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 LIBATA Libata driver is enabled
54 LP Printer support is enabled.
55 LOOP Loopback device support is enabled.
56 M68k M68k architecture is enabled.
57 These options have more detailed description inside of
58 Documentation/m68k/kernel-options.txt.
59 MCA MCA bus support is enabled.
60 MDA MDA console support is enabled.
61 MOUSE Appropriate mouse support is enabled.
62 MSI Message Signaled Interrupts (PCI).
63 MTD MTD (Memory Technology Device) support is enabled.
64 NET Appropriate network support is enabled.
65 NUMA NUMA support is enabled.
66 GENERIC_TIME The generic timeofday code is enabled.
67 NFS Appropriate NFS support is enabled.
68 OSS OSS sound support is enabled.
69 PV_OPS A paravirtualized kernel is enabled.
70 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
71 PARISC The PA-RISC architecture is enabled.
72 PCI PCI bus support is enabled.
73 PCIE PCI Express support is enabled.
74 PCMCIA The PCMCIA subsystem is enabled.
75 PNP Plug & Play support is enabled.
76 PPC PowerPC architecture is enabled.
77 PPT Parallel port support is enabled.
78 PS2 Appropriate PS/2 support is enabled.
79 RAM RAM disk support is enabled.
80 ROOTPLUG The example Root Plug LSM is enabled.
81 S390 S390 architecture is enabled.
82 SCSI Appropriate SCSI support is enabled.
83 A lot of drivers has their options described inside of
85 SECURITY Different security models are enabled.
86 SELINUX SELinux support is enabled.
87 SERIAL Serial support is enabled.
88 SH SuperH architecture is enabled.
89 SMP The kernel is an SMP kernel.
90 SPARC Sparc architecture is enabled.
91 SWSUSP Software suspend (hibernation) is enabled.
92 SUSPEND System suspend states are enabled.
93 FTRACE Function tracing enabled.
94 TS Appropriate touchscreen support is enabled.
95 UMS USB Mass Storage support is enabled.
96 USB USB support is enabled.
97 USBHID USB Human Interface Device support is enabled.
98 V4L Video For Linux support is enabled.
99 VGA The VGA console has been enabled.
100 VT Virtual terminal support is enabled.
101 WDT Watchdog support is enabled.
102 XT IBM PC/XT MFM hard disk support is enabled.
103 X86-32 X86-32, aka i386 architecture is enabled.
104 X86-64 X86-64 architecture is enabled.
105 More X86-64 boot options can be found in
106 Documentation/x86/x86_64/boot-options.txt .
107 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
109 In addition, the following text indicates that the option:
111 BUGS= Relates to possible processor bugs on the said processor.
112 KNL Is a kernel start-up parameter.
113 BOOT Is a boot loader parameter.
115 Parameters denoted with BOOT are actually interpreted by the boot
116 loader, and have no meaning to the kernel directly.
117 Do not modify the syntax of boot loader parameters without extreme
118 need or coordination with <Documentation/x86/boot.txt>.
120 There are also arch-specific kernel-parameters not documented here.
121 See for example <Documentation/x86/x86_64/boot-options.txt>.
123 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
124 a trailing = on the name of any parameter states that that parameter will
125 be entered as an environment variable, whereas its absence indicates that
126 it will appear as a kernel argument readable via /proc/cmdline by programs
127 running once the system is up.
129 The number of kernel parameters is not limited, but the length of the
130 complete command line (parameters including spaces etc.) is limited to
131 a fixed number of characters. This limit depends on the architecture
132 and is between 256 and 4096 characters. It is defined in the file
133 ./include/asm/setup.h as COMMAND_LINE_SIZE.
136 acpi= [HW,ACPI,X86-64,i386]
137 Advanced Configuration and Power Interface
138 Format: { force | off | ht | strict | noirq | rsdt }
139 force -- enable ACPI if default was off
140 off -- disable ACPI if default was on
141 noirq -- do not use ACPI for IRQ routing
142 ht -- run only enough ACPI to enable Hyper Threading
143 strict -- Be less tolerant of platforms that are not
144 strictly ACPI specification compliant.
145 rsdt -- prefer RSDT over (default) XSDT
147 See also Documentation/power/pm.txt, pci=noacpi
149 acpi_apic_instance= [ACPI, IOAPIC]
151 2: use 2nd APIC table, if available
152 1,0: use 1st APIC table
155 acpi_sleep= [HW,ACPI] Sleep options
156 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
157 old_ordering, s4_nonvs }
158 See Documentation/power/video.txt for information on
160 s3_beep is for debugging; it makes the PC's speaker beep
161 as soon as the kernel's real-mode entry point is called.
162 s4_nohwsig prevents ACPI hardware signature from being
163 used during resume from hibernation.
164 old_ordering causes the ACPI 1.0 ordering of the _PTS
165 control method, with respect to putting devices into
166 low power states, to be enforced (the ACPI 2.0 ordering
167 of _PTS is used by default).
168 s4_nonvs prevents the kernel from saving/restoring the
169 ACPI NVS memory during hibernation.
171 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
172 Format: { level | edge | high | low }
174 acpi_irq_balance [HW,ACPI]
175 ACPI will balance active IRQs
178 acpi_irq_nobalance [HW,ACPI]
179 ACPI will not move active IRQs (default)
182 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
184 Format: <irq>,<irq>...
186 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
187 Format: <irq>,<irq>...
189 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
191 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
192 Format: To spoof as Windows 98: ="Microsoft Windows"
194 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
195 acpi_osi="string1" # add string1 -- only one string
196 acpi_osi="!string2" # remove built-in string2
197 acpi_osi= # disable all strings
199 acpi_serialize [HW,ACPI] force serialization of AML methods
201 acpi_skip_timer_override [HW,ACPI]
202 Recognize and ignore IRQ0/pin2 Interrupt Override.
203 For broken nForce2 BIOS resulting in XT-PIC timer.
204 acpi_use_timer_override [HW,ACPI]
205 Use timer override. For some broken Nvidia NF5 boards
206 that require a timer override, but don't have
209 acpi_backlight= [HW,ACPI]
210 acpi_backlight=vendor
212 If set to vendor, prefer vendor specific driver
213 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
214 of the ACPI video.ko driver.
216 acpi_display_output= [HW,ACPI]
217 acpi_display_output=vendor
218 acpi_display_output=video
221 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
222 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
224 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
225 debug output. Bits in debug_layer correspond to a
226 _COMPONENT in an ACPI source file, e.g.,
227 #define _COMPONENT ACPI_PCI_COMPONENT
228 Bits in debug_level correspond to a level in
229 ACPI_DEBUG_PRINT statements, e.g.,
230 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
231 The debug_level mask defaults to "info". See
232 Documentation/acpi/debug.txt for more information about
233 debug layers and levels.
235 Enable processor driver info messages:
236 acpi.debug_layer=0x20000000
237 Enable PCI/PCI interrupt routing info messages:
238 acpi.debug_layer=0x400000
239 Enable AML "Debug" output, i.e., stores to the Debug
240 object while interpreting AML:
241 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
242 Enable all messages related to ACPI hardware:
243 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
245 Some values produce so much output that the system is
246 unusable. The "log_buf_len" parameter may be useful
247 if you need to capture more output.
249 acpi.power_nocheck= [HW,ACPI]
250 Format: 1/0 enable/disable the check of power state.
251 On some bogus BIOS the _PSC object/_STA object of
252 power resource can't return the correct device power
253 state. In such case it is unneccessary to check its
254 power state again in power transition.
255 1 : disable the power state check
257 acpi_pm_good [X86-32,X86-64]
258 Override the pmtimer bug detection: force the kernel
259 to assume that this machine's pmtimer latches its value
260 and always returns good values.
262 acpi_enforce_resources= [ACPI]
263 { strict | lax | no }
264 Check for resource conflicts between native drivers
265 and ACPI OperationRegions (SystemIO and SystemMemory
266 only). IO ports and memory declared in ACPI might be
267 used by the ACPI subsystem in arbitrary AML code and
268 can interfere with legacy drivers.
269 strict (default): access to resources claimed by ACPI
270 is denied; legacy drivers trying to access reserved
271 resources will fail to bind to device using them.
272 lax: access to resources claimed by ACPI is allowed;
273 legacy drivers trying to access reserved resources
274 will bind successfully but a warning message is logged.
275 no: ACPI OperationRegions are not marked as reserved,
276 no further checks are performed.
279 { off | try_unsupported }
280 off: disable AGP support
281 try_unsupported: try to drive unsupported chipsets
282 (may crash computer or cause data corruption)
284 enable_timer_pin_1 [i386,x86-64]
285 Enable PIN 1 of APIC timer
286 Can be useful to work around chipset bugs
287 (in particular on some ATI chipsets).
