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 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 AVR32 AVR32 architecture is enabled.
44 AX25 Appropriate AX.25 support is enabled.
45 BLACKFIN Blackfin architecture is enabled.
46 DRM Direct Rendering Management support is enabled.
47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
51 GCOV GCOV profiling is enabled.
52 HW Appropriate hardware is enabled.
53 IA-64 IA-64 architecture is enabled.
54 IMA Integrity measurement architecture is enabled.
55 IOSCHED More than one I/O scheduler is enabled.
56 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
57 ISAPNP ISA PnP code is enabled.
58 ISDN Appropriate ISDN support is enabled.
59 JOY Appropriate joystick support is enabled.
60 KVM Kernel Virtual Machine support is enabled.
61 LIBATA Libata driver is enabled
62 LP Printer support is enabled.
63 LOOP Loopback device support is enabled.
64 M68k M68k architecture is enabled.
65 These options have more detailed description inside of
66 Documentation/m68k/kernel-options.txt.
67 MCA MCA bus support is enabled.
68 MDA MDA console support is enabled.
69 MOUSE Appropriate mouse support is enabled.
70 MSI Message Signaled Interrupts (PCI).
71 MTD MTD (Memory Technology Device) support is enabled.
72 NET Appropriate network support is enabled.
73 NUMA NUMA support is enabled.
74 GENERIC_TIME The generic timeofday code is enabled.
75 NFS Appropriate NFS support is enabled.
76 OSS OSS sound support is enabled.
77 PV_OPS A paravirtualized kernel is enabled.
78 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
79 PARISC The PA-RISC architecture is enabled.
80 PCI PCI bus support is enabled.
81 PCIE PCI Express support is enabled.
82 PCMCIA The PCMCIA subsystem is enabled.
83 PNP Plug & Play support is enabled.
84 PPC PowerPC architecture is enabled.
85 PPT Parallel port support is enabled.
86 PS2 Appropriate PS/2 support is enabled.
87 RAM RAM disk support is enabled.
88 ROOTPLUG The example Root Plug LSM is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
93 SECURITY Different security models are enabled.
94 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
96 SH SuperH architecture is enabled.
97 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
99 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
101 FTRACE Function tracing enabled.
102 TS Appropriate touchscreen support is enabled.
103 UMS USB Mass Storage support is enabled.
104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
111 X86-32 X86-32, aka i386 architecture is enabled.
112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
114 Documentation/x86/x86_64/boot-options.txt .
115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
117 In addition, the following text indicates that the option:
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
123 Parameters denoted with BOOT are actually interpreted by the boot
124 loader, and have no meaning to the kernel directly.
125 Do not modify the syntax of boot loader parameters without extreme
126 need or coordination with <Documentation/x86/boot.txt>.
128 There are also arch-specific kernel-parameters not documented here.
129 See for example <Documentation/x86/x86_64/boot-options.txt>.
131 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132 a trailing = on the name of any parameter states that that parameter will
133 be entered as an environment variable, whereas its absence indicates that
134 it will appear as a kernel argument readable via /proc/cmdline by programs
135 running once the system is up.
137 The number of kernel parameters is not limited, but the length of the
138 complete command line (parameters including spaces etc.) is limited to
139 a fixed number of characters. This limit depends on the architecture
140 and is between 256 and 4096 characters. It is defined in the file
141 ./include/asm/setup.h as COMMAND_LINE_SIZE.
145 Advanced Configuration and Power Interface
146 Format: { force | off | ht | strict | noirq | rsdt }
147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
151 strict -- Be less tolerant of platforms that are not
152 strictly ACPI specification compliant.
153 rsdt -- prefer RSDT over (default) XSDT
155 See also Documentation/power/pm.txt, pci=noacpi
157 acpi_apic_instance= [ACPI, IOAPIC]
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
203 acpi_irq_balance [HW,ACPI]
204 ACPI will balance active IRQs
207 acpi_irq_nobalance [HW,ACPI]
208 ACPI will not move active IRQs (default)
211 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
212 Format: <irq>,<irq>...
214 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
216 Format: <irq>,<irq>...
218 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
220 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
221 Format: To spoof as Windows 98: ="Microsoft Windows"
223 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
224 acpi_osi="string1" # add string1 -- only one string
225 acpi_osi="!string2" # remove built-in string2
226 acpi_osi= # disable all strings
229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
233 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
234 Format: { level | edge | high | low }
236 acpi_serialize [HW,ACPI] force serialization of AML methods
238 acpi_skip_timer_override [HW,ACPI]
239 Recognize and ignore IRQ0/pin2 Interrupt Override.
240 For broken nForce2 BIOS resulting in XT-PIC timer.
242 acpi_sleep= [HW,ACPI] Sleep options
243 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
244 old_ordering, s4_nonvs }
245 See Documentation/power/video.txt for information on
247 s3_beep is for debugging; it makes the PC's speaker beep
248 as soon as the kernel's real-mode entry point is called.
249 s4_nohwsig prevents ACPI hardware signature from being
250 used during resume from hibernation.
251 old_ordering causes the ACPI 1.0 ordering of the _PTS
252 control method, with respect to putting devices into
253 low power states, to be enforced (the ACPI 2.0 ordering
254 of _PTS is used by default).
255 s4_nonvs prevents the kernel from saving/restoring the
256 ACPI NVS memory during hibernation.
258 acpi_use_timer_override [HW,ACPI]
259 Use timer override. For some broken Nvidia NF5 boards
260 that require a timer override, but don't have HPET
262 acpi_enforce_resources= [ACPI]
263 { strict | lax | no }
264 Check for resource conflicts between native drivers
265 and ACPI OperationRegions (SystemIO and SystemMemory
266 only). IO ports and memory declared in ACPI might be
267 used by the ACPI subsystem in arbitrary AML code and
268 can interfere with legacy drivers.
269 strict (default): access to resources claimed by ACPI
270 is denied; legacy drivers trying to access reserved
271 resources will fail to bind to device using them.
272 lax: access to resources claimed by ACPI is allowed;
273 legacy drivers trying to access reserved resources
274 will bind successfully but a warning message is logged.
275 no: ACPI OperationRegions are not marked as reserved,
276 no further checks are performed.
279 Format: <io>,<irq>,<dma>,<dma2>,<type>
281 add_efi_memmap [EFI; X86] Include EFI memory map in
282 kernel's map of available physical RAM.
285 See header of drivers/scsi/advansys.c.
287 advwdt= [HW,WDT] Advantech WDT
288 Format: <iostart>,<iostop>
290 aedsp16= [HW,OSS] Audio Excel DSP 16
291 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
292 See also header of sound/oss/aedsp16.c.
295 { off | try_unsupported }
296 off: disable AGP support
297 try_unsupported: try to drive unsupported chipsets
298 (may crash computer or cause data corruption)
301 See Documentation/scsi/aha152x.txt.
304 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
307 See Documentation/scsi/aic7xxx.txt.
310 See Documentation/scsi/aic79xx.txt.
312 amd_iommu= [HW,X86-84]
313 Pass parameters to the AMD IOMMU driver in the system.
315 isolate - enable device isolation (each device, as far
316 as possible, will get its own protection
318 share - put every device behind one IOMMU into the
319 same protection domain
320 fullflush - enable flushing of IO/TLB entries when
321 they are unmapped. Otherwise they are
322 flushed before they will be reused, which
325 amijoy.map= [HW,JOY] Amiga joystick support
326 Map of devices attached to JOY0DAT and JOY1DAT
328 See also Documentation/kernel/input/joystick.txt
330 analog.map= [HW,JOY] Analog joystick and gamepad support
331 Specifies type or capabilities of an analog joystick
332 connected to one of 16 gameports
333 Format: <type1>,<type2>,..<type16>
336 Power management functions (SPARCstation-4/5 + deriv.)
338 Disable APC CPU standby support. SPARCstation-Fox does
339 not play well with APC CPU idle - disable it if you have
340 APC and your system crashes randomly.
342 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
343 Change the output verbosity whilst booting
344 Format: { quiet (default) | verbose | debug }
345 Change the amount of debugging information output
346 when initialising the APIC and IO-APIC components.
348 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
349 Limit apic dumping. The parameter defines the maximal
350 number of local apics being dumped. Also it is possible
351 to set it to "all" by meaning -- no limit here.
352 Format: { 1 (default) | 2 | ... | all }.
353 The parameter valid if only apic=debug or
354 apic=verbose is specified.
355 Example: apic=debug show_lapic=all
357 apm= [APM] Advanced Power Management
358 See header of arch/x86/kernel/apm_32.c.
360 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
361 Format: <io>,<irq>,<nodeID>
365 atarimouse= [HW,MOUSE] Atari Mouse
367 atascsi= [HW,SCSI] Atari SCSI
369 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
370 EzKey and similar keyboards
372 atkbd.reset= [HW] Reset keyboard during initialization
374 atkbd.set= [HW] Select keyboard code set
375 Format: <int> (2 = AT (default), 3 = PS/2)
377 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
380 atkbd.softraw= [HW] Choose between synthetic and real raw mode
381 Format: <bool> (0 = real, 1 = synthetic (default))
383 atkbd.softrepeat= [HW]
384 Use software keyboard repeat
388 baycom_epp= [HW,AX25]
391 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
393 See header of drivers/net/hamradio/baycom_par.c.
395 baycom_ser_fdx= [HW,AX25]
396 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
397 Format: <io>,<irq>,<mode>[,<baud>]
398 See header of drivers/net/hamradio/baycom_ser_fdx.c.
400 baycom_ser_hdx= [HW,AX25]
401 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
402 Format: <io>,<irq>,<mode>
403 See header of drivers/net/hamradio/baycom_ser_hdx.c.
405 boot_delay= Milliseconds to delay each printk during boot.
406 Values larger than 10 seconds (10000) are changed to
410 bootmem_debug [KNL] Enable bootmem allocator debug messages.
412 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
413 bttv.radio= Most important insmod options are available as
415 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
416 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
419 See drivers/scsi/BusLogic.c, comment before function
420 BusLogic_ParseDriverOptions().
422 c101= [NET] Moxa C101 synchronous serial card
424 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
425 Sometimes CPU hardware bugs make them report the cache
426 size incorrectly. The kernel will attempt work arounds
427 to fix known problems, but for some CPUs it is not
428 possible to determine what the correct size should be.
429 This option provides an override for these situations.
432 [SECURITY] Disable capabilities. This would normally
433 be used only if an alternative security model is to be
434 configured. Potentially dangerous and should only be
435 used if you are entirely sure of the consequences.
437 ccw_timeout_log [S390]
438 See Documentation/s390/CommonIO for details.
440 cgroup_disable= [KNL] Disable a particular controller
441 Format: {name of the controller(s) to disable}
442 {Currently supported controllers - "memory"}
444 checkreqprot [SELINUX] Set initial checkreqprot flag value.
445 Format: { "0" | "1" }
446 See security/selinux/Kconfig help text.
447 0 -- check protection applied by kernel (includes
448 any implied execute protection).
449 1 -- check protection requested by application.
450 Default value is set via a kernel config option.
451 Value can be changed at runtime via
452 /selinux/checkreqprot.
455 See Documentation/s390/CommonIO for details.
457 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
459 Forces specified clocksource (if available) to be used
460 when calculating gettimeofday(). If specified
461 clocksource is not available, it defaults to PIT.
462 Format: { pit | tsc | cyclone | pmtmr }
464 clocksource= [GENERIC_TIME] Override the default clocksource
466 Override the default clocksource and use the clocksource
467 with the name specified.
468 Some clocksource names to choose from, depending on
470 [all] jiffies (this is the base, fallback clocksource)
472 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
473 pxa_timer,timer3,32k_counter,timer0_1
475 [X86-32] pit,hpet,tsc,vmi-timer;
476 scx200_hrt on Geode; cyclone on IBM x440
484 clearcpuid=BITNUM [X86]
485 Disable CPUID feature X for the kernel. See
486 arch/x86/include/asm/cpufeature.h for the valid bit
487 numbers. Note the Linux specific bits are not necessarily
488 stable over kernel options, but the vendor specific
490 Also note that user programs calling CPUID directly
491 or using the feature without checking anything
492 will still see it. This just prevents it from
493 being used by the kernel or shown in /proc/cpuinfo.
494 Also note the kernel might malfunction if you disable
497 cmo_free_hint= [PPC] Format: { yes | no }
498 Specify whether pages are marked as being inactive
499 when they are freed. This is used in CMO environments
500 to determine OS memory pressure for page stealing by
504 code_bytes [X86] How many bytes of object code to print
509 com20020= [HW,NET] ARCnet - COM20020 chipset
511 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
513 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
517 ARCnet - COM90xx chipset (memory-mapped buffers)
518 Format: <io>[,<irq>[,<memstart>]]
520 condev= [HW,S390] console device
523 console= [KNL] Output console device and options.
525 tty<n> Use the virtual console device <n>.
529 Use the specified serial port. The options are of
530 the form "bbbbpnf", where "bbbb" is the baud rate,
531 "p" is parity ("n", "o", or "e"), "n" is number of
532 bits, and "f" is flow control ("r" for RTS or
533 omit it). Default is "9600n8".
535 See Documentation/serial-console.txt for more
537 Documentation/networking/netconsole.txt for an
540 uart[8250],io,<addr>[,options]
541 uart[8250],mmio,<addr>[,options]
542 Start an early, polled-mode console on the 8250/16550
543 UART at the specified I/O port or MMIO address,
544 switching to the matching ttyS device later. The
545 options are the same as for ttyS, above.
547 If the device connected to the port is not a TTY but a braille
548 device, prepend "brl," before the device type, for instance
550 For now, only VisioBraille is supported.
552 consoleblank= [KNL] The console blank (screen saver) timeout in
553 seconds. Defaults to 10*60 = 10mins. A value of 0
554 disables the blank timer.
557 [KNL] Change the default value for
558 /proc/<pid>/coredump_filter.
559 See also Documentation/filesystems/proc.txt.
561 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
563 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
565 crashkernel=nn[KMG]@ss[KMG]
566 [KNL] Reserve a chunk of physical memory to
567 hold a kernel to switch to with kexec on panic.
569 crashkernel=range1:size1[,range2:size2,...][@offset]
570 [KNL] Same as above, but depends on the memory
571 in the running system. The syntax of range is
572 start-[end] where start and end are both
573 a memory unit (amount[KMG]). See also
574 Documentation/kdump/kdump.txt for a example.
579 cs89x0_media= [HW,NET]
580 Format: { rj45 | aui | bnc }
583 See header of drivers/s390/block/dasd_devmap.c.
585 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
586 (one device per port)
587 Format: <port#>,<type>
588 See also Documentation/input/joystick-parport.txt
590 debug [KNL] Enable kernel debugging (events log level).
593 [KNL] verbose self-tests
595 Print debugging info while doing the locking API
597 We default to 0 (no extra messages), setting it to
598 1 will print _a lot_ more information - normally
599 only useful to kernel developers.
601 debug_objects [KNL] Enable object debugging
604 [KNL] Disable object debugging
606 debugpat [X86] Enable PAT debugging
608 decnet.addr= [HW,NET]
609 Format: <area>[,<node>]
610 See also Documentation/networking/decnet.txt.
613 [same as hugepagesz=] The size of the default
614 HugeTLB page size. This is the size represented by
615 the legacy /proc/ hugepages APIs, used for SHM, and
616 default size when mounting hugetlbfs filesystems.
617 Defaults to the default architecture's huge page size
621 Set number of hash buckets for dentry cache.
624 IO parameters + enable/disable command.
626 digiepca= [HW,SERIAL]
627 See drivers/char/README.epca and
628 Documentation/serial/digiepca.txt.
630 disable_mtrr_cleanup [X86]
631 The kernel tries to adjust MTRR layout from continuous
632 to discrete, to make X server driver able to add WB
633 entry later. This parameter disables that.
635 disable_mtrr_trim [X86, Intel and AMD only]
636 By default the kernel will trim any uncacheable
637 memory out of your available memory pool based on
638 MTRR settings. This parameter disables that behavior,
639 possibly causing your machine to run very slowly.
641 disable_timer_pin_1 [X86]
642 Disable PIN 1 of APIC timer
643 Can be useful to work around chipset bugs.
645 dmasound= [HW,OSS] Sound subsystem buffers
647 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
648 this option disables the debugging code at boot.
650 dma_debug_entries=<number>
651 This option allows to tune the number of preallocated
652 entries for DMA-API debugging code. One entry is
653 required per DMA-API allocation. Use this if the
654 DMA-API debugging code disables itself because the
655 architectural default is too low.
657 dma_debug_driver=<driver_name>
658 With this option the DMA-API debugging driver
659 filter feature can be enabled at boot time. Just
660 pass the driver to filter for as the parameter.
661 The filter can be disabled or changed to another
662 driver later using sysfs.
668 dynamic_printk Enables pr_debug()/dev_dbg() calls if
669 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
670 These can also be switched on/off via
671 <debugfs>/dynamic_printk/modules
673 earlycon= [KNL] Output early console device and options.
674 uart[8250],io,<addr>[,options]
675 uart[8250],mmio,<addr>[,options]
676 Start an early, polled-mode console on the 8250/16550
677 UART at the specified I/O port or MMIO address.
678 The options are the same as for ttyS, above.
680 earlyprintk= [X86,SH,BLACKFIN]
682 earlyprintk=serial[,ttySn[,baudrate]]
683 earlyprintk=ttySn[,baudrate]
684 earlyprintk=dbgp[debugController#]
686 Append ",keep" to not disable it when the real console
689 Only vga or serial or usb debug port at a time.
691 Currently only ttyS0 and ttyS1 are supported.
693 Interaction with the standard serial driver is not
696 The VGA output is eventually overwritten by the real
702 Format: {"off" | "on" | "skip[mbr]"}
704 eisa_irq_edge= [PARISC,HW]
705 See header of drivers/parisc/eisa.c.
708 See comment before function elanfreq_setup() in
709 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
712 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
713 See Documentation/block/as-iosched.txt and
714 Documentation/block/deadline-iosched.txt for details.
716 elfcorehdr= [IA64,PPC,SH,X86]
717 Specifies physical address of start of kernel core
718 image elf header. Generally kexec loader will
719 pass this option to capture kernel.
720 See Documentation/kdump/kdump.txt for details.
722 enable_mtrr_cleanup [X86]
723 The kernel tries to adjust MTRR layout from continuous
724 to discrete, to make X server driver able to add WB
725 entry later. This parameter enables that.
727 enable_timer_pin_1 [X86]
728 Enable PIN 1 of APIC timer
729 Can be useful to work around chipset bugs
730 (in particular on some ATI chipsets).
731 The kernel tries to set a reasonable default.
733 enforcing [SELINUX] Set initial enforcing status.
735 See security/selinux/Kconfig help text.
736 0 -- permissive (log only, no denials).
737 1 -- enforcing (deny and log).
739 Value can be changed at runtime via /selinux/enforce.
741 ether= [HW,NET] Ethernet cards parameters
742 This option is obsoleted by the "netdev=" option, which
743 has equivalent usage. See its documentation for details.
745 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
750 fail_make_request=[KNL]
751 General fault injection mechanism.
752 Format: <interval>,<probability>,<space>,<times>
753 See also /Documentation/fault-injection/.
756 See header of drivers/scsi/fd_mcs.c.
759 See header of drivers/scsi/fdomain.c.
762 See Documentation/blockdev/floppy.txt.
764 force_pal_cache_flush
765 [IA-64] Avoid check_sal_cache_flush which may hang on
766 buggy SAL_CACHE_FLUSH implementations. Using this
767 parameter will force ia64_sal_cache_flush to call
768 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
771 [FTRACE] will set and start the specified tracer
772 as early as possible in order to facilitate early
776 [FTRACE] will dump the trace buffers on oops.
778 ftrace_filter=[function-list]
779 [FTRACE] Limit the functions traced by the function
780 tracer at boot up. function-list is a comma separated
781 list of functions. This list can be changed at run
782 time by the set_ftrace_filter file in the debugfs
785 ftrace_notrace=[function-list]
786 [FTRACE] Do not trace the functions specified in
787 function-list. This list can be changed at run time
788 by the set_ftrace_notrace file in the debugfs
792 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
793 support via parallel port (up to 5 devices per port)
794 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
795 See also Documentation/input/joystick-parport.txt
799 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
803 gcov_persist= [GCOV] When non-zero (default), profiling data for
804 kernel modules is saved and remains accessible via
805 debugfs, even when the module is unloaded/reloaded.
806 When zero, profiling data is discarded and associated
807 debugfs files are removed at module unload time.
810 See header of drivers/scsi/gdth.c.
812 gpt [EFI] Forces disk with valid GPT signature but
813 invalid Protective MBR to be treated as GPT.
817 hashdist= [KNL,NUMA] Large hashes allocated during boot
818 are distributed across NUMA nodes. Defaults on
819 for 64bit NUMA, off otherwise.
820 Format: 0 | 1 (for off | on)
822 hcl= [IA-64] SGI's Hardware Graph compatibility layer
824 hd= [EIDE] (E)IDE hard drive subsystem geometry
825 Format: <cyl>,<head>,<sect>
827 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
828 size of <nn>. This works even on boxes that have no
829 highmem otherwise. This also works to reduce highmem
830 size on bigger boxes.
832 highres= [KNL] Enable/disable high resolution timer mode.
833 Valid parameters: "on", "off"
837 See Documentation/isdn/README.HiSax.
841 hpet= [X86-32,HPET] option to control HPET usage
842 Format: { enable (default) | disable | force |
844 disable: disable HPET and use PIT instead
845 force: allow force enabled of undocumented chips (ICH4,
847 verbose: show contents of HPET registers during setup
849 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
850 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
851 On x86-64 and powerpc, this option can be specified
852 multiple times interleaved with hugepages= to reserve
853 huge pages of different sizes. Valid pages sizes on
854 x86-64 are 2M (when the CPU supports "pse") and 1G
855 (when the CPU supports the "pdpe1gb" cpuinfo flag)
856 Note that 1GB pages can only be allocated at boot time
857 using hugepages= and not freed afterwards.
859 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
860 terminal devices. Valid values: 0..8
861 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
862 If specified, z/VM IUCV HVC accepts connections
863 from listed z/VM user IDs only.
865 i2c_bus= [HW] Override the default board specific I2C bus speed
866 or register an additional I2C bus that is not
867 registered from board initialization code.
871 i8042.debug [HW] Toggle i8042 debug mode
872 i8042.direct [HW] Put keyboard port into non-translated mode
873 i8042.dumbkbd [HW] Pretend that controller can only read data from
874 keyboard and cannot control its state
875 (Don't attempt to blink the leds)
876 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
877 i8042.nokbd [HW] Don't check/create keyboard port
878 i8042.noloop [HW] Disable the AUX Loopback command while probing
880 i8042.nomux [HW] Don't check presence of an active multiplexing
882 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
885 [HW] Frequency with which keyboard LEDs should blink
886 when kernel panics (default is 0.5 sec)
887 i8042.reset [HW] Reset the controller during init and cleanup
888 i8042.unlock [HW] Unlock (ignore) the keylock
892 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
893 indicates that the driver is running on unsupported
895 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
896 does not match list of supported models.
898 [HW] Report power status in /proc/i8k
899 (disabled by default)
900 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
903 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
904 See Documentation/mca.txt.
907 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
909 ide-core.nodma= [HW] (E)IDE subsystem
910 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
911 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
912 .cdrom .chs .ignore_cable are additional options
913 See Documentation/ide/ide.txt.
915 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
916 Claim all unknown PCI IDE storage controllers.
919 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
920 Poll forces a polling idle loop that can slightly
921 improve the performance of waking up a idle CPU, but
922 will use a lot of power and make the system run hot.
924 idle=mwait: On systems which support MONITOR/MWAIT but
925 the kernel chose to not use it because it doesn't save
926 as much power as a normal idle loop, use the
927 MONITOR/MWAIT idle loop anyways. Performance should be
928 the same as idle=poll.
929 idle=halt: Halt is forced to be used for CPU idle.
930 In such case C2/C3 won't be used again.
931 idle=nomwait: Disable mwait for CPU C-states
933 ignore_loglevel [KNL]
934 Ignore loglevel setting - this will print /all/
935 kernel messages to the console. Useful for debugging.
938 Set number of hash buckets for inode cache.
941 Format: { "0" | "1" }
942 0 -- integrity auditing messages. (Default)
943 1 -- enable informational integrity auditing messages.
946 Format: { "sha1" | "md5" }
950 Load a policy which meets the needs of the Trusted
951 Computing Base. This means IMA will measure all
952 programs exec'd, files mmap'd for exec, and all files
953 opened for read by uid=0.
956 See header of drivers/scsi/in2000.c.
960 Run specified binary instead of /sbin/init as init
963 initcall_debug [KNL] Trace initcalls as they are executed. Useful
964 for working out where the kernel is dying during
967 initrd= [BOOT] Specify the location of the initial ramdisk
969 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
972 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
974 Enable intel iommu driver.
976 Disable intel iommu driver.
977 igfx_off [Default Off]
978 By default, gfx is mapped as normal device. If a gfx
979 device has a dedicated DMAR unit, the DMAR unit is
980 bypassed by not enabling DMAR with this option. In
981 this case, gfx device will use physical address for
984 With this option iommu will not optimize to look
985 for io virtual address below 32 bit forcing dual
986 address cycle on pci bus for cards supporting greater
987 than 32 bit addressing. The default is to look
988 for translation below 32 bit and if not available
989 then look in the higher range.
991 With this option on every unmap_single operation will
992 result in a hardware IOTLB flush operation as opposed
993 to batching them for performance.
997 iomem= Disable strict checking of access to MMIO memory
998 strict regions from userspace.
1014 io7= [HW] IO7 for Marvel based alpha systems
1015 See comment before marvel_specify_io7 in
1016 arch/alpha/kernel/core_marvel.c.
1018 io_delay= [X86] I/O delay method
1020 Standard port 0x80 based delay
1022 Alternate port 0xed based delay (needed on some systems)
1024 Simple two microseconds delay
1029 See Documentation/filesystems/nfsroot.txt.
1031 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1032 See comment before ip2_setup() in
1033 drivers/char/ip2/ip2base.c.
1035 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1036 See header of drivers/scsi/ips.c.
1039 When an interrupt is not handled search all handlers
1040 for it. Intended to get systems with badly broken
1044 When an interrupt is not handled search all handlers
1045 for it. Also check all handlers each timer
1046 interrupt. Intended to get systems with badly broken
1050 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1052 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1054 <cpu number>,...,<cpu number>
1056 <cpu number>-<cpu number>
1057 (must be a positive range in ascending order)
1059 <cpu number>,...,<cpu number>-<cpu number>
1061 This option can be used to specify one or more CPUs
1062 to isolate from the general SMP balancing and scheduling
1063 algorithms. You can move a process onto or off an
1064 "isolated" CPU via the CPU affinity syscalls or cpuset.
1065 <cpu number> begins at 0 and the maximum value is
1066 "number of CPUs in system - 1".
1068 This option is the preferred way to isolate CPUs. The
1069 alternative -- manually setting the CPU mask of all
1070 tasks in the system -- can cause problems and
1071 suboptimal load balancer performance.
1075 js= [HW,JOY] Analog joystick
1076 See Documentation/input/joystick.txt.
1080 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1081 specifies the amount of memory usable by the kernel
1082 for non-movable allocations. The requested amount is
1083 spread evenly throughout all nodes in the system. The
1084 remaining memory in each node is used for Movable
1085 pages. In the event, a node is too small to have both
1086 kernelcore and Movable pages, kernelcore pages will
1087 take priority and other nodes will have a larger number
1088 of kernelcore pages. The Movable zone is used for the
1089 allocation of pages that may be reclaimed or moved
1090 by the page migration subsystem. This means that
1091 HugeTLB pages may not be allocated from this zone.
1092 Note that allocations like PTEs-from-HighMem still
1093 use the HighMem zone if it exists, and the Normal
1094 zone if it does not.
1096 kgdboc= [HW] kgdb over consoles.
1097 Requires a tty driver that supports console polling.
1098 (only serial supported for now)
1099 Format: <serial_device>[,baud]
1101 kmac= [MIPS] korina ethernet MAC address.
1102 Configure the RouterBoard 532 series on-chip
1103 Ethernet adapter MAC address.
1105 kmemleak= [KNL] Boot-time kmemleak enable/disable
1106 Valid arguments: on, off
1109 kstack=N [X86] Print N words from the kernel stack
1112 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1113 Default is 0 (don't ignore, but inject #GP)
1115 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1116 Default is 1 (enabled)
1118 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1121 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1123 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1125 kvm-intel.bypass_guest_pf=
1126 [KVM,Intel] Disables bypassing of guest page faults
1127 on Intel chips. Default is 1 (enabled)
1129 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1130 (virtualized MMU) support on capable Intel chips.
1131 Default is 1 (enabled)
1133 kvm-intel.emulate_invalid_guest_state=
1134 [KVM,Intel] Enable emulation of invalid guest states
1135 Default is 0 (disabled)
1137 kvm-intel.flexpriority=
1138 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1139 Default is 1 (enabled)
1141 kvm-intel.unrestricted_guest=
1142 [KVM,Intel] Disable unrestricted guest feature
1143 (virtualized real and unpaged mode) on capable
1144 Intel chips. Default is 1 (enabled)
1146 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1147 feature (tagged TLBs) on capable Intel chips.
1148 Default is 1 (enabled)
1154 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1157 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1160 libata.dma= [LIBATA] DMA control
1161 libata.dma=0 Disable all PATA and SATA DMA
1162 libata.dma=1 PATA and SATA Disk DMA only
1163 libata.dma=2 ATAPI (CDROM) DMA only
1164 libata.dma=4 Compact Flash DMA only
1165 Combinations also work, so libata.dma=3 enables DMA
1166 for disks and CDROMs, but not CFs.
1168 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1169 libata.ignore_hpa=0 keep BIOS limits (default)
1170 libata.ignore_hpa=1 ignore limits, using full disk
1172 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1176 libata.force= [LIBATA] Force configurations. The format is comma
1177 separated list of "[ID:]VAL" where ID is
1178 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1179 matching port, link or device. Basically, it matches
1180 the ATA ID string printed on console by libata. If
1181 the whole ID part is omitted, the last PORT and DEVICE
1182 values are used. If ID hasn't been specified yet, the
1183 configuration applies to all ports, links and devices.
1185 If only DEVICE is omitted, the parameter applies to
1186 the port and all links and devices behind it. DEVICE
1187 number of 0 either selects the first device or the
1188 first fan-out link behind PMP device. It does not
1189 select the host link. DEVICE number of 15 selects the
1190 host link and device attached to it.
1192 The VAL specifies the configuration to force. As long
1193 as there's no ambiguity shortcut notation is allowed.
1194 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1195 The following configurations can be forced.
1197 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1198 Any ID with matching PORT is used.
1200 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1202 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1203 udma[/][16,25,33,44,66,100,133] notation is also
1206 * [no]ncq: Turn on or off NCQ.
1208 * nohrst, nosrst, norst: suppress hard, soft
1211 If there are multiple matching configurations changing
1212 the same attribute, the last one is used.
1214 lmb=debug [KNL] Enable lmb debug messages.
1216 load_ramdisk= [RAM] List of ramdisks to load from floppy
1217 See Documentation/blockdev/ramdisk.txt.
1219 lockd.nlm_grace_period=P [NFS] Assign grace period.
1222 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1225 lockd.nlm_timeout=T [NFS] Assign timeout value.
1228 lockd.nlm_udpport=M [NFS] Assign UDP port.
1231 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1234 loglevel= All Kernel Messages with a loglevel smaller than the
1235 console loglevel will be printed to the console. It can
1236 also be changed with klogd or other programs. The
1237 loglevels are defined as follows:
1239 0 (KERN_EMERG) system is unusable
1240 1 (KERN_ALERT) action must be taken immediately
1241 2 (KERN_CRIT) critical conditions
1242 3 (KERN_ERR) error conditions
1243 4 (KERN_WARNING) warning conditions
1244 5 (KERN_NOTICE) normal but significant condition
1245 6 (KERN_INFO) informational
1246 7 (KERN_DEBUG) debug-level messages
1248 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1249 Format: { n | nk | nM }
1250 n must be a power of two. The default size
1251 is set in the kernel config file.
1253 logo.nologo [FB] Disables display of the built-in Linux logo.
1254 This may be used to provide more screen space for
1255 kernel log messages and is useful when debugging
1256 kernel boot problems.
1258 lp=0 [LP] Specify parallel ports to use, e.g,
1259 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1260 lp=reset first parallel port). 'lp=0' disables the
1261 lp=auto printer driver. 'lp=reset' (which can be
1262 specified in addition to the ports) causes
1263 attached printers to be reset. Using
1264 lp=port1,port2,... specifies the parallel ports
1265 to associate lp devices with, starting with
1266 lp0. A port specification may be 'none' to skip
1267 that lp device, or a parport name such as
1268 'parport0'. Specifying 'lp=auto' instead of a
1269 port specification list means that device IDs
1270 from each port should be examined, to see if
1271 an IEEE 1284-compliant printer is attached; if
1272 so, the driver will manage that printer.
1273 See also header of drivers/char/lp.c.
1276 Sets loops_per_jiffy to given constant, thus avoiding
1277 time-consuming boot-time autodetection (up to 250 ms per
1278 CPU). 0 enables autodetection (default). To determine
1279 the correct value for your kernel, boot with normal
1280 autodetection and see what value is printed. Note that
1281 on SMP systems the preset will be applied to all CPUs,
1282 which is likely to cause problems if your CPUs need
1283 significantly divergent settings. An incorrect value
1284 will cause delays in the kernel to be wrong, leading to
1285 unpredictable I/O errors and other breakage. Although
1286 unlikely, in the extreme case this might damage your
1290 Format: <io>,<irq>,<dma>
1292 mac5380= [HW,SCSI] Format:
1293 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1295 machvec= [IA64] Force the use of a particular machine-vector
1296 (machvec) in a generic kernel.
1297 Example: machvec=hpzx1_swiotlb
1299 machtype= [Loongson] Share the same kernel image file between different
1301 Example: machtype=lemote-yeeloong-2f-7inch
1303 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1304 than or equal to this physical address is ignored.
1306 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1307 should make use of. maxcpus=n : n >= 0 limits the
1308 kernel to using 'n' processors. n=0 is a special case,
1309 it is equivalent to "nosmp", which also disables
1312 max_loop= [LOOP] Maximum number of loopback devices that can
1316 max_luns= [SCSI] Maximum number of LUNs to probe.
1317 Should be between 1 and 2^32-1.
1320 [SCSI] Maximum number of LUNs received.
1321 Should be between 1 and 16384.
1325 mce [X86-32] Machine Check Exception
1327 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1329 md= [HW] RAID subsystems devices and level
1330 See Documentation/md.txt.
1333 Format: <first>,<last>
1334 Specifies range of consoles to be captured by the MDA.
1336 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1337 Amount of memory to be used when the kernel is not able
1338 to see the whole system memory or for test.
1339 [X86-32] Use together with memmap= to avoid physical
1340 address space collisions. Without memmap= PCI devices
1341 could be placed at addresses belonging to unused RAM.
1343 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1347 [KNL,SH] Allow user to override the default size for
1348 per-device physically contiguous DMA buffers.
1350 memmap=exactmap [KNL,X86] Enable setting of an exact
1351 E820 memory map, as specified by the user.
1352 Such memmap=exactmap lines can be constructed based on
1353 BIOS output or other requirements. See the memmap=nn@ss
1356 memmap=nn[KMG]@ss[KMG]
1357 [KNL] Force usage of a specific region of memory
1358 Region of memory to be used, from ss to ss+nn.
1360 memmap=nn[KMG]#ss[KMG]
1361 [KNL,ACPI] Mark specific memory as ACPI data.
1362 Region of memory to be used, from ss to ss+nn.
1364 memmap=nn[KMG]$ss[KMG]
1365 [KNL,ACPI] Mark specific memory as reserved.
1366 Region of memory to be used, from ss to ss+nn.
1367 Example: Exclude memory from 0x18690000-0x1869ffff
1368 memmap=64K$0x18690000
1370 memmap=0x10000$0x18690000
1372 memory_corruption_check=0/1 [X86]
1373 Some BIOSes seem to corrupt the first 64k of
1374 memory when doing things like suspend/resume.
1375 Setting this option will scan the memory
1376 looking for corruption. Enabling this will
1377 both detect corruption and prevent the kernel
1378 from using the memory being corrupted.
1379 However, its intended as a diagnostic tool; if
1380 repeatable BIOS-originated corruption always
1381 affects the same memory, you can use memmap=
1382 to prevent the kernel from using that memory.
1384 memory_corruption_check_size=size [X86]
1385 By default it checks for corruption in the low
1386 64k, making this memory unavailable for normal
1387 use. Use this parameter to scan for
1388 corruption in more or less memory.
1390 memory_corruption_check_period=seconds [X86]
1391 By default it checks for corruption every 60
1392 seconds. Use this parameter to check at some
1393 other rate. 0 disables periodic checking.
1395 memtest= [KNL,X86] Enable memtest
1397 default : 0 <disable>
1398 Specifies the number of memtest passes to be
1399 performed. Each pass selects another test
1400 pattern from a given set of patterns. Memtest
1401 fills the memory with this pattern, validates
1402 memory contents and reserves bad memory
1403 regions that are detected.
1405 meye.*= [HW] Set MotionEye Camera parameters
1406 See Documentation/video4linux/meye.txt.
1408 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1409 Multi-Function General Purpose Timers on AMD Geode
1412 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1413 the BIOS has incorrectly applied a workaround. TinyBIOS
1414 version 0.98 is known to be affected, 0.99 fixes the
1415 problem by letting the user disable the workaround.
1419 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1420 physical address is ignored.
1422 mini2440= [ARM,HW,KNL]
1423 Format:[0..2][b][c][t]
1425 MINI2440 configuration specification:
1426 0 - The attached screen is the 3.5" TFT
1427 1 - The attached screen is the 7" TFT
1428 2 - The VGA Shield is attached (1024x768)
1429 Leaving out the screen size parameter will not load
1430 the TFT driver, and the framebuffer will be left
1432 b - Enable backlight. The TFT backlight pin will be
1433 linked to the kernel VESA blanking code and a GPIO
1434 LED. This parameter is not necessary when using the
1436 c - Enable the s3c camera interface.
1437 t - Reserved for enabling touchscreen support. The
1438 touchscreen support is not enabled in the mainstream
1439 kernel as of 2.6.30, a preliminary port can be found
1440 in the "bleeding edge" mini2440 support kernel at
1441 http://repo.or.cz/w/linux-2.6/mini2440.git
1444 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1445 parameter allows control of the logging verbosity for
1446 the additional memory initialisation checks. A value
1447 of 0 disables mminit logging and a level of 4 will
1448 log everything. Information is printed at KERN_DEBUG
1449 so loglevel=8 may also need to be specified.
1452 [MOUSE] Maximum time between finger touching and
1453 leaving touchpad surface for touch to be considered
1454 a tap and be reported as a left button click (for
1455 touchpads working in absolute mode only).
1457 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1458 reporting absolute coordinates, such as tablets
1459 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1460 reporting absolute coordinates, such as tablets
1462 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1463 is similar to kernelcore except it specifies the
1464 amount of memory used for migratable allocations.
1465 If both kernelcore and movablecore is specified,
1466 then kernelcore will be at *least* the specified
1467 value but may be more. If movablecore on its own
1468 is specified, the administrator must be careful
1469 that the amount of memory usable for all allocations
1475 MTD_Partition= [MTD]
1476 Format: <name>,<region-number>,<size>,<offset>
1478 MTD_Region= [MTD] Format:
1479 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1482 See drivers/mtd/cmdlinepart.c.
1484 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1486 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1488 boundary - index of last SLC block on Flex-OneNAND.
1489 The remaining blocks are configured as MLC blocks.
1490 lock - Configure if Flex-OneNAND boundary should be locked.
1491 Once locked, the boundary cannot be changed.
1492 1 indicates lock status, 0 indicates unlock status.
1495 ARM/S3C2412 JIVE boot control
1497 See arch/arm/mach-s3c2412/mach-jive.c
1499 mtouchusb.raw_coordinates=
1500 [HW] Make the MicroTouch USB driver use raw coordinates
1501 ('y', default) or cooked coordinates ('n')
1503 mtrr_chunk_size=nn[KMG] [X86]
1504 used for mtrr cleanup. It is largest continuous chunk
1505 that could hold holes aka. UC entries.
1507 mtrr_gran_size=nn[KMG] [X86]
1508 Used for mtrr cleanup. It is granularity of mtrr block.
1510 Large value could prevent small alignment from
1513 mtrr_spare_reg_nr=n [X86]
1515 Range: 0,7 : spare reg number
1517 Used for mtrr cleanup. It is spare mtrr entries number.
1518 Set to 2 or more if your graphical card needs more.
1520 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1523 See header of drivers/scsi/NCR_D700.c.
1527 ncr53c400= [HW,SCSI]
1529 ncr53c400a= [HW,SCSI]
1531 ncr53c406a= [HW,SCSI]
1533 ncr53c8xx= [HW,SCSI]
1535 netdev= [NET] Network devices parameters
1536 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1537 Note that mem_start is often overloaded to mean
1538 something different and driver-specific.
1539 This usage is only documented in each driver source
1543 [NETFILTER] Enable connection tracking flow accounting
1544 0 to disable accounting
1545 1 to enable accounting
1546 Default value depends on CONFIG_NF_CT_ACCT that is
1547 going to be removed in 2.6.29.
1550 See Documentation/filesystems/nfsroot.txt.
1552 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1553 See Documentation/filesystems/nfsroot.txt.
1555 nfs.callback_tcpport=
1556 [NFS] set the TCP port on which the NFSv4 callback
1557 channel should listen.
1560 [NFS] sets the pathname to the program which is used
1561 to update the NFS client cache entries.
1563 nfs.cache_getent_timeout=
1564 [NFS] sets the timeout after which an attempt to
1565 update a cache entry is deemed to have failed.
1567 nfs.idmap_cache_timeout=
1568 [NFS] set the maximum lifetime for idmapper cache
1572 [NFS] enable 64-bit inode numbers.
1573 If zero, the NFS client will fake up a 32-bit inode
1574 number for the readdir() and stat() syscalls instead
1575 of returning the full 64-bit number.
1576 The default is to return 64-bit inode numbers.
1578 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1579 when a NMI is triggered.
1580 Format: [state][,regs][,debounce][,die]
1582 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1583 Format: [panic,][num]
1585 0 - turn nmi_watchdog off
1586 1 - use the IO-APIC timer for the NMI watchdog
1587 2 - use the local APIC for the NMI watchdog using
1588 a performance counter. Note: This will use one
1589 performance counter and the local APIC's performance
1591 When panic is specified, panic when an NMI watchdog
1593 This is useful when you use a panic=... timeout and
1594 need the box quickly up again.
1595 Instead of 1 and 2 it is possible to use the following
1596 symbolic names: lapic and ioapic
1597 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1599 netpoll.carrier_timeout=
1600 [NET] Specifies amount of time (in seconds) that
1601 netpoll should wait for a carrier. By default netpoll
1604 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1605 emulation library even if a 387 maths coprocessor
1609 [HW] Never suspend the console
1610 Disable suspending of consoles during suspend and
1611 hibernate operations. Once disabled, debugging
1612 messages can reach various consoles while the rest
1613 of the system is being put to sleep (ie, while
1614 debugging driver suspend/resume hooks). This may
1615 not work reliably with all consoles, but is known
1616 to work with serial and VGA consoles.
1618 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1619 caches in the slab allocator. Saves per-node memory,
1620 but will impact performance.
1624 noapic [SMP,APIC] Tells the kernel to not make use of any
1625 IOAPICs that may be present in the system.
1627 nobats [PPC] Do not use BATs for mapping kernel lowmem
1628 on "Classic" PPC cores.
1632 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1634 nodelayacct [KNL] Disable per-task delay accounting
1636 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1638 nodsp [SH] Disable hardware DSP at boot time.
1640 noefi [X86] Disable EFI runtime services support.
1645 On X86-32 available only on PAE configured kernels.
1646 noexec=on: enable non-executable mappings (default)
1647 noexec=off: disable non-executable mappings
1650 This affects only 32-bit executables.
1651 noexec32=on: enable non-executable mappings (default)
1652 read doesn't imply executable mappings
1653 noexec32=off: disable non-executable mappings
1654 read implies executable mappings
1656 nofpu [SH] Disable hardware FPU at boot time.
1658 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1659 register save and restore. The kernel will only save
1660 legacy floating-point registers on task switch.
1662 noxsave [BUGS=X86] Disables x86 extended register state save
1663 and restore using xsave. The kernel will fallback to
1664 enabling legacy floating-point and sse state.
1666 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1667 wfi(ARM) instruction doesn't work correctly and not to
1668 use it. This is also useful when using JTAG debugger.
1670 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1671 instruction doesn't work correctly and not to
1674 no_file_caps Tells the kernel not to honor file capabilities. The
1675 only way then for a file to be executed with privilege
1676 is to be setuid root or executed by root.
1678 nohalt [IA-64] Tells the kernel not to use the power saving
1679 function PAL_HALT_LIGHT when idle. This increases
1680 power-consumption. On the positive side, it reduces
1681 interrupt wake-up latency, which may improve performance
1682 in certain environments such as networked servers or
1685 nohz= [KNL] Boottime enable/disable dynamic ticks
1686 Valid arguments: on, off
1689 noiotrap [SH] Disables trapped I/O port accesses.
1691 noirqdebug [X86-32] Disables the code which attempts to detect and
1692 disable unhandled interrupt sources.
1694 no_timer_check [X86,APIC] Disables the code which tests for
1695 broken timer IRQ sources.
1697 noisapnp [ISAPNP] Disables ISA PnP code.
1699 noinitrd [RAM] Tells the kernel not to load any configured
1702 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1707 nojitter [IA64] Disables jitter checking for ITC timers.
1709 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1711 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1713 noltlbs [PPC] Do not use large page/tlb entries for kernel
1714 lowmem mapping on PPC40x.
1716 nomca [IA-64] Disable machine check abort handling
1718 nomce [X86-32] Machine Check Exception
1720 nomfgpt [X86-32] Disable Multi-Function General Purpose
1721 Timer usage (for AMD Geode machines).
1723 norandmaps Don't use address space randomization. Equivalent to
1724 echo 0 > /proc/sys/kernel/randomize_va_space
1726 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1728 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1729 with UP alternatives
1731 noresidual [PPC] Don't use residual data on PReP machines.
1733 noresume [SWSUSP] Disables resume and restores original swap
1736 no-scroll [VGA] Disables scrollback.
1737 This is required for the Braillex ib80-piezo Braille
1738 reader made by F.H. Papenmeier (Germany).
1742 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1744 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1745 and disable the IO APIC. legacy for "maxcpus=0".
1747 nosoftlockup [KNL] Disable the soft-lockup detector.
1749 noswapaccount [KNL] Disable accounting of swap in memory resource
1750 controller. (See Documentation/cgroups/memory.txt)
1752 nosync [HW,M68K] Disables sync negotiation for all devices.
1754 notsc [BUGS=X86-32] Disable Time Stamp Counter
1756 nousb [USB] Disable the USB subsystem
1760 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1762 nptcg= [IA64] Override max number of concurrent global TLB
1763 purges which is reported from either PAL_VM_SUMMARY or
1766 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1768 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1769 one of ['zone', 'node', 'default'] can be specified
1770 This can be set from sysctl after boot.
1771 See Documentation/sysctl/vm.txt for details.
1773 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1774 See Documentation/debugging-via-ohci1394.txt for more
1777 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1778 Rather than timing out after 20 ms if an EC
1779 command is not properly ACKed, override the length
1780 of the timeout. We have interrupts disabled while
1781 waiting for the ACK, so if this is set too high
1782 interrupts *may* be lost!
1787 oprofile.timer= [HW]
1788 Use timer interrupt instead of performance counters
1790 oprofile.cpu_type= Force an oprofile cpu type
1791 This might be useful if you have an older oprofile
1792 userland or if you want common events.
1793 Format: { arch_perfmon }
1794 arch_perfmon: [X86] Force use of architectural
1795 perfmon on Intel CPUs instead of the
1796 CPU specific event set.
1798 osst= [HW,SCSI] SCSI Tape Driver
1799 Format: <buffer_size>,<write_threshold>
1800 See also Documentation/scsi/st.txt.
1802 panic= [KNL] Kernel behaviour on panic
1805 parkbd.port= [HW] Parallel port number the keyboard adapter is
1806 connected to, default is 0.
1808 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1809 0 for XT, 1 for AT (default is AT).
1812 parport= [HW,PPT] Specify parallel ports. 0 disables.
1813 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1814 Use 'auto' to force the driver to use any
1815 IRQ/DMA settings detected (the default is to
1816 ignore detected IRQ/DMA settings because of
1817 possible conflicts). You can specify the base
1818 address, IRQ, and DMA settings; IRQ and DMA
1819 should be numbers, or 'auto' (for using detected
1820 settings on that particular port), or 'nofifo'
1821 (to avoid using a FIFO even if it is detected).
1822 Parallel ports are assigned in the order they
1823 are specified on the command line, starting
1826 parport_init_mode= [HW,PPT]
1827 Configure VIA parallel port to operate in
1828 a specific mode. This is necessary on Pegasos
1829 computer where firmware has no options for setting
1830 up parallel port mode and sets it to spp.
1831 Currently this function knows 686a and 8231 chips.
1832 Format: [spp|ps2|epp|ecp|ecpepp]
1834 pas2= [HW,OSS] Format:
1835 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1838 See header of drivers/scsi/pas16.c.
1841 Halt all CPUs after the first oops has been printed for
1842 the specified number of seconds. This is to be used if
1843 your oopses keep scrolling off the screen.
1848 See header of drivers/block/paride/pcd.c.
1849 See also Documentation/blockdev/paride.txt.
1851 pci=option[,option...] [PCI] various PCI subsystem options:
1852 earlydump [X86] dump PCI config space before the kernel
1854 off [X86] don't probe for the PCI bus
1855 bios [X86-32] force use of PCI BIOS, don't access
1856 the hardware directly. Use this if your machine
1857 has a non-standard PCI host bridge.
1858 nobios [X86-32] disallow use of PCI BIOS, only direct
1859 hardware access methods are allowed. Use this
1860 if you experience crashes upon bootup and you
1861 suspect they are caused by the BIOS.
1862 conf1 [X86] Force use of PCI Configuration
1864 conf2 [X86] Force use of PCI Configuration
1866 noaer [PCIE] If the PCIEAER kernel config parameter is
1867 enabled, this kernel boot option can be used to
1868 disable the use of PCIE advanced error reporting.
1869 nodomains [PCI] Disable support for multiple PCI
1870 root domains (aka PCI segments, in ACPI-speak).
1871 nommconf [X86] Disable use of MMCONFIG for PCI
1873 check_enable_amd_mmconf [X86] check for and enable
1874 properly configured MMIO access to PCI
1875 config space on AMD family 10h CPU
1876 nomsi [MSI] If the PCI_MSI kernel config parameter is
1877 enabled, this kernel boot option can be used to
1878 disable the use of MSI interrupts system-wide.
1879 noioapicquirk [APIC] Disable all boot interrupt quirks.
1880 Safety option to keep boot IRQs enabled. This
1881 should never be necessary.
1882 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1883 primary IO-APIC for bridges that cannot disable
1884 boot IRQs. This fixes a source of spurious IRQs
1885 when the system masks IRQs.
1886 noioapicreroute [APIC] Disable workaround that uses the
1887 boot IRQ equivalent of an IRQ that connects to
1888 a chipset where boot IRQs cannot be disabled.
1889 The opposite of ioapicreroute.
1890 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1891 routing table. These calls are known to be buggy
1892 on several machines and they hang the machine
1893 when used, but on other computers it's the only
1894 way to get the interrupt routing table. Try
1895 this option if the kernel is unable to allocate
1896 IRQs or discover secondary PCI buses on your
1898 rom [X86] Assign address space to expansion ROMs.
1899 Use with caution as certain devices share
1900 address decoders between ROMs and other
1902 norom [X86] Do not assign address space to
1903 expansion ROMs that do not already have
1904 BIOS assigned address ranges.
1905 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1906 assigned automatically to PCI devices. You can
1907 make the kernel exclude IRQs of your ISA cards
1909 pirqaddr=0xAAAAA [X86] Specify the physical address
1910 of the PIRQ table (normally generated
1911 by the BIOS) if it is outside the
1912 F0000h-100000h range.
1913 lastbus=N [X86] Scan all buses thru bus #N. Can be
1914 useful if the kernel is unable to find your
1915 secondary buses and you want to tell it
1916 explicitly which ones they are.
1917 assign-busses [X86] Always assign all PCI bus
1918 numbers ourselves, overriding
1919 whatever the firmware may have done.
1920 usepirqmask [X86] Honor the possible IRQ mask stored
1921 in the BIOS $PIR table. This is needed on
1922 some systems with broken BIOSes, notably
1923 some HP Pavilion N5400 and Omnibook XE3
1924 notebooks. This will have no effect if ACPI
1925 IRQ routing is enabled.
1926 noacpi [X86] Do not use ACPI for IRQ routing
1927 or for PCI scanning.
1928 use_crs [X86] Use _CRS for PCI resource
1930 routeirq Do IRQ routing for all PCI devices.
1931 This is normally done in pci_enable_device(),
1932 so this option is a temporary workaround
1933 for broken drivers that don't call it.
1934 skip_isa_align [X86] do not align io start addr, so can
1935 handle more pci cards
1936 firmware [ARM] Do not re-enumerate the bus but instead
1937 just use the configuration from the
1938 bootloader. This is currently used on
1939 IXP2000 systems where the bus has to be
1940 configured a certain way for adjunct CPUs.
1941 noearly [X86] Don't do any early type 1 scanning.
1942 This might help on some broken boards which
1943 machine check when some devices' config space
1944 is read. But various workarounds are disabled
1945 and some IOMMU drivers will not work.
1946 bfsort Sort PCI devices into breadth-first order.
1947 This sorting is done to get a device
1948 order compatible with older (<= 2.4) kernels.
1949 nobfsort Don't sort PCI devices into breadth-first order.
1950 cbiosize=nn[KMG] The fixed amount of bus space which is
1951 reserved for the CardBus bridge's IO window.
1952 The default value is 256 bytes.
1953 cbmemsize=nn[KMG] The fixed amount of bus space which is
1954 reserved for the CardBus bridge's memory
1955 window. The default value is 64 megabytes.
1958 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1959 Specifies alignment and device to reassign
1960 aligned memory resources.
1961 If <order of align> is not specified,
1962 PAGE_SIZE is used as alignment.
1963 PCI-PCI bridge can be specified, if resource
1964 windows need to be expanded.
1965 ecrc= Enable/disable PCIe ECRC (transaction layer
1966 end-to-end CRC checking).
1967 bios: Use BIOS/firmware settings. This is the
1972 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1975 force Enable ASPM even on devices that claim not to support it.
1976 WARNING: Forcing ASPM on may cause system lockups.
1978 pcmv= [HW,PCMCIA] BadgePAD 4
1981 See Documentation/blockdev/paride.txt.
1983 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1986 See arch/parisc/kernel/pdc_chassis.c
1988 percpu_alloc= Select which percpu first chunk allocator to use.
1989 Currently supported values are "embed" and "page".
1990 Archs may support subset or none of the selections.
1991 See comments in mm/percpu.c for details on each
1992 allocator. This parameter is primarily for debugging
1993 and performance comparison.
1996 See Documentation/blockdev/paride.txt.
1999 See Documentation/blockdev/paride.txt.
2001 pirq= [SMP,APIC] Manual mp-table setup
2002 See Documentation/x86/i386/IO-APIC.txt.
2004 plip= [PPT,NET] Parallel port network link
2005 Format: { parport<nr> | timid | 0 }
2006 See also Documentation/parport.txt.
2008 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2009 Override pmtimer IOPort with a hex value.
2013 Enable PNP debug messages. This depends on the
2014 CONFIG_PNP_DEBUG_MESSAGES option.
2020 { on | off | curr | res | no-curr | no-res }
2023 [ISAPNP] Exclude IRQs for the autoconfiguration
2026 [ISAPNP] Exclude DMAs for the autoconfiguration
2028 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2029 Ranges are in pairs (I/O port base and size).
2032 [ISAPNP] Exclude memory regions for the
2034 Ranges are in pairs (memory base and size).
2036 ports= [IP_VS_FTP] IPVS ftp helper module
2038 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2040 Format: <port>,<port>....
2042 print-fatal-signals=
2043 [KNL] debug: print fatal signals
2044 print-fatal-signals=1: print segfault info to
2048 printk.time= Show timing data prefixed to each printk message line
2049 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2051 processor.max_cstate= [HW,ACPI]
2052 Limit processor to maximum C-state
2053 max_cstate=9 overrides any DMI blacklist limit.
2055 processor.nocst [HW,ACPI]
2056 Ignore the _CST method to determine C-states,
2057 instead using the legacy FADT method
2059 profile= [KNL] Enable kernel profiling via /proc/profile
2060 Format: [schedule,]<number>
2061 Param: "schedule" - profile schedule points.
2062 Param: <number> - step/bucket size as a power of 2 for
2063 statistical time based profiling.
2064 Param: "sleep" - profile D-state sleeping (millisecs).
2065 Requires CONFIG_SCHEDSTATS
2066 Param: "kvm" - profile VM exits.
2068 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2070 See Documentation/blockdev/ramdisk.txt.
2072 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2073 probe for; one of (bare|imps|exps|lifebook|any).
2074 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2076 psmouse.resetafter= [HW,MOUSE]
2077 Try to reset the device after so many bad packets
2080 [HW,MOUSE] Set desired mouse resolution, in dpi.
2081 psmouse.smartscroll=
2082 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2083 0 = disabled, 1 = enabled (default).
2085 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2087 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2090 See Documentation/blockdev/paride.txt.
2093 [KNL] Number of legacy pty's. Overwrites compiled-in
2096 quiet [KNL] Disable most log messages
2101 See Documentation/md.txt.
2103 ramdisk_blocksize= [RAM]
2104 See Documentation/blockdev/ramdisk.txt.
2106 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2107 See Documentation/blockdev/ramdisk.txt.
2109 rcupdate.blimit= [KNL,BOOT]
2110 Set maximum number of finished RCU callbacks to process
2113 rcupdate.qhimark= [KNL,BOOT]
2114 Set threshold of queued
2115 RCU callbacks over which batch limiting is disabled.
2117 rcupdate.qlowmark= [KNL,BOOT]
2118 Set threshold of queued RCU callbacks below which
2119 batch limiting is re-enabled.
2123 Run specified binary instead of /init from the ramdisk,
2124 used for early userspace startup. See initrd.
2126 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2127 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2128 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2131 [KNL, SMP] Set scheduler's default relax_domain_level.
2132 See Documentation/cgroups/cpusets.txt.
2134 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2136 reservetop= [X86-32]
2138 Reserves a hole at the top of the kernel virtual
2141 reset_devices [KNL] Force drivers to reset the underlying device
2142 during initialization.
2145 Specify the partition device for software suspend
2147 resume_offset= [SWSUSP]
2148 Specify the offset from the beginning of the partition
2149 given by "resume=" at which the swap header is located,
2150 in <PAGE_SIZE> units (needed only for swap files).
2151 See Documentation/power/swsusp-and-swap-files.txt
2153 retain_initrd [RAM] Keep initrd memory after extraction
2155 rhash_entries= [KNL,NET]
2156 Set number of hash buckets for route cache
2158 riscom8= [HW,SERIAL]
2159 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2161 ro [KNL] Mount root device read-only on boot
2163 root= [KNL] Root filesystem
2165 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2166 mount the root filesystem
2168 rootflags= [KNL] Set root filesystem mount option string
2170 rootfstype= [KNL] Set root filesystem type
2172 rootwait [KNL] Wait (indefinitely) for root device to show up.
2173 Useful for devices that are detected asynchronously
2174 (e.g. USB and MMC devices).
2176 root_plug.vendor_id=
2177 [ROOTPLUG] Override the default vendor ID
2179 root_plug.product_id=
2180 [ROOTPLUG] Override the default product ID
2183 [ROOTPLUG] Enable debugging output
2185 rw [KNL] Mount root device read-write on boot
2187 S [KNL] Run init in single mode
2190 See drivers/net/irda/sa1100_ir.c.
2192 sbni= [NET] Granch SBNI12 leased line adapter
2194 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2195 Format: <io>[,<timeout>[,<isapnp>]]
2197 scsi_debug_*= [SCSI]
2198 See drivers/scsi/scsi_debug.c.
2200 scsi_default_dev_flags=
2201 [SCSI] SCSI default device flags
2204 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2205 Format: <vendor>:<model>:<flags>
2206 (flags are integer value)
2208 scsi_logging_level= [SCSI] a bit mask of logging levels
2209 See drivers/scsi/scsi_logging.h for bits. Also
2210 settable via sysctl at dev.scsi.logging_level
2211 (/proc/sys/dev/scsi/logging_level).
2212 There is also a nice 'scsi_logging_level' script in the
2213 S390-tools package, available for download at
2214 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2216 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2217 discovered. async scans them in kernel threads,
2218 allowing boot to proceed. none ignores them, expecting
2219 user space to do the scan.
2221 security= [SECURITY] Choose a security module to enable at boot.
2222 If this boot parameter is not specified, only the first
2223 security module asking for security registration will be
2224 loaded. An invalid security module name will be treated
2225 as if no module has been chosen.
2227 selinux= [SELINUX] Disable or enable SELinux at boot time.
2228 Format: { "0" | "1" }
2229 See security/selinux/Kconfig help text.
2232 Default value is set via kernel config option.
2233 If enabled at boot time, /selinux/disable can be used
2234 later to disable prior to initial policy load.
2236 serialnumber [BUGS=X86-32]
2239 Maximal number of shapers.
2241 show_msr= [x86] show boot-time MSR settings
2242 Format: { <integer> }
2243 Show boot-time (BIOS-initialized) MSR settings.
2244 The parameter means the number of CPUs to show,
2245 for example 1 means boot CPU only.
2248 See header of drivers/scsi/sim710.c.
2255 slub_debug[=options[,slabs]] [MM, SLUB]
2256 Enabling slub_debug allows one to determine the
2257 culprit if slab objects become corrupted. Enabling
2258 slub_debug can create guard zones around objects and
2259 may poison objects when not in use. Also tracks the
2260 last alloc / free. For more information see
2261 Documentation/vm/slub.txt.
2263 slub_max_order= [MM, SLUB]
2264 Determines the maximum allowed order for slabs.
2265 A high setting may cause OOMs due to memory
2266 fragmentation. For more information see
2267 Documentation/vm/slub.txt.
2269 slub_min_objects= [MM, SLUB]
2270 The minimum number of objects per slab. SLUB will
2271 increase the slab order up to slub_max_order to
2272 generate a sufficiently large slab able to contain
2273 the number of objects indicated. The higher the number
2274 of objects the smaller the overhead of tracking slabs
2275 and the less frequently locks need to be acquired.
2276 For more information see Documentation/vm/slub.txt.
2278 slub_min_order= [MM, SLUB]
2279 Determines the mininum page order for slabs. Must be
2280 lower than slub_max_order.
2281 For more information see Documentation/vm/slub.txt.
2283 slub_nomerge [MM, SLUB]
2284 Disable merging of slabs with similar size. May be
2285 necessary if there is some reason to distinguish
2286 allocs to different slabs. Debug options disable
2287 merging on their own.
2288 For more information see Documentation/vm/slub.txt.
2291 Format: <io1>[,<io2>[,...,<io8>]]
2293 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2294 attempt to substitute SMP alternatives once at boot.
2296 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2297 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2298 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2299 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2300 smsc-ircc2.ircc_irq= [HW] IRQ line
2301 smsc-ircc2.ircc_dma= [HW] DMA channel
2302 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2303 0: Toshiba Satellite 1800 (GP data pin select)
2304 1: Fast pin select (default)
2307 snd-ad1816a= [HW,ALSA]
2309 snd-ad1848= [HW,ALSA]
2311 snd-ali5451= [HW,ALSA]
2313 snd-als100= [HW,ALSA]
2315 snd-als4000= [HW,ALSA]
2317 snd-azt2320= [HW,ALSA]
2319 snd-cmi8330= [HW,ALSA]
2321 snd-cmipci= [HW,ALSA]
2323 snd-cs4231= [HW,ALSA]
2325 snd-cs4232= [HW,ALSA]
2327 snd-cs4236= [HW,ALSA]
2329 snd-cs4281= [HW,ALSA]
2331 snd-cs46xx= [HW,ALSA]
2333 snd-dt019x= [HW,ALSA]
2335 snd-dummy= [HW,ALSA]
2337 snd-emu10k1= [HW,ALSA]
2339 snd-ens1370= [HW,ALSA]
2341 snd-ens1371= [HW,ALSA]
2343 snd-es968= [HW,ALSA]
2345 snd-es1688= [HW,ALSA]
2347 snd-es18xx= [HW,ALSA]
2349 snd-es1938= [HW,ALSA]
2351 snd-es1968= [HW,ALSA]
2353 snd-fm801= [HW,ALSA]
2355 snd-gusclassic= [HW,ALSA]
2357 snd-gusextreme= [HW,ALSA]
2359 snd-gusmax= [HW,ALSA]
2363 snd-ice1712= [HW,ALSA]
2365 snd-intel8x0= [HW,ALSA]
2367 snd-interwave= [HW,ALSA]
2372 snd-korg1212= [HW,ALSA]
2374 snd-maestro3= [HW,ALSA]
2376 snd-mpu401= [HW,ALSA]
2378 snd-mtpav= [HW,ALSA]
2380 snd-nm256= [HW,ALSA]
2382 snd-opl3sa2= [HW,ALSA]
2390 snd-opti93x= [HW,ALSA]
2394 snd-rme32= [HW,ALSA]
2396 snd-rme96= [HW,ALSA]
2398 snd-rme9652= [HW,ALSA]
2404 snd-sbawe= [HW,ALSA]
2406 snd-serial= [HW,ALSA]
2408 snd-sgalaxy= [HW,ALSA]
2410 snd-sonicvibes= [HW,ALSA]
2415 snd-sun-cs4231= [HW,ALSA]
2417 snd-trident= [HW,ALSA]
2419 snd-usb-audio= [HW,ALSA,USB]
2421 snd-via82xx= [HW,ALSA]
2423 snd-virmidi= [HW,ALSA]
2425 snd-wavefront= [HW,ALSA]
2427 snd-ymfpci= [HW,ALSA]
2430 [KNL] Should the soft-lockup detector generate panics.
2432 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2433 See Documentation/sonypi.txt
2435 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2436 See Documentation/serial/specialix.txt.
2438 spia_io_base= [HW,MTD]
2444 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2446 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2447 See Documentation/scsi/st.txt.
2450 Enabled the stack tracer on boot up.
2454 Set the STI (builtin display/keyboard on the HP-PARISC
2455 machines) console (graphic card) which should be used
2456 as the initial boot-console.
2457 See also comment in drivers/video/console/sticore.c.
2460 See comment in drivers/video/console/sticore.c.
2463 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2465 sunrpc.min_resvport=
2466 sunrpc.max_resvport=
2468 SunRPC servers often require that client requests
2469 originate from a privileged port (i.e. a port in the
2470 range 0 < portnr < 1024).
2471 An administrator who wishes to reserve some of these
2472 ports for other uses may adjust the range that the
2473 kernel's sunrpc client considers to be privileged
2474 using these two parameters to set the minimum and
2475 maximum port values.
2479 Control how the NFS server code allocates CPUs to
2480 service thread pools. Depending on how many NICs
2481 you have and where their interrupts are bound, this
2482 option will affect which CPUs will do NFS serving.
2483 Note: this parameter cannot be changed while the
2484 NFS server is running.
2486 auto the server chooses an appropriate mode
2487 automatically using heuristics
2488 global a single global pool contains all CPUs
2489 percpu one pool for each CPU
2490 pernode one pool for each NUMA node (equivalent
2491 to global on non-NUMA machines)
2493 sunrpc.tcp_slot_table_entries=
2494 sunrpc.udp_slot_table_entries=
2496 Sets the upper limit on the number of simultaneous
2497 RPC calls that can be sent from the client to a
2498 server. Increasing these values may allow you to
2499 improve throughput, but will also increase the
2500 amount of memory reserved for use by the client.
2502 swiotlb= [IA-64] Number of I/O TLB slabs
2506 sym53c416= [HW,SCSI]
2507 See header of drivers/scsi/sym53c416.c.
2509 sysrq_always_enabled
2511 Ignore sysrq setting - this boot parameter will
2512 neutralize any effect of /proc/sys/kernel/sysrq.
2513 Useful for debugging.
2516 See header of drivers/scsi/t128.c.
2520 test_suspend= [SUSPEND]
2521 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2522 standby suspend) as the system sleep state to briefly
2523 enter during system startup. The system is woken from
2524 this state using a wakeup-capable RTC alarm.
2526 thash_entries= [KNL,NET]
2527 Set number of hash buckets for TCP connection
2529 thermal.act= [HW,ACPI]
2530 -1: disable all active trip points in all thermal zones
2531 <degrees C>: override all lowest active trip points
2533 thermal.crt= [HW,ACPI]
2534 -1: disable all critical trip points in all thermal zones
2535 <degrees C>: override all critical trip points
2537 thermal.nocrt= [HW,ACPI]
2538 Set to disable actions on ACPI thermal zone
2539 critical and hot trip points.
2541 thermal.off= [HW,ACPI]
2542 1: disable ACPI thermal control
2544 thermal.psv= [HW,ACPI]
2545 -1: disable all passive trip points
2546 <degrees C>: override all passive trip points to this
2549 thermal.tzp= [HW,ACPI]
2550 Specify global default ACPI thermal zone polling rate
2551 <deci-seconds>: poll all this frequency
2552 0: no polling (default)
2555 See comment before function dc390_setup() in
2556 drivers/scsi/tmscsim.c.
2560 Specify if the kernel should make use of the cpu
2561 topology informations if the hardware supports these.
2562 The scheduler will make use of these informations and
2563 e.g. base its process migration decisions on it.
2568 trace_buf_size=nn[KMG]
2569 [FTRACE] will set tracing buffer size.
2571 trace_event=[event-list]
2572 [FTRACE] Set and start specified trace events in order
2573 to facilitate early boot debugging.
2574 See also Documentation/trace/events.txt
2576 trix= [HW,OSS] MediaTrix AudioTrix Pro
2578 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2580 tsc= Disable clocksource-must-verify flag for TSC.
2582 [x86] reliable: mark tsc clocksource as reliable, this
2583 disables clocksource verification at runtime.
2584 Used to enable high-resolution timer mode on older
2585 hardware, and in virtualized environment.
2587 turbografx.map[2|3]= [HW,JOY]
2588 TurboGraFX parallel port interface
2590 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2591 See also Documentation/input/joystick-parport.txt
2593 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2594 See header of drivers/scsi/u14-34f.c.
2603 [USB] Ignore overcurrent events (default N).
2604 Some badly-designed motherboards generate lots of
2605 bogus events, for ports that aren't wired to
2606 anything. Set this parameter to avoid log spamming.
2607 Note that genuine overcurrent events won't be
2612 Set unknown_nmi_panic=1 early on boot.
2614 usbcore.autosuspend=
2615 [USB] The autosuspend time delay (in seconds) used
2616 for newly-detected USB devices (default 2). This
2617 is the time required before an idle device will be
2618 autosuspended. Devices for which the delay is set
2619 to a negative value won't be autosuspended at all.
2621 usbcore.usbfs_snoop=
2622 [USB] Set to log all usbfs traffic (default 0 = off).
2624 usbcore.blinkenlights=
2625 [USB] Set to cycle leds on hubs (default 0 = off).
2627 usbcore.old_scheme_first=
2628 [USB] Start with the old device initialization
2629 scheme (default 0 = off).
2631 usbcore.use_both_schemes=
2632 [USB] Try the other device initialization scheme
2633 if the first one fails (default 1 = enabled).
2635 usbcore.initial_descriptor_timeout=
2636 [USB] Specifies timeout for the initial 64-byte
2637 USB_REQ_GET_DESCRIPTOR request in milliseconds
2638 (default 5000 = 5.0 seconds).
2641 [USBHID] The interval which mice are to be polled at.
2643 usb-storage.delay_use=
2644 [UMS] The delay in seconds before a new device is
2645 scanned for Logical Units (default 5).
2648 [UMS] A list of quirks entries to supplement or
2649 override the built-in unusual_devs list. List
2650 entries are separated by commas. Each entry has
2651 the form VID:PID:Flags where VID and PID are Vendor
2652 and Product ID values (4-digit hex numbers) and
2653 Flags is a set of characters, each corresponding
2654 to a common usb-storage quirk flag as follows:
2655 a = SANE_SENSE (collect more than 18 bytes
2657 c = FIX_CAPACITY (decrease the reported
2658 device capacity by one sector);
2659 h = CAPACITY_HEURISTICS (decrease the
2660 reported device capacity by one
2661 sector if the number is odd);
2662 i = IGNORE_DEVICE (don't bind to this
2664 l = NOT_LOCKABLE (don't try to lock and
2665 unlock ejectable media);
2666 m = MAX_SECTORS_64 (don't transfer more
2667 than 64 sectors = 32 KB at a time);
2668 o = CAPACITY_OK (accept the capacity
2669 reported by the device);
2670 r = IGNORE_RESIDUE (the device reports
2671 bogus residue values);
2672 s = SINGLE_LUN (the device has only one
2674 w = NO_WP_DETECT (don't test whether the
2675 medium is write-protected).
2676 Example: quirks=0419:aaf5:rl,0421:0433:rc
2679 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2680 vdso=1: enable VDSO (default)
2681 vdso=0: disable VDSO mapping
2684 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2685 vdso32=1: enable 32-bit VDSO (default)
2686 vdso32=0: disable 32-bit VDSO mapping
2689 vector=percpu: enable percpu vector domain
2691 video= [FB] Frame buffer configuration
2692 See Documentation/fb/modedb.txt.
2694 vga= [BOOT,X86-32] Select a particular video mode
2695 See Documentation/x86/boot.txt and
2696 Documentation/svga.txt.
2697 Use vga=ask for menu.
2698 This is actually a boot loader parameter; the value is
2699 passed to the kernel using a special protocol.
2701 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2702 size of <nn>. This can be used to increase the
2703 minimum size (128MB on x86). It can also be used to
2704 decrease the size and leave more room for directly
2707 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2710 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2713 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2716 vt.default_blu= [VT]
2717 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2718 Change the default blue palette of the console.
2719 This is a 16-member array composed of values
2722 vt.default_grn= [VT]
2723 Format: <green0>,<green1>,<green2>,...,<green15>
2724 Change the default green palette of the console.
2725 This is a 16-member array composed of values
2728 vt.default_red= [VT]
2729 Format: <red0>,<red1>,<red2>,...,<red15>
2730 Change the default red palette of the console.
2731 This is a 16-member array composed of values
2737 Set system-wide default UTF-8 mode for all tty's.
2738 Default is 1, i.e. UTF-8 mode is enabled for all
2739 newly opened terminals.
2741 waveartist= [HW,OSS]
2742 Format: <io>,<irq>,<dma>,<dma2>
2745 See header of drivers/scsi/wd33c93.c.
2748 See header of drivers/scsi/wd7000.c.
2751 See Documentation/watchdog/wdt.txt.
2753 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2754 default x2apic cluster mode on platforms
2757 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2758 xd_geo= See header of drivers/block/xd.c.
2760 xirc2ps_cs= [NET,PCMCIA]
2762 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2764 ______________________________________________________________________
2768 Add documentation for ALSA options.
2769 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob