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 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend is enabled.
91 TS Appropriate touchscreen support is enabled.
92 USB USB support is enabled.
93 USBHID USB Human Interface Device support is enabled.
94 V4L Video For Linux support is enabled.
95 VGA The VGA console has been enabled.
96 VT Virtual terminal support is enabled.
97 WDT Watchdog support is enabled.
98 XT IBM PC/XT MFM hard disk support is enabled.
99 X86-32 X86-32, aka i386 architecture is enabled.
100 X86-64 X86-64 architecture is enabled.
101 More X86-64 boot options can be found in
102 Documentation/x86_64/boot-options.txt .
104 In addition, the following text indicates that the option:
106 BUGS= Relates to possible processor bugs on the said processor.
107 KNL Is a kernel start-up parameter.
108 BOOT Is a boot loader parameter.
110 Parameters denoted with BOOT are actually interpreted by the boot
111 loader, and have no meaning to the kernel directly.
112 Do not modify the syntax of boot loader parameters without extreme
113 need or coordination with <Documentation/i386/boot.txt>.
115 There are also arch-specific kernel-parameters not documented here.
116 See for example <Documentation/x86_64/boot-options.txt>.
118 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
119 a trailing = on the name of any parameter states that that parameter will
120 be entered as an environment variable, whereas its absence indicates that
121 it will appear as a kernel argument readable via /proc/cmdline by programs
122 running once the system is up.
124 The number of kernel parameters is not limited, but the length of the
125 complete command line (parameters including spaces etc.) is limited to
126 a fixed number of characters. This limit depends on the architecture
127 and is between 256 and 4096 characters. It is defined in the file
128 ./include/asm/setup.h as COMMAND_LINE_SIZE.
131 acpi= [HW,ACPI,X86-64,i386]
132 Advanced Configuration and Power Interface
133 Format: { force | off | ht | strict | noirq }
134 force -- enable ACPI if default was off
135 off -- disable ACPI if default was on
136 noirq -- do not use ACPI for IRQ routing
137 ht -- run only enough ACPI to enable Hyper Threading
138 strict -- Be less tolerant of platforms that are not
139 strictly ACPI specification compliant.
141 See also Documentation/pm.txt, pci=noacpi
143 acpi_apic_instance= [ACPI, IOAPIC]
145 2: use 2nd APIC table, if available
146 1,0: use 1st APIC table
149 acpi_sleep= [HW,ACPI] Sleep options
150 Format: { s3_bios, s3_mode }
151 See Documentation/power/video.txt
153 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
154 Format: { level | edge | high | low }
156 acpi_irq_balance [HW,ACPI]
157 ACPI will balance active IRQs
160 acpi_irq_nobalance [HW,ACPI]
161 ACPI will not move active IRQs (default)
164 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
166 Format: <irq>,<irq>...
168 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
169 Format: <irq>,<irq>...
171 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
173 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
174 Format: To spoof as Windows 98: ="Microsoft Windows"
176 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
177 acpi_osi="string1" # add string1 -- only one string
178 acpi_osi="!string2" # remove built-in string2
179 acpi_osi= # disable all strings
181 acpi_serialize [HW,ACPI] force serialization of AML methods
183 acpi_skip_timer_override [HW,ACPI]
184 Recognize and ignore IRQ0/pin2 Interrupt Override.
185 For broken nForce2 BIOS resulting in XT-PIC timer.
186 acpi_use_timer_override [HW,ACPI}
187 Use timer override. For some broken Nvidia NF5 boards
188 that require a timer override, but don't have
191 acpi.debug_layer= [HW,ACPI]
193 Each bit of the <int> indicates an ACPI debug layer,
194 1: enable, 0: disable. It is useful for boot time
195 debugging. After system has booted up, it can be set
196 via /sys/module/acpi/parameters/debug_layer.
197 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
198 Available bits (add the numbers together) to enable debug output
199 for specific parts of the ACPI subsystem:
200 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
201 0x10 namespace 0x20 parser 0x40 dispatcher
202 0x80 executer 0x100 resources 0x200 acpica debugger
203 0x400 os services 0x800 acpica disassembler.
204 The number can be in decimal or prefixed with 0x in hex.
205 Warning: Many of these options can produce a lot of
206 output and make your system unusable. Be very careful.
208 acpi.debug_level= [HW,ACPI]
210 Each bit of the <int> indicates an ACPI debug level,
211 1: enable, 0: disable. It is useful for boot time
212 debugging. After system has booted up, it can be set
213 via /sys/module/acpi/parameters/debug_level.
214 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
215 Available bits (add the numbers together) to enable different
216 debug output levels of the ACPI subsystem:
217 0x01 error 0x02 warn 0x04 init 0x08 debug object
218 0x10 info 0x20 init names 0x40 parse 0x80 load
219 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
220 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
221 0x10000 resources 0x20000 user requests 0x40000 package.
222 The number can be in decimal or prefixed with 0x in hex.
223 Warning: Many of these options can produce a lot of
224 output and make your system unusable. Be very careful.
226 acpi_pm_good [X86-32,X86-64]
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
232 { off | try_unsupported }
233 off: disable AGP support
234 try_unsupported: try to drive unsupported chipsets
235 (may crash computer or cause data corruption)
237 enable_timer_pin_1 [i386,x86-64]
238 Enable PIN 1 of APIC timer
239 Can be useful to work around chipset bugs
240 (in particular on some ATI chipsets).
241 The kernel tries to set a reasonable default.
243 disable_timer_pin_1 [i386,x86-64]
244 Disable PIN 1 of APIC timer
245 Can be useful to work around chipset bugs.
248 Format: <io>,<irq>,<dma>,<dma2>,<type>
251 See header of drivers/scsi/advansys.c.
253 advwdt= [HW,WDT] Advantech WDT
254 Format: <iostart>,<iostop>
256 aedsp16= [HW,OSS] Audio Excel DSP 16
257 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
258 See also header of sound/oss/aedsp16.c.
261 See Documentation/scsi/aha152x.txt.
264 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
267 See Documentation/scsi/aic7xxx.txt.
270 See Documentation/scsi/aic79xx.txt.
272 amijoy.map= [HW,JOY] Amiga joystick support
273 Map of devices attached to JOY0DAT and JOY1DAT
275 See also Documentation/kernel/input/joystick.txt
277 analog.map= [HW,JOY] Analog joystick and gamepad support
278 Specifies type or capabilities of an analog joystick
279 connected to one of 16 gameports
280 Format: <type1>,<type2>,..<type16>
283 Power management functions (SPARCstation-4/5 + deriv.)
285 Disable APC CPU standby support. SPARCstation-Fox does
286 not play well with APC CPU idle - disable it if you have
287 APC and your system crashes randomly.
289 apic= [APIC,i386] Advanced Programmable Interrupt Controller
290 Change the output verbosity whilst booting
291 Format: { quiet (default) | verbose | debug }
292 Change the amount of debugging information output
293 when initialising the APIC and IO-APIC components.
