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=ttySn[,baudrate]
674 earlyprintk=dbgp[debugController#]
676 Append ",keep" to not disable it when the real console
679 Only vga or serial or usb debug port at a time.
681 Currently only ttyS0 and ttyS1 are supported.
683 Interaction with the standard serial driver is not
686 The VGA output is eventually overwritten by the real
692 Format: {"off" | "on" | "skip[mbr]"}
694 eisa_irq_edge= [PARISC,HW]
695 See header of drivers/parisc/eisa.c.
698 See comment before function elanfreq_setup() in
699 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
702 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
703 See Documentation/block/as-iosched.txt and
704 Documentation/block/deadline-iosched.txt for details.
706 elfcorehdr= [IA64,PPC,SH,X86]
707 Specifies physical address of start of kernel core
708 image elf header. Generally kexec loader will
709 pass this option to capture kernel.
710 See Documentation/kdump/kdump.txt for details.
712 enable_mtrr_cleanup [X86]
713 The kernel tries to adjust MTRR layout from continuous
714 to discrete, to make X server driver able to add WB
715 entry later. This parameter enables that.
717 enable_timer_pin_1 [X86]
718 Enable PIN 1 of APIC timer
719 Can be useful to work around chipset bugs
720 (in particular on some ATI chipsets).
721 The kernel tries to set a reasonable default.
723 enforcing [SELINUX] Set initial enforcing status.
725 See security/selinux/Kconfig help text.
726 0 -- permissive (log only, no denials).
727 1 -- enforcing (deny and log).
729 Value can be changed at runtime via /selinux/enforce.
731 ether= [HW,NET] Ethernet cards parameters
732 This option is obsoleted by the "netdev=" option, which
733 has equivalent usage. See its documentation for details.
735 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
740 fail_make_request=[KNL]
741 General fault injection mechanism.
742 Format: <interval>,<probability>,<space>,<times>
743 See also /Documentation/fault-injection/.
746 See header of drivers/scsi/fd_mcs.c.
749 See header of drivers/scsi/fdomain.c.
752 See Documentation/blockdev/floppy.txt.
754 force_pal_cache_flush
755 [IA-64] Avoid check_sal_cache_flush which may hang on
756 buggy SAL_CACHE_FLUSH implementations. Using this
757 parameter will force ia64_sal_cache_flush to call
758 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
761 [FTRACE] will set and start the specified tracer
762 as early as possible in order to facilitate early
766 [FTRACE] will dump the trace buffers on oops.
768 ftrace_filter=[function-list]
769 [FTRACE] Limit the functions traced by the function
770 tracer at boot up. function-list is a comma separated
771 list of functions. This list can be changed at run
772 time by the set_ftrace_filter file in the debugfs
775 ftrace_notrace=[function-list]
776 [FTRACE] Do not trace the functions specified in
777 function-list. This list can be changed at run time
778 by the set_ftrace_notrace file in the debugfs
781 ftrace_graph_filter=[function-list]
782 [FTRACE] Limit the top level callers functions traced
783 by the function graph tracer at boot up.
784 function-list is a comma separated list of functions
785 that can be changed at run time by the
786 set_graph_function file in the debugfs tracing directory.
789 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
790 support via parallel port (up to 5 devices per port)
791 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
792 See also Documentation/input/joystick-parport.txt
796 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
800 gcov_persist= [GCOV] When non-zero (default), profiling data for
801 kernel modules is saved and remains accessible via
802 debugfs, even when the module is unloaded/reloaded.
803 When zero, profiling data is discarded and associated
804 debugfs files are removed at module unload time.
807 See header of drivers/scsi/gdth.c.
809 gpt [EFI] Forces disk with valid GPT signature but
810 invalid Protective MBR to be treated as GPT.
814 hashdist= [KNL,NUMA] Large hashes allocated during boot
815 are distributed across NUMA nodes. Defaults on
816 for 64bit NUMA, off otherwise.
817 Format: 0 | 1 (for off | on)
819 hcl= [IA-64] SGI's Hardware Graph compatibility layer
821 hd= [EIDE] (E)IDE hard drive subsystem geometry
822 Format: <cyl>,<head>,<sect>
824 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
825 size of <nn>. This works even on boxes that have no
826 highmem otherwise. This also works to reduce highmem
827 size on bigger boxes.
829 highres= [KNL] Enable/disable high resolution timer mode.
830 Valid parameters: "on", "off"
834 See Documentation/isdn/README.HiSax.
838 hpet= [X86-32,HPET] option to control HPET usage
839 Format: { enable (default) | disable | force |
841 disable: disable HPET and use PIT instead
842 force: allow force enabled of undocumented chips (ICH4,
844 verbose: show contents of HPET registers during setup
846 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
847 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
848 On x86-64 and powerpc, this option can be specified
849 multiple times interleaved with hugepages= to reserve
850 huge pages of different sizes. Valid pages sizes on
851 x86-64 are 2M (when the CPU supports "pse") and 1G
852 (when the CPU supports the "pdpe1gb" cpuinfo flag)
853 Note that 1GB pages can only be allocated at boot time
854 using hugepages= and not freed afterwards.
856 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
857 terminal devices. Valid values: 0..8
858 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
859 If specified, z/VM IUCV HVC accepts connections
860 from listed z/VM user IDs only.
862 i2c_bus= [HW] Override the default board specific I2C bus speed
863 or register an additional I2C bus that is not
864 registered from board initialization code.
868 i8042.debug [HW] Toggle i8042 debug mode
869 i8042.direct [HW] Put keyboard port into non-translated mode
870 i8042.dumbkbd [HW] Pretend that controller can only read data from
871 keyboard and cannot control its state
872 (Don't attempt to blink the leds)
873 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
874 i8042.nokbd [HW] Don't check/create keyboard port
875 i8042.noloop [HW] Disable the AUX Loopback command while probing
877 i8042.nomux [HW] Don't check presence of an active multiplexing
879 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
882 [HW] Frequency with which keyboard LEDs should blink
883 when kernel panics (default is 0.5 sec)
884 i8042.reset [HW] Reset the controller during init and cleanup
885 i8042.unlock [HW] Unlock (ignore) the keylock
889 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
890 indicates that the driver is running on unsupported
892 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
893 does not match list of supported models.
895 [HW] Report power status in /proc/i8k
896 (disabled by default)
897 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
900 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
901 See Documentation/mca.txt.
904 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
906 ide-core.nodma= [HW] (E)IDE subsystem
907 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
908 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
909 .cdrom .chs .ignore_cable are additional options
910 See Documentation/ide/ide.txt.
912 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
913 Claim all unknown PCI IDE storage controllers.
916 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
917 Poll forces a polling idle loop that can slightly
918 improve the performance of waking up a idle CPU, but
919 will use a lot of power and make the system run hot.
921 idle=mwait: On systems which support MONITOR/MWAIT but
922 the kernel chose to not use it because it doesn't save
923 as much power as a normal idle loop, use the
924 MONITOR/MWAIT idle loop anyways. Performance should be
925 the same as idle=poll.
926 idle=halt: Halt is forced to be used for CPU idle.
927 In such case C2/C3 won't be used again.
928 idle=nomwait: Disable mwait for CPU C-states
930 ignore_loglevel [KNL]
931 Ignore loglevel setting - this will print /all/
932 kernel messages to the console. Useful for debugging.
935 Set number of hash buckets for inode cache.
938 Format: { "0" | "1" }
939 0 -- integrity auditing messages. (Default)
940 1 -- enable informational integrity auditing messages.
