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_irq_balance [HW,ACPI]
203 ACPI will balance active IRQs
206 acpi_irq_nobalance [HW,ACPI]
207 ACPI will not move active IRQs (default)
210 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
211 Format: <irq>,<irq>...
213 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
215 Format: <irq>,<irq>...
217 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
219 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
220 Format: To spoof as Windows 98: ="Microsoft Windows"
222 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
223 acpi_osi="string1" # add string1 -- only one string
224 acpi_osi="!string2" # remove built-in string2
225 acpi_osi= # disable all strings
228 Override the pmtimer bug detection: force the kernel
229 to assume that this machine's pmtimer latches its value
230 and always returns good values.
232 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
233 Format: { level | edge | high | low }
235 acpi_serialize [HW,ACPI] force serialization of AML methods
237 acpi_skip_timer_override [HW,ACPI]
238 Recognize and ignore IRQ0/pin2 Interrupt Override.
239 For broken nForce2 BIOS resulting in XT-PIC timer.
241 acpi_sleep= [HW,ACPI] Sleep options
242 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
243 old_ordering, s4_nonvs }
244 See Documentation/power/video.txt for information on
246 s3_beep is for debugging; it makes the PC's speaker beep
247 as soon as the kernel's real-mode entry point is called.
248 s4_nohwsig prevents ACPI hardware signature from being
249 used during resume from hibernation.
250 old_ordering causes the ACPI 1.0 ordering of the _PTS
251 control method, with respect to putting devices into
252 low power states, to be enforced (the ACPI 2.0 ordering
253 of _PTS is used by default).
254 s4_nonvs prevents the kernel from saving/restoring the
255 ACPI NVS memory during hibernation.
257 acpi_use_timer_override [HW,ACPI]
258 Use timer override. For some broken Nvidia NF5 boards
259 that require a timer override, but don't have HPET
261 acpi_enforce_resources= [ACPI]
262 { strict | lax | no }
263 Check for resource conflicts between native drivers
264 and ACPI OperationRegions (SystemIO and SystemMemory
265 only). IO ports and memory declared in ACPI might be
266 used by the ACPI subsystem in arbitrary AML code and
267 can interfere with legacy drivers.
268 strict (default): access to resources claimed by ACPI
269 is denied; legacy drivers trying to access reserved
270 resources will fail to bind to device using them.
271 lax: access to resources claimed by ACPI is allowed;
272 legacy drivers trying to access reserved resources
273 will bind successfully but a warning message is logged.
274 no: ACPI OperationRegions are not marked as reserved,
275 no further checks are performed.
278 Format: <io>,<irq>,<dma>,<dma2>,<type>
280 add_efi_memmap [EFI; X86] Include EFI memory map in
281 kernel's map of available physical RAM.
284 See header of drivers/scsi/advansys.c.
286 advwdt= [HW,WDT] Advantech WDT
287 Format: <iostart>,<iostop>
289 aedsp16= [HW,OSS] Audio Excel DSP 16
290 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
291 See also header of sound/oss/aedsp16.c.
294 { off | try_unsupported }
295 off: disable AGP support
296 try_unsupported: try to drive unsupported chipsets
297 (may crash computer or cause data corruption)
300 See Documentation/scsi/aha152x.txt.
303 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
306 See Documentation/scsi/aic7xxx.txt.
309 See Documentation/scsi/aic79xx.txt.
311 amd_iommu= [HW,X86-84]
312 Pass parameters to the AMD IOMMU driver in the system.
314 isolate - enable device isolation (each device, as far
315 as possible, will get its own protection
317 share - put every device behind one IOMMU into the
318 same protection domain
319 fullflush - enable flushing of IO/TLB entries when
320 they are unmapped. Otherwise they are
321 flushed before they will be reused, which
324 amijoy.map= [HW,JOY] Amiga joystick support
325 Map of devices attached to JOY0DAT and JOY1DAT
327 See also Documentation/kernel/input/joystick.txt
329 analog.map= [HW,JOY] Analog joystick and gamepad support
330 Specifies type or capabilities of an analog joystick
331 connected to one of 16 gameports
332 Format: <type1>,<type2>,..<type16>
335 Power management functions (SPARCstation-4/5 + deriv.)
337 Disable APC CPU standby support. SPARCstation-Fox does
338 not play well with APC CPU idle - disable it if you have
339 APC and your system crashes randomly.
341 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
342 Change the output verbosity whilst booting
343 Format: { quiet (default) | verbose | debug }
344 Change the amount of debugging information output
345 when initialising the APIC and IO-APIC components.
347 apm= [APM] Advanced Power Management
348 See header of arch/x86/kernel/apm_32.c.
350 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
351 Format: <io>,<irq>,<nodeID>
355 atarimouse= [HW,MOUSE] Atari Mouse
357 atascsi= [HW,SCSI] Atari SCSI
359 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
360 EzKey and similar keyboards
362 atkbd.reset= [HW] Reset keyboard during initialization
364 atkbd.set= [HW] Select keyboard code set
365 Format: <int> (2 = AT (default), 3 = PS/2)
367 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
370 atkbd.softraw= [HW] Choose between synthetic and real raw mode
371 Format: <bool> (0 = real, 1 = synthetic (default))
373 atkbd.softrepeat= [HW]
374 Use software keyboard repeat
378 baycom_epp= [HW,AX25]
381 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
383 See header of drivers/net/hamradio/baycom_par.c.
385 baycom_ser_fdx= [HW,AX25]
386 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
387 Format: <io>,<irq>,<mode>[,<baud>]
388 See header of drivers/net/hamradio/baycom_ser_fdx.c.
390 baycom_ser_hdx= [HW,AX25]
391 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
392 Format: <io>,<irq>,<mode>
393 See header of drivers/net/hamradio/baycom_ser_hdx.c.
395 boot_delay= Milliseconds to delay each printk during boot.
396 Values larger than 10 seconds (10000) are changed to
400 bootmem_debug [KNL] Enable bootmem allocator debug messages.
402 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
403 bttv.radio= Most important insmod options are available as
405 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
406 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
409 See drivers/scsi/BusLogic.c, comment before function
410 BusLogic_ParseDriverOptions().
412 c101= [NET] Moxa C101 synchronous serial card
414 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
415 Sometimes CPU hardware bugs make them report the cache
416 size incorrectly. The kernel will attempt work arounds
417 to fix known problems, but for some CPUs it is not
418 possible to determine what the correct size should be.
419 This option provides an override for these situations.
422 [SECURITY] Disable capabilities. This would normally
423 be used only if an alternative security model is to be
424 configured. Potentially dangerous and should only be
425 used if you are entirely sure of the consequences.
427 ccw_timeout_log [S390]
428 See Documentation/s390/CommonIO for details.
430 cgroup_disable= [KNL] Disable a particular controller
431 Format: {name of the controller(s) to disable}
432 {Currently supported controllers - "memory"}
434 checkreqprot [SELINUX] Set initial checkreqprot flag value.
435 Format: { "0" | "1" }
436 See security/selinux/Kconfig help text.
437 0 -- check protection applied by kernel (includes
438 any implied execute protection).
439 1 -- check protection requested by application.
440 Default value is set via a kernel config option.
441 Value can be changed at runtime via
442 /selinux/checkreqprot.
445 See Documentation/s390/CommonIO for details.
447 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
449 Forces specified clocksource (if available) to be used
450 when calculating gettimeofday(). If specified
451 clocksource is not available, it defaults to PIT.
452 Format: { pit | tsc | cyclone | pmtmr }
454 clocksource= [GENERIC_TIME] Override the default clocksource
456 Override the default clocksource and use the clocksource
457 with the name specified.
458 Some clocksource names to choose from, depending on
460 [all] jiffies (this is the base, fallback clocksource)
462 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
463 pxa_timer,timer3,32k_counter,timer0_1
465 [X86-32] pit,hpet,tsc,vmi-timer;
466 scx200_hrt on Geode; cyclone on IBM x440
474 clearcpuid=BITNUM [X86]
475 Disable CPUID feature X for the kernel. See
476 arch/x86/include/asm/cpufeature.h for the valid bit
477 numbers. Note the Linux specific bits are not necessarily
478 stable over kernel options, but the vendor specific
480 Also note that user programs calling CPUID directly
481 or using the feature without checking anything
482 will still see it. This just prevents it from
483 being used by the kernel or shown in /proc/cpuinfo.
484 Also note the kernel might malfunction if you disable
487 cmo_free_hint= [PPC] Format: { yes | no }
488 Specify whether pages are marked as being inactive
489 when they are freed. This is used in CMO environments
490 to determine OS memory pressure for page stealing by
494 code_bytes [X86] How many bytes of object code to print
499 com20020= [HW,NET] ARCnet - COM20020 chipset
501 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
503 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
507 ARCnet - COM90xx chipset (memory-mapped buffers)
508 Format: <io>[,<irq>[,<memstart>]]
510 condev= [HW,S390] console device
513 console= [KNL] Output console device and options.
515 tty<n> Use the virtual console device <n>.
519 Use the specified serial port. The options are of
520 the form "bbbbpnf", where "bbbb" is the baud rate,
521 "p" is parity ("n", "o", or "e"), "n" is number of
522 bits, and "f" is flow control ("r" for RTS or
523 omit it). Default is "9600n8".
525 See Documentation/serial-console.txt for more
527 Documentation/networking/netconsole.txt for an
530 uart[8250],io,<addr>[,options]
531 uart[8250],mmio,<addr>[,options]
532 Start an early, polled-mode console on the 8250/16550
533 UART at the specified I/O port or MMIO address,
534 switching to the matching ttyS device later. The
535 options are the same as for ttyS, above.
537 If the device connected to the port is not a TTY but a braille
538 device, prepend "brl," before the device type, for instance
540 For now, only VisioBraille is supported.
542 consoleblank= [KNL] The console blank (screen saver) timeout in
543 seconds. Defaults to 10*60 = 10mins. A value of 0
544 disables the blank timer.
547 [KNL] Change the default value for
548 /proc/<pid>/coredump_filter.
549 See also Documentation/filesystems/proc.txt.
551 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
553 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
555 crashkernel=nn[KMG]@ss[KMG]
556 [KNL] Reserve a chunk of physical memory to
557 hold a kernel to switch to with kexec on panic.
559 crashkernel=range1:size1[,range2:size2,...][@offset]
560 [KNL] Same as above, but depends on the memory
561 in the running system. The syntax of range is
562 start-[end] where start and end are both
563 a memory unit (amount[KMG]). See also
564 Documentation/kdump/kdump.txt for a example.
569 cs89x0_media= [HW,NET]
570 Format: { rj45 | aui | bnc }
573 See header of drivers/s390/block/dasd_devmap.c.
575 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
576 (one device per port)
577 Format: <port#>,<type>
578 See also Documentation/input/joystick-parport.txt
580 debug [KNL] Enable kernel debugging (events log level).
583 [KNL] verbose self-tests
585 Print debugging info while doing the locking API
587 We default to 0 (no extra messages), setting it to
588 1 will print _a lot_ more information - normally
589 only useful to kernel developers.
591 debug_objects [KNL] Enable object debugging
594 [KNL] Disable object debugging
596 debugpat [X86] Enable PAT debugging
598 decnet.addr= [HW,NET]
599 Format: <area>[,<node>]
600 See also Documentation/networking/decnet.txt.
603 [same as hugepagesz=] The size of the default
604 HugeTLB page size. This is the size represented by
605 the legacy /proc/ hugepages APIs, used for SHM, and
606 default size when mounting hugetlbfs filesystems.
607 Defaults to the default architecture's huge page size
611 Set number of hash buckets for dentry cache.
614 IO parameters + enable/disable command.
616 digiepca= [HW,SERIAL]
617 See drivers/char/README.epca and
618 Documentation/serial/digiepca.txt.
620 disable_mtrr_cleanup [X86]
621 The kernel tries to adjust MTRR layout from continuous
622 to discrete, to make X server driver able to add WB
623 entry later. This parameter disables that.
625 disable_mtrr_trim [X86, Intel and AMD only]
626 By default the kernel will trim any uncacheable
627 memory out of your available memory pool based on
628 MTRR settings. This parameter disables that behavior,
629 possibly causing your machine to run very slowly.
631 disable_timer_pin_1 [X86]
632 Disable PIN 1 of APIC timer
633 Can be useful to work around chipset bugs.
635 dmasound= [HW,OSS] Sound subsystem buffers
637 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
638 this option disables the debugging code at boot.
640 dma_debug_entries=<number>
641 This option allows to tune the number of preallocated
642 entries for DMA-API debugging code. One entry is
643 required per DMA-API allocation. Use this if the
644 DMA-API debugging code disables itself because the
645 architectural default is too low.
647 dma_debug_driver=<driver_name>
648 With this option the DMA-API debugging driver
649 filter feature can be enabled at boot time. Just
650 pass the driver to filter for as the parameter.
651 The filter can be disabled or changed to another
652 driver later using sysfs.
658 dynamic_printk Enables pr_debug()/dev_dbg() calls if
659 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
660 These can also be switched on/off via
661 <debugfs>/dynamic_printk/modules
663 earlycon= [KNL] Output early console device and options.
664 uart[8250],io,<addr>[,options]
665 uart[8250],mmio,<addr>[,options]
666 Start an early, polled-mode console on the 8250/16550
667 UART at the specified I/O port or MMIO address.
668 The options are the same as for ttyS, above.
670 earlyprintk= [X86,SH,BLACKFIN]
672 earlyprintk=serial[,ttySn[,baudrate]]
673 earlyprintk=dbgp[debugController#]
675 Append ",keep" to not disable it when the real console
678 Only vga or serial or usb debug port at a time.
680 Currently only ttyS0 and ttyS1 are supported.
682 Interaction with the standard serial driver is not
685 The VGA output is eventually overwritten by the real
691 Format: {"off" | "on" | "skip[mbr]"}
693 eisa_irq_edge= [PARISC,HW]
694 See header of drivers/parisc/eisa.c.
697 See comment before function elanfreq_setup() in
698 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
701 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
702 See Documentation/block/as-iosched.txt and
703 Documentation/block/deadline-iosched.txt for details.
705 elfcorehdr= [IA64,PPC,SH,X86]
706 Specifies physical address of start of kernel core
707 image elf header. Generally kexec loader will
708 pass this option to capture kernel.
709 See Documentation/kdump/kdump.txt for details.
711 enable_mtrr_cleanup [X86]
712 The kernel tries to adjust MTRR layout from continuous
713 to discrete, to make X server driver able to add WB
714 entry later. This parameter enables that.
716 enable_timer_pin_1 [X86]
717 Enable PIN 1 of APIC timer
718 Can be useful to work around chipset bugs
719 (in particular on some ATI chipsets).
720 The kernel tries to set a reasonable default.
722 enforcing [SELINUX] Set initial enforcing status.
724 See security/selinux/Kconfig help text.
725 0 -- permissive (log only, no denials).
726 1 -- enforcing (deny and log).
728 Value can be changed at runtime via /selinux/enforce.
730 ether= [HW,NET] Ethernet cards parameters
731 This option is obsoleted by the "netdev=" option, which
732 has equivalent usage. See its documentation for details.
734 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
739 fail_make_request=[KNL]
740 General fault injection mechanism.
741 Format: <interval>,<probability>,<space>,<times>
742 See also /Documentation/fault-injection/.
745 See header of drivers/scsi/fd_mcs.c.
748 See header of drivers/scsi/fdomain.c.
751 See Documentation/blockdev/floppy.txt.
753 force_pal_cache_flush
754 [IA-64] Avoid check_sal_cache_flush which may hang on
755 buggy SAL_CACHE_FLUSH implementations. Using this
756 parameter will force ia64_sal_cache_flush to call
757 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
760 [FTRACE] will set and start the specified tracer
761 as early as possible in order to facilitate early
765 [FTRACE] will dump the trace buffers on oops.
767 ftrace_filter=[function-list]
768 [FTRACE] Limit the functions traced by the function
769 tracer at boot up. function-list is a comma separated
770 list of functions. This list can be changed at run
771 time by the set_ftrace_filter file in the debugfs
774 ftrace_notrace=[function-list]
775 [FTRACE] Do not trace the functions specified in
776 function-list. This list can be changed at run time
777 by the set_ftrace_notrace file in the debugfs
781 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
782 support via parallel port (up to 5 devices per port)
783 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
784 See also Documentation/input/joystick-parport.txt
788 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
792 gcov_persist= [GCOV] When non-zero (default), profiling data for
793 kernel modules is saved and remains accessible via
794 debugfs, even when the module is unloaded/reloaded.
795 When zero, profiling data is discarded and associated
796 debugfs files are removed at module unload time.
799 See header of drivers/scsi/gdth.c.
801 gpt [EFI] Forces disk with valid GPT signature but
802 invalid Protective MBR to be treated as GPT.
806 hashdist= [KNL,NUMA] Large hashes allocated during boot
807 are distributed across NUMA nodes. Defaults on
808 for 64bit NUMA, off otherwise.
809 Format: 0 | 1 (for off | on)
811 hcl= [IA-64] SGI's Hardware Graph compatibility layer
813 hd= [EIDE] (E)IDE hard drive subsystem geometry
814 Format: <cyl>,<head>,<sect>
816 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
817 size of <nn>. This works even on boxes that have no
818 highmem otherwise. This also works to reduce highmem
819 size on bigger boxes.
821 highres= [KNL] Enable/disable high resolution timer mode.
822 Valid parameters: "on", "off"
826 See Documentation/isdn/README.HiSax.
830 hpet= [X86-32,HPET] option to control HPET usage
831 Format: { enable (default) | disable | force |
833 disable: disable HPET and use PIT instead
834 force: allow force enabled of undocumented chips (ICH4,
836 verbose: show contents of HPET registers during setup
838 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
839 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
840 On x86-64 and powerpc, this option can be specified
841 multiple times interleaved with hugepages= to reserve
842 huge pages of different sizes. Valid pages sizes on
843 x86-64 are 2M (when the CPU supports "pse") and 1G
844 (when the CPU supports the "pdpe1gb" cpuinfo flag)
845 Note that 1GB pages can only be allocated at boot time
846 using hugepages= and not freed afterwards.
848 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
849 terminal devices. Valid values: 0..8
850 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
851 If specified, z/VM IUCV HVC accepts connections
852 from listed z/VM user IDs only.
854 i2c_bus= [HW] Override the default board specific I2C bus speed
855 or register an additional I2C bus that is not
856 registered from board initialization code.
860 i8042.debug [HW] Toggle i8042 debug mode
861 i8042.direct [HW] Put keyboard port into non-translated mode
862 i8042.dumbkbd [HW] Pretend that controller can only read data from
863 keyboard and cannot control its state
864 (Don't attempt to blink the leds)
865 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
866 i8042.nokbd [HW] Don't check/create keyboard port
867 i8042.noloop [HW] Disable the AUX Loopback command while probing
869 i8042.nomux [HW] Don't check presence of an active multiplexing
871 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
874 [HW] Frequency with which keyboard LEDs should blink
875 when kernel panics (default is 0.5 sec)
876 i8042.reset [HW] Reset the controller during init and cleanup
877 i8042.unlock [HW] Unlock (ignore) the keylock
881 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
882 indicates that the driver is running on unsupported
884 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
885 does not match list of supported models.
887 [HW] Report power status in /proc/i8k
888 (disabled by default)
889 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
892 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
893 See Documentation/mca.txt.
896 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
898 ide-core.nodma= [HW] (E)IDE subsystem
899 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
900 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
901 .cdrom .chs .ignore_cable are additional options
902 See Documentation/ide/ide.txt.
904 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
905 Claim all unknown PCI IDE storage controllers.
908 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
909 Poll forces a polling idle loop that can slightly
910 improve the performance of waking up a idle CPU, but
911 will use a lot of power and make the system run hot.
913 idle=mwait: On systems which support MONITOR/MWAIT but
914 the kernel chose to not use it because it doesn't save
915 as much power as a normal idle loop, use the
916 MONITOR/MWAIT idle loop anyways. Performance should be
917 the same as idle=poll.
918 idle=halt: Halt is forced to be used for CPU idle.
919 In such case C2/C3 won't be used again.
920 idle=nomwait: Disable mwait for CPU C-states
922 ignore_loglevel [KNL]
923 Ignore loglevel setting - this will print /all/
924 kernel messages to the console. Useful for debugging.
927 Set number of hash buckets for inode cache.
930 Format: { "0" | "1" }
931 0 -- integrity auditing messages. (Default)
932 1 -- enable informational integrity auditing messages.
935 Format: { "sha1" | "md5" }
939 Load a policy which meets the needs of the Trusted
940 Computing Base. This means IMA will measure all
941 programs exec'd, files mmap'd for exec, and all files
942 opened for read by uid=0.
945 See header of drivers/scsi/in2000.c.
949 Run specified binary instead of /sbin/init as init
952 initcall_debug [KNL] Trace initcalls as they are executed. Useful
953 for working out where the kernel is dying during
956 initrd= [BOOT] Specify the location of the initial ramdisk
958 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
961 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
963 Enable intel iommu driver.
965 Disable intel iommu driver.
966 igfx_off [Default Off]
967 By default, gfx is mapped as normal device. If a gfx
968 device has a dedicated DMAR unit, the DMAR unit is
969 bypassed by not enabling DMAR with this option. In
970 this case, gfx device will use physical address for
973 With this option iommu will not optimize to look
974 for io virtual address below 32 bit forcing dual
975 address cycle on pci bus for cards supporting greater
976 than 32 bit addressing. The default is to look
977 for translation below 32 bit and if not available
978 then look in the higher range.
980 With this option on every unmap_single operation will
981 result in a hardware IOTLB flush operation as opposed
982 to batching them for performance.
986 iomem= Disable strict checking of access to MMIO memory
987 strict regions from userspace.
1003 io7= [HW] IO7 for Marvel based alpha systems
1004 See comment before marvel_specify_io7 in
1005 arch/alpha/kernel/core_marvel.c.
1007 io_delay= [X86] I/O delay method
1009 Standard port 0x80 based delay
1011 Alternate port 0xed based delay (needed on some systems)
1013 Simple two microseconds delay
1018 See Documentation/filesystems/nfsroot.txt.
1020 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1021 See comment before ip2_setup() in
1022 drivers/char/ip2/ip2base.c.
1024 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1025 See header of drivers/scsi/ips.c.
1028 When an interrupt is not handled search all handlers
1029 for it. Intended to get systems with badly broken
1033 When an interrupt is not handled search all handlers
1034 for it. Also check all handlers each timer
1035 interrupt. Intended to get systems with badly broken
1039 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1041 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1043 <cpu number>,...,<cpu number>
1045 <cpu number>-<cpu number>
1046 (must be a positive range in ascending order)
1048 <cpu number>,...,<cpu number>-<cpu number>
1050 This option can be used to specify one or more CPUs
1051 to isolate from the general SMP balancing and scheduling
1052 algorithms. You can move a process onto or off an
1053 "isolated" CPU via the CPU affinity syscalls or cpuset.
1054 <cpu number> begins at 0 and the maximum value is
1055 "number of CPUs in system - 1".
1057 This option is the preferred way to isolate CPUs. The
1058 alternative -- manually setting the CPU mask of all
1059 tasks in the system -- can cause problems and
1060 suboptimal load balancer performance.
1064 js= [HW,JOY] Analog joystick
1065 See Documentation/input/joystick.txt.
1069 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1070 specifies the amount of memory usable by the kernel
1071 for non-movable allocations. The requested amount is
1072 spread evenly throughout all nodes in the system. The
1073 remaining memory in each node is used for Movable
1074 pages. In the event, a node is too small to have both
1075 kernelcore and Movable pages, kernelcore pages will
1076 take priority and other nodes will have a larger number
1077 of kernelcore pages. The Movable zone is used for the
1078 allocation of pages that may be reclaimed or moved
1079 by the page migration subsystem. This means that
1080 HugeTLB pages may not be allocated from this zone.
1081 Note that allocations like PTEs-from-HighMem still
1082 use the HighMem zone if it exists, and the Normal
1083 zone if it does not.
1085 kgdboc= [HW] kgdb over consoles.
1086 Requires a tty driver that supports console polling.
1087 (only serial supported for now)
1088 Format: <serial_device>[,baud]
1090 kmac= [MIPS] korina ethernet MAC address.
1091 Configure the RouterBoard 532 series on-chip
1092 Ethernet adapter MAC address.
1094 kmemleak= [KNL] Boot-time kmemleak enable/disable
1095 Valid arguments: on, off
1098 kstack=N [X86] Print N words from the kernel stack
1101 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1102 Default is 0 (don't ignore, but inject #GP)
1104 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1105 Default is 1 (enabled)
1107 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1110 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1112 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1114 kvm-intel.bypass_guest_pf=
1115 [KVM,Intel] Disables bypassing of guest page faults
1116 on Intel chips. Default is 1 (enabled)
1118 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1119 (virtualized MMU) support on capable Intel chips.
1120 Default is 1 (enabled)
1122 kvm-intel.emulate_invalid_guest_state=
1123 [KVM,Intel] Enable emulation of invalid guest states
1124 Default is 0 (disabled)
1126 kvm-intel.flexpriority=
1127 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1128 Default is 1 (enabled)
1130 kvm-intel.unrestricted_guest=
1131 [KVM,Intel] Disable unrestricted guest feature
1132 (virtualized real and unpaged mode) on capable
1133 Intel chips. Default is 1 (enabled)
1135 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1136 feature (tagged TLBs) on capable Intel chips.
1137 Default is 1 (enabled)
1143 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1146 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1149 libata.dma= [LIBATA] DMA control
1150 libata.dma=0 Disable all PATA and SATA DMA
1151 libata.dma=1 PATA and SATA Disk DMA only
1152 libata.dma=2 ATAPI (CDROM) DMA only
1153 libata.dma=4 Compact Flash DMA only
1154 Combinations also work, so libata.dma=3 enables DMA
1155 for disks and CDROMs, but not CFs.
1157 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1158 libata.ignore_hpa=0 keep BIOS limits (default)
1159 libata.ignore_hpa=1 ignore limits, using full disk
1161 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1165 libata.force= [LIBATA] Force configurations. The format is comma
1166 separated list of "[ID:]VAL" where ID is
1167 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1168 matching port, link or device. Basically, it matches
1169 the ATA ID string printed on console by libata. If
1170 the whole ID part is omitted, the last PORT and DEVICE
1171 values are used. If ID hasn't been specified yet, the
1172 configuration applies to all ports, links and devices.
1174 If only DEVICE is omitted, the parameter applies to
1175 the port and all links and devices behind it. DEVICE
1176 number of 0 either selects the first device or the
1177 first fan-out link behind PMP device. It does not
1178 select the host link. DEVICE number of 15 selects the
1179 host link and device attached to it.
1181 The VAL specifies the configuration to force. As long
1182 as there's no ambiguity shortcut notation is allowed.
1183 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1184 The following configurations can be forced.
1186 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1187 Any ID with matching PORT is used.
1189 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1191 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1192 udma[/][16,25,33,44,66,100,133] notation is also
1195 * [no]ncq: Turn on or off NCQ.
1197 * nohrst, nosrst, norst: suppress hard, soft
1200 If there are multiple matching configurations changing
1201 the same attribute, the last one is used.
1203 lmb=debug [KNL] Enable lmb debug messages.
1205 load_ramdisk= [RAM] List of ramdisks to load from floppy
1206 See Documentation/blockdev/ramdisk.txt.
1208 lockd.nlm_grace_period=P [NFS] Assign grace period.
1211 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1214 lockd.nlm_timeout=T [NFS] Assign timeout value.
1217 lockd.nlm_udpport=M [NFS] Assign UDP port.
1220 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1223 loglevel= All Kernel Messages with a loglevel smaller than the
1224 console loglevel will be printed to the console. It can
1225 also be changed with klogd or other programs. The
1226 loglevels are defined as follows:
1228 0 (KERN_EMERG) system is unusable
1229 1 (KERN_ALERT) action must be taken immediately
1230 2 (KERN_CRIT) critical conditions
1231 3 (KERN_ERR) error conditions
1232 4 (KERN_WARNING) warning conditions
1233 5 (KERN_NOTICE) normal but significant condition
1234 6 (KERN_INFO) informational
1235 7 (KERN_DEBUG) debug-level messages
1237 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1238 Format: { n | nk | nM }
1239 n must be a power of two. The default size
1240 is set in the kernel config file.
1242 logo.nologo [FB] Disables display of the built-in Linux logo.
1243 This may be used to provide more screen space for
1244 kernel log messages and is useful when debugging
1245 kernel boot problems.
1247 lp=0 [LP] Specify parallel ports to use, e.g,
1248 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1249 lp=reset first parallel port). 'lp=0' disables the
1250 lp=auto printer driver. 'lp=reset' (which can be
1251 specified in addition to the ports) causes
1252 attached printers to be reset. Using
1253 lp=port1,port2,... specifies the parallel ports
1254 to associate lp devices with, starting with
1255 lp0. A port specification may be 'none' to skip
1256 that lp device, or a parport name such as
1257 'parport0'. Specifying 'lp=auto' instead of a
1258 port specification list means that device IDs
1259 from each port should be examined, to see if
1260 an IEEE 1284-compliant printer is attached; if
1261 so, the driver will manage that printer.
1262 See also header of drivers/char/lp.c.
1265 Sets loops_per_jiffy to given constant, thus avoiding
1266 time-consuming boot-time autodetection (up to 250 ms per
1267 CPU). 0 enables autodetection (default). To determine
1268 the correct value for your kernel, boot with normal
1269 autodetection and see what value is printed. Note that
1270 on SMP systems the preset will be applied to all CPUs,
1271 which is likely to cause problems if your CPUs need
1272 significantly divergent settings. An incorrect value
1273 will cause delays in the kernel to be wrong, leading to
1274 unpredictable I/O errors and other breakage. Although
1275 unlikely, in the extreme case this might damage your
1279 Format: <io>,<irq>,<dma>
1281 mac5380= [HW,SCSI] Format:
1282 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1284 machvec= [IA64] Force the use of a particular machine-vector
1285 (machvec) in a generic kernel.
1286 Example: machvec=hpzx1_swiotlb
1288 machtype= [Loongson] Share the same kernel image file between different
1290 Example: machtype=lemote-yeeloong-2f-7inch
1292 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1293 than or equal to this physical address is ignored.
1295 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1296 should make use of. maxcpus=n : n >= 0 limits the
1297 kernel to using 'n' processors. n=0 is a special case,
1298 it is equivalent to "nosmp", which also disables
1301 max_loop= [LOOP] Maximum number of loopback devices that can
1305 max_luns= [SCSI] Maximum number of LUNs to probe.
1306 Should be between 1 and 2^32-1.
1309 [SCSI] Maximum number of LUNs received.
1310 Should be between 1 and 16384.
1314 mce [X86-32] Machine Check Exception
1316 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1318 md= [HW] RAID subsystems devices and level
1319 See Documentation/md.txt.
1322 Format: <first>,<last>
1323 Specifies range of consoles to be captured by the MDA.
1325 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1326 Amount of memory to be used when the kernel is not able
1327 to see the whole system memory or for test.
1328 [X86-32] Use together with memmap= to avoid physical
1329 address space collisions. Without memmap= PCI devices
1330 could be placed at addresses belonging to unused RAM.
1332 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1336 [KNL,SH] Allow user to override the default size for
1337 per-device physically contiguous DMA buffers.
1339 memmap=exactmap [KNL,X86] Enable setting of an exact
1340 E820 memory map, as specified by the user.
1341 Such memmap=exactmap lines can be constructed based on
1342 BIOS output or other requirements. See the memmap=nn@ss
1345 memmap=nn[KMG]@ss[KMG]
1346 [KNL] Force usage of a specific region of memory
1347 Region of memory to be used, from ss to ss+nn.
1349 memmap=nn[KMG]#ss[KMG]
1350 [KNL,ACPI] Mark specific memory as ACPI data.
1351 Region of memory to be used, from ss to ss+nn.
1353 memmap=nn[KMG]$ss[KMG]
1354 [KNL,ACPI] Mark specific memory as reserved.
1355 Region of memory to be used, from ss to ss+nn.
1356 Example: Exclude memory from 0x18690000-0x1869ffff
1357 memmap=64K$0x18690000
1359 memmap=0x10000$0x18690000
1361 memory_corruption_check=0/1 [X86]
1362 Some BIOSes seem to corrupt the first 64k of
1363 memory when doing things like suspend/resume.
1364 Setting this option will scan the memory
1365 looking for corruption. Enabling this will
1366 both detect corruption and prevent the kernel
1367 from using the memory being corrupted.
1368 However, its intended as a diagnostic tool; if
1369 repeatable BIOS-originated corruption always
1370 affects the same memory, you can use memmap=
1371 to prevent the kernel from using that memory.
1373 memory_corruption_check_size=size [X86]
1374 By default it checks for corruption in the low
1375 64k, making this memory unavailable for normal
1376 use. Use this parameter to scan for
1377 corruption in more or less memory.
1379 memory_corruption_check_period=seconds [X86]
1380 By default it checks for corruption every 60
1381 seconds. Use this parameter to check at some
1382 other rate. 0 disables periodic checking.
1384 memtest= [KNL,X86] Enable memtest
1386 default : 0 <disable>
1387 Specifies the number of memtest passes to be
1388 performed. Each pass selects another test
1389 pattern from a given set of patterns. Memtest
1390 fills the memory with this pattern, validates
1391 memory contents and reserves bad memory
1392 regions that are detected.
1394 meye.*= [HW] Set MotionEye Camera parameters
1395 See Documentation/video4linux/meye.txt.
1397 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1398 Multi-Function General Purpose Timers on AMD Geode
1401 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1402 the BIOS has incorrectly applied a workaround. TinyBIOS
1403 version 0.98 is known to be affected, 0.99 fixes the
1404 problem by letting the user disable the workaround.
1408 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1409 physical address is ignored.
1411 mini2440= [ARM,HW,KNL]
1412 Format:[0..2][b][c][t]
1414 MINI2440 configuration specification:
1415 0 - The attached screen is the 3.5" TFT
1416 1 - The attached screen is the 7" TFT
1417 2 - The VGA Shield is attached (1024x768)
1418 Leaving out the screen size parameter will not load
1419 the TFT driver, and the framebuffer will be left
1421 b - Enable backlight. The TFT backlight pin will be
1422 linked to the kernel VESA blanking code and a GPIO
1423 LED. This parameter is not necessary when using the
1425 c - Enable the s3c camera interface.
1426 t - Reserved for enabling touchscreen support. The
1427 touchscreen support is not enabled in the mainstream
1428 kernel as of 2.6.30, a preliminary port can be found
1429 in the "bleeding edge" mini2440 support kernel at
1430 http://repo.or.cz/w/linux-2.6/mini2440.git
1433 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1434 parameter allows control of the logging verbosity for
1435 the additional memory initialisation checks. A value
1436 of 0 disables mminit logging and a level of 4 will
1437 log everything. Information is printed at KERN_DEBUG
1438 so loglevel=8 may also need to be specified.
1441 [MOUSE] Maximum time between finger touching and
1442 leaving touchpad surface for touch to be considered
1443 a tap and be reported as a left button click (for
1444 touchpads working in absolute mode only).
1446 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1447 reporting absolute coordinates, such as tablets
1448 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1449 reporting absolute coordinates, such as tablets
1451 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1452 is similar to kernelcore except it specifies the
1453 amount of memory used for migratable allocations.
1454 If both kernelcore and movablecore is specified,
1455 then kernelcore will be at *least* the specified
1456 value but may be more. If movablecore on its own
1457 is specified, the administrator must be careful
1458 that the amount of memory usable for all allocations
1464 MTD_Partition= [MTD]
1465 Format: <name>,<region-number>,<size>,<offset>
1467 MTD_Region= [MTD] Format:
1468 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1471 See drivers/mtd/cmdlinepart.c.
1473 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1475 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1477 boundary - index of last SLC block on Flex-OneNAND.
1478 The remaining blocks are configured as MLC blocks.
1479 lock - Configure if Flex-OneNAND boundary should be locked.
1480 Once locked, the boundary cannot be changed.
1481 1 indicates lock status, 0 indicates unlock status.
1484 ARM/S3C2412 JIVE boot control
1486 See arch/arm/mach-s3c2412/mach-jive.c
1488 mtouchusb.raw_coordinates=
1489 [HW] Make the MicroTouch USB driver use raw coordinates
1490 ('y', default) or cooked coordinates ('n')
1492 mtrr_chunk_size=nn[KMG] [X86]
1493 used for mtrr cleanup. It is largest continuous chunk
1494 that could hold holes aka. UC entries.
1496 mtrr_gran_size=nn[KMG] [X86]
1497 Used for mtrr cleanup. It is granularity of mtrr block.
1499 Large value could prevent small alignment from
1502 mtrr_spare_reg_nr=n [X86]
1504 Range: 0,7 : spare reg number
1506 Used for mtrr cleanup. It is spare mtrr entries number.
1507 Set to 2 or more if your graphical card needs more.
1509 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1512 See header of drivers/scsi/NCR_D700.c.
1516 ncr53c400= [HW,SCSI]
1518 ncr53c400a= [HW,SCSI]
1520 ncr53c406a= [HW,SCSI]
1522 ncr53c8xx= [HW,SCSI]
1524 netdev= [NET] Network devices parameters
1525 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1526 Note that mem_start is often overloaded to mean
1527 something different and driver-specific.
1528 This usage is only documented in each driver source
1532 [NETFILTER] Enable connection tracking flow accounting
1533 0 to disable accounting
1534 1 to enable accounting
1535 Default value depends on CONFIG_NF_CT_ACCT that is
1536 going to be removed in 2.6.29.
1539 See Documentation/filesystems/nfsroot.txt.
1541 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1542 See Documentation/filesystems/nfsroot.txt.
1544 nfs.callback_tcpport=
1545 [NFS] set the TCP port on which the NFSv4 callback
1546 channel should listen.
1549 [NFS] sets the pathname to the program which is used
1550 to update the NFS client cache entries.
1552 nfs.cache_getent_timeout=
1553 [NFS] sets the timeout after which an attempt to
1554 update a cache entry is deemed to have failed.
1556 nfs.idmap_cache_timeout=
1557 [NFS] set the maximum lifetime for idmapper cache
1561 [NFS] enable 64-bit inode numbers.
1562 If zero, the NFS client will fake up a 32-bit inode
1563 number for the readdir() and stat() syscalls instead
1564 of returning the full 64-bit number.
1565 The default is to return 64-bit inode numbers.
1567 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1568 when a NMI is triggered.
1569 Format: [state][,regs][,debounce][,die]
1571 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1572 Format: [panic,][num]
1574 0 - turn nmi_watchdog off
1575 1 - use the IO-APIC timer for the NMI watchdog
1576 2 - use the local APIC for the NMI watchdog using
1577 a performance counter. Note: This will use one
1578 performance counter and the local APIC's performance
1580 When panic is specified, panic when an NMI watchdog
1582 This is useful when you use a panic=... timeout and
1583 need the box quickly up again.
1584 Instead of 1 and 2 it is possible to use the following
1585 symbolic names: lapic and ioapic
1586 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1588 netpoll.carrier_timeout=
1589 [NET] Specifies amount of time (in seconds) that
1590 netpoll should wait for a carrier. By default netpoll
1593 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1594 emulation library even if a 387 maths coprocessor
1598 [HW] Never suspend the console
1599 Disable suspending of consoles during suspend and
1600 hibernate operations. Once disabled, debugging
1601 messages can reach various consoles while the rest
1602 of the system is being put to sleep (ie, while
1603 debugging driver suspend/resume hooks). This may
1604 not work reliably with all consoles, but is known
1605 to work with serial and VGA consoles.
1607 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1608 caches in the slab allocator. Saves per-node memory,
1609 but will impact performance.
1613 noapic [SMP,APIC] Tells the kernel to not make use of any
1614 IOAPICs that may be present in the system.
1616 nobats [PPC] Do not use BATs for mapping kernel lowmem
1617 on "Classic" PPC cores.
1621 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1623 nodelayacct [KNL] Disable per-task delay accounting
1625 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1627 nodsp [SH] Disable hardware DSP at boot time.
1629 noefi [X86] Disable EFI runtime services support.
1634 On X86-32 available only on PAE configured kernels.
1635 noexec=on: enable non-executable mappings (default)
1636 noexec=off: disable non-executable mappings
1639 This affects only 32-bit executables.
1640 noexec32=on: enable non-executable mappings (default)
1641 read doesn't imply executable mappings
1642 noexec32=off: disable non-executable mappings
1643 read implies executable mappings
1645 nofpu [SH] Disable hardware FPU at boot time.
1647 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1648 register save and restore. The kernel will only save
1649 legacy floating-point registers on task switch.
1651 noxsave [BUGS=X86] Disables x86 extended register state save
1652 and restore using xsave. The kernel will fallback to
1653 enabling legacy floating-point and sse state.
1655 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1656 wfi(ARM) instruction doesn't work correctly and not to
1657 use it. This is also useful when using JTAG debugger.
1659 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1660 instruction doesn't work correctly and not to
1663 no_file_caps Tells the kernel not to honor file capabilities. The
1664 only way then for a file to be executed with privilege
1665 is to be setuid root or executed by root.
1667 nohalt [IA-64] Tells the kernel not to use the power saving
1668 function PAL_HALT_LIGHT when idle. This increases
1669 power-consumption. On the positive side, it reduces
1670 interrupt wake-up latency, which may improve performance
1671 in certain environments such as networked servers or
1674 nohz= [KNL] Boottime enable/disable dynamic ticks
1675 Valid arguments: on, off
1678 noiotrap [SH] Disables trapped I/O port accesses.
1680 noirqdebug [X86-32] Disables the code which attempts to detect and
1681 disable unhandled interrupt sources.
1683 no_timer_check [X86,APIC] Disables the code which tests for
1684 broken timer IRQ sources.
1686 noisapnp [ISAPNP] Disables ISA PnP code.
1688 noinitrd [RAM] Tells the kernel not to load any configured
1691 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1696 nojitter [IA64] Disables jitter checking for ITC timers.
1698 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1700 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1702 noltlbs [PPC] Do not use large page/tlb entries for kernel
1703 lowmem mapping on PPC40x.
1705 nomca [IA-64] Disable machine check abort handling
1707 nomce [X86-32] Machine Check Exception
1709 nomfgpt [X86-32] Disable Multi-Function General Purpose
1710 Timer usage (for AMD Geode machines).
1712 norandmaps Don't use address space randomization. Equivalent to
1713 echo 0 > /proc/sys/kernel/randomize_va_space
1715 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1717 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1718 with UP alternatives
1720 noresidual [PPC] Don't use residual data on PReP machines.
1722 noresume [SWSUSP] Disables resume and restores original swap
1725 no-scroll [VGA] Disables scrollback.
1726 This is required for the Braillex ib80-piezo Braille
1727 reader made by F.H. Papenmeier (Germany).
1731 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1733 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1734 and disable the IO APIC. legacy for "maxcpus=0".
1736 nosoftlockup [KNL] Disable the soft-lockup detector.
1738 noswapaccount [KNL] Disable accounting of swap in memory resource
1739 controller. (See Documentation/cgroups/memory.txt)
1741 nosync [HW,M68K] Disables sync negotiation for all devices.
1743 notsc [BUGS=X86-32] Disable Time Stamp Counter
1745 nousb [USB] Disable the USB subsystem
1749 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1751 nptcg= [IA64] Override max number of concurrent global TLB
1752 purges which is reported from either PAL_VM_SUMMARY or
1755 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1757 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1758 one of ['zone', 'node', 'default'] can be specified
1759 This can be set from sysctl after boot.
1760 See Documentation/sysctl/vm.txt for details.
1762 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1763 See Documentation/debugging-via-ohci1394.txt for more
1766 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1767 Rather than timing out after 20 ms if an EC
1768 command is not properly ACKed, override the length
1769 of the timeout. We have interrupts disabled while
1770 waiting for the ACK, so if this is set too high
1771 interrupts *may* be lost!
1776 oprofile.timer= [HW]
1777 Use timer interrupt instead of performance counters
1779 oprofile.cpu_type= Force an oprofile cpu type
1780 This might be useful if you have an older oprofile
1781 userland or if you want common events.
1782 Format: { arch_perfmon }
1783 arch_perfmon: [X86] Force use of architectural
1784 perfmon on Intel CPUs instead of the
1785 CPU specific event set.
1787 osst= [HW,SCSI] SCSI Tape Driver
1788 Format: <buffer_size>,<write_threshold>
1789 See also Documentation/scsi/st.txt.
1791 panic= [KNL] Kernel behaviour on panic
1794 parkbd.port= [HW] Parallel port number the keyboard adapter is
1795 connected to, default is 0.
1797 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1798 0 for XT, 1 for AT (default is AT).
1801 parport= [HW,PPT] Specify parallel ports. 0 disables.
1802 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1803 Use 'auto' to force the driver to use any
1804 IRQ/DMA settings detected (the default is to
1805 ignore detected IRQ/DMA settings because of
1806 possible conflicts). You can specify the base
1807 address, IRQ, and DMA settings; IRQ and DMA
1808 should be numbers, or 'auto' (for using detected
1809 settings on that particular port), or 'nofifo'
1810 (to avoid using a FIFO even if it is detected).
1811 Parallel ports are assigned in the order they
1812 are specified on the command line, starting
1815 parport_init_mode= [HW,PPT]
1816 Configure VIA parallel port to operate in
1817 a specific mode. This is necessary on Pegasos
1818 computer where firmware has no options for setting
1819 up parallel port mode and sets it to spp.
1820 Currently this function knows 686a and 8231 chips.
1821 Format: [spp|ps2|epp|ecp|ecpepp]
1823 pas2= [HW,OSS] Format:
1824 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1827 See header of drivers/scsi/pas16.c.
1830 Halt all CPUs after the first oops has been printed for
1831 the specified number of seconds. This is to be used if
1832 your oopses keep scrolling off the screen.
1837 See header of drivers/block/paride/pcd.c.
1838 See also Documentation/blockdev/paride.txt.
1840 pci=option[,option...] [PCI] various PCI subsystem options:
1841 earlydump [X86] dump PCI config space before the kernel
1843 off [X86] don't probe for the PCI bus
1844 bios [X86-32] force use of PCI BIOS, don't access
1845 the hardware directly. Use this if your machine
1846 has a non-standard PCI host bridge.
1847 nobios [X86-32] disallow use of PCI BIOS, only direct
1848 hardware access methods are allowed. Use this
1849 if you experience crashes upon bootup and you
1850 suspect they are caused by the BIOS.
1851 conf1 [X86] Force use of PCI Configuration
1853 conf2 [X86] Force use of PCI Configuration
1855 noaer [PCIE] If the PCIEAER kernel config parameter is
1856 enabled, this kernel boot option can be used to
1857 disable the use of PCIE advanced error reporting.
1858 nodomains [PCI] Disable support for multiple PCI
1859 root domains (aka PCI segments, in ACPI-speak).
1860 nommconf [X86] Disable use of MMCONFIG for PCI
1862 check_enable_amd_mmconf [X86] check for and enable
1863 properly configured MMIO access to PCI
1864 config space on AMD family 10h CPU
1865 nomsi [MSI] If the PCI_MSI kernel config parameter is
1866 enabled, this kernel boot option can be used to
1867 disable the use of MSI interrupts system-wide.
1868 noioapicquirk [APIC] Disable all boot interrupt quirks.
1869 Safety option to keep boot IRQs enabled. This
1870 should never be necessary.
1871 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1872 primary IO-APIC for bridges that cannot disable
1873 boot IRQs. This fixes a source of spurious IRQs
1874 when the system masks IRQs.
1875 noioapicreroute [APIC] Disable workaround that uses the
1876 boot IRQ equivalent of an IRQ that connects to
1877 a chipset where boot IRQs cannot be disabled.
1878 The opposite of ioapicreroute.
1879 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1880 routing table. These calls are known to be buggy
1881 on several machines and they hang the machine
1882 when used, but on other computers it's the only
1883 way to get the interrupt routing table. Try
1884 this option if the kernel is unable to allocate
1885 IRQs or discover secondary PCI buses on your
1887 rom [X86] Assign address space to expansion ROMs.
1888 Use with caution as certain devices share
1889 address decoders between ROMs and other
1891 norom [X86] Do not assign address space to
1892 expansion ROMs that do not already have
1893 BIOS assigned address ranges.
1894 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1895 assigned automatically to PCI devices. You can
1896 make the kernel exclude IRQs of your ISA cards
1898 pirqaddr=0xAAAAA [X86] Specify the physical address
1899 of the PIRQ table (normally generated
1900 by the BIOS) if it is outside the
1901 F0000h-100000h range.
1902 lastbus=N [X86] Scan all buses thru bus #N. Can be
1903 useful if the kernel is unable to find your
1904 secondary buses and you want to tell it
1905 explicitly which ones they are.
1906 assign-busses [X86] Always assign all PCI bus
1907 numbers ourselves, overriding
1908 whatever the firmware may have done.
1909 usepirqmask [X86] Honor the possible IRQ mask stored
1910 in the BIOS $PIR table. This is needed on
1911 some systems with broken BIOSes, notably
1912 some HP Pavilion N5400 and Omnibook XE3
1913 notebooks. This will have no effect if ACPI
1914 IRQ routing is enabled.
1915 noacpi [X86] Do not use ACPI for IRQ routing
1916 or for PCI scanning.
1917 use_crs [X86] Use _CRS for PCI resource
1919 routeirq Do IRQ routing for all PCI devices.
1920 This is normally done in pci_enable_device(),
1921 so this option is a temporary workaround
1922 for broken drivers that don't call it.
1923 skip_isa_align [X86] do not align io start addr, so can
1924 handle more pci cards
1925 firmware [ARM] Do not re-enumerate the bus but instead
1926 just use the configuration from the
1927 bootloader. This is currently used on
1928 IXP2000 systems where the bus has to be
1929 configured a certain way for adjunct CPUs.
1930 noearly [X86] Don't do any early type 1 scanning.
1931 This might help on some broken boards which
1932 machine check when some devices' config space
1933 is read. But various workarounds are disabled
1934 and some IOMMU drivers will not work.
1935 bfsort Sort PCI devices into breadth-first order.
1936 This sorting is done to get a device
1937 order compatible with older (<= 2.4) kernels.
1938 nobfsort Don't sort PCI devices into breadth-first order.
1939 cbiosize=nn[KMG] The fixed amount of bus space which is
1940 reserved for the CardBus bridge's IO window.
1941 The default value is 256 bytes.
1942 cbmemsize=nn[KMG] The fixed amount of bus space which is
1943 reserved for the CardBus bridge's memory
1944 window. The default value is 64 megabytes.
1947 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1948 Specifies alignment and device to reassign
1949 aligned memory resources.
1950 If <order of align> is not specified,
1951 PAGE_SIZE is used as alignment.
1952 PCI-PCI bridge can be specified, if resource
1953 windows need to be expanded.
1954 ecrc= Enable/disable PCIe ECRC (transaction layer
1955 end-to-end CRC checking).
1956 bios: Use BIOS/firmware settings. This is the
1961 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1964 force Enable ASPM even on devices that claim not to support it.
1965 WARNING: Forcing ASPM on may cause system lockups.
1967 pcmv= [HW,PCMCIA] BadgePAD 4
1970 See Documentation/blockdev/paride.txt.
1972 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1975 See arch/parisc/kernel/pdc_chassis.c
1977 percpu_alloc= Select which percpu first chunk allocator to use.
1978 Currently supported values are "embed" and "page".
1979 Archs may support subset or none of the selections.
1980 See comments in mm/percpu.c for details on each
1981 allocator. This parameter is primarily for debugging
1982 and performance comparison.
1985 See Documentation/blockdev/paride.txt.
1988 See Documentation/blockdev/paride.txt.
1990 pirq= [SMP,APIC] Manual mp-table setup
1991 See Documentation/x86/i386/IO-APIC.txt.
1993 plip= [PPT,NET] Parallel port network link
1994 Format: { parport<nr> | timid | 0 }
1995 See also Documentation/parport.txt.
1997 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1998 Override pmtimer IOPort with a hex value.
2002 Enable PNP debug messages. This depends on the
2003 CONFIG_PNP_DEBUG_MESSAGES option.
2009 { on | off | curr | res | no-curr | no-res }
2012 [ISAPNP] Exclude IRQs for the autoconfiguration
2015 [ISAPNP] Exclude DMAs for the autoconfiguration
2017 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2018 Ranges are in pairs (I/O port base and size).
2021 [ISAPNP] Exclude memory regions for the
2023 Ranges are in pairs (memory base and size).
2025 ports= [IP_VS_FTP] IPVS ftp helper module
2027 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2029 Format: <port>,<port>....
2031 print-fatal-signals=
2032 [KNL] debug: print fatal signals
2033 print-fatal-signals=1: print segfault info to
2037 printk.time= Show timing data prefixed to each printk message line
2038 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2040 processor.max_cstate= [HW,ACPI]
2041 Limit processor to maximum C-state
2042 max_cstate=9 overrides any DMI blacklist limit.
2044 processor.nocst [HW,ACPI]
2045 Ignore the _CST method to determine C-states,
2046 instead using the legacy FADT method
2048 profile= [KNL] Enable kernel profiling via /proc/profile
2049 Format: [schedule,]<number>
2050 Param: "schedule" - profile schedule points.
2051 Param: <number> - step/bucket size as a power of 2 for
2052 statistical time based profiling.
2053 Param: "sleep" - profile D-state sleeping (millisecs).
2054 Requires CONFIG_SCHEDSTATS
2055 Param: "kvm" - profile VM exits.
2057 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2059 See Documentation/blockdev/ramdisk.txt.
2061 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2062 probe for; one of (bare|imps|exps|lifebook|any).
2063 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2065 psmouse.resetafter= [HW,MOUSE]
2066 Try to reset the device after so many bad packets
2069 [HW,MOUSE] Set desired mouse resolution, in dpi.
2070 psmouse.smartscroll=
2071 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2072 0 = disabled, 1 = enabled (default).
2074 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2076 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2079 See Documentation/blockdev/paride.txt.
2082 [KNL] Number of legacy pty's. Overwrites compiled-in
2085 quiet [KNL] Disable most log messages
2090 See Documentation/md.txt.
2092 ramdisk_blocksize= [RAM]
2093 See Documentation/blockdev/ramdisk.txt.
2095 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2096 See Documentation/blockdev/ramdisk.txt.
2098 rcupdate.blimit= [KNL,BOOT]
2099 Set maximum number of finished RCU callbacks to process
2102 rcupdate.qhimark= [KNL,BOOT]
2103 Set threshold of queued
2104 RCU callbacks over which batch limiting is disabled.
2106 rcupdate.qlowmark= [KNL,BOOT]
2107 Set threshold of queued RCU callbacks below which
2108 batch limiting is re-enabled.
2112 Run specified binary instead of /init from the ramdisk,
2113 used for early userspace startup. See initrd.
2115 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2116 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2117 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2120 [KNL, SMP] Set scheduler's default relax_domain_level.
2121 See Documentation/cgroups/cpusets.txt.
2123 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2125 reservetop= [X86-32]
2127 Reserves a hole at the top of the kernel virtual
2130 reset_devices [KNL] Force drivers to reset the underlying device
2131 during initialization.
2134 Specify the partition device for software suspend
2136 resume_offset= [SWSUSP]
2137 Specify the offset from the beginning of the partition
2138 given by "resume=" at which the swap header is located,
2139 in <PAGE_SIZE> units (needed only for swap files).
2140 See Documentation/power/swsusp-and-swap-files.txt
2142 retain_initrd [RAM] Keep initrd memory after extraction
2144 rhash_entries= [KNL,NET]
2145 Set number of hash buckets for route cache
2147 riscom8= [HW,SERIAL]
2148 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2150 ro [KNL] Mount root device read-only on boot
2152 root= [KNL] Root filesystem
2154 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2155 mount the root filesystem
2157 rootflags= [KNL] Set root filesystem mount option string
2159 rootfstype= [KNL] Set root filesystem type
2161 rootwait [KNL] Wait (indefinitely) for root device to show up.
2162 Useful for devices that are detected asynchronously
2163 (e.g. USB and MMC devices).
2165 rw [KNL] Mount root device read-write on boot
2167 S [KNL] Run init in single mode
2170 See drivers/net/irda/sa1100_ir.c.
2172 sbni= [NET] Granch SBNI12 leased line adapter
2174 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2175 Format: <io>[,<timeout>[,<isapnp>]]
2177 scsi_debug_*= [SCSI]
2178 See drivers/scsi/scsi_debug.c.
2180 scsi_default_dev_flags=
2181 [SCSI] SCSI default device flags
2184 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2185 Format: <vendor>:<model>:<flags>
2186 (flags are integer value)
2188 scsi_logging_level= [SCSI] a bit mask of logging levels
2189 See drivers/scsi/scsi_logging.h for bits. Also
2190 settable via sysctl at dev.scsi.logging_level
2191 (/proc/sys/dev/scsi/logging_level).
2192 There is also a nice 'scsi_logging_level' script in the
2193 S390-tools package, available for download at
2194 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2196 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2197 discovered. async scans them in kernel threads,
2198 allowing boot to proceed. none ignores them, expecting
2199 user space to do the scan.
2201 security= [SECURITY] Choose a security module to enable at boot.
2202 If this boot parameter is not specified, only the first
2203 security module asking for security registration will be
2204 loaded. An invalid security module name will be treated
2205 as if no module has been chosen.
2207 selinux= [SELINUX] Disable or enable SELinux at boot time.
2208 Format: { "0" | "1" }
2209 See security/selinux/Kconfig help text.
2212 Default value is set via kernel config option.
2213 If enabled at boot time, /selinux/disable can be used
2214 later to disable prior to initial policy load.
2216 serialnumber [BUGS=X86-32]
2219 Maximal number of shapers.
2221 show_msr= [x86] show boot-time MSR settings
2222 Format: { <integer> }
2223 Show boot-time (BIOS-initialized) MSR settings.
2224 The parameter means the number of CPUs to show,
2225 for example 1 means boot CPU only.
2228 See header of drivers/scsi/sim710.c.
2235 slub_debug[=options[,slabs]] [MM, SLUB]
2236 Enabling slub_debug allows one to determine the
2237 culprit if slab objects become corrupted. Enabling
2238 slub_debug can create guard zones around objects and
2239 may poison objects when not in use. Also tracks the
2240 last alloc / free. For more information see
2241 Documentation/vm/slub.txt.
2243 slub_max_order= [MM, SLUB]
2244 Determines the maximum allowed order for slabs.
2245 A high setting may cause OOMs due to memory
2246 fragmentation. For more information see
2247 Documentation/vm/slub.txt.
2249 slub_min_objects= [MM, SLUB]
2250 The minimum number of objects per slab. SLUB will
2251 increase the slab order up to slub_max_order to
2252 generate a sufficiently large slab able to contain
2253 the number of objects indicated. The higher the number
2254 of objects the smaller the overhead of tracking slabs
2255 and the less frequently locks need to be acquired.
2256 For more information see Documentation/vm/slub.txt.
2258 slub_min_order= [MM, SLUB]
2259 Determines the mininum page order for slabs. Must be
2260 lower than slub_max_order.
2261 For more information see Documentation/vm/slub.txt.
2263 slub_nomerge [MM, SLUB]
2264 Disable merging of slabs with similar size. May be
2265 necessary if there is some reason to distinguish
2266 allocs to different slabs. Debug options disable
2267 merging on their own.
2268 For more information see Documentation/vm/slub.txt.
2271 Format: <io1>[,<io2>[,...,<io8>]]
2273 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2274 attempt to substitute SMP alternatives once at boot.
2276 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2277 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2278 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2279 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2280 smsc-ircc2.ircc_irq= [HW] IRQ line
2281 smsc-ircc2.ircc_dma= [HW] DMA channel
2282 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2283 0: Toshiba Satellite 1800 (GP data pin select)
2284 1: Fast pin select (default)
2287 snd-ad1816a= [HW,ALSA]
2289 snd-ad1848= [HW,ALSA]
2291 snd-ali5451= [HW,ALSA]
2293 snd-als100= [HW,ALSA]
2295 snd-als4000= [HW,ALSA]
2297 snd-azt2320= [HW,ALSA]
2299 snd-cmi8330= [HW,ALSA]
2301 snd-cmipci= [HW,ALSA]
2303 snd-cs4231= [HW,ALSA]
2305 snd-cs4232= [HW,ALSA]
2307 snd-cs4236= [HW,ALSA]
2309 snd-cs4281= [HW,ALSA]
2311 snd-cs46xx= [HW,ALSA]
2313 snd-dt019x= [HW,ALSA]
2315 snd-dummy= [HW,ALSA]
2317 snd-emu10k1= [HW,ALSA]
2319 snd-ens1370= [HW,ALSA]
2321 snd-ens1371= [HW,ALSA]
2323 snd-es968= [HW,ALSA]
2325 snd-es1688= [HW,ALSA]
2327 snd-es18xx= [HW,ALSA]
2329 snd-es1938= [HW,ALSA]
2331 snd-es1968= [HW,ALSA]
2333 snd-fm801= [HW,ALSA]
2335 snd-gusclassic= [HW,ALSA]
2337 snd-gusextreme= [HW,ALSA]
2339 snd-gusmax= [HW,ALSA]
2343 snd-ice1712= [HW,ALSA]
2345 snd-intel8x0= [HW,ALSA]
2347 snd-interwave= [HW,ALSA]
2352 snd-korg1212= [HW,ALSA]
2354 snd-maestro3= [HW,ALSA]
2356 snd-mpu401= [HW,ALSA]
2358 snd-mtpav= [HW,ALSA]
2360 snd-nm256= [HW,ALSA]
2362 snd-opl3sa2= [HW,ALSA]
2370 snd-opti93x= [HW,ALSA]
2374 snd-rme32= [HW,ALSA]
2376 snd-rme96= [HW,ALSA]
2378 snd-rme9652= [HW,ALSA]
2384 snd-sbawe= [HW,ALSA]
2386 snd-serial= [HW,ALSA]
2388 snd-sgalaxy= [HW,ALSA]
2390 snd-sonicvibes= [HW,ALSA]
2395 snd-sun-cs4231= [HW,ALSA]
2397 snd-trident= [HW,ALSA]
2399 snd-usb-audio= [HW,ALSA,USB]
2401 snd-via82xx= [HW,ALSA]
2403 snd-virmidi= [HW,ALSA]
2405 snd-wavefront= [HW,ALSA]
2407 snd-ymfpci= [HW,ALSA]
2410 [KNL] Should the soft-lockup detector generate panics.
2412 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2413 See Documentation/sonypi.txt
2415 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2416 See Documentation/serial/specialix.txt.
2418 spia_io_base= [HW,MTD]
2424 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2426 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2427 See Documentation/scsi/st.txt.
2430 Enabled the stack tracer on boot up.
2434 Set the STI (builtin display/keyboard on the HP-PARISC
2435 machines) console (graphic card) which should be used
2436 as the initial boot-console.
2437 See also comment in drivers/video/console/sticore.c.
2440 See comment in drivers/video/console/sticore.c.
2443 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2445 sunrpc.min_resvport=
2446 sunrpc.max_resvport=
2448 SunRPC servers often require that client requests
2449 originate from a privileged port (i.e. a port in the
2450 range 0 < portnr < 1024).
2451 An administrator who wishes to reserve some of these
2452 ports for other uses may adjust the range that the
2453 kernel's sunrpc client considers to be privileged
2454 using these two parameters to set the minimum and
2455 maximum port values.
2459 Control how the NFS server code allocates CPUs to
2460 service thread pools. Depending on how many NICs
2461 you have and where their interrupts are bound, this
2462 option will affect which CPUs will do NFS serving.
2463 Note: this parameter cannot be changed while the
2464 NFS server is running.
2466 auto the server chooses an appropriate mode
2467 automatically using heuristics
2468 global a single global pool contains all CPUs
2469 percpu one pool for each CPU
2470 pernode one pool for each NUMA node (equivalent
2471 to global on non-NUMA machines)
2473 sunrpc.tcp_slot_table_entries=
2474 sunrpc.udp_slot_table_entries=
2476 Sets the upper limit on the number of simultaneous
2477 RPC calls that can be sent from the client to a
2478 server. Increasing these values may allow you to
2479 improve throughput, but will also increase the
2480 amount of memory reserved for use by the client.
2482 swiotlb= [IA-64] Number of I/O TLB slabs
2486 sym53c416= [HW,SCSI]
2487 See header of drivers/scsi/sym53c416.c.
2489 sysrq_always_enabled
2491 Ignore sysrq setting - this boot parameter will
2492 neutralize any effect of /proc/sys/kernel/sysrq.
2493 Useful for debugging.
2496 See header of drivers/scsi/t128.c.
2500 test_suspend= [SUSPEND]
2501 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2502 standby suspend) as the system sleep state to briefly
2503 enter during system startup. The system is woken from
2504 this state using a wakeup-capable RTC alarm.
2506 thash_entries= [KNL,NET]
2507 Set number of hash buckets for TCP connection
2509 thermal.act= [HW,ACPI]
2510 -1: disable all active trip points in all thermal zones
2511 <degrees C>: override all lowest active trip points
2513 thermal.crt= [HW,ACPI]
2514 -1: disable all critical trip points in all thermal zones
2515 <degrees C>: override all critical trip points
2517 thermal.nocrt= [HW,ACPI]
2518 Set to disable actions on ACPI thermal zone
2519 critical and hot trip points.
2521 thermal.off= [HW,ACPI]
2522 1: disable ACPI thermal control
2524 thermal.psv= [HW,ACPI]
2525 -1: disable all passive trip points
2526 <degrees C>: override all passive trip points to this
2529 thermal.tzp= [HW,ACPI]
2530 Specify global default ACPI thermal zone polling rate
2531 <deci-seconds>: poll all this frequency
2532 0: no polling (default)
2535 See comment before function dc390_setup() in
2536 drivers/scsi/tmscsim.c.
2540 Specify if the kernel should make use of the cpu
2541 topology informations if the hardware supports these.
2542 The scheduler will make use of these informations and
2543 e.g. base its process migration decisions on it.
2548 trace_buf_size=nn[KMG]
2549 [FTRACE] will set tracing buffer size.
2551 trace_event=[event-list]
2552 [FTRACE] Set and start specified trace events in order
2553 to facilitate early boot debugging.
2554 See also Documentation/trace/events.txt
2556 trix= [HW,OSS] MediaTrix AudioTrix Pro
2558 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2560 tsc= Disable clocksource-must-verify flag for TSC.
2562 [x86] reliable: mark tsc clocksource as reliable, this
2563 disables clocksource verification at runtime.
2564 Used to enable high-resolution timer mode on older
2565 hardware, and in virtualized environment.
2567 turbografx.map[2|3]= [HW,JOY]
2568 TurboGraFX parallel port interface
2570 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2571 See also Documentation/input/joystick-parport.txt
2573 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2574 See header of drivers/scsi/u14-34f.c.
2583 [USB] Ignore overcurrent events (default N).
2584 Some badly-designed motherboards generate lots of
2585 bogus events, for ports that aren't wired to
2586 anything. Set this parameter to avoid log spamming.
2587 Note that genuine overcurrent events won't be
2592 Set unknown_nmi_panic=1 early on boot.
2594 usbcore.autosuspend=
2595 [USB] The autosuspend time delay (in seconds) used
2596 for newly-detected USB devices (default 2). This
2597 is the time required before an idle device will be
2598 autosuspended. Devices for which the delay is set
2599 to a negative value won't be autosuspended at all.
2601 usbcore.usbfs_snoop=
2602 [USB] Set to log all usbfs traffic (default 0 = off).
2604 usbcore.blinkenlights=
2605 [USB] Set to cycle leds on hubs (default 0 = off).
2607 usbcore.old_scheme_first=
2608 [USB] Start with the old device initialization
2609 scheme (default 0 = off).
2611 usbcore.use_both_schemes=
2612 [USB] Try the other device initialization scheme
2613 if the first one fails (default 1 = enabled).
2615 usbcore.initial_descriptor_timeout=
2616 [USB] Specifies timeout for the initial 64-byte
2617 USB_REQ_GET_DESCRIPTOR request in milliseconds
2618 (default 5000 = 5.0 seconds).
2621 [USBHID] The interval which mice are to be polled at.
2623 usb-storage.delay_use=
2624 [UMS] The delay in seconds before a new device is
2625 scanned for Logical Units (default 5).
2628 [UMS] A list of quirks entries to supplement or
2629 override the built-in unusual_devs list. List
2630 entries are separated by commas. Each entry has
2631 the form VID:PID:Flags where VID and PID are Vendor
2632 and Product ID values (4-digit hex numbers) and
2633 Flags is a set of characters, each corresponding
2634 to a common usb-storage quirk flag as follows:
2635 a = SANE_SENSE (collect more than 18 bytes
2637 c = FIX_CAPACITY (decrease the reported
2638 device capacity by one sector);
2639 h = CAPACITY_HEURISTICS (decrease the
2640 reported device capacity by one
2641 sector if the number is odd);
2642 i = IGNORE_DEVICE (don't bind to this
2644 l = NOT_LOCKABLE (don't try to lock and
2645 unlock ejectable media);
2646 m = MAX_SECTORS_64 (don't transfer more
2647 than 64 sectors = 32 KB at a time);
2648 o = CAPACITY_OK (accept the capacity
2649 reported by the device);
2650 r = IGNORE_RESIDUE (the device reports
2651 bogus residue values);
2652 s = SINGLE_LUN (the device has only one
2654 w = NO_WP_DETECT (don't test whether the
2655 medium is write-protected).
2656 Example: quirks=0419:aaf5:rl,0421:0433:rc
2659 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2660 vdso=1: enable VDSO (default)
2661 vdso=0: disable VDSO mapping
2664 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2665 vdso32=1: enable 32-bit VDSO (default)
2666 vdso32=0: disable 32-bit VDSO mapping
2669 vector=percpu: enable percpu vector domain
2671 video= [FB] Frame buffer configuration
2672 See Documentation/fb/modedb.txt.
2674 vga= [BOOT,X86-32] Select a particular video mode
2675 See Documentation/x86/boot.txt and
2676 Documentation/svga.txt.
2677 Use vga=ask for menu.
2678 This is actually a boot loader parameter; the value is
2679 passed to the kernel using a special protocol.
2681 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2682 size of <nn>. This can be used to increase the
2683 minimum size (128MB on x86). It can also be used to
2684 decrease the size and leave more room for directly
2687 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2690 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2693 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2696 vt.default_blu= [VT]
2697 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2698 Change the default blue palette of the console.
2699 This is a 16-member array composed of values
2702 vt.default_grn= [VT]
2703 Format: <green0>,<green1>,<green2>,...,<green15>
2704 Change the default green palette of the console.
2705 This is a 16-member array composed of values
2708 vt.default_red= [VT]
2709 Format: <red0>,<red1>,<red2>,...,<red15>
2710 Change the default red palette of the console.
2711 This is a 16-member array composed of values
2717 Set system-wide default UTF-8 mode for all tty's.
2718 Default is 1, i.e. UTF-8 mode is enabled for all
2719 newly opened terminals.
2721 waveartist= [HW,OSS]
2722 Format: <io>,<irq>,<dma>,<dma2>
2725 See header of drivers/scsi/wd33c93.c.
2728 See header of drivers/scsi/wd7000.c.
2731 See Documentation/watchdog/wdt.txt.
2733 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2734 default x2apic cluster mode on platforms
2737 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2738 xd_geo= See header of drivers/block/xd.c.
2740 xirc2ps_cs= [NET,PCMCIA]
2742 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2744 ______________________________________________________________________
2748 Add documentation for ALSA options.
2749 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob