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 AX25 Appropriate AX.25 support is enabled.
38 BLACKFIN Blackfin architecture is enabled.
39 DRM Direct Rendering Management support is enabled.
40 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
41 EFI EFI Partitioning (GPT) is enabled
42 EIDE EIDE/ATAPI support is enabled.
43 FB The frame buffer device is enabled.
44 HW Appropriate hardware is enabled.
45 IA-64 IA-64 architecture is enabled.
46 IOSCHED More than one I/O scheduler is enabled.
47 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
48 ISAPNP ISA PnP code is enabled.
49 ISDN Appropriate ISDN support is enabled.
50 JOY Appropriate joystick support is enabled.
51 LIBATA Libata driver is enabled
52 LP Printer support is enabled.
53 LOOP Loopback device support is enabled.
54 M68k M68k architecture is enabled.
55 These options have more detailed description inside of
56 Documentation/m68k/kernel-options.txt.
57 MCA MCA bus support is enabled.
58 MDA MDA console support is enabled.
59 MOUSE Appropriate mouse support is enabled.
60 MSI Message Signaled Interrupts (PCI).
61 MTD MTD (Memory Technology Device) support is enabled.
62 NET Appropriate network support is enabled.
63 NUMA NUMA support is enabled.
64 GENERIC_TIME The generic timeofday code is enabled.
65 NFS Appropriate NFS support is enabled.
66 OSS OSS sound support is enabled.
67 PV_OPS A paravirtualized kernel is enabled.
68 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
69 PARISC The PA-RISC architecture is enabled.
70 PCI PCI bus support is enabled.
71 PCIE PCI Express support is enabled.
72 PCMCIA The PCMCIA subsystem is enabled.
73 PNP Plug & Play support is enabled.
74 PPC PowerPC architecture is enabled.
75 PPT Parallel port support is enabled.
76 PS2 Appropriate PS/2 support is enabled.
77 RAM RAM disk support is enabled.
78 ROOTPLUG The example Root Plug LSM is enabled.
79 S390 S390 architecture is enabled.
80 SCSI Appropriate SCSI support is enabled.
81 A lot of drivers has their options described inside of
83 SECURITY Different security models are enabled.
84 SELINUX SELinux support is enabled.
85 SERIAL Serial support is enabled.
86 SH SuperH architecture is enabled.
87 SMP The kernel is an SMP kernel.
88 SPARC Sparc architecture is enabled.
89 SWSUSP Software suspend is enabled.
90 TS Appropriate touchscreen support is enabled.
91 USB USB support is enabled.
92 USBHID USB Human Interface Device support is enabled.
93 V4L Video For Linux support is enabled.
94 VGA The VGA console has been enabled.
95 VT Virtual terminal support is enabled.
96 WDT Watchdog support is enabled.
97 XT IBM PC/XT MFM hard disk support is enabled.
98 X86-32 X86-32, aka i386 architecture is enabled.
99 X86-64 X86-64 architecture is enabled.
100 More X86-64 boot options can be found in
101 Documentation/x86_64/boot-options.txt .
103 In addition, the following text indicates that the option:
105 BUGS= Relates to possible processor bugs on the said processor.
106 KNL Is a kernel start-up parameter.
107 BOOT Is a boot loader parameter.
109 Parameters denoted with BOOT are actually interpreted by the boot
110 loader, and have no meaning to the kernel directly.
111 Do not modify the syntax of boot loader parameters without extreme
112 need or coordination with <Documentation/i386/boot.txt>.
114 There are also arch-specific kernel-parameters not documented here.
115 See for example <Documentation/x86_64/boot-options.txt>.
117 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
118 a trailing = on the name of any parameter states that that parameter will
119 be entered as an environment variable, whereas its absence indicates that
120 it will appear as a kernel argument readable via /proc/cmdline by programs
121 running once the system is up.
123 The number of kernel parameters is not limited, but the length of the
124 complete command line (parameters including spaces etc.) is limited to
125 a fixed number of characters. This limit depends on the architecture
126 and is between 256 and 4096 characters. It is defined in the file
127 ./include/asm/setup.h as COMMAND_LINE_SIZE.
130 acpi= [HW,ACPI,X86-64,i386]
131 Advanced Configuration and Power Interface
132 Format: { force | off | ht | strict | noirq }
133 force -- enable ACPI if default was off
134 off -- disable ACPI if default was on
135 noirq -- do not use ACPI for IRQ routing
136 ht -- run only enough ACPI to enable Hyper Threading
137 strict -- Be less tolerant of platforms that are not
138 strictly ACPI specification compliant.
140 See also Documentation/pm.txt, pci=noacpi
142 acpi_apic_instance= [ACPI, IOAPIC]
144 2: use 2nd APIC table, if available
145 1,0: use 1st APIC table
148 acpi_sleep= [HW,ACPI] Sleep options
149 Format: { s3_bios, s3_mode }
150 See Documentation/power/video.txt
152 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
153 Format: { level | edge | high | low }
155 acpi_irq_balance [HW,ACPI]
156 ACPI will balance active IRQs
159 acpi_irq_nobalance [HW,ACPI]
160 ACPI will not move active IRQs (default)
163 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
165 Format: <irq>,<irq>...
167 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
168 Format: <irq>,<irq>...
170 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
172 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
173 Format: To spoof as Windows 98: ="Microsoft Windows"
175 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
176 acpi_osi="string1" # add string1 -- only one string
177 acpi_osi="!string2" # remove built-in string2
178 acpi_osi= # disable all strings
180 acpi_serialize [HW,ACPI] force serialization of AML methods
182 acpi_skip_timer_override [HW,ACPI]
183 Recognize and ignore IRQ0/pin2 Interrupt Override.
184 For broken nForce2 BIOS resulting in XT-PIC timer.
185 acpi_use_timer_override [HW,ACPI}
186 Use timer override. For some broken Nvidia NF5 boards
187 that require a timer override, but don't have
190 acpi.debug_layer= [HW,ACPI]
192 Each bit of the <int> indicates an ACPI debug layer,
193 1: enable, 0: disable. It is useful for boot time
194 debugging. After system has booted up, it can be set
195 via /sys/module/acpi/parameters/debug_layer.
196 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
197 Available bits (add the numbers together) to enable debug output
198 for specific parts of the ACPI subsystem:
199 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
200 0x10 namespace 0x20 parser 0x40 dispatcher
201 0x80 executer 0x100 resources 0x200 acpica debugger
202 0x400 os services 0x800 acpica disassembler.
203 The number can be in decimal or prefixed with 0x in hex.
204 Warning: Many of these options can produce a lot of
205 output and make your system unusable. Be very careful.
207 acpi.debug_level= [HW,ACPI]
209 Each bit of the <int> indicates an ACPI debug level,
210 1: enable, 0: disable. It is useful for boot time
211 debugging. After system has booted up, it can be set
212 via /sys/module/acpi/parameters/debug_level.
213 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
214 Available bits (add the numbers together) to enable different
215 debug output levels of the ACPI subsystem:
216 0x01 error 0x02 warn 0x04 init 0x08 debug object
217 0x10 info 0x20 init names 0x40 parse 0x80 load
218 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
219 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
220 0x10000 resources 0x20000 user requests 0x40000 package.
221 The number can be in decimal or prefixed with 0x in hex.
222 Warning: Many of these options can produce a lot of
223 output and make your system unusable. Be very careful.
225 acpi_pm_good [X86-32,X86-64]
226 Override the pmtimer bug detection: force the kernel
227 to assume that this machine's pmtimer latches its value
228 and always returns good values.
231 { off | try_unsupported }
232 off: disable AGP support
233 try_unsupported: try to drive unsupported chipsets
234 (may crash computer or cause data corruption)
236 enable_timer_pin_1 [i386,x86-64]
237 Enable PIN 1 of APIC timer
238 Can be useful to work around chipset bugs
239 (in particular on some ATI chipsets).
240 The kernel tries to set a reasonable default.
242 disable_timer_pin_1 [i386,x86-64]
243 Disable PIN 1 of APIC timer
244 Can be useful to work around chipset bugs.
247 Format: <io>,<irq>,<dma>,<dma2>,<type>
250 See header of drivers/scsi/advansys.c.
252 advwdt= [HW,WDT] Advantech WDT
253 Format: <iostart>,<iostop>
255 aedsp16= [HW,OSS] Audio Excel DSP 16
256 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
257 See also header of sound/oss/aedsp16.c.
260 See Documentation/scsi/aha152x.txt.
263 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
266 See Documentation/scsi/aic7xxx.txt.
269 See Documentation/scsi/aic79xx.txt.
271 amijoy.map= [HW,JOY] Amiga joystick support
272 Map of devices attached to JOY0DAT and JOY1DAT
274 See also Documentation/kernel/input/joystick.txt
276 analog.map= [HW,JOY] Analog joystick and gamepad support
277 Specifies type or capabilities of an analog joystick
278 connected to one of 16 gameports
279 Format: <type1>,<type2>,..<type16>
282 Power management functions (SPARCstation-4/5 + deriv.)
284 Disable APC CPU standby support. SPARCstation-Fox does
285 not play well with APC CPU idle - disable it if you have
286 APC and your system crashes randomly.
288 apic= [APIC,i386] Advanced Programmable Interrupt Controller
289 Change the output verbosity whilst booting
290 Format: { quiet (default) | verbose | debug }
291 Change the amount of debugging information output
292 when initialising the APIC and IO-APIC components.
294 apm= [APM] Advanced Power Management
295 See header of arch/i386/kernel/apm.c.
297 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
298 Format: <io>,<irq>,<nodeID>
302 atarimouse= [HW,MOUSE] Atari Mouse
304 atascsi= [HW,SCSI] Atari SCSI
306 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
307 EzKey and similar keyboards
309 atkbd.reset= [HW] Reset keyboard during initialization
311 atkbd.set= [HW] Select keyboard code set
312 Format: <int> (2 = AT (default), 3 = PS/2)
314 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
317 atkbd.softraw= [HW] Choose between synthetic and real raw mode
318 Format: <bool> (0 = real, 1 = synthetic (default))
320 atkbd.softrepeat= [HW]
321 Use software keyboard repeat
325 baycom_epp= [HW,AX25]
328 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
330 See header of drivers/net/hamradio/baycom_par.c.
332 baycom_ser_fdx= [HW,AX25]
333 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
334 Format: <io>,<irq>,<mode>[,<baud>]
335 See header of drivers/net/hamradio/baycom_ser_fdx.c.
337 baycom_ser_hdx= [HW,AX25]
338 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
339 Format: <io>,<irq>,<mode>
340 See header of drivers/net/hamradio/baycom_ser_hdx.c.
342 blkmtd_device= [HW,MTD]
348 boot_delay= Milliseconds to delay each printk during boot.
349 Values larger than 10 seconds (10000) are changed to
353 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
354 bttv.radio= Most important insmod options are available as
356 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
357 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
360 See drivers/scsi/BusLogic.c, comment before function
361 BusLogic_ParseDriverOptions().
363 c101= [NET] Moxa C101 synchronous serial card
365 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
366 Sometimes CPU hardware bugs make them report the cache
367 size incorrectly. The kernel will attempt work arounds
368 to fix known problems, but for some CPUs it is not
369 possible to determine what the correct size should be.
370 This option provides an override for these situations.
373 [SECURITY] Disable capabilities. This would normally
374 be used only if an alternative security model is to be
375 configured. Potentially dangerous and should only be
376 used if you are entirely sure of the consequences.
378 chandev= [HW,NET] Generic channel device initialisation
380 checkreqprot [SELINUX] Set initial checkreqprot flag value.
381 Format: { "0" | "1" }
382 See security/selinux/Kconfig help text.
383 0 -- check protection applied by kernel (includes
384 any implied execute protection).
385 1 -- check protection requested by application.
386 Default value is set via a kernel config option.
387 Value can be changed at runtime via
388 /selinux/checkreqprot.
390 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
392 Forces specified clocksource (if available) to be used
393 when calculating gettimeofday(). If specified
394 clocksource is not available, it defaults to PIT.
395 Format: { pit | tsc | cyclone | pmtmr }
397 clocksource= [GENERIC_TIME] Override the default clocksource
399 Override the default clocksource and use the clocksource
400 with the name specified.
401 Some clocksource names to choose from, depending on
403 [all] jiffies (this is the base, fallback clocksource)
405 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
406 pxa_timer,timer3,32k_counter,timer0_1
408 [X86-32] pit,hpet,tsc,vmi-timer;
409 scx200_hrt on Geode; cyclone on IBM x440
417 code_bytes [IA32] How many bytes of object code to print in an
424 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
425 over the 8254 in addition to over the IO-APIC. The
426 kernel tries to set a sensible default.
428 hpet= [X86-32,HPET] option to disable HPET and use PIT.
431 com20020= [HW,NET] ARCnet - COM20020 chipset
433 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
435 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
439 ARCnet - COM90xx chipset (memory-mapped buffers)
440 Format: <io>[,<irq>[,<memstart>]]
442 condev= [HW,S390] console device
445 console= [KNL] Output console device and options.
447 tty<n> Use the virtual console device <n>.
451 Use the specified serial port. The options are of
452 the form "bbbbpnf", where "bbbb" is the baud rate,
453 "p" is parity ("n", "o", or "e"), "n" is number of
454 bits, and "f" is flow control ("r" for RTS or
455 omit it). Default is "9600n8".
457 See Documentation/serial-console.txt for more
459 Documentation/networking/netconsole.txt for an
462 uart[8250],io,<addr>[,options]
463 uart[8250],mmio,<addr>[,options]
464 Start an early, polled-mode console on the 8250/16550
465 UART at the specified I/O port or MMIO address,
466 switching to the matching ttyS device later. The
467 options are the same as for ttyS, above.
469 earlycon= [KNL] Output early console device and options.
470 uart[8250],io,<addr>[,options]
471 uart[8250],mmio,<addr>[,options]
472 Start an early, polled-mode console on the 8250/16550
473 UART at the specified I/O port or MMIO address.
474 The options are the same as for ttyS, above.
477 [HW] Never suspend the console
478 Disable suspending of consoles during suspend and
479 hibernate operations. Once disabled, debugging
480 messages can reach various consoles while the rest
481 of the system is being put to sleep (ie, while
482 debugging driver suspend/resume hooks). This may
483 not work reliably with all consoles, but is known
484 to work with serial and VGA consoles.
486 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
488 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
490 crashkernel=nn[KMG]@ss[KMG]
491 [KNL] Reserve a chunk of physical memory to
492 hold a kernel to switch to with kexec on panic.
494 crashkernel=range1:size1[,range2:size2,...][@offset]
495 [KNL] Same as above, but depends on the memory
496 in the running system. The syntax of range is
497 start-[end] where start and end are both
498 a memory unit (amount[KMG]). See also
499 Documentation/kdump/kdump.txt for a example.
502 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
507 cs89x0_media= [HW,NET]
508 Format: { rj45 | aui | bnc }
511 See header of drivers/s390/block/dasd_devmap.c.
513 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
514 (one device per port)
515 Format: <port#>,<type>
516 See also Documentation/input/joystick-parport.txt
518 debug [KNL] Enable kernel debugging (events log level).
521 [KNL] verbose self-tests
523 Print debugging info while doing the locking API
525 We default to 0 (no extra messages), setting it to
526 1 will print _a lot_ more information - normally
527 only useful to kernel developers.
530 Format: <area>[,<node>]
531 See also Documentation/networking/decnet.txt.
534 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
535 Change the default blue palette of the console.
536 This is a 16-member array composed of values
540 Format: <green0>,<green1>,<green2>,...,<green15>
541 Change the default green palette of the console.
542 This is a 16-member array composed of values
546 Format: <red0>,<red1>,<red2>,...,<red15>
547 Change the default red palette of the console.
548 This is a 16-member array composed of values
553 Set system-wide default UTF-8 mode for all tty's.
554 Default is 0 and by setting to 1, it enables UTF-8
555 mode for all newly opened or allocated terminals.
558 Set number of hash buckets for dentry cache.
561 IO parameters + enable/disable command.
563 digiepca= [HW,SERIAL]
564 See drivers/char/README.epca and
565 Documentation/digiepca.txt.
567 dmasound= [HW,OSS] Sound subsystem buffers
573 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
575 earlyprintk=serial[,ttySn[,baudrate]]
577 Append ",keep" to not disable it when the real console
580 Only vga or serial at a time, not both.
582 Currently only ttyS0 and ttyS1 are supported.
584 Interaction with the standard serial driver is not
587 The VGA output is eventually overwritten by the real
592 ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
595 non-0: interrupt mode (default)
598 Format: {"of[f]" | "sk[ipmbr]"}
599 See comment in arch/i386/boot/edd.S
601 eisa_irq_edge= [PARISC,HW]
602 See header of drivers/parisc/eisa.c.
605 See comment before function elanfreq_setup() in
606 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
609 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
610 See Documentation/block/as-iosched.txt and
611 Documentation/block/deadline-iosched.txt for details.
613 elfcorehdr= [X86-32, X86_64]
614 Specifies physical address of start of kernel core
615 image elf header. Generally kexec loader will
616 pass this option to capture kernel.
617 See Documentation/kdump/kdump.txt for details.
619 enforcing [SELINUX] Set initial enforcing status.
621 See security/selinux/Kconfig help text.
622 0 -- permissive (log only, no denials).
623 1 -- enforcing (deny and log).
625 Value can be changed at runtime via /selinux/enforce.
628 Format: <spdif>,[<nomix>,[<amplifier>]]
629 See also header of sound/oss/es1371.c.
631 ether= [HW,NET] Ethernet cards parameters
632 This option is obsoleted by the "netdev=" option, which
633 has equivalent usage. See its documentation for details.
635 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
640 fail_make_request=[KNL]
641 General fault injection mechanism.
642 Format: <interval>,<probability>,<space>,<times>
643 See also /Documentation/fault-injection/.
646 See header of drivers/scsi/fd_mcs.c.
649 See header of drivers/scsi/fdomain.c.
652 See Documentation/floppy.txt.
655 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
656 support via parallel port (up to 5 devices per port)
657 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
658 See also Documentation/input/joystick-parport.txt
663 See header of drivers/scsi/gdth.c.
665 gpt [EFI] Forces disk with valid GPT signature but
666 invalid Protective MBR to be treated as GPT.
670 hashdist= [KNL,NUMA] Large hashes allocated during boot
671 are distributed across NUMA nodes. Defaults on
672 for IA-64, off otherwise.
673 Format: 0 | 1 (for off | on)
675 hcl= [IA-64] SGI's Hardware Graph compatibility layer
677 hd= [EIDE] (E)IDE hard drive subsystem geometry
678 Format: <cyl>,<head>,<sect>
680 hd?= [HW] (E)IDE subsystem
681 hd?lun= See Documentation/ide.txt.
683 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
684 size of <nn>. This works even on boxes that have no
685 highmem otherwise. This also works to reduce highmem
686 size on bigger boxes.
688 highres= [KNL] Enable/disable high resolution timer mode.
689 Valid parameters: "on", "off"
693 See Documentation/isdn/README.HiSax.
695 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
697 i8042.direct [HW] Put keyboard port into non-translated mode
698 i8042.dumbkbd [HW] Pretend that controller can only read data from
699 keyboard and cannot control its state
700 (Don't attempt to blink the leds)
701 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
702 i8042.nokbd [HW] Don't check/create keyboard port
703 i8042.nomux [HW] Don't check presence of an active multiplexing
705 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
708 [HW] Frequency with which keyboard LEDs should blink
709 when kernel panics (default is 0.5 sec)
710 i8042.reset [HW] Reset the controller during init and cleanup
711 i8042.unlock [HW] Unlock (ignore) the keylock
715 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
716 indicates that the driver is running on unsupported
718 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
719 does not match list of supported models.
721 [HW] Report power status in /proc/i8k
722 (disabled by default)
723 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
726 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
727 See Documentation/mca.txt.
730 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
732 ide= [HW] (E)IDE subsystem
733 Format: ide=nodma or ide=doubler or ide=reverse
734 See Documentation/ide.txt.
736 ide?= [HW] (E)IDE subsystem
737 Format: ide?=noprobe or chipset specific parameters.
738 See Documentation/ide.txt.
740 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
741 See Documentation/ide.txt.
744 Format: idle=poll or idle=mwait
745 Poll forces a polling idle loop that can slightly improves the performance
746 of waking up a idle CPU, but will use a lot of power and make the system
747 run hot. Not recommended.
748 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
749 to not use it because it doesn't save as much power as a normal idle
750 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
753 ignore_loglevel [KNL]
754 Ignore loglevel setting - this will print /all/
755 kernel messages to the console. Useful for debugging.
758 Set number of hash buckets for inode cache.
761 See header of drivers/scsi/in2000.c.
765 Run specified binary instead of /sbin/init as init
768 initcall_debug [KNL] Trace initcalls as they are executed. Useful
769 for working out where the kernel is dying during
772 initrd= [BOOT] Specify the location of the initial ramdisk
774 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
779 io7= [HW] IO7 for Marvel based alpha systems
780 See comment before marvel_specify_io7 in
781 arch/alpha/kernel/core_marvel.c.
784 See Documentation/nfsroot.txt.
786 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
787 See comment before ip2_setup() in
788 drivers/char/ip2/ip2base.c.
790 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
791 See header of drivers/scsi/ips.c.
793 ports= [IP_VS_FTP] IPVS ftp helper module
795 Up to 8 (IP_VS_APP_MAX_PORTS) ports
797 Format: <port>,<port>....
800 When an interrupt is not handled search all handlers
801 for it. Intended to get systems with badly broken
805 When an interrupt is not handled search all handlers
806 for it. Also check all handlers each timer
807 interrupt. Intended to get systems with badly broken
811 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
813 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
815 <cpu number>,...,<cpu number>
817 <cpu number>-<cpu number> (must be a positive range in ascending order)
819 <cpu number>,...,<cpu number>-<cpu number>
820 This option can be used to specify one or more CPUs
821 to isolate from the general SMP balancing and scheduling
822 algorithms. The only way to move a process onto or off
823 an "isolated" CPU is via the CPU affinity syscalls.
824 <cpu number> begins at 0 and the maximum value is
825 "number of CPUs in system - 1".
827 This option is the preferred way to isolate CPUs. The
828 alternative -- manually setting the CPU mask of all
829 tasks in the system -- can cause problems and
830 suboptimal load balancer performance.
834 js= [HW,JOY] Analog joystick
835 See Documentation/input/joystick.txt.
837 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
838 specifies the amount of memory usable by the kernel
839 for non-movable allocations. The requested amount is
840 spread evenly throughout all nodes in the system. The
841 remaining memory in each node is used for Movable
842 pages. In the event, a node is too small to have both
843 kernelcore and Movable pages, kernelcore pages will
844 take priority and other nodes will have a larger number
845 of kernelcore pages. The Movable zone is used for the
846 allocation of pages that may be reclaimed or moved
847 by the page migration subsystem. This means that
848 HugeTLB pages may not be allocated from this zone.
849 Note that allocations like PTEs-from-HighMem still
850 use the HighMem zone if it exists, and the Normal
853 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
854 is similar to kernelcore except it specifies the
855 amount of memory used for migratable allocations.
856 If both kernelcore and movablecore is specified,
857 then kernelcore will be at *least* the specified
858 value but may be more. If movablecore on its own
859 is specified, the administrator must be careful
860 that the amount of memory usable for all allocations
865 kstack=N [X86-32,X86-64] Print N words from the kernel stack
870 lapic [X86-32,APIC] Enable the local APIC even if BIOS
873 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
876 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
880 load_ramdisk= [RAM] List of ramdisks to load from floppy
881 See Documentation/ramdisk.txt.
883 lockd.nlm_grace_period=P [NFS] Assign grace period.
886 lockd.nlm_tcpport=N [NFS] Assign TCP port.
889 lockd.nlm_timeout=T [NFS] Assign timeout value.
892 lockd.nlm_udpport=M [NFS] Assign UDP port.
895 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
898 loglevel= All Kernel Messages with a loglevel smaller than the
899 console loglevel will be printed to the console. It can
900 also be changed with klogd or other programs. The
901 loglevels are defined as follows:
903 0 (KERN_EMERG) system is unusable
904 1 (KERN_ALERT) action must be taken immediately
905 2 (KERN_CRIT) critical conditions
906 3 (KERN_ERR) error conditions
907 4 (KERN_WARNING) warning conditions
908 5 (KERN_NOTICE) normal but significant condition
909 6 (KERN_INFO) informational
910 7 (KERN_DEBUG) debug-level messages
912 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
913 Format: { n | nk | nM }
914 n must be a power of two. The default size
915 is set in the kernel config file.
917 logo.nologo [FB] Disables display of the built-in Linux logo.
918 This may be used to provide more screen space for
919 kernel log messages and is useful when debugging
920 kernel boot problems.
922 lp=0 [LP] Specify parallel ports to use, e.g,
923 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
924 lp=reset first parallel port). 'lp=0' disables the
925 lp=auto printer driver. 'lp=reset' (which can be
926 specified in addition to the ports) causes
927 attached printers to be reset. Using
928 lp=port1,port2,... specifies the parallel ports
929 to associate lp devices with, starting with
930 lp0. A port specification may be 'none' to skip
931 that lp device, or a parport name such as
932 'parport0'. Specifying 'lp=auto' instead of a
933 port specification list means that device IDs
934 from each port should be examined, to see if
935 an IEEE 1284-compliant printer is attached; if
936 so, the driver will manage that printer.
937 See also header of drivers/char/lp.c.
940 Sets loops_per_jiffy to given constant, thus avoiding
941 time-consuming boot-time autodetection (up to 250 ms per
942 CPU). 0 enables autodetection (default). To determine
943 the correct value for your kernel, boot with normal
944 autodetection and see what value is printed. Note that
945 on SMP systems the preset will be applied to all CPUs,
946 which is likely to cause problems if your CPUs need
947 significantly divergent settings. An incorrect value
948 will cause delays in the kernel to be wrong, leading to
949 unpredictable I/O errors and other breakage. Although
950 unlikely, in the extreme case this might damage your
954 Format: <io>,<irq>,<dma>
956 mac5380= [HW,SCSI] Format:
957 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
959 mac53c9x= [HW,SCSI] Format:
960 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
962 machvec= [IA64] Force the use of a particular machine-vector
963 (machvec) in a generic kernel.
964 Example: machvec=hpzx1_swiotlb
966 max_loop= [LOOP] Maximum number of loopback devices that can
970 maxcpus= [SMP] Maximum number of processors that an SMP kernel
971 should make use of. maxcpus=n : n >= 0 limits the
972 kernel to using 'n' processors. n=0 is a special case,
973 it is equivalent to "nosmp", which also disables
976 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
977 equal to this physical address is ignored.
979 max_luns= [SCSI] Maximum number of LUNs to probe.
980 Should be between 1 and 2^32-1.
983 [SCSI] Maximum number of LUNs received.
984 Should be between 1 and 16384.
986 mca-pentium [BUGS=X86-32]
990 mce [X86-32] Machine Check Exception
992 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
994 md= [HW] RAID subsystems devices and level
995 See Documentation/md.txt.
998 Format: <first>,<last>
999 Specifies range of consoles to be captured by the MDA.
1001 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1002 Amount of memory to be used when the kernel is not able
1003 to see the whole system memory or for test.
1004 [X86-32] Use together with memmap= to avoid physical
1005 address space collisions. Without memmap= PCI devices
1006 could be placed at addresses belonging to unused RAM.
1008 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1011 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1012 E820 memory map, as specified by the user.
1013 Such memmap=exactmap lines can be constructed based on
1014 BIOS output or other requirements. See the memmap=nn@ss
1017 memmap=nn[KMG]@ss[KMG]
1018 [KNL] Force usage of a specific region of memory
1019 Region of memory to be used, from ss to ss+nn.
1021 memmap=nn[KMG]#ss[KMG]
1022 [KNL,ACPI] Mark specific memory as ACPI data.
1023 Region of memory to be used, from ss to ss+nn.
1025 memmap=nn[KMG]$ss[KMG]
1026 [KNL,ACPI] Mark specific memory as reserved.
1027 Region of memory to be used, from ss to ss+nn.
1029 meye.*= [HW] Set MotionEye Camera parameters
1030 See Documentation/video4linux/meye.txt.
1032 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1033 Multi-Function General Purpose Timers on AMD Geode
1039 [MOUSE] Maximum time between finger touching and
1040 leaving touchpad surface for touch to be considered
1041 a tap and be reported as a left button click (for
1042 touchpads working in absolute mode only).
1044 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1045 reporting absolute coordinates, such as tablets
1046 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1047 reporting absolute coordinates, such as tablets
1052 MTD_Partition= [MTD]
1053 Format: <name>,<region-number>,<size>,<offset>
1055 MTD_Region= [MTD] Format:
1056 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1059 See drivers/mtd/cmdlinepart.c.
1061 mtouchusb.raw_coordinates=
1062 [HW] Make the MicroTouch USB driver use raw coordinates
1063 ('y', default) or cooked coordinates ('n')
1065 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1068 See header of drivers/scsi/NCR_D700.c.
1072 ncr53c400= [HW,SCSI]
1074 ncr53c400a= [HW,SCSI]
1076 ncr53c406a= [HW,SCSI]
1078 ncr53c8xx= [HW,SCSI]
1080 netdev= [NET] Network devices parameters
1081 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1082 Note that mem_start is often overloaded to mean
1083 something different and driver-specific.
1084 This usage is only documented in each driver source
1088 See Documentation/nfsroot.txt.
1090 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1091 See Documentation/nfsroot.txt.
1093 nfs.callback_tcpport=
1094 [NFS] set the TCP port on which the NFSv4 callback
1095 channel should listen.
1097 nfs.idmap_cache_timeout=
1098 [NFS] set the maximum lifetime for idmapper cache
1102 [NFS] enable 64-bit inode numbers.
1103 If zero, the NFS client will fake up a 32-bit inode
1104 number for the readdir() and stat() syscalls instead
1105 of returning the full 64-bit number.
1106 The default is to return 64-bit inode numbers.
1108 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1110 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1111 emulation library even if a 387 maths coprocessor
1114 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1115 caches in the slab allocator. Saves per-node memory,
1116 but will impact performance.
1120 noapic [SMP,APIC] Tells the kernel to not make use of any
1121 IOAPICs that may be present in the system.
1123 nobats [PPC] Do not use BATs for mapping kernel lowmem
1124 on "Classic" PPC cores.
1128 nodelayacct [KNL] Disable per-task delay accounting
1130 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1134 noexec [X86-32,X86-64]
1135 noexec=on: enable non-executable mappings (default)
1136 noexec=off: disable nn-executable mappings
1138 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1139 register save and restore. The kernel will only save
1140 legacy floating-point registers on task switch.
1144 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1145 instruction doesn't work correctly and not to
1148 nohalt [IA-64] Tells the kernel not to use the power saving
1149 function PAL_HALT_LIGHT when idle. This increases
1150 power-consumption. On the positive side, it reduces
1151 interrupt wake-up latency, which may improve performance
1152 in certain environments such as networked servers or
1155 nohz= [KNL] Boottime enable/disable dynamic ticks
1156 Valid arguments: on, off
1159 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1161 noirqdebug [X86-32] Disables the code which attempts to detect and
1162 disable unhandled interrupt sources.
1164 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1165 broken timer IRQ sources.
1167 noisapnp [ISAPNP] Disables ISA PnP code.
1169 noinitrd [RAM] Tells the kernel not to load any configured
1174 nojitter [IA64] Disables jitter checking for ITC timers.
1176 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1178 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1180 noltlbs [PPC] Do not use large page/tlb entries for kernel
1181 lowmem mapping on PPC40x.
1183 nomca [IA-64] Disable machine check abort handling
1185 nomce [X86-32] Machine Check Exception
1187 nomfgpt [X86-32] Disable Multi-Function General Purpose
1188 Timer usage (for AMD Geode machines).
1190 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1192 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1193 with UP alternatives
1195 noresidual [PPC] Don't use residual data on PReP machines.
1197 noresume [SWSUSP] Disables resume and restores original swap
1200 no-scroll [VGA] Disables scrollback.
1201 This is required for the Braillex ib80-piezo Braille
1202 reader made by F.H. Papenmeier (Germany).
1206 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1208 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1209 and disable the IO APIC. legacy for "maxcpus=0".
1211 nosoftlockup [KNL] Disable the soft-lockup detector.
1213 nosync [HW,M68K] Disables sync negotiation for all devices.
1215 notsc [BUGS=X86-32] Disable Time Stamp Counter
1217 nousb [USB] Disable the USB subsystem
1221 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1222 one of ['zone', 'node', 'default'] can be specified
1223 This can be set from sysctl after boot.
1224 See Documentation/sysctl/vm.txt for details.
1226 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1231 oprofile.timer= [HW]
1232 Use timer interrupt instead of performance counters
1234 osst= [HW,SCSI] SCSI Tape Driver
1235 Format: <buffer_size>,<write_threshold>
1236 See also Documentation/scsi/st.txt.
1238 panic= [KNL] Kernel behaviour on panic
1241 parkbd.port= [HW] Parallel port number the keyboard adapter is
1242 connected to, default is 0.
1244 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1245 0 for XT, 1 for AT (default is AT).
1248 parport= [HW,PPT] Specify parallel ports. 0 disables.
1249 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1250 Use 'auto' to force the driver to use any
1251 IRQ/DMA settings detected (the default is to
1252 ignore detected IRQ/DMA settings because of
1253 possible conflicts). You can specify the base
1254 address, IRQ, and DMA settings; IRQ and DMA
1255 should be numbers, or 'auto' (for using detected
1256 settings on that particular port), or 'nofifo'
1257 (to avoid using a FIFO even if it is detected).
1258 Parallel ports are assigned in the order they
1259 are specified on the command line, starting
1262 parport_init_mode= [HW,PPT]
1263 Configure VIA parallel port to operate in
1264 a specific mode. This is necessary on Pegasos
1265 computer where firmware has no options for setting
1266 up parallel port mode and sets it to spp.
1267 Currently this function knows 686a and 8231 chips.
1268 Format: [spp|ps2|epp|ecp|ecpepp]
1270 pas2= [HW,OSS] Format:
1271 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1274 See header of drivers/scsi/pas16.c.
1277 Halt all CPUs after the first oops has been printed for
1278 the specified number of seconds. This is to be used if
1279 your oopses keep scrolling off the screen.
1284 See header of drivers/block/paride/pcd.c.
1285 See also Documentation/paride.txt.
1287 pci=option[,option...] [PCI] various PCI subsystem options:
1288 off [X86-32] don't probe for the PCI bus
1289 bios [X86-32] force use of PCI BIOS, don't access
1290 the hardware directly. Use this if your machine
1291 has a non-standard PCI host bridge.
1292 nobios [X86-32] disallow use of PCI BIOS, only direct
1293 hardware access methods are allowed. Use this
1294 if you experience crashes upon bootup and you
1295 suspect they are caused by the BIOS.
1296 conf1 [X86-32] Force use of PCI Configuration
1298 conf2 [X86-32] Force use of PCI Configuration
1300 noaer [PCIE] If the PCIEAER kernel config parameter is
1301 enabled, this kernel boot option can be used to
1302 disable the use of PCIE advanced error reporting.
1303 nodomains [PCI] Disable support for multiple PCI
1304 root domains (aka PCI segments, in ACPI-speak).
1305 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1307 nomsi [MSI] If the PCI_MSI kernel config parameter is
1308 enabled, this kernel boot option can be used to
1309 disable the use of MSI interrupts system-wide.
1310 nosort [X86-32] Don't sort PCI devices according to
1311 order given by the PCI BIOS. This sorting is
1312 done to get a device order compatible with
1314 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1315 routing table. These calls are known to be buggy
1316 on several machines and they hang the machine
1317 when used, but on other computers it's the only
1318 way to get the interrupt routing table. Try
1319 this option if the kernel is unable to allocate
1320 IRQs or discover secondary PCI buses on your
1322 rom [X86-32] Assign address space to expansion ROMs.
1323 Use with caution as certain devices share
1324 address decoders between ROMs and other
1326 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1327 assigned automatically to PCI devices. You can
1328 make the kernel exclude IRQs of your ISA cards
1330 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1331 of the PIRQ table (normally generated
1332 by the BIOS) if it is outside the
1333 F0000h-100000h range.
1334 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1335 useful if the kernel is unable to find your
1336 secondary buses and you want to tell it
1337 explicitly which ones they are.
1338 assign-busses [X86-32] Always assign all PCI bus
1339 numbers ourselves, overriding
1340 whatever the firmware may have done.
1341 usepirqmask [X86-32] Honor the possible IRQ mask stored
1342 in the BIOS $PIR table. This is needed on
1343 some systems with broken BIOSes, notably
1344 some HP Pavilion N5400 and Omnibook XE3
1345 notebooks. This will have no effect if ACPI
1346 IRQ routing is enabled.
1347 noacpi [X86-32] Do not use ACPI for IRQ routing
1348 or for PCI scanning.
1349 use_crs [X86-32] Use _CRS for PCI resource
1351 routeirq Do IRQ routing for all PCI devices.
1352 This is normally done in pci_enable_device(),
1353 so this option is a temporary workaround
1354 for broken drivers that don't call it.
1355 firmware [ARM] Do not re-enumerate the bus but instead
1356 just use the configuration from the
1357 bootloader. This is currently used on
1358 IXP2000 systems where the bus has to be
1359 configured a certain way for adjunct CPUs.
1360 noearly [X86] Don't do any early type 1 scanning.
1361 This might help on some broken boards which
1362 machine check when some devices' config space
1363 is read. But various workarounds are disabled
1364 and some IOMMU drivers will not work.
1365 bfsort Sort PCI devices into breadth-first order.
1366 This sorting is done to get a device
1367 order compatible with older (<= 2.4) kernels.
1368 nobfsort Don't sort PCI devices into breadth-first order.
1369 cbiosize=nn[KMG] The fixed amount of bus space which is
1370 reserved for the CardBus bridge's IO window.
1371 The default value is 256 bytes.
1372 cbmemsize=nn[KMG] The fixed amount of bus space which is
1373 reserved for the CardBus bridge's memory
1374 window. The default value is 64 megabytes.
1376 pcmv= [HW,PCMCIA] BadgePAD 4
1379 See Documentation/paride.txt.
1381 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1384 See arch/parisc/kernel/pdc_chassis.c
1387 See Documentation/paride.txt.
1390 See Documentation/paride.txt.
1392 pirq= [SMP,APIC] Manual mp-table setup
1393 See Documentation/i386/IO-APIC.txt.
1395 plip= [PPT,NET] Parallel port network link
1396 Format: { parport<nr> | timid | 0 }
1397 See also Documentation/parport.txt.
1403 { on | off | curr | res | no-curr | no-res }
1406 [ISAPNP] Exclude IRQs for the autoconfiguration
1409 [ISAPNP] Exclude DMAs for the autoconfiguration
1411 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1412 Ranges are in pairs (I/O port base and size).
1415 [ISAPNP] Exclude memory regions for the
1417 Ranges are in pairs (memory base and size).
1419 print-fatal-signals=
1420 [KNL] debug: print fatal signals
1421 print-fatal-signals=1: print segfault info to
1425 printk.time= Show timing data prefixed to each printk message line
1426 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1428 profile= [KNL] Enable kernel profiling via /proc/profile
1429 Format: [schedule,]<number>
1430 Param: "schedule" - profile schedule points.
1431 Param: <number> - step/bucket size as a power of 2 for
1432 statistical time based profiling.
1433 Param: "sleep" - profile D-state sleeping (millisecs)
1435 processor.max_cstate= [HW,ACPI]
1436 Limit processor to maximum C-state
1437 max_cstate=9 overrides any DMI blacklist limit.
1439 processor.nocst [HW,ACPI]
1440 Ignore the _CST method to determine C-states,
1441 instead using the legacy FADT method
1443 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1445 See Documentation/ramdisk.txt.
1447 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1448 probe for; one of (bare|imps|exps|lifebook|any).
1449 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1451 psmouse.resetafter= [HW,MOUSE]
1452 Try to reset the device after so many bad packets
1455 [HW,MOUSE] Set desired mouse resolution, in dpi.
1456 psmouse.smartscroll=
1457 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1458 0 = disabled, 1 = enabled (default).
1460 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1462 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1465 See Documentation/paride.txt.
1468 [KNL] Number of legacy pty's. Overwrites compiled-in
1471 quiet [KNL] Disable most log messages
1476 See Documentation/md.txt.
1478 ramdisk_blocksize= [RAM]
1479 See Documentation/ramdisk.txt.
1481 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1482 See Documentation/ramdisk.txt.
1484 rcu.blimit= [KNL,BOOT] Set maximum number of finished
1485 RCU callbacks to process in one batch.
1487 rcu.qhimark= [KNL,BOOT] Set threshold of queued
1488 RCU callbacks over which batch limiting is disabled.
1490 rcu.qlowmark= [KNL,BOOT] Set threshold of queued
1491 RCU callbacks below which batch limiting is re-enabled.
1495 Run specified binary instead of /init from the ramdisk,
1496 used for early userspace startup. See initrd.
1498 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1499 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1500 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1502 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1504 reservetop= [X86-32]
1506 Reserves a hole at the top of the kernel virtual
1509 reset_devices [KNL] Force drivers to reset the underlying device
1510 during initialization.
1513 Specify the partition device for software suspend
1515 resume_offset= [SWSUSP]
1516 Specify the offset from the beginning of the partition
1517 given by "resume=" at which the swap header is located,
1518 in <PAGE_SIZE> units (needed only for swap files).
1519 See Documentation/power/swsusp-and-swap-files.txt
1521 retain_initrd [RAM] Keep initrd memory after extraction
1523 rhash_entries= [KNL,NET]
1524 Set number of hash buckets for route cache
1526 riscom8= [HW,SERIAL]
1527 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1529 ro [KNL] Mount root device read-only on boot
1531 root= [KNL] Root filesystem
1533 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1534 mount the root filesystem
1536 rootflags= [KNL] Set root filesystem mount option string
1538 rootfstype= [KNL] Set root filesystem type
1540 rootwait [KNL] Wait (indefinitely) for root device to show up.
1541 Useful for devices that are detected asynchronously
1542 (e.g. USB and MMC devices).
1544 root_plug.vendor_id=
1545 [ROOTPLUG] Override the default vendor ID
1547 root_plug.product_id=
1548 [ROOTPLUG] Override the default product ID
1551 [ROOTPLUG] Enable debugging output
1553 rw [KNL] Mount root device read-write on boot
1555 S [KNL] Run init in single mode
1558 See drivers/net/irda/sa1100_ir.c.
1560 sbni= [NET] Granch SBNI12 leased line adapter
1562 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1563 Format: <io>[,<timeout>[,<isapnp>]]
1565 scsi_debug_*= [SCSI]
1566 See drivers/scsi/scsi_debug.c.
1568 scsi_default_dev_flags=
1569 [SCSI] SCSI default device flags
1572 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1573 Format: <vendor>:<model>:<flags>
1574 (flags are integer value)
1576 scsi_logging= [SCSI]
1578 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1579 discovered. async scans them in kernel threads,
1580 allowing boot to proceed. none ignores them, expecting
1581 user space to do the scan.
1583 selinux [SELINUX] Disable or enable SELinux at boot time.
1584 Format: { "0" | "1" }
1585 See security/selinux/Kconfig help text.
1588 Default value is set via kernel config option.
1589 If enabled at boot time, /selinux/disable can be used
1590 later to disable prior to initial policy load.
1592 selinux_compat_net =
1593 [SELINUX] Set initial selinux_compat_net flag value.
1594 Format: { "0" | "1" }
1595 0 -- use new secmark-based packet controls
1596 1 -- use legacy packet controls
1597 Default value is 0 (preferred).
1598 Value can be changed at runtime via
1599 /selinux/compat_net.
1601 serialnumber [BUGS=X86-32]
1604 Maximal number of shapers.
1607 See header of drivers/scsi/sim710.c.
1614 slub_debug[=options[,slabs]] [MM, SLUB]
1615 Enabling slub_debug allows one to determine the
1616 culprit if slab objects become corrupted. Enabling
1617 slub_debug can create guard zones around objects and
1618 may poison objects when not in use. Also tracks the
1619 last alloc / free. For more information see
1620 Documentation/vm/slub.txt.
1622 slub_max_order= [MM, SLUB]
1623 Determines the maximum allowed order for slabs.
1624 A high setting may cause OOMs due to memory
1625 fragmentation. For more information see
1626 Documentation/vm/slub.txt.
1628 slub_min_objects= [MM, SLUB]
1629 The minimum number of objects per slab. SLUB will
1630 increase the slab order up to slub_max_order to
1631 generate a sufficiently large slab able to contain
1632 the number of objects indicated. The higher the number
1633 of objects the smaller the overhead of tracking slabs
1634 and the less frequently locks need to be acquired.
1635 For more information see Documentation/vm/slub.txt.
1637 slub_min_order= [MM, SLUB]
1638 Determines the mininum page order for slabs. Must be
1639 lower than slub_max_order.
1640 For more information see Documentation/vm/slub.txt.
1642 slub_nomerge [MM, SLUB]
1643 Disable merging of slabs with similar size. May be
1644 necessary if there is some reason to distinguish
1645 allocs to different slabs. Debug options disable
1646 merging on their own.
1647 For more information see Documentation/vm/slub.txt.
1650 Format: <io1>[,<io2>[,...,<io8>]]
1652 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1653 attempt to substitute SMP alternatives once at boot.
1655 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1656 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1657 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1658 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1659 smsc-ircc2.ircc_irq= [HW] IRQ line
1660 smsc-ircc2.ircc_dma= [HW] DMA channel
1661 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1662 0: Toshiba Satellite 1800 (GP data pin select)
1663 1: Fast pin select (default)
1666 snd-ad1816a= [HW,ALSA]
1668 snd-ad1848= [HW,ALSA]
1670 snd-ali5451= [HW,ALSA]
1672 snd-als100= [HW,ALSA]
1674 snd-als4000= [HW,ALSA]
1676 snd-azt2320= [HW,ALSA]
1678 snd-cmi8330= [HW,ALSA]
1680 snd-cmipci= [HW,ALSA]
1682 snd-cs4231= [HW,ALSA]
1684 snd-cs4232= [HW,ALSA]
1686 snd-cs4236= [HW,ALSA]
1688 snd-cs4281= [HW,ALSA]
1690 snd-cs46xx= [HW,ALSA]
1692 snd-dt019x= [HW,ALSA]
1694 snd-dummy= [HW,ALSA]
1696 snd-emu10k1= [HW,ALSA]
1698 snd-ens1370= [HW,ALSA]
1700 snd-ens1371= [HW,ALSA]
1702 snd-es968= [HW,ALSA]
1704 snd-es1688= [HW,ALSA]
1706 snd-es18xx= [HW,ALSA]
1708 snd-es1938= [HW,ALSA]
1710 snd-es1968= [HW,ALSA]
1712 snd-fm801= [HW,ALSA]
1714 snd-gusclassic= [HW,ALSA]
1716 snd-gusextreme= [HW,ALSA]
1718 snd-gusmax= [HW,ALSA]
1722 snd-ice1712= [HW,ALSA]
1724 snd-intel8x0= [HW,ALSA]
1726 snd-interwave= [HW,ALSA]
1731 snd-korg1212= [HW,ALSA]
1733 snd-maestro3= [HW,ALSA]
1735 snd-mpu401= [HW,ALSA]
1737 snd-mtpav= [HW,ALSA]
1739 snd-nm256= [HW,ALSA]
1741 snd-opl3sa2= [HW,ALSA]
1749 snd-opti93x= [HW,ALSA]
1753 snd-rme32= [HW,ALSA]
1755 snd-rme96= [HW,ALSA]
1757 snd-rme9652= [HW,ALSA]
1763 snd-sbawe= [HW,ALSA]
1765 snd-serial= [HW,ALSA]
1767 snd-sgalaxy= [HW,ALSA]
1769 snd-sonicvibes= [HW,ALSA]
1774 snd-sun-cs4231= [HW,ALSA]
1776 snd-trident= [HW,ALSA]
1778 snd-usb-audio= [HW,ALSA,USB]
1780 snd-via82xx= [HW,ALSA]
1782 snd-virmidi= [HW,ALSA]
1784 snd-wavefront= [HW,ALSA]
1786 snd-ymfpci= [HW,ALSA]
1788 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1789 See Documentation/sonypi.txt
1791 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1792 See Documentation/specialix.txt.
1794 spia_io_base= [HW,MTD]
1800 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1802 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1803 See Documentation/scsi/st.txt.
1806 See header of drivers/scsi/seagate.c.
1810 Set the STI (builtin display/keyboard on the HP-PARISC
1811 machines) console (graphic card) which should be used
1812 as the initial boot-console.
1813 See also comment in drivers/video/console/sticore.c.
1816 See comment in drivers/video/console/sticore.c.
1819 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1823 Control how the NFS server code allocates CPUs to
1824 service thread pools. Depending on how many NICs
1825 you have and where their interrupts are bound, this
1826 option will affect which CPUs will do NFS serving.
1827 Note: this parameter cannot be changed while the
1828 NFS server is running.
1830 auto the server chooses an appropriate mode
1831 automatically using heuristics
1832 global a single global pool contains all CPUs
1833 percpu one pool for each CPU
1834 pernode one pool for each NUMA node (equivalent
1835 to global on non-NUMA machines)
1837 swiotlb= [IA-64] Number of I/O TLB slabs
1841 sym53c416= [HW,SCSI]
1842 See header of drivers/scsi/sym53c416.c.
1844 sysrq_always_enabled
1846 Ignore sysrq setting - this boot parameter will
1847 neutralize any effect of /proc/sys/kernel/sysrq.
1848 Useful for debugging.
1851 See header of drivers/scsi/t128.c.
1855 thash_entries= [KNL,NET]
1856 Set number of hash buckets for TCP connection
1858 thermal.act= [HW,ACPI]
1859 -1: disable all active trip points in all thermal zones
1860 <degrees C>: override all lowest active trip points
1862 thermal.crt= [HW,ACPI]
1863 -1: disable all critical trip points in all thermal zones
1864 <degrees C>: lower all critical trip points
1866 thermal.nocrt= [HW,ACPI]
1867 Set to disable actions on ACPI thermal zone
1868 critical and hot trip points.
1870 thermal.off= [HW,ACPI]
1871 1: disable ACPI thermal control
1873 thermal.psv= [HW,ACPI]
1874 -1: disable all passive trip points
1875 <degrees C>: override all passive trip points to this value
1877 thermal.tzp= [HW,ACPI]
1878 Specify global default ACPI thermal zone polling rate
1879 <deci-seconds>: poll all this frequency
1880 0: no polling (default)
1882 time Show timing data prefixed to each printk message line
1883 [deprecated, see 'printk.time']
1885 tipar.timeout= [HW,PPT]
1886 Set communications timeout in tenths of a second
1889 tipar.delay= [HW,PPT]
1890 Set inter-bit delay in microseconds (default 10).
1893 See header of drivers/scsi/seagate.c.
1896 See comment before function dc390_setup() in
1897 drivers/scsi/tmscsim.c.
1901 trix= [HW,OSS] MediaTrix AudioTrix Pro
1903 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
1905 turbografx.map[2|3]= [HW,JOY]
1906 TurboGraFX parallel port interface
1908 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
1909 See also Documentation/input/joystick-parport.txt
1911 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
1912 See header of drivers/scsi/u14-34f.c.
1921 [USB] Ignore overcurrent events (default N).
1922 Some badly-designed motherboards generate lots of
1923 bogus events, for ports that aren't wired to
1924 anything. Set this parameter to avoid log spamming.
1925 Note that genuine overcurrent events won't be
1928 usbcore.autosuspend=
1929 [USB] The autosuspend time delay (in seconds) used
1930 for newly-detected USB devices (default 2). This
1931 is the time required before an idle device will be
1932 autosuspended. Devices for which the delay is set
1933 to a negative value won't be autosuspended at all.
1936 [USBHID] The interval which mice are to be polled at.
1938 vdso= [X86-32,SH,x86-64]
1939 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
1940 vdso=1: enable VDSO (default)
1941 vdso=0: disable VDSO mapping
1944 vector=percpu: enable percpu vector domain
1946 video= [FB] Frame buffer configuration
1947 See Documentation/fb/modedb.txt.
1949 vga= [BOOT,X86-32] Select a particular video mode
1950 See Documentation/i386/boot.txt and
1951 Documentation/svga.txt.
1952 Use vga=ask for menu.
1953 This is actually a boot loader parameter; the value is
1954 passed to the kernel using a special protocol.
1956 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
1957 size of <nn>. This can be used to increase the
1958 minimum size (128MB on x86). It can also be used to
1959 decrease the size and leave more room for directly
1962 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
1965 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
1968 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
1971 waveartist= [HW,OSS]
1972 Format: <io>,<irq>,<dma>,<dma2>
1975 See header of drivers/scsi/wd33c93.c.
1978 See header of drivers/scsi/wd7000.c.
1981 See Documentation/watchdog/wdt.txt.
1983 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
1984 xd_geo= See header of drivers/block/xd.c.
1986 xirc2ps_cs= [NET,PCMCIA]
1988 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
1990 norandmaps Don't use address space randomization
1991 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
1993 ______________________________________________________________________
1997 Add documentation for ALSA options.
1998 Add more DRM drivers.