943 Format: { "sha1" | "md5" }
947 Load a policy which meets the needs of the Trusted
948 Computing Base. This means IMA will measure all
949 programs exec'd, files mmap'd for exec, and all files
950 opened for read by uid=0.
953 See header of drivers/scsi/in2000.c.
957 Run specified binary instead of /sbin/init as init
960 initcall_debug [KNL] Trace initcalls as they are executed. Useful
961 for working out where the kernel is dying during
964 initrd= [BOOT] Specify the location of the initial ramdisk
966 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
969 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
971 Enable intel iommu driver.
973 Disable intel iommu driver.
974 igfx_off [Default Off]
975 By default, gfx is mapped as normal device. If a gfx
976 device has a dedicated DMAR unit, the DMAR unit is
977 bypassed by not enabling DMAR with this option. In
978 this case, gfx device will use physical address for
981 With this option iommu will not optimize to look
982 for io virtual address below 32 bit forcing dual
983 address cycle on pci bus for cards supporting greater
984 than 32 bit addressing. The default is to look
985 for translation below 32 bit and if not available
986 then look in the higher range.
988 With this option on every unmap_single operation will
989 result in a hardware IOTLB flush operation as opposed
990 to batching them for performance.
994 iomem= Disable strict checking of access to MMIO memory
995 strict regions from userspace.
1011 io7= [HW] IO7 for Marvel based alpha systems
1012 See comment before marvel_specify_io7 in
1013 arch/alpha/kernel/core_marvel.c.
1015 io_delay= [X86] I/O delay method
1017 Standard port 0x80 based delay
1019 Alternate port 0xed based delay (needed on some systems)
1021 Simple two microseconds delay
1026 See Documentation/filesystems/nfsroot.txt.
1028 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1029 See comment before ip2_setup() in
1030 drivers/char/ip2/ip2base.c.
1032 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1033 See header of drivers/scsi/ips.c.
1036 When an interrupt is not handled search all handlers
1037 for it. Intended to get systems with badly broken
1041 When an interrupt is not handled search all handlers
1042 for it. Also check all handlers each timer
1043 interrupt. Intended to get systems with badly broken
1047 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1049 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1051 <cpu number>,...,<cpu number>
1053 <cpu number>-<cpu number>
1054 (must be a positive range in ascending order)
1056 <cpu number>,...,<cpu number>-<cpu number>
1058 This option can be used to specify one or more CPUs
1059 to isolate from the general SMP balancing and scheduling
1060 algorithms. You can move a process onto or off an
1061 "isolated" CPU via the CPU affinity syscalls or cpuset.
1062 <cpu number> begins at 0 and the maximum value is
1063 "number of CPUs in system - 1".
1065 This option is the preferred way to isolate CPUs. The
1066 alternative -- manually setting the CPU mask of all
1067 tasks in the system -- can cause problems and
1068 suboptimal load balancer performance.
1072 js= [HW,JOY] Analog joystick
1073 See Documentation/input/joystick.txt.
1077 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1078 specifies the amount of memory usable by the kernel
1079 for non-movable allocations. The requested amount is
1080 spread evenly throughout all nodes in the system. The
1081 remaining memory in each node is used for Movable
1082 pages. In the event, a node is too small to have both
1083 kernelcore and Movable pages, kernelcore pages will
1084 take priority and other nodes will have a larger number
1085 of kernelcore pages. The Movable zone is used for the
1086 allocation of pages that may be reclaimed or moved
1087 by the page migration subsystem. This means that
1088 HugeTLB pages may not be allocated from this zone.
1089 Note that allocations like PTEs-from-HighMem still
1090 use the HighMem zone if it exists, and the Normal
1091 zone if it does not.
1093 kgdboc= [HW] kgdb over consoles.
1094 Requires a tty driver that supports console polling.
1095 (only serial supported for now)
1096 Format: <serial_device>[,baud]
1098 kmac= [MIPS] korina ethernet MAC address.
1099 Configure the RouterBoard 532 series on-chip
1100 Ethernet adapter MAC address.
1102 kmemleak= [KNL] Boot-time kmemleak enable/disable
1103 Valid arguments: on, off
1106 kstack=N [X86] Print N words from the kernel stack
1109 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1110 Default is 0 (don't ignore, but inject #GP)
1112 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1113 Default is 1 (enabled)
1115 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1118 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1120 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1122 kvm-intel.bypass_guest_pf=
1123 [KVM,Intel] Disables bypassing of guest page faults
1124 on Intel chips. Default is 1 (enabled)
1126 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1127 (virtualized MMU) support on capable Intel chips.
1128 Default is 1 (enabled)
1130 kvm-intel.emulate_invalid_guest_state=
1131 [KVM,Intel] Enable emulation of invalid guest states
1132 Default is 0 (disabled)
1134 kvm-intel.flexpriority=
1135 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1136 Default is 1 (enabled)
1138 kvm-intel.unrestricted_guest=
1139 [KVM,Intel] Disable unrestricted guest feature
1140 (virtualized real and unpaged mode) on capable
1141 Intel chips. Default is 1 (enabled)
1143 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1144 feature (tagged TLBs) on capable Intel chips.
1145 Default is 1 (enabled)
1151 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1154 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1157 libata.dma= [LIBATA] DMA control
1158 libata.dma=0 Disable all PATA and SATA DMA
1159 libata.dma=1 PATA and SATA Disk DMA only
1160 libata.dma=2 ATAPI (CDROM) DMA only
1161 libata.dma=4 Compact Flash DMA only
1162 Combinations also work, so libata.dma=3 enables DMA
1163 for disks and CDROMs, but not CFs.
1165 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1166 libata.ignore_hpa=0 keep BIOS limits (default)
1167 libata.ignore_hpa=1 ignore limits, using full disk
1169 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1173 libata.force= [LIBATA] Force configurations. The format is comma
1174 separated list of "[ID:]VAL" where ID is
1175 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1176 matching port, link or device. Basically, it matches
1177 the ATA ID string printed on console by libata. If
1178 the whole ID part is omitted, the last PORT and DEVICE
1179 values are used. If ID hasn't been specified yet, the
1180 configuration applies to all ports, links and devices.
1182 If only DEVICE is omitted, the parameter applies to
1183 the port and all links and devices behind it. DEVICE
1184 number of 0 either selects the first device or the
1185 first fan-out link behind PMP device. It does not
1186 select the host link. DEVICE number of 15 selects the
1187 host link and device attached to it.
1189 The VAL specifies the configuration to force. As long
1190 as there's no ambiguity shortcut notation is allowed.
1191 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1192 The following configurations can be forced.
1194 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1195 Any ID with matching PORT is used.
1197 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1199 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1200 udma[/][16,25,33,44,66,100,133] notation is also
1203 * [no]ncq: Turn on or off NCQ.
1205 * nohrst, nosrst, norst: suppress hard, soft
1208 If there are multiple matching configurations changing
1209 the same attribute, the last one is used.
1211 lmb=debug [KNL] Enable lmb debug messages.
1213 load_ramdisk= [RAM] List of ramdisks to load from floppy
1214 See Documentation/blockdev/ramdisk.txt.
1216 lockd.nlm_grace_period=P [NFS] Assign grace period.
1219 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1222 lockd.nlm_timeout=T [NFS] Assign timeout value.
1225 lockd.nlm_udpport=M [NFS] Assign UDP port.
