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 See also Documentation/power/pm.txt, pci=noacpi
166 acpi_apic_instance= [ACPI, IOAPIC]
168 2: use 2nd APIC table, if available
169 1,0: use 1st APIC table
172 acpi_backlight= [HW,ACPI]
173 acpi_backlight=vendor
175 If set to vendor, prefer vendor specific driver
176 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
177 of the ACPI video.ko driver.
179 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
180 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
182 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
183 debug output. Bits in debug_layer correspond to a
184 _COMPONENT in an ACPI source file, e.g.,
185 #define _COMPONENT ACPI_PCI_COMPONENT
186 Bits in debug_level correspond to a level in
187 ACPI_DEBUG_PRINT statements, e.g.,
188 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
189 The debug_level mask defaults to "info". See
190 Documentation/acpi/debug.txt for more information about
191 debug layers and levels.
193 Enable processor driver info messages:
194 acpi.debug_layer=0x20000000
195 Enable PCI/PCI interrupt routing info messages:
196 acpi.debug_layer=0x400000
197 Enable AML "Debug" output, i.e., stores to the Debug
198 object while interpreting AML:
199 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
200 Enable all messages related to ACPI hardware:
201 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
203 Some values produce so much output that the system is
204 unusable. The "log_buf_len" parameter may be useful
205 if you need to capture more output.
207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
220 Format: <irq>,<irq>...
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
240 acpi_serialize [HW,ACPI] force serialization of AML methods
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
248 old_ordering, nonvs, sci_force_enable }
249 See Documentation/power/video.txt for information on
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
259 nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during suspend/hibernation and resume.
261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
285 add_efi_memmap [EFI; X86] Include EFI memory map in
286 kernel's map of available physical RAM.
289 { off | try_unsupported }
290 off: disable AGP support
291 try_unsupported: try to drive unsupported chipsets
292 (may crash computer or cause data corruption)
295 See Documentation/sound/alsa/alsa-parameters.txt
298 Allow the default userspace alignment fault handler
299 behaviour to be specified. Bit 0 enables warnings,
300 bit 1 enables fixups, and bit 2 sends a segfault.
302 align_va_addr= [X86-64]
303 Align virtual addresses by clearing slice [14:12] when
304 allocating a VMA at process creation time. This option
305 gives you up to 3% performance improvement on AMD F15h
306 machines (where it is enabled by default) for a
307 CPU-intensive style benchmark, and it can vary highly in
308 a microbenchmark depending on workload and compiler.
310 1: only for 32-bit processes
311 2: only for 64-bit processes
312 on: enable for both 32- and 64-bit processes
313 off: disable for both 32- and 64-bit processes
315 amd_iommu= [HW,X86-84]
316 Pass parameters to the AMD IOMMU driver in the system.
318 fullflush - enable flushing of IO/TLB entries when
319 they are unmapped. Otherwise they are
320 flushed before they will be reused, which
322 off - do not initialize any AMD IOMMU found in
325 amijoy.map= [HW,JOY] Amiga joystick support
326 Map of devices attached to JOY0DAT and JOY1DAT
328 See also Documentation/kernel/input/joystick.txt
330 analog.map= [HW,JOY] Analog joystick and gamepad support
331 Specifies type or capabilities of an analog joystick
332 connected to one of 16 gameports
333 Format: <type1>,<type2>,..<type16>
336 Power management functions (SPARCstation-4/5 + deriv.)
338 Disable APC CPU standby support. SPARCstation-Fox does
339 not play well with APC CPU idle - disable it if you have
340 APC and your system crashes randomly.
342 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
343 Change the output verbosity whilst booting
344 Format: { quiet (default) | verbose | debug }
345 Change the amount of debugging information output
346 when initialising the APIC and IO-APIC components.
349 See Documentation/networking/ipv6.txt.
351 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
352 Limit apic dumping. The parameter defines the maximal
353 number of local apics being dumped. Also it is possible
354 to set it to "all" by meaning -- no limit here.
355 Format: { 1 (default) | 2 | ... | all }.
356 The parameter valid if only apic=debug or
357 apic=verbose is specified.
358 Example: apic=debug show_lapic=all
360 apm= [APM] Advanced Power Management
361 See header of arch/x86/kernel/apm_32.c.
363 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
364 Format: <io>,<irq>,<nodeID>
368 atarimouse= [HW,MOUSE] Atari Mouse
370 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
371 EzKey and similar keyboards
373 atkbd.reset= [HW] Reset keyboard during initialization
375 atkbd.set= [HW] Select keyboard code set
376 Format: <int> (2 = AT (default), 3 = PS/2)
378 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
381 atkbd.softraw= [HW] Choose between synthetic and real raw mode
382 Format: <bool> (0 = real, 1 = synthetic (default))
384 atkbd.softrepeat= [HW]
385 Use software keyboard repeat
389 baycom_epp= [HW,AX25]
392 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
394 See header of drivers/net/hamradio/baycom_par.c.
396 baycom_ser_fdx= [HW,AX25]
397 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
398 Format: <io>,<irq>,<mode>[,<baud>]
399 See header of drivers/net/hamradio/baycom_ser_fdx.c.
401 baycom_ser_hdx= [HW,AX25]
402 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
403 Format: <io>,<irq>,<mode>
404 See header of drivers/net/hamradio/baycom_ser_hdx.c.
406 boot_delay= Milliseconds to delay each printk during boot.
407 Values larger than 10 seconds (10000) are changed to
411 bootmem_debug [KNL] Enable bootmem allocator debug messages.
413 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
414 bttv.radio= Most important insmod options are available as
416 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
417 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
419 bulk_remove=off [PPC] This parameter disables the use of the pSeries
420 firmware feature for flushing multiple hpte entries
423 c101= [NET] Moxa C101 synchronous serial card
425 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
426 Sometimes CPU hardware bugs make them report the cache
427 size incorrectly. The kernel will attempt work arounds
428 to fix known problems, but for some CPUs it is not
429 possible to determine what the correct size should be.
430 This option provides an override for these situations.
433 [SECURITY] Disable capabilities. This would normally
434 be used only if an alternative security model is to be
435 configured. Potentially dangerous and should only be
436 used if you are entirely sure of the consequences.
438 ccw_timeout_log [S390]
439 See Documentation/s390/CommonIO for details.
441 cgroup_disable= [KNL] Disable a particular controller
442 Format: {name of the controller(s) to disable}
443 {Currently supported controllers - "memory"}
445 checkreqprot [SELINUX] Set initial checkreqprot flag value.
446 Format: { "0" | "1" }
447 See security/selinux/Kconfig help text.
448 0 -- check protection applied by kernel (includes
449 any implied execute protection).
450 1 -- check protection requested by application.
451 Default value is set via a kernel config option.
452 Value can be changed at runtime via
453 /selinux/checkreqprot.
456 See Documentation/s390/CommonIO for details.
458 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
460 Forces specified clocksource (if available) to be used
461 when calculating gettimeofday(). If specified
462 clocksource is not available, it defaults to PIT.
463 Format: { pit | tsc | cyclone | pmtmr }
465 clocksource= Override the default clocksource
467 Override the default clocksource and use the clocksource
468 with the name specified.
469 Some clocksource names to choose from, depending on
471 [all] jiffies (this is the base, fallback clocksource)
473 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
474 pxa_timer,timer3,32k_counter,timer0_1
476 [X86-32] pit,hpet,tsc;
477 scx200_hrt on Geode; cyclone on IBM x440
485 clearcpuid=BITNUM [X86]
486 Disable CPUID feature X for the kernel. See
487 arch/x86/include/asm/cpufeature.h for the valid bit
488 numbers. Note the Linux specific bits are not necessarily
489 stable over kernel options, but the vendor specific
491 Also note that user programs calling CPUID directly
492 or using the feature without checking anything
493 will still see it. This just prevents it from
494 being used by the kernel or shown in /proc/cpuinfo.
495 Also note the kernel might malfunction if you disable
498 cmo_free_hint= [PPC] Format: { yes | no }
499 Specify whether pages are marked as being inactive
500 when they are freed. This is used in CMO environments
501 to determine OS memory pressure for page stealing by
505 code_bytes [X86] How many bytes of object code to print
510 com20020= [HW,NET] ARCnet - COM20020 chipset
512 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
514 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
518 ARCnet - COM90xx chipset (memory-mapped buffers)
519 Format: <io>[,<irq>[,<memstart>]]
521 condev= [HW,S390] console device
524 console= [KNL] Output console device and options.
526 tty<n> Use the virtual console device <n>.
530 Use the specified serial port. The options are of
531 the form "bbbbpnf", where "bbbb" is the baud rate,
532 "p" is parity ("n", "o", or "e"), "n" is number of
533 bits, and "f" is flow control ("r" for RTS or
534 omit it). Default is "9600n8".
536 See Documentation/serial-console.txt for more
538 Documentation/networking/netconsole.txt for an
541 uart[8250],io,<addr>[,options]
542 uart[8250],mmio,<addr>[,options]
543 Start an early, polled-mode console on the 8250/16550
544 UART at the specified I/O port or MMIO address,
545 switching to the matching ttyS device later. The
546 options are the same as for ttyS, above.
548 If the device connected to the port is not a TTY but a braille
549 device, prepend "brl," before the device type, for instance
551 For now, only VisioBraille is supported.
553 consoleblank= [KNL] The console blank (screen saver) timeout in
554 seconds. Defaults to 10*60 = 10mins. A value of 0
555 disables the blank timer.
