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/power/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, s3_beep }
151 See Documentation/power/video.txt for s3_bios and s3_mode.
152 s3_beep is for debugging; it makes the PC's speaker beep
153 as soon as the kernel's real-mode entry point is called.
155 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
156 Format: { level | edge | high | low }
158 acpi_irq_balance [HW,ACPI]
159 ACPI will balance active IRQs
162 acpi_irq_nobalance [HW,ACPI]
163 ACPI will not move active IRQs (default)
166 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
168 Format: <irq>,<irq>...
170 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
171 Format: <irq>,<irq>...
173 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
175 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
176 Format: To spoof as Windows 98: ="Microsoft Windows"
178 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
179 acpi_osi="string1" # add string1 -- only one string
180 acpi_osi="!string2" # remove built-in string2
181 acpi_osi= # disable all strings
183 acpi_serialize [HW,ACPI] force serialization of AML methods
185 acpi_skip_timer_override [HW,ACPI]
186 Recognize and ignore IRQ0/pin2 Interrupt Override.
187 For broken nForce2 BIOS resulting in XT-PIC timer.
188 acpi_use_timer_override [HW,ACPI}
189 Use timer override. For some broken Nvidia NF5 boards
190 that require a timer override, but don't have
193 acpi.debug_layer= [HW,ACPI]
195 Each bit of the <int> indicates an ACPI debug layer,
196 1: enable, 0: disable. It is useful for boot time
197 debugging. After system has booted up, it can be set
198 via /sys/module/acpi/parameters/debug_layer.
199 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
200 Available bits (add the numbers together) to enable debug output
201 for specific parts of the ACPI subsystem:
202 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
203 0x10 namespace 0x20 parser 0x40 dispatcher
204 0x80 executer 0x100 resources 0x200 acpica debugger
205 0x400 os services 0x800 acpica disassembler.
206 The number can be in decimal or prefixed with 0x in hex.
207 Warning: Many of these options can produce a lot of
208 output and make your system unusable. Be very careful.
210 acpi.debug_level= [HW,ACPI]
212 Each bit of the <int> indicates an ACPI debug level,
213 1: enable, 0: disable. It is useful for boot time
214 debugging. After system has booted up, it can be set
215 via /sys/module/acpi/parameters/debug_level.
216 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
217 Available bits (add the numbers together) to enable different
218 debug output levels of the ACPI subsystem:
219 0x01 error 0x02 warn 0x04 init 0x08 debug object
220 0x10 info 0x20 init names 0x40 parse 0x80 load
221 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
222 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
223 0x10000 resources 0x20000 user requests 0x40000 package.
224 The number can be in decimal or prefixed with 0x in hex.
225 Warning: Many of these options can produce a lot of
226 output and make your system unusable. Be very careful.
228 acpi_pm_good [X86-32,X86-64]
229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
234 { off | try_unsupported }
235 off: disable AGP support
236 try_unsupported: try to drive unsupported chipsets
237 (may crash computer or cause data corruption)
239 enable_timer_pin_1 [i386,x86-64]
240 Enable PIN 1 of APIC timer
241 Can be useful to work around chipset bugs
242 (in particular on some ATI chipsets).
243 The kernel tries to set a reasonable default.
245 disable_timer_pin_1 [i386,x86-64]
246 Disable PIN 1 of APIC timer
247 Can be useful to work around chipset bugs.
250 Format: <io>,<irq>,<dma>,<dma2>,<type>
253 See header of drivers/scsi/advansys.c.
255 advwdt= [HW,WDT] Advantech WDT
256 Format: <iostart>,<iostop>
258 aedsp16= [HW,OSS] Audio Excel DSP 16
259 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
260 See also header of sound/oss/aedsp16.c.
263 See Documentation/scsi/aha152x.txt.
266 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
269 See Documentation/scsi/aic7xxx.txt.
272 See Documentation/scsi/aic79xx.txt.
274 amijoy.map= [HW,JOY] Amiga joystick support
275 Map of devices attached to JOY0DAT and JOY1DAT
277 See also Documentation/kernel/input/joystick.txt
279 analog.map= [HW,JOY] Analog joystick and gamepad support
280 Specifies type or capabilities of an analog joystick
281 connected to one of 16 gameports
282 Format: <type1>,<type2>,..<type16>
285 Power management functions (SPARCstation-4/5 + deriv.)
287 Disable APC CPU standby support. SPARCstation-Fox does
288 not play well with APC CPU idle - disable it if you have
289 APC and your system crashes randomly.
291 apic= [APIC,i386] Advanced Programmable Interrupt Controller
292 Change the output verbosity whilst booting
293 Format: { quiet (default) | verbose | debug }
294 Change the amount of debugging information output
295 when initialising the APIC and IO-APIC components.
297 apm= [APM] Advanced Power Management
298 See header of arch/i386/kernel/apm.c.
300 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
301 Format: <io>,<irq>,<nodeID>
305 atarimouse= [HW,MOUSE] Atari Mouse
307 atascsi= [HW,SCSI] Atari SCSI
309 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
310 EzKey and similar keyboards
312 atkbd.reset= [HW] Reset keyboard during initialization
314 atkbd.set= [HW] Select keyboard code set
315 Format: <int> (2 = AT (default), 3 = PS/2)
317 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
320 atkbd.softraw= [HW] Choose between synthetic and real raw mode
321 Format: <bool> (0 = real, 1 = synthetic (default))
323 atkbd.softrepeat= [HW]
324 Use software keyboard repeat
328 baycom_epp= [HW,AX25]
331 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
333 See header of drivers/net/hamradio/baycom_par.c.
335 baycom_ser_fdx= [HW,AX25]
336 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
337 Format: <io>,<irq>,<mode>[,<baud>]
338 See header of drivers/net/hamradio/baycom_ser_fdx.c.
340 baycom_ser_hdx= [HW,AX25]
341 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
342 Format: <io>,<irq>,<mode>
343 See header of drivers/net/hamradio/baycom_ser_hdx.c.
345 boot_delay= Milliseconds to delay each printk during boot.
346 Values larger than 10 seconds (10000) are changed to
350 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
351 bttv.radio= Most important insmod options are available as
353 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
354 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
357 See drivers/scsi/BusLogic.c, comment before function
358 BusLogic_ParseDriverOptions().
360 c101= [NET] Moxa C101 synchronous serial card
362 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
363 Sometimes CPU hardware bugs make them report the cache
364 size incorrectly. The kernel will attempt work arounds
365 to fix known problems, but for some CPUs it is not
366 possible to determine what the correct size should be.
367 This option provides an override for these situations.
369 security= [SECURITY] Choose a security module to enable at boot.
370 If this boot parameter is not specified, only the first
371 security module asking for security registration will be
372 loaded. An invalid security module name will be treated
373 as if no module has been chosen.
376 [SECURITY] Disable capabilities. This would normally
377 be used only if an alternative security model is to be
378 configured. Potentially dangerous and should only be
379 used if you are entirely sure of the consequences.
