4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 This document may not be entirely up to date and comprehensive. The command
21 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
22 module. Loadable modules, after being loaded into the running kernel, also
23 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
24 parameters may be changed at runtime by the command
25 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
27 The parameters listed below are only valid if certain kernel build options were
28 enabled and if respective hardware is present. The text in square brackets at
29 the beginning of each description states the restrictions within which a
30 parameter is applicable:
32 ACPI ACPI support is enabled.
33 AGP AGP (Accelerated Graphics Port) is enabled.
34 ALSA ALSA sound support is enabled.
35 APIC APIC support is enabled.
36 APM Advanced Power Management support is enabled.
37 AVR32 AVR32 architecture is enabled.
38 AX25 Appropriate AX.25 support is enabled.
39 BLACKFIN Blackfin architecture is enabled.
40 DRM Direct Rendering Management support is enabled.
41 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
42 EFI EFI Partitioning (GPT) is enabled
43 EIDE EIDE/ATAPI support is enabled.
44 FB The frame buffer device is enabled.
45 HW Appropriate hardware is enabled.
46 IA-64 IA-64 architecture is enabled.
47 IOSCHED More than one I/O scheduler is enabled.
48 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
49 ISAPNP ISA PnP code is enabled.
50 ISDN Appropriate ISDN support is enabled.
51 JOY Appropriate joystick support is enabled.
52 LIBATA Libata driver is enabled
53 LP Printer support is enabled.
54 LOOP Loopback device support is enabled.
55 M68k M68k architecture is enabled.
56 These options have more detailed description inside of
57 Documentation/m68k/kernel-options.txt.
58 MCA MCA bus support is enabled.
59 MDA MDA console support is enabled.
60 MOUSE Appropriate mouse support is enabled.
61 MSI Message Signaled Interrupts (PCI).
62 MTD MTD (Memory Technology Device) support is enabled.
63 NET Appropriate network support is enabled.
64 NUMA NUMA support is enabled.
65 GENERIC_TIME The generic timeofday code is enabled.
66 NFS Appropriate NFS support is enabled.
67 OSS OSS sound support is enabled.
68 PV_OPS A paravirtualized kernel is enabled.
69 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
70 PARISC The PA-RISC architecture is enabled.
71 PCI PCI bus support is enabled.
72 PCIE PCI Express support is enabled.
73 PCMCIA The PCMCIA subsystem is enabled.
74 PNP Plug & Play support is enabled.
75 PPC PowerPC architecture is enabled.
76 PPT Parallel port support is enabled.
77 PS2 Appropriate PS/2 support is enabled.
78 RAM RAM disk support is enabled.
79 ROOTPLUG The example Root Plug LSM is enabled.
80 S390 S390 architecture is enabled.
81 SCSI Appropriate SCSI support is enabled.
82 A lot of drivers has their options described inside of
84 SECURITY Different security models are enabled.
85 SELINUX SELinux support is enabled.
86 SERIAL Serial support is enabled.
87 SH SuperH architecture is enabled.
88 SMP The kernel is an SMP kernel.
89 SPARC Sparc architecture is enabled.
90 SWSUSP Software suspend (hibernation) is enabled.
91 SUSPEND System suspend states are enabled.
92 TS Appropriate touchscreen support is enabled.
93 USB USB support is enabled.
94 USBHID USB Human Interface Device support is enabled.
95 V4L Video For Linux support is enabled.
96 VGA The VGA console has been enabled.
97 VT Virtual terminal support is enabled.
98 WDT Watchdog support is enabled.
99 XT IBM PC/XT MFM hard disk support is enabled.
100 X86-32 X86-32, aka i386 architecture is enabled.
101 X86-64 X86-64 architecture is enabled.
102 More X86-64 boot options can be found in
103 Documentation/x86_64/boot-options.txt .
105 In addition, the following text indicates that the option:
107 BUGS= Relates to possible processor bugs on the said processor.
108 KNL Is a kernel start-up parameter.
109 BOOT Is a boot loader parameter.
111 Parameters denoted with BOOT are actually interpreted by the boot
112 loader, and have no meaning to the kernel directly.
113 Do not modify the syntax of boot loader parameters without extreme
114 need or coordination with <Documentation/i386/boot.txt>.
116 There are also arch-specific kernel-parameters not documented here.
117 See for example <Documentation/x86_64/boot-options.txt>.
119 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
120 a trailing = on the name of any parameter states that that parameter will
121 be entered as an environment variable, whereas its absence indicates that
122 it will appear as a kernel argument readable via /proc/cmdline by programs
123 running once the system is up.
125 The number of kernel parameters is not limited, but the length of the
126 complete command line (parameters including spaces etc.) is limited to
127 a fixed number of characters. This limit depends on the architecture
128 and is between 256 and 4096 characters. It is defined in the file
129 ./include/asm/setup.h as COMMAND_LINE_SIZE.
132 acpi= [HW,ACPI,X86-64,i386]
133 Advanced Configuration and Power Interface
134 Format: { force | off | ht | strict | noirq }
135 force -- enable ACPI if default was off
136 off -- disable ACPI if default was on
137 noirq -- do not use ACPI for IRQ routing
138 ht -- run only enough ACPI to enable Hyper Threading
139 strict -- Be less tolerant of platforms that are not
140 strictly ACPI specification compliant.
142 See also Documentation/power/pm.txt, pci=noacpi
144 acpi_apic_instance= [ACPI, IOAPIC]
146 2: use 2nd APIC table, if available
147 1,0: use 1st APIC table
150 acpi_sleep= [HW,ACPI] Sleep options
151 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
152 See Documentation/power/video.txt for s3_bios and s3_mode.
153 s3_beep is for debugging; it makes the PC's speaker beep
154 as soon as the kernel's real-mode entry point is called.
155 s4_nohwsig prevents ACPI hardware signature from being
156 used during resume from hibernation.
157 old_ordering causes the ACPI 1.0 ordering of the _PTS
158 control method, wrt putting devices into low power
159 states, to be enforced (the ACPI 2.0 ordering of _PTS is
162 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
163 Format: { level | edge | high | low }
165 acpi_irq_balance [HW,ACPI]
166 ACPI will balance active IRQs
169 acpi_irq_nobalance [HW,ACPI]
170 ACPI will not move active IRQs (default)
173 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
175 Format: <irq>,<irq>...
177 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
178 Format: <irq>,<irq>...
180 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
182 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
183 Format: To spoof as Windows 98: ="Microsoft Windows"
185 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
186 acpi_osi="string1" # add string1 -- only one string
187 acpi_osi="!string2" # remove built-in string2
188 acpi_osi= # disable all strings
190 acpi_serialize [HW,ACPI] force serialization of AML methods
192 acpi_skip_timer_override [HW,ACPI]
193 Recognize and ignore IRQ0/pin2 Interrupt Override.
194 For broken nForce2 BIOS resulting in XT-PIC timer.
195 acpi_use_timer_override [HW,ACPI}
196 Use timer override. For some broken Nvidia NF5 boards
197 that require a timer override, but don't have
200 acpi.debug_layer= [HW,ACPI]
202 Each bit of the <int> indicates an ACPI debug layer,
203 1: enable, 0: disable. It is useful for boot time
204 debugging. After system has booted up, it can be set
205 via /sys/module/acpi/parameters/debug_layer.
206 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
207 Available bits (add the numbers together) to enable debug output
208 for specific parts of the ACPI subsystem:
209 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
210 0x10 namespace 0x20 parser 0x40 dispatcher
211 0x80 executer 0x100 resources 0x200 acpica debugger
212 0x400 os services 0x800 acpica disassembler.
213 The number can be in decimal or prefixed with 0x in hex.
214 Warning: Many of these options can produce a lot of
215 output and make your system unusable. Be very careful.
217 acpi.debug_level= [HW,ACPI]
219 Each bit of the <int> indicates an ACPI debug level,
220 1: enable, 0: disable. It is useful for boot time
221 debugging. After system has booted up, it can be set
222 via /sys/module/acpi/parameters/debug_level.