1228 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1231 loglevel= All Kernel Messages with a loglevel smaller than the
1232 console loglevel will be printed to the console. It can
1233 also be changed with klogd or other programs. The
1234 loglevels are defined as follows:
1236 0 (KERN_EMERG) system is unusable
1237 1 (KERN_ALERT) action must be taken immediately
1238 2 (KERN_CRIT) critical conditions
1239 3 (KERN_ERR) error conditions
1240 4 (KERN_WARNING) warning conditions
1241 5 (KERN_NOTICE) normal but significant condition
1242 6 (KERN_INFO) informational
1243 7 (KERN_DEBUG) debug-level messages
1245 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1246 Format: { n | nk | nM }
1247 n must be a power of two. The default size
1248 is set in the kernel config file.
1250 logo.nologo [FB] Disables display of the built-in Linux logo.
1251 This may be used to provide more screen space for
1252 kernel log messages and is useful when debugging
1253 kernel boot problems.
1255 lp=0 [LP] Specify parallel ports to use, e.g,
1256 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1257 lp=reset first parallel port). 'lp=0' disables the
1258 lp=auto printer driver. 'lp=reset' (which can be
1259 specified in addition to the ports) causes
1260 attached printers to be reset. Using
1261 lp=port1,port2,... specifies the parallel ports
1262 to associate lp devices with, starting with
1263 lp0. A port specification may be 'none' to skip
1264 that lp device, or a parport name such as
1265 'parport0'. Specifying 'lp=auto' instead of a
1266 port specification list means that device IDs
1267 from each port should be examined, to see if
1268 an IEEE 1284-compliant printer is attached; if
1269 so, the driver will manage that printer.
1270 See also header of drivers/char/lp.c.
1273 Sets loops_per_jiffy to given constant, thus avoiding
1274 time-consuming boot-time autodetection (up to 250 ms per
1275 CPU). 0 enables autodetection (default). To determine
1276 the correct value for your kernel, boot with normal
1277 autodetection and see what value is printed. Note that
1278 on SMP systems the preset will be applied to all CPUs,
1279 which is likely to cause problems if your CPUs need
1280 significantly divergent settings. An incorrect value
1281 will cause delays in the kernel to be wrong, leading to
1282 unpredictable I/O errors and other breakage. Although
1283 unlikely, in the extreme case this might damage your
1287 Format: <io>,<irq>,<dma>
1289 mac5380= [HW,SCSI] Format:
1290 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1292 machvec= [IA64] Force the use of a particular machine-vector
1293 (machvec) in a generic kernel.
1294 Example: machvec=hpzx1_swiotlb
1296 machtype= [Loongson] Share the same kernel image file between different
1298 Example: machtype=lemote-yeeloong-2f-7inch
1300 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1301 than or equal to this physical address is ignored.
1303 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1304 should make use of. maxcpus=n : n >= 0 limits the
1305 kernel to using 'n' processors. n=0 is a special case,
1306 it is equivalent to "nosmp", which also disables
1309 max_loop= [LOOP] Maximum number of loopback devices that can
1313 max_luns= [SCSI] Maximum number of LUNs to probe.
1314 Should be between 1 and 2^32-1.
1317 [SCSI] Maximum number of LUNs received.
1318 Should be between 1 and 16384.
1322 mce [X86-32] Machine Check Exception
1324 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1326 md= [HW] RAID subsystems devices and level
1327 See Documentation/md.txt.
1330 Format: <first>,<last>
1331 Specifies range of consoles to be captured by the MDA.
1333 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1334 Amount of memory to be used when the kernel is not able
1335 to see the whole system memory or for test.
1336 [X86-32] Use together with memmap= to avoid physical
1337 address space collisions. Without memmap= PCI devices
1338 could be placed at addresses belonging to unused RAM.
1340 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1344 [KNL,SH] Allow user to override the default size for
1345 per-device physically contiguous DMA buffers.
1347 memmap=exactmap [KNL,X86] Enable setting of an exact
1348 E820 memory map, as specified by the user.
1349 Such memmap=exactmap lines can be constructed based on
1350 BIOS output or other requirements. See the memmap=nn@ss
1353 memmap=nn[KMG]@ss[KMG]
1354 [KNL] Force usage of a specific region of memory
1355 Region of memory to be used, from ss to ss+nn.
1357 memmap=nn[KMG]#ss[KMG]
1358 [KNL,ACPI] Mark specific memory as ACPI data.
1359 Region of memory to be used, from ss to ss+nn.
1361 memmap=nn[KMG]$ss[KMG]
1362 [KNL,ACPI] Mark specific memory as reserved.
1363 Region of memory to be used, from ss to ss+nn.
1364 Example: Exclude memory from 0x18690000-0x1869ffff
1365 memmap=64K$0x18690000
1367 memmap=0x10000$0x18690000
1369 memory_corruption_check=0/1 [X86]
1370 Some BIOSes seem to corrupt the first 64k of
1371 memory when doing things like suspend/resume.
1372 Setting this option will scan the memory
1373 looking for corruption. Enabling this will
1374 both detect corruption and prevent the kernel
1375 from using the memory being corrupted.
1376 However, its intended as a diagnostic tool; if
1377 repeatable BIOS-originated corruption always
1378 affects the same memory, you can use memmap=
1379 to prevent the kernel from using that memory.
1381 memory_corruption_check_size=size [X86]
1382 By default it checks for corruption in the low
1383 64k, making this memory unavailable for normal
1384 use. Use this parameter to scan for
1385 corruption in more or less memory.
1387 memory_corruption_check_period=seconds [X86]
1388 By default it checks for corruption every 60
1389 seconds. Use this parameter to check at some
1390 other rate. 0 disables periodic checking.
1392 memtest= [KNL,X86] Enable memtest
1394 default : 0 <disable>
1395 Specifies the number of memtest passes to be
1396 performed. Each pass selects another test
1397 pattern from a given set of patterns. Memtest
1398 fills the memory with this pattern, validates
1399 memory contents and reserves bad memory
1400 regions that are detected.
1402 meye.*= [HW] Set MotionEye Camera parameters
1403 See Documentation/video4linux/meye.txt.
1405 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1406 Multi-Function General Purpose Timers on AMD Geode
1409 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1410 the BIOS has incorrectly applied a workaround. TinyBIOS
1411 version 0.98 is known to be affected, 0.99 fixes the
1412 problem by letting the user disable the workaround.
1416 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1417 physical address is ignored.
1419 mini2440= [ARM,HW,KNL]
1420 Format:[0..2][b][c][t]
1422 MINI2440 configuration specification:
1423 0 - The attached screen is the 3.5" TFT
1424 1 - The attached screen is the 7" TFT
1425 2 - The VGA Shield is attached (1024x768)
1426 Leaving out the screen size parameter will not load
1427 the TFT driver, and the framebuffer will be left
1429 b - Enable backlight. The TFT backlight pin will be
1430 linked to the kernel VESA blanking code and a GPIO
1431 LED. This parameter is not necessary when using the
1433 c - Enable the s3c camera interface.
1434 t - Reserved for enabling touchscreen support. The
1435 touchscreen support is not enabled in the mainstream
1436 kernel as of 2.6.30, a preliminary port can be found
1437 in the "bleeding edge" mini2440 support kernel at
1438 http://repo.or.cz/w/linux-2.6/mini2440.git
1441 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1442 parameter allows control of the logging verbosity for
1443 the additional memory initialisation checks. A value
1444 of 0 disables mminit logging and a level of 4 will
1445 log everything. Information is printed at KERN_DEBUG
1446 so loglevel=8 may also need to be specified.
1449 [MOUSE] Maximum time between finger touching and
1450 leaving touchpad surface for touch to be considered
1451 a tap and be reported as a left button click (for
1452 touchpads working in absolute mode only).
