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
935 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
937 Disable intel iommu driver.
938 igfx_off [Default Off]
939 By default, gfx is mapped as normal device. If a gfx
940 device has a dedicated DMAR unit, the DMAR unit is
941 bypassed by not enabling DMAR with this option. In
942 this case, gfx device will use physical address for
945 With this option iommu will not optimize to look
946 for io virtual address below 32 bit forcing dual
947 address cycle on pci bus for cards supporting greater
948 than 32 bit addressing. The default is to look
949 for translation below 32 bit and if not available
950 then look in the higher range.
952 With this option on every unmap_single operation will
953 result in a hardware IOTLB flush operation as opposed
954 to batching them for performance.
956 io_delay= [X86-32,X86-64] I/O delay method
958 Standard port 0x80 based delay
960 Alternate port 0xed based delay (needed on some systems)
962 Simple two microseconds delay
966 io7= [HW] IO7 for Marvel based alpha systems
967 See comment before marvel_specify_io7 in
968 arch/alpha/kernel/core_marvel.c.
971 See Documentation/filesystems/nfsroot.txt.
973 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
974 See comment before ip2_setup() in
975 drivers/char/ip2/ip2base.c.
977 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
978 See header of drivers/scsi/ips.c.
980 ports= [IP_VS_FTP] IPVS ftp helper module
982 Up to 8 (IP_VS_APP_MAX_PORTS) ports
984 Format: <port>,<port>....
987 When an interrupt is not handled search all handlers
988 for it. Intended to get systems with badly broken
992 When an interrupt is not handled search all handlers
993 for it. Also check all handlers each timer
994 interrupt. Intended to get systems with badly broken
998 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1000 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1002 <cpu number>,...,<cpu number>
1004 <cpu number>-<cpu number>
1005 (must be a positive range in ascending order)
1007 <cpu number>,...,<cpu number>-<cpu number>
1009 This option can be used to specify one or more CPUs
1010 to isolate from the general SMP balancing and scheduling
1011 algorithms. You can move a process onto or off an
1012 "isolated" CPU via the CPU affinity syscalls or cpuset.
1013 <cpu number> begins at 0 and the maximum value is
1014 "number of CPUs in system - 1".
1016 This option is the preferred way to isolate CPUs. The
1017 alternative -- manually setting the CPU mask of all
1018 tasks in the system -- can cause problems and
1019 suboptimal load balancer performance.
1023 js= [HW,JOY] Analog joystick
1024 See Documentation/input/joystick.txt.
1026 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1027 specifies the amount of memory usable by the kernel
1028 for non-movable allocations. The requested amount is
1029 spread evenly throughout all nodes in the system. The
1030 remaining memory in each node is used for Movable
1031 pages. In the event, a node is too small to have both
1032 kernelcore and Movable pages, kernelcore pages will
1033 take priority and other nodes will have a larger number
1034 of kernelcore pages. The Movable zone is used for the
1035 allocation of pages that may be reclaimed or moved
1036 by the page migration subsystem. This means that
1037 HugeTLB pages may not be allocated from this zone.
1038 Note that allocations like PTEs-from-HighMem still
1039 use the HighMem zone if it exists, and the Normal
1040 zone if it does not.
1042 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1043 is similar to kernelcore except it specifies the
1044 amount of memory used for migratable allocations.
1045 If both kernelcore and movablecore is specified,
1046 then kernelcore will be at *least* the specified
1047 value but may be more. If movablecore on its own
1048 is specified, the administrator must be careful
1049 that the amount of memory usable for all allocations
1054 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1057 kgdboc= [HW] kgdb over consoles.
1058 Requires a tty driver that supports console polling.
1059 (only serial suported for now)
1060 Format: <serial_device>[,baud]
1062 kmac= [MIPS] korina ethernet MAC address.
1063 Configure the RouterBoard 532 series on-chip
1064 Ethernet adapter MAC address.
1070 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1073 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1076 libata.dma= [LIBATA] DMA control
1077 libata.dma=0 Disable all PATA and SATA DMA
1078 libata.dma=1 PATA and SATA Disk DMA only
1079 libata.dma=2 ATAPI (CDROM) DMA only
1080 libata.dma=4 Compact Flash DMA only
1081 Combinations also work, so libata.dma=3 enables DMA
1082 for disks and CDROMs, but not CFs.
1084 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1088 libata.force= [LIBATA] Force configurations. The format is comma
1089 separated list of "[ID:]VAL" where ID is
1090 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1091 matching port, link or device. Basically, it matches
1092 the ATA ID string printed on console by libata. If
1093 the whole ID part is omitted, the last PORT and DEVICE
1094 values are used. If ID hasn't been specified yet, the
1095 configuration applies to all ports, links and devices.
1097 If only DEVICE is omitted, the parameter applies to
1098 the port and all links and devices behind it. DEVICE
1099 number of 0 either selects the first device or the
1100 first fan-out link behind PMP device. It does not
1101 select the host link. DEVICE number of 15 selects the
1102 host link and device attached to it.
1104 The VAL specifies the configuration to force. As long
1105 as there's no ambiguity shortcut notation is allowed.
1106 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1107 The following configurations can be forced.
1109 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1110 Any ID with matching PORT is used.
1112 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1114 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1115 udma[/][16,25,33,44,66,100,133] notation is also
1118 * [no]ncq: Turn on or off NCQ.
1120 * nohrst, nosrst, norst: suppress hard, soft
1123 If there are multiple matching configurations changing
1124 the same attribute, the last one is used.
1126 lmb=debug [KNL] Enable lmb debug messages.