223 CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
224 Available bits (add the numbers together) to enable different
225 debug output levels of the ACPI subsystem:
226 0x01 error 0x02 warn 0x04 init 0x08 debug object
227 0x10 info 0x20 init names 0x40 parse 0x80 load
228 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
229 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
230 0x10000 resources 0x20000 user requests 0x40000 package.
231 The number can be in decimal or prefixed with 0x in hex.
232 Warning: Many of these options can produce a lot of
233 output and make your system unusable. Be very careful.
235 acpi_pm_good [X86-32,X86-64]
236 Override the pmtimer bug detection: force the kernel
237 to assume that this machine's pmtimer latches its value
238 and always returns good values.
241 { off | try_unsupported }
242 off: disable AGP support
243 try_unsupported: try to drive unsupported chipsets
244 (may crash computer or cause data corruption)
246 enable_timer_pin_1 [i386,x86-64]
247 Enable PIN 1 of APIC timer
248 Can be useful to work around chipset bugs
249 (in particular on some ATI chipsets).
250 The kernel tries to set a reasonable default.
252 disable_timer_pin_1 [i386,x86-64]
253 Disable PIN 1 of APIC timer
254 Can be useful to work around chipset bugs.
257 Format: <io>,<irq>,<dma>,<dma2>,<type>
260 See header of drivers/scsi/advansys.c.
262 advwdt= [HW,WDT] Advantech WDT
263 Format: <iostart>,<iostop>
265 aedsp16= [HW,OSS] Audio Excel DSP 16
266 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
267 See also header of sound/oss/aedsp16.c.
270 See Documentation/scsi/aha152x.txt.
273 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
276 See Documentation/scsi/aic7xxx.txt.
279 See Documentation/scsi/aic79xx.txt.
281 amd_iommu= [HW,X86-84]
282 Pass parameters to the AMD IOMMU driver in the system.
284 isolate - enable device isolation (each device, as far
285 as possible, will get its own protection
287 amd_iommu_size= [HW,X86-64]
288 Define the size of the aperture for the AMD IOMMU
289 driver. Possible values are:
290 '32M', '64M' (default), '128M', '256M', '512M', '1G'
292 amijoy.map= [HW,JOY] Amiga joystick support
293 Map of devices attached to JOY0DAT and JOY1DAT
295 See also Documentation/kernel/input/joystick.txt
297 analog.map= [HW,JOY] Analog joystick and gamepad support
298 Specifies type or capabilities of an analog joystick
299 connected to one of 16 gameports
300 Format: <type1>,<type2>,..<type16>
303 Power management functions (SPARCstation-4/5 + deriv.)
305 Disable APC CPU standby support. SPARCstation-Fox does
306 not play well with APC CPU idle - disable it if you have
307 APC and your system crashes randomly.
309 apic= [APIC,i386] Advanced Programmable Interrupt Controller
310 Change the output verbosity whilst booting
311 Format: { quiet (default) | verbose | debug }
312 Change the amount of debugging information output
313 when initialising the APIC and IO-APIC components.
315 apm= [APM] Advanced Power Management
316 See header of arch/x86/kernel/apm_32.c.
318 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
319 Format: <io>,<irq>,<nodeID>
323 atarimouse= [HW,MOUSE] Atari Mouse
325 atascsi= [HW,SCSI] Atari SCSI
327 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
328 EzKey and similar keyboards
330 atkbd.reset= [HW] Reset keyboard during initialization
332 atkbd.set= [HW] Select keyboard code set
333 Format: <int> (2 = AT (default), 3 = PS/2)
335 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
338 atkbd.softraw= [HW] Choose between synthetic and real raw mode
339 Format: <bool> (0 = real, 1 = synthetic (default))
341 atkbd.softrepeat= [HW]
342 Use software keyboard repeat
346 baycom_epp= [HW,AX25]
349 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
351 See header of drivers/net/hamradio/baycom_par.c.
353 baycom_ser_fdx= [HW,AX25]
354 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
355 Format: <io>,<irq>,<mode>[,<baud>]
356 See header of drivers/net/hamradio/baycom_ser_fdx.c.
358 baycom_ser_hdx= [HW,AX25]
359 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
360 Format: <io>,<irq>,<mode>
361 See header of drivers/net/hamradio/baycom_ser_hdx.c.
363 boot_delay= Milliseconds to delay each printk during boot.
364 Values larger than 10 seconds (10000) are changed to
368 bootmem_debug [KNL] Enable bootmem allocator debug messages.
370 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
371 bttv.radio= Most important insmod options are available as
373 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
374 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
377 See drivers/scsi/BusLogic.c, comment before function
378 BusLogic_ParseDriverOptions().
380 c101= [NET] Moxa C101 synchronous serial card
382 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
383 Sometimes CPU hardware bugs make them report the cache
384 size incorrectly. The kernel will attempt work arounds
385 to fix known problems, but for some CPUs it is not
386 possible to determine what the correct size should be.
387 This option provides an override for these situations.
389 security= [SECURITY] Choose a security module to enable at boot.
390 If this boot parameter is not specified, only the first
391 security module asking for security registration will be
392 loaded. An invalid security module name will be treated
393 as if no module has been chosen.
396 [SECURITY] Disable capabilities. This would normally
397 be used only if an alternative security model is to be
398 configured. Potentially dangerous and should only be
399 used if you are entirely sure of the consequences.
401 ccw_timeout_log [S390]
402 See Documentation/s390/CommonIO for details.
404 cgroup_disable= [KNL] Disable a particular controller
405 Format: {name of the controller(s) to disable}
406 {Currently supported controllers - "memory"}
408 checkreqprot [SELINUX] Set initial checkreqprot flag value.
409 Format: { "0" | "1" }
410 See security/selinux/Kconfig help text.
411 0 -- check protection applied by kernel (includes
412 any implied execute protection).
413 1 -- check protection requested by application.
414 Default value is set via a kernel config option.
415 Value can be changed at runtime via
416 /selinux/checkreqprot.
419 See Documentation/s390/CommonIO for details.
421 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
423 Forces specified clocksource (if available) to be used
424 when calculating gettimeofday(). If specified
425 clocksource is not available, it defaults to PIT.
426 Format: { pit | tsc | cyclone | pmtmr }
428 clocksource= [GENERIC_TIME] Override the default clocksource
430 Override the default clocksource and use the clocksource
431 with the name specified.
432 Some clocksource names to choose from, depending on
434 [all] jiffies (this is the base, fallback clocksource)
436 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
437 pxa_timer,timer3,32k_counter,timer0_1
439 [X86-32] pit,hpet,tsc,vmi-timer;
440 scx200_hrt on Geode; cyclone on IBM x440
448 clearcpuid=BITNUM [X86]
449 Disable CPUID feature X for the kernel. See
450 include/asm-x86/cpufeature.h for the valid bit numbers.
451 Note the Linux specific bits are not necessarily
452 stable over kernel options, but the vendor specific
454 Also note that user programs calling CPUID directly
455 or using the feature without checking anything
456 will still see it. This just prevents it from
457 being used by the kernel or shown in /proc/cpuinfo.
458 Also note the kernel might malfunction if you disable
461 code_bytes [IA32/X86_64] How many bytes of object code to print
466 hpet= [X86-32,HPET] option to control HPET usage
467 Format: { enable (default) | disable | force }
468 disable: disable HPET and use PIT instead
469 force: allow force enabled of undocumented chips (ICH4,
472 com20020= [HW,NET] ARCnet - COM20020 chipset
474 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
476 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
480 ARCnet - COM90xx chipset (memory-mapped buffers)
481 Format: <io>[,<irq>[,<memstart>]]
483 condev= [HW,S390] console device
486 console= [KNL] Output console device and options.
488 tty<n> Use the virtual console device <n>.
492 Use the specified serial port. The options are of
493 the form "bbbbpnf", where "bbbb" is the baud rate,
494 "p" is parity ("n", "o", or "e"), "n" is number of
495 bits, and "f" is flow control ("r" for RTS or
496 omit it). Default is "9600n8".
498 See Documentation/serial-console.txt for more
500 Documentation/networking/netconsole.txt for an
503 uart[8250],io,<addr>[,options]
504 uart[8250],mmio,<addr>[,options]
505 Start an early, polled-mode console on the 8250/16550
506 UART at the specified I/O port or MMIO address,
507 switching to the matching ttyS device later. The
508 options are the same as for ttyS, above.
510 If the device connected to the port is not a TTY but a braille
511 device, prepend "brl," before the device type, for instance
513 For now, only VisioBraille is supported.
515 earlycon= [KNL] Output early console device and options.
516 uart[8250],io,<addr>[,options]
517 uart[8250],mmio,<addr>[,options]
518 Start an early, polled-mode console on the 8250/16550
519 UART at the specified I/O port or MMIO address.
520 The options are the same as for ttyS, above.
523 [HW] Never suspend the console
524 Disable suspending of consoles during suspend and
525 hibernate operations. Once disabled, debugging
526 messages can reach various consoles while the rest
527 of the system is being put to sleep (ie, while
528 debugging driver suspend/resume hooks). This may
529 not work reliably with all consoles, but is known
530 to work with serial and VGA consoles.
532 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
534 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
536 crashkernel=nn[KMG]@ss[KMG]
537 [KNL] Reserve a chunk of physical memory to
538 hold a kernel to switch to with kexec on panic.
540 crashkernel=range1:size1[,range2:size2,...][@offset]
541 [KNL] Same as above, but depends on the memory
542 in the running system. The syntax of range is
543 start-[end] where start and end are both
544 a memory unit (amount[KMG]). See also
545 Documentation/kdump/kdump.txt for a example.
548 Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
553 cs89x0_media= [HW,NET]
554 Format: { rj45 | aui | bnc }
557 See header of drivers/s390/block/dasd_devmap.c.
559 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
560 (one device per port)
561 Format: <port#>,<type>
562 See also Documentation/input/joystick-parport.txt
564 debug [KNL] Enable kernel debugging (events log level).
567 [KNL] verbose self-tests
569 Print debugging info while doing the locking API
571 We default to 0 (no extra messages), setting it to
572 1 will print _a lot_ more information - normally
573 only useful to kernel developers.
575 debug_objects [KNL] Enable object debugging
577 debugpat [X86] Enable PAT debugging
579 decnet.addr= [HW,NET]
580 Format: <area>[,<node>]
581 See also Documentation/networking/decnet.txt.
584 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
585 Change the default blue palette of the console.
586 This is a 16-member array composed of values
590 Format: <green0>,<green1>,<green2>,...,<green15>
591 Change the default green palette of the console.
592 This is a 16-member array composed of values
596 Format: <red0>,<red1>,<red2>,...,<red15>
597 Change the default red palette of the console.
598 This is a 16-member array composed of values
604 Set system-wide default UTF-8 mode for all tty's.
605 Default is 1, i.e. UTF-8 mode is enabled for all
606 newly opened terminals.
609 Set number of hash buckets for dentry cache.
612 IO parameters + enable/disable command.
614 digiepca= [HW,SERIAL]
615 See drivers/char/README.epca and
616 Documentation/digiepca.txt.
618 disable_mtrr_cleanup [X86]
619 enable_mtrr_cleanup [X86]
620 The kernel tries to adjust MTRR layout from continuous
621 to discrete, to make X server driver able to add WB
622 entry later. This parameter enables/disables that.
624 mtrr_chunk_size=nn[KMG] [X86]
625 used for mtrr cleanup. It is largest continous chunk
626 that could hold holes aka. UC entries.
628 mtrr_gran_size=nn[KMG] [X86]
629 Used for mtrr cleanup. It is granularity of mtrr block.
631 Large value could prevent small alignment from
634 mtrr_spare_reg_nr=n [X86]
636 Range: 0,7 : spare reg number
638 Used for mtrr cleanup. It is spare mtrr entries number.
639 Set to 2 or more if your graphical card needs more.
641 disable_mtrr_trim [X86, Intel and AMD only]
642 By default the kernel will trim any uncacheable
643 memory out of your available memory pool based on
644 MTRR settings. This parameter disables that behavior,
645 possibly causing your machine to run very slowly.
647 dmasound= [HW,OSS] Sound subsystem buffers
653 earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
655 earlyprintk=serial[,ttySn[,baudrate]]
657 Append ",keep" to not disable it when the real console
660 Only vga or serial at a time, not both.
662 Currently only ttyS0 and ttyS1 are supported.
664 Interaction with the standard serial driver is not
667 The VGA output is eventually overwritten by the real
673 Format: {"off" | "on" | "skip[mbr]"}
675 eisa_irq_edge= [PARISC,HW]
676 See header of drivers/parisc/eisa.c.
679 See comment before function elanfreq_setup() in
680 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
683 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
684 See Documentation/block/as-iosched.txt and
685 Documentation/block/deadline-iosched.txt for details.
687 elfcorehdr= [X86-32, X86_64]
688 Specifies physical address of start of kernel core
689 image elf header. Generally kexec loader will
690 pass this option to capture kernel.
691 See Documentation/kdump/kdump.txt for details.
693 enforcing [SELINUX] Set initial enforcing status.
695 See security/selinux/Kconfig help text.
696 0 -- permissive (log only, no denials).
697 1 -- enforcing (deny and log).
699 Value can be changed at runtime via /selinux/enforce.
702 Format: <spdif>,[<nomix>,[<amplifier>]]
703 See also header of sound/oss/es1371.c.
705 ether= [HW,NET] Ethernet cards parameters
706 This option is obsoleted by the "netdev=" option, which
707 has equivalent usage. See its documentation for details.
709 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
714 fail_make_request=[KNL]
715 General fault injection mechanism.
716 Format: <interval>,<probability>,<space>,<times>
717 See also /Documentation/fault-injection/.
720 See header of drivers/scsi/fd_mcs.c.
723 See header of drivers/scsi/fdomain.c.
726 See Documentation/floppy.txt.
728 force_pal_cache_flush
729 [IA-64] Avoid check_sal_cache_flush which may hang on
730 buggy SAL_CACHE_FLUSH implementations. Using this
731 parameter will force ia64_sal_cache_flush to call
732 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
735 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
736 support via parallel port (up to 5 devices per port)
737 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
738 See also Documentation/input/joystick-parport.txt
742 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
747 See header of drivers/scsi/gdth.c.
749 gpt [EFI] Forces disk with valid GPT signature but
750 invalid Protective MBR to be treated as GPT.
754 hashdist= [KNL,NUMA] Large hashes allocated during boot
755 are distributed across NUMA nodes. Defaults on
756 for IA-64, off otherwise.
757 Format: 0 | 1 (for off | on)
759 hcl= [IA-64] SGI's Hardware Graph compatibility layer
761 hd= [EIDE] (E)IDE hard drive subsystem geometry
762 Format: <cyl>,<head>,<sect>
764 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
765 size of <nn>. This works even on boxes that have no
766 highmem otherwise. This also works to reduce highmem
767 size on bigger boxes.
769 highres= [KNL] Enable/disable high resolution timer mode.
770 Valid parameters: "on", "off"
774 See Documentation/isdn/README.HiSax.
776 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
777 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
778 On x86-64 and powerpc, this option can be specified
779 multiple times interleaved with hugepages= to reserve
780 huge pages of different sizes. Valid pages sizes on
781 x86-64 are 2M (when the CPU supports "pse") and 1G
782 (when the CPU supports the "pdpe1gb" cpuinfo flag)
783 Note that 1GB pages can only be allocated at boot time
784 using hugepages= and not freed afterwards.
786 [same as hugepagesz=] The size of the default
787 HugeTLB page size. This is the size represented by
788 the legacy /proc/ hugepages APIs, used for SHM, and
789 default size when mounting hugetlbfs filesystems.
790 Defaults to the default architecture's huge page size
793 i8042.direct [HW] Put keyboard port into non-translated mode
794 i8042.dumbkbd [HW] Pretend that controller can only read data from
795 keyboard and cannot control its state
796 (Don't attempt to blink the leds)
797 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
798 i8042.nokbd [HW] Don't check/create keyboard port
799 i8042.noloop [HW] Disable the AUX Loopback command while probing
801 i8042.nomux [HW] Don't check presence of an active multiplexing
803 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
806 [HW] Frequency with which keyboard LEDs should blink
807 when kernel panics (default is 0.5 sec)
808 i8042.reset [HW] Reset the controller during init and cleanup
809 i8042.unlock [HW] Unlock (ignore) the keylock
813 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
814 indicates that the driver is running on unsupported
816 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
817 does not match list of supported models.
819 [HW] Report power status in /proc/i8k
820 (disabled by default)
821 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
824 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
825 See Documentation/mca.txt.
828 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
830 ide= [HW] (E)IDE subsystem
831 Format: ide=nodma or ide=doubler
832 See Documentation/ide/ide.txt.
834 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
835 See Documentation/ide/ide.txt.
838 Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
839 Poll forces a polling idle loop that can slightly improves the performance
840 of waking up a idle CPU, but will use a lot of power and make the system
841 run hot. Not recommended.
842 idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
843 to not use it because it doesn't save as much power as a normal idle
844 loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
846 idle=halt. Halt is forced to be used for CPU idle.
847 In such case C2/C3 won't be used again.
848 idle=nomwait. Disable mwait for CPU C-states
850 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
851 Claim all unknown PCI IDE storage controllers.
853 ignore_loglevel [KNL]
854 Ignore loglevel setting - this will print /all/
855 kernel messages to the console. Useful for debugging.
858 Set number of hash buckets for inode cache.
861 See header of drivers/scsi/in2000.c.
865 Run specified binary instead of /sbin/init as init
868 initcall_debug [KNL] Trace initcalls as they are executed. Useful
869 for working out where the kernel is dying during
872 initrd= [BOOT] Specify the location of the initial ramdisk
874 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
892 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
894 Disable intel iommu driver.
895 igfx_off [Default Off]
896 By default, gfx is mapped as normal device. If a gfx
897 device has a dedicated DMAR unit, the DMAR unit is
898 bypassed by not enabling DMAR with this option. In
899 this case, gfx device will use physical address for
902 With this option iommu will not optimize to look
903 for io virtual address below 32 bit forcing dual
904 address cycle on pci bus for cards supporting greater
905 than 32 bit addressing. The default is to look
906 for translation below 32 bit and if not available
907 then look in the higher range.
909 With this option on every unmap_single operation will
910 result in a hardware IOTLB flush operation as opposed
911 to batching them for performance.
913 io_delay= [X86-32,X86-64] I/O delay method
915 Standard port 0x80 based delay
917 Alternate port 0xed based delay (needed on some systems)
919 Simple two microseconds delay
923 io7= [HW] IO7 for Marvel based alpha systems
924 See comment before marvel_specify_io7 in
925 arch/alpha/kernel/core_marvel.c.
928 See Documentation/filesystems/nfsroot.txt.
930 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
931 See comment before ip2_setup() in
932 drivers/char/ip2/ip2base.c.
934 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
935 See header of drivers/scsi/ips.c.
937 ports= [IP_VS_FTP] IPVS ftp helper module
939 Up to 8 (IP_VS_APP_MAX_PORTS) ports
941 Format: <port>,<port>....
944 When an interrupt is not handled search all handlers
945 for it. Intended to get systems with badly broken
949 When an interrupt is not handled search all handlers
950 for it. Also check all handlers each timer
951 interrupt. Intended to get systems with badly broken
955 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
957 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
959 <cpu number>,...,<cpu number>
961 <cpu number>-<cpu number> (must be a positive range in ascending order)
963 <cpu number>,...,<cpu number>-<cpu number>
964 This option can be used to specify one or more CPUs
965 to isolate from the general SMP balancing and scheduling
966 algorithms. The only way to move a process onto or off
967 an "isolated" CPU is via the CPU affinity syscalls.
968 <cpu number> begins at 0 and the maximum value is
969 "number of CPUs in system - 1".
971 This option is the preferred way to isolate CPUs. The
972 alternative -- manually setting the CPU mask of all
973 tasks in the system -- can cause problems and
974 suboptimal load balancer performance.
978 js= [HW,JOY] Analog joystick
979 See Documentation/input/joystick.txt.
981 kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
982 specifies the amount of memory usable by the kernel
983 for non-movable allocations. The requested amount is
984 spread evenly throughout all nodes in the system. The
985 remaining memory in each node is used for Movable
986 pages. In the event, a node is too small to have both
987 kernelcore and Movable pages, kernelcore pages will
988 take priority and other nodes will have a larger number
989 of kernelcore pages. The Movable zone is used for the
990 allocation of pages that may be reclaimed or moved
991 by the page migration subsystem. This means that
992 HugeTLB pages may not be allocated from this zone.
993 Note that allocations like PTEs-from-HighMem still
994 use the HighMem zone if it exists, and the Normal
997 movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
998 is similar to kernelcore except it specifies the
999 amount of memory used for migratable allocations.
1000 If both kernelcore and movablecore is specified,
1001 then kernelcore will be at *least* the specified
1002 value but may be more. If movablecore on its own
1003 is specified, the administrator must be careful
1004 that the amount of memory usable for all allocations
1009 kstack=N [X86-32,X86-64] Print N words from the kernel stack
1012 kgdboc= [HW] kgdb over consoles.
1013 Requires a tty driver that supports console polling.
1014 (only serial suported for now)
1015 Format: <serial_device>[,baud]
1021 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1024 lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
1027 libata.dma= [LIBATA] DMA control
1028 libata.dma=0 Disable all PATA and SATA DMA
1029 libata.dma=1 PATA and SATA Disk DMA only
1030 libata.dma=2 ATAPI (CDROM) DMA only
1031 libata.dma=4 Compact Flash DMA only
1032 Combinations also work, so libata.dma=3 enables DMA
1033 for disks and CDROMs, but not CFs.
1035 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1039 libata.force= [LIBATA] Force configurations. The format is comma
1040 separated list of "[ID:]VAL" where ID is
1041 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1042 matching port, link or device. Basically, it matches
1043 the ATA ID string printed on console by libata. If
1044 the whole ID part is omitted, the last PORT and DEVICE
1045 values are used. If ID hasn't been specified yet, the
1046 configuration applies to all ports, links and devices.
1048 If only DEVICE is omitted, the parameter applies to
1049 the port and all links and devices behind it. DEVICE
1050 number of 0 either selects the first device or the
1051 first fan-out link behind PMP device. It does not
1052 select the host link. DEVICE number of 15 selects the
1053 host link and device attached to it.
1055 The VAL specifies the configuration to force. As long
1056 as there's no ambiguity shortcut notation is allowed.
1057 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1058 The following configurations can be forced.
1060 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1061 Any ID with matching PORT is used.
1063 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1065 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1066 udma[/][16,25,33,44,66,100,133] notation is also
1069 * [no]ncq: Turn on or off NCQ.
1071 If there are multiple matching configurations changing
1072 the same attribute, the last one is used.
1074 load_ramdisk= [RAM] List of ramdisks to load from floppy
1075 See Documentation/ramdisk.txt.
1077 lockd.nlm_grace_period=P [NFS] Assign grace period.
1080 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1083 lockd.nlm_timeout=T [NFS] Assign timeout value.
1086 lockd.nlm_udpport=M [NFS] Assign UDP port.
1089 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1092 loglevel= All Kernel Messages with a loglevel smaller than the
1093 console loglevel will be printed to the console. It can
1094 also be changed with klogd or other programs. The
1095 loglevels are defined as follows:
1097 0 (KERN_EMERG) system is unusable
1098 1 (KERN_ALERT) action must be taken immediately
1099 2 (KERN_CRIT) critical conditions
1100 3 (KERN_ERR) error conditions
1101 4 (KERN_WARNING) warning conditions
1102 5 (KERN_NOTICE) normal but significant condition
1103 6 (KERN_INFO) informational
1104 7 (KERN_DEBUG) debug-level messages
1106 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1107 Format: { n | nk | nM }
1108 n must be a power of two. The default size
1109 is set in the kernel config file.
1111 logo.nologo [FB] Disables display of the built-in Linux logo.
1112 This may be used to provide more screen space for
1113 kernel log messages and is useful when debugging
1114 kernel boot problems.
1116 lp=0 [LP] Specify parallel ports to use, e.g,
1117 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1118 lp=reset first parallel port). 'lp=0' disables the
1119 lp=auto printer driver. 'lp=reset' (which can be
1120 specified in addition to the ports) causes
1121 attached printers to be reset. Using
1122 lp=port1,port2,... specifies the parallel ports
1123 to associate lp devices with, starting with
1124 lp0. A port specification may be 'none' to skip
1125 that lp device, or a parport name such as
1126 'parport0'. Specifying 'lp=auto' instead of a
1127 port specification list means that device IDs
1128 from each port should be examined, to see if
1129 an IEEE 1284-compliant printer is attached; if
1130 so, the driver will manage that printer.
1131 See also header of drivers/char/lp.c.
1134 Sets loops_per_jiffy to given constant, thus avoiding
1135 time-consuming boot-time autodetection (up to 250 ms per
1136 CPU). 0 enables autodetection (default). To determine
1137 the correct value for your kernel, boot with normal
1138 autodetection and see what value is printed. Note that
1139 on SMP systems the preset will be applied to all CPUs,
1140 which is likely to cause problems if your CPUs need
1141 significantly divergent settings. An incorrect value
1142 will cause delays in the kernel to be wrong, leading to
1143 unpredictable I/O errors and other breakage. Although
1144 unlikely, in the extreme case this might damage your
1148 Format: <io>,<irq>,<dma>
1150 mac5380= [HW,SCSI] Format:
1151 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1153 machvec= [IA64] Force the use of a particular machine-vector
1154 (machvec) in a generic kernel.
1155 Example: machvec=hpzx1_swiotlb
1157 max_loop= [LOOP] Maximum number of loopback devices that can
1161 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1162 should make use of. maxcpus=n : n >= 0 limits the
1163 kernel to using 'n' processors. n=0 is a special case,
1164 it is equivalent to "nosmp", which also disables
1167 max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
1168 equal to this physical address is ignored.
1170 max_luns= [SCSI] Maximum number of LUNs to probe.
1171 Should be between 1 and 2^32-1.
1174 [SCSI] Maximum number of LUNs received.
1175 Should be between 1 and 16384.
1179 mce [X86-32] Machine Check Exception
1181 mce=option [X86-64] See Documentation/x86_64/boot-options.txt
1183 md= [HW] RAID subsystems devices and level
1184 See Documentation/md.txt.
1187 Format: <first>,<last>
1188 Specifies range of consoles to be captured by the MDA.
1190 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1191 Amount of memory to be used when the kernel is not able
1192 to see the whole system memory or for test.
1193 [X86-32] Use together with memmap= to avoid physical
1194 address space collisions. Without memmap= PCI devices
1195 could be placed at addresses belonging to unused RAM.
1197 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1200 memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
1201 E820 memory map, as specified by the user.
1202 Such memmap=exactmap lines can be constructed based on
1203 BIOS output or other requirements. See the memmap=nn@ss
1206 memmap=nn[KMG]@ss[KMG]
1207 [KNL] Force usage of a specific region of memory
1208 Region of memory to be used, from ss to ss+nn.
1210 memmap=nn[KMG]#ss[KMG]
1211 [KNL,ACPI] Mark specific memory as ACPI data.
1212 Region of memory to be used, from ss to ss+nn.
1214 memmap=nn[KMG]$ss[KMG]
1215 [KNL,ACPI] Mark specific memory as reserved.
1216 Region of memory to be used, from ss to ss+nn.
1217 Example: Exclude memory from 0x18690000-0x1869ffff
1218 memmap=64K$0x18690000
1220 memmap=0x10000$0x18690000
1222 memtest= [KNL,X86] Enable memtest
1224 range: 0,4 : pattern number
1225 default : 0 <disable>
1227 meye.*= [HW] Set MotionEye Camera parameters
1228 See Documentation/video4linux/meye.txt.
1230 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1231 Multi-Function General Purpose Timers on AMD Geode
1234 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1235 the BIOS has incorrectly applied a workaround. TinyBIOS
1236 version 0.98 is known to be affected, 0.99 fixes the
1237 problem by letting the user disable the workaround.
1242 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1243 parameter allows control of the logging verbosity for
1244 the additional memory initialisation checks. A value
1245 of 0 disables mminit logging and a level of 4 will
1246 log everything. Information is printed at KERN_DEBUG
1247 so loglevel=8 may also need to be specified.
1250 [MOUSE] Maximum time between finger touching and
1251 leaving touchpad surface for touch to be considered
1252 a tap and be reported as a left button click (for
1253 touchpads working in absolute mode only).
1255 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1256 reporting absolute coordinates, such as tablets
1257 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1258 reporting absolute coordinates, such as tablets
1263 MTD_Partition= [MTD]
1264 Format: <name>,<region-number>,<size>,<offset>
1266 MTD_Region= [MTD] Format:
1267 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1270 See drivers/mtd/cmdlinepart.c.
1273 ARM/S3C2412 JIVE boot control
1275 See arch/arm/mach-s3c2412/mach-jive.c
1277 mtouchusb.raw_coordinates=
1278 [HW] Make the MicroTouch USB driver use raw coordinates
1279 ('y', default) or cooked coordinates ('n')
1281 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1284 See header of drivers/scsi/NCR_D700.c.
1288 ncr53c400= [HW,SCSI]
1290 ncr53c400a= [HW,SCSI]
1292 ncr53c406a= [HW,SCSI]
1294 ncr53c8xx= [HW,SCSI]
1296 netdev= [NET] Network devices parameters
1297 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1298 Note that mem_start is often overloaded to mean
1299 something different and driver-specific.
1300 This usage is only documented in each driver source
1304 [NETFILTER] Enable connection tracking flow accounting
1305 0 to disable accounting
1306 1 to enable accounting
1307 Default value depends on CONFIG_NF_CT_ACCT that is
1308 going to be removed in 2.6.29.
1311 See Documentation/filesystems/nfsroot.txt.
1313 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1314 See Documentation/filesystems/nfsroot.txt.
1316 nfs.callback_tcpport=
1317 [NFS] set the TCP port on which the NFSv4 callback
1318 channel should listen.
1320 nfs.idmap_cache_timeout=
1321 [NFS] set the maximum lifetime for idmapper cache
1325 [NFS] enable 64-bit inode numbers.
1326 If zero, the NFS client will fake up a 32-bit inode
1327 number for the readdir() and stat() syscalls instead
1328 of returning the full 64-bit number.
1329 The default is to return 64-bit inode numbers.
1331 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1332 when a NMI is triggered.
1333 Format: [state][,regs][,debounce][,die]
1335 nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
1337 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1338 emulation library even if a 387 maths coprocessor
1341 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1342 caches in the slab allocator. Saves per-node memory,
1343 but will impact performance.
1347 noapic [SMP,APIC] Tells the kernel to not make use of any
1348 IOAPICs that may be present in the system.
1350 nobats [PPC] Do not use BATs for mapping kernel lowmem
1351 on "Classic" PPC cores.
1355 nodelayacct [KNL] Disable per-task delay accounting
1357 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1359 noefi [X86-32,X86-64] Disable EFI runtime services support.
1363 noexec [X86-32,X86-64]
1364 On X86-32 available only on PAE configured kernels.
1365 noexec=on: enable non-executable mappings (default)
1366 noexec=off: disable non-executable mappings
1369 This affects only 32-bit executables.
1370 noexec32=on: enable non-executable mappings (default)
1371 read doesn't imply executable mappings
1372 noexec32=off: disable non-executable mappings
1373 read implies executable mappings
1375 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1376 register save and restore. The kernel will only save
1377 legacy floating-point registers on task switch.
1379 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1383 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1384 instruction doesn't work correctly and not to
1387 nohalt [IA-64] Tells the kernel not to use the power saving
1388 function PAL_HALT_LIGHT when idle. This increases
1389 power-consumption. On the positive side, it reduces
1390 interrupt wake-up latency, which may improve performance
1391 in certain environments such as networked servers or
1394 nohz= [KNL] Boottime enable/disable dynamic ticks
1395 Valid arguments: on, off
1398 noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
1400 noirqdebug [X86-32] Disables the code which attempts to detect and
1401 disable unhandled interrupt sources.
1403 no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
1404 broken timer IRQ sources.
1406 noisapnp [ISAPNP] Disables ISA PnP code.
1408 noinitrd [RAM] Tells the kernel not to load any configured
1413 nojitter [IA64] Disables jitter checking for ITC timers.
1415 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1417 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1419 noltlbs [PPC] Do not use large page/tlb entries for kernel
1420 lowmem mapping on PPC40x.
1422 nomca [IA-64] Disable machine check abort handling
1424 nomce [X86-32] Machine Check Exception
1426 nomfgpt [X86-32] Disable Multi-Function General Purpose
1427 Timer usage (for AMD Geode machines).
1429 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1431 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1432 with UP alternatives
1434 noresidual [PPC] Don't use residual data on PReP machines.
1436 noresume [SWSUSP] Disables resume and restores original swap
1439 no-scroll [VGA] Disables scrollback.
1440 This is required for the Braillex ib80-piezo Braille
1441 reader made by F.H. Papenmeier (Germany).
1445 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1447 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1448 and disable the IO APIC. legacy for "maxcpus=0".
1450 nosoftlockup [KNL] Disable the soft-lockup detector.
1452 nosync [HW,M68K] Disables sync negotiation for all devices.
1454 notsc [BUGS=X86-32] Disable Time Stamp Counter
1456 nousb [USB] Disable the USB subsystem
1460 nptcg= [IA64] Override max number of concurrent global TLB
1461 purges which is reported from either PAL_VM_SUMMARY or
1464 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1465 one of ['zone', 'node', 'default'] can be specified
1466 This can be set from sysctl after boot.
1467 See Documentation/sysctl/vm.txt for details.
1469 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1471 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1472 Rather than timing out after 20 ms if an EC
1473 command is not properly ACKed, override the length
1474 of the timeout. We have interrupts disabled while
1475 waiting for the ACK, so if this is set too high
1476 interrupts *may* be lost!
1481 oprofile.timer= [HW]
1482 Use timer interrupt instead of performance counters
1484 osst= [HW,SCSI] SCSI Tape Driver
1485 Format: <buffer_size>,<write_threshold>
1486 See also Documentation/scsi/st.txt.
1488 panic= [KNL] Kernel behaviour on panic
1491 parkbd.port= [HW] Parallel port number the keyboard adapter is
1492 connected to, default is 0.
1494 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1495 0 for XT, 1 for AT (default is AT).
1498 parport= [HW,PPT] Specify parallel ports. 0 disables.
1499 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1500 Use 'auto' to force the driver to use any
1501 IRQ/DMA settings detected (the default is to
1502 ignore detected IRQ/DMA settings because of
1503 possible conflicts). You can specify the base
1504 address, IRQ, and DMA settings; IRQ and DMA
1505 should be numbers, or 'auto' (for using detected
1506 settings on that particular port), or 'nofifo'
1507 (to avoid using a FIFO even if it is detected).
1508 Parallel ports are assigned in the order they
1509 are specified on the command line, starting
1512 parport_init_mode= [HW,PPT]
1513 Configure VIA parallel port to operate in
1514 a specific mode. This is necessary on Pegasos
1515 computer where firmware has no options for setting
1516 up parallel port mode and sets it to spp.
1517 Currently this function knows 686a and 8231 chips.
1518 Format: [spp|ps2|epp|ecp|ecpepp]
1520 pas2= [HW,OSS] Format:
1521 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1524 See header of drivers/scsi/pas16.c.
1527 Halt all CPUs after the first oops has been printed for
1528 the specified number of seconds. This is to be used if
1529 your oopses keep scrolling off the screen.
1534 See header of drivers/block/paride/pcd.c.
1535 See also Documentation/paride.txt.
1537 pci=option[,option...] [PCI] various PCI subsystem options:
1538 off [X86-32] don't probe for the PCI bus
1539 bios [X86-32] force use of PCI BIOS, don't access
1540 the hardware directly. Use this if your machine
1541 has a non-standard PCI host bridge.
1542 nobios [X86-32] disallow use of PCI BIOS, only direct
1543 hardware access methods are allowed. Use this
1544 if you experience crashes upon bootup and you
1545 suspect they are caused by the BIOS.
1546 conf1 [X86-32] Force use of PCI Configuration
1548 conf2 [X86-32] Force use of PCI Configuration
1550 noaer [PCIE] If the PCIEAER kernel config parameter is
1551 enabled, this kernel boot option can be used to
1552 disable the use of PCIE advanced error reporting.
1553 nodomains [PCI] Disable support for multiple PCI
1554 root domains (aka PCI segments, in ACPI-speak).
1555 nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
1557 nomsi [MSI] If the PCI_MSI kernel config parameter is
1558 enabled, this kernel boot option can be used to
1559 disable the use of MSI interrupts system-wide.
1560 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1561 routing table. These calls are known to be buggy
1562 on several machines and they hang the machine
1563 when used, but on other computers it's the only
1564 way to get the interrupt routing table. Try
1565 this option if the kernel is unable to allocate
1566 IRQs or discover secondary PCI buses on your
1568 rom [X86-32] Assign address space to expansion ROMs.
1569 Use with caution as certain devices share
1570 address decoders between ROMs and other
1572 norom [X86-32,X86_64] Do not assign address space to
1573 expansion ROMs that do not already have
1574 BIOS assigned address ranges.
1575 irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
1576 assigned automatically to PCI devices. You can
1577 make the kernel exclude IRQs of your ISA cards
1579 pirqaddr=0xAAAAA [X86-32] Specify the physical address
1580 of the PIRQ table (normally generated
1581 by the BIOS) if it is outside the
1582 F0000h-100000h range.
1583 lastbus=N [X86-32] Scan all buses thru bus #N. Can be
1584 useful if the kernel is unable to find your
1585 secondary buses and you want to tell it
1586 explicitly which ones they are.
1587 assign-busses [X86-32] Always assign all PCI bus
1588 numbers ourselves, overriding
1589 whatever the firmware may have done.
1590 usepirqmask [X86-32] Honor the possible IRQ mask stored
1591 in the BIOS $PIR table. This is needed on
1592 some systems with broken BIOSes, notably
1593 some HP Pavilion N5400 and Omnibook XE3
1594 notebooks. This will have no effect if ACPI
1595 IRQ routing is enabled.
1596 noacpi [X86-32] Do not use ACPI for IRQ routing
1597 or for PCI scanning.
1598 use_crs [X86-32] Use _CRS for PCI resource
1600 routeirq Do IRQ routing for all PCI devices.
1601 This is normally done in pci_enable_device(),
1602 so this option is a temporary workaround
1603 for broken drivers that don't call it.
1604 skip_isa_align [X86] do not align io start addr, so can
1605 handle more pci cards
1606 firmware [ARM] Do not re-enumerate the bus but instead
1607 just use the configuration from the
1608 bootloader. This is currently used on
1609 IXP2000 systems where the bus has to be
1610 configured a certain way for adjunct CPUs.
1611 noearly [X86] Don't do any early type 1 scanning.
1612 This might help on some broken boards which
1613 machine check when some devices' config space
1614 is read. But various workarounds are disabled
1615 and some IOMMU drivers will not work.
1616 bfsort Sort PCI devices into breadth-first order.
1617 This sorting is done to get a device
1618 order compatible with older (<= 2.4) kernels.
1619 nobfsort Don't sort PCI devices into breadth-first order.
1620 cbiosize=nn[KMG] The fixed amount of bus space which is
1621 reserved for the CardBus bridge's IO window.
1622 The default value is 256 bytes.
1623 cbmemsize=nn[KMG] The fixed amount of bus space which is
1624 reserved for the CardBus bridge's memory
1625 window. The default value is 64 megabytes.
1627 pcmv= [HW,PCMCIA] BadgePAD 4
1630 See Documentation/paride.txt.
1632 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1635 See arch/parisc/kernel/pdc_chassis.c
1638 See Documentation/paride.txt.
1641 See Documentation/paride.txt.
1643 pirq= [SMP,APIC] Manual mp-table setup
1644 See Documentation/i386/IO-APIC.txt.
1646 plip= [PPT,NET] Parallel port network link
1647 Format: { parport<nr> | timid | 0 }
1648 See also Documentation/parport.txt.
1650 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1651 Override pmtimer IOPort with a hex value.
1658 { on | off | curr | res | no-curr | no-res }
1661 [ISAPNP] Exclude IRQs for the autoconfiguration
1664 [ISAPNP] Exclude DMAs for the autoconfiguration
1666 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1667 Ranges are in pairs (I/O port base and size).
1670 [ISAPNP] Exclude memory regions for the
1672 Ranges are in pairs (memory base and size).
1674 print-fatal-signals=
1675 [KNL] debug: print fatal signals
1676 print-fatal-signals=1: print segfault info to
1680 printk.time= Show timing data prefixed to each printk message line
1681 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1683 profile= [KNL] Enable kernel profiling via /proc/profile
1684 Format: [schedule,]<number>
1685 Param: "schedule" - profile schedule points.
1686 Param: <number> - step/bucket size as a power of 2 for
1687 statistical time based profiling.
1688 Param: "sleep" - profile D-state sleeping (millisecs).
1689 Requires CONFIG_SCHEDSTATS
1690 Param: "kvm" - profile VM exits.
1692 processor.max_cstate= [HW,ACPI]
1693 Limit processor to maximum C-state
1694 max_cstate=9 overrides any DMI blacklist limit.
1696 processor.nocst [HW,ACPI]
1697 Ignore the _CST method to determine C-states,
1698 instead using the legacy FADT method
1700 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1702 See Documentation/ramdisk.txt.
1704 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1705 probe for; one of (bare|imps|exps|lifebook|any).
1706 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1708 psmouse.resetafter= [HW,MOUSE]
1709 Try to reset the device after so many bad packets
1712 [HW,MOUSE] Set desired mouse resolution, in dpi.
1713 psmouse.smartscroll=
1714 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1715 0 = disabled, 1 = enabled (default).
1717 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1719 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1722 See Documentation/paride.txt.
1725 [KNL] Number of legacy pty's. Overwrites compiled-in
1728 quiet [KNL] Disable most log messages
1733 See Documentation/md.txt.
1735 ramdisk_blocksize= [RAM]
1736 See Documentation/ramdisk.txt.
1738 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1739 See Documentation/ramdisk.txt.
1741 rcupdate.blimit= [KNL,BOOT]
1742 Set maximum number of finished RCU callbacks to process
1745 rcupdate.qhimark= [KNL,BOOT]
1746 Set threshold of queued
1747 RCU callbacks over which batch limiting is disabled.
1749 rcupdate.qlowmark= [KNL,BOOT]
1750 Set threshold of queued RCU callbacks below which
1751 batch limiting is re-enabled.
1755 Run specified binary instead of /init from the ramdisk,
1756 used for early userspace startup. See initrd.
1758 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1759 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1760 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1763 [KNL, SMP] Set scheduler's default relax_domain_level.
1764 See Documentation/cpusets.txt.
1766 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1768 reservetop= [X86-32]
1770 Reserves a hole at the top of the kernel virtual
1773 reset_devices [KNL] Force drivers to reset the underlying device
1774 during initialization.
1777 Specify the partition device for software suspend
1779 resume_offset= [SWSUSP]
1780 Specify the offset from the beginning of the partition
1781 given by "resume=" at which the swap header is located,
1782 in <PAGE_SIZE> units (needed only for swap files).
1783 See Documentation/power/swsusp-and-swap-files.txt
1785 retain_initrd [RAM] Keep initrd memory after extraction
1787 rhash_entries= [KNL,NET]
1788 Set number of hash buckets for route cache
1790 riscom8= [HW,SERIAL]
1791 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
1793 ro [KNL] Mount root device read-only on boot
1795 root= [KNL] Root filesystem
1797 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
1798 mount the root filesystem
1800 rootflags= [KNL] Set root filesystem mount option string
1802 rootfstype= [KNL] Set root filesystem type
1804 rootwait [KNL] Wait (indefinitely) for root device to show up.
1805 Useful for devices that are detected asynchronously
1806 (e.g. USB and MMC devices).
1808 root_plug.vendor_id=
1809 [ROOTPLUG] Override the default vendor ID
1811 root_plug.product_id=
1812 [ROOTPLUG] Override the default product ID
1815 [ROOTPLUG] Enable debugging output
1817 rw [KNL] Mount root device read-write on boot
1819 S [KNL] Run init in single mode
1822 See drivers/net/irda/sa1100_ir.c.
1824 sbni= [NET] Granch SBNI12 leased line adapter
1826 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
1827 Format: <io>[,<timeout>[,<isapnp>]]
1829 scsi_debug_*= [SCSI]
1830 See drivers/scsi/scsi_debug.c.
1832 scsi_default_dev_flags=
1833 [SCSI] SCSI default device flags
1836 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
1837 Format: <vendor>:<model>:<flags>
1838 (flags are integer value)
1840 scsi_logging_level= [SCSI] a bit mask of logging levels
1841 See drivers/scsi/scsi_logging.h for bits. Also
1842 settable via sysctl at dev.scsi.logging_level
1843 (/proc/sys/dev/scsi/logging_level).
1844 There is also a nice 'scsi_logging_level' script in the
1845 S390-tools package, available for download at
1846 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
1848 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
1849 discovered. async scans them in kernel threads,
1850 allowing boot to proceed. none ignores them, expecting
1851 user space to do the scan.
1853 selinux [SELINUX] Disable or enable SELinux at boot time.
1854 Format: { "0" | "1" }
1855 See security/selinux/Kconfig help text.
1858 Default value is set via kernel config option.
1859 If enabled at boot time, /selinux/disable can be used
1860 later to disable prior to initial policy load.
1862 selinux_compat_net =
1863 [SELINUX] Set initial selinux_compat_net flag value.
1864 Format: { "0" | "1" }
1865 0 -- use new secmark-based packet controls
1866 1 -- use legacy packet controls
1867 Default value is 0 (preferred).
1868 Value can be changed at runtime via
1869 /selinux/compat_net.
1871 serialnumber [BUGS=X86-32]
1874 Maximal number of shapers.
1877 See header of drivers/scsi/sim710.c.
1884 slub_debug[=options[,slabs]] [MM, SLUB]
1885 Enabling slub_debug allows one to determine the
1886 culprit if slab objects become corrupted. Enabling
1887 slub_debug can create guard zones around objects and
1888 may poison objects when not in use. Also tracks the
1889 last alloc / free. For more information see
1890 Documentation/vm/slub.txt.
1892 slub_max_order= [MM, SLUB]
1893 Determines the maximum allowed order for slabs.
1894 A high setting may cause OOMs due to memory
1895 fragmentation. For more information see
1896 Documentation/vm/slub.txt.
1898 slub_min_objects= [MM, SLUB]
1899 The minimum number of objects per slab. SLUB will
1900 increase the slab order up to slub_max_order to
1901 generate a sufficiently large slab able to contain
1902 the number of objects indicated. The higher the number
1903 of objects the smaller the overhead of tracking slabs
1904 and the less frequently locks need to be acquired.
1905 For more information see Documentation/vm/slub.txt.
1907 slub_min_order= [MM, SLUB]
1908 Determines the mininum page order for slabs. Must be
1909 lower than slub_max_order.
1910 For more information see Documentation/vm/slub.txt.
1912 slub_nomerge [MM, SLUB]
1913 Disable merging of slabs with similar size. May be
1914 necessary if there is some reason to distinguish
1915 allocs to different slabs. Debug options disable
1916 merging on their own.
1917 For more information see Documentation/vm/slub.txt.
1920 Format: <io1>[,<io2>[,...,<io8>]]
1922 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
1923 attempt to substitute SMP alternatives once at boot.
1925 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
1926 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
1927 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
1928 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
1929 smsc-ircc2.ircc_irq= [HW] IRQ line
1930 smsc-ircc2.ircc_dma= [HW] DMA channel
1931 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
1932 0: Toshiba Satellite 1800 (GP data pin select)
1933 1: Fast pin select (default)
1936 snd-ad1816a= [HW,ALSA]
1938 snd-ad1848= [HW,ALSA]
1940 snd-ali5451= [HW,ALSA]
1942 snd-als100= [HW,ALSA]
1944 snd-als4000= [HW,ALSA]
1946 snd-azt2320= [HW,ALSA]
1948 snd-cmi8330= [HW,ALSA]
1950 snd-cmipci= [HW,ALSA]
1952 snd-cs4231= [HW,ALSA]
1954 snd-cs4232= [HW,ALSA]
1956 snd-cs4236= [HW,ALSA]
1958 snd-cs4281= [HW,ALSA]
1960 snd-cs46xx= [HW,ALSA]
1962 snd-dt019x= [HW,ALSA]
1964 snd-dummy= [HW,ALSA]
1966 snd-emu10k1= [HW,ALSA]
1968 snd-ens1370= [HW,ALSA]
1970 snd-ens1371= [HW,ALSA]
1972 snd-es968= [HW,ALSA]
1974 snd-es1688= [HW,ALSA]
1976 snd-es18xx= [HW,ALSA]
1978 snd-es1938= [HW,ALSA]
1980 snd-es1968= [HW,ALSA]
1982 snd-fm801= [HW,ALSA]
1984 snd-gusclassic= [HW,ALSA]
1986 snd-gusextreme= [HW,ALSA]
1988 snd-gusmax= [HW,ALSA]
1992 snd-ice1712= [HW,ALSA]
1994 snd-intel8x0= [HW,ALSA]
1996 snd-interwave= [HW,ALSA]
2001 snd-korg1212= [HW,ALSA]
2003 snd-maestro3= [HW,ALSA]
2005 snd-mpu401= [HW,ALSA]
2007 snd-mtpav= [HW,ALSA]
2009 snd-nm256= [HW,ALSA]
2011 snd-opl3sa2= [HW,ALSA]
2019 snd-opti93x= [HW,ALSA]
2023 snd-rme32= [HW,ALSA]
2025 snd-rme96= [HW,ALSA]
2027 snd-rme9652= [HW,ALSA]
2033 snd-sbawe= [HW,ALSA]
2035 snd-serial= [HW,ALSA]
2037 snd-sgalaxy= [HW,ALSA]
2039 snd-sonicvibes= [HW,ALSA]
2044 snd-sun-cs4231= [HW,ALSA]
2046 snd-trident= [HW,ALSA]
2048 snd-usb-audio= [HW,ALSA,USB]
2050 snd-via82xx= [HW,ALSA]
2052 snd-virmidi= [HW,ALSA]
2054 snd-wavefront= [HW,ALSA]
2056 snd-ymfpci= [HW,ALSA]
2059 [KNL] Should the soft-lockup detector generate panics.
2061 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2062 See Documentation/sonypi.txt
2064 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2065 See Documentation/specialix.txt.
2067 spia_io_base= [HW,MTD]
2073 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2075 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2076 See Documentation/scsi/st.txt.
2080 Set the STI (builtin display/keyboard on the HP-PARISC
2081 machines) console (graphic card) which should be used
2082 as the initial boot-console.
2083 See also comment in drivers/video/console/sticore.c.
2086 See comment in drivers/video/console/sticore.c.
2089 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2093 Control how the NFS server code allocates CPUs to
2094 service thread pools. Depending on how many NICs
2095 you have and where their interrupts are bound, this
2096 option will affect which CPUs will do NFS serving.
2097 Note: this parameter cannot be changed while the
2098 NFS server is running.
2100 auto the server chooses an appropriate mode
2101 automatically using heuristics
2102 global a single global pool contains all CPUs
2103 percpu one pool for each CPU
2104 pernode one pool for each NUMA node (equivalent
2105 to global on non-NUMA machines)
2107 swiotlb= [IA-64] Number of I/O TLB slabs
2111 sym53c416= [HW,SCSI]
2112 See header of drivers/scsi/sym53c416.c.
2114 sysrq_always_enabled
2116 Ignore sysrq setting - this boot parameter will
2117 neutralize any effect of /proc/sys/kernel/sysrq.
2118 Useful for debugging.
2121 See header of drivers/scsi/t128.c.
2125 test_suspend= [SUSPEND]
2126 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2127 standby suspend) as the system sleep state to briefly
2128 enter during system startup. The system is woken from
2129 this state using a wakeup-capable RTC alarm.
2131 thash_entries= [KNL,NET]
2132 Set number of hash buckets for TCP connection
2134 thermal.act= [HW,ACPI]
2135 -1: disable all active trip points in all thermal zones
2136 <degrees C>: override all lowest active trip points
2138 thermal.crt= [HW,ACPI]
2139 -1: disable all critical trip points in all thermal zones
2140 <degrees C>: lower all critical trip points
2142 thermal.nocrt= [HW,ACPI]
2143 Set to disable actions on ACPI thermal zone
2144 critical and hot trip points.
2146 thermal.off= [HW,ACPI]
2147 1: disable ACPI thermal control
2149 thermal.psv= [HW,ACPI]
2150 -1: disable all passive trip points
2151 <degrees C>: override all passive trip points to this value
2153 thermal.tzp= [HW,ACPI]
2154 Specify global default ACPI thermal zone polling rate
2155 <deci-seconds>: poll all this frequency
2156 0: no polling (default)
2159 See comment before function dc390_setup() in
2160 drivers/scsi/tmscsim.c.
2164 trix= [HW,OSS] MediaTrix AudioTrix Pro
2166 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2168 turbografx.map[2|3]= [HW,JOY]
2169 TurboGraFX parallel port interface
2171 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2172 See also Documentation/input/joystick-parport.txt
2174 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2175 See header of drivers/scsi/u14-34f.c.
2184 [USB] Ignore overcurrent events (default N).
2185 Some badly-designed motherboards generate lots of
2186 bogus events, for ports that aren't wired to
2187 anything. Set this parameter to avoid log spamming.
2188 Note that genuine overcurrent events won't be
2193 Set unknown_nmi_panic=1 early on boot.
2195 usbcore.autosuspend=
2196 [USB] The autosuspend time delay (in seconds) used
2197 for newly-detected USB devices (default 2). This
2198 is the time required before an idle device will be
2199 autosuspended. Devices for which the delay is set
2200 to a negative value won't be autosuspended at all.
2203 [USBHID] The interval which mice are to be polled at.
2205 add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
2206 kernel's map of available physical RAM.
2208 vdso= [X86-32,SH,x86-64]
2209 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2210 vdso=1: enable VDSO (default)
2211 vdso=0: disable VDSO mapping
2213 vdso32= [X86-32,X86-64]
2214 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2215 vdso32=1: enable 32-bit VDSO (default)
2216 vdso32=0: disable 32-bit VDSO mapping
2219 vector=percpu: enable percpu vector domain
2221 video= [FB] Frame buffer configuration
2222 See Documentation/fb/modedb.txt.
2224 vga= [BOOT,X86-32] Select a particular video mode
2225 See Documentation/i386/boot.txt and
2226 Documentation/svga.txt.
2227 Use vga=ask for menu.
2228 This is actually a boot loader parameter; the value is
2229 passed to the kernel using a special protocol.
2231 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2232 size of <nn>. This can be used to increase the
2233 minimum size (128MB on x86). It can also be used to
2234 decrease the size and leave more room for directly
2237 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2240 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2243 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2246 waveartist= [HW,OSS]
2247 Format: <io>,<irq>,<dma>,<dma2>
2250 See header of drivers/scsi/wd33c93.c.
2253 See header of drivers/scsi/wd7000.c.
2256 See Documentation/watchdog/wdt.txt.
2258 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2259 xd_geo= See header of drivers/block/xd.c.
2261 xirc2ps_cs= [NET,PCMCIA]
2263 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2265 norandmaps Don't use address space randomization
2266 Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
2268 ______________________________________________________________________
2272 Add documentation for ALSA options.
2273 Add more DRM drivers.