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 FTRACE Function tracing enabled.
93 TS Appropriate touchscreen support is enabled.
94 UMS USB Mass Storage support is enabled.
95 USB USB support is enabled.
96 USBHID USB Human Interface Device support is enabled.
97 V4L Video For Linux support is enabled.
98 VGA The VGA console has been enabled.
99 VT Virtual terminal support is enabled.
100 WDT Watchdog support is enabled.
101 XT IBM PC/XT MFM hard disk support is enabled.
102 X86-32 X86-32, aka i386 architecture is enabled.
103 X86-64 X86-64 architecture is enabled.
104 More X86-64 boot options can be found in
105 Documentation/x86/x86_64/boot-options.txt .
106 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
108 In addition, the following text indicates that the option:
110 BUGS= Relates to possible processor bugs on the said processor.
111 KNL Is a kernel start-up parameter.
112 BOOT Is a boot loader parameter.
114 Parameters denoted with BOOT are actually interpreted by the boot
115 loader, and have no meaning to the kernel directly.
116 Do not modify the syntax of boot loader parameters without extreme
117 need or coordination with <Documentation/x86/i386/boot.txt>.
119 There are also arch-specific kernel-parameters not documented here.
120 See for example <Documentation/x86/x86_64/boot-options.txt>.
122 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
123 a trailing = on the name of any parameter states that that parameter will
124 be entered as an environment variable, whereas its absence indicates that
125 it will appear as a kernel argument readable via /proc/cmdline by programs
126 running once the system is up.
128 The number of kernel parameters is not limited, but the length of the
129 complete command line (parameters including spaces etc.) is limited to
130 a fixed number of characters. This limit depends on the architecture
131 and is between 256 and 4096 characters. It is defined in the file
132 ./include/asm/setup.h as COMMAND_LINE_SIZE.
135 acpi= [HW,ACPI,X86-64,i386]
136 Advanced Configuration and Power Interface
137 Format: { force | off | ht | strict | noirq }
138 force -- enable ACPI if default was off
139 off -- disable ACPI if default was on
140 noirq -- do not use ACPI for IRQ routing
141 ht -- run only enough ACPI to enable Hyper Threading
142 strict -- Be less tolerant of platforms that are not
143 strictly ACPI specification compliant.
145 See also Documentation/power/pm.txt, pci=noacpi
147 acpi_apic_instance= [ACPI, IOAPIC]
149 2: use 2nd APIC table, if available
150 1,0: use 1st APIC table
153 acpi_sleep= [HW,ACPI] Sleep options
154 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
155 See Documentation/power/video.txt for s3_bios and s3_mode.
156 s3_beep is for debugging; it makes the PC's speaker beep
157 as soon as the kernel's real-mode entry point is called.
158 s4_nohwsig prevents ACPI hardware signature from being
159 used during resume from hibernation.
160 old_ordering causes the ACPI 1.0 ordering of the _PTS
161 control method, wrt putting devices into low power
162 states, to be enforced (the ACPI 2.0 ordering of _PTS is
165 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
166 Format: { level | edge | high | low }
168 acpi_irq_balance [HW,ACPI]
169 ACPI will balance active IRQs
172 acpi_irq_nobalance [HW,ACPI]
173 ACPI will not move active IRQs (default)
176 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
178 Format: <irq>,<irq>...
180 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
181 Format: <irq>,<irq>...
183 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
185 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
186 Format: To spoof as Windows 98: ="Microsoft Windows"
188 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
189 acpi_osi="string1" # add string1 -- only one string
190 acpi_osi="!string2" # remove built-in string2
191 acpi_osi= # disable all strings
193 acpi_serialize [HW,ACPI] force serialization of AML methods
195 acpi_skip_timer_override [HW,ACPI]
196 Recognize and ignore IRQ0/pin2 Interrupt Override.
197 For broken nForce2 BIOS resulting in XT-PIC timer.
198 acpi_use_timer_override [HW,ACPI}
199 Use timer override. For some broken Nvidia NF5 boards
200 that require a timer override, but don't have
203 acpi_backlight= [HW,ACPI]
204 acpi_backlight=vendor
206 If set to vendor, prefer vendor specific driver
207 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
208 of the ACPI video.ko driver.
210 acpi_display_output= [HW,ACPI]
211 acpi_display_output=vendor
212 acpi_display_output=video
215 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
216 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
218 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
219 debug output. Bits in debug_layer correspond to a
220 _COMPONENT in an ACPI source file, e.g.,
221 #define _COMPONENT ACPI_PCI_COMPONENT
222 Bits in debug_level correspond to a level in
223 ACPI_DEBUG_PRINT statements, e.g.,
224 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
225 The debug_level mask defaults to "info". See
226 Documentation/acpi/debug.txt for more information about
227 debug layers and levels.
229 Enable processor driver info messages:
230 acpi.debug_layer=0x20000000
231 Enable PCI/PCI interrupt routing info messages:
232 acpi.debug_layer=0x400000
233 Enable AML "Debug" output, i.e., stores to the Debug
234 object while interpreting AML:
235 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
236 Enable all messages related to ACPI hardware:
237 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
239 Some values produce so much output that the system is
240 unusable. The "log_buf_len" parameter may be useful
241 if you need to capture more output.
243 acpi.power_nocheck= [HW,ACPI]
244 Format: 1/0 enable/disable the check of power state.
245 On some bogus BIOS the _PSC object/_STA object of
246 power resource can't return the correct device power
247 state. In such case it is unneccessary to check its
248 power state again in power transition.
249 1 : disable the power state check
251 acpi_pm_good [X86-32,X86-64]
252 Override the pmtimer bug detection: force the kernel
253 to assume that this machine's pmtimer latches its value
254 and always returns good values.
257 { off | try_unsupported }
258 off: disable AGP support
259 try_unsupported: try to drive unsupported chipsets
260 (may crash computer or cause data corruption)
262 enable_timer_pin_1 [i386,x86-64]
263 Enable PIN 1 of APIC timer
264 Can be useful to work around chipset bugs
265 (in particular on some ATI chipsets).
266 The kernel tries to set a reasonable default.
268 disable_timer_pin_1 [i386,x86-64]
269 Disable PIN 1 of APIC timer
270 Can be useful to work around chipset bugs.
273 Format: <io>,<irq>,<dma>,<dma2>,<type>
276 See header of drivers/scsi/advansys.c.
278 advwdt= [HW,WDT] Advantech WDT
279 Format: <iostart>,<iostop>
281 aedsp16= [HW,OSS] Audio Excel DSP 16
282 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
283 See also header of sound/oss/aedsp16.c.
286 See Documentation/scsi/aha152x.txt.
289 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
292 See Documentation/scsi/aic7xxx.txt.
295 See Documentation/scsi/aic79xx.txt.
297 amd_iommu= [HW,X86-84]
298 Pass parameters to the AMD IOMMU driver in the system.
300 isolate - enable device isolation (each device, as far
301 as possible, will get its own protection
303 share - put every device behind one IOMMU into the
304 same protection domain
305 fullflush - enable flushing of IO/TLB entries when
306 they are unmapped. Otherwise they are
307 flushed before they will be reused, which
310 amd_iommu_size= [HW,X86-64]
311 Define the size of the aperture for the AMD IOMMU
312 driver. Possible values are:
313 '32M', '64M' (default), '128M', '256M', '512M', '1G'
315 amijoy.map= [HW,JOY] Amiga joystick support
316 Map of devices attached to JOY0DAT and JOY1DAT
318 See also Documentation/kernel/input/joystick.txt
320 analog.map= [HW,JOY] Analog joystick and gamepad support
321 Specifies type or capabilities of an analog joystick
322 connected to one of 16 gameports
323 Format: <type1>,<type2>,..<type16>
326 Power management functions (SPARCstation-4/5 + deriv.)
328 Disable APC CPU standby support. SPARCstation-Fox does
329 not play well with APC CPU idle - disable it if you have
330 APC and your system crashes randomly.
332 apic= [APIC,i386] Advanced Programmable Interrupt Controller
333 Change the output verbosity whilst booting
334 Format: { quiet (default) | verbose | debug }
335 Change the amount of debugging information output
336 when initialising the APIC and IO-APIC components.
