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 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IMA Integrity measurement architecture is enabled.
48 IOSCHED More than one I/O scheduler is enabled.
49 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
50 ISAPNP ISA PnP code is enabled.
51 ISDN Appropriate ISDN support is enabled.
52 JOY Appropriate joystick support is enabled.
53 KMEMTRACE kmemtrace is enabled.
54 LIBATA Libata driver is enabled
55 LP Printer support is enabled.
56 LOOP Loopback device support is enabled.
57 M68k M68k architecture is enabled.
58 These options have more detailed description inside of
59 Documentation/m68k/kernel-options.txt.
60 MCA MCA bus support is enabled.
61 MDA MDA console support is enabled.
62 MOUSE Appropriate mouse support is enabled.
63 MSI Message Signaled Interrupts (PCI).
64 MTD MTD (Memory Technology Device) support is enabled.
65 NET Appropriate network support is enabled.
66 NUMA NUMA support is enabled.
67 GENERIC_TIME The generic timeofday code is enabled.
68 NFS Appropriate NFS support is enabled.
69 OSS OSS sound support is enabled.
70 PV_OPS A paravirtualized kernel is enabled.
71 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
72 PARISC The PA-RISC architecture is enabled.
73 PCI PCI bus support is enabled.
74 PCIE PCI Express support is enabled.
75 PCMCIA The PCMCIA subsystem is enabled.
76 PNP Plug & Play support is enabled.
77 PPC PowerPC architecture is enabled.
78 PPT Parallel port support is enabled.
79 PS2 Appropriate PS/2 support is enabled.
80 RAM RAM disk support is enabled.
81 ROOTPLUG The example Root Plug LSM is enabled.
82 S390 S390 architecture is enabled.
83 SCSI Appropriate SCSI support is enabled.
84 A lot of drivers has their options described inside of
86 SECURITY Different security models are enabled.
87 SELINUX SELinux support is enabled.
88 SERIAL Serial support is enabled.
89 SH SuperH architecture is enabled.
90 SMP The kernel is an SMP kernel.
91 SPARC Sparc architecture is enabled.
92 SWSUSP Software suspend (hibernation) is enabled.
93 SUSPEND System suspend states are enabled.
94 FTRACE Function tracing enabled.
95 TS Appropriate touchscreen support is enabled.
96 UMS USB Mass Storage support is enabled.
97 USB USB support is enabled.
98 USBHID USB Human Interface Device support is enabled.
99 V4L Video For Linux support is enabled.
100 VGA The VGA console has been enabled.
101 VT Virtual terminal support is enabled.
102 WDT Watchdog support is enabled.
103 XT IBM PC/XT MFM hard disk support is enabled.
104 X86-32 X86-32, aka i386 architecture is enabled.
105 X86-64 X86-64 architecture is enabled.
106 More X86-64 boot options can be found in
107 Documentation/x86/x86_64/boot-options.txt .
108 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
110 In addition, the following text indicates that the option:
112 BUGS= Relates to possible processor bugs on the said processor.
113 KNL Is a kernel start-up parameter.
114 BOOT Is a boot loader parameter.
116 Parameters denoted with BOOT are actually interpreted by the boot
117 loader, and have no meaning to the kernel directly.
118 Do not modify the syntax of boot loader parameters without extreme
119 need or coordination with <Documentation/x86/boot.txt>.
121 There are also arch-specific kernel-parameters not documented here.
122 See for example <Documentation/x86/x86_64/boot-options.txt>.
124 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
125 a trailing = on the name of any parameter states that that parameter will
126 be entered as an environment variable, whereas its absence indicates that
127 it will appear as a kernel argument readable via /proc/cmdline by programs
128 running once the system is up.
130 The number of kernel parameters is not limited, but the length of the
131 complete command line (parameters including spaces etc.) is limited to
132 a fixed number of characters. This limit depends on the architecture
133 and is between 256 and 4096 characters. It is defined in the file
134 ./include/asm/setup.h as COMMAND_LINE_SIZE.
137 acpi= [HW,ACPI,X86-64,i386]
138 Advanced Configuration and Power Interface
139 Format: { force | off | ht | strict | noirq | rsdt }
140 force -- enable ACPI if default was off
141 off -- disable ACPI if default was on
142 noirq -- do not use ACPI for IRQ routing
143 ht -- run only enough ACPI to enable Hyper Threading
144 strict -- Be less tolerant of platforms that are not
145 strictly ACPI specification compliant.
146 rsdt -- prefer RSDT over (default) XSDT
148 See also Documentation/power/pm.txt, pci=noacpi
150 acpi_apic_instance= [ACPI, IOAPIC]
152 2: use 2nd APIC table, if available
153 1,0: use 1st APIC table
156 acpi_sleep= [HW,ACPI] Sleep options
157 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
158 old_ordering, s4_nonvs }
159 See Documentation/power/video.txt for information on
161 s3_beep is for debugging; it makes the PC's speaker beep
162 as soon as the kernel's real-mode entry point is called.
163 s4_nohwsig prevents ACPI hardware signature from being
164 used during resume from hibernation.
165 old_ordering causes the ACPI 1.0 ordering of the _PTS
166 control method, with respect to putting devices into
167 low power states, to be enforced (the ACPI 2.0 ordering
168 of _PTS is used by default).
169 s4_nonvs prevents the kernel from saving/restoring the
170 ACPI NVS memory during hibernation.
172 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
173 Format: { level | edge | high | low }
175 acpi_irq_balance [HW,ACPI]
176 ACPI will balance active IRQs
179 acpi_irq_nobalance [HW,ACPI]
180 ACPI will not move active IRQs (default)
183 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
185 Format: <irq>,<irq>...
187 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
188 Format: <irq>,<irq>...
190 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
192 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
193 Format: To spoof as Windows 98: ="Microsoft Windows"
195 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
196 acpi_osi="string1" # add string1 -- only one string
197 acpi_osi="!string2" # remove built-in string2
198 acpi_osi= # disable all strings
200 acpi_serialize [HW,ACPI] force serialization of AML methods
202 acpi_skip_timer_override [HW,ACPI]
203 Recognize and ignore IRQ0/pin2 Interrupt Override.
204 For broken nForce2 BIOS resulting in XT-PIC timer.
205 acpi_use_timer_override [HW,ACPI]
206 Use timer override. For some broken Nvidia NF5 boards
207 that require a timer override, but don't have
210 acpi_backlight= [HW,ACPI]
211 acpi_backlight=vendor
213 If set to vendor, prefer vendor specific driver
214 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
215 of the ACPI video.ko driver.
217 acpi_display_output= [HW,ACPI]
218 acpi_display_output=vendor
219 acpi_display_output=video
222 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
223 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
225 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
226 debug output. Bits in debug_layer correspond to a
227 _COMPONENT in an ACPI source file, e.g.,
228 #define _COMPONENT ACPI_PCI_COMPONENT
229 Bits in debug_level correspond to a level in
230 ACPI_DEBUG_PRINT statements, e.g.,
231 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
232 The debug_level mask defaults to "info". See
233 Documentation/acpi/debug.txt for more information about
234 debug layers and levels.
236 Enable processor driver info messages:
237 acpi.debug_layer=0x20000000
238 Enable PCI/PCI interrupt routing info messages:
239 acpi.debug_layer=0x400000
240 Enable AML "Debug" output, i.e., stores to the Debug
241 object while interpreting AML:
242 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
243 Enable all messages related to ACPI hardware:
244 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
246 Some values produce so much output that the system is
247 unusable. The "log_buf_len" parameter may be useful
248 if you need to capture more output.
250 acpi.power_nocheck= [HW,ACPI]
251 Format: 1/0 enable/disable the check of power state.
252 On some bogus BIOS the _PSC object/_STA object of
253 power resource can't return the correct device power
254 state. In such case it is unneccessary to check its
255 power state again in power transition.
256 1 : disable the power state check
258 acpi_pm_good [X86-32,X86-64]
259 Override the pmtimer bug detection: force the kernel
260 to assume that this machine's pmtimer latches its value
261 and always returns good values.
264 { off | try_unsupported }
265 off: disable AGP support
266 try_unsupported: try to drive unsupported chipsets
267 (may crash computer or cause data corruption)
269 enable_timer_pin_1 [i386,x86-64]
270 Enable PIN 1 of APIC timer
271 Can be useful to work around chipset bugs
272 (in particular on some ATI chipsets).
