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.
401 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
403 Forces specified clocksource (if available) to be used
404 when calculating gettimeofday(). If specified
405 clocksource is not available, it defaults to PIT.
406 Format: { pit | tsc | cyclone | pmtmr }
408 clocksource= [GENERIC_TIME] Override the default clocksource
410 Override the default clocksource and use the clocksource
411 with the name specified.
412 Some clocksource names to choose from, depending on
414 [all] jiffies (this is the base, fallback clocksource)
416 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
417 pxa_timer,timer3,32k_counter,timer0_1
419 [X86-32] pit,hpet,tsc,vmi-timer;
420 scx200_hrt on Geode; cyclone on IBM x440
428 clearcpuid=BITNUM [X86]
429 Disable CPUID feature X for the kernel. See
430 include/asm-x86/cpufeature.h for the valid bit numbers.
431 Note the Linux specific bits are not necessarily
432 stable over kernel options, but the vendor specific
434 Also note that user programs calling CPUID directly
435 or using the feature without checking anything
436 will still see it. This just prevents it from
437 being used by the kernel or shown in /proc/cpuinfo.
438 Also note the kernel might malfunction if you disable
441 code_bytes [IA32/X86_64] How many bytes of object code to print
448 [IA32/X86_64] Disable/Enable interrupt 0 timer routing
449 over the 8254 in addition to over the IO-APIC. The
450 kernel tries to set a sensible default.
452 hpet= [X86-32,HPET] option to control HPET usage
453 Format: { enable (default) | disable | force }
454 disable: disable HPET and use PIT instead
455 force: allow force enabled of undocumented chips (ICH4,
458 com20020= [HW,NET] ARCnet - COM20020 chipset
460 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
462 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
466 ARCnet - COM90xx chipset (memory-mapped buffers)
467 Format: <io>[,<irq>[,<memstart>]]
469 condev= [HW,S390] console device
472 console= [KNL] Output console device and options.
474 tty<n> Use the virtual console device <n>.
478 Use the specified serial port. The options are of
479 the form "bbbbpnf", where "bbbb" is the baud rate,
480 "p" is parity ("n", "o", or "e"), "n" is number of
481 bits, and "f" is flow control ("r" for RTS or
482 omit it). Default is "9600n8".
484 See Documentation/serial-console.txt for more
486 Documentation/networking/netconsole.txt for an
489 uart[8250],io,<addr>[,options]
490 uart[8250],mmio,<addr>[,options]
491 Start an early, polled-mode console on the 8250/16550
492 UART at the specified I/O port or MMIO address,
493 switching to the matching ttyS device later. The
494 options are the same as for ttyS, above.
496 If the device connected to the port is not a TTY but a braille
497 device, prepend "brl," before the device type, for instance
499 For now, only VisioBraille is supported.
501 earlycon= [KNL] Output early console device and options.
502 uart[8250],io,<addr>[,options]
503 uart[8250],mmio,<addr>[,options]
504 Start an early, polled-mode console on the 8250/16550
505 UART at the specified I/O port or MMIO address.
506 The options are the same as for ttyS, above.
509 [HW] Never suspend the console
510 Disable suspending of consoles during suspend and
511 hibernate operations. Once disabled, debugging
512 messages can reach various consoles while the rest
513 of the system is being put to sleep (ie, while
514 debugging driver suspend/resume hooks). This may
515 not work reliably with all consoles, but is known
516 to work with serial and VGA consoles.
518 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
520 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
522 crashkernel=nn[KMG]@ss[KMG]
523 [KNL] Reserve a chunk of physical memory to
524 hold a kernel to switch to with kexec on panic.
526 crashkernel=range1:size1[,range2:size2,...][@offset]
527 [KNL] Same as above, but depends on the memory
528 in the running system. The syntax of range is
529 start-[end] where start and end are both
530 a memory unit (amount[KMG]). See also
531 Documentation/kdump/kdump.txt for a example.
534 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
539 cs89x0_media= [HW,NET]
540 Format: { rj45 | aui | bnc }
543 See header of drivers/s390/block/dasd_devmap.c.
545 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
546 (one device per port)
547 Format: <port#>,<type>
548 See also Documentation/input/joystick-parport.txt
550 debug [KNL] Enable kernel debugging (events log level).
553 [KNL] verbose self-tests
555 Print debugging info while doing the locking API
557 We default to 0 (no extra messages), setting it to
558 1 will print _a lot_ more information - normally
559 only useful to kernel developers.
561 debug_objects [KNL] Enable object debugging
563 decnet.addr= [HW,NET]
564 Format: <area>[,<node>]
565 See also Documentation/networking/decnet.txt.
568 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
569 Change the default blue palette of the console.
570 This is a 16-member array composed of values
574 Format: <green0>,<green1>,<green2>,...,<green15>
575 Change the default green palette of the console.
576 This is a 16-member array composed of values
580 Format: <red0>,<red1>,<red2>,...,<red15>
581 Change the default red palette of the console.
582 This is a 16-member array composed of values
588 Set system-wide default UTF-8 mode for all tty's.
589 Default is 1, i.e. UTF-8 mode is enabled for all
590 newly opened terminals.
593 Set number of hash buckets for dentry cache.
596 IO parameters + enable/disable command.
598 digiepca= [HW,SERIAL]
599 See drivers/char/README.epca and
600 Documentation/digiepca.txt.
602 disable_mtrr_cleanup [X86]
603 enable_mtrr_cleanup [X86]
604 The kernel tries to adjust MTRR layout from continuous
605 to discrete, to make X server driver able to add WB
606 entry later. This parameter enables/disables that.
608 mtrr_chunk_size=nn[KMG] [X86]
609 used for mtrr cleanup. It is largest continous chunk
610 that could hold holes aka. UC entries.
612 mtrr_gran_size=nn[KMG] [X86]
613 Used for mtrr cleanup. It is granularity of mtrr block.
615 Large value could prevent small alignment from
618 mtrr_spare_reg_nr=n [X86]
620 Range: 0,7 : spare reg number
622 Used for mtrr cleanup. It is spare mtrr entries number.
623 Set to 2 or more if your graphical card needs more.
625 disable_mtrr_trim [X86, Intel and AMD only]
626 By default the kernel will trim any uncacheable
627 memory out of your available memory pool based on
628 MTRR settings. This parameter disables that behavior,
629 possibly causing your machine to run very slowly.
631 dmasound= [HW,OSS] Sound subsystem buffers
637 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
639 earlyprintk=serial[,ttySn[,baudrate]]
641 Append ",keep" to not disable it when the real console
644 Only vga or serial at a time, not both.
646 Currently only ttyS0 and ttyS1 are supported.
648 Interaction with the standard serial driver is not
651 The VGA output is eventually overwritten by the real
657 Format: {"off" | "on" | "skip[mbr]"}
659 eisa_irq_edge= [PARISC,HW]
660 See header of drivers/parisc/eisa.c.
663 See comment before function elanfreq_setup() in
664 arch/i386/kernel/cpu/cpufreq/elanfreq.c.
667 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
668 See Documentation/block/as-iosched.txt and
669 Documentation/block/deadline-iosched.txt for details.
671 elfcorehdr= [X86-32, X86_64]
672 Specifies physical address of start of kernel core
673 image elf header. Generally kexec loader will
674 pass this option to capture kernel.
675 See Documentation/kdump/kdump.txt for details.
677 enforcing [SELINUX] Set initial enforcing status.
679 See security/selinux/Kconfig help text.
680 0 -- permissive (log only, no denials).
681 1 -- enforcing (deny and log).
683 Value can be changed at runtime via /selinux/enforce.
686 Format: <spdif>,[<nomix>,[<amplifier>]]
687 See also header of sound/oss/es1371.c.
689 ether= [HW,NET] Ethernet cards parameters
690 This option is obsoleted by the "netdev=" option, which
691 has equivalent usage. See its documentation for details.
693 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
698 fail_make_request=[KNL]
699 General fault injection mechanism.
700 Format: <interval>,<probability>,<space>,<times>
701 See also /Documentation/fault-injection/.
704 See header of drivers/scsi/fd_mcs.c.
707 See header of drivers/scsi/fdomain.c.
710 See Documentation/floppy.txt.
712 force_pal_cache_flush
713 [IA-64] Avoid check_sal_cache_flush which may hang on
714 buggy SAL_CACHE_FLUSH implementations. Using this
715 parameter will force ia64_sal_cache_flush to call
716 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
719 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
720 support via parallel port (up to 5 devices per port)
721 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
722 See also Documentation/input/joystick-parport.txt
726 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
731 See header of drivers/scsi/gdth.c.
733 gpt [EFI] Forces disk with valid GPT signature but
734 invalid Protective MBR to be treated as GPT.
738 hashdist= [KNL,NUMA] Large hashes allocated during boot
739 are distributed across NUMA nodes. Defaults on
740 for IA-64, off otherwise.
741 Format: 0 | 1 (for off | on)
743 hcl= [IA-64] SGI's Hardware Graph compatibility layer
745 hd= [EIDE] (E)IDE hard drive subsystem geometry
746 Format: <cyl>,<head>,<sect>
748 hd?= [HW] (E)IDE subsystem
749 hd?lun= See Documentation/ide/ide.txt.
751 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
752 size of <nn>. This works even on boxes that have no
753 highmem otherwise. This also works to reduce highmem
754 size on bigger boxes.
756 highres= [KNL] Enable/disable high resolution timer mode.
757 Valid parameters: "on", "off"
761 See Documentation/isdn/README.HiSax.
763 hugepages= [HW,X86-32,IA-64] Maximal number of HugeTLB pages.
764 hugepagesz= [HW,IA-64,PPC] The size of the HugeTLB pages.
766 i8042.direct [HW] Put keyboard port into non-translated mode
767 i8042.dumbkbd [HW] Pretend that controller can only read data from
768 keyboard and cannot control its state
769 (Don't attempt to blink the leds)
770 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
771 i8042.nokbd [HW] Don't check/create keyboard port
772 i8042.noloop [HW] Disable the AUX Loopback command while probing
774 i8042.nomux [HW] Don't check presence of an active multiplexing
776 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
779 [HW] Frequency with which keyboard LEDs should blink
780 when kernel panics (default is 0.5 sec)
781 i8042.reset [HW] Reset the controller during init and cleanup
782 i8042.unlock [HW] Unlock (ignore) the keylock
786 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
787 indicates that the driver is running on unsupported
789 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
790 does not match list of supported models.
792 [HW] Report power status in /proc/i8k
793 (disabled by default)
794 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
797 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
798 See Documentation/mca.txt.
801 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
803 ide= [HW] (E)IDE subsystem
804 Format: ide=nodma or ide=doubler
805 See Documentation/ide/ide.txt.
807 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
808 See Documentation/ide/ide.txt.
811 Format: idle=poll or idle=mwait
812 Poll forces a polling idle loop that can slightly improves the performance
813 of waking up a idle CPU, but will use a lot of power and make the system
814 run hot. Not recommended.
815 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
816 to not use it because it doesn't save as much power as a normal idle
817 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
820 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
821 Claim all unknown PCI IDE storage controllers.
823 ignore_loglevel [KNL]
824 Ignore loglevel setting - this will print /all/
825 kernel messages to the console. Useful for debugging.
828 Set number of hash buckets for inode cache.
831 See header of drivers/scsi/in2000.c.
835 Run specified binary instead of /sbin/init as init
838 initcall_debug [KNL] Trace initcalls as they are executed. Useful
839 for working out where the kernel is dying during
842 initrd= [BOOT] Specify the location of the initial ramdisk
844 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
862 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
864 Disable intel iommu driver.
865 igfx_off [Default Off]
866 By default, gfx is mapped as normal device. If a gfx
867 device has a dedicated DMAR unit, the DMAR unit is
868 bypassed by not enabling DMAR with this option. In
869 this case, gfx device will use physical address for
872 With this option iommu will not optimize to look
873 for io virtual address below 32 bit forcing dual
874 address cycle on pci bus for cards supporting greater
875 than 32 bit addressing. The default is to look
876 for translation below 32 bit and if not available
877 then look in the higher range.
879 With this option on every unmap_single operation will
880 result in a hardware IOTLB flush operation as opposed
881 to batching them for performance.