558 [KNL] Change the default value for
559 /proc/<pid>/coredump_filter.
560 See also Documentation/filesystems/proc.txt.
562 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
564 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
566 crashkernel=size[KMG][@offset[KMG]]
567 [KNL] Using kexec, Linux can switch to a 'crash kernel'
568 upon panic. This parameter reserves the physical
569 memory region [offset, offset + size] for that kernel
570 image. If '@offset' is omitted, then a suitable offset
571 is selected automatically. Check
572 Documentation/kdump/kdump.txt for further details.
574 crashkernel=range1:size1[,range2:size2,...][@offset]
575 [KNL] Same as above, but depends on the memory
576 in the running system. The syntax of range is
577 start-[end] where start and end are both
578 a memory unit (amount[KMG]). See also
579 Documentation/kdump/kdump.txt for an example.
584 cs89x0_media= [HW,NET]
585 Format: { rj45 | aui | bnc }
588 See header of drivers/s390/block/dasd_devmap.c.
590 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
591 (one device per port)
592 Format: <port#>,<type>
593 See also Documentation/input/joystick-parport.txt
595 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
596 time. See Documentation/dynamic-debug-howto.txt for
599 debug [KNL] Enable kernel debugging (events log level).
602 [KNL] verbose self-tests
604 Print debugging info while doing the locking API
606 We default to 0 (no extra messages), setting it to
607 1 will print _a lot_ more information - normally
608 only useful to kernel developers.
610 debug_objects [KNL] Enable object debugging
613 [KNL] Disable object debugging
615 debugpat [X86] Enable PAT debugging
617 decnet.addr= [HW,NET]
618 Format: <area>[,<node>]
619 See also Documentation/networking/decnet.txt.
622 [same as hugepagesz=] The size of the default
623 HugeTLB page size. This is the size represented by
624 the legacy /proc/ hugepages APIs, used for SHM, and
625 default size when mounting hugetlbfs filesystems.
626 Defaults to the default architecture's huge page size
630 Set number of hash buckets for dentry cache.
633 IO parameters + enable/disable command.
635 digiepca= [HW,SERIAL]
636 See drivers/char/README.epca and
637 Documentation/serial/digiepca.txt.
640 See Documentation/networking/ipv6.txt.
642 disable_ddw [PPC/PSERIES]
643 Disable Dynamic DMA Window support. Use this if
644 to workaround buggy firmware.
647 See Documentation/networking/ipv6.txt.
649 disable_mtrr_cleanup [X86]
650 The kernel tries to adjust MTRR layout from continuous
651 to discrete, to make X server driver able to add WB
652 entry later. This parameter disables that.
654 disable_mtrr_trim [X86, Intel and AMD only]
655 By default the kernel will trim any uncacheable
656 memory out of your available memory pool based on
657 MTRR settings. This parameter disables that behavior,
658 possibly causing your machine to run very slowly.
660 disable_timer_pin_1 [X86]
661 Disable PIN 1 of APIC timer
662 Can be useful to work around chipset bugs.
664 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
665 this option disables the debugging code at boot.
667 dma_debug_entries=<number>
668 This option allows to tune the number of preallocated
669 entries for DMA-API debugging code. One entry is
670 required per DMA-API allocation. Use this if the
671 DMA-API debugging code disables itself because the
672 architectural default is too low.
674 dma_debug_driver=<driver_name>
675 With this option the DMA-API debugging driver
676 filter feature can be enabled at boot time. Just
677 pass the driver to filter for as the parameter.
678 The filter can be disabled or changed to another
679 driver later using sysfs.
683 earlycon= [KNL] Output early console device and options.
684 uart[8250],io,<addr>[,options]
685 uart[8250],mmio,<addr>[,options]
686 uart[8250],mmio32,<addr>[,options]
687 Start an early, polled-mode console on the 8250/16550
688 UART at the specified I/O port or MMIO address.
689 MMIO inter-register address stride is either 8bit (mmio)
691 The options are the same as for ttyS, above.
693 earlyprintk= [X86,SH,BLACKFIN]
695 earlyprintk=serial[,ttySn[,baudrate]]
696 earlyprintk=ttySn[,baudrate]
697 earlyprintk=dbgp[debugController#]
699 Append ",keep" to not disable it when the real console
702 Only vga or serial or usb debug port at a time.
704 Currently only ttyS0 and ttyS1 are supported.
706 Interaction with the standard serial driver is not
709 The VGA output is eventually overwritten by the real
712 ekgdboc= [X86,KGDB] Allow early kernel console debugging
715 This is designed to be used in conjunction with
716 the boot argument: earlyprintk=vga
719 Format: {"off" | "on" | "skip[mbr]"}
721 eisa_irq_edge= [PARISC,HW]
722 See header of drivers/parisc/eisa.c.
725 See comment before function elanfreq_setup() in
726 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
729 Format: {"cfq" | "deadline" | "noop"}
730 See Documentation/block/as-iosched.txt and
731 Documentation/block/deadline-iosched.txt for details.
733 elfcorehdr= [IA64,PPC,SH,X86]
734 Specifies physical address of start of kernel core
735 image elf header. Generally kexec loader will
736 pass this option to capture kernel.
737 See Documentation/kdump/kdump.txt for details.
739 enable_mtrr_cleanup [X86]
740 The kernel tries to adjust MTRR layout from continuous
741 to discrete, to make X server driver able to add WB
742 entry later. This parameter enables that.
744 enable_timer_pin_1 [X86]
745 Enable PIN 1 of APIC timer
746 Can be useful to work around chipset bugs
747 (in particular on some ATI chipsets).
748 The kernel tries to set a reasonable default.
750 enforcing [SELINUX] Set initial enforcing status.
752 See security/selinux/Kconfig help text.
753 0 -- permissive (log only, no denials).
754 1 -- enforcing (deny and log).
756 Value can be changed at runtime via /selinux/enforce.
759 Disable Error Record Serialization Table (ERST)
762 ether= [HW,NET] Ethernet cards parameters
763 This option is obsoleted by the "netdev=" option, which
764 has equivalent usage. See its documentation for details.
768 fail_make_request=[KNL]
769 General fault injection mechanism.
770 Format: <interval>,<probability>,<space>,<times>
771 See also /Documentation/fault-injection/.
774 See Documentation/blockdev/floppy.txt.
776 force_pal_cache_flush
777 [IA-64] Avoid check_sal_cache_flush which may hang on
778 buggy SAL_CACHE_FLUSH implementations. Using this
779 parameter will force ia64_sal_cache_flush to call
780 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
783 [FTRACE] will set and start the specified tracer
784 as early as possible in order to facilitate early
787 ftrace_dump_on_oops[=orig_cpu]
788 [FTRACE] will dump the trace buffers on oops.
789 If no parameter is passed, ftrace will dump
790 buffers of all CPUs, but if you pass orig_cpu, it will
791 dump only the buffer of the CPU that triggered the
794 ftrace_filter=[function-list]
795 [FTRACE] Limit the functions traced by the function
796 tracer at boot up. function-list is a comma separated
797 list of functions. This list can be changed at run
798 time by the set_ftrace_filter file in the debugfs
801 ftrace_notrace=[function-list]
802 [FTRACE] Do not trace the functions specified in
803 function-list. This list can be changed at run time
804 by the set_ftrace_notrace file in the debugfs
807 ftrace_graph_filter=[function-list]
808 [FTRACE] Limit the top level callers functions traced
809 by the function graph tracer at boot up.
810 function-list is a comma separated list of functions
811 that can be changed at run time by the
812 set_graph_function file in the debugfs tracing directory.
815 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
816 support via parallel port (up to 5 devices per port)
817 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
818 See also Documentation/input/joystick-parport.txt
822 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
826 gcov_persist= [GCOV] When non-zero (default), profiling data for
827 kernel modules is saved and remains accessible via
828 debugfs, even when the module is unloaded/reloaded.
829 When zero, profiling data is discarded and associated
830 debugfs files are removed at module unload time.
832 gpt [EFI] Forces disk with valid GPT signature but
833 invalid Protective MBR to be treated as GPT.
835 hashdist= [KNL,NUMA] Large hashes allocated during boot
836 are distributed across NUMA nodes. Defaults on
837 for 64bit NUMA, off otherwise.
838 Format: 0 | 1 (for off | on)
840 hcl= [IA-64] SGI's Hardware Graph compatibility layer
842 hd= [EIDE] (E)IDE hard drive subsystem geometry
843 Format: <cyl>,<head>,<sect>
846 Disable Hardware Error Source Table (HEST) support;
847 corresponding firmware-first mode error processing
848 logic will be disabled.
850 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
851 size of <nn>. This works even on boxes that have no
852 highmem otherwise. This also works to reduce highmem
853 size on bigger boxes.
855 highres= [KNL] Enable/disable high resolution timer mode.
856 Valid parameters: "on", "off"
860 See Documentation/isdn/README.HiSax.
864 hpet= [X86-32,HPET] option to control HPET usage
865 Format: { enable (default) | disable | force |
867 disable: disable HPET and use PIT instead
868 force: allow force enabled of undocumented chips (ICH4,
870 verbose: show contents of HPET registers during setup
872 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
873 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
874 On x86-64 and powerpc, this option can be specified
875 multiple times interleaved with hugepages= to reserve
876 huge pages of different sizes. Valid pages sizes on
877 x86-64 are 2M (when the CPU supports "pse") and 1G
878 (when the CPU supports the "pdpe1gb" cpuinfo flag)
879 Note that 1GB pages can only be allocated at boot time
880 using hugepages= and not freed afterwards.
882 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
883 terminal devices. Valid values: 0..8
884 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
885 If specified, z/VM IUCV HVC accepts connections
886 from listed z/VM user IDs only.
889 Do not unregister boot console at start. This is only
890 useful for debugging when something happens in the window
891 between unregistering the boot console and initializing
894 i2c_bus= [HW] Override the default board specific I2C bus speed
895 or register an additional I2C bus that is not
896 registered from board initialization code.
900 i8042.debug [HW] Toggle i8042 debug mode
901 i8042.direct [HW] Put keyboard port into non-translated mode
902 i8042.dumbkbd [HW] Pretend that controller can only read data from
903 keyboard and cannot control its state
904 (Don't attempt to blink the leds)
905 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
906 i8042.nokbd [HW] Don't check/create keyboard port
907 i8042.noloop [HW] Disable the AUX Loopback command while probing
909 i8042.nomux [HW] Don't check presence of an active multiplexing
911 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
913 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
914 i8042.reset [HW] Reset the controller during init and cleanup
915 i8042.unlock [HW] Unlock (ignore) the keylock
919 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
920 indicates that the driver is running on unsupported
922 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
923 does not match list of supported models.
925 [HW] Report power status in /proc/i8k
926 (disabled by default)
927 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
931 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
933 ide-core.nodma= [HW] (E)IDE subsystem
934 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
935 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
936 .cdrom .chs .ignore_cable are additional options
937 See Documentation/ide/ide.txt.
939 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
940 Claim all unknown PCI IDE storage controllers.
943 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
944 Poll forces a polling idle loop that can slightly
945 improve the performance of waking up a idle CPU, but
946 will use a lot of power and make the system run hot.
948 idle=mwait: On systems which support MONITOR/MWAIT but
949 the kernel chose to not use it because it doesn't save
950 as much power as a normal idle loop, use the
951 MONITOR/MWAIT idle loop anyways. Performance should be
952 the same as idle=poll.
953 idle=halt: Halt is forced to be used for CPU idle.
954 In such case C2/C3 won't be used again.
955 idle=nomwait: Disable mwait for CPU C-states
957 ignore_loglevel [KNL]
958 Ignore loglevel setting - this will print /all/
959 kernel messages to the console. Useful for debugging.
962 Set number of hash buckets for inode cache.
965 Format: { "0" | "1" }
966 0 -- integrity auditing messages. (Default)
967 1 -- enable informational integrity auditing messages.
970 Format: { "sha1" | "md5" }
974 Load a policy which meets the needs of the Trusted
975 Computing Base. This means IMA will measure all
976 programs exec'd, files mmap'd for exec, and all files
977 opened for read by uid=0.
981 Run specified binary instead of /sbin/init as init
984 initcall_debug [KNL] Trace initcalls as they are executed. Useful
985 for working out where the kernel is dying during
988 initrd= [BOOT] Specify the location of the initial ramdisk
990 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
993 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
995 Enable intel iommu driver.
997 Disable intel iommu driver.
998 igfx_off [Default Off]
999 By default, gfx is mapped as normal device. If a gfx
1000 device has a dedicated DMAR unit, the DMAR unit is
1001 bypassed by not enabling DMAR with this option. In
1002 this case, gfx device will use physical address for
1005 With this option iommu will not optimize to look
1006 for io virtual address below 32 bit forcing dual
1007 address cycle on pci bus for cards supporting greater
1008 than 32 bit addressing. The default is to look
1009 for translation below 32 bit and if not available
1010 then look in the higher range.
1011 strict [Default Off]
1012 With this option on every unmap_single operation will
1013 result in a hardware IOTLB flush operation as opposed
1014 to batching them for performance.
1015 sp_off [Default Off]
1016 By default, super page will be supported if Intel IOMMU
1017 has the capability. With this option, super page will
1019 intremap= [X86-64, Intel-IOMMU]
1020 Format: { on (default) | off | nosid }
1021 on enable Interrupt Remapping (default)
1022 off disable Interrupt Remapping
1023 nosid disable Source ID checking
1027 iomem= Disable strict checking of access to MMIO memory
1028 strict regions from userspace.
1044 io7= [HW] IO7 for Marvel based alpha systems
1045 See comment before marvel_specify_io7 in
1046 arch/alpha/kernel/core_marvel.c.
1048 io_delay= [X86] I/O delay method
1050 Standard port 0x80 based delay
1052 Alternate port 0xed based delay (needed on some systems)
1054 Simple two microseconds delay
1059 See Documentation/filesystems/nfs/nfsroot.txt.
1061 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1062 See comment before ip2_setup() in
1063 drivers/char/ip2/ip2base.c.
1066 When an interrupt is not handled search all handlers
1067 for it. Intended to get systems with badly broken
1071 When an interrupt is not handled search all handlers
1072 for it. Also check all handlers each timer
1073 interrupt. Intended to get systems with badly broken
1077 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1079 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1081 <cpu number>,...,<cpu number>
1083 <cpu number>-<cpu number>
1084 (must be a positive range in ascending order)
1086 <cpu number>,...,<cpu number>-<cpu number>
1088 This option can be used to specify one or more CPUs
1089 to isolate from the general SMP balancing and scheduling
1090 algorithms. You can move a process onto or off an
1091 "isolated" CPU via the CPU affinity syscalls or cpuset.
1092 <cpu number> begins at 0 and the maximum value is
1093 "number of CPUs in system - 1".
1095 This option is the preferred way to isolate CPUs. The
1096 alternative -- manually setting the CPU mask of all
1097 tasks in the system -- can cause problems and
1098 suboptimal load balancer performance.
1102 js= [HW,JOY] Analog joystick
1103 See Documentation/input/joystick.txt.
1107 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1108 specifies the amount of memory usable by the kernel
1109 for non-movable allocations. The requested amount is
1110 spread evenly throughout all nodes in the system. The
1111 remaining memory in each node is used for Movable
1112 pages. In the event, a node is too small to have both
1113 kernelcore and Movable pages, kernelcore pages will
1114 take priority and other nodes will have a larger number
1115 of kernelcore pages. The Movable zone is used for the
1116 allocation of pages that may be reclaimed or moved
1117 by the page migration subsystem. This means that
1118 HugeTLB pages may not be allocated from this zone.
1119 Note that allocations like PTEs-from-HighMem still
1120 use the HighMem zone if it exists, and the Normal
1121 zone if it does not.
1123 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1124 Format: <Controller#>[,poll interval]
1125 The controller # is the number of the ehci usb debug
1126 port as it is probed via PCI. The poll interval is
1127 optional and is the number seconds in between
1128 each poll cycle to the debug port in case you need
1129 the functionality for interrupting the kernel with
1130 gdb or control-c on the dbgp connection. When
1131 not using this parameter you use sysrq-g to break into
1132 the kernel debugger.
1134 kgdboc= [KGDB,HW] kgdb over consoles.
1135 Requires a tty driver that supports console polling,
1136 or a supported polling keyboard driver (non-usb).
1137 Serial only format: <serial_device>[,baud]
1138 keyboard only format: kbd
1139 keyboard and serial format: kbd,<serial_device>[,baud]
1140 Optional Kernel mode setting:
1141 kms, kbd format: kms,kbd
1142 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1144 kgdbwait [KGDB] Stop kernel execution and enter the
1145 kernel debugger at the earliest opportunity.
1147 kmac= [MIPS] korina ethernet MAC address.
1148 Configure the RouterBoard 532 series on-chip
1149 Ethernet adapter MAC address.
1151 kmemleak= [KNL] Boot-time kmemleak enable/disable
1152 Valid arguments: on, off
1155 kstack=N [X86] Print N words from the kernel stack
1158 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1159 Default is 0 (don't ignore, but inject #GP)
1161 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1162 Default is 1 (enabled)
1164 kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
1168 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1169 Default is 1 (enabled)
1171 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1173 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1175 kvm-intel.bypass_guest_pf=
1176 [KVM,Intel] Disables bypassing of guest page faults
1177 on Intel chips. Default is 1 (enabled)
1179 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1180 (virtualized MMU) support on capable Intel chips.
1181 Default is 1 (enabled)
1183 kvm-intel.emulate_invalid_guest_state=
1184 [KVM,Intel] Enable emulation of invalid guest states
1185 Default is 0 (disabled)
1187 kvm-intel.flexpriority=
1188 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1189 Default is 1 (enabled)
1191 kvm-intel.unrestricted_guest=
1192 [KVM,Intel] Disable unrestricted guest feature
1193 (virtualized real and unpaged mode) on capable
1194 Intel chips. Default is 1 (enabled)
1196 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1197 feature (tagged TLBs) on capable Intel chips.
1198 Default is 1 (enabled)
1204 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1207 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1210 libata.dma= [LIBATA] DMA control
1211 libata.dma=0 Disable all PATA and SATA DMA
1212 libata.dma=1 PATA and SATA Disk DMA only
1213 libata.dma=2 ATAPI (CDROM) DMA only
1214 libata.dma=4 Compact Flash DMA only
1215 Combinations also work, so libata.dma=3 enables DMA
1216 for disks and CDROMs, but not CFs.
1218 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1219 libata.ignore_hpa=0 keep BIOS limits (default)
1220 libata.ignore_hpa=1 ignore limits, using full disk
1222 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1226 libata.force= [LIBATA] Force configurations. The format is comma
1227 separated list of "[ID:]VAL" where ID is
1228 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1229 matching port, link or device. Basically, it matches
1230 the ATA ID string printed on console by libata. If
1231 the whole ID part is omitted, the last PORT and DEVICE
1232 values are used. If ID hasn't been specified yet, the
1233 configuration applies to all ports, links and devices.
1235 If only DEVICE is omitted, the parameter applies to
1236 the port and all links and devices behind it. DEVICE
1237 number of 0 either selects the first device or the
1238 first fan-out link behind PMP device. It does not
1239 select the host link. DEVICE number of 15 selects the
1240 host link and device attached to it.
1242 The VAL specifies the configuration to force. As long
1243 as there's no ambiguity shortcut notation is allowed.
1244 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1245 The following configurations can be forced.
1247 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1248 Any ID with matching PORT is used.
1250 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1252 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1253 udma[/][16,25,33,44,66,100,133] notation is also
1256 * [no]ncq: Turn on or off NCQ.
1258 * nohrst, nosrst, norst: suppress hard, soft
1261 * dump_id: dump IDENTIFY data.
1263 If there are multiple matching configurations changing
1264 the same attribute, the last one is used.
1266 memblock=debug [KNL] Enable memblock debug messages.
1268 load_ramdisk= [RAM] List of ramdisks to load from floppy
1269 See Documentation/blockdev/ramdisk.txt.
1271 lockd.nlm_grace_period=P [NFS] Assign grace period.
1274 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1277 lockd.nlm_timeout=T [NFS] Assign timeout value.
1280 lockd.nlm_udpport=M [NFS] Assign UDP port.
1283 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1286 loglevel= All Kernel Messages with a loglevel smaller than the
1287 console loglevel will be printed to the console. It can
1288 also be changed with klogd or other programs. The
1289 loglevels are defined as follows:
1291 0 (KERN_EMERG) system is unusable
1292 1 (KERN_ALERT) action must be taken immediately
1293 2 (KERN_CRIT) critical conditions
1294 3 (KERN_ERR) error conditions
1295 4 (KERN_WARNING) warning conditions
1296 5 (KERN_NOTICE) normal but significant condition
1297 6 (KERN_INFO) informational
1298 7 (KERN_DEBUG) debug-level messages
1300 log_buf_len=n[KMG] Sets the size of the printk ring buffer,
1301 in bytes. n must be a power of two. The default
1302 size is set in the kernel config file.
1304 logo.nologo [FB] Disables display of the built-in Linux logo.
1305 This may be used to provide more screen space for
1306 kernel log messages and is useful when debugging
1307 kernel boot problems.
1309 lp=0 [LP] Specify parallel ports to use, e.g,
1310 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1311 lp=reset first parallel port). 'lp=0' disables the
1312 lp=auto printer driver. 'lp=reset' (which can be
1313 specified in addition to the ports) causes
1314 attached printers to be reset. Using
1315 lp=port1,port2,... specifies the parallel ports
1316 to associate lp devices with, starting with
1317 lp0. A port specification may be 'none' to skip
1318 that lp device, or a parport name such as
1319 'parport0'. Specifying 'lp=auto' instead of a
1320 port specification list means that device IDs
1321 from each port should be examined, to see if
1322 an IEEE 1284-compliant printer is attached; if
1323 so, the driver will manage that printer.
1324 See also header of drivers/char/lp.c.
1327 Sets loops_per_jiffy to given constant, thus avoiding
1328 time-consuming boot-time autodetection (up to 250 ms per
1329 CPU). 0 enables autodetection (default). To determine
1330 the correct value for your kernel, boot with normal
1331 autodetection and see what value is printed. Note that
1332 on SMP systems the preset will be applied to all CPUs,
1333 which is likely to cause problems if your CPUs need
1334 significantly divergent settings. An incorrect value
1335 will cause delays in the kernel to be wrong, leading to
1336 unpredictable I/O errors and other breakage. Although
1337 unlikely, in the extreme case this might damage your
1341 Format: <io>,<irq>,<dma>
1343 machvec= [IA64] Force the use of a particular machine-vector
1344 (machvec) in a generic kernel.
1345 Example: machvec=hpzx1_swiotlb
1347 machtype= [Loongson] Share the same kernel image file between different
1349 Example: machtype=lemote-yeeloong-2f-7inch
1351 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1352 than or equal to this physical address is ignored.
1354 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1355 should make use of. maxcpus=n : n >= 0 limits the
1356 kernel to using 'n' processors. n=0 is a special case,
1357 it is equivalent to "nosmp", which also disables
1360 max_loop= [LOOP] Maximum number of loopback devices that can
1366 mce [X86-32] Machine Check Exception
1368 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1370 md= [HW] RAID subsystems devices and level
1371 See Documentation/md.txt.
1374 Format: <first>,<last>
1375 Specifies range of consoles to be captured by the MDA.
1377 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1378 Amount of memory to be used when the kernel is not able
1379 to see the whole system memory or for test.
1380 [X86-32] Use together with memmap= to avoid physical
1381 address space collisions. Without memmap= PCI devices
1382 could be placed at addresses belonging to unused RAM.
1384 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1388 [KNL,SH] Allow user to override the default size for
1389 per-device physically contiguous DMA buffers.
1391 memmap=exactmap [KNL,X86] Enable setting of an exact
1392 E820 memory map, as specified by the user.
1393 Such memmap=exactmap lines can be constructed based on
1394 BIOS output or other requirements. See the memmap=nn@ss
1397 memmap=nn[KMG]@ss[KMG]
1398 [KNL] Force usage of a specific region of memory
1399 Region of memory to be used, from ss to ss+nn.
1401 memmap=nn[KMG]#ss[KMG]
1402 [KNL,ACPI] Mark specific memory as ACPI data.
1403 Region of memory to be used, from ss to ss+nn.
1405 memmap=nn[KMG]$ss[KMG]
1406 [KNL,ACPI] Mark specific memory as reserved.
1407 Region of memory to be used, from ss to ss+nn.
1408 Example: Exclude memory from 0x18690000-0x1869ffff
1409 memmap=64K$0x18690000
1411 memmap=0x10000$0x18690000
1413 memory_corruption_check=0/1 [X86]
1414 Some BIOSes seem to corrupt the first 64k of
1415 memory when doing things like suspend/resume.
1416 Setting this option will scan the memory
1417 looking for corruption. Enabling this will
1418 both detect corruption and prevent the kernel
1419 from using the memory being corrupted.
1420 However, its intended as a diagnostic tool; if
1421 repeatable BIOS-originated corruption always
1422 affects the same memory, you can use memmap=
1423 to prevent the kernel from using that memory.
1425 memory_corruption_check_size=size [X86]
1426 By default it checks for corruption in the low
1427 64k, making this memory unavailable for normal
1428 use. Use this parameter to scan for
1429 corruption in more or less memory.
1431 memory_corruption_check_period=seconds [X86]
1432 By default it checks for corruption every 60
1433 seconds. Use this parameter to check at some
1434 other rate. 0 disables periodic checking.
1436 memtest= [KNL,X86] Enable memtest
1438 default : 0 <disable>
1439 Specifies the number of memtest passes to be
1440 performed. Each pass selects another test
1441 pattern from a given set of patterns. Memtest
1442 fills the memory with this pattern, validates
1443 memory contents and reserves bad memory
1444 regions that are detected.
1446 meye.*= [HW] Set MotionEye Camera parameters
1447 See Documentation/video4linux/meye.txt.
1449 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1450 Multi-Function General Purpose Timers on AMD Geode
1453 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1454 the BIOS has incorrectly applied a workaround. TinyBIOS
1455 version 0.98 is known to be affected, 0.99 fixes the
1456 problem by letting the user disable the workaround.
1460 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1461 physical address is ignored.
1463 mini2440= [ARM,HW,KNL]
1464 Format:[0..2][b][c][t]
1466 MINI2440 configuration specification:
1467 0 - The attached screen is the 3.5" TFT
1468 1 - The attached screen is the 7" TFT
1469 2 - The VGA Shield is attached (1024x768)
1470 Leaving out the screen size parameter will not load
1471 the TFT driver, and the framebuffer will be left
1473 b - Enable backlight. The TFT backlight pin will be
1474 linked to the kernel VESA blanking code and a GPIO
1475 LED. This parameter is not necessary when using the
1477 c - Enable the s3c camera interface.
1478 t - Reserved for enabling touchscreen support. The
1479 touchscreen support is not enabled in the mainstream
1480 kernel as of 2.6.30, a preliminary port can be found
1481 in the "bleeding edge" mini2440 support kernel at
1482 http://repo.or.cz/w/linux-2.6/mini2440.git
1485 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1486 parameter allows control of the logging verbosity for
1487 the additional memory initialisation checks. A value
1488 of 0 disables mminit logging and a level of 4 will
1489 log everything. Information is printed at KERN_DEBUG
1490 so loglevel=8 may also need to be specified.
1493 [MOUSE] Maximum time between finger touching and
1494 leaving touchpad surface for touch to be considered
1495 a tap and be reported as a left button click (for
1496 touchpads working in absolute mode only).
1498 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1499 reporting absolute coordinates, such as tablets
1500 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1501 reporting absolute coordinates, such as tablets
1503 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1504 is similar to kernelcore except it specifies the
1505 amount of memory used for migratable allocations.
1506 If both kernelcore and movablecore is specified,
1507 then kernelcore will be at *least* the specified
1508 value but may be more. If movablecore on its own
1509 is specified, the administrator must be careful
1510 that the amount of memory usable for all allocations
1513 MTD_Partition= [MTD]
1514 Format: <name>,<region-number>,<size>,<offset>
1516 MTD_Region= [MTD] Format:
1517 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1520 See drivers/mtd/cmdlinepart.c.
1522 multitce=off [PPC] This parameter disables the use of the pSeries
1523 firmware feature for updating multiple TCE entries
1526 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1528 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1530 boundary - index of last SLC block on Flex-OneNAND.
1531 The remaining blocks are configured as MLC blocks.
1532 lock - Configure if Flex-OneNAND boundary should be locked.
1533 Once locked, the boundary cannot be changed.
1534 1 indicates lock status, 0 indicates unlock status.
1537 ARM/S3C2412 JIVE boot control
1539 See arch/arm/mach-s3c2412/mach-jive.c
1541 mtouchusb.raw_coordinates=
1542 [HW] Make the MicroTouch USB driver use raw coordinates
1543 ('y', default) or cooked coordinates ('n')
1545 mtrr_chunk_size=nn[KMG] [X86]
1546 used for mtrr cleanup. It is largest continuous chunk
1547 that could hold holes aka. UC entries.
1549 mtrr_gran_size=nn[KMG] [X86]
1550 Used for mtrr cleanup. It is granularity of mtrr block.
1552 Large value could prevent small alignment from
1555 mtrr_spare_reg_nr=n [X86]
1557 Range: 0,7 : spare reg number
1559 Used for mtrr cleanup. It is spare mtrr entries number.
1560 Set to 2 or more if your graphical card needs more.
1562 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1564 netdev= [NET] Network devices parameters
1565 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1566 Note that mem_start is often overloaded to mean
1567 something different and driver-specific.
1568 This usage is only documented in each driver source
1572 [NETFILTER] Enable connection tracking flow accounting
1573 0 to disable accounting
1574 1 to enable accounting
1577 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1578 See Documentation/filesystems/nfs/nfsroot.txt.
1580 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1581 See Documentation/filesystems/nfs/nfsroot.txt.
1583 nfsrootdebug [NFS] enable nfsroot debugging messages.
1584 See Documentation/filesystems/nfs/nfsroot.txt.
1586 nfs.callback_tcpport=
1587 [NFS] set the TCP port on which the NFSv4 callback
1588 channel should listen.
1591 [NFS] sets the pathname to the program which is used
1592 to update the NFS client cache entries.
1594 nfs.cache_getent_timeout=
1595 [NFS] sets the timeout after which an attempt to
1596 update a cache entry is deemed to have failed.
1598 nfs.idmap_cache_timeout=
1599 [NFS] set the maximum lifetime for idmapper cache
1603 [NFS] enable 64-bit inode numbers.
1604 If zero, the NFS client will fake up a 32-bit inode
1605 number for the readdir() and stat() syscalls instead
1606 of returning the full 64-bit number.
1607 The default is to return 64-bit inode numbers.
1609 nfs.nfs4_disable_idmapping=
1610 [NFSv4] When set, this option disables the NFSv4
1611 idmapper on the client, but only if the mount
1612 is using the 'sec=sys' security flavour. This may
1613 make migration from legacy NFSv2/v3 systems easier
1614 provided that the server has the appropriate support.
1615 The default is to always enable NFSv4 idmapping.
1617 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1618 when a NMI is triggered.
1619 Format: [state][,regs][,debounce][,die]
1621 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1622 Format: [panic,][nopanic,][num]
1624 0 - turn nmi_watchdog off
1625 When panic is specified, panic when an NMI watchdog
1626 timeout occurs (or 'nopanic' to override the opposite
1628 This is useful when you use a panic=... timeout and
1629 need the box quickly up again.
1631 netpoll.carrier_timeout=
1632 [NET] Specifies amount of time (in seconds) that
1633 netpoll should wait for a carrier. By default netpoll
1636 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1637 emulation library even if a 387 maths coprocessor
1641 [HW] Never suspend the console
1642 Disable suspending of consoles during suspend and
1643 hibernate operations. Once disabled, debugging
1644 messages can reach various consoles while the rest
1645 of the system is being put to sleep (ie, while
1646 debugging driver suspend/resume hooks). This may
1647 not work reliably with all consoles, but is known
1648 to work with serial and VGA consoles.
1650 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1651 caches in the slab allocator. Saves per-node memory,
1652 but will impact performance.
1656 noapic [SMP,APIC] Tells the kernel to not make use of any
1657 IOAPICs that may be present in the system.
1659 noautogroup Disable scheduler automatic task group creation.
1661 nobats [PPC] Do not use BATs for mapping kernel lowmem
1662 on "Classic" PPC cores.
1666 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1668 nodelayacct [KNL] Disable per-task delay accounting
1670 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1672 nodsp [SH] Disable hardware DSP at boot time.
1674 noefi [X86] Disable EFI runtime services support.
1679 On X86-32 available only on PAE configured kernels.
1680 noexec=on: enable non-executable mappings (default)
1681 noexec=off: disable non-executable mappings
1684 Disable SMEP (Supervisor Mode Execution Protection)
1685 even if it is supported by processor.
1688 This affects only 32-bit executables.
1689 noexec32=on: enable non-executable mappings (default)
1690 read doesn't imply executable mappings
1691 noexec32=off: disable non-executable mappings
1692 read implies executable mappings
1694 nofpu [SH] Disable hardware FPU at boot time.
1696 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1697 register save and restore. The kernel will only save
1698 legacy floating-point registers on task switch.
1700 noxsave [BUGS=X86] Disables x86 extended register state save
1701 and restore using xsave. The kernel will fallback to
1702 enabling legacy floating-point and sse state.
1704 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1705 wfi(ARM) instruction doesn't work correctly and not to
1706 use it. This is also useful when using JTAG debugger.
1708 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1709 instruction doesn't work correctly and not to
1712 no_file_caps Tells the kernel not to honor file capabilities. The
1713 only way then for a file to be executed with privilege
1714 is to be setuid root or executed by root.
1716 nohalt [IA-64] Tells the kernel not to use the power saving
1717 function PAL_HALT_LIGHT when idle. This increases
1718 power-consumption. On the positive side, it reduces
1719 interrupt wake-up latency, which may improve performance
1720 in certain environments such as networked servers or
1723 nohz= [KNL] Boottime enable/disable dynamic ticks
1724 Valid arguments: on, off
1727 noiotrap [SH] Disables trapped I/O port accesses.
1729 noirqdebug [X86-32] Disables the code which attempts to detect and
1730 disable unhandled interrupt sources.
1732 no_timer_check [X86,APIC] Disables the code which tests for
1733 broken timer IRQ sources.
1735 noisapnp [ISAPNP] Disables ISA PnP code.
1737 noinitrd [RAM] Tells the kernel not to load any configured
1740 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1742 [Deprecated - use intremap=off]
1746 nojitter [IA64] Disables jitter checking for ITC timers.
1748 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1750 no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
1753 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1755 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1757 noltlbs [PPC] Do not use large page/tlb entries for kernel
1758 lowmem mapping on PPC40x.
1760 nomca [IA-64] Disable machine check abort handling
1762 nomce [X86-32] Machine Check Exception
1764 nomfgpt [X86-32] Disable Multi-Function General Purpose
1765 Timer usage (for AMD Geode machines).
1767 nopat [X86] Disable PAT (page attribute table extension of
1768 pagetables) support.
1770 norandmaps Don't use address space randomization. Equivalent to
1771 echo 0 > /proc/sys/kernel/randomize_va_space
1773 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1775 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1776 with UP alternatives
1778 noresidual [PPC] Don't use residual data on PReP machines.
1780 noresume [SWSUSP] Disables resume and restores original swap
1783 no-scroll [VGA] Disables scrollback.
1784 This is required for the Braillex ib80-piezo Braille
1785 reader made by F.H. Papenmeier (Germany).
1789 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1791 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1792 and disable the IO APIC. legacy for "maxcpus=0".
1794 nosoftlockup [KNL] Disable the soft-lockup detector.
1796 nosync [HW,M68K] Disables sync negotiation for all devices.
1798 notsc [BUGS=X86-32] Disable Time Stamp Counter
1800 nousb [USB] Disable the USB subsystem
1802 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1806 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1808 nptcg= [IA64] Override max number of concurrent global TLB
1809 purges which is reported from either PAL_VM_SUMMARY or
1812 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1813 could support. nr_cpus=n : n >= 1 limits the kernel to
1814 supporting 'n' processors. Later in runtime you can not
1815 use hotplug cpu feature to put more cpu back to online.
1816 just like you compile the kernel NR_CPUS=n
1818 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1820 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1821 one of ['zone', 'node', 'default'] can be specified
1822 This can be set from sysctl after boot.
1823 See Documentation/sysctl/vm.txt for details.
1825 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1826 See Documentation/debugging-via-ohci1394.txt for more
1829 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1830 Rather than timing out after 20 ms if an EC
1831 command is not properly ACKed, override the length
1832 of the timeout. We have interrupts disabled while
1833 waiting for the ACK, so if this is set too high
1834 interrupts *may* be lost!
1836 omap_mux= [OMAP] Override bootloader pin multiplexing.
1837 Format: <mux_mode0.mode_name=value>...
1838 For example, to override I2C bus2:
1839 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1841 oprofile.timer= [HW]
1842 Use timer interrupt instead of performance counters
1844 oprofile.cpu_type= Force an oprofile cpu type
1845 This might be useful if you have an older oprofile
1846 userland or if you want common events.
1847 Format: { arch_perfmon }
1848 arch_perfmon: [X86] Force use of architectural
1849 perfmon on Intel CPUs instead of the
1850 CPU specific event set.
1852 oops=panic Always panic on oopses. Default is to just kill the
1853 process, but there is a small probability of
1854 deadlocking the machine.
1855 This will also cause panics on machine check exceptions.
1856 Useful together with panic=30 to trigger a reboot.
1859 See Documentation/sound/oss/oss-parameters.txt
1861 panic= [KNL] Kernel behaviour on panic: delay <timeout>
1862 seconds before rebooting
1865 parkbd.port= [HW] Parallel port number the keyboard adapter is
1866 connected to, default is 0.
1868 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1869 0 for XT, 1 for AT (default is AT).
1872 parport= [HW,PPT] Specify parallel ports. 0 disables.
1873 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1874 Use 'auto' to force the driver to use any
1875 IRQ/DMA settings detected (the default is to
1876 ignore detected IRQ/DMA settings because of
1877 possible conflicts). You can specify the base
1878 address, IRQ, and DMA settings; IRQ and DMA
1879 should be numbers, or 'auto' (for using detected
1880 settings on that particular port), or 'nofifo'
1881 (to avoid using a FIFO even if it is detected).
1882 Parallel ports are assigned in the order they
1883 are specified on the command line, starting
1886 parport_init_mode= [HW,PPT]
1887 Configure VIA parallel port to operate in
1888 a specific mode. This is necessary on Pegasos
1889 computer where firmware has no options for setting
1890 up parallel port mode and sets it to spp.
1891 Currently this function knows 686a and 8231 chips.
1892 Format: [spp|ps2|epp|ecp|ecpepp]
1895 Halt all CPUs after the first oops has been printed for
1896 the specified number of seconds. This is to be used if
1897 your oopses keep scrolling off the screen.
1902 See header of drivers/block/paride/pcd.c.
1903 See also Documentation/blockdev/paride.txt.
1905 pci=option[,option...] [PCI] various PCI subsystem options:
1906 earlydump [X86] dump PCI config space before the kernel
1908 off [X86] don't probe for the PCI bus
1909 bios [X86-32] force use of PCI BIOS, don't access
1910 the hardware directly. Use this if your machine
1911 has a non-standard PCI host bridge.
1912 nobios [X86-32] disallow use of PCI BIOS, only direct
1913 hardware access methods are allowed. Use this
1914 if you experience crashes upon bootup and you
1915 suspect they are caused by the BIOS.
1916 conf1 [X86] Force use of PCI Configuration
1918 conf2 [X86] Force use of PCI Configuration
1920 noaer [PCIE] If the PCIEAER kernel config parameter is
1921 enabled, this kernel boot option can be used to
1922 disable the use of PCIE advanced error reporting.
1923 nodomains [PCI] Disable support for multiple PCI
1924 root domains (aka PCI segments, in ACPI-speak).
1925 nommconf [X86] Disable use of MMCONFIG for PCI
1927 check_enable_amd_mmconf [X86] check for and enable
1928 properly configured MMIO access to PCI
1929 config space on AMD family 10h CPU
1930 nomsi [MSI] If the PCI_MSI kernel config parameter is
1931 enabled, this kernel boot option can be used to
1932 disable the use of MSI interrupts system-wide.
1933 noioapicquirk [APIC] Disable all boot interrupt quirks.
1934 Safety option to keep boot IRQs enabled. This
1935 should never be necessary.
1936 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1937 primary IO-APIC for bridges that cannot disable
1938 boot IRQs. This fixes a source of spurious IRQs
1939 when the system masks IRQs.
1940 noioapicreroute [APIC] Disable workaround that uses the
1941 boot IRQ equivalent of an IRQ that connects to
1942 a chipset where boot IRQs cannot be disabled.
1943 The opposite of ioapicreroute.
1944 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1945 routing table. These calls are known to be buggy
1946 on several machines and they hang the machine
1947 when used, but on other computers it's the only
1948 way to get the interrupt routing table. Try
1949 this option if the kernel is unable to allocate
1950 IRQs or discover secondary PCI buses on your
1952 rom [X86] Assign address space to expansion ROMs.
1953 Use with caution as certain devices share
1954 address decoders between ROMs and other
1956 norom [X86] Do not assign address space to
1957 expansion ROMs that do not already have
1958 BIOS assigned address ranges.
1959 nobar [X86] Do not assign address space to the
1960 BARs that weren't assigned by the BIOS.
1961 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1962 assigned automatically to PCI devices. You can
1963 make the kernel exclude IRQs of your ISA cards
1965 pirqaddr=0xAAAAA [X86] Specify the physical address
1966 of the PIRQ table (normally generated
1967 by the BIOS) if it is outside the
1968 F0000h-100000h range.
1969 lastbus=N [X86] Scan all buses thru bus #N. Can be
1970 useful if the kernel is unable to find your
1971 secondary buses and you want to tell it
1972 explicitly which ones they are.
1973 assign-busses [X86] Always assign all PCI bus
1974 numbers ourselves, overriding
1975 whatever the firmware may have done.
1976 usepirqmask [X86] Honor the possible IRQ mask stored
1977 in the BIOS $PIR table. This is needed on
1978 some systems with broken BIOSes, notably
1979 some HP Pavilion N5400 and Omnibook XE3
1980 notebooks. This will have no effect if ACPI
1981 IRQ routing is enabled.
1982 noacpi [X86] Do not use ACPI for IRQ routing
1983 or for PCI scanning.
1984 use_crs [X86] Use PCI host bridge window information
1985 from ACPI. On BIOSes from 2008 or later, this
1986 is enabled by default. If you need to use this,
1987 please report a bug.
1988 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1989 If you need to use this, please report a bug.
1990 routeirq Do IRQ routing for all PCI devices.
1991 This is normally done in pci_enable_device(),
1992 so this option is a temporary workaround
1993 for broken drivers that don't call it.
1994 skip_isa_align [X86] do not align io start addr, so can
1995 handle more pci cards
1996 firmware [ARM] Do not re-enumerate the bus but instead
1997 just use the configuration from the
1998 bootloader. This is currently used on
1999 IXP2000 systems where the bus has to be
2000 configured a certain way for adjunct CPUs.
2001 noearly [X86] Don't do any early type 1 scanning.
2002 This might help on some broken boards which
2003 machine check when some devices' config space
2004 is read. But various workarounds are disabled
2005 and some IOMMU drivers will not work.
2006 bfsort Sort PCI devices into breadth-first order.
2007 This sorting is done to get a device
2008 order compatible with older (<= 2.4) kernels.
2009 nobfsort Don't sort PCI devices into breadth-first order.
2010 cbiosize=nn[KMG] The fixed amount of bus space which is
2011 reserved for the CardBus bridge's IO window.
2012 The default value is 256 bytes.
2013 cbmemsize=nn[KMG] The fixed amount of bus space which is
2014 reserved for the CardBus bridge's memory
2015 window. The default value is 64 megabytes.
2018 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
2019 Specifies alignment and device to reassign
2020 aligned memory resources.
2021 If <order of align> is not specified,
2022 PAGE_SIZE is used as alignment.
2023 PCI-PCI bridge can be specified, if resource
2024 windows need to be expanded.
2025 ecrc= Enable/disable PCIe ECRC (transaction layer
2026 end-to-end CRC checking).
2027 bios: Use BIOS/firmware settings. This is the
2031 realloc reallocate PCI resources if allocations done by BIOS
2034 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2037 force Enable ASPM even on devices that claim not to support it.
2038 WARNING: Forcing ASPM on may cause system lockups.
2040 pcie_ports= [PCIE] PCIe ports handling:
2041 auto Ask the BIOS whether or not to use native PCIe services
2042 associated with PCIe ports (PME, hot-plug, AER). Use
2043 them only if that is allowed by the BIOS.
2044 native Use native PCIe services associated with PCIe ports
2046 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2049 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2050 nomsi Do not use MSI for native PCIe PME signaling (this makes
2051 all PCIe root ports use INTx for all services).
2053 pcmv= [HW,PCMCIA] BadgePAD 4
2056 See Documentation/blockdev/paride.txt.
2058 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2061 See arch/parisc/kernel/pdc_chassis.c
2063 percpu_alloc= Select which percpu first chunk allocator to use.
2064 Currently supported values are "embed" and "page".
2065 Archs may support subset or none of the selections.
2066 See comments in mm/percpu.c for details on each
2067 allocator. This parameter is primarily for debugging
2068 and performance comparison.
2071 See Documentation/blockdev/paride.txt.
2074 See Documentation/blockdev/paride.txt.
2076 pirq= [SMP,APIC] Manual mp-table setup
2077 See Documentation/x86/i386/IO-APIC.txt.
2079 plip= [PPT,NET] Parallel port network link
2080 Format: { parport<nr> | timid | 0 }
2081 See also Documentation/parport.txt.
2083 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2084 Override pmtimer IOPort with a hex value.
2088 Enable PNP debug messages. This depends on the
2089 CONFIG_PNP_DEBUG_MESSAGES option.
2095 { on | off | curr | res | no-curr | no-res }
2098 [ISAPNP] Exclude IRQs for the autoconfiguration
2101 [ISAPNP] Exclude DMAs for the autoconfiguration
2103 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2104 Ranges are in pairs (I/O port base and size).
2107 [ISAPNP] Exclude memory regions for the
2109 Ranges are in pairs (memory base and size).
2111 ports= [IP_VS_FTP] IPVS ftp helper module
2113 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2115 Format: <port>,<port>....
2117 print-fatal-signals=
2118 [KNL] debug: print fatal signals
2120 If enabled, warn about various signal handling
2121 related application anomalies: too many signals,
2122 too many POSIX.1 timers, fatal signals causing a
2125 If you hit the warning due to signal overflow,
2126 you might want to try "ulimit -i unlimited".
2130 printk.time= Show timing data prefixed to each printk message line
2131 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2133 processor.max_cstate= [HW,ACPI]
2134 Limit processor to maximum C-state
2135 max_cstate=9 overrides any DMI blacklist limit.
2137 processor.nocst [HW,ACPI]
2138 Ignore the _CST method to determine C-states,
2139 instead using the legacy FADT method
2141 profile= [KNL] Enable kernel profiling via /proc/profile
2142 Format: [schedule,]<number>
2143 Param: "schedule" - profile schedule points.
2144 Param: <number> - step/bucket size as a power of 2 for
2145 statistical time based profiling.
2146 Param: "sleep" - profile D-state sleeping (millisecs).
2147 Requires CONFIG_SCHEDSTATS
2148 Param: "kvm" - profile VM exits.
2150 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2152 See Documentation/blockdev/ramdisk.txt.
2154 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2155 probe for; one of (bare|imps|exps|lifebook|any).
2156 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2158 psmouse.resetafter= [HW,MOUSE]
2159 Try to reset the device after so many bad packets
2162 [HW,MOUSE] Set desired mouse resolution, in dpi.
2163 psmouse.smartscroll=
2164 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2165 0 = disabled, 1 = enabled (default).
2168 See Documentation/blockdev/paride.txt.
2171 [KNL] Number of legacy pty's. Overwrites compiled-in
2174 quiet [KNL] Disable most log messages
2179 See Documentation/md.txt.
2181 ramdisk_blocksize= [RAM]
2182 See Documentation/blockdev/ramdisk.txt.
2184 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2185 See Documentation/blockdev/ramdisk.txt.
2187 rcupdate.blimit= [KNL,BOOT]
2188 Set maximum number of finished RCU callbacks to process
2191 rcupdate.qhimark= [KNL,BOOT]
2192 Set threshold of queued
2193 RCU callbacks over which batch limiting is disabled.
2195 rcupdate.qlowmark= [KNL,BOOT]
2196 Set threshold of queued RCU callbacks below which
2197 batch limiting is re-enabled.
2201 Run specified binary instead of /init from the ramdisk,
2202 used for early userspace startup. See initrd.
2204 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2205 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2206 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2209 [KNL, SMP] Set scheduler's default relax_domain_level.
2210 See Documentation/cgroups/cpusets.txt.
2212 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2214 reservetop= [X86-32]
2216 Reserves a hole at the top of the kernel virtual
2221 Set the amount of memory to reserve for BIOS at
2222 the bottom of the address space.
2224 reset_devices [KNL] Force drivers to reset the underlying device
2225 during initialization.
2228 Specify the partition device for software suspend
2230 resume_offset= [SWSUSP]
2231 Specify the offset from the beginning of the partition
2232 given by "resume=" at which the swap header is located,
2233 in <PAGE_SIZE> units (needed only for swap files).
2234 See Documentation/power/swsusp-and-swap-files.txt
2236 hibernate= [HIBERNATION]
2237 noresume Don't check if there's a hibernation image
2238 present during boot.
2239 nocompress Don't compress/decompress hibernation images.
2241 retain_initrd [RAM] Keep initrd memory after extraction
2243 rhash_entries= [KNL,NET]
2244 Set number of hash buckets for route cache
2246 riscom8= [HW,SERIAL]
2247 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2249 ro [KNL] Mount root device read-only on boot
2251 root= [KNL] Root filesystem
2253 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2254 mount the root filesystem
2256 rootflags= [KNL] Set root filesystem mount option string
2258 rootfstype= [KNL] Set root filesystem type
2260 rootwait [KNL] Wait (indefinitely) for root device to show up.
2261 Useful for devices that are detected asynchronously
2262 (e.g. USB and MMC devices).
2264 rw [KNL] Mount root device read-write on boot
2266 S [KNL] Run init in single mode
2269 See drivers/net/irda/sa1100_ir.c.
2271 sbni= [NET] Granch SBNI12 leased line adapter
2273 sched_debug [KNL] Enables verbose scheduler debug messages.
2275 security= [SECURITY] Choose a security module to enable at boot.
2276 If this boot parameter is not specified, only the first
2277 security module asking for security registration will be
2278 loaded. An invalid security module name will be treated
2279 as if no module has been chosen.
2281 selinux= [SELINUX] Disable or enable SELinux at boot time.
2282 Format: { "0" | "1" }
2283 See security/selinux/Kconfig help text.
2286 Default value is set via kernel config option.
2287 If enabled at boot time, /selinux/disable can be used
2288 later to disable prior to initial policy load.
2290 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2291 Format: { "0" | "1" }
2292 See security/apparmor/Kconfig help text
2295 Default value is set via kernel config option.
2297 serialnumber [BUGS=X86-32]
2300 Maximal number of shapers.
2302 show_msr= [x86] show boot-time MSR settings
2303 Format: { <integer> }
2304 Show boot-time (BIOS-initialized) MSR settings.
2305 The parameter means the number of CPUs to show,
2306 for example 1 means boot CPU only.
2313 slub_debug[=options[,slabs]] [MM, SLUB]
2314 Enabling slub_debug allows one to determine the
2315 culprit if slab objects become corrupted. Enabling
2316 slub_debug can create guard zones around objects and
2317 may poison objects when not in use. Also tracks the
2318 last alloc / free. For more information see
2319 Documentation/vm/slub.txt.
2321 slub_max_order= [MM, SLUB]
2322 Determines the maximum allowed order for slabs.
2323 A high setting may cause OOMs due to memory
2324 fragmentation. For more information see
2325 Documentation/vm/slub.txt.
2327 slub_min_objects= [MM, SLUB]
2328 The minimum number of objects per slab. SLUB will
2329 increase the slab order up to slub_max_order to
2330 generate a sufficiently large slab able to contain
2331 the number of objects indicated. The higher the number
2332 of objects the smaller the overhead of tracking slabs
2333 and the less frequently locks need to be acquired.
2334 For more information see Documentation/vm/slub.txt.
2336 slub_min_order= [MM, SLUB]
2337 Determines the mininum page order for slabs. Must be
2338 lower than slub_max_order.
2339 For more information see Documentation/vm/slub.txt.
2341 slub_nomerge [MM, SLUB]
2342 Disable merging of slabs with similar size. May be
2343 necessary if there is some reason to distinguish
2344 allocs to different slabs. Debug options disable
2345 merging on their own.
2346 For more information see Documentation/vm/slub.txt.
2349 Format: <io1>[,<io2>[,...,<io8>]]
2351 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2352 attempt to substitute SMP alternatives once at boot.
2354 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2355 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2356 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2357 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2358 smsc-ircc2.ircc_irq= [HW] IRQ line
2359 smsc-ircc2.ircc_dma= [HW] DMA channel
2360 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2361 0: Toshiba Satellite 1800 (GP data pin select)
2362 1: Fast pin select (default)
2366 [KNL] Should the soft-lockup detector generate panics.
2369 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2370 See Documentation/sonypi.txt
2372 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2373 See Documentation/serial/specialix.txt.
2375 spia_io_base= [HW,MTD]
2381 Enabled the stack tracer on boot up.
2385 Set the STI (builtin display/keyboard on the HP-PARISC
2386 machines) console (graphic card) which should be used
2387 as the initial boot-console.
2388 See also comment in drivers/video/console/sticore.c.
2391 See comment in drivers/video/console/sticore.c.
2394 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2396 sunrpc.min_resvport=
2397 sunrpc.max_resvport=
2399 SunRPC servers often require that client requests
2400 originate from a privileged port (i.e. a port in the
2401 range 0 < portnr < 1024).
2402 An administrator who wishes to reserve some of these
2403 ports for other uses may adjust the range that the
2404 kernel's sunrpc client considers to be privileged
2405 using these two parameters to set the minimum and
2406 maximum port values.
2410 Control how the NFS server code allocates CPUs to
2411 service thread pools. Depending on how many NICs
2412 you have and where their interrupts are bound, this
2413 option will affect which CPUs will do NFS serving.
2414 Note: this parameter cannot be changed while the
2415 NFS server is running.
2417 auto the server chooses an appropriate mode
2418 automatically using heuristics
2419 global a single global pool contains all CPUs
2420 percpu one pool for each CPU
2421 pernode one pool for each NUMA node (equivalent
2422 to global on non-NUMA machines)
2424 sunrpc.tcp_slot_table_entries=
2425 sunrpc.udp_slot_table_entries=
2427 Sets the upper limit on the number of simultaneous
2428 RPC calls that can be sent from the client to a
2429 server. Increasing these values may allow you to
2430 improve throughput, but will also increase the
2431 amount of memory reserved for use by the client.
2434 [KNL] Enable accounting of swap in memory resource
2435 controller if no parameter or 1 is given or disable
2436 it if 0 is given (See Documentation/cgroups/memory.txt)
2438 swiotlb= [IA-64] Number of I/O TLB slabs
2442 sysfs.deprecated=0|1 [KNL]
2443 Enable/disable old style sysfs layout for old udev
2444 on older distributions. When this option is enabled
2445 very new udev will not work anymore. When this option
2446 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2447 in older udev will not work anymore.
2448 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2449 the kernel configuration.
2451 sysrq_always_enabled
2453 Ignore sysrq setting - this boot parameter will
2454 neutralize any effect of /proc/sys/kernel/sysrq.
2455 Useful for debugging.
2459 test_suspend= [SUSPEND]
2460 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2461 standby suspend) as the system sleep state to briefly
2462 enter during system startup. The system is woken from
2463 this state using a wakeup-capable RTC alarm.
2465 thash_entries= [KNL,NET]
2466 Set number of hash buckets for TCP connection
2468 thermal.act= [HW,ACPI]
2469 -1: disable all active trip points in all thermal zones
2470 <degrees C>: override all lowest active trip points
2472 thermal.crt= [HW,ACPI]
2473 -1: disable all critical trip points in all thermal zones
2474 <degrees C>: override all critical trip points
2476 thermal.nocrt= [HW,ACPI]
2477 Set to disable actions on ACPI thermal zone
2478 critical and hot trip points.
2480 thermal.off= [HW,ACPI]
2481 1: disable ACPI thermal control
2483 thermal.psv= [HW,ACPI]
2484 -1: disable all passive trip points
2485 <degrees C>: override all passive trip points to this
2488 thermal.tzp= [HW,ACPI]
2489 Specify global default ACPI thermal zone polling rate
2490 <deci-seconds>: poll all this frequency
2491 0: no polling (default)
2494 Force threading of all interrupt handlers except those
2495 marked explicitely IRQF_NO_THREAD.
2499 Specify if the kernel should make use of the cpu
2500 topology information if the hardware supports this.
2501 The scheduler will make use of this information and
2502 e.g. base its process migration decisions on it.
2507 tpm_suspend_pcr=[HW,TPM]
2508 Format: integer pcr id
2509 Specify that at suspend time, the tpm driver
2510 should extend the specified pcr with zeros,
2511 as a workaround for some chips which fail to
2512 flush the last written pcr on TPM_SaveState.
2513 This will guarantee that all the other pcrs
2516 trace_buf_size=nn[KMG]
2517 [FTRACE] will set tracing buffer size.
2519 trace_event=[event-list]
2520 [FTRACE] Set and start specified trace events in order
2521 to facilitate early boot debugging.
2522 See also Documentation/trace/events.txt
2524 tsc= Disable clocksource stability checks for TSC.
2526 [x86] reliable: mark tsc clocksource as reliable, this
2527 disables clocksource verification at runtime, as well
2528 as the stability checks done at bootup. Used to enable
2529 high-resolution timer mode on older hardware, and in
2530 virtualized environment.
2531 [x86] noirqtime: Do not use TSC to do irq accounting.
2532 Used to run time disable IRQ_TIME_ACCOUNTING on any
2533 platforms where RDTSC is slow and this accounting
2536 turbografx.map[2|3]= [HW,JOY]
2537 TurboGraFX parallel port interface
2539 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2540 See also Documentation/input/joystick-parport.txt
2542 uhash_entries= [KNL,NET]
2543 Set number of hash buckets for UDP/UDP-Lite connections
2546 [USB] Ignore overcurrent events (default N).
2547 Some badly-designed motherboards generate lots of
2548 bogus events, for ports that aren't wired to
2549 anything. Set this parameter to avoid log spamming.
2550 Note that genuine overcurrent events won't be
2554 [X86] Cause panic on unknown NMI.
2556 usbcore.autosuspend=
2557 [USB] The autosuspend time delay (in seconds) used
2558 for newly-detected USB devices (default 2). This
2559 is the time required before an idle device will be
2560 autosuspended. Devices for which the delay is set
2561 to a negative value won't be autosuspended at all.
2563 usbcore.usbfs_snoop=
2564 [USB] Set to log all usbfs traffic (default 0 = off).
2566 usbcore.blinkenlights=
2567 [USB] Set to cycle leds on hubs (default 0 = off).
2569 usbcore.old_scheme_first=
2570 [USB] Start with the old device initialization
2571 scheme (default 0 = off).
2573 usbcore.use_both_schemes=
2574 [USB] Try the other device initialization scheme
2575 if the first one fails (default 1 = enabled).
2577 usbcore.initial_descriptor_timeout=
2578 [USB] Specifies timeout for the initial 64-byte
2579 USB_REQ_GET_DESCRIPTOR request in milliseconds
2580 (default 5000 = 5.0 seconds).
2583 [USBHID] The interval which mice are to be polled at.
2585 usb-storage.delay_use=
2586 [UMS] The delay in seconds before a new device is
2587 scanned for Logical Units (default 5).
2590 [UMS] A list of quirks entries to supplement or
2591 override the built-in unusual_devs list. List
2592 entries are separated by commas. Each entry has
2593 the form VID:PID:Flags where VID and PID are Vendor
2594 and Product ID values (4-digit hex numbers) and
2595 Flags is a set of characters, each corresponding
2596 to a common usb-storage quirk flag as follows:
2597 a = SANE_SENSE (collect more than 18 bytes
2599 b = BAD_SENSE (don't collect more than 18
2600 bytes of sense data);
2601 c = FIX_CAPACITY (decrease the reported
2602 device capacity by one sector);
2603 d = NO_READ_DISC_INFO (don't use
2604 READ_DISC_INFO command);
2605 e = NO_READ_CAPACITY_16 (don't use
2606 READ_CAPACITY_16 command);
2607 h = CAPACITY_HEURISTICS (decrease the
2608 reported device capacity by one
2609 sector if the number is odd);
2610 i = IGNORE_DEVICE (don't bind to this
2612 l = NOT_LOCKABLE (don't try to lock and
2613 unlock ejectable media);
2614 m = MAX_SECTORS_64 (don't transfer more
2615 than 64 sectors = 32 KB at a time);
2616 n = INITIAL_READ10 (force a retry of the
2617 initial READ(10) command);
2618 o = CAPACITY_OK (accept the capacity
2619 reported by the device);
2620 r = IGNORE_RESIDUE (the device reports
2621 bogus residue values);
2622 s = SINGLE_LUN (the device has only one
2624 w = NO_WP_DETECT (don't test whether the
2625 medium is write-protected).
2626 Example: quirks=0419:aaf5:rl,0421:0433:rc
2629 [X86] Flags controlling user PTE allocations.
2631 nohigh = do not allocate PTE pages in
2632 HIGHMEM regardless of setting
2636 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2637 vdso=1: enable VDSO (default)
2638 vdso=0: disable VDSO mapping
2641 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2642 vdso32=1: enable 32-bit VDSO (default)
2643 vdso32=0: disable 32-bit VDSO mapping
2646 vector=percpu: enable percpu vector domain
2648 video= [FB] Frame buffer configuration
2649 See Documentation/fb/modedb.txt.
2651 vga= [BOOT,X86-32] Select a particular video mode
2652 See Documentation/x86/boot.txt and
2653 Documentation/svga.txt.
2654 Use vga=ask for menu.
2655 This is actually a boot loader parameter; the value is
2656 passed to the kernel using a special protocol.
2658 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2659 size of <nn>. This can be used to increase the
2660 minimum size (128MB on x86). It can also be used to
2661 decrease the size and leave more room for directly
2664 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2667 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2670 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2673 vt.cur_default= [VT] Default cursor shape.
2674 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2675 the parameters of the <Esc>[?A;B;Cc escape sequence;
2676 see VGA-softcursor.txt. Default: 2 = underline.
2678 vt.default_blu= [VT]
2679 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2680 Change the default blue palette of the console.
2681 This is a 16-member array composed of values
2684 vt.default_grn= [VT]
2685 Format: <green0>,<green1>,<green2>,...,<green15>
2686 Change the default green palette of the console.
2687 This is a 16-member array composed of values
2690 vt.default_red= [VT]
2691 Format: <red0>,<red1>,<red2>,...,<red15>
2692 Change the default red palette of the console.
2693 This is a 16-member array composed of values
2699 Set system-wide default UTF-8 mode for all tty's.
2700 Default is 1, i.e. UTF-8 mode is enabled for all
2701 newly opened terminals.
2703 vt.global_cursor_default=
2706 Set system-wide default for whether a cursor
2707 is shown on new VTs. Default is -1,
2708 i.e. cursors will be created by default unless
2709 overridden by individual drivers. 0 will hide
2710 cursors, 1 will display them.
2712 watchdog timers [HW,WDT] For information on watchdog timers,
2713 see Documentation/watchdog/watchdog-parameters.txt
2714 or other driver-specific files in the
2715 Documentation/watchdog/ directory.
2717 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2718 default x2apic cluster mode on platforms
2721 x86_mrst_timer= [X86-32,APBT]
2722 Choose timer option for x86 Moorestown MID platform.
2723 Two valid options are apbt timer only and lapic timer
2724 plus one apbt timer for broadcast timer.
2725 x86_mrst_timer=apbt_only | lapic_and_apbt
2727 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2728 xd_geo= See header of drivers/block/xd.c.
2730 xen_emul_unplug= [HW,X86,XEN]
2731 Unplug Xen emulated devices
2732 Format: [unplug0,][unplug1]
2733 ide-disks -- unplug primary master IDE devices
2734 aux-ide-disks -- unplug non-primary-master IDE devices
2735 nics -- unplug network devices
2736 all -- unplug all emulated devices (NICs and IDE disks)
2737 unnecessary -- unplugging emulated devices is
2738 unnecessary even if the host did not respond to
2740 never -- do not unplug even if version check succeeds
2742 xirc2ps_cs= [NET,PCMCIA]
2744 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2746 ______________________________________________________________________
2750 Add more DRM drivers.
projects / linux-flexiantxendom0-3.2.10.git / blob