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 HW Appropriate hardware is enabled.
52 IA-64 IA-64 architecture is enabled.
53 IMA Integrity measurement architecture is enabled.
54 IOSCHED More than one I/O scheduler is enabled.
55 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
56 ISAPNP ISA PnP code is enabled.
57 ISDN Appropriate ISDN support is enabled.
58 JOY Appropriate joystick support is enabled.
59 LIBATA Libata driver is enabled
60 LP Printer support is enabled.
61 LOOP Loopback device support is enabled.
62 M68k M68k architecture is enabled.
63 These options have more detailed description inside of
64 Documentation/m68k/kernel-options.txt.
65 MCA MCA bus support is enabled.
66 MDA MDA console support is enabled.
67 MOUSE Appropriate mouse support is enabled.
68 MSI Message Signaled Interrupts (PCI).
69 MTD MTD (Memory Technology Device) support is enabled.
70 NET Appropriate network support is enabled.
71 NUMA NUMA support is enabled.
72 GENERIC_TIME The generic timeofday code is enabled.
73 NFS Appropriate NFS support is enabled.
74 OSS OSS sound support is enabled.
75 PV_OPS A paravirtualized kernel is enabled.
76 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
77 PARISC The PA-RISC architecture is enabled.
78 PCI PCI bus support is enabled.
79 PCIE PCI Express support is enabled.
80 PCMCIA The PCMCIA subsystem is enabled.
81 PNP Plug & Play support is enabled.
82 PPC PowerPC architecture is enabled.
83 PPT Parallel port support is enabled.
84 PS2 Appropriate PS/2 support is enabled.
85 RAM RAM disk support is enabled.
86 ROOTPLUG The example Root Plug LSM is enabled.
87 S390 S390 architecture is enabled.
88 SCSI Appropriate SCSI support is enabled.
89 A lot of drivers has their options described inside of
91 SECURITY Different security models are enabled.
92 SELINUX SELinux support is enabled.
93 SERIAL Serial support is enabled.
94 SH SuperH architecture is enabled.
95 SMP The kernel is an SMP kernel.
96 SPARC Sparc architecture is enabled.
97 SWSUSP Software suspend (hibernation) is enabled.
98 SUSPEND System suspend states are enabled.
99 FTRACE Function tracing enabled.
100 TS Appropriate touchscreen support is enabled.
101 UMS USB Mass Storage support is enabled.
102 USB USB support is enabled.
103 USBHID USB Human Interface Device support is enabled.
104 V4L Video For Linux support is enabled.
105 VGA The VGA console has been enabled.
106 VT Virtual terminal support is enabled.
107 WDT Watchdog support is enabled.
108 XT IBM PC/XT MFM hard disk support is enabled.
109 X86-32 X86-32, aka i386 architecture is enabled.
110 X86-64 X86-64 architecture is enabled.
111 More X86-64 boot options can be found in
112 Documentation/x86/x86_64/boot-options.txt .
113 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
115 In addition, the following text indicates that the option:
117 BUGS= Relates to possible processor bugs on the said processor.
118 KNL Is a kernel start-up parameter.
119 BOOT Is a boot loader parameter.
121 Parameters denoted with BOOT are actually interpreted by the boot
122 loader, and have no meaning to the kernel directly.
123 Do not modify the syntax of boot loader parameters without extreme
124 need or coordination with <Documentation/x86/boot.txt>.
126 There are also arch-specific kernel-parameters not documented here.
127 See for example <Documentation/x86/x86_64/boot-options.txt>.
129 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
130 a trailing = on the name of any parameter states that that parameter will
131 be entered as an environment variable, whereas its absence indicates that
132 it will appear as a kernel argument readable via /proc/cmdline by programs
133 running once the system is up.
135 The number of kernel parameters is not limited, but the length of the
136 complete command line (parameters including spaces etc.) is limited to
137 a fixed number of characters. This limit depends on the architecture
138 and is between 256 and 4096 characters. It is defined in the file
139 ./include/asm/setup.h as COMMAND_LINE_SIZE.
143 Advanced Configuration and Power Interface
144 Format: { force | off | ht | strict | noirq | rsdt }
145 force -- enable ACPI if default was off
146 off -- disable ACPI if default was on
147 noirq -- do not use ACPI for IRQ routing
148 ht -- run only enough ACPI to enable Hyper Threading
149 strict -- Be less tolerant of platforms that are not
150 strictly ACPI specification compliant.
151 rsdt -- prefer RSDT over (default) XSDT
153 See also Documentation/power/pm.txt, pci=noacpi
155 acpi_apic_instance= [ACPI, IOAPIC]
157 2: use 2nd APIC table, if available
158 1,0: use 1st APIC table
161 acpi_backlight= [HW,ACPI]
162 acpi_backlight=vendor
164 If set to vendor, prefer vendor specific driver
165 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
166 of the ACPI video.ko driver.
168 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
169 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
171 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
172 debug output. Bits in debug_layer correspond to a
173 _COMPONENT in an ACPI source file, e.g.,
174 #define _COMPONENT ACPI_PCI_COMPONENT
175 Bits in debug_level correspond to a level in
176 ACPI_DEBUG_PRINT statements, e.g.,
177 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
178 The debug_level mask defaults to "info". See
179 Documentation/acpi/debug.txt for more information about
180 debug layers and levels.
182 Enable processor driver info messages:
183 acpi.debug_layer=0x20000000
184 Enable PCI/PCI interrupt routing info messages:
185 acpi.debug_layer=0x400000
186 Enable AML "Debug" output, i.e., stores to the Debug
187 object while interpreting AML:
188 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
189 Enable all messages related to ACPI hardware:
190 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
192 Some values produce so much output that the system is
193 unusable. The "log_buf_len" parameter may be useful
194 if you need to capture more output.
196 acpi_display_output= [HW,ACPI]
197 acpi_display_output=vendor
198 acpi_display_output=video
201 acpi_irq_balance [HW,ACPI]
202 ACPI will balance active IRQs
205 acpi_irq_nobalance [HW,ACPI]
206 ACPI will not move active IRQs (default)
209 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
210 Format: <irq>,<irq>...
212 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
214 Format: <irq>,<irq>...
216 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
218 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
219 Format: To spoof as Windows 98: ="Microsoft Windows"
221 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
222 acpi_osi="string1" # add string1 -- only one string
223 acpi_osi="!string2" # remove built-in string2
224 acpi_osi= # disable all strings
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
231 acpi.power_nocheck= [HW,ACPI]
232 Format: 1/0 enable/disable the check of power state.
233 On some bogus BIOS the _PSC object/_STA object of
234 power resource can't return the correct device power
235 state. In such case it is unneccessary to check its
236 power state again in power transition.
237 1 : disable the power state check
239 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
240 Format: { level | edge | high | low }
242 acpi_serialize [HW,ACPI] force serialization of AML methods
244 acpi_skip_timer_override [HW,ACPI]
245 Recognize and ignore IRQ0/pin2 Interrupt Override.
246 For broken nForce2 BIOS resulting in XT-PIC timer.
248 acpi_sleep= [HW,ACPI] Sleep options
249 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
250 old_ordering, s4_nonvs }
251 See Documentation/power/video.txt for information on
253 s3_beep is for debugging; it makes the PC's speaker beep
254 as soon as the kernel's real-mode entry point is called.
255 s4_nohwsig prevents ACPI hardware signature from being
256 used during resume from hibernation.
257 old_ordering causes the ACPI 1.0 ordering of the _PTS
258 control method, with respect to putting devices into
259 low power states, to be enforced (the ACPI 2.0 ordering
260 of _PTS is used by default).
261 s4_nonvs prevents the kernel from saving/restoring the
262 ACPI NVS memory during hibernation.
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
291 See header of drivers/scsi/advansys.c.
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
307 See Documentation/scsi/aha152x.txt.
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
313 See Documentation/scsi/aic7xxx.txt.
316 See Documentation/scsi/aic79xx.txt.
318 amd_iommu= [HW,X86-84]
319 Pass parameters to the AMD IOMMU driver in the system.
321 isolate - enable device isolation (each device, as far
322 as possible, will get its own protection
324 share - put every device behind one IOMMU into the
325 same protection domain
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
331 amijoy.map= [HW,JOY] Amiga joystick support
332 Map of devices attached to JOY0DAT and JOY1DAT
334 See also Documentation/kernel/input/joystick.txt
336 analog.map= [HW,JOY] Analog joystick and gamepad support
337 Specifies type or capabilities of an analog joystick
338 connected to one of 16 gameports
339 Format: <type1>,<type2>,..<type16>
342 Power management functions (SPARCstation-4/5 + deriv.)
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
346 APC and your system crashes randomly.
348 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
349 Change the output verbosity whilst booting
350 Format: { quiet (default) | verbose | debug }
351 Change the amount of debugging information output
352 when initialising the APIC and IO-APIC components.