883 io_delay= [X86-32,X86-64] I/O delay method
885 Standard port 0x80 based delay
887 Alternate port 0xed based delay (needed on some systems)
889 Simple two microseconds delay
893 io7= [HW] IO7 for Marvel based alpha systems
894 See comment before marvel_specify_io7 in
895 arch/alpha/kernel/core_marvel.c.
898 See Documentation/filesystems/nfsroot.txt.
900 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
901 See comment before ip2_setup() in
902 drivers/char/ip2/ip2base.c.
904 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
905 See header of drivers/scsi/ips.c.
907 ports= [IP_VS_FTP] IPVS ftp helper module
909 Up to 8 (IP_VS_APP_MAX_PORTS) ports
911 Format: <port>,<port>....
914 When an interrupt is not handled search all handlers
915 for it. Intended to get systems with badly broken
919 When an interrupt is not handled search all handlers
920 for it. Also check all handlers each timer
921 interrupt. Intended to get systems with badly broken
925 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
927 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
929 <cpu number>,...,<cpu number>
931 <cpu number>-<cpu number> (must be a positive range in ascending order)
933 <cpu number>,...,<cpu number>-<cpu number>
934 This option can be used to specify one or more CPUs
935 to isolate from the general SMP balancing and scheduling
936 algorithms. The only way to move a process onto or off
937 an "isolated" CPU is via the CPU affinity syscalls.
938 <cpu number> begins at 0 and the maximum value is
939 "number of CPUs in system - 1".
941 This option is the preferred way to isolate CPUs. The
942 alternative -- manually setting the CPU mask of all
943 tasks in the system -- can cause problems and
944 suboptimal load balancer performance.
948 js= [HW,JOY] Analog joystick
949 See Documentation/input/joystick.txt.
951 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
952 specifies the amount of memory usable by the kernel
953 for non-movable allocations. The requested amount is
954 spread evenly throughout all nodes in the system. The
955 remaining memory in each node is used for Movable
956 pages. In the event, a node is too small to have both
957 kernelcore and Movable pages, kernelcore pages will
958 take priority and other nodes will have a larger number
959 of kernelcore pages. The Movable zone is used for the
960 allocation of pages that may be reclaimed or moved
961 by the page migration subsystem. This means that
962 HugeTLB pages may not be allocated from this zone.
963 Note that allocations like PTEs-from-HighMem still
964 use the HighMem zone if it exists, and the Normal
967 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
968 is similar to kernelcore except it specifies the
969 amount of memory used for migratable allocations.
970 If both kernelcore and movablecore is specified,
971 then kernelcore will be at *least* the specified
972 value but may be more. If movablecore on its own
973 is specified, the administrator must be careful
974 that the amount of memory usable for all allocations
979 kstack=N [X86-32,X86-64] Print N words from the kernel stack
982 kgdboc= [HW] kgdb over consoles.
983 Requires a tty driver that supports console polling.
984 (only serial suported for now)
985 Format: <serial_device>[,baud]
991 lapic [X86-32,APIC] Enable the local APIC even if BIOS
994 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
997 libata.dma= [LIBATA] DMA control
998 libata.dma=0 Disable all PATA and SATA DMA
999 libata.dma=1 PATA and SATA Disk DMA only
1000 libata.dma=2 ATAPI (CDROM) DMA only
1001 libata.dma=4 Compact Flash DMA only
1002 Combinations also work, so libata.dma=3 enables DMA
1003 for disks and CDROMs, but not CFs.
1005 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1009 libata.force= [LIBATA] Force configurations. The format is comma
1010 separated list of "[ID:]VAL" where ID is
1011 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1012 matching port, link or device. Basically, it matches
1013 the ATA ID string printed on console by libata. If
1014 the whole ID part is omitted, the last PORT and DEVICE
1015 values are used. If ID hasn't been specified yet, the
1016 configuration applies to all ports, links and devices.
1018 If only DEVICE is omitted, the parameter applies to
1019 the port and all links and devices behind it. DEVICE
1020 number of 0 either selects the first device or the
1021 first fan-out link behind PMP device. It does not
1022 select the host link. DEVICE number of 15 selects the
1023 host link and device attached to it.
1025 The VAL specifies the configuration to force. As long
1026 as there's no ambiguity shortcut notation is allowed.
1027 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1028 The following configurations can be forced.
1030 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1031 Any ID with matching PORT is used.
1033 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1035 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1036 udma[/][16,25,33,44,66,100,133] notation is also
1039 * [no]ncq: Turn on or off NCQ.
1041 If there are multiple matching configurations changing
1042 the same attribute, the last one is used.
1044 load_ramdisk= [RAM] List of ramdisks to load from floppy
1045 See Documentation/ramdisk.txt.
1047 lockd.nlm_grace_period=P [NFS] Assign grace period.
1050 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1053 lockd.nlm_timeout=T [NFS] Assign timeout value.
1056 lockd.nlm_udpport=M [NFS] Assign UDP port.
1059 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1062 loglevel= All Kernel Messages with a loglevel smaller than the
1063 console loglevel will be printed to the console. It can
1064 also be changed with klogd or other programs. The
1065 loglevels are defined as follows:
1067 0 (KERN_EMERG) system is unusable
1068 1 (KERN_ALERT) action must be taken immediately
1069 2 (KERN_CRIT) critical conditions
1070 3 (KERN_ERR) error conditions
1071 4 (KERN_WARNING) warning conditions
1072 5 (KERN_NOTICE) normal but significant condition
1073 6 (KERN_INFO) informational
1074 7 (KERN_DEBUG) debug-level messages
1076 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1077 Format: { n | nk | nM }
1078 n must be a power of two. The default size
1079 is set in the kernel config file.
1081 logo.nologo [FB] Disables display of the built-in Linux logo.
1082 This may be used to provide more screen space for
1083 kernel log messages and is useful when debugging
1084 kernel boot problems.