273 The kernel tries to set a reasonable default.
275 disable_timer_pin_1 [i386,x86-64]
276 Disable PIN 1 of APIC timer
277 Can be useful to work around chipset bugs.
280 Format: <io>,<irq>,<dma>,<dma2>,<type>
283 See header of drivers/scsi/advansys.c.
285 advwdt= [HW,WDT] Advantech WDT
286 Format: <iostart>,<iostop>
288 aedsp16= [HW,OSS] Audio Excel DSP 16
289 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
290 See also header of sound/oss/aedsp16.c.
293 See Documentation/scsi/aha152x.txt.
296 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
299 See Documentation/scsi/aic7xxx.txt.
302 See Documentation/scsi/aic79xx.txt.
304 amd_iommu= [HW,X86-84]
305 Pass parameters to the AMD IOMMU driver in the system.
307 isolate - enable device isolation (each device, as far
308 as possible, will get its own protection
310 share - put every device behind one IOMMU into the
311 same protection domain
312 fullflush - enable flushing of IO/TLB entries when
313 they are unmapped. Otherwise they are
314 flushed before they will be reused, which
317 amd_iommu_size= [HW,X86-64]
318 Define the size of the aperture for the AMD IOMMU
319 driver. Possible values are:
320 '32M', '64M' (default), '128M', '256M', '512M', '1G'
322 amijoy.map= [HW,JOY] Amiga joystick support
323 Map of devices attached to JOY0DAT and JOY1DAT
325 See also Documentation/kernel/input/joystick.txt
327 analog.map= [HW,JOY] Analog joystick and gamepad support
328 Specifies type or capabilities of an analog joystick
329 connected to one of 16 gameports
330 Format: <type1>,<type2>,..<type16>
333 Power management functions (SPARCstation-4/5 + deriv.)
335 Disable APC CPU standby support. SPARCstation-Fox does
336 not play well with APC CPU idle - disable it if you have
337 APC and your system crashes randomly.
339 apic= [APIC,i386] Advanced Programmable Interrupt Controller
340 Change the output verbosity whilst booting
341 Format: { quiet (default) | verbose | debug }
342 Change the amount of debugging information output
343 when initialising the APIC and IO-APIC components.
345 apm= [APM] Advanced Power Management
346 See header of arch/x86/kernel/apm_32.c.
348 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
349 Format: <io>,<irq>,<nodeID>
353 atarimouse= [HW,MOUSE] Atari Mouse
355 atascsi= [HW,SCSI] Atari SCSI
357 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
358 EzKey and similar keyboards
360 atkbd.reset= [HW] Reset keyboard during initialization
362 atkbd.set= [HW] Select keyboard code set
363 Format: <int> (2 = AT (default), 3 = PS/2)
365 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
368 atkbd.softraw= [HW] Choose between synthetic and real raw mode
369 Format: <bool> (0 = real, 1 = synthetic (default))
371 atkbd.softrepeat= [HW]
372 Use software keyboard repeat
376 baycom_epp= [HW,AX25]
379 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
381 See header of drivers/net/hamradio/baycom_par.c.
383 baycom_ser_fdx= [HW,AX25]
384 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
385 Format: <io>,<irq>,<mode>[,<baud>]
386 See header of drivers/net/hamradio/baycom_ser_fdx.c.
388 baycom_ser_hdx= [HW,AX25]
389 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
390 Format: <io>,<irq>,<mode>
391 See header of drivers/net/hamradio/baycom_ser_hdx.c.
393 boot_delay= Milliseconds to delay each printk during boot.
394 Values larger than 10 seconds (10000) are changed to
398 bootmem_debug [KNL] Enable bootmem allocator debug messages.
400 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
401 bttv.radio= Most important insmod options are available as
403 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
404 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
407 See drivers/scsi/BusLogic.c, comment before function
408 BusLogic_ParseDriverOptions().
410 c101= [NET] Moxa C101 synchronous serial card
412 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
413 Sometimes CPU hardware bugs make them report the cache
414 size incorrectly. The kernel will attempt work arounds
415 to fix known problems, but for some CPUs it is not
416 possible to determine what the correct size should be.
417 This option provides an override for these situations.
419 security= [SECURITY] Choose a security module to enable at boot.
420 If this boot parameter is not specified, only the first
421 security module asking for security registration will be
422 loaded. An invalid security module name will be treated
423 as if no module has been chosen.
426 [SECURITY] Disable capabilities. This would normally
427 be used only if an alternative security model is to be
428 configured. Potentially dangerous and should only be
429 used if you are entirely sure of the consequences.
431 ccw_timeout_log [S390]
432 See Documentation/s390/CommonIO for details.
434 cgroup_disable= [KNL] Disable a particular controller
435 Format: {name of the controller(s) to disable}
436 {Currently supported controllers - "memory"}
438 checkreqprot [SELINUX] Set initial checkreqprot flag value.
439 Format: { "0" | "1" }
440 See security/selinux/Kconfig help text.
441 0 -- check protection applied by kernel (includes
442 any implied execute protection).
443 1 -- check protection requested by application.
444 Default value is set via a kernel config option.
445 Value can be changed at runtime via
446 /selinux/checkreqprot.
449 See Documentation/s390/CommonIO for details.
451 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
453 Forces specified clocksource (if available) to be used
454 when calculating gettimeofday(). If specified
455 clocksource is not available, it defaults to PIT.
456 Format: { pit | tsc | cyclone | pmtmr }
458 clocksource= [GENERIC_TIME] Override the default clocksource
460 Override the default clocksource and use the clocksource
461 with the name specified.
462 Some clocksource names to choose from, depending on
464 [all] jiffies (this is the base, fallback clocksource)
466 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
467 pxa_timer,timer3,32k_counter,timer0_1
469 [X86-32] pit,hpet,tsc,vmi-timer;
470 scx200_hrt on Geode; cyclone on IBM x440
478 clearcpuid=BITNUM [X86]
479 Disable CPUID feature X for the kernel. See
480 arch/x86/include/asm/cpufeature.h for the valid bit
481 numbers. Note the Linux specific bits are not necessarily
482 stable over kernel options, but the vendor specific
484 Also note that user programs calling CPUID directly
485 or using the feature without checking anything
486 will still see it. This just prevents it from
487 being used by the kernel or shown in /proc/cpuinfo.
488 Also note the kernel might malfunction if you disable
491 code_bytes [IA32/X86_64] How many bytes of object code to print
496 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
497 this option disables the debugging code at boot.
499 dma_debug_entries=<number>
500 This option allows to tune the number of preallocated
501 entries for DMA-API debugging code. One entry is
502 required per DMA-API allocation. Use this if the
503 DMA-API debugging code disables itself because the
504 architectural default is too low.
506 hpet= [X86-32,HPET] option to control HPET usage
507 Format: { enable (default) | disable | force |
509 disable: disable HPET and use PIT instead
510 force: allow force enabled of undocumented chips (ICH4,
512 verbose: show contents of HPET registers during setup
514 com20020= [HW,NET] ARCnet - COM20020 chipset
516 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
518 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
522 ARCnet - COM90xx chipset (memory-mapped buffers)
523 Format: <io>[,<irq>[,<memstart>]]
525 condev= [HW,S390] console device
528 console= [KNL] Output console device and options.
530 tty<n> Use the virtual console device <n>.
534 Use the specified serial port. The options are of
535 the form "bbbbpnf", where "bbbb" is the baud rate,
536 "p" is parity ("n", "o", or "e"), "n" is number of
537 bits, and "f" is flow control ("r" for RTS or
538 omit it). Default is "9600n8".
540 See Documentation/serial-console.txt for more
542 Documentation/networking/netconsole.txt for an
545 uart[8250],io,<addr>[,options]
546 uart[8250],mmio,<addr>[,options]
547 Start an early, polled-mode console on the 8250/16550
548 UART at the specified I/O port or MMIO address,
549 switching to the matching ttyS device later. The
550 options are the same as for ttyS, above.
552 If the device connected to the port is not a TTY but a braille
553 device, prepend "brl," before the device type, for instance
555 For now, only VisioBraille is supported.
557 earlycon= [KNL] Output early console device and options.
558 uart[8250],io,<addr>[,options]
559 uart[8250],mmio,<addr>[,options]
560 Start an early, polled-mode console on the 8250/16550
561 UART at the specified I/O port or MMIO address.
562 The options are the same as for ttyS, above.
565 [HW] Never suspend the console
566 Disable suspending of consoles during suspend and
567 hibernate operations. Once disabled, debugging
568 messages can reach various consoles while the rest
569 of the system is being put to sleep (ie, while
570 debugging driver suspend/resume hooks). This may
571 not work reliably with all consoles, but is known
572 to work with serial and VGA consoles.
575 [KNL] Change the default value for
576 /proc/<pid>/coredump_filter.
577 See also Documentation/filesystems/proc.txt.
579 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
581 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
583 crashkernel=nn[KMG]@ss[KMG]
584 [KNL] Reserve a chunk of physical memory to
585 hold a kernel to switch to with kexec on panic.
587 crashkernel=range1:size1[,range2:size2,...][@offset]
588 [KNL] Same as above, but depends on the memory
589 in the running system. The syntax of range is
590 start-[end] where start and end are both
591 a memory unit (amount[KMG]). See also
592 Documentation/kdump/kdump.txt for a example.
597 cs89x0_media= [HW,NET]
598 Format: { rj45 | aui | bnc }
601 See header of drivers/s390/block/dasd_devmap.c.
603 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
604 (one device per port)
605 Format: <port#>,<type>
606 See also Documentation/input/joystick-parport.txt
608 debug [KNL] Enable kernel debugging (events log level).