354 apm= [APM] Advanced Power Management
355 See header of arch/x86/kernel/apm_32.c.
357 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
358 Format: <io>,<irq>,<nodeID>
362 atarimouse= [HW,MOUSE] Atari Mouse
364 atascsi= [HW,SCSI] Atari SCSI
366 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
367 EzKey and similar keyboards
369 atkbd.reset= [HW] Reset keyboard during initialization
371 atkbd.set= [HW] Select keyboard code set
372 Format: <int> (2 = AT (default), 3 = PS/2)
374 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
377 atkbd.softraw= [HW] Choose between synthetic and real raw mode
378 Format: <bool> (0 = real, 1 = synthetic (default))
380 atkbd.softrepeat= [HW]
381 Use software keyboard repeat
385 baycom_epp= [HW,AX25]
388 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
390 See header of drivers/net/hamradio/baycom_par.c.
392 baycom_ser_fdx= [HW,AX25]
393 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
394 Format: <io>,<irq>,<mode>[,<baud>]
395 See header of drivers/net/hamradio/baycom_ser_fdx.c.
397 baycom_ser_hdx= [HW,AX25]
398 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
399 Format: <io>,<irq>,<mode>
400 See header of drivers/net/hamradio/baycom_ser_hdx.c.
402 boot_delay= Milliseconds to delay each printk during boot.
403 Values larger than 10 seconds (10000) are changed to
407 bootmem_debug [KNL] Enable bootmem allocator debug messages.
409 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
410 bttv.radio= Most important insmod options are available as
412 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
413 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
416 See drivers/scsi/BusLogic.c, comment before function
417 BusLogic_ParseDriverOptions().
419 c101= [NET] Moxa C101 synchronous serial card
421 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
422 Sometimes CPU hardware bugs make them report the cache
423 size incorrectly. The kernel will attempt work arounds
424 to fix known problems, but for some CPUs it is not
425 possible to determine what the correct size should be.
426 This option provides an override for these situations.
429 [SECURITY] Disable capabilities. This would normally
430 be used only if an alternative security model is to be
431 configured. Potentially dangerous and should only be
432 used if you are entirely sure of the consequences.
434 ccw_timeout_log [S390]
435 See Documentation/s390/CommonIO for details.
437 cgroup_disable= [KNL] Disable a particular controller
438 Format: {name of the controller(s) to disable}
439 {Currently supported controllers - "memory"}
441 checkreqprot [SELINUX] Set initial checkreqprot flag value.
442 Format: { "0" | "1" }
443 See security/selinux/Kconfig help text.
444 0 -- check protection applied by kernel (includes
445 any implied execute protection).
446 1 -- check protection requested by application.
447 Default value is set via a kernel config option.
448 Value can be changed at runtime via
449 /selinux/checkreqprot.
452 See Documentation/s390/CommonIO for details.
454 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
456 Forces specified clocksource (if available) to be used
457 when calculating gettimeofday(). If specified
458 clocksource is not available, it defaults to PIT.
459 Format: { pit | tsc | cyclone | pmtmr }
461 clocksource= [GENERIC_TIME] Override the default clocksource
463 Override the default clocksource and use the clocksource
464 with the name specified.
465 Some clocksource names to choose from, depending on
467 [all] jiffies (this is the base, fallback clocksource)
469 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
470 pxa_timer,timer3,32k_counter,timer0_1
472 [X86-32] pit,hpet,tsc,vmi-timer;
473 scx200_hrt on Geode; cyclone on IBM x440
481 clearcpuid=BITNUM [X86]
482 Disable CPUID feature X for the kernel. See
483 arch/x86/include/asm/cpufeature.h for the valid bit
484 numbers. Note the Linux specific bits are not necessarily
485 stable over kernel options, but the vendor specific
487 Also note that user programs calling CPUID directly
488 or using the feature without checking anything
489 will still see it. This just prevents it from
490 being used by the kernel or shown in /proc/cpuinfo.
491 Also note the kernel might malfunction if you disable
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.
543 [KNL] Change the default value for
544 /proc/<pid>/coredump_filter.
545 See also Documentation/filesystems/proc.txt.
547 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
549 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
551 crashkernel=nn[KMG]@ss[KMG]
552 [KNL] Reserve a chunk of physical memory to
553 hold a kernel to switch to with kexec on panic.
555 crashkernel=range1:size1[,range2:size2,...][@offset]
556 [KNL] Same as above, but depends on the memory
557 in the running system. The syntax of range is
558 start-[end] where start and end are both
559 a memory unit (amount[KMG]). See also
560 Documentation/kdump/kdump.txt for a example.
565 cs89x0_media= [HW,NET]
566 Format: { rj45 | aui | bnc }
569 See header of drivers/s390/block/dasd_devmap.c.
571 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
572 (one device per port)
573 Format: <port#>,<type>
574 See also Documentation/input/joystick-parport.txt
576 debug [KNL] Enable kernel debugging (events log level).
579 [KNL] verbose self-tests
581 Print debugging info while doing the locking API
583 We default to 0 (no extra messages), setting it to
584 1 will print _a lot_ more information - normally
585 only useful to kernel developers.
587 debug_objects [KNL] Enable object debugging
590 [KNL] Disable object debugging
592 debugpat [X86] Enable PAT debugging
594 decnet.addr= [HW,NET]
595 Format: <area>[,<node>]
596 See also Documentation/networking/decnet.txt.
599 [same as hugepagesz=] The size of the default
600 HugeTLB page size. This is the size represented by
601 the legacy /proc/ hugepages APIs, used for SHM, and
602 default size when mounting hugetlbfs filesystems.
603 Defaults to the default architecture's huge page size
607 Set number of hash buckets for dentry cache.
610 IO parameters + enable/disable command.
612 digiepca= [HW,SERIAL]
613 See drivers/char/README.epca and
614 Documentation/serial/digiepca.txt.
616 disable_mtrr_cleanup [X86]
617 The kernel tries to adjust MTRR layout from continuous
618 to discrete, to make X server driver able to add WB
619 entry later. This parameter disables that.
621 disable_mtrr_trim [X86, Intel and AMD only]
622 By default the kernel will trim any uncacheable
623 memory out of your available memory pool based on
624 MTRR settings. This parameter disables that behavior,
625 possibly causing your machine to run very slowly.
627 disable_timer_pin_1 [X86]
628 Disable PIN 1 of APIC timer
629 Can be useful to work around chipset bugs.
631 dmasound= [HW,OSS] Sound subsystem buffers
633 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
634 this option disables the debugging code at boot.
636 dma_debug_entries=<number>
637 This option allows to tune the number of preallocated
638 entries for DMA-API debugging code. One entry is
639 required per DMA-API allocation. Use this if the
640 DMA-API debugging code disables itself because the
641 architectural default is too low.
643 dma_debug_driver=<driver_name>
644 With this option the DMA-API debugging driver
645 filter feature can be enabled at boot time. Just
646 pass the driver to filter for as the parameter.
647 The filter can be disabled or changed to another
648 driver later using sysfs.
654 dynamic_printk Enables pr_debug()/dev_dbg() calls if
655 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
656 These can also be switched on/off via
657 <debugfs>/dynamic_printk/modules
659 earlycon= [KNL] Output early console device and options.
660 uart[8250],io,<addr>[,options]
661 uart[8250],mmio,<addr>[,options]
662 Start an early, polled-mode console on the 8250/16550
663 UART at the specified I/O port or MMIO address.
664 The options are the same as for ttyS, above.
666 earlyprintk= [X86,SH,BLACKFIN]
668 earlyprintk=serial[,ttySn[,baudrate]]
671 Append ",keep" to not disable it when the real console
674 Only vga or serial or usb debug port at a time.
676 Currently only ttyS0 and ttyS1 are supported.
678 Interaction with the standard serial driver is not
681 The VGA output is eventually overwritten by the real
687 Format: {"off" | "on" | "skip[mbr]"}
689 eisa_irq_edge= [PARISC,HW]
690 See header of drivers/parisc/eisa.c.
693 See comment before function elanfreq_setup() in
694 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
697 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
698 See Documentation/block/as-iosched.txt and
699 Documentation/block/deadline-iosched.txt for details.
701 elfcorehdr= [IA64,PPC,SH,X86]
702 Specifies physical address of start of kernel core
703 image elf header. Generally kexec loader will
704 pass this option to capture kernel.
705 See Documentation/kdump/kdump.txt for details.
707 enable_mtrr_cleanup [X86]
708 The kernel tries to adjust MTRR layout from continuous
709 to discrete, to make X server driver able to add WB
710 entry later. This parameter enables that.
712 enable_timer_pin_1 [X86]
713 Enable PIN 1 of APIC timer
714 Can be useful to work around chipset bugs
715 (in particular on some ATI chipsets).
716 The kernel tries to set a reasonable default.
718 enforcing [SELINUX] Set initial enforcing status.
720 See security/selinux/Kconfig help text.
721 0 -- permissive (log only, no denials).
722 1 -- enforcing (deny and log).