1086 lp=0 [LP] Specify parallel ports to use, e.g,
1087 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1088 lp=reset first parallel port). 'lp=0' disables the
1089 lp=auto printer driver. 'lp=reset' (which can be
1090 specified in addition to the ports) causes
1091 attached printers to be reset. Using
1092 lp=port1,port2,... specifies the parallel ports
1093 to associate lp devices with, starting with
1094 lp0. A port specification may be 'none' to skip
1095 that lp device, or a parport name such as
1096 'parport0'. Specifying 'lp=auto' instead of a
1097 port specification list means that device IDs
1098 from each port should be examined, to see if
1099 an IEEE 1284-compliant printer is attached; if
1100 so, the driver will manage that printer.
1101 See also header of drivers/char/lp.c.
1104 Sets loops_per_jiffy to given constant, thus avoiding
1105 time-consuming boot-time autodetection (up to 250 ms per
1106 CPU). 0 enables autodetection (default). To determine
1107 the correct value for your kernel, boot with normal
1108 autodetection and see what value is printed. Note that
1109 on SMP systems the preset will be applied to all CPUs,
1110 which is likely to cause problems if your CPUs need
1111 significantly divergent settings. An incorrect value
1112 will cause delays in the kernel to be wrong, leading to
1113 unpredictable I/O errors and other breakage. Although
1114 unlikely, in the extreme case this might damage your
1118 Format: <io>,<irq>,<dma>
1120 mac5380= [HW,SCSI] Format:
1121 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1123 machvec= [IA64] Force the use of a particular machine-vector
1124 (machvec) in a generic kernel.
1125 Example: machvec=hpzx1_swiotlb
1127 max_loop= [LOOP] Maximum number of loopback devices that can
1131 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1132 should make use of. maxcpus=n : n >= 0 limits the
1133 kernel to using 'n' processors. n=0 is a special case,
1134 it is equivalent to "nosmp", which also disables
1137 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1138 equal to this physical address is ignored.
1140 max_luns= [SCSI] Maximum number of LUNs to probe.
1141 Should be between 1 and 2^32-1.
1144 [SCSI] Maximum number of LUNs received.
1145 Should be between 1 and 16384.
1149 mce [X86-32] Machine Check Exception
1151 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1153 md= [HW] RAID subsystems devices and level
1154 See Documentation/md.txt.
1157 Format: <first>,<last>
1158 Specifies range of consoles to be captured by the MDA.
1160 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1161 Amount of memory to be used when the kernel is not able
1162 to see the whole system memory or for test.
1163 [X86-32] Use together with memmap= to avoid physical
1164 address space collisions. Without memmap= PCI devices
1165 could be placed at addresses belonging to unused RAM.
1167 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1170 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1171 E820 memory map, as specified by the user.
1172 Such memmap=exactmap lines can be constructed based on
1173 BIOS output or other requirements. See the memmap=nn@ss
1176 memmap=nn[KMG]@ss[KMG]
1177 [KNL] Force usage of a specific region of memory
1178 Region of memory to be used, from ss to ss+nn.
1180 memmap=nn[KMG]#ss[KMG]
1181 [KNL,ACPI] Mark specific memory as ACPI data.
1182 Region of memory to be used, from ss to ss+nn.
1184 memmap=nn[KMG]$ss[KMG]
1185 [KNL,ACPI] Mark specific memory as reserved.
1186 Region of memory to be used, from ss to ss+nn.
1187 Example: Exclude memory from 0x18690000-0x1869ffff
1188 memmap=64K$0x18690000
1190 memmap=0x10000$0x18690000
1192 memtest= [KNL,X86_64] Enable memtest
1194 range: 0,4 : pattern number
1195 default : 0 <disable>
1197 meye.*= [HW] Set MotionEye Camera parameters
1198 See Documentation/video4linux/meye.txt.
1200 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1201 Multi-Function General Purpose Timers on AMD Geode
1204 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1205 the BIOS has incorrectly applied a workaround. TinyBIOS
1206 version 0.98 is known to be affected, 0.99 fixes the
1207 problem by letting the user disable the workaround.
1212 [MOUSE] Maximum time between finger touching and
1213 leaving touchpad surface for touch to be considered
1214 a tap and be reported as a left button click (for
1215 touchpads working in absolute mode only).
1217 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1218 reporting absolute coordinates, such as tablets
1219 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1220 reporting absolute coordinates, such as tablets
1225 MTD_Partition= [MTD]
1226 Format: <name>,<region-number>,<size>,<offset>
1228 MTD_Region= [MTD] Format:
1229 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1232 See drivers/mtd/cmdlinepart.c.
1234 mtouchusb.raw_coordinates=
1235 [HW] Make the MicroTouch USB driver use raw coordinates
1236 ('y', default) or cooked coordinates ('n')
1238 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1241 See header of drivers/scsi/NCR_D700.c.
1245 ncr53c400= [HW,SCSI]
1247 ncr53c400a= [HW,SCSI]
1249 ncr53c406a= [HW,SCSI]
1251 ncr53c8xx= [HW,SCSI]
1253 netdev= [NET] Network devices parameters
1254 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1255 Note that mem_start is often overloaded to mean
1256 something different and driver-specific.
1257 This usage is only documented in each driver source
1261 See Documentation/filesystems/nfsroot.txt.
1263 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1264 See Documentation/filesystems/nfsroot.txt.
1266 nfs.callback_tcpport=
1267 [NFS] set the TCP port on which the NFSv4 callback
1268 channel should listen.
1270 nfs.idmap_cache_timeout=
1271 [NFS] set the maximum lifetime for idmapper cache
1275 [NFS] enable 64-bit inode numbers.
1276 If zero, the NFS client will fake up a 32-bit inode
1277 number for the readdir() and stat() syscalls instead
1278 of returning the full 64-bit number.
1279 The default is to return 64-bit inode numbers.
1281 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1282 when a NMI is triggered.
1283 Format: [state][,regs][,debounce][,die]
1285 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1287 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1288 emulation library even if a 387 maths coprocessor
1291 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1292 caches in the slab allocator. Saves per-node memory,
1293 but will impact performance.
1297 noapic [SMP,APIC] Tells the kernel to not make use of any
1298 IOAPICs that may be present in the system.
1300 nobats [PPC] Do not use BATs for mapping kernel lowmem
1301 on "Classic" PPC cores.
1305 nodelayacct [KNL] Disable per-task delay accounting
1307 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1309 noefi [X86-32,X86-64] Disable EFI runtime services support.
1313 noexec [X86-32,X86-64]
1314 On X86-32 available only on PAE configured kernels.
1315 noexec=on: enable non-executable mappings (default)
1316 noexec=off: disable non-executable mappings
1319 This affects only 32-bit executables.
1320 noexec32=on: enable non-executable mappings (default)
1321 read doesn't imply executable mappings
1322 noexec32=off: disable non-executable mappings
1323 read implies executable mappings
1325 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1326 register save and restore. The kernel will only save
1327 legacy floating-point registers on task switch.
1329 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1333 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1334 instruction doesn't work correctly and not to
1337 nohalt [IA-64] Tells the kernel not to use the power saving
1338 function PAL_HALT_LIGHT when idle. This increases
1339 power-consumption. On the positive side, it reduces
1340 interrupt wake-up latency, which may improve performance
1341 in certain environments such as networked servers or
1344 nohz= [KNL] Boottime enable/disable dynamic ticks
1345 Valid arguments: on, off
1348 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1350 noirqdebug [X86-32] Disables the code which attempts to detect and
1351 disable unhandled interrupt sources.
1353 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1354 broken timer IRQ sources.
1356 noisapnp [ISAPNP] Disables ISA PnP code.
1358 noinitrd [RAM] Tells the kernel not to load any configured
1363 nojitter [IA64] Disables jitter checking for ITC timers.
1365 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1367 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1369 noltlbs [PPC] Do not use large page/tlb entries for kernel
1370 lowmem mapping on PPC40x.
1372 nomca [IA-64] Disable machine check abort handling
1374 nomce [X86-32] Machine Check Exception
1376 nomfgpt [X86-32] Disable Multi-Function General Purpose
1377 Timer usage (for AMD Geode machines).
1379 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1381 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1382 with UP alternatives
1384 noresidual [PPC] Don't use residual data on PReP machines.
1386 noresume [SWSUSP] Disables resume and restores original swap
1389 no-scroll [VGA] Disables scrollback.
1390 This is required for the Braillex ib80-piezo Braille
1391 reader made by F.H. Papenmeier (Germany).
1395 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1397 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1398 and disable the IO APIC. legacy for "maxcpus=0".
1400 nosoftlockup [KNL] Disable the soft-lockup detector.
1402 nosync [HW,M68K] Disables sync negotiation for all devices.
1404 notsc [BUGS=X86-32] Disable Time Stamp Counter
1406 nousb [USB] Disable the USB subsystem
1410 nptcg= [IA64] Override max number of concurrent global TLB
1411 purges which is reported from either PAL_VM_SUMMARY or
1414 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1415 one of ['zone', 'node', 'default'] can be specified
1416 This can be set from sysctl after boot.
1417 See Documentation/sysctl/vm.txt for details.
1419 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1421 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1422 Rather than timing out after 20 ms if an EC
1423 command is not properly ACKed, override the length
1424 of the timeout. We have interrupts disabled while
1425 waiting for the ACK, so if this is set too high
1426 interrupts *may* be lost!
1431 oprofile.timer= [HW]
1432 Use timer interrupt instead of performance counters
1434 osst= [HW,SCSI] SCSI Tape Driver
1435 Format: <buffer_size>,<write_threshold>
1436 See also Documentation/scsi/st.txt.
1438 panic= [KNL] Kernel behaviour on panic
1441 parkbd.port= [HW] Parallel port number the keyboard adapter is
1442 connected to, default is 0.
1444 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1445 0 for XT, 1 for AT (default is AT).
1448 parport= [HW,PPT] Specify parallel ports. 0 disables.
1449 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1450 Use 'auto' to force the driver to use any
1451 IRQ/DMA settings detected (the default is to
1452 ignore detected IRQ/DMA settings because of
1453 possible conflicts). You can specify the base
1454 address, IRQ, and DMA settings; IRQ and DMA
1455 should be numbers, or 'auto' (for using detected
1456 settings on that particular port), or 'nofifo'
1457 (to avoid using a FIFO even if it is detected).
1458 Parallel ports are assigned in the order they
1459 are specified on the command line, starting
1462 parport_init_mode= [HW,PPT]
1463 Configure VIA parallel port to operate in
1464 a specific mode. This is necessary on Pegasos
1465 computer where firmware has no options for setting
1466 up parallel port mode and sets it to spp.
1467 Currently this function knows 686a and 8231 chips.
1468 Format: [spp|ps2|epp|ecp|ecpepp]
1470 pas2= [HW,OSS] Format:
1471 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1474 See header of drivers/scsi/pas16.c.
1477 Halt all CPUs after the first oops has been printed for
1478 the specified number of seconds. This is to be used if
1479 your oopses keep scrolling off the screen.
1484 See header of drivers/block/paride/pcd.c.
1485 See also Documentation/paride.txt.
1487 pci=option[,option...] [PCI] various PCI subsystem options:
1488 off [X86-32] don't probe for the PCI bus
1489 bios [X86-32] force use of PCI BIOS, don't access
1490 the hardware directly. Use this if your machine
1491 has a non-standard PCI host bridge.
1492 nobios [X86-32] disallow use of PCI BIOS, only direct
1493 hardware access methods are allowed. Use this
1494 if you experience crashes upon bootup and you
1495 suspect they are caused by the BIOS.
1496 conf1 [X86-32] Force use of PCI Configuration
1498 conf2 [X86-32] Force use of PCI Configuration
1500 noaer [PCIE] If the PCIEAER kernel config parameter is
1501 enabled, this kernel boot option can be used to
1502 disable the use of PCIE advanced error reporting.
1503 nodomains [PCI] Disable support for multiple PCI
1504 root domains (aka PCI segments, in ACPI-speak).
1505 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1507 nomsi [MSI] If the PCI_MSI kernel config parameter is
1508 enabled, this kernel boot option can be used to
1509 disable the use of MSI interrupts system-wide.
1510 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1511 routing table. These calls are known to be buggy
1512 on several machines and they hang the machine
1513 when used, but on other computers it's the only
1514 way to get the interrupt routing table. Try
1515 this option if the kernel is unable to allocate
1516 IRQs or discover secondary PCI buses on your
1518 rom [X86-32] Assign address space to expansion ROMs.
1519 Use with caution as certain devices share
1520 address decoders between ROMs and other
1522 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1523 assigned automatically to PCI devices. You can
1524 make the kernel exclude IRQs of your ISA cards
1526 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1527 of the PIRQ table (normally generated
1528 by the BIOS) if it is outside the
1529 F0000h-100000h range.
1530 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1531 useful if the kernel is unable to find your
1532 secondary buses and you want to tell it
1533 explicitly which ones they are.
1534 assign-busses [X86-32] Always assign all PCI bus
1535 numbers ourselves, overriding
1536 whatever the firmware may have done.
1537 usepirqmask [X86-32] Honor the possible IRQ mask stored
1538 in the BIOS $PIR table. This is needed on
1539 some systems with broken BIOSes, notably
1540 some HP Pavilion N5400 and Omnibook XE3
1541 notebooks. This will have no effect if ACPI
1542 IRQ routing is enabled.
1543 noacpi [X86-32] Do not use ACPI for IRQ routing
1544 or for PCI scanning.
1545 use_crs [X86-32] Use _CRS for PCI resource
1547 routeirq Do IRQ routing for all PCI devices.
1548 This is normally done in pci_enable_device(),
1549 so this option is a temporary workaround
1550 for broken drivers that don't call it.
1551 skip_isa_align [X86] do not align io start addr, so can
1552 handle more pci cards
1553 firmware [ARM] Do not re-enumerate the bus but instead
1554 just use the configuration from the
1555 bootloader. This is currently used on
1556 IXP2000 systems where the bus has to be
1557 configured a certain way for adjunct CPUs.
1558 noearly [X86] Don't do any early type 1 scanning.
1559 This might help on some broken boards which
1560 machine check when some devices' config space
1561 is read. But various workarounds are disabled
1562 and some IOMMU drivers will not work.
1563 bfsort Sort PCI devices into breadth-first order.
1564 This sorting is done to get a device
1565 order compatible with older (<= 2.4) kernels.
1566 nobfsort Don't sort PCI devices into breadth-first order.
1567 cbiosize=nn[KMG] The fixed amount of bus space which is
1568 reserved for the CardBus bridge's IO window.
1569 The default value is 256 bytes.
1570 cbmemsize=nn[KMG] The fixed amount of bus space which is
1571 reserved for the CardBus bridge's memory
1572 window. The default value is 64 megabytes.
1574 pcmv= [HW,PCMCIA] BadgePAD 4
1577 See Documentation/paride.txt.
1579 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1582 See arch/parisc/kernel/pdc_chassis.c
1585 See Documentation/paride.txt.
1588 See Documentation/paride.txt.
1590 pirq= [SMP,APIC] Manual mp-table setup
1591 See Documentation/i386/IO-APIC.txt.
1593 plip= [PPT,NET] Parallel port network link
1594 Format: { parport<nr> | timid | 0 }
1595 See also Documentation/parport.txt.
1601 { on | off | curr | res | no-curr | no-res }
1604 [ISAPNP] Exclude IRQs for the autoconfiguration
1607 [ISAPNP] Exclude DMAs for the autoconfiguration
1609 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1610 Ranges are in pairs (I/O port base and size).
1613 [ISAPNP] Exclude memory regions for the
1615 Ranges are in pairs (memory base and size).
1617 print-fatal-signals=
1618 [KNL] debug: print fatal signals
1619 print-fatal-signals=1: print segfault info to
1623 printk.time= Show timing data prefixed to each printk message line
1624 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1626 profile= [KNL] Enable kernel profiling via /proc/profile
1627 Format: [schedule,]<number>
1628 Param: "schedule" - profile schedule points.
1629 Param: <number> - step/bucket size as a power of 2 for
1630 statistical time based profiling.
1631 Param: "sleep" - profile D-state sleeping (millisecs).
1632 Requires CONFIG_SCHEDSTATS
1633 Param: "kvm" - profile VM exits.
1635 processor.max_cstate= [HW,ACPI]
1636 Limit processor to maximum C-state
1637 max_cstate=9 overrides any DMI blacklist limit.
1639 processor.nocst [HW,ACPI]
1640 Ignore the _CST method to determine C-states,
1641 instead using the legacy FADT method
1643 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1645 See Documentation/ramdisk.txt.
1647 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1648 probe for; one of (bare|imps|exps|lifebook|any).
1649 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1651 psmouse.resetafter= [HW,MOUSE]
1652 Try to reset the device after so many bad packets
1655 [HW,MOUSE] Set desired mouse resolution, in dpi.
1656 psmouse.smartscroll=
1657 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1658 0 = disabled, 1 = enabled (default).
1660 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1662 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1665 See Documentation/paride.txt.
1668 [KNL] Number of legacy pty's. Overwrites compiled-in
1671 quiet [KNL] Disable most log messages
1676 See Documentation/md.txt.
1678 ramdisk_blocksize= [RAM]
1679 See Documentation/ramdisk.txt.
1681 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1682 See Documentation/ramdisk.txt.
1684 rcupdate.blimit= [KNL,BOOT]
1685 Set maximum number of finished RCU callbacks to process
1688 rcupdate.qhimark= [KNL,BOOT]
1689 Set threshold of queued
1690 RCU callbacks over which batch limiting is disabled.
1692 rcupdate.qlowmark= [KNL,BOOT]
1693 Set threshold of queued RCU callbacks below which
1694 batch limiting is re-enabled.
1698 Run specified binary instead of /init from the ramdisk,
1699 used for early userspace startup. See initrd.
1701 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1702 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1703 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1705 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1707 reservetop= [X86-32]
1709 Reserves a hole at the top of the kernel virtual
1712 reset_devices [KNL] Force drivers to reset the underlying device
1713 during initialization.
1716 Specify the partition device for software suspend
1718 resume_offset= [SWSUSP]
1719 Specify the offset from the beginning of the partition
1720 given by "resume=" at which the swap header is located,
1721 in <PAGE_SIZE> units (needed only for swap files).
1722 See Documentation/power/swsusp-and-swap-files.txt
1724 retain_initrd [RAM] Keep initrd memory after extraction
1726 rhash_entries= [KNL,NET]
1727 Set number of hash buckets for route cache
1729 riscom8= [HW,SERIAL]
1730 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1732 ro [KNL] Mount root device read-only on boot
1734 root= [KNL] Root filesystem
1736 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1737 mount the root filesystem
1739 rootflags= [KNL] Set root filesystem mount option string
1741 rootfstype= [KNL] Set root filesystem type
1743 rootwait [KNL] Wait (indefinitely) for root device to show up.
1744 Useful for devices that are detected asynchronously
1745 (e.g. USB and MMC devices).
1747 root_plug.vendor_id=
1748 [ROOTPLUG] Override the default vendor ID
1750 root_plug.product_id=
1751 [ROOTPLUG] Override the default product ID
1754 [ROOTPLUG] Enable debugging output
1756 rw [KNL] Mount root device read-write on boot
1758 S [KNL] Run init in single mode
1761 See drivers/net/irda/sa1100_ir.c.
1763 sbni= [NET] Granch SBNI12 leased line adapter
1765 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1766 Format: <io>[,<timeout>[,<isapnp>]]
1768 scsi_debug_*= [SCSI]
1769 See drivers/scsi/scsi_debug.c.
1771 scsi_default_dev_flags=
1772 [SCSI] SCSI default device flags
1775 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1776 Format: <vendor>:<model>:<flags>
1777 (flags are integer value)
1779 scsi_logging_level= [SCSI] a bit mask of logging levels
1780 See drivers/scsi/scsi_logging.h for bits. Also
1781 settable via sysctl at dev.scsi.logging_level
1782 (/proc/sys/dev/scsi/logging_level).
1783 There is also a nice 'scsi_logging_level' script in the
1784 S390-tools package, available for download at
1785 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1787 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1788 discovered. async scans them in kernel threads,
1789 allowing boot to proceed. none ignores them, expecting
1790 user space to do the scan.
1792 selinux [SELINUX] Disable or enable SELinux at boot time.
1793 Format: { "0" | "1" }
1794 See security/selinux/Kconfig help text.
1797 Default value is set via kernel config option.
1798 If enabled at boot time, /selinux/disable can be used
1799 later to disable prior to initial policy load.
1801 selinux_compat_net =
1802 [SELINUX] Set initial selinux_compat_net flag value.
1803 Format: { "0" | "1" }
1804 0 -- use new secmark-based packet controls
1805 1 -- use legacy packet controls
1806 Default value is 0 (preferred).
1807 Value can be changed at runtime via
1808 /selinux/compat_net.
1810 serialnumber [BUGS=X86-32]
1813 Maximal number of shapers.
1816 See header of drivers/scsi/sim710.c.
1823 slub_debug[=options[,slabs]] [MM, SLUB]
1824 Enabling slub_debug allows one to determine the
1825 culprit if slab objects become corrupted. Enabling
1826 slub_debug can create guard zones around objects and
1827 may poison objects when not in use. Also tracks the
1828 last alloc / free. For more information see
1829 Documentation/vm/slub.txt.
1831 slub_max_order= [MM, SLUB]
1832 Determines the maximum allowed order for slabs.
1833 A high setting may cause OOMs due to memory
1834 fragmentation. For more information see
1835 Documentation/vm/slub.txt.
1837 slub_min_objects= [MM, SLUB]
1838 The minimum number of objects per slab. SLUB will
1839 increase the slab order up to slub_max_order to
1840 generate a sufficiently large slab able to contain
1841 the number of objects indicated. The higher the number
1842 of objects the smaller the overhead of tracking slabs
1843 and the less frequently locks need to be acquired.
1844 For more information see Documentation/vm/slub.txt.
1846 slub_min_order= [MM, SLUB]
1847 Determines the mininum page order for slabs. Must be
1848 lower than slub_max_order.
1849 For more information see Documentation/vm/slub.txt.
1851 slub_nomerge [MM, SLUB]
1852 Disable merging of slabs with similar size. May be
1853 necessary if there is some reason to distinguish
1854 allocs to different slabs. Debug options disable
1855 merging on their own.
1856 For more information see Documentation/vm/slub.txt.
1859 Format: <io1>[,<io2>[,...,<io8>]]
1861 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1862 attempt to substitute SMP alternatives once at boot.
1864 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1865 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1866 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1867 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1868 smsc-ircc2.ircc_irq= [HW] IRQ line
1869 smsc-ircc2.ircc_dma= [HW] DMA channel
1870 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1871 0: Toshiba Satellite 1800 (GP data pin select)
1872 1: Fast pin select (default)
1875 snd-ad1816a= [HW,ALSA]
1877 snd-ad1848= [HW,ALSA]
1879 snd-ali5451= [HW,ALSA]
1881 snd-als100= [HW,ALSA]
1883 snd-als4000= [HW,ALSA]
1885 snd-azt2320= [HW,ALSA]
1887 snd-cmi8330= [HW,ALSA]
1889 snd-cmipci= [HW,ALSA]
1891 snd-cs4231= [HW,ALSA]
1893 snd-cs4232= [HW,ALSA]
1895 snd-cs4236= [HW,ALSA]
1897 snd-cs4281= [HW,ALSA]
1899 snd-cs46xx= [HW,ALSA]
1901 snd-dt019x= [HW,ALSA]
1903 snd-dummy= [HW,ALSA]
1905 snd-emu10k1= [HW,ALSA]
1907 snd-ens1370= [HW,ALSA]
1909 snd-ens1371= [HW,ALSA]
1911 snd-es968= [HW,ALSA]
1913 snd-es1688= [HW,ALSA]
1915 snd-es18xx= [HW,ALSA]
1917 snd-es1938= [HW,ALSA]
1919 snd-es1968= [HW,ALSA]
1921 snd-fm801= [HW,ALSA]
1923 snd-gusclassic= [HW,ALSA]
1925 snd-gusextreme= [HW,ALSA]
1927 snd-gusmax= [HW,ALSA]
1931 snd-ice1712= [HW,ALSA]
1933 snd-intel8x0= [HW,ALSA]
1935 snd-interwave= [HW,ALSA]
1940 snd-korg1212= [HW,ALSA]
1942 snd-maestro3= [HW,ALSA]
1944 snd-mpu401= [HW,ALSA]
1946 snd-mtpav= [HW,ALSA]
1948 snd-nm256= [HW,ALSA]
1950 snd-opl3sa2= [HW,ALSA]
1958 snd-opti93x= [HW,ALSA]
1962 snd-rme32= [HW,ALSA]
1964 snd-rme96= [HW,ALSA]
1966 snd-rme9652= [HW,ALSA]
1972 snd-sbawe= [HW,ALSA]
1974 snd-serial= [HW,ALSA]
1976 snd-sgalaxy= [HW,ALSA]
1978 snd-sonicvibes= [HW,ALSA]
1983 snd-sun-cs4231= [HW,ALSA]
1985 snd-trident= [HW,ALSA]
1987 snd-usb-audio= [HW,ALSA,USB]
1989 snd-via82xx= [HW,ALSA]
1991 snd-virmidi= [HW,ALSA]
1993 snd-wavefront= [HW,ALSA]
1995 snd-ymfpci= [HW,ALSA]
1997 sonypi.*= [HW] Sony Programmable I/O Control Device driver
1998 See Documentation/sonypi.txt
2000 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2001 See Documentation/specialix.txt.
2003 spia_io_base= [HW,MTD]
2009 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2011 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2012 See Documentation/scsi/st.txt.
2016 Set the STI (builtin display/keyboard on the HP-PARISC
2017 machines) console (graphic card) which should be used
2018 as the initial boot-console.
2019 See also comment in drivers/video/console/sticore.c.
2022 See comment in drivers/video/console/sticore.c.
2025 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2029 Control how the NFS server code allocates CPUs to
2030 service thread pools. Depending on how many NICs
2031 you have and where their interrupts are bound, this
2032 option will affect which CPUs will do NFS serving.
2033 Note: this parameter cannot be changed while the
2034 NFS server is running.
2036 auto the server chooses an appropriate mode
2037 automatically using heuristics
2038 global a single global pool contains all CPUs
2039 percpu one pool for each CPU
2040 pernode one pool for each NUMA node (equivalent
2041 to global on non-NUMA machines)
2043 swiotlb= [IA-64] Number of I/O TLB slabs
2047 sym53c416= [HW,SCSI]
2048 See header of drivers/scsi/sym53c416.c.
2050 sysrq_always_enabled
2052 Ignore sysrq setting - this boot parameter will
2053 neutralize any effect of /proc/sys/kernel/sysrq.
2054 Useful for debugging.
2057 See header of drivers/scsi/t128.c.
2061 thash_entries= [KNL,NET]
2062 Set number of hash buckets for TCP connection
2064 thermal.act= [HW,ACPI]
2065 -1: disable all active trip points in all thermal zones
2066 <degrees C>: override all lowest active trip points
2068 thermal.crt= [HW,ACPI]
2069 -1: disable all critical trip points in all thermal zones
2070 <degrees C>: lower all critical trip points
2072 thermal.nocrt= [HW,ACPI]
2073 Set to disable actions on ACPI thermal zone
2074 critical and hot trip points.
2076 thermal.off= [HW,ACPI]
2077 1: disable ACPI thermal control
2079 thermal.psv= [HW,ACPI]
2080 -1: disable all passive trip points
2081 <degrees C>: override all passive trip points to this value
2083 thermal.tzp= [HW,ACPI]
2084 Specify global default ACPI thermal zone polling rate
2085 <deci-seconds>: poll all this frequency
2086 0: no polling (default)
2088 tipar.timeout= [HW,PPT]
2089 Set communications timeout in tenths of a second
2092 tipar.delay= [HW,PPT]
2093 Set inter-bit delay in microseconds (default 10).
2096 See comment before function dc390_setup() in
2097 drivers/scsi/tmscsim.c.
2101 trix= [HW,OSS] MediaTrix AudioTrix Pro
2103 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2105 turbografx.map[2|3]= [HW,JOY]
2106 TurboGraFX parallel port interface
2108 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2109 See also Documentation/input/joystick-parport.txt
2111 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2112 See header of drivers/scsi/u14-34f.c.
2121 [USB] Ignore overcurrent events (default N).
2122 Some badly-designed motherboards generate lots of
2123 bogus events, for ports that aren't wired to
2124 anything. Set this parameter to avoid log spamming.
2125 Note that genuine overcurrent events won't be
2128 usbcore.autosuspend=
2129 [USB] The autosuspend time delay (in seconds) used
2130 for newly-detected USB devices (default 2). This
2131 is the time required before an idle device will be
2132 autosuspended. Devices for which the delay is set
2133 to a negative value won't be autosuspended at all.
2136 [USBHID] The interval which mice are to be polled at.
2138 vdso= [X86-32,SH,x86-64]
2139 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2140 vdso=1: enable VDSO (default)
2141 vdso=0: disable VDSO mapping
2143 vdso32= [X86-32,X86-64]
2144 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2145 vdso32=1: enable 32-bit VDSO (default)
2146 vdso32=0: disable 32-bit VDSO mapping
2149 vector=percpu: enable percpu vector domain
2151 video= [FB] Frame buffer configuration
2152 See Documentation/fb/modedb.txt.
2154 vga= [BOOT,X86-32] Select a particular video mode
2155 See Documentation/i386/boot.txt and
2156 Documentation/svga.txt.
2157 Use vga=ask for menu.
2158 This is actually a boot loader parameter; the value is
2159 passed to the kernel using a special protocol.
2161 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2162 size of <nn>. This can be used to increase the
2163 minimum size (128MB on x86). It can also be used to
2164 decrease the size and leave more room for directly
2167 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2170 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2173 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2176 waveartist= [HW,OSS]
2177 Format: <io>,<irq>,<dma>,<dma2>
2180 See header of drivers/scsi/wd33c93.c.
2183 See header of drivers/scsi/wd7000.c.
2186 See Documentation/watchdog/wdt.txt.
2188 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2189 xd_geo= See header of drivers/block/xd.c.
2191 xirc2ps_cs= [NET,PCMCIA]
2193 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2195 norandmaps Don't use address space randomization
2196 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2198 ______________________________________________________________________
2202 Add documentation for ALSA options.
2203 Add more DRM drivers.
projects / linux-2.6 / blob