1454 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1455 reporting absolute coordinates, such as tablets
1456 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1457 reporting absolute coordinates, such as tablets
1459 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1460 is similar to kernelcore except it specifies the
1461 amount of memory used for migratable allocations.
1462 If both kernelcore and movablecore is specified,
1463 then kernelcore will be at *least* the specified
1464 value but may be more. If movablecore on its own
1465 is specified, the administrator must be careful
1466 that the amount of memory usable for all allocations
1472 MTD_Partition= [MTD]
1473 Format: <name>,<region-number>,<size>,<offset>
1475 MTD_Region= [MTD] Format:
1476 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1479 See drivers/mtd/cmdlinepart.c.
1481 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1483 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1485 boundary - index of last SLC block on Flex-OneNAND.
1486 The remaining blocks are configured as MLC blocks.
1487 lock - Configure if Flex-OneNAND boundary should be locked.
1488 Once locked, the boundary cannot be changed.
1489 1 indicates lock status, 0 indicates unlock status.
1492 ARM/S3C2412 JIVE boot control
1494 See arch/arm/mach-s3c2412/mach-jive.c
1496 mtouchusb.raw_coordinates=
1497 [HW] Make the MicroTouch USB driver use raw coordinates
1498 ('y', default) or cooked coordinates ('n')
1500 mtrr_chunk_size=nn[KMG] [X86]
1501 used for mtrr cleanup. It is largest continuous chunk
1502 that could hold holes aka. UC entries.
1504 mtrr_gran_size=nn[KMG] [X86]
1505 Used for mtrr cleanup. It is granularity of mtrr block.
1507 Large value could prevent small alignment from
1510 mtrr_spare_reg_nr=n [X86]
1512 Range: 0,7 : spare reg number
1514 Used for mtrr cleanup. It is spare mtrr entries number.
1515 Set to 2 or more if your graphical card needs more.
1517 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1520 See header of drivers/scsi/NCR_D700.c.
1524 ncr53c400= [HW,SCSI]
1526 ncr53c400a= [HW,SCSI]
1528 ncr53c406a= [HW,SCSI]
1530 ncr53c8xx= [HW,SCSI]
1532 netdev= [NET] Network devices parameters
1533 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1534 Note that mem_start is often overloaded to mean
1535 something different and driver-specific.
1536 This usage is only documented in each driver source
1540 [NETFILTER] Enable connection tracking flow accounting
1541 0 to disable accounting
1542 1 to enable accounting
1543 Default value depends on CONFIG_NF_CT_ACCT that is
1544 going to be removed in 2.6.29.
1547 See Documentation/filesystems/nfsroot.txt.
1549 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1550 See Documentation/filesystems/nfsroot.txt.
1552 nfs.callback_tcpport=
1553 [NFS] set the TCP port on which the NFSv4 callback
1554 channel should listen.
1557 [NFS] sets the pathname to the program which is used
1558 to update the NFS client cache entries.
1560 nfs.cache_getent_timeout=
1561 [NFS] sets the timeout after which an attempt to
1562 update a cache entry is deemed to have failed.
1564 nfs.idmap_cache_timeout=
1565 [NFS] set the maximum lifetime for idmapper cache
1569 [NFS] enable 64-bit inode numbers.
1570 If zero, the NFS client will fake up a 32-bit inode
1571 number for the readdir() and stat() syscalls instead
1572 of returning the full 64-bit number.
1573 The default is to return 64-bit inode numbers.
1575 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1576 when a NMI is triggered.
1577 Format: [state][,regs][,debounce][,die]
1579 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1580 Format: [panic,][num]
1582 0 - turn nmi_watchdog off
1583 1 - use the IO-APIC timer for the NMI watchdog
1584 2 - use the local APIC for the NMI watchdog using
1585 a performance counter. Note: This will use one
1586 performance counter and the local APIC's performance
1588 When panic is specified, panic when an NMI watchdog
1590 This is useful when you use a panic=... timeout and
1591 need the box quickly up again.
1592 Instead of 1 and 2 it is possible to use the following
1593 symbolic names: lapic and ioapic
1594 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1596 netpoll.carrier_timeout=
1597 [NET] Specifies amount of time (in seconds) that
1598 netpoll should wait for a carrier. By default netpoll
1601 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1602 emulation library even if a 387 maths coprocessor
1606 [HW] Never suspend the console
1607 Disable suspending of consoles during suspend and
1608 hibernate operations. Once disabled, debugging
1609 messages can reach various consoles while the rest
1610 of the system is being put to sleep (ie, while
1611 debugging driver suspend/resume hooks). This may
1612 not work reliably with all consoles, but is known
1613 to work with serial and VGA consoles.
1615 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1616 caches in the slab allocator. Saves per-node memory,
1617 but will impact performance.
1621 noapic [SMP,APIC] Tells the kernel to not make use of any
1622 IOAPICs that may be present in the system.
1624 nobats [PPC] Do not use BATs for mapping kernel lowmem
1625 on "Classic" PPC cores.
1629 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1631 nodelayacct [KNL] Disable per-task delay accounting
1633 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1635 nodsp [SH] Disable hardware DSP at boot time.
1637 noefi [X86] Disable EFI runtime services support.
1642 On X86-32 available only on PAE configured kernels.
1643 noexec=on: enable non-executable mappings (default)
1644 noexec=off: disable non-executable mappings
1647 This affects only 32-bit executables.
1648 noexec32=on: enable non-executable mappings (default)
1649 read doesn't imply executable mappings
1650 noexec32=off: disable non-executable mappings
1651 read implies executable mappings
1653 nofpu [SH] Disable hardware FPU at boot time.
1655 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1656 register save and restore. The kernel will only save
1657 legacy floating-point registers on task switch.
1659 noxsave [BUGS=X86] Disables x86 extended register state save
1660 and restore using xsave. The kernel will fallback to
1661 enabling legacy floating-point and sse state.
1663 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1664 wfi(ARM) instruction doesn't work correctly and not to
1665 use it. This is also useful when using JTAG debugger.
1667 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1668 instruction doesn't work correctly and not to
1671 no_file_caps Tells the kernel not to honor file capabilities. The
1672 only way then for a file to be executed with privilege
1673 is to be setuid root or executed by root.
1675 nohalt [IA-64] Tells the kernel not to use the power saving
1676 function PAL_HALT_LIGHT when idle. This increases
1677 power-consumption. On the positive side, it reduces
1678 interrupt wake-up latency, which may improve performance
1679 in certain environments such as networked servers or
1682 nohz= [KNL] Boottime enable/disable dynamic ticks
1683 Valid arguments: on, off
1686 noiotrap [SH] Disables trapped I/O port accesses.
1688 noirqdebug [X86-32] Disables the code which attempts to detect and
1689 disable unhandled interrupt sources.
1691 no_timer_check [X86,APIC] Disables the code which tests for
1692 broken timer IRQ sources.
1694 noisapnp [ISAPNP] Disables ISA PnP code.
1696 noinitrd [RAM] Tells the kernel not to load any configured
1699 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1704 nojitter [IA64] Disables jitter checking for ITC timers.
1706 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1708 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1710 noltlbs [PPC] Do not use large page/tlb entries for kernel
1711 lowmem mapping on PPC40x.
1713 nomca [IA-64] Disable machine check abort handling
1715 nomce [X86-32] Machine Check Exception
1717 nomfgpt [X86-32] Disable Multi-Function General Purpose
1718 Timer usage (for AMD Geode machines).
1720 norandmaps Don't use address space randomization. Equivalent to
1721 echo 0 > /proc/sys/kernel/randomize_va_space
1723 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1725 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1726 with UP alternatives
1728 noresidual [PPC] Don't use residual data on PReP machines.