724 Value can be changed at runtime via /selinux/enforce.
726 ether= [HW,NET] Ethernet cards parameters
727 This option is obsoleted by the "netdev=" option, which
728 has equivalent usage. See its documentation for details.
730 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
735 fail_make_request=[KNL]
736 General fault injection mechanism.
737 Format: <interval>,<probability>,<space>,<times>
738 See also /Documentation/fault-injection/.
741 See header of drivers/scsi/fd_mcs.c.
744 See header of drivers/scsi/fdomain.c.
747 See Documentation/blockdev/floppy.txt.
749 force_pal_cache_flush
750 [IA-64] Avoid check_sal_cache_flush which may hang on
751 buggy SAL_CACHE_FLUSH implementations. Using this
752 parameter will force ia64_sal_cache_flush to call
753 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
756 [FTRACE] will set and start the specified tracer
757 as early as possible in order to facilitate early
761 [FTRACE] will dump the trace buffers on oops.
763 ftrace_filter=[function-list]
764 [FTRACE] Limit the functions traced by the function
765 tracer at boot up. function-list is a comma separated
766 list of functions. This list can be changed at run
767 time by the set_ftrace_filter file in the debugfs
770 ftrace_notrace=[function-list]
771 [FTRACE] Do not trace the functions specified in
772 function-list. This list can be changed at run time
773 by the set_ftrace_notrace file in the debugfs
777 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
778 support via parallel port (up to 5 devices per port)
779 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
780 See also Documentation/input/joystick-parport.txt
784 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
789 See header of drivers/scsi/gdth.c.
791 gpt [EFI] Forces disk with valid GPT signature but
792 invalid Protective MBR to be treated as GPT.
796 hashdist= [KNL,NUMA] Large hashes allocated during boot
797 are distributed across NUMA nodes. Defaults on
798 for 64bit NUMA, off otherwise.
799 Format: 0 | 1 (for off | on)
801 hcl= [IA-64] SGI's Hardware Graph compatibility layer
803 hd= [EIDE] (E)IDE hard drive subsystem geometry
804 Format: <cyl>,<head>,<sect>
806 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
807 size of <nn>. This works even on boxes that have no
808 highmem otherwise. This also works to reduce highmem
809 size on bigger boxes.
811 highres= [KNL] Enable/disable high resolution timer mode.
812 Valid parameters: "on", "off"
816 See Documentation/isdn/README.HiSax.
820 hpet= [X86-32,HPET] option to control HPET usage
821 Format: { enable (default) | disable | force |
823 disable: disable HPET and use PIT instead
824 force: allow force enabled of undocumented chips (ICH4,
826 verbose: show contents of HPET registers during setup
828 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
829 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
830 On x86-64 and powerpc, this option can be specified
831 multiple times interleaved with hugepages= to reserve
832 huge pages of different sizes. Valid pages sizes on
833 x86-64 are 2M (when the CPU supports "pse") and 1G
834 (when the CPU supports the "pdpe1gb" cpuinfo flag)
835 Note that 1GB pages can only be allocated at boot time
836 using hugepages= and not freed afterwards.
838 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
839 terminal devices. Valid values: 0..8
840 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
841 If specified, z/VM IUCV HVC accepts connections
842 from listed z/VM user IDs only.
844 i2c_bus= [HW] Override the default board specific I2C bus speed
845 or register an additional I2C bus that is not
846 registered from board initialization code.
850 i8042.debug [HW] Toggle i8042 debug mode
851 i8042.direct [HW] Put keyboard port into non-translated mode
852 i8042.dumbkbd [HW] Pretend that controller can only read data from
853 keyboard and cannot control its state
854 (Don't attempt to blink the leds)
855 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
856 i8042.nokbd [HW] Don't check/create keyboard port
857 i8042.noloop [HW] Disable the AUX Loopback command while probing
859 i8042.nomux [HW] Don't check presence of an active multiplexing
861 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
864 [HW] Frequency with which keyboard LEDs should blink
865 when kernel panics (default is 0.5 sec)
866 i8042.reset [HW] Reset the controller during init and cleanup
867 i8042.unlock [HW] Unlock (ignore) the keylock
871 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
872 indicates that the driver is running on unsupported
874 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
875 does not match list of supported models.
877 [HW] Report power status in /proc/i8k
878 (disabled by default)
879 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
882 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
883 See Documentation/mca.txt.
886 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
888 ide-core.nodma= [HW] (E)IDE subsystem
889 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
890 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
891 .chs .ignore_cable are additional options
892 See Documentation/ide/ide.txt.
894 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
895 See Documentation/ide/ide.txt.
897 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
898 Claim all unknown PCI IDE storage controllers.
901 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
902 Poll forces a polling idle loop that can slightly
903 improve the performance of waking up a idle CPU, but
904 will use a lot of power and make the system run hot.
906 idle=mwait: On systems which support MONITOR/MWAIT but
907 the kernel chose to not use it because it doesn't save
908 as much power as a normal idle loop, use the
909 MONITOR/MWAIT idle loop anyways. Performance should be
910 the same as idle=poll.
911 idle=halt: Halt is forced to be used for CPU idle.
912 In such case C2/C3 won't be used again.
913 idle=nomwait: Disable mwait for CPU C-states
915 ignore_loglevel [KNL]
916 Ignore loglevel setting - this will print /all/
917 kernel messages to the console. Useful for debugging.
920 Set number of hash buckets for inode cache.
923 Format: { "0" | "1" }
924 0 -- integrity auditing messages. (Default)
925 1 -- enable informational integrity auditing messages.
928 Formt: { "sha1" | "md5" }
932 See header of drivers/scsi/in2000.c.
936 Run specified binary instead of /sbin/init as init
939 initcall_debug [KNL] Trace initcalls as they are executed. Useful
940 for working out where the kernel is dying during
943 initrd= [BOOT] Specify the location of the initial ramdisk
945 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
948 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
950 Enable intel iommu driver.
952 Disable intel iommu driver.
953 igfx_off [Default Off]
954 By default, gfx is mapped as normal device. If a gfx
955 device has a dedicated DMAR unit, the DMAR unit is
956 bypassed by not enabling DMAR with this option. In
957 this case, gfx device will use physical address for
960 With this option iommu will not optimize to look
961 for io virtual address below 32 bit forcing dual
962 address cycle on pci bus for cards supporting greater
963 than 32 bit addressing. The default is to look
964 for translation below 32 bit and if not available
965 then look in the higher range.
967 With this option on every unmap_single operation will
968 result in a hardware IOTLB flush operation as opposed
969 to batching them for performance.
973 iomem= Disable strict checking of access to MMIO memory
974 strict regions from userspace.
989 io7= [HW] IO7 for Marvel based alpha systems
990 See comment before marvel_specify_io7 in
991 arch/alpha/kernel/core_marvel.c.
993 io_delay= [X86] I/O delay method
995 Standard port 0x80 based delay
997 Alternate port 0xed based delay (needed on some systems)
999 Simple two microseconds delay
1004 See Documentation/filesystems/nfsroot.txt.
1006 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1007 See comment before ip2_setup() in
1008 drivers/char/ip2/ip2base.c.
1010 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1011 See header of drivers/scsi/ips.c.
1014 When an interrupt is not handled search all handlers
1015 for it. Intended to get systems with badly broken
1019 When an interrupt is not handled search all handlers
1020 for it. Also check all handlers each timer
1021 interrupt. Intended to get systems with badly broken
1025 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1027 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1029 <cpu number>,...,<cpu number>
1031 <cpu number>-<cpu number>
1032 (must be a positive range in ascending order)
1034 <cpu number>,...,<cpu number>-<cpu number>
1036 This option can be used to specify one or more CPUs
1037 to isolate from the general SMP balancing and scheduling
1038 algorithms. You can move a process onto or off an
1039 "isolated" CPU via the CPU affinity syscalls or cpuset.
1040 <cpu number> begins at 0 and the maximum value is
1041 "number of CPUs in system - 1".
1043 This option is the preferred way to isolate CPUs. The
1044 alternative -- manually setting the CPU mask of all
1045 tasks in the system -- can cause problems and
1046 suboptimal load balancer performance.
1050 js= [HW,JOY] Analog joystick
1051 See Documentation/input/joystick.txt.
1055 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1056 specifies the amount of memory usable by the kernel
1057 for non-movable allocations. The requested amount is
1058 spread evenly throughout all nodes in the system. The
1059 remaining memory in each node is used for Movable
1060 pages. In the event, a node is too small to have both
1061 kernelcore and Movable pages, kernelcore pages will
1062 take priority and other nodes will have a larger number
1063 of kernelcore pages. The Movable zone is used for the
1064 allocation of pages that may be reclaimed or moved
1065 by the page migration subsystem. This means that
1066 HugeTLB pages may not be allocated from this zone.
1067 Note that allocations like PTEs-from-HighMem still
1068 use the HighMem zone if it exists, and the Normal
1069 zone if it does not.
1071 kgdboc= [HW] kgdb over consoles.
1072 Requires a tty driver that supports console polling.
1073 (only serial suported for now)
1074 Format: <serial_device>[,baud]
1076 kmac= [MIPS] korina ethernet MAC address.
1077 Configure the RouterBoard 532 series on-chip
1078 Ethernet adapter MAC address.
1080 kmemleak= [KNL] Boot-time kmemleak enable/disable
1081 Valid arguments: on, off
1084 kstack=N [X86] Print N words from the kernel stack
1091 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1094 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1097 libata.dma= [LIBATA] DMA control
1098 libata.dma=0 Disable all PATA and SATA DMA
1099 libata.dma=1 PATA and SATA Disk DMA only
1100 libata.dma=2 ATAPI (CDROM) DMA only
1101 libata.dma=4 Compact Flash DMA only
1102 Combinations also work, so libata.dma=3 enables DMA
1103 for disks and CDROMs, but not CFs.
1105 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1109 libata.force= [LIBATA] Force configurations. The format is comma
1110 separated list of "[ID:]VAL" where ID is
1111 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1112 matching port, link or device. Basically, it matches
1113 the ATA ID string printed on console by libata. If
1114 the whole ID part is omitted, the last PORT and DEVICE
1115 values are used. If ID hasn't been specified yet, the
1116 configuration applies to all ports, links and devices.
1118 If only DEVICE is omitted, the parameter applies to
1119 the port and all links and devices behind it. DEVICE
1120 number of 0 either selects the first device or the
1121 first fan-out link behind PMP device. It does not
1122 select the host link. DEVICE number of 15 selects the
1123 host link and device attached to it.
1125 The VAL specifies the configuration to force. As long
1126 as there's no ambiguity shortcut notation is allowed.
1127 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1128 The following configurations can be forced.
1130 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1131 Any ID with matching PORT is used.
1133 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1135 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1136 udma[/][16,25,33,44,66,100,133] notation is also
1139 * [no]ncq: Turn on or off NCQ.
1141 * nohrst, nosrst, norst: suppress hard, soft
1144 If there are multiple matching configurations changing
1145 the same attribute, the last one is used.
1147 lmb=debug [KNL] Enable lmb debug messages.
1149 load_ramdisk= [RAM] List of ramdisks to load from floppy
1150 See Documentation/blockdev/ramdisk.txt.
1152 lockd.nlm_grace_period=P [NFS] Assign grace period.
1155 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1158 lockd.nlm_timeout=T [NFS] Assign timeout value.
1161 lockd.nlm_udpport=M [NFS] Assign UDP port.
1164 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1167 loglevel= All Kernel Messages with a loglevel smaller than the
1168 console loglevel will be printed to the console. It can
1169 also be changed with klogd or other programs. The
1170 loglevels are defined as follows:
1172 0 (KERN_EMERG) system is unusable
1173 1 (KERN_ALERT) action must be taken immediately
1174 2 (KERN_CRIT) critical conditions
1175 3 (KERN_ERR) error conditions
1176 4 (KERN_WARNING) warning conditions
1177 5 (KERN_NOTICE) normal but significant condition
1178 6 (KERN_INFO) informational
1179 7 (KERN_DEBUG) debug-level messages
1181 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1182 Format: { n | nk | nM }
1183 n must be a power of two. The default size
1184 is set in the kernel config file.
1186 logo.nologo [FB] Disables display of the built-in Linux logo.
1187 This may be used to provide more screen space for
1188 kernel log messages and is useful when debugging
1189 kernel boot problems.
1191 lp=0 [LP] Specify parallel ports to use, e.g,
1192 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1193 lp=reset first parallel port). 'lp=0' disables the
1194 lp=auto printer driver. 'lp=reset' (which can be
1195 specified in addition to the ports) causes
1196 attached printers to be reset. Using
1197 lp=port1,port2,... specifies the parallel ports
1198 to associate lp devices with, starting with
1199 lp0. A port specification may be 'none' to skip
1200 that lp device, or a parport name such as
1201 'parport0'. Specifying 'lp=auto' instead of a
1202 port specification list means that device IDs
1203 from each port should be examined, to see if
1204 an IEEE 1284-compliant printer is attached; if
1205 so, the driver will manage that printer.
1206 See also header of drivers/char/lp.c.
1209 Sets loops_per_jiffy to given constant, thus avoiding
1210 time-consuming boot-time autodetection (up to 250 ms per
1211 CPU). 0 enables autodetection (default). To determine
1212 the correct value for your kernel, boot with normal
1213 autodetection and see what value is printed. Note that
1214 on SMP systems the preset will be applied to all CPUs,
1215 which is likely to cause problems if your CPUs need
1216 significantly divergent settings. An incorrect value
1217 will cause delays in the kernel to be wrong, leading to
1218 unpredictable I/O errors and other breakage. Although
1219 unlikely, in the extreme case this might damage your
1223 Format: <io>,<irq>,<dma>
1225 mac5380= [HW,SCSI] Format:
1226 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1228 machvec= [IA64] Force the use of a particular machine-vector
1229 (machvec) in a generic kernel.
1230 Example: machvec=hpzx1_swiotlb
1232 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1233 than or equal to this physical address is ignored.
1235 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1236 should make use of. maxcpus=n : n >= 0 limits the
1237 kernel to using 'n' processors. n=0 is a special case,
1238 it is equivalent to "nosmp", which also disables
1241 max_loop= [LOOP] Maximum number of loopback devices that can
1245 max_luns= [SCSI] Maximum number of LUNs to probe.
1246 Should be between 1 and 2^32-1.
1249 [SCSI] Maximum number of LUNs received.
1250 Should be between 1 and 16384.
1254 mce [X86-32] Machine Check Exception
1256 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1258 md= [HW] RAID subsystems devices and level
1259 See Documentation/md.txt.
1262 Format: <first>,<last>
1263 Specifies range of consoles to be captured by the MDA.
1265 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1266 Amount of memory to be used when the kernel is not able
1267 to see the whole system memory or for test.
1268 [X86-32] Use together with memmap= to avoid physical
1269 address space collisions. Without memmap= PCI devices
1270 could be placed at addresses belonging to unused RAM.
1272 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1276 [KNL,SH] Allow user to override the default size for
1277 per-device physically contiguous DMA buffers.
1279 memmap=exactmap [KNL,X86] Enable setting of an exact
1280 E820 memory map, as specified by the user.
1281 Such memmap=exactmap lines can be constructed based on
1282 BIOS output or other requirements. See the memmap=nn@ss
1285 memmap=nn[KMG]@ss[KMG]
1286 [KNL] Force usage of a specific region of memory
1287 Region of memory to be used, from ss to ss+nn.
1289 memmap=nn[KMG]#ss[KMG]
1290 [KNL,ACPI] Mark specific memory as ACPI data.
1291 Region of memory to be used, from ss to ss+nn.
1293 memmap=nn[KMG]$ss[KMG]
1294 [KNL,ACPI] Mark specific memory as reserved.
1295 Region of memory to be used, from ss to ss+nn.
1296 Example: Exclude memory from 0x18690000-0x1869ffff
1297 memmap=64K$0x18690000
1299 memmap=0x10000$0x18690000
1301 memory_corruption_check=0/1 [X86]
1302 Some BIOSes seem to corrupt the first 64k of
1303 memory when doing things like suspend/resume.
1304 Setting this option will scan the memory
1305 looking for corruption. Enabling this will
1306 both detect corruption and prevent the kernel
1307 from using the memory being corrupted.
1308 However, its intended as a diagnostic tool; if
1309 repeatable BIOS-originated corruption always
1310 affects the same memory, you can use memmap=
1311 to prevent the kernel from using that memory.
1313 memory_corruption_check_size=size [X86]
1314 By default it checks for corruption in the low
1315 64k, making this memory unavailable for normal
1316 use. Use this parameter to scan for
1317 corruption in more or less memory.
1319 memory_corruption_check_period=seconds [X86]
1320 By default it checks for corruption every 60
1321 seconds. Use this parameter to check at some
1322 other rate. 0 disables periodic checking.
1324 memtest= [KNL,X86] Enable memtest
1326 default : 0 <disable>
1327 Specifies the number of memtest passes to be
1328 performed. Each pass selects another test
1329 pattern from a given set of patterns. Memtest
1330 fills the memory with this pattern, validates
1331 memory contents and reserves bad memory
1332 regions that are detected.
1334 meye.*= [HW] Set MotionEye Camera parameters
1335 See Documentation/video4linux/meye.txt.
1337 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1338 Multi-Function General Purpose Timers on AMD Geode
1341 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1342 the BIOS has incorrectly applied a workaround. TinyBIOS
1343 version 0.98 is known to be affected, 0.99 fixes the
1344 problem by letting the user disable the workaround.
1348 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1349 physical address is ignored.