338 apm= [APM] Advanced Power Management
339 See header of arch/x86/kernel/apm_32.c.
341 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
342 Format: <io>,<irq>,<nodeID>
346 atarimouse= [HW,MOUSE] Atari Mouse
348 atascsi= [HW,SCSI] Atari SCSI
350 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
351 EzKey and similar keyboards
353 atkbd.reset= [HW] Reset keyboard during initialization
355 atkbd.set= [HW] Select keyboard code set
356 Format: <int> (2 = AT (default), 3 = PS/2)
358 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
361 atkbd.softraw= [HW] Choose between synthetic and real raw mode
362 Format: <bool> (0 = real, 1 = synthetic (default))
364 atkbd.softrepeat= [HW]
365 Use software keyboard repeat
369 baycom_epp= [HW,AX25]
372 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
374 See header of drivers/net/hamradio/baycom_par.c.
376 baycom_ser_fdx= [HW,AX25]
377 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
378 Format: <io>,<irq>,<mode>[,<baud>]
379 See header of drivers/net/hamradio/baycom_ser_fdx.c.
381 baycom_ser_hdx= [HW,AX25]
382 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
383 Format: <io>,<irq>,<mode>
384 See header of drivers/net/hamradio/baycom_ser_hdx.c.
386 boot_delay= Milliseconds to delay each printk during boot.
387 Values larger than 10 seconds (10000) are changed to
391 bootmem_debug [KNL] Enable bootmem allocator debug messages.
393 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
394 bttv.radio= Most important insmod options are available as
396 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
397 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
400 See drivers/scsi/BusLogic.c, comment before function
401 BusLogic_ParseDriverOptions().
403 c101= [NET] Moxa C101 synchronous serial card
405 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
406 Sometimes CPU hardware bugs make them report the cache
407 size incorrectly. The kernel will attempt work arounds
408 to fix known problems, but for some CPUs it is not
409 possible to determine what the correct size should be.
410 This option provides an override for these situations.
412 security= [SECURITY] Choose a security module to enable at boot.
413 If this boot parameter is not specified, only the first
414 security module asking for security registration will be
415 loaded. An invalid security module name will be treated
416 as if no module has been chosen.
419 [SECURITY] Disable capabilities. This would normally
420 be used only if an alternative security model is to be
421 configured. Potentially dangerous and should only be
422 used if you are entirely sure of the consequences.
424 ccw_timeout_log [S390]
425 See Documentation/s390/CommonIO for details.
427 cgroup_disable= [KNL] Disable a particular controller
428 Format: {name of the controller(s) to disable}
429 {Currently supported controllers - "memory"}
431 checkreqprot [SELINUX] Set initial checkreqprot flag value.
432 Format: { "0" | "1" }
433 See security/selinux/Kconfig help text.
434 0 -- check protection applied by kernel (includes
435 any implied execute protection).
436 1 -- check protection requested by application.
437 Default value is set via a kernel config option.
438 Value can be changed at runtime via
439 /selinux/checkreqprot.
442 See Documentation/s390/CommonIO for details.
444 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
446 Forces specified clocksource (if available) to be used
447 when calculating gettimeofday(). If specified
448 clocksource is not available, it defaults to PIT.
449 Format: { pit | tsc | cyclone | pmtmr }
451 clocksource= [GENERIC_TIME] Override the default clocksource
453 Override the default clocksource and use the clocksource
454 with the name specified.
455 Some clocksource names to choose from, depending on
457 [all] jiffies (this is the base, fallback clocksource)
459 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
460 pxa_timer,timer3,32k_counter,timer0_1
462 [X86-32] pit,hpet,tsc,vmi-timer;
463 scx200_hrt on Geode; cyclone on IBM x440
471 clearcpuid=BITNUM [X86]
472 Disable CPUID feature X for the kernel. See
473 arch/x86/include/asm/cpufeature.h for the valid bit
474 numbers. Note the Linux specific bits are not necessarily
475 stable over kernel options, but the vendor specific
477 Also note that user programs calling CPUID directly
478 or using the feature without checking anything
479 will still see it. This just prevents it from
480 being used by the kernel or shown in /proc/cpuinfo.
481 Also note the kernel might malfunction if you disable
484 code_bytes [IA32/X86_64] How many bytes of object code to print
489 hpet= [X86-32,HPET] option to control HPET usage
490 Format: { enable (default) | disable | force }
491 disable: disable HPET and use PIT instead
492 force: allow force enabled of undocumented chips (ICH4,
495 com20020= [HW,NET] ARCnet - COM20020 chipset
497 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
499 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
503 ARCnet - COM90xx chipset (memory-mapped buffers)
504 Format: <io>[,<irq>[,<memstart>]]
506 condev= [HW,S390] console device
509 console= [KNL] Output console device and options.
511 tty<n> Use the virtual console device <n>.
515 Use the specified serial port. The options are of
516 the form "bbbbpnf", where "bbbb" is the baud rate,
517 "p" is parity ("n", "o", or "e"), "n" is number of
518 bits, and "f" is flow control ("r" for RTS or
519 omit it). Default is "9600n8".
521 See Documentation/serial-console.txt for more
523 Documentation/networking/netconsole.txt for an
526 uart[8250],io,<addr>[,options]
527 uart[8250],mmio,<addr>[,options]
528 Start an early, polled-mode console on the 8250/16550
529 UART at the specified I/O port or MMIO address,
530 switching to the matching ttyS device later. The
531 options are the same as for ttyS, above.
533 If the device connected to the port is not a TTY but a braille
534 device, prepend "brl," before the device type, for instance
536 For now, only VisioBraille is supported.
538 earlycon= [KNL] Output early console device and options.
539 uart[8250],io,<addr>[,options]
540 uart[8250],mmio,<addr>[,options]
541 Start an early, polled-mode console on the 8250/16550
542 UART at the specified I/O port or MMIO address.
543 The options are the same as for ttyS, above.
546 [HW] Never suspend the console
547 Disable suspending of consoles during suspend and
548 hibernate operations. Once disabled, debugging
549 messages can reach various consoles while the rest
550 of the system is being put to sleep (ie, while
551 debugging driver suspend/resume hooks). This may
552 not work reliably with all consoles, but is known
553 to work with serial and VGA consoles.
556 [KNL] Change the default value for
557 /proc/<pid>/coredump_filter.
558 See also Documentation/filesystems/proc.txt.
560 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
562 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
564 crashkernel=nn[KMG]@ss[KMG]
565 [KNL] Reserve a chunk of physical memory to
566 hold a kernel to switch to with kexec on panic.
568 crashkernel=range1:size1[,range2:size2,...][@offset]
569 [KNL] Same as above, but depends on the memory
570 in the running system. The syntax of range is
571 start-[end] where start and end are both
572 a memory unit (amount[KMG]). See also
573 Documentation/kdump/kdump.txt for a example.
576 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
581 cs89x0_media= [HW,NET]
582 Format: { rj45 | aui | bnc }
585 See header of drivers/s390/block/dasd_devmap.c.
587 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
588 (one device per port)
589 Format: <port#>,<type>
590 See also Documentation/input/joystick-parport.txt
592 debug [KNL] Enable kernel debugging (events log level).
595 [KNL] verbose self-tests
597 Print debugging info while doing the locking API
599 We default to 0 (no extra messages), setting it to
600 1 will print _a lot_ more information - normally
601 only useful to kernel developers.
603 debug_objects [KNL] Enable object debugging
605 debugpat [X86] Enable PAT debugging
607 decnet.addr= [HW,NET]
608 Format: <area>[,<node>]
609 See also Documentation/networking/decnet.txt.
612 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
613 Change the default blue palette of the console.
614 This is a 16-member array composed of values
618 Format: <green0>,<green1>,<green2>,...,<green15>
619 Change the default green palette of the console.
620 This is a 16-member array composed of values
624 Format: <red0>,<red1>,<red2>,...,<red15>
625 Change the default red palette of the console.
626 This is a 16-member array composed of values
632 Set system-wide default UTF-8 mode for all tty's.
633 Default is 1, i.e. UTF-8 mode is enabled for all
634 newly opened terminals.
637 Set number of hash buckets for dentry cache.
640 IO parameters + enable/disable command.
642 digiepca= [HW,SERIAL]
643 See drivers/char/README.epca and
644 Documentation/serial/digiepca.txt.
646 disable_mtrr_cleanup [X86]
647 enable_mtrr_cleanup [X86]
648 The kernel tries to adjust MTRR layout from continuous
649 to discrete, to make X server driver able to add WB
650 entry later. This parameter enables/disables that.
652 mtrr_chunk_size=nn[KMG] [X86]
653 used for mtrr cleanup. It is largest continous chunk
654 that could hold holes aka. UC entries.
