 probe for; one of (bare|imps|exps|lifebook|any).
2099 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2101 psmouse.resetafter= [HW,MOUSE]
2102 Try to reset the device after so many bad packets
2105 [HW,MOUSE] Set desired mouse resolution, in dpi.
2106 psmouse.smartscroll=
2107 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2108 0 = disabled, 1 = enabled (default).
2110 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2112 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2115 See Documentation/blockdev/paride.txt.
2118 [KNL] Number of legacy pty's. Overwrites compiled-in
2121 quiet [KNL] Disable most log messages
2126 See Documentation/md.txt.
2128 ramdisk_blocksize= [RAM]
2129 See Documentation/blockdev/ramdisk.txt.
2131 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2132 See Documentation/blockdev/ramdisk.txt.
2134 rcupdate.blimit= [KNL,BOOT]
2135 Set maximum number of finished RCU callbacks to process
2138 rcupdate.qhimark= [KNL,BOOT]
2139 Set threshold of queued
2140 RCU callbacks over which batch limiting is disabled.
2142 rcupdate.qlowmark= [KNL,BOOT]
2143 Set threshold of queued RCU callbacks below which
2144 batch limiting is re-enabled.
2148 Run specified binary instead of /init from the ramdisk,
2149 used for early userspace startup. See initrd.
2151 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2152 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2153 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2156 [KNL, SMP] Set scheduler's default relax_domain_level.
2157 See Documentation/cgroups/cpusets.txt.
2159 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2161 reservetop= [X86-32]
2163 Reserves a hole at the top of the kernel virtual
2166 reset_devices [KNL] Force drivers to reset the underlying device
2167 during initialization.
2170 Specify the partition device for software suspend
2172 resume_offset= [SWSUSP]
2173 Specify the offset from the beginning of the partition
2174 given by "resume=" at which the swap header is located,
2175 in <PAGE_SIZE> units (needed only for swap files).
2176 See Documentation/power/swsusp-and-swap-files.txt
2178 retain_initrd [RAM] Keep initrd memory after extraction
2180 rhash_entries= [KNL,NET]
2181 Set number of hash buckets for route cache
2183 riscom8= [HW,SERIAL]
2184 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2186 ro [KNL] Mount root device read-only on boot
2188 root= [KNL] Root filesystem
2190 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2191 mount the root filesystem
2193 rootflags= [KNL] Set root filesystem mount option string
2195 rootfstype= [KNL] Set root filesystem type
2197 rootwait [KNL] Wait (indefinitely) for root device to show up.
2198 Useful for devices that are detected asynchronously
2199 (e.g. USB and MMC devices).
2201 rw [KNL] Mount root device read-write on boot
2203 S [KNL] Run init in single mode
2206 See drivers/net/irda/sa1100_ir.c.
2208 sbni= [NET] Granch SBNI12 leased line adapter
2210 sched_debug [KNL] Enables verbose scheduler debug messages.
2212 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2213 Format: <io>[,<timeout>[,<isapnp>]]
2215 scsi_debug_*= [SCSI]
2216 See drivers/scsi/scsi_debug.c.
2218 scsi_default_dev_flags=
2219 [SCSI] SCSI default device flags
2222 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2223 Format: <vendor>:<model>:<flags>
2224 (flags are integer value)
2226 scsi_logging_level= [SCSI] a bit mask of logging levels
2227 See drivers/scsi/scsi_logging.h for bits. Also
2228 settable via sysctl at dev.scsi.logging_level
2229 (/proc/sys/dev/scsi/logging_level).
2230 There is also a nice 'scsi_logging_level' script in the
2231 S390-tools package, available for download at
2232 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2234 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2235 discovered. async scans them in kernel threads,
2236 allowing boot to proceed. none ignores them, expecting
2237 user space to do the scan.
2239 security= [SECURITY] Choose a security module to enable at boot.