295 apm= [APM] Advanced Power Management
296 See header of arch/i386/kernel/apm.c.
298 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
299 Format: <io>,<irq>,<nodeID>
303 atarimouse= [HW,MOUSE] Atari Mouse
305 atascsi= [HW,SCSI] Atari SCSI
307 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
308 EzKey and similar keyboards
310 atkbd.reset= [HW] Reset keyboard during initialization
312 atkbd.set= [HW] Select keyboard code set
313 Format: <int> (2 = AT (default), 3 = PS/2)
315 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
318 atkbd.softraw= [HW] Choose between synthetic and real raw mode
319 Format: <bool> (0 = real, 1 = synthetic (default))
321 atkbd.softrepeat= [HW]
322 Use software keyboard repeat
326 baycom_epp= [HW,AX25]
329 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
331 See header of drivers/net/hamradio/baycom_par.c.
333 baycom_ser_fdx= [HW,AX25]
334 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
335 Format: <io>,<irq>,<mode>[,<baud>]
336 See header of drivers/net/hamradio/baycom_ser_fdx.c.
338 baycom_ser_hdx= [HW,AX25]
339 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
340 Format: <io>,<irq>,<mode>
341 See header of drivers/net/hamradio/baycom_ser_hdx.c.
343 boot_delay= Milliseconds to delay each printk during boot.
344 Values larger than 10 seconds (10000) are changed to
348 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
349 bttv.radio= Most important insmod options are available as
351 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
352 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
355 See drivers/scsi/BusLogic.c, comment before function
356 BusLogic_ParseDriverOptions().
358 c101= [NET] Moxa C101 synchronous serial card
360 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
361 Sometimes CPU hardware bugs make them report the cache
362 size incorrectly. The kernel will attempt work arounds
363 to fix known problems, but for some CPUs it is not
364 possible to determine what the correct size should be.
365 This option provides an override for these situations.
368 [SECURITY] Disable capabilities. This would normally
369 be used only if an alternative security model is to be
370 configured. Potentially dangerous and should only be
371 used if you are entirely sure of the consequences.
373 ccw_timeout_log [S390]
374 See Documentation/s390/CommonIO for details.
376 checkreqprot [SELINUX] Set initial checkreqprot flag value.
377 Format: { "0" | "1" }
378 See security/selinux/Kconfig help text.
379 0 -- check protection applied by kernel (includes
380 any implied execute protection).
381 1 -- check protection requested by application.
382 Default value is set via a kernel config option.
383 Value can be changed at runtime via
384 /selinux/checkreqprot.
387 See Documentation/s390/CommonIO for details.
390 See Documentation/s390/CommonIO for details.
392 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
394 Forces specified clocksource (if available) to be used
395 when calculating gettimeofday(). If specified
396 clocksource is not available, it defaults to PIT.
397 Format: { pit | tsc | cyclone | pmtmr }
399 clocksource= [GENERIC_TIME] Override the default clocksource
401 Override the default clocksource and use the clocksource
402 with the name specified.
403 Some clocksource names to choose from, depending on
405 [all] jiffies (this is the base, fallback clocksource)
407 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
408 pxa_timer,timer3,32k_counter,timer0_1
410 [X86-32] pit,hpet,tsc,vmi-timer;
411 scx200_hrt on Geode; cyclone on IBM x440
419 code_bytes [IA32] How many bytes of object code to print in an
426 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
427 over the 8254 in addition to over the IO-APIC. The
428 kernel tries to set a sensible default.
430 hpet= [X86-32,HPET] option to control HPET usage
431 Format: { enable (default) | disable | force }
432 disable: disable HPET and use PIT instead
433 force: allow force enabled of undocumented chips (ICH4,
436 com20020= [HW,NET] ARCnet - COM20020 chipset
438 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
440 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
444 ARCnet - COM90xx chipset (memory-mapped buffers)
445 Format: <io>[,<irq>[,<memstart>]]
447 condev= [HW,S390] console device
450 console= [KNL] Output console device and options.
452 tty<n> Use the virtual console device <n>.
456 Use the specified serial port. The options are of
457 the form "bbbbpnf", where "bbbb" is the baud rate,
458 "p" is parity ("n", "o", or "e"), "n" is number of
459 bits, and "f" is flow control ("r" for RTS or
460 omit it). Default is "9600n8".
462 See Documentation/serial-console.txt for more
464 Documentation/networking/netconsole.txt for an
467 uart[8250],io,<addr>[,options]
468 uart[8250],mmio,<addr>[,options]
469 Start an early, polled-mode console on the 8250/16550
470 UART at the specified I/O port or MMIO address,
471 switching to the matching ttyS device later. The
472 options are the same as for ttyS, above.
474 earlycon= [KNL] Output early console device and options.
475 uart[8250],io,<addr>[,options]
476 uart[8250],mmio,<addr>[,options]
477 Start an early, polled-mode console on the 8250/16550
478 UART at the specified I/O port or MMIO address.
479 The options are the same as for ttyS, above.
482 [HW] Never suspend the console
483 Disable suspending of consoles during suspend and
484 hibernate operations. Once disabled, debugging
485 messages can reach various consoles while the rest
486 of the system is being put to sleep (ie, while
487 debugging driver suspend/resume hooks). This may
488 not work reliably with all consoles, but is known
489 to work with serial and VGA consoles.
491 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
493 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
495 crashkernel=nn[KMG]@ss[KMG]
496 [KNL] Reserve a chunk of physical memory to
497 hold a kernel to switch to with kexec on panic.
499 crashkernel=range1:size1[,range2:size2,...][@offset]
500 [KNL] Same as above, but depends on the memory
501 in the running system. The syntax of range is
502 start-[end] where start and end are both
503 a memory unit (amount[KMG]). See also
504 Documentation/kdump/kdump.txt for a example.
507 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
512 cs89x0_media= [HW,NET]
513 Format: { rj45 | aui | bnc }
516 See header of drivers/s390/block/dasd_devmap.c.
518 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
519 (one device per port)
520 Format: <port#>,<type>
521 See also Documentation/input/joystick-parport.txt
523 debug [KNL] Enable kernel debugging (events log level).
526 [KNL] verbose self-tests
528 Print debugging info while doing the locking API
530 We default to 0 (no extra messages), setting it to
531 1 will print _a lot_ more information - normally
532 only useful to kernel developers.
535 Format: <area>[,<node>]
536 See also Documentation/networking/decnet.txt.
539 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
540 Change the default blue palette of the console.
541 This is a 16-member array composed of values
545 Format: <green0>,<green1>,<green2>,...,<green15>
546 Change the default green palette of the console.
547 This is a 16-member array composed of values
551 Format: <red0>,<red1>,<red2>,...,<red15>
552 Change the default red palette of the console.
553 This is a 16-member array composed of values
559 Set system-wide default UTF-8 mode for all tty's.
560 Default is 1, i.e. UTF-8 mode is enabled for all
561 newly opened terminals.
564 Set number of hash buckets for dentry cache.
567 IO parameters + enable/disable command.
569 digiepca= [HW,SERIAL]
570 See drivers/char/README.epca and
571 Documentation/digiepca.txt.
573 dmasound= [HW,OSS] Sound subsystem buffers
579 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
581 earlyprintk=serial[,ttySn[,baudrate]]
583 Append ",keep" to not disable it when the real console
586 Only vga or serial at a time, not both.
588 Currently only ttyS0 and ttyS1 are supported.
590 Interaction with the standard serial driver is not
593 The VGA output is eventually overwritten by the real
599 Format: {"of[f]" | "sk[ipmbr]"}
600 See comment in arch/i386/boot/edd.S
602 eisa_irq_edge= [PARISC,HW]
603 See header of drivers/parisc/eisa.c.
606 See comment before function elanfreq_setup() in
607 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
610 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
611 See Documentation/block/as-iosched.txt and
612 Documentation/block/deadline-iosched.txt for details.
614 elfcorehdr= [X86-32, X86_64]
615 Specifies physical address of start of kernel core
616 image elf header. Generally kexec loader will
617 pass this option to capture kernel.
618 See Documentation/kdump/kdump.txt for details.
620 enforcing [SELINUX] Set initial enforcing status.
622 See security/selinux/Kconfig help text.
623 0 -- permissive (log only, no denials).
624 1 -- enforcing (deny and log).
626 Value can be changed at runtime via /selinux/enforce.
629 Format: <spdif>,[<nomix>,[<amplifier>]]
630 See also header of sound/oss/es1371.c.
632 ether= [HW,NET] Ethernet cards parameters
633 This option is obsoleted by the "netdev=" option, which
634 has equivalent usage. See its documentation for details.
636 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
641 fail_make_request=[KNL]
642 General fault injection mechanism.
643 Format: <interval>,<probability>,<space>,<times>
644 See also /Documentation/fault-injection/.
647 See header of drivers/scsi/fd_mcs.c.
650 See header of drivers/scsi/fdomain.c.
653 See Documentation/floppy.txt.
656 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
657 support via parallel port (up to 5 devices per port)
658 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
659 See also Documentation/input/joystick-parport.txt
664 See header of drivers/scsi/gdth.c.
666 gpt [EFI] Forces disk with valid GPT signature but
667 invalid Protective MBR to be treated as GPT.
671 hashdist= [KNL,NUMA] Large hashes allocated during boot
672 are distributed across NUMA nodes. Defaults on
673 for IA-64, off otherwise.
674 Format: 0 | 1 (for off | on)
676 hcl= [IA-64] SGI's Hardware Graph compatibility layer
678 hd= [EIDE] (E)IDE hard drive subsystem geometry
679 Format: <cyl>,<head>,<sect>
681 hd?= [HW] (E)IDE subsystem
682 hd?lun= See Documentation/ide.txt.
684 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
685 size of <nn>. This works even on boxes that have no
686 highmem otherwise. This also works to reduce highmem
687 size on bigger boxes.
689 highres= [KNL] Enable/disable high resolution timer mode.
690 Valid parameters: "on", "off"
694 See Documentation/isdn/README.HiSax.
696 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
698 i8042.direct [HW] Put keyboard port into non-translated mode
699 i8042.dumbkbd [HW] Pretend that controller can only read data from
700 keyboard and cannot control its state
701 (Don't attempt to blink the leds)
702 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
703 i8042.nokbd [HW] Don't check/create keyboard port
704 i8042.nomux [HW] Don't check presence of an active multiplexing
706 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
709 [HW] Frequency with which keyboard LEDs should blink
710 when kernel panics (default is 0.5 sec)
711 i8042.reset [HW] Reset the controller during init and cleanup
712 i8042.unlock [HW] Unlock (ignore) the keylock
716 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
717 indicates that the driver is running on unsupported
719 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
720 does not match list of supported models.
722 [HW] Report power status in /proc/i8k
723 (disabled by default)
724 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
727 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
728 See Documentation/mca.txt.
731 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
733 ide= [HW] (E)IDE subsystem
734 Format: ide=nodma or ide=doubler or ide=reverse
735 See Documentation/ide.txt.
737 ide?= [HW] (E)IDE subsystem
738 Format: ide?=noprobe or chipset specific parameters.
739 See Documentation/ide.txt.
741 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
742 See Documentation/ide.txt.
745 Format: idle=poll or idle=mwait
746 Poll forces a polling idle loop that can slightly improves the performance
747 of waking up a idle CPU, but will use a lot of power and make the system
748 run hot. Not recommended.
749 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
750 to not use it because it doesn't save as much power as a normal idle
751 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
754 ignore_loglevel [KNL]
755 Ignore loglevel setting - this will print /all/
756 kernel messages to the console. Useful for debugging.
759 Set number of hash buckets for inode cache.
762 See header of drivers/scsi/in2000.c.
766 Run specified binary instead of /sbin/init as init
769 initcall_debug [KNL] Trace initcalls as they are executed. Useful
770 for working out where the kernel is dying during
773 initrd= [BOOT] Specify the location of the initial ramdisk
775 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
780 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
782 Disable intel iommu driver.
783 igfx_off [Default Off]
784 By default, gfx is mapped as normal device. If a gfx
785 device has a dedicated DMAR unit, the DMAR unit is
786 bypassed by not enabling DMAR with this option. In
787 this case, gfx device will use physical address for
790 With this option iommu will not optimize to look
791 for io virtual address below 32 bit forcing dual
792 address cycle on pci bus for cards supporting greater
793 than 32 bit addressing. The default is to look
794 for translation below 32 bit and if not available
795 then look in the higher range.
797 io_delay= [X86-32,X86-64] I/O delay method
799 Standard port 0x80 delay
801 Alternate port 0xed delay
803 Simple two microsecond delay
805 io7= [HW] IO7 for Marvel based alpha systems
806 See comment before marvel_specify_io7 in
807 arch/alpha/kernel/core_marvel.c.
810 See Documentation/nfsroot.txt.
812 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
813 See comment before ip2_setup() in
814 drivers/char/ip2/ip2base.c.
816 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
817 See header of drivers/scsi/ips.c.
819 ports= [IP_VS_FTP] IPVS ftp helper module
821 Up to 8 (IP_VS_APP_MAX_PORTS) ports
823 Format: <port>,<port>....
826 When an interrupt is not handled search all handlers
827 for it. Intended to get systems with badly broken
831 When an interrupt is not handled search all handlers
832 for it. Also check all handlers each timer
833 interrupt. Intended to get systems with badly broken
837 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
839 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
841 <cpu number>,...,<cpu number>
843 <cpu number>-<cpu number> (must be a positive range in ascending order)
845 <cpu number>,...,<cpu number>-<cpu number>
846 This option can be used to specify one or more CPUs
847 to isolate from the general SMP balancing and scheduling
848 algorithms. The only way to move a process onto or off
849 an "isolated" CPU is via the CPU affinity syscalls.
850 <cpu number> begins at 0 and the maximum value is
851 "number of CPUs in system - 1".
853 This option is the preferred way to isolate CPUs. The
854 alternative -- manually setting the CPU mask of all
855 tasks in the system -- can cause problems and
856 suboptimal load balancer performance.
860 js= [HW,JOY] Analog joystick
861 See Documentation/input/joystick.txt.
863 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
864 specifies the amount of memory usable by the kernel
865 for non-movable allocations. The requested amount is
866 spread evenly throughout all nodes in the system. The
867 remaining memory in each node is used for Movable
868 pages. In the event, a node is too small to have both
869 kernelcore and Movable pages, kernelcore pages will
870 take priority and other nodes will have a larger number
871 of kernelcore pages. The Movable zone is used for the
872 allocation of pages that may be reclaimed or moved
873 by the page migration subsystem. This means that
874 HugeTLB pages may not be allocated from this zone.
875 Note that allocations like PTEs-from-HighMem still
876 use the HighMem zone if it exists, and the Normal
879 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
880 is similar to kernelcore except it specifies the
881 amount of memory used for migratable allocations.
882 If both kernelcore and movablecore is specified,
883 then kernelcore will be at *least* the specified
884 value but may be more. If movablecore on its own
885 is specified, the administrator must be careful
886 that the amount of memory usable for all allocations
891 kstack=N [X86-32,X86-64] Print N words from the kernel stack
896 lapic [X86-32,APIC] Enable the local APIC even if BIOS
899 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
902 libata.dma= [LIBATA] DMA control
903 libata.dma=0 Disable all PATA and SATA DMA
904 libata.dma=1 PATA and SATA Disk DMA only
905 libata.dma=2 ATAPI (CDROM) DMA only
906 libata.dma=4 Compact Flash DMA only
907 Combinations also work, so libata.dma=3 enables DMA
908 for disks and CDROMs, but not CFs.
910 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
914 load_ramdisk= [RAM] List of ramdisks to load from floppy
915 See Documentation/ramdisk.txt.
917 lockd.nlm_grace_period=P [NFS] Assign grace period.
920 lockd.nlm_tcpport=N [NFS] Assign TCP port.
923 lockd.nlm_timeout=T [NFS] Assign timeout value.
926 lockd.nlm_udpport=M [NFS] Assign UDP port.
929 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
932 loglevel= All Kernel Messages with a loglevel smaller than the
933 console loglevel will be printed to the console. It can
934 also be changed with klogd or other programs. The
935 loglevels are defined as follows:
937 0 (KERN_EMERG) system is unusable
938 1 (KERN_ALERT) action must be taken immediately
939 2 (KERN_CRIT) critical conditions
940 3 (KERN_ERR) error conditions
941 4 (KERN_WARNING) warning conditions
942 5 (KERN_NOTICE) normal but significant condition
943 6 (KERN_INFO) informational
944 7 (KERN_DEBUG) debug-level messages
946 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
947 Format: { n | nk | nM }
948 n must be a power of two. The default size
949 is set in the kernel config file.
951 logo.nologo [FB] Disables display of the built-in Linux logo.
952 This may be used to provide more screen space for
953 kernel log messages and is useful when debugging
954 kernel boot problems.
956 lp=0 [LP] Specify parallel ports to use, e.g,
957 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
958 lp=reset first parallel port). 'lp=0' disables the
959 lp=auto printer driver. 'lp=reset' (which can be
960 specified in addition to the ports) causes
961 attached printers to be reset. Using
962 lp=port1,port2,... specifies the parallel ports
963 to associate lp devices with, starting with
964 lp0. A port specification may be 'none' to skip
965 that lp device, or a parport name such as
966 'parport0'. Specifying 'lp=auto' instead of a
967 port specification list means that device IDs
968 from each port should be examined, to see if
969 an IEEE 1284-compliant printer is attached; if
970 so, the driver will manage that printer.
971 See also header of drivers/char/lp.c.
974 Sets loops_per_jiffy to given constant, thus avoiding
975 time-consuming boot-time autodetection (up to 250 ms per
976 CPU). 0 enables autodetection (default). To determine
977 the correct value for your kernel, boot with normal
978 autodetection and see what value is printed. Note that
979 on SMP systems the preset will be applied to all CPUs,
980 which is likely to cause problems if your CPUs need
981 significantly divergent settings. An incorrect value
982 will cause delays in the kernel to be wrong, leading to
983 unpredictable I/O errors and other breakage. Although
984 unlikely, in the extreme case this might damage your
988 Format: <io>,<irq>,<dma>
990 mac5380= [HW,SCSI] Format:
991 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
993 mac53c9x= [HW,SCSI] Format:
994 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
996 machvec= [IA64] Force the use of a particular machine-vector
997 (machvec) in a generic kernel.
998 Example: machvec=hpzx1_swiotlb
1000 max_loop= [LOOP] Maximum number of loopback devices that can
1004 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1005 should make use of. maxcpus=n : n >= 0 limits the
1006 kernel to using 'n' processors. n=0 is a special case,
1007 it is equivalent to "nosmp", which also disables
1010 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1011 equal to this physical address is ignored.
1013 max_luns= [SCSI] Maximum number of LUNs to probe.
1014 Should be between 1 and 2^32-1.
1017 [SCSI] Maximum number of LUNs received.
1018 Should be between 1 and 16384.
1020 mca-pentium [BUGS=X86-32]
1024 mce [X86-32] Machine Check Exception
1026 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1028 md= [HW] RAID subsystems devices and level
1029 See Documentation/md.txt.
1032 Format: <first>,<last>
1033 Specifies range of consoles to be captured by the MDA.
1035 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1036 Amount of memory to be used when the kernel is not able
1037 to see the whole system memory or for test.
1038 [X86-32] Use together with memmap= to avoid physical
1039 address space collisions. Without memmap= PCI devices
1040 could be placed at addresses belonging to unused RAM.
1042 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1045 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1046 E820 memory map, as specified by the user.
1047 Such memmap=exactmap lines can be constructed based on
1048 BIOS output or other requirements. See the memmap=nn@ss
1051 memmap=nn[KMG]@ss[KMG]
1052 [KNL] Force usage of a specific region of memory
1053 Region of memory to be used, from ss to ss+nn.
1055 memmap=nn[KMG]#ss[KMG]
1056 [KNL,ACPI] Mark specific memory as ACPI data.
1057 Region of memory to be used, from ss to ss+nn.
1059 memmap=nn[KMG]$ss[KMG]
1060 [KNL,ACPI] Mark specific memory as reserved.
1061 Region of memory to be used, from ss to ss+nn.
1063 meye.*= [HW] Set MotionEye Camera parameters
1064 See Documentation/video4linux/meye.txt.
1066 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1067 Multi-Function General Purpose Timers on AMD Geode
1073 [MOUSE] Maximum time between finger touching and
1074 leaving touchpad surface for touch to be considered
1075 a tap and be reported as a left button click (for
1076 touchpads working in absolute mode only).
1078 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1079 reporting absolute coordinates, such as tablets
1080 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1081 reporting absolute coordinates, such as tablets
1086 MTD_Partition= [MTD]
1087 Format: <name>,<region-number>,<size>,<offset>
1089 MTD_Region= [MTD] Format:
1090 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1093 See drivers/mtd/cmdlinepart.c.
1095 mtouchusb.raw_coordinates=
1096 [HW] Make the MicroTouch USB driver use raw coordinates
1097 ('y', default) or cooked coordinates ('n')
1099 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1102 See header of drivers/scsi/NCR_D700.c.
1106 ncr53c400= [HW,SCSI]
1108 ncr53c400a= [HW,SCSI]
1110 ncr53c406a= [HW,SCSI]
1112 ncr53c8xx= [HW,SCSI]
1114 netdev= [NET] Network devices parameters
1115 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1116 Note that mem_start is often overloaded to mean
1117 something different and driver-specific.
1118 This usage is only documented in each driver source
1122 See Documentation/nfsroot.txt.
1124 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1125 See Documentation/nfsroot.txt.
1127 nfs.callback_tcpport=
1128 [NFS] set the TCP port on which the NFSv4 callback
1129 channel should listen.
1131 nfs.idmap_cache_timeout=
1132 [NFS] set the maximum lifetime for idmapper cache
1136 [NFS] enable 64-bit inode numbers.
1137 If zero, the NFS client will fake up a 32-bit inode
1138 number for the readdir() and stat() syscalls instead
1139 of returning the full 64-bit number.
1140 The default is to return 64-bit inode numbers.
1142 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1143 when a NMI is triggered.
1144 Format: [state][,regs][,debounce][,die]
1146 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1148 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1149 emulation library even if a 387 maths coprocessor
1152 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1153 caches in the slab allocator. Saves per-node memory,
1154 but will impact performance.
1158 noapic [SMP,APIC] Tells the kernel to not make use of any
1159 IOAPICs that may be present in the system.
1161 nobats [PPC] Do not use BATs for mapping kernel lowmem
1162 on "Classic" PPC cores.
1166 nodelayacct [KNL] Disable per-task delay accounting
1168 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1172 noexec [X86-32,X86-64]
1173 noexec=on: enable non-executable mappings (default)
1174 noexec=off: disable nn-executable mappings
1176 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1177 register save and restore. The kernel will only save
1178 legacy floating-point registers on task switch.
1182 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1183 instruction doesn't work correctly and not to
1186 nohalt [IA-64] Tells the kernel not to use the power saving
1187 function PAL_HALT_LIGHT when idle. This increases
1188 power-consumption. On the positive side, it reduces
1189 interrupt wake-up latency, which may improve performance
1190 in certain environments such as networked servers or
1193 nohz= [KNL] Boottime enable/disable dynamic ticks
1194 Valid arguments: on, off
1197 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1199 noirqdebug [X86-32] Disables the code which attempts to detect and
1200 disable unhandled interrupt sources.
1202 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1203 broken timer IRQ sources.
1205 noisapnp [ISAPNP] Disables ISA PnP code.
1207 noinitrd [RAM] Tells the kernel not to load any configured
1212 nojitter [IA64] Disables jitter checking for ITC timers.
1214 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1216 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1218 noltlbs [PPC] Do not use large page/tlb entries for kernel
1219 lowmem mapping on PPC40x.
1221 nomca [IA-64] Disable machine check abort handling
1223 nomce [X86-32] Machine Check Exception
1225 nomfgpt [X86-32] Disable Multi-Function General Purpose
1226 Timer usage (for AMD Geode machines).
1228 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1230 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1231 with UP alternatives
1233 noresidual [PPC] Don't use residual data on PReP machines.
1235 noresume [SWSUSP] Disables resume and restores original swap
1238 no-scroll [VGA] Disables scrollback.
1239 This is required for the Braillex ib80-piezo Braille
1240 reader made by F.H. Papenmeier (Germany).
1244 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1246 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1247 and disable the IO APIC. legacy for "maxcpus=0".
1249 nosoftlockup [KNL] Disable the soft-lockup detector.
1251 nosync [HW,M68K] Disables sync negotiation for all devices.
1253 notsc [BUGS=X86-32] Disable Time Stamp Counter
1255 nousb [USB] Disable the USB subsystem
1259 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1260 one of ['zone', 'node', 'default'] can be specified
1261 This can be set from sysctl after boot.
1262 See Documentation/sysctl/vm.txt for details.
1264 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1269 oprofile.timer= [HW]
1270 Use timer interrupt instead of performance counters
1272 osst= [HW,SCSI] SCSI Tape Driver
1273 Format: <buffer_size>,<write_threshold>
1274 See also Documentation/scsi/st.txt.
1276 panic= [KNL] Kernel behaviour on panic
1279 parkbd.port= [HW] Parallel port number the keyboard adapter is
1280 connected to, default is 0.
1282 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1283 0 for XT, 1 for AT (default is AT).
1286 parport= [HW,PPT] Specify parallel ports. 0 disables.
1287 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1288 Use 'auto' to force the driver to use any
1289 IRQ/DMA settings detected (the default is to
1290 ignore detected IRQ/DMA settings because of
1291 possible conflicts). You can specify the base
1292 address, IRQ, and DMA settings; IRQ and DMA
1293 should be numbers, or 'auto' (for using detected
1294 settings on that particular port), or 'nofifo'
1295 (to avoid using a FIFO even if it is detected).
1296 Parallel ports are assigned in the order they
1297 are specified on the command line, starting
1300 parport_init_mode= [HW,PPT]
1301 Configure VIA parallel port to operate in
1302 a specific mode. This is necessary on Pegasos
1303 computer where firmware has no options for setting
1304 up parallel port mode and sets it to spp.
1305 Currently this function knows 686a and 8231 chips.
1306 Format: [spp|ps2|epp|ecp|ecpepp]
1308 pas2= [HW,OSS] Format:
1309 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1312 See header of drivers/scsi/pas16.c.
1315 Halt all CPUs after the first oops has been printed for
1316 the specified number of seconds. This is to be used if
1317 your oopses keep scrolling off the screen.
1322 See header of drivers/block/paride/pcd.c.
1323 See also Documentation/paride.txt.
1325 pci=option[,option...] [PCI] various PCI subsystem options:
1326 off [X86-32] don't probe for the PCI bus
1327 bios [X86-32] force use of PCI BIOS, don't access
1328 the hardware directly. Use this if your machine
1329 has a non-standard PCI host bridge.
1330 nobios [X86-32] disallow use of PCI BIOS, only direct
1331 hardware access methods are allowed. Use this
1332 if you experience crashes upon bootup and you
1333 suspect they are caused by the BIOS.
1334 conf1 [X86-32] Force use of PCI Configuration
1336 conf2 [X86-32] Force use of PCI Configuration
1338 noaer [PCIE] If the PCIEAER kernel config parameter is
1339 enabled, this kernel boot option can be used to
1340 disable the use of PCIE advanced error reporting.
1341 nodomains [PCI] Disable support for multiple PCI
1342 root domains (aka PCI segments, in ACPI-speak).
1343 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1345 nomsi [MSI] If the PCI_MSI kernel config parameter is
1346 enabled, this kernel boot option can be used to
1347 disable the use of MSI interrupts system-wide.
1348 nosort [X86-32] Don't sort PCI devices according to
1349 order given by the PCI BIOS. This sorting is
1350 done to get a device order compatible with
1352 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1353 routing table. These calls are known to be buggy
1354 on several machines and they hang the machine
1355 when used, but on other computers it's the only
1356 way to get the interrupt routing table. Try
1357 this option if the kernel is unable to allocate
1358 IRQs or discover secondary PCI buses on your
1360 rom [X86-32] Assign address space to expansion ROMs.
1361 Use with caution as certain devices share
1362 address decoders between ROMs and other
1364 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1365 assigned automatically to PCI devices. You can
1366 make the kernel exclude IRQs of your ISA cards
1368 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1369 of the PIRQ table (normally generated
1370 by the BIOS) if it is outside the
1371 F0000h-100000h range.
1372 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1373 useful if the kernel is unable to find your
1374 secondary buses and you want to tell it
1375 explicitly which ones they are.
1376 assign-busses [X86-32] Always assign all PCI bus
1377 numbers ourselves, overriding
1378 whatever the firmware may have done.
1379 usepirqmask [X86-32] Honor the possible IRQ mask stored
1380 in the BIOS $PIR table. This is needed on
1381 some systems with broken BIOSes, notably
1382 some HP Pavilion N5400 and Omnibook XE3
1383 notebooks. This will have no effect if ACPI
1384 IRQ routing is enabled.
1385 noacpi [X86-32] Do not use ACPI for IRQ routing
1386 or for PCI scanning.
1387 use_crs [X86-32] Use _CRS for PCI resource
1389 routeirq Do IRQ routing for all PCI devices.
1390 This is normally done in pci_enable_device(),
1391 so this option is a temporary workaround
1392 for broken drivers that don't call it.
1393 firmware [ARM] Do not re-enumerate the bus but instead
1394 just use the configuration from the
1395 bootloader. This is currently used on
1396 IXP2000 systems where the bus has to be
1397 configured a certain way for adjunct CPUs.
1398 noearly [X86] Don't do any early type 1 scanning.
1399 This might help on some broken boards which
1400 machine check when some devices' config space
1401 is read. But various workarounds are disabled
1402 and some IOMMU drivers will not work.
1403 bfsort Sort PCI devices into breadth-first order.
1404 This sorting is done to get a device
1405 order compatible with older (<= 2.4) kernels.
1406 nobfsort Don't sort PCI devices into breadth-first order.
1407 cbiosize=nn[KMG] The fixed amount of bus space which is
1408 reserved for the CardBus bridge's IO window.
1409 The default value is 256 bytes.
1410 cbmemsize=nn[KMG] The fixed amount of bus space which is
1411 reserved for the CardBus bridge's memory
1412 window. The default value is 64 megabytes.
1414 pcmv= [HW,PCMCIA] BadgePAD 4
1417 See Documentation/paride.txt.
1419 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1422 See arch/parisc/kernel/pdc_chassis.c
1425 See Documentation/paride.txt.
1428 See Documentation/paride.txt.
1430 pirq= [SMP,APIC] Manual mp-table setup
1431 See Documentation/i386/IO-APIC.txt.
1433 plip= [PPT,NET] Parallel port network link
1434 Format: { parport<nr> | timid | 0 }
1435 See also Documentation/parport.txt.
1441 { on | off | curr | res | no-curr | no-res }
1444 [ISAPNP] Exclude IRQs for the autoconfiguration
1447 [ISAPNP] Exclude DMAs for the autoconfiguration
1449 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1450 Ranges are in pairs (I/O port base and size).
1453 [ISAPNP] Exclude memory regions for the
1455 Ranges are in pairs (memory base and size).
1457 print-fatal-signals=
1458 [KNL] debug: print fatal signals
1459 print-fatal-signals=1: print segfault info to
1463 printk.time= Show timing data prefixed to each printk message line
1464 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1466 profile= [KNL] Enable kernel profiling via /proc/profile
1467 Format: [schedule,]<number>
1468 Param: "schedule" - profile schedule points.
1469 Param: <number> - step/bucket size as a power of 2 for
1470 statistical time based profiling.
1471 Param: "sleep" - profile D-state sleeping (millisecs).
1472 Requires CONFIG_SCHEDSTATS
1473 Param: "kvm" - profile VM exits.
1475 processor.max_cstate= [HW,ACPI]
1476 Limit processor to maximum C-state
1477 max_cstate=9 overrides any DMI blacklist limit.
1479 processor.nocst [HW,ACPI]
1480 Ignore the _CST method to determine C-states,
1481 instead using the legacy FADT method
1483 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1485 See Documentation/ramdisk.txt.
1487 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1488 probe for; one of (bare|imps|exps|lifebook|any).
1489 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1491 psmouse.resetafter= [HW,MOUSE]
1492 Try to reset the device after so many bad packets
1495 [HW,MOUSE] Set desired mouse resolution, in dpi.
1496 psmouse.smartscroll=
1497 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1498 0 = disabled, 1 = enabled (default).
1500 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1502 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1505 See Documentation/paride.txt.
1508 [KNL] Number of legacy pty's. Overwrites compiled-in
1511 quiet [KNL] Disable most log messages
1516 See Documentation/md.txt.
1518 ramdisk_blocksize= [RAM]
1519 See Documentation/ramdisk.txt.
1521 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1522 See Documentation/ramdisk.txt.
1524 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1525 RCU callbacks to process in one batch.
1527 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1528 RCU callbacks over which batch limiting is disabled.
1530 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1531 RCU callbacks below which batch limiting is re-enabled.
1535 Run specified binary instead of /init from the ramdisk,
1536 used for early userspace startup. See initrd.
1538 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1539 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1540 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1542 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1544 reservetop= [X86-32]
1546 Reserves a hole at the top of the kernel virtual
1549 reset_devices [KNL] Force drivers to reset the underlying device
1550 during initialization.
1553 Specify the partition device for software suspend
1555 resume_offset= [SWSUSP]
1556 Specify the offset from the beginning of the partition
1557 given by "resume=" at which the swap header is located,
1558 in <PAGE_SIZE> units (needed only for swap files).
1559 See Documentation/power/swsusp-and-swap-files.txt
1561 retain_initrd [RAM] Keep initrd memory after extraction
1563 rhash_entries= [KNL,NET]
1564 Set number of hash buckets for route cache
1566 riscom8= [HW,SERIAL]
1567 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1569 ro [KNL] Mount root device read-only on boot
1571 root= [KNL] Root filesystem
1573 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1574 mount the root filesystem
1576 rootflags= [KNL] Set root filesystem mount option string
1578 rootfstype= [KNL] Set root filesystem type
1580 rootwait [KNL] Wait (indefinitely) for root device to show up.
1581 Useful for devices that are detected asynchronously
1582 (e.g. USB and MMC devices).
1584 root_plug.vendor_id=
1585 [ROOTPLUG] Override the default vendor ID
1587 root_plug.product_id=
1588 [ROOTPLUG] Override the default product ID
1591 [ROOTPLUG] Enable debugging output
1593 rw [KNL] Mount root device read-write on boot
1595 S [KNL] Run init in single mode
1598 See drivers/net/irda/sa1100_ir.c.
1600 sbni= [NET] Granch SBNI12 leased line adapter
1602 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1603 Format: <io>[,<timeout>[,<isapnp>]]
1605 scsi_debug_*= [SCSI]
1606 See drivers/scsi/scsi_debug.c.
1608 scsi_default_dev_flags=
1609 [SCSI] SCSI default device flags
1612 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1613 Format: <vendor>:<model>:<flags>
1614 (flags are integer value)
1616 scsi_logging_level= [SCSI] a bit mask of logging levels
1617 See drivers/scsi/scsi_logging.h for bits. Also
1618 settable via sysctl at dev.scsi.logging_level
1619 (/proc/sys/dev/scsi/logging_level).
1620 There is also a nice 'scsi_logging_level' script in the
1621 S390-tools package, available for download at
1622 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1624 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1625 discovered. async scans them in kernel threads,
1626 allowing boot to proceed. none ignores them, expecting
1627 user space to do the scan.
1629 selinux [SELINUX] Disable or enable SELinux at boot time.
1630 Format: { "0" | "1" }
1631 See security/selinux/Kconfig help text.
1634 Default value is set via kernel config option.
1635 If enabled at boot time, /selinux/disable can be used
1636 later to disable prior to initial policy load.
1638 selinux_compat_net =
1639 [SELINUX] Set initial selinux_compat_net flag value.
1640 Format: { "0" | "1" }
1641 0 -- use new secmark-based packet controls
1642 1 -- use legacy packet controls
1643 Default value is 0 (preferred).
1644 Value can be changed at runtime via
1645 /selinux/compat_net.
1647 serialnumber [BUGS=X86-32]
1650 Maximal number of shapers.
1653 See header of drivers/scsi/sim710.c.
1660 slub_debug[=options[,slabs]] [MM, SLUB]
1661 Enabling slub_debug allows one to determine the
1662 culprit if slab objects become corrupted. Enabling
1663 slub_debug can create guard zones around objects and
1664 may poison objects when not in use. Also tracks the
1665 last alloc / free. For more information see
1666 Documentation/vm/slub.txt.
1668 slub_max_order= [MM, SLUB]
1669 Determines the maximum allowed order for slabs.
1670 A high setting may cause OOMs due to memory
1671 fragmentation. For more information see
1672 Documentation/vm/slub.txt.
1674 slub_min_objects= [MM, SLUB]
1675 The minimum number of objects per slab. SLUB will
1676 increase the slab order up to slub_max_order to
1677 generate a sufficiently large slab able to contain
1678 the number of objects indicated. The higher the number
1679 of objects the smaller the overhead of tracking slabs
1680 and the less frequently locks need to be acquired.
1681 For more information see Documentation/vm/slub.txt.
1683 slub_min_order= [MM, SLUB]
1684 Determines the mininum page order for slabs. Must be
1685 lower than slub_max_order.
1686 For more information see Documentation/vm/slub.txt.
1688 slub_nomerge [MM, SLUB]
1689 Disable merging of slabs with similar size. May be
1690 necessary if there is some reason to distinguish
1691 allocs to different slabs. Debug options disable
1692 merging on their own.
1693 For more information see Documentation/vm/slub.txt.
1696 Format: <io1>[,<io2>[,...,<io8>]]
1698 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1699 attempt to substitute SMP alternatives once at boot.
1701 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1702 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1703 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1704 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1705 smsc-ircc2.ircc_irq= [HW] IRQ line
1706 smsc-ircc2.ircc_dma= [HW] DMA channel
1707 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1708 0: Toshiba Satellite 1800 (GP data pin select)
1709 1: Fast pin select (default)
1712 snd-ad1816a= [HW,ALSA]
1714 snd-ad1848= [HW,ALSA]
1716 snd-ali5451= [HW,ALSA]
1718 snd-als100= [HW,ALSA]
1720 snd-als4000= [HW,ALSA]
1722 snd-azt2320= [HW,ALSA]
1724 snd-cmi8330= [HW,ALSA]
1726 snd-cmipci= [HW,ALSA]
1728 snd-cs4231= [HW,ALSA]
1730 snd-cs4232= [HW,ALSA]
1732 snd-cs4236= [HW,ALSA]
1734 snd-cs4281= [HW,ALSA]
1736 snd-cs46xx= [HW,ALSA]
1738 snd-dt019x= [HW,ALSA]
1740 snd-dummy= [HW,ALSA]
1742 snd-emu10k1= [HW,ALSA]
1744 snd-ens1370= [HW,ALSA]
1746 snd-ens1371= [HW,ALSA]
1748 snd-es968= [HW,ALSA]
1750 snd-es1688= [HW,ALSA]
1752 snd-es18xx= [HW,ALSA]
1754 snd-es1938= [HW,ALSA]
1756 snd-es1968= [HW,ALSA]
1758 snd-fm801= [HW,ALSA]
1760 snd-gusclassic= [HW,ALSA]
1762 snd-gusextreme= [HW,ALSA]
1764 snd-gusmax= [HW,ALSA]
1768 snd-ice1712= [HW,ALSA]
1770 snd-intel8x0= [HW,ALSA]
1772 snd-interwave= [HW,ALSA]
1777 snd-korg1212= [HW,ALSA]
1779 snd-maestro3= [HW,ALSA]
1781 snd-mpu401= [HW,ALSA]
1783 snd-mtpav= [HW,ALSA]
1785 snd-nm256= [HW,ALSA]
1787 snd-opl3sa2= [HW,ALSA]
1795 snd-opti93x= [HW,ALSA]
1799 snd-rme32= [HW,ALSA]
1801 snd-rme96= [HW,ALSA]
1803 snd-rme9652= [HW,ALSA]
1809 snd-sbawe= [HW,ALSA]
1811 snd-serial= [HW,ALSA]
1813 snd-sgalaxy= [HW,ALSA]
1815 snd-sonicvibes= [HW,ALSA]
1820 snd-sun-cs4231= [HW,ALSA]
1822 snd-trident= [HW,ALSA]
1824 snd-usb-audio= [HW,ALSA,USB]
1826 snd-via82xx= [HW,ALSA]
1828 snd-virmidi= [HW,ALSA]
1830 snd-wavefront= [HW,ALSA]
1832 snd-ymfpci= [HW,ALSA]
1834 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1835 See Documentation/sonypi.txt
1837 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1838 See Documentation/specialix.txt.
1840 spia_io_base= [HW,MTD]
1846 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1848 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1849 See Documentation/scsi/st.txt.
1852 See header of drivers/scsi/seagate.c.
1856 Set the STI (builtin display/keyboard on the HP-PARISC
1857 machines) console (graphic card) which should be used
1858 as the initial boot-console.
1859 See also comment in drivers/video/console/sticore.c.
1862 See comment in drivers/video/console/sticore.c.
1865 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1869 Control how the NFS server code allocates CPUs to
1870 service thread pools. Depending on how many NICs
1871 you have and where their interrupts are bound, this
1872 option will affect which CPUs will do NFS serving.
1873 Note: this parameter cannot be changed while the
1874 NFS server is running.
1876 auto the server chooses an appropriate mode
1877 automatically using heuristics
1878 global a single global pool contains all CPUs
1879 percpu one pool for each CPU
1880 pernode one pool for each NUMA node (equivalent
1881 to global on non-NUMA machines)
1883 swiotlb= [IA-64] Number of I/O TLB slabs
1887 sym53c416= [HW,SCSI]
1888 See header of drivers/scsi/sym53c416.c.
1890 sysrq_always_enabled
1892 Ignore sysrq setting - this boot parameter will
1893 neutralize any effect of /proc/sys/kernel/sysrq.
1894 Useful for debugging.
1897 See header of drivers/scsi/t128.c.
1901 thash_entries= [KNL,NET]
1902 Set number of hash buckets for TCP connection
1904 thermal.act= [HW,ACPI]
1905 -1: disable all active trip points in all thermal zones
1906 <degrees C>: override all lowest active trip points
1908 thermal.crt= [HW,ACPI]
1909 -1: disable all critical trip points in all thermal zones
1910 <degrees C>: lower all critical trip points
1912 thermal.nocrt= [HW,ACPI]
1913 Set to disable actions on ACPI thermal zone
1914 critical and hot trip points.
1916 thermal.off= [HW,ACPI]
1917 1: disable ACPI thermal control
1919 thermal.psv= [HW,ACPI]
1920 -1: disable all passive trip points
1921 <degrees C>: override all passive trip points to this value
1923 thermal.tzp= [HW,ACPI]
1924 Specify global default ACPI thermal zone polling rate
1925 <deci-seconds>: poll all this frequency
1926 0: no polling (default)
1928 time Show timing data prefixed to each printk message line
1929 [deprecated, see 'printk.time']
1931 tipar.timeout= [HW,PPT]
1932 Set communications timeout in tenths of a second
1935 tipar.delay= [HW,PPT]
1936 Set inter-bit delay in microseconds (default 10).
1939 See header of drivers/scsi/seagate.c.
1942 See comment before function dc390_setup() in
1943 drivers/scsi/tmscsim.c.
1947 trix= [HW,OSS] MediaTrix AudioTrix Pro
1949 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1951 turbografx.map[2|3]= [HW,JOY]
1952 TurboGraFX parallel port interface
1954 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1955 See also Documentation/input/joystick-parport.txt
1957 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1958 See header of drivers/scsi/u14-34f.c.
1967 [USB] Ignore overcurrent events (default N).
1968 Some badly-designed motherboards generate lots of
1969 bogus events, for ports that aren't wired to
1970 anything. Set this parameter to avoid log spamming.
1971 Note that genuine overcurrent events won't be
1974 usbcore.autosuspend=
1975 [USB] The autosuspend time delay (in seconds) used
1976 for newly-detected USB devices (default 2). This
1977 is the time required before an idle device will be
1978 autosuspended. Devices for which the delay is set
1979 to a negative value won't be autosuspended at all.
1982 [USBHID] The interval which mice are to be polled at.
1984 vdso= [X86-32,SH,x86-64]
1985 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1986 vdso=1: enable VDSO (default)
1987 vdso=0: disable VDSO mapping
1990 vector=percpu: enable percpu vector domain
1992 video= [FB] Frame buffer configuration
1993 See Documentation/fb/modedb.txt.
1995 vga= [BOOT,X86-32] Select a particular video mode
1996 See Documentation/i386/boot.txt and
1997 Documentation/svga.txt.
1998 Use vga=ask for menu.
1999 This is actually a boot loader parameter; the value is
2000 passed to the kernel using a special protocol.
2002 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2003 size of <nn>. This can be used to increase the
2004 minimum size (128MB on x86). It can also be used to
2005 decrease the size and leave more room for directly
2008 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2011 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2014 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2017 waveartist= [HW,OSS]
2018 Format: <io>,<irq>,<dma>,<dma2>
2021 See header of drivers/scsi/wd33c93.c.
2024 See header of drivers/scsi/wd7000.c.
2027 See Documentation/watchdog/wdt.txt.
2029 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2030 xd_geo= See header of drivers/block/xd.c.
2032 xirc2ps_cs= [NET,PCMCIA]
2034 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2036 norandmaps Don't use address space randomization
2037 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2039 ______________________________________________________________________
2043 Add documentation for ALSA options.
2044 Add more DRM drivers.