381 ccw_timeout_log [S390]
382 See Documentation/s390/CommonIO for details.
384 cgroup_disable= [KNL] Disable a particular controller
385 Format: {name of the controller(s) to disable}
386 {Currently supported controllers - "memory"}
388 checkreqprot [SELINUX] Set initial checkreqprot flag value.
389 Format: { "0" | "1" }
390 See security/selinux/Kconfig help text.
391 0 -- check protection applied by kernel (includes
392 any implied execute protection).
393 1 -- check protection requested by application.
394 Default value is set via a kernel config option.
395 Value can be changed at runtime via
396 /selinux/checkreqprot.
399 See Documentation/s390/CommonIO for details.
402 See Documentation/s390/CommonIO for details.
404 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
406 Forces specified clocksource (if available) to be used
407 when calculating gettimeofday(). If specified
408 clocksource is not available, it defaults to PIT.
409 Format: { pit | tsc | cyclone | pmtmr }
411 clocksource= [GENERIC_TIME] Override the default clocksource
413 Override the default clocksource and use the clocksource
414 with the name specified.
415 Some clocksource names to choose from, depending on
417 [all] jiffies (this is the base, fallback clocksource)
419 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
420 pxa_timer,timer3,32k_counter,timer0_1
422 [X86-32] pit,hpet,tsc,vmi-timer;
423 scx200_hrt on Geode; cyclone on IBM x440
431 clearcpuid=BITNUM [X86]
432 Disable CPUID feature X for the kernel. See
433 include/asm-x86/cpufeature.h for the valid bit numbers.
434 Note the Linux specific bits are not necessarily
435 stable over kernel options, but the vendor specific
437 Also note that user programs calling CPUID directly
438 or using the feature without checking anything
439 will still see it. This just prevents it from
440 being used by the kernel or shown in /proc/cpuinfo.
441 Also note the kernel might malfunction if you disable
444 code_bytes [IA32/X86_64] How many bytes of object code to print
451 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
452 over the 8254 in addition to over the IO-APIC. The
453 kernel tries to set a sensible default.
455 hpet= [X86-32,HPET] option to control HPET usage
456 Format: { enable (default) | disable | force }
457 disable: disable HPET and use PIT instead
458 force: allow force enabled of undocumented chips (ICH4,
461 com20020= [HW,NET] ARCnet - COM20020 chipset
463 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
465 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
469 ARCnet - COM90xx chipset (memory-mapped buffers)
470 Format: <io>[,<irq>[,<memstart>]]
472 condev= [HW,S390] console device
475 console= [KNL] Output console device and options.
477 tty<n> Use the virtual console device <n>.
481 Use the specified serial port. The options are of
482 the form "bbbbpnf", where "bbbb" is the baud rate,
483 "p" is parity ("n", "o", or "e"), "n" is number of
484 bits, and "f" is flow control ("r" for RTS or
485 omit it). Default is "9600n8".
487 See Documentation/serial-console.txt for more
489 Documentation/networking/netconsole.txt for an
492 uart[8250],io,<addr>[,options]
493 uart[8250],mmio,<addr>[,options]
494 Start an early, polled-mode console on the 8250/16550
495 UART at the specified I/O port or MMIO address,
496 switching to the matching ttyS device later. The
497 options are the same as for ttyS, above.
499 earlycon= [KNL] Output early console device and options.
500 uart[8250],io,<addr>[,options]
501 uart[8250],mmio,<addr>[,options]
502 Start an early, polled-mode console on the 8250/16550
503 UART at the specified I/O port or MMIO address.
504 The options are the same as for ttyS, above.
507 [HW] Never suspend the console
508 Disable suspending of consoles during suspend and
509 hibernate operations. Once disabled, debugging
510 messages can reach various consoles while the rest
511 of the system is being put to sleep (ie, while
512 debugging driver suspend/resume hooks). This may
513 not work reliably with all consoles, but is known
514 to work with serial and VGA consoles.
516 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
518 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
520 crashkernel=nn[KMG]@ss[KMG]
521 [KNL] Reserve a chunk of physical memory to
522 hold a kernel to switch to with kexec on panic.
524 crashkernel=range1:size1[,range2:size2,...][@offset]
525 [KNL] Same as above, but depends on the memory
526 in the running system. The syntax of range is
527 start-[end] where start and end are both
528 a memory unit (amount[KMG]). See also
529 Documentation/kdump/kdump.txt for a example.
532 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
537 cs89x0_media= [HW,NET]
538 Format: { rj45 | aui | bnc }
541 See header of drivers/s390/block/dasd_devmap.c.
543 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
544 (one device per port)
545 Format: <port#>,<type>
546 See also Documentation/input/joystick-parport.txt
548 debug [KNL] Enable kernel debugging (events log level).
551 [KNL] verbose self-tests
553 Print debugging info while doing the locking API
555 We default to 0 (no extra messages), setting it to
556 1 will print _a lot_ more information - normally
557 only useful to kernel developers.
559 decnet.addr= [HW,NET]
560 Format: <area>[,<node>]
561 See also Documentation/networking/decnet.txt.
564 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
565 Change the default blue palette of the console.
566 This is a 16-member array composed of values
570 Format: <green0>,<green1>,<green2>,...,<green15>
571 Change the default green palette of the console.
572 This is a 16-member array composed of values
576 Format: <red0>,<red1>,<red2>,...,<red15>
577 Change the default red palette of the console.
578 This is a 16-member array composed of values
584 Set system-wide default UTF-8 mode for all tty's.
585 Default is 1, i.e. UTF-8 mode is enabled for all
586 newly opened terminals.
589 Set number of hash buckets for dentry cache.
592 IO parameters + enable/disable command.
594 digiepca= [HW,SERIAL]
595 See drivers/char/README.epca and
596 Documentation/digiepca.txt.
598 disable_mtrr_trim [X86, Intel and AMD only]
599 By default the kernel will trim any uncacheable
600 memory out of your available memory pool based on
601 MTRR settings. This parameter disables that behavior,
602 possibly causing your machine to run very slowly.
604 dmasound= [HW,OSS] Sound subsystem buffers
610 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
612 earlyprintk=serial[,ttySn[,baudrate]]
614 Append ",keep" to not disable it when the real console
617 Only vga or serial at a time, not both.
619 Currently only ttyS0 and ttyS1 are supported.
621 Interaction with the standard serial driver is not
624 The VGA output is eventually overwritten by the real
630 Format: {"of[f]" | "sk[ipmbr]"}
631 See comment in arch/i386/boot/edd.S
633 eisa_irq_edge= [PARISC,HW]
634 See header of drivers/parisc/eisa.c.
637 See comment before function elanfreq_setup() in
638 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
641 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
642 See Documentation/block/as-iosched.txt and
643 Documentation/block/deadline-iosched.txt for details.
645 elfcorehdr= [X86-32, X86_64]
646 Specifies physical address of start of kernel core
647 image elf header. Generally kexec loader will
648 pass this option to capture kernel.
649 See Documentation/kdump/kdump.txt for details.
651 enforcing [SELINUX] Set initial enforcing status.
653 See security/selinux/Kconfig help text.
654 0 -- permissive (log only, no denials).
655 1 -- enforcing (deny and log).
657 Value can be changed at runtime via /selinux/enforce.
660 Format: <spdif>,[<nomix>,[<amplifier>]]
661 See also header of sound/oss/es1371.c.
663 ether= [HW,NET] Ethernet cards parameters
664 This option is obsoleted by the "netdev=" option, which
665 has equivalent usage. See its documentation for details.
667 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
672 fail_make_request=[KNL]
673 General fault injection mechanism.
674 Format: <interval>,<probability>,<space>,<times>
675 See also /Documentation/fault-injection/.
678 See header of drivers/scsi/fd_mcs.c.
681 See header of drivers/scsi/fdomain.c.
684 See Documentation/floppy.txt.
687 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
688 support via parallel port (up to 5 devices per port)
689 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
690 See also Documentation/input/joystick-parport.txt
694 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
699 See header of drivers/scsi/gdth.c.
701 gpt [EFI] Forces disk with valid GPT signature but
702 invalid Protective MBR to be treated as GPT.
706 hashdist= [KNL,NUMA] Large hashes allocated during boot
707 are distributed across NUMA nodes. Defaults on
708 for IA-64, off otherwise.
709 Format: 0 | 1 (for off | on)
711 hcl= [IA-64] SGI's Hardware Graph compatibility layer
713 hd= [EIDE] (E)IDE hard drive subsystem geometry
714 Format: <cyl>,<head>,<sect>
716 hd?= [HW] (E)IDE subsystem
717 hd?lun= See Documentation/ide/ide.txt.
719 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
720 size of <nn>. This works even on boxes that have no
721 highmem otherwise. This also works to reduce highmem
722 size on bigger boxes.
724 highres= [KNL] Enable/disable high resolution timer mode.
725 Valid parameters: "on", "off"
729 See Documentation/isdn/README.HiSax.
731 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
732 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
734 i8042.direct [HW] Put keyboard port into non-translated mode
735 i8042.dumbkbd [HW] Pretend that controller can only read data from
736 keyboard and cannot control its state
737 (Don't attempt to blink the leds)
738 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
739 i8042.nokbd [HW] Don't check/create keyboard port
740 i8042.noloop [HW] Disable the AUX Loopback command while probing
742 i8042.nomux [HW] Don't check presence of an active multiplexing
744 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
747 [HW] Frequency with which keyboard LEDs should blink
748 when kernel panics (default is 0.5 sec)
749 i8042.reset [HW] Reset the controller during init and cleanup
750 i8042.unlock [HW] Unlock (ignore) the keylock
754 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
755 indicates that the driver is running on unsupported
757 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
758 does not match list of supported models.
760 [HW] Report power status in /proc/i8k
761 (disabled by default)
762 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
765 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
766 See Documentation/mca.txt.
769 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
771 ide= [HW] (E)IDE subsystem
772 Format: ide=nodma or ide=doubler
773 See Documentation/ide/ide.txt.
775 ide?= [HW] (E)IDE subsystem
776 Format: ide?=ata66 or chipset specific parameters.
777 See Documentation/ide/ide.txt.
779 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
780 See Documentation/ide/ide.txt.
783 Format: idle=poll or idle=mwait
784 Poll forces a polling idle loop that can slightly improves the performance
785 of waking up a idle CPU, but will use a lot of power and make the system
786 run hot. Not recommended.
787 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
788 to not use it because it doesn't save as much power as a normal idle
789 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
792 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
793 Claim all unknown PCI IDE storage controllers.
795 ignore_loglevel [KNL]
796 Ignore loglevel setting - this will print /all/
797 kernel messages to the console. Useful for debugging.
800 Set number of hash buckets for inode cache.
803 See header of drivers/scsi/in2000.c.
807 Run specified binary instead of /sbin/init as init
810 initcall_debug [KNL] Trace initcalls as they are executed. Useful
811 for working out where the kernel is dying during
814 initrd= [BOOT] Specify the location of the initial ramdisk
816 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
834 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
836 Disable intel iommu driver.
837 igfx_off [Default Off]
838 By default, gfx is mapped as normal device. If a gfx
839 device has a dedicated DMAR unit, the DMAR unit is
840 bypassed by not enabling DMAR with this option. In
841 this case, gfx device will use physical address for
844 With this option iommu will not optimize to look
845 for io virtual address below 32 bit forcing dual
846 address cycle on pci bus for cards supporting greater
847 than 32 bit addressing. The default is to look
848 for translation below 32 bit and if not available
849 then look in the higher range.
851 io_delay= [X86-32,X86-64] I/O delay method
853 Standard port 0x80 based delay
855 Alternate port 0xed based delay (needed on some systems)
857 Simple two microseconds delay
861 io7= [HW] IO7 for Marvel based alpha systems
862 See comment before marvel_specify_io7 in
863 arch/alpha/kernel/core_marvel.c.
866 See Documentation/filesystems/nfsroot.txt.
868 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
869 See comment before ip2_setup() in
870 drivers/char/ip2/ip2base.c.
872 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
873 See header of drivers/scsi/ips.c.
875 ports= [IP_VS_FTP] IPVS ftp helper module
877 Up to 8 (IP_VS_APP_MAX_PORTS) ports
879 Format: <port>,<port>....
882 When an interrupt is not handled search all handlers
883 for it. Intended to get systems with badly broken
887 When an interrupt is not handled search all handlers
888 for it. Also check all handlers each timer
889 interrupt. Intended to get systems with badly broken
893 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
895 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
897 <cpu number>,...,<cpu number>
899 <cpu number>-<cpu number> (must be a positive range in ascending order)
901 <cpu number>,...,<cpu number>-<cpu number>
902 This option can be used to specify one or more CPUs
903 to isolate from the general SMP balancing and scheduling
904 algorithms. The only way to move a process onto or off
905 an "isolated" CPU is via the CPU affinity syscalls.
906 <cpu number> begins at 0 and the maximum value is
907 "number of CPUs in system - 1".
909 This option is the preferred way to isolate CPUs. The
910 alternative -- manually setting the CPU mask of all
911 tasks in the system -- can cause problems and
912 suboptimal load balancer performance.
916 js= [HW,JOY] Analog joystick
917 See Documentation/input/joystick.txt.
919 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
920 specifies the amount of memory usable by the kernel
921 for non-movable allocations. The requested amount is
922 spread evenly throughout all nodes in the system. The
923 remaining memory in each node is used for Movable
924 pages. In the event, a node is too small to have both
925 kernelcore and Movable pages, kernelcore pages will
926 take priority and other nodes will have a larger number
927 of kernelcore pages. The Movable zone is used for the
928 allocation of pages that may be reclaimed or moved
929 by the page migration subsystem. This means that
930 HugeTLB pages may not be allocated from this zone.
931 Note that allocations like PTEs-from-HighMem still
932 use the HighMem zone if it exists, and the Normal
935 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
936 is similar to kernelcore except it specifies the
937 amount of memory used for migratable allocations.
938 If both kernelcore and movablecore is specified,
939 then kernelcore will be at *least* the specified
940 value but may be more. If movablecore on its own
941 is specified, the administrator must be careful
942 that the amount of memory usable for all allocations
947 kstack=N [X86-32,X86-64] Print N words from the kernel stack
950 kgdboc= [HW] kgdb over consoles.
951 Requires a tty driver that supports console polling.
952 (only serial suported for now)
953 Format: <serial_device>[,baud]
957 lapic [X86-32,APIC] Enable the local APIC even if BIOS
960 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
963 libata.dma= [LIBATA] DMA control
964 libata.dma=0 Disable all PATA and SATA DMA
965 libata.dma=1 PATA and SATA Disk DMA only
966 libata.dma=2 ATAPI (CDROM) DMA only
967 libata.dma=4 Compact Flash DMA only
968 Combinations also work, so libata.dma=3 enables DMA
969 for disks and CDROMs, but not CFs.
971 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
975 libata.force= [LIBATA] Force configurations. The format is comma
976 separated list of "[ID:]VAL" where ID is
977 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
978 matching port, link or device. Basically, it matches
979 the ATA ID string printed on console by libata. If
980 the whole ID part is omitted, the last PORT and DEVICE
981 values are used. If ID hasn't been specified yet, the
982 configuration applies to all ports, links and devices.
984 If only DEVICE is omitted, the parameter applies to
985 the port and all links and devices behind it. DEVICE
986 number of 0 either selects the first device or the
987 first fan-out link behind PMP device. It does not
988 select the host link. DEVICE number of 15 selects the
989 host link and device attached to it.
991 The VAL specifies the configuration to force. As long
992 as there's no ambiguity shortcut notation is allowed.
993 For example, both 1.5 and 1.5G would work for 1.5Gbps.
994 The following configurations can be forced.
996 * Cable type: 40c, 80c, short40c, unk, ign or sata.
997 Any ID with matching PORT is used.
999 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1001 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1002 udma[/][16,25,33,44,66,100,133] notation is also
1005 * [no]ncq: Turn on or off NCQ.
1007 If there are multiple matching configurations changing
1008 the same attribute, the last one is used.
1010 load_ramdisk= [RAM] List of ramdisks to load from floppy
1011 See Documentation/ramdisk.txt.
1013 lockd.nlm_grace_period=P [NFS] Assign grace period.
1016 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1019 lockd.nlm_timeout=T [NFS] Assign timeout value.
1022 lockd.nlm_udpport=M [NFS] Assign UDP port.
1025 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1028 loglevel= All Kernel Messages with a loglevel smaller than the
1029 console loglevel will be printed to the console. It can
1030 also be changed with klogd or other programs. The
1031 loglevels are defined as follows:
1033 0 (KERN_EMERG) system is unusable
1034 1 (KERN_ALERT) action must be taken immediately
1035 2 (KERN_CRIT) critical conditions
1036 3 (KERN_ERR) error conditions
1037 4 (KERN_WARNING) warning conditions
1038 5 (KERN_NOTICE) normal but significant condition
1039 6 (KERN_INFO) informational
1040 7 (KERN_DEBUG) debug-level messages
1042 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1043 Format: { n | nk | nM }
1044 n must be a power of two. The default size
1045 is set in the kernel config file.
1047 logo.nologo [FB] Disables display of the built-in Linux logo.
1048 This may be used to provide more screen space for
1049 kernel log messages and is useful when debugging
1050 kernel boot problems.
1052 lp=0 [LP] Specify parallel ports to use, e.g,
1053 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1054 lp=reset first parallel port). 'lp=0' disables the
1055 lp=auto printer driver. 'lp=reset' (which can be
1056 specified in addition to the ports) causes
1057 attached printers to be reset. Using
1058 lp=port1,port2,... specifies the parallel ports
1059 to associate lp devices with, starting with
1060 lp0. A port specification may be 'none' to skip
1061 that lp device, or a parport name such as
1062 'parport0'. Specifying 'lp=auto' instead of a
1063 port specification list means that device IDs
1064 from each port should be examined, to see if
1065 an IEEE 1284-compliant printer is attached; if
1066 so, the driver will manage that printer.
1067 See also header of drivers/char/lp.c.
1070 Sets loops_per_jiffy to given constant, thus avoiding
1071 time-consuming boot-time autodetection (up to 250 ms per
1072 CPU). 0 enables autodetection (default). To determine
1073 the correct value for your kernel, boot with normal
1074 autodetection and see what value is printed. Note that
1075 on SMP systems the preset will be applied to all CPUs,
1076 which is likely to cause problems if your CPUs need
1077 significantly divergent settings. An incorrect value
1078 will cause delays in the kernel to be wrong, leading to
1079 unpredictable I/O errors and other breakage. Although
1080 unlikely, in the extreme case this might damage your
1084 Format: <io>,<irq>,<dma>
1086 mac5380= [HW,SCSI] Format:
1087 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1089 mac53c9x= [HW,SCSI] Format:
1090 <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1092 machvec= [IA64] Force the use of a particular machine-vector
1093 (machvec) in a generic kernel.
1094 Example: machvec=hpzx1_swiotlb
1096 max_loop= [LOOP] Maximum number of loopback devices that can
1100 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1101 should make use of. maxcpus=n : n >= 0 limits the
1102 kernel to using 'n' processors. n=0 is a special case,
1103 it is equivalent to "nosmp", which also disables
1106 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1107 equal to this physical address is ignored.
1109 max_luns= [SCSI] Maximum number of LUNs to probe.
1110 Should be between 1 and 2^32-1.
1113 [SCSI] Maximum number of LUNs received.
1114 Should be between 1 and 16384.
1118 mce [X86-32] Machine Check Exception
1120 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1122 md= [HW] RAID subsystems devices and level
1123 See Documentation/md.txt.
1126 Format: <first>,<last>
1127 Specifies range of consoles to be captured by the MDA.
1129 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1130 Amount of memory to be used when the kernel is not able
1131 to see the whole system memory or for test.
1132 [X86-32] Use together with memmap= to avoid physical
1133 address space collisions. Without memmap= PCI devices
1134 could be placed at addresses belonging to unused RAM.
1136 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1139 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1140 E820 memory map, as specified by the user.
1141 Such memmap=exactmap lines can be constructed based on
1142 BIOS output or other requirements. See the memmap=nn@ss
1145 memmap=nn[KMG]@ss[KMG]
1146 [KNL] Force usage of a specific region of memory
1147 Region of memory to be used, from ss to ss+nn.
1149 memmap=nn[KMG]#ss[KMG]
1150 [KNL,ACPI] Mark specific memory as ACPI data.
1151 Region of memory to be used, from ss to ss+nn.
1153 memmap=nn[KMG]$ss[KMG]
1154 [KNL,ACPI] Mark specific memory as reserved.
1155 Region of memory to be used, from ss to ss+nn.
1156 Example: Exclude memory from 0x18690000-0x1869ffff
1157 memmap=64K$0x18690000
1159 memmap=0x10000$0x18690000
1161 memtest= [KNL,X86_64] Enable memtest
1163 range: 0,4 : pattern number
1164 default : 0 <disable>
1166 meye.*= [HW] Set MotionEye Camera parameters
1167 See Documentation/video4linux/meye.txt.
1169 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1170 Multi-Function General Purpose Timers on AMD Geode
1173 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1174 the BIOS has incorrectly applied a workaround. TinyBIOS
1175 version 0.98 is known to be affected, 0.99 fixes the
1176 problem by letting the user disable the workaround.
1181 [MOUSE] Maximum time between finger touching and
1182 leaving touchpad surface for touch to be considered
1183 a tap and be reported as a left button click (for
1184 touchpads working in absolute mode only).
1186 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1187 reporting absolute coordinates, such as tablets
1188 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1189 reporting absolute coordinates, such as tablets
1194 MTD_Partition= [MTD]
1195 Format: <name>,<region-number>,<size>,<offset>
1197 MTD_Region= [MTD] Format:
1198 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1201 See drivers/mtd/cmdlinepart.c.
1203 mtouchusb.raw_coordinates=
1204 [HW] Make the MicroTouch USB driver use raw coordinates
1205 ('y', default) or cooked coordinates ('n')
1207 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1210 See header of drivers/scsi/NCR_D700.c.
1214 ncr53c400= [HW,SCSI]
1216 ncr53c400a= [HW,SCSI]
1218 ncr53c406a= [HW,SCSI]
1220 ncr53c8xx= [HW,SCSI]
1222 netdev= [NET] Network devices parameters
1223 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1224 Note that mem_start is often overloaded to mean
1225 something different and driver-specific.
1226 This usage is only documented in each driver source
1230 See Documentation/filesystems/nfsroot.txt.
1232 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1233 See Documentation/filesystems/nfsroot.txt.
1235 nfs.callback_tcpport=
1236 [NFS] set the TCP port on which the NFSv4 callback
1237 channel should listen.
1239 nfs.idmap_cache_timeout=
1240 [NFS] set the maximum lifetime for idmapper cache
1244 [NFS] enable 64-bit inode numbers.
1245 If zero, the NFS client will fake up a 32-bit inode
1246 number for the readdir() and stat() syscalls instead
1247 of returning the full 64-bit number.
1248 The default is to return 64-bit inode numbers.
1250 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1251 when a NMI is triggered.
1252 Format: [state][,regs][,debounce][,die]
1254 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1256 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1257 emulation library even if a 387 maths coprocessor
1260 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1261 caches in the slab allocator. Saves per-node memory,
1262 but will impact performance.
1266 noapic [SMP,APIC] Tells the kernel to not make use of any
1267 IOAPICs that may be present in the system.
1269 nobats [PPC] Do not use BATs for mapping kernel lowmem
1270 on "Classic" PPC cores.
1274 nodelayacct [KNL] Disable per-task delay accounting
1276 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1278 noefi [X86-32,X86-64] Disable EFI runtime services support.
1282 noexec [X86-32,X86-64]
1283 On X86-32 available only on PAE configured kernels.
1284 noexec=on: enable non-executable mappings (default)
1285 noexec=off: disable non-executable mappings
1288 This affects only 32-bit executables.
1289 noexec32=on: enable non-executable mappings (default)
1290 read doesn't imply executable mappings
1291 noexec32=off: disable non-executable mappings
1292 read implies executable mappings
1294 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1295 register save and restore. The kernel will only save
1296 legacy floating-point registers on task switch.
1298 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1302 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1303 instruction doesn't work correctly and not to
1306 nohalt [IA-64] Tells the kernel not to use the power saving
1307 function PAL_HALT_LIGHT when idle. This increases
1308 power-consumption. On the positive side, it reduces
1309 interrupt wake-up latency, which may improve performance
1310 in certain environments such as networked servers or
1313 nohz= [KNL] Boottime enable/disable dynamic ticks
1314 Valid arguments: on, off
1317 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1319 noirqdebug [X86-32] Disables the code which attempts to detect and
1320 disable unhandled interrupt sources.
1322 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1323 broken timer IRQ sources.
1325 noisapnp [ISAPNP] Disables ISA PnP code.
1327 noinitrd [RAM] Tells the kernel not to load any configured
1332 nojitter [IA64] Disables jitter checking for ITC timers.
1334 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1336 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1338 noltlbs [PPC] Do not use large page/tlb entries for kernel
1339 lowmem mapping on PPC40x.
1341 nomca [IA-64] Disable machine check abort handling
1343 nomce [X86-32] Machine Check Exception
1345 nomfgpt [X86-32] Disable Multi-Function General Purpose
1346 Timer usage (for AMD Geode machines).
1348 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1350 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1351 with UP alternatives
1353 noresidual [PPC] Don't use residual data on PReP machines.
1355 noresume [SWSUSP] Disables resume and restores original swap
1358 no-scroll [VGA] Disables scrollback.
1359 This is required for the Braillex ib80-piezo Braille
1360 reader made by F.H. Papenmeier (Germany).
1364 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1366 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1367 and disable the IO APIC. legacy for "maxcpus=0".
1369 nosoftlockup [KNL] Disable the soft-lockup detector.
1371 nosync [HW,M68K] Disables sync negotiation for all devices.
1373 notsc [BUGS=X86-32] Disable Time Stamp Counter
1375 nousb [USB] Disable the USB subsystem
1379 nptcg= [IA64] Override max number of concurrent global TLB
1380 purges which is reported from either PAL_VM_SUMMARY or
1383 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1384 one of ['zone', 'node', 'default'] can be specified
1385 This can be set from sysctl after boot.
1386 See Documentation/sysctl/vm.txt for details.
1388 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1393 oprofile.timer= [HW]
1394 Use timer interrupt instead of performance counters
1396 osst= [HW,SCSI] SCSI Tape Driver
1397 Format: <buffer_size>,<write_threshold>
1398 See also Documentation/scsi/st.txt.
1400 panic= [KNL] Kernel behaviour on panic
1403 parkbd.port= [HW] Parallel port number the keyboard adapter is
1404 connected to, default is 0.
1406 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1407 0 for XT, 1 for AT (default is AT).
1410 parport= [HW,PPT] Specify parallel ports. 0 disables.
1411 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1412 Use 'auto' to force the driver to use any
1413 IRQ/DMA settings detected (the default is to
1414 ignore detected IRQ/DMA settings because of
1415 possible conflicts). You can specify the base
1416 address, IRQ, and DMA settings; IRQ and DMA
1417 should be numbers, or 'auto' (for using detected
1418 settings on that particular port), or 'nofifo'
1419 (to avoid using a FIFO even if it is detected).
1420 Parallel ports are assigned in the order they
1421 are specified on the command line, starting
1424 parport_init_mode= [HW,PPT]
1425 Configure VIA parallel port to operate in
1426 a specific mode. This is necessary on Pegasos
1427 computer where firmware has no options for setting
1428 up parallel port mode and sets it to spp.
1429 Currently this function knows 686a and 8231 chips.
1430 Format: [spp|ps2|epp|ecp|ecpepp]
1432 pas2= [HW,OSS] Format:
1433 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1436 See header of drivers/scsi/pas16.c.
1439 Halt all CPUs after the first oops has been printed for
1440 the specified number of seconds. This is to be used if
1441 your oopses keep scrolling off the screen.
1446 See header of drivers/block/paride/pcd.c.
1447 See also Documentation/paride.txt.
1449 pci=option[,option...] [PCI] various PCI subsystem options:
1450 off [X86-32] don't probe for the PCI bus
1451 bios [X86-32] force use of PCI BIOS, don't access
1452 the hardware directly. Use this if your machine
1453 has a non-standard PCI host bridge.
1454 nobios [X86-32] disallow use of PCI BIOS, only direct
1455 hardware access methods are allowed. Use this
1456 if you experience crashes upon bootup and you
1457 suspect they are caused by the BIOS.
1458 conf1 [X86-32] Force use of PCI Configuration
1460 conf2 [X86-32] Force use of PCI Configuration
1462 noaer [PCIE] If the PCIEAER kernel config parameter is
1463 enabled, this kernel boot option can be used to
1464 disable the use of PCIE advanced error reporting.
1465 nodomains [PCI] Disable support for multiple PCI
1466 root domains (aka PCI segments, in ACPI-speak).
1467 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1469 nomsi [MSI] If the PCI_MSI kernel config parameter is
1470 enabled, this kernel boot option can be used to
1471 disable the use of MSI interrupts system-wide.
1472 nosort [X86-32] Don't sort PCI devices according to
1473 order given by the PCI BIOS. This sorting is
1474 done to get a device order compatible with
1476 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1477 routing table. These calls are known to be buggy
1478 on several machines and they hang the machine
1479 when used, but on other computers it's the only
1480 way to get the interrupt routing table. Try
1481 this option if the kernel is unable to allocate
1482 IRQs or discover secondary PCI buses on your
1484 rom [X86-32] Assign address space to expansion ROMs.
1485 Use with caution as certain devices share
1486 address decoders between ROMs and other
1488 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1489 assigned automatically to PCI devices. You can
1490 make the kernel exclude IRQs of your ISA cards
1492 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1493 of the PIRQ table (normally generated
1494 by the BIOS) if it is outside the
1495 F0000h-100000h range.
1496 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1497 useful if the kernel is unable to find your
1498 secondary buses and you want to tell it
1499 explicitly which ones they are.
1500 assign-busses [X86-32] Always assign all PCI bus
1501 numbers ourselves, overriding
1502 whatever the firmware may have done.
1503 usepirqmask [X86-32] Honor the possible IRQ mask stored
1504 in the BIOS $PIR table. This is needed on
1505 some systems with broken BIOSes, notably
1506 some HP Pavilion N5400 and Omnibook XE3
1507 notebooks. This will have no effect if ACPI
1508 IRQ routing is enabled.
1509 noacpi [X86-32] Do not use ACPI for IRQ routing
1510 or for PCI scanning.
1511 use_crs [X86-32] Use _CRS for PCI resource
1513 routeirq Do IRQ routing for all PCI devices.
1514 This is normally done in pci_enable_device(),
1515 so this option is a temporary workaround
1516 for broken drivers that don't call it.
1517 firmware [ARM] Do not re-enumerate the bus but instead
1518 just use the configuration from the
1519 bootloader. This is currently used on
1520 IXP2000 systems where the bus has to be
1521 configured a certain way for adjunct CPUs.
1522 noearly [X86] Don't do any early type 1 scanning.
1523 This might help on some broken boards which
1524 machine check when some devices' config space
1525 is read. But various workarounds are disabled
1526 and some IOMMU drivers will not work.
1527 bfsort Sort PCI devices into breadth-first order.
1528 This sorting is done to get a device
1529 order compatible with older (<= 2.4) kernels.
1530 nobfsort Don't sort PCI devices into breadth-first order.
1531 cbiosize=nn[KMG] The fixed amount of bus space which is
1532 reserved for the CardBus bridge's IO window.
1533 The default value is 256 bytes.
1534 cbmemsize=nn[KMG] The fixed amount of bus space which is
1535 reserved for the CardBus bridge's memory
1536 window. The default value is 64 megabytes.
1538 pcmv= [HW,PCMCIA] BadgePAD 4
1541 See Documentation/paride.txt.
1543 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1546 See arch/parisc/kernel/pdc_chassis.c
1549 See Documentation/paride.txt.
1552 See Documentation/paride.txt.
1554 pirq= [SMP,APIC] Manual mp-table setup
1555 See Documentation/i386/IO-APIC.txt.
1557 plip= [PPT,NET] Parallel port network link
1558 Format: { parport<nr> | timid | 0 }
1559 See also Documentation/parport.txt.
1565 { on | off | curr | res | no-curr | no-res }
1568 [ISAPNP] Exclude IRQs for the autoconfiguration
1571 [ISAPNP] Exclude DMAs for the autoconfiguration
1573 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1574 Ranges are in pairs (I/O port base and size).
1577 [ISAPNP] Exclude memory regions for the
1579 Ranges are in pairs (memory base and size).
1581 print-fatal-signals=
1582 [KNL] debug: print fatal signals
1583 print-fatal-signals=1: print segfault info to
1587 printk.time= Show timing data prefixed to each printk message line
1588 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1590 profile= [KNL] Enable kernel profiling via /proc/profile
1591 Format: [schedule,]<number>
1592 Param: "schedule" - profile schedule points.
1593 Param: <number> - step/bucket size as a power of 2 for
1594 statistical time based profiling.
1595 Param: "sleep" - profile D-state sleeping (millisecs).
1596 Requires CONFIG_SCHEDSTATS
1597 Param: "kvm" - profile VM exits.
1599 processor.max_cstate= [HW,ACPI]
1600 Limit processor to maximum C-state
1601 max_cstate=9 overrides any DMI blacklist limit.
1603 processor.nocst [HW,ACPI]
1604 Ignore the _CST method to determine C-states,
1605 instead using the legacy FADT method
1607 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1609 See Documentation/ramdisk.txt.
1611 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1612 probe for; one of (bare|imps|exps|lifebook|any).
1613 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1615 psmouse.resetafter= [HW,MOUSE]
1616 Try to reset the device after so many bad packets
1619 [HW,MOUSE] Set desired mouse resolution, in dpi.
1620 psmouse.smartscroll=
1621 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1622 0 = disabled, 1 = enabled (default).
1624 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1626 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1629 See Documentation/paride.txt.
1632 [KNL] Number of legacy pty's. Overwrites compiled-in
1635 quiet [KNL] Disable most log messages
1640 See Documentation/md.txt.
1642 ramdisk_blocksize= [RAM]
1643 See Documentation/ramdisk.txt.
1645 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1646 See Documentation/ramdisk.txt.
1648 rcupdate.blimit= [KNL,BOOT]
1649 Set maximum number of finished RCU callbacks to process
1652 rcupdate.qhimark= [KNL,BOOT]
1653 Set threshold of queued
1654 RCU callbacks over which batch limiting is disabled.
1656 rcupdate.qlowmark= [KNL,BOOT]
1657 Set threshold of queued RCU callbacks below which
1658 batch limiting is re-enabled.
1662 Run specified binary instead of /init from the ramdisk,
1663 used for early userspace startup. See initrd.
1665 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1666 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1667 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1669 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1671 reservetop= [X86-32]
1673 Reserves a hole at the top of the kernel virtual
1676 reset_devices [KNL] Force drivers to reset the underlying device
1677 during initialization.
1680 Specify the partition device for software suspend
1682 resume_offset= [SWSUSP]
1683 Specify the offset from the beginning of the partition
1684 given by "resume=" at which the swap header is located,
1685 in <PAGE_SIZE> units (needed only for swap files).
1686 See Documentation/power/swsusp-and-swap-files.txt
1688 retain_initrd [RAM] Keep initrd memory after extraction
1690 rhash_entries= [KNL,NET]
1691 Set number of hash buckets for route cache
1693 riscom8= [HW,SERIAL]
1694 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1696 ro [KNL] Mount root device read-only on boot
1698 root= [KNL] Root filesystem
1700 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1701 mount the root filesystem
1703 rootflags= [KNL] Set root filesystem mount option string
1705 rootfstype= [KNL] Set root filesystem type
1707 rootwait [KNL] Wait (indefinitely) for root device to show up.
1708 Useful for devices that are detected asynchronously
1709 (e.g. USB and MMC devices).
1711 root_plug.vendor_id=
1712 [ROOTPLUG] Override the default vendor ID
1714 root_plug.product_id=
1715 [ROOTPLUG] Override the default product ID
1718 [ROOTPLUG] Enable debugging output
1720 rw [KNL] Mount root device read-write on boot
1722 S [KNL] Run init in single mode
1725 See drivers/net/irda/sa1100_ir.c.
1727 sbni= [NET] Granch SBNI12 leased line adapter
1729 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1730 Format: <io>[,<timeout>[,<isapnp>]]
1732 scsi_debug_*= [SCSI]
1733 See drivers/scsi/scsi_debug.c.
1735 scsi_default_dev_flags=
1736 [SCSI] SCSI default device flags
1739 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1740 Format: <vendor>:<model>:<flags>
1741 (flags are integer value)
1743 scsi_logging_level= [SCSI] a bit mask of logging levels
1744 See drivers/scsi/scsi_logging.h for bits. Also
1745 settable via sysctl at dev.scsi.logging_level
1746 (/proc/sys/dev/scsi/logging_level).
1747 There is also a nice 'scsi_logging_level' script in the
1748 S390-tools package, available for download at
1749 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1751 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1752 discovered. async scans them in kernel threads,
1753 allowing boot to proceed. none ignores them, expecting
1754 user space to do the scan.
1756 selinux [SELINUX] Disable or enable SELinux at boot time.
1757 Format: { "0" | "1" }
1758 See security/selinux/Kconfig help text.
1761 Default value is set via kernel config option.
1762 If enabled at boot time, /selinux/disable can be used
1763 later to disable prior to initial policy load.
1765 selinux_compat_net =
1766 [SELINUX] Set initial selinux_compat_net flag value.
1767 Format: { "0" | "1" }
1768 0 -- use new secmark-based packet controls
1769 1 -- use legacy packet controls
1770 Default value is 0 (preferred).
1771 Value can be changed at runtime via
1772 /selinux/compat_net.
1774 serialnumber [BUGS=X86-32]
1777 Maximal number of shapers.
1780 See header of drivers/scsi/sim710.c.
1787 slub_debug[=options[,slabs]] [MM, SLUB]
1788 Enabling slub_debug allows one to determine the
1789 culprit if slab objects become corrupted. Enabling
1790 slub_debug can create guard zones around objects and
1791 may poison objects when not in use. Also tracks the
1792 last alloc / free. For more information see
1793 Documentation/vm/slub.txt.
1795 slub_max_order= [MM, SLUB]
1796 Determines the maximum allowed order for slabs.
1797 A high setting may cause OOMs due to memory
1798 fragmentation. For more information see
1799 Documentation/vm/slub.txt.
1801 slub_min_objects= [MM, SLUB]
1802 The minimum number of objects per slab. SLUB will
1803 increase the slab order up to slub_max_order to
1804 generate a sufficiently large slab able to contain
1805 the number of objects indicated. The higher the number
1806 of objects the smaller the overhead of tracking slabs
1807 and the less frequently locks need to be acquired.
1808 For more information see Documentation/vm/slub.txt.
1810 slub_min_order= [MM, SLUB]
1811 Determines the mininum page order for slabs. Must be
1812 lower than slub_max_order.
1813 For more information see Documentation/vm/slub.txt.
1815 slub_nomerge [MM, SLUB]
1816 Disable merging of slabs with similar size. May be
1817 necessary if there is some reason to distinguish
1818 allocs to different slabs. Debug options disable
1819 merging on their own.
1820 For more information see Documentation/vm/slub.txt.
1823 Format: <io1>[,<io2>[,...,<io8>]]
1825 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1826 attempt to substitute SMP alternatives once at boot.
1828 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1829 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1830 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1831 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1832 smsc-ircc2.ircc_irq= [HW] IRQ line
1833 smsc-ircc2.ircc_dma= [HW] DMA channel
1834 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1835 0: Toshiba Satellite 1800 (GP data pin select)
1836 1: Fast pin select (default)
1839 snd-ad1816a= [HW,ALSA]
1841 snd-ad1848= [HW,ALSA]
1843 snd-ali5451= [HW,ALSA]
1845 snd-als100= [HW,ALSA]
1847 snd-als4000= [HW,ALSA]
1849 snd-azt2320= [HW,ALSA]
1851 snd-cmi8330= [HW,ALSA]
1853 snd-cmipci= [HW,ALSA]
1855 snd-cs4231= [HW,ALSA]
1857 snd-cs4232= [HW,ALSA]
1859 snd-cs4236= [HW,ALSA]
1861 snd-cs4281= [HW,ALSA]
1863 snd-cs46xx= [HW,ALSA]
1865 snd-dt019x= [HW,ALSA]
1867 snd-dummy= [HW,ALSA]
1869 snd-emu10k1= [HW,ALSA]
1871 snd-ens1370= [HW,ALSA]
1873 snd-ens1371= [HW,ALSA]
1875 snd-es968= [HW,ALSA]
1877 snd-es1688= [HW,ALSA]
1879 snd-es18xx= [HW,ALSA]
1881 snd-es1938= [HW,ALSA]
1883 snd-es1968= [HW,ALSA]
1885 snd-fm801= [HW,ALSA]
1887 snd-gusclassic= [HW,ALSA]
1889 snd-gusextreme= [HW,ALSA]
1891 snd-gusmax= [HW,ALSA]
1895 snd-ice1712= [HW,ALSA]
1897 snd-intel8x0= [HW,ALSA]
1899 snd-interwave= [HW,ALSA]
1904 snd-korg1212= [HW,ALSA]
1906 snd-maestro3= [HW,ALSA]
1908 snd-mpu401= [HW,ALSA]
1910 snd-mtpav= [HW,ALSA]
1912 snd-nm256= [HW,ALSA]
1914 snd-opl3sa2= [HW,ALSA]
1922 snd-opti93x= [HW,ALSA]
1926 snd-rme32= [HW,ALSA]
1928 snd-rme96= [HW,ALSA]
1930 snd-rme9652= [HW,ALSA]
1936 snd-sbawe= [HW,ALSA]
1938 snd-serial= [HW,ALSA]
1940 snd-sgalaxy= [HW,ALSA]
1942 snd-sonicvibes= [HW,ALSA]
1947 snd-sun-cs4231= [HW,ALSA]
1949 snd-trident= [HW,ALSA]
1951 snd-usb-audio= [HW,ALSA,USB]
1953 snd-via82xx= [HW,ALSA]
1955 snd-virmidi= [HW,ALSA]
1957 snd-wavefront= [HW,ALSA]
1959 snd-ymfpci= [HW,ALSA]
1961 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1962 See Documentation/sonypi.txt
1964 specialix= [HW,SERIAL] Specialix multi-serial port adapter
1965 See Documentation/specialix.txt.
1967 spia_io_base= [HW,MTD]
1973 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
1975 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
1976 See Documentation/scsi/st.txt.
1980 Set the STI (builtin display/keyboard on the HP-PARISC
1981 machines) console (graphic card) which should be used
1982 as the initial boot-console.
1983 See also comment in drivers/video/console/sticore.c.
1986 See comment in drivers/video/console/sticore.c.
1989 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
1993 Control how the NFS server code allocates CPUs to
1994 service thread pools. Depending on how many NICs
1995 you have and where their interrupts are bound, this
1996 option will affect which CPUs will do NFS serving.
1997 Note: this parameter cannot be changed while the
1998 NFS server is running.
2000 auto the server chooses an appropriate mode
2001 automatically using heuristics
2002 global a single global pool contains all CPUs
2003 percpu one pool for each CPU
2004 pernode one pool for each NUMA node (equivalent
2005 to global on non-NUMA machines)
2007 swiotlb= [IA-64] Number of I/O TLB slabs
2011 sym53c416= [HW,SCSI]
2012 See header of drivers/scsi/sym53c416.c.
2014 sysrq_always_enabled
2016 Ignore sysrq setting - this boot parameter will
2017 neutralize any effect of /proc/sys/kernel/sysrq.
2018 Useful for debugging.
2021 See header of drivers/scsi/t128.c.
2025 thash_entries= [KNL,NET]
2026 Set number of hash buckets for TCP connection
2028 thermal.act= [HW,ACPI]
2029 -1: disable all active trip points in all thermal zones
2030 <degrees C>: override all lowest active trip points
2032 thermal.crt= [HW,ACPI]
2033 -1: disable all critical trip points in all thermal zones
2034 <degrees C>: lower all critical trip points
2036 thermal.nocrt= [HW,ACPI]
2037 Set to disable actions on ACPI thermal zone
2038 critical and hot trip points.
2040 thermal.off= [HW,ACPI]
2041 1: disable ACPI thermal control
2043 thermal.psv= [HW,ACPI]
2044 -1: disable all passive trip points
2045 <degrees C>: override all passive trip points to this value
2047 thermal.tzp= [HW,ACPI]
2048 Specify global default ACPI thermal zone polling rate
2049 <deci-seconds>: poll all this frequency
2050 0: no polling (default)
2052 tipar.timeout= [HW,PPT]
2053 Set communications timeout in tenths of a second
2056 tipar.delay= [HW,PPT]
2057 Set inter-bit delay in microseconds (default 10).
2060 See comment before function dc390_setup() in
2061 drivers/scsi/tmscsim.c.
2065 trix= [HW,OSS] MediaTrix AudioTrix Pro
2067 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2069 turbografx.map[2|3]= [HW,JOY]
2070 TurboGraFX parallel port interface
2072 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2073 See also Documentation/input/joystick-parport.txt
2075 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2076 See header of drivers/scsi/u14-34f.c.
2085 [USB] Ignore overcurrent events (default N).
2086 Some badly-designed motherboards generate lots of
2087 bogus events, for ports that aren't wired to
2088 anything. Set this parameter to avoid log spamming.
2089 Note that genuine overcurrent events won't be
2092 usbcore.autosuspend=
2093 [USB] The autosuspend time delay (in seconds) used
2094 for newly-detected USB devices (default 2). This
2095 is the time required before an idle device will be
2096 autosuspended. Devices for which the delay is set
2097 to a negative value won't be autosuspended at all.
2100 [USBHID] The interval which mice are to be polled at.
2102 vdso= [X86-32,SH,x86-64]
2103 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2104 vdso=1: enable VDSO (default)
2105 vdso=0: disable VDSO mapping
2107 vdso32= [X86-32,X86-64]
2108 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2109 vdso32=1: enable 32-bit VDSO (default)
2110 vdso32=0: disable 32-bit VDSO mapping
2113 vector=percpu: enable percpu vector domain
2115 video= [FB] Frame buffer configuration
2116 See Documentation/fb/modedb.txt.
2118 vga= [BOOT,X86-32] Select a particular video mode
2119 See Documentation/i386/boot.txt and
2120 Documentation/svga.txt.
2121 Use vga=ask for menu.
2122 This is actually a boot loader parameter; the value is
2123 passed to the kernel using a special protocol.
2125 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2126 size of <nn>. This can be used to increase the
2127 minimum size (128MB on x86). It can also be used to
2128 decrease the size and leave more room for directly
2131 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2134 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2137 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2140 waveartist= [HW,OSS]
2141 Format: <io>,<irq>,<dma>,<dma2>
2144 See header of drivers/scsi/wd33c93.c.
2147 See header of drivers/scsi/wd7000.c.
2150 See Documentation/watchdog/wdt.txt.
2152 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2153 xd_geo= See header of drivers/block/xd.c.
2155 xirc2ps_cs= [NET,PCMCIA]
2157 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2159 norandmaps Don't use address space randomization
2160 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2162 ______________________________________________________________________
2166 Add documentation for ALSA options.
2167 Add more DRM drivers.