1128 load_ramdisk= [RAM] List of ramdisks to load from floppy
1129 See Documentation/blockdev/ramdisk.txt.
1131 lockd.nlm_grace_period=P [NFS] Assign grace period.
1134 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1137 lockd.nlm_timeout=T [NFS] Assign timeout value.
1140 lockd.nlm_udpport=M [NFS] Assign UDP port.
1143 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1146 loglevel= All Kernel Messages with a loglevel smaller than the
1147 console loglevel will be printed to the console. It can
1148 also be changed with klogd or other programs. The
1149 loglevels are defined as follows:
1151 0 (KERN_EMERG) system is unusable
1152 1 (KERN_ALERT) action must be taken immediately
1153 2 (KERN_CRIT) critical conditions
1154 3 (KERN_ERR) error conditions
1155 4 (KERN_WARNING) warning conditions
1156 5 (KERN_NOTICE) normal but significant condition
1157 6 (KERN_INFO) informational
1158 7 (KERN_DEBUG) debug-level messages
1160 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1161 Format: { n | nk | nM }
1162 n must be a power of two. The default size
1163 is set in the kernel config file.
1165 logo.nologo [FB] Disables display of the built-in Linux logo.
1166 This may be used to provide more screen space for
1167 kernel log messages and is useful when debugging
1168 kernel boot problems.
1170 lp=0 [LP] Specify parallel ports to use, e.g,
1171 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1172 lp=reset first parallel port). 'lp=0' disables the
1173 lp=auto printer driver. 'lp=reset' (which can be
1174 specified in addition to the ports) causes
1175 attached printers to be reset. Using
1176 lp=port1,port2,... specifies the parallel ports
1177 to associate lp devices with, starting with
1178 lp0. A port specification may be 'none' to skip
1179 that lp device, or a parport name such as
1180 'parport0'. Specifying 'lp=auto' instead of a
1181 port specification list means that device IDs
1182 from each port should be examined, to see if
1183 an IEEE 1284-compliant printer is attached; if
1184 so, the driver will manage that printer.
1185 See also header of drivers/char/lp.c.
1188 Sets loops_per_jiffy to given constant, thus avoiding
1189 time-consuming boot-time autodetection (up to 250 ms per
1190 CPU). 0 enables autodetection (default). To determine
1191 the correct value for your kernel, boot with normal
1192 autodetection and see what value is printed. Note that
1193 on SMP systems the preset will be applied to all CPUs,
1194 which is likely to cause problems if your CPUs need
1195 significantly divergent settings. An incorrect value
1196 will cause delays in the kernel to be wrong, leading to
1197 unpredictable I/O errors and other breakage. Although
1198 unlikely, in the extreme case this might damage your
1202 Format: <io>,<irq>,<dma>
1204 mac5380= [HW,SCSI] Format:
1205 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1207 machvec= [IA64] Force the use of a particular machine-vector
1208 (machvec) in a generic kernel.
1209 Example: machvec=hpzx1_swiotlb
1211 max_loop= [LOOP] Maximum number of loopback devices that can
1215 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1216 should make use of. maxcpus=n : n >= 0 limits the
1217 kernel to using 'n' processors. n=0 is a special case,
1218 it is equivalent to "nosmp", which also disables
1221 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1222 or equal to this physical address is ignored.
1224 max_luns= [SCSI] Maximum number of LUNs to probe.
1225 Should be between 1 and 2^32-1.
1228 [SCSI] Maximum number of LUNs received.
1229 Should be between 1 and 16384.
1233 mce [X86-32] Machine Check Exception
1235 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1237 md= [HW] RAID subsystems devices and level
1238 See Documentation/md.txt.
1241 Format: <first>,<last>
1242 Specifies range of consoles to be captured by the MDA.
1244 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1245 Amount of memory to be used when the kernel is not able
1246 to see the whole system memory or for test.
1247 [X86-32] Use together with memmap= to avoid physical
1248 address space collisions. Without memmap= PCI devices
1249 could be placed at addresses belonging to unused RAM.
1251 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1255 [KNL,SH] Allow user to override the default size for
1256 per-device physically contiguous DMA buffers.
1258 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1259 E820 memory map, as specified by the user.
1260 Such memmap=exactmap lines can be constructed based on
1261 BIOS output or other requirements. See the memmap=nn@ss
1264 memmap=nn[KMG]@ss[KMG]
1265 [KNL] Force usage of a specific region of memory
1266 Region of memory to be used, from ss to ss+nn.
1268 memmap=nn[KMG]#ss[KMG]
1269 [KNL,ACPI] Mark specific memory as ACPI data.
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 reserved.
1274 Region of memory to be used, from ss to ss+nn.
1275 Example: Exclude memory from 0x18690000-0x1869ffff
1276 memmap=64K$0x18690000
1278 memmap=0x10000$0x18690000
1280 memory_corruption_check=0/1 [X86]
1281 Some BIOSes seem to corrupt the first 64k of
1282 memory when doing things like suspend/resume.
1283 Setting this option will scan the memory
1284 looking for corruption. Enabling this will
1285 both detect corruption and prevent the kernel
1286 from using the memory being corrupted.
1287 However, its intended as a diagnostic tool; if
1288 repeatable BIOS-originated corruption always
1289 affects the same memory, you can use memmap=
1290 to prevent the kernel from using that memory.
1292 memory_corruption_check_size=size [X86]
1293 By default it checks for corruption in the low
1294 64k, making this memory unavailable for normal
1295 use. Use this parameter to scan for
1296 corruption in more or less memory.
1298 memory_corruption_check_period=seconds [X86]
1299 By default it checks for corruption every 60
1300 seconds. Use this parameter to check at some
1301 other rate. 0 disables periodic checking.