656 mtrr_gran_size=nn[KMG] [X86]
657 Used for mtrr cleanup. It is granularity of mtrr block.
659 Large value could prevent small alignment from
662 mtrr_spare_reg_nr=n [X86]
664 Range: 0,7 : spare reg number
666 Used for mtrr cleanup. It is spare mtrr entries number.
667 Set to 2 or more if your graphical card needs more.
669 disable_mtrr_trim [X86, Intel and AMD only]
670 By default the kernel will trim any uncacheable
671 memory out of your available memory pool based on
672 MTRR settings. This parameter disables that behavior,
673 possibly causing your machine to run very slowly.
675 dmasound= [HW,OSS] Sound subsystem buffers
681 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
683 earlyprintk=serial[,ttySn[,baudrate]]
686 Append ",keep" to not disable it when the real console
689 Only vga or serial or usb debug port at a time.
691 Currently only ttyS0 and ttyS1 are supported.
693 Interaction with the standard serial driver is not
696 The VGA output is eventually overwritten by the real
702 Format: {"off" | "on" | "skip[mbr]"}
704 eisa_irq_edge= [PARISC,HW]
705 See header of drivers/parisc/eisa.c.
708 See comment before function elanfreq_setup() in
709 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
712 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
713 See Documentation/block/as-iosched.txt and
714 Documentation/block/deadline-iosched.txt for details.
716 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
717 Specifies physical address of start of kernel core
718 image elf header. Generally kexec loader will
719 pass this option to capture kernel.
720 See Documentation/kdump/kdump.txt for details.
722 enforcing [SELINUX] Set initial enforcing status.
724 See security/selinux/Kconfig help text.
725 0 -- permissive (log only, no denials).
726 1 -- enforcing (deny and log).
728 Value can be changed at runtime via /selinux/enforce.
731 Format: <spdif>,[<nomix>,[<amplifier>]]
732 See also header of sound/oss/es1371.c.
734 ether= [HW,NET] Ethernet cards parameters
735 This option is obsoleted by the "netdev=" option, which
736 has equivalent usage. See its documentation for details.
738 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
743 fail_make_request=[KNL]
744 General fault injection mechanism.
745 Format: <interval>,<probability>,<space>,<times>
746 See also /Documentation/fault-injection/.
749 See header of drivers/scsi/fd_mcs.c.
752 See header of drivers/scsi/fdomain.c.
755 See Documentation/blockdev/floppy.txt.
757 force_pal_cache_flush
758 [IA-64] Avoid check_sal_cache_flush which may hang on
759 buggy SAL_CACHE_FLUSH implementations. Using this
760 parameter will force ia64_sal_cache_flush to call
761 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
764 [ftrace] will set and start the specified tracer
765 as early as possible in order to facilitate early
769 [ftrace] will dump the trace buffers on oops.
772 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
773 support via parallel port (up to 5 devices per port)
774 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
775 See also Documentation/input/joystick-parport.txt
779 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
784 See header of drivers/scsi/gdth.c.
786 gpt [EFI] Forces disk with valid GPT signature but
787 invalid Protective MBR to be treated as GPT.
791 hashdist= [KNL,NUMA] Large hashes allocated during boot
792 are distributed across NUMA nodes. Defaults on
793 for IA-64, off otherwise.
794 Format: 0 | 1 (for off | on)
796 hcl= [IA-64] SGI's Hardware Graph compatibility layer
798 hd= [EIDE] (E)IDE hard drive subsystem geometry
799 Format: <cyl>,<head>,<sect>
801 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
802 size of <nn>. This works even on boxes that have no
803 highmem otherwise. This also works to reduce highmem
804 size on bigger boxes.
806 highres= [KNL] Enable/disable high resolution timer mode.
807 Valid parameters: "on", "off"
811 See Documentation/isdn/README.HiSax.
813 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
814 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
815 On x86-64 and powerpc, this option can be specified
816 multiple times interleaved with hugepages= to reserve
817 huge pages of different sizes. Valid pages sizes on
818 x86-64 are 2M (when the CPU supports "pse") and 1G
819 (when the CPU supports the "pdpe1gb" cpuinfo flag)
820 Note that 1GB pages can only be allocated at boot time
821 using hugepages= and not freed afterwards.
823 [same as hugepagesz=] The size of the default
824 HugeTLB page size. This is the size represented by
825 the legacy /proc/ hugepages APIs, used for SHM, and
826 default size when mounting hugetlbfs filesystems.
827 Defaults to the default architecture's huge page size
832 hvc_iucv= [S390] Number of z/VM IUCV Hypervisor console (HVC)
833 back-ends. Valid parameters: 0..8
835 i8042.debug [HW] Toggle i8042 debug mode
836 i8042.direct [HW] Put keyboard port into non-translated mode
837 i8042.dumbkbd [HW] Pretend that controller can only read data from
838 keyboard and cannot control its state
839 (Don't attempt to blink the leds)
840 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
841 i8042.nokbd [HW] Don't check/create keyboard port
842 i8042.noloop [HW] Disable the AUX Loopback command while probing
844 i8042.nomux [HW] Don't check presence of an active multiplexing
846 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
849 [HW] Frequency with which keyboard LEDs should blink
850 when kernel panics (default is 0.5 sec)
851 i8042.reset [HW] Reset the controller during init and cleanup
852 i8042.unlock [HW] Unlock (ignore) the keylock
856 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
857 indicates that the driver is running on unsupported
859 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
860 does not match list of supported models.
862 [HW] Report power status in /proc/i8k
863 (disabled by default)
864 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
867 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
868 See Documentation/mca.txt.
871 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
873 ide= [HW] (E)IDE subsystem
874 Format: ide=nodma or ide=doubler
875 See Documentation/ide/ide.txt.
877 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
878 See Documentation/ide/ide.txt.
881 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
882 Poll forces a polling idle loop that can slightly improves the performance
883 of waking up a idle CPU, but will use a lot of power and make the system
884 run hot. Not recommended.
885 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
886 to not use it because it doesn't save as much power as a normal idle
887 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
889 idle=halt. Halt is forced to be used for CPU idle.
890 In such case C2/C3 won't be used again.
891 idle=nomwait. Disable mwait for CPU C-states
893 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
894 Claim all unknown PCI IDE storage controllers.
896 ignore_loglevel [KNL]
897 Ignore loglevel setting - this will print /all/
898 kernel messages to the console. Useful for debugging.
901 Set number of hash buckets for inode cache.
904 See header of drivers/scsi/in2000.c.
908 Run specified binary instead of /sbin/init as init
911 initcall_debug [KNL] Trace initcalls as they are executed. Useful
912 for working out where the kernel is dying during
915 initrd= [BOOT] Specify the location of the initial ramdisk
917 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
922 iomem= Disable strict checking of access to MMIO memory
923 strict regions from userspace.
939 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
941 Disable intel iommu driver.
942 igfx_off [Default Off]
943 By default, gfx is mapped as normal device. If a gfx
944 device has a dedicated DMAR unit, the DMAR unit is
945 bypassed by not enabling DMAR with this option. In
946 this case, gfx device will use physical address for
949 With this option iommu will not optimize to look
950 for io virtual address below 32 bit forcing dual
951 address cycle on pci bus for cards supporting greater
952 than 32 bit addressing. The default is to look
953 for translation below 32 bit and if not available
954 then look in the higher range.
956 With this option on every unmap_single operation will
957 result in a hardware IOTLB flush operation as opposed
958 to batching them for performance.
960 io_delay= [X86-32,X86-64] I/O delay method
962 Standard port 0x80 based delay
964 Alternate port 0xed based delay (needed on some systems)
966 Simple two microseconds delay
970 io7= [HW] IO7 for Marvel based alpha systems
971 See comment before marvel_specify_io7 in
972 arch/alpha/kernel/core_marvel.c.
975 See Documentation/filesystems/nfsroot.txt.
977 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
978 See comment before ip2_setup() in
979 drivers/char/ip2/ip2base.c.
981 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
982 See header of drivers/scsi/ips.c.
984 ports= [IP_VS_FTP] IPVS ftp helper module
986 Up to 8 (IP_VS_APP_MAX_PORTS) ports
988 Format: <port>,<port>....
991 When an interrupt is not handled search all handlers
992 for it. Intended to get systems with badly broken
996 When an interrupt is not handled search all handlers
997 for it. Also check all handlers each timer
998 interrupt. Intended to get systems with badly broken
1002 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1004 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1006 <cpu number>,...,<cpu number>
1008 <cpu number>-<cpu number>
1009 (must be a positive range in ascending order)
1011 <cpu number>,...,<cpu number>-<cpu number>
1013 This option can be used to specify one or more CPUs
1014 to isolate from the general SMP balancing and scheduling
1015 algorithms. You can move a process onto or off an
1016 "isolated" CPU via the CPU affinity syscalls or cpuset.
1017 <cpu number> begins at 0 and the maximum value is
1018 "number of CPUs in system - 1".
1020 This option is the preferred way to isolate CPUs. The
1021 alternative -- manually setting the CPU mask of all
1022 tasks in the system -- can cause problems and
1023 suboptimal load balancer performance.
1027 js= [HW,JOY] Analog joystick
1028 See Documentation/input/joystick.txt.
1030 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1031 specifies the amount of memory usable by the kernel
1032 for non-movable allocations. The requested amount is
1033 spread evenly throughout all nodes in the system. The
1034 remaining memory in each node is used for Movable
1035 pages. In the event, a node is too small to have both
1036 kernelcore and Movable pages, kernelcore pages will
1037 take priority and other nodes will have a larger number
1038 of kernelcore pages. The Movable zone is used for the
1039 allocation of pages that may be reclaimed or moved
1040 by the page migration subsystem. This means that
1041 HugeTLB pages may not be allocated from this zone.
1042 Note that allocations like PTEs-from-HighMem still
1043 use the HighMem zone if it exists, and the Normal
1044 zone if it does not.
1046 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1047 is similar to kernelcore except it specifies the
1048 amount of memory used for migratable allocations.
1049 If both kernelcore and movablecore is specified,
1050 then kernelcore will be at *least* the specified
1051 value but may be more. If movablecore on its own
1052 is specified, the administrator must be careful
1053 that the amount of memory usable for all allocations
1058 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1061 kgdboc= [HW] kgdb over consoles.
1062 Requires a tty driver that supports console polling.
1063 (only serial suported for now)
1064 Format: <serial_device>[,baud]
1066 kmac= [MIPS] korina ethernet MAC address.
1067 Configure the RouterBoard 532 series on-chip
1068 Ethernet adapter MAC address.
1074 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1077 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1080 libata.dma= [LIBATA] DMA control
1081 libata.dma=0 Disable all PATA and SATA DMA
1082 libata.dma=1 PATA and SATA Disk DMA only
1083 libata.dma=2 ATAPI (CDROM) DMA only
1084 libata.dma=4 Compact Flash DMA only
1085 Combinations also work, so libata.dma=3 enables DMA
1086 for disks and CDROMs, but not CFs.
1088 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1092 libata.force= [LIBATA] Force configurations. The format is comma
1093 separated list of "[ID:]VAL" where ID is
1094 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1095 matching port, link or device. Basically, it matches
1096 the ATA ID string printed on console by libata. If
1097 the whole ID part is omitted, the last PORT and DEVICE
1098 values are used. If ID hasn't been specified yet, the
1099 configuration applies to all ports, links and devices.
1101 If only DEVICE is omitted, the parameter applies to
1102 the port and all links and devices behind it. DEVICE
1103 number of 0 either selects the first device or the
1104 first fan-out link behind PMP device. It does not
1105 select the host link. DEVICE number of 15 selects the
1106 host link and device attached to it.
1108 The VAL specifies the configuration to force. As long
1109 as there's no ambiguity shortcut notation is allowed.
1110 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1111 The following configurations can be forced.
1113 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1114 Any ID with matching PORT is used.
1116 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1118 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1119 udma[/][16,25,33,44,66,100,133] notation is also
1122 * [no]ncq: Turn on or off NCQ.
1124 * nohrst, nosrst, norst: suppress hard, soft
1127 If there are multiple matching configurations changing
1128 the same attribute, the last one is used.
1130 lmb=debug [KNL] Enable lmb debug messages.
1132 load_ramdisk= [RAM] List of ramdisks to load from floppy
1133 See Documentation/blockdev/ramdisk.txt.
1135 lockd.nlm_grace_period=P [NFS] Assign grace period.
1138 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1141 lockd.nlm_timeout=T [NFS] Assign timeout value.
1144 lockd.nlm_udpport=M [NFS] Assign UDP port.
1147 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1150 loglevel= All Kernel Messages with a loglevel smaller than the
1151 console loglevel will be printed to the console. It can
1152 also be changed with klogd or other programs. The
1153 loglevels are defined as follows:
1155 0 (KERN_EMERG) system is unusable
1156 1 (KERN_ALERT) action must be taken immediately
1157 2 (KERN_CRIT) critical conditions
1158 3 (KERN_ERR) error conditions
1159 4 (KERN_WARNING) warning conditions
1160 5 (KERN_NOTICE) normal but significant condition
1161 6 (KERN_INFO) informational
1162 7 (KERN_DEBUG) debug-level messages
1164 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1165 Format: { n | nk | nM }
1166 n must be a power of two. The default size
1167 is set in the kernel config file.
1169 logo.nologo [FB] Disables display of the built-in Linux logo.
1170 This may be used to provide more screen space for
1171 kernel log messages and is useful when debugging
1172 kernel boot problems.
1174 lp=0 [LP] Specify parallel ports to use, e.g,
1175 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1176 lp=reset first parallel port). 'lp=0' disables the
1177 lp=auto printer driver. 'lp=reset' (which can be
1178 specified in addition to the ports) causes
1179 attached printers to be reset. Using
1180 lp=port1,port2,... specifies the parallel ports
1181 to associate lp devices with, starting with
1182 lp0. A port specification may be 'none' to skip
1183 that lp device, or a parport name such as
1184 'parport0'. Specifying 'lp=auto' instead of a
1185 port specification list means that device IDs
1186 from each port should be examined, to see if
1187 an IEEE 1284-compliant printer is attached; if
1188 so, the driver will manage that printer.
1189 See also header of drivers/char/lp.c.
1192 Sets loops_per_jiffy to given constant, thus avoiding
1193 time-consuming boot-time autodetection (up to 250 ms per
1194 CPU). 0 enables autodetection (default). To determine
1195 the correct value for your kernel, boot with normal
1196 autodetection and see what value is printed. Note that
1197 on SMP systems the preset will be applied to all CPUs,
1198 which is likely to cause problems if your CPUs need
1199 significantly divergent settings. An incorrect value
1200 will cause delays in the kernel to be wrong, leading to
1201 unpredictable I/O errors and other breakage. Although
1202 unlikely, in the extreme case this might damage your
1206 Format: <io>,<irq>,<dma>
1208 mac5380= [HW,SCSI] Format:
1209 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1211 machvec= [IA64] Force the use of a particular machine-vector
1212 (machvec) in a generic kernel.
1213 Example: machvec=hpzx1_swiotlb
1215 max_loop= [LOOP] Maximum number of loopback devices that can
1219 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1220 should make use of. maxcpus=n : n >= 0 limits the
1221 kernel to using 'n' processors. n=0 is a special case,
1222 it is equivalent to "nosmp", which also disables
1225 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1226 or equal to this physical address is ignored.
1228 max_luns= [SCSI] Maximum number of LUNs to probe.
1229 Should be between 1 and 2^32-1.
1232 [SCSI] Maximum number of LUNs received.
1233 Should be between 1 and 16384.
1237 mce [X86-32] Machine Check Exception
1239 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1241 md= [HW] RAID subsystems devices and level
1242 See Documentation/md.txt.
1245 Format: <first>,<last>
1246 Specifies range of consoles to be captured by the MDA.
1248 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1249 Amount of memory to be used when the kernel is not able
1250 to see the whole system memory or for test.
1251 [X86-32] Use together with memmap= to avoid physical
1252 address space collisions. Without memmap= PCI devices
1253 could be placed at addresses belonging to unused RAM.
1255 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1259 [KNL,SH] Allow user to override the default size for
1260 per-device physically contiguous DMA buffers.
1262 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1263 E820 memory map, as specified by the user.
1264 Such memmap=exactmap lines can be constructed based on
1265 BIOS output or other requirements. See the memmap=nn@ss
1268 memmap=nn[KMG]@ss[KMG]
1269 [KNL] Force usage of a specific region of memory
1270 Region of memory to be used, from ss to ss+nn.
1272 memmap=nn[KMG]#ss[KMG]
1273 [KNL,ACPI] Mark specific memory as ACPI data.
1274 Region of memory to be used, from ss to ss+nn.
1276 memmap=nn[KMG]$ss[KMG]
1277 [KNL,ACPI] Mark specific memory as reserved.
1278 Region of memory to be used, from ss to ss+nn.
1279 Example: Exclude memory from 0x18690000-0x1869ffff
1280 memmap=64K$0x18690000
1282 memmap=0x10000$0x18690000
1284 memory_corruption_check=0/1 [X86]
1285 Some BIOSes seem to corrupt the first 64k of
1286 memory when doing things like suspend/resume.
1287 Setting this option will scan the memory
1288 looking for corruption. Enabling this will
1289 both detect corruption and prevent the kernel
1290 from using the memory being corrupted.
1291 However, its intended as a diagnostic tool; if
1292 repeatable BIOS-originated corruption always
1293 affects the same memory, you can use memmap=
1294 to prevent the kernel from using that memory.
1296 memory_corruption_check_size=size [X86]
1297 By default it checks for corruption in the low
1298 64k, making this memory unavailable for normal
1299 use. Use this parameter to scan for
1300 corruption in more or less memory.
1302 memory_corruption_check_period=seconds [X86]
1303 By default it checks for corruption every 60
1304 seconds. Use this parameter to check at some
1305 other rate. 0 disables periodic checking.
1307 memtest= [KNL,X86] Enable memtest
1309 range: 0,4 : pattern number
1310 default : 0 <disable>
1312 meye.*= [HW] Set MotionEye Camera parameters
1313 See Documentation/video4linux/meye.txt.
1315 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1316 Multi-Function General Purpose Timers on AMD Geode
1319 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1320 the BIOS has incorrectly applied a workaround. TinyBIOS
1321 version 0.98 is known to be affected, 0.99 fixes the
1322 problem by letting the user disable the workaround.
1326 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1327 physical address is ignored.
1330 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1331 parameter allows control of the logging verbosity for
1332 the additional memory initialisation checks. A value
1333 of 0 disables mminit logging and a level of 4 will
1334 log everything. Information is printed at KERN_DEBUG
1335 so loglevel=8 may also need to be specified.
1338 [MOUSE] Maximum time between finger touching and
1339 leaving touchpad surface for touch to be considered
1340 a tap and be reported as a left button click (for
1341 touchpads working in absolute mode only).
1343 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1344 reporting absolute coordinates, such as tablets
1345 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1346 reporting absolute coordinates, such as tablets
1351 MTD_Partition= [MTD]
1352 Format: <name>,<region-number>,<size>,<offset>
1354 MTD_Region= [MTD] Format:
1355 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1358 See drivers/mtd/cmdlinepart.c.
1361 ARM/S3C2412 JIVE boot control
1363 See arch/arm/mach-s3c2412/mach-jive.c
1365 mtouchusb.raw_coordinates=
1366 [HW] Make the MicroTouch USB driver use raw coordinates
1367 ('y', default) or cooked coordinates ('n')
1369 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1372 See header of drivers/scsi/NCR_D700.c.
1376 ncr53c400= [HW,SCSI]
1378 ncr53c400a= [HW,SCSI]
1380 ncr53c406a= [HW,SCSI]
1382 ncr53c8xx= [HW,SCSI]
1384 netdev= [NET] Network devices parameters
1385 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1386 Note that mem_start is often overloaded to mean
1387 something different and driver-specific.
1388 This usage is only documented in each driver source
1392 [NETFILTER] Enable connection tracking flow accounting
1393 0 to disable accounting
1394 1 to enable accounting
1395 Default value depends on CONFIG_NF_CT_ACCT that is
1396 going to be removed in 2.6.29.
1399 See Documentation/filesystems/nfsroot.txt.
1401 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1402 See Documentation/filesystems/nfsroot.txt.
1404 nfs.callback_tcpport=
1405 [NFS] set the TCP port on which the NFSv4 callback
1406 channel should listen.
1408 nfs.idmap_cache_timeout=
1409 [NFS] set the maximum lifetime for idmapper cache
1413 [NFS] enable 64-bit inode numbers.
1414 If zero, the NFS client will fake up a 32-bit inode
1415 number for the readdir() and stat() syscalls instead
1416 of returning the full 64-bit number.
1417 The default is to return 64-bit inode numbers.
1419 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1420 when a NMI is triggered.
1421 Format: [state][,regs][,debounce][,die]
1423 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1424 Format: [panic,][num]
1426 0 - turn nmi_watchdog off
1427 1 - use the IO-APIC timer for the NMI watchdog
1428 2 - use the local APIC for the NMI watchdog using
1429 a performance counter. Note: This will use one performance
1430 counter and the local APIC's performance vector.
1431 When panic is specified panic when an NMI watchdog timeout occurs.
1432 This is useful when you use a panic=... timeout and need the box
1434 Instead of 1 and 2 it is possible to use the following
1435 symbolic names: lapic and ioapic
1436 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1438 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1439 emulation library even if a 387 maths coprocessor
1442 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1443 caches in the slab allocator. Saves per-node memory,
1444 but will impact performance.
1448 noapic [SMP,APIC] Tells the kernel to not make use of any
1449 IOAPICs that may be present in the system.
1451 nobats [PPC] Do not use BATs for mapping kernel lowmem
1452 on "Classic" PPC cores.
1456 nodelayacct [KNL] Disable per-task delay accounting
1458 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1460 nodsp [SH] Disable hardware DSP at boot time.
1462 noefi [X86-32,X86-64] Disable EFI runtime services support.
1466 noexec [X86-32,X86-64]
1467 On X86-32 available only on PAE configured kernels.
1468 noexec=on: enable non-executable mappings (default)
1469 noexec=off: disable non-executable mappings
1472 This affects only 32-bit executables.
1473 noexec32=on: enable non-executable mappings (default)
1474 read doesn't imply executable mappings
1475 noexec32=off: disable non-executable mappings
1476 read implies executable mappings
1478 nofpu [SH] Disable hardware FPU at boot time.
1480 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1481 register save and restore. The kernel will only save
1482 legacy floating-point registers on task switch.
1484 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1488 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1489 instruction doesn't work correctly and not to
1492 no_file_caps Tells the kernel not to honor file capabilities. The
1493 only way then for a file to be executed with privilege
1494 is to be setuid root or executed by root.
1496 nohalt [IA-64] Tells the kernel not to use the power saving
1497 function PAL_HALT_LIGHT when idle. This increases
1498 power-consumption. On the positive side, it reduces
1499 interrupt wake-up latency, which may improve performance
1500 in certain environments such as networked servers or
1503 nohz= [KNL] Boottime enable/disable dynamic ticks
1504 Valid arguments: on, off
1507 noirqdebug [X86-32] Disables the code which attempts to detect and
1508 disable unhandled interrupt sources.
1510 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1511 broken timer IRQ sources.
1513 noisapnp [ISAPNP] Disables ISA PnP code.
1515 noinitrd [RAM] Tells the kernel not to load any configured
1520 nojitter [IA64] Disables jitter checking for ITC timers.
1522 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1524 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1526 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1528 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1529 default x2apic cluster mode on platforms
1532 noltlbs [PPC] Do not use large page/tlb entries for kernel
1533 lowmem mapping on PPC40x.
1535 nomca [IA-64] Disable machine check abort handling
1537 nomce [X86-32] Machine Check Exception
1539 nomfgpt [X86-32] Disable Multi-Function General Purpose
1540 Timer usage (for AMD Geode machines).
1542 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1544 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1545 with UP alternatives
1547 noresidual [PPC] Don't use residual data on PReP machines.
1549 noresume [SWSUSP] Disables resume and restores original swap
1552 no-scroll [VGA] Disables scrollback.
1553 This is required for the Braillex ib80-piezo Braille
1554 reader made by F.H. Papenmeier (Germany).
1558 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1560 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1561 and disable the IO APIC. legacy for "maxcpus=0".
1563 nosoftlockup [KNL] Disable the soft-lockup detector.
1565 nosync [HW,M68K] Disables sync negotiation for all devices.
1567 notsc [BUGS=X86-32] Disable Time Stamp Counter
1569 nousb [USB] Disable the USB subsystem
1573 nptcg= [IA64] Override max number of concurrent global TLB
1574 purges which is reported from either PAL_VM_SUMMARY or
1577 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1578 one of ['zone', 'node', 'default'] can be specified
1579 This can be set from sysctl after boot.
1580 See Documentation/sysctl/vm.txt for details.
1582 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1584 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1585 See Documentation/debugging-via-ohci1394.txt for more
1588 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1589 Rather than timing out after 20 ms if an EC
1590 command is not properly ACKed, override the length
1591 of the timeout. We have interrupts disabled while
1592 waiting for the ACK, so if this is set too high
1593 interrupts *may* be lost!
1598 oprofile.timer= [HW]
1599 Use timer interrupt instead of performance counters
1601 osst= [HW,SCSI] SCSI Tape Driver
1602 Format: <buffer_size>,<write_threshold>
1603 See also Documentation/scsi/st.txt.
1605 panic= [KNL] Kernel behaviour on panic
1608 parkbd.port= [HW] Parallel port number the keyboard adapter is
1609 connected to, default is 0.
1611 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1612 0 for XT, 1 for AT (default is AT).
1615 parport= [HW,PPT] Specify parallel ports. 0 disables.
1616 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1617 Use 'auto' to force the driver to use any
1618 IRQ/DMA settings detected (the default is to
1619 ignore detected IRQ/DMA settings because of
1620 possible conflicts). You can specify the base
1621 address, IRQ, and DMA settings; IRQ and DMA
1622 should be numbers, or 'auto' (for using detected
1623 settings on that particular port), or 'nofifo'
1624 (to avoid using a FIFO even if it is detected).
1625 Parallel ports are assigned in the order they
1626 are specified on the command line, starting
1629 parport_init_mode= [HW,PPT]
1630 Configure VIA parallel port to operate in
1631 a specific mode. This is necessary on Pegasos
1632 computer where firmware has no options for setting
1633 up parallel port mode and sets it to spp.
1634 Currently this function knows 686a and 8231 chips.
1635 Format: [spp|ps2|epp|ecp|ecpepp]
1637 pas2= [HW,OSS] Format:
1638 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1641 See header of drivers/scsi/pas16.c.
1644 Halt all CPUs after the first oops has been printed for
1645 the specified number of seconds. This is to be used if
1646 your oopses keep scrolling off the screen.
1651 See header of drivers/block/paride/pcd.c.
1652 See also Documentation/blockdev/paride.txt.
1654 pci=option[,option...] [PCI] various PCI subsystem options:
1655 off [X86] don't probe for the PCI bus
1656 bios [X86-32] force use of PCI BIOS, don't access
1657 the hardware directly. Use this if your machine
1658 has a non-standard PCI host bridge.
1659 nobios [X86-32] disallow use of PCI BIOS, only direct
1660 hardware access methods are allowed. Use this
1661 if you experience crashes upon bootup and you
1662 suspect they are caused by the BIOS.
1663 conf1 [X86] Force use of PCI Configuration
1665 conf2 [X86] Force use of PCI Configuration
1667 noaer [PCIE] If the PCIEAER kernel config parameter is
1668 enabled, this kernel boot option can be used to
1669 disable the use of PCIE advanced error reporting.
1670 nodomains [PCI] Disable support for multiple PCI
1671 root domains (aka PCI segments, in ACPI-speak).
1672 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1674 nomsi [MSI] If the PCI_MSI kernel config parameter is
1675 enabled, this kernel boot option can be used to
1676 disable the use of MSI interrupts system-wide.
1677 noioapicquirk [APIC] Disable all boot interrupt quirks.
1678 Safety option to keep boot IRQs enabled. This
1679 should never be necessary.
1680 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1681 primary IO-APIC for bridges that cannot disable
1682 boot IRQs. This fixes a source of spurious IRQs
1683 when the system masks IRQs.
1684 noioapicreroute [APIC] Disable workaround that uses the
1685 boot IRQ equivalent of an IRQ that connects to
1686 a chipset where boot IRQs cannot be disabled.
1687 The opposite of ioapicreroute.
1688 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1689 routing table. These calls are known to be buggy
1690 on several machines and they hang the machine
1691 when used, but on other computers it's the only
1692 way to get the interrupt routing table. Try
1693 this option if the kernel is unable to allocate
1694 IRQs or discover secondary PCI buses on your
1696 rom [X86] Assign address space to expansion ROMs.
1697 Use with caution as certain devices share
1698 address decoders between ROMs and other
1700 norom [X86] Do not assign address space to
1701 expansion ROMs that do not already have
1702 BIOS assigned address ranges.
1703 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1704 assigned automatically to PCI devices. You can
1705 make the kernel exclude IRQs of your ISA cards
1707 pirqaddr=0xAAAAA [X86] Specify the physical address
1708 of the PIRQ table (normally generated
1709 by the BIOS) if it is outside the
1710 F0000h-100000h range.
1711 lastbus=N [X86] Scan all buses thru bus #N. Can be
1712 useful if the kernel is unable to find your
1713 secondary buses and you want to tell it
1714 explicitly which ones they are.
1715 assign-busses [X86] Always assign all PCI bus
1716 numbers ourselves, overriding
1717 whatever the firmware may have done.
1718 usepirqmask [X86] Honor the possible IRQ mask stored
1719 in the BIOS $PIR table. This is needed on
1720 some systems with broken BIOSes, notably
1721 some HP Pavilion N5400 and Omnibook XE3
1722 notebooks. This will have no effect if ACPI
1723 IRQ routing is enabled.
1724 noacpi [X86] Do not use ACPI for IRQ routing
1725 or for PCI scanning.
1726 use_crs [X86] Use _CRS for PCI resource
1728 routeirq Do IRQ routing for all PCI devices.
1729 This is normally done in pci_enable_device(),
1730 so this option is a temporary workaround
1731 for broken drivers that don't call it.
1732 skip_isa_align [X86] do not align io start addr, so can
1733 handle more pci cards
1734 firmware [ARM] Do not re-enumerate the bus but instead
1735 just use the configuration from the
1736 bootloader. This is currently used on
1737 IXP2000 systems where the bus has to be
1738 configured a certain way for adjunct CPUs.
1739 noearly [X86] Don't do any early type 1 scanning.
1740 This might help on some broken boards which
1741 machine check when some devices' config space
1742 is read. But various workarounds are disabled
1743 and some IOMMU drivers will not work.
1744 bfsort Sort PCI devices into breadth-first order.
1745 This sorting is done to get a device
1746 order compatible with older (<= 2.4) kernels.
1747 nobfsort Don't sort PCI devices into breadth-first order.
1748 cbiosize=nn[KMG] The fixed amount of bus space which is
1749 reserved for the CardBus bridge's IO window.
1750 The default value is 256 bytes.
1751 cbmemsize=nn[KMG] The fixed amount of bus space which is
1752 reserved for the CardBus bridge's memory
1753 window. The default value is 64 megabytes.
1755 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1758 force Enable ASPM even on devices that claim not to support it.
1759 WARNING: Forcing ASPM on may cause system lockups.
1761 pcmv= [HW,PCMCIA] BadgePAD 4
1764 See Documentation/blockdev/paride.txt.
1766 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1769 See arch/parisc/kernel/pdc_chassis.c
1772 See Documentation/blockdev/paride.txt.
1775 See Documentation/blockdev/paride.txt.
1777 pirq= [SMP,APIC] Manual mp-table setup
1778 See Documentation/x86/i386/IO-APIC.txt.
1780 plip= [PPT,NET] Parallel port network link
1781 Format: { parport<nr> | timid | 0 }
1782 See also Documentation/parport.txt.
1784 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1785 Override pmtimer IOPort with a hex value.
1789 Enable PNP debug messages. This depends on the
1790 CONFIG_PNP_DEBUG_MESSAGES option.
1796 { on | off | curr | res | no-curr | no-res }
1799 [ISAPNP] Exclude IRQs for the autoconfiguration
1802 [ISAPNP] Exclude DMAs for the autoconfiguration
1804 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1805 Ranges are in pairs (I/O port base and size).
1808 [ISAPNP] Exclude memory regions for the
1810 Ranges are in pairs (memory base and size).
1812 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1813 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1814 These can also be switched on/off via
1815 <debugfs>/dynamic_printk/modules
1817 print-fatal-signals=
1818 [KNL] debug: print fatal signals
1819 print-fatal-signals=1: print segfault info to
1823 printk.time= Show timing data prefixed to each printk message line
1824 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1826 profile= [KNL] Enable kernel profiling via /proc/profile
1827 Format: [schedule,]<number>
1828 Param: "schedule" - profile schedule points.
1829 Param: <number> - step/bucket size as a power of 2 for
1830 statistical time based profiling.
1831 Param: "sleep" - profile D-state sleeping (millisecs).
1832 Requires CONFIG_SCHEDSTATS
1833 Param: "kvm" - profile VM exits.
1835 processor.max_cstate= [HW,ACPI]
1836 Limit processor to maximum C-state
1837 max_cstate=9 overrides any DMI blacklist limit.
1839 processor.nocst [HW,ACPI]
1840 Ignore the _CST method to determine C-states,
1841 instead using the legacy FADT method
1843 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1845 See Documentation/blockdev/ramdisk.txt.
1847 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1848 probe for; one of (bare|imps|exps|lifebook|any).
1849 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1851 psmouse.resetafter= [HW,MOUSE]
1852 Try to reset the device after so many bad packets
1855 [HW,MOUSE] Set desired mouse resolution, in dpi.