1730 noresume [SWSUSP] Disables resume and restores original swap
1733 no-scroll [VGA] Disables scrollback.
1734 This is required for the Braillex ib80-piezo Braille
1735 reader made by F.H. Papenmeier (Germany).
1739 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1741 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1742 and disable the IO APIC. legacy for "maxcpus=0".
1744 nosoftlockup [KNL] Disable the soft-lockup detector.
1746 noswapaccount [KNL] Disable accounting of swap in memory resource
1747 controller. (See Documentation/cgroups/memory.txt)
1749 nosync [HW,M68K] Disables sync negotiation for all devices.
1751 notsc [BUGS=X86-32] Disable Time Stamp Counter
1753 nousb [USB] Disable the USB subsystem
1757 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1759 nptcg= [IA64] Override max number of concurrent global TLB
1760 purges which is reported from either PAL_VM_SUMMARY or
1763 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1765 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1766 one of ['zone', 'node', 'default'] can be specified
1767 This can be set from sysctl after boot.
1768 See Documentation/sysctl/vm.txt for details.
1770 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1771 See Documentation/debugging-via-ohci1394.txt for more
1774 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1775 Rather than timing out after 20 ms if an EC
1776 command is not properly ACKed, override the length
1777 of the timeout. We have interrupts disabled while
1778 waiting for the ACK, so if this is set too high
1779 interrupts *may* be lost!
1784 oprofile.timer= [HW]
1785 Use timer interrupt instead of performance counters
1787 oprofile.cpu_type= Force an oprofile cpu type
1788 This might be useful if you have an older oprofile
1789 userland or if you want common events.
1790 Format: { arch_perfmon }
1791 arch_perfmon: [X86] Force use of architectural
1792 perfmon on Intel CPUs instead of the
1793 CPU specific event set.
1795 osst= [HW,SCSI] SCSI Tape Driver
1796 Format: <buffer_size>,<write_threshold>
1797 See also Documentation/scsi/st.txt.
1799 panic= [KNL] Kernel behaviour on panic
1802 parkbd.port= [HW] Parallel port number the keyboard adapter is
1803 connected to, default is 0.
1805 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1806 0 for XT, 1 for AT (default is AT).
1809 parport= [HW,PPT] Specify parallel ports. 0 disables.
1810 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1811 Use 'auto' to force the driver to use any
1812 IRQ/DMA settings detected (the default is to
1813 ignore detected IRQ/DMA settings because of
1814 possible conflicts). You can specify the base
1815 address, IRQ, and DMA settings; IRQ and DMA
1816 should be numbers, or 'auto' (for using detected
1817 settings on that particular port), or 'nofifo'
1818 (to avoid using a FIFO even if it is detected).
1819 Parallel ports are assigned in the order they
1820 are specified on the command line, starting
1823 parport_init_mode= [HW,PPT]
1824 Configure VIA parallel port to operate in
1825 a specific mode. This is necessary on Pegasos
1826 computer where firmware has no options for setting
1827 up parallel port mode and sets it to spp.
1828 Currently this function knows 686a and 8231 chips.
1829 Format: [spp|ps2|epp|ecp|ecpepp]
1831 pas2= [HW,OSS] Format:
1832 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1835 See header of drivers/scsi/pas16.c.
1838 Halt all CPUs after the first oops has been printed for
1839 the specified number of seconds. This is to be used if
1840 your oopses keep scrolling off the screen.
1845 See header of drivers/block/paride/pcd.c.
1846 See also Documentation/blockdev/paride.txt.
1848 pci=option[,option...] [PCI] various PCI subsystem options:
1849 earlydump [X86] dump PCI config space before the kernel
1851 off [X86] don't probe for the PCI bus
1852 bios [X86-32] force use of PCI BIOS, don't access
1853 the hardware directly. Use this if your machine
1854 has a non-standard PCI host bridge.
1855 nobios [X86-32] disallow use of PCI BIOS, only direct
1856 hardware access methods are allowed. Use this
1857 if you experience crashes upon bootup and you
1858 suspect they are caused by the BIOS.
1859 conf1 [X86] Force use of PCI Configuration
1861 conf2 [X86] Force use of PCI Configuration
1863 noaer [PCIE] If the PCIEAER kernel config parameter is
1864 enabled, this kernel boot option can be used to
1865 disable the use of PCIE advanced error reporting.
1866 nodomains [PCI] Disable support for multiple PCI
1867 root domains (aka PCI segments, in ACPI-speak).
1868 nommconf [X86] Disable use of MMCONFIG for PCI
1870 check_enable_amd_mmconf [X86] check for and enable
1871 properly configured MMIO access to PCI
1872 config space on AMD family 10h CPU
1873 nomsi [MSI] If the PCI_MSI kernel config parameter is
1874 enabled, this kernel boot option can be used to
1875 disable the use of MSI interrupts system-wide.
1876 noioapicquirk [APIC] Disable all boot interrupt quirks.
1877 Safety option to keep boot IRQs enabled. This
1878 should never be necessary.
1879 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1880 primary IO-APIC for bridges that cannot disable
1881 boot IRQs. This fixes a source of spurious IRQs
1882 when the system masks IRQs.
1883 noioapicreroute [APIC] Disable workaround that uses the
1884 boot IRQ equivalent of an IRQ that connects to
1885 a chipset where boot IRQs cannot be disabled.
1886 The opposite of ioapicreroute.
1887 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1888 routing table. These calls are known to be buggy
1889 on several machines and they hang the machine
1890 when used, but on other computers it's the only
1891 way to get the interrupt routing table. Try
1892 this option if the kernel is unable to allocate
1893 IRQs or discover secondary PCI buses on your
1895 rom [X86] Assign address space to expansion ROMs.
1896 Use with caution as certain devices share
1897 address decoders between ROMs and other
1899 norom [X86] Do not assign address space to
1900 expansion ROMs that do not already have
1901 BIOS assigned address ranges.
1902 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1903 assigned automatically to PCI devices. You can
1904 make the kernel exclude IRQs of your ISA cards
1906 pirqaddr=0xAAAAA [X86] Specify the physical address
1907 of the PIRQ table (normally generated
1908 by the BIOS) if it is outside the
1909 F0000h-100000h range.
1910 lastbus=N [X86] Scan all buses thru bus #N. Can be
1911 useful if the kernel is unable to find your
1912 secondary buses and you want to tell it
1913 explicitly which ones they are.
1914 assign-busses [X86] Always assign all PCI bus
1915 numbers ourselves, overriding
1916 whatever the firmware may have done.
1917 usepirqmask [X86] Honor the possible IRQ mask stored
1918 in the BIOS $PIR table. This is needed on
1919 some systems with broken BIOSes, notably
1920 some HP Pavilion N5400 and Omnibook XE3
1921 notebooks. This will have no effect if ACPI
1922 IRQ routing is enabled.
1923 noacpi [X86] Do not use ACPI for IRQ routing
1924 or for PCI scanning.
1925 use_crs [X86] Use _CRS for PCI resource
1927 routeirq Do IRQ routing for all PCI devices.
1928 This is normally done in pci_enable_device(),
1929 so this option is a temporary workaround
1930 for broken drivers that don't call it.
1931 skip_isa_align [X86] do not align io start addr, so can
1932 handle more pci cards
1933 firmware [ARM] Do not re-enumerate the bus but instead
1934 just use the configuration from the
1935 bootloader. This is currently used on
1936 IXP2000 systems where the bus has to be
1937 configured a certain way for adjunct CPUs.