1352 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1353 parameter allows control of the logging verbosity for
1354 the additional memory initialisation checks. A value
1355 of 0 disables mminit logging and a level of 4 will
1356 log everything. Information is printed at KERN_DEBUG
1357 so loglevel=8 may also need to be specified.
1360 [MOUSE] Maximum time between finger touching and
1361 leaving touchpad surface for touch to be considered
1362 a tap and be reported as a left button click (for
1363 touchpads working in absolute mode only).
1365 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1366 reporting absolute coordinates, such as tablets
1367 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1368 reporting absolute coordinates, such as tablets
1370 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1371 is similar to kernelcore except it specifies the
1372 amount of memory used for migratable allocations.
1373 If both kernelcore and movablecore is specified,
1374 then kernelcore will be at *least* the specified
1375 value but may be more. If movablecore on its own
1376 is specified, the administrator must be careful
1377 that the amount of memory usable for all allocations
1383 MTD_Partition= [MTD]
1384 Format: <name>,<region-number>,<size>,<offset>
1386 MTD_Region= [MTD] Format:
1387 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1390 See drivers/mtd/cmdlinepart.c.
1393 ARM/S3C2412 JIVE boot control
1395 See arch/arm/mach-s3c2412/mach-jive.c
1397 mtouchusb.raw_coordinates=
1398 [HW] Make the MicroTouch USB driver use raw coordinates
1399 ('y', default) or cooked coordinates ('n')
1401 mtrr_chunk_size=nn[KMG] [X86]
1402 used for mtrr cleanup. It is largest continous chunk
1403 that could hold holes aka. UC entries.
1405 mtrr_gran_size=nn[KMG] [X86]
1406 Used for mtrr cleanup. It is granularity of mtrr block.
1408 Large value could prevent small alignment from
1411 mtrr_spare_reg_nr=n [X86]
1413 Range: 0,7 : spare reg number
1415 Used for mtrr cleanup. It is spare mtrr entries number.
1416 Set to 2 or more if your graphical card needs more.
1418 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1421 See header of drivers/scsi/NCR_D700.c.
1425 ncr53c400= [HW,SCSI]
1427 ncr53c400a= [HW,SCSI]
1429 ncr53c406a= [HW,SCSI]
1431 ncr53c8xx= [HW,SCSI]
1433 netdev= [NET] Network devices parameters
1434 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1435 Note that mem_start is often overloaded to mean
1436 something different and driver-specific.
1437 This usage is only documented in each driver source
1441 [NETFILTER] Enable connection tracking flow accounting
1442 0 to disable accounting
1443 1 to enable accounting
1444 Default value depends on CONFIG_NF_CT_ACCT that is
1445 going to be removed in 2.6.29.
1448 See Documentation/filesystems/nfsroot.txt.
1450 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1451 See Documentation/filesystems/nfsroot.txt.
1453 nfs.callback_tcpport=
1454 [NFS] set the TCP port on which the NFSv4 callback
1455 channel should listen.
1457 nfs.idmap_cache_timeout=
1458 [NFS] set the maximum lifetime for idmapper cache
1462 [NFS] enable 64-bit inode numbers.
1463 If zero, the NFS client will fake up a 32-bit inode
1464 number for the readdir() and stat() syscalls instead
1465 of returning the full 64-bit number.
1466 The default is to return 64-bit inode numbers.
1468 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1469 when a NMI is triggered.
1470 Format: [state][,regs][,debounce][,die]
1472 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1473 Format: [panic,][num]
1475 0 - turn nmi_watchdog off
1476 1 - use the IO-APIC timer for the NMI watchdog
1477 2 - use the local APIC for the NMI watchdog using
1478 a performance counter. Note: This will use one
1479 performance counter and the local APIC's performance
1481 When panic is specified, panic when an NMI watchdog
1483 This is useful when you use a panic=... timeout and
1484 need the box quickly up again.
1485 Instead of 1 and 2 it is possible to use the following
1486 symbolic names: lapic and ioapic
1487 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1489 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1490 emulation library even if a 387 maths coprocessor
1494 [HW] Never suspend the console
1495 Disable suspending of consoles during suspend and
1496 hibernate operations. Once disabled, debugging
1497 messages can reach various consoles while the rest
1498 of the system is being put to sleep (ie, while
1499 debugging driver suspend/resume hooks). This may
1500 not work reliably with all consoles, but is known
1501 to work with serial and VGA consoles.
1503 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1504 caches in the slab allocator. Saves per-node memory,
1505 but will impact performance.
1509 noapic [SMP,APIC] Tells the kernel to not make use of any
1510 IOAPICs that may be present in the system.
1512 nobats [PPC] Do not use BATs for mapping kernel lowmem
1513 on "Classic" PPC cores.
1517 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1519 nodelayacct [KNL] Disable per-task delay accounting
1521 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1523 nodsp [SH] Disable hardware DSP at boot time.
1525 noefi [X86] Disable EFI runtime services support.
1530 On X86-32 available only on PAE configured kernels.
1531 noexec=on: enable non-executable mappings (default)
1532 noexec=off: disable non-executable mappings
1535 This affects only 32-bit executables.
1536 noexec32=on: enable non-executable mappings (default)
1537 read doesn't imply executable mappings
1538 noexec32=off: disable non-executable mappings
1539 read implies executable mappings
1541 nofpu [SH] Disable hardware FPU at boot time.
1543 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1544 register save and restore. The kernel will only save
1545 legacy floating-point registers on task switch.
1547 noxsave [BUGS=X86] Disables x86 extended register state save
1548 and restore using xsave. The kernel will fallback to
1549 enabling legacy floating-point and sse state.
1551 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1552 wfi(ARM) instruction doesn't work correctly and not to
1553 use it. This is also useful when using JTAG debugger.
1555 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1556 instruction doesn't work correctly and not to
1559 no_file_caps Tells the kernel not to honor file capabilities. The
1560 only way then for a file to be executed with privilege
1561 is to be setuid root or executed by root.
1563 nohalt [IA-64] Tells the kernel not to use the power saving
1564 function PAL_HALT_LIGHT when idle. This increases
1565 power-consumption. On the positive side, it reduces
1566 interrupt wake-up latency, which may improve performance
1567 in certain environments such as networked servers or
1570 nohz= [KNL] Boottime enable/disable dynamic ticks
1571 Valid arguments: on, off
1574 noiotrap [SH] Disables trapped I/O port accesses.
1576 noirqdebug [X86-32] Disables the code which attempts to detect and
1577 disable unhandled interrupt sources.
1579 no_timer_check [X86,APIC] Disables the code which tests for
1580 broken timer IRQ sources.
1582 noisapnp [ISAPNP] Disables ISA PnP code.
1584 noinitrd [RAM] Tells the kernel not to load any configured
1587 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1592 nojitter [IA64] Disables jitter checking for ITC timers.
1594 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1596 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1598 noltlbs [PPC] Do not use large page/tlb entries for kernel
1599 lowmem mapping on PPC40x.
1601 nomca [IA-64] Disable machine check abort handling
1603 nomce [X86-32] Machine Check Exception
1605 nomfgpt [X86-32] Disable Multi-Function General Purpose
1606 Timer usage (for AMD Geode machines).
1608 norandmaps Don't use address space randomization. Equivalent to
1609 echo 0 > /proc/sys/kernel/randomize_va_space
1611 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1613 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1614 with UP alternatives
1616 noresidual [PPC] Don't use residual data on PReP machines.
1618 noresume [SWSUSP] Disables resume and restores original swap
1621 no-scroll [VGA] Disables scrollback.
1622 This is required for the Braillex ib80-piezo Braille
1623 reader made by F.H. Papenmeier (Germany).
1627 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1629 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1630 and disable the IO APIC. legacy for "maxcpus=0".
1632 nosoftlockup [KNL] Disable the soft-lockup detector.
1634 noswapaccount [KNL] Disable accounting of swap in memory resource
1635 controller. (See Documentation/cgroups/memory.txt)
1637 nosync [HW,M68K] Disables sync negotiation for all devices.
1639 notsc [BUGS=X86-32] Disable Time Stamp Counter
1641 nousb [USB] Disable the USB subsystem
1645 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1647 nptcg= [IA64] Override max number of concurrent global TLB
1648 purges which is reported from either PAL_VM_SUMMARY or
1651 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1653 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1654 one of ['zone', 'node', 'default'] can be specified
1655 This can be set from sysctl after boot.
1656 See Documentation/sysctl/vm.txt for details.
1658 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1659 See Documentation/debugging-via-ohci1394.txt for more
1662 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1663 Rather than timing out after 20 ms if an EC
1664 command is not properly ACKed, override the length
1665 of the timeout. We have interrupts disabled while
1666 waiting for the ACK, so if this is set too high
1667 interrupts *may* be lost!
1672 oprofile.timer= [HW]
1673 Use timer interrupt instead of performance counters
1675 oprofile.cpu_type= Force an oprofile cpu type
1676 This might be useful if you have an older oprofile
1677 userland or if you want common events.
1678 Format: { archperfmon }
1679 archperfmon: [X86] Force use of architectural
1680 perfmon on Intel CPUs instead of the
1681 CPU specific event set.
1683 osst= [HW,SCSI] SCSI Tape Driver
1684 Format: <buffer_size>,<write_threshold>
1685 See also Documentation/scsi/st.txt.
1687 panic= [KNL] Kernel behaviour on panic
1690 parkbd.port= [HW] Parallel port number the keyboard adapter is
1691 connected to, default is 0.
1693 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1694 0 for XT, 1 for AT (default is AT).
1697 parport= [HW,PPT] Specify parallel ports. 0 disables.
1698 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1699 Use 'auto' to force the driver to use any
1700 IRQ/DMA settings detected (the default is to
1701 ignore detected IRQ/DMA settings because of
1702 possible conflicts). You can specify the base
1703 address, IRQ, and DMA settings; IRQ and DMA
1704 should be numbers, or 'auto' (for using detected
1705 settings on that particular port), or 'nofifo'
1706 (to avoid using a FIFO even if it is detected).
1707 Parallel ports are assigned in the order they
1708 are specified on the command line, starting
1711 parport_init_mode= [HW,PPT]
1712 Configure VIA parallel port to operate in
1713 a specific mode. This is necessary on Pegasos
1714 computer where firmware has no options for setting
1715 up parallel port mode and sets it to spp.
1716 Currently this function knows 686a and 8231 chips.
1717 Format: [spp|ps2|epp|ecp|ecpepp]
1719 pas2= [HW,OSS] Format:
1720 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1723 See header of drivers/scsi/pas16.c.
1726 Halt all CPUs after the first oops has been printed for
1727 the specified number of seconds. This is to be used if
1728 your oopses keep scrolling off the screen.
1733 See header of drivers/block/paride/pcd.c.
1734 See also Documentation/blockdev/paride.txt.
1736 pci=option[,option...] [PCI] various PCI subsystem options:
1737 earlydump [X86] dump PCI config space before the kernel
1739 off [X86] don't probe for the PCI bus
1740 bios [X86-32] force use of PCI BIOS, don't access
1741 the hardware directly. Use this if your machine
1742 has a non-standard PCI host bridge.
1743 nobios [X86-32] disallow use of PCI BIOS, only direct
1744 hardware access methods are allowed. Use this
1745 if you experience crashes upon bootup and you
1746 suspect they are caused by the BIOS.
1747 conf1 [X86] Force use of PCI Configuration
1749 conf2 [X86] Force use of PCI Configuration
1751 noaer [PCIE] If the PCIEAER kernel config parameter is
1752 enabled, this kernel boot option can be used to
1753 disable the use of PCIE advanced error reporting.
1754 nodomains [PCI] Disable support for multiple PCI
1755 root domains (aka PCI segments, in ACPI-speak).
1756 nommconf [X86] Disable use of MMCONFIG for PCI
1758 nomsi [MSI] If the PCI_MSI kernel config parameter is
1759 enabled, this kernel boot option can be used to
1760 disable the use of MSI interrupts system-wide.
1761 noioapicquirk [APIC] Disable all boot interrupt quirks.
1762 Safety option to keep boot IRQs enabled. This
1763 should never be necessary.
1764 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1765 primary IO-APIC for bridges that cannot disable
1766 boot IRQs. This fixes a source of spurious IRQs
1767 when the system masks IRQs.
1768 noioapicreroute [APIC] Disable workaround that uses the
1769 boot IRQ equivalent of an IRQ that connects to
1770 a chipset where boot IRQs cannot be disabled.
1771 The opposite of ioapicreroute.
1772 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1773 routing table. These calls are known to be buggy
1774 on several machines and they hang the machine
1775 when used, but on other computers it's the only
1776 way to get the interrupt routing table. Try
1777 this option if the kernel is unable to allocate
1778 IRQs or discover secondary PCI buses on your
1780 rom [X86] Assign address space to expansion ROMs.
1781 Use with caution as certain devices share
1782 address decoders between ROMs and other
1784 norom [X86] Do not assign address space to
1785 expansion ROMs that do not already have
1786 BIOS assigned address ranges.
1787 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1788 assigned automatically to PCI devices. You can
1789 make the kernel exclude IRQs of your ISA cards
1791 pirqaddr=0xAAAAA [X86] Specify the physical address
1792 of the PIRQ table (normally generated
1793 by the BIOS) if it is outside the
1794 F0000h-100000h range.
1795 lastbus=N [X86] Scan all buses thru bus #N. Can be
1796 useful if the kernel is unable to find your
1797 secondary buses and you want to tell it
1798 explicitly which ones they are.
1799 assign-busses [X86] Always assign all PCI bus
1800 numbers ourselves, overriding
1801 whatever the firmware may have done.
1802 usepirqmask [X86] Honor the possible IRQ mask stored
1803 in the BIOS $PIR table. This is needed on
1804 some systems with broken BIOSes, notably
1805 some HP Pavilion N5400 and Omnibook XE3
1806 notebooks. This will have no effect if ACPI
1807 IRQ routing is enabled.
1808 noacpi [X86] Do not use ACPI for IRQ routing
1809 or for PCI scanning.
1810 use_crs [X86] Use _CRS for PCI resource
1812 routeirq Do IRQ routing for all PCI devices.
1813 This is normally done in pci_enable_device(),
1814 so this option is a temporary workaround
1815 for broken drivers that don't call it.
1816 skip_isa_align [X86] do not align io start addr, so can
1817 handle more pci cards
1818 firmware [ARM] Do not re-enumerate the bus but instead
1819 just use the configuration from the
1820 bootloader. This is currently used on
1821 IXP2000 systems where the bus has to be
1822 configured a certain way for adjunct CPUs.
1823 noearly [X86] Don't do any early type 1 scanning.
1824 This might help on some broken boards which
1825 machine check when some devices' config space
1826 is read. But various workarounds are disabled
1827 and some IOMMU drivers will not work.
1828 bfsort Sort PCI devices into breadth-first order.
1829 This sorting is done to get a device
1830 order compatible with older (<= 2.4) kernels.
1831 nobfsort Don't sort PCI devices into breadth-first order.
1832 cbiosize=nn[KMG] The fixed amount of bus space which is
1833 reserved for the CardBus bridge's IO window.
1834 The default value is 256 bytes.
1835 cbmemsize=nn[KMG] The fixed amount of bus space which is
1836 reserved for the CardBus bridge's memory
1837 window. The default value is 64 megabytes.
1840 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1841 Specifies alignment and device to reassign
1842 aligned memory resources.
1843 If <order of align> is not specified,
1844 PAGE_SIZE is used as alignment.
1845 PCI-PCI bridge can be specified, if resource
1846 windows need to be expanded.
1848 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1851 force Enable ASPM even on devices that claim not to support it.
1852 WARNING: Forcing ASPM on may cause system lockups.
1854 pcmv= [HW,PCMCIA] BadgePAD 4
1857 See Documentation/blockdev/paride.txt.
1859 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1862 See arch/parisc/kernel/pdc_chassis.c
1865 See Documentation/blockdev/paride.txt.
1868 See Documentation/blockdev/paride.txt.
1870 pirq= [SMP,APIC] Manual mp-table setup
1871 See Documentation/x86/i386/IO-APIC.txt.
1873 plip= [PPT,NET] Parallel port network link
1874 Format: { parport<nr> | timid | 0 }
1875 See also Documentation/parport.txt.
1877 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1878 Override pmtimer IOPort with a hex value.
1882 Enable PNP debug messages. This depends on the
1883 CONFIG_PNP_DEBUG_MESSAGES option.
1889 { on | off | curr | res | no-curr | no-res }
1892 [ISAPNP] Exclude IRQs for the autoconfiguration
1895 [ISAPNP] Exclude DMAs for the autoconfiguration
1897 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1898 Ranges are in pairs (I/O port base and size).
1901 [ISAPNP] Exclude memory regions for the
1903 Ranges are in pairs (memory base and size).
1905 ports= [IP_VS_FTP] IPVS ftp helper module
1907 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1909 Format: <port>,<port>....
1911 print-fatal-signals=
1912 [KNL] debug: print fatal signals
1913 print-fatal-signals=1: print segfault info to
1917 printk.time= Show timing data prefixed to each printk message line
1918 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1920 processor.max_cstate= [HW,ACPI]
1921 Limit processor to maximum C-state
1922 max_cstate=9 overrides any DMI blacklist limit.
1924 processor.nocst [HW,ACPI]
1925 Ignore the _CST method to determine C-states,
1926 instead using the legacy FADT method
1928 profile= [KNL] Enable kernel profiling via /proc/profile
1929 Format: [schedule,]<number>
1930 Param: "schedule" - profile schedule points.
1931 Param: <number> - step/bucket size as a power of 2 for
1932 statistical time based profiling.
1933 Param: "sleep" - profile D-state sleeping (millisecs).
1934 Requires CONFIG_SCHEDSTATS
1935 Param: "kvm" - profile VM exits.
1937 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1939 See Documentation/blockdev/ramdisk.txt.
1941 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1942 probe for; one of (bare|imps|exps|lifebook|any).
1943 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1945 psmouse.resetafter= [HW,MOUSE]
1946 Try to reset the device after so many bad packets
1949 [HW,MOUSE] Set desired mouse resolution, in dpi.
1950 psmouse.smartscroll=
1951 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1952 0 = disabled, 1 = enabled (default).
1954 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1956 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1959 See Documentation/blockdev/paride.txt.
1962 [KNL] Number of legacy pty's. Overwrites compiled-in
1965 quiet [KNL] Disable most log messages
1970 See Documentation/md.txt.
1972 ramdisk_blocksize= [RAM]
1973 See Documentation/blockdev/ramdisk.txt.
1975 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1976 See Documentation/blockdev/ramdisk.txt.
1978 rcupdate.blimit= [KNL,BOOT]
1979 Set maximum number of finished RCU callbacks to process
1982 rcupdate.qhimark= [KNL,BOOT]
1983 Set threshold of queued
1984 RCU callbacks over which batch limiting is disabled.
1986 rcupdate.qlowmark= [KNL,BOOT]
1987 Set threshold of queued RCU callbacks below which
1988 batch limiting is re-enabled.
1992 Run specified binary instead of /init from the ramdisk,
1993 used for early userspace startup. See initrd.
1995 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1996 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1997 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2000 [KNL, SMP] Set scheduler's default relax_domain_level.
2001 See Documentation/cgroups/cpusets.txt.
2003 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2005 reservetop= [X86-32]
2007 Reserves a hole at the top of the kernel virtual
2010 reset_devices [KNL] Force drivers to reset the underlying device
2011 during initialization.
2014 Specify the partition device for software suspend
2016 resume_offset= [SWSUSP]
2017 Specify the offset from the beginning of the partition
2018 given by "resume=" at which the swap header is located,
2019 in <PAGE_SIZE> units (needed only for swap files).
2020 See Documentation/power/swsusp-and-swap-files.txt
2022 retain_initrd [RAM] Keep initrd memory after extraction
2024 rhash_entries= [KNL,NET]
2025 Set number of hash buckets for route cache
2027 riscom8= [HW,SERIAL]
2028 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2030 ro [KNL] Mount root device read-only on boot
2032 root= [KNL] Root filesystem
2034 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2035 mount the root filesystem
2037 rootflags= [KNL] Set root filesystem mount option string
2039 rootfstype= [KNL] Set root filesystem type
2041 rootwait [KNL] Wait (indefinitely) for root device to show up.
2042 Useful for devices that are detected asynchronously
2043 (e.g. USB and MMC devices).
2045 root_plug.vendor_id=
2046 [ROOTPLUG] Override the default vendor ID
2048 root_plug.product_id=
2049 [ROOTPLUG] Override the default product ID
2052 [ROOTPLUG] Enable debugging output
2054 rw [KNL] Mount root device read-write on boot
2056 S [KNL] Run init in single mode
2059 See drivers/net/irda/sa1100_ir.c.
2061 sbni= [NET] Granch SBNI12 leased line adapter
2063 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2064 Format: <io>[,<timeout>[,<isapnp>]]
2066 scsi_debug_*= [SCSI]
2067 See drivers/scsi/scsi_debug.c.
2069 scsi_default_dev_flags=
2070 [SCSI] SCSI default device flags
2073 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2074 Format: <vendor>:<model>:<flags>
2075 (flags are integer value)
2077 scsi_logging_level= [SCSI] a bit mask of logging levels
2078 See drivers/scsi/scsi_logging.h for bits. Also
2079 settable via sysctl at dev.scsi.logging_level
2080 (/proc/sys/dev/scsi/logging_level).
2081 There is also a nice 'scsi_logging_level' script in the
2082 S390-tools package, available for download at
2083 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2085 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2086 discovered. async scans them in kernel threads,
2087 allowing boot to proceed. none ignores them, expecting
2088 user space to do the scan.
2090 security= [SECURITY] Choose a security module to enable at boot.
2091 If this boot parameter is not specified, only the first
2092 security module asking for security registration will be
2093 loaded. An invalid security module name will be treated
2094 as if no module has been chosen.
2096 selinux= [SELINUX] Disable or enable SELinux at boot time.
2097 Format: { "0" | "1" }
2098 See security/selinux/Kconfig help text.
2101 Default value is set via kernel config option.
2102 If enabled at boot time, /selinux/disable can be used
2103 later to disable prior to initial policy load.
2105 serialnumber [BUGS=X86-32]
2108 Maximal number of shapers.
2110 show_msr= [x86] show boot-time MSR settings
2111 Format: { <integer> }
2112 Show boot-time (BIOS-initialized) MSR settings.
2113 The parameter means the number of CPUs to show,
2114 for example 1 means boot CPU only.
2117 See header of drivers/scsi/sim710.c.
2124 slub_debug[=options[,slabs]] [MM, SLUB]
2125 Enabling slub_debug allows one to determine the
2126 culprit if slab objects become corrupted. Enabling
2127 slub_debug can create guard zones around objects and
2128 may poison objects when not in use. Also tracks the
2129 last alloc / free. For more information see
2130 Documentation/vm/slub.txt.
2132 slub_max_order= [MM, SLUB]
2133 Determines the maximum allowed order for slabs.
2134 A high setting may cause OOMs due to memory
2135 fragmentation. For more information see
2136 Documentation/vm/slub.txt.
2138 slub_min_objects= [MM, SLUB]
2139 The minimum number of objects per slab. SLUB will
2140 increase the slab order up to slub_max_order to
2141 generate a sufficiently large slab able to contain
2142 the number of objects indicated. The higher the number
2143 of objects the smaller the overhead of tracking slabs
2144 and the less frequently locks need to be acquired.
2145 For more information see Documentation/vm/slub.txt.
2147 slub_min_order= [MM, SLUB]
2148 Determines the mininum page order for slabs. Must be
2149 lower than slub_max_order.
2150 For more information see Documentation/vm/slub.txt.
2152 slub_nomerge [MM, SLUB]
2153 Disable merging of slabs with similar size. May be
2154 necessary if there is some reason to distinguish
2155 allocs to different slabs. Debug options disable
2156 merging on their own.
2157 For more information see Documentation/vm/slub.txt.
2160 Format: <io1>[,<io2>[,...,<io8>]]
2162 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2163 attempt to substitute SMP alternatives once at boot.
2165 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2166 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2167 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2168 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2169 smsc-ircc2.ircc_irq= [HW] IRQ line
2170 smsc-ircc2.ircc_dma= [HW] DMA channel
2171 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2172 0: Toshiba Satellite 1800 (GP data pin select)
2173 1: Fast pin select (default)
2176 snd-ad1816a= [HW,ALSA]
2178 snd-ad1848= [HW,ALSA]
2180 snd-ali5451= [HW,ALSA]
2182 snd-als100= [HW,ALSA]
2184 snd-als4000= [HW,ALSA]
2186 snd-azt2320= [HW,ALSA]
2188 snd-cmi8330= [HW,ALSA]
2190 snd-cmipci= [HW,ALSA]
2192 snd-cs4231= [HW,ALSA]
2194 snd-cs4232= [HW,ALSA]
2196 snd-cs4236= [HW,ALSA]
2198 snd-cs4281= [HW,ALSA]
2200 snd-cs46xx= [HW,ALSA]
2202 snd-dt019x= [HW,ALSA]
2204 snd-dummy= [HW,ALSA]
2206 snd-emu10k1= [HW,ALSA]
2208 snd-ens1370= [HW,ALSA]
2210 snd-ens1371= [HW,ALSA]
2212 snd-es968= [HW,ALSA]
2214 snd-es1688= [HW,ALSA]
2216 snd-es18xx= [HW,ALSA]
2218 snd-es1938= [HW,ALSA]
2220 snd-es1968= [HW,ALSA]
2222 snd-fm801= [HW,ALSA]
2224 snd-gusclassic= [HW,ALSA]
2226 snd-gusextreme= [HW,ALSA]
2228 snd-gusmax= [HW,ALSA]
2232 snd-ice1712= [HW,ALSA]
2234 snd-intel8x0= [HW,ALSA]
2236 snd-interwave= [HW,ALSA]
2241 snd-korg1212= [HW,ALSA]
2243 snd-maestro3= [HW,ALSA]
2245 snd-mpu401= [HW,ALSA]
2247 snd-mtpav= [HW,ALSA]
2249 snd-nm256= [HW,ALSA]
2251 snd-opl3sa2= [HW,ALSA]
2259 snd-opti93x= [HW,ALSA]
2263 snd-rme32= [HW,ALSA]
2265 snd-rme96= [HW,ALSA]
2267 snd-rme9652= [HW,ALSA]
2273 snd-sbawe= [HW,ALSA]
2275 snd-serial= [HW,ALSA]
2277 snd-sgalaxy= [HW,ALSA]
2279 snd-sonicvibes= [HW,ALSA]
2284 snd-sun-cs4231= [HW,ALSA]
2286 snd-trident= [HW,ALSA]
2288 snd-usb-audio= [HW,ALSA,USB]
2290 snd-via82xx= [HW,ALSA]
2292 snd-virmidi= [HW,ALSA]
2294 snd-wavefront= [HW,ALSA]
2296 snd-ymfpci= [HW,ALSA]
2299 [KNL] Should the soft-lockup detector generate panics.
2301 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2302 See Documentation/sonypi.txt
2304 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2305 See Documentation/serial/specialix.txt.
2307 spia_io_base= [HW,MTD]
2313 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2315 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2316 See Documentation/scsi/st.txt.
2319 Enabled the stack tracer on boot up.
2323 Set the STI (builtin display/keyboard on the HP-PARISC
2324 machines) console (graphic card) which should be used
2325 as the initial boot-console.
2326 See also comment in drivers/video/console/sticore.c.
2329 See comment in drivers/video/console/sticore.c.
2332 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2336 Control how the NFS server code allocates CPUs to
2337 service thread pools. Depending on how many NICs
2338 you have and where their interrupts are bound, this
2339 option will affect which CPUs will do NFS serving.
2340 Note: this parameter cannot be changed while the
2341 NFS server is running.
2343 auto the server chooses an appropriate mode
2344 automatically using heuristics
2345 global a single global pool contains all CPUs
2346 percpu one pool for each CPU
2347 pernode one pool for each NUMA node (equivalent
2348 to global on non-NUMA machines)
2350 swiotlb= [IA-64] Number of I/O TLB slabs
2354 sym53c416= [HW,SCSI]
2355 See header of drivers/scsi/sym53c416.c.
2357 sysrq_always_enabled
2359 Ignore sysrq setting - this boot parameter will
2360 neutralize any effect of /proc/sys/kernel/sysrq.
2361 Useful for debugging.
2364 See header of drivers/scsi/t128.c.
2368 test_suspend= [SUSPEND]
2369 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2370 standby suspend) as the system sleep state to briefly
2371 enter during system startup. The system is woken from
2372 this state using a wakeup-capable RTC alarm.
2374 thash_entries= [KNL,NET]
2375 Set number of hash buckets for TCP connection
2377 thermal.act= [HW,ACPI]
2378 -1: disable all active trip points in all thermal zones
2379 <degrees C>: override all lowest active trip points
2381 thermal.crt= [HW,ACPI]
2382 -1: disable all critical trip points in all thermal zones
2383 <degrees C>: override all critical trip points
2385 thermal.nocrt= [HW,ACPI]
2386 Set to disable actions on ACPI thermal zone
2387 critical and hot trip points.
2389 thermal.off= [HW,ACPI]
2390 1: disable ACPI thermal control
2392 thermal.psv= [HW,ACPI]
2393 -1: disable all passive trip points
2394 <degrees C>: override all passive trip points to this
2397 thermal.tzp= [HW,ACPI]
2398 Specify global default ACPI thermal zone polling rate
2399 <deci-seconds>: poll all this frequency
2400 0: no polling (default)
2403 See comment before function dc390_setup() in
2404 drivers/scsi/tmscsim.c.
2408 Specify if the kernel should make use of the cpu
2409 topology informations if the hardware supports these.
2410 The scheduler will make use of these informations and
2411 e.g. base its process migration decisions on it.
2416 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2418 trix= [HW,OSS] MediaTrix AudioTrix Pro
2420 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2422 tsc= Disable clocksource-must-verify flag for TSC.
2424 [x86] reliable: mark tsc clocksource as reliable, this
2425 disables clocksource verification at runtime.
2426 Used to enable high-resolution timer mode on older
2427 hardware, and in virtualized environment.
2429 turbografx.map[2|3]= [HW,JOY]
2430 TurboGraFX parallel port interface
2432 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2433 See also Documentation/input/joystick-parport.txt
2435 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2436 See header of drivers/scsi/u14-34f.c.
2445 [USB] Ignore overcurrent events (default N).
2446 Some badly-designed motherboards generate lots of
2447 bogus events, for ports that aren't wired to
2448 anything. Set this parameter to avoid log spamming.
2449 Note that genuine overcurrent events won't be
2454 Set unknown_nmi_panic=1 early on boot.
2456 usbcore.autosuspend=
2457 [USB] The autosuspend time delay (in seconds) used
2458 for newly-detected USB devices (default 2). This
2459 is the time required before an idle device will be
2460 autosuspended. Devices for which the delay is set
2461 to a negative value won't be autosuspended at all.
2463 usbcore.usbfs_snoop=
2464 [USB] Set to log all usbfs traffic (default 0 = off).
2466 usbcore.blinkenlights=
2467 [USB] Set to cycle leds on hubs (default 0 = off).
2469 usbcore.old_scheme_first=
2470 [USB] Start with the old device initialization
2471 scheme (default 0 = off).
2473 usbcore.use_both_schemes=
2474 [USB] Try the other device initialization scheme
2475 if the first one fails (default 1 = enabled).
2477 usbcore.initial_descriptor_timeout=
2478 [USB] Specifies timeout for the initial 64-byte
2479 USB_REQ_GET_DESCRIPTOR request in milliseconds
2480 (default 5000 = 5.0 seconds).
2483 [USBHID] The interval which mice are to be polled at.
2485 usb-storage.delay_use=
2486 [UMS] The delay in seconds before a new device is
2487 scanned for Logical Units (default 5).
2490 [UMS] A list of quirks entries to supplement or
2491 override the built-in unusual_devs list. List
2492 entries are separated by commas. Each entry has
2493 the form VID:PID:Flags where VID and PID are Vendor
2494 and Product ID values (4-digit hex numbers) and
2495 Flags is a set of characters, each corresponding
2496 to a common usb-storage quirk flag as follows:
2497 a = SANE_SENSE (collect more than 18 bytes
2499 c = FIX_CAPACITY (decrease the reported
2500 device capacity by one sector);
2501 h = CAPACITY_HEURISTICS (decrease the
2502 reported device capacity by one
2503 sector if the number is odd);
2504 i = IGNORE_DEVICE (don't bind to this
2506 l = NOT_LOCKABLE (don't try to lock and
2507 unlock ejectable media);
2508 m = MAX_SECTORS_64 (don't transfer more
2509 than 64 sectors = 32 KB at a time);
2510 o = CAPACITY_OK (accept the capacity
2511 reported by the device);
2512 r = IGNORE_RESIDUE (the device reports
2513 bogus residue values);
2514 s = SINGLE_LUN (the device has only one
2516 w = NO_WP_DETECT (don't test whether the
2517 medium is write-protected).
2518 Example: quirks=0419:aaf5:rl,0421:0433:rc
2521 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2522 vdso=1: enable VDSO (default)
2523 vdso=0: disable VDSO mapping
2526 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2527 vdso32=1: enable 32-bit VDSO (default)
2528 vdso32=0: disable 32-bit VDSO mapping
2531 vector=percpu: enable percpu vector domain
2533 video= [FB] Frame buffer configuration
2534 See Documentation/fb/modedb.txt.
2536 vga= [BOOT,X86-32] Select a particular video mode
2537 See Documentation/x86/boot.txt and
2538 Documentation/svga.txt.
2539 Use vga=ask for menu.
2540 This is actually a boot loader parameter; the value is
2541 passed to the kernel using a special protocol.
2543 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2544 size of <nn>. This can be used to increase the
2545 minimum size (128MB on x86). It can also be used to
2546 decrease the size and leave more room for directly
2549 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2552 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2555 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2558 vt.default_blu= [VT]
2559 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2560 Change the default blue palette of the console.
2561 This is a 16-member array composed of values
2564 vt.default_grn= [VT]
2565 Format: <green0>,<green1>,<green2>,...,<green15>
2566 Change the default green palette of the console.
2567 This is a 16-member array composed of values
2570 vt.default_red= [VT]
2571 Format: <red0>,<red1>,<red2>,...,<red15>
2572 Change the default red palette of the console.
2573 This is a 16-member array composed of values
2579 Set system-wide default UTF-8 mode for all tty's.
2580 Default is 1, i.e. UTF-8 mode is enabled for all
2581 newly opened terminals.
2583 waveartist= [HW,OSS]
2584 Format: <io>,<irq>,<dma>,<dma2>
2587 See header of drivers/scsi/wd33c93.c.
2590 See header of drivers/scsi/wd7000.c.
2593 See Documentation/watchdog/wdt.txt.
2595 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2596 default x2apic cluster mode on platforms
2599 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2600 xd_geo= See header of drivers/block/xd.c.
2602 xirc2ps_cs= [NET,PCMCIA]
2604 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2606 ______________________________________________________________________
2610 Add documentation for ALSA options.
2611 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob