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 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
48 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
49 EFI EFI Partitioning (GPT) is enabled
50 EIDE EIDE/ATAPI support is enabled.
51 FB The frame buffer device is enabled.
52 GCOV GCOV profiling is enabled.
53 HW Appropriate hardware is enabled.
54 IA-64 IA-64 architecture is enabled.
55 IMA Integrity measurement architecture is enabled.
56 IOSCHED More than one I/O scheduler is enabled.
57 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
58 IPV6 IPv6 support is enabled.
59 ISAPNP ISA PnP code is enabled.
60 ISDN Appropriate ISDN support is enabled.
61 JOY Appropriate joystick support is enabled.
62 KGDB Kernel debugger support is enabled.
63 KVM Kernel Virtual Machine support is enabled.
64 LIBATA Libata driver is enabled
65 LP Printer support is enabled.
66 LOOP Loopback device support is enabled.
67 M68k M68k architecture is enabled.
68 These options have more detailed description inside of
69 Documentation/m68k/kernel-options.txt.
70 MCA MCA bus support is enabled.
71 MDA MDA console support is enabled.
72 MOUSE Appropriate mouse support is enabled.
73 MSI Message Signaled Interrupts (PCI).
74 MTD MTD (Memory Technology Device) support is enabled.
75 NET Appropriate network support is enabled.
76 NUMA NUMA support is enabled.
77 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
79 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
81 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
83 PCIE PCI Express support is enabled.
84 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers have their options described inside
93 the Documentation/scsi/ sub-directory.
94 SECURITY Different security models are enabled.
95 SELINUX SELinux support is enabled.
96 APPARMOR AppArmor support is enabled.
97 SERIAL Serial support is enabled.
98 SH SuperH architecture is enabled.
99 SMP The kernel is an SMP kernel.
100 SPARC Sparc architecture is enabled.
101 SWSUSP Software suspend (hibernation) is enabled.
102 SUSPEND System suspend states are enabled.
103 FTRACE Function tracing enabled.
104 TPM TPM drivers are enabled.
105 TS Appropriate touchscreen support is enabled.
106 UMS USB Mass Storage support is enabled.
107 USB USB support is enabled.
108 USBHID USB Human Interface Device support is enabled.
109 V4L Video For Linux support is enabled.
110 VGA The VGA console has been enabled.
111 VT Virtual terminal support is enabled.
112 WDT Watchdog support is enabled.
113 XT IBM PC/XT MFM hard disk support is enabled.
114 X86-32 X86-32, aka i386 architecture is enabled.
115 X86-64 X86-64 architecture is enabled.
116 More X86-64 boot options can be found in
117 Documentation/x86/x86_64/boot-options.txt .
118 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
119 XEN Xen support is enabled
121 In addition, the following text indicates that the option:
123 BUGS= Relates to possible processor bugs on the said processor.
124 KNL Is a kernel start-up parameter.
125 BOOT Is a boot loader parameter.
127 Parameters denoted with BOOT are actually interpreted by the boot
128 loader, and have no meaning to the kernel directly.
129 Do not modify the syntax of boot loader parameters without extreme
130 need or coordination with <Documentation/x86/boot.txt>.
132 There are also arch-specific kernel-parameters not documented here.
133 See for example <Documentation/x86/x86_64/boot-options.txt>.
135 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
136 a trailing = on the name of any parameter states that that parameter will
137 be entered as an environment variable, whereas its absence indicates that
138 it will appear as a kernel argument readable via /proc/cmdline by programs
139 running once the system is up.
141 The number of kernel parameters is not limited, but the length of the
142 complete command line (parameters including spaces etc.) is limited to
143 a fixed number of characters. This limit depends on the architecture
144 and is between 256 and 4096 characters. It is defined in the file
145 ./include/asm/setup.h as COMMAND_LINE_SIZE.
149 Advanced Configuration and Power Interface
150 Format: { force | off | strict | noirq | rsdt }
151 force -- enable ACPI if default was off
152 off -- disable ACPI if default was on
153 noirq -- do not use ACPI for IRQ routing
154 strict -- Be less tolerant of platforms that are not
155 strictly ACPI specification compliant.
156 rsdt -- prefer RSDT over (default) XSDT
157 copy_dsdt -- copy DSDT to memory
159 See also Documentation/power/pm.txt, pci=noacpi
161 acpi_apic_instance= [ACPI, IOAPIC]
163 2: use 2nd APIC table, if available
164 1,0: use 1st APIC table
167 acpi_backlight= [HW,ACPI]
168 acpi_backlight=vendor
170 If set to vendor, prefer vendor specific driver
171 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
172 of the ACPI video.ko driver.
174 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
175 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
177 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
178 debug output. Bits in debug_layer correspond to a
179 _COMPONENT in an ACPI source file, e.g.,
180 #define _COMPONENT ACPI_PCI_COMPONENT
181 Bits in debug_level correspond to a level in
182 ACPI_DEBUG_PRINT statements, e.g.,
183 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
184 The debug_level mask defaults to "info". See
185 Documentation/acpi/debug.txt for more information about
186 debug layers and levels.
188 Enable processor driver info messages:
189 acpi.debug_layer=0x20000000
190 Enable PCI/PCI interrupt routing info messages:
191 acpi.debug_layer=0x400000
192 Enable AML "Debug" output, i.e., stores to the Debug
193 object while interpreting AML:
194 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
195 Enable all messages related to ACPI hardware:
196 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
198 Some values produce so much output that the system is
199 unusable. The "log_buf_len" parameter may be useful
200 if you need to capture more output.
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, sci_force_enable }
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 nonvs prevents the kernel from saving/restoring the
255 ACPI NVS memory during suspend/hibernation and resume.
256 sci_force_enable causes the kernel to set SCI_EN directly
257 on resume from S1/S3 (which is against the ACPI spec,
258 but some broken systems don't work without it).
260 acpi_use_timer_override [HW,ACPI]
261 Use timer override. For some broken Nvidia NF5 boards
262 that require a timer override, but don't have HPET
264 acpi_enforce_resources= [ACPI]
265 { strict | lax | no }
266 Check for resource conflicts between native drivers
267 and ACPI OperationRegions (SystemIO and SystemMemory
268 only). IO ports and memory declared in ACPI might be
269 used by the ACPI subsystem in arbitrary AML code and
270 can interfere with legacy drivers.
271 strict (default): access to resources claimed by ACPI
272 is denied; legacy drivers trying to access reserved
273 resources will fail to bind to device using them.
274 lax: access to resources claimed by ACPI is allowed;
275 legacy drivers trying to access reserved resources
276 will bind successfully but a warning message is logged.
277 no: ACPI OperationRegions are not marked as reserved,
278 no further checks are performed.
280 add_efi_memmap [EFI; X86] Include EFI memory map in
281 kernel's map of available physical RAM.
284 { off | try_unsupported }
285 off: disable AGP support
286 try_unsupported: try to drive unsupported chipsets
287 (may crash computer or cause data corruption)
290 See Documentation/sound/alsa/alsa-parameters.txt
293 Allow the default userspace alignment fault handler
294 behaviour to be specified. Bit 0 enables warnings,
295 bit 1 enables fixups, and bit 2 sends a segfault.
297 amd_iommu= [HW,X86-84]
298 Pass parameters to the AMD IOMMU driver in the system.
300 fullflush - enable flushing of IO/TLB entries when
301 they are unmapped. Otherwise they are
302 flushed before they will be reused, which
304 off - do not initialize any AMD IOMMU found in
307 amijoy.map= [HW,JOY] Amiga joystick support
308 Map of devices attached to JOY0DAT and JOY1DAT
310 See also Documentation/kernel/input/joystick.txt
312 analog.map= [HW,JOY] Analog joystick and gamepad support
313 Specifies type or capabilities of an analog joystick
314 connected to one of 16 gameports
315 Format: <type1>,<type2>,..<type16>
318 Power management functions (SPARCstation-4/5 + deriv.)
320 Disable APC CPU standby support. SPARCstation-Fox does
321 not play well with APC CPU idle - disable it if you have
322 APC and your system crashes randomly.
324 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
325 Change the output verbosity whilst booting
326 Format: { quiet (default) | verbose | debug }
327 Change the amount of debugging information output
328 when initialising the APIC and IO-APIC components.
331 See Documentation/networking/ipv6.txt.
333 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
334 Limit apic dumping. The parameter defines the maximal
335 number of local apics being dumped. Also it is possible
336 to set it to "all" by meaning -- no limit here.
337 Format: { 1 (default) | 2 | ... | all }.
338 The parameter valid if only apic=debug or
339 apic=verbose is specified.
340 Example: apic=debug show_lapic=all
342 apm= [APM] Advanced Power Management
343 See header of arch/x86/kernel/apm_32.c.
345 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
346 Format: <io>,<irq>,<nodeID>
350 atarimouse= [HW,MOUSE] Atari Mouse
352 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
353 EzKey and similar keyboards
355 atkbd.reset= [HW] Reset keyboard during initialization
357 atkbd.set= [HW] Select keyboard code set
358 Format: <int> (2 = AT (default), 3 = PS/2)
360 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
363 atkbd.softraw= [HW] Choose between synthetic and real raw mode
364 Format: <bool> (0 = real, 1 = synthetic (default))
366 atkbd.softrepeat= [HW]
367 Use software keyboard repeat
371 baycom_epp= [HW,AX25]
374 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
376 See header of drivers/net/hamradio/baycom_par.c.
378 baycom_ser_fdx= [HW,AX25]
379 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
380 Format: <io>,<irq>,<mode>[,<baud>]
381 See header of drivers/net/hamradio/baycom_ser_fdx.c.
383 baycom_ser_hdx= [HW,AX25]
384 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
385 Format: <io>,<irq>,<mode>
386 See header of drivers/net/hamradio/baycom_ser_hdx.c.
388 boot_delay= Milliseconds to delay each printk during boot.
