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 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
48 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
49 EFI EFI Partitioning (GPT) is enabled
50 EIDE EIDE/ATAPI support is enabled.
51 FB The frame buffer device is enabled.
52 GCOV GCOV profiling is enabled.
53 HW Appropriate hardware is enabled.
54 IA-64 IA-64 architecture is enabled.
55 IMA Integrity measurement architecture is enabled.
56 IOSCHED More than one I/O scheduler is enabled.
57 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
58 IPV6 IPv6 support is enabled.
59 ISAPNP ISA PnP code is enabled.
60 ISDN Appropriate ISDN support is enabled.
61 JOY Appropriate joystick support is enabled.
62 KGDB Kernel debugger support is enabled.
63 KVM Kernel Virtual Machine support is enabled.
64 LIBATA Libata driver is enabled
65 LP Printer support is enabled.
66 LOOP Loopback device support is enabled.
67 M68k M68k architecture is enabled.
68 These options have more detailed description inside of
69 Documentation/m68k/kernel-options.txt.
70 MCA MCA bus support is enabled.
71 MDA MDA console support is enabled.
72 MOUSE Appropriate mouse support is enabled.
73 MSI Message Signaled Interrupts (PCI).
74 MTD MTD (Memory Technology Device) support is enabled.
75 NET Appropriate network support is enabled.
76 NUMA NUMA support is enabled.
77 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
79 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
81 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
83 PCIE PCI Express support is enabled.
84 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers have their options described inside
93 the Documentation/scsi/ sub-directory.
94 SECURITY Different security models are enabled.
95 SELINUX SELinux support is enabled.
96 APPARMOR AppArmor support is enabled.
97 SERIAL Serial support is enabled.
98 SH SuperH architecture is enabled.
99 SMP The kernel is an SMP kernel.
100 SPARC Sparc architecture is enabled.
101 SWSUSP Software suspend (hibernation) is enabled.
102 SUSPEND System suspend states are enabled.
103 FTRACE Function tracing enabled.
104 TPM TPM drivers are enabled.
105 TS Appropriate touchscreen support is enabled.
106 UMS USB Mass Storage support is enabled.
107 USB USB support is enabled.
108 USBHID USB Human Interface Device support is enabled.
109 V4L Video For Linux support is enabled.
110 VGA The VGA console has been enabled.
111 VT Virtual terminal support is enabled.
112 WDT Watchdog support is enabled.
113 XT IBM PC/XT MFM hard disk support is enabled.
114 X86-32 X86-32, aka i386 architecture is enabled.
115 X86-64 X86-64 architecture is enabled.
116 More X86-64 boot options can be found in
117 Documentation/x86/x86_64/boot-options.txt .
118 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
119 XEN Xen support is enabled
121 In addition, the following text indicates that the option:
123 BUGS= Relates to possible processor bugs on the said processor.
124 KNL Is a kernel start-up parameter.
125 BOOT Is a boot loader parameter.
127 Parameters denoted with BOOT are actually interpreted by the boot
128 loader, and have no meaning to the kernel directly.
129 Do not modify the syntax of boot loader parameters without extreme
130 need or coordination with <Documentation/x86/boot.txt>.
132 There are also arch-specific kernel-parameters not documented here.
133 See for example <Documentation/x86/x86_64/boot-options.txt>.
135 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
136 a trailing = on the name of any parameter states that that parameter will
137 be entered as an environment variable, whereas its absence indicates that
138 it will appear as a kernel argument readable via /proc/cmdline by programs
139 running once the system is up.
141 The number of kernel parameters is not limited, but the length of the
142 complete command line (parameters including spaces etc.) is limited to
143 a fixed number of characters. This limit depends on the architecture
144 and is between 256 and 4096 characters. It is defined in the file
145 ./include/asm/setup.h as COMMAND_LINE_SIZE.
147 Finally, the [KMG] suffix is commonly described after a number of kernel
148 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
149 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
150 bytes respectively. Such letter suffixes can also be entirely omitted.
154 Advanced Configuration and Power Interface
155 Format: { force | off | strict | noirq | rsdt }
156 force -- enable ACPI if default was off
157 off -- disable ACPI if default was on
158 noirq -- do not use ACPI for IRQ routing
159 strict -- Be less tolerant of platforms that are not
160 strictly ACPI specification compliant.
161 rsdt -- prefer RSDT over (default) XSDT
162 copy_dsdt -- copy DSDT to memory
164 acpi_apic_instance= [ACPI, IOAPIC]
166 2: use 2nd APIC table, if available
167 1,0: use 1st APIC table
170 acpi_backlight= [HW,ACPI]
171 acpi_backlight=vendor
173 If set to vendor, prefer vendor specific driver
174 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
175 of the ACPI video.ko driver.
177 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
178 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
180 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
181 debug output. Bits in debug_layer correspond to a
182 _COMPONENT in an ACPI source file, e.g.,
183 #define _COMPONENT ACPI_PCI_COMPONENT
184 Bits in debug_level correspond to a level in
185 ACPI_DEBUG_PRINT statements, e.g.,
186 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
187 The debug_level mask defaults to "info". See
188 Documentation/acpi/debug.txt for more information about
189 debug layers and levels.
191 Enable processor driver info messages:
192 acpi.debug_layer=0x20000000
193 Enable PCI/PCI interrupt routing info messages:
194 acpi.debug_layer=0x400000
195 Enable AML "Debug" output, i.e., stores to the Debug
196 object while interpreting AML:
197 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
198 Enable all messages related to ACPI hardware:
199 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
201 Some values produce so much output that the system is
202 unusable. The "log_buf_len" parameter may be useful
203 if you need to capture more output.
205 acpi_irq_balance [HW,ACPI]
206 ACPI will balance active IRQs
209 acpi_irq_nobalance [HW,ACPI]
210 ACPI will not move active IRQs (default)
213 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
214 Format: <irq>,<irq>...
216 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
218 Format: <irq>,<irq>...
220 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
222 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
223 Format: To spoof as Windows 98: ="Microsoft Windows"
225 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
226 acpi_osi="string1" # add string1 -- only one string
227 acpi_osi="!string2" # remove built-in string2
228 acpi_osi= # disable all strings
231 Override the pmtimer bug detection: force the kernel
232 to assume that this machine's pmtimer latches its value
233 and always returns good values.
235 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
236 Format: { level | edge | high | low }
238 acpi_serialize [HW,ACPI] force serialization of AML methods
240 acpi_skip_timer_override [HW,ACPI]
241 Recognize and ignore IRQ0/pin2 Interrupt Override.
242 For broken nForce2 BIOS resulting in XT-PIC timer.
244 acpi_sleep= [HW,ACPI] Sleep options
245 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
246 old_ordering, nonvs, sci_force_enable }
247 See Documentation/power/video.txt for information on
249 s3_beep is for debugging; it makes the PC's speaker beep
250 as soon as the kernel's real-mode entry point is called.
251 s4_nohwsig prevents ACPI hardware signature from being
252 used during resume from hibernation.
253 old_ordering causes the ACPI 1.0 ordering of the _PTS
254 control method, with respect to putting devices into
255 low power states, to be enforced (the ACPI 2.0 ordering
256 of _PTS is used by default).
257 nonvs prevents the kernel from saving/restoring the
258 ACPI NVS memory during suspend/hibernation and resume.
259 sci_force_enable causes the kernel to set SCI_EN directly
260 on resume from S1/S3 (which is against the ACPI spec,
261 but some broken systems don't work without it).
263 acpi_use_timer_override [HW,ACPI]
264 Use timer override. For some broken Nvidia NF5 boards
265 that require a timer override, but don't have HPET
267 acpi_enforce_resources= [ACPI]
268 { strict | lax | no }
269 Check for resource conflicts between native drivers
270 and ACPI OperationRegions (SystemIO and SystemMemory
271 only). IO ports and memory declared in ACPI might be
272 used by the ACPI subsystem in arbitrary AML code and
273 can interfere with legacy drivers.
274 strict (default): access to resources claimed by ACPI
275 is denied; legacy drivers trying to access reserved
276 resources will fail to bind to device using them.
277 lax: access to resources claimed by ACPI is allowed;
278 legacy drivers trying to access reserved resources
279 will bind successfully but a warning message is logged.
280 no: ACPI OperationRegions are not marked as reserved,
281 no further checks are performed.
283 add_efi_memmap [EFI; X86] Include EFI memory map in
284 kernel's map of available physical RAM.
287 { off | try_unsupported }
288 off: disable AGP support
289 try_unsupported: try to drive unsupported chipsets
290 (may crash computer or cause data corruption)
293 See Documentation/sound/alsa/alsa-parameters.txt
296 Allow the default userspace alignment fault handler
297 behaviour to be specified. Bit 0 enables warnings,
298 bit 1 enables fixups, and bit 2 sends a segfault.
300 amd_iommu= [HW,X86-84]
301 Pass parameters to the AMD IOMMU driver in the system.
303 fullflush - enable flushing of IO/TLB entries when
304 they are unmapped. Otherwise they are
305 flushed before they will be reused, which
307 off - do not initialize any AMD IOMMU found in
310 amijoy.map= [HW,JOY] Amiga joystick support
311 Map of devices attached to JOY0DAT and JOY1DAT
313 See also Documentation/kernel/input/joystick.txt
315 analog.map= [HW,JOY] Analog joystick and gamepad support
316 Specifies type or capabilities of an analog joystick
317 connected to one of 16 gameports
318 Format: <type1>,<type2>,..<type16>
321 Power management functions (SPARCstation-4/5 + deriv.)
323 Disable APC CPU standby support. SPARCstation-Fox does
324 not play well with APC CPU idle - disable it if you have
325 APC and your system crashes randomly.
327 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
328 Change the output verbosity whilst booting
329 Format: { quiet (default) | verbose | debug }
330 Change the amount of debugging information output
331 when initialising the APIC and IO-APIC components.
334 See Documentation/networking/ipv6.txt.
336 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
337 Limit apic dumping. The parameter defines the maximal
338 number of local apics being dumped. Also it is possible
339 to set it to "all" by meaning -- no limit here.
340 Format: { 1 (default) | 2 | ... | all }.
341 The parameter valid if only apic=debug or
342 apic=verbose is specified.
343 Example: apic=debug show_lapic=all
345 apm= [APM] Advanced Power Management
346 See header of arch/x86/kernel/apm_32.c.
348 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
349 Format: <io>,<irq>,<nodeID>
353 atarimouse= [HW,MOUSE] Atari Mouse
355 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
356 EzKey and similar keyboards
358 atkbd.reset= [HW] Reset keyboard during initialization
360 atkbd.set= [HW] Select keyboard code set
361 Format: <int> (2 = AT (default), 3 = PS/2)
363 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
366 atkbd.softraw= [HW] Choose between synthetic and real raw mode
367 Format: <bool> (0 = real, 1 = synthetic (default))
369 atkbd.softrepeat= [HW]
370 Use software keyboard repeat
374 baycom_epp= [HW,AX25]
377 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
379 See header of drivers/net/hamradio/baycom_par.c.
381 baycom_ser_fdx= [HW,AX25]
382 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
383 Format: <io>,<irq>,<mode>[,<baud>]
384 See header of drivers/net/hamradio/baycom_ser_fdx.c.
386 baycom_ser_hdx= [HW,AX25]
387 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
388 Format: <io>,<irq>,<mode>
389 See header of drivers/net/hamradio/baycom_ser_hdx.c.
391 boot_delay= Milliseconds to delay each printk during boot.
392 Values larger than 10 seconds (10000) are changed to
396 bootmem_debug [KNL] Enable bootmem allocator debug messages.
398 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
399 bttv.radio= Most important insmod options are available as
401 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
402 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
404 bulk_remove=off [PPC] This parameter disables the use of the pSeries
405 firmware feature for flushing multiple hpte entries
408 c101= [NET] Moxa C101 synchronous serial card
410 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
411 Sometimes CPU hardware bugs make them report the cache
412 size incorrectly. The kernel will attempt work arounds
413 to fix known problems, but for some CPUs it is not
414 possible to determine what the correct size should be.
415 This option provides an override for these situations.
418 [SECURITY] Disable capabilities. This would normally
419 be used only if an alternative security model is to be
420 configured. Potentially dangerous and should only be
421 used if you are entirely sure of the consequences.
423 ccw_timeout_log [S390]
424 See Documentation/s390/CommonIO for details.
426 cgroup_disable= [KNL] Disable a particular controller
427 Format: {name of the controller(s) to disable}
428 {Currently supported controllers - "memory"}
430 checkreqprot [SELINUX] Set initial checkreqprot flag value.
431 Format: { "0" | "1" }
432 See security/selinux/Kconfig help text.
433 0 -- check protection applied by kernel (includes
434 any implied execute protection).
435 1 -- check protection requested by application.
436 Default value is set via a kernel config option.
437 Value can be changed at runtime via
438 /selinux/checkreqprot.
441 See Documentation/s390/CommonIO for details.
443 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
445 Forces specified clocksource (if available) to be used
446 when calculating gettimeofday(). If specified
447 clocksource is not available, it defaults to PIT.
448 Format: { pit | tsc | cyclone | pmtmr }
450 clocksource= Override the default clocksource
452 Override the default clocksource and use the clocksource
453 with the name specified.
454 Some clocksource names to choose from, depending on
456 [all] jiffies (this is the base, fallback clocksource)
458 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
459 pxa_timer,timer3,32k_counter,timer0_1
461 [X86-32] pit,hpet,tsc;
462 scx200_hrt on Geode; cyclone on IBM x440
470 clearcpuid=BITNUM [X86]
471 Disable CPUID feature X for the kernel. See
472 arch/x86/include/asm/cpufeature.h for the valid bit
473 numbers. Note the Linux specific bits are not necessarily
474 stable over kernel options, but the vendor specific
476 Also note that user programs calling CPUID directly
477 or using the feature without checking anything
478 will still see it. This just prevents it from
479 being used by the kernel or shown in /proc/cpuinfo.
480 Also note the kernel might malfunction if you disable
483 cmo_free_hint= [PPC] Format: { yes | no }
484 Specify whether pages are marked as being inactive
485 when they are freed. This is used in CMO environments
486 to determine OS memory pressure for page stealing by
490 code_bytes [X86] How many bytes of object code to print
495 com20020= [HW,NET] ARCnet - COM20020 chipset
497 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
499 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
503 ARCnet - COM90xx chipset (memory-mapped buffers)
504 Format: <io>[,<irq>[,<memstart>]]
506 condev= [HW,S390] console device
509 console= [KNL] Output console device and options.
511 tty<n> Use the virtual console device <n>.
515 Use the specified serial port. The options are of
516 the form "bbbbpnf", where "bbbb" is the baud rate,
517 "p" is parity ("n", "o", or "e"), "n" is number of
518 bits, and "f" is flow control ("r" for RTS or
519 omit it). Default is "9600n8".
521 See Documentation/serial-console.txt for more
523 Documentation/networking/netconsole.txt for an
526 uart[8250],io,<addr>[,options]
527 uart[8250],mmio,<addr>[,options]
528 Start an early, polled-mode console on the 8250/16550
529 UART at the specified I/O port or MMIO address,
530 switching to the matching ttyS device later. The
531 options are the same as for ttyS, above.
533 If the device connected to the port is not a TTY but a braille
534 device, prepend "brl," before the device type, for instance
536 For now, only VisioBraille is supported.
538 consoleblank= [KNL] The console blank (screen saver) timeout in
539 seconds. Defaults to 10*60 = 10mins. A value of 0
540 disables the blank timer.
543 [KNL] Change the default value for
544 /proc/<pid>/coredump_filter.
545 See also Documentation/filesystems/proc.txt.
547 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
549 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
551 crashkernel=size[KMG][@offset[KMG]]
552 [KNL] Using kexec, Linux can switch to a 'crash kernel'
553 upon panic. This parameter reserves the physical
554 memory region [offset, offset + size] for that kernel
555 image. If '@offset' is omitted, then a suitable offset
556 is selected automatically. Check
557 Documentation/kdump/kdump.txt for further details.
559 crashkernel=range1:size1[,range2:size2,...][@offset]
560 [KNL] Same as above, but depends on the memory
561 in the running system. The syntax of range is
562 start-[end] where start and end are both
563 a memory unit (amount[KMG]). See also
564 Documentation/kdump/kdump.txt for an example.
569 cs89x0_media= [HW,NET]
570 Format: { rj45 | aui | bnc }
573 See header of drivers/s390/block/dasd_devmap.c.
575 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
576 (one device per port)
577 Format: <port#>,<type>
578 See also Documentation/input/joystick-parport.txt
580 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
581 time. See Documentation/dynamic-debug-howto.txt for
584 debug [KNL] Enable kernel debugging (events log level).
587 [KNL] verbose self-tests
589 Print debugging info while doing the locking API
591 We default to 0 (no extra messages), setting it to
592 1 will print _a lot_ more information - normally
593 only useful to kernel developers.
595 debug_objects [KNL] Enable object debugging
598 [KNL] Disable object debugging
600 debugpat [X86] Enable PAT debugging
602 decnet.addr= [HW,NET]
603 Format: <area>[,<node>]
604 See also Documentation/networking/decnet.txt.
607 [same as hugepagesz=] The size of the default
608 HugeTLB page size. This is the size represented by
609 the legacy /proc/ hugepages APIs, used for SHM, and
610 default size when mounting hugetlbfs filesystems.
611 Defaults to the default architecture's huge page size
615 Set number of hash buckets for dentry cache.
618 IO parameters + enable/disable command.
620 digiepca= [HW,SERIAL]
621 See drivers/char/README.epca and
622 Documentation/serial/digiepca.txt.
625 See Documentation/networking/ipv6.txt.
627 disable_ddw [PPC/PSERIES]
628 Disable Dynamic DMA Window support. Use this if
629 to workaround buggy firmware.
632 See Documentation/networking/ipv6.txt.
634 disable_mtrr_cleanup [X86]
635 The kernel tries to adjust MTRR layout from continuous
636 to discrete, to make X server driver able to add WB
637 entry later. This parameter disables that.
639 disable_mtrr_trim [X86, Intel and AMD only]
640 By default the kernel will trim any uncacheable
641 memory out of your available memory pool based on
642 MTRR settings. This parameter disables that behavior,
643 possibly causing your machine to run very slowly.
645 disable_timer_pin_1 [X86]
646 Disable PIN 1 of APIC timer
647 Can be useful to work around chipset bugs.
649 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
650 this option disables the debugging code at boot.
652 dma_debug_entries=<number>
653 This option allows to tune the number of preallocated
654 entries for DMA-API debugging code. One entry is
655 required per DMA-API allocation. Use this if the
656 DMA-API debugging code disables itself because the
657 architectural default is too low.
659 dma_debug_driver=<driver_name>
660 With this option the DMA-API debugging driver
661 filter feature can be enabled at boot time. Just
662 pass the driver to filter for as the parameter.
663 The filter can be disabled or changed to another
664 driver later using sysfs.
668 earlycon= [KNL] Output early console device and options.
669 uart[8250],io,<addr>[,options]
670 uart[8250],mmio,<addr>[,options]
671 uart[8250],mmio32,<addr>[,options]
672 Start an early, polled-mode console on the 8250/16550
673 UART at the specified I/O port or MMIO address.
674 MMIO inter-register address stride is either 8bit (mmio)
676 The options are the same as for ttyS, above.
678 earlyprintk= [X86,SH,BLACKFIN]
680 earlyprintk=serial[,ttySn[,baudrate]]
681 earlyprintk=ttySn[,baudrate]
682 earlyprintk=dbgp[debugController#]
684 Append ",keep" to not disable it when the real console
687 Only vga or serial or usb debug port at a time.
689 Currently only ttyS0 and ttyS1 are supported.
691 Interaction with the standard serial driver is not
694 The VGA output is eventually overwritten by the real
697 ekgdboc= [X86,KGDB] Allow early kernel console debugging
700 This is designed to be used in conjunction with
701 the boot argument: earlyprintk=vga
704 Format: {"off" | "on" | "skip[mbr]"}
706 eisa_irq_edge= [PARISC,HW]
707 See header of drivers/parisc/eisa.c.
710 See comment before function elanfreq_setup() in
711 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
714 Format: {"cfq" | "deadline" | "noop"}
715 See Documentation/block/as-iosched.txt and
716 Documentation/block/deadline-iosched.txt for details.
718 elfcorehdr= [IA64,PPC,SH,X86]
719 Specifies physical address of start of kernel core
720 image elf header. Generally kexec loader will
721 pass this option to capture kernel.
722 See Documentation/kdump/kdump.txt for details.
724 enable_mtrr_cleanup [X86]
725 The kernel tries to adjust MTRR layout from continuous
726 to discrete, to make X server driver able to add WB
727 entry later. This parameter enables that.
729 enable_timer_pin_1 [X86]
730 Enable PIN 1 of APIC timer
731 Can be useful to work around chipset bugs
732 (in particular on some ATI chipsets).
733 The kernel tries to set a reasonable default.
735 enforcing [SELINUX] Set initial enforcing status.
737 See security/selinux/Kconfig help text.
738 0 -- permissive (log only, no denials).
739 1 -- enforcing (deny and log).
741 Value can be changed at runtime via /selinux/enforce.
744 Disable Error Record Serialization Table (ERST)
747 ether= [HW,NET] Ethernet cards parameters
748 This option is obsoleted by the "netdev=" option, which
749 has equivalent usage. See its documentation for details.
753 fail_make_request=[KNL]
754 General fault injection mechanism.
755 Format: <interval>,<probability>,<space>,<times>
756 See also /Documentation/fault-injection/.
759 See Documentation/blockdev/floppy.txt.
761 force_pal_cache_flush
762 [IA-64] Avoid check_sal_cache_flush which may hang on
763 buggy SAL_CACHE_FLUSH implementations. Using this
764 parameter will force ia64_sal_cache_flush to call
765 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
768 [FTRACE] will set and start the specified tracer
769 as early as possible in order to facilitate early
772 ftrace_dump_on_oops[=orig_cpu]
773 [FTRACE] will dump the trace buffers on oops.
774 If no parameter is passed, ftrace will dump
775 buffers of all CPUs, but if you pass orig_cpu, it will
776 dump only the buffer of the CPU that triggered the
779 ftrace_filter=[function-list]
780 [FTRACE] Limit the functions traced by the function
781 tracer at boot up. function-list is a comma separated
782 list of functions. This list can be changed at run
783 time by the set_ftrace_filter file in the debugfs
786 ftrace_notrace=[function-list]
787 [FTRACE] Do not trace the functions specified in
788 function-list. This list can be changed at run time
789 by the set_ftrace_notrace file in the debugfs
792 ftrace_graph_filter=[function-list]
793 [FTRACE] Limit the top level callers functions traced
794 by the function graph tracer at boot up.
795 function-list is a comma separated list of functions
796 that can be changed at run time by the
797 set_graph_function file in the debugfs tracing directory.
800 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
801 support via parallel port (up to 5 devices per port)
802 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
803 See also Documentation/input/joystick-parport.txt
807 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
811 gcov_persist= [GCOV] When non-zero (default), profiling data for
812 kernel modules is saved and remains accessible via
813 debugfs, even when the module is unloaded/reloaded.
814 When zero, profiling data is discarded and associated
815 debugfs files are removed at module unload time.
817 gpt [EFI] Forces disk with valid GPT signature but
818 invalid Protective MBR to be treated as GPT.
820 hashdist= [KNL,NUMA] Large hashes allocated during boot
821 are distributed across NUMA nodes. Defaults on
822 for 64bit NUMA, off otherwise.
823 Format: 0 | 1 (for off | on)
825 hcl= [IA-64] SGI's Hardware Graph compatibility layer
827 hd= [EIDE] (E)IDE hard drive subsystem geometry
828 Format: <cyl>,<head>,<sect>
831 Disable Hardware Error Source Table (HEST) support;
832 corresponding firmware-first mode error processing
833 logic will be disabled.
835 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
836 size of <nn>. This works even on boxes that have no
837 highmem otherwise. This also works to reduce highmem
838 size on bigger boxes.
840 highres= [KNL] Enable/disable high resolution timer mode.
841 Valid parameters: "on", "off"
845 See Documentation/isdn/README.HiSax.
849 hpet= [X86-32,HPET] option to control HPET usage
850 Format: { enable (default) | disable | force |
852 disable: disable HPET and use PIT instead
853 force: allow force enabled of undocumented chips (ICH4,
855 verbose: show contents of HPET registers during setup
857 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
858 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
859 On x86-64 and powerpc, this option can be specified
860 multiple times interleaved with hugepages= to reserve
861 huge pages of different sizes. Valid pages sizes on
862 x86-64 are 2M (when the CPU supports "pse") and 1G
863 (when the CPU supports the "pdpe1gb" cpuinfo flag)
864 Note that 1GB pages can only be allocated at boot time
865 using hugepages= and not freed afterwards.
867 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
868 terminal devices. Valid values: 0..8
869 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
870 If specified, z/VM IUCV HVC accepts connections
871 from listed z/VM user IDs only.
874 Do not unregister boot console at start. This is only
875 useful for debugging when something happens in the window
876 between unregistering the boot console and initializing
879 i2c_bus= [HW] Override the default board specific I2C bus speed
880 or register an additional I2C bus that is not
881 registered from board initialization code.
885 i8042.debug [HW] Toggle i8042 debug mode
886 i8042.direct [HW] Put keyboard port into non-translated mode
887 i8042.dumbkbd [HW] Pretend that controller can only read data from
888 keyboard and cannot control its state
889 (Don't attempt to blink the leds)
890 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
891 i8042.nokbd [HW] Don't check/create keyboard port
892 i8042.noloop [HW] Disable the AUX Loopback command while probing
894 i8042.nomux [HW] Don't check presence of an active multiplexing
896 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
898 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
899 i8042.reset [HW] Reset the controller during init and cleanup
900 i8042.unlock [HW] Unlock (ignore) the keylock
904 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
905 indicates that the driver is running on unsupported
907 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
908 does not match list of supported models.
910 [HW] Report power status in /proc/i8k
911 (disabled by default)
912 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
916 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
918 ide-core.nodma= [HW] (E)IDE subsystem
919 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
920 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
921 .cdrom .chs .ignore_cable are additional options
922 See Documentation/ide/ide.txt.
924 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
925 Claim all unknown PCI IDE storage controllers.
928 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
929 Poll forces a polling idle loop that can slightly
930 improve the performance of waking up a idle CPU, but
931 will use a lot of power and make the system run hot.
933 idle=mwait: On systems which support MONITOR/MWAIT but
934 the kernel chose to not use it because it doesn't save
935 as much power as a normal idle loop, use the
936 MONITOR/MWAIT idle loop anyways. Performance should be
937 the same as idle=poll.
938 idle=halt: Halt is forced to be used for CPU idle.
939 In such case C2/C3 won't be used again.
940 idle=nomwait: Disable mwait for CPU C-states
942 ignore_loglevel [KNL]
943 Ignore loglevel setting - this will print /all/
944 kernel messages to the console. Useful for debugging.
947 Set number of hash buckets for inode cache.
950 Format: { "0" | "1" }
951 0 -- integrity auditing messages. (Default)
952 1 -- enable informational integrity auditing messages.
955 Format: { "sha1" | "md5" }
959 Load a policy which meets the needs of the Trusted
960 Computing Base. This means IMA will measure all
961 programs exec'd, files mmap'd for exec, and all files
962 opened for read by uid=0.
966 Run specified binary instead of /sbin/init as init
969 initcall_debug [KNL] Trace initcalls as they are executed. Useful
970 for working out where the kernel is dying during
973 initrd= [BOOT] Specify the location of the initial ramdisk
975 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
978 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
980 Enable intel iommu driver.
982 Disable intel iommu driver.
983 igfx_off [Default Off]
984 By default, gfx is mapped as normal device. If a gfx
985 device has a dedicated DMAR unit, the DMAR unit is
986 bypassed by not enabling DMAR with this option. In
987 this case, gfx device will use physical address for
990 With this option iommu will not optimize to look
991 for io virtual address below 32 bit forcing dual
992 address cycle on pci bus for cards supporting greater
993 than 32 bit addressing. The default is to look
994 for translation below 32 bit and if not available
995 then look in the higher range.
997 With this option on every unmap_single operation will
998 result in a hardware IOTLB flush operation as opposed
999 to batching them for performance.
1000 sp_off [Default Off]
1001 By default, super page will be supported if Intel IOMMU
1002 has the capability. With this option, super page will
1004 intremap= [X86-64, Intel-IOMMU]
1005 Format: { on (default) | off | nosid }
1006 on enable Interrupt Remapping (default)
1007 off disable Interrupt Remapping
1008 nosid disable Source ID checking
1012 iomem= Disable strict checking of access to MMIO memory
1013 strict regions from userspace.
1029 io7= [HW] IO7 for Marvel based alpha systems
1030 See comment before marvel_specify_io7 in
1031 arch/alpha/kernel/core_marvel.c.
1033 io_delay= [X86] I/O delay method
1035 Standard port 0x80 based delay
1037 Alternate port 0xed based delay (needed on some systems)
1039 Simple two microseconds delay
1044 See Documentation/filesystems/nfs/nfsroot.txt.
1046 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1047 See comment before ip2_setup() in
1048 drivers/char/ip2/ip2base.c.
1051 When an interrupt is not handled search all handlers
1052 for it. Intended to get systems with badly broken
1056 When an interrupt is not handled search all handlers
1057 for it. Also check all handlers each timer
1058 interrupt. Intended to get systems with badly broken
1062 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1064 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1066 <cpu number>,...,<cpu number>
1068 <cpu number>-<cpu number>
1069 (must be a positive range in ascending order)
1071 <cpu number>,...,<cpu number>-<cpu number>
1073 This option can be used to specify one or more CPUs
1074 to isolate from the general SMP balancing and scheduling
1075 algorithms. You can move a process onto or off an
1076 "isolated" CPU via the CPU affinity syscalls or cpuset.
1077 <cpu number> begins at 0 and the maximum value is
1078 "number of CPUs in system - 1".
1080 This option is the preferred way to isolate CPUs. The
1081 alternative -- manually setting the CPU mask of all
1082 tasks in the system -- can cause problems and
1083 suboptimal load balancer performance.
1087 js= [HW,JOY] Analog joystick
1088 See Documentation/input/joystick.txt.
1092 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1093 specifies the amount of memory usable by the kernel
1094 for non-movable allocations. The requested amount is
1095 spread evenly throughout all nodes in the system. The
1096 remaining memory in each node is used for Movable
1097 pages. In the event, a node is too small to have both
1098 kernelcore and Movable pages, kernelcore pages will
1099 take priority and other nodes will have a larger number
1100 of kernelcore pages. The Movable zone is used for the
1101 allocation of pages that may be reclaimed or moved
1102 by the page migration subsystem. This means that
1103 HugeTLB pages may not be allocated from this zone.
1104 Note that allocations like PTEs-from-HighMem still
1105 use the HighMem zone if it exists, and the Normal
1106 zone if it does not.
1108 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1109 Format: <Controller#>[,poll interval]
1110 The controller # is the number of the ehci usb debug
1111 port as it is probed via PCI. The poll interval is
1112 optional and is the number seconds in between
1113 each poll cycle to the debug port in case you need
1114 the functionality for interrupting the kernel with
1115 gdb or control-c on the dbgp connection. When
1116 not using this parameter you use sysrq-g to break into
1117 the kernel debugger.
1119 kgdboc= [KGDB,HW] kgdb over consoles.
1120 Requires a tty driver that supports console polling,
1121 or a supported polling keyboard driver (non-usb).
1122 Serial only format: <serial_device>[,baud]
1123 keyboard only format: kbd
1124 keyboard and serial format: kbd,<serial_device>[,baud]
1125 Optional Kernel mode setting:
1126 kms, kbd format: kms,kbd
1127 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1129 kgdbwait [KGDB] Stop kernel execution and enter the
1130 kernel debugger at the earliest opportunity.
1132 kmac= [MIPS] korina ethernet MAC address.
1133 Configure the RouterBoard 532 series on-chip
1134 Ethernet adapter MAC address.
1136 kmemleak= [KNL] Boot-time kmemleak enable/disable
1137 Valid arguments: on, off
1140 kstack=N [X86] Print N words from the kernel stack
1143 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1144 Default is 0 (don't ignore, but inject #GP)
1146 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1147 Default is 1 (enabled)
1149 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1153 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1154 Default is 1 (enabled)
1156 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1158 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1160 kvm-intel.bypass_guest_pf=
1161 [KVM,Intel] Disables bypassing of guest page faults
1162 on Intel chips. Default is 1 (enabled)
1164 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1165 (virtualized MMU) support on capable Intel chips.
1166 Default is 1 (enabled)
1168 kvm-intel.emulate_invalid_guest_state=
1169 [KVM,Intel] Enable emulation of invalid guest states
1170 Default is 0 (disabled)
1172 kvm-intel.flexpriority=
1173 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1174 Default is 1 (enabled)
1176 kvm-intel.unrestricted_guest=
1177 [KVM,Intel] Disable unrestricted guest feature
1178 (virtualized real and unpaged mode) on capable
1179 Intel chips. Default is 1 (enabled)
1181 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1182 feature (tagged TLBs) on capable Intel chips.
1183 Default is 1 (enabled)
1189 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1192 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1195 libata.dma= [LIBATA] DMA control
1196 libata.dma=0 Disable all PATA and SATA DMA
1197 libata.dma=1 PATA and SATA Disk DMA only
1198 libata.dma=2 ATAPI (CDROM) DMA only
1199 libata.dma=4 Compact Flash DMA only
1200 Combinations also work, so libata.dma=3 enables DMA
1201 for disks and CDROMs, but not CFs.
1203 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1204 libata.ignore_hpa=0 keep BIOS limits (default)
1205 libata.ignore_hpa=1 ignore limits, using full disk
1207 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1211 libata.force= [LIBATA] Force configurations. The format is comma
1212 separated list of "[ID:]VAL" where ID is
1213 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1214 matching port, link or device. Basically, it matches
1215 the ATA ID string printed on console by libata. If
1216 the whole ID part is omitted, the last PORT and DEVICE
1217 values are used. If ID hasn't been specified yet, the
1218 configuration applies to all ports, links and devices.
1220 If only DEVICE is omitted, the parameter applies to
1221 the port and all links and devices behind it. DEVICE
1222 number of 0 either selects the first device or the
1223 first fan-out link behind PMP device. It does not
1224 select the host link. DEVICE number of 15 selects the
1225 host link and device attached to it.
1227 The VAL specifies the configuration to force. As long
1228 as there's no ambiguity shortcut notation is allowed.
1229 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1230 The following configurations can be forced.
1232 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1233 Any ID with matching PORT is used.
1235 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1237 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1238 udma[/][16,25,33,44,66,100,133] notation is also
1241 * [no]ncq: Turn on or off NCQ.
1243 * nohrst, nosrst, norst: suppress hard, soft
1246 * dump_id: dump IDENTIFY data.
1248 If there are multiple matching configurations changing
1249 the same attribute, the last one is used.
1251 memblock=debug [KNL] Enable memblock debug messages.
1253 load_ramdisk= [RAM] List of ramdisks to load from floppy
1254 See Documentation/blockdev/ramdisk.txt.
1256 lockd.nlm_grace_period=P [NFS] Assign grace period.
1259 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1262 lockd.nlm_timeout=T [NFS] Assign timeout value.
1265 lockd.nlm_udpport=M [NFS] Assign UDP port.
1268 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1271 loglevel= All Kernel Messages with a loglevel smaller than the
1272 console loglevel will be printed to the console. It can
1273 also be changed with klogd or other programs. The
1274 loglevels are defined as follows:
1276 0 (KERN_EMERG) system is unusable
1277 1 (KERN_ALERT) action must be taken immediately
1278 2 (KERN_CRIT) critical conditions
1279 3 (KERN_ERR) error conditions
1280 4 (KERN_WARNING) warning conditions
1281 5 (KERN_NOTICE) normal but significant condition
1282 6 (KERN_INFO) informational
1283 7 (KERN_DEBUG) debug-level messages
1285 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1286 in bytes. n must be a power of two. The default
1287 size is set in the kernel config file.
1289 logo.nologo [FB] Disables display of the built-in Linux logo.
1290 This may be used to provide more screen space for
1291 kernel log messages and is useful when debugging
1292 kernel boot problems.
1294 lp=0 [LP] Specify parallel ports to use, e.g,
1295 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1296 lp=reset first parallel port). 'lp=0' disables the
1297 lp=auto printer driver. 'lp=reset' (which can be
1298 specified in addition to the ports) causes
1299 attached printers to be reset. Using
1300 lp=port1,port2,... specifies the parallel ports
1301 to associate lp devices with, starting with
1302 lp0. A port specification may be 'none' to skip
1303 that lp device, or a parport name such as
1304 'parport0'. Specifying 'lp=auto' instead of a
1305 port specification list means that device IDs
1306 from each port should be examined, to see if
1307 an IEEE 1284-compliant printer is attached; if
1308 so, the driver will manage that printer.
1309 See also header of drivers/char/lp.c.
1312 Sets loops_per_jiffy to given constant, thus avoiding
1313 time-consuming boot-time autodetection (up to 250 ms per
1314 CPU). 0 enables autodetection (default). To determine
1315 the correct value for your kernel, boot with normal
1316 autodetection and see what value is printed. Note that
1317 on SMP systems the preset will be applied to all CPUs,
1318 which is likely to cause problems if your CPUs need
1319 significantly divergent settings. An incorrect value
1320 will cause delays in the kernel to be wrong, leading to
1321 unpredictable I/O errors and other breakage. Although
1322 unlikely, in the extreme case this might damage your
1326 Format: <io>,<irq>,<dma>
1328 machvec= [IA64] Force the use of a particular machine-vector
1329 (machvec) in a generic kernel.
1330 Example: machvec=hpzx1_swiotlb
1332 machtype= [Loongson] Share the same kernel image file between different
1334 Example: machtype=lemote-yeeloong-2f-7inch
1336 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1337 than or equal to this physical address is ignored.
1339 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1340 should make use of. maxcpus=n : n >= 0 limits the
1341 kernel to using 'n' processors. n=0 is a special case,
1342 it is equivalent to "nosmp", which also disables
1345 max_loop= [LOOP] Maximum number of loopback devices that can
1351 mce [X86-32] Machine Check Exception
1353 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1355 md= [HW] RAID subsystems devices and level
1356 See Documentation/md.txt.
1359 Format: <first>,<last>
1360 Specifies range of consoles to be captured by the MDA.
1362 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1363 Amount of memory to be used when the kernel is not able
1364 to see the whole system memory or for test.
1365 [X86-32] Use together with memmap= to avoid physical
1366 address space collisions. Without memmap= PCI devices
1367 could be placed at addresses belonging to unused RAM.
1369 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1373 [KNL,SH] Allow user to override the default size for
1374 per-device physically contiguous DMA buffers.
1376 memmap=exactmap [KNL,X86] Enable setting of an exact
1377 E820 memory map, as specified by the user.
1378 Such memmap=exactmap lines can be constructed based on
1379 BIOS output or other requirements. See the memmap=nn@ss
1382 memmap=nn[KMG]@ss[KMG]
1383 [KNL] Force usage of a specific region of memory
1384 Region of memory to be used, from ss to ss+nn.
1386 memmap=nn[KMG]#ss[KMG]
1387 [KNL,ACPI] Mark specific memory as ACPI data.
1388 Region of memory to be used, from ss to ss+nn.
1390 memmap=nn[KMG]$ss[KMG]
1391 [KNL,ACPI] Mark specific memory as reserved.
1392 Region of memory to be used, from ss to ss+nn.
1393 Example: Exclude memory from 0x18690000-0x1869ffff
1394 memmap=64K$0x18690000
1396 memmap=0x10000$0x18690000
1398 memory_corruption_check=0/1 [X86]
1399 Some BIOSes seem to corrupt the first 64k of
1400 memory when doing things like suspend/resume.
1401 Setting this option will scan the memory
1402 looking for corruption. Enabling this will
1403 both detect corruption and prevent the kernel
1404 from using the memory being corrupted.
1405 However, its intended as a diagnostic tool; if
1406 repeatable BIOS-originated corruption always
1407 affects the same memory, you can use memmap=
1408 to prevent the kernel from using that memory.
1410 memory_corruption_check_size=size [X86]
1411 By default it checks for corruption in the low
1412 64k, making this memory unavailable for normal
1413 use. Use this parameter to scan for
1414 corruption in more or less memory.
1416 memory_corruption_check_period=seconds [X86]
1417 By default it checks for corruption every 60
1418 seconds. Use this parameter to check at some
1419 other rate. 0 disables periodic checking.
1421 memtest= [KNL,X86] Enable memtest
1423 default : 0 <disable>
1424 Specifies the number of memtest passes to be
1425 performed. Each pass selects another test
1426 pattern from a given set of patterns. Memtest
1427 fills the memory with this pattern, validates
1428 memory contents and reserves bad memory
1429 regions that are detected.
1431 meye.*= [HW] Set MotionEye Camera parameters
1432 See Documentation/video4linux/meye.txt.
1434 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1435 Multi-Function General Purpose Timers on AMD Geode
1438 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1439 the BIOS has incorrectly applied a workaround. TinyBIOS
1440 version 0.98 is known to be affected, 0.99 fixes the
1441 problem by letting the user disable the workaround.
1445 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1446 physical address is ignored.
1448 mini2440= [ARM,HW,KNL]
1449 Format:[0..2][b][c][t]
1451 MINI2440 configuration specification:
1452 0 - The attached screen is the 3.5" TFT
1453 1 - The attached screen is the 7" TFT
1454 2 - The VGA Shield is attached (1024x768)
1455 Leaving out the screen size parameter will not load
1456 the TFT driver, and the framebuffer will be left
1458 b - Enable backlight. The TFT backlight pin will be
1459 linked to the kernel VESA blanking code and a GPIO
1460 LED. This parameter is not necessary when using the
1462 c - Enable the s3c camera interface.
1463 t - Reserved for enabling touchscreen support. The
1464 touchscreen support is not enabled in the mainstream
1465 kernel as of 2.6.30, a preliminary port can be found
1466 in the "bleeding edge" mini2440 support kernel at
1467 http://repo.or.cz/w/linux-2.6/mini2440.git
1470 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1471 parameter allows control of the logging verbosity for
1472 the additional memory initialisation checks. A value
1473 of 0 disables mminit logging and a level of 4 will
1474 log everything. Information is printed at KERN_DEBUG
1475 so loglevel=8 may also need to be specified.
1478 [MOUSE] Maximum time between finger touching and
1479 leaving touchpad surface for touch to be considered
1480 a tap and be reported as a left button click (for
1481 touchpads working in absolute mode only).
1483 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1484 reporting absolute coordinates, such as tablets
1485 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1486 reporting absolute coordinates, such as tablets
1488 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1489 is similar to kernelcore except it specifies the
1490 amount of memory used for migratable allocations.
1491 If both kernelcore and movablecore is specified,
1492 then kernelcore will be at *least* the specified
1493 value but may be more. If movablecore on its own
1494 is specified, the administrator must be careful
1495 that the amount of memory usable for all allocations
1498 MTD_Partition= [MTD]
1499 Format: <name>,<region-number>,<size>,<offset>
1501 MTD_Region= [MTD] Format:
1502 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1505 See drivers/mtd/cmdlinepart.c.
1507 multitce=off [PPC] This parameter disables the use of the pSeries
1508 firmware feature for updating multiple TCE entries
1511 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1513 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1515 boundary - index of last SLC block on Flex-OneNAND.
1516 The remaining blocks are configured as MLC blocks.
1517 lock - Configure if Flex-OneNAND boundary should be locked.
1518 Once locked, the boundary cannot be changed.
1519 1 indicates lock status, 0 indicates unlock status.
1522 ARM/S3C2412 JIVE boot control
1524 See arch/arm/mach-s3c2412/mach-jive.c
1526 mtouchusb.raw_coordinates=
1527 [HW] Make the MicroTouch USB driver use raw coordinates
1528 ('y', default) or cooked coordinates ('n')
1530 mtrr_chunk_size=nn[KMG] [X86]
1531 used for mtrr cleanup. It is largest continuous chunk
1532 that could hold holes aka. UC entries.
1534 mtrr_gran_size=nn[KMG] [X86]
1535 Used for mtrr cleanup. It is granularity of mtrr block.
1537 Large value could prevent small alignment from
1540 mtrr_spare_reg_nr=n [X86]
1542 Range: 0,7 : spare reg number
1544 Used for mtrr cleanup. It is spare mtrr entries number.
1545 Set to 2 or more if your graphical card needs more.
1547 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1549 netdev= [NET] Network devices parameters
1550 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1551 Note that mem_start is often overloaded to mean
1552 something different and driver-specific.
1553 This usage is only documented in each driver source
1557 [NETFILTER] Enable connection tracking flow accounting
1558 0 to disable accounting
1559 1 to enable accounting
1562 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1563 See Documentation/filesystems/nfs/nfsroot.txt.
1565 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1566 See Documentation/filesystems/nfs/nfsroot.txt.
1568 nfsrootdebug [NFS] enable nfsroot debugging messages.
1569 See Documentation/filesystems/nfs/nfsroot.txt.
1571 nfs.callback_tcpport=
1572 [NFS] set the TCP port on which the NFSv4 callback
1573 channel should listen.
1576 [NFS] sets the pathname to the program which is used
1577 to update the NFS client cache entries.
1579 nfs.cache_getent_timeout=
1580 [NFS] sets the timeout after which an attempt to
1581 update a cache entry is deemed to have failed.
1583 nfs.idmap_cache_timeout=
1584 [NFS] set the maximum lifetime for idmapper cache
1588 [NFS] enable 64-bit inode numbers.
1589 If zero, the NFS client will fake up a 32-bit inode
1590 number for the readdir() and stat() syscalls instead
1591 of returning the full 64-bit number.
1592 The default is to return 64-bit inode numbers.
1594 nfs.nfs4_disable_idmapping=
1595 [NFSv4] When set, this option disables the NFSv4
1596 idmapper on the client, but only if the mount
1597 is using the 'sec=sys' security flavour. This may
1598 make migration from legacy NFSv2/v3 systems easier
1599 provided that the server has the appropriate support.
1600 The default is to always enable NFSv4 idmapping.
1602 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1603 when a NMI is triggered.
1604 Format: [state][,regs][,debounce][,die]
1606 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1607 Format: [panic,][nopanic,][num]
1609 0 - turn nmi_watchdog off
1610 When panic is specified, panic when an NMI watchdog
1611 timeout occurs (or 'nopanic' to override the opposite
1613 This is useful when you use a panic=... timeout and
1614 need the box quickly up again.
1616 netpoll.carrier_timeout=
1617 [NET] Specifies amount of time (in seconds) that
1618 netpoll should wait for a carrier. By default netpoll
1621 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1622 emulation library even if a 387 maths coprocessor
1626 [HW] Never suspend the console
1627 Disable suspending of consoles during suspend and
1628 hibernate operations. Once disabled, debugging
1629 messages can reach various consoles while the rest
1630 of the system is being put to sleep (ie, while
1631 debugging driver suspend/resume hooks). This may
1632 not work reliably with all consoles, but is known
1633 to work with serial and VGA consoles.
1635 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1636 caches in the slab allocator. Saves per-node memory,
1637 but will impact performance.
1641 noapic [SMP,APIC] Tells the kernel to not make use of any
1642 IOAPICs that may be present in the system.
1644 noautogroup Disable scheduler automatic task group creation.
1646 nobats [PPC] Do not use BATs for mapping kernel lowmem
1647 on "Classic" PPC cores.
1651 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1653 nodelayacct [KNL] Disable per-task delay accounting
1655 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1657 nodsp [SH] Disable hardware DSP at boot time.
1659 noefi [X86] Disable EFI runtime services support.
1664 On X86-32 available only on PAE configured kernels.
1665 noexec=on: enable non-executable mappings (default)
1666 noexec=off: disable non-executable mappings
1669 Disable SMEP (Supervisor Mode Execution Protection)
1670 even if it is supported by processor.
1673 This affects only 32-bit executables.
1674 noexec32=on: enable non-executable mappings (default)
1675 read doesn't imply executable mappings
1676 noexec32=off: disable non-executable mappings
1677 read implies executable mappings
1679 nofpu [SH] Disable hardware FPU at boot time.
1681 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1682 register save and restore. The kernel will only save
1683 legacy floating-point registers on task switch.
1685 noxsave [BUGS=X86] Disables x86 extended register state save
1686 and restore using xsave. The kernel will fallback to
1687 enabling legacy floating-point and sse state.
1689 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1690 wfi(ARM) instruction doesn't work correctly and not to
1691 use it. This is also useful when using JTAG debugger.
1693 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1694 instruction doesn't work correctly and not to
1697 no_file_caps Tells the kernel not to honor file capabilities. The
1698 only way then for a file to be executed with privilege
1699 is to be setuid root or executed by root.
1701 nohalt [IA-64] Tells the kernel not to use the power saving
1702 function PAL_HALT_LIGHT when idle. This increases
1703 power-consumption. On the positive side, it reduces
1704 interrupt wake-up latency, which may improve performance
1705 in certain environments such as networked servers or
1708 nohz= [KNL] Boottime enable/disable dynamic ticks
1709 Valid arguments: on, off
1712 noiotrap [SH] Disables trapped I/O port accesses.
1714 noirqdebug [X86-32] Disables the code which attempts to detect and
1715 disable unhandled interrupt sources.
1717 no_timer_check [X86,APIC] Disables the code which tests for
1718 broken timer IRQ sources.
1720 noisapnp [ISAPNP] Disables ISA PnP code.
1722 noinitrd [RAM] Tells the kernel not to load any configured
1725 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1727 [Deprecated - use intremap=off]
1731 nojitter [IA64] Disables jitter checking for ITC timers.
1733 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1735 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1738 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1740 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1742 noltlbs [PPC] Do not use large page/tlb entries for kernel
1743 lowmem mapping on PPC40x.
1745 nomca [IA-64] Disable machine check abort handling
1747 nomce [X86-32] Machine Check Exception
1749 nomfgpt [X86-32] Disable Multi-Function General Purpose
1750 Timer usage (for AMD Geode machines).
1752 nopat [X86] Disable PAT (page attribute table extension of
1753 pagetables) support.
1755 norandmaps Don't use address space randomization. Equivalent to
1756 echo 0 > /proc/sys/kernel/randomize_va_space
1758 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1760 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1761 with UP alternatives
1763 noresidual [PPC] Don't use residual data on PReP machines.
1765 noresume [SWSUSP] Disables resume and restores original swap
1768 no-scroll [VGA] Disables scrollback.
1769 This is required for the Braillex ib80-piezo Braille
1770 reader made by F.H. Papenmeier (Germany).
1774 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1776 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1777 and disable the IO APIC. legacy for "maxcpus=0".
1779 nosoftlockup [KNL] Disable the soft-lockup detector.
1781 nosync [HW,M68K] Disables sync negotiation for all devices.
1783 notsc [BUGS=X86-32] Disable Time Stamp Counter
1785 nousb [USB] Disable the USB subsystem
1787 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1791 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1793 nptcg= [IA64] Override max number of concurrent global TLB
1794 purges which is reported from either PAL_VM_SUMMARY or
1797 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1798 could support. nr_cpus=n : n >= 1 limits the kernel to
1799 supporting 'n' processors. Later in runtime you can not
1800 use hotplug cpu feature to put more cpu back to online.
1801 just like you compile the kernel NR_CPUS=n
1803 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1805 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1806 one of ['zone', 'node', 'default'] can be specified
1807 This can be set from sysctl after boot.
1808 See Documentation/sysctl/vm.txt for details.
1810 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1811 See Documentation/debugging-via-ohci1394.txt for more
1814 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1815 Rather than timing out after 20 ms if an EC
1816 command is not properly ACKed, override the length
1817 of the timeout. We have interrupts disabled while
1818 waiting for the ACK, so if this is set too high
1819 interrupts *may* be lost!
1821 omap_mux= [OMAP] Override bootloader pin multiplexing.
1822 Format: <mux_mode0.mode_name=value>...
1823 For example, to override I2C bus2:
1824 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1826 oprofile.timer= [HW]
1827 Use timer interrupt instead of performance counters
1829 oprofile.cpu_type= Force an oprofile cpu type
1830 This might be useful if you have an older oprofile
1831 userland or if you want common events.
1832 Format: { arch_perfmon }
1833 arch_perfmon: [X86] Force use of architectural
1834 perfmon on Intel CPUs instead of the
1835 CPU specific event set.
1837 oops=panic Always panic on oopses. Default is to just kill the
1838 process, but there is a small probability of
1839 deadlocking the machine.
1840 This will also cause panics on machine check exceptions.
1841 Useful together with panic=30 to trigger a reboot.
1844 See Documentation/sound/oss/oss-parameters.txt
1846 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1847 seconds before rebooting
1850 parkbd.port= [HW] Parallel port number the keyboard adapter is
1851 connected to, default is 0.
1853 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1854 0 for XT, 1 for AT (default is AT).
1857 parport= [HW,PPT] Specify parallel ports. 0 disables.
1858 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1859 Use 'auto' to force the driver to use any
1860 IRQ/DMA settings detected (the default is to
1861 ignore detected IRQ/DMA settings because of
1862 possible conflicts). You can specify the base
1863 address, IRQ, and DMA settings; IRQ and DMA
1864 should be numbers, or 'auto' (for using detected
1865 settings on that particular port), or 'nofifo'
1866 (to avoid using a FIFO even if it is detected).
1867 Parallel ports are assigned in the order they
1868 are specified on the command line, starting
1871 parport_init_mode= [HW,PPT]
1872 Configure VIA parallel port to operate in
1873 a specific mode. This is necessary on Pegasos
1874 computer where firmware has no options for setting
1875 up parallel port mode and sets it to spp.
1876 Currently this function knows 686a and 8231 chips.
1877 Format: [spp|ps2|epp|ecp|ecpepp]
1880 Halt all CPUs after the first oops has been printed for
1881 the specified number of seconds. This is to be used if
1882 your oopses keep scrolling off the screen.
1887 See header of drivers/block/paride/pcd.c.
1888 See also Documentation/blockdev/paride.txt.
1890 pci=option[,option...] [PCI] various PCI subsystem options:
1891 earlydump [X86] dump PCI config space before the kernel
1893 off [X86] don't probe for the PCI bus
1894 bios [X86-32] force use of PCI BIOS, don't access
1895 the hardware directly. Use this if your machine
1896 has a non-standard PCI host bridge.
1897 nobios [X86-32] disallow use of PCI BIOS, only direct
1898 hardware access methods are allowed. Use this
1899 if you experience crashes upon bootup and you
1900 suspect they are caused by the BIOS.
1901 conf1 [X86] Force use of PCI Configuration
1903 conf2 [X86] Force use of PCI Configuration
1905 noaer [PCIE] If the PCIEAER kernel config parameter is
1906 enabled, this kernel boot option can be used to
1907 disable the use of PCIE advanced error reporting.
1908 nodomains [PCI] Disable support for multiple PCI
1909 root domains (aka PCI segments, in ACPI-speak).
1910 nommconf [X86] Disable use of MMCONFIG for PCI
1912 check_enable_amd_mmconf [X86] check for and enable
1913 properly configured MMIO access to PCI
1914 config space on AMD family 10h CPU
1915 nomsi [MSI] If the PCI_MSI kernel config parameter is
1916 enabled, this kernel boot option can be used to
1917 disable the use of MSI interrupts system-wide.
1918 noioapicquirk [APIC] Disable all boot interrupt quirks.
1919 Safety option to keep boot IRQs enabled. This
1920 should never be necessary.
1921 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1922 primary IO-APIC for bridges that cannot disable
1923 boot IRQs. This fixes a source of spurious IRQs
1924 when the system masks IRQs.
1925 noioapicreroute [APIC] Disable workaround that uses the
1926 boot IRQ equivalent of an IRQ that connects to
1927 a chipset where boot IRQs cannot be disabled.
1928 The opposite of ioapicreroute.
1929 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1930 routing table. These calls are known to be buggy
1931 on several machines and they hang the machine
1932 when used, but on other computers it's the only
1933 way to get the interrupt routing table. Try
1934 this option if the kernel is unable to allocate
1935 IRQs or discover secondary PCI buses on your
1937 rom [X86] Assign address space to expansion ROMs.
1938 Use with caution as certain devices share
1939 address decoders between ROMs and other
1941 norom [X86] Do not assign address space to
1942 expansion ROMs that do not already have
1943 BIOS assigned address ranges.
1944 nobar [X86] Do not assign address space to the
1945 BARs that weren't assigned by the BIOS.
1946 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1947 assigned automatically to PCI devices. You can
1948 make the kernel exclude IRQs of your ISA cards
1950 pirqaddr=0xAAAAA [X86] Specify the physical address
1951 of the PIRQ table (normally generated
1952 by the BIOS) if it is outside the
1953 F0000h-100000h range.
1954 lastbus=N [X86] Scan all buses thru bus #N. Can be
1955 useful if the kernel is unable to find your
1956 secondary buses and you want to tell it
1957 explicitly which ones they are.
1958 assign-busses [X86] Always assign all PCI bus
1959 numbers ourselves, overriding
1960 whatever the firmware may have done.
1961 usepirqmask [X86] Honor the possible IRQ mask stored
1962 in the BIOS $PIR table. This is needed on
1963 some systems with broken BIOSes, notably
1964 some HP Pavilion N5400 and Omnibook XE3
1965 notebooks. This will have no effect if ACPI
1966 IRQ routing is enabled.
1967 noacpi [X86] Do not use ACPI for IRQ routing
1968 or for PCI scanning.
1969 use_crs [X86] Use PCI host bridge window information
1970 from ACPI. On BIOSes from 2008 or later, this
1971 is enabled by default. If you need to use this,
1972 please report a bug.
1973 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1974 If you need to use this, please report a bug.
1975 routeirq Do IRQ routing for all PCI devices.
1976 This is normally done in pci_enable_device(),
1977 so this option is a temporary workaround
1978 for broken drivers that don't call it.
1979 skip_isa_align [X86] do not align io start addr, so can
1980 handle more pci cards
1981 firmware [ARM] Do not re-enumerate the bus but instead
1982 just use the configuration from the
1983 bootloader. This is currently used on
1984 IXP2000 systems where the bus has to be
1985 configured a certain way for adjunct CPUs.
1986 noearly [X86] Don't do any early type 1 scanning.
1987 This might help on some broken boards which
1988 machine check when some devices' config space
1989 is read. But various workarounds are disabled
1990 and some IOMMU drivers will not work.
1991 bfsort Sort PCI devices into breadth-first order.
1992 This sorting is done to get a device
1993 order compatible with older (<= 2.4) kernels.
1994 nobfsort Don't sort PCI devices into breadth-first order.
1995 cbiosize=nn[KMG] The fixed amount of bus space which is
1996 reserved for the CardBus bridge's IO window.
1997 The default value is 256 bytes.
1998 cbmemsize=nn[KMG] The fixed amount of bus space which is
1999 reserved for the CardBus bridge's memory
2000 window. The default value is 64 megabytes.
2003 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2004 Specifies alignment and device to reassign
2005 aligned memory resources.
2006 If <order of align> is not specified,
2007 PAGE_SIZE is used as alignment.
2008 PCI-PCI bridge can be specified, if resource
2009 windows need to be expanded.
2010 ecrc= Enable/disable PCIe ECRC (transaction layer
2011 end-to-end CRC checking).
2012 bios: Use BIOS/firmware settings. This is the
2016 realloc reallocate PCI resources if allocations done by BIOS
2019 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2022 force Enable ASPM even on devices that claim not to support it.
2023 WARNING: Forcing ASPM on may cause system lockups.
2025 pcie_ports= [PCIE] PCIe ports handling:
2026 auto Ask the BIOS whether or not to use native PCIe services
2027 associated with PCIe ports (PME, hot-plug, AER). Use
2028 them only if that is allowed by the BIOS.
2029 native Use native PCIe services associated with PCIe ports
2031 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2034 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2035 nomsi Do not use MSI for native PCIe PME signaling (this makes
2036 all PCIe root ports use INTx for all services).
2038 pcmv= [HW,PCMCIA] BadgePAD 4
2041 See Documentation/blockdev/paride.txt.
2043 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2046 See arch/parisc/kernel/pdc_chassis.c
2048 percpu_alloc= Select which percpu first chunk allocator to use.
2049 Currently supported values are "embed" and "page".
2050 Archs may support subset or none of the selections.
2051 See comments in mm/percpu.c for details on each
2052 allocator. This parameter is primarily for debugging
2053 and performance comparison.
2056 See Documentation/blockdev/paride.txt.
2059 See Documentation/blockdev/paride.txt.
2061 pirq= [SMP,APIC] Manual mp-table setup
2062 See Documentation/x86/i386/IO-APIC.txt.
2064 plip= [PPT,NET] Parallel port network link
2065 Format: { parport<nr> | timid | 0 }
2066 See also Documentation/parport.txt.
2068 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2069 Override pmtimer IOPort with a hex value.
2073 Enable PNP debug messages. This depends on the
2074 CONFIG_PNP_DEBUG_MESSAGES option.
2080 { on | off | curr | res | no-curr | no-res }
2083 [ISAPNP] Exclude IRQs for the autoconfiguration
2086 [ISAPNP] Exclude DMAs for the autoconfiguration
2088 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2089 Ranges are in pairs (I/O port base and size).
2092 [ISAPNP] Exclude memory regions for the
2094 Ranges are in pairs (memory base and size).
2096 ports= [IP_VS_FTP] IPVS ftp helper module
2098 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2100 Format: <port>,<port>....
2102 print-fatal-signals=
2103 [KNL] debug: print fatal signals
2105 If enabled, warn about various signal handling
2106 related application anomalies: too many signals,
2107 too many POSIX.1 timers, fatal signals causing a
2110 If you hit the warning due to signal overflow,
2111 you might want to try "ulimit -i unlimited".
2115 printk.time= Show timing data prefixed to each printk message line
2116 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2118 processor.max_cstate= [HW,ACPI]
2119 Limit processor to maximum C-state
2120 max_cstate=9 overrides any DMI blacklist limit.
2122 processor.nocst [HW,ACPI]
2123 Ignore the _CST method to determine C-states,
2124 instead using the legacy FADT method
2126 profile= [KNL] Enable kernel profiling via /proc/profile
2127 Format: [schedule,]<number>
2128 Param: "schedule" - profile schedule points.
2129 Param: <number> - step/bucket size as a power of 2 for
2130 statistical time based profiling.
2131 Param: "sleep" - profile D-state sleeping (millisecs).
2132 Requires CONFIG_SCHEDSTATS
2133 Param: "kvm" - profile VM exits.
2135 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2137 See Documentation/blockdev/ramdisk.txt.
2139 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2140 probe for; one of (bare|imps|exps|lifebook|any).
2141 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2143 psmouse.resetafter= [HW,MOUSE]
2144 Try to reset the device after so many bad packets
2147 [HW,MOUSE] Set desired mouse resolution, in dpi.
2148 psmouse.smartscroll=
2149 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2150 0 = disabled, 1 = enabled (default).
2153 See Documentation/blockdev/paride.txt.
2156 [KNL] Number of legacy pty's. Overwrites compiled-in
2159 quiet [KNL] Disable most log messages
2164 See Documentation/md.txt.
2166 ramdisk_blocksize= [RAM]
2167 See Documentation/blockdev/ramdisk.txt.
2169 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2170 See Documentation/blockdev/ramdisk.txt.
2172 rcupdate.blimit= [KNL,BOOT]
2173 Set maximum number of finished RCU callbacks to process
2176 rcupdate.qhimark= [KNL,BOOT]
2177 Set threshold of queued
2178 RCU callbacks over which batch limiting is disabled.
2180 rcupdate.qlowmark= [KNL,BOOT]
2181 Set threshold of queued RCU callbacks below which
2182 batch limiting is re-enabled.
2186 Run specified binary instead of /init from the ramdisk,
2187 used for early userspace startup. See initrd.
2189 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2190 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2191 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2194 [KNL, SMP] Set scheduler's default relax_domain_level.
2195 See Documentation/cgroups/cpusets.txt.
2197 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2199 reservetop= [X86-32]
2201 Reserves a hole at the top of the kernel virtual
2206 Set the amount of memory to reserve for BIOS at
2207 the bottom of the address space.
2209 reset_devices [KNL] Force drivers to reset the underlying device
2210 during initialization.
2213 Specify the partition device for software suspend
2215 resume_offset= [SWSUSP]
2216 Specify the offset from the beginning of the partition
2217 given by "resume=" at which the swap header is located,
2218 in <PAGE_SIZE> units (needed only for swap files).
2219 See Documentation/power/swsusp-and-swap-files.txt
2221 hibernate= [HIBERNATION]
2222 noresume Don't check if there's a hibernation image
2223 present during boot.
2224 nocompress Don't compress/decompress hibernation images.
2226 retain_initrd [RAM] Keep initrd memory after extraction
2228 rhash_entries= [KNL,NET]
2229 Set number of hash buckets for route cache
2231 riscom8= [HW,SERIAL]
2232 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2234 ro [KNL] Mount root device read-only on boot
2236 root= [KNL] Root filesystem
2238 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2239 mount the root filesystem
2241 rootflags= [KNL] Set root filesystem mount option string
2243 rootfstype= [KNL] Set root filesystem type
2245 rootwait [KNL] Wait (indefinitely) for root device to show up.
2246 Useful for devices that are detected asynchronously
2247 (e.g. USB and MMC devices).
2249 rw [KNL] Mount root device read-write on boot
2251 S [KNL] Run init in single mode
2254 See drivers/net/irda/sa1100_ir.c.
2256 sbni= [NET] Granch SBNI12 leased line adapter
2258 sched_debug [KNL] Enables verbose scheduler debug messages.
2260 security= [SECURITY] Choose a security module to enable at boot.
2261 If this boot parameter is not specified, only the first
2262 security module asking for security registration will be
2263 loaded. An invalid security module name will be treated
2264 as if no module has been chosen.
2266 selinux= [SELINUX] Disable or enable SELinux at boot time.
2267 Format: { "0" | "1" }
2268 See security/selinux/Kconfig help text.
2271 Default value is set via kernel config option.
2272 If enabled at boot time, /selinux/disable can be used
2273 later to disable prior to initial policy load.
2275 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2276 Format: { "0" | "1" }
2277 See security/apparmor/Kconfig help text
2280 Default value is set via kernel config option.
2282 serialnumber [BUGS=X86-32]
2285 Maximal number of shapers.
2287 show_msr= [x86] show boot-time MSR settings
2288 Format: { <integer> }
2289 Show boot-time (BIOS-initialized) MSR settings.
2290 The parameter means the number of CPUs to show,
2291 for example 1 means boot CPU only.
2298 slub_debug[=options[,slabs]] [MM, SLUB]
2299 Enabling slub_debug allows one to determine the
2300 culprit if slab objects become corrupted. Enabling
2301 slub_debug can create guard zones around objects and
2302 may poison objects when not in use. Also tracks the
2303 last alloc / free. For more information see
2304 Documentation/vm/slub.txt.
2306 slub_max_order= [MM, SLUB]
2307 Determines the maximum allowed order for slabs.
2308 A high setting may cause OOMs due to memory
2309 fragmentation. For more information see
2310 Documentation/vm/slub.txt.
2312 slub_min_objects= [MM, SLUB]
2313 The minimum number of objects per slab. SLUB will
2314 increase the slab order up to slub_max_order to
2315 generate a sufficiently large slab able to contain
2316 the number of objects indicated. The higher the number
2317 of objects the smaller the overhead of tracking slabs
2318 and the less frequently locks need to be acquired.
2319 For more information see Documentation/vm/slub.txt.
2321 slub_min_order= [MM, SLUB]
2322 Determines the mininum page order for slabs. Must be
2323 lower than slub_max_order.
2324 For more information see Documentation/vm/slub.txt.
2326 slub_nomerge [MM, SLUB]
2327 Disable merging of slabs with similar size. May be
2328 necessary if there is some reason to distinguish
2329 allocs to different slabs. Debug options disable
2330 merging on their own.
2331 For more information see Documentation/vm/slub.txt.
2334 Format: <io1>[,<io2>[,...,<io8>]]
2336 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2337 attempt to substitute SMP alternatives once at boot.
2339 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2340 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2341 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2342 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2343 smsc-ircc2.ircc_irq= [HW] IRQ line
2344 smsc-ircc2.ircc_dma= [HW] DMA channel
2345 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2346 0: Toshiba Satellite 1800 (GP data pin select)
2347 1: Fast pin select (default)
2351 [KNL] Should the soft-lockup detector generate panics.
2354 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2355 See Documentation/sonypi.txt
2357 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2358 See Documentation/serial/specialix.txt.
2360 spia_io_base= [HW,MTD]
2366 Enabled the stack tracer on boot up.
2370 Set the STI (builtin display/keyboard on the HP-PARISC
2371 machines) console (graphic card) which should be used
2372 as the initial boot-console.
2373 See also comment in drivers/video/console/sticore.c.
2376 See comment in drivers/video/console/sticore.c.
2379 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2381 sunrpc.min_resvport=
2382 sunrpc.max_resvport=
2384 SunRPC servers often require that client requests
2385 originate from a privileged port (i.e. a port in the
2386 range 0 < portnr < 1024).
2387 An administrator who wishes to reserve some of these
2388 ports for other uses may adjust the range that the
2389 kernel's sunrpc client considers to be privileged
2390 using these two parameters to set the minimum and
2391 maximum port values.
2395 Control how the NFS server code allocates CPUs to
2396 service thread pools. Depending on how many NICs
2397 you have and where their interrupts are bound, this
2398 option will affect which CPUs will do NFS serving.
2399 Note: this parameter cannot be changed while the
2400 NFS server is running.
2402 auto the server chooses an appropriate mode
2403 automatically using heuristics
2404 global a single global pool contains all CPUs
2405 percpu one pool for each CPU
2406 pernode one pool for each NUMA node (equivalent
2407 to global on non-NUMA machines)
2409 sunrpc.tcp_slot_table_entries=
2410 sunrpc.udp_slot_table_entries=
2412 Sets the upper limit on the number of simultaneous
2413 RPC calls that can be sent from the client to a
2414 server. Increasing these values may allow you to
2415 improve throughput, but will also increase the
2416 amount of memory reserved for use by the client.
2419 [KNL] Enable accounting of swap in memory resource
2420 controller if no parameter or 1 is given or disable
2421 it if 0 is given (See Documentation/cgroups/memory.txt)
2423 swiotlb= [IA-64] Number of I/O TLB slabs
2427 sysfs.deprecated=0|1 [KNL]
2428 Enable/disable old style sysfs layout for old udev
2429 on older distributions. When this option is enabled
2430 very new udev will not work anymore. When this option
2431 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2432 in older udev will not work anymore.
2433 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2434 the kernel configuration.
2436 sysrq_always_enabled
2438 Ignore sysrq setting - this boot parameter will
2439 neutralize any effect of /proc/sys/kernel/sysrq.
2440 Useful for debugging.
2444 test_suspend= [SUSPEND]
2445 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2446 standby suspend) as the system sleep state to briefly
2447 enter during system startup. The system is woken from
2448 this state using a wakeup-capable RTC alarm.
2450 thash_entries= [KNL,NET]
2451 Set number of hash buckets for TCP connection
2453 thermal.act= [HW,ACPI]
2454 -1: disable all active trip points in all thermal zones
2455 <degrees C>: override all lowest active trip points
2457 thermal.crt= [HW,ACPI]
2458 -1: disable all critical trip points in all thermal zones
2459 <degrees C>: override all critical trip points
2461 thermal.nocrt= [HW,ACPI]
2462 Set to disable actions on ACPI thermal zone
2463 critical and hot trip points.
2465 thermal.off= [HW,ACPI]
2466 1: disable ACPI thermal control
2468 thermal.psv= [HW,ACPI]
2469 -1: disable all passive trip points
2470 <degrees C>: override all passive trip points to this
2473 thermal.tzp= [HW,ACPI]
2474 Specify global default ACPI thermal zone polling rate
2475 <deci-seconds>: poll all this frequency
2476 0: no polling (default)
2479 Force threading of all interrupt handlers except those
2480 marked explicitely IRQF_NO_THREAD.
2484 Specify if the kernel should make use of the cpu
2485 topology information if the hardware supports this.
2486 The scheduler will make use of this information and
2487 e.g. base its process migration decisions on it.
2492 tpm_suspend_pcr=[HW,TPM]
2493 Format: integer pcr id
2494 Specify that at suspend time, the tpm driver
2495 should extend the specified pcr with zeros,
2496 as a workaround for some chips which fail to
2497 flush the last written pcr on TPM_SaveState.
2498 This will guarantee that all the other pcrs
2501 trace_buf_size=nn[KMG]
2502 [FTRACE] will set tracing buffer size.
2504 trace_event=[event-list]
2505 [FTRACE] Set and start specified trace events in order
2506 to facilitate early boot debugging.
2507 See also Documentation/trace/events.txt
2509 tsc= Disable clocksource stability checks for TSC.
2511 [x86] reliable: mark tsc clocksource as reliable, this
2512 disables clocksource verification at runtime, as well
2513 as the stability checks done at bootup. Used to enable
2514 high-resolution timer mode on older hardware, and in
2515 virtualized environment.
2516 [x86] noirqtime: Do not use TSC to do irq accounting.
2517 Used to run time disable IRQ_TIME_ACCOUNTING on any
2518 platforms where RDTSC is slow and this accounting
2521 turbografx.map[2|3]= [HW,JOY]
2522 TurboGraFX parallel port interface
2524 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2525 See also Documentation/input/joystick-parport.txt
2527 uhash_entries= [KNL,NET]
2528 Set number of hash buckets for UDP/UDP-Lite connections
2531 [USB] Ignore overcurrent events (default N).
2532 Some badly-designed motherboards generate lots of
2533 bogus events, for ports that aren't wired to
2534 anything. Set this parameter to avoid log spamming.
2535 Note that genuine overcurrent events won't be
2539 [X86] Cause panic on unknown NMI.
2541 usbcore.autosuspend=
2542 [USB] The autosuspend time delay (in seconds) used
2543 for newly-detected USB devices (default 2). This
2544 is the time required before an idle device will be
2545 autosuspended. Devices for which the delay is set
2546 to a negative value won't be autosuspended at all.
2548 usbcore.usbfs_snoop=
2549 [USB] Set to log all usbfs traffic (default 0 = off).
2551 usbcore.blinkenlights=
2552 [USB] Set to cycle leds on hubs (default 0 = off).
2554 usbcore.old_scheme_first=
2555 [USB] Start with the old device initialization
2556 scheme (default 0 = off).
2558 usbcore.use_both_schemes=
2559 [USB] Try the other device initialization scheme
2560 if the first one fails (default 1 = enabled).
2562 usbcore.initial_descriptor_timeout=
2563 [USB] Specifies timeout for the initial 64-byte
2564 USB_REQ_GET_DESCRIPTOR request in milliseconds
2565 (default 5000 = 5.0 seconds).
2568 [USBHID] The interval which mice are to be polled at.
2570 usb-storage.delay_use=
2571 [UMS] The delay in seconds before a new device is
2572 scanned for Logical Units (default 5).
2575 [UMS] A list of quirks entries to supplement or
2576 override the built-in unusual_devs list. List
2577 entries are separated by commas. Each entry has
2578 the form VID:PID:Flags where VID and PID are Vendor
2579 and Product ID values (4-digit hex numbers) and
2580 Flags is a set of characters, each corresponding
2581 to a common usb-storage quirk flag as follows:
2582 a = SANE_SENSE (collect more than 18 bytes
2584 b = BAD_SENSE (don't collect more than 18
2585 bytes of sense data);
2586 c = FIX_CAPACITY (decrease the reported
2587 device capacity by one sector);
2588 d = NO_READ_DISC_INFO (don't use
2589 READ_DISC_INFO command);
2590 e = NO_READ_CAPACITY_16 (don't use
2591 READ_CAPACITY_16 command);
2592 h = CAPACITY_HEURISTICS (decrease the
2593 reported device capacity by one
2594 sector if the number is odd);
2595 i = IGNORE_DEVICE (don't bind to this
2597 l = NOT_LOCKABLE (don't try to lock and
2598 unlock ejectable media);
2599 m = MAX_SECTORS_64 (don't transfer more
2600 than 64 sectors = 32 KB at a time);
2601 n = INITIAL_READ10 (force a retry of the
2602 initial READ(10) command);
2603 o = CAPACITY_OK (accept the capacity
2604 reported by the device);
2605 r = IGNORE_RESIDUE (the device reports
2606 bogus residue values);
2607 s = SINGLE_LUN (the device has only one
2609 w = NO_WP_DETECT (don't test whether the
2610 medium is write-protected).
2611 Example: quirks=0419:aaf5:rl,0421:0433:rc
2614 [X86] Flags controlling user PTE allocations.
2616 nohigh = do not allocate PTE pages in
2617 HIGHMEM regardless of setting
2621 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2622 vdso=1: enable VDSO (default)
2623 vdso=0: disable VDSO mapping
2626 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2627 vdso32=1: enable 32-bit VDSO (default)
2628 vdso32=0: disable 32-bit VDSO mapping
2631 vector=percpu: enable percpu vector domain
2633 video= [FB] Frame buffer configuration
2634 See Documentation/fb/modedb.txt.
2636 vga= [BOOT,X86-32] Select a particular video mode
2637 See Documentation/x86/boot.txt and
2638 Documentation/svga.txt.
2639 Use vga=ask for menu.
2640 This is actually a boot loader parameter; the value is
2641 passed to the kernel using a special protocol.
2643 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2644 size of <nn>. This can be used to increase the
2645 minimum size (128MB on x86). It can also be used to
2646 decrease the size and leave more room for directly
2649 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2652 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2655 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2658 vt.cur_default= [VT] Default cursor shape.
2659 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2660 the parameters of the <Esc>[?A;B;Cc escape sequence;
2661 see VGA-softcursor.txt. Default: 2 = underline.
2663 vt.default_blu= [VT]
2664 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2665 Change the default blue palette of the console.
2666 This is a 16-member array composed of values
2669 vt.default_grn= [VT]
2670 Format: <green0>,<green1>,<green2>,...,<green15>
2671 Change the default green palette of the console.
2672 This is a 16-member array composed of values
2675 vt.default_red= [VT]
2676 Format: <red0>,<red1>,<red2>,...,<red15>
2677 Change the default red palette of the console.
2678 This is a 16-member array composed of values
2684 Set system-wide default UTF-8 mode for all tty's.
2685 Default is 1, i.e. UTF-8 mode is enabled for all
2686 newly opened terminals.
2688 vt.global_cursor_default=
2691 Set system-wide default for whether a cursor
2692 is shown on new VTs. Default is -1,
2693 i.e. cursors will be created by default unless
2694 overridden by individual drivers. 0 will hide
2695 cursors, 1 will display them.
2697 watchdog timers [HW,WDT] For information on watchdog timers,
2698 see Documentation/watchdog/watchdog-parameters.txt
2699 or other driver-specific files in the
2700 Documentation/watchdog/ directory.
2702 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2703 default x2apic cluster mode on platforms
2706 x86_mrst_timer= [X86-32,APBT]
2707 Choose timer option for x86 Moorestown MID platform.
2708 Two valid options are apbt timer only and lapic timer
2709 plus one apbt timer for broadcast timer.
2710 x86_mrst_timer=apbt_only | lapic_and_apbt
2712 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2713 xd_geo= See header of drivers/block/xd.c.
2715 xen_emul_unplug= [HW,X86,XEN]
2716 Unplug Xen emulated devices
2717 Format: [unplug0,][unplug1]
2718 ide-disks -- unplug primary master IDE devices
2719 aux-ide-disks -- unplug non-primary-master IDE devices
2720 nics -- unplug network devices
2721 all -- unplug all emulated devices (NICs and IDE disks)
2722 unnecessary -- unplugging emulated devices is
2723 unnecessary even if the host did not respond to
2725 never -- do not unplug even if version check succeeds
2727 xirc2ps_cs= [NET,PCMCIA]
2729 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2731 ______________________________________________________________________
2735 Add more DRM drivers.
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blob