1303 memtest= [KNL,X86] Enable memtest
1305 range: 0,4 : pattern number
1306 default : 0 <disable>
1308 meye.*= [HW] Set MotionEye Camera parameters
1309 See Documentation/video4linux/meye.txt.
1311 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1312 Multi-Function General Purpose Timers on AMD Geode
1315 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1316 the BIOS has incorrectly applied a workaround. TinyBIOS
1317 version 0.98 is known to be affected, 0.99 fixes the
1318 problem by letting the user disable the workaround.
1322 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1323 physical address is ignored.
1326 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1327 parameter allows control of the logging verbosity for
1328 the additional memory initialisation checks. A value
1329 of 0 disables mminit logging and a level of 4 will
1330 log everything. Information is printed at KERN_DEBUG
1331 so loglevel=8 may also need to be specified.
1334 [MOUSE] Maximum time between finger touching and
1335 leaving touchpad surface for touch to be considered
1336 a tap and be reported as a left button click (for
1337 touchpads working in absolute mode only).
1339 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1340 reporting absolute coordinates, such as tablets
1341 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1342 reporting absolute coordinates, such as tablets
1347 MTD_Partition= [MTD]
1348 Format: <name>,<region-number>,<size>,<offset>
1350 MTD_Region= [MTD] Format:
1351 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1354 See drivers/mtd/cmdlinepart.c.
1357 ARM/S3C2412 JIVE boot control
1359 See arch/arm/mach-s3c2412/mach-jive.c
1361 mtouchusb.raw_coordinates=
1362 [HW] Make the MicroTouch USB driver use raw coordinates
1363 ('y', default) or cooked coordinates ('n')
1365 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1368 See header of drivers/scsi/NCR_D700.c.
1372 ncr53c400= [HW,SCSI]
1374 ncr53c400a= [HW,SCSI]
1376 ncr53c406a= [HW,SCSI]
1378 ncr53c8xx= [HW,SCSI]
1380 netdev= [NET] Network devices parameters
1381 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1382 Note that mem_start is often overloaded to mean
1383 something different and driver-specific.
1384 This usage is only documented in each driver source
1388 [NETFILTER] Enable connection tracking flow accounting
1389 0 to disable accounting
1390 1 to enable accounting
1391 Default value depends on CONFIG_NF_CT_ACCT that is
1392 going to be removed in 2.6.29.
1395 See Documentation/filesystems/nfsroot.txt.
1397 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1398 See Documentation/filesystems/nfsroot.txt.
1400 nfs.callback_tcpport=
1401 [NFS] set the TCP port on which the NFSv4 callback
1402 channel should listen.
1404 nfs.idmap_cache_timeout=
1405 [NFS] set the maximum lifetime for idmapper cache
1409 [NFS] enable 64-bit inode numbers.
1410 If zero, the NFS client will fake up a 32-bit inode
1411 number for the readdir() and stat() syscalls instead
1412 of returning the full 64-bit number.
1413 The default is to return 64-bit inode numbers.
1415 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1416 when a NMI is triggered.
1417 Format: [state][,regs][,debounce][,die]
1419 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1420 Format: [panic,][num]
1422 0 - turn nmi_watchdog off
1423 1 - use the IO-APIC timer for the NMI watchdog
1424 2 - use the local APIC for the NMI watchdog using
1425 a performance counter. Note: This will use one performance
1426 counter and the local APIC's performance vector.
1427 When panic is specified panic when an NMI watchdog timeout occurs.
1428 This is useful when you use a panic=... timeout and need the box
1430 Instead of 1 and 2 it is possible to use the following
1431 symbolic names: lapic and ioapic
1432 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1434 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1435 emulation library even if a 387 maths coprocessor
1438 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1439 caches in the slab allocator. Saves per-node memory,
1440 but will impact performance.
1444 noapic [SMP,APIC] Tells the kernel to not make use of any
1445 IOAPICs that may be present in the system.
1447 nobats [PPC] Do not use BATs for mapping kernel lowmem
1448 on "Classic" PPC cores.
1452 nodelayacct [KNL] Disable per-task delay accounting
1454 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1456 nodsp [SH] Disable hardware DSP at boot time.
1458 noefi [X86-32,X86-64] Disable EFI runtime services support.
1462 noexec [X86-32,X86-64]
1463 On X86-32 available only on PAE configured kernels.
1464 noexec=on: enable non-executable mappings (default)
1465 noexec=off: disable non-executable mappings
1468 This affects only 32-bit executables.
1469 noexec32=on: enable non-executable mappings (default)
1470 read doesn't imply executable mappings
1471 noexec32=off: disable non-executable mappings
1472 read implies executable mappings
1474 nofpu [SH] Disable hardware FPU at boot time.
1476 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1477 register save and restore. The kernel will only save
1478 legacy floating-point registers on task switch.
1480 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1484 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1485 instruction doesn't work correctly and not to
1488 no_file_caps Tells the kernel not to honor file capabilities. The
1489 only way then for a file to be executed with privilege
1490 is to be setuid root or executed by root.
1492 nohalt [IA-64] Tells the kernel not to use the power saving
1493 function PAL_HALT_LIGHT when idle. This increases
1494 power-consumption. On the positive side, it reduces
1495 interrupt wake-up latency, which may improve performance
1496 in certain environments such as networked servers or
1499 nohz= [KNL] Boottime enable/disable dynamic ticks
1500 Valid arguments: on, off
1503 noirqdebug [X86-32] Disables the code which attempts to detect and
1504 disable unhandled interrupt sources.