1856 psmouse.smartscroll=
1857 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1858 0 = disabled, 1 = enabled (default).
1860 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1862 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1865 See Documentation/blockdev/paride.txt.
1868 [KNL] Number of legacy pty's. Overwrites compiled-in
1871 quiet [KNL] Disable most log messages
1876 See Documentation/md.txt.
1878 ramdisk_blocksize= [RAM]
1879 See Documentation/blockdev/ramdisk.txt.
1881 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1882 See Documentation/blockdev/ramdisk.txt.
1884 rcupdate.blimit= [KNL,BOOT]
1885 Set maximum number of finished RCU callbacks to process
1888 rcupdate.qhimark= [KNL,BOOT]
1889 Set threshold of queued
1890 RCU callbacks over which batch limiting is disabled.
1892 rcupdate.qlowmark= [KNL,BOOT]
1893 Set threshold of queued RCU callbacks below which
1894 batch limiting is re-enabled.
1898 Run specified binary instead of /init from the ramdisk,
1899 used for early userspace startup. See initrd.
1901 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1902 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1903 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1906 [KNL, SMP] Set scheduler's default relax_domain_level.
1907 See Documentation/cpusets.txt.
1909 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1911 reservetop= [X86-32]
1913 Reserves a hole at the top of the kernel virtual
1916 reset_devices [KNL] Force drivers to reset the underlying device
1917 during initialization.
1920 Specify the partition device for software suspend
1922 resume_offset= [SWSUSP]
1923 Specify the offset from the beginning of the partition
1924 given by "resume=" at which the swap header is located,
1925 in <PAGE_SIZE> units (needed only for swap files).
1926 See Documentation/power/swsusp-and-swap-files.txt
1928 retain_initrd [RAM] Keep initrd memory after extraction
1930 rhash_entries= [KNL,NET]
1931 Set number of hash buckets for route cache
1933 riscom8= [HW,SERIAL]
1934 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1936 ro [KNL] Mount root device read-only on boot
1938 root= [KNL] Root filesystem
1940 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1941 mount the root filesystem
1943 rootflags= [KNL] Set root filesystem mount option string
1945 rootfstype= [KNL] Set root filesystem type
1947 rootwait [KNL] Wait (indefinitely) for root device to show up.
1948 Useful for devices that are detected asynchronously
1949 (e.g. USB and MMC devices).
1951 root_plug.vendor_id=
1952 [ROOTPLUG] Override the default vendor ID
1954 root_plug.product_id=
1955 [ROOTPLUG] Override the default product ID
1958 [ROOTPLUG] Enable debugging output
1960 rw [KNL] Mount root device read-write on boot
1962 S [KNL] Run init in single mode
1965 See drivers/net/irda/sa1100_ir.c.
1967 sbni= [NET] Granch SBNI12 leased line adapter
1969 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1970 Format: <io>[,<timeout>[,<isapnp>]]
1972 scsi_debug_*= [SCSI]
1973 See drivers/scsi/scsi_debug.c.
1975 scsi_default_dev_flags=
1976 [SCSI] SCSI default device flags
1979 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1980 Format: <vendor>:<model>:<flags>
1981 (flags are integer value)
1983 scsi_logging_level= [SCSI] a bit mask of logging levels
1984 See drivers/scsi/scsi_logging.h for bits. Also
1985 settable via sysctl at dev.scsi.logging_level
1986 (/proc/sys/dev/scsi/logging_level).
1987 There is also a nice 'scsi_logging_level' script in the
1988 S390-tools package, available for download at
1989 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1991 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1992 discovered. async scans them in kernel threads,
1993 allowing boot to proceed. none ignores them, expecting
1994 user space to do the scan.
1996 selinux [SELINUX] Disable or enable SELinux at boot time.
1997 Format: { "0" | "1" }
1998 See security/selinux/Kconfig help text.
2001 Default value is set via kernel config option.
2002 If enabled at boot time, /selinux/disable can be used
2003 later to disable prior to initial policy load.
2005 selinux_compat_net =
2006 [SELINUX] Set initial selinux_compat_net flag value.
2007 Format: { "0" | "1" }
2008 0 -- use new secmark-based packet controls
2009 1 -- use legacy packet controls
2010 Default value is 0 (preferred).
2011 Value can be changed at runtime via
2012 /selinux/compat_net.
2014 serialnumber [BUGS=X86-32]
2017 Maximal number of shapers.
2019 show_msr= [x86] show boot-time MSR settings
2020 Format: { <integer> }
2021 Show boot-time (BIOS-initialized) MSR settings.
2022 The parameter means the number of CPUs to show,
2023 for example 1 means boot CPU only.
2026 See header of drivers/scsi/sim710.c.
2033 slub_debug[=options[,slabs]] [MM, SLUB]
2034 Enabling slub_debug allows one to determine the
2035 culprit if slab objects become corrupted. Enabling
2036 slub_debug can create guard zones around objects and
2037 may poison objects when not in use. Also tracks the
2038 last alloc / free. For more information see
2039 Documentation/vm/slub.txt.
2041 slub_max_order= [MM, SLUB]
2042 Determines the maximum allowed order for slabs.
2043 A high setting may cause OOMs due to memory
2044 fragmentation. For more information see
2045 Documentation/vm/slub.txt.
2047 slub_min_objects= [MM, SLUB]
2048 The minimum number of objects per slab. SLUB will
2049 increase the slab order up to slub_max_order to
2050 generate a sufficiently large slab able to contain
2051 the number of objects indicated. The higher the number
2052 of objects the smaller the overhead of tracking slabs
2053 and the less frequently locks need to be acquired.
2054 For more information see Documentation/vm/slub.txt.
2056 slub_min_order= [MM, SLUB]
2057 Determines the mininum page order for slabs. Must be
2058 lower than slub_max_order.
2059 For more information see Documentation/vm/slub.txt.
2061 slub_nomerge [MM, SLUB]
2062 Disable merging of slabs with similar size. May be
2063 necessary if there is some reason to distinguish
2064 allocs to different slabs. Debug options disable
2065 merging on their own.
2066 For more information see Documentation/vm/slub.txt.
2069 Format: <io1>[,<io2>[,...,<io8>]]
2071 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2072 attempt to substitute SMP alternatives once at boot.
2074 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2075 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2076 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2077 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2078 smsc-ircc2.ircc_irq= [HW] IRQ line
2079 smsc-ircc2.ircc_dma= [HW] DMA channel
2080 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2081 0: Toshiba Satellite 1800 (GP data pin select)
2082 1: Fast pin select (default)
2085 snd-ad1816a= [HW,ALSA]
2087 snd-ad1848= [HW,ALSA]
2089 snd-ali5451= [HW,ALSA]
2091 snd-als100= [HW,ALSA]
2093 snd-als4000= [HW,ALSA]
2095 snd-azt2320= [HW,ALSA]
2097 snd-cmi8330= [HW,ALSA]
2099 snd-cmipci= [HW,ALSA]
2101 snd-cs4231= [HW,ALSA]
2103 snd-cs4232= [HW,ALSA]
2105 snd-cs4236= [HW,ALSA]
2107 snd-cs4281= [HW,ALSA]
2109 snd-cs46xx= [HW,ALSA]
2111 snd-dt019x= [HW,ALSA]
2113 snd-dummy= [HW,ALSA]
2115 snd-emu10k1= [HW,ALSA]
2117 snd-ens1370= [HW,ALSA]
2119 snd-ens1371= [HW,ALSA]
2121 snd-es968= [HW,ALSA]
2123 snd-es1688= [HW,ALSA]
2125 snd-es18xx= [HW,ALSA]
2127 snd-es1938= [HW,ALSA]
2129 snd-es1968= [HW,ALSA]
2131 snd-fm801= [HW,ALSA]
2133 snd-gusclassic= [HW,ALSA]
2135 snd-gusextreme= [HW,ALSA]
2137 snd-gusmax= [HW,ALSA]
2141 snd-ice1712= [HW,ALSA]
2143 snd-intel8x0= [HW,ALSA]
2145 snd-interwave= [HW,ALSA]
2150 snd-korg1212= [HW,ALSA]
2152 snd-maestro3= [HW,ALSA]
2154 snd-mpu401= [HW,ALSA]
2156 snd-mtpav= [HW,ALSA]
2158 snd-nm256= [HW,ALSA]
2160 snd-opl3sa2= [HW,ALSA]
2168 snd-opti93x= [HW,ALSA]
2172 snd-rme32= [HW,ALSA]
2174 snd-rme96= [HW,ALSA]
2176 snd-rme9652= [HW,ALSA]
2182 snd-sbawe= [HW,ALSA]
2184 snd-serial= [HW,ALSA]
2186 snd-sgalaxy= [HW,ALSA]
2188 snd-sonicvibes= [HW,ALSA]
2193 snd-sun-cs4231= [HW,ALSA]
2195 snd-trident= [HW,ALSA]
2197 snd-usb-audio= [HW,ALSA,USB]
2199 snd-via82xx= [HW,ALSA]
2201 snd-virmidi= [HW,ALSA]
2203 snd-wavefront= [HW,ALSA]
2205 snd-ymfpci= [HW,ALSA]
2208 [KNL] Should the soft-lockup detector generate panics.