1938 noearly [X86] Don't do any early type 1 scanning.
1939 This might help on some broken boards which
1940 machine check when some devices' config space
1941 is read. But various workarounds are disabled
1942 and some IOMMU drivers will not work.
1943 bfsort Sort PCI devices into breadth-first order.
1944 This sorting is done to get a device
1945 order compatible with older (<= 2.4) kernels.
1946 nobfsort Don't sort PCI devices into breadth-first order.
1947 cbiosize=nn[KMG] The fixed amount of bus space which is
1948 reserved for the CardBus bridge's IO window.
1949 The default value is 256 bytes.
1950 cbmemsize=nn[KMG] The fixed amount of bus space which is
1951 reserved for the CardBus bridge's memory
1952 window. The default value is 64 megabytes.
1955 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1956 Specifies alignment and device to reassign
1957 aligned memory resources.
1958 If <order of align> is not specified,
1959 PAGE_SIZE is used as alignment.
1960 PCI-PCI bridge can be specified, if resource
1961 windows need to be expanded.
1962 ecrc= Enable/disable PCIe ECRC (transaction layer
1963 end-to-end CRC checking).
1964 bios: Use BIOS/firmware settings. This is the
1969 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1972 force Enable ASPM even on devices that claim not to support it.
1973 WARNING: Forcing ASPM on may cause system lockups.
1975 pcmv= [HW,PCMCIA] BadgePAD 4
1978 See Documentation/blockdev/paride.txt.
1980 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1983 See arch/parisc/kernel/pdc_chassis.c
1985 percpu_alloc= Select which percpu first chunk allocator to use.
1986 Currently supported values are "embed" and "page".
1987 Archs may support subset or none of the selections.
1988 See comments in mm/percpu.c for details on each
1989 allocator. This parameter is primarily for debugging
1990 and performance comparison.
1993 See Documentation/blockdev/paride.txt.
1996 See Documentation/blockdev/paride.txt.
1998 pirq= [SMP,APIC] Manual mp-table setup
1999 See Documentation/x86/i386/IO-APIC.txt.
2001 plip= [PPT,NET] Parallel port network link
2002 Format: { parport<nr> | timid | 0 }
2003 See also Documentation/parport.txt.
2005 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2006 Override pmtimer IOPort with a hex value.
2010 Enable PNP debug messages. This depends on the
2011 CONFIG_PNP_DEBUG_MESSAGES option.
2017 { on | off | curr | res | no-curr | no-res }
2020 [ISAPNP] Exclude IRQs for the autoconfiguration
2023 [ISAPNP] Exclude DMAs for the autoconfiguration
2025 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2026 Ranges are in pairs (I/O port base and size).
2029 [ISAPNP] Exclude memory regions for the
2031 Ranges are in pairs (memory base and size).
2033 ports= [IP_VS_FTP] IPVS ftp helper module
2035 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2037 Format: <port>,<port>....
2039 print-fatal-signals=
2040 [KNL] debug: print fatal signals
2042 If enabled, warn about various signal handling
2043 related application anomalies: too many signals,
2044 too many POSIX.1 timers, fatal signals causing a
2047 If you hit the warning due to signal overflow,
2048 you might want to try "ulimit -i unlimited".
2052 printk.time= Show timing data prefixed to each printk message line
2053 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2055 processor.max_cstate= [HW,ACPI]
2056 Limit processor to maximum C-state
2057 max_cstate=9 overrides any DMI blacklist limit.
2059 processor.nocst [HW,ACPI]
2060 Ignore the _CST method to determine C-states,
2061 instead using the legacy FADT method
2063 profile= [KNL] Enable kernel profiling via /proc/profile
2064 Format: [schedule,]<number>
2065 Param: "schedule" - profile schedule points.
2066 Param: <number> - step/bucket size as a power of 2 for
2067 statistical time based profiling.
2068 Param: "sleep" - profile D-state sleeping (millisecs).
2069 Requires CONFIG_SCHEDSTATS
2070 Param: "kvm" - profile VM exits.
2072 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2074 See Documentation/blockdev/ramdisk.txt.
2076 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2077 probe for; one of (bare|imps|exps|lifebook|any).
2078 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2080 psmouse.resetafter= [HW,MOUSE]
2081 Try to reset the device after so many bad packets
2084 [HW,MOUSE] Set desired mouse resolution, in dpi.
2085 psmouse.smartscroll=
2086 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2087 0 = disabled, 1 = enabled (default).
2089 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2091 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2094 See Documentation/blockdev/paride.txt.
2097 [KNL] Number of legacy pty's. Overwrites compiled-in
2100 quiet [KNL] Disable most log messages
2105 See Documentation/md.txt.
2107 ramdisk_blocksize= [RAM]
2108 See Documentation/blockdev/ramdisk.txt.
2110 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2111 See Documentation/blockdev/ramdisk.txt.
2113 rcupdate.blimit= [KNL,BOOT]
2114 Set maximum number of finished RCU callbacks to process
2117 rcupdate.qhimark= [KNL,BOOT]
2118 Set threshold of queued
2119 RCU callbacks over which batch limiting is disabled.
2121 rcupdate.qlowmark= [KNL,BOOT]
2122 Set threshold of queued RCU callbacks below which
2123 batch limiting is re-enabled.
2127 Run specified binary instead of /init from the ramdisk,
2128 used for early userspace startup. See initrd.
2130 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2131 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2132 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2135 [KNL, SMP] Set scheduler's default relax_domain_level.
2136 See Documentation/cgroups/cpusets.txt.
2138 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2140 reservetop= [X86-32]
2142 Reserves a hole at the top of the kernel virtual
2145 reset_devices [KNL] Force drivers to reset the underlying device
2146 during initialization.
2149 Specify the partition device for software suspend
2151 resume_offset= [SWSUSP]
2152 Specify the offset from the beginning of the partition
2153 given by "resume=" at which the swap header is located,
2154 in <PAGE_SIZE> units (needed only for swap files).
2155 See Documentation/power/swsusp-and-swap-files.txt
2157 retain_initrd [RAM] Keep initrd memory after extraction
2159 rhash_entries= [KNL,NET]
2160 Set number of hash buckets for route cache
2162 riscom8= [HW,SERIAL]
2163 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2165 ro [KNL] Mount root device read-only on boot
2167 root= [KNL] Root filesystem
2169 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2170 mount the root filesystem
2172 rootflags= [KNL] Set root filesystem mount option string
2174 rootfstype= [KNL] Set root filesystem type
2176 rootwait [KNL] Wait (indefinitely) for root device to show up.
2177 Useful for devices that are detected asynchronously
2178 (e.g. USB and MMC devices).
2180 rw [KNL] Mount root device read-write on boot
2182 S [KNL] Run init in single mode
2185 See drivers/net/irda/sa1100_ir.c.
2187 sbni= [NET] Granch SBNI12 leased line adapter
2189 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2190 Format: <io>[,<timeout>[,<isapnp>]]
2192 scsi_debug_*= [SCSI]
2193 See drivers/scsi/scsi_debug.c.
2195 scsi_default_dev_flags=
2196 [SCSI] SCSI default device flags
2199 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2200 Format: <vendor>:<model>:<flags>
2201 (flags are integer value)
2203 scsi_logging_level= [SCSI] a bit mask of logging levels
2204 See drivers/scsi/scsi_logging.h for bits. Also
2205 settable via sysctl at dev.scsi.logging_level
2206 (/proc/sys/dev/scsi/logging_level).