1506 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1507 broken timer IRQ sources.
1509 noisapnp [ISAPNP] Disables ISA PnP code.
1511 noinitrd [RAM] Tells the kernel not to load any configured
1516 nojitter [IA64] Disables jitter checking for ITC timers.
1518 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1520 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1522 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1524 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1525 default x2apic cluster mode on platforms
1528 noltlbs [PPC] Do not use large page/tlb entries for kernel
1529 lowmem mapping on PPC40x.
1531 nomca [IA-64] Disable machine check abort handling
1533 nomce [X86-32] Machine Check Exception
1535 nomfgpt [X86-32] Disable Multi-Function General Purpose
1536 Timer usage (for AMD Geode machines).
1538 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1540 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1541 with UP alternatives
1543 noresidual [PPC] Don't use residual data on PReP machines.
1545 noresume [SWSUSP] Disables resume and restores original swap
1548 no-scroll [VGA] Disables scrollback.
1549 This is required for the Braillex ib80-piezo Braille
1550 reader made by F.H. Papenmeier (Germany).
1554 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1556 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1557 and disable the IO APIC. legacy for "maxcpus=0".
1559 nosoftlockup [KNL] Disable the soft-lockup detector.
1561 nosync [HW,M68K] Disables sync negotiation for all devices.
1563 notsc [BUGS=X86-32] Disable Time Stamp Counter
1565 nousb [USB] Disable the USB subsystem
1569 nptcg= [IA64] Override max number of concurrent global TLB
1570 purges which is reported from either PAL_VM_SUMMARY or
1573 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1574 one of ['zone', 'node', 'default'] can be specified
1575 This can be set from sysctl after boot.
1576 See Documentation/sysctl/vm.txt for details.
1578 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1580 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1581 See Documentation/debugging-via-ohci1394.txt for more
1584 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1585 Rather than timing out after 20 ms if an EC
1586 command is not properly ACKed, override the length
1587 of the timeout. We have interrupts disabled while
1588 waiting for the ACK, so if this is set too high
1589 interrupts *may* be lost!
1594 oprofile.timer= [HW]
1595 Use timer interrupt instead of performance counters
1597 osst= [HW,SCSI] SCSI Tape Driver
1598 Format: <buffer_size>,<write_threshold>
1599 See also Documentation/scsi/st.txt.
1601 panic= [KNL] Kernel behaviour on panic
1604 parkbd.port= [HW] Parallel port number the keyboard adapter is
1605 connected to, default is 0.
1607 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1608 0 for XT, 1 for AT (default is AT).
1611 parport= [HW,PPT] Specify parallel ports. 0 disables.
1612 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1613 Use 'auto' to force the driver to use any
1614 IRQ/DMA settings detected (the default is to
1615 ignore detected IRQ/DMA settings because of
1616 possible conflicts). You can specify the base
1617 address, IRQ, and DMA settings; IRQ and DMA
1618 should be numbers, or 'auto' (for using detected
1619 settings on that particular port), or 'nofifo'
1620 (to avoid using a FIFO even if it is detected).
1621 Parallel ports are assigned in the order they
1622 are specified on the command line, starting
1625 parport_init_mode= [HW,PPT]
1626 Configure VIA parallel port to operate in
1627 a specific mode. This is necessary on Pegasos
1628 computer where firmware has no options for setting
1629 up parallel port mode and sets it to spp.
1630 Currently this function knows 686a and 8231 chips.
1631 Format: [spp|ps2|epp|ecp|ecpepp]
1633 pas2= [HW,OSS] Format:
1634 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1637 See header of drivers/scsi/pas16.c.
1640 Halt all CPUs after the first oops has been printed for
1641 the specified number of seconds. This is to be used if
1642 your oopses keep scrolling off the screen.
1647 See header of drivers/block/paride/pcd.c.
1648 See also Documentation/blockdev/paride.txt.
1650 pci=option[,option...] [PCI] various PCI subsystem options:
1651 off [X86] don't probe for the PCI bus
1652 bios [X86-32] force use of PCI BIOS, don't access
1653 the hardware directly. Use this if your machine
1654 has a non-standard PCI host bridge.
1655 nobios [X86-32] disallow use of PCI BIOS, only direct
1656 hardware access methods are allowed. Use this
1657 if you experience crashes upon bootup and you
1658 suspect they are caused by the BIOS.
1659 conf1 [X86] Force use of PCI Configuration
1661 conf2 [X86] Force use of PCI Configuration
1663 noaer [PCIE] If the PCIEAER kernel config parameter is
1664 enabled, this kernel boot option can be used to
1665 disable the use of PCIE advanced error reporting.
1666 nodomains [PCI] Disable support for multiple PCI
1667 root domains (aka PCI segments, in ACPI-speak).
1668 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1670 nomsi [MSI] If the PCI_MSI kernel config parameter is
1671 enabled, this kernel boot option can be used to
1672 disable the use of MSI interrupts system-wide.
1673 noioapicquirk [APIC] Disable all boot interrupt quirks.
1674 Safety option to keep boot IRQs enabled. This
1675 should never be necessary.
1676 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1677 primary IO-APIC for bridges that cannot disable
1678 boot IRQs. This fixes a source of spurious IRQs
1679 when the system masks IRQs.
1680 noioapicreroute [APIC] Disable workaround that uses the
1681 boot IRQ equivalent of an IRQ that connects to
1682 a chipset where boot IRQs cannot be disabled.
1683 The opposite of ioapicreroute.
1684 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1685 routing table. These calls are known to be buggy
1686 on several machines and they hang the machine
1687 when used, but on other computers it's the only
1688 way to get the interrupt routing table. Try
1689 this option if the kernel is unable to allocate
1690 IRQs or discover secondary PCI buses on your
1692 rom [X86] Assign address space to expansion ROMs.
1693 Use with caution as certain devices share
1694 address decoders between ROMs and other
1696 norom [X86] Do not assign address space to
1697 expansion ROMs that do not already have
1698 BIOS assigned address ranges.
1699 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1700 assigned automatically to PCI devices. You can
1701 make the kernel exclude IRQs of your ISA cards
1703 pirqaddr=0xAAAAA [X86] Specify the physical address
1704 of the PIRQ table (normally generated
1705 by the BIOS) if it is outside the
1706 F0000h-100000h range.
1707 lastbus=N [X86] Scan all buses thru bus #N. Can be
1708 useful if the kernel is unable to find your
1709 secondary buses and you want to tell it
1710 explicitly which ones they are.
1711 assign-busses [X86] Always assign all PCI bus
1712 numbers ourselves, overriding
1713 whatever the firmware may have done.
1714 usepirqmask [X86] Honor the possible IRQ mask stored
1715 in the BIOS $PIR table. This is needed on
1716 some systems with broken BIOSes, notably
1717 some HP Pavilion N5400 and Omnibook XE3
1718 notebooks. This will have no effect if ACPI
1719 IRQ routing is enabled.
1720 noacpi [X86] Do not use ACPI for IRQ routing
1721 or for PCI scanning.
1722 use_crs [X86] Use _CRS for PCI resource
1724 routeirq Do IRQ routing for all PCI devices.
1725 This is normally done in pci_enable_device(),
1726 so this option is a temporary workaround
1727 for broken drivers that don't call it.
1728 skip_isa_align [X86] do not align io start addr, so can
1729 handle more pci cards
1730 firmware [ARM] Do not re-enumerate the bus but instead
1731 just use the configuration from the
1732 bootloader. This is currently used on
1733 IXP2000 systems where the bus has to be
1734 configured a certain way for adjunct CPUs.
1735 noearly [X86] Don't do any early type 1 scanning.
1736 This might help on some broken boards which
1737 machine check when some devices' config space
1738 is read. But various workarounds are disabled
1739 and some IOMMU drivers will not work.
1740 bfsort Sort PCI devices into breadth-first order.
1741 This sorting is done to get a device
1742 order compatible with older (<= 2.4) kernels.
1743 nobfsort Don't sort PCI devices into breadth-first order.
1744 cbiosize=nn[KMG] The fixed amount of bus space which is
1745 reserved for the CardBus bridge's IO window.
1746 The default value is 256 bytes.
1747 cbmemsize=nn[KMG] The fixed amount of bus space which is
1748 reserved for the CardBus bridge's memory
1749 window. The default value is 64 megabytes.
1751 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1754 force Enable ASPM even on devices that claim not to support it.
1755 WARNING: Forcing ASPM on may cause system lockups.
1757 pcmv= [HW,PCMCIA] BadgePAD 4
1760 See Documentation/blockdev/paride.txt.
1762 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1765 See arch/parisc/kernel/pdc_chassis.c
1768 See Documentation/blockdev/paride.txt.
1771 See Documentation/blockdev/paride.txt.
1773 pirq= [SMP,APIC] Manual mp-table setup
1774 See Documentation/x86/i386/IO-APIC.txt.
1776 plip= [PPT,NET] Parallel port network link
1777 Format: { parport<nr> | timid | 0 }
1778 See also Documentation/parport.txt.
1780 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1781 Override pmtimer IOPort with a hex value.
1785 Enable PNP debug messages. This depends on the
1786 CONFIG_PNP_DEBUG_MESSAGES option.
1792 { on | off | curr | res | no-curr | no-res }
1795 [ISAPNP] Exclude IRQs for the autoconfiguration
1798 [ISAPNP] Exclude DMAs for the autoconfiguration
1800 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1801 Ranges are in pairs (I/O port base and size).
1804 [ISAPNP] Exclude memory regions for the
1806 Ranges are in pairs (memory base and size).
1808 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1809 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1810 These can also be switched on/off via
1811 <debugfs>/dynamic_printk/modules
1813 print-fatal-signals=
1814 [KNL] debug: print fatal signals
1815 print-fatal-signals=1: print segfault info to
1819 printk.time= Show timing data prefixed to each printk message line
1820 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1822 profile= [KNL] Enable kernel profiling via /proc/profile
1823 Format: [schedule,]<number>
1824 Param: "schedule" - profile schedule points.
1825 Param: <number> - step/bucket size as a power of 2 for
1826 statistical time based profiling.
1827 Param: "sleep" - profile D-state sleeping (millisecs).
1828 Requires CONFIG_SCHEDSTATS
1829 Param: "kvm" - profile VM exits.
1831 processor.max_cstate= [HW,ACPI]
1832 Limit processor to maximum C-state
1833 max_cstate=9 overrides any DMI blacklist limit.
1835 processor.nocst [HW,ACPI]
1836 Ignore the _CST method to determine C-states,
1837 instead using the legacy FADT method
1839 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1841 See Documentation/blockdev/ramdisk.txt.
1843 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1844 probe for; one of (bare|imps|exps|lifebook|any).
1845 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1847 psmouse.resetafter= [HW,MOUSE]
1848 Try to reset the device after so many bad packets
1851 [HW,MOUSE] Set desired mouse resolution, in dpi.
1852 psmouse.smartscroll=
1853 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1854 0 = disabled, 1 = enabled (default).
1856 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1858 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1861 See Documentation/blockdev/paride.txt.
1864 [KNL] Number of legacy pty's. Overwrites compiled-in
1867 quiet [KNL] Disable most log messages
1872 See Documentation/md.txt.
1874 ramdisk_blocksize= [RAM]
1875 See Documentation/blockdev/ramdisk.txt.
1877 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1878 See Documentation/blockdev/ramdisk.txt.
1880 rcupdate.blimit= [KNL,BOOT]
1881 Set maximum number of finished RCU callbacks to process
1884 rcupdate.qhimark= [KNL,BOOT]
1885 Set threshold of queued
1886 RCU callbacks over which batch limiting is disabled.
1888 rcupdate.qlowmark= [KNL,BOOT]
1889 Set threshold of queued RCU callbacks below which
1890 batch limiting is re-enabled.
1894 Run specified binary instead of /init from the ramdisk,
1895 used for early userspace startup. See initrd.
1897 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1898 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1899 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1902 [KNL, SMP] Set scheduler's default relax_domain_level.
1903 See Documentation/cpusets.txt.
1905 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1907 reservetop= [X86-32]
1909 Reserves a hole at the top of the kernel virtual
1912 reset_devices [KNL] Force drivers to reset the underlying device
1913 during initialization.
1916 Specify the partition device for software suspend
1918 resume_offset= [SWSUSP]
1919 Specify the offset from the beginning of the partition
1920 given by "resume=" at which the swap header is located,
1921 in <PAGE_SIZE> units (needed only for swap files).
1922 See Documentation/power/swsusp-and-swap-files.txt
1924 retain_initrd [RAM] Keep initrd memory after extraction
1926 rhash_entries= [KNL,NET]
1927 Set number of hash buckets for route cache
1929 riscom8= [HW,SERIAL]
1930 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1932 ro [KNL] Mount root device read-only on boot
1934 root= [KNL] Root filesystem
1936 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1937 mount the root filesystem
1939 rootflags= [KNL] Set root filesystem mount option string
1941 rootfstype= [KNL] Set root filesystem type
1943 rootwait [KNL] Wait (indefinitely) for root device to show up.
1944 Useful for devices that are detected asynchronously
1945 (e.g. USB and MMC devices).
1947 root_plug.vendor_id=
1948 [ROOTPLUG] Override the default vendor ID
1950 root_plug.product_id=
1951 [ROOTPLUG] Override the default product ID
1954 [ROOTPLUG] Enable debugging output
1956 rw [KNL] Mount root device read-write on boot
1958 S [KNL] Run init in single mode
1961 See drivers/net/irda/sa1100_ir.c.
1963 sbni= [NET] Granch SBNI12 leased line adapter
1965 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1966 Format: <io>[,<timeout>[,<isapnp>]]
1968 scsi_debug_*= [SCSI]
1969 See drivers/scsi/scsi_debug.c.
1971 scsi_default_dev_flags=
1972 [SCSI] SCSI default device flags
1975 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1976 Format: <vendor>:<model>:<flags>
1977 (flags are integer value)
1979 scsi_logging_level= [SCSI] a bit mask of logging levels
1980 See drivers/scsi/scsi_logging.h for bits. Also
1981 settable via sysctl at dev.scsi.logging_level
1982 (/proc/sys/dev/scsi/logging_level).
1983 There is also a nice 'scsi_logging_level' script in the
1984 S390-tools package, available for download at
1985 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1987 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1988 discovered. async scans them in kernel threads,
1989 allowing boot to proceed. none ignores them, expecting
1990 user space to do the scan.
1992 selinux [SELINUX] Disable or enable SELinux at boot time.
1993 Format: { "0" | "1" }
1994 See security/selinux/Kconfig help text.
1997 Default value is set via kernel config option.
1998 If enabled at boot time, /selinux/disable can be used
1999 later to disable prior to initial policy load.
2001 selinux_compat_net =
2002 [SELINUX] Set initial selinux_compat_net flag value.
2003 Format: { "0" | "1" }
2004 0 -- use new secmark-based packet controls
2005 1 -- use legacy packet controls
2006 Default value is 0 (preferred).
2007 Value can be changed at runtime via
2008 /selinux/compat_net.
2010 serialnumber [BUGS=X86-32]
2013 Maximal number of shapers.
2015 show_msr= [x86] show boot-time MSR settings
2016 Format: { <integer> }
2017 Show boot-time (BIOS-initialized) MSR settings.
2018 The parameter means the number of CPUs to show,
2019 for example 1 means boot CPU only.
2022 See header of drivers/scsi/sim710.c.
2029 slub_debug[=options[,slabs]] [MM, SLUB]
2030 Enabling slub_debug allows one to determine the
2031 culprit if slab objects become corrupted. Enabling
2032 slub_debug can create guard zones around objects and
2033 may poison objects when not in use. Also tracks the
2034 last alloc / free. For more information see
2035 Documentation/vm/slub.txt.
2037 slub_max_order= [MM, SLUB]
2038 Determines the maximum allowed order for slabs.
2039 A high setting may cause OOMs due to memory
2040 fragmentation. For more information see
2041 Documentation/vm/slub.txt.
2043 slub_min_objects= [MM, SLUB]
2044 The minimum number of objects per slab. SLUB will
2045 increase the slab order up to slub_max_order to
2046 generate a sufficiently large slab able to contain
2047 the number of objects indicated. The higher the number
2048 of objects the smaller the overhead of tracking slabs
2049 and the less frequently locks need to be acquired.
2050 For more information see Documentation/vm/slub.txt.
2052 slub_min_order= [MM, SLUB]
2053 Determines the mininum page order for slabs. Must be
2054 lower than slub_max_order.
2055 For more information see Documentation/vm/slub.txt.
2057 slub_nomerge [MM, SLUB]
2058 Disable merging of slabs with similar size. May be
2059 necessary if there is some reason to distinguish
2060 allocs to different slabs. Debug options disable
2061 merging on their own.
2062 For more information see Documentation/vm/slub.txt.
2065 Format: <io1>[,<io2>[,...,<io8>]]
2067 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2068 attempt to substitute SMP alternatives once at boot.
2070 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2071 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2072 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2073 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2074 smsc-ircc2.ircc_irq= [HW] IRQ line
2075 smsc-ircc2.ircc_dma= [HW] DMA channel
2076 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2077 0: Toshiba Satellite 1800 (GP data pin select)
2078 1: Fast pin select (default)
2081 snd-ad1816a= [HW,ALSA]
2083 snd-ad1848= [HW,ALSA]
2085 snd-ali5451= [HW,ALSA]
2087 snd-als100= [HW,ALSA]
2089 snd-als4000= [HW,ALSA]
2091 snd-azt2320= [HW,ALSA]
2093 snd-cmi8330= [HW,ALSA]
2095 snd-cmipci= [HW,ALSA]
2097 snd-cs4231= [HW,ALSA]
2099 snd-cs4232= [HW,ALSA]
2101 snd-cs4236= [HW,ALSA]
2103 snd-cs4281= [HW,ALSA]
2105 snd-cs46xx= [HW,ALSA]
2107 snd-dt019x= [HW,ALSA]
2109 snd-dummy= [HW,ALSA]
2111 snd-emu10k1= [HW,ALSA]
2113 snd-ens1370= [HW,ALSA]
2115 snd-ens1371= [HW,ALSA]
2117 snd-es968= [HW,ALSA]
2119 snd-es1688= [HW,ALSA]
2121 snd-es18xx= [HW,ALSA]
2123 snd-es1938= [HW,ALSA]
2125 snd-es1968= [HW,ALSA]
2127 snd-fm801= [HW,ALSA]
2129 snd-gusclassic= [HW,ALSA]
2131 snd-gusextreme= [HW,ALSA]
2133 snd-gusmax= [HW,ALSA]
2137 snd-ice1712= [HW,ALSA]
2139 snd-intel8x0= [HW,ALSA]
2141 snd-interwave= [HW,ALSA]
2146 snd-korg1212= [HW,ALSA]
2148 snd-maestro3= [HW,ALSA]
2150 snd-mpu401= [HW,ALSA]
2152 snd-mtpav= [HW,ALSA]
2154 snd-nm256= [HW,ALSA]
2156 snd-opl3sa2= [HW,ALSA]
2164 snd-opti93x= [HW,ALSA]
2168 snd-rme32= [HW,ALSA]
2170 snd-rme96= [HW,ALSA]
2172 snd-rme9652= [HW,ALSA]
2178 snd-sbawe= [HW,ALSA]
2180 snd-serial= [HW,ALSA]
2182 snd-sgalaxy= [HW,ALSA]
2184 snd-sonicvibes= [HW,ALSA]
2189 snd-sun-cs4231= [HW,ALSA]
2191 snd-trident= [HW,ALSA]
2193 snd-usb-audio= [HW,ALSA,USB]
2195 snd-via82xx= [HW,ALSA]
2197 snd-virmidi= [HW,ALSA]
2199 snd-wavefront= [HW,ALSA]
2201 snd-ymfpci= [HW,ALSA]
2204 [KNL] Should the soft-lockup detector generate panics.
2206 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2207 See Documentation/sonypi.txt
2209 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2210 See Documentation/serial/specialix.txt.
2212 spia_io_base= [HW,MTD]
2218 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2220 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2221 See Documentation/scsi/st.txt.
2224 Enabled the stack tracer on boot up.
2228 Set the STI (builtin display/keyboard on the HP-PARISC
2229 machines) console (graphic card) which should be used
2230 as the initial boot-console.
2231 See also comment in drivers/video/console/sticore.c.
2234 See comment in drivers/video/console/sticore.c.
2237 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2241 Control how the NFS server code allocates CPUs to
2242 service thread pools. Depending on how many NICs
2243 you have and where their interrupts are bound, this
2244 option will affect which CPUs will do NFS serving.
2245 Note: this parameter cannot be changed while the
2246 NFS server is running.
2248 auto the server chooses an appropriate mode
2249 automatically using heuristics
2250 global a single global pool contains all CPUs
2251 percpu one pool for each CPU
2252 pernode one pool for each NUMA node (equivalent
2253 to global on non-NUMA machines)
2255 swiotlb= [IA-64] Number of I/O TLB slabs
2259 sym53c416= [HW,SCSI]
2260 See header of drivers/scsi/sym53c416.c.
2262 sysrq_always_enabled
2264 Ignore sysrq setting - this boot parameter will
2265 neutralize any effect of /proc/sys/kernel/sysrq.
2266 Useful for debugging.
2269 See header of drivers/scsi/t128.c.
2273 test_suspend= [SUSPEND]
2274 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2275 standby suspend) as the system sleep state to briefly
2276 enter during system startup. The system is woken from
2277 this state using a wakeup-capable RTC alarm.
2279 thash_entries= [KNL,NET]
2280 Set number of hash buckets for TCP connection
2282 thermal.act= [HW,ACPI]
2283 -1: disable all active trip points in all thermal zones
2284 <degrees C>: override all lowest active trip points
2286 thermal.crt= [HW,ACPI]
2287 -1: disable all critical trip points in all thermal zones
2288 <degrees C>: override all critical trip points
2290 thermal.nocrt= [HW,ACPI]
2291 Set to disable actions on ACPI thermal zone
2292 critical and hot trip points.