2210 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2211 See Documentation/sonypi.txt
2213 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2214 See Documentation/serial/specialix.txt.
2216 spia_io_base= [HW,MTD]
2222 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2224 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2225 See Documentation/scsi/st.txt.
2228 Enabled the stack tracer on boot up.
2232 Set the STI (builtin display/keyboard on the HP-PARISC
2233 machines) console (graphic card) which should be used
2234 as the initial boot-console.
2235 See also comment in drivers/video/console/sticore.c.
2238 See comment in drivers/video/console/sticore.c.
2241 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2245 Control how the NFS server code allocates CPUs to
2246 service thread pools. Depending on how many NICs
2247 you have and where their interrupts are bound, this
2248 option will affect which CPUs will do NFS serving.
2249 Note: this parameter cannot be changed while the
2250 NFS server is running.
2252 auto the server chooses an appropriate mode
2253 automatically using heuristics
2254 global a single global pool contains all CPUs
2255 percpu one pool for each CPU
2256 pernode one pool for each NUMA node (equivalent
2257 to global on non-NUMA machines)
2259 swiotlb= [IA-64] Number of I/O TLB slabs
2263 sym53c416= [HW,SCSI]
2264 See header of drivers/scsi/sym53c416.c.
2266 sysrq_always_enabled
2268 Ignore sysrq setting - this boot parameter will
2269 neutralize any effect of /proc/sys/kernel/sysrq.
2270 Useful for debugging.
2273 See header of drivers/scsi/t128.c.
2277 test_suspend= [SUSPEND]
2278 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2279 standby suspend) as the system sleep state to briefly
2280 enter during system startup. The system is woken from
2281 this state using a wakeup-capable RTC alarm.
2283 thash_entries= [KNL,NET]
2284 Set number of hash buckets for TCP connection
2286 thermal.act= [HW,ACPI]
2287 -1: disable all active trip points in all thermal zones
2288 <degrees C>: override all lowest active trip points
2290 thermal.crt= [HW,ACPI]
2291 -1: disable all critical trip points in all thermal zones
2292 <degrees C>: override all critical trip points
2294 thermal.nocrt= [HW,ACPI]
2295 Set to disable actions on ACPI thermal zone
2296 critical and hot trip points.
2298 thermal.off= [HW,ACPI]
2299 1: disable ACPI thermal control
2301 thermal.psv= [HW,ACPI]
2302 -1: disable all passive trip points
2303 <degrees C>: override all passive trip points to this value
2305 thermal.tzp= [HW,ACPI]
2306 Specify global default ACPI thermal zone polling rate
2307 <deci-seconds>: poll all this frequency
2308 0: no polling (default)
2311 See comment before function dc390_setup() in
2312 drivers/scsi/tmscsim.c.
2316 Specify if the kernel should make use of the cpu
2317 topology informations if the hardware supports these.
2318 The scheduler will make use of these informations and
2319 e.g. base its process migration decisions on it.
2324 trix= [HW,OSS] MediaTrix AudioTrix Pro
2326 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2328 tsc= Disable clocksource-must-verify flag for TSC.
2330 [x86] reliable: mark tsc clocksource as reliable, this
2331 disables clocksource verification at runtime.
2332 Used to enable high-resolution timer mode on older
2333 hardware, and in virtualized environment.
2335 turbografx.map[2|3]= [HW,JOY]
2336 TurboGraFX parallel port interface
2338 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2339 See also Documentation/input/joystick-parport.txt
2341 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2342 See header of drivers/scsi/u14-34f.c.
2351 [USB] Ignore overcurrent events (default N).
2352 Some badly-designed motherboards generate lots of
2353 bogus events, for ports that aren't wired to
2354 anything. Set this parameter to avoid log spamming.
2355 Note that genuine overcurrent events won't be
2360 Set unknown_nmi_panic=1 early on boot.
2362 usbcore.autosuspend=
2363 [USB] The autosuspend time delay (in seconds) used
2364 for newly-detected USB devices (default 2). This
2365 is the time required before an idle device will be
2366 autosuspended. Devices for which the delay is set
2367 to a negative value won't be autosuspended at all.
2369 usbcore.usbfs_snoop=
2370 [USB] Set to log all usbfs traffic (default 0 = off).
2372 usbcore.blinkenlights=
2373 [USB] Set to cycle leds on hubs (default 0 = off).
2375 usbcore.old_scheme_first=
2376 [USB] Start with the old device initialization
2377 scheme (default 0 = off).
2379 usbcore.use_both_schemes=
2380 [USB] Try the other device initialization scheme
2381 if the first one fails (default 1 = enabled).
2383 usbcore.initial_descriptor_timeout=
2384 [USB] Specifies timeout for the initial 64-byte
2385 USB_REQ_GET_DESCRIPTOR request in milliseconds
2386 (default 5000 = 5.0 seconds).
2389 [USBHID] The interval which mice are to be polled at.
2391 usb-storage.delay_use=
2392 [UMS] The delay in seconds before a new device is
2393 scanned for Logical Units (default 5).
2396 [UMS] A list of quirks entries to supplement or
2397 override the built-in unusual_devs list. List
2398 entries are separated by commas. Each entry has
2399 the form VID:PID:Flags where VID and PID are Vendor
2400 and Product ID values (4-digit hex numbers) and
2401 Flags is a set of characters, each corresponding
2402 to a common usb-storage quirk flag as follows:
2403 a = SANE_SENSE (collect more than 18 bytes
2405 c = FIX_CAPACITY (decrease the reported
2406 device capacity by one sector);
2407 h = CAPACITY_HEURISTICS (decrease the
2408 reported device capacity by one
2409 sector if the number is odd);
2410 i = IGNORE_DEVICE (don't bind to this
2412 l = NOT_LOCKABLE (don't try to lock and
2413 unlock ejectable media);
2414 m = MAX_SECTORS_64 (don't transfer more
2415 than 64 sectors = 32 KB at a time);
2416 o = CAPACITY_OK (accept the capacity
2417 reported by the device);
2418 r = IGNORE_RESIDUE (the device reports
2419 bogus residue values);
2420 s = SINGLE_LUN (the device has only one
2422 w = NO_WP_DETECT (don't test whether the
2423 medium is write-protected).
2424 Example: quirks=0419:aaf5:rl,0421:0433:rc
2426 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2427 kernel's map of available physical RAM.
2429 vdso= [X86-32,SH,x86-64]
2430 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2431 vdso=1: enable VDSO (default)
2432 vdso=0: disable VDSO mapping
2434 vdso32= [X86-32,X86-64]
2435 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2436 vdso32=1: enable 32-bit VDSO (default)
2437 vdso32=0: disable 32-bit VDSO mapping
2440 vector=percpu: enable percpu vector domain
2442 video= [FB] Frame buffer configuration
2443 See Documentation/fb/modedb.txt.
2445 vga= [BOOT,X86-32] Select a particular video mode
2446 See Documentation/x86/i386/boot.txt and
2447 Documentation/svga.txt.
2448 Use vga=ask for menu.
2449 This is actually a boot loader parameter; the value is
2450 passed to the kernel using a special protocol.
2452 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2453 size of <nn>. This can be used to increase the
2454 minimum size (128MB on x86). It can also be used to
2455 decrease the size and leave more room for directly
2458 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2461 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2464 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2467 waveartist= [HW,OSS]
2468 Format: <io>,<irq>,<dma>,<dma2>
2471 See header of drivers/scsi/wd33c93.c.
2474 See header of drivers/scsi/wd7000.c.
2477 See Documentation/watchdog/wdt.txt.
2479 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2480 xd_geo= See header of drivers/block/xd.c.
2482 xirc2ps_cs= [NET,PCMCIA]
2484 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2486 norandmaps Don't use address space randomization. Equivalent to
2487 echo 0 > /proc/sys/kernel/randomize_va_space
2489 ______________________________________________________________________
2493 Add documentation for ALSA options.
2494 Add more DRM drivers.