611 [KNL] verbose self-tests
613 Print debugging info while doing the locking API
615 We default to 0 (no extra messages), setting it to
616 1 will print _a lot_ more information - normally
617 only useful to kernel developers.
619 debug_objects [KNL] Enable object debugging
621 debugpat [X86] Enable PAT debugging
623 decnet.addr= [HW,NET]
624 Format: <area>[,<node>]
625 See also Documentation/networking/decnet.txt.
628 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
629 Change the default blue palette of the console.
630 This is a 16-member array composed of values
634 Format: <green0>,<green1>,<green2>,...,<green15>
635 Change the default green palette of the console.
636 This is a 16-member array composed of values
640 Format: <red0>,<red1>,<red2>,...,<red15>
641 Change the default red palette of the console.
642 This is a 16-member array composed of values
648 Set system-wide default UTF-8 mode for all tty's.
649 Default is 1, i.e. UTF-8 mode is enabled for all
650 newly opened terminals.
653 Set number of hash buckets for dentry cache.
656 IO parameters + enable/disable command.
658 digiepca= [HW,SERIAL]
659 See drivers/char/README.epca and
660 Documentation/serial/digiepca.txt.
662 disable_mtrr_cleanup [X86]
663 enable_mtrr_cleanup [X86]
664 The kernel tries to adjust MTRR layout from continuous
665 to discrete, to make X server driver able to add WB
666 entry later. This parameter enables/disables that.
668 mtrr_chunk_size=nn[KMG] [X86]
669 used for mtrr cleanup. It is largest continous chunk
670 that could hold holes aka. UC entries.
672 mtrr_gran_size=nn[KMG] [X86]
673 Used for mtrr cleanup. It is granularity of mtrr block.
675 Large value could prevent small alignment from
678 mtrr_spare_reg_nr=n [X86]
680 Range: 0,7 : spare reg number
682 Used for mtrr cleanup. It is spare mtrr entries number.
683 Set to 2 or more if your graphical card needs more.
685 disable_mtrr_trim [X86, Intel and AMD only]
686 By default the kernel will trim any uncacheable
687 memory out of your available memory pool based on
688 MTRR settings. This parameter disables that behavior,
689 possibly causing your machine to run very slowly.
691 dmasound= [HW,OSS] Sound subsystem buffers
697 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
699 earlyprintk=serial[,ttySn[,baudrate]]
702 Append ",keep" to not disable it when the real console
705 Only vga or serial or usb debug port at a time.
707 Currently only ttyS0 and ttyS1 are supported.
709 Interaction with the standard serial driver is not
712 The VGA output is eventually overwritten by the real
718 Format: {"off" | "on" | "skip[mbr]"}
720 eisa_irq_edge= [PARISC,HW]
721 See header of drivers/parisc/eisa.c.
724 See comment before function elanfreq_setup() in
725 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
728 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
729 See Documentation/block/as-iosched.txt and
730 Documentation/block/deadline-iosched.txt for details.
732 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
733 Specifies physical address of start of kernel core
734 image elf header. Generally kexec loader will
735 pass this option to capture kernel.
736 See Documentation/kdump/kdump.txt for details.
738 enforcing [SELINUX] Set initial enforcing status.
740 See security/selinux/Kconfig help text.
741 0 -- permissive (log only, no denials).
742 1 -- enforcing (deny and log).
744 Value can be changed at runtime via /selinux/enforce.
746 ether= [HW,NET] Ethernet cards parameters
747 This option is obsoleted by the "netdev=" option, which
748 has equivalent usage. See its documentation for details.
750 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
755 fail_make_request=[KNL]
756 General fault injection mechanism.
757 Format: <interval>,<probability>,<space>,<times>
758 See also /Documentation/fault-injection/.
761 See header of drivers/scsi/fd_mcs.c.
764 See header of drivers/scsi/fdomain.c.
767 See Documentation/blockdev/floppy.txt.
769 force_pal_cache_flush
770 [IA-64] Avoid check_sal_cache_flush which may hang on
771 buggy SAL_CACHE_FLUSH implementations. Using this
772 parameter will force ia64_sal_cache_flush to call
773 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
776 [ftrace] will set and start the specified tracer
777 as early as possible in order to facilitate early
781 [ftrace] will dump the trace buffers on oops.
784 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
785 support via parallel port (up to 5 devices per port)
786 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
787 See also Documentation/input/joystick-parport.txt
791 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
796 See header of drivers/scsi/gdth.c.
798 gpt [EFI] Forces disk with valid GPT signature but
799 invalid Protective MBR to be treated as GPT.
803 hashdist= [KNL,NUMA] Large hashes allocated during boot
804 are distributed across NUMA nodes. Defaults on
805 for IA-64, off otherwise.
806 Format: 0 | 1 (for off | on)
808 hcl= [IA-64] SGI's Hardware Graph compatibility layer
810 hd= [EIDE] (E)IDE hard drive subsystem geometry
811 Format: <cyl>,<head>,<sect>
813 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
814 size of <nn>. This works even on boxes that have no
815 highmem otherwise. This also works to reduce highmem
816 size on bigger boxes.
818 highres= [KNL] Enable/disable high resolution timer mode.
819 Valid parameters: "on", "off"
823 See Documentation/isdn/README.HiSax.
825 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
826 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
827 On x86-64 and powerpc, this option can be specified
828 multiple times interleaved with hugepages= to reserve
829 huge pages of different sizes. Valid pages sizes on
830 x86-64 are 2M (when the CPU supports "pse") and 1G
831 (when the CPU supports the "pdpe1gb" cpuinfo flag)
832 Note that 1GB pages can only be allocated at boot time
833 using hugepages= and not freed afterwards.
835 [same as hugepagesz=] The size of the default
836 HugeTLB page size. This is the size represented by
837 the legacy /proc/ hugepages APIs, used for SHM, and
838 default size when mounting hugetlbfs filesystems.
839 Defaults to the default architecture's huge page size
844 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
845 terminal devices. Valid values: 0..8
846 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
847 If specified, z/VM IUCV HVC accepts connections
848 from listed z/VM user IDs only.
850 i2c_bus= [HW] Override the default board specific I2C bus speed
851 or register an additional I2C bus that is not
852 registered from board initialization code.
856 i8042.debug [HW] Toggle i8042 debug mode
857 i8042.direct [HW] Put keyboard port into non-translated mode
858 i8042.dumbkbd [HW] Pretend that controller can only read data from
859 keyboard and cannot control its state
860 (Don't attempt to blink the leds)
861 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
862 i8042.nokbd [HW] Don't check/create keyboard port
863 i8042.noloop [HW] Disable the AUX Loopback command while probing
865 i8042.nomux [HW] Don't check presence of an active multiplexing
867 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
870 [HW] Frequency with which keyboard LEDs should blink
871 when kernel panics (default is 0.5 sec)
872 i8042.reset [HW] Reset the controller during init and cleanup
873 i8042.unlock [HW] Unlock (ignore) the keylock
877 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
878 indicates that the driver is running on unsupported
880 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
881 does not match list of supported models.
883 [HW] Report power status in /proc/i8k
884 (disabled by default)
885 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
888 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
889 See Documentation/mca.txt.
892 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
894 ide-core.nodma= [HW] (E)IDE subsystem
895 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
896 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
897 .chs .ignore_cable are additional options
898 See Documentation/ide/ide.txt.
900 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
901 See Documentation/ide/ide.txt.
904 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
905 Poll forces a polling idle loop that can slightly
906 improve the performance of waking up a idle CPU, but
907 will use a lot of power and make the system run hot.
909 idle=mwait: On systems which support MONITOR/MWAIT but
910 the kernel chose to not use it because it doesn't save
911 as much power as a normal idle loop, use the
912 MONITOR/MWAIT idle loop anyways. Performance should be
913 the same as idle=poll.
914 idle=halt: Halt is forced to be used for CPU idle.
915 In such case C2/C3 won't be used again.
916 idle=nomwait: Disable mwait for CPU C-states
918 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
919 Claim all unknown PCI IDE storage controllers.
921 ignore_loglevel [KNL]
922 Ignore loglevel setting - this will print /all/
923 kernel messages to the console. Useful for debugging.
926 Set number of hash buckets for inode cache.
929 Format: { "0" | "1" }
930 0 -- integrity auditing messages. (Default)
931 1 -- enable informational integrity auditing messages.
934 Formt: { "sha1" | "md5" }
938 See header of drivers/scsi/in2000.c.
942 Run specified binary instead of /sbin/init as init
945 initcall_debug [KNL] Trace initcalls as they are executed. Useful
946 for working out where the kernel is dying during
949 initrd= [BOOT] Specify the location of the initial ramdisk
951 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
956 iomem= Disable strict checking of access to MMIO memory
957 strict regions from userspace.
