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/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 | rsdt }
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.
144 rsdt -- prefer RSDT over (default) XSDT
146 See also Documentation/power/pm.txt, pci=noacpi
148 acpi_apic_instance= [ACPI, IOAPIC]
150 2: use 2nd APIC table, if available
151 1,0: use 1st APIC table
154 acpi_sleep= [HW,ACPI] Sleep options
155 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
156 old_ordering, s4_nonvs }
157 See Documentation/power/video.txt for information on
159 s3_beep is for debugging; it makes the PC's speaker beep
160 as soon as the kernel's real-mode entry point is called.
161 s4_nohwsig prevents ACPI hardware signature from being
162 used during resume from hibernation.
163 old_ordering causes the ACPI 1.0 ordering of the _PTS
164 control method, with respect to putting devices into
165 low power states, to be enforced (the ACPI 2.0 ordering
166 of _PTS is used by default).
167 s4_nonvs prevents the kernel from saving/restoring the
168 ACPI NVS memory during hibernation.
170 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
171 Format: { level | edge | high | low }
173 acpi_irq_balance [HW,ACPI]
174 ACPI will balance active IRQs
177 acpi_irq_nobalance [HW,ACPI]
178 ACPI will not move active IRQs (default)
181 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
183 Format: <irq>,<irq>...
185 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
186 Format: <irq>,<irq>...
188 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
190 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
191 Format: To spoof as Windows 98: ="Microsoft Windows"
193 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
194 acpi_osi="string1" # add string1 -- only one string
195 acpi_osi="!string2" # remove built-in string2
196 acpi_osi= # disable all strings
198 acpi_serialize [HW,ACPI] force serialization of AML methods
200 acpi_skip_timer_override [HW,ACPI]
201 Recognize and ignore IRQ0/pin2 Interrupt Override.
202 For broken nForce2 BIOS resulting in XT-PIC timer.
203 acpi_use_timer_override [HW,ACPI]
204 Use timer override. For some broken Nvidia NF5 boards
205 that require a timer override, but don't have
208 acpi_backlight= [HW,ACPI]
209 acpi_backlight=vendor
211 If set to vendor, prefer vendor specific driver
212 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
213 of the ACPI video.ko driver.
215 acpi_display_output= [HW,ACPI]
216 acpi_display_output=vendor
217 acpi_display_output=video
220 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
221 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
223 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
224 debug output. Bits in debug_layer correspond to a
225 _COMPONENT in an ACPI source file, e.g.,
226 #define _COMPONENT ACPI_PCI_COMPONENT
227 Bits in debug_level correspond to a level in
228 ACPI_DEBUG_PRINT statements, e.g.,
229 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
230 The debug_level mask defaults to "info". See
231 Documentation/acpi/debug.txt for more information about
232 debug layers and levels.
234 Enable processor driver info messages:
235 acpi.debug_layer=0x20000000
236 Enable PCI/PCI interrupt routing info messages:
237 acpi.debug_layer=0x400000
238 Enable AML "Debug" output, i.e., stores to the Debug
239 object while interpreting AML:
240 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
241 Enable all messages related to ACPI hardware:
242 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
244 Some values produce so much output that the system is
245 unusable. The "log_buf_len" parameter may be useful
246 if you need to capture more output.
248 acpi.power_nocheck= [HW,ACPI]
249 Format: 1/0 enable/disable the check of power state.
250 On some bogus BIOS the _PSC object/_STA object of
251 power resource can't return the correct device power
252 state. In such case it is unneccessary to check its
253 power state again in power transition.
254 1 : disable the power state check
256 acpi_pm_good [X86-32,X86-64]
257 Override the pmtimer bug detection: force the kernel
258 to assume that this machine's pmtimer latches its value
259 and always returns good values.
262 { off | try_unsupported }
263 off: disable AGP support
264 try_unsupported: try to drive unsupported chipsets
265 (may crash computer or cause data corruption)
267 enable_timer_pin_1 [i386,x86-64]
268 Enable PIN 1 of APIC timer
269 Can be useful to work around chipset bugs
270 (in particular on some ATI chipsets).
271 The kernel tries to set a reasonable default.
273 disable_timer_pin_1 [i386,x86-64]
274 Disable PIN 1 of APIC timer
275 Can be useful to work around chipset bugs.
278 Format: <io>,<irq>,<dma>,<dma2>,<type>
281 See header of drivers/scsi/advansys.c.
283 advwdt= [HW,WDT] Advantech WDT
284 Format: <iostart>,<iostop>
286 aedsp16= [HW,OSS] Audio Excel DSP 16
287 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
288 See also header of sound/oss/aedsp16.c.
291 See Documentation/scsi/aha152x.txt.
294 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
297 See Documentation/scsi/aic7xxx.txt.
300 See Documentation/scsi/aic79xx.txt.
302 amd_iommu= [HW,X86-84]
303 Pass parameters to the AMD IOMMU driver in the system.
305 isolate - enable device isolation (each device, as far
306 as possible, will get its own protection
308 share - put every device behind one IOMMU into the
309 same protection domain
310 fullflush - enable flushing of IO/TLB entries when
311 they are unmapped. Otherwise they are
312 flushed before they will be reused, which
315 amd_iommu_size= [HW,X86-64]
316 Define the size of the aperture for the AMD IOMMU
317 driver. Possible values are:
318 '32M', '64M' (default), '128M', '256M', '512M', '1G'
320 amijoy.map= [HW,JOY] Amiga joystick support
321 Map of devices attached to JOY0DAT and JOY1DAT
323 See also Documentation/kernel/input/joystick.txt
325 analog.map= [HW,JOY] Analog joystick and gamepad support
326 Specifies type or capabilities of an analog joystick
327 connected to one of 16 gameports
328 Format: <type1>,<type2>,..<type16>
331 Power management functions (SPARCstation-4/5 + deriv.)
333 Disable APC CPU standby support. SPARCstation-Fox does
334 not play well with APC CPU idle - disable it if you have
335 APC and your system crashes randomly.
337 apic= [APIC,i386] Advanced Programmable Interrupt Controller
338 Change the output verbosity whilst booting
339 Format: { quiet (default) | verbose | debug }
340 Change the amount of debugging information output
341 when initialising the APIC and IO-APIC components.
343 apm= [APM] Advanced Power Management
344 See header of arch/x86/kernel/apm_32.c.
346 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
347 Format: <io>,<irq>,<nodeID>
351 atarimouse= [HW,MOUSE] Atari Mouse
353 atascsi= [HW,SCSI] Atari SCSI
355 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
356 EzKey and similar keyboards
358 atkbd.reset= [HW] Reset keyboard during initialization
360 atkbd.set= [HW] Select keyboard code set
361 Format: <int> (2 = AT (default), 3 = PS/2)
363 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
366 atkbd.softraw= [HW] Choose between synthetic and real raw mode
367 Format: <bool> (0 = real, 1 = synthetic (default))
369 atkbd.softrepeat= [HW]
370 Use software keyboard repeat
374 baycom_epp= [HW,AX25]
377 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
379 See header of drivers/net/hamradio/baycom_par.c.
381 baycom_ser_fdx= [HW,AX25]
382 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
383 Format: <io>,<irq>,<mode>[,<baud>]
384 See header of drivers/net/hamradio/baycom_ser_fdx.c.
386 baycom_ser_hdx= [HW,AX25]
387 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
388 Format: <io>,<irq>,<mode>
389 See header of drivers/net/hamradio/baycom_ser_hdx.c.
391 boot_delay= Milliseconds to delay each printk during boot.
392 Values larger than 10 seconds (10000) are changed to
396 bootmem_debug [KNL] Enable bootmem allocator debug messages.
398 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
399 bttv.radio= Most important insmod options are available as
401 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
402 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
405 See drivers/scsi/BusLogic.c, comment before function
406 BusLogic_ParseDriverOptions().
408 c101= [NET] Moxa C101 synchronous serial card
410 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
411 Sometimes CPU hardware bugs make them report the cache
412 size incorrectly. The kernel will attempt work arounds
413 to fix known problems, but for some CPUs it is not
414 possible to determine what the correct size should be.
415 This option provides an override for these situations.
417 security= [SECURITY] Choose a security module to enable at boot.
418 If this boot parameter is not specified, only the first
419 security module asking for security registration will be
420 loaded. An invalid security module name will be treated
421 as if no module has been chosen.
424 [SECURITY] Disable capabilities. This would normally
425 be used only if an alternative security model is to be
426 configured. Potentially dangerous and should only be
427 used if you are entirely sure of the consequences.
429 ccw_timeout_log [S390]
430 See Documentation/s390/CommonIO for details.
432 cgroup_disable= [KNL] Disable a particular controller
433 Format: {name of the controller(s) to disable}
434 {Currently supported controllers - "memory"}
436 checkreqprot [SELINUX] Set initial checkreqprot flag value.
437 Format: { "0" | "1" }
438 See security/selinux/Kconfig help text.
439 0 -- check protection applied by kernel (includes
440 any implied execute protection).
441 1 -- check protection requested by application.
442 Default value is set via a kernel config option.
443 Value can be changed at runtime via
444 /selinux/checkreqprot.
447 See Documentation/s390/CommonIO for details.
449 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
451 Forces specified clocksource (if available) to be used
452 when calculating gettimeofday(). If specified
453 clocksource is not available, it defaults to PIT.
454 Format: { pit | tsc | cyclone | pmtmr }
456 clocksource= [GENERIC_TIME] Override the default clocksource
458 Override the default clocksource and use the clocksource
459 with the name specified.
460 Some clocksource names to choose from, depending on
462 [all] jiffies (this is the base, fallback clocksource)
464 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
465 pxa_timer,timer3,32k_counter,timer0_1
467 [X86-32] pit,hpet,tsc,vmi-timer;
468 scx200_hrt on Geode; cyclone on IBM x440
476 clearcpuid=BITNUM [X86]
477 Disable CPUID feature X for the kernel. See
478 arch/x86/include/asm/cpufeature.h for the valid bit
479 numbers. Note the Linux specific bits are not necessarily
480 stable over kernel options, but the vendor specific
482 Also note that user programs calling CPUID directly
483 or using the feature without checking anything
484 will still see it. This just prevents it from
485 being used by the kernel or shown in /proc/cpuinfo.
486 Also note the kernel might malfunction if you disable
489 code_bytes [IA32/X86_64] How many bytes of object code to print
494 hpet= [X86-32,HPET] option to control HPET usage
495 Format: { enable (default) | disable | force |
497 disable: disable HPET and use PIT instead
498 force: allow force enabled of undocumented chips (ICH4,
500 verbose: show contents of HPET registers during setup
502 com20020= [HW,NET] ARCnet - COM20020 chipset
504 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
506 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
510 ARCnet - COM90xx chipset (memory-mapped buffers)
511 Format: <io>[,<irq>[,<memstart>]]
513 condev= [HW,S390] console device
516 console= [KNL] Output console device and options.
518 tty<n> Use the virtual console device <n>.
522 Use the specified serial port. The options are of
523 the form "bbbbpnf", where "bbbb" is the baud rate,
524 "p" is parity ("n", "o", or "e"), "n" is number of
525 bits, and "f" is flow control ("r" for RTS or
526 omit it). Default is "9600n8".
528 See Documentation/serial-console.txt for more
530 Documentation/networking/netconsole.txt for an
533 uart[8250],io,<addr>[,options]
534 uart[8250],mmio,<addr>[,options]
535 Start an early, polled-mode console on the 8250/16550
536 UART at the specified I/O port or MMIO address,
537 switching to the matching ttyS device later. The
538 options are the same as for ttyS, above.
540 If the device connected to the port is not a TTY but a braille
541 device, prepend "brl," before the device type, for instance
543 For now, only VisioBraille is supported.
545 earlycon= [KNL] Output early console device and options.
546 uart[8250],io,<addr>[,options]
547 uart[8250],mmio,<addr>[,options]
548 Start an early, polled-mode console on the 8250/16550
549 UART at the specified I/O port or MMIO address.
550 The options are the same as for ttyS, above.
553 [HW] Never suspend the console
554 Disable suspending of consoles during suspend and
555 hibernate operations. Once disabled, debugging
556 messages can reach various consoles while the rest
557 of the system is being put to sleep (ie, while
558 debugging driver suspend/resume hooks). This may
559 not work reliably with all consoles, but is known
560 to work with serial and VGA consoles.
563 [KNL] Change the default value for
564 /proc/<pid>/coredump_filter.
565 See also Documentation/filesystems/proc.txt.
567 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
569 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
571 crashkernel=nn[KMG]@ss[KMG]
572 [KNL] Reserve a chunk of physical memory to
573 hold a kernel to switch to with kexec on panic.
575 crashkernel=range1:size1[,range2:size2,...][@offset]
576 [KNL] Same as above, but depends on the memory
577 in the running system. The syntax of range is
578 start-[end] where start and end are both
579 a memory unit (amount[KMG]). See also
580 Documentation/kdump/kdump.txt for a example.
585 cs89x0_media= [HW,NET]
586 Format: { rj45 | aui | bnc }
589 See header of drivers/s390/block/dasd_devmap.c.
591 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
592 (one device per port)
593 Format: <port#>,<type>
594 See also Documentation/input/joystick-parport.txt
596 debug [KNL] Enable kernel debugging (events log level).
599 [KNL] verbose self-tests
601 Print debugging info while doing the locking API
603 We default to 0 (no extra messages), setting it to
604 1 will print _a lot_ more information - normally
605 only useful to kernel developers.
607 debug_objects [KNL] Enable object debugging
609 debugpat [X86] Enable PAT debugging
611 decnet.addr= [HW,NET]
612 Format: <area>[,<node>]
613 See also Documentation/networking/decnet.txt.
616 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
617 Change the default blue palette of the console.
618 This is a 16-member array composed of values
622 Format: <green0>,<green1>,<green2>,...,<green15>
623 Change the default green palette of the console.
624 This is a 16-member array composed of values
628 Format: <red0>,<red1>,<red2>,...,<red15>
629 Change the default red palette of the console.
630 This is a 16-member array composed of values
636 Set system-wide default UTF-8 mode for all tty's.
637 Default is 1, i.e. UTF-8 mode is enabled for all
638 newly opened terminals.
641 Set number of hash buckets for dentry cache.
644 IO parameters + enable/disable command.
646 digiepca= [HW,SERIAL]
647 See drivers/char/README.epca and
648 Documentation/serial/digiepca.txt.
650 disable_mtrr_cleanup [X86]
651 enable_mtrr_cleanup [X86]
652 The kernel tries to adjust MTRR layout from continuous
653 to discrete, to make X server driver able to add WB
654 entry later. This parameter enables/disables that.
656 mtrr_chunk_size=nn[KMG] [X86]
657 used for mtrr cleanup. It is largest continous chunk
658 that could hold holes aka. UC entries.
660 mtrr_gran_size=nn[KMG] [X86]
661 Used for mtrr cleanup. It is granularity of mtrr block.
663 Large value could prevent small alignment from
666 mtrr_spare_reg_nr=n [X86]
668 Range: 0,7 : spare reg number
670 Used for mtrr cleanup. It is spare mtrr entries number.
671 Set to 2 or more if your graphical card needs more.
673 disable_mtrr_trim [X86, Intel and AMD only]
674 By default the kernel will trim any uncacheable
675 memory out of your available memory pool based on
676 MTRR settings. This parameter disables that behavior,
677 possibly causing your machine to run very slowly.
679 dmasound= [HW,OSS] Sound subsystem buffers
685 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
687 earlyprintk=serial[,ttySn[,baudrate]]
690 Append ",keep" to not disable it when the real console
693 Only vga or serial or usb debug port at a time.
695 Currently only ttyS0 and ttyS1 are supported.
697 Interaction with the standard serial driver is not
700 The VGA output is eventually overwritten by the real
706 Format: {"off" | "on" | "skip[mbr]"}
708 eisa_irq_edge= [PARISC,HW]
709 See header of drivers/parisc/eisa.c.
712 See comment before function elanfreq_setup() in
713 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
716 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
717 See Documentation/block/as-iosched.txt and
718 Documentation/block/deadline-iosched.txt for details.
720 elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
721 Specifies physical address of start of kernel core
722 image elf header. Generally kexec loader will
723 pass this option to capture kernel.
724 See Documentation/kdump/kdump.txt for details.
726 enforcing [SELINUX] Set initial enforcing status.
728 See security/selinux/Kconfig help text.
729 0 -- permissive (log only, no denials).
730 1 -- enforcing (deny and log).
732 Value can be changed at runtime via /selinux/enforce.
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 terminal devices. Valid values: 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-core.nodma= [HW] (E)IDE subsystem
874 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
875 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
876 .chs .ignore_cable are additional options
877 See Documentation/ide/ide.txt.
879 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
880 See Documentation/ide/ide.txt.
883 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
884 Poll forces a polling idle loop that can slightly
885 improve the performance of waking up a idle CPU, but
886 will use a lot of power and make the system run hot.
888 idle=mwait: On systems which support MONITOR/MWAIT but
889 the kernel chose to not use it because it doesn't save
890 as much power as a normal idle loop, use the
891 MONITOR/MWAIT idle loop anyways. Performance should be
892 the same as idle=poll.
893 idle=halt: Halt is forced to be used for CPU idle.
894 In such case C2/C3 won't be used again.
895 idle=nomwait: Disable mwait for CPU C-states
897 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
898 Claim all unknown PCI IDE storage controllers.
900 ignore_loglevel [KNL]
901 Ignore loglevel setting - this will print /all/
902 kernel messages to the console. Useful for debugging.
905 Set number of hash buckets for inode cache.
908 See header of drivers/scsi/in2000.c.
912 Run specified binary instead of /sbin/init as init
915 initcall_debug [KNL] Trace initcalls as they are executed. Useful
916 for working out where the kernel is dying during
919 initrd= [BOOT] Specify the location of the initial ramdisk
921 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
926 iomem= Disable strict checking of access to MMIO memory
927 strict regions from userspace.
943 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
945 Enable intel iommu driver.
947 Disable intel iommu driver.
948 igfx_off [Default Off]
949 By default, gfx is mapped as normal device. If a gfx
950 device has a dedicated DMAR unit, the DMAR unit is
951 bypassed by not enabling DMAR with this option. In
952 this case, gfx device will use physical address for
955 With this option iommu will not optimize to look
956 for io virtual address below 32 bit forcing dual
957 address cycle on pci bus for cards supporting greater
958 than 32 bit addressing. The default is to look
959 for translation below 32 bit and if not available
960 then look in the higher range.
962 With this option on every unmap_single operation will
963 result in a hardware IOTLB flush operation as opposed
964 to batching them for performance.
966 io_delay= [X86-32,X86-64] I/O delay method
968 Standard port 0x80 based delay
970 Alternate port 0xed based delay (needed on some systems)
972 Simple two microseconds delay
976 io7= [HW] IO7 for Marvel based alpha systems
977 See comment before marvel_specify_io7 in
978 arch/alpha/kernel/core_marvel.c.
981 See Documentation/filesystems/nfsroot.txt.
983 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
984 See comment before ip2_setup() in
985 drivers/char/ip2/ip2base.c.
987 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
988 See header of drivers/scsi/ips.c.
990 ports= [IP_VS_FTP] IPVS ftp helper module
992 Up to 8 (IP_VS_APP_MAX_PORTS) ports
994 Format: <port>,<port>....
997 When an interrupt is not handled search all handlers
998 for it. Intended to get systems with badly broken
1002 When an interrupt is not handled search all handlers
1003 for it. Also check all handlers each timer
1004 interrupt. Intended to get systems with badly broken
1008 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1010 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1012 <cpu number>,...,<cpu number>
1014 <cpu number>-<cpu number>
1015 (must be a positive range in ascending order)
1017 <cpu number>,...,<cpu number>-<cpu number>
1019 This option can be used to specify one or more CPUs
1020 to isolate from the general SMP balancing and scheduling
1021 algorithms. You can move a process onto or off an
1022 "isolated" CPU via the CPU affinity syscalls or cpuset.
1023 <cpu number> begins at 0 and the maximum value is
1024 "number of CPUs in system - 1".
1026 This option is the preferred way to isolate CPUs. The
1027 alternative -- manually setting the CPU mask of all
1028 tasks in the system -- can cause problems and
1029 suboptimal load balancer performance.
1033 js= [HW,JOY] Analog joystick
1034 See Documentation/input/joystick.txt.
1036 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1037 specifies the amount of memory usable by the kernel
1038 for non-movable allocations. The requested amount is
1039 spread evenly throughout all nodes in the system. The
1040 remaining memory in each node is used for Movable
1041 pages. In the event, a node is too small to have both
1042 kernelcore and Movable pages, kernelcore pages will
1043 take priority and other nodes will have a larger number
1044 of kernelcore pages. The Movable zone is used for the
1045 allocation of pages that may be reclaimed or moved
1046 by the page migration subsystem. This means that
1047 HugeTLB pages may not be allocated from this zone.
1048 Note that allocations like PTEs-from-HighMem still
1049 use the HighMem zone if it exists, and the Normal
1050 zone if it does not.
1052 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
1053 is similar to kernelcore except it specifies the
1054 amount of memory used for migratable allocations.
1055 If both kernelcore and movablecore is specified,
1056 then kernelcore will be at *least* the specified
1057 value but may be more. If movablecore on its own
1058 is specified, the administrator must be careful
1059 that the amount of memory usable for all allocations
1064 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1067 kgdboc= [HW] kgdb over consoles.
1068 Requires a tty driver that supports console polling.
1069 (only serial suported for now)
1070 Format: <serial_device>[,baud]
1072 kmac= [MIPS] korina ethernet MAC address.
1073 Configure the RouterBoard 532 series on-chip
1074 Ethernet adapter MAC address.
1080 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1083 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
1086 libata.dma= [LIBATA] DMA control
1087 libata.dma=0 Disable all PATA and SATA DMA
1088 libata.dma=1 PATA and SATA Disk DMA only
1089 libata.dma=2 ATAPI (CDROM) DMA only
1090 libata.dma=4 Compact Flash DMA only
1091 Combinations also work, so libata.dma=3 enables DMA
1092 for disks and CDROMs, but not CFs.
1094 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1098 libata.force= [LIBATA] Force configurations. The format is comma
1099 separated list of "[ID:]VAL" where ID is
1100 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1101 matching port, link or device. Basically, it matches
1102 the ATA ID string printed on console by libata. If
1103 the whole ID part is omitted, the last PORT and DEVICE
1104 values are used. If ID hasn't been specified yet, the
1105 configuration applies to all ports, links and devices.
1107 If only DEVICE is omitted, the parameter applies to
1108 the port and all links and devices behind it. DEVICE
1109 number of 0 either selects the first device or the
1110 first fan-out link behind PMP device. It does not
1111 select the host link. DEVICE number of 15 selects the
1112 host link and device attached to it.
1114 The VAL specifies the configuration to force. As long
1115 as there's no ambiguity shortcut notation is allowed.
1116 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1117 The following configurations can be forced.
1119 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1120 Any ID with matching PORT is used.
1122 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1124 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1125 udma[/][16,25,33,44,66,100,133] notation is also
1128 * [no]ncq: Turn on or off NCQ.
1130 * nohrst, nosrst, norst: suppress hard, soft
1133 If there are multiple matching configurations changing
1134 the same attribute, the last one is used.
1136 lmb=debug [KNL] Enable lmb debug messages.