288 The kernel tries to set a reasonable default.
290 disable_timer_pin_1 [i386,x86-64]
291 Disable PIN 1 of APIC timer
292 Can be useful to work around chipset bugs.
295 Format: <io>,<irq>,<dma>,<dma2>,<type>
298 See header of drivers/scsi/advansys.c.
300 advwdt= [HW,WDT] Advantech WDT
301 Format: <iostart>,<iostop>
303 aedsp16= [HW,OSS] Audio Excel DSP 16
304 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
305 See also header of sound/oss/aedsp16.c.
308 See Documentation/scsi/aha152x.txt.
311 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
314 See Documentation/scsi/aic7xxx.txt.
317 See Documentation/scsi/aic79xx.txt.
319 amd_iommu= [HW,X86-84]
320 Pass parameters to the AMD IOMMU driver in the system.
322 isolate - enable device isolation (each device, as far
323 as possible, will get its own protection
325 share - put every device behind one IOMMU into the
326 same protection domain
327 fullflush - enable flushing of IO/TLB entries when
328 they are unmapped. Otherwise they are
329 flushed before they will be reused, which
332 amd_iommu_size= [HW,X86-64]
333 Define the size of the aperture for the AMD IOMMU
334 driver. Possible values are:
335 '32M', '64M' (default), '128M', '256M', '512M', '1G'
337 amijoy.map= [HW,JOY] Amiga joystick support
338 Map of devices attached to JOY0DAT and JOY1DAT
340 See also Documentation/kernel/input/joystick.txt
342 analog.map= [HW,JOY] Analog joystick and gamepad support
343 Specifies type or capabilities of an analog joystick
344 connected to one of 16 gameports
345 Format: <type1>,<type2>,..<type16>
348 Power management functions (SPARCstation-4/5 + deriv.)
350 Disable APC CPU standby support. SPARCstation-Fox does
351 not play well with APC CPU idle - disable it if you have
352 APC and your system crashes randomly.
354 apic= [APIC,i386] Advanced Programmable Interrupt Controller
355 Change the output verbosity whilst booting
356 Format: { quiet (default) | verbose | debug }
357 Change the amount of debugging information output
358 when initialising the APIC and IO-APIC components.
360 apm= [APM] Advanced Power Management
361 See header of arch/x86/kernel/apm_32.c.
363 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
364 Format: <io>,<irq>,<nodeID>
368 atarimouse= [HW,MOUSE] Atari Mouse
370 atascsi= [HW,SCSI] Atari SCSI
372 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
373 EzKey and similar keyboards
375 atkbd.reset= [HW] Reset keyboard during initialization
377 atkbd.set= [HW] Select keyboard code set
378 Format: <int> (2 = AT (default), 3 = PS/2)
380 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
383 atkbd.softraw= [HW] Choose between synthetic and real raw mode
384 Format: <bool> (0 = real, 1 = synthetic (default))
386 atkbd.softrepeat= [HW]
387 Use software keyboard repeat
391 baycom_epp= [HW,AX25]
394 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
396 See header of drivers/net/hamradio/baycom_par.c.
398 baycom_ser_fdx= [HW,AX25]
399 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
400 Format: <io>,<irq>,<mode>[,<baud>]
401 See header of drivers/net/hamradio/baycom_ser_fdx.c.
403 baycom_ser_hdx= [HW,AX25]
404 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
405 Format: <io>,<irq>,<mode>
406 See header of drivers/net/hamradio/baycom_ser_hdx.c.
408 boot_delay= Milliseconds to delay each printk during boot.
409 Values larger than 10 seconds (10000) are changed to
413 bootmem_debug [KNL] Enable bootmem allocator debug messages.
415 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
416 bttv.radio= Most important insmod options are available as
418 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
419 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
422 See drivers/scsi/BusLogic.c, comment before function
423 BusLogic_ParseDriverOptions().
425 c101= [NET] Moxa C101 synchronous serial card
427 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
428 Sometimes CPU hardware bugs make them report the cache
429 size incorrectly. The kernel will attempt work arounds
430 to fix known problems, but for some CPUs it is not
431 possible to determine what the correct size should be.
432 This option provides an override for these situations.
434 security= [SECURITY] Choose a security module to enable at boot.
435 If this boot parameter is not specified, only the first
436 security module asking for security registration will be
437 loaded. An invalid security module name will be treated
438 as if no module has been chosen.
441 [SECURITY] Disable capabilities. This would normally
442 be used only if an alternative security model is to be
443 configured. Potentially dangerous and should only be
444 used if you are entirely sure of the consequences.
446 ccw_timeout_log [S390]
447 See Documentation/s390/CommonIO for details.
449 cgroup_disable= [KNL] Disable a particular controller
450 Format: {name of the controller(s) to disable}
451 {Currently supported controllers - "memory"}
453 checkreqprot [SELINUX] Set initial checkreqprot flag value.
454 Format: { "0" | "1" }
455 See security/selinux/Kconfig help text.
456 0 -- check protection applied by kernel (includes
457 any implied execute protection).
458 1 -- check protection requested by application.
459 Default value is set via a kernel config option.
460 Value can be changed at runtime via
461 /selinux/checkreqprot.
464 See Documentation/s390/CommonIO for details.
466 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
468 Forces specified clocksource (if available) to be used
469 when calculating gettimeofday(). If specified
470 clocksource is not available, it defaults to PIT.
471 Format: { pit | tsc | cyclone | pmtmr }
473 clocksource= [GENERIC_TIME] Override the default clocksource
475 Override the default clocksource and use the clocksource
476 with the name specified.
477 Some clocksource names to choose from, depending on
479 [all] jiffies (this is the base, fallback clocksource)
481 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
482 pxa_timer,timer3,32k_counter,timer0_1
484 [X86-32] pit,hpet,tsc,vmi-timer;
485 scx200_hrt on Geode; cyclone on IBM x440
493 clearcpuid=BITNUM [X86]
494 Disable CPUID feature X for the kernel. See
495 arch/x86/include/asm/cpufeature.h for the valid bit
496 numbers. Note the Linux specific bits are not necessarily
497 stable over kernel options, but the vendor specific
499 Also note that user programs calling CPUID directly
500 or using the feature without checking anything
501 will still see it. This just prevents it from
502 being used by the kernel or shown in /proc/cpuinfo.
503 Also note the kernel might malfunction if you disable
506 code_bytes [IA32/X86_64] How many bytes of object code to print
511 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support
512 this option disables the debugging code at boot.
514 dma_debug_entries=<number>
515 This option allows to tune the number of preallocated
516 entries for DMA-API debugging code. One entry is
517 required per DMA-API allocation. Use this if the
518 DMA-API debugging code disables itself because the
519 architectural default is too low.
521 hpet= [X86-32,HPET] option to control HPET usage
522 Format: { enable (default) | disable | force |
524 disable: disable HPET and use PIT instead
525 force: allow force enabled of undocumented chips (ICH4,
527 verbose: show contents of HPET registers during setup
529 com20020= [HW,NET] ARCnet - COM20020 chipset
531 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
533 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
537 ARCnet - COM90xx chipset (memory-mapped buffers)
538 Format: <io>[,<irq>[,<memstart>]]
540 condev= [HW,S390] console device
543 console= [KNL] Output console device and options.
545 tty<n> Use the virtual console device <n>.
549 Use the specified serial port. The options are of
550 the form "bbbbpnf", where "bbbb" is the baud rate,
551 "p" is parity ("n", "o", or "e"), "n" is number of
552 bits, and "f" is flow control ("r" for RTS or
553 omit it). Default is "9600n8".
555 See Documentation/serial-console.txt for more
557 Documentation/networking/netconsole.txt for an
560 uart[8250],io,<addr>[,options]
561 uart[8250],mmio,<addr>[,options]
562 Start an early, polled-mode console on the 8250/16550
563 UART at the specified I/O port or MMIO address,
564 switching to the matching ttyS device later. The
565 options are the same as for ttyS, above.
567 If the device connected to the port is not a TTY but a braille
568 device, prepend "brl," before the device type, for instance
570 For now, only VisioBraille is supported.
572 earlycon= [KNL] Output early console device and options.
573 uart[8250],io,<addr>[,options]
574 uart[8250],mmio,<addr>[,options]
575 Start an early, polled-mode console on the 8250/16550
576 UART at the specified I/O port or MMIO address.
577 The options are the same as for ttyS, above.
580 [HW] Never suspend the console
581 Disable suspending of consoles during suspend and
582 hibernate operations. Once disabled, debugging
583 messages can reach various consoles while the rest
584 of the system is being put to sleep (ie, while
585 debugging driver suspend/resume hooks). This may
586 not work reliably with all consoles, but is known
587 to work with serial and VGA consoles.
590 [KNL] Change the default value for
591 /proc/<pid>/coredump_filter.
592 See also Documentation/filesystems/proc.txt.
594 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
596 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
598 crashkernel=nn[KMG]@ss[KMG]
599 [KNL] Reserve a chunk of physical memory to
600 hold a kernel to switch to with kexec on panic.
602 crashkernel=range1:size1[,range2:size2,...][@offset]
603 [KNL] Same as above, but depends on the memory
604 in the running system. The syntax of range is
605 start-[end] where start and end are both
606 a memory unit (amount[KMG]). See also
607 Documentation/kdump/kdump.txt for a example.
612 cs89x0_media= [HW,NET]
613 Format: { rj45 | aui | bnc }
616 See header of drivers/s390/block/dasd_devmap.c.
618 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
619 (one device per port)
620 Format: <port#>,<type>
621 See also Documentation/input/joystick-parport.txt
623 debug [KNL] Enable kernel debugging (events log level).