2240 If this boot parameter is not specified, only the first
2241 security module asking for security registration will be
2242 loaded. An invalid security module name will be treated
2243 as if no module has been chosen.
2245 selinux= [SELINUX] Disable or enable SELinux at boot time.
2246 Format: { "0" | "1" }
2247 See security/selinux/Kconfig help text.
2250 Default value is set via kernel config option.
2251 If enabled at boot time, /selinux/disable can be used
2252 later to disable prior to initial policy load.
2254 serialnumber [BUGS=X86-32]
2257 Maximal number of shapers.
2259 show_msr= [x86] show boot-time MSR settings
2260 Format: { <integer> }
2261 Show boot-time (BIOS-initialized) MSR settings.
2262 The parameter means the number of CPUs to show,
2263 for example 1 means boot CPU only.
2266 See header of drivers/scsi/sim710.c.
2273 slub_debug[=options[,slabs]] [MM, SLUB]
2274 Enabling slub_debug allows one to determine the
2275 culprit if slab objects become corrupted. Enabling
2276 slub_debug can create guard zones around objects and
2277 may poison objects when not in use. Also tracks the
2278 last alloc / free. For more information see
2279 Documentation/vm/slub.txt.
2281 slub_max_order= [MM, SLUB]
2282 Determines the maximum allowed order for slabs.
2283 A high setting may cause OOMs due to memory
2284 fragmentation. For more information see
2285 Documentation/vm/slub.txt.
2287 slub_min_objects= [MM, SLUB]
2288 The minimum number of objects per slab. SLUB will
2289 increase the slab order up to slub_max_order to
2290 generate a sufficiently large slab able to contain
2291 the number of objects indicated. The higher the number
2292 of objects the smaller the overhead of tracking slabs
2293 and the less frequently locks need to be acquired.
2294 For more information see Documentation/vm/slub.txt.
2296 slub_min_order= [MM, SLUB]
2297 Determines the mininum page order for slabs. Must be
2298 lower than slub_max_order.
2299 For more information see Documentation/vm/slub.txt.
2301 slub_nomerge [MM, SLUB]
2302 Disable merging of slabs with similar size. May be
2303 necessary if there is some reason to distinguish
2304 allocs to different slabs. Debug options disable
2305 merging on their own.
2306 For more information see Documentation/vm/slub.txt.
2309 Format: <io1>[,<io2>[,...,<io8>]]
2311 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2312 attempt to substitute SMP alternatives once at boot.
2314 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2315 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2316 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2317 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2318 smsc-ircc2.ircc_irq= [HW] IRQ line
2319 smsc-ircc2.ircc_dma= [HW] DMA channel
2320 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2321 0: Toshiba Satellite 1800 (GP data pin select)
2322 1: Fast pin select (default)
2325 snd-ad1816a= [HW,ALSA]
2327 snd-ad1848= [HW,ALSA]
2329 snd-ali5451= [HW,ALSA]
2331 snd-als100= [HW,ALSA]
2333 snd-als4000= [HW,ALSA]
2335 snd-azt2320= [HW,ALSA]
2337 snd-cmi8330= [HW,ALSA]
2339 snd-cmipci= [HW,ALSA]
2341 snd-cs4231= [HW,ALSA]
2343 snd-cs4232= [HW,ALSA]
2345 snd-cs4236= [HW,ALSA]
2347 snd-cs4281= [HW,ALSA]
2349 snd-cs46xx= [HW,ALSA]
2351 snd-dt019x= [HW,ALSA]
2353 snd-dummy= [HW,ALSA]
2355 snd-emu10k1= [HW,ALSA]
2357 snd-ens1370= [HW,ALSA]
2359 snd-ens1371= [HW,ALSA]
2361 snd-es968= [HW,ALSA]
2363 snd-es1688= [HW,ALSA]
2365 snd-es18xx= [HW,ALSA]
2367 snd-es1938= [HW,ALSA]
2369 snd-es1968= [HW,ALSA]