973 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
975 Enable intel iommu driver.
977 Disable intel iommu driver.
978 igfx_off [Default Off]
979 By default, gfx is mapped as normal device. If a gfx
980 device has a dedicated DMAR unit, the DMAR unit is
981 bypassed by not enabling DMAR with this option. In
982 this case, gfx device will use physical address for
985 With this option iommu will not optimize to look
986 for io virtual address below 32 bit forcing dual
987 address cycle on pci bus for cards supporting greater
988 than 32 bit addressing. The default is to look
989 for translation below 32 bit and if not available
990 then look in the higher range.
992 With this option on every unmap_single operation will
993 result in a hardware IOTLB flush operation as opposed
994 to batching them for performance.
996 io_delay= [X86-32,X86-64] I/O delay method
998 Standard port 0x80 based delay
1000 Alternate port 0xed based delay (needed on some systems)
1002 Simple two microseconds delay
1006 io7= [HW] IO7 for Marvel based alpha systems
1007 See comment before marvel_specify_io7 in
1008 arch/alpha/kernel/core_marvel.c.
1011 See Documentation/filesystems/nfsroot.txt.
1013 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1014 See comment before ip2_setup() in
1015 drivers/char/ip2/ip2base.c.
1017 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1018 See header of drivers/scsi/ips.c.
1020 ports= [IP_VS_FTP] IPVS ftp helper module
1022 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1024 Format: <port>,<port>....
1027 When an interrupt is not handled search all handlers
1028 for it. Intended to get systems with badly broken
1032 When an interrupt is not handled search all handlers
1033 for it. Also check all handlers each timer
1034 interrupt. Intended to get systems with badly broken
1038 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1040 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1042 <cpu number>,...,<cpu number>
1044 <cpu number>-<cpu number>
1045 (must be a positive range in ascending order)
1047 <cpu number>,...,<cpu number>-<cpu number>
1049 This option can be used to specify one or more CPUs
1050 to isolate from the general SMP balancing and scheduling
1051 algorithms. You can move a process onto or off an
1052 "isolated" CPU via the CPU affinity syscalls or cpuset.
1053 <cpu number> begins at 0 and the maximum value is
1054 "number of CPUs in system - 1".
1056 This option is the preferred way to isolate CPUs. The
1057 alternative -- manually setting the CPU mask of all
1058 tasks in the system -- can cause problems and
1059 suboptimal load balancer performance.
1063 js= [HW,JOY] Analog joystick
1064 See Documentation/input/joystick.txt.
1066 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1067 specifies the amount of memory usable by the kernel
1068 for non-movable allocations. The requested amount is
1069 spread evenly throughout all nodes in the system. The
1070 remaining memory in each node is used for Movable
1071 pages. In the event, a node is too small to have both
1072 kernelcore and Movable pages, kernelcore pages will
1073 take priority and other nodes will have a larger number
1074 of kernelcore pages. The Movable zone is used for the
1075 allocation of pages that may be reclaimed or moved
1076 by the page migration subsystem. This means that
1077 HugeTLB pages may not be allocated from this zone.
1078 Note that allocations like PTEs-from-HighMem still
1079 use the HighMem zone if it exists, and the Normal
1080 zone if it does not.
1082 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1083 Controls whether kmemtrace is enabled
1086 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1087 subbufs kmemtrace's relay channel has. Set this
1088 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1089 you experience buffer overruns.
1091 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1092 is similar to kernelcore except it specifies the
1093 amount of memory used for migratable allocations.
1094 If both kernelcore and movablecore is specified,
1095 then kernelcore will be at *least* the specified
1096 value but may be more. If movablecore on its own
1097 is specified, the administrator must be careful
1098 that the amount of memory usable for all allocations
1103 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1106 kgdboc= [HW] kgdb over consoles.
1107 Requires a tty driver that supports console polling.
1108 (only serial suported for now)
1109 Format: <serial_device>[,baud]
1111 kmac= [MIPS] korina ethernet MAC address.
1112 Configure the RouterBoard 532 series on-chip
1113 Ethernet adapter MAC address.
1119 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1122 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1125 libata.dma= [LIBATA] DMA control
1126 libata.dma=0 Disable all PATA and SATA DMA
1127 libata.dma=1 PATA and SATA Disk DMA only
1128 libata.dma=2 ATAPI (CDROM) DMA only
1129 libata.dma=4 Compact Flash DMA only
1130 Combinations also work, so libata.dma=3 enables DMA
1131 for disks and CDROMs, but not CFs.
1133 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1137 libata.force= [LIBATA] Force configurations. The format is comma
1138 separated list of "[ID:]VAL" where ID is
1139 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1140 matching port, link or device. Basically, it matches
1141 the ATA ID string printed on console by libata. If
1142 the whole ID part is omitted, the last PORT and DEVICE
1143 values are used. If ID hasn't been specified yet, the
1144 configuration applies to all ports, links and devices.
1146 If only DEVICE is omitted, the parameter applies to
1147 the port and all links and devices behind it. DEVICE
1148 number of 0 either selects the first device or the
1149 first fan-out link behind PMP device. It does not
1150 select the host link. DEVICE number of 15 selects the
1151 host link and device attached to it.
1153 The VAL specifies the configuration to force. As long
1154 as there's no ambiguity shortcut notation is allowed.
1155 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1156 The following configurations can be forced.
1158 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1159 Any ID with matching PORT is used.
1161 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1163 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1164 udma[/][16,25,33,44,66,100,133] notation is also
1167 * [no]ncq: Turn on or off NCQ.
1169 * nohrst, nosrst, norst: suppress hard, soft
1172 If there are multiple matching configurations changing
1173 the same attribute, the last one is used.
1175 lmb=debug [KNL] Enable lmb debug messages.
1177 load_ramdisk= [RAM] List of ramdisks to load from floppy
1178 See Documentation/blockdev/ramdisk.txt.
1180 lockd.nlm_grace_period=P [NFS] Assign grace period.
1183 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1186 lockd.nlm_timeout=T [NFS] Assign timeout value.
1189 lockd.nlm_udpport=M [NFS] Assign UDP port.
1192 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1195 loglevel= All Kernel Messages with a loglevel smaller than the
1196 console loglevel will be printed to the console. It can
1197 also be changed with klogd or other programs. The
1198 loglevels are defined as follows:
1200 0 (KERN_EMERG) system is unusable
1201 1 (KERN_ALERT) action must be taken immediately
1202 2 (KERN_CRIT) critical conditions
1203 3 (KERN_ERR) error conditions
1204 4 (KERN_WARNING) warning conditions
1205 5 (KERN_NOTICE) normal but significant condition
1206 6 (KERN_INFO) informational
1207 7 (KERN_DEBUG) debug-level messages
1209 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1210 Format: { n | nk | nM }
1211 n must be a power of two. The default size
1212 is set in the kernel config file.
1214 logo.nologo [FB] Disables display of the built-in Linux logo.
1215 This may be used to provide more screen space for
1216 kernel log messages and is useful when debugging
1217 kernel boot problems.
1219 lp=0 [LP] Specify parallel ports to use, e.g,
1220 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1221 lp=reset first parallel port). 'lp=0' disables the
1222 lp=auto printer driver. 'lp=reset' (which can be
1223 specified in addition to the ports) causes
1224 attached printers to be reset. Using
1225 lp=port1,port2,... specifies the parallel ports
1226 to associate lp devices with, starting with
1227 lp0. A port specification may be 'none' to skip
1228 that lp device, or a parport name such as
1229 'parport0'. Specifying 'lp=auto' instead of a
1230 port specification list means that device IDs
1231 from each port should be examined, to see if
1232 an IEEE 1284-compliant printer is attached; if
1233 so, the driver will manage that printer.
1234 See also header of drivers/char/lp.c.
1237 Sets loops_per_jiffy to given constant, thus avoiding
1238 time-consuming boot-time autodetection (up to 250 ms per
1239 CPU). 0 enables autodetection (default). To determine
1240 the correct value for your kernel, boot with normal
1241 autodetection and see what value is printed. Note that
1242 on SMP systems the preset will be applied to all CPUs,
1243 which is likely to cause problems if your CPUs need
1244 significantly divergent settings. An incorrect value
1245 will cause delays in the kernel to be wrong, leading to
1246 unpredictable I/O errors and other breakage. Although
1247 unlikely, in the extreme case this might damage your
1251 Format: <io>,<irq>,<dma>
1253 mac5380= [HW,SCSI] Format:
1254 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1256 machvec= [IA64] Force the use of a particular machine-vector
1257 (machvec) in a generic kernel.
1258 Example: machvec=hpzx1_swiotlb
1260 max_loop= [LOOP] Maximum number of loopback devices that can
1264 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1265 should make use of. maxcpus=n : n >= 0 limits the
1266 kernel to using 'n' processors. n=0 is a special case,
1267 it is equivalent to "nosmp", which also disables
1270 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1271 or equal to this physical address is ignored.
1273 max_luns= [SCSI] Maximum number of LUNs to probe.
1274 Should be between 1 and 2^32-1.
1277 [SCSI] Maximum number of LUNs received.
1278 Should be between 1 and 16384.
1282 mce [X86-32] Machine Check Exception
1284 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1286 md= [HW] RAID subsystems devices and level
1287 See Documentation/md.txt.
1290 Format: <first>,<last>
1291 Specifies range of consoles to be captured by the MDA.
1293 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1294 Amount of memory to be used when the kernel is not able
1295 to see the whole system memory or for test.
1296 [X86-32] Use together with memmap= to avoid physical
1297 address space collisions. Without memmap= PCI devices
1298 could be placed at addresses belonging to unused RAM.
1300 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1304 [KNL,SH] Allow user to override the default size for
1305 per-device physically contiguous DMA buffers.
1307 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1308 E820 memory map, as specified by the user.
1309 Such memmap=exactmap lines can be constructed based on
1310 BIOS output or other requirements. See the memmap=nn@ss
1313 memmap=nn[KMG]@ss[KMG]
1314 [KNL] Force usage of a specific region of memory
1315 Region of memory to be used, from ss to ss+nn.
1317 memmap=nn[KMG]#ss[KMG]
1318 [KNL,ACPI] Mark specific memory as ACPI data.
1319 Region of memory to be used, from ss to ss+nn.
1321 memmap=nn[KMG]$ss[KMG]
1322 [KNL,ACPI] Mark specific memory as reserved.
1323 Region of memory to be used, from ss to ss+nn.
1324 Example: Exclude memory from 0x18690000-0x1869ffff
1325 memmap=64K$0x18690000
1327 memmap=0x10000$0x18690000
1329 memory_corruption_check=0/1 [X86]
1330 Some BIOSes seem to corrupt the first 64k of
1331 memory when doing things like suspend/resume.
1332 Setting this option will scan the memory
1333 looking for corruption. Enabling this will
1334 both detect corruption and prevent the kernel
1335 from using the memory being corrupted.
1336 However, its intended as a diagnostic tool; if
1337 repeatable BIOS-originated corruption always
1338 affects the same memory, you can use memmap=
1339 to prevent the kernel from using that memory.
1341 memory_corruption_check_size=size [X86]
1342 By default it checks for corruption in the low
1343 64k, making this memory unavailable for normal
1344 use. Use this parameter to scan for
1345 corruption in more or less memory.
1347 memory_corruption_check_period=seconds [X86]
1348 By default it checks for corruption every 60
1349 seconds. Use this parameter to check at some
1350 other rate. 0 disables periodic checking.
1352 memtest= [KNL,X86] Enable memtest
1354 default : 0 <disable>
1355 Specifies the number of memtest passes to be
1356 performed. Each pass selects another test
1357 pattern from a given set of patterns. Memtest
1358 fills the memory with this pattern, validates
1359 memory contents and reserves bad memory
1360 regions that are detected.
1362 meye.*= [HW] Set MotionEye Camera parameters
1363 See Documentation/video4linux/meye.txt.
1365 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1366 Multi-Function General Purpose Timers on AMD Geode
1369 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1370 the BIOS has incorrectly applied a workaround. TinyBIOS
1371 version 0.98 is known to be affected, 0.99 fixes the
1372 problem by letting the user disable the workaround.
1376 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1377 physical address is ignored.
1380 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1381 parameter allows control of the logging verbosity for
1382 the additional memory initialisation checks. A value
1383 of 0 disables mminit logging and a level of 4 will
1384 log everything. Information is printed at KERN_DEBUG
1385 so loglevel=8 may also need to be specified.
1388 [MOUSE] Maximum time between finger touching and
1389 leaving touchpad surface for touch to be considered
1390 a tap and be reported as a left button click (for
1391 touchpads working in absolute mode only).
1393 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1394 reporting absolute coordinates, such as tablets
1395 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1396 reporting absolute coordinates, such as tablets
1401 MTD_Partition= [MTD]
1402 Format: <name>,<region-number>,<size>,<offset>
1404 MTD_Region= [MTD] Format:
1405 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1408 See drivers/mtd/cmdlinepart.c.
1411 ARM/S3C2412 JIVE boot control
1413 See arch/arm/mach-s3c2412/mach-jive.c
1415 mtouchusb.raw_coordinates=
1416 [HW] Make the MicroTouch USB driver use raw coordinates
1417 ('y', default) or cooked coordinates ('n')
1419 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1422 See header of drivers/scsi/NCR_D700.c.
1426 ncr53c400= [HW,SCSI]
1428 ncr53c400a= [HW,SCSI]
1430 ncr53c406a= [HW,SCSI]
1432 ncr53c8xx= [HW,SCSI]
1434 netdev= [NET] Network devices parameters
1435 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1436 Note that mem_start is often overloaded to mean
1437 something different and driver-specific.
1438 This usage is only documented in each driver source
1442 [NETFILTER] Enable connection tracking flow accounting
1443 0 to disable accounting
1444 1 to enable accounting
1445 Default value depends on CONFIG_NF_CT_ACCT that is
1446 going to be removed in 2.6.29.
1449 See Documentation/filesystems/nfsroot.txt.
1451 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1452 See Documentation/filesystems/nfsroot.txt.
1454 nfs.callback_tcpport=
1455 [NFS] set the TCP port on which the NFSv4 callback
1456 channel should listen.
1458 nfs.idmap_cache_timeout=
1459 [NFS] set the maximum lifetime for idmapper cache
1463 [NFS] enable 64-bit inode numbers.
1464 If zero, the NFS client will fake up a 32-bit inode
1465 number for the readdir() and stat() syscalls instead
1466 of returning the full 64-bit number.
1467 The default is to return 64-bit inode numbers.
1469 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1470 when a NMI is triggered.
1471 Format: [state][,regs][,debounce][,die]
1473 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1474 Format: [panic,][num]
1476 0 - turn nmi_watchdog off
1477 1 - use the IO-APIC timer for the NMI watchdog
1478 2 - use the local APIC for the NMI watchdog using
1479 a performance counter. Note: This will use one performance
1480 counter and the local APIC's performance vector.
1481 When panic is specified panic when an NMI watchdog timeout occurs.
1482 This is useful when you use a panic=... timeout and need the box
1484 Instead of 1 and 2 it is possible to use the following
1485 symbolic names: lapic and ioapic
1486 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1488 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1489 emulation library even if a 387 maths coprocessor
1492 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1493 caches in the slab allocator. Saves per-node memory,
1494 but will impact performance.
1498 noapic [SMP,APIC] Tells the kernel to not make use of any
1499 IOAPICs that may be present in the system.
1501 nobats [PPC] Do not use BATs for mapping kernel lowmem
1502 on "Classic" PPC cores.
1506 nodelayacct [KNL] Disable per-task delay accounting
1508 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1510 nodsp [SH] Disable hardware DSP at boot time.
1512 noefi [X86-32,X86-64] Disable EFI runtime services support.
1516 noexec [X86-32,X86-64]
1517 On X86-32 available only on PAE configured kernels.
1518 noexec=on: enable non-executable mappings (default)
1519 noexec=off: disable non-executable mappings
1522 This affects only 32-bit executables.
1523 noexec32=on: enable non-executable mappings (default)
1524 read doesn't imply executable mappings
1525 noexec32=off: disable non-executable mappings
1526 read implies executable mappings
1528 nofpu [SH] Disable hardware FPU at boot time.
1530 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1531 register save and restore. The kernel will only save
1532 legacy floating-point registers on task switch.
1534 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1538 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1539 instruction doesn't work correctly and not to
1542 no_file_caps Tells the kernel not to honor file capabilities. The
1543 only way then for a file to be executed with privilege
1544 is to be setuid root or executed by root.
1546 nohalt [IA-64] Tells the kernel not to use the power saving
1547 function PAL_HALT_LIGHT when idle. This increases
1548 power-consumption. On the positive side, it reduces
1549 interrupt wake-up latency, which may improve performance
1550 in certain environments such as networked servers or
1553 nohz= [KNL] Boottime enable/disable dynamic ticks
1554 Valid arguments: on, off
1557 noirqdebug [X86-32] Disables the code which attempts to detect and
1558 disable unhandled interrupt sources.
1560 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1561 broken timer IRQ sources.
1563 noisapnp [ISAPNP] Disables ISA PnP code.
1565 noinitrd [RAM] Tells the kernel not to load any configured
1570 nojitter [IA64] Disables jitter checking for ITC timers.
1572 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1574 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1576 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1578 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1579 default x2apic cluster mode on platforms
1582 noltlbs [PPC] Do not use large page/tlb entries for kernel
1583 lowmem mapping on PPC40x.
1585 nomca [IA-64] Disable machine check abort handling
1587 nomce [X86-32] Machine Check Exception
1589 nomfgpt [X86-32] Disable Multi-Function General Purpose
1590 Timer usage (for AMD Geode machines).
1592 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1594 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1595 with UP alternatives
1597 noresidual [PPC] Don't use residual data on PReP machines.
1599 noresume [SWSUSP] Disables resume and restores original swap
1602 no-scroll [VGA] Disables scrollback.
1603 This is required for the Braillex ib80-piezo Braille
1604 reader made by F.H. Papenmeier (Germany).
1608 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1610 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1611 and disable the IO APIC. legacy for "maxcpus=0".
1613 nosoftlockup [KNL] Disable the soft-lockup detector.
1615 noswapaccount [KNL] Disable accounting of swap in memory resource
1616 controller. (See Documentation/controllers/memory.txt)
1618 nosync [HW,M68K] Disables sync negotiation for all devices.
1620 notsc [BUGS=X86-32] Disable Time Stamp Counter
1622 nousb [USB] Disable the USB subsystem
1626 nptcg= [IA64] Override max number of concurrent global TLB
1627 purges which is reported from either PAL_VM_SUMMARY or
1630 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1631 one of ['zone', 'node', 'default'] can be specified
1632 This can be set from sysctl after boot.
1633 See Documentation/sysctl/vm.txt for details.
1635 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1637 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1638 See Documentation/debugging-via-ohci1394.txt for more
1641 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1642 Rather than timing out after 20 ms if an EC
1643 command is not properly ACKed, override the length
1644 of the timeout. We have interrupts disabled while
1645 waiting for the ACK, so if this is set too high
1646 interrupts *may* be lost!
1651 oprofile.timer= [HW]
1652 Use timer interrupt instead of performance counters
1654 osst= [HW,SCSI] SCSI Tape Driver
1655 Format: <buffer_size>,<write_threshold>
1656 See also Documentation/scsi/st.txt.
1658 panic= [KNL] Kernel behaviour on panic
1661 parkbd.port= [HW] Parallel port number the keyboard adapter is
1662 connected to, default is 0.
1664 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1665 0 for XT, 1 for AT (default is AT).
1668 parport= [HW,PPT] Specify parallel ports. 0 disables.
1669 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1670 Use 'auto' to force the driver to use any
1671 IRQ/DMA settings detected (the default is to
1672 ignore detected IRQ/DMA settings because of
1673 possible conflicts). You can specify the base
1674 address, IRQ, and DMA settings; IRQ and DMA
1675 should be numbers, or 'auto' (for using detected
1676 settings on that particular port), or 'nofifo'
1677 (to avoid using a FIFO even if it is detected).
1678 Parallel ports are assigned in the order they
1679 are specified on the command line, starting
1682 parport_init_mode= [HW,PPT]
1683 Configure VIA parallel port to operate in
1684 a specific mode. This is necessary on Pegasos
1685 computer where firmware has no options for setting
1686 up parallel port mode and sets it to spp.
1687 Currently this function knows 686a and 8231 chips.
1688 Format: [spp|ps2|epp|ecp|ecpepp]
1690 pas2= [HW,OSS] Format:
1691 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1694 See header of drivers/scsi/pas16.c.
1697 Halt all CPUs after the first oops has been printed for
1698 the specified number of seconds. This is to be used if
1699 your oopses keep scrolling off the screen.
1704 See header of drivers/block/paride/pcd.c.
1705 See also Documentation/blockdev/paride.txt.
1707 pci=option[,option...] [PCI] various PCI subsystem options:
1708 earlydump [X86] dump PCI config space before the kernel
1710 off [X86] don't probe for the PCI bus
1711 bios [X86-32] force use of PCI BIOS, don't access
1712 the hardware directly. Use this if your machine
1713 has a non-standard PCI host bridge.
1714 nobios [X86-32] disallow use of PCI BIOS, only direct
1715 hardware access methods are allowed. Use this
1716 if you experience crashes upon bootup and you
1717 suspect they are caused by the BIOS.
1718 conf1 [X86] Force use of PCI Configuration
1720 conf2 [X86] Force use of PCI Configuration
1722 noaer [PCIE] If the PCIEAER kernel config parameter is
1723 enabled, this kernel boot option can be used to
1724 disable the use of PCIE advanced error reporting.
1725 nodomains [PCI] Disable support for multiple PCI
1726 root domains (aka PCI segments, in ACPI-speak).
1727 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1729 nomsi [MSI] If the PCI_MSI kernel config parameter is
1730 enabled, this kernel boot option can be used to
1731 disable the use of MSI interrupts system-wide.
1732 noioapicquirk [APIC] Disable all boot interrupt quirks.
1733 Safety option to keep boot IRQs enabled. This
1734 should never be necessary.
1735 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1736 primary IO-APIC for bridges that cannot disable
1737 boot IRQs. This fixes a source of spurious IRQs
1738 when the system masks IRQs.
1739 noioapicreroute [APIC] Disable workaround that uses the
1740 boot IRQ equivalent of an IRQ that connects to
1741 a chipset where boot IRQs cannot be disabled.
1742 The opposite of ioapicreroute.
1743 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1744 routing table. These calls are known to be buggy
1745 on several machines and they hang the machine
1746 when used, but on other computers it's the only
1747 way to get the interrupt routing table. Try
1748 this option if the kernel is unable to allocate
1749 IRQs or discover secondary PCI buses on your
1751 rom [X86] Assign address space to expansion ROMs.
1752 Use with caution as certain devices share
1753 address decoders between ROMs and other
1755 norom [X86] Do not assign address space to
1756 expansion ROMs that do not already have
1757 BIOS assigned address ranges.
1758 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1759 assigned automatically to PCI devices. You can
1760 make the kernel exclude IRQs of your ISA cards
1762 pirqaddr=0xAAAAA [X86] Specify the physical address
1763 of the PIRQ table (normally generated
1764 by the BIOS) if it is outside the
1765 F0000h-100000h range.
1766 lastbus=N [X86] Scan all buses thru bus #N. Can be
1767 useful if the kernel is unable to find your
1768 secondary buses and you want to tell it
1769 explicitly which ones they are.
1770 assign-busses [X86] Always assign all PCI bus
1771 numbers ourselves, overriding
1772 whatever the firmware may have done.
1773 usepirqmask [X86] Honor the possible IRQ mask stored
1774 in the BIOS $PIR table. This is needed on
1775 some systems with broken BIOSes, notably
1776 some HP Pavilion N5400 and Omnibook XE3
1777 notebooks. This will have no effect if ACPI
1778 IRQ routing is enabled.
1779 noacpi [X86] Do not use ACPI for IRQ routing
1780 or for PCI scanning.
1781 use_crs [X86] Use _CRS for PCI resource
1783 routeirq Do IRQ routing for all PCI devices.
1784 This is normally done in pci_enable_device(),
1785 so this option is a temporary workaround
1786 for broken drivers that don't call it.
1787 skip_isa_align [X86] do not align io start addr, so can
1788 handle more pci cards
1789 firmware [ARM] Do not re-enumerate the bus but instead
1790 just use the configuration from the
1791 bootloader. This is currently used on
1792 IXP2000 systems where the bus has to be
1793 configured a certain way for adjunct CPUs.
1794 noearly [X86] Don't do any early type 1 scanning.
1795 This might help on some broken boards which
1796 machine check when some devices' config space
1797 is read. But various workarounds are disabled
1798 and some IOMMU drivers will not work.
1799 bfsort Sort PCI devices into breadth-first order.
1800 This sorting is done to get a device
1801 order compatible with older (<= 2.4) kernels.
1802 nobfsort Don't sort PCI devices into breadth-first order.
1803 cbiosize=nn[KMG] The fixed amount of bus space which is
1804 reserved for the CardBus bridge's IO window.
1805 The default value is 256 bytes.
1806 cbmemsize=nn[KMG] The fixed amount of bus space which is
1807 reserved for the CardBus bridge's memory
1808 window. The default value is 64 megabytes.
1811 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1812 Specifies alignment and device to reassign
1813 aligned memory resources.
1814 If <order of align> is not specified,
1815 PAGE_SIZE is used as alignment.
1816 PCI-PCI bridge can be specified, if resource
1817 windows need to be expanded.
1819 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1822 force Enable ASPM even on devices that claim not to support it.
1823 WARNING: Forcing ASPM on may cause system lockups.
1825 pcmv= [HW,PCMCIA] BadgePAD 4
1828 See Documentation/blockdev/paride.txt.
1830 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1833 See arch/parisc/kernel/pdc_chassis.c
1836 See Documentation/blockdev/paride.txt.
1839 See Documentation/blockdev/paride.txt.
1841 pirq= [SMP,APIC] Manual mp-table setup
1842 See Documentation/x86/i386/IO-APIC.txt.
1844 plip= [PPT,NET] Parallel port network link
1845 Format: { parport<nr> | timid | 0 }
1846 See also Documentation/parport.txt.
1848 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1849 Override pmtimer IOPort with a hex value.
1853 Enable PNP debug messages. This depends on the
1854 CONFIG_PNP_DEBUG_MESSAGES option.
1860 { on | off | curr | res | no-curr | no-res }
1863 [ISAPNP] Exclude IRQs for the autoconfiguration
1866 [ISAPNP] Exclude DMAs for the autoconfiguration
1868 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1869 Ranges are in pairs (I/O port base and size).
1872 [ISAPNP] Exclude memory regions for the
1874 Ranges are in pairs (memory base and size).
1876 print-fatal-signals=
1877 [KNL] debug: print fatal signals
1878 print-fatal-signals=1: print segfault info to
1882 printk.time= Show timing data prefixed to each printk message line
1883 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1885 profile= [KNL] Enable kernel profiling via /proc/profile
1886 Format: [schedule,]<number>
1887 Param: "schedule" - profile schedule points.
1888 Param: <number> - step/bucket size as a power of 2 for
1889 statistical time based profiling.
1890 Param: "sleep" - profile D-state sleeping (millisecs).
1891 Requires CONFIG_SCHEDSTATS
1892 Param: "kvm" - profile VM exits.
1894 processor.max_cstate= [HW,ACPI]
1895 Limit processor to maximum C-state
1896 max_cstate=9 overrides any DMI blacklist limit.
1898 processor.nocst [HW,ACPI]
1899 Ignore the _CST method to determine C-states,
1900 instead using the legacy FADT method
1902 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1904 See Documentation/blockdev/ramdisk.txt.
1906 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1907 probe for; one of (bare|imps|exps|lifebook|any).
1908 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1910 psmouse.resetafter= [HW,MOUSE]
1911 Try to reset the device after so many bad packets
1914 [HW,MOUSE] Set desired mouse resolution, in dpi.
1915 psmouse.smartscroll=
1916 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1917 0 = disabled, 1 = enabled (default).
1919 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1921 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1924 See Documentation/blockdev/paride.txt.
1927 [KNL] Number of legacy pty's. Overwrites compiled-in
1930 quiet [KNL] Disable most log messages
1935 See Documentation/md.txt.
1937 ramdisk_blocksize= [RAM]
1938 See Documentation/blockdev/ramdisk.txt.
1940 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1941 See Documentation/blockdev/ramdisk.txt.
1943 rcupdate.blimit= [KNL,BOOT]
1944 Set maximum number of finished RCU callbacks to process
1947 rcupdate.qhimark= [KNL,BOOT]
1948 Set threshold of queued
1949 RCU callbacks over which batch limiting is disabled.
1951 rcupdate.qlowmark= [KNL,BOOT]
1952 Set threshold of queued RCU callbacks below which
1953 batch limiting is re-enabled.
1957 Run specified binary instead of /init from the ramdisk,
1958 used for early userspace startup. See initrd.
1960 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1961 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1962 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1965 [KNL, SMP] Set scheduler's default relax_domain_level.
1966 See Documentation/cpusets.txt.
1968 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1970 reservetop= [X86-32]
1972 Reserves a hole at the top of the kernel virtual
1975 reset_devices [KNL] Force drivers to reset the underlying device
1976 during initialization.
1979 Specify the partition device for software suspend
1981 resume_offset= [SWSUSP]
1982 Specify the offset from the beginning of the partition
1983 given by "resume=" at which the swap header is located,
1984 in <PAGE_SIZE> units (needed only for swap files).
1985 See Documentation/power/swsusp-and-swap-files.txt
1987 retain_initrd [RAM] Keep initrd memory after extraction
1989 rhash_entries= [KNL,NET]
1990 Set number of hash buckets for route cache
1992 riscom8= [HW,SERIAL]
1993 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1995 ro [KNL] Mount root device read-only on boot
1997 root= [KNL] Root filesystem
1999 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2000 mount the root filesystem
2002 rootflags= [KNL] Set root filesystem mount option string
2004 rootfstype= [KNL] Set root filesystem type
2006 rootwait [KNL] Wait (indefinitely) for root device to show up.
2007 Useful for devices that are detected asynchronously
2008 (e.g. USB and MMC devices).
2010 root_plug.vendor_id=
2011 [ROOTPLUG] Override the default vendor ID
2013 root_plug.product_id=
2014 [ROOTPLUG] Override the default product ID
2017 [ROOTPLUG] Enable debugging output
2019 rw [KNL] Mount root device read-write on boot
2021 S [KNL] Run init in single mode
2024 See drivers/net/irda/sa1100_ir.c.
2026 sbni= [NET] Granch SBNI12 leased line adapter
2028 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2029 Format: <io>[,<timeout>[,<isapnp>]]
2031 scsi_debug_*= [SCSI]
2032 See drivers/scsi/scsi_debug.c.
2034 scsi_default_dev_flags=
2035 [SCSI] SCSI default device flags
2038 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2039 Format: <vendor>:<model>:<flags>
2040 (flags are integer value)
2042 scsi_logging_level= [SCSI] a bit mask of logging levels
2043 See drivers/scsi/scsi_logging.h for bits. Also
2044 settable via sysctl at dev.scsi.logging_level
2045 (/proc/sys/dev/scsi/logging_level).
2046 There is also a nice 'scsi_logging_level' script in the
2047 S390-tools package, available for download at
2048 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2050 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2051 discovered. async scans them in kernel threads,
2052 allowing boot to proceed. none ignores them, expecting
2053 user space to do the scan.
2055 selinux [SELINUX] Disable or enable SELinux at boot time.
2056 Format: { "0" | "1" }
2057 See security/selinux/Kconfig help text.
2060 Default value is set via kernel config option.
2061 If enabled at boot time, /selinux/disable can be used
2062 later to disable prior to initial policy load.
2064 serialnumber [BUGS=X86-32]
2067 Maximal number of shapers.
2069 show_msr= [x86] show boot-time MSR settings
2070 Format: { <integer> }
2071 Show boot-time (BIOS-initialized) MSR settings.
2072 The parameter means the number of CPUs to show,
2073 for example 1 means boot CPU only.
2076 See header of drivers/scsi/sim710.c.
2083 slub_debug[=options[,slabs]] [MM, SLUB]
2084 Enabling slub_debug allows one to determine the
2085 culprit if slab objects become corrupted. Enabling
2086 slub_debug can create guard zones around objects and
2087 may poison objects when not in use. Also tracks the
2088 last alloc / free. For more information see
2089 Documentation/vm/slub.txt.
2091 slub_max_order= [MM, SLUB]
2092 Determines the maximum allowed order for slabs.
2093 A high setting may cause OOMs due to memory
2094 fragmentation. For more information see
2095 Documentation/vm/slub.txt.
2097 slub_min_objects= [MM, SLUB]
2098 The minimum number of objects per slab. SLUB will
2099 increase the slab order up to slub_max_order to
2100 generate a sufficiently large slab able to contain
2101 the number of objects indicated. The higher the number
2102 of objects the smaller the overhead of tracking slabs
2103 and the less frequently locks need to be acquired.
2104 For more information see Documentation/vm/slub.txt.
2106 slub_min_order= [MM, SLUB]
2107 Determines the mininum page order for slabs. Must be
2108 lower than slub_max_order.
2109 For more information see Documentation/vm/slub.txt.
2111 slub_nomerge [MM, SLUB]
2112 Disable merging of slabs with similar size. May be
2113 necessary if there is some reason to distinguish
2114 allocs to different slabs. Debug options disable
2115 merging on their own.
2116 For more information see Documentation/vm/slub.txt.
2119 Format: <io1>[,<io2>[,...,<io8>]]
2121 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2122 attempt to substitute SMP alternatives once at boot.
2124 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2125 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2126 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2127 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2128 smsc-ircc2.ircc_irq= [HW] IRQ line
2129 smsc-ircc2.ircc_dma= [HW] DMA channel
2130 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2131 0: Toshiba Satellite 1800 (GP data pin select)
2132 1: Fast pin select (default)
2135 snd-ad1816a= [HW,ALSA]
2137 snd-ad1848= [HW,ALSA]
2139 snd-ali5451= [HW,ALSA]
2141 snd-als100= [HW,ALSA]
2143 snd-als4000= [HW,ALSA]
2145 snd-azt2320= [HW,ALSA]
2147 snd-cmi8330= [HW,ALSA]
2149 snd-cmipci= [HW,ALSA]
2151 snd-cs4231= [HW,ALSA]
2153 snd-cs4232= [HW,ALSA]
2155 snd-cs4236= [HW,ALSA]
2157 snd-cs4281= [HW,ALSA]
2159 snd-cs46xx= [HW,ALSA]
2161 snd-dt019x= [HW,ALSA]
2163 snd-dummy= [HW,ALSA]
2165 snd-emu10k1= [HW,ALSA]
2167 snd-ens1370= [HW,ALSA]
2169 snd-ens1371= [HW,ALSA]
2171 snd-es968= [HW,ALSA]
2173 snd-es1688= [HW,ALSA]
2175 snd-es18xx= [HW,ALSA]
2177 snd-es1938= [HW,ALSA]
2179 snd-es1968= [HW,ALSA]
2181 snd-fm801= [HW,ALSA]
2183 snd-gusclassic= [HW,ALSA]
2185 snd-gusextreme= [HW,ALSA]
2187 snd-gusmax= [HW,ALSA]
2191 snd-ice1712= [HW,ALSA]
2193 snd-intel8x0= [HW,ALSA]
2195 snd-interwave= [HW,ALSA]
2200 snd-korg1212= [HW,ALSA]
2202 snd-maestro3= [HW,ALSA]
2204 snd-mpu401= [HW,ALSA]
2206 snd-mtpav= [HW,ALSA]
2208 snd-nm256= [HW,ALSA]
2210 snd-opl3sa2= [HW,ALSA]
2218 snd-opti93x= [HW,ALSA]
2222 snd-rme32= [HW,ALSA]
2224 snd-rme96= [HW,ALSA]
2226 snd-rme9652= [HW,ALSA]
2232 snd-sbawe= [HW,ALSA]
2234 snd-serial= [HW,ALSA]
2236 snd-sgalaxy= [HW,ALSA]
2238 snd-sonicvibes= [HW,ALSA]
2243 snd-sun-cs4231= [HW,ALSA]
2245 snd-trident= [HW,ALSA]
2247 snd-usb-audio= [HW,ALSA,USB]
2249 snd-via82xx= [HW,ALSA]
2251 snd-virmidi= [HW,ALSA]
2253 snd-wavefront= [HW,ALSA]
2255 snd-ymfpci= [HW,ALSA]
2258 [KNL] Should the soft-lockup detector generate panics.
2260 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2261 See Documentation/sonypi.txt
2263 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2264 See Documentation/serial/specialix.txt.
2266 spia_io_base= [HW,MTD]
2272 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2274 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2275 See Documentation/scsi/st.txt.
2278 Enabled the stack tracer on boot up.
2282 Set the STI (builtin display/keyboard on the HP-PARISC
2283 machines) console (graphic card) which should be used
2284 as the initial boot-console.
2285 See also comment in drivers/video/console/sticore.c.
2288 See comment in drivers/video/console/sticore.c.
2291 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2295 Control how the NFS server code allocates CPUs to
2296 service thread pools. Depending on how many NICs
2297 you have and where their interrupts are bound, this
2298 option will affect which CPUs will do NFS serving.
2299 Note: this parameter cannot be changed while the
2300 NFS server is running.
2302 auto the server chooses an appropriate mode
2303 automatically using heuristics
2304 global a single global pool contains all CPUs
2305 percpu one pool for each CPU
2306 pernode one pool for each NUMA node (equivalent
2307 to global on non-NUMA machines)
2309 swiotlb= [IA-64] Number of I/O TLB slabs
2313 sym53c416= [HW,SCSI]
2314 See header of drivers/scsi/sym53c416.c.
2316 sysrq_always_enabled
2318 Ignore sysrq setting - this boot parameter will
2319 neutralize any effect of /proc/sys/kernel/sysrq.
2320 Useful for debugging.
2323 See header of drivers/scsi/t128.c.
2327 test_suspend= [SUSPEND]
2328 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2329 standby suspend) as the system sleep state to briefly
2330 enter during system startup. The system is woken from
2331 this state using a wakeup-capable RTC alarm.
2333 thash_entries= [KNL,NET]
2334 Set number of hash buckets for TCP connection
2336 thermal.act= [HW,ACPI]
2337 -1: disable all active trip points in all thermal zones
2338 <degrees C>: override all lowest active trip points
2340 thermal.crt= [HW,ACPI]
2341 -1: disable all critical trip points in all thermal zones
2342 <degrees C>: override all critical trip points
2344 thermal.nocrt= [HW,ACPI]
2345 Set to disable actions on ACPI thermal zone
2346 critical and hot trip points.
2348 thermal.off= [HW,ACPI]
2349 1: disable ACPI thermal control
2351 thermal.psv= [HW,ACPI]
2352 -1: disable all passive trip points
2353 <degrees C>: override all passive trip points to this
2356 thermal.tzp= [HW,ACPI]
2357 Specify global default ACPI thermal zone polling rate
2358 <deci-seconds>: poll all this frequency
2359 0: no polling (default)
2362 See comment before function dc390_setup() in
2363 drivers/scsi/tmscsim.c.
2367 Specify if the kernel should make use of the cpu
2368 topology informations if the hardware supports these.
2369 The scheduler will make use of these informations and
2370 e.g. base its process migration decisions on it.
2375 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2377 trix= [HW,OSS] MediaTrix AudioTrix Pro
2379 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2381 tsc= Disable clocksource-must-verify flag for TSC.
2383 [x86] reliable: mark tsc clocksource as reliable, this
2384 disables clocksource verification at runtime.
2385 Used to enable high-resolution timer mode on older
2386 hardware, and in virtualized environment.
2388 turbografx.map[2|3]= [HW,JOY]
2389 TurboGraFX parallel port interface
2391 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2392 See also Documentation/input/joystick-parport.txt
2394 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2395 See header of drivers/scsi/u14-34f.c.
2404 [USB] Ignore overcurrent events (default N).
2405 Some badly-designed motherboards generate lots of
2406 bogus events, for ports that aren't wired to
2407 anything. Set this parameter to avoid log spamming.
2408 Note that genuine overcurrent events won't be
2413 Set unknown_nmi_panic=1 early on boot.
2415 usbcore.autosuspend=
2416 [USB] The autosuspend time delay (in seconds) used
2417 for newly-detected USB devices (default 2). This
2418 is the time required before an idle device will be
2419 autosuspended. Devices for which the delay is set
2420 to a negative value won't be autosuspended at all.
2422 usbcore.usbfs_snoop=
2423 [USB] Set to log all usbfs traffic (default 0 = off).
2425 usbcore.blinkenlights=
2426 [USB] Set to cycle leds on hubs (default 0 = off).
2428 usbcore.old_scheme_first=
2429 [USB] Start with the old device initialization
2430 scheme (default 0 = off).
2432 usbcore.use_both_schemes=
2433 [USB] Try the other device initialization scheme
2434 if the first one fails (default 1 = enabled).
2436 usbcore.initial_descriptor_timeout=
2437 [USB] Specifies timeout for the initial 64-byte
2438 USB_REQ_GET_DESCRIPTOR request in milliseconds
2439 (default 5000 = 5.0 seconds).
2442 [USBHID] The interval which mice are to be polled at.
2444 usb-storage.delay_use=
2445 [UMS] The delay in seconds before a new device is
2446 scanned for Logical Units (default 5).
2449 [UMS] A list of quirks entries to supplement or
2450 override the built-in unusual_devs list. List
2451 entries are separated by commas. Each entry has
2452 the form VID:PID:Flags where VID and PID are Vendor
2453 and Product ID values (4-digit hex numbers) and
2454 Flags is a set of characters, each corresponding
2455 to a common usb-storage quirk flag as follows:
2456 a = SANE_SENSE (collect more than 18 bytes
2458 c = FIX_CAPACITY (decrease the reported
2459 device capacity by one sector);
2460 h = CAPACITY_HEURISTICS (decrease the
2461 reported device capacity by one
2462 sector if the number is odd);
2463 i = IGNORE_DEVICE (don't bind to this
2465 l = NOT_LOCKABLE (don't try to lock and
2466 unlock ejectable media);
2467 m = MAX_SECTORS_64 (don't transfer more
2468 than 64 sectors = 32 KB at a time);
2469 o = CAPACITY_OK (accept the capacity
2470 reported by the device);
2471 r = IGNORE_RESIDUE (the device reports
2472 bogus residue values);
2473 s = SINGLE_LUN (the device has only one
2475 w = NO_WP_DETECT (don't test whether the
2476 medium is write-protected).
2477 Example: quirks=0419:aaf5:rl,0421:0433:rc
2479 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2480 kernel's map of available physical RAM.
2482 vdso= [X86-32,SH,x86-64]
2483 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2484 vdso=1: enable VDSO (default)
2485 vdso=0: disable VDSO mapping
2487 vdso32= [X86-32,X86-64]
2488 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2489 vdso32=1: enable 32-bit VDSO (default)
2490 vdso32=0: disable 32-bit VDSO mapping
2493 vector=percpu: enable percpu vector domain
2495 video= [FB] Frame buffer configuration
2496 See Documentation/fb/modedb.txt.
2498 vga= [BOOT,X86-32] Select a particular video mode
2499 See Documentation/x86/boot.txt and
2500 Documentation/svga.txt.
2501 Use vga=ask for menu.
2502 This is actually a boot loader parameter; the value is
2503 passed to the kernel using a special protocol.
2505 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2506 size of <nn>. This can be used to increase the
2507 minimum size (128MB on x86). It can also be used to
2508 decrease the size and leave more room for directly
2511 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2514 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2517 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2520 waveartist= [HW,OSS]
2521 Format: <io>,<irq>,<dma>,<dma2>
2524 See header of drivers/scsi/wd33c93.c.
2527 See header of drivers/scsi/wd7000.c.
2530 See Documentation/watchdog/wdt.txt.
2532 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2533 xd_geo= See header of drivers/block/xd.c.
2535 xirc2ps_cs= [NET,PCMCIA]
2537 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2539 norandmaps Don't use address space randomization. Equivalent to
2540 echo 0 > /proc/sys/kernel/randomize_va_space
2542 ______________________________________________________________________
2546 Add documentation for ALSA options.
2547 Add more DRM drivers.
projects / linux-2.6 / blob