626 [KNL] verbose self-tests
628 Print debugging info while doing the locking API
630 We default to 0 (no extra messages), setting it to
631 1 will print _a lot_ more information - normally
632 only useful to kernel developers.
634 debug_objects [KNL] Enable object debugging
636 debugpat [X86] Enable PAT debugging
638 decnet.addr= [HW,NET]
639 Format: <area>[,<node>]
640 See also Documentation/networking/decnet.txt.
643 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
644 Change the default blue palette of the console.
645 This is a 16-member array composed of values
649 Format: <green0>,<green1>,<green2>,...,<green15>
650 Change the default green palette of the console.
651 This is a 16-member array composed of values
655 Format: <red0>,<red1>,<red2>,...,<red15>
656 Change the default red palette of the console.
657 This is a 16-member array composed of values
663 Set system-wide default UTF-8 mode for all tty's.
664 Default is 1, i.e. UTF-8 mode is enabled for all
665 newly opened terminals.
668 Set number of hash buckets for dentry cache.
671 IO parameters + enable/disable command.
673 digiepca= [HW,SERIAL]
674 See drivers/char/README.epca and
675 Documentation/serial/digiepca.txt.
677 disable_mtrr_cleanup [X86]
678 enable_mtrr_cleanup [X86]
679 The kernel tries to adjust MTRR layout from continuous
680 to discrete, to make X server driver able to add WB
681 entry later. This parameter enables/disables that.
683 mtrr_chunk_size=nn[KMG] [X86]
684 used for mtrr cleanup. It is largest continous chunk
685 that could hold holes aka. UC entries.
687 mtrr_gran_size=nn[KMG] [X86]
688 Used for mtrr cleanup. It is granularity of mtrr block.
690 Large value could prevent small alignment from
693 mtrr_spare_reg_nr=n [X86]
695 Range: 0,7 : spare reg number
697 Used for mtrr cleanup. It is spare mtrr entries number.
698 Set to 2 or more if your graphical card needs more.
700 disable_mtrr_trim [X86, Intel and AMD only]
701 By default the kernel will trim any uncacheable
702 memory out of your available memory pool based on
703 MTRR settings. This parameter disables that behavior,
704 possibly causing your machine to run very slowly.
706 dmasound= [HW,OSS] Sound subsystem buffers
712 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
714 earlyprintk=serial[,ttySn[,baudrate]]
717 Append ",keep" to not disable it when the real console
720 Only vga or serial or usb debug port at a time.
722 Currently only ttyS0 and ttyS1 are supported.
724 Interaction with the standard serial driver is not
727 The VGA output is eventually overwritten by the real
733 Format: {"off" | "on" | "skip[mbr]"}
735 eisa_irq_edge= [PARISC,HW]
736 See header of drivers/parisc/eisa.c.
739 See comment before function elanfreq_setup() in
740 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
743 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
744 See Documentation/block/as-iosched.txt and
745 Documentation/block/deadline-iosched.txt for details.
747 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
748 Specifies physical address of start of kernel core
749 image elf header. Generally kexec loader will
750 pass this option to capture kernel.
751 See Documentation/kdump/kdump.txt for details.
753 enforcing [SELINUX] Set initial enforcing status.
755 See security/selinux/Kconfig help text.
756 0 -- permissive (log only, no denials).
757 1 -- enforcing (deny and log).
759 Value can be changed at runtime via /selinux/enforce.
761 ether= [HW,NET] Ethernet cards parameters
762 This option is obsoleted by the "netdev=" option, which
763 has equivalent usage. See its documentation for details.
765 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
770 fail_make_request=[KNL]
771 General fault injection mechanism.
772 Format: <interval>,<probability>,<space>,<times>
773 See also /Documentation/fault-injection/.
776 See header of drivers/scsi/fd_mcs.c.
779 See header of drivers/scsi/fdomain.c.
782 See Documentation/blockdev/floppy.txt.
784 force_pal_cache_flush
785 [IA-64] Avoid check_sal_cache_flush which may hang on
786 buggy SAL_CACHE_FLUSH implementations. Using this
787 parameter will force ia64_sal_cache_flush to call
788 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
791 [ftrace] will set and start the specified tracer
792 as early as possible in order to facilitate early
796 [ftrace] will dump the trace buffers on oops.
799 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
800 support via parallel port (up to 5 devices per port)
801 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
802 See also Documentation/input/joystick-parport.txt
806 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
811 See header of drivers/scsi/gdth.c.
813 gpt [EFI] Forces disk with valid GPT signature but
814 invalid Protective MBR to be treated as GPT.
818 hashdist= [KNL,NUMA] Large hashes allocated during boot
819 are distributed across NUMA nodes. Defaults on
820 for IA-64, off otherwise.
821 Format: 0 | 1 (for off | on)
823 hcl= [IA-64] SGI's Hardware Graph compatibility layer
825 hd= [EIDE] (E)IDE hard drive subsystem geometry
826 Format: <cyl>,<head>,<sect>
828 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
829 size of <nn>. This works even on boxes that have no
830 highmem otherwise. This also works to reduce highmem
831 size on bigger boxes.
833 highres= [KNL] Enable/disable high resolution timer mode.
834 Valid parameters: "on", "off"
838 See Documentation/isdn/README.HiSax.
840 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
841 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
842 On x86-64 and powerpc, this option can be specified
843 multiple times interleaved with hugepages= to reserve
844 huge pages of different sizes. Valid pages sizes on
845 x86-64 are 2M (when the CPU supports "pse") and 1G
846 (when the CPU supports the "pdpe1gb" cpuinfo flag)
847 Note that 1GB pages can only be allocated at boot time
848 using hugepages= and not freed afterwards.
850 [same as hugepagesz=] The size of the default
851 HugeTLB page size. This is the size represented by
852 the legacy /proc/ hugepages APIs, used for SHM, and
853 default size when mounting hugetlbfs filesystems.
854 Defaults to the default architecture's huge page size
859 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
860 terminal devices. Valid values: 0..8
861 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
862 If specified, z/VM IUCV HVC accepts connections
863 from listed z/VM user IDs only.
865 i2c_bus= [HW] Override the default board specific I2C bus speed
866 or register an additional I2C bus that is not
867 registered from board initialization code.
871 i8042.debug [HW] Toggle i8042 debug mode
872 i8042.direct [HW] Put keyboard port into non-translated mode
873 i8042.dumbkbd [HW] Pretend that controller can only read data from
874 keyboard and cannot control its state
875 (Don't attempt to blink the leds)
876 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
877 i8042.nokbd [HW] Don't check/create keyboard port
878 i8042.noloop [HW] Disable the AUX Loopback command while probing
880 i8042.nomux [HW] Don't check presence of an active multiplexing
882 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
885 [HW] Frequency with which keyboard LEDs should blink
886 when kernel panics (default is 0.5 sec)
887 i8042.reset [HW] Reset the controller during init and cleanup
888 i8042.unlock [HW] Unlock (ignore) the keylock
892 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
893 indicates that the driver is running on unsupported
895 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
896 does not match list of supported models.
898 [HW] Report power status in /proc/i8k
899 (disabled by default)
900 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
903 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
904 See Documentation/mca.txt.
907 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
909 ide-core.nodma= [HW] (E)IDE subsystem
910 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
911 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
912 .chs .ignore_cable are additional options
913 See Documentation/ide/ide.txt.
915 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
916 See Documentation/ide/ide.txt.
919 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
920 Poll forces a polling idle loop that can slightly
921 improve the performance of waking up a idle CPU, but
922 will use a lot of power and make the system run hot.
924 idle=mwait: On systems which support MONITOR/MWAIT but
925 the kernel chose to not use it because it doesn't save
926 as much power as a normal idle loop, use the
927 MONITOR/MWAIT idle loop anyways. Performance should be
928 the same as idle=poll.
929 idle=halt: Halt is forced to be used for CPU idle.
930 In such case C2/C3 won't be used again.
931 idle=nomwait: Disable mwait for CPU C-states
933 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
934 Claim all unknown PCI IDE storage controllers.
936 ignore_loglevel [KNL]
937 Ignore loglevel setting - this will print /all/
938 kernel messages to the console. Useful for debugging.
941 Set number of hash buckets for inode cache.
944 Format: { "0" | "1" }
945 0 -- integrity auditing messages. (Default)
946 1 -- enable informational integrity auditing messages.
949 Formt: { "sha1" | "md5" }
953 See header of drivers/scsi/in2000.c.
957 Run specified binary instead of /sbin/init as init
960 initcall_debug [KNL] Trace initcalls as they are executed. Useful
961 for working out where the kernel is dying during
964 initrd= [BOOT] Specify the location of the initial ramdisk
966 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
971 iomem= Disable strict checking of access to MMIO memory
972 strict regions from userspace.