389 Values larger than 10 seconds (10000) are changed to
393 bootmem_debug [KNL] Enable bootmem allocator debug messages.
395 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
396 bttv.radio= Most important insmod options are available as
398 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
399 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
401 bulk_remove=off [PPC] This parameter disables the use of the pSeries
402 firmware feature for flushing multiple hpte entries
405 c101= [NET] Moxa C101 synchronous serial card
407 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
408 Sometimes CPU hardware bugs make them report the cache
409 size incorrectly. The kernel will attempt work arounds
410 to fix known problems, but for some CPUs it is not
411 possible to determine what the correct size should be.
412 This option provides an override for these situations.
415 [SECURITY] Disable capabilities. This would normally
416 be used only if an alternative security model is to be
417 configured. Potentially dangerous and should only be
418 used if you are entirely sure of the consequences.
420 ccw_timeout_log [S390]
421 See Documentation/s390/CommonIO for details.
423 cgroup_disable= [KNL] Disable a particular controller
424 Format: {name of the controller(s) to disable}
425 {Currently supported controllers - "memory"}
427 checkreqprot [SELINUX] Set initial checkreqprot flag value.
428 Format: { "0" | "1" }
429 See security/selinux/Kconfig help text.
430 0 -- check protection applied by kernel (includes
431 any implied execute protection).
432 1 -- check protection requested by application.
433 Default value is set via a kernel config option.
434 Value can be changed at runtime via
435 /selinux/checkreqprot.
438 See Documentation/s390/CommonIO for details.
440 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
442 Forces specified clocksource (if available) to be used
443 when calculating gettimeofday(). If specified
444 clocksource is not available, it defaults to PIT.
445 Format: { pit | tsc | cyclone | pmtmr }
447 clocksource= Override the default clocksource
449 Override the default clocksource and use the clocksource
450 with the name specified.
451 Some clocksource names to choose from, depending on
453 [all] jiffies (this is the base, fallback clocksource)
455 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
456 pxa_timer,timer3,32k_counter,timer0_1
458 [X86-32] pit,hpet,tsc;
459 scx200_hrt on Geode; cyclone on IBM x440
467 clearcpuid=BITNUM [X86]
468 Disable CPUID feature X for the kernel. See
469 arch/x86/include/asm/cpufeature.h for the valid bit
470 numbers. Note the Linux specific bits are not necessarily
471 stable over kernel options, but the vendor specific
473 Also note that user programs calling CPUID directly
474 or using the feature without checking anything
475 will still see it. This just prevents it from
476 being used by the kernel or shown in /proc/cpuinfo.
477 Also note the kernel might malfunction if you disable
480 cmo_free_hint= [PPC] Format: { yes | no }
481 Specify whether pages are marked as being inactive
482 when they are freed. This is used in CMO environments
483 to determine OS memory pressure for page stealing by
487 code_bytes [X86] How many bytes of object code to print
492 com20020= [HW,NET] ARCnet - COM20020 chipset
494 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
496 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
500 ARCnet - COM90xx chipset (memory-mapped buffers)
501 Format: <io>[,<irq>[,<memstart>]]
503 condev= [HW,S390] console device
506 console= [KNL] Output console device and options.
508 tty<n> Use the virtual console device <n>.
512 Use the specified serial port. The options are of
513 the form "bbbbpnf", where "bbbb" is the baud rate,
514 "p" is parity ("n", "o", or "e"), "n" is number of
515 bits, and "f" is flow control ("r" for RTS or
516 omit it). Default is "9600n8".
518 See Documentation/serial-console.txt for more
520 Documentation/networking/netconsole.txt for an
523 uart[8250],io,<addr>[,options]
524 uart[8250],mmio,<addr>[,options]
525 Start an early, polled-mode console on the 8250/16550
526 UART at the specified I/O port or MMIO address,
527 switching to the matching ttyS device later. The
528 options are the same as for ttyS, above.
530 If the device connected to the port is not a TTY but a braille
531 device, prepend "brl," before the device type, for instance
533 For now, only VisioBraille is supported.
535 consoleblank= [KNL] The console blank (screen saver) timeout in
536 seconds. Defaults to 10*60 = 10mins. A value of 0
537 disables the blank timer.
540 [KNL] Change the default value for
541 /proc/<pid>/coredump_filter.
542 See also Documentation/filesystems/proc.txt.
544 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
546 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
548 crashkernel=size[KMG][@offset[KMG]]
549 [KNL] Using kexec, Linux can switch to a 'crash kernel'
550 upon panic. This parameter reserves the physical
551 memory region [offset, offset + size] for that kernel
552 image. If '@offset' is omitted, then a suitable offset
553 is selected automatically. Check
554 Documentation/kdump/kdump.txt for further details.
556 crashkernel=range1:size1[,range2:size2,...][@offset]
557 [KNL] Same as above, but depends on the memory
558 in the running system. The syntax of range is
559 start-[end] where start and end are both
560 a memory unit (amount[KMG]). See also
561 Documentation/kdump/kdump.txt for an example.
566 cs89x0_media= [HW,NET]
567 Format: { rj45 | aui | bnc }
570 See header of drivers/s390/block/dasd_devmap.c.
572 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
573 (one device per port)
574 Format: <port#>,<type>
575 See also Documentation/input/joystick-parport.txt
577 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
578 time. See Documentation/dynamic-debug-howto.txt for
581 debug [KNL] Enable kernel debugging (events log level).
584 [KNL] verbose self-tests
586 Print debugging info while doing the locking API
588 We default to 0 (no extra messages), setting it to
589 1 will print _a lot_ more information - normally
590 only useful to kernel developers.
592 debug_objects [KNL] Enable object debugging
595 [KNL] Disable object debugging
597 debugpat [X86] Enable PAT debugging
599 decnet.addr= [HW,NET]
600 Format: <area>[,<node>]
601 See also Documentation/networking/decnet.txt.
604 [same as hugepagesz=] The size of the default
605 HugeTLB page size. This is the size represented by
606 the legacy /proc/ hugepages APIs, used for SHM, and
607 default size when mounting hugetlbfs filesystems.
608 Defaults to the default architecture's huge page size
612 Set number of hash buckets for dentry cache.
615 IO parameters + enable/disable command.
617 digiepca= [HW,SERIAL]
618 See drivers/char/README.epca and
619 Documentation/serial/digiepca.txt.
622 See Documentation/networking/ipv6.txt.
625 See Documentation/networking/ipv6.txt.
627 disable_mtrr_cleanup [X86]
628 The kernel tries to adjust MTRR layout from continuous
629 to discrete, to make X server driver able to add WB
630 entry later. This parameter disables that.
632 disable_mtrr_trim [X86, Intel and AMD only]
633 By default the kernel will trim any uncacheable
634 memory out of your available memory pool based on
635 MTRR settings. This parameter disables that behavior,
636 possibly causing your machine to run very slowly.
638 disable_timer_pin_1 [X86]
639 Disable PIN 1 of APIC timer
640 Can be useful to work around chipset bugs.
642 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
643 this option disables the debugging code at boot.
645 dma_debug_entries=<number>
646 This option allows to tune the number of preallocated
647 entries for DMA-API debugging code. One entry is
648 required per DMA-API allocation. Use this if the
649 DMA-API debugging code disables itself because the
650 architectural default is too low.
652 dma_debug_driver=<driver_name>
653 With this option the DMA-API debugging driver
654 filter feature can be enabled at boot time. Just
655 pass the driver to filter for as the parameter.
656 The filter can be disabled or changed to another
657 driver later using sysfs.
661 earlycon= [KNL] Output early console device and options.
662 uart[8250],io,<addr>[,options]
663 uart[8250],mmio,<addr>[,options]
664 uart[8250],mmio32,<addr>[,options]
665 Start an early, polled-mode console on the 8250/16550
666 UART at the specified I/O port or MMIO address.
667 MMIO inter-register address stride is either 8bit (mmio)
669 The options are the same as for ttyS, above.
671 earlyprintk= [X86,SH,BLACKFIN]
673 earlyprintk=serial[,ttySn[,baudrate]]
674 earlyprintk=ttySn[,baudrate]
675 earlyprintk=dbgp[debugController#]
677 Append ",keep" to not disable it when the real console
680 Only vga or serial or usb debug port at a time.
682 Currently only ttyS0 and ttyS1 are supported.
684 Interaction with the standard serial driver is not
687 The VGA output is eventually overwritten by the real
690 ekgdboc= [X86,KGDB] Allow early kernel console debugging
693 This is desgined to be used in conjunction with
694 the boot argument: earlyprintk=vga
697 Format: {"off" | "on" | "skip[mbr]"}
699 eisa_irq_edge= [PARISC,HW]
700 See header of drivers/parisc/eisa.c.
703 See comment before function elanfreq_setup() in
704 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
707 Format: {"cfq" | "deadline" | "noop"}
708 See Documentation/block/as-iosched.txt and
709 Documentation/block/deadline-iosched.txt for details.
711 elfcorehdr= [IA64,PPC,SH,X86]
712 Specifies physical address of start of kernel core
713 image elf header. Generally kexec loader will
714 pass this option to capture kernel.
715 See Documentation/kdump/kdump.txt for details.
717 enable_mtrr_cleanup [X86]
718 The kernel tries to adjust MTRR layout from continuous
719 to discrete, to make X server driver able to add WB
720 entry later. This parameter enables that.
722 enable_timer_pin_1 [X86]
723 Enable PIN 1 of APIC timer
724 Can be useful to work around chipset bugs
725 (in particular on some ATI chipsets).
726 The kernel tries to set a reasonable default.
728 enforcing [SELINUX] Set initial enforcing status.
730 See security/selinux/Kconfig help text.
731 0 -- permissive (log only, no denials).
732 1 -- enforcing (deny and log).
734 Value can be changed at runtime via /selinux/enforce.
737 Disable Error Record Serialization Table (ERST)
740 ether= [HW,NET] Ethernet cards parameters
741 This option is obsoleted by the "netdev=" option, which
742 has equivalent usage. See its documentation for details.
746 fail_make_request=[KNL]
747 General fault injection mechanism.
748 Format: <interval>,<probability>,<space>,<times>
749 See also /Documentation/fault-injection/.
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
765 ftrace_dump_on_oops[=orig_cpu]
766 [FTRACE] will dump the trace buffers on oops.
767 If no parameter is passed, ftrace will dump
768 buffers of all CPUs, but if you pass orig_cpu, it will
769 dump only the buffer of the CPU that triggered the
772 ftrace_filter=[function-list]
773 [FTRACE] Limit the functions traced by the function
774 tracer at boot up. function-list is a comma separated
775 list of functions. This list can be changed at run
776 time by the set_ftrace_filter file in the debugfs
779 ftrace_notrace=[function-list]
780 [FTRACE] Do not trace the functions specified in
781 function-list. This list can be changed at run time
782 by the set_ftrace_notrace file in the debugfs
785 ftrace_graph_filter=[function-list]
786 [FTRACE] Limit the top level callers functions traced
787 by the function graph tracer at boot up.
788 function-list is a comma separated list of functions
789 that can be changed at run time by the
790 set_graph_function file in the debugfs tracing directory.
793 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
794 support via parallel port (up to 5 devices per port)
795 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
796 See also Documentation/input/joystick-parport.txt
800 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
804 gcov_persist= [GCOV] When non-zero (default), profiling data for
805 kernel modules is saved and remains accessible via
806 debugfs, even when the module is unloaded/reloaded.
807 When zero, profiling data is discarded and associated
808 debugfs files are removed at module unload time.
810 gpt [EFI] Forces disk with valid GPT signature but
811 invalid Protective MBR to be treated as GPT.
813 hashdist= [KNL,NUMA] Large hashes allocated during boot
814 are distributed across NUMA nodes. Defaults on
815 for 64bit NUMA, off otherwise.
816 Format: 0 | 1 (for off | on)
818 hcl= [IA-64] SGI's Hardware Graph compatibility layer
820 hd= [EIDE] (E)IDE hard drive subsystem geometry
821 Format: <cyl>,<head>,<sect>
824 Disable Hardware Error Source Table (HEST) support;
825 corresponding firmware-first mode error processing
826 logic will be disabled.
828 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
829 size of <nn>. This works even on boxes that have no
830 highmem otherwise. This also works to reduce highmem
831 size on bigger boxes.
833 highres= [KNL] Enable/disable high resolution timer mode.
834 Valid parameters: "on", "off"
838 See Documentation/isdn/README.HiSax.
842 hpet= [X86-32,HPET] option to control HPET usage
843 Format: { enable (default) | disable | force |
845 disable: disable HPET and use PIT instead
846 force: allow force enabled of undocumented chips (ICH4,
848 verbose: show contents of HPET registers during setup
850 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
851 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
852 On x86-64 and powerpc, this option can be specified
853 multiple times interleaved with hugepages= to reserve
854 huge pages of different sizes. Valid pages sizes on
855 x86-64 are 2M (when the CPU supports "pse") and 1G
856 (when the CPU supports the "pdpe1gb" cpuinfo flag)
857 Note that 1GB pages can only be allocated at boot time
858 using hugepages= and not freed afterwards.
860 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
861 terminal devices. Valid values: 0..8
862 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
863 If specified, z/VM IUCV HVC accepts connections
864 from listed z/VM user IDs only.
866 i2c_bus= [HW] Override the default board specific I2C bus speed
867 or register an additional I2C bus that is not
868 registered from board initialization code.
872 i8042.debug [HW] Toggle i8042 debug mode
873 i8042.direct [HW] Put keyboard port into non-translated mode
874 i8042.dumbkbd [HW] Pretend that controller can only read data from
875 keyboard and cannot control its state
876 (Don't attempt to blink the leds)
877 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
878 i8042.nokbd [HW] Don't check/create keyboard port
879 i8042.noloop [HW] Disable the AUX Loopback command while probing
881 i8042.nomux [HW] Don't check presence of an active multiplexing
883 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
885 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
886 i8042.reset [HW] Reset the controller during init and cleanup
887 i8042.unlock [HW] Unlock (ignore) the keylock
891 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
892 indicates that the driver is running on unsupported
894 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
895 does not match list of supported models.
897 [HW] Report power status in /proc/i8k
898 (disabled by default)
899 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
903 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
905 ide-core.nodma= [HW] (E)IDE subsystem
906 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
907 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
908 .cdrom .chs .ignore_cable are additional options
909 See Documentation/ide/ide.txt.
911 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
912 Claim all unknown PCI IDE storage controllers.
915 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
916 Poll forces a polling idle loop that can slightly
917 improve the performance of waking up a idle CPU, but
918 will use a lot of power and make the system run hot.
920 idle=mwait: On systems which support MONITOR/MWAIT but
921 the kernel chose to not use it because it doesn't save
922 as much power as a normal idle loop, use the
923 MONITOR/MWAIT idle loop anyways. Performance should be
924 the same as idle=poll.
925 idle=halt: Halt is forced to be used for CPU idle.
926 In such case C2/C3 won't be used again.
927 idle=nomwait: Disable mwait for CPU C-states
929 ignore_loglevel [KNL]
930 Ignore loglevel setting - this will print /all/
931 kernel messages to the console. Useful for debugging.
934 Set number of hash buckets for inode cache.
937 Format: { "0" | "1" }
938 0 -- integrity auditing messages. (Default)
939 1 -- enable informational integrity auditing messages.
942 Format: { "sha1" | "md5" }
946 Load a policy which meets the needs of the Trusted
947 Computing Base. This means IMA will measure all
948 programs exec'd, files mmap'd for exec, and all files
949 opened for read by uid=0.
953 Run specified binary instead of /sbin/init as init
956 initcall_debug [KNL] Trace initcalls as they are executed. Useful
957 for working out where the kernel is dying during
960 initrd= [BOOT] Specify the location of the initial ramdisk
962 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
965 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
967 Enable intel iommu driver.
969 Disable intel iommu driver.
970 igfx_off [Default Off]
971 By default, gfx is mapped as normal device. If a gfx
972 device has a dedicated DMAR unit, the DMAR unit is
973 bypassed by not enabling DMAR with this option. In
974 this case, gfx device will use physical address for
977 With this option iommu will not optimize to look
978 for io virtual address below 32 bit forcing dual
979 address cycle on pci bus for cards supporting greater
980 than 32 bit addressing. The default is to look
981 for translation below 32 bit and if not available
982 then look in the higher range.
984 With this option on every unmap_single operation will
985 result in a hardware IOTLB flush operation as opposed
986 to batching them for performance.
988 intremap= [X86-64, Intel-IOMMU]
989 Format: { on (default) | off | nosid }
990 on enable Interrupt Remapping (default)
991 off disable Interrupt Remapping
992 nosid disable Source ID checking
996 iomem= Disable strict checking of access to MMIO memory
997 strict regions from userspace.
1013 io7= [HW] IO7 for Marvel based alpha systems
1014 See comment before marvel_specify_io7 in
1015 arch/alpha/kernel/core_marvel.c.
1017 io_delay= [X86] I/O delay method
1019 Standard port 0x80 based delay
1021 Alternate port 0xed based delay (needed on some systems)
1023 Simple two microseconds delay
1028 See Documentation/filesystems/nfs/nfsroot.txt.
1030 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1031 See comment before ip2_setup() in
1032 drivers/char/ip2/ip2base.c.
1035 When an interrupt is not handled search all handlers
1036 for it. Intended to get systems with badly broken
1040 When an interrupt is not handled search all handlers
1041 for it. Also check all handlers each timer
1042 interrupt. Intended to get systems with badly broken
1046 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1048 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1050 <cpu number>,...,<cpu number>
1052 <cpu number>-<cpu number>
1053 (must be a positive range in ascending order)
1055 <cpu number>,...,<cpu number>-<cpu number>
1057 This option can be used to specify one or more CPUs
1058 to isolate from the general SMP balancing and scheduling
1059 algorithms. You can move a process onto or off an
1060 "isolated" CPU via the CPU affinity syscalls or cpuset.
1061 <cpu number> begins at 0 and the maximum value is
1062 "number of CPUs in system - 1".
1064 This option is the preferred way to isolate CPUs. The
1065 alternative -- manually setting the CPU mask of all
1066 tasks in the system -- can cause problems and
1067 suboptimal load balancer performance.
1071 js= [HW,JOY] Analog joystick
1072 See Documentation/input/joystick.txt.
1076 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1077 specifies the amount of memory usable by the kernel
1078 for non-movable allocations. The requested amount is
1079 spread evenly throughout all nodes in the system. The
1080 remaining memory in each node is used for Movable
1081 pages. In the event, a node is too small to have both
1082 kernelcore and Movable pages, kernelcore pages will
1083 take priority and other nodes will have a larger number
1084 of kernelcore pages. The Movable zone is used for the
1085 allocation of pages that may be reclaimed or moved
1086 by the page migration subsystem. This means that
1087 HugeTLB pages may not be allocated from this zone.
1088 Note that allocations like PTEs-from-HighMem still
1089 use the HighMem zone if it exists, and the Normal
1090 zone if it does not.
1092 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1093 Format: <Controller#>[,poll interval]
1094 The controller # is the number of the ehci usb debug
1095 port as it is probed via PCI. The poll interval is
1096 optional and is the number seconds in between
1097 each poll cycle to the debug port in case you need
1098 the functionality for interrupting the kernel with
1099 gdb or control-c on the dbgp connection. When
1100 not using this parameter you use sysrq-g to break into
1101 the kernel debugger.
1103 kgdboc= [KGDB,HW] kgdb over consoles.
1104 Requires a tty driver that supports console polling,
1105 or a supported polling keyboard driver (non-usb).
1106 Serial only format: <serial_device>[,baud]
1107 keyboard only format: kbd
1108 keyboard and serial format: kbd,<serial_device>[,baud]
1109 Optional Kernel mode setting:
1110 kms, kbd format: kms,kbd
1111 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1113 kgdbwait [KGDB] Stop kernel execution and enter the
1114 kernel debugger at the earliest opportunity.
1116 kmac= [MIPS] korina ethernet MAC address.
1117 Configure the RouterBoard 532 series on-chip
1118 Ethernet adapter MAC address.
1120 kmemleak= [KNL] Boot-time kmemleak enable/disable
1121 Valid arguments: on, off
1124 kstack=N [X86] Print N words from the kernel stack
1127 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1128 Default is 0 (don't ignore, but inject #GP)
1130 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1131 Default is 1 (enabled)
1133 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1137 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1138 Default is 1 (enabled)
1140 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1142 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1144 kvm-intel.bypass_guest_pf=
1145 [KVM,Intel] Disables bypassing of guest page faults
1146 on Intel chips. Default is 1 (enabled)
1148 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1149 (virtualized MMU) support on capable Intel chips.
1150 Default is 1 (enabled)
1152 kvm-intel.emulate_invalid_guest_state=
1153 [KVM,Intel] Enable emulation of invalid guest states
1154 Default is 0 (disabled)
1156 kvm-intel.flexpriority=
1157 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1158 Default is 1 (enabled)
1160 kvm-intel.unrestricted_guest=
1161 [KVM,Intel] Disable unrestricted guest feature
1162 (virtualized real and unpaged mode) on capable
1163 Intel chips. Default is 1 (enabled)
1165 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1166 feature (tagged TLBs) on capable Intel chips.
1167 Default is 1 (enabled)
1173 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1176 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1179 libata.dma= [LIBATA] DMA control
1180 libata.dma=0 Disable all PATA and SATA DMA
1181 libata.dma=1 PATA and SATA Disk DMA only
1182 libata.dma=2 ATAPI (CDROM) DMA only
1183 libata.dma=4 Compact Flash DMA only
1184 Combinations also work, so libata.dma=3 enables DMA
1185 for disks and CDROMs, but not CFs.
1187 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1188 libata.ignore_hpa=0 keep BIOS limits (default)
1189 libata.ignore_hpa=1 ignore limits, using full disk
1191 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1195 libata.force= [LIBATA] Force configurations. The format is comma
1196 separated list of "[ID:]VAL" where ID is
1197 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1198 matching port, link or device. Basically, it matches
1199 the ATA ID string printed on console by libata. If
1200 the whole ID part is omitted, the last PORT and DEVICE
1201 values are used. If ID hasn't been specified yet, the
1202 configuration applies to all ports, links and devices.
1204 If only DEVICE is omitted, the parameter applies to
1205 the port and all links and devices behind it. DEVICE
1206 number of 0 either selects the first device or the
1207 first fan-out link behind PMP device. It does not
1208 select the host link. DEVICE number of 15 selects the
1209 host link and device attached to it.
1211 The VAL specifies the configuration to force. As long
1212 as there's no ambiguity shortcut notation is allowed.
1213 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1214 The following configurations can be forced.
1216 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1217 Any ID with matching PORT is used.
1219 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1221 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1222 udma[/][16,25,33,44,66,100,133] notation is also
1225 * [no]ncq: Turn on or off NCQ.
1227 * nohrst, nosrst, norst: suppress hard, soft
1230 * dump_id: dump IDENTIFY data.
1232 If there are multiple matching configurations changing
1233 the same attribute, the last one is used.
1235 memblock=debug [KNL] Enable memblock debug messages.
1237 load_ramdisk= [RAM] List of ramdisks to load from floppy
1238 See Documentation/blockdev/ramdisk.txt.
1240 lockd.nlm_grace_period=P [NFS] Assign grace period.
1243 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1246 lockd.nlm_timeout=T [NFS] Assign timeout value.
1249 lockd.nlm_udpport=M [NFS] Assign UDP port.
1252 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1255 loglevel= All Kernel Messages with a loglevel smaller than the
1256 console loglevel will be printed to the console. It can
1257 also be changed with klogd or other programs. The
1258 loglevels are defined as follows:
1260 0 (KERN_EMERG) system is unusable
1261 1 (KERN_ALERT) action must be taken immediately
1262 2 (KERN_CRIT) critical conditions
1263 3 (KERN_ERR) error conditions
1264 4 (KERN_WARNING) warning conditions
1265 5 (KERN_NOTICE) normal but significant condition
1266 6 (KERN_INFO) informational
1267 7 (KERN_DEBUG) debug-level messages
1269 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1270 Format: { n | nk | nM }
1271 n must be a power of two. The default size
1272 is set in the kernel config file.
1274 logo.nologo [FB] Disables display of the built-in Linux logo.
1275 This may be used to provide more screen space for
1276 kernel log messages and is useful when debugging
1277 kernel boot problems.
1279 lp=0 [LP] Specify parallel ports to use, e.g,
1280 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1281 lp=reset first parallel port). 'lp=0' disables the
1282 lp=auto printer driver. 'lp=reset' (which can be
1283 specified in addition to the ports) causes
1284 attached printers to be reset. Using
1285 lp=port1,port2,... specifies the parallel ports
1286 to associate lp devices with, starting with
1287 lp0. A port specification may be 'none' to skip
1288 that lp device, or a parport name such as
1289 'parport0'. Specifying 'lp=auto' instead of a
1290 port specification list means that device IDs
1291 from each port should be examined, to see if
1292 an IEEE 1284-compliant printer is attached; if
1293 so, the driver will manage that printer.
1294 See also header of drivers/char/lp.c.
1297 Sets loops_per_jiffy to given constant, thus avoiding
1298 time-consuming boot-time autodetection (up to 250 ms per
1299 CPU). 0 enables autodetection (default). To determine
1300 the correct value for your kernel, boot with normal
1301 autodetection and see what value is printed. Note that
1302 on SMP systems the preset will be applied to all CPUs,
1303 which is likely to cause problems if your CPUs need
1304 significantly divergent settings. An incorrect value
1305 will cause delays in the kernel to be wrong, leading to
1306 unpredictable I/O errors and other breakage. Although
1307 unlikely, in the extreme case this might damage your
1311 Format: <io>,<irq>,<dma>
1313 machvec= [IA64] Force the use of a particular machine-vector
1314 (machvec) in a generic kernel.
1315 Example: machvec=hpzx1_swiotlb
1317 machtype= [Loongson] Share the same kernel image file between different
1319 Example: machtype=lemote-yeeloong-2f-7inch
1321 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1322 than or equal to this physical address is ignored.
1324 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1325 should make use of. maxcpus=n : n >= 0 limits the
1326 kernel to using 'n' processors. n=0 is a special case,
1327 it is equivalent to "nosmp", which also disables
1330 max_loop= [LOOP] Maximum number of loopback devices that can
1336 mce [X86-32] Machine Check Exception
1338 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1340 md= [HW] RAID subsystems devices and level
1341 See Documentation/md.txt.
1344 Format: <first>,<last>
1345 Specifies range of consoles to be captured by the MDA.
1347 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1348 Amount of memory to be used when the kernel is not able
1349 to see the whole system memory or for test.
1350 [X86-32] Use together with memmap= to avoid physical
1351 address space collisions. Without memmap= PCI devices
1352 could be placed at addresses belonging to unused RAM.
1354 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1358 [KNL,SH] Allow user to override the default size for
1359 per-device physically contiguous DMA buffers.
1361 memmap=exactmap [KNL,X86] Enable setting of an exact
1362 E820 memory map, as specified by the user.
1363 Such memmap=exactmap lines can be constructed based on
1364 BIOS output or other requirements. See the memmap=nn@ss
1367 memmap=nn[KMG]@ss[KMG]
1368 [KNL] Force usage of a specific region of memory
1369 Region of memory to be used, from ss to ss+nn.
1371 memmap=nn[KMG]#ss[KMG]
1372 [KNL,ACPI] Mark specific memory as ACPI data.
1373 Region of memory to be used, from ss to ss+nn.
1375 memmap=nn[KMG]$ss[KMG]
1376 [KNL,ACPI] Mark specific memory as reserved.
1377 Region of memory to be used, from ss to ss+nn.
1378 Example: Exclude memory from 0x18690000-0x1869ffff
1379 memmap=64K$0x18690000
1381 memmap=0x10000$0x18690000
1383 memory_corruption_check=0/1 [X86]
1384 Some BIOSes seem to corrupt the first 64k of
1385 memory when doing things like suspend/resume.
1386 Setting this option will scan the memory
1387 looking for corruption. Enabling this will
1388 both detect corruption and prevent the kernel
1389 from using the memory being corrupted.
1390 However, its intended as a diagnostic tool; if
1391 repeatable BIOS-originated corruption always
1392 affects the same memory, you can use memmap=
1393 to prevent the kernel from using that memory.
1395 memory_corruption_check_size=size [X86]
1396 By default it checks for corruption in the low
1397 64k, making this memory unavailable for normal
1398 use. Use this parameter to scan for
1399 corruption in more or less memory.
1401 memory_corruption_check_period=seconds [X86]
1402 By default it checks for corruption every 60
1403 seconds. Use this parameter to check at some
1404 other rate. 0 disables periodic checking.
1406 memtest= [KNL,X86] Enable memtest
1408 default : 0 <disable>
1409 Specifies the number of memtest passes to be
1410 performed. Each pass selects another test
1411 pattern from a given set of patterns. Memtest
1412 fills the memory with this pattern, validates
1413 memory contents and reserves bad memory
1414 regions that are detected.
1416 meye.*= [HW] Set MotionEye Camera parameters
1417 See Documentation/video4linux/meye.txt.
1419 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1420 Multi-Function General Purpose Timers on AMD Geode
1423 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1424 the BIOS has incorrectly applied a workaround. TinyBIOS
1425 version 0.98 is known to be affected, 0.99 fixes the
1426 problem by letting the user disable the workaround.
1430 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1431 physical address is ignored.
1433 mini2440= [ARM,HW,KNL]
1434 Format:[0..2][b][c][t]
1436 MINI2440 configuration specification:
1437 0 - The attached screen is the 3.5" TFT
1438 1 - The attached screen is the 7" TFT
1439 2 - The VGA Shield is attached (1024x768)
1440 Leaving out the screen size parameter will not load
1441 the TFT driver, and the framebuffer will be left
1443 b - Enable backlight. The TFT backlight pin will be
1444 linked to the kernel VESA blanking code and a GPIO
1445 LED. This parameter is not necessary when using the
1447 c - Enable the s3c camera interface.
1448 t - Reserved for enabling touchscreen support. The
1449 touchscreen support is not enabled in the mainstream
1450 kernel as of 2.6.30, a preliminary port can be found
1451 in the "bleeding edge" mini2440 support kernel at
1452 http://repo.or.cz/w/linux-2.6/mini2440.git
1455 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1456 parameter allows control of the logging verbosity for
1457 the additional memory initialisation checks. A value
1458 of 0 disables mminit logging and a level of 4 will
1459 log everything. Information is printed at KERN_DEBUG
1460 so loglevel=8 may also need to be specified.
1463 [MOUSE] Maximum time between finger touching and
1464 leaving touchpad surface for touch to be considered
1465 a tap and be reported as a left button click (for
1466 touchpads working in absolute mode only).
1468 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1469 reporting absolute coordinates, such as tablets
1470 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1471 reporting absolute coordinates, such as tablets
1473 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1474 is similar to kernelcore except it specifies the
1475 amount of memory used for migratable allocations.
1476 If both kernelcore and movablecore is specified,
1477 then kernelcore will be at *least* the specified
1478 value but may be more. If movablecore on its own
1479 is specified, the administrator must be careful
1480 that the amount of memory usable for all allocations
1483 MTD_Partition= [MTD]
1484 Format: <name>,<region-number>,<size>,<offset>
1486 MTD_Region= [MTD] Format:
1487 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1490 See drivers/mtd/cmdlinepart.c.
1492 multitce=off [PPC] This parameter disables the use of the pSeries
1493 firmware feature for updating multiple TCE entries
1496 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1498 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1500 boundary - index of last SLC block on Flex-OneNAND.
1501 The remaining blocks are configured as MLC blocks.
1502 lock - Configure if Flex-OneNAND boundary should be locked.
1503 Once locked, the boundary cannot be changed.
1504 1 indicates lock status, 0 indicates unlock status.
1507 ARM/S3C2412 JIVE boot control
1509 See arch/arm/mach-s3c2412/mach-jive.c
1511 mtouchusb.raw_coordinates=
1512 [HW] Make the MicroTouch USB driver use raw coordinates
1513 ('y', default) or cooked coordinates ('n')
1515 mtrr_chunk_size=nn[KMG] [X86]
1516 used for mtrr cleanup. It is largest continuous chunk
1517 that could hold holes aka. UC entries.
1519 mtrr_gran_size=nn[KMG] [X86]
1520 Used for mtrr cleanup. It is granularity of mtrr block.
1522 Large value could prevent small alignment from
1525 mtrr_spare_reg_nr=n [X86]
1527 Range: 0,7 : spare reg number
1529 Used for mtrr cleanup. It is spare mtrr entries number.
1530 Set to 2 or more if your graphical card needs more.
1532 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1534 netdev= [NET] Network devices parameters
1535 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1536 Note that mem_start is often overloaded to mean
1537 something different and driver-specific.
1538 This usage is only documented in each driver source
1542 [NETFILTER] Enable connection tracking flow accounting
1543 0 to disable accounting
1544 1 to enable accounting
1547 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1548 See Documentation/filesystems/nfs/nfsroot.txt.
1550 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1551 See Documentation/filesystems/nfs/nfsroot.txt.
1553 nfsrootdebug [NFS] enable nfsroot debugging messages.
1554 See Documentation/filesystems/nfs/nfsroot.txt.
1556 nfs.callback_tcpport=
1557 [NFS] set the TCP port on which the NFSv4 callback
1558 channel should listen.
1561 [NFS] sets the pathname to the program which is used
1562 to update the NFS client cache entries.
1564 nfs.cache_getent_timeout=
1565 [NFS] sets the timeout after which an attempt to
1566 update a cache entry is deemed to have failed.
1568 nfs.idmap_cache_timeout=
1569 [NFS] set the maximum lifetime for idmapper cache
1573 [NFS] enable 64-bit inode numbers.
1574 If zero, the NFS client will fake up a 32-bit inode
1575 number for the readdir() and stat() syscalls instead
1576 of returning the full 64-bit number.
1577 The default is to return 64-bit inode numbers.
1579 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1580 when a NMI is triggered.
1581 Format: [state][,regs][,debounce][,die]
1583 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1584 Format: [panic,][num]
1586 0 - turn nmi_watchdog off
1587 When panic is specified, panic when an NMI watchdog
1589 This is useful when you use a panic=... timeout and
1590 need the box quickly up again.
1592 netpoll.carrier_timeout=
1593 [NET] Specifies amount of time (in seconds) that
1594 netpoll should wait for a carrier. By default netpoll
1597 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1598 emulation library even if a 387 maths coprocessor
1602 [HW] Never suspend the console
1603 Disable suspending of consoles during suspend and
1604 hibernate operations. Once disabled, debugging
1605 messages can reach various consoles while the rest
1606 of the system is being put to sleep (ie, while
1607 debugging driver suspend/resume hooks). This may
1608 not work reliably with all consoles, but is known
1609 to work with serial and VGA consoles.
1611 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1612 caches in the slab allocator. Saves per-node memory,
1613 but will impact performance.
1617 noapic [SMP,APIC] Tells the kernel to not make use of any
1618 IOAPICs that may be present in the system.
1620 noautogroup Disable scheduler automatic task group creation.
1622 nobats [PPC] Do not use BATs for mapping kernel lowmem
1623 on "Classic" PPC cores.
1627 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1629 nodelayacct [KNL] Disable per-task delay accounting
1631 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1633 nodsp [SH] Disable hardware DSP at boot time.
1635 noefi [X86] Disable EFI runtime services support.
1640 On X86-32 available only on PAE configured kernels.
1641 noexec=on: enable non-executable mappings (default)
1642 noexec=off: disable non-executable mappings
1645 This affects only 32-bit executables.
1646 noexec32=on: enable non-executable mappings (default)
1647 read doesn't imply executable mappings
1648 noexec32=off: disable non-executable mappings
1649 read implies executable mappings
1651 nofpu [SH] Disable hardware FPU at boot time.
1653 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1654 register save and restore. The kernel will only save
1655 legacy floating-point registers on task switch.
1657 noxsave [BUGS=X86] Disables x86 extended register state save
1658 and restore using xsave. The kernel will fallback to
1659 enabling legacy floating-point and sse state.
1661 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1662 wfi(ARM) instruction doesn't work correctly and not to
1663 use it. This is also useful when using JTAG debugger.
1665 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1666 instruction doesn't work correctly and not to
1669 no_file_caps Tells the kernel not to honor file capabilities. The
1670 only way then for a file to be executed with privilege
1671 is to be setuid root or executed by root.
1673 nohalt [IA-64] Tells the kernel not to use the power saving
1674 function PAL_HALT_LIGHT when idle. This increases
1675 power-consumption. On the positive side, it reduces
1676 interrupt wake-up latency, which may improve performance
1677 in certain environments such as networked servers or
1680 nohz= [KNL] Boottime enable/disable dynamic ticks
1681 Valid arguments: on, off
1684 noiotrap [SH] Disables trapped I/O port accesses.
1686 noirqdebug [X86-32] Disables the code which attempts to detect and
1687 disable unhandled interrupt sources.
1689 no_timer_check [X86,APIC] Disables the code which tests for
1690 broken timer IRQ sources.
1692 noisapnp [ISAPNP] Disables ISA PnP code.
1694 noinitrd [RAM] Tells the kernel not to load any configured
1697 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1699 [Deprecated - use intremap=off]
1703 nojitter [IA64] Disables jitter checking for ITC timers.
1705 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1707 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1710 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1712 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1714 noltlbs [PPC] Do not use large page/tlb entries for kernel
1715 lowmem mapping on PPC40x.
1717 nomca [IA-64] Disable machine check abort handling
1719 nomce [X86-32] Machine Check Exception
1721 nomfgpt [X86-32] Disable Multi-Function General Purpose
1722 Timer usage (for AMD Geode machines).
1724 nopat [X86] Disable PAT (page attribute table extension of
1725 pagetables) support.
1727 norandmaps Don't use address space randomization. Equivalent to
1728 echo 0 > /proc/sys/kernel/randomize_va_space
1730 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1732 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1733 with UP alternatives
1735 noresidual [PPC] Don't use residual data on PReP machines.
1737 noresume [SWSUSP] Disables resume and restores original swap
1740 no-scroll [VGA] Disables scrollback.
1741 This is required for the Braillex ib80-piezo Braille
1742 reader made by F.H. Papenmeier (Germany).
1746 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1748 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1749 and disable the IO APIC. legacy for "maxcpus=0".
1751 nosoftlockup [KNL] Disable the soft-lockup detector.
1753 noswapaccount [KNL] Disable accounting of swap in memory resource
1754 controller. (See Documentation/cgroups/memory.txt)
1756 nosync [HW,M68K] Disables sync negotiation for all devices.
1758 notsc [BUGS=X86-32] Disable Time Stamp Counter
1760 nousb [USB] Disable the USB subsystem
1762 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1766 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1768 nptcg= [IA64] Override max number of concurrent global TLB
1769 purges which is reported from either PAL_VM_SUMMARY or
1772 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1773 could support. nr_cpus=n : n >= 1 limits the kernel to
1774 supporting 'n' processors. Later in runtime you can not
1775 use hotplug cpu feature to put more cpu back to online.
1776 just like you compile the kernel NR_CPUS=n
1778 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1780 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1781 one of ['zone', 'node', 'default'] can be specified
1782 This can be set from sysctl after boot.
1783 See Documentation/sysctl/vm.txt for details.
1785 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1786 See Documentation/debugging-via-ohci1394.txt for more
1789 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1790 Rather than timing out after 20 ms if an EC
1791 command is not properly ACKed, override the length
1792 of the timeout. We have interrupts disabled while
1793 waiting for the ACK, so if this is set too high
1794 interrupts *may* be lost!
1796 omap_mux= [OMAP] Override bootloader pin multiplexing.
1797 Format: <mux_mode0.mode_name=value>...
1798 For example, to override I2C bus2:
1799 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1801 oprofile.timer= [HW]
1802 Use timer interrupt instead of performance counters
1804 oprofile.cpu_type= Force an oprofile cpu type
1805 This might be useful if you have an older oprofile
1806 userland or if you want common events.
1807 Format: { arch_perfmon }
1808 arch_perfmon: [X86] Force use of architectural
1809 perfmon on Intel CPUs instead of the
1810 CPU specific event set.
1813 See Documentation/sound/oss/oss-parameters.txt
1815 panic= [KNL] Kernel behaviour on panic
1818 parkbd.port= [HW] Parallel port number the keyboard adapter is
1819 connected to, default is 0.
1821 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1822 0 for XT, 1 for AT (default is AT).
1825 parport= [HW,PPT] Specify parallel ports. 0 disables.
1826 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1827 Use 'auto' to force the driver to use any
1828 IRQ/DMA settings detected (the default is to
1829 ignore detected IRQ/DMA settings because of
1830 possible conflicts). You can specify the base
1831 address, IRQ, and DMA settings; IRQ and DMA
1832 should be numbers, or 'auto' (for using detected
1833 settings on that particular port), or 'nofifo'
1834 (to avoid using a FIFO even if it is detected).
1835 Parallel ports are assigned in the order they
1836 are specified on the command line, starting
1839 parport_init_mode= [HW,PPT]
1840 Configure VIA parallel port to operate in
1841 a specific mode. This is necessary on Pegasos
1842 computer where firmware has no options for setting
1843 up parallel port mode and sets it to spp.
1844 Currently this function knows 686a and 8231 chips.
1845 Format: [spp|ps2|epp|ecp|ecpepp]
1848 Halt all CPUs after the first oops has been printed for
1849 the specified number of seconds. This is to be used if
1850 your oopses keep scrolling off the screen.
1855 See header of drivers/block/paride/pcd.c.
1856 See also Documentation/blockdev/paride.txt.
1858 pci=option[,option...] [PCI] various PCI subsystem options:
1859 earlydump [X86] dump PCI config space before the kernel
1861 off [X86] don't probe for the PCI bus
1862 bios [X86-32] force use of PCI BIOS, don't access
1863 the hardware directly. Use this if your machine
1864 has a non-standard PCI host bridge.
1865 nobios [X86-32] disallow use of PCI BIOS, only direct
1866 hardware access methods are allowed. Use this
1867 if you experience crashes upon bootup and you
1868 suspect they are caused by the BIOS.
1869 conf1 [X86] Force use of PCI Configuration
1871 conf2 [X86] Force use of PCI Configuration
1873 noaer [PCIE] If the PCIEAER kernel config parameter is
1874 enabled, this kernel boot option can be used to
1875 disable the use of PCIE advanced error reporting.
1876 nodomains [PCI] Disable support for multiple PCI
1877 root domains (aka PCI segments, in ACPI-speak).
1878 nommconf [X86] Disable use of MMCONFIG for PCI
1880 check_enable_amd_mmconf [X86] check for and enable
1881 properly configured MMIO access to PCI
1882 config space on AMD family 10h CPU
1883 nomsi [MSI] If the PCI_MSI kernel config parameter is
1884 enabled, this kernel boot option can be used to
1885 disable the use of MSI interrupts system-wide.
1886 noioapicquirk [APIC] Disable all boot interrupt quirks.
1887 Safety option to keep boot IRQs enabled. This
1888 should never be necessary.
1889 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1890 primary IO-APIC for bridges that cannot disable
1891 boot IRQs. This fixes a source of spurious IRQs
1892 when the system masks IRQs.
1893 noioapicreroute [APIC] Disable workaround that uses the
1894 boot IRQ equivalent of an IRQ that connects to
1895 a chipset where boot IRQs cannot be disabled.
1896 The opposite of ioapicreroute.
1897 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1898 routing table. These calls are known to be buggy
1899 on several machines and they hang the machine
1900 when used, but on other computers it's the only
1901 way to get the interrupt routing table. Try
1902 this option if the kernel is unable to allocate
1903 IRQs or discover secondary PCI buses on your
1905 rom [X86] Assign address space to expansion ROMs.
1906 Use with caution as certain devices share
1907 address decoders between ROMs and other
1909 norom [X86] Do not assign address space to
1910 expansion ROMs that do not already have
1911 BIOS assigned address ranges.
1912 nobar [X86] Do not assign address space to the
1913 BARs that weren't assigned by the BIOS.
1914 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1915 assigned automatically to PCI devices. You can
1916 make the kernel exclude IRQs of your ISA cards
1918 pirqaddr=0xAAAAA [X86] Specify the physical address
1919 of the PIRQ table (normally generated
1920 by the BIOS) if it is outside the
1921 F0000h-100000h range.
1922 lastbus=N [X86] Scan all buses thru bus #N. Can be
1923 useful if the kernel is unable to find your
1924 secondary buses and you want to tell it
1925 explicitly which ones they are.
1926 assign-busses [X86] Always assign all PCI bus
1927 numbers ourselves, overriding
1928 whatever the firmware may have done.
1929 usepirqmask [X86] Honor the possible IRQ mask stored
1930 in the BIOS $PIR table. This is needed on
1931 some systems with broken BIOSes, notably
1932 some HP Pavilion N5400 and Omnibook XE3
1933 notebooks. This will have no effect if ACPI
1934 IRQ routing is enabled.
1935 noacpi [X86] Do not use ACPI for IRQ routing
1936 or for PCI scanning.
1937 use_crs [X86] Use PCI host bridge window information
1938 from ACPI. On BIOSes from 2008 or later, this
1939 is enabled by default. If you need to use this,
1940 please report a bug.
1941 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1942 If you need to use this, please report a bug.
1943 routeirq Do IRQ routing for all PCI devices.
1944 This is normally done in pci_enable_device(),
1945 so this option is a temporary workaround
1946 for broken drivers that don't call it.
1947 skip_isa_align [X86] do not align io start addr, so can
1948 handle more pci cards
1949 firmware [ARM] Do not re-enumerate the bus but instead
1950 just use the configuration from the
1951 bootloader. This is currently used on
1952 IXP2000 systems where the bus has to be
1953 configured a certain way for adjunct CPUs.
1954 noearly [X86] Don't do any early type 1 scanning.
1955 This might help on some broken boards which
1956 machine check when some devices' config space
1957 is read. But various workarounds are disabled
1958 and some IOMMU drivers will not work.
1959 bfsort Sort PCI devices into breadth-first order.
1960 This sorting is done to get a device
1961 order compatible with older (<= 2.4) kernels.
1962 nobfsort Don't sort PCI devices into breadth-first order.
1963 cbiosize=nn[KMG] The fixed amount of bus space which is
1964 reserved for the CardBus bridge's IO window.
1965 The default value is 256 bytes.
1966 cbmemsize=nn[KMG] The fixed amount of bus space which is
1967 reserved for the CardBus bridge's memory
1968 window. The default value is 64 megabytes.
1971 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1972 Specifies alignment and device to reassign
1973 aligned memory resources.
1974 If <order of align> is not specified,
1975 PAGE_SIZE is used as alignment.
1976 PCI-PCI bridge can be specified, if resource
1977 windows need to be expanded.
1978 ecrc= Enable/disable PCIe ECRC (transaction layer
1979 end-to-end CRC checking).
1980 bios: Use BIOS/firmware settings. This is the
1985 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1988 force Enable ASPM even on devices that claim not to support it.
1989 WARNING: Forcing ASPM on may cause system lockups.
1991 pcie_ports= [PCIE] PCIe ports handling:
1992 auto Ask the BIOS whether or not to use native PCIe services
1993 associated with PCIe ports (PME, hot-plug, AER). Use
1994 them only if that is allowed by the BIOS.
1995 native Use native PCIe services associated with PCIe ports
1997 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2000 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2001 nomsi Do not use MSI for native PCIe PME signaling (this makes
2002 all PCIe root ports use INTx for all services).
2004 pcmv= [HW,PCMCIA] BadgePAD 4
2007 See Documentation/blockdev/paride.txt.
2009 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2012 See arch/parisc/kernel/pdc_chassis.c
2014 percpu_alloc= Select which percpu first chunk allocator to use.
2015 Currently supported values are "embed" and "page".
2016 Archs may support subset or none of the selections.
2017 See comments in mm/percpu.c for details on each
2018 allocator. This parameter is primarily for debugging
2019 and performance comparison.
2022 See Documentation/blockdev/paride.txt.
2025 See Documentation/blockdev/paride.txt.
2027 pirq= [SMP,APIC] Manual mp-table setup
2028 See Documentation/x86/i386/IO-APIC.txt.
2030 plip= [PPT,NET] Parallel port network link
2031 Format: { parport<nr> | timid | 0 }
2032 See also Documentation/parport.txt.
2034 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2035 Override pmtimer IOPort with a hex value.
2039 Enable PNP debug messages. This depends on the
2040 CONFIG_PNP_DEBUG_MESSAGES option.
2046 { on | off | curr | res | no-curr | no-res }
2049 [ISAPNP] Exclude IRQs for the autoconfiguration
2052 [ISAPNP] Exclude DMAs for the autoconfiguration
2054 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2055 Ranges are in pairs (I/O port base and size).
2058 [ISAPNP] Exclude memory regions for the
2060 Ranges are in pairs (memory base and size).
2062 ports= [IP_VS_FTP] IPVS ftp helper module
2064 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2066 Format: <port>,<port>....
2068 print-fatal-signals=
2069 [KNL] debug: print fatal signals
2071 If enabled, warn about various signal handling
2072 related application anomalies: too many signals,
2073 too many POSIX.1 timers, fatal signals causing a
2076 If you hit the warning due to signal overflow,
2077 you might want to try "ulimit -i unlimited".
2081 printk.time= Show timing data prefixed to each printk message line
2082 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2084 processor.max_cstate= [HW,ACPI]
2085 Limit processor to maximum C-state
2086 max_cstate=9 overrides any DMI blacklist limit.
2088 processor.nocst [HW,ACPI]
2089 Ignore the _CST method to determine C-states,
2090 instead using the legacy FADT method
2092 profile= [KNL] Enable kernel profiling via /proc/profile
2093 Format: [schedule,]<number>
2094 Param: "schedule" - profile schedule points.
2095 Param: <number> - step/bucket size as a power of 2 for
2096 statistical time based profiling.
2097 Param: "sleep" - profile D-state sleeping (millisecs).
2098 Requires CONFIG_SCHEDSTATS
2099 Param: "kvm" - profile VM exits.
2101 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2103 See Documentation/blockdev/ramdisk.txt.
2105 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2106 probe for; one of (bare|imps|exps|lifebook|any).
2107 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2109 psmouse.resetafter= [HW,MOUSE]
2110 Try to reset the device after so many bad packets
2113 [HW,MOUSE] Set desired mouse resolution, in dpi.
2114 psmouse.smartscroll=
2115 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2116 0 = disabled, 1 = enabled (default).
2119 See Documentation/blockdev/paride.txt.
2122 [KNL] Number of legacy pty's. Overwrites compiled-in
2125 quiet [KNL] Disable most log messages
2130 See Documentation/md.txt.
2132 ramdisk_blocksize= [RAM]
2133 See Documentation/blockdev/ramdisk.txt.
2135 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2136 See Documentation/blockdev/ramdisk.txt.
2138 rcupdate.blimit= [KNL,BOOT]
2139 Set maximum number of finished RCU callbacks to process
2142 rcupdate.qhimark= [KNL,BOOT]
2143 Set threshold of queued
2144 RCU callbacks over which batch limiting is disabled.
2146 rcupdate.qlowmark= [KNL,BOOT]
2147 Set threshold of queued RCU callbacks below which
2148 batch limiting is re-enabled.
2152 Run specified binary instead of /init from the ramdisk,
2153 used for early userspace startup. See initrd.
2155 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2156 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2157 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2160 [KNL, SMP] Set scheduler's default relax_domain_level.
2161 See Documentation/cgroups/cpusets.txt.
2163 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2165 reservetop= [X86-32]
2167 Reserves a hole at the top of the kernel virtual
2172 Set the amount of memory to reserve for BIOS at
2173 the bottom of the address space.
2175 reset_devices [KNL] Force drivers to reset the underlying device
2176 during initialization.
2179 Specify the partition device for software suspend
2181 resume_offset= [SWSUSP]
2182 Specify the offset from the beginning of the partition
2183 given by "resume=" at which the swap header is located,
2184 in <PAGE_SIZE> units (needed only for swap files).
2185 See Documentation/power/swsusp-and-swap-files.txt
2187 hibernate= [HIBERNATION]
2188 noresume Don't check if there's a hibernation image
2189 present during boot.
2190 nocompress Don't compress/decompress hibernation images.
2192 retain_initrd [RAM] Keep initrd memory after extraction
2194 rhash_entries= [KNL,NET]
2195 Set number of hash buckets for route cache
2197 riscom8= [HW,SERIAL]
2198 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2200 ro [KNL] Mount root device read-only on boot
2202 root= [KNL] Root filesystem
2204 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2205 mount the root filesystem
2207 rootflags= [KNL] Set root filesystem mount option string
2209 rootfstype= [KNL] Set root filesystem type
2211 rootwait [KNL] Wait (indefinitely) for root device to show up.
2212 Useful for devices that are detected asynchronously
2213 (e.g. USB and MMC devices).
2215 rw [KNL] Mount root device read-write on boot
2217 S [KNL] Run init in single mode
2220 See drivers/net/irda/sa1100_ir.c.
2222 sbni= [NET] Granch SBNI12 leased line adapter
2224 sched_debug [KNL] Enables verbose scheduler debug messages.
2226 security= [SECURITY] Choose a security module to enable at boot.
2227 If this boot parameter is not specified, only the first
2228 security module asking for security registration will be
2229 loaded. An invalid security module name will be treated
2230 as if no module has been chosen.
2232 selinux= [SELINUX] Disable or enable SELinux at boot time.
2233 Format: { "0" | "1" }
2234 See security/selinux/Kconfig help text.
2237 Default value is set via kernel config option.
2238 If enabled at boot time, /selinux/disable can be used
2239 later to disable prior to initial policy load.
2241 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2242 Format: { "0" | "1" }
2243 See security/apparmor/Kconfig help text
2246 Default value is set via kernel config option.
2248 serialnumber [BUGS=X86-32]
2251 Maximal number of shapers.
2253 show_msr= [x86] show boot-time MSR settings
2254 Format: { <integer> }
2255 Show boot-time (BIOS-initialized) MSR settings.
2256 The parameter means the number of CPUs to show,
2257 for example 1 means boot CPU only.
2264 slub_debug[=options[,slabs]] [MM, SLUB]
2265 Enabling slub_debug allows one to determine the
2266 culprit if slab objects become corrupted. Enabling
2267 slub_debug can create guard zones around objects and
2268 may poison objects when not in use. Also tracks the
2269 last alloc / free. For more information see
2270 Documentation/vm/slub.txt.
2272 slub_max_order= [MM, SLUB]
2273 Determines the maximum allowed order for slabs.
2274 A high setting may cause OOMs due to memory
2275 fragmentation. For more information see
2276 Documentation/vm/slub.txt.
2278 slub_min_objects= [MM, SLUB]
2279 The minimum number of objects per slab. SLUB will
2280 increase the slab order up to slub_max_order to
2281 generate a sufficiently large slab able to contain
2282 the number of objects indicated. The higher the number
2283 of objects the smaller the overhead of tracking slabs
2284 and the less frequently locks need to be acquired.
2285 For more information see Documentation/vm/slub.txt.
2287 slub_min_order= [MM, SLUB]
2288 Determines the mininum page order for slabs. Must be
2289 lower than slub_max_order.
2290 For more information see Documentation/vm/slub.txt.
2292 slub_nomerge [MM, SLUB]
2293 Disable merging of slabs with similar size. May be
2294 necessary if there is some reason to distinguish
2295 allocs to different slabs. Debug options disable
2296 merging on their own.
2297 For more information see Documentation/vm/slub.txt.
2300 Format: <io1>[,<io2>[,...,<io8>]]
2302 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2303 attempt to substitute SMP alternatives once at boot.
2305 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2306 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2307 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2308 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2309 smsc-ircc2.ircc_irq= [HW] IRQ line
2310 smsc-ircc2.ircc_dma= [HW] DMA channel
2311 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2312 0: Toshiba Satellite 1800 (GP data pin select)
2313 1: Fast pin select (default)
2317 [KNL] Should the soft-lockup detector generate panics.
2319 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2320 See Documentation/sonypi.txt
2322 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2323 See Documentation/serial/specialix.txt.
2325 spia_io_base= [HW,MTD]
2331 Enabled the stack tracer on boot up.
2335 Set the STI (builtin display/keyboard on the HP-PARISC
2336 machines) console (graphic card) which should be used
2337 as the initial boot-console.
2338 See also comment in drivers/video/console/sticore.c.
2341 See comment in drivers/video/console/sticore.c.
2344 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2346 sunrpc.min_resvport=
2347 sunrpc.max_resvport=
2349 SunRPC servers often require that client requests
2350 originate from a privileged port (i.e. a port in the
2351 range 0 < portnr < 1024).
2352 An administrator who wishes to reserve some of these
2353 ports for other uses may adjust the range that the
2354 kernel's sunrpc client considers to be privileged
2355 using these two parameters to set the minimum and
2356 maximum port values.
2360 Control how the NFS server code allocates CPUs to
2361 service thread pools. Depending on how many NICs
2362 you have and where their interrupts are bound, this
2363 option will affect which CPUs will do NFS serving.
2364 Note: this parameter cannot be changed while the
2365 NFS server is running.
2367 auto the server chooses an appropriate mode
2368 automatically using heuristics
2369 global a single global pool contains all CPUs
2370 percpu one pool for each CPU
2371 pernode one pool for each NUMA node (equivalent
2372 to global on non-NUMA machines)
2374 sunrpc.tcp_slot_table_entries=
2375 sunrpc.udp_slot_table_entries=
2377 Sets the upper limit on the number of simultaneous
2378 RPC calls that can be sent from the client to a
2379 server. Increasing these values may allow you to
2380 improve throughput, but will also increase the
2381 amount of memory reserved for use by the client.
2384 [KNL] Enable accounting of swap in memory resource
2385 controller if no parameter or 1 is given or disable
2386 it if 0 is given (See Documentation/cgroups/memory.txt)
2388 swiotlb= [IA-64] Number of I/O TLB slabs
2392 sysfs.deprecated=0|1 [KNL]
2393 Enable/disable old style sysfs layout for old udev
2394 on older distributions. When this option is enabled
2395 very new udev will not work anymore. When this option
2396 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2397 in older udev will not work anymore.
2398 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2399 the kernel configuration.
2401 sysrq_always_enabled
2403 Ignore sysrq setting - this boot parameter will
2404 neutralize any effect of /proc/sys/kernel/sysrq.
2405 Useful for debugging.
2409 test_suspend= [SUSPEND]
2410 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2411 standby suspend) as the system sleep state to briefly
2412 enter during system startup. The system is woken from
2413 this state using a wakeup-capable RTC alarm.
2415 thash_entries= [KNL,NET]
2416 Set number of hash buckets for TCP connection
2418 thermal.act= [HW,ACPI]
2419 -1: disable all active trip points in all thermal zones
2420 <degrees C>: override all lowest active trip points
2422 thermal.crt= [HW,ACPI]
2423 -1: disable all critical trip points in all thermal zones
2424 <degrees C>: override all critical trip points
2426 thermal.nocrt= [HW,ACPI]
2427 Set to disable actions on ACPI thermal zone
2428 critical and hot trip points.
2430 thermal.off= [HW,ACPI]
2431 1: disable ACPI thermal control
2433 thermal.psv= [HW,ACPI]
2434 -1: disable all passive trip points
2435 <degrees C>: override all passive trip points to this
2438 thermal.tzp= [HW,ACPI]
2439 Specify global default ACPI thermal zone polling rate
2440 <deci-seconds>: poll all this frequency
2441 0: no polling (default)
2445 Specify if the kernel should make use of the cpu
2446 topology informations if the hardware supports these.
2447 The scheduler will make use of these informations and
2448 e.g. base its process migration decisions on it.
2453 tpm_suspend_pcr=[HW,TPM]
2454 Format: integer pcr id
2455 Specify that at suspend time, the tpm driver
2456 should extend the specified pcr with zeros,
2457 as a workaround for some chips which fail to
2458 flush the last written pcr on TPM_SaveState.
2459 This will guarantee that all the other pcrs
2462 trace_buf_size=nn[KMG]
2463 [FTRACE] will set tracing buffer size.
2465 trace_event=[event-list]
2466 [FTRACE] Set and start specified trace events in order
2467 to facilitate early boot debugging.
2468 See also Documentation/trace/events.txt
2470 tsc= Disable clocksource stability checks for TSC.
2472 [x86] reliable: mark tsc clocksource as reliable, this
2473 disables clocksource verification at runtime, as well
2474 as the stability checks done at bootup. Used to enable
2475 high-resolution timer mode on older hardware, and in
2476 virtualized environment.
2477 [x86] noirqtime: Do not use TSC to do irq accounting.
2478 Used to run time disable IRQ_TIME_ACCOUNTING on any
2479 platforms where RDTSC is slow and this accounting
2482 turbografx.map[2|3]= [HW,JOY]
2483 TurboGraFX parallel port interface
2485 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2486 See also Documentation/input/joystick-parport.txt
2488 uhash_entries= [KNL,NET]
2489 Set number of hash buckets for UDP/UDP-Lite connections
2492 [USB] Ignore overcurrent events (default N).
2493 Some badly-designed motherboards generate lots of
2494 bogus events, for ports that aren't wired to
2495 anything. Set this parameter to avoid log spamming.
2496 Note that genuine overcurrent events won't be
2501 Set unknown_nmi_panic=1 early on boot.
2503 usbcore.autosuspend=
2504 [USB] The autosuspend time delay (in seconds) used
2505 for newly-detected USB devices (default 2). This
2506 is the time required before an idle device will be
2507 autosuspended. Devices for which the delay is set
2508 to a negative value won't be autosuspended at all.
2510 usbcore.usbfs_snoop=
2511 [USB] Set to log all usbfs traffic (default 0 = off).
2513 usbcore.blinkenlights=
2514 [USB] Set to cycle leds on hubs (default 0 = off).
2516 usbcore.old_scheme_first=
2517 [USB] Start with the old device initialization
2518 scheme (default 0 = off).
2520 usbcore.use_both_schemes=
2521 [USB] Try the other device initialization scheme
2522 if the first one fails (default 1 = enabled).
2524 usbcore.initial_descriptor_timeout=
2525 [USB] Specifies timeout for the initial 64-byte
2526 USB_REQ_GET_DESCRIPTOR request in milliseconds
2527 (default 5000 = 5.0 seconds).
2530 [USBHID] The interval which mice are to be polled at.
2532 usb-storage.delay_use=
2533 [UMS] The delay in seconds before a new device is
2534 scanned for Logical Units (default 5).
2537 [UMS] A list of quirks entries to supplement or
2538 override the built-in unusual_devs list. List
2539 entries are separated by commas. Each entry has
2540 the form VID:PID:Flags where VID and PID are Vendor
2541 and Product ID values (4-digit hex numbers) and
2542 Flags is a set of characters, each corresponding
2543 to a common usb-storage quirk flag as follows:
2544 a = SANE_SENSE (collect more than 18 bytes
2546 b = BAD_SENSE (don't collect more than 18
2547 bytes of sense data);
2548 c = FIX_CAPACITY (decrease the reported
2549 device capacity by one sector);
2550 h = CAPACITY_HEURISTICS (decrease the
2551 reported device capacity by one
2552 sector if the number is odd);
2553 i = IGNORE_DEVICE (don't bind to this
2555 l = NOT_LOCKABLE (don't try to lock and
2556 unlock ejectable media);
2557 m = MAX_SECTORS_64 (don't transfer more
2558 than 64 sectors = 32 KB at a time);
2559 o = CAPACITY_OK (accept the capacity
2560 reported by the device);
2561 r = IGNORE_RESIDUE (the device reports
2562 bogus residue values);
2563 s = SINGLE_LUN (the device has only one
2565 w = NO_WP_DETECT (don't test whether the
2566 medium is write-protected).
2567 Example: quirks=0419:aaf5:rl,0421:0433:rc
2570 [X86] Flags controlling user PTE allocations.
2572 nohigh = do not allocate PTE pages in
2573 HIGHMEM regardless of setting
2577 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2578 vdso=1: enable VDSO (default)
2579 vdso=0: disable VDSO mapping
2582 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2583 vdso32=1: enable 32-bit VDSO (default)
2584 vdso32=0: disable 32-bit VDSO mapping
2587 vector=percpu: enable percpu vector domain
2589 video= [FB] Frame buffer configuration
2590 See Documentation/fb/modedb.txt.
2592 vga= [BOOT,X86-32] Select a particular video mode
2593 See Documentation/x86/boot.txt and
2594 Documentation/svga.txt.
2595 Use vga=ask for menu.
2596 This is actually a boot loader parameter; the value is
2597 passed to the kernel using a special protocol.
2599 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2600 size of <nn>. This can be used to increase the
2601 minimum size (128MB on x86). It can also be used to
2602 decrease the size and leave more room for directly
2605 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2608 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2611 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2614 vt.cur_default= [VT] Default cursor shape.
2615 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2616 the parameters of the <Esc>[?A;B;Cc escape sequence;
2617 see VGA-softcursor.txt. Default: 2 = underline.
2619 vt.default_blu= [VT]
2620 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2621 Change the default blue palette of the console.
2622 This is a 16-member array composed of values
2625 vt.default_grn= [VT]
2626 Format: <green0>,<green1>,<green2>,...,<green15>
2627 Change the default green palette of the console.
2628 This is a 16-member array composed of values
2631 vt.default_red= [VT]
2632 Format: <red0>,<red1>,<red2>,...,<red15>
2633 Change the default red palette of the console.
2634 This is a 16-member array composed of values
2640 Set system-wide default UTF-8 mode for all tty's.
2641 Default is 1, i.e. UTF-8 mode is enabled for all
2642 newly opened terminals.
2644 vt.global_cursor_default=
2647 Set system-wide default for whether a cursor
2648 is shown on new VTs. Default is -1,
2649 i.e. cursors will be created by default unless
2650 overridden by individual drivers. 0 will hide
2651 cursors, 1 will display them.
2653 watchdog timers [HW,WDT] For information on watchdog timers,
2654 see Documentation/watchdog/watchdog-parameters.txt
2655 or other driver-specific files in the
2656 Documentation/watchdog/ directory.
2658 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2659 default x2apic cluster mode on platforms
2662 x86_mrst_timer= [X86-32,APBT]
2663 Choose timer option for x86 Moorestown MID platform.
2664 Two valid options are apbt timer only and lapic timer
2665 plus one apbt timer for broadcast timer.
2666 x86_mrst_timer=apbt_only | lapic_and_apbt
2668 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2669 xd_geo= See header of drivers/block/xd.c.
2671 xen_emul_unplug= [HW,X86,XEN]
2672 Unplug Xen emulated devices
2673 Format: [unplug0,][unplug1]
2674 ide-disks -- unplug primary master IDE devices
2675 aux-ide-disks -- unplug non-primary-master IDE devices
2676 nics -- unplug network devices
2677 all -- unplug all emulated devices (NICs and IDE disks)
2678 unnecessary -- unplugging emulated devices is
2679 unnecessary even if the host did not respond to
2681 never -- do not unplug even if version check succeeds
2683 xirc2ps_cs= [NET,PCMCIA]
2685 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2687 ______________________________________________________________________
2691 Add more DRM drivers.
projects / mv-sheeva.git / blob