1138 load_ramdisk= [RAM] List of ramdisks to load from floppy
1139 See Documentation/blockdev/ramdisk.txt.
1141 lockd.nlm_grace_period=P [NFS] Assign grace period.
1144 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1147 lockd.nlm_timeout=T [NFS] Assign timeout value.
1150 lockd.nlm_udpport=M [NFS] Assign UDP port.
1153 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1156 loglevel= All Kernel Messages with a loglevel smaller than the
1157 console loglevel will be printed to the console. It can
1158 also be changed with klogd or other programs. The
1159 loglevels are defined as follows:
1161 0 (KERN_EMERG) system is unusable
1162 1 (KERN_ALERT) action must be taken immediately
1163 2 (KERN_CRIT) critical conditions
1164 3 (KERN_ERR) error conditions
1165 4 (KERN_WARNING) warning conditions
1166 5 (KERN_NOTICE) normal but significant condition
1167 6 (KERN_INFO) informational
1168 7 (KERN_DEBUG) debug-level messages
1170 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1171 Format: { n | nk | nM }
1172 n must be a power of two. The default size
1173 is set in the kernel config file.
1175 logo.nologo [FB] Disables display of the built-in Linux logo.
1176 This may be used to provide more screen space for
1177 kernel log messages and is useful when debugging
1178 kernel boot problems.
1180 lp=0 [LP] Specify parallel ports to use, e.g,
1181 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1182 lp=reset first parallel port). 'lp=0' disables the
1183 lp=auto printer driver. 'lp=reset' (which can be
1184 specified in addition to the ports) causes
1185 attached printers to be reset. Using
1186 lp=port1,port2,... specifies the parallel ports
1187 to associate lp devices with, starting with
1188 lp0. A port specification may be 'none' to skip
1189 that lp device, or a parport name such as
1190 'parport0'. Specifying 'lp=auto' instead of a
1191 port specification list means that device IDs
1192 from each port should be examined, to see if
1193 an IEEE 1284-compliant printer is attached; if
1194 so, the driver will manage that printer.
1195 See also header of drivers/char/lp.c.
1198 Sets loops_per_jiffy to given constant, thus avoiding
1199 time-consuming boot-time autodetection (up to 250 ms per
1200 CPU). 0 enables autodetection (default). To determine
1201 the correct value for your kernel, boot with normal
1202 autodetection and see what value is printed. Note that
1203 on SMP systems the preset will be applied to all CPUs,
1204 which is likely to cause problems if your CPUs need
1205 significantly divergent settings. An incorrect value
1206 will cause delays in the kernel to be wrong, leading to
1207 unpredictable I/O errors and other breakage. Although
1208 unlikely, in the extreme case this might damage your
1212 Format: <io>,<irq>,<dma>
1214 mac5380= [HW,SCSI] Format:
1215 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1217 machvec= [IA64] Force the use of a particular machine-vector
1218 (machvec) in a generic kernel.
1219 Example: machvec=hpzx1_swiotlb
1221 max_loop= [LOOP] Maximum number of loopback devices that can
1225 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1226 should make use of. maxcpus=n : n >= 0 limits the
1227 kernel to using 'n' processors. n=0 is a special case,
1228 it is equivalent to "nosmp", which also disables
1231 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater than
1232 or equal to this physical address is ignored.
1234 max_luns= [SCSI] Maximum number of LUNs to probe.
1235 Should be between 1 and 2^32-1.
1238 [SCSI] Maximum number of LUNs received.
1239 Should be between 1 and 16384.
1243 mce [X86-32] Machine Check Exception
1245 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1247 md= [HW] RAID subsystems devices and level
1248 See Documentation/md.txt.
1251 Format: <first>,<last>
1252 Specifies range of consoles to be captured by the MDA.
1254 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1255 Amount of memory to be used when the kernel is not able
1256 to see the whole system memory or for test.
1257 [X86-32] Use together with memmap= to avoid physical
1258 address space collisions. Without memmap= PCI devices
1259 could be placed at addresses belonging to unused RAM.
1261 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1265 [KNL,SH] Allow user to override the default size for
1266 per-device physically contiguous DMA buffers.
1268 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1269 E820 memory map, as specified by the user.
1270 Such memmap=exactmap lines can be constructed based on
1271 BIOS output or other requirements. See the memmap=nn@ss
1274 memmap=nn[KMG]@ss[KMG]
1275 [KNL] Force usage of a specific region of memory
1276 Region of memory to be used, from ss to ss+nn.
1278 memmap=nn[KMG]#ss[KMG]
1279 [KNL,ACPI] Mark specific memory as ACPI data.
1280 Region of memory to be used, from ss to ss+nn.
1282 memmap=nn[KMG]$ss[KMG]
1283 [KNL,ACPI] Mark specific memory as reserved.
1284 Region of memory to be used, from ss to ss+nn.
1285 Example: Exclude memory from 0x18690000-0x1869ffff
1286 memmap=64K$0x18690000
1288 memmap=0x10000$0x18690000
1290 memory_corruption_check=0/1 [X86]
1291 Some BIOSes seem to corrupt the first 64k of
1292 memory when doing things like suspend/resume.
1293 Setting this option will scan the memory
1294 looking for corruption. Enabling this will
1295 both detect corruption and prevent the kernel
1296 from using the memory being corrupted.
1297 However, its intended as a diagnostic tool; if
1298 repeatable BIOS-originated corruption always
1299 affects the same memory, you can use memmap=
1300 to prevent the kernel from using that memory.
1302 memory_corruption_check_size=size [X86]
1303 By default it checks for corruption in the low
1304 64k, making this memory unavailable for normal
1305 use. Use this parameter to scan for
1306 corruption in more or less memory.
1308 memory_corruption_check_period=seconds [X86]
1309 By default it checks for corruption every 60
1310 seconds. Use this parameter to check at some
1311 other rate. 0 disables periodic checking.
1313 memtest= [KNL,X86] Enable memtest
1315 range: 0,4 : pattern number
1316 default : 0 <disable>
1318 meye.*= [HW] Set MotionEye Camera parameters
1319 See Documentation/video4linux/meye.txt.
1321 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1322 Multi-Function General Purpose Timers on AMD Geode
1325 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1326 the BIOS has incorrectly applied a workaround. TinyBIOS
1327 version 0.98 is known to be affected, 0.99 fixes the
1328 problem by letting the user disable the workaround.
1332 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1333 physical address is ignored.
1336 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1337 parameter allows control of the logging verbosity for
1338 the additional memory initialisation checks. A value
1339 of 0 disables mminit logging and a level of 4 will
1340 log everything. Information is printed at KERN_DEBUG
1341 so loglevel=8 may also need to be specified.
1344 [MOUSE] Maximum time between finger touching and
1345 leaving touchpad surface for touch to be considered
1346 a tap and be reported as a left button click (for
1347 touchpads working in absolute mode only).
1349 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1350 reporting absolute coordinates, such as tablets
1351 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1352 reporting absolute coordinates, such as tablets
1357 MTD_Partition= [MTD]
1358 Format: <name>,<region-number>,<size>,<offset>
1360 MTD_Region= [MTD] Format:
1361 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1364 See drivers/mtd/cmdlinepart.c.
1367 ARM/S3C2412 JIVE boot control
1369 See arch/arm/mach-s3c2412/mach-jive.c
1371 mtouchusb.raw_coordinates=
1372 [HW] Make the MicroTouch USB driver use raw coordinates
1373 ('y', default) or cooked coordinates ('n')
1375 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1378 See header of drivers/scsi/NCR_D700.c.
1382 ncr53c400= [HW,SCSI]
1384 ncr53c400a= [HW,SCSI]
1386 ncr53c406a= [HW,SCSI]
1388 ncr53c8xx= [HW,SCSI]
1390 netdev= [NET] Network devices parameters
1391 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1392 Note that mem_start is often overloaded to mean
1393 something different and driver-specific.
1394 This usage is only documented in each driver source
1398 [NETFILTER] Enable connection tracking flow accounting
1399 0 to disable accounting
1400 1 to enable accounting
1401 Default value depends on CONFIG_NF_CT_ACCT that is
1402 going to be removed in 2.6.29.
1405 See Documentation/filesystems/nfsroot.txt.
1407 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1408 See Documentation/filesystems/nfsroot.txt.
1410 nfs.callback_tcpport=
1411 [NFS] set the TCP port on which the NFSv4 callback
1412 channel should listen.
1414 nfs.idmap_cache_timeout=
1415 [NFS] set the maximum lifetime for idmapper cache
1419 [NFS] enable 64-bit inode numbers.
1420 If zero, the NFS client will fake up a 32-bit inode
1421 number for the readdir() and stat() syscalls instead
1422 of returning the full 64-bit number.
1423 The default is to return 64-bit inode numbers.
1425 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1426 when a NMI is triggered.
1427 Format: [state][,regs][,debounce][,die]
1429 nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
1430 Format: [panic,][num]
1432 0 - turn nmi_watchdog off
1433 1 - use the IO-APIC timer for the NMI watchdog
1434 2 - use the local APIC for the NMI watchdog using
1435 a performance counter. Note: This will use one performance
1436 counter and the local APIC's performance vector.
1437 When panic is specified panic when an NMI watchdog timeout occurs.
1438 This is useful when you use a panic=... timeout and need the box
1440 Instead of 1 and 2 it is possible to use the following
1441 symbolic names: lapic and ioapic
1442 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1444 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1445 emulation library even if a 387 maths coprocessor
1448 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1449 caches in the slab allocator. Saves per-node memory,
1450 but will impact performance.
1454 noapic [SMP,APIC] Tells the kernel to not make use of any
1455 IOAPICs that may be present in the system.
1457 nobats [PPC] Do not use BATs for mapping kernel lowmem
1458 on "Classic" PPC cores.
1462 nodelayacct [KNL] Disable per-task delay accounting
1464 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1466 nodsp [SH] Disable hardware DSP at boot time.
1468 noefi [X86-32,X86-64] Disable EFI runtime services support.
1472 noexec [X86-32,X86-64]
1473 On X86-32 available only on PAE configured kernels.
1474 noexec=on: enable non-executable mappings (default)
1475 noexec=off: disable non-executable mappings
1478 This affects only 32-bit executables.
1479 noexec32=on: enable non-executable mappings (default)
1480 read doesn't imply executable mappings
1481 noexec32=off: disable non-executable mappings
1482 read implies executable mappings
1484 nofpu [SH] Disable hardware FPU at boot time.
1486 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1487 register save and restore. The kernel will only save
1488 legacy floating-point registers on task switch.
1490 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1494 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1495 instruction doesn't work correctly and not to
1498 no_file_caps Tells the kernel not to honor file capabilities. The
1499 only way then for a file to be executed with privilege
1500 is to be setuid root or executed by root.
1502 nohalt [IA-64] Tells the kernel not to use the power saving
1503 function PAL_HALT_LIGHT when idle. This increases
1504 power-consumption. On the positive side, it reduces
1505 interrupt wake-up latency, which may improve performance
1506 in certain environments such as networked servers or
1509 nohz= [KNL] Boottime enable/disable dynamic ticks
1510 Valid arguments: on, off
1513 noirqdebug [X86-32] Disables the code which attempts to detect and
1514 disable unhandled interrupt sources.
1516 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1517 broken timer IRQ sources.
1519 noisapnp [ISAPNP] Disables ISA PnP code.
1521 noinitrd [RAM] Tells the kernel not to load any configured
1526 nojitter [IA64] Disables jitter checking for ITC timers.
1528 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1530 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1532 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1534 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
1535 default x2apic cluster mode on platforms
1538 noltlbs [PPC] Do not use large page/tlb entries for kernel
1539 lowmem mapping on PPC40x.
1541 nomca [IA-64] Disable machine check abort handling
1543 nomce [X86-32] Machine Check Exception
1545 nomfgpt [X86-32] Disable Multi-Function General Purpose
1546 Timer usage (for AMD Geode machines).
1548 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1550 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1551 with UP alternatives
1553 noresidual [PPC] Don't use residual data on PReP machines.
1555 noresume [SWSUSP] Disables resume and restores original swap
1558 no-scroll [VGA] Disables scrollback.
1559 This is required for the Braillex ib80-piezo Braille
1560 reader made by F.H. Papenmeier (Germany).
1564 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1566 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1567 and disable the IO APIC. legacy for "maxcpus=0".
1569 nosoftlockup [KNL] Disable the soft-lockup detector.
1571 noswapaccount [KNL] Disable accounting of swap in memory resource
1572 controller. (See Documentation/controllers/memory.txt)
1574 nosync [HW,M68K] Disables sync negotiation for all devices.
1576 notsc [BUGS=X86-32] Disable Time Stamp Counter
1578 nousb [USB] Disable the USB subsystem
1582 nptcg= [IA64] Override max number of concurrent global TLB
1583 purges which is reported from either PAL_VM_SUMMARY or
1586 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1587 one of ['zone', 'node', 'default'] can be specified
1588 This can be set from sysctl after boot.
1589 See Documentation/sysctl/vm.txt for details.
1591 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1593 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1594 See Documentation/debugging-via-ohci1394.txt for more
1597 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1598 Rather than timing out after 20 ms if an EC
1599 command is not properly ACKed, override the length
1600 of the timeout. We have interrupts disabled while
1601 waiting for the ACK, so if this is set too high
1602 interrupts *may* be lost!
1607 oprofile.timer= [HW]
1608 Use timer interrupt instead of performance counters
1610 osst= [HW,SCSI] SCSI Tape Driver
1611 Format: <buffer_size>,<write_threshold>
1612 See also Documentation/scsi/st.txt.
1614 panic= [KNL] Kernel behaviour on panic
1617 parkbd.port= [HW] Parallel port number the keyboard adapter is
1618 connected to, default is 0.
1620 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1621 0 for XT, 1 for AT (default is AT).
1624 parport= [HW,PPT] Specify parallel ports. 0 disables.
1625 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1626 Use 'auto' to force the driver to use any
1627 IRQ/DMA settings detected (the default is to
1628 ignore detected IRQ/DMA settings because of
1629 possible conflicts). You can specify the base
1630 address, IRQ, and DMA settings; IRQ and DMA
1631 should be numbers, or 'auto' (for using detected
1632 settings on that particular port), or 'nofifo'
1633 (to avoid using a FIFO even if it is detected).
1634 Parallel ports are assigned in the order they
1635 are specified on the command line, starting
1638 parport_init_mode= [HW,PPT]
1639 Configure VIA parallel port to operate in
1640 a specific mode. This is necessary on Pegasos
1641 computer where firmware has no options for setting
1642 up parallel port mode and sets it to spp.
1643 Currently this function knows 686a and 8231 chips.
1644 Format: [spp|ps2|epp|ecp|ecpepp]
1646 pas2= [HW,OSS] Format:
1647 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1650 See header of drivers/scsi/pas16.c.
1653 Halt all CPUs after the first oops has been printed for
1654 the specified number of seconds. This is to be used if
1655 your oopses keep scrolling off the screen.
1660 See header of drivers/block/paride/pcd.c.
1661 See also Documentation/blockdev/paride.txt.
1663 pci=option[,option...] [PCI] various PCI subsystem options:
1664 off [X86] don't probe for the PCI bus
1665 bios [X86-32] force use of PCI BIOS, don't access
1666 the hardware directly. Use this if your machine
1667 has a non-standard PCI host bridge.
1668 nobios [X86-32] disallow use of PCI BIOS, only direct
1669 hardware access methods are allowed. Use this
1670 if you experience crashes upon bootup and you
1671 suspect they are caused by the BIOS.
1672 conf1 [X86] Force use of PCI Configuration
1674 conf2 [X86] Force use of PCI Configuration
1676 noaer [PCIE] If the PCIEAER kernel config parameter is
1677 enabled, this kernel boot option can be used to
1678 disable the use of PCIE advanced error reporting.
1679 nodomains [PCI] Disable support for multiple PCI
1680 root domains (aka PCI segments, in ACPI-speak).
1681 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1683 nomsi [MSI] If the PCI_MSI kernel config parameter is
1684 enabled, this kernel boot option can be used to
1685 disable the use of MSI interrupts system-wide.
1686 noioapicquirk [APIC] Disable all boot interrupt quirks.
1687 Safety option to keep boot IRQs enabled. This
1688 should never be necessary.
1689 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1690 primary IO-APIC for bridges that cannot disable
1691 boot IRQs. This fixes a source of spurious IRQs
1692 when the system masks IRQs.
1693 noioapicreroute [APIC] Disable workaround that uses the
1694 boot IRQ equivalent of an IRQ that connects to
1695 a chipset where boot IRQs cannot be disabled.
1696 The opposite of ioapicreroute.
1697 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1698 routing table. These calls are known to be buggy
1699 on several machines and they hang the machine
1700 when used, but on other computers it's the only
1701 way to get the interrupt routing table. Try
1702 this option if the kernel is unable to allocate
1703 IRQs or discover secondary PCI buses on your
1705 rom [X86] Assign address space to expansion ROMs.
1706 Use with caution as certain devices share
1707 address decoders between ROMs and other
1709 norom [X86] Do not assign address space to
1710 expansion ROMs that do not already have
1711 BIOS assigned address ranges.
1712 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1713 assigned automatically to PCI devices. You can
1714 make the kernel exclude IRQs of your ISA cards
1716 pirqaddr=0xAAAAA [X86] Specify the physical address
1717 of the PIRQ table (normally generated
1718 by the BIOS) if it is outside the
1719 F0000h-100000h range.
1720 lastbus=N [X86] Scan all buses thru bus #N. Can be
1721 useful if the kernel is unable to find your
1722 secondary buses and you want to tell it
1723 explicitly which ones they are.
1724 assign-busses [X86] Always assign all PCI bus
1725 numbers ourselves, overriding
1726 whatever the firmware may have done.
1727 usepirqmask [X86] Honor the possible IRQ mask stored
1728 in the BIOS $PIR table. This is needed on
1729 some systems with broken BIOSes, notably
1730 some HP Pavilion N5400 and Omnibook XE3
1731 notebooks. This will have no effect if ACPI
1732 IRQ routing is enabled.
1733 noacpi [X86] Do not use ACPI for IRQ routing
1734 or for PCI scanning.
1735 use_crs [X86] Use _CRS for PCI resource
1737 routeirq Do IRQ routing for all PCI devices.
1738 This is normally done in pci_enable_device(),
1739 so this option is a temporary workaround
1740 for broken drivers that don't call it.
1741 skip_isa_align [X86] do not align io start addr, so can
1742 handle more pci cards
1743 firmware [ARM] Do not re-enumerate the bus but instead
1744 just use the configuration from the
1745 bootloader. This is currently used on
1746 IXP2000 systems where the bus has to be
1747 configured a certain way for adjunct CPUs.
1748 noearly [X86] Don't do any early type 1 scanning.
1749 This might help on some broken boards which
1750 machine check when some devices' config space
1751 is read. But various workarounds are disabled
1752 and some IOMMU drivers will not work.
1753 bfsort Sort PCI devices into breadth-first order.
1754 This sorting is done to get a device
1755 order compatible with older (<= 2.4) kernels.
1756 nobfsort Don't sort PCI devices into breadth-first order.
1757 cbiosize=nn[KMG] The fixed amount of bus space which is
1758 reserved for the CardBus bridge's IO window.
1759 The default value is 256 bytes.
1760 cbmemsize=nn[KMG] The fixed amount of bus space which is
1761 reserved for the CardBus bridge's memory
1762 window. The default value is 64 megabytes.
1764 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1767 force Enable ASPM even on devices that claim not to support it.
1768 WARNING: Forcing ASPM on may cause system lockups.
1770 pcmv= [HW,PCMCIA] BadgePAD 4
1773 See Documentation/blockdev/paride.txt.
1775 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1778 See arch/parisc/kernel/pdc_chassis.c
1781 See Documentation/blockdev/paride.txt.
1784 See Documentation/blockdev/paride.txt.
1786 pirq= [SMP,APIC] Manual mp-table setup
1787 See Documentation/x86/i386/IO-APIC.txt.
1789 plip= [PPT,NET] Parallel port network link
1790 Format: { parport<nr> | timid | 0 }
1791 See also Documentation/parport.txt.
1793 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1794 Override pmtimer IOPort with a hex value.
1798 Enable PNP debug messages. This depends on the
1799 CONFIG_PNP_DEBUG_MESSAGES option.
1805 { on | off | curr | res | no-curr | no-res }
1808 [ISAPNP] Exclude IRQs for the autoconfiguration
1811 [ISAPNP] Exclude DMAs for the autoconfiguration
1813 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1814 Ranges are in pairs (I/O port base and size).
1817 [ISAPNP] Exclude memory regions for the
1819 Ranges are in pairs (memory base and size).
1821 dynamic_printk Enables pr_debug()/dev_dbg() calls if
1822 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
1823 These can also be switched on/off via
1824 <debugfs>/dynamic_printk/modules
1826 print-fatal-signals=
1827 [KNL] debug: print fatal signals
1828 print-fatal-signals=1: print segfault info to
1832 printk.time= Show timing data prefixed to each printk message line
1833 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1835 profile= [KNL] Enable kernel profiling via /proc/profile
1836 Format: [schedule,]<number>
1837 Param: "schedule" - profile schedule points.
1838 Param: <number> - step/bucket size as a power of 2 for
1839 statistical time based profiling.
1840 Param: "sleep" - profile D-state sleeping (millisecs).
1841 Requires CONFIG_SCHEDSTATS
1842 Param: "kvm" - profile VM exits.
1844 processor.max_cstate= [HW,ACPI]
1845 Limit processor to maximum C-state
1846 max_cstate=9 overrides any DMI blacklist limit.
1848 processor.nocst [HW,ACPI]
1849 Ignore the _CST method to determine C-states,
1850 instead using the legacy FADT method
1852 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1854 See Documentation/blockdev/ramdisk.txt.
1856 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1857 probe for; one of (bare|imps|exps|lifebook|any).
1858 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1860 psmouse.resetafter= [HW,MOUSE]
1861 Try to reset the device after so many bad packets
1864 [HW,MOUSE] Set desired mouse resolution, in dpi.
1865 psmouse.smartscroll=
1866 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1867 0 = disabled, 1 = enabled (default).
1869 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1871 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1874 See Documentation/blockdev/paride.txt.
1877 [KNL] Number of legacy pty's. Overwrites compiled-in
1880 quiet [KNL] Disable most log messages
1885 See Documentation/md.txt.
1887 ramdisk_blocksize= [RAM]
1888 See Documentation/blockdev/ramdisk.txt.
1890 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1891 See Documentation/blockdev/ramdisk.txt.
1893 rcupdate.blimit= [KNL,BOOT]
1894 Set maximum number of finished RCU callbacks to process
1897 rcupdate.qhimark= [KNL,BOOT]
1898 Set threshold of queued
1899 RCU callbacks over which batch limiting is disabled.
1901 rcupdate.qlowmark= [KNL,BOOT]
1902 Set threshold of queued RCU callbacks below which
1903 batch limiting is re-enabled.
1907 Run specified binary instead of /init from the ramdisk,
1908 used for early userspace startup. See initrd.
1910 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1911 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1912 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1915 [KNL, SMP] Set scheduler's default relax_domain_level.
1916 See Documentation/cpusets.txt.
1918 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1920 reservetop= [X86-32]
1922 Reserves a hole at the top of the kernel virtual
1925 reset_devices [KNL] Force drivers to reset the underlying device
1926 during initialization.
1929 Specify the partition device for software suspend
1931 resume_offset= [SWSUSP]
1932 Specify the offset from the beginning of the partition
1933 given by "resume=" at which the swap header is located,
1934 in <PAGE_SIZE> units (needed only for swap files).
1935 See Documentation/power/swsusp-and-swap-files.txt
1937 retain_initrd [RAM] Keep initrd memory after extraction
1939 rhash_entries= [KNL,NET]
1940 Set number of hash buckets for route cache
1942 riscom8= [HW,SERIAL]
1943 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1945 ro [KNL] Mount root device read-only on boot
1947 root= [KNL] Root filesystem
1949 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1950 mount the root filesystem
1952 rootflags= [KNL] Set root filesystem mount option string
1954 rootfstype= [KNL] Set root filesystem type
1956 rootwait [KNL] Wait (indefinitely) for root device to show up.
1957 Useful for devices that are detected asynchronously
1958 (e.g. USB and MMC devices).
1960 root_plug.vendor_id=
1961 [ROOTPLUG] Override the default vendor ID
1963 root_plug.product_id=
1964 [ROOTPLUG] Override the default product ID
1967 [ROOTPLUG] Enable debugging output
1969 rw [KNL] Mount root device read-write on boot
1971 S [KNL] Run init in single mode
1974 See drivers/net/irda/sa1100_ir.c.
1976 sbni= [NET] Granch SBNI12 leased line adapter
1978 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1979 Format: <io>[,<timeout>[,<isapnp>]]
1981 scsi_debug_*= [SCSI]
1982 See drivers/scsi/scsi_debug.c.
1984 scsi_default_dev_flags=
1985 [SCSI] SCSI default device flags
1988 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1989 Format: <vendor>:<model>:<flags>
1990 (flags are integer value)
1992 scsi_logging_level= [SCSI] a bit mask of logging levels
1993 See drivers/scsi/scsi_logging.h for bits. Also
1994 settable via sysctl at dev.scsi.logging_level
1995 (/proc/sys/dev/scsi/logging_level).
1996 There is also a nice 'scsi_logging_level' script in the
1997 S390-tools package, available for download at
1998 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2000 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2001 discovered. async scans them in kernel threads,
2002 allowing boot to proceed. none ignores them, expecting
2003 user space to do the scan.
2005 selinux [SELINUX] Disable or enable SELinux at boot time.
2006 Format: { "0" | "1" }
2007 See security/selinux/Kconfig help text.
2010 Default value is set via kernel config option.
2011 If enabled at boot time, /selinux/disable can be used
2012 later to disable prior to initial policy load.
2014 selinux_compat_net =
2015 [SELINUX] Set initial selinux_compat_net flag value.
2016 Format: { "0" | "1" }
2017 0 -- use new secmark-based packet controls
2018 1 -- use legacy packet controls
2019 Default value is 0 (preferred).
2020 Value can be changed at runtime via
2021 /selinux/compat_net.
2023 serialnumber [BUGS=X86-32]
2026 Maximal number of shapers.
2028 show_msr= [x86] show boot-time MSR settings
2029 Format: { <integer> }
2030 Show boot-time (BIOS-initialized) MSR settings.
2031 The parameter means the number of CPUs to show,
2032 for example 1 means boot CPU only.
2035 See header of drivers/scsi/sim710.c.
2042 slub_debug[=options[,slabs]] [MM, SLUB]
2043 Enabling slub_debug allows one to determine the
2044 culprit if slab objects become corrupted. Enabling
2045 slub_debug can create guard zones around objects and
2046 may poison objects when not in use. Also tracks the
2047 last alloc / free. For more information see
2048 Documentation/vm/slub.txt.
2050 slub_max_order= [MM, SLUB]
2051 Determines the maximum allowed order for slabs.
2052 A high setting may cause OOMs due to memory
2053 fragmentation. For more information see
2054 Documentation/vm/slub.txt.
2056 slub_min_objects= [MM, SLUB]
2057 The minimum number of objects per slab. SLUB will
2058 increase the slab order up to slub_max_order to
2059 generate a sufficiently large slab able to contain
2060 the number of objects indicated. The higher the number
2061 of objects the smaller the overhead of tracking slabs
2062 and the less frequently locks need to be acquired.
2063 For more information see Documentation/vm/slub.txt.
2065 slub_min_order= [MM, SLUB]
2066 Determines the mininum page order for slabs. Must be
2067 lower than slub_max_order.
2068 For more information see Documentation/vm/slub.txt.
2070 slub_nomerge [MM, SLUB]
2071 Disable merging of slabs with similar size. May be
2072 necessary if there is some reason to distinguish
2073 allocs to different slabs. Debug options disable
2074 merging on their own.
2075 For more information see Documentation/vm/slub.txt.
2078 Format: <io1>[,<io2>[,...,<io8>]]
2080 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2081 attempt to substitute SMP alternatives once at boot.
2083 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2084 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2085 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2086 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2087 smsc-ircc2.ircc_irq= [HW] IRQ line
2088 smsc-ircc2.ircc_dma= [HW] DMA channel
2089 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2090 0: Toshiba Satellite 1800 (GP data pin select)
2091 1: Fast pin select (default)
2094 snd-ad1816a= [HW,ALSA]
2096 snd-ad1848= [HW,ALSA]
2098 snd-ali5451= [HW,ALSA]
2100 snd-als100= [HW,ALSA]
2102 snd-als4000= [HW,ALSA]
2104 snd-azt2320= [HW,ALSA]
2106 snd-cmi8330= [HW,ALSA]
2108 snd-cmipci= [HW,ALSA]
2110 snd-cs4231= [HW,ALSA]
2112 snd-cs4232= [HW,ALSA]
2114 snd-cs4236= [HW,ALSA]
2116 snd-cs4281= [HW,ALSA]
2118 snd-cs46xx= [HW,ALSA]
2120 snd-dt019x= [HW,ALSA]
2122 snd-dummy= [HW,ALSA]
2124 snd-emu10k1= [HW,ALSA]
2126 snd-ens1370= [HW,ALSA]
2128 snd-ens1371= [HW,ALSA]
2130 snd-es968= [HW,ALSA]
2132 snd-es1688= [HW,ALSA]
2134 snd-es18xx= [HW,ALSA]
2136 snd-es1938= [HW,ALSA]
2138 snd-es1968= [HW,ALSA]
2140 snd-fm801= [HW,ALSA]
2142 snd-gusclassic= [HW,ALSA]
2144 snd-gusextreme= [HW,ALSA]
2146 snd-gusmax= [HW,ALSA]
2150 snd-ice1712= [HW,ALSA]
2152 snd-intel8x0= [HW,ALSA]
2154 snd-interwave= [HW,ALSA]
2159 snd-korg1212= [HW,ALSA]
2161 snd-maestro3= [HW,ALSA]
2163 snd-mpu401= [HW,ALSA]
2165 snd-mtpav= [HW,ALSA]
2167 snd-nm256= [HW,ALSA]
2169 snd-opl3sa2= [HW,ALSA]
2177 snd-opti93x= [HW,ALSA]
2181 snd-rme32= [HW,ALSA]
2183 snd-rme96= [HW,ALSA]
2185 snd-rme9652= [HW,ALSA]
2191 snd-sbawe= [HW,ALSA]
2193 snd-serial= [HW,ALSA]
2195 snd-sgalaxy= [HW,ALSA]
2197 snd-sonicvibes= [HW,ALSA]
2202 snd-sun-cs4231= [HW,ALSA]
2204 snd-trident= [HW,ALSA]
2206 snd-usb-audio= [HW,ALSA,USB]
2208 snd-via82xx= [HW,ALSA]
2210 snd-virmidi= [HW,ALSA]
2212 snd-wavefront= [HW,ALSA]
2214 snd-ymfpci= [HW,ALSA]
2217 [KNL] Should the soft-lockup detector generate panics.
2219 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2220 See Documentation/sonypi.txt
2222 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2223 See Documentation/serial/specialix.txt.
2225 spia_io_base= [HW,MTD]
2231 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2233 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2234 See Documentation/scsi/st.txt.
2237 Enabled the stack tracer on boot up.
2241 Set the STI (builtin display/keyboard on the HP-PARISC
2242 machines) console (graphic card) which should be used
2243 as the initial boot-console.
2244 See also comment in drivers/video/console/sticore.c.
2247 See comment in drivers/video/console/sticore.c.
2250 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2254 Control how the NFS server code allocates CPUs to
2255 service thread pools. Depending on how many NICs
2256 you have and where their interrupts are bound, this
2257 option will affect which CPUs will do NFS serving.
2258 Note: this parameter cannot be changed while the
2259 NFS server is running.
2261 auto the server chooses an appropriate mode
2262 automatically using heuristics
2263 global a single global pool contains all CPUs
2264 percpu one pool for each CPU
2265 pernode one pool for each NUMA node (equivalent
2266 to global on non-NUMA machines)
2268 swiotlb= [IA-64] Number of I/O TLB slabs
2272 sym53c416= [HW,SCSI]
2273 See header of drivers/scsi/sym53c416.c.
2275 sysrq_always_enabled
2277 Ignore sysrq setting - this boot parameter will
2278 neutralize any effect of /proc/sys/kernel/sysrq.
2279 Useful for debugging.
2282 See header of drivers/scsi/t128.c.
2286 test_suspend= [SUSPEND]
2287 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2288 standby suspend) as the system sleep state to briefly
2289 enter during system startup. The system is woken from
2290 this state using a wakeup-capable RTC alarm.
2292 thash_entries= [KNL,NET]
2293 Set number of hash buckets for TCP connection
2295 thermal.act= [HW,ACPI]
2296 -1: disable all active trip points in all thermal zones
2297 <degrees C>: override all lowest active trip points
2299 thermal.crt= [HW,ACPI]
2300 -1: disable all critical trip points in all thermal zones
2301 <degrees C>: override all critical trip points
2303 thermal.nocrt= [HW,ACPI]
2304 Set to disable actions on ACPI thermal zone
2305 critical and hot trip points.
2307 thermal.off= [HW,ACPI]
2308 1: disable ACPI thermal control
2310 thermal.psv= [HW,ACPI]
2311 -1: disable all passive trip points
2312 <degrees C>: override all passive trip points to this
2315 thermal.tzp= [HW,ACPI]
2316 Specify global default ACPI thermal zone polling rate
2317 <deci-seconds>: poll all this frequency
2318 0: no polling (default)
2321 See comment before function dc390_setup() in
2322 drivers/scsi/tmscsim.c.
2326 Specify if the kernel should make use of the cpu
2327 topology informations if the hardware supports these.
2328 The scheduler will make use of these informations and
2329 e.g. base its process migration decisions on it.
2334 trix= [HW,OSS] MediaTrix AudioTrix Pro
2336 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2338 tsc= Disable clocksource-must-verify flag for TSC.
2340 [x86] reliable: mark tsc clocksource as reliable, this
2341 disables clocksource verification at runtime.
2342 Used to enable high-resolution timer mode on older
2343 hardware, and in virtualized environment.
2345 turbografx.map[2|3]= [HW,JOY]
2346 TurboGraFX parallel port interface
2348 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2349 See also Documentation/input/joystick-parport.txt
2351 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2352 See header of drivers/scsi/u14-34f.c.
2361 [USB] Ignore overcurrent events (default N).
2362 Some badly-designed motherboards generate lots of
2363 bogus events, for ports that aren't wired to
2364 anything. Set this parameter to avoid log spamming.
2365 Note that genuine overcurrent events won't be
2370 Set unknown_nmi_panic=1 early on boot.
2372 usbcore.autosuspend=
2373 [USB] The autosuspend time delay (in seconds) used
2374 for newly-detected USB devices (default 2). This
2375 is the time required before an idle device will be
2376 autosuspended. Devices for which the delay is set
2377 to a negative value won't be autosuspended at all.
2379 usbcore.usbfs_snoop=
2380 [USB] Set to log all usbfs traffic (default 0 = off).
2382 usbcore.blinkenlights=
2383 [USB] Set to cycle leds on hubs (default 0 = off).
2385 usbcore.old_scheme_first=
2386 [USB] Start with the old device initialization
2387 scheme (default 0 = off).
2389 usbcore.use_both_schemes=
2390 [USB] Try the other device initialization scheme
2391 if the first one fails (default 1 = enabled).
2393 usbcore.initial_descriptor_timeout=
2394 [USB] Specifies timeout for the initial 64-byte
2395 USB_REQ_GET_DESCRIPTOR request in milliseconds
2396 (default 5000 = 5.0 seconds).
2399 [USBHID] The interval which mice are to be polled at.
2401 usb-storage.delay_use=
2402 [UMS] The delay in seconds before a new device is
2403 scanned for Logical Units (default 5).
2406 [UMS] A list of quirks entries to supplement or
2407 override the built-in unusual_devs list. List
2408 entries are separated by commas. Each entry has
2409 the form VID:PID:Flags where VID and PID are Vendor
2410 and Product ID values (4-digit hex numbers) and
2411 Flags is a set of characters, each corresponding
2412 to a common usb-storage quirk flag as follows:
2413 a = SANE_SENSE (collect more than 18 bytes
2415 c = FIX_CAPACITY (decrease the reported
2416 device capacity by one sector);
2417 h = CAPACITY_HEURISTICS (decrease the
2418 reported device capacity by one
2419 sector if the number is odd);
2420 i = IGNORE_DEVICE (don't bind to this
2422 l = NOT_LOCKABLE (don't try to lock and
2423 unlock ejectable media);
2424 m = MAX_SECTORS_64 (don't transfer more
2425 than 64 sectors = 32 KB at a time);
2426 o = CAPACITY_OK (accept the capacity
2427 reported by the device);
2428 r = IGNORE_RESIDUE (the device reports
2429 bogus residue values);
2430 s = SINGLE_LUN (the device has only one
2432 w = NO_WP_DETECT (don't test whether the
2433 medium is write-protected).
2434 Example: quirks=0419:aaf5:rl,0421:0433:rc
2436 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2437 kernel's map of available physical RAM.
2439 vdso= [X86-32,SH,x86-64]
2440 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2441 vdso=1: enable VDSO (default)
2442 vdso=0: disable VDSO mapping
2444 vdso32= [X86-32,X86-64]
2445 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2446 vdso32=1: enable 32-bit VDSO (default)
2447 vdso32=0: disable 32-bit VDSO mapping
2450 vector=percpu: enable percpu vector domain
2452 video= [FB] Frame buffer configuration
2453 See Documentation/fb/modedb.txt.
2455 vga= [BOOT,X86-32] Select a particular video mode
2456 See Documentation/x86/boot.txt and
2457 Documentation/svga.txt.
2458 Use vga=ask for menu.
2459 This is actually a boot loader parameter; the value is
2460 passed to the kernel using a special protocol.
2462 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2463 size of <nn>. This can be used to increase the
2464 minimum size (128MB on x86). It can also be used to
2465 decrease the size and leave more room for directly
2468 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2471 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2474 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2477 waveartist= [HW,OSS]
2478 Format: <io>,<irq>,<dma>,<dma2>
2481 See header of drivers/scsi/wd33c93.c.
2484 See header of drivers/scsi/wd7000.c.
2487 See Documentation/watchdog/wdt.txt.
2489 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2490 xd_geo= See header of drivers/block/xd.c.
2492 xirc2ps_cs= [NET,PCMCIA]
2494 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2496 norandmaps Don't use address space randomization. Equivalent to
2497 echo 0 > /proc/sys/kernel/randomize_va_space
2499 ______________________________________________________________________
2503 Add documentation for ALSA options.
2504 Add more DRM drivers.