988 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
990 Enable intel iommu driver.
992 Disable intel iommu driver.
993 igfx_off [Default Off]
994 By default, gfx is mapped as normal device. If a gfx
995 device has a dedicated DMAR unit, the DMAR unit is
996 bypassed by not enabling DMAR with this option. In
997 this case, gfx device will use physical address for
1000 With this option iommu will not optimize to look
1001 for io virtual address below 32 bit forcing dual
1002 address cycle on pci bus for cards supporting greater
1003 than 32 bit addressing. The default is to look
1004 for translation below 32 bit and if not available
1005 then look in the higher range.
1006 strict [Default Off]
1007 With this option on every unmap_single operation will
1008 result in a hardware IOTLB flush operation as opposed
1009 to batching them for performance.
1011 io_delay= [X86-32,X86-64] I/O delay method
1013 Standard port 0x80 based delay
1015 Alternate port 0xed based delay (needed on some systems)
1017 Simple two microseconds delay
1021 io7= [HW] IO7 for Marvel based alpha systems
1022 See comment before marvel_specify_io7 in
1023 arch/alpha/kernel/core_marvel.c.
1026 See Documentation/filesystems/nfsroot.txt.
1028 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1029 See comment before ip2_setup() in
1030 drivers/char/ip2/ip2base.c.
1032 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1033 See header of drivers/scsi/ips.c.
1035 ports= [IP_VS_FTP] IPVS ftp helper module
1037 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1039 Format: <port>,<port>....
1042 When an interrupt is not handled search all handlers
1043 for it. Intended to get systems with badly broken
1047 When an interrupt is not handled search all handlers
1048 for it. Also check all handlers each timer
1049 interrupt. Intended to get systems with badly broken
1053 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1055 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1057 <cpu number>,...,<cpu number>
1059 <cpu number>-<cpu number>
1060 (must be a positive range in ascending order)
1062 <cpu number>,...,<cpu number>-<cpu number>
1064 This option can be used to specify one or more CPUs
1065 to isolate from the general SMP balancing and scheduling
1066 algorithms. You can move a process onto or off an
1067 "isolated" CPU via the CPU affinity syscalls or cpuset.
1068 <cpu number> begins at 0 and the maximum value is
1069 "number of CPUs in system - 1".
1071 This option is the preferred way to isolate CPUs. The
1072 alternative -- manually setting the CPU mask of all
1073 tasks in the system -- can cause problems and
1074 suboptimal load balancer performance.
1078 js= [HW,JOY] Analog joystick
1079 See Documentation/input/joystick.txt.
1081 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1082 specifies the amount of memory usable by the kernel
1083 for non-movable allocations. The requested amount is
1084 spread evenly throughout all nodes in the system. The
1085 remaining memory in each node is used for Movable
1086 pages. In the event, a node is too small to have both
1087 kernelcore and Movable pages, kernelcore pages will
1088 take priority and other nodes will have a larger number
1089 of kernelcore pages. The Movable zone is used for the
1090 allocation of pages that may be reclaimed or moved
1091 by the page migration subsystem. This means that
1092 HugeTLB pages may not be allocated from this zone.
1093 Note that allocations like PTEs-from-HighMem still
1094 use the HighMem zone if it exists, and the Normal
1095 zone if it does not.
1097 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1098 is similar to kernelcore except it specifies the
1099 amount of memory used for migratable allocations.
1100 If both kernelcore and movablecore is specified,
1101 then kernelcore will be at *least* the specified
1102 value but may be more. If movablecore on its own
1103 is specified, the administrator must be careful
1104 that the amount of memory usable for all allocations
1109 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1112 kgdboc= [HW] kgdb over consoles.
1113 Requires a tty driver that supports console polling.
1114 (only serial suported for now)
1115 Format: <serial_device>[,baud]
1117 kmac= [MIPS] korina ethernet MAC address.
1118 Configure the RouterBoard 532 series on-chip
1119 Ethernet adapter MAC address.
1125 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1128 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1131 libata.dma= [LIBATA] DMA control
1132 libata.dma=0 Disable all PATA and SATA DMA
1133 libata.dma=1 PATA and SATA Disk DMA only
1134 libata.dma=2 ATAPI (CDROM) DMA only
1135 libata.dma=4 Compact Flash DMA only
1136 Combinations also work, so libata.dma=3 enables DMA
1137 for disks and CDROMs, but not CFs.
1139 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1143 libata.force= [LIBATA] Force configurations. The format is comma
1144 separated list of "[ID:]VAL" where ID is
1145 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1146 matching port, link or device. Basically, it matches
1147 the ATA ID string printed on console by libata. If
1148 the whole ID part is omitted, the last PORT and DEVICE
1149 values are used. If ID hasn't been specified yet, the
1150 configuration applies to all ports, links and devices.
1152 If only DEVICE is omitted, the parameter applies to
1153 the port and all links and devices behind it. DEVICE
1154 number of 0 either selects the first device or the
1155 first fan-out link behind PMP device. It does not
1156 select the host link. DEVICE number of 15 selects the
1157 host link and device attached to it.
1159 The VAL specifies the configuration to force. As long
1160 as there's no ambiguity shortcut notation is allowed.
1161 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1162 The following configurations can be forced.
1164 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1165 Any ID with matching PORT is used.
1167 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1169 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1170 udma[/][16,25,33,44,66,100,133] notation is also
1173 * [no]ncq: Turn on or off NCQ.
1175 * nohrst, nosrst, norst: suppress hard, soft
1178 If there are multiple matching configurations changing
1179 the same attribute, the last one is used.
1181 lmb=debug [KNL] Enable lmb debug messages.
1183 load_ramdisk= [RAM] List of ramdisks to load from floppy
1184 See Documentation/blockdev/ramdisk.txt.
1186 lockd.nlm_grace_period=P [NFS] Assign grace period.
1189 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1192 lockd.nlm_timeout=T [NFS] Assign timeout value.
1195 lockd.nlm_udpport=M [NFS] Assign UDP port.
1198 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1201 loglevel= All Kernel Messages with a loglevel smaller than the
1202 console loglevel will be printed to the console. It can
1203 also be changed with klogd or other programs. The
1204 loglevels are defined as follows:
1206 0 (KERN_EMERG) system is unusable
1207 1 (KERN_ALERT) action must be taken immediately
1208 2 (KERN_CRIT) critical conditions
1209 3 (KERN_ERR) error conditions
1210 4 (KERN_WARNING) warning conditions
1211 5 (KERN_NOTICE) normal but significant condition
1212 6 (KERN_INFO) informational
1213 7 (KERN_DEBUG) debug-level messages
1215 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1216 Format: { n | nk | nM }
1217 n must be a power of two. The default size
1218 is set in the kernel config file.
1220 logo.nologo [FB] Disables display of the built-in Linux logo.
1221 This may be used to provide more screen space for
1222 kernel log messages and is useful when debugging
1223 kernel boot problems.
1225 lp=0 [LP] Specify parallel ports to use, e.g,
1226 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1227 lp=reset first parallel port). 'lp=0' disables the
1228 lp=auto printer driver. 'lp=reset' (which can be
1229 specified in addition to the ports) causes
1230 attached printers to be reset. Using
1231 lp=port1,port2,... specifies the parallel ports
1232 to associate lp devices with, starting with
1233 lp0. A port specification may be 'none' to skip
1234 that lp device, or a parport name such as
1235 'parport0'. Specifying 'lp=auto' instead of a
1236 port specification list means that device IDs
1237 from each port should be examined, to see if
1238 an IEEE 1284-compliant printer is attached; if
1239 so, the driver will manage that printer.
1240 See also header of drivers/char/lp.c.
1243 Sets loops_per_jiffy to given constant, thus avoiding
1244 time-consuming boot-time autodetection (up to 250 ms per
1245 CPU). 0 enables autodetection (default). To determine
1246 the correct value for your kernel, boot with normal
1247 autodetection and see what value is printed. Note that
1248 on SMP systems the preset will be applied to all CPUs,
1249 which is likely to cause problems if your CPUs need
1250 significantly divergent settings. An incorrect value
1251 will cause delays in the kernel to be wrong, leading to
1252 unpredictable I/O errors and other breakage. Although
1253 unlikely, in the extreme case this might damage your
1257 Format: <io>,<irq>,<dma>
1259 mac5380= [HW,SCSI] Format:
1260 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1262 machvec= [IA64] Force the use of a particular machine-vector
1263 (machvec) in a generic kernel.
1264 Example: machvec=hpzx1_swiotlb
1266 max_loop= [LOOP] Maximum number of loopback devices that can
1270 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1271 should make use of. maxcpus=n : n >= 0 limits the
1272 kernel to using 'n' processors. n=0 is a special case,
1273 it is equivalent to "nosmp", which also disables
1276 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1277 or equal to this physical address is ignored.
1279 max_luns= [SCSI] Maximum number of LUNs to probe.
1280 Should be between 1 and 2^32-1.
1283 [SCSI] Maximum number of LUNs received.
1284 Should be between 1 and 16384.
1288 mce [X86-32] Machine Check Exception
1290 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1292 md= [HW] RAID subsystems devices and level
1293 See Documentation/md.txt.
1296 Format: <first>,<last>
1297 Specifies range of consoles to be captured by the MDA.
1299 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1300 Amount of memory to be used when the kernel is not able
1301 to see the whole system memory or for test.
1302 [X86-32] Use together with memmap= to avoid physical
1303 address space collisions. Without memmap= PCI devices
1304 could be placed at addresses belonging to unused RAM.
1306 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1310 [KNL,SH] Allow user to override the default size for
1311 per-device physically contiguous DMA buffers.
1313 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1314 E820 memory map, as specified by the user.
1315 Such memmap=exactmap lines can be constructed based on
1316 BIOS output or other requirements. See the memmap=nn@ss
1319 memmap=nn[KMG]@ss[KMG]
1320 [KNL] Force usage of a specific region of memory
1321 Region of memory to be used, from ss to ss+nn.
1323 memmap=nn[KMG]#ss[KMG]
1324 [KNL,ACPI] Mark specific memory as ACPI data.
1325 Region of memory to be used, from ss to ss+nn.
1327 memmap=nn[KMG]$ss[KMG]
1328 [KNL,ACPI] Mark specific memory as reserved.
1329 Region of memory to be used, from ss to ss+nn.
1330 Example: Exclude memory from 0x18690000-0x1869ffff
1331 memmap=64K$0x18690000
1333 memmap=0x10000$0x18690000
1335 memory_corruption_check=0/1 [X86]
1336 Some BIOSes seem to corrupt the first 64k of
1337 memory when doing things like suspend/resume.
1338 Setting this option will scan the memory
1339 looking for corruption. Enabling this will
1340 both detect corruption and prevent the kernel
1341 from using the memory being corrupted.
1342 However, its intended as a diagnostic tool; if
1343 repeatable BIOS-originated corruption always
1344 affects the same memory, you can use memmap=
1345 to prevent the kernel from using that memory.
1347 memory_corruption_check_size=size [X86]
1348 By default it checks for corruption in the low
1349 64k, making this memory unavailable for normal
1350 use. Use this parameter to scan for
1351 corruption in more or less memory.
1353 memory_corruption_check_period=seconds [X86]
1354 By default it checks for corruption every 60
1355 seconds. Use this parameter to check at some
1356 other rate. 0 disables periodic checking.
1358 memtest= [KNL,X86] Enable memtest
1360 default : 0 <disable>
1361 Specifies the number of memtest passes to be
1362 performed. Each pass selects another test
1363 pattern from a given set of patterns. Memtest
1364 fills the memory with this pattern, validates
1365 memory contents and reserves bad memory
1366 regions that are detected.
1368 meye.*= [HW] Set MotionEye Camera parameters
1369 See Documentation/video4linux/meye.txt.
1371 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1372 Multi-Function General Purpose Timers on AMD Geode
1375 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1376 the BIOS has incorrectly applied a workaround. TinyBIOS
1377 version 0.98 is known to be affected, 0.99 fixes the
1378 problem by letting the user disable the workaround.
1382 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1383 physical address is ignored.
1386 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1387 parameter allows control of the logging verbosity for
1388 the additional memory initialisation checks. A value
1389 of 0 disables mminit logging and a level of 4 will
1390 log everything. Information is printed at KERN_DEBUG
1391 so loglevel=8 may also need to be specified.
1394 [MOUSE] Maximum time between finger touching and
1395 leaving touchpad surface for touch to be considered
1396 a tap and be reported as a left button click (for
1397 touchpads working in absolute mode only).
1399 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1400 reporting absolute coordinates, such as tablets
1401 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1402 reporting absolute coordinates, such as tablets
1407 MTD_Partition= [MTD]
1408 Format: <name>,<region-number>,<size>,<offset>
1410 MTD_Region= [MTD] Format:
1411 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1414 See drivers/mtd/cmdlinepart.c.
1417 ARM/S3C2412 JIVE boot control
1419 See arch/arm/mach-s3c2412/mach-jive.c
1421 mtouchusb.raw_coordinates=
1422 [HW] Make the MicroTouch USB driver use raw coordinates
1423 ('y', default) or cooked coordinates ('n')
1425 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1428 See header of drivers/scsi/NCR_D700.c.
1432 ncr53c400= [HW,SCSI]
1434 ncr53c400a= [HW,SCSI]
1436 ncr53c406a= [HW,SCSI]
1438 ncr53c8xx= [HW,SCSI]
1440 netdev= [NET] Network devices parameters
1441 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1442 Note that mem_start is often overloaded to mean
1443 something different and driver-specific.
1444 This usage is only documented in each driver source
1448 [NETFILTER] Enable connection tracking flow accounting
1449 0 to disable accounting
1450 1 to enable accounting
1451 Default value depends on CONFIG_NF_CT_ACCT that is
1452 going to be removed in 2.6.29.
1455 See Documentation/filesystems/nfsroot.txt.
1457 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1458 See Documentation/filesystems/nfsroot.txt.
1460 nfs.callback_tcpport=
1461 [NFS] set the TCP port on which the NFSv4 callback
1462 channel should listen.
1464 nfs.idmap_cache_timeout=
1465 [NFS] set the maximum lifetime for idmapper cache
1469 [NFS] enable 64-bit inode numbers.
1470 If zero, the NFS client will fake up a 32-bit inode
1471 number for the readdir() and stat() syscalls instead
1472 of returning the full 64-bit number.
1473 The default is to return 64-bit inode numbers.
1475 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1476 when a NMI is triggered.
1477 Format: [state][,regs][,debounce][,die]
1479 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1480 Format: [panic,][num]
1482 0 - turn nmi_watchdog off
1483 1 - use the IO-APIC timer for the NMI watchdog
1484 2 - use the local APIC for the NMI watchdog using
1485 a performance counter. Note: This will use one performance
1486 counter and the local APIC's performance vector.
1487 When panic is specified panic when an NMI watchdog timeout occurs.
1488 This is useful when you use a panic=... timeout and need the box
1490 Instead of 1 and 2 it is possible to use the following
1491 symbolic names: lapic and ioapic
1492 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1494 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1495 emulation library even if a 387 maths coprocessor
1498 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1499 caches in the slab allocator. Saves per-node memory,
1500 but will impact performance.
1504 noapic [SMP,APIC] Tells the kernel to not make use of any
1505 IOAPICs that may be present in the system.
1507 nobats [PPC] Do not use BATs for mapping kernel lowmem
1508 on "Classic" PPC cores.
1512 nodelayacct [KNL] Disable per-task delay accounting
1514 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1516 nodsp [SH] Disable hardware DSP at boot time.
1518 noefi [X86-32,X86-64] Disable EFI runtime services support.
1522 noexec [X86-32,X86-64]
1523 On X86-32 available only on PAE configured kernels.
1524 noexec=on: enable non-executable mappings (default)
1525 noexec=off: disable non-executable mappings
1528 This affects only 32-bit executables.
1529 noexec32=on: enable non-executable mappings (default)
1530 read doesn't imply executable mappings
1531 noexec32=off: disable non-executable mappings
1532 read implies executable mappings
1534 nofpu [SH] Disable hardware FPU at boot time.
1536 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1537 register save and restore. The kernel will only save
1538 legacy floating-point registers on task switch.
1540 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1542 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1543 wfi(ARM) instruction doesn't work correctly and not to
1544 use it. This is also useful when using JTAG debugger.
1546 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1547 instruction doesn't work correctly and not to
1550 no_file_caps Tells the kernel not to honor file capabilities. The
1551 only way then for a file to be executed with privilege
1552 is to be setuid root or executed by root.
1554 nohalt [IA-64] Tells the kernel not to use the power saving
1555 function PAL_HALT_LIGHT when idle. This increases
1556 power-consumption. On the positive side, it reduces
1557 interrupt wake-up latency, which may improve performance
1558 in certain environments such as networked servers or
1561 nohz= [KNL] Boottime enable/disable dynamic ticks
1562 Valid arguments: on, off
1565 noirqdebug [X86-32] Disables the code which attempts to detect and
1566 disable unhandled interrupt sources.
1568 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1569 broken timer IRQ sources.
1571 noisapnp [ISAPNP] Disables ISA PnP code.
1573 noinitrd [RAM] Tells the kernel not to load any configured
1578 nojitter [IA64] Disables jitter checking for ITC timers.
1580 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1582 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1584 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1586 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1587 default x2apic cluster mode on platforms
1590 noltlbs [PPC] Do not use large page/tlb entries for kernel
1591 lowmem mapping on PPC40x.
1593 nomca [IA-64] Disable machine check abort handling
1595 nomce [X86-32] Machine Check Exception
1597 nomfgpt [X86-32] Disable Multi-Function General Purpose
1598 Timer usage (for AMD Geode machines).
1600 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1602 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1603 with UP alternatives
1605 noresidual [PPC] Don't use residual data on PReP machines.
1607 noresume [SWSUSP] Disables resume and restores original swap
1610 no-scroll [VGA] Disables scrollback.
1611 This is required for the Braillex ib80-piezo Braille
1612 reader made by F.H. Papenmeier (Germany).
1616 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1618 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1619 and disable the IO APIC. legacy for "maxcpus=0".
1621 nosoftlockup [KNL] Disable the soft-lockup detector.
1623 noswapaccount [KNL] Disable accounting of swap in memory resource
1624 controller. (See Documentation/cgroups/memory.txt)
1626 nosync [HW,M68K] Disables sync negotiation for all devices.
1628 notsc [BUGS=X86-32] Disable Time Stamp Counter
1630 nousb [USB] Disable the USB subsystem
1634 nptcg= [IA64] Override max number of concurrent global TLB
1635 purges which is reported from either PAL_VM_SUMMARY or
1638 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1639 one of ['zone', 'node', 'default'] can be specified
1640 This can be set from sysctl after boot.
1641 See Documentation/sysctl/vm.txt for details.
1643 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1645 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1646 See Documentation/debugging-via-ohci1394.txt for more
1649 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1650 Rather than timing out after 20 ms if an EC
1651 command is not properly ACKed, override the length
1652 of the timeout. We have interrupts disabled while
1653 waiting for the ACK, so if this is set too high
1654 interrupts *may* be lost!
1659 oprofile.timer= [HW]
1660 Use timer interrupt instead of performance counters
1662 osst= [HW,SCSI] SCSI Tape Driver
1663 Format: <buffer_size>,<write_threshold>
1664 See also Documentation/scsi/st.txt.
1666 panic= [KNL] Kernel behaviour on panic
1669 parkbd.port= [HW] Parallel port number the keyboard adapter is
1670 connected to, default is 0.
1672 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1673 0 for XT, 1 for AT (default is AT).
1676 parport= [HW,PPT] Specify parallel ports. 0 disables.
1677 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1678 Use 'auto' to force the driver to use any
1679 IRQ/DMA settings detected (the default is to
1680 ignore detected IRQ/DMA settings because of
1681 possible conflicts). You can specify the base
1682 address, IRQ, and DMA settings; IRQ and DMA
1683 should be numbers, or 'auto' (for using detected
1684 settings on that particular port), or 'nofifo'
1685 (to avoid using a FIFO even if it is detected).
1686 Parallel ports are assigned in the order they
1687 are specified on the command line, starting
1690 parport_init_mode= [HW,PPT]
1691 Configure VIA parallel port to operate in
1692 a specific mode. This is necessary on Pegasos
1693 computer where firmware has no options for setting
1694 up parallel port mode and sets it to spp.
1695 Currently this function knows 686a and 8231 chips.
1696 Format: [spp|ps2|epp|ecp|ecpepp]
1698 pas2= [HW,OSS] Format:
1699 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1702 See header of drivers/scsi/pas16.c.
1705 Halt all CPUs after the first oops has been printed for
1706 the specified number of seconds. This is to be used if
1707 your oopses keep scrolling off the screen.
1712 See header of drivers/block/paride/pcd.c.
1713 See also Documentation/blockdev/paride.txt.
1715 pci=option[,option...] [PCI] various PCI subsystem options:
1716 earlydump [X86] dump PCI config space before the kernel
1718 off [X86] don't probe for the PCI bus
1719 bios [X86-32] force use of PCI BIOS, don't access
1720 the hardware directly. Use this if your machine
1721 has a non-standard PCI host bridge.
1722 nobios [X86-32] disallow use of PCI BIOS, only direct
1723 hardware access methods are allowed. Use this
1724 if you experience crashes upon bootup and you
1725 suspect they are caused by the BIOS.
1726 conf1 [X86] Force use of PCI Configuration
1728 conf2 [X86] Force use of PCI Configuration
1730 noaer [PCIE] If the PCIEAER kernel config parameter is
1731 enabled, this kernel boot option can be used to
1732 disable the use of PCIE advanced error reporting.
1733 nodomains [PCI] Disable support for multiple PCI
1734 root domains (aka PCI segments, in ACPI-speak).
1735 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1737 nomsi [MSI] If the PCI_MSI kernel config parameter is
1738 enabled, this kernel boot option can be used to
1739 disable the use of MSI interrupts system-wide.
1740 noioapicquirk [APIC] Disable all boot interrupt quirks.
1741 Safety option to keep boot IRQs enabled. This
1742 should never be necessary.
1743 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1744 primary IO-APIC for bridges that cannot disable
1745 boot IRQs. This fixes a source of spurious IRQs
1746 when the system masks IRQs.
1747 noioapicreroute [APIC] Disable workaround that uses the
1748 boot IRQ equivalent of an IRQ that connects to
1749 a chipset where boot IRQs cannot be disabled.
1750 The opposite of ioapicreroute.
1751 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1752 routing table. These calls are known to be buggy
1753 on several machines and they hang the machine
1754 when used, but on other computers it's the only
1755 way to get the interrupt routing table. Try
1756 this option if the kernel is unable to allocate
1757 IRQs or discover secondary PCI buses on your
1759 rom [X86] Assign address space to expansion ROMs.
1760 Use with caution as certain devices share
1761 address decoders between ROMs and other
1763 norom [X86] Do not assign address space to
1764 expansion ROMs that do not already have
1765 BIOS assigned address ranges.
1766 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1767 assigned automatically to PCI devices. You can
1768 make the kernel exclude IRQs of your ISA cards
1770 pirqaddr=0xAAAAA [X86] Specify the physical address
1771 of the PIRQ table (normally generated
1772 by the BIOS) if it is outside the
1773 F0000h-100000h range.
1774 lastbus=N [X86] Scan all buses thru bus #N. Can be
1775 useful if the kernel is unable to find your
1776 secondary buses and you want to tell it
1777 explicitly which ones they are.
1778 assign-busses [X86] Always assign all PCI bus
1779 numbers ourselves, overriding
1780 whatever the firmware may have done.
1781 usepirqmask [X86] Honor the possible IRQ mask stored
1782 in the BIOS $PIR table. This is needed on
1783 some systems with broken BIOSes, notably
1784 some HP Pavilion N5400 and Omnibook XE3
1785 notebooks. This will have no effect if ACPI
1786 IRQ routing is enabled.
1787 noacpi [X86] Do not use ACPI for IRQ routing
1788 or for PCI scanning.
1789 use_crs [X86] Use _CRS for PCI resource
1791 routeirq Do IRQ routing for all PCI devices.
1792 This is normally done in pci_enable_device(),
1793 so this option is a temporary workaround
1794 for broken drivers that don't call it.
1795 skip_isa_align [X86] do not align io start addr, so can
1796 handle more pci cards
1797 firmware [ARM] Do not re-enumerate the bus but instead
1798 just use the configuration from the
1799 bootloader. This is currently used on
1800 IXP2000 systems where the bus has to be
1801 configured a certain way for adjunct CPUs.
1802 noearly [X86] Don't do any early type 1 scanning.
1803 This might help on some broken boards which
1804 machine check when some devices' config space
1805 is read. But various workarounds are disabled
1806 and some IOMMU drivers will not work.
1807 bfsort Sort PCI devices into breadth-first order.
1808 This sorting is done to get a device
1809 order compatible with older (<= 2.4) kernels.
1810 nobfsort Don't sort PCI devices into breadth-first order.
1811 cbiosize=nn[KMG] The fixed amount of bus space which is
1812 reserved for the CardBus bridge's IO window.
1813 The default value is 256 bytes.
1814 cbmemsize=nn[KMG] The fixed amount of bus space which is
1815 reserved for the CardBus bridge's memory
1816 window. The default value is 64 megabytes.
1819 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1820 Specifies alignment and device to reassign
1821 aligned memory resources.
1822 If <order of align> is not specified,
1823 PAGE_SIZE is used as alignment.
1824 PCI-PCI bridge can be specified, if resource
1825 windows need to be expanded.
1827 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1830 force Enable ASPM even on devices that claim not to support it.
1831 WARNING: Forcing ASPM on may cause system lockups.
1833 pcmv= [HW,PCMCIA] BadgePAD 4
1836 See Documentation/blockdev/paride.txt.
1838 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1841 See arch/parisc/kernel/pdc_chassis.c
1844 See Documentation/blockdev/paride.txt.
1847 See Documentation/blockdev/paride.txt.
1849 pirq= [SMP,APIC] Manual mp-table setup
1850 See Documentation/x86/i386/IO-APIC.txt.
1852 plip= [PPT,NET] Parallel port network link
1853 Format: { parport<nr> | timid | 0 }
1854 See also Documentation/parport.txt.
1856 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1857 Override pmtimer IOPort with a hex value.
1861 Enable PNP debug messages. This depends on the
1862 CONFIG_PNP_DEBUG_MESSAGES option.
1868 { on | off | curr | res | no-curr | no-res }
1871 [ISAPNP] Exclude IRQs for the autoconfiguration
1874 [ISAPNP] Exclude DMAs for the autoconfiguration
1876 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1877 Ranges are in pairs (I/O port base and size).
1880 [ISAPNP] Exclude memory regions for the
1882 Ranges are in pairs (memory base and size).
1884 print-fatal-signals=
1885 [KNL] debug: print fatal signals
1886 print-fatal-signals=1: print segfault info to
1890 printk.time= Show timing data prefixed to each printk message line
1891 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1893 profile= [KNL] Enable kernel profiling via /proc/profile
1894 Format: [schedule,]<number>
1895 Param: "schedule" - profile schedule points.
1896 Param: <number> - step/bucket size as a power of 2 for
1897 statistical time based profiling.
1898 Param: "sleep" - profile D-state sleeping (millisecs).
1899 Requires CONFIG_SCHEDSTATS
1900 Param: "kvm" - profile VM exits.
1902 processor.max_cstate= [HW,ACPI]
1903 Limit processor to maximum C-state
1904 max_cstate=9 overrides any DMI blacklist limit.
1906 processor.nocst [HW,ACPI]
1907 Ignore the _CST method to determine C-states,
1908 instead using the legacy FADT method
1910 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1912 See Documentation/blockdev/ramdisk.txt.
1914 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1915 probe for; one of (bare|imps|exps|lifebook|any).
1916 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1918 psmouse.resetafter= [HW,MOUSE]
1919 Try to reset the device after so many bad packets
1922 [HW,MOUSE] Set desired mouse resolution, in dpi.
1923 psmouse.smartscroll=
1924 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1925 0 = disabled, 1 = enabled (default).
1927 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1929 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1932 See Documentation/blockdev/paride.txt.
1935 [KNL] Number of legacy pty's. Overwrites compiled-in
1938 quiet [KNL] Disable most log messages
1943 See Documentation/md.txt.
1945 ramdisk_blocksize= [RAM]
1946 See Documentation/blockdev/ramdisk.txt.
1948 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1949 See Documentation/blockdev/ramdisk.txt.
1951 rcupdate.blimit= [KNL,BOOT]
1952 Set maximum number of finished RCU callbacks to process
1955 rcupdate.qhimark= [KNL,BOOT]
1956 Set threshold of queued
1957 RCU callbacks over which batch limiting is disabled.
1959 rcupdate.qlowmark= [KNL,BOOT]
1960 Set threshold of queued RCU callbacks below which
1961 batch limiting is re-enabled.
1965 Run specified binary instead of /init from the ramdisk,
1966 used for early userspace startup. See initrd.
1968 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1969 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1970 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1973 [KNL, SMP] Set scheduler's default relax_domain_level.
1974 See Documentation/cgroups/cpusets.txt.
1976 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1978 reservetop= [X86-32]
1980 Reserves a hole at the top of the kernel virtual
1983 reset_devices [KNL] Force drivers to reset the underlying device
1984 during initialization.
1987 Specify the partition device for software suspend
1989 resume_offset= [SWSUSP]
1990 Specify the offset from the beginning of the partition
1991 given by "resume=" at which the swap header is located,
1992 in <PAGE_SIZE> units (needed only for swap files).
1993 See Documentation/power/swsusp-and-swap-files.txt
1995 retain_initrd [RAM] Keep initrd memory after extraction
1997 rhash_entries= [KNL,NET]
1998 Set number of hash buckets for route cache
2000 riscom8= [HW,SERIAL]
2001 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2003 ro [KNL] Mount root device read-only on boot
2005 root= [KNL] Root filesystem
2007 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2008 mount the root filesystem
2010 rootflags= [KNL] Set root filesystem mount option string
2012 rootfstype= [KNL] Set root filesystem type
2014 rootwait [KNL] Wait (indefinitely) for root device to show up.
2015 Useful for devices that are detected asynchronously
2016 (e.g. USB and MMC devices).
2018 root_plug.vendor_id=
2019 [ROOTPLUG] Override the default vendor ID
2021 root_plug.product_id=
2022 [ROOTPLUG] Override the default product ID
2025 [ROOTPLUG] Enable debugging output
2027 rw [KNL] Mount root device read-write on boot
2029 S [KNL] Run init in single mode
2032 See drivers/net/irda/sa1100_ir.c.
2034 sbni= [NET] Granch SBNI12 leased line adapter
2036 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2037 Format: <io>[,<timeout>[,<isapnp>]]
2039 scsi_debug_*= [SCSI]
2040 See drivers/scsi/scsi_debug.c.
2042 scsi_default_dev_flags=
2043 [SCSI] SCSI default device flags
2046 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2047 Format: <vendor>:<model>:<flags>
2048 (flags are integer value)
2050 scsi_logging_level= [SCSI] a bit mask of logging levels
2051 See drivers/scsi/scsi_logging.h for bits. Also
2052 settable via sysctl at dev.scsi.logging_level
2053 (/proc/sys/dev/scsi/logging_level).
2054 There is also a nice 'scsi_logging_level' script in the
2055 S390-tools package, available for download at
2056 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2058 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2059 discovered. async scans them in kernel threads,
2060 allowing boot to proceed. none ignores them, expecting
2061 user space to do the scan.
2063 selinux [SELINUX] Disable or enable SELinux at boot time.
2064 Format: { "0" | "1" }
2065 See security/selinux/Kconfig help text.
2068 Default value is set via kernel config option.
2069 If enabled at boot time, /selinux/disable can be used
2070 later to disable prior to initial policy load.
2072 serialnumber [BUGS=X86-32]
2075 Maximal number of shapers.
2077 show_msr= [x86] show boot-time MSR settings
2078 Format: { <integer> }
2079 Show boot-time (BIOS-initialized) MSR settings.
2080 The parameter means the number of CPUs to show,
2081 for example 1 means boot CPU only.
2084 See header of drivers/scsi/sim710.c.
2091 slub_debug[=options[,slabs]] [MM, SLUB]
2092 Enabling slub_debug allows one to determine the
2093 culprit if slab objects become corrupted. Enabling
2094 slub_debug can create guard zones around objects and
2095 may poison objects when not in use. Also tracks the
2096 last alloc / free. For more information see
2097 Documentation/vm/slub.txt.
2099 slub_max_order= [MM, SLUB]
2100 Determines the maximum allowed order for slabs.
2101 A high setting may cause OOMs due to memory
2102 fragmentation. For more information see
2103 Documentation/vm/slub.txt.
2105 slub_min_objects= [MM, SLUB]
2106 The minimum number of objects per slab. SLUB will
2107 increase the slab order up to slub_max_order to
2108 generate a sufficiently large slab able to contain
2109 the number of objects indicated. The higher the number
2110 of objects the smaller the overhead of tracking slabs
2111 and the less frequently locks need to be acquired.
2112 For more information see Documentation/vm/slub.txt.
2114 slub_min_order= [MM, SLUB]
2115 Determines the mininum page order for slabs. Must be
2116 lower than slub_max_order.
2117 For more information see Documentation/vm/slub.txt.
2119 slub_nomerge [MM, SLUB]
2120 Disable merging of slabs with similar size. May be
2121 necessary if there is some reason to distinguish
2122 allocs to different slabs. Debug options disable
2123 merging on their own.
2124 For more information see Documentation/vm/slub.txt.
2127 Format: <io1>[,<io2>[,...,<io8>]]
2129 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2130 attempt to substitute SMP alternatives once at boot.
2132 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2133 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2134 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2135 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2136 smsc-ircc2.ircc_irq= [HW] IRQ line
2137 smsc-ircc2.ircc_dma= [HW] DMA channel
2138 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2139 0: Toshiba Satellite 1800 (GP data pin select)
2140 1: Fast pin select (default)
2143 snd-ad1816a= [HW,ALSA]
2145 snd-ad1848= [HW,ALSA]
2147 snd-ali5451= [HW,ALSA]
2149 snd-als100= [HW,ALSA]
2151 snd-als4000= [HW,ALSA]
2153 snd-azt2320= [HW,ALSA]
2155 snd-cmi8330= [HW,ALSA]
2157 snd-cmipci= [HW,ALSA]
2159 snd-cs4231= [HW,ALSA]
2161 snd-cs4232= [HW,ALSA]
2163 snd-cs4236= [HW,ALSA]
2165 snd-cs4281= [HW,ALSA]
2167 snd-cs46xx= [HW,ALSA]
2169 snd-dt019x= [HW,ALSA]
2171 snd-dummy= [HW,ALSA]
2173 snd-emu10k1= [HW,ALSA]
2175 snd-ens1370= [HW,ALSA]
2177 snd-ens1371= [HW,ALSA]
2179 snd-es968= [HW,ALSA]
2181 snd-es1688= [HW,ALSA]
2183 snd-es18xx= [HW,ALSA]
2185 snd-es1938= [HW,ALSA]
2187 snd-es1968= [HW,ALSA]
2189 snd-fm801= [HW,ALSA]
2191 snd-gusclassic= [HW,ALSA]
2193 snd-gusextreme= [HW,ALSA]
2195 snd-gusmax= [HW,ALSA]
2199 snd-ice1712= [HW,ALSA]
2201 snd-intel8x0= [HW,ALSA]
2203 snd-interwave= [HW,ALSA]
2208 snd-korg1212= [HW,ALSA]
2210 snd-maestro3= [HW,ALSA]
2212 snd-mpu401= [HW,ALSA]
2214 snd-mtpav= [HW,ALSA]
2216 snd-nm256= [HW,ALSA]
2218 snd-opl3sa2= [HW,ALSA]
2226 snd-opti93x= [HW,ALSA]
2230 snd-rme32= [HW,ALSA]
2232 snd-rme96= [HW,ALSA]
2234 snd-rme9652= [HW,ALSA]
2240 snd-sbawe= [HW,ALSA]
2242 snd-serial= [HW,ALSA]
2244 snd-sgalaxy= [HW,ALSA]
2246 snd-sonicvibes= [HW,ALSA]
2251 snd-sun-cs4231= [HW,ALSA]
2253 snd-trident= [HW,ALSA]
2255 snd-usb-audio= [HW,ALSA,USB]
2257 snd-via82xx= [HW,ALSA]
2259 snd-virmidi= [HW,ALSA]
2261 snd-wavefront= [HW,ALSA]
2263 snd-ymfpci= [HW,ALSA]
2266 [KNL] Should the soft-lockup detector generate panics.
2268 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2269 See Documentation/sonypi.txt
2271 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2272 See Documentation/serial/specialix.txt.
2274 spia_io_base= [HW,MTD]
2280 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2282 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2283 See Documentation/scsi/st.txt.
2286 Enabled the stack tracer on boot up.
2290 Set the STI (builtin display/keyboard on the HP-PARISC
2291 machines) console (graphic card) which should be used
2292 as the initial boot-console.
2293 See also comment in drivers/video/console/sticore.c.
2296 See comment in drivers/video/console/sticore.c.
2299 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2303 Control how the NFS server code allocates CPUs to
2304 service thread pools. Depending on how many NICs
2305 you have and where their interrupts are bound, this
2306 option will affect which CPUs will do NFS serving.
2307 Note: this parameter cannot be changed while the
2308 NFS server is running.
2310 auto the server chooses an appropriate mode
2311 automatically using heuristics
2312 global a single global pool contains all CPUs
2313 percpu one pool for each CPU
2314 pernode one pool for each NUMA node (equivalent
2315 to global on non-NUMA machines)
2317 swiotlb= [IA-64] Number of I/O TLB slabs
2321 sym53c416= [HW,SCSI]
2322 See header of drivers/scsi/sym53c416.c.
2324 sysrq_always_enabled
2326 Ignore sysrq setting - this boot parameter will
2327 neutralize any effect of /proc/sys/kernel/sysrq.
2328 Useful for debugging.
2331 See header of drivers/scsi/t128.c.
2335 test_suspend= [SUSPEND]
2336 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2337 standby suspend) as the system sleep state to briefly
2338 enter during system startup. The system is woken from
2339 this state using a wakeup-capable RTC alarm.
2341 thash_entries= [KNL,NET]
2342 Set number of hash buckets for TCP connection
2344 thermal.act= [HW,ACPI]
2345 -1: disable all active trip points in all thermal zones
2346 <degrees C>: override all lowest active trip points
2348 thermal.crt= [HW,ACPI]
2349 -1: disable all critical trip points in all thermal zones
2350 <degrees C>: override all critical trip points
2352 thermal.nocrt= [HW,ACPI]
2353 Set to disable actions on ACPI thermal zone
2354 critical and hot trip points.
2356 thermal.off= [HW,ACPI]
2357 1: disable ACPI thermal control
2359 thermal.psv= [HW,ACPI]
2360 -1: disable all passive trip points
2361 <degrees C>: override all passive trip points to this
2364 thermal.tzp= [HW,ACPI]
2365 Specify global default ACPI thermal zone polling rate
2366 <deci-seconds>: poll all this frequency
2367 0: no polling (default)
2370 See comment before function dc390_setup() in
2371 drivers/scsi/tmscsim.c.
2375 Specify if the kernel should make use of the cpu
2376 topology informations if the hardware supports these.
2377 The scheduler will make use of these informations and
2378 e.g. base its process migration decisions on it.
2383 trix= [HW,OSS] MediaTrix AudioTrix Pro
2385 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2387 tsc= Disable clocksource-must-verify flag for TSC.
2389 [x86] reliable: mark tsc clocksource as reliable, this
2390 disables clocksource verification at runtime.
2391 Used to enable high-resolution timer mode on older
2392 hardware, and in virtualized environment.
2394 turbografx.map[2|3]= [HW,JOY]
2395 TurboGraFX parallel port interface
2397 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2398 See also Documentation/input/joystick-parport.txt
2400 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2401 See header of drivers/scsi/u14-34f.c.
2410 [USB] Ignore overcurrent events (default N).
2411 Some badly-designed motherboards generate lots of
2412 bogus events, for ports that aren't wired to
2413 anything. Set this parameter to avoid log spamming.
2414 Note that genuine overcurrent events won't be
2419 Set unknown_nmi_panic=1 early on boot.
2421 usbcore.autosuspend=
2422 [USB] The autosuspend time delay (in seconds) used
2423 for newly-detected USB devices (default 2). This
2424 is the time required before an idle device will be
2425 autosuspended. Devices for which the delay is set
2426 to a negative value won't be autosuspended at all.
2428 usbcore.usbfs_snoop=
2429 [USB] Set to log all usbfs traffic (default 0 = off).
2431 usbcore.blinkenlights=
2432 [USB] Set to cycle leds on hubs (default 0 = off).
2434 usbcore.old_scheme_first=
2435 [USB] Start with the old device initialization
2436 scheme (default 0 = off).
2438 usbcore.use_both_schemes=
2439 [USB] Try the other device initialization scheme
2440 if the first one fails (default 1 = enabled).
2442 usbcore.initial_descriptor_timeout=
2443 [USB] Specifies timeout for the initial 64-byte
2444 USB_REQ_GET_DESCRIPTOR request in milliseconds
2445 (default 5000 = 5.0 seconds).
2448 [USBHID] The interval which mice are to be polled at.
2450 usb-storage.delay_use=
2451 [UMS] The delay in seconds before a new device is
2452 scanned for Logical Units (default 5).
2455 [UMS] A list of quirks entries to supplement or
2456 override the built-in unusual_devs list. List
2457 entries are separated by commas. Each entry has
2458 the form VID:PID:Flags where VID and PID are Vendor
2459 and Product ID values (4-digit hex numbers) and
2460 Flags is a set of characters, each corresponding
2461 to a common usb-storage quirk flag as follows:
2462 a = SANE_SENSE (collect more than 18 bytes
2464 c = FIX_CAPACITY (decrease the reported
2465 device capacity by one sector);
2466 h = CAPACITY_HEURISTICS (decrease the
2467 reported device capacity by one
2468 sector if the number is odd);
2469 i = IGNORE_DEVICE (don't bind to this
2471 l = NOT_LOCKABLE (don't try to lock and
2472 unlock ejectable media);
2473 m = MAX_SECTORS_64 (don't transfer more
2474 than 64 sectors = 32 KB at a time);
2475 o = CAPACITY_OK (accept the capacity
2476 reported by the device);
2477 r = IGNORE_RESIDUE (the device reports
2478 bogus residue values);
2479 s = SINGLE_LUN (the device has only one
2481 w = NO_WP_DETECT (don't test whether the
2482 medium is write-protected).
2483 Example: quirks=0419:aaf5:rl,0421:0433:rc
2485 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2486 kernel's map of available physical RAM.
2488 vdso= [X86-32,SH,x86-64]
2489 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2490 vdso=1: enable VDSO (default)
2491 vdso=0: disable VDSO mapping
2493 vdso32= [X86-32,X86-64]
2494 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2495 vdso32=1: enable 32-bit VDSO (default)
2496 vdso32=0: disable 32-bit VDSO mapping
2499 vector=percpu: enable percpu vector domain
2501 video= [FB] Frame buffer configuration
2502 See Documentation/fb/modedb.txt.
2504 vga= [BOOT,X86-32] Select a particular video mode
2505 See Documentation/x86/boot.txt and
2506 Documentation/svga.txt.
2507 Use vga=ask for menu.
2508 This is actually a boot loader parameter; the value is
2509 passed to the kernel using a special protocol.
2511 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2512 size of <nn>. This can be used to increase the
2513 minimum size (128MB on x86). It can also be used to
2514 decrease the size and leave more room for directly
2517 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2520 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2523 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2526 waveartist= [HW,OSS]
2527 Format: <io>,<irq>,<dma>,<dma2>
2530 See header of drivers/scsi/wd33c93.c.
2533 See header of drivers/scsi/wd7000.c.
2536 See Documentation/watchdog/wdt.txt.
2538 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2539 xd_geo= See header of drivers/block/xd.c.
2541 xirc2ps_cs= [NET,PCMCIA]
2543 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2545 norandmaps Don't use address space randomization. Equivalent to
2546 echo 0 > /proc/sys/kernel/randomize_va_space
2548 ______________________________________________________________________
2552 Add documentation for ALSA options.
2553 Add more DRM drivers.