2207 There is also a nice 'scsi_logging_level' script in the
2208 S390-tools package, available for download at
2209 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2211 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2212 discovered. async scans them in kernel threads,
2213 allowing boot to proceed. none ignores them, expecting
2214 user space to do the scan.
2216 security= [SECURITY] Choose a security module to enable at boot.
2217 If this boot parameter is not specified, only the first
2218 security module asking for security registration will be
2219 loaded. An invalid security module name will be treated
2220 as if no module has been chosen.
2222 selinux= [SELINUX] Disable or enable SELinux at boot time.
2223 Format: { "0" | "1" }
2224 See security/selinux/Kconfig help text.
2227 Default value is set via kernel config option.
2228 If enabled at boot time, /selinux/disable can be used
2229 later to disable prior to initial policy load.
2231 serialnumber [BUGS=X86-32]
2234 Maximal number of shapers.
2236 show_msr= [x86] show boot-time MSR settings
2237 Format: { <integer> }
2238 Show boot-time (BIOS-initialized) MSR settings.
2239 The parameter means the number of CPUs to show,
2240 for example 1 means boot CPU only.
2243 See header of drivers/scsi/sim710.c.
2250 slub_debug[=options[,slabs]] [MM, SLUB]
2251 Enabling slub_debug allows one to determine the
2252 culprit if slab objects become corrupted. Enabling
2253 slub_debug can create guard zones around objects and
2254 may poison objects when not in use. Also tracks the
2255 last alloc / free. For more information see
2256 Documentation/vm/slub.txt.
2258 slub_max_order= [MM, SLUB]
2259 Determines the maximum allowed order for slabs.
2260 A high setting may cause OOMs due to memory
2261 fragmentation. For more information see
2262 Documentation/vm/slub.txt.
2264 slub_min_objects= [MM, SLUB]
2265 The minimum number of objects per slab. SLUB will
2266 increase the slab order up to slub_max_order to
2267 generate a sufficiently large slab able to contain
2268 the number of objects indicated. The higher the number
2269 of objects the smaller the overhead of tracking slabs
2270 and the less frequently locks need to be acquired.
2271 For more information see Documentation/vm/slub.txt.
2273 slub_min_order= [MM, SLUB]
2274 Determines the mininum page order for slabs. Must be
2275 lower than slub_max_order.
2276 For more information see Documentation/vm/slub.txt.
2278 slub_nomerge [MM, SLUB]
2279 Disable merging of slabs with similar size. May be
2280 necessary if there is some reason to distinguish
2281 allocs to different slabs. Debug options disable
2282 merging on their own.
2283 For more information see Documentation/vm/slub.txt.
2286 Format: <io1>[,<io2>[,...,<io8>]]
2288 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2289 attempt to substitute SMP alternatives once at boot.
2291 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2292 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2293 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2294 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2295 smsc-ircc2.ircc_irq= [HW] IRQ line
2296 smsc-ircc2.ircc_dma= [HW] DMA channel
2297 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2298 0: Toshiba Satellite 1800 (GP data pin select)
2299 1: Fast pin select (default)
2302 snd-ad1816a= [HW,ALSA]
2304 snd-ad1848= [HW,ALSA]
2306 snd-ali5451= [HW,ALSA]
2308 snd-als100= [HW,ALSA]
2310 snd-als4000= [HW,ALSA]
2312 snd-azt2320= [HW,ALSA]
2314 snd-cmi8330= [HW,ALSA]
2316 snd-cmipci= [HW,ALSA]
2318 snd-cs4231= [HW,ALSA]
2320 snd-cs4232= [HW,ALSA]
2322 snd-cs4236= [HW,ALSA]
2324 snd-cs4281= [HW,ALSA]
2326 snd-cs46xx= [HW,ALSA]
2328 snd-dt019x= [HW,ALSA]
2330 snd-dummy= [HW,ALSA]
2332 snd-emu10k1= [HW,ALSA]
2334 snd-ens1370= [HW,ALSA]
2336 snd-ens1371= [HW,ALSA]
2338 snd-es968= [HW,ALSA]
2340 snd-es1688= [HW,ALSA]
2342 snd-es18xx= [HW,ALSA]
2344 snd-es1938= [HW,ALSA]
2346 snd-es1968= [HW,ALSA]
2348 snd-fm801= [HW,ALSA]
2350 snd-gusclassic= [HW,ALSA]
2352 snd-gusextreme= [HW,ALSA]
2354 snd-gusmax= [HW,ALSA]
2358 snd-ice1712= [HW,ALSA]
2360 snd-intel8x0= [HW,ALSA]
2362 snd-interwave= [HW,ALSA]
2367 snd-korg1212= [HW,ALSA]
2369 snd-maestro3= [HW,ALSA]
2371 snd-mpu401= [HW,ALSA]
2373 snd-mtpav= [HW,ALSA]
2375 snd-nm256= [HW,ALSA]
2377 snd-opl3sa2= [HW,ALSA]
2385 snd-opti93x= [HW,ALSA]
2389 snd-rme32= [HW,ALSA]
2391 snd-rme96= [HW,ALSA]
2393 snd-rme9652= [HW,ALSA]
2399 snd-sbawe= [HW,ALSA]
2401 snd-serial= [HW,ALSA]
2403 snd-sgalaxy= [HW,ALSA]
2405 snd-sonicvibes= [HW,ALSA]
2410 snd-sun-cs4231= [HW,ALSA]
2412 snd-trident= [HW,ALSA]
2414 snd-usb-audio= [HW,ALSA,USB]
2416 snd-via82xx= [HW,ALSA]
2418 snd-virmidi= [HW,ALSA]
2420 snd-wavefront= [HW,ALSA]
2422 snd-ymfpci= [HW,ALSA]
2425 [KNL] Should the soft-lockup detector generate panics.
2427 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2428 See Documentation/sonypi.txt
2430 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2431 See Documentation/serial/specialix.txt.
2433 spia_io_base= [HW,MTD]
2439 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2441 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2442 See Documentation/scsi/st.txt.
2445 Enabled the stack tracer on boot up.
2449 Set the STI (builtin display/keyboard on the HP-PARISC
2450 machines) console (graphic card) which should be used
2451 as the initial boot-console.
2452 See also comment in drivers/video/console/sticore.c.
2455 See comment in drivers/video/console/sticore.c.
2458 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2460 sunrpc.min_resvport=
2461 sunrpc.max_resvport=
2463 SunRPC servers often require that client requests
2464 originate from a privileged port (i.e. a port in the
2465 range 0 < portnr < 1024).
2466 An administrator who wishes to reserve some of these
2467 ports for other uses may adjust the range that the
2468 kernel's sunrpc client considers to be privileged
2469 using these two parameters to set the minimum and
2470 maximum port values.
2474 Control how the NFS server code allocates CPUs to
2475 service thread pools. Depending on how many NICs
2476 you have and where their interrupts are bound, this
2477 option will affect which CPUs will do NFS serving.
2478 Note: this parameter cannot be changed while the
2479 NFS server is running.
2481 auto the server chooses an appropriate mode
2482 automatically using heuristics
2483 global a single global pool contains all CPUs
2484 percpu one pool for each CPU
2485 pernode one pool for each NUMA node (equivalent
2486 to global on non-NUMA machines)
2488 sunrpc.tcp_slot_table_entries=
2489 sunrpc.udp_slot_table_entries=
2491 Sets the upper limit on the number of simultaneous
2492 RPC calls that can be sent from the client to a
2493 server. Increasing these values may allow you to
2494 improve throughput, but will also increase the
2495 amount of memory reserved for use by the client.
