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 EVM Extended Verification Module
52 FB The frame buffer device is enabled.
53 GCOV GCOV profiling is enabled.
54 HW Appropriate hardware is enabled.
55 IA-64 IA-64 architecture is enabled.
56 IMA Integrity measurement architecture is enabled.
57 IOSCHED More than one I/O scheduler is enabled.
58 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
59 IPV6 IPv6 support is enabled.
60 ISAPNP ISA PnP code is enabled.
61 ISDN Appropriate ISDN support is enabled.
62 JOY Appropriate joystick support is enabled.
63 KGDB Kernel debugger support is enabled.
64 KVM Kernel Virtual Machine support is enabled.
65 LIBATA Libata driver is enabled
66 LP Printer support is enabled.
67 LOOP Loopback device support is enabled.
68 M68k M68k architecture is enabled.
69 These options have more detailed description inside of
70 Documentation/m68k/kernel-options.txt.
71 MCA MCA bus support is enabled.
72 MDA MDA console support is enabled.
73 MOUSE Appropriate mouse support is enabled.
74 MSI Message Signaled Interrupts (PCI).
75 MTD MTD (Memory Technology Device) support is enabled.
76 NET Appropriate network support is enabled.
77 NUMA NUMA support is enabled.
78 NFS Appropriate NFS support is enabled.
79 OSS OSS sound support is enabled.
80 PV_OPS A paravirtualized kernel is enabled.
81 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
82 PARISC The PA-RISC architecture is enabled.
83 PCI PCI bus support is enabled.
84 PCIE PCI Express support is enabled.
85 PCMCIA The PCMCIA subsystem is enabled.
86 PNP Plug & Play support is enabled.
87 PPC PowerPC architecture is enabled.
88 PPT Parallel port support is enabled.
89 PS2 Appropriate PS/2 support is enabled.
90 RAM RAM disk support is enabled.
91 S390 S390 architecture is enabled.
92 SCSI Appropriate SCSI support is enabled.
93 A lot of drivers have their options described inside
94 the Documentation/scsi/ sub-directory.
95 SECURITY Different security models are enabled.
96 SELINUX SELinux support is enabled.
97 APPARMOR AppArmor support is enabled.
98 SERIAL Serial support is enabled.
99 SH SuperH architecture is enabled.
100 SMP The kernel is an SMP kernel.
101 SPARC Sparc architecture is enabled.
102 SWSUSP Software suspend (hibernation) is enabled.
103 SUSPEND System suspend states are enabled.
104 FTRACE Function tracing enabled.
105 TPM TPM drivers are enabled.
106 TS Appropriate touchscreen support is enabled.
107 UMS USB Mass Storage support is enabled.
108 USB USB support is enabled.
109 USBHID USB Human Interface Device support is enabled.
110 V4L Video For Linux support is enabled.
111 VGA The VGA console has been enabled.
112 VT Virtual terminal support is enabled.
113 WDT Watchdog support is enabled.
114 XT IBM PC/XT MFM hard disk support is enabled.
115 X86-32 X86-32, aka i386 architecture is enabled.
116 X86-64 X86-64 architecture is enabled.
117 More X86-64 boot options can be found in
118 Documentation/x86/x86_64/boot-options.txt .
119 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
120 XEN Xen support is enabled
122 In addition, the following text indicates that the option:
124 BUGS= Relates to possible processor bugs on the said processor.
125 KNL Is a kernel start-up parameter.
126 BOOT Is a boot loader parameter.
128 Parameters denoted with BOOT are actually interpreted by the boot
129 loader, and have no meaning to the kernel directly.
130 Do not modify the syntax of boot loader parameters without extreme
131 need or coordination with <Documentation/x86/boot.txt>.
133 There are also arch-specific kernel-parameters not documented here.
134 See for example <Documentation/x86/x86_64/boot-options.txt>.
136 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
137 a trailing = on the name of any parameter states that that parameter will
138 be entered as an environment variable, whereas its absence indicates that
139 it will appear as a kernel argument readable via /proc/cmdline by programs
140 running once the system is up.
142 The number of kernel parameters is not limited, but the length of the
143 complete command line (parameters including spaces etc.) is limited to
144 a fixed number of characters. This limit depends on the architecture
145 and is between 256 and 4096 characters. It is defined in the file
146 ./include/asm/setup.h as COMMAND_LINE_SIZE.
148 Finally, the [KMG] suffix is commonly described after a number of kernel
149 parameter values. These 'K', 'M', and 'G' letters represent the _binary_
150 multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
151 bytes respectively. Such letter suffixes can also be entirely omitted.
155 Advanced Configuration and Power Interface
156 Format: { force | off | strict | noirq | rsdt }
157 force -- enable ACPI if default was off
158 off -- disable ACPI if default was on
159 noirq -- do not use ACPI for IRQ routing
160 strict -- Be less tolerant of platforms that are not
161 strictly ACPI specification compliant.
162 rsdt -- prefer RSDT over (default) XSDT
163 copy_dsdt -- copy DSDT to memory
165 See also Documentation/power/pm.txt, pci=noacpi
167 acpi_apic_instance= [ACPI, IOAPIC]
169 2: use 2nd APIC table, if available
170 1,0: use 1st APIC table
173 acpi_backlight= [HW,ACPI]
174 acpi_backlight=vendor
176 If set to vendor, prefer vendor specific driver
177 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
178 of the ACPI video.ko driver.
180 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
181 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
183 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
184 debug output. Bits in debug_layer correspond to a
185 _COMPONENT in an ACPI source file, e.g.,
186 #define _COMPONENT ACPI_PCI_COMPONENT
187 Bits in debug_level correspond to a level in
188 ACPI_DEBUG_PRINT statements, e.g.,
189 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
190 The debug_level mask defaults to "info". See
191 Documentation/acpi/debug.txt for more information about
192 debug layers and levels.
194 Enable processor driver info messages:
195 acpi.debug_layer=0x20000000
196 Enable PCI/PCI interrupt routing info messages:
197 acpi.debug_layer=0x400000
198 Enable AML "Debug" output, i.e., stores to the Debug
199 object while interpreting AML:
200 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
201 Enable all messages related to ACPI hardware:
202 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
204 Some values produce so much output that the system is
205 unusable. The "log_buf_len" parameter may be useful
206 if you need to capture more output.
208 acpi_irq_balance [HW,ACPI]
209 ACPI will balance active IRQs
212 acpi_irq_nobalance [HW,ACPI]
213 ACPI will not move active IRQs (default)
216 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
217 Format: <irq>,<irq>...
219 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
221 Format: <irq>,<irq>...
223 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
225 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
226 Format: To spoof as Windows 98: ="Microsoft Windows"
228 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
229 acpi_osi="string1" # add string1 -- only one string
230 acpi_osi="!string2" # remove built-in string2
231 acpi_osi= # disable all strings
234 Override the pmtimer bug detection: force the kernel
235 to assume that this machine's pmtimer latches its value
236 and always returns good values.
238 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
239 Format: { level | edge | high | low }
241 acpi_serialize [HW,ACPI] force serialization of AML methods
243 acpi_skip_timer_override [HW,ACPI]
244 Recognize and ignore IRQ0/pin2 Interrupt Override.
245 For broken nForce2 BIOS resulting in XT-PIC timer.
247 acpi_sleep= [HW,ACPI] Sleep options
248 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
249 old_ordering, nonvs, sci_force_enable }
250 See Documentation/power/video.txt for information on
252 s3_beep is for debugging; it makes the PC's speaker beep
253 as soon as the kernel's real-mode entry point is called.
254 s4_nohwsig prevents ACPI hardware signature from being
255 used during resume from hibernation.
256 old_ordering causes the ACPI 1.0 ordering of the _PTS
257 control method, with respect to putting devices into
258 low power states, to be enforced (the ACPI 2.0 ordering
259 of _PTS is used by default).
260 nonvs prevents the kernel from saving/restoring the
261 ACPI NVS memory during suspend/hibernation and resume.
262 sci_force_enable causes the kernel to set SCI_EN directly
263 on resume from S1/S3 (which is against the ACPI spec,
264 but some broken systems don't work without it).
266 acpi_use_timer_override [HW,ACPI]
267 Use timer override. For some broken Nvidia NF5 boards
268 that require a timer override, but don't have HPET
270 acpi_enforce_resources= [ACPI]
271 { strict | lax | no }
272 Check for resource conflicts between native drivers
273 and ACPI OperationRegions (SystemIO and SystemMemory
274 only). IO ports and memory declared in ACPI might be
275 used by the ACPI subsystem in arbitrary AML code and
276 can interfere with legacy drivers.
277 strict (default): access to resources claimed by ACPI
278 is denied; legacy drivers trying to access reserved
279 resources will fail to bind to device using them.
280 lax: access to resources claimed by ACPI is allowed;
281 legacy drivers trying to access reserved resources
282 will bind successfully but a warning message is logged.
283 no: ACPI OperationRegions are not marked as reserved,
284 no further checks are performed.
286 add_efi_memmap [EFI; X86] Include EFI memory map in
287 kernel's map of available physical RAM.
290 { off | try_unsupported }
291 off: disable AGP support
292 try_unsupported: try to drive unsupported chipsets
293 (may crash computer or cause data corruption)
296 See Documentation/sound/alsa/alsa-parameters.txt
299 Allow the default userspace alignment fault handler
300 behaviour to be specified. Bit 0 enables warnings,
301 bit 1 enables fixups, and bit 2 sends a segfault.
303 amd_iommu= [HW,X86-84]
304 Pass parameters to the AMD IOMMU driver in the system.
306 fullflush - enable flushing of IO/TLB entries when
307 they are unmapped. Otherwise they are
308 flushed before they will be reused, which
310 off - do not initialize any AMD IOMMU found in
313 amijoy.map= [HW,JOY] Amiga joystick support
314 Map of devices attached to JOY0DAT and JOY1DAT
316 See also Documentation/kernel/input/joystick.txt
318 analog.map= [HW,JOY] Analog joystick and gamepad support
319 Specifies type or capabilities of an analog joystick
320 connected to one of 16 gameports
321 Format: <type1>,<type2>,..<type16>
324 Power management functions (SPARCstation-4/5 + deriv.)
326 Disable APC CPU standby support. SPARCstation-Fox does
327 not play well with APC CPU idle - disable it if you have
328 APC and your system crashes randomly.
330 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
331 Change the output verbosity whilst booting
332 Format: { quiet (default) | verbose | debug }
333 Change the amount of debugging information output
334 when initialising the APIC and IO-APIC components.
337 See Documentation/networking/ipv6.txt.
339 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
340 Limit apic dumping. The parameter defines the maximal
341 number of local apics being dumped. Also it is possible
342 to set it to "all" by meaning -- no limit here.
343 Format: { 1 (default) | 2 | ... | all }.
344 The parameter valid if only apic=debug or
345 apic=verbose is specified.
346 Example: apic=debug show_lapic=all
348 apm= [APM] Advanced Power Management
349 See header of arch/x86/kernel/apm_32.c.
351 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
352 Format: <io>,<irq>,<nodeID>
356 atarimouse= [HW,MOUSE] Atari Mouse
358 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
359 EzKey and similar keyboards
361 atkbd.reset= [HW] Reset keyboard during initialization
363 atkbd.set= [HW] Select keyboard code set
364 Format: <int> (2 = AT (default), 3 = PS/2)
366 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
369 atkbd.softraw= [HW] Choose between synthetic and real raw mode
370 Format: <bool> (0 = real, 1 = synthetic (default))
372 atkbd.softrepeat= [HW]
373 Use software keyboard repeat
377 baycom_epp= [HW,AX25]
380 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
382 See header of drivers/net/hamradio/baycom_par.c.
384 baycom_ser_fdx= [HW,AX25]
385 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
386 Format: <io>,<irq>,<mode>[,<baud>]
387 See header of drivers/net/hamradio/baycom_ser_fdx.c.
389 baycom_ser_hdx= [HW,AX25]
390 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
391 Format: <io>,<irq>,<mode>
392 See header of drivers/net/hamradio/baycom_ser_hdx.c.
394 boot_delay= Milliseconds to delay each printk during boot.
395 Values larger than 10 seconds (10000) are changed to
399 bootmem_debug [KNL] Enable bootmem allocator debug messages.
401 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
402 bttv.radio= Most important insmod options are available as
404 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
405 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
407 bulk_remove=off [PPC] This parameter disables the use of the pSeries
408 firmware feature for flushing multiple hpte entries
411 c101= [NET] Moxa C101 synchronous serial card
413 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
414 Sometimes CPU hardware bugs make them report the cache
415 size incorrectly. The kernel will attempt work arounds
416 to fix known problems, but for some CPUs it is not
417 possible to determine what the correct size should be.
418 This option provides an override for these situations.
421 [SECURITY] Disable capabilities. This would normally
422 be used only if an alternative security model is to be
423 configured. Potentially dangerous and should only be
424 used if you are entirely sure of the consequences.
426 ccw_timeout_log [S390]
427 See Documentation/s390/CommonIO for details.
429 cgroup_disable= [KNL] Disable a particular controller
430 Format: {name of the controller(s) to disable}
431 {Currently supported controllers - "memory"}
433 checkreqprot [SELINUX] Set initial checkreqprot flag value.
434 Format: { "0" | "1" }
435 See security/selinux/Kconfig help text.
436 0 -- check protection applied by kernel (includes
437 any implied execute protection).
438 1 -- check protection requested by application.
439 Default value is set via a kernel config option.
440 Value can be changed at runtime via
441 /selinux/checkreqprot.
444 See Documentation/s390/CommonIO for details.
446 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
448 Forces specified clocksource (if available) to be used
449 when calculating gettimeofday(). If specified
450 clocksource is not available, it defaults to PIT.
451 Format: { pit | tsc | cyclone | pmtmr }
453 clocksource= Override the default clocksource
455 Override the default clocksource and use the clocksource
456 with the name specified.
457 Some clocksource names to choose from, depending on
459 [all] jiffies (this is the base, fallback clocksource)
461 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
462 pxa_timer,timer3,32k_counter,timer0_1
464 [X86-32] pit,hpet,tsc;
465 scx200_hrt on Geode; cyclone on IBM x440
473 clearcpuid=BITNUM [X86]
474 Disable CPUID feature X for the kernel. See
475 arch/x86/include/asm/cpufeature.h for the valid bit
476 numbers. Note the Linux specific bits are not necessarily
477 stable over kernel options, but the vendor specific
479 Also note that user programs calling CPUID directly
480 or using the feature without checking anything
481 will still see it. This just prevents it from
482 being used by the kernel or shown in /proc/cpuinfo.
483 Also note the kernel might malfunction if you disable
486 cmo_free_hint= [PPC] Format: { yes | no }
487 Specify whether pages are marked as being inactive
488 when they are freed. This is used in CMO environments
489 to determine OS memory pressure for page stealing by
493 code_bytes [X86] How many bytes of object code to print
498 com20020= [HW,NET] ARCnet - COM20020 chipset
500 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
502 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
506 ARCnet - COM90xx chipset (memory-mapped buffers)
507 Format: <io>[,<irq>[,<memstart>]]
509 condev= [HW,S390] console device
512 console= [KNL] Output console device and options.
514 tty<n> Use the virtual console device <n>.
518 Use the specified serial port. The options are of
519 the form "bbbbpnf", where "bbbb" is the baud rate,
520 "p" is parity ("n", "o", or "e"), "n" is number of
521 bits, and "f" is flow control ("r" for RTS or
522 omit it). Default is "9600n8".
524 See Documentation/serial-console.txt for more
526 Documentation/networking/netconsole.txt for an
529 uart[8250],io,<addr>[,options]
530 uart[8250],mmio,<addr>[,options]
531 Start an early, polled-mode console on the 8250/16550
532 UART at the specified I/O port or MMIO address,
533 switching to the matching ttyS device later. The
534 options are the same as for ttyS, above.
536 If the device connected to the port is not a TTY but a braille
537 device, prepend "brl," before the device type, for instance
539 For now, only VisioBraille is supported.
541 consoleblank= [KNL] The console blank (screen saver) timeout in
542 seconds. Defaults to 10*60 = 10mins. A value of 0
543 disables the blank timer.
546 [KNL] Change the default value for
547 /proc/<pid>/coredump_filter.
548 See also Documentation/filesystems/proc.txt.
550 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
552 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
554 crashkernel=size[KMG][@offset[KMG]]
555 [KNL] Using kexec, Linux can switch to a 'crash kernel'
556 upon panic. This parameter reserves the physical
557 memory region [offset, offset + size] for that kernel
558 image. If '@offset' is omitted, then a suitable offset
559 is selected automatically. Check
560 Documentation/kdump/kdump.txt for further details.
562 crashkernel=range1:size1[,range2:size2,...][@offset]
563 [KNL] Same as above, but depends on the memory
564 in the running system. The syntax of range is
565 start-[end] where start and end are both
566 a memory unit (amount[KMG]). See also
567 Documentation/kdump/kdump.txt for an example.
572 cs89x0_media= [HW,NET]
573 Format: { rj45 | aui | bnc }
576 See header of drivers/s390/block/dasd_devmap.c.
578 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
579 (one device per port)
580 Format: <port#>,<type>
581 See also Documentation/input/joystick-parport.txt
583 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
584 time. See Documentation/dynamic-debug-howto.txt for
587 debug [KNL] Enable kernel debugging (events log level).
590 [KNL] verbose self-tests
592 Print debugging info while doing the locking API
594 We default to 0 (no extra messages), setting it to
595 1 will print _a lot_ more information - normally
596 only useful to kernel developers.
598 debug_objects [KNL] Enable object debugging
601 [KNL] Disable object debugging
603 debugpat [X86] Enable PAT debugging
605 decnet.addr= [HW,NET]
606 Format: <area>[,<node>]
607 See also Documentation/networking/decnet.txt.
610 [same as hugepagesz=] The size of the default
611 HugeTLB page size. This is the size represented by
612 the legacy /proc/ hugepages APIs, used for SHM, and
613 default size when mounting hugetlbfs filesystems.
614 Defaults to the default architecture's huge page size
618 Set number of hash buckets for dentry cache.
621 IO parameters + enable/disable command.
623 digiepca= [HW,SERIAL]
624 See drivers/char/README.epca and
625 Documentation/serial/digiepca.txt.
628 See Documentation/networking/ipv6.txt.
630 disable_ddw [PPC/PSERIES]
631 Disable Dynamic DMA Window support. Use this if
632 to workaround buggy firmware.
635 See Documentation/networking/ipv6.txt.
637 disable_mtrr_cleanup [X86]
638 The kernel tries to adjust MTRR layout from continuous
639 to discrete, to make X server driver able to add WB
640 entry later. This parameter disables that.
642 disable_mtrr_trim [X86, Intel and AMD only]
643 By default the kernel will trim any uncacheable
644 memory out of your available memory pool based on
645 MTRR settings. This parameter disables that behavior,
646 possibly causing your machine to run very slowly.
648 disable_timer_pin_1 [X86]
649 Disable PIN 1 of APIC timer
650 Can be useful to work around chipset bugs.
652 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
653 this option disables the debugging code at boot.
655 dma_debug_entries=<number>
656 This option allows to tune the number of preallocated
657 entries for DMA-API debugging code. One entry is
658 required per DMA-API allocation. Use this if the
659 DMA-API debugging code disables itself because the
660 architectural default is too low.
662 dma_debug_driver=<driver_name>
663 With this option the DMA-API debugging driver
664 filter feature can be enabled at boot time. Just
665 pass the driver to filter for as the parameter.
666 The filter can be disabled or changed to another
667 driver later using sysfs.
671 earlycon= [KNL] Output early console device and options.
672 uart[8250],io,<addr>[,options]
673 uart[8250],mmio,<addr>[,options]
674 uart[8250],mmio32,<addr>[,options]
675 Start an early, polled-mode console on the 8250/16550
676 UART at the specified I/O port or MMIO address.
677 MMIO inter-register address stride is either 8bit (mmio)
679 The options are the same as for ttyS, above.
681 earlyprintk= [X86,SH,BLACKFIN]
683 earlyprintk=serial[,ttySn[,baudrate]]
684 earlyprintk=ttySn[,baudrate]
685 earlyprintk=dbgp[debugController#]
687 Append ",keep" to not disable it when the real console
690 Only vga or serial or usb debug port at a time.
692 Currently only ttyS0 and ttyS1 are supported.
694 Interaction with the standard serial driver is not
697 The VGA output is eventually overwritten by the real
700 ekgdboc= [X86,KGDB] Allow early kernel console debugging
703 This is designed to be used in conjunction with
704 the boot argument: earlyprintk=vga
707 Format: {"off" | "on" | "skip[mbr]"}
709 eisa_irq_edge= [PARISC,HW]
710 See header of drivers/parisc/eisa.c.
713 See comment before function elanfreq_setup() in
714 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
717 Format: {"cfq" | "deadline" | "noop"}
718 See Documentation/block/as-iosched.txt and
719 Documentation/block/deadline-iosched.txt for details.
721 elfcorehdr= [IA64,PPC,SH,X86]
722 Specifies physical address of start of kernel core
723 image elf header. Generally kexec loader will
724 pass this option to capture kernel.
725 See Documentation/kdump/kdump.txt for details.
727 enable_mtrr_cleanup [X86]
728 The kernel tries to adjust MTRR layout from continuous
729 to discrete, to make X server driver able to add WB
730 entry later. This parameter enables that.
732 enable_timer_pin_1 [X86]
733 Enable PIN 1 of APIC timer
734 Can be useful to work around chipset bugs
735 (in particular on some ATI chipsets).
736 The kernel tries to set a reasonable default.
738 enforcing [SELINUX] Set initial enforcing status.
740 See security/selinux/Kconfig help text.
741 0 -- permissive (log only, no denials).
742 1 -- enforcing (deny and log).
744 Value can be changed at runtime via /selinux/enforce.
747 Disable Error Record Serialization Table (ERST)
750 ether= [HW,NET] Ethernet cards parameters
751 This option is obsoleted by the "netdev=" option, which
752 has equivalent usage. See its documentation for details.
756 Permit 'security.evm' to be updated regardless of
757 current integrity status.
761 fail_make_request=[KNL]
762 General fault injection mechanism.
763 Format: <interval>,<probability>,<space>,<times>
764 See also /Documentation/fault-injection/.
767 See Documentation/blockdev/floppy.txt.
769 force_pal_cache_flush
770 [IA-64] Avoid check_sal_cache_flush which may hang on
771 buggy SAL_CACHE_FLUSH implementations. Using this
772 parameter will force ia64_sal_cache_flush to call
773 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
776 [FTRACE] will set and start the specified tracer
777 as early as possible in order to facilitate early
780 ftrace_dump_on_oops[=orig_cpu]
781 [FTRACE] will dump the trace buffers on oops.
782 If no parameter is passed, ftrace will dump
783 buffers of all CPUs, but if you pass orig_cpu, it will
784 dump only the buffer of the CPU that triggered the
787 ftrace_filter=[function-list]
788 [FTRACE] Limit the functions traced by the function
789 tracer at boot up. function-list is a comma separated
790 list of functions. This list can be changed at run
791 time by the set_ftrace_filter file in the debugfs
794 ftrace_notrace=[function-list]
795 [FTRACE] Do not trace the functions specified in
796 function-list. This list can be changed at run time
797 by the set_ftrace_notrace file in the debugfs
800 ftrace_graph_filter=[function-list]
801 [FTRACE] Limit the top level callers functions traced
802 by the function graph tracer at boot up.
803 function-list is a comma separated list of functions
804 that can be changed at run time by the
805 set_graph_function file in the debugfs tracing directory.
808 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
809 support via parallel port (up to 5 devices per port)
810 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
811 See also Documentation/input/joystick-parport.txt
815 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
819 gcov_persist= [GCOV] When non-zero (default), profiling data for
820 kernel modules is saved and remains accessible via
821 debugfs, even when the module is unloaded/reloaded.
822 When zero, profiling data is discarded and associated
823 debugfs files are removed at module unload time.
825 gpt [EFI] Forces disk with valid GPT signature but
826 invalid Protective MBR to be treated as GPT.
828 hashdist= [KNL,NUMA] Large hashes allocated during boot
829 are distributed across NUMA nodes. Defaults on
830 for 64bit NUMA, off otherwise.
831 Format: 0 | 1 (for off | on)
833 hcl= [IA-64] SGI's Hardware Graph compatibility layer
835 hd= [EIDE] (E)IDE hard drive subsystem geometry
836 Format: <cyl>,<head>,<sect>
839 Disable Hardware Error Source Table (HEST) support;
840 corresponding firmware-first mode error processing
841 logic will be disabled.
843 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
844 size of <nn>. This works even on boxes that have no
845 highmem otherwise. This also works to reduce highmem
846 size on bigger boxes.
848 highres= [KNL] Enable/disable high resolution timer mode.
849 Valid parameters: "on", "off"
853 See Documentation/isdn/README.HiSax.
857 hpet= [X86-32,HPET] option to control HPET usage
858 Format: { enable (default) | disable | force |
860 disable: disable HPET and use PIT instead
861 force: allow force enabled of undocumented chips (ICH4,
863 verbose: show contents of HPET registers during setup
865 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
866 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
867 On x86-64 and powerpc, this option can be specified
868 multiple times interleaved with hugepages= to reserve
869 huge pages of different sizes. Valid pages sizes on
870 x86-64 are 2M (when the CPU supports "pse") and 1G
871 (when the CPU supports the "pdpe1gb" cpuinfo flag)
872 Note that 1GB pages can only be allocated at boot time
873 using hugepages= and not freed afterwards.
875 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
876 terminal devices. Valid values: 0..8
877 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
878 If specified, z/VM IUCV HVC accepts connections
879 from listed z/VM user IDs only.
882 Do not unregister boot console at start. This is only
883 useful for debugging when something happens in the window
884 between unregistering the boot console and initializing
887 i2c_bus= [HW] Override the default board specific I2C bus speed
888 or register an additional I2C bus that is not
889 registered from board initialization code.
893 i8042.debug [HW] Toggle i8042 debug mode
894 i8042.direct [HW] Put keyboard port into non-translated mode
895 i8042.dumbkbd [HW] Pretend that controller can only read data from
896 keyboard and cannot control its state
897 (Don't attempt to blink the leds)
898 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
899 i8042.nokbd [HW] Don't check/create keyboard port
900 i8042.noloop [HW] Disable the AUX Loopback command while probing
902 i8042.nomux [HW] Don't check presence of an active multiplexing
904 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
906 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
907 i8042.reset [HW] Reset the controller during init and cleanup
908 i8042.unlock [HW] Unlock (ignore) the keylock
912 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
913 indicates that the driver is running on unsupported
915 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
916 does not match list of supported models.
918 [HW] Report power status in /proc/i8k
919 (disabled by default)
920 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
924 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
926 ide-core.nodma= [HW] (E)IDE subsystem
927 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
928 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
929 .cdrom .chs .ignore_cable are additional options
930 See Documentation/ide/ide.txt.
932 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
933 Claim all unknown PCI IDE storage controllers.
936 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
937 Poll forces a polling idle loop that can slightly
938 improve the performance of waking up a idle CPU, but
939 will use a lot of power and make the system run hot.
941 idle=mwait: On systems which support MONITOR/MWAIT but
942 the kernel chose to not use it because it doesn't save
943 as much power as a normal idle loop, use the
944 MONITOR/MWAIT idle loop anyways. Performance should be
945 the same as idle=poll.
946 idle=halt: Halt is forced to be used for CPU idle.
947 In such case C2/C3 won't be used again.
948 idle=nomwait: Disable mwait for CPU C-states
950 ignore_loglevel [KNL]
951 Ignore loglevel setting - this will print /all/
952 kernel messages to the console. Useful for debugging.
955 Set number of hash buckets for inode cache.
958 Format: { "0" | "1" }
959 0 -- integrity auditing messages. (Default)
960 1 -- enable informational integrity auditing messages.
963 Format: { "sha1" | "md5" }
967 Load a policy which meets the needs of the Trusted
968 Computing Base. This means IMA will measure all
969 programs exec'd, files mmap'd for exec, and all files
970 opened for read by uid=0.
974 Run specified binary instead of /sbin/init as init
977 initcall_debug [KNL] Trace initcalls as they are executed. Useful
978 for working out where the kernel is dying during
981 initrd= [BOOT] Specify the location of the initial ramdisk
983 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
986 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
988 Enable intel iommu driver.
990 Disable intel iommu driver.
991 igfx_off [Default Off]
992 By default, gfx is mapped as normal device. If a gfx
993 device has a dedicated DMAR unit, the DMAR unit is
994 bypassed by not enabling DMAR with this option. In
995 this case, gfx device will use physical address for
998 With this option iommu will not optimize to look
999 for io virtual address below 32 bit forcing dual
1000 address cycle on pci bus for cards supporting greater
1001 than 32 bit addressing. The default is to look
1002 for translation below 32 bit and if not available
1003 then look in the higher range.
1004 strict [Default Off]
1005 With this option on every unmap_single operation will
1006 result in a hardware IOTLB flush operation as opposed
1007 to batching them for performance.
1008 sp_off [Default Off]
1009 By default, super page will be supported if Intel IOMMU
1010 has the capability. With this option, super page will
1012 intremap= [X86-64, Intel-IOMMU]
1013 Format: { on (default) | off | nosid }
1014 on enable Interrupt Remapping (default)
1015 off disable Interrupt Remapping
1016 nosid disable Source ID checking
1020 iomem= Disable strict checking of access to MMIO memory
1021 strict regions from userspace.
1037 io7= [HW] IO7 for Marvel based alpha systems
1038 See comment before marvel_specify_io7 in
1039 arch/alpha/kernel/core_marvel.c.
1041 io_delay= [X86] I/O delay method
1043 Standard port 0x80 based delay
1045 Alternate port 0xed based delay (needed on some systems)
1047 Simple two microseconds delay
1052 See Documentation/filesystems/nfs/nfsroot.txt.
1054 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1055 See comment before ip2_setup() in
1056 drivers/char/ip2/ip2base.c.
1059 When an interrupt is not handled search all handlers
1060 for it. Intended to get systems with badly broken
1064 When an interrupt is not handled search all handlers
1065 for it. Also check all handlers each timer
1066 interrupt. Intended to get systems with badly broken
1070 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1072 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1074 <cpu number>,...,<cpu number>
1076 <cpu number>-<cpu number>
1077 (must be a positive range in ascending order)
1079 <cpu number>,...,<cpu number>-<cpu number>
1081 This option can be used to specify one or more CPUs
1082 to isolate from the general SMP balancing and scheduling
1083 algorithms. You can move a process onto or off an
1084 "isolated" CPU via the CPU affinity syscalls or cpuset.
1085 <cpu number> begins at 0 and the maximum value is
1086 "number of CPUs in system - 1".
1088 This option is the preferred way to isolate CPUs. The
1089 alternative -- manually setting the CPU mask of all
1090 tasks in the system -- can cause problems and
1091 suboptimal load balancer performance.
1095 js= [HW,JOY] Analog joystick
1096 See Documentation/input/joystick.txt.
1100 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1101 specifies the amount of memory usable by the kernel
1102 for non-movable allocations. The requested amount is
1103 spread evenly throughout all nodes in the system. The
1104 remaining memory in each node is used for Movable
1105 pages. In the event, a node is too small to have both
1106 kernelcore and Movable pages, kernelcore pages will
1107 take priority and other nodes will have a larger number
1108 of kernelcore pages. The Movable zone is used for the
1109 allocation of pages that may be reclaimed or moved
1110 by the page migration subsystem. This means that
1111 HugeTLB pages may not be allocated from this zone.
1112 Note that allocations like PTEs-from-HighMem still
1113 use the HighMem zone if it exists, and the Normal
1114 zone if it does not.
1116 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1117 Format: <Controller#>[,poll interval]
1118 The controller # is the number of the ehci usb debug
1119 port as it is probed via PCI. The poll interval is
1120 optional and is the number seconds in between
1121 each poll cycle to the debug port in case you need
1122 the functionality for interrupting the kernel with
1123 gdb or control-c on the dbgp connection. When
1124 not using this parameter you use sysrq-g to break into
1125 the kernel debugger.
1127 kgdboc= [KGDB,HW] kgdb over consoles.
1128 Requires a tty driver that supports console polling,
1129 or a supported polling keyboard driver (non-usb).
1130 Serial only format: <serial_device>[,baud]
1131 keyboard only format: kbd
1132 keyboard and serial format: kbd,<serial_device>[,baud]
1133 Optional Kernel mode setting:
1134 kms, kbd format: kms,kbd
1135 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1137 kgdbwait [KGDB] Stop kernel execution and enter the
1138 kernel debugger at the earliest opportunity.
1140 kmac= [MIPS] korina ethernet MAC address.
1141 Configure the RouterBoard 532 series on-chip
1142 Ethernet adapter MAC address.
1144 kmemleak= [KNL] Boot-time kmemleak enable/disable
1145 Valid arguments: on, off
1148 kstack=N [X86] Print N words from the kernel stack
1151 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1152 Default is 0 (don't ignore, but inject #GP)
1154 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1155 Default is 1 (enabled)
1157 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1161 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1162 Default is 1 (enabled)
1164 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1166 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1168 kvm-intel.bypass_guest_pf=
1169 [KVM,Intel] Disables bypassing of guest page faults
1170 on Intel chips. Default is 1 (enabled)
1172 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1173 (virtualized MMU) support on capable Intel chips.
1174 Default is 1 (enabled)
1176 kvm-intel.emulate_invalid_guest_state=
1177 [KVM,Intel] Enable emulation of invalid guest states
1178 Default is 0 (disabled)
1180 kvm-intel.flexpriority=
1181 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1182 Default is 1 (enabled)
1184 kvm-intel.unrestricted_guest=
1185 [KVM,Intel] Disable unrestricted guest feature
1186 (virtualized real and unpaged mode) on capable
1187 Intel chips. Default is 1 (enabled)
1189 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1190 feature (tagged TLBs) on capable Intel chips.
1191 Default is 1 (enabled)
1197 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1200 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1203 libata.dma= [LIBATA] DMA control
1204 libata.dma=0 Disable all PATA and SATA DMA
1205 libata.dma=1 PATA and SATA Disk DMA only
1206 libata.dma=2 ATAPI (CDROM) DMA only
1207 libata.dma=4 Compact Flash DMA only
1208 Combinations also work, so libata.dma=3 enables DMA
1209 for disks and CDROMs, but not CFs.
1211 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1212 libata.ignore_hpa=0 keep BIOS limits (default)
1213 libata.ignore_hpa=1 ignore limits, using full disk
1215 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1219 libata.force= [LIBATA] Force configurations. The format is comma
1220 separated list of "[ID:]VAL" where ID is
1221 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1222 matching port, link or device. Basically, it matches
1223 the ATA ID string printed on console by libata. If
1224 the whole ID part is omitted, the last PORT and DEVICE
1225 values are used. If ID hasn't been specified yet, the
1226 configuration applies to all ports, links and devices.
1228 If only DEVICE is omitted, the parameter applies to
1229 the port and all links and devices behind it. DEVICE
1230 number of 0 either selects the first device or the
1231 first fan-out link behind PMP device. It does not
1232 select the host link. DEVICE number of 15 selects the
1233 host link and device attached to it.
1235 The VAL specifies the configuration to force. As long
1236 as there's no ambiguity shortcut notation is allowed.
1237 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1238 The following configurations can be forced.
1240 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1241 Any ID with matching PORT is used.
1243 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1245 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1246 udma[/][16,25,33,44,66,100,133] notation is also
1249 * [no]ncq: Turn on or off NCQ.
1251 * nohrst, nosrst, norst: suppress hard, soft
1254 * dump_id: dump IDENTIFY data.
1256 If there are multiple matching configurations changing
1257 the same attribute, the last one is used.
1259 memblock=debug [KNL] Enable memblock debug messages.
1261 load_ramdisk= [RAM] List of ramdisks to load from floppy
1262 See Documentation/blockdev/ramdisk.txt.
1264 lockd.nlm_grace_period=P [NFS] Assign grace period.
1267 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1270 lockd.nlm_timeout=T [NFS] Assign timeout value.
1273 lockd.nlm_udpport=M [NFS] Assign UDP port.
1276 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1279 loglevel= All Kernel Messages with a loglevel smaller than the
1280 console loglevel will be printed to the console. It can
1281 also be changed with klogd or other programs. The
1282 loglevels are defined as follows:
1284 0 (KERN_EMERG) system is unusable
1285 1 (KERN_ALERT) action must be taken immediately
1286 2 (KERN_CRIT) critical conditions
1287 3 (KERN_ERR) error conditions
1288 4 (KERN_WARNING) warning conditions
1289 5 (KERN_NOTICE) normal but significant condition
1290 6 (KERN_INFO) informational
1291 7 (KERN_DEBUG) debug-level messages
1293 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1294 in bytes. n must be a power of two. The default
1295 size is set in the kernel config file.
1297 logo.nologo [FB] Disables display of the built-in Linux logo.
1298 This may be used to provide more screen space for
1299 kernel log messages and is useful when debugging
1300 kernel boot problems.
1302 lp=0 [LP] Specify parallel ports to use, e.g,
1303 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1304 lp=reset first parallel port). 'lp=0' disables the
1305 lp=auto printer driver. 'lp=reset' (which can be
1306 specified in addition to the ports) causes
1307 attached printers to be reset. Using
1308 lp=port1,port2,... specifies the parallel ports
1309 to associate lp devices with, starting with
1310 lp0. A port specification may be 'none' to skip
1311 that lp device, or a parport name such as
1312 'parport0'. Specifying 'lp=auto' instead of a
1313 port specification list means that device IDs
1314 from each port should be examined, to see if
1315 an IEEE 1284-compliant printer is attached; if
1316 so, the driver will manage that printer.
1317 See also header of drivers/char/lp.c.
1320 Sets loops_per_jiffy to given constant, thus avoiding
1321 time-consuming boot-time autodetection (up to 250 ms per
1322 CPU). 0 enables autodetection (default). To determine
1323 the correct value for your kernel, boot with normal
1324 autodetection and see what value is printed. Note that
1325 on SMP systems the preset will be applied to all CPUs,
1326 which is likely to cause problems if your CPUs need
1327 significantly divergent settings. An incorrect value
1328 will cause delays in the kernel to be wrong, leading to
1329 unpredictable I/O errors and other breakage. Although
1330 unlikely, in the extreme case this might damage your
1334 Format: <io>,<irq>,<dma>
1336 machvec= [IA64] Force the use of a particular machine-vector
1337 (machvec) in a generic kernel.
1338 Example: machvec=hpzx1_swiotlb
1340 machtype= [Loongson] Share the same kernel image file between different
1342 Example: machtype=lemote-yeeloong-2f-7inch
1344 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1345 than or equal to this physical address is ignored.
1347 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1348 should make use of. maxcpus=n : n >= 0 limits the
1349 kernel to using 'n' processors. n=0 is a special case,
1350 it is equivalent to "nosmp", which also disables
1353 max_loop= [LOOP] Maximum number of loopback devices that can
1359 mce [X86-32] Machine Check Exception
1361 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1363 md= [HW] RAID subsystems devices and level
1364 See Documentation/md.txt.
1367 Format: <first>,<last>
1368 Specifies range of consoles to be captured by the MDA.
1370 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1371 Amount of memory to be used when the kernel is not able
1372 to see the whole system memory or for test.
1373 [X86-32] Use together with memmap= to avoid physical
1374 address space collisions. Without memmap= PCI devices
1375 could be placed at addresses belonging to unused RAM.
1377 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1381 [KNL,SH] Allow user to override the default size for
1382 per-device physically contiguous DMA buffers.
1384 memmap=exactmap [KNL,X86] Enable setting of an exact
1385 E820 memory map, as specified by the user.
1386 Such memmap=exactmap lines can be constructed based on
1387 BIOS output or other requirements. See the memmap=nn@ss
1390 memmap=nn[KMG]@ss[KMG]
1391 [KNL] Force usage of a specific region of memory
1392 Region of memory to be used, from ss to ss+nn.
1394 memmap=nn[KMG]#ss[KMG]
1395 [KNL,ACPI] Mark specific memory as ACPI data.
1396 Region of memory to be used, from ss to ss+nn.
1398 memmap=nn[KMG]$ss[KMG]
1399 [KNL,ACPI] Mark specific memory as reserved.
1400 Region of memory to be used, from ss to ss+nn.
1401 Example: Exclude memory from 0x18690000-0x1869ffff
1402 memmap=64K$0x18690000
1404 memmap=0x10000$0x18690000
1406 memory_corruption_check=0/1 [X86]
1407 Some BIOSes seem to corrupt the first 64k of
1408 memory when doing things like suspend/resume.
1409 Setting this option will scan the memory
1410 looking for corruption. Enabling this will
1411 both detect corruption and prevent the kernel
1412 from using the memory being corrupted.
1413 However, its intended as a diagnostic tool; if
1414 repeatable BIOS-originated corruption always
1415 affects the same memory, you can use memmap=
1416 to prevent the kernel from using that memory.
1418 memory_corruption_check_size=size [X86]
1419 By default it checks for corruption in the low
1420 64k, making this memory unavailable for normal
1421 use. Use this parameter to scan for
1422 corruption in more or less memory.
1424 memory_corruption_check_period=seconds [X86]
1425 By default it checks for corruption every 60
1426 seconds. Use this parameter to check at some
1427 other rate. 0 disables periodic checking.
1429 memtest= [KNL,X86] Enable memtest
1431 default : 0 <disable>
1432 Specifies the number of memtest passes to be
1433 performed. Each pass selects another test
1434 pattern from a given set of patterns. Memtest
1435 fills the memory with this pattern, validates
1436 memory contents and reserves bad memory
1437 regions that are detected.
1439 meye.*= [HW] Set MotionEye Camera parameters
1440 See Documentation/video4linux/meye.txt.
1442 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1443 Multi-Function General Purpose Timers on AMD Geode
1446 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1447 the BIOS has incorrectly applied a workaround. TinyBIOS
1448 version 0.98 is known to be affected, 0.99 fixes the
1449 problem by letting the user disable the workaround.
1453 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1454 physical address is ignored.
1456 mini2440= [ARM,HW,KNL]
1457 Format:[0..2][b][c][t]
1459 MINI2440 configuration specification:
1460 0 - The attached screen is the 3.5" TFT
1461 1 - The attached screen is the 7" TFT
1462 2 - The VGA Shield is attached (1024x768)
1463 Leaving out the screen size parameter will not load
1464 the TFT driver, and the framebuffer will be left
1466 b - Enable backlight. The TFT backlight pin will be
1467 linked to the kernel VESA blanking code and a GPIO
1468 LED. This parameter is not necessary when using the
1470 c - Enable the s3c camera interface.
1471 t - Reserved for enabling touchscreen support. The
1472 touchscreen support is not enabled in the mainstream
1473 kernel as of 2.6.30, a preliminary port can be found
1474 in the "bleeding edge" mini2440 support kernel at
1475 http://repo.or.cz/w/linux-2.6/mini2440.git
1478 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1479 parameter allows control of the logging verbosity for
1480 the additional memory initialisation checks. A value
1481 of 0 disables mminit logging and a level of 4 will
1482 log everything. Information is printed at KERN_DEBUG
1483 so loglevel=8 may also need to be specified.
1486 [MOUSE] Maximum time between finger touching and
1487 leaving touchpad surface for touch to be considered
1488 a tap and be reported as a left button click (for
1489 touchpads working in absolute mode only).
1491 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1492 reporting absolute coordinates, such as tablets
1493 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1494 reporting absolute coordinates, such as tablets
1496 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1497 is similar to kernelcore except it specifies the
1498 amount of memory used for migratable allocations.
1499 If both kernelcore and movablecore is specified,
1500 then kernelcore will be at *least* the specified
1501 value but may be more. If movablecore on its own
1502 is specified, the administrator must be careful
1503 that the amount of memory usable for all allocations
1506 MTD_Partition= [MTD]
1507 Format: <name>,<region-number>,<size>,<offset>
1509 MTD_Region= [MTD] Format:
1510 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1513 See drivers/mtd/cmdlinepart.c.
1515 multitce=off [PPC] This parameter disables the use of the pSeries
1516 firmware feature for updating multiple TCE entries
1519 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1521 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1523 boundary - index of last SLC block on Flex-OneNAND.
1524 The remaining blocks are configured as MLC blocks.
1525 lock - Configure if Flex-OneNAND boundary should be locked.
1526 Once locked, the boundary cannot be changed.
1527 1 indicates lock status, 0 indicates unlock status.
1530 ARM/S3C2412 JIVE boot control
1532 See arch/arm/mach-s3c2412/mach-jive.c
1534 mtouchusb.raw_coordinates=
1535 [HW] Make the MicroTouch USB driver use raw coordinates
1536 ('y', default) or cooked coordinates ('n')
1538 mtrr_chunk_size=nn[KMG] [X86]
1539 used for mtrr cleanup. It is largest continuous chunk
1540 that could hold holes aka. UC entries.
1542 mtrr_gran_size=nn[KMG] [X86]
1543 Used for mtrr cleanup. It is granularity of mtrr block.
1545 Large value could prevent small alignment from
1548 mtrr_spare_reg_nr=n [X86]
1550 Range: 0,7 : spare reg number
1552 Used for mtrr cleanup. It is spare mtrr entries number.
1553 Set to 2 or more if your graphical card needs more.
1555 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1557 netdev= [NET] Network devices parameters
1558 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1559 Note that mem_start is often overloaded to mean
1560 something different and driver-specific.
1561 This usage is only documented in each driver source
1565 [NETFILTER] Enable connection tracking flow accounting
1566 0 to disable accounting
1567 1 to enable accounting
1570 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1571 See Documentation/filesystems/nfs/nfsroot.txt.
1573 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1574 See Documentation/filesystems/nfs/nfsroot.txt.
1576 nfsrootdebug [NFS] enable nfsroot debugging messages.
1577 See Documentation/filesystems/nfs/nfsroot.txt.
1579 nfs.callback_tcpport=
1580 [NFS] set the TCP port on which the NFSv4 callback
1581 channel should listen.
1584 [NFS] sets the pathname to the program which is used
1585 to update the NFS client cache entries.
1587 nfs.cache_getent_timeout=
1588 [NFS] sets the timeout after which an attempt to
1589 update a cache entry is deemed to have failed.
1591 nfs.idmap_cache_timeout=
1592 [NFS] set the maximum lifetime for idmapper cache
1596 [NFS] enable 64-bit inode numbers.
1597 If zero, the NFS client will fake up a 32-bit inode
1598 number for the readdir() and stat() syscalls instead
1599 of returning the full 64-bit number.
1600 The default is to return 64-bit inode numbers.
1602 nfs.nfs4_disable_idmapping=
1603 [NFSv4] When set, this option disables the NFSv4
1604 idmapper on the client, but only if the mount
1605 is using the 'sec=sys' security flavour. This may
1606 make migration from legacy NFSv2/v3 systems easier
1607 provided that the server has the appropriate support.
1608 The default is to always enable NFSv4 idmapping.
1610 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1611 when a NMI is triggered.
1612 Format: [state][,regs][,debounce][,die]
1614 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1615 Format: [panic,][nopanic,][num]
1617 0 - turn nmi_watchdog off
1618 When panic is specified, panic when an NMI watchdog
1619 timeout occurs (or 'nopanic' to override the opposite
1621 This is useful when you use a panic=... timeout and
1622 need the box quickly up again.
1624 netpoll.carrier_timeout=
1625 [NET] Specifies amount of time (in seconds) that
1626 netpoll should wait for a carrier. By default netpoll
1629 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1630 emulation library even if a 387 maths coprocessor
1634 [HW] Never suspend the console
1635 Disable suspending of consoles during suspend and
1636 hibernate operations. Once disabled, debugging
1637 messages can reach various consoles while the rest
1638 of the system is being put to sleep (ie, while
1639 debugging driver suspend/resume hooks). This may
1640 not work reliably with all consoles, but is known
1641 to work with serial and VGA consoles.
1643 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1644 caches in the slab allocator. Saves per-node memory,
1645 but will impact performance.
1649 noapic [SMP,APIC] Tells the kernel to not make use of any
1650 IOAPICs that may be present in the system.
1652 noautogroup Disable scheduler automatic task group creation.
1654 nobats [PPC] Do not use BATs for mapping kernel lowmem
1655 on "Classic" PPC cores.
1659 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1661 nodelayacct [KNL] Disable per-task delay accounting
1663 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1665 nodsp [SH] Disable hardware DSP at boot time.
1667 noefi [X86] Disable EFI runtime services support.
1672 On X86-32 available only on PAE configured kernels.
1673 noexec=on: enable non-executable mappings (default)
1674 noexec=off: disable non-executable mappings
1677 Disable SMEP (Supervisor Mode Execution Protection)
1678 even if it is supported by processor.
1681 This affects only 32-bit executables.
1682 noexec32=on: enable non-executable mappings (default)
1683 read doesn't imply executable mappings
1684 noexec32=off: disable non-executable mappings
1685 read implies executable mappings
1687 nofpu [SH] Disable hardware FPU at boot time.
1689 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1690 register save and restore. The kernel will only save
1691 legacy floating-point registers on task switch.
1693 noxsave [BUGS=X86] Disables x86 extended register state save
1694 and restore using xsave. The kernel will fallback to
1695 enabling legacy floating-point and sse state.
1697 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1698 wfi(ARM) instruction doesn't work correctly and not to
1699 use it. This is also useful when using JTAG debugger.
1701 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1702 instruction doesn't work correctly and not to
1705 no_file_caps Tells the kernel not to honor file capabilities. The
1706 only way then for a file to be executed with privilege
1707 is to be setuid root or executed by root.
1709 nohalt [IA-64] Tells the kernel not to use the power saving
1710 function PAL_HALT_LIGHT when idle. This increases
1711 power-consumption. On the positive side, it reduces
1712 interrupt wake-up latency, which may improve performance
1713 in certain environments such as networked servers or
1716 nohz= [KNL] Boottime enable/disable dynamic ticks
1717 Valid arguments: on, off
1720 noiotrap [SH] Disables trapped I/O port accesses.
1722 noirqdebug [X86-32] Disables the code which attempts to detect and
1723 disable unhandled interrupt sources.
1725 no_timer_check [X86,APIC] Disables the code which tests for
1726 broken timer IRQ sources.
1728 noisapnp [ISAPNP] Disables ISA PnP code.
1730 noinitrd [RAM] Tells the kernel not to load any configured
1733 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1735 [Deprecated - use intremap=off]
1739 nojitter [IA64] Disables jitter checking for ITC timers.
1741 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1743 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1746 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1748 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1750 noltlbs [PPC] Do not use large page/tlb entries for kernel
1751 lowmem mapping on PPC40x.
1753 nomca [IA-64] Disable machine check abort handling
1755 nomce [X86-32] Machine Check Exception
1757 nomfgpt [X86-32] Disable Multi-Function General Purpose
1758 Timer usage (for AMD Geode machines).
1760 nopat [X86] Disable PAT (page attribute table extension of
1761 pagetables) support.
1763 norandmaps Don't use address space randomization. Equivalent to
1764 echo 0 > /proc/sys/kernel/randomize_va_space
1766 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1768 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1769 with UP alternatives
1771 noresidual [PPC] Don't use residual data on PReP machines.
1773 noresume [SWSUSP] Disables resume and restores original swap
1776 no-scroll [VGA] Disables scrollback.
1777 This is required for the Braillex ib80-piezo Braille
1778 reader made by F.H. Papenmeier (Germany).
1782 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1784 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1785 and disable the IO APIC. legacy for "maxcpus=0".
1787 nosoftlockup [KNL] Disable the soft-lockup detector.
1789 nosync [HW,M68K] Disables sync negotiation for all devices.
1791 notsc [BUGS=X86-32] Disable Time Stamp Counter
1793 nousb [USB] Disable the USB subsystem
1795 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1799 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1801 nptcg= [IA64] Override max number of concurrent global TLB
1802 purges which is reported from either PAL_VM_SUMMARY or
1805 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1806 could support. nr_cpus=n : n >= 1 limits the kernel to
1807 supporting 'n' processors. Later in runtime you can not
1808 use hotplug cpu feature to put more cpu back to online.
1809 just like you compile the kernel NR_CPUS=n
1811 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1813 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1814 one of ['zone', 'node', 'default'] can be specified
1815 This can be set from sysctl after boot.
1816 See Documentation/sysctl/vm.txt for details.
1818 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1819 See Documentation/debugging-via-ohci1394.txt for more
1822 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1823 Rather than timing out after 20 ms if an EC
1824 command is not properly ACKed, override the length
1825 of the timeout. We have interrupts disabled while
1826 waiting for the ACK, so if this is set too high
1827 interrupts *may* be lost!
1829 omap_mux= [OMAP] Override bootloader pin multiplexing.
1830 Format: <mux_mode0.mode_name=value>...
1831 For example, to override I2C bus2:
1832 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1834 oprofile.timer= [HW]
1835 Use timer interrupt instead of performance counters
1837 oprofile.cpu_type= Force an oprofile cpu type
1838 This might be useful if you have an older oprofile
1839 userland or if you want common events.
1840 Format: { arch_perfmon }
1841 arch_perfmon: [X86] Force use of architectural
1842 perfmon on Intel CPUs instead of the
1843 CPU specific event set.
1845 oops=panic Always panic on oopses. Default is to just kill the
1846 process, but there is a small probability of
1847 deadlocking the machine.
1848 This will also cause panics on machine check exceptions.
1849 Useful together with panic=30 to trigger a reboot.
1852 See Documentation/sound/oss/oss-parameters.txt
1854 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1855 seconds before rebooting
1858 parkbd.port= [HW] Parallel port number the keyboard adapter is
1859 connected to, default is 0.
1861 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1862 0 for XT, 1 for AT (default is AT).
1865 parport= [HW,PPT] Specify parallel ports. 0 disables.
1866 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1867 Use 'auto' to force the driver to use any
1868 IRQ/DMA settings detected (the default is to
1869 ignore detected IRQ/DMA settings because of
1870 possible conflicts). You can specify the base
1871 address, IRQ, and DMA settings; IRQ and DMA
1872 should be numbers, or 'auto' (for using detected
1873 settings on that particular port), or 'nofifo'
1874 (to avoid using a FIFO even if it is detected).
1875 Parallel ports are assigned in the order they
1876 are specified on the command line, starting
1879 parport_init_mode= [HW,PPT]
1880 Configure VIA parallel port to operate in
1881 a specific mode. This is necessary on Pegasos
1882 computer where firmware has no options for setting
1883 up parallel port mode and sets it to spp.
1884 Currently this function knows 686a and 8231 chips.
1885 Format: [spp|ps2|epp|ecp|ecpepp]
1888 Halt all CPUs after the first oops has been printed for
1889 the specified number of seconds. This is to be used if
1890 your oopses keep scrolling off the screen.
1895 See header of drivers/block/paride/pcd.c.
1896 See also Documentation/blockdev/paride.txt.
1898 pci=option[,option...] [PCI] various PCI subsystem options:
1899 earlydump [X86] dump PCI config space before the kernel
1901 off [X86] don't probe for the PCI bus
1902 bios [X86-32] force use of PCI BIOS, don't access
1903 the hardware directly. Use this if your machine
1904 has a non-standard PCI host bridge.
1905 nobios [X86-32] disallow use of PCI BIOS, only direct
1906 hardware access methods are allowed. Use this
1907 if you experience crashes upon bootup and you
1908 suspect they are caused by the BIOS.
1909 conf1 [X86] Force use of PCI Configuration
1911 conf2 [X86] Force use of PCI Configuration
1913 noaer [PCIE] If the PCIEAER kernel config parameter is
1914 enabled, this kernel boot option can be used to
1915 disable the use of PCIE advanced error reporting.
1916 nodomains [PCI] Disable support for multiple PCI
1917 root domains (aka PCI segments, in ACPI-speak).
1918 nommconf [X86] Disable use of MMCONFIG for PCI
1920 check_enable_amd_mmconf [X86] check for and enable
1921 properly configured MMIO access to PCI
1922 config space on AMD family 10h CPU
1923 nomsi [MSI] If the PCI_MSI kernel config parameter is
1924 enabled, this kernel boot option can be used to
1925 disable the use of MSI interrupts system-wide.
1926 noioapicquirk [APIC] Disable all boot interrupt quirks.
1927 Safety option to keep boot IRQs enabled. This
1928 should never be necessary.
1929 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1930 primary IO-APIC for bridges that cannot disable
1931 boot IRQs. This fixes a source of spurious IRQs
1932 when the system masks IRQs.
1933 noioapicreroute [APIC] Disable workaround that uses the
1934 boot IRQ equivalent of an IRQ that connects to
1935 a chipset where boot IRQs cannot be disabled.
1936 The opposite of ioapicreroute.
1937 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1938 routing table. These calls are known to be buggy
1939 on several machines and they hang the machine
1940 when used, but on other computers it's the only
1941 way to get the interrupt routing table. Try
1942 this option if the kernel is unable to allocate
1943 IRQs or discover secondary PCI buses on your
1945 rom [X86] Assign address space to expansion ROMs.
1946 Use with caution as certain devices share
1947 address decoders between ROMs and other
1949 norom [X86] Do not assign address space to
1950 expansion ROMs that do not already have
1951 BIOS assigned address ranges.
1952 nobar [X86] Do not assign address space to the
1953 BARs that weren't assigned by the BIOS.
1954 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1955 assigned automatically to PCI devices. You can
1956 make the kernel exclude IRQs of your ISA cards
1958 pirqaddr=0xAAAAA [X86] Specify the physical address
1959 of the PIRQ table (normally generated
1960 by the BIOS) if it is outside the
1961 F0000h-100000h range.
1962 lastbus=N [X86] Scan all buses thru bus #N. Can be
1963 useful if the kernel is unable to find your
1964 secondary buses and you want to tell it
1965 explicitly which ones they are.
1966 assign-busses [X86] Always assign all PCI bus
1967 numbers ourselves, overriding
1968 whatever the firmware may have done.
1969 usepirqmask [X86] Honor the possible IRQ mask stored
1970 in the BIOS $PIR table. This is needed on
1971 some systems with broken BIOSes, notably
1972 some HP Pavilion N5400 and Omnibook XE3
1973 notebooks. This will have no effect if ACPI
1974 IRQ routing is enabled.
1975 noacpi [X86] Do not use ACPI for IRQ routing
1976 or for PCI scanning.
1977 use_crs [X86] Use PCI host bridge window information
1978 from ACPI. On BIOSes from 2008 or later, this
1979 is enabled by default. If you need to use this,
1980 please report a bug.
1981 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1982 If you need to use this, please report a bug.
1983 routeirq Do IRQ routing for all PCI devices.
1984 This is normally done in pci_enable_device(),
1985 so this option is a temporary workaround
1986 for broken drivers that don't call it.
1987 skip_isa_align [X86] do not align io start addr, so can
1988 handle more pci cards
1989 firmware [ARM] Do not re-enumerate the bus but instead
1990 just use the configuration from the
1991 bootloader. This is currently used on
1992 IXP2000 systems where the bus has to be
1993 configured a certain way for adjunct CPUs.
1994 noearly [X86] Don't do any early type 1 scanning.
1995 This might help on some broken boards which
1996 machine check when some devices' config space
1997 is read. But various workarounds are disabled
1998 and some IOMMU drivers will not work.
1999 bfsort Sort PCI devices into breadth-first order.
2000 This sorting is done to get a device
2001 order compatible with older (<= 2.4) kernels.
2002 nobfsort Don't sort PCI devices into breadth-first order.
2003 cbiosize=nn[KMG] The fixed amount of bus space which is
2004 reserved for the CardBus bridge's IO window.
2005 The default value is 256 bytes.
2006 cbmemsize=nn[KMG] The fixed amount of bus space which is
2007 reserved for the CardBus bridge's memory
2008 window. The default value is 64 megabytes.
2011 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2012 Specifies alignment and device to reassign
2013 aligned memory resources.
2014 If <order of align> is not specified,
2015 PAGE_SIZE is used as alignment.
2016 PCI-PCI bridge can be specified, if resource
2017 windows need to be expanded.
2018 ecrc= Enable/disable PCIe ECRC (transaction layer
2019 end-to-end CRC checking).
2020 bios: Use BIOS/firmware settings. This is the
2025 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2028 force Enable ASPM even on devices that claim not to support it.
2029 WARNING: Forcing ASPM on may cause system lockups.
2031 pcie_ports= [PCIE] PCIe ports handling:
2032 auto Ask the BIOS whether or not to use native PCIe services
2033 associated with PCIe ports (PME, hot-plug, AER). Use
2034 them only if that is allowed by the BIOS.
2035 native Use native PCIe services associated with PCIe ports
2037 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2040 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2041 nomsi Do not use MSI for native PCIe PME signaling (this makes
2042 all PCIe root ports use INTx for all services).
2044 pcmv= [HW,PCMCIA] BadgePAD 4
2047 See Documentation/blockdev/paride.txt.
2049 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2052 See arch/parisc/kernel/pdc_chassis.c
2054 percpu_alloc= Select which percpu first chunk allocator to use.
2055 Currently supported values are "embed" and "page".
2056 Archs may support subset or none of the selections.
2057 See comments in mm/percpu.c for details on each
2058 allocator. This parameter is primarily for debugging
2059 and performance comparison.
2062 See Documentation/blockdev/paride.txt.
2065 See Documentation/blockdev/paride.txt.
2067 pirq= [SMP,APIC] Manual mp-table setup
2068 See Documentation/x86/i386/IO-APIC.txt.
2070 plip= [PPT,NET] Parallel port network link
2071 Format: { parport<nr> | timid | 0 }
2072 See also Documentation/parport.txt.
2074 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2075 Override pmtimer IOPort with a hex value.
2079 Enable PNP debug messages. This depends on the
2080 CONFIG_PNP_DEBUG_MESSAGES option.
2086 { on | off | curr | res | no-curr | no-res }
2089 [ISAPNP] Exclude IRQs for the autoconfiguration
2092 [ISAPNP] Exclude DMAs for the autoconfiguration
2094 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2095 Ranges are in pairs (I/O port base and size).
2098 [ISAPNP] Exclude memory regions for the
2100 Ranges are in pairs (memory base and size).
2102 ports= [IP_VS_FTP] IPVS ftp helper module
2104 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2106 Format: <port>,<port>....
2108 print-fatal-signals=
2109 [KNL] debug: print fatal signals
2111 If enabled, warn about various signal handling
2112 related application anomalies: too many signals,
2113 too many POSIX.1 timers, fatal signals causing a
2116 If you hit the warning due to signal overflow,
2117 you might want to try "ulimit -i unlimited".
2121 printk.time= Show timing data prefixed to each printk message line
2122 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2124 processor.max_cstate= [HW,ACPI]
2125 Limit processor to maximum C-state
2126 max_cstate=9 overrides any DMI blacklist limit.
2128 processor.nocst [HW,ACPI]
2129 Ignore the _CST method to determine C-states,
2130 instead using the legacy FADT method
2132 profile= [KNL] Enable kernel profiling via /proc/profile
2133 Format: [schedule,]<number>
2134 Param: "schedule" - profile schedule points.
2135 Param: <number> - step/bucket size as a power of 2 for
2136 statistical time based profiling.
2137 Param: "sleep" - profile D-state sleeping (millisecs).
2138 Requires CONFIG_SCHEDSTATS
2139 Param: "kvm" - profile VM exits.
2141 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2143 See Documentation/blockdev/ramdisk.txt.
2145 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2146 probe for; one of (bare|imps|exps|lifebook|any).
2147 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2149 psmouse.resetafter= [HW,MOUSE]
2150 Try to reset the device after so many bad packets
2153 [HW,MOUSE] Set desired mouse resolution, in dpi.
2154 psmouse.smartscroll=
2155 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2156 0 = disabled, 1 = enabled (default).
2159 See Documentation/blockdev/paride.txt.
2162 [KNL] Number of legacy pty's. Overwrites compiled-in
2165 quiet [KNL] Disable most log messages
2170 See Documentation/md.txt.
2172 ramdisk_blocksize= [RAM]
2173 See Documentation/blockdev/ramdisk.txt.
2175 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2176 See Documentation/blockdev/ramdisk.txt.
2178 rcupdate.blimit= [KNL,BOOT]
2179 Set maximum number of finished RCU callbacks to process
2182 rcupdate.qhimark= [KNL,BOOT]
2183 Set threshold of queued
2184 RCU callbacks over which batch limiting is disabled.
2186 rcupdate.qlowmark= [KNL,BOOT]
2187 Set threshold of queued RCU callbacks below which
2188 batch limiting is re-enabled.
2192 Run specified binary instead of /init from the ramdisk,
2193 used for early userspace startup. See initrd.
2195 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2196 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2197 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2200 [KNL, SMP] Set scheduler's default relax_domain_level.
2201 See Documentation/cgroups/cpusets.txt.
2203 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2205 reservetop= [X86-32]
2207 Reserves a hole at the top of the kernel virtual
2212 Set the amount of memory to reserve for BIOS at
2213 the bottom of the address space.
2215 reset_devices [KNL] Force drivers to reset the underlying device
2216 during initialization.
2219 Specify the partition device for software suspend
2221 resume_offset= [SWSUSP]
2222 Specify the offset from the beginning of the partition
2223 given by "resume=" at which the swap header is located,
2224 in <PAGE_SIZE> units (needed only for swap files).
2225 See Documentation/power/swsusp-and-swap-files.txt
2227 hibernate= [HIBERNATION]
2228 noresume Don't check if there's a hibernation image
2229 present during boot.
2230 nocompress Don't compress/decompress hibernation images.
2232 retain_initrd [RAM] Keep initrd memory after extraction
2234 rhash_entries= [KNL,NET]
2235 Set number of hash buckets for route cache
2237 riscom8= [HW,SERIAL]
2238 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2240 ro [KNL] Mount root device read-only on boot
2242 root= [KNL] Root filesystem
2244 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2245 mount the root filesystem
2247 rootflags= [KNL] Set root filesystem mount option string
2249 rootfstype= [KNL] Set root filesystem type
2251 rootwait [KNL] Wait (indefinitely) for root device to show up.
2252 Useful for devices that are detected asynchronously
2253 (e.g. USB and MMC devices).
2255 rw [KNL] Mount root device read-write on boot
2257 S [KNL] Run init in single mode
2260 See drivers/net/irda/sa1100_ir.c.
2262 sbni= [NET] Granch SBNI12 leased line adapter
2264 sched_debug [KNL] Enables verbose scheduler debug messages.
2266 security= [SECURITY] Choose a security module to enable at boot.
2267 If this boot parameter is not specified, only the first
2268 security module asking for security registration will be
2269 loaded. An invalid security module name will be treated
2270 as if no module has been chosen.
2272 selinux= [SELINUX] Disable or enable SELinux at boot time.
2273 Format: { "0" | "1" }
2274 See security/selinux/Kconfig help text.
2277 Default value is set via kernel config option.
2278 If enabled at boot time, /selinux/disable can be used
2279 later to disable prior to initial policy load.
2281 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2282 Format: { "0" | "1" }
2283 See security/apparmor/Kconfig help text
2286 Default value is set via kernel config option.
2288 serialnumber [BUGS=X86-32]
2291 Maximal number of shapers.
2293 show_msr= [x86] show boot-time MSR settings
2294 Format: { <integer> }
2295 Show boot-time (BIOS-initialized) MSR settings.
2296 The parameter means the number of CPUs to show,
2297 for example 1 means boot CPU only.
2304 slub_debug[=options[,slabs]] [MM, SLUB]
2305 Enabling slub_debug allows one to determine the
2306 culprit if slab objects become corrupted. Enabling
2307 slub_debug can create guard zones around objects and
2308 may poison objects when not in use. Also tracks the
2309 last alloc / free. For more information see
2310 Documentation/vm/slub.txt.
2312 slub_max_order= [MM, SLUB]
2313 Determines the maximum allowed order for slabs.
2314 A high setting may cause OOMs due to memory
2315 fragmentation. For more information see
2316 Documentation/vm/slub.txt.
2318 slub_min_objects= [MM, SLUB]
2319 The minimum number of objects per slab. SLUB will
2320 increase the slab order up to slub_max_order to
2321 generate a sufficiently large slab able to contain
2322 the number of objects indicated. The higher the number
2323 of objects the smaller the overhead of tracking slabs
2324 and the less frequently locks need to be acquired.
2325 For more information see Documentation/vm/slub.txt.
2327 slub_min_order= [MM, SLUB]
2328 Determines the mininum page order for slabs. Must be
2329 lower than slub_max_order.
2330 For more information see Documentation/vm/slub.txt.
2332 slub_nomerge [MM, SLUB]
2333 Disable merging of slabs with similar size. May be
2334 necessary if there is some reason to distinguish
2335 allocs to different slabs. Debug options disable
2336 merging on their own.
2337 For more information see Documentation/vm/slub.txt.
2340 Format: <io1>[,<io2>[,...,<io8>]]
2342 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2343 attempt to substitute SMP alternatives once at boot.
2345 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2346 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2347 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2348 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2349 smsc-ircc2.ircc_irq= [HW] IRQ line
2350 smsc-ircc2.ircc_dma= [HW] DMA channel
2351 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2352 0: Toshiba Satellite 1800 (GP data pin select)
2353 1: Fast pin select (default)
2357 [KNL] Should the soft-lockup detector generate panics.
2360 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2361 See Documentation/sonypi.txt
2363 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2364 See Documentation/serial/specialix.txt.
2366 spia_io_base= [HW,MTD]
2372 Enabled the stack tracer on boot up.
2376 Set the STI (builtin display/keyboard on the HP-PARISC
2377 machines) console (graphic card) which should be used
2378 as the initial boot-console.
2379 See also comment in drivers/video/console/sticore.c.
2382 See comment in drivers/video/console/sticore.c.
2385 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2387 sunrpc.min_resvport=
2388 sunrpc.max_resvport=
2390 SunRPC servers often require that client requests
2391 originate from a privileged port (i.e. a port in the
2392 range 0 < portnr < 1024).
2393 An administrator who wishes to reserve some of these
2394 ports for other uses may adjust the range that the
2395 kernel's sunrpc client considers to be privileged
2396 using these two parameters to set the minimum and
2397 maximum port values.
2401 Control how the NFS server code allocates CPUs to
2402 service thread pools. Depending on how many NICs
2403 you have and where their interrupts are bound, this
2404 option will affect which CPUs will do NFS serving.
2405 Note: this parameter cannot be changed while the
2406 NFS server is running.
2408 auto the server chooses an appropriate mode
2409 automatically using heuristics
2410 global a single global pool contains all CPUs
2411 percpu one pool for each CPU
2412 pernode one pool for each NUMA node (equivalent
2413 to global on non-NUMA machines)
2415 sunrpc.tcp_slot_table_entries=
2416 sunrpc.udp_slot_table_entries=
2418 Sets the upper limit on the number of simultaneous
2419 RPC calls that can be sent from the client to a
2420 server. Increasing these values may allow you to
2421 improve throughput, but will also increase the
2422 amount of memory reserved for use by the client.
2425 [KNL] Enable accounting of swap in memory resource
2426 controller if no parameter or 1 is given or disable
2427 it if 0 is given (See Documentation/cgroups/memory.txt)
2429 swiotlb= [IA-64] Number of I/O TLB slabs
2433 sysfs.deprecated=0|1 [KNL]
2434 Enable/disable old style sysfs layout for old udev
2435 on older distributions. When this option is enabled
2436 very new udev will not work anymore. When this option
2437 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2438 in older udev will not work anymore.
2439 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2440 the kernel configuration.
2442 sysrq_always_enabled
2444 Ignore sysrq setting - this boot parameter will
2445 neutralize any effect of /proc/sys/kernel/sysrq.
2446 Useful for debugging.
2450 test_suspend= [SUSPEND]
2451 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2452 standby suspend) as the system sleep state to briefly
2453 enter during system startup. The system is woken from
2454 this state using a wakeup-capable RTC alarm.
2456 thash_entries= [KNL,NET]
2457 Set number of hash buckets for TCP connection
2459 thermal.act= [HW,ACPI]
2460 -1: disable all active trip points in all thermal zones
2461 <degrees C>: override all lowest active trip points
2463 thermal.crt= [HW,ACPI]
2464 -1: disable all critical trip points in all thermal zones
2465 <degrees C>: override all critical trip points
2467 thermal.nocrt= [HW,ACPI]
2468 Set to disable actions on ACPI thermal zone
2469 critical and hot trip points.
2471 thermal.off= [HW,ACPI]
2472 1: disable ACPI thermal control
2474 thermal.psv= [HW,ACPI]
2475 -1: disable all passive trip points
2476 <degrees C>: override all passive trip points to this
2479 thermal.tzp= [HW,ACPI]
2480 Specify global default ACPI thermal zone polling rate
2481 <deci-seconds>: poll all this frequency
2482 0: no polling (default)
2485 Force threading of all interrupt handlers except those
2486 marked explicitely IRQF_NO_THREAD.
2490 Specify if the kernel should make use of the cpu
2491 topology information if the hardware supports this.
2492 The scheduler will make use of this information and
2493 e.g. base its process migration decisions on it.
2498 tpm_suspend_pcr=[HW,TPM]
2499 Format: integer pcr id
2500 Specify that at suspend time, the tpm driver
2501 should extend the specified pcr with zeros,
2502 as a workaround for some chips which fail to
2503 flush the last written pcr on TPM_SaveState.
2504 This will guarantee that all the other pcrs
2507 trace_buf_size=nn[KMG]
2508 [FTRACE] will set tracing buffer size.
2510 trace_event=[event-list]
2511 [FTRACE] Set and start specified trace events in order
2512 to facilitate early boot debugging.
2513 See also Documentation/trace/events.txt
2515 tsc= Disable clocksource stability checks for TSC.
2517 [x86] reliable: mark tsc clocksource as reliable, this
2518 disables clocksource verification at runtime, as well
2519 as the stability checks done at bootup. Used to enable
2520 high-resolution timer mode on older hardware, and in
2521 virtualized environment.
2522 [x86] noirqtime: Do not use TSC to do irq accounting.
2523 Used to run time disable IRQ_TIME_ACCOUNTING on any
2524 platforms where RDTSC is slow and this accounting
2527 turbografx.map[2|3]= [HW,JOY]
2528 TurboGraFX parallel port interface
2530 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2531 See also Documentation/input/joystick-parport.txt
2533 uhash_entries= [KNL,NET]
2534 Set number of hash buckets for UDP/UDP-Lite connections
2537 [USB] Ignore overcurrent events (default N).
2538 Some badly-designed motherboards generate lots of
2539 bogus events, for ports that aren't wired to
2540 anything. Set this parameter to avoid log spamming.
2541 Note that genuine overcurrent events won't be
2545 [X86] Cause panic on unknown NMI.
2547 usbcore.autosuspend=
2548 [USB] The autosuspend time delay (in seconds) used
2549 for newly-detected USB devices (default 2). This
2550 is the time required before an idle device will be
2551 autosuspended. Devices for which the delay is set
2552 to a negative value won't be autosuspended at all.
2554 usbcore.usbfs_snoop=
2555 [USB] Set to log all usbfs traffic (default 0 = off).
2557 usbcore.blinkenlights=
2558 [USB] Set to cycle leds on hubs (default 0 = off).
2560 usbcore.old_scheme_first=
2561 [USB] Start with the old device initialization
2562 scheme (default 0 = off).
2564 usbcore.use_both_schemes=
2565 [USB] Try the other device initialization scheme
2566 if the first one fails (default 1 = enabled).
2568 usbcore.initial_descriptor_timeout=
2569 [USB] Specifies timeout for the initial 64-byte
2570 USB_REQ_GET_DESCRIPTOR request in milliseconds
2571 (default 5000 = 5.0 seconds).
2574 [USBHID] The interval which mice are to be polled at.
2576 usb-storage.delay_use=
2577 [UMS] The delay in seconds before a new device is
2578 scanned for Logical Units (default 5).
2581 [UMS] A list of quirks entries to supplement or
2582 override the built-in unusual_devs list. List
2583 entries are separated by commas. Each entry has
2584 the form VID:PID:Flags where VID and PID are Vendor
2585 and Product ID values (4-digit hex numbers) and
2586 Flags is a set of characters, each corresponding
2587 to a common usb-storage quirk flag as follows:
2588 a = SANE_SENSE (collect more than 18 bytes
2590 b = BAD_SENSE (don't collect more than 18
2591 bytes of sense data);
2592 c = FIX_CAPACITY (decrease the reported
2593 device capacity by one sector);
2594 d = NO_READ_DISC_INFO (don't use
2595 READ_DISC_INFO command);
2596 e = NO_READ_CAPACITY_16 (don't use
2597 READ_CAPACITY_16 command);
2598 h = CAPACITY_HEURISTICS (decrease the
2599 reported device capacity by one
2600 sector if the number is odd);
2601 i = IGNORE_DEVICE (don't bind to this
2603 l = NOT_LOCKABLE (don't try to lock and
2604 unlock ejectable media);
2605 m = MAX_SECTORS_64 (don't transfer more
2606 than 64 sectors = 32 KB at a time);
2607 n = INITIAL_READ10 (force a retry of the
2608 initial READ(10) command);
2609 o = CAPACITY_OK (accept the capacity
2610 reported by the device);
2611 r = IGNORE_RESIDUE (the device reports
2612 bogus residue values);
2613 s = SINGLE_LUN (the device has only one
2615 w = NO_WP_DETECT (don't test whether the
2616 medium is write-protected).
2617 Example: quirks=0419:aaf5:rl,0421:0433:rc
2620 [X86] Flags controlling user PTE allocations.
2622 nohigh = do not allocate PTE pages in
2623 HIGHMEM regardless of setting
2627 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2628 vdso=1: enable VDSO (default)
2629 vdso=0: disable VDSO mapping
2632 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2633 vdso32=1: enable 32-bit VDSO (default)
2634 vdso32=0: disable 32-bit VDSO mapping
2637 vector=percpu: enable percpu vector domain
2639 video= [FB] Frame buffer configuration
2640 See Documentation/fb/modedb.txt.
2642 vga= [BOOT,X86-32] Select a particular video mode
2643 See Documentation/x86/boot.txt and
2644 Documentation/svga.txt.
2645 Use vga=ask for menu.
2646 This is actually a boot loader parameter; the value is
2647 passed to the kernel using a special protocol.
2649 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2650 size of <nn>. This can be used to increase the
2651 minimum size (128MB on x86). It can also be used to
2652 decrease the size and leave more room for directly
2655 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2658 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2661 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2664 vt.cur_default= [VT] Default cursor shape.
2665 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2666 the parameters of the <Esc>[?A;B;Cc escape sequence;
2667 see VGA-softcursor.txt. Default: 2 = underline.
2669 vt.default_blu= [VT]
2670 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2671 Change the default blue palette of the console.
2672 This is a 16-member array composed of values
2675 vt.default_grn= [VT]
2676 Format: <green0>,<green1>,<green2>,...,<green15>
2677 Change the default green palette of the console.
2678 This is a 16-member array composed of values
2681 vt.default_red= [VT]
2682 Format: <red0>,<red1>,<red2>,...,<red15>
2683 Change the default red palette of the console.
2684 This is a 16-member array composed of values
2690 Set system-wide default UTF-8 mode for all tty's.
2691 Default is 1, i.e. UTF-8 mode is enabled for all
2692 newly opened terminals.
2694 vt.global_cursor_default=
2697 Set system-wide default for whether a cursor
2698 is shown on new VTs. Default is -1,
2699 i.e. cursors will be created by default unless
2700 overridden by individual drivers. 0 will hide
2701 cursors, 1 will display them.
2703 watchdog timers [HW,WDT] For information on watchdog timers,
2704 see Documentation/watchdog/watchdog-parameters.txt
2705 or other driver-specific files in the
2706 Documentation/watchdog/ directory.
2708 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2709 default x2apic cluster mode on platforms
2712 x86_mrst_timer= [X86-32,APBT]
2713 Choose timer option for x86 Moorestown MID platform.
2714 Two valid options are apbt timer only and lapic timer
2715 plus one apbt timer for broadcast timer.
2716 x86_mrst_timer=apbt_only | lapic_and_apbt
2718 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2719 xd_geo= See header of drivers/block/xd.c.
2721 xen_emul_unplug= [HW,X86,XEN]
2722 Unplug Xen emulated devices
2723 Format: [unplug0,][unplug1]
2724 ide-disks -- unplug primary master IDE devices
2725 aux-ide-disks -- unplug non-primary-master IDE devices
2726 nics -- unplug network devices
2727 all -- unplug all emulated devices (NICs and IDE disks)
2728 unnecessary -- unplugging emulated devices is
2729 unnecessary even if the host did not respond to
2731 never -- do not unplug even if version check succeeds
2733 xirc2ps_cs= [NET,PCMCIA]
2735 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2737 ______________________________________________________________________
2741 Add more DRM drivers.
git.openpandora.org / pandora-kernel.git / blob