2294 thermal.off= [HW,ACPI]
2295 1: disable ACPI thermal control
2297 thermal.psv= [HW,ACPI]
2298 -1: disable all passive trip points
2299 <degrees C>: override all passive trip points to this value
2301 thermal.tzp= [HW,ACPI]
2302 Specify global default ACPI thermal zone polling rate
2303 <deci-seconds>: poll all this frequency
2304 0: no polling (default)
2307 See comment before function dc390_setup() in
2308 drivers/scsi/tmscsim.c.
2312 Specify if the kernel should make use of the cpu
2313 topology informations if the hardware supports these.
2314 The scheduler will make use of these informations and
2315 e.g. base its process migration decisions on it.
2320 trix= [HW,OSS] MediaTrix AudioTrix Pro
2322 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2324 tsc= Disable clocksource-must-verify flag for TSC.
2326 [x86] reliable: mark tsc clocksource as reliable, this
2327 disables clocksource verification at runtime.
2328 Used to enable high-resolution timer mode on older
2329 hardware, and in virtualized environment.
2331 turbografx.map[2|3]= [HW,JOY]
2332 TurboGraFX parallel port interface
2334 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2335 See also Documentation/input/joystick-parport.txt
2337 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2338 See header of drivers/scsi/u14-34f.c.
2347 [USB] Ignore overcurrent events (default N).
2348 Some badly-designed motherboards generate lots of
2349 bogus events, for ports that aren't wired to
2350 anything. Set this parameter to avoid log spamming.
2351 Note that genuine overcurrent events won't be
2356 Set unknown_nmi_panic=1 early on boot.
2358 usbcore.autosuspend=
2359 [USB] The autosuspend time delay (in seconds) used
2360 for newly-detected USB devices (default 2). This
2361 is the time required before an idle device will be
2362 autosuspended. Devices for which the delay is set
2363 to a negative value won't be autosuspended at all.
2365 usbcore.usbfs_snoop=
2366 [USB] Set to log all usbfs traffic (default 0 = off).
2368 usbcore.blinkenlights=
2369 [USB] Set to cycle leds on hubs (default 0 = off).
2371 usbcore.old_scheme_first=
2372 [USB] Start with the old device initialization
2373 scheme (default 0 = off).
2375 usbcore.use_both_schemes=
2376 [USB] Try the other device initialization scheme
2377 if the first one fails (default 1 = enabled).
2379 usbcore.initial_descriptor_timeout=
2380 [USB] Specifies timeout for the initial 64-byte
2381 USB_REQ_GET_DESCRIPTOR request in milliseconds
2382 (default 5000 = 5.0 seconds).
2385 [USBHID] The interval which mice are to be polled at.
2387 usb-storage.delay_use=
2388 [UMS] The delay in seconds before a new device is
2389 scanned for Logical Units (default 5).
2392 [UMS] A list of quirks entries to supplement or
2393 override the built-in unusual_devs list. List
2394 entries are separated by commas. Each entry has
2395 the form VID:PID:Flags where VID and PID are Vendor
2396 and Product ID values (4-digit hex numbers) and
2397 Flags is a set of characters, each corresponding
2398 to a common usb-storage quirk flag as follows:
2399 c = FIX_CAPACITY (decrease the reported
2400 device capacity by one sector);
2401 i = IGNORE_DEVICE (don't bind to this
2403 l = NOT_LOCKABLE (don't try to lock and
2404 unlock ejectable media);
2405 m = MAX_SECTORS_64 (don't transfer more
2406 than 64 sectors = 32 KB at a time);
2407 r = IGNORE_RESIDUE (the device reports
2408 bogus residue values);
2409 s = SINGLE_LUN (the device has only one
2411 w = NO_WP_DETECT (don't test whether the
2412 medium is write-protected).
2413 Example: quirks=0419:aaf5:rl,0421:0433:rc
2415 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2416 kernel's map of available physical RAM.
2418 vdso= [X86-32,SH,x86-64]
2419 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2420 vdso=1: enable VDSO (default)
2421 vdso=0: disable VDSO mapping
2423 vdso32= [X86-32,X86-64]
2424 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2425 vdso32=1: enable 32-bit VDSO (default)
2426 vdso32=0: disable 32-bit VDSO mapping
2429 vector=percpu: enable percpu vector domain
2431 video= [FB] Frame buffer configuration
2432 See Documentation/fb/modedb.txt.
2434 vga= [BOOT,X86-32] Select a particular video mode
2435 See Documentation/x86/i386/boot.txt and
2436 Documentation/svga.txt.
2437 Use vga=ask for menu.
2438 This is actually a boot loader parameter; the value is
2439 passed to the kernel using a special protocol.
2441 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2442 size of <nn>. This can be used to increase the
2443 minimum size (128MB on x86). It can also be used to
2444 decrease the size and leave more room for directly
2447 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2450 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2453 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2456 waveartist= [HW,OSS]
2457 Format: <io>,<irq>,<dma>,<dma2>
2460 See header of drivers/scsi/wd33c93.c.
2463 See header of drivers/scsi/wd7000.c.
2466 See Documentation/watchdog/wdt.txt.
2468 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2469 xd_geo= See header of drivers/block/xd.c.
2471 xirc2ps_cs= [NET,PCMCIA]
2473 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2475 norandmaps Don't use address space randomization. Equivalent to
2476 echo 0 > /proc/sys/kernel/randomize_va_space
2478 ______________________________________________________________________
2482 Add documentation for ALSA options.
2483 Add more DRM drivers.