2497 swiotlb= [IA-64] Number of I/O TLB slabs
2501 sym53c416= [HW,SCSI]
2502 See header of drivers/scsi/sym53c416.c.
2504 sysrq_always_enabled
2506 Ignore sysrq setting - this boot parameter will
2507 neutralize any effect of /proc/sys/kernel/sysrq.
2508 Useful for debugging.
2511 See header of drivers/scsi/t128.c.
2515 test_suspend= [SUSPEND]
2516 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2517 standby suspend) as the system sleep state to briefly
2518 enter during system startup. The system is woken from
2519 this state using a wakeup-capable RTC alarm.
2521 thash_entries= [KNL,NET]
2522 Set number of hash buckets for TCP connection
2524 thermal.act= [HW,ACPI]
2525 -1: disable all active trip points in all thermal zones
2526 <degrees C>: override all lowest active trip points
2528 thermal.crt= [HW,ACPI]
2529 -1: disable all critical trip points in all thermal zones
2530 <degrees C>: override all critical trip points
2532 thermal.nocrt= [HW,ACPI]
2533 Set to disable actions on ACPI thermal zone
2534 critical and hot trip points.
2536 thermal.off= [HW,ACPI]
2537 1: disable ACPI thermal control
2539 thermal.psv= [HW,ACPI]
2540 -1: disable all passive trip points
2541 <degrees C>: override all passive trip points to this
2544 thermal.tzp= [HW,ACPI]
2545 Specify global default ACPI thermal zone polling rate
2546 <deci-seconds>: poll all this frequency
2547 0: no polling (default)
2550 See comment before function dc390_setup() in
2551 drivers/scsi/tmscsim.c.
2555 Specify if the kernel should make use of the cpu
2556 topology informations if the hardware supports these.
2557 The scheduler will make use of these informations and
2558 e.g. base its process migration decisions on it.
2563 trace_buf_size=nn[KMG]
2564 [FTRACE] will set tracing buffer size.
2566 trace_event=[event-list]
2567 [FTRACE] Set and start specified trace events in order
2568 to facilitate early boot debugging.
2569 See also Documentation/trace/events.txt
2571 trix= [HW,OSS] MediaTrix AudioTrix Pro
2573 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2575 tsc= Disable clocksource-must-verify flag for TSC.
2577 [x86] reliable: mark tsc clocksource as reliable, this
2578 disables clocksource verification at runtime.
2579 Used to enable high-resolution timer mode on older
2580 hardware, and in virtualized environment.
2582 turbografx.map[2|3]= [HW,JOY]
2583 TurboGraFX parallel port interface
2585 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2586 See also Documentation/input/joystick-parport.txt
2588 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2589 See header of drivers/scsi/u14-34f.c.
2597 uhash_entries= [KNL,NET]
2598 Set number of hash buckets for UDP/UDP-Lite connections
2601 [USB] Ignore overcurrent events (default N).
2602 Some badly-designed motherboards generate lots of
2603 bogus events, for ports that aren't wired to
2604 anything. Set this parameter to avoid log spamming.
2605 Note that genuine overcurrent events won't be
2610 Set unknown_nmi_panic=1 early on boot.
2612 usbcore.autosuspend=
2613 [USB] The autosuspend time delay (in seconds) used
2614 for newly-detected USB devices (default 2). This
2615 is the time required before an idle device will be
2616 autosuspended. Devices for which the delay is set
2617 to a negative value won't be autosuspended at all.
2619 usbcore.usbfs_snoop=
2620 [USB] Set to log all usbfs traffic (default 0 = off).
2622 usbcore.blinkenlights=
2623 [USB] Set to cycle leds on hubs (default 0 = off).
2625 usbcore.old_scheme_first=
2626 [USB] Start with the old device initialization
2627 scheme (default 0 = off).
2629 usbcore.use_both_schemes=
2630 [USB] Try the other device initialization scheme
2631 if the first one fails (default 1 = enabled).
2633 usbcore.initial_descriptor_timeout=
2634 [USB] Specifies timeout for the initial 64-byte
2635 USB_REQ_GET_DESCRIPTOR request in milliseconds
2636 (default 5000 = 5.0 seconds).
2639 [USBHID] The interval which mice are to be polled at.
2641 usb-storage.delay_use=
2642 [UMS] The delay in seconds before a new device is
2643 scanned for Logical Units (default 5).
2646 [UMS] A list of quirks entries to supplement or
2647 override the built-in unusual_devs list. List
2648 entries are separated by commas. Each entry has
2649 the form VID:PID:Flags where VID and PID are Vendor
2650 and Product ID values (4-digit hex numbers) and
2651 Flags is a set of characters, each corresponding
2652 to a common usb-storage quirk flag as follows:
2653 a = SANE_SENSE (collect more than 18 bytes
2655 c = FIX_CAPACITY (decrease the reported
2656 device capacity by one sector);
2657 h = CAPACITY_HEURISTICS (decrease the
2658 reported device capacity by one
2659 sector if the number is odd);
2660 i = IGNORE_DEVICE (don't bind to this
2662 l = NOT_LOCKABLE (don't try to lock and
2663 unlock ejectable media);
2664 m = MAX_SECTORS_64 (don't transfer more
2665 than 64 sectors = 32 KB at a time);
2666 o = CAPACITY_OK (accept the capacity
2667 reported by the device);
2668 r = IGNORE_RESIDUE (the device reports
2669 bogus residue values);
2670 s = SINGLE_LUN (the device has only one
2672 w = NO_WP_DETECT (don't test whether the
2673 medium is write-protected).
2674 Example: quirks=0419:aaf5:rl,0421:0433:rc
2677 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2678 vdso=1: enable VDSO (default)
2679 vdso=0: disable VDSO mapping
2682 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2683 vdso32=1: enable 32-bit VDSO (default)
2684 vdso32=0: disable 32-bit VDSO mapping
2687 vector=percpu: enable percpu vector domain
2689 video= [FB] Frame buffer configuration
2690 See Documentation/fb/modedb.txt.
2692 vga= [BOOT,X86-32] Select a particular video mode
2693 See Documentation/x86/boot.txt and
2694 Documentation/svga.txt.
2695 Use vga=ask for menu.
2696 This is actually a boot loader parameter; the value is
2697 passed to the kernel using a special protocol.
2699 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2700 size of <nn>. This can be used to increase the
2701 minimum size (128MB on x86). It can also be used to
2702 decrease the size and leave more room for directly
2705 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2708 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2711 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2714 vt.default_blu= [VT]
2715 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2716 Change the default blue palette of the console.
2717 This is a 16-member array composed of values
2720 vt.default_grn= [VT]
2721 Format: <green0>,<green1>,<green2>,...,<green15>
2722 Change the default green palette of the console.
2723 This is a 16-member array composed of values
2726 vt.default_red= [VT]
2727 Format: <red0>,<red1>,<red2>,...,<red15>
2728 Change the default red palette of the console.
2729 This is a 16-member array composed of values
2735 Set system-wide default UTF-8 mode for all tty's.
2736 Default is 1, i.e. UTF-8 mode is enabled for all
2737 newly opened terminals.
2739 waveartist= [HW,OSS]
2740 Format: <io>,<irq>,<dma>,<dma2>
2743 See header of drivers/scsi/wd33c93.c.
2746 See header of drivers/scsi/wd7000.c.
2749 See Documentation/watchdog/wdt.txt.
2751 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2752 default x2apic cluster mode on platforms
2755 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2756 xd_geo= See header of drivers/block/xd.c.
2758 xirc2ps_cs= [NET,PCMCIA]
2760 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2762 ______________________________________________________________________
2766 Add documentation for ALSA options.
2767 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob