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 (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86/x86_64/boot-options.txt .
104 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
106 In addition, the following text indicates that the option:
108 BUGS= Relates to possible processor bugs on the said processor.
109 KNL Is a kernel start-up parameter.
110 BOOT Is a boot loader parameter.
112 Parameters denoted with BOOT are actually interpreted by the boot
113 loader, and have no meaning to the kernel directly.
114 Do not modify the syntax of boot loader parameters without extreme
115 need or coordination with <Documentation/x86/i386/boot.txt>.
117 There are also arch-specific kernel-parameters not documented here.
118 See for example <Documentation/x86/x86_64/boot-options.txt>.
120 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
121 a trailing = on the name of any parameter states that that parameter will
122 be entered as an environment variable, whereas its absence indicates that
123 it will appear as a kernel argument readable via /proc/cmdline by programs
124 running once the system is up.
126 The number of kernel parameters is not limited, but the length of the
127 complete command line (parameters including spaces etc.) is limited to
128 a fixed number of characters. This limit depends on the architecture
129 and is between 256 and 4096 characters. It is defined in the file
130 ./include/asm/setup.h as COMMAND_LINE_SIZE.
133 acpi= [HW,ACPI,X86-64,i386]
134 Advanced Configuration and Power Interface
135 Format: { force | off | ht | strict | noirq }
136 force -- enable ACPI if default was off
137 off -- disable ACPI if default was on
138 noirq -- do not use ACPI for IRQ routing
139 ht -- run only enough ACPI to enable Hyper Threading
140 strict -- Be less tolerant of platforms that are not
141 strictly ACPI specification compliant.
143 See also Documentation/power/pm.txt, pci=noacpi
145 acpi_apic_instance= [ACPI, IOAPIC]
147 2: use 2nd APIC table, if available
148 1,0: use 1st APIC table
151 acpi_sleep= [HW,ACPI] Sleep options
152 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
153 See Documentation/power/video.txt for s3_bios and s3_mode.
154 s3_beep is for debugging; it makes the PC's speaker beep
155 as soon as the kernel's real-mode entry point is called.
156 s4_nohwsig prevents ACPI hardware signature from being
157 used during resume from hibernation.
158 old_ordering causes the ACPI 1.0 ordering of the _PTS
159 control method, wrt putting devices into low power
160 states, to be enforced (the ACPI 2.0 ordering of _PTS is
163 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
164 Format: { level | edge | high | low }
166 acpi_irq_balance [HW,ACPI]
167 ACPI will balance active IRQs
170 acpi_irq_nobalance [HW,ACPI]
171 ACPI will not move active IRQs (default)
174 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
176 Format: <irq>,<irq>...
178 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
179 Format: <irq>,<irq>...
181 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
183 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
184 Format: To spoof as Windows 98: ="Microsoft Windows"
186 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
187 acpi_osi="string1" # add string1 -- only one string
188 acpi_osi="!string2" # remove built-in string2
189 acpi_osi= # disable all strings
191 acpi_serialize [HW,ACPI] force serialization of AML methods
193 acpi_skip_timer_override [HW,ACPI]
194 Recognize and ignore IRQ0/pin2 Interrupt Override.
195 For broken nForce2 BIOS resulting in XT-PIC timer.
196 acpi_use_timer_override [HW,ACPI}
197 Use timer override. For some broken Nvidia NF5 boards
198 that require a timer override, but don't have
201 acpi_backlight= [HW,ACPI]
202 acpi_backlight=vendor
204 If set to vendor, prefer vendor specific driver
205 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
206 of the ACPI video.ko driver.
208 acpi_display_output= [HW,ACPI]
209 acpi_display_output=vendor
210 acpi_display_output=video
213 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
214 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
216 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
217 debug output. Bits in debug_layer correspond to a
218 _COMPONENT in an ACPI source file, e.g.,
219 #define _COMPONENT ACPI_PCI_COMPONENT
220 Bits in debug_level correspond to a level in
221 ACPI_DEBUG_PRINT statements, e.g.,
222 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
223 See Documentation/acpi/debug.txt for more information
224 about debug layers and levels.
226 Enable AML "Debug" output, i.e., stores to the Debug
227 object while interpreting AML:
228 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
229 Enable PCI/PCI interrupt routing info messages:
230 acpi.debug_layer=0x400000 acpi.debug_level=0x4
231 Enable all messages related to ACPI hardware:
232 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
234 Some values produce so much output that the system is
235 unusable. The "log_buf_len" parameter may be useful
236 if you need to capture more output.
238 acpi.power_nocheck= [HW,ACPI]
239 Format: 1/0 enable/disable the check of power state.
240 On some bogus BIOS the _PSC object/_STA object of
241 power resource can't return the correct device power
242 state. In such case it is unneccessary to check its
243 power state again in power transition.
244 1 : disable the power state check
246 acpi_pm_good [X86-32,X86-64]
247 Override the pmtimer bug detection: force the kernel
248 to assume that this machine's pmtimer latches its value
249 and always returns good values.
252 { off | try_unsupported }
253 off: disable AGP support
254 try_unsupported: try to drive unsupported chipsets
255 (may crash computer or cause data corruption)
257 enable_timer_pin_1 [i386,x86-64]
258 Enable PIN 1 of APIC timer
259 Can be useful to work around chipset bugs
260 (in particular on some ATI chipsets).
261 The kernel tries to set a reasonable default.
263 disable_timer_pin_1 [i386,x86-64]
264 Disable PIN 1 of APIC timer
265 Can be useful to work around chipset bugs.
268 Format: <io>,<irq>,<dma>,<dma2>,<type>
271 See header of drivers/scsi/advansys.c.
273 advwdt= [HW,WDT] Advantech WDT
274 Format: <iostart>,<iostop>
276 aedsp16= [HW,OSS] Audio Excel DSP 16
277 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
278 See also header of sound/oss/aedsp16.c.
281 See Documentation/scsi/aha152x.txt.
284 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
287 See Documentation/scsi/aic7xxx.txt.
290 See Documentation/scsi/aic79xx.txt.
292 amd_iommu= [HW,X86-84]
293 Pass parameters to the AMD IOMMU driver in the system.
295 isolate - enable device isolation (each device, as far
296 as possible, will get its own protection
298 fullflush - enable flushing of IO/TLB entries when
299 they are unmapped. Otherwise they are
300 flushed before they will be reused, which
303 amd_iommu_size= [HW,X86-64]
304 Define the size of the aperture for the AMD IOMMU
305 driver. Possible values are:
306 '32M', '64M' (default), '128M', '256M', '512M', '1G'
308 amijoy.map= [HW,JOY] Amiga joystick support
309 Map of devices attached to JOY0DAT and JOY1DAT
311 See also Documentation/kernel/input/joystick.txt
313 analog.map= [HW,JOY] Analog joystick and gamepad support
314 Specifies type or capabilities of an analog joystick
315 connected to one of 16 gameports
316 Format: <type1>,<type2>,..<type16>
319 Power management functions (SPARCstation-4/5 + deriv.)
321 Disable APC CPU standby support. SPARCstation-Fox does
322 not play well with APC CPU idle - disable it if you have
323 APC and your system crashes randomly.
325 apic= [APIC,i386] Advanced Programmable Interrupt Controller
326 Change the output verbosity whilst booting
327 Format: { quiet (default) | verbose | debug }
328 Change the amount of debugging information output
329 when initialising the APIC and IO-APIC components.
331 apm= [APM] Advanced Power Management
332 See header of arch/x86/kernel/apm_32.c.
334 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
335 Format: <io>,<irq>,<nodeID>
339 atarimouse= [HW,MOUSE] Atari Mouse
341 atascsi= [HW,SCSI] Atari SCSI
343 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
344 EzKey and similar keyboards
346 atkbd.reset= [HW] Reset keyboard during initialization
348 atkbd.set= [HW] Select keyboard code set
349 Format: <int> (2 = AT (default), 3 = PS/2)
351 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
354 atkbd.softraw= [HW] Choose between synthetic and real raw mode
355 Format: <bool> (0 = real, 1 = synthetic (default))
357 atkbd.softrepeat= [HW]
358 Use software keyboard repeat
362 baycom_epp= [HW,AX25]
365 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
367 See header of drivers/net/hamradio/baycom_par.c.
369 baycom_ser_fdx= [HW,AX25]
370 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
371 Format: <io>,<irq>,<mode>[,<baud>]
372 See header of drivers/net/hamradio/baycom_ser_fdx.c.
374 baycom_ser_hdx= [HW,AX25]
375 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
376 Format: <io>,<irq>,<mode>
377 See header of drivers/net/hamradio/baycom_ser_hdx.c.
379 boot_delay= Milliseconds to delay each printk during boot.
380 Values larger than 10 seconds (10000) are changed to
384 bootmem_debug [KNL] Enable bootmem allocator debug messages.
386 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
387 bttv.radio= Most important insmod options are available as
389 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
390 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
393 See drivers/scsi/BusLogic.c, comment before function
394 BusLogic_ParseDriverOptions().
396 c101= [NET] Moxa C101 synchronous serial card
398 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
399 Sometimes CPU hardware bugs make them report the cache
400 size incorrectly. The kernel will attempt work arounds
401 to fix known problems, but for some CPUs it is not
402 possible to determine what the correct size should be.
403 This option provides an override for these situations.
405 security= [SECURITY] Choose a security module to enable at boot.
406 If this boot parameter is not specified, only the first
407 security module asking for security registration will be
408 loaded. An invalid security module name will be treated
409 as if no module has been chosen.
412 [SECURITY] Disable capabilities. This would normally
413 be used only if an alternative security model is to be
414 configured. Potentially dangerous and should only be
415 used if you are entirely sure of the consequences.
417 ccw_timeout_log [S390]
418 See Documentation/s390/CommonIO for details.
420 cgroup_disable= [KNL] Disable a particular controller
421 Format: {name of the controller(s) to disable}
422 {Currently supported controllers - "memory"}
424 checkreqprot [SELINUX] Set initial checkreqprot flag value.
425 Format: { "0" | "1" }
426 See security/selinux/Kconfig help text.
427 0 -- check protection applied by kernel (includes
428 any implied execute protection).
429 1 -- check protection requested by application.
430 Default value is set via a kernel config option.
431 Value can be changed at runtime via
432 /selinux/checkreqprot.
435 See Documentation/s390/CommonIO for details.
437 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
439 Forces specified clocksource (if available) to be used
440 when calculating gettimeofday(). If specified
441 clocksource is not available, it defaults to PIT.
442 Format: { pit | tsc | cyclone | pmtmr }
444 clocksource= [GENERIC_TIME] Override the default clocksource
446 Override the default clocksource and use the clocksource
447 with the name specified.
448 Some clocksource names to choose from, depending on
450 [all] jiffies (this is the base, fallback clocksource)
452 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
453 pxa_timer,timer3,32k_counter,timer0_1
455 [X86-32] pit,hpet,tsc,vmi-timer;
456 scx200_hrt on Geode; cyclone on IBM x440
464 clearcpuid=BITNUM [X86]
465 Disable CPUID feature X for the kernel. See
466 include/asm-x86/cpufeature.h for the valid bit numbers.
467 Note the Linux specific bits are not necessarily
468 stable over kernel options, but the vendor specific
470 Also note that user programs calling CPUID directly
471 or using the feature without checking anything
472 will still see it. This just prevents it from
473 being used by the kernel or shown in /proc/cpuinfo.
474 Also note the kernel might malfunction if you disable
477 code_bytes [IA32/X86_64] How many bytes of object code to print
482 hpet= [X86-32,HPET] option to control HPET usage
483 Format: { enable (default) | disable | force }
484 disable: disable HPET and use PIT instead
485 force: allow force enabled of undocumented chips (ICH4,
488 com20020= [HW,NET] ARCnet - COM20020 chipset
490 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
492 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
496 ARCnet - COM90xx chipset (memory-mapped buffers)
497 Format: <io>[,<irq>[,<memstart>]]
499 condev= [HW,S390] console device
502 console= [KNL] Output console device and options.
504 tty<n> Use the virtual console device <n>.
508 Use the specified serial port. The options are of
509 the form "bbbbpnf", where "bbbb" is the baud rate,
510 "p" is parity ("n", "o", or "e"), "n" is number of
511 bits, and "f" is flow control ("r" for RTS or
512 omit it). Default is "9600n8".
514 See Documentation/serial-console.txt for more
516 Documentation/networking/netconsole.txt for an
519 uart[8250],io,<addr>[,options]
520 uart[8250],mmio,<addr>[,options]
521 Start an early, polled-mode console on the 8250/16550
522 UART at the specified I/O port or MMIO address,
523 switching to the matching ttyS device later. The
524 options are the same as for ttyS, above.
526 If the device connected to the port is not a TTY but a braille
527 device, prepend "brl," before the device type, for instance
529 For now, only VisioBraille is supported.
531 earlycon= [KNL] Output early console device and options.
532 uart[8250],io,<addr>[,options]
533 uart[8250],mmio,<addr>[,options]
534 Start an early, polled-mode console on the 8250/16550
535 UART at the specified I/O port or MMIO address.
536 The options are the same as for ttyS, above.
539 [HW] Never suspend the console
540 Disable suspending of consoles during suspend and
541 hibernate operations. Once disabled, debugging
542 messages can reach various consoles while the rest
543 of the system is being put to sleep (ie, while
544 debugging driver suspend/resume hooks). This may
545 not work reliably with all consoles, but is known
546 to work with serial and VGA consoles.
548 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
550 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
552 crashkernel=nn[KMG]@ss[KMG]
553 [KNL] Reserve a chunk of physical memory to
554 hold a kernel to switch to with kexec on panic.
556 crashkernel=range1:size1[,range2:size2,...][@offset]
557 [KNL] Same as above, but depends on the memory
558 in the running system. The syntax of range is
559 start-[end] where start and end are both
560 a memory unit (amount[KMG]). See also
561 Documentation/kdump/kdump.txt for a example.
564 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
569 cs89x0_media= [HW,NET]
570 Format: { rj45 | aui | bnc }
573 See header of drivers/s390/block/dasd_devmap.c.
575 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
576 (one device per port)
577 Format: <port#>,<type>
578 See also Documentation/input/joystick-parport.txt
580 debug [KNL] Enable kernel debugging (events log level).
583 [KNL] verbose self-tests
585 Print debugging info while doing the locking API
587 We default to 0 (no extra messages), setting it to
588 1 will print _a lot_ more information - normally
589 only useful to kernel developers.
591 debug_objects [KNL] Enable object debugging
593 debugpat [X86] Enable PAT debugging
595 decnet.addr= [HW,NET]
596 Format: <area>[,<node>]
597 See also Documentation/networking/decnet.txt.
600 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
601 Change the default blue palette of the console.
602 This is a 16-member array composed of values
606 Format: <green0>,<green1>,<green2>,...,<green15>
607 Change the default green palette of the console.
608 This is a 16-member array composed of values
612 Format: <red0>,<red1>,<red2>,...,<red15>
613 Change the default red palette of the console.
614 This is a 16-member array composed of values
620 Set system-wide default UTF-8 mode for all tty's.
621 Default is 1, i.e. UTF-8 mode is enabled for all
622 newly opened terminals.
625 Set number of hash buckets for dentry cache.
628 IO parameters + enable/disable command.
630 digiepca= [HW,SERIAL]
631 See drivers/char/README.epca and
632 Documentation/serial/digiepca.txt.
634 disable_mtrr_cleanup [X86]
635 enable_mtrr_cleanup [X86]
636 The kernel tries to adjust MTRR layout from continuous
637 to discrete, to make X server driver able to add WB
638 entry later. This parameter enables/disables that.
640 mtrr_chunk_size=nn[KMG] [X86]
641 used for mtrr cleanup. It is largest continous chunk
642 that could hold holes aka. UC entries.
644 mtrr_gran_size=nn[KMG] [X86]
645 Used for mtrr cleanup. It is granularity of mtrr block.
647 Large value could prevent small alignment from
650 mtrr_spare_reg_nr=n [X86]
652 Range: 0,7 : spare reg number
654 Used for mtrr cleanup. It is spare mtrr entries number.
655 Set to 2 or more if your graphical card needs more.
657 disable_mtrr_trim [X86, Intel and AMD only]
658 By default the kernel will trim any uncacheable
659 memory out of your available memory pool based on
660 MTRR settings. This parameter disables that behavior,
661 possibly causing your machine to run very slowly.
663 dmasound= [HW,OSS] Sound subsystem buffers
669 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
671 earlyprintk=serial[,ttySn[,baudrate]]
674 Append ",keep" to not disable it when the real console
677 Only vga or serial or usb debug port at a time.
679 Currently only ttyS0 and ttyS1 are supported.
681 Interaction with the standard serial driver is not
684 The VGA output is eventually overwritten by the real
690 Format: {"off" | "on" | "skip[mbr]"}
692 eisa_irq_edge= [PARISC,HW]
693 See header of drivers/parisc/eisa.c.
696 See comment before function elanfreq_setup() in
697 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
700 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
701 See Documentation/block/as-iosched.txt and
702 Documentation/block/deadline-iosched.txt for details.
704 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
705 Specifies physical address of start of kernel core
706 image elf header. Generally kexec loader will
707 pass this option to capture kernel.
708 See Documentation/kdump/kdump.txt for details.
710 enforcing [SELINUX] Set initial enforcing status.
712 See security/selinux/Kconfig help text.
713 0 -- permissive (log only, no denials).
714 1 -- enforcing (deny and log).
716 Value can be changed at runtime via /selinux/enforce.
719 Format: <spdif>,[<nomix>,[<amplifier>]]
720 See also header of sound/oss/es1371.c.
722 ether= [HW,NET] Ethernet cards parameters
723 This option is obsoleted by the "netdev=" option, which
724 has equivalent usage. See its documentation for details.
726 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
731 fail_make_request=[KNL]
732 General fault injection mechanism.
733 Format: <interval>,<probability>,<space>,<times>
734 See also /Documentation/fault-injection/.
737 See header of drivers/scsi/fd_mcs.c.
740 See header of drivers/scsi/fdomain.c.
743 See Documentation/blockdev/floppy.txt.
745 force_pal_cache_flush
746 [IA-64] Avoid check_sal_cache_flush which may hang on
747 buggy SAL_CACHE_FLUSH implementations. Using this
748 parameter will force ia64_sal_cache_flush to call
749 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
752 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
753 support via parallel port (up to 5 devices per port)
754 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
755 See also Documentation/input/joystick-parport.txt
759 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
764 See header of drivers/scsi/gdth.c.
766 gpt [EFI] Forces disk with valid GPT signature but
767 invalid Protective MBR to be treated as GPT.
771 hashdist= [KNL,NUMA] Large hashes allocated during boot
772 are distributed across NUMA nodes. Defaults on
773 for IA-64, off otherwise.
774 Format: 0 | 1 (for off | on)
776 hcl= [IA-64] SGI's Hardware Graph compatibility layer
778 hd= [EIDE] (E)IDE hard drive subsystem geometry
779 Format: <cyl>,<head>,<sect>
781 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
782 size of <nn>. This works even on boxes that have no
783 highmem otherwise. This also works to reduce highmem
784 size on bigger boxes.
786 highres= [KNL] Enable/disable high resolution timer mode.
787 Valid parameters: "on", "off"
791 See Documentation/isdn/README.HiSax.
793 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
794 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
795 On x86-64 and powerpc, this option can be specified
796 multiple times interleaved with hugepages= to reserve
797 huge pages of different sizes. Valid pages sizes on
798 x86-64 are 2M (when the CPU supports "pse") and 1G
799 (when the CPU supports the "pdpe1gb" cpuinfo flag)
800 Note that 1GB pages can only be allocated at boot time
801 using hugepages= and not freed afterwards.
803 [same as hugepagesz=] The size of the default
804 HugeTLB page size. This is the size represented by
805 the legacy /proc/ hugepages APIs, used for SHM, and
806 default size when mounting hugetlbfs filesystems.
807 Defaults to the default architecture's huge page size
812 i8042.debug [HW] Toggle i8042 debug mode
813 i8042.direct [HW] Put keyboard port into non-translated mode
814 i8042.dumbkbd [HW] Pretend that controller can only read data from
815 keyboard and cannot control its state
816 (Don't attempt to blink the leds)
817 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
818 i8042.nokbd [HW] Don't check/create keyboard port
819 i8042.noloop [HW] Disable the AUX Loopback command while probing
821 i8042.nomux [HW] Don't check presence of an active multiplexing
823 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
826 [HW] Frequency with which keyboard LEDs should blink
827 when kernel panics (default is 0.5 sec)
828 i8042.reset [HW] Reset the controller during init and cleanup
829 i8042.unlock [HW] Unlock (ignore) the keylock
833 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
834 indicates that the driver is running on unsupported
836 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
837 does not match list of supported models.
839 [HW] Report power status in /proc/i8k
840 (disabled by default)
841 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
844 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
845 See Documentation/mca.txt.
848 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
850 ide= [HW] (E)IDE subsystem
851 Format: ide=nodma or ide=doubler
852 See Documentation/ide/ide.txt.
854 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
855 See Documentation/ide/ide.txt.
858 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
859 Poll forces a polling idle loop that can slightly improves the performance
860 of waking up a idle CPU, but will use a lot of power and make the system
861 run hot. Not recommended.
862 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
863 to not use it because it doesn't save as much power as a normal idle
864 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
866 idle=halt. Halt is forced to be used for CPU idle.
867 In such case C2/C3 won't be used again.
868 idle=nomwait. Disable mwait for CPU C-states
870 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
871 Claim all unknown PCI IDE storage controllers.
873 ignore_loglevel [KNL]
874 Ignore loglevel setting - this will print /all/
875 kernel messages to the console. Useful for debugging.
878 Set number of hash buckets for inode cache.
881 See header of drivers/scsi/in2000.c.
885 Run specified binary instead of /sbin/init as init
888 initcall_debug [KNL] Trace initcalls as they are executed. Useful
889 for working out where the kernel is dying during
892 initrd= [BOOT] Specify the location of the initial ramdisk
894 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
912 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
914 Disable intel iommu driver.
915 igfx_off [Default Off]
916 By default, gfx is mapped as normal device. If a gfx
917 device has a dedicated DMAR unit, the DMAR unit is
918 bypassed by not enabling DMAR with this option. In
919 this case, gfx device will use physical address for
922 With this option iommu will not optimize to look
923 for io virtual address below 32 bit forcing dual
924 address cycle on pci bus for cards supporting greater
925 than 32 bit addressing. The default is to look
926 for translation below 32 bit and if not available
927 then look in the higher range.
929 With this option on every unmap_single operation will
930 result in a hardware IOTLB flush operation as opposed
931 to batching them for performance.
933 io_delay= [X86-32,X86-64] I/O delay method
935 Standard port 0x80 based delay
937 Alternate port 0xed based delay (needed on some systems)
939 Simple two microseconds delay
943 io7= [HW] IO7 for Marvel based alpha systems
944 See comment before marvel_specify_io7 in
945 arch/alpha/kernel/core_marvel.c.
948 See Documentation/filesystems/nfsroot.txt.
950 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
951 See comment before ip2_setup() in
952 drivers/char/ip2/ip2base.c.
954 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
955 See header of drivers/scsi/ips.c.
957 ports= [IP_VS_FTP] IPVS ftp helper module
959 Up to 8 (IP_VS_APP_MAX_PORTS) ports
961 Format: <port>,<port>....
964 When an interrupt is not handled search all handlers
965 for it. Intended to get systems with badly broken
969 When an interrupt is not handled search all handlers
970 for it. Also check all handlers each timer
971 interrupt. Intended to get systems with badly broken
975 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
977 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
979 <cpu number>,...,<cpu number>
981 <cpu number>-<cpu number>
982 (must be a positive range in ascending order)
984 <cpu number>,...,<cpu number>-<cpu number>
986 This option can be used to specify one or more CPUs
987 to isolate from the general SMP balancing and scheduling
988 algorithms. You can move a process onto or off an
989 "isolated" CPU via the CPU affinity syscalls or cpuset.
990 <cpu number> begins at 0 and the maximum value is
991 "number of CPUs in system - 1".
993 This option is the preferred way to isolate CPUs. The
994 alternative -- manually setting the CPU mask of all
995 tasks in the system -- can cause problems and
996 suboptimal load balancer performance.
1000 js= [HW,JOY] Analog joystick
1001 See Documentation/input/joystick.txt.
1003 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1004 specifies the amount of memory usable by the kernel
1005 for non-movable allocations. The requested amount is
1006 spread evenly throughout all nodes in the system. The
1007 remaining memory in each node is used for Movable
1008 pages. In the event, a node is too small to have both
1009 kernelcore and Movable pages, kernelcore pages will
1010 take priority and other nodes will have a larger number
1011 of kernelcore pages. The Movable zone is used for the
1012 allocation of pages that may be reclaimed or moved
1013 by the page migration subsystem. This means that
1014 HugeTLB pages may not be allocated from this zone.
1015 Note that allocations like PTEs-from-HighMem still
1016 use the HighMem zone if it exists, and the Normal
1017 zone if it does not.
1019 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1020 is similar to kernelcore except it specifies the
1021 amount of memory used for migratable allocations.
1022 If both kernelcore and movablecore is specified,
1023 then kernelcore will be at *least* the specified
1024 value but may be more. If movablecore on its own
1025 is specified, the administrator must be careful
1026 that the amount of memory usable for all allocations
1031 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1034 kgdboc= [HW] kgdb over consoles.
1035 Requires a tty driver that supports console polling.
1036 (only serial suported for now)
1037 Format: <serial_device>[,baud]
1039 kmac= [MIPS] korina ethernet MAC address.
1040 Configure the RouterBoard 532 series on-chip
1041 Ethernet adapter MAC address.
1047 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1050 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1053 libata.dma= [LIBATA] DMA control
1054 libata.dma=0 Disable all PATA and SATA DMA
1055 libata.dma=1 PATA and SATA Disk DMA only
1056 libata.dma=2 ATAPI (CDROM) DMA only
1057 libata.dma=4 Compact Flash DMA only
1058 Combinations also work, so libata.dma=3 enables DMA
1059 for disks and CDROMs, but not CFs.
1061 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1065 libata.force= [LIBATA] Force configurations. The format is comma
1066 separated list of "[ID:]VAL" where ID is
1067 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1068 matching port, link or device. Basically, it matches
1069 the ATA ID string printed on console by libata. If
1070 the whole ID part is omitted, the last PORT and DEVICE
1071 values are used. If ID hasn't been specified yet, the
1072 configuration applies to all ports, links and devices.
1074 If only DEVICE is omitted, the parameter applies to
1075 the port and all links and devices behind it. DEVICE
1076 number of 0 either selects the first device or the
1077 first fan-out link behind PMP device. It does not
1078 select the host link. DEVICE number of 15 selects the
1079 host link and device attached to it.
1081 The VAL specifies the configuration to force. As long
1082 as there's no ambiguity shortcut notation is allowed.
1083 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1084 The following configurations can be forced.
1086 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1087 Any ID with matching PORT is used.
1089 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1091 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1092 udma[/][16,25,33,44,66,100,133] notation is also
1095 * [no]ncq: Turn on or off NCQ.
1097 * nohrst, nosrst, norst: suppress hard, soft
1100 If there are multiple matching configurations changing
1101 the same attribute, the last one is used.
1103 load_ramdisk= [RAM] List of ramdisks to load from floppy
1104 See Documentation/blockdev/ramdisk.txt.
1106 lockd.nlm_grace_period=P [NFS] Assign grace period.
1109 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1112 lockd.nlm_timeout=T [NFS] Assign timeout value.
1115 lockd.nlm_udpport=M [NFS] Assign UDP port.
1118 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1121 loglevel= All Kernel Messages with a loglevel smaller than the
1122 console loglevel will be printed to the console. It can
1123 also be changed with klogd or other programs. The
1124 loglevels are defined as follows:
1126 0 (KERN_EMERG) system is unusable
1127 1 (KERN_ALERT) action must be taken immediately
1128 2 (KERN_CRIT) critical conditions
1129 3 (KERN_ERR) error conditions
1130 4 (KERN_WARNING) warning conditions
1131 5 (KERN_NOTICE) normal but significant condition
1132 6 (KERN_INFO) informational
1133 7 (KERN_DEBUG) debug-level messages
1135 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1136 Format: { n | nk | nM }
1137 n must be a power of two. The default size
1138 is set in the kernel config file.
1140 logo.nologo [FB] Disables display of the built-in Linux logo.
1141 This may be used to provide more screen space for
1142 kernel log messages and is useful when debugging
1143 kernel boot problems.
1145 lp=0 [LP] Specify parallel ports to use, e.g,
1146 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1147 lp=reset first parallel port). 'lp=0' disables the
1148 lp=auto printer driver. 'lp=reset' (which can be
1149 specified in addition to the ports) causes
1150 attached printers to be reset. Using
1151 lp=port1,port2,... specifies the parallel ports
1152 to associate lp devices with, starting with
1153 lp0. A port specification may be 'none' to skip
1154 that lp device, or a parport name such as
1155 'parport0'. Specifying 'lp=auto' instead of a
1156 port specification list means that device IDs
1157 from each port should be examined, to see if
1158 an IEEE 1284-compliant printer is attached; if
1159 so, the driver will manage that printer.
1160 See also header of drivers/char/lp.c.
1163 Sets loops_per_jiffy to given constant, thus avoiding
1164 time-consuming boot-time autodetection (up to 250 ms per
1165 CPU). 0 enables autodetection (default). To determine
1166 the correct value for your kernel, boot with normal
1167 autodetection and see what value is printed. Note that
1168 on SMP systems the preset will be applied to all CPUs,
1169 which is likely to cause problems if your CPUs need
1170 significantly divergent settings. An incorrect value
1171 will cause delays in the kernel to be wrong, leading to
1172 unpredictable I/O errors and other breakage. Although
1173 unlikely, in the extreme case this might damage your
1177 Format: <io>,<irq>,<dma>
1179 mac5380= [HW,SCSI] Format:
1180 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1182 machvec= [IA64] Force the use of a particular machine-vector
1183 (machvec) in a generic kernel.
1184 Example: machvec=hpzx1_swiotlb
1186 max_loop= [LOOP] Maximum number of loopback devices that can
1190 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1191 should make use of. maxcpus=n : n >= 0 limits the
1192 kernel to using 'n' processors. n=0 is a special case,
1193 it is equivalent to "nosmp", which also disables
1196 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1197 equal to this physical address is ignored.
1199 max_luns= [SCSI] Maximum number of LUNs to probe.
1200 Should be between 1 and 2^32-1.
1203 [SCSI] Maximum number of LUNs received.
1204 Should be between 1 and 16384.
1208 mce [X86-32] Machine Check Exception
1210 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1212 md= [HW] RAID subsystems devices and level
1213 See Documentation/md.txt.
1216 Format: <first>,<last>
1217 Specifies range of consoles to be captured by the MDA.
1219 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1220 Amount of memory to be used when the kernel is not able
1221 to see the whole system memory or for test.
1222 [X86-32] Use together with memmap= to avoid physical
1223 address space collisions. Without memmap= PCI devices
1224 could be placed at addresses belonging to unused RAM.
1226 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1230 [KNL,SH] Allow user to override the default size for
1231 per-device physically contiguous DMA buffers.
1233 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1234 E820 memory map, as specified by the user.
1235 Such memmap=exactmap lines can be constructed based on
1236 BIOS output or other requirements. See the memmap=nn@ss
1239 memmap=nn[KMG]@ss[KMG]
1240 [KNL] Force usage of a specific region of memory
1241 Region of memory to be used, from ss to ss+nn.
1243 memmap=nn[KMG]#ss[KMG]
1244 [KNL,ACPI] Mark specific memory as ACPI data.
1245 Region of memory to be used, from ss to ss+nn.
1247 memmap=nn[KMG]$ss[KMG]
1248 [KNL,ACPI] Mark specific memory as reserved.
1249 Region of memory to be used, from ss to ss+nn.
1250 Example: Exclude memory from 0x18690000-0x1869ffff
1251 memmap=64K$0x18690000
1253 memmap=0x10000$0x18690000
1255 memory_corruption_check=0/1 [X86]
1256 Some BIOSes seem to corrupt the first 64k of
1257 memory when doing things like suspend/resume.
1258 Setting this option will scan the memory
1259 looking for corruption. Enabling this will
1260 both detect corruption and prevent the kernel
1261 from using the memory being corrupted.
1262 However, its intended as a diagnostic tool; if
1263 repeatable BIOS-originated corruption always
1264 affects the same memory, you can use memmap=
1265 to prevent the kernel from using that memory.
1267 memory_corruption_check_size=size [X86]
1268 By default it checks for corruption in the low
1269 64k, making this memory unavailable for normal
1270 use. Use this parameter to scan for
1271 corruption in more or less memory.
1273 memory_corruption_check_period=seconds [X86]
1274 By default it checks for corruption every 60
1275 seconds. Use this parameter to check at some
1276 other rate. 0 disables periodic checking.
1278 memtest= [KNL,X86] Enable memtest
1280 range: 0,4 : pattern number
1281 default : 0 <disable>
1283 meye.*= [HW] Set MotionEye Camera parameters
1284 See Documentation/video4linux/meye.txt.
1286 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1287 Multi-Function General Purpose Timers on AMD Geode
1290 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1291 the BIOS has incorrectly applied a workaround. TinyBIOS
1292 version 0.98 is known to be affected, 0.99 fixes the
1293 problem by letting the user disable the workaround.
1298 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1299 parameter allows control of the logging verbosity for
1300 the additional memory initialisation checks. A value
1301 of 0 disables mminit logging and a level of 4 will
1302 log everything. Information is printed at KERN_DEBUG
1303 so loglevel=8 may also need to be specified.
1306 [MOUSE] Maximum time between finger touching and
1307 leaving touchpad surface for touch to be considered
1308 a tap and be reported as a left button click (for
1309 touchpads working in absolute mode only).
1311 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1312 reporting absolute coordinates, such as tablets
1313 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1314 reporting absolute coordinates, such as tablets
1319 MTD_Partition= [MTD]
1320 Format: <name>,<region-number>,<size>,<offset>
1322 MTD_Region= [MTD] Format:
1323 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1326 See drivers/mtd/cmdlinepart.c.
1329 ARM/S3C2412 JIVE boot control
1331 See arch/arm/mach-s3c2412/mach-jive.c
1333 mtouchusb.raw_coordinates=
1334 [HW] Make the MicroTouch USB driver use raw coordinates
1335 ('y', default) or cooked coordinates ('n')
1337 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1340 See header of drivers/scsi/NCR_D700.c.
1344 ncr53c400= [HW,SCSI]
1346 ncr53c400a= [HW,SCSI]
1348 ncr53c406a= [HW,SCSI]
1350 ncr53c8xx= [HW,SCSI]
1352 netdev= [NET] Network devices parameters
1353 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1354 Note that mem_start is often overloaded to mean
1355 something different and driver-specific.
1356 This usage is only documented in each driver source
1360 [NETFILTER] Enable connection tracking flow accounting
1361 0 to disable accounting
1362 1 to enable accounting
1363 Default value depends on CONFIG_NF_CT_ACCT that is
1364 going to be removed in 2.6.29.
1367 See Documentation/filesystems/nfsroot.txt.
1369 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1370 See Documentation/filesystems/nfsroot.txt.
1372 nfs.callback_tcpport=
1373 [NFS] set the TCP port on which the NFSv4 callback
1374 channel should listen.
1376 nfs.idmap_cache_timeout=
1377 [NFS] set the maximum lifetime for idmapper cache
1381 [NFS] enable 64-bit inode numbers.
1382 If zero, the NFS client will fake up a 32-bit inode
1383 number for the readdir() and stat() syscalls instead
1384 of returning the full 64-bit number.
1385 The default is to return 64-bit inode numbers.
1387 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1388 when a NMI is triggered.
1389 Format: [state][,regs][,debounce][,die]
1391 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1393 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1394 emulation library even if a 387 maths coprocessor
1397 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1398 caches in the slab allocator. Saves per-node memory,
1399 but will impact performance.
1403 noapic [SMP,APIC] Tells the kernel to not make use of any
1404 IOAPICs that may be present in the system.
1406 nobats [PPC] Do not use BATs for mapping kernel lowmem
1407 on "Classic" PPC cores.
1411 nodelayacct [KNL] Disable per-task delay accounting
1413 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1415 nodsp [SH] Disable hardware DSP at boot time.
1417 noefi [X86-32,X86-64] Disable EFI runtime services support.
1421 noexec [X86-32,X86-64]
1422 On X86-32 available only on PAE configured kernels.
1423 noexec=on: enable non-executable mappings (default)
1424 noexec=off: disable non-executable mappings
1427 This affects only 32-bit executables.
1428 noexec32=on: enable non-executable mappings (default)
1429 read doesn't imply executable mappings
1430 noexec32=off: disable non-executable mappings
1431 read implies executable mappings
1433 nofpu [SH] Disable hardware FPU at boot time.
1435 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1436 register save and restore. The kernel will only save
1437 legacy floating-point registers on task switch.
1439 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1443 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1444 instruction doesn't work correctly and not to
1447 nohalt [IA-64] Tells the kernel not to use the power saving
1448 function PAL_HALT_LIGHT when idle. This increases
1449 power-consumption. On the positive side, it reduces
1450 interrupt wake-up latency, which may improve performance
1451 in certain environments such as networked servers or
1454 nohz= [KNL] Boottime enable/disable dynamic ticks
1455 Valid arguments: on, off
1458 noirqdebug [X86-32] Disables the code which attempts to detect and
1459 disable unhandled interrupt sources.
1461 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1462 broken timer IRQ sources.
1464 noisapnp [ISAPNP] Disables ISA PnP code.
1466 noinitrd [RAM] Tells the kernel not to load any configured
1471 nojitter [IA64] Disables jitter checking for ITC timers.
1473 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1475 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1477 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1479 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1480 default x2apic cluster mode on platforms
1483 noltlbs [PPC] Do not use large page/tlb entries for kernel
1484 lowmem mapping on PPC40x.
1486 nomca [IA-64] Disable machine check abort handling
1488 nomce [X86-32] Machine Check Exception
1490 nomfgpt [X86-32] Disable Multi-Function General Purpose
1491 Timer usage (for AMD Geode machines).
1493 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1495 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1496 with UP alternatives
1498 noresidual [PPC] Don't use residual data on PReP machines.
1500 noresume [SWSUSP] Disables resume and restores original swap
1503 no-scroll [VGA] Disables scrollback.
1504 This is required for the Braillex ib80-piezo Braille
1505 reader made by F.H. Papenmeier (Germany).
1509 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1511 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1512 and disable the IO APIC. legacy for "maxcpus=0".
1514 nosoftlockup [KNL] Disable the soft-lockup detector.
1516 nosync [HW,M68K] Disables sync negotiation for all devices.
1518 notsc [BUGS=X86-32] Disable Time Stamp Counter
1520 nousb [USB] Disable the USB subsystem
1524 nptcg= [IA64] Override max number of concurrent global TLB
1525 purges which is reported from either PAL_VM_SUMMARY or
1528 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1529 one of ['zone', 'node', 'default'] can be specified
1530 This can be set from sysctl after boot.
1531 See Documentation/sysctl/vm.txt for details.
1533 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1535 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1536 Rather than timing out after 20 ms if an EC
1537 command is not properly ACKed, override the length
1538 of the timeout. We have interrupts disabled while
1539 waiting for the ACK, so if this is set too high
1540 interrupts *may* be lost!
1545 oprofile.timer= [HW]
1546 Use timer interrupt instead of performance counters
1548 osst= [HW,SCSI] SCSI Tape Driver
1549 Format: <buffer_size>,<write_threshold>
1550 See also Documentation/scsi/st.txt.
1552 panic= [KNL] Kernel behaviour on panic
1555 parkbd.port= [HW] Parallel port number the keyboard adapter is
1556 connected to, default is 0.
1558 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1559 0 for XT, 1 for AT (default is AT).
1562 parport= [HW,PPT] Specify parallel ports. 0 disables.
1563 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1564 Use 'auto' to force the driver to use any
1565 IRQ/DMA settings detected (the default is to
1566 ignore detected IRQ/DMA settings because of
1567 possible conflicts). You can specify the base
1568 address, IRQ, and DMA settings; IRQ and DMA
1569 should be numbers, or 'auto' (for using detected
1570 settings on that particular port), or 'nofifo'
1571 (to avoid using a FIFO even if it is detected).
1572 Parallel ports are assigned in the order they
1573 are specified on the command line, starting
1576 parport_init_mode= [HW,PPT]
1577 Configure VIA parallel port to operate in
1578 a specific mode. This is necessary on Pegasos
1579 computer where firmware has no options for setting
1580 up parallel port mode and sets it to spp.
1581 Currently this function knows 686a and 8231 chips.
1582 Format: [spp|ps2|epp|ecp|ecpepp]
1584 pas2= [HW,OSS] Format:
1585 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1588 See header of drivers/scsi/pas16.c.
1591 Halt all CPUs after the first oops has been printed for
1592 the specified number of seconds. This is to be used if
1593 your oopses keep scrolling off the screen.
1598 See header of drivers/block/paride/pcd.c.
1599 See also Documentation/blockdev/paride.txt.
1601 pci=option[,option...] [PCI] various PCI subsystem options:
1602 off [X86] don't probe for the PCI bus
1603 bios [X86-32] force use of PCI BIOS, don't access
1604 the hardware directly. Use this if your machine
1605 has a non-standard PCI host bridge.
1606 nobios [X86-32] disallow use of PCI BIOS, only direct
1607 hardware access methods are allowed. Use this
1608 if you experience crashes upon bootup and you
1609 suspect they are caused by the BIOS.
1610 conf1 [X86] Force use of PCI Configuration
1612 conf2 [X86] Force use of PCI Configuration
1614 noaer [PCIE] If the PCIEAER kernel config parameter is
1615 enabled, this kernel boot option can be used to
1616 disable the use of PCIE advanced error reporting.
1617 nodomains [PCI] Disable support for multiple PCI
1618 root domains (aka PCI segments, in ACPI-speak).
1619 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1621 nomsi [MSI] If the PCI_MSI kernel config parameter is
1622 enabled, this kernel boot option can be used to
1623 disable the use of MSI interrupts system-wide.
1624 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1625 routing table. These calls are known to be buggy
1626 on several machines and they hang the machine
1627 when used, but on other computers it's the only
1628 way to get the interrupt routing table. Try
1629 this option if the kernel is unable to allocate
1630 IRQs or discover secondary PCI buses on your
1632 rom [X86] Assign address space to expansion ROMs.
1633 Use with caution as certain devices share
1634 address decoders between ROMs and other
1636 norom [X86] Do not assign address space to
1637 expansion ROMs that do not already have
1638 BIOS assigned address ranges.
1639 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1640 assigned automatically to PCI devices. You can
1641 make the kernel exclude IRQs of your ISA cards
1643 pirqaddr=0xAAAAA [X86] Specify the physical address
1644 of the PIRQ table (normally generated
1645 by the BIOS) if it is outside the
1646 F0000h-100000h range.
1647 lastbus=N [X86] Scan all buses thru bus #N. Can be
1648 useful if the kernel is unable to find your
1649 secondary buses and you want to tell it
1650 explicitly which ones they are.
1651 assign-busses [X86] Always assign all PCI bus
1652 numbers ourselves, overriding
1653 whatever the firmware may have done.
1654 usepirqmask [X86] Honor the possible IRQ mask stored
1655 in the BIOS $PIR table. This is needed on
1656 some systems with broken BIOSes, notably
1657 some HP Pavilion N5400 and Omnibook XE3
1658 notebooks. This will have no effect if ACPI
1659 IRQ routing is enabled.
1660 noacpi [X86] Do not use ACPI for IRQ routing
1661 or for PCI scanning.
1662 use_crs [X86] Use _CRS for PCI resource
1664 routeirq Do IRQ routing for all PCI devices.
1665 This is normally done in pci_enable_device(),
1666 so this option is a temporary workaround
1667 for broken drivers that don't call it.
1668 skip_isa_align [X86] do not align io start addr, so can
1669 handle more pci cards
1670 firmware [ARM] Do not re-enumerate the bus but instead
1671 just use the configuration from the
1672 bootloader. This is currently used on
1673 IXP2000 systems where the bus has to be
1674 configured a certain way for adjunct CPUs.
1675 noearly [X86] Don't do any early type 1 scanning.
1676 This might help on some broken boards which
1677 machine check when some devices' config space
1678 is read. But various workarounds are disabled
1679 and some IOMMU drivers will not work.
1680 bfsort Sort PCI devices into breadth-first order.
1681 This sorting is done to get a device
1682 order compatible with older (<= 2.4) kernels.
1683 nobfsort Don't sort PCI devices into breadth-first order.
1684 cbiosize=nn[KMG] The fixed amount of bus space which is
1685 reserved for the CardBus bridge's IO window.
1686 The default value is 256 bytes.
1687 cbmemsize=nn[KMG] The fixed amount of bus space which is
1688 reserved for the CardBus bridge's memory
1689 window. The default value is 64 megabytes.
1691 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1694 force Enable ASPM even on devices that claim not to support it.
1695 WARNING: Forcing ASPM on may cause system lockups.
1697 pcmv= [HW,PCMCIA] BadgePAD 4
1700 See Documentation/blockdev/paride.txt.
1702 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1705 See arch/parisc/kernel/pdc_chassis.c
1708 See Documentation/blockdev/paride.txt.
1711 See Documentation/blockdev/paride.txt.
1713 pirq= [SMP,APIC] Manual mp-table setup
1714 See Documentation/x86/i386/IO-APIC.txt.
1716 plip= [PPT,NET] Parallel port network link
1717 Format: { parport<nr> | timid | 0 }
1718 See also Documentation/parport.txt.
1720 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1721 Override pmtimer IOPort with a hex value.
1725 Enable PNP debug messages. This depends on the
1726 CONFIG_PNP_DEBUG_MESSAGES option.
1732 { on | off | curr | res | no-curr | no-res }
1735 [ISAPNP] Exclude IRQs for the autoconfiguration
1738 [ISAPNP] Exclude DMAs for the autoconfiguration
1740 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1741 Ranges are in pairs (I/O port base and size).
1744 [ISAPNP] Exclude memory regions for the
1746 Ranges are in pairs (memory base and size).
1749 Enables pr_debug()/dev_dbg() calls if
1750 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled. These can also
1751 be switched on/off via <debugfs>/dynamic_printk/modules
1753 print-fatal-signals=
1754 [KNL] debug: print fatal signals
1755 print-fatal-signals=1: print segfault info to
1759 printk.time= Show timing data prefixed to each printk message line
1760 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1762 profile= [KNL] Enable kernel profiling via /proc/profile
1763 Format: [schedule,]<number>
1764 Param: "schedule" - profile schedule points.
1765 Param: <number> - step/bucket size as a power of 2 for
1766 statistical time based profiling.
1767 Param: "sleep" - profile D-state sleeping (millisecs).
1768 Requires CONFIG_SCHEDSTATS
1769 Param: "kvm" - profile VM exits.
1771 processor.max_cstate= [HW,ACPI]
1772 Limit processor to maximum C-state
1773 max_cstate=9 overrides any DMI blacklist limit.
1775 processor.nocst [HW,ACPI]
1776 Ignore the _CST method to determine C-states,
1777 instead using the legacy FADT method
1779 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1781 See Documentation/blockdev/ramdisk.txt.
1783 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1784 probe for; one of (bare|imps|exps|lifebook|any).
1785 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1787 psmouse.resetafter= [HW,MOUSE]
1788 Try to reset the device after so many bad packets
1791 [HW,MOUSE] Set desired mouse resolution, in dpi.
1792 psmouse.smartscroll=
1793 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1794 0 = disabled, 1 = enabled (default).
1796 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1798 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1801 See Documentation/blockdev/paride.txt.
1804 [KNL] Number of legacy pty's. Overwrites compiled-in
1807 quiet [KNL] Disable most log messages
1812 See Documentation/md.txt.
1814 ramdisk_blocksize= [RAM]
1815 See Documentation/blockdev/ramdisk.txt.
1817 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1818 See Documentation/blockdev/ramdisk.txt.
1820 rcupdate.blimit= [KNL,BOOT]
1821 Set maximum number of finished RCU callbacks to process
1824 rcupdate.qhimark= [KNL,BOOT]
1825 Set threshold of queued
1826 RCU callbacks over which batch limiting is disabled.
1828 rcupdate.qlowmark= [KNL,BOOT]
1829 Set threshold of queued RCU callbacks below which
1830 batch limiting is re-enabled.
1834 Run specified binary instead of /init from the ramdisk,
1835 used for early userspace startup. See initrd.
1837 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1838 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1839 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1842 [KNL, SMP] Set scheduler's default relax_domain_level.
1843 See Documentation/cpusets.txt.
1845 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1847 reservetop= [X86-32]
1849 Reserves a hole at the top of the kernel virtual
1852 reset_devices [KNL] Force drivers to reset the underlying device
1853 during initialization.
1856 Specify the partition device for software suspend
1858 resume_offset= [SWSUSP]
1859 Specify the offset from the beginning of the partition
1860 given by "resume=" at which the swap header is located,
1861 in <PAGE_SIZE> units (needed only for swap files).
1862 See Documentation/power/swsusp-and-swap-files.txt
1864 retain_initrd [RAM] Keep initrd memory after extraction
1866 rhash_entries= [KNL,NET]
1867 Set number of hash buckets for route cache
1869 riscom8= [HW,SERIAL]
1870 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1872 ro [KNL] Mount root device read-only on boot
1874 root= [KNL] Root filesystem
1876 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1877 mount the root filesystem
1879 rootflags= [KNL] Set root filesystem mount option string
1881 rootfstype= [KNL] Set root filesystem type
1883 rootwait [KNL] Wait (indefinitely) for root device to show up.
1884 Useful for devices that are detected asynchronously
1885 (e.g. USB and MMC devices).
1887 root_plug.vendor_id=
1888 [ROOTPLUG] Override the default vendor ID
1890 root_plug.product_id=
1891 [ROOTPLUG] Override the default product ID
1894 [ROOTPLUG] Enable debugging output
1896 rw [KNL] Mount root device read-write on boot
1898 S [KNL] Run init in single mode
1901 See drivers/net/irda/sa1100_ir.c.
1903 sbni= [NET] Granch SBNI12 leased line adapter
1905 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1906 Format: <io>[,<timeout>[,<isapnp>]]
1908 scsi_debug_*= [SCSI]
1909 See drivers/scsi/scsi_debug.c.
1911 scsi_default_dev_flags=
1912 [SCSI] SCSI default device flags
1915 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1916 Format: <vendor>:<model>:<flags>
1917 (flags are integer value)
1919 scsi_logging_level= [SCSI] a bit mask of logging levels
1920 See drivers/scsi/scsi_logging.h for bits. Also
1921 settable via sysctl at dev.scsi.logging_level
1922 (/proc/sys/dev/scsi/logging_level).
1923 There is also a nice 'scsi_logging_level' script in the
1924 S390-tools package, available for download at
1925 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1927 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1928 discovered. async scans them in kernel threads,
1929 allowing boot to proceed. none ignores them, expecting
1930 user space to do the scan.
1932 selinux [SELINUX] Disable or enable SELinux at boot time.
1933 Format: { "0" | "1" }
1934 See security/selinux/Kconfig help text.
1937 Default value is set via kernel config option.
1938 If enabled at boot time, /selinux/disable can be used
1939 later to disable prior to initial policy load.
1941 selinux_compat_net =
1942 [SELINUX] Set initial selinux_compat_net flag value.
1943 Format: { "0" | "1" }
1944 0 -- use new secmark-based packet controls
1945 1 -- use legacy packet controls
1946 Default value is 0 (preferred).
1947 Value can be changed at runtime via
1948 /selinux/compat_net.
1950 serialnumber [BUGS=X86-32]
1953 Maximal number of shapers.
1955 show_msr= [x86] show boot-time MSR settings
1956 Format: { <integer> }
1957 Show boot-time (BIOS-initialized) MSR settings.
1958 The parameter means the number of CPUs to show,
1959 for example 1 means boot CPU only.
1962 See header of drivers/scsi/sim710.c.
1969 slub_debug[=options[,slabs]] [MM, SLUB]
1970 Enabling slub_debug allows one to determine the
1971 culprit if slab objects become corrupted. Enabling
1972 slub_debug can create guard zones around objects and
1973 may poison objects when not in use. Also tracks the
1974 last alloc / free. For more information see
1975 Documentation/vm/slub.txt.
1977 slub_max_order= [MM, SLUB]
1978 Determines the maximum allowed order for slabs.
1979 A high setting may cause OOMs due to memory
1980 fragmentation. For more information see
1981 Documentation/vm/slub.txt.
1983 slub_min_objects= [MM, SLUB]
1984 The minimum number of objects per slab. SLUB will
1985 increase the slab order up to slub_max_order to
1986 generate a sufficiently large slab able to contain
1987 the number of objects indicated. The higher the number
1988 of objects the smaller the overhead of tracking slabs
1989 and the less frequently locks need to be acquired.
1990 For more information see Documentation/vm/slub.txt.
1992 slub_min_order= [MM, SLUB]
1993 Determines the mininum page order for slabs. Must be
1994 lower than slub_max_order.
1995 For more information see Documentation/vm/slub.txt.
1997 slub_nomerge [MM, SLUB]
1998 Disable merging of slabs with similar size. May be
1999 necessary if there is some reason to distinguish
2000 allocs to different slabs. Debug options disable
2001 merging on their own.
2002 For more information see Documentation/vm/slub.txt.
2005 Format: <io1>[,<io2>[,...,<io8>]]
2007 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2008 attempt to substitute SMP alternatives once at boot.
2010 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2011 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2012 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2013 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2014 smsc-ircc2.ircc_irq= [HW] IRQ line
2015 smsc-ircc2.ircc_dma= [HW] DMA channel
2016 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2017 0: Toshiba Satellite 1800 (GP data pin select)
2018 1: Fast pin select (default)
2021 snd-ad1816a= [HW,ALSA]
2023 snd-ad1848= [HW,ALSA]
2025 snd-ali5451= [HW,ALSA]
2027 snd-als100= [HW,ALSA]
2029 snd-als4000= [HW,ALSA]
2031 snd-azt2320= [HW,ALSA]
2033 snd-cmi8330= [HW,ALSA]
2035 snd-cmipci= [HW,ALSA]
2037 snd-cs4231= [HW,ALSA]
2039 snd-cs4232= [HW,ALSA]
2041 snd-cs4236= [HW,ALSA]
2043 snd-cs4281= [HW,ALSA]
2045 snd-cs46xx= [HW,ALSA]
2047 snd-dt019x= [HW,ALSA]
2049 snd-dummy= [HW,ALSA]
2051 snd-emu10k1= [HW,ALSA]
2053 snd-ens1370= [HW,ALSA]
2055 snd-ens1371= [HW,ALSA]
2057 snd-es968= [HW,ALSA]
2059 snd-es1688= [HW,ALSA]
2061 snd-es18xx= [HW,ALSA]
2063 snd-es1938= [HW,ALSA]
2065 snd-es1968= [HW,ALSA]
2067 snd-fm801= [HW,ALSA]
2069 snd-gusclassic= [HW,ALSA]
2071 snd-gusextreme= [HW,ALSA]
2073 snd-gusmax= [HW,ALSA]
2077 snd-ice1712= [HW,ALSA]
2079 snd-intel8x0= [HW,ALSA]
2081 snd-interwave= [HW,ALSA]
2086 snd-korg1212= [HW,ALSA]
2088 snd-maestro3= [HW,ALSA]
2090 snd-mpu401= [HW,ALSA]
2092 snd-mtpav= [HW,ALSA]
2094 snd-nm256= [HW,ALSA]
2096 snd-opl3sa2= [HW,ALSA]
2104 snd-opti93x= [HW,ALSA]
2108 snd-rme32= [HW,ALSA]
2110 snd-rme96= [HW,ALSA]
2112 snd-rme9652= [HW,ALSA]
2118 snd-sbawe= [HW,ALSA]
2120 snd-serial= [HW,ALSA]
2122 snd-sgalaxy= [HW,ALSA]
2124 snd-sonicvibes= [HW,ALSA]
2129 snd-sun-cs4231= [HW,ALSA]
2131 snd-trident= [HW,ALSA]
2133 snd-usb-audio= [HW,ALSA,USB]
2135 snd-via82xx= [HW,ALSA]
2137 snd-virmidi= [HW,ALSA]
2139 snd-wavefront= [HW,ALSA]
2141 snd-ymfpci= [HW,ALSA]
2144 [KNL] Should the soft-lockup detector generate panics.
2146 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2147 See Documentation/sonypi.txt
2149 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2150 See Documentation/serial/specialix.txt.
2152 spia_io_base= [HW,MTD]
2158 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2160 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2161 See Documentation/scsi/st.txt.
2165 Set the STI (builtin display/keyboard on the HP-PARISC
2166 machines) console (graphic card) which should be used
2167 as the initial boot-console.
2168 See also comment in drivers/video/console/sticore.c.
2171 See comment in drivers/video/console/sticore.c.
2174 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2178 Control how the NFS server code allocates CPUs to
2179 service thread pools. Depending on how many NICs
2180 you have and where their interrupts are bound, this
2181 option will affect which CPUs will do NFS serving.
2182 Note: this parameter cannot be changed while the
2183 NFS server is running.
2185 auto the server chooses an appropriate mode
2186 automatically using heuristics
2187 global a single global pool contains all CPUs
2188 percpu one pool for each CPU
2189 pernode one pool for each NUMA node (equivalent
2190 to global on non-NUMA machines)
2192 swiotlb= [IA-64] Number of I/O TLB slabs
2196 sym53c416= [HW,SCSI]
2197 See header of drivers/scsi/sym53c416.c.
2199 sysrq_always_enabled
2201 Ignore sysrq setting - this boot parameter will
2202 neutralize any effect of /proc/sys/kernel/sysrq.
2203 Useful for debugging.
2206 See header of drivers/scsi/t128.c.
2210 test_suspend= [SUSPEND]
2211 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2212 standby suspend) as the system sleep state to briefly
2213 enter during system startup. The system is woken from
2214 this state using a wakeup-capable RTC alarm.
2216 thash_entries= [KNL,NET]
2217 Set number of hash buckets for TCP connection
2219 thermal.act= [HW,ACPI]
2220 -1: disable all active trip points in all thermal zones
2221 <degrees C>: override all lowest active trip points
2223 thermal.crt= [HW,ACPI]
2224 -1: disable all critical trip points in all thermal zones
2225 <degrees C>: override all critical trip points
2227 thermal.nocrt= [HW,ACPI]
2228 Set to disable actions on ACPI thermal zone
2229 critical and hot trip points.
2231 thermal.off= [HW,ACPI]
2232 1: disable ACPI thermal control
2234 thermal.psv= [HW,ACPI]
2235 -1: disable all passive trip points
2236 <degrees C>: override all passive trip points to this value
2238 thermal.tzp= [HW,ACPI]
2239 Specify global default ACPI thermal zone polling rate
2240 <deci-seconds>: poll all this frequency
2241 0: no polling (default)
2244 See comment before function dc390_setup() in
2245 drivers/scsi/tmscsim.c.
2249 trix= [HW,OSS] MediaTrix AudioTrix Pro
2251 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2253 turbografx.map[2|3]= [HW,JOY]
2254 TurboGraFX parallel port interface
2256 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2257 See also Documentation/input/joystick-parport.txt
2259 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2260 See header of drivers/scsi/u14-34f.c.
2269 [USB] Ignore overcurrent events (default N).
2270 Some badly-designed motherboards generate lots of
2271 bogus events, for ports that aren't wired to
2272 anything. Set this parameter to avoid log spamming.
2273 Note that genuine overcurrent events won't be
2278 Set unknown_nmi_panic=1 early on boot.
2280 usbcore.autosuspend=
2281 [USB] The autosuspend time delay (in seconds) used
2282 for newly-detected USB devices (default 2). This
2283 is the time required before an idle device will be
2284 autosuspended. Devices for which the delay is set
2285 to a negative value won't be autosuspended at all.
2287 usbcore.usbfs_snoop=
2288 [USB] Set to log all usbfs traffic (default 0 = off).
2290 usbcore.blinkenlights=
2291 [USB] Set to cycle leds on hubs (default 0 = off).
2293 usbcore.old_scheme_first=
2294 [USB] Start with the old device initialization
2295 scheme (default 0 = off).
2297 usbcore.use_both_schemes=
2298 [USB] Try the other device initialization scheme
2299 if the first one fails (default 1 = enabled).
2301 usbcore.initial_descriptor_timeout=
2302 [USB] Specifies timeout for the initial 64-byte
2303 USB_REQ_GET_DESCRIPTOR request in milliseconds
2304 (default 5000 = 5.0 seconds).
2307 [USBHID] The interval which mice are to be polled at.
2309 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2310 kernel's map of available physical RAM.
2312 vdso= [X86-32,SH,x86-64]
2313 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2314 vdso=1: enable VDSO (default)
2315 vdso=0: disable VDSO mapping
2317 vdso32= [X86-32,X86-64]
2318 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2319 vdso32=1: enable 32-bit VDSO (default)
2320 vdso32=0: disable 32-bit VDSO mapping
2323 vector=percpu: enable percpu vector domain
2325 video= [FB] Frame buffer configuration
2326 See Documentation/fb/modedb.txt.
2328 vga= [BOOT,X86-32] Select a particular video mode
2329 See Documentation/x86/i386/boot.txt and
2330 Documentation/svga.txt.
2331 Use vga=ask for menu.
2332 This is actually a boot loader parameter; the value is
2333 passed to the kernel using a special protocol.
2335 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2336 size of <nn>. This can be used to increase the
2337 minimum size (128MB on x86). It can also be used to
2338 decrease the size and leave more room for directly
2341 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2344 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2347 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2350 waveartist= [HW,OSS]
2351 Format: <io>,<irq>,<dma>,<dma2>
2354 See header of drivers/scsi/wd33c93.c.
2357 See header of drivers/scsi/wd7000.c.
2360 See Documentation/watchdog/wdt.txt.
2362 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2363 xd_geo= See header of drivers/block/xd.c.
2365 xirc2ps_cs= [NET,PCMCIA]
2367 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2369 norandmaps Don't use address space randomization
2370 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2372 ______________________________________________________________________
2376 Add documentation for ALSA options.
2377 Add more DRM drivers.