2371 snd-fm801= [HW,ALSA]
2373 snd-gusclassic= [HW,ALSA]
2375 snd-gusextreme= [HW,ALSA]
2377 snd-gusmax= [HW,ALSA]
2381 snd-ice1712= [HW,ALSA]
2383 snd-intel8x0= [HW,ALSA]
2385 snd-interwave= [HW,ALSA]
2390 snd-korg1212= [HW,ALSA]
2392 snd-maestro3= [HW,ALSA]
2394 snd-mpu401= [HW,ALSA]
2396 snd-mtpav= [HW,ALSA]
2398 snd-nm256= [HW,ALSA]
2400 snd-opl3sa2= [HW,ALSA]
2408 snd-opti93x= [HW,ALSA]
2412 snd-rme32= [HW,ALSA]
2414 snd-rme96= [HW,ALSA]
2416 snd-rme9652= [HW,ALSA]
2422 snd-sbawe= [HW,ALSA]
2424 snd-serial= [HW,ALSA]
2426 snd-sgalaxy= [HW,ALSA]
2428 snd-sonicvibes= [HW,ALSA]
2433 snd-sun-cs4231= [HW,ALSA]
2435 snd-trident= [HW,ALSA]
2437 snd-usb-audio= [HW,ALSA,USB]
2439 snd-via82xx= [HW,ALSA]
2441 snd-virmidi= [HW,ALSA]
2443 snd-wavefront= [HW,ALSA]
2445 snd-ymfpci= [HW,ALSA]
2448 [KNL] Should the soft-lockup detector generate panics.
2450 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2451 See Documentation/sonypi.txt
2453 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2454 See Documentation/serial/specialix.txt.
2456 spia_io_base= [HW,MTD]
2462 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2464 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2465 See Documentation/scsi/st.txt.
2468 Enabled the stack tracer on boot up.
2472 Set the STI (builtin display/keyboard on the HP-PARISC
2473 machines) console (graphic card) which should be used
2474 as the initial boot-console.
2475 See also comment in drivers/video/console/sticore.c.
2478 See comment in drivers/video/console/sticore.c.
2481 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2483 sunrpc.min_resvport=
2484 sunrpc.max_resvport=
2486 SunRPC servers often require that client requests
2487 originate from a privileged port (i.e. a port in the
2488 range 0 < portnr < 1024).
2489 An administrator who wishes to reserve some of these
2490 ports for other uses may adjust the range that the
2491 kernel's sunrpc client considers to be privileged
2492 using these two parameters to set the minimum and
2493 maximum port values.
2497 Control how the NFS server code allocates CPUs to
2498 service thread pools. Depending on how many NICs
2499 you have and where their interrupts are bound, this
2500 option will affect which CPUs will do NFS serving.
2501 Note: this parameter cannot be changed while the
2502 NFS server is running.
2504 auto the server chooses an appropriate mode
2505 automatically using heuristics
2506 global a single global pool contains all CPUs
2507 percpu one pool for each CPU
2508 pernode one pool for each NUMA node (equivalent
2509 to global on non-NUMA machines)
2511 sunrpc.tcp_slot_table_entries=
2512 sunrpc.udp_slot_table_entries=
2514 Sets the upper limit on the number of simultaneous
2515 RPC calls that can be sent from the client to a
2516 server. Increasing these values may allow you to
2517 improve throughput, but will also increase the
2518 amount of memory reserved for use by the client.
2520 swiotlb= [IA-64] Number of I/O TLB slabs
2524 sym53c416= [HW,SCSI]
2525 See header of drivers/scsi/sym53c416.c.
2527 sysrq_always_enabled
2529 Ignore sysrq setting - this boot parameter will
2530 neutralize any effect of /proc/sys/kernel/sysrq.
2531 Useful for debugging.
2534 See header of drivers/scsi/t128.c.
2538 test_suspend= [SUSPEND]
2539 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2540 standby suspend) as the system sleep state to briefly
2541 enter during system startup. The system is woken from
2542 this state using a wakeup-capable RTC alarm.
2544 thash_entries= [KNL,NET]
2545 Set number of hash buckets for TCP connection
2547 thermal.act= [HW,ACPI]
2548 -1: disable all active trip points in all thermal zones
2549 <degrees C>: override all lowest active trip points
2551 thermal.crt= [HW,ACPI]
2552 -1: disable all critical trip points in all thermal zones
2553 <degrees C>: override all critical trip points
2555 thermal.nocrt= [HW,ACPI]
2556 Set to disable actions on ACPI thermal zone
2557 critical and hot trip points.
2559 thermal.off= [HW,ACPI]
2560 1: disable ACPI thermal control
2562 thermal.psv= [HW,ACPI]
2563 -1: disable all passive trip points
2564 <degrees C>: override all passive trip points to this
2567 thermal.tzp= [HW,ACPI]
2568 Specify global default ACPI thermal zone polling rate
2569 <deci-seconds>: poll all this frequency
2570 0: no polling (default)
2573 See comment before function dc390_setup() in
2574 drivers/scsi/tmscsim.c.
2578 Specify if the kernel should make use of the cpu
2579 topology informations if the hardware supports these.
2580 The scheduler will make use of these informations and
2581 e.g. base its process migration decisions on it.
2586 trace_buf_size=nn[KMG]
2587 [FTRACE] will set tracing buffer size.
2589 trace_event=[event-list]
2590 [FTRACE] Set and start specified trace events in order
2591 to facilitate early boot debugging.
2592 See also Documentation/trace/events.txt
2594 trix= [HW,OSS] MediaTrix AudioTrix Pro
2596 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2598 tsc= Disable clocksource-must-verify flag for TSC.
2600 [x86] reliable: mark tsc clocksource as reliable, this
2601 disables clocksource verification at runtime.
2602 Used to enable high-resolution timer mode on older
2603 hardware, and in virtualized environment.
2605 turbografx.map[2|3]= [HW,JOY]
2606 TurboGraFX parallel port interface
2608 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2609 See also Documentation/input/joystick-parport.txt
2611 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2612 See header of drivers/scsi/u14-34f.c.
2620 uhash_entries= [KNL,NET]
2621 Set number of hash buckets for UDP/UDP-Lite connections
2624 [USB] Ignore overcurrent events (default N).
2625 Some badly-designed motherboards generate lots of
2626 bogus events, for ports that aren't wired to
2627 anything. Set this parameter to avoid log spamming.
2628 Note that genuine overcurrent events won't be
2633 Set unknown_nmi_panic=1 early on boot.
2635 usbcore.autosuspend=
2636 [USB] The autosuspend time delay (in seconds) used
2637 for newly-detected USB devices (default 2). This
2638 is the time required before an idle device will be
2639 autosuspended. Devices for which the delay is set
2640 to a negative value won't be autosuspended at all.
2642 usbcore.usbfs_snoop=
2643 [USB] Set to log all usbfs traffic (default 0 = off).
2645 usbcore.blinkenlights=
2646 [USB] Set to cycle leds on hubs (default 0 = off).
2648 usbcore.old_scheme_first=
2649 [USB] Start with the old device initialization
2650 scheme (default 0 = off).
2652 usbcore.use_both_schemes=
2653 [USB] Try the other device initialization scheme
2654 if the first one fails (default 1 = enabled).
2656 usbcore.initial_descriptor_timeout=
2657 [USB] Specifies timeout for the initial 64-byte
2658 USB_REQ_GET_DESCRIPTOR request in milliseconds
2659 (default 5000 = 5.0 seconds).
2662 [USBHID] The interval which mice are to be polled at.
2664 usb-storage.delay_use=
2665 [UMS] The delay in seconds before a new device is
2666 scanned for Logical Units (default 5).
2669 [UMS] A list of quirks entries to supplement or
2670 override the built-in unusual_devs list. List
2671 entries are separated by commas. Each entry has
2672 the form VID:PID:Flags where VID and PID are Vendor
2673 and Product ID values (4-digit hex numbers) and
2674 Flags is a set of characters, each corresponding
2675 to a common usb-storage quirk flag as follows:
2676 a = SANE_SENSE (collect more than 18 bytes
2678 b = BAD_SENSE (don't collect more than 18
2679 bytes of sense data);
2680 c = FIX_CAPACITY (decrease the reported
2681 device capacity by one sector);
2682 h = CAPACITY_HEURISTICS (decrease the
2683 reported device capacity by one
2684 sector if the number is odd);
2685 i = IGNORE_DEVICE (don't bind to this
2687 l = NOT_LOCKABLE (don't try to lock and
2688 unlock ejectable media);
2689 m = MAX_SECTORS_64 (don't transfer more
2690 than 64 sectors = 32 KB at a time);
2691 o = CAPACITY_OK (accept the capacity
2692 reported by the device);
2693 r = IGNORE_RESIDUE (the device reports
2694 bogus residue values);
2695 s = SINGLE_LUN (the device has only one
2697 w = NO_WP_DETECT (don't test whether the
2698 medium is write-protected).
2699 Example: quirks=0419:aaf5:rl,0421:0433:rc
2702 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2703 vdso=1: enable VDSO (default)
2704 vdso=0: disable VDSO mapping
2707 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2708 vdso32=1: enable 32-bit VDSO (default)
2709 vdso32=0: disable 32-bit VDSO mapping
2712 vector=percpu: enable percpu vector domain
2714 video= [FB] Frame buffer configuration
2715 See Documentation/fb/modedb.txt.
2717 vga= [BOOT,X86-32] Select a particular video mode
2718 See Documentation/x86/boot.txt and
2719 Documentation/svga.txt.
2720 Use vga=ask for menu.
2721 This is actually a boot loader parameter; the value is
2722 passed to the kernel using a special protocol.
2724 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2725 size of <nn>. This can be used to increase the
2726 minimum size (128MB on x86). It can also be used to
2727 decrease the size and leave more room for directly
2730 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2733 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2736 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2739 vt.cur_default= [VT] Default cursor shape.
2740 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2741 the parameters of the <Esc>[?A;B;Cc escape sequence;
2742 see VGA-softcursor.txt. Default: 2 = underline.
2744 vt.default_blu= [VT]
2745 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2746 Change the default blue palette of the console.
2747 This is a 16-member array composed of values
2750 vt.default_grn= [VT]
2751 Format: <green0>,<green1>,<green2>,...,<green15>
2752 Change the default green palette of the console.
2753 This is a 16-member array composed of values
2756 vt.default_red= [VT]
2757 Format: <red0>,<red1>,<red2>,...,<red15>
2758 Change the default red palette of the console.
2759 This is a 16-member array composed of values
2765 Set system-wide default UTF-8 mode for all tty's.
2766 Default is 1, i.e. UTF-8 mode is enabled for all
2767 newly opened terminals.
2769 vt.global_cursor_default=
2772 Set system-wide default for whether a cursor
2773 is shown on new VTs. Default is -1,
2774 i.e. cursors will be created by default unless
2775 overridden by individual drivers. 0 will hide
2776 cursors, 1 will display them.
2778 waveartist= [HW,OSS]
2779 Format: <io>,<irq>,<dma>,<dma2>
2782 See header of drivers/scsi/wd33c93.c.
2785 See header of drivers/scsi/wd7000.c.
2788 See Documentation/watchdog/wdt.txt.
2790 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2791 default x2apic cluster mode on platforms
2794 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2795 xd_geo= See header of drivers/block/xd.c.
2797 xirc2ps_cs= [NET,PCMCIA]
2799 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2801 ______________________________________________________________________
2805 Add documentation for ALSA options.
2806 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob