4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 AVR32 AVR32 architecture is enabled.
44 AX25 Appropriate AX.25 support is enabled.
45 BLACKFIN Blackfin architecture is enabled.
46 DRM Direct Rendering Management support is enabled.
47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
51 HW Appropriate hardware is enabled.
52 IA-64 IA-64 architecture is enabled.
53 IMA Integrity measurement architecture is enabled.
54 IOSCHED More than one I/O scheduler is enabled.
55 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
56 ISAPNP ISA PnP code is enabled.
57 ISDN Appropriate ISDN support is enabled.
58 JOY Appropriate joystick support is enabled.
59 LIBATA Libata driver is enabled
60 LP Printer support is enabled.
61 LOOP Loopback device support is enabled.
62 M68k M68k architecture is enabled.
63 These options have more detailed description inside of
64 Documentation/m68k/kernel-options.txt.
65 MCA MCA bus support is enabled.
66 MDA MDA console support is enabled.
67 MOUSE Appropriate mouse support is enabled.
68 MSI Message Signaled Interrupts (PCI).
69 MTD MTD (Memory Technology Device) support is enabled.
70 NET Appropriate network support is enabled.
71 NUMA NUMA support is enabled.
72 GENERIC_TIME The generic timeofday code is enabled.
73 NFS Appropriate NFS support is enabled.
74 OSS OSS sound support is enabled.
75 PV_OPS A paravirtualized kernel is enabled.
76 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
77 PARISC The PA-RISC architecture is enabled.
78 PCI PCI bus support is enabled.
79 PCIE PCI Express support is enabled.
80 PCMCIA The PCMCIA subsystem is enabled.
81 PNP Plug & Play support is enabled.
82 PPC PowerPC architecture is enabled.
83 PPT Parallel port support is enabled.
84 PS2 Appropriate PS/2 support is enabled.
85 RAM RAM disk support is enabled.
86 ROOTPLUG The example Root Plug LSM is enabled.
87 S390 S390 architecture is enabled.
88 SCSI Appropriate SCSI support is enabled.
89 A lot of drivers has their options described inside of
91 SECURITY Different security models are enabled.
92 SELINUX SELinux support is enabled.
93 SERIAL Serial support is enabled.
94 SH SuperH architecture is enabled.
95 SMP The kernel is an SMP kernel.
96 SPARC Sparc architecture is enabled.
97 SWSUSP Software suspend (hibernation) is enabled.
98 SUSPEND System suspend states are enabled.
99 FTRACE Function tracing enabled.
100 TS Appropriate touchscreen support is enabled.
101 UMS USB Mass Storage support is enabled.
102 USB USB support is enabled.
103 USBHID USB Human Interface Device support is enabled.
104 V4L Video For Linux support is enabled.
105 VGA The VGA console has been enabled.
106 VT Virtual terminal support is enabled.
107 WDT Watchdog support is enabled.
108 XT IBM PC/XT MFM hard disk support is enabled.
109 X86-32 X86-32, aka i386 architecture is enabled.
110 X86-64 X86-64 architecture is enabled.
111 More X86-64 boot options can be found in
112 Documentation/x86/x86_64/boot-options.txt .
113 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
115 In addition, the following text indicates that the option:
117 BUGS= Relates to possible processor bugs on the said processor.
118 KNL Is a kernel start-up parameter.
119 BOOT Is a boot loader parameter.
121 Parameters denoted with BOOT are actually interpreted by the boot
122 loader, and have no meaning to the kernel directly.
123 Do not modify the syntax of boot loader parameters without extreme
124 need or coordination with <Documentation/x86/boot.txt>.
126 There are also arch-specific kernel-parameters not documented here.
127 See for example <Documentation/x86/x86_64/boot-options.txt>.
129 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
130 a trailing = on the name of any parameter states that that parameter will
131 be entered as an environment variable, whereas its absence indicates that
132 it will appear as a kernel argument readable via /proc/cmdline by programs
133 running once the system is up.
135 The number of kernel parameters is not limited, but the length of the
136 complete command line (parameters including spaces etc.) is limited to
137 a fixed number of characters. This limit depends on the architecture
138 and is between 256 and 4096 characters. It is defined in the file
139 ./include/asm/setup.h as COMMAND_LINE_SIZE.
143 Advanced Configuration and Power Interface
144 Format: { force | off | ht | strict | noirq | rsdt }
145 force -- enable ACPI if default was off
146 off -- disable ACPI if default was on
147 noirq -- do not use ACPI for IRQ routing
148 ht -- run only enough ACPI to enable Hyper Threading
149 strict -- Be less tolerant of platforms that are not
150 strictly ACPI specification compliant.
151 rsdt -- prefer RSDT over (default) XSDT
153 See also Documentation/power/pm.txt, pci=noacpi
155 acpi_apic_instance= [ACPI, IOAPIC]
157 2: use 2nd APIC table, if available
158 1,0: use 1st APIC table
161 acpi_backlight= [HW,ACPI]
162 acpi_backlight=vendor
164 If set to vendor, prefer vendor specific driver
165 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
166 of the ACPI video.ko driver.
168 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
169 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
171 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
172 debug output. Bits in debug_layer correspond to a
173 _COMPONENT in an ACPI source file, e.g.,
174 #define _COMPONENT ACPI_PCI_COMPONENT
175 Bits in debug_level correspond to a level in
176 ACPI_DEBUG_PRINT statements, e.g.,
177 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
178 The debug_level mask defaults to "info". See
179 Documentation/acpi/debug.txt for more information about
180 debug layers and levels.
182 Enable processor driver info messages:
183 acpi.debug_layer=0x20000000
184 Enable PCI/PCI interrupt routing info messages:
185 acpi.debug_layer=0x400000
186 Enable AML "Debug" output, i.e., stores to the Debug
187 object while interpreting AML:
188 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
189 Enable all messages related to ACPI hardware:
190 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
192 Some values produce so much output that the system is
193 unusable. The "log_buf_len" parameter may be useful
194 if you need to capture more output.
196 acpi_display_output= [HW,ACPI]
197 acpi_display_output=vendor
198 acpi_display_output=video
201 acpi_irq_balance [HW,ACPI]
202 ACPI will balance active IRQs
205 acpi_irq_nobalance [HW,ACPI]
206 ACPI will not move active IRQs (default)
209 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
210 Format: <irq>,<irq>...
212 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
214 Format: <irq>,<irq>...
216 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
218 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
219 Format: To spoof as Windows 98: ="Microsoft Windows"
221 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
222 acpi_osi="string1" # add string1 -- only one string
223 acpi_osi="!string2" # remove built-in string2
224 acpi_osi= # disable all strings
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
231 acpi.power_nocheck= [HW,ACPI]
232 Format: 1/0 enable/disable the check of power state.
233 On some bogus BIOS the _PSC object/_STA object of
234 power resource can't return the correct device power
235 state. In such case it is unneccessary to check its
236 power state again in power transition.
237 1 : disable the power state check
239 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
240 Format: { level | edge | high | low }
242 acpi_serialize [HW,ACPI] force serialization of AML methods
244 acpi_skip_timer_override [HW,ACPI]
245 Recognize and ignore IRQ0/pin2 Interrupt Override.
246 For broken nForce2 BIOS resulting in XT-PIC timer.
248 acpi_sleep= [HW,ACPI] Sleep options
249 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
250 old_ordering, s4_nonvs }
251 See Documentation/power/video.txt for information on
253 s3_beep is for debugging; it makes the PC's speaker beep
254 as soon as the kernel's real-mode entry point is called.
255 s4_nohwsig prevents ACPI hardware signature from being
256 used during resume from hibernation.
257 old_ordering causes the ACPI 1.0 ordering of the _PTS
258 control method, with respect to putting devices into
259 low power states, to be enforced (the ACPI 2.0 ordering
260 of _PTS is used by default).
261 s4_nonvs prevents the kernel from saving/restoring the
262 ACPI NVS memory during hibernation.
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
291 See header of drivers/scsi/advansys.c.
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
307 See Documentation/scsi/aha152x.txt.
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
313 See Documentation/scsi/aic7xxx.txt.
316 See Documentation/scsi/aic79xx.txt.
318 amd_iommu= [HW,X86-84]
319 Pass parameters to the AMD IOMMU driver in the system.
321 isolate - enable device isolation (each device, as far
322 as possible, will get its own protection
324 share - put every device behind one IOMMU into the
325 same protection domain
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
331 amijoy.map= [HW,JOY] Amiga joystick support
332 Map of devices attached to JOY0DAT and JOY1DAT
334 See also Documentation/kernel/input/joystick.txt
336 analog.map= [HW,JOY] Analog joystick and gamepad support
337 Specifies type or capabilities of an analog joystick
338 connected to one of 16 gameports
339 Format: <type1>,<type2>,..<type16>
342 Power management functions (SPARCstation-4/5 + deriv.)
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
346 APC and your system crashes randomly.
348 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
349 Change the output verbosity whilst booting
350 Format: { quiet (default) | verbose | debug }
351 Change the amount of debugging information output
352 when initialising the APIC and IO-APIC components.
354 apm= [APM] Advanced Power Management
355 See header of arch/x86/kernel/apm_32.c.
357 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
358 Format: <io>,<irq>,<nodeID>
362 atarimouse= [HW,MOUSE] Atari Mouse
364 atascsi= [HW,SCSI] Atari SCSI
366 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
367 EzKey and similar keyboards
369 atkbd.reset= [HW] Reset keyboard during initialization
371 atkbd.set= [HW] Select keyboard code set
372 Format: <int> (2 = AT (default), 3 = PS/2)
374 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
377 atkbd.softraw= [HW] Choose between synthetic and real raw mode
378 Format: <bool> (0 = real, 1 = synthetic (default))
380 atkbd.softrepeat= [HW]
381 Use software keyboard repeat
385 baycom_epp= [HW,AX25]
388 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
390 See header of drivers/net/hamradio/baycom_par.c.
392 baycom_ser_fdx= [HW,AX25]
393 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
394 Format: <io>,<irq>,<mode>[,<baud>]
395 See header of drivers/net/hamradio/baycom_ser_fdx.c.
397 baycom_ser_hdx= [HW,AX25]
398 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
399 Format: <io>,<irq>,<mode>
400 See header of drivers/net/hamradio/baycom_ser_hdx.c.
402 boot_delay= Milliseconds to delay each printk during boot.
403 Values larger than 10 seconds (10000) are changed to
407 bootmem_debug [KNL] Enable bootmem allocator debug messages.
409 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
410 bttv.radio= Most important insmod options are available as
412 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
413 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
416 See drivers/scsi/BusLogic.c, comment before function
417 BusLogic_ParseDriverOptions().
419 c101= [NET] Moxa C101 synchronous serial card
421 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
422 Sometimes CPU hardware bugs make them report the cache
423 size incorrectly. The kernel will attempt work arounds
424 to fix known problems, but for some CPUs it is not
425 possible to determine what the correct size should be.
426 This option provides an override for these situations.
429 [SECURITY] Disable capabilities. This would normally
430 be used only if an alternative security model is to be
431 configured. Potentially dangerous and should only be
432 used if you are entirely sure of the consequences.
434 ccw_timeout_log [S390]
435 See Documentation/s390/CommonIO for details.
437 cgroup_disable= [KNL] Disable a particular controller
438 Format: {name of the controller(s) to disable}
439 {Currently supported controllers - "memory"}
441 checkreqprot [SELINUX] Set initial checkreqprot flag value.
442 Format: { "0" | "1" }
443 See security/selinux/Kconfig help text.
444 0 -- check protection applied by kernel (includes
445 any implied execute protection).
446 1 -- check protection requested by application.
447 Default value is set via a kernel config option.
448 Value can be changed at runtime via
449 /selinux/checkreqprot.
452 See Documentation/s390/CommonIO for details.
454 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
456 Forces specified clocksource (if available) to be used
457 when calculating gettimeofday(). If specified
458 clocksource is not available, it defaults to PIT.
459 Format: { pit | tsc | cyclone | pmtmr }
461 clocksource= [GENERIC_TIME] Override the default clocksource
463 Override the default clocksource and use the clocksource
464 with the name specified.
465 Some clocksource names to choose from, depending on
467 [all] jiffies (this is the base, fallback clocksource)
469 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
470 pxa_timer,timer3,32k_counter,timer0_1
472 [X86-32] pit,hpet,tsc,vmi-timer;
473 scx200_hrt on Geode; cyclone on IBM x440
481 clearcpuid=BITNUM [X86]
482 Disable CPUID feature X for the kernel. See
483 arch/x86/include/asm/cpufeature.h for the valid bit
484 numbers. Note the Linux specific bits are not necessarily
485 stable over kernel options, but the vendor specific
487 Also note that user programs calling CPUID directly
488 or using the feature without checking anything
489 will still see it. This just prevents it from
490 being used by the kernel or shown in /proc/cpuinfo.
491 Also note the kernel might malfunction if you disable
494 code_bytes [X86] How many bytes of object code to print
499 com20020= [HW,NET] ARCnet - COM20020 chipset
501 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
503 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
507 ARCnet - COM90xx chipset (memory-mapped buffers)
508 Format: <io>[,<irq>[,<memstart>]]
510 condev= [HW,S390] console device
513 console= [KNL] Output console device and options.
515 tty<n> Use the virtual console device <n>.
519 Use the specified serial port. The options are of
520 the form "bbbbpnf", where "bbbb" is the baud rate,
521 "p" is parity ("n", "o", or "e"), "n" is number of
522 bits, and "f" is flow control ("r" for RTS or
523 omit it). Default is "9600n8".
525 See Documentation/serial-console.txt for more
527 Documentation/networking/netconsole.txt for an
530 uart[8250],io,<addr>[,options]
531 uart[8250],mmio,<addr>[,options]
532 Start an early, polled-mode console on the 8250/16550
533 UART at the specified I/O port or MMIO address,
534 switching to the matching ttyS device later. The
535 options are the same as for ttyS, above.
537 If the device connected to the port is not a TTY but a braille
538 device, prepend "brl," before the device type, for instance
540 For now, only VisioBraille is supported.
543 [KNL] Change the default value for
544 /proc/<pid>/coredump_filter.
545 See also Documentation/filesystems/proc.txt.
547 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
549 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
551 crashkernel=nn[KMG]@ss[KMG]
552 [KNL] Reserve a chunk of physical memory to
553 hold a kernel to switch to with kexec on panic.
555 crashkernel=range1:size1[,range2:size2,...][@offset]
556 [KNL] Same as above, but depends on the memory
557 in the running system. The syntax of range is
558 start-[end] where start and end are both
559 a memory unit (amount[KMG]). See also
560 Documentation/kdump/kdump.txt for a example.
565 cs89x0_media= [HW,NET]
566 Format: { rj45 | aui | bnc }
569 See header of drivers/s390/block/dasd_devmap.c.
571 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
572 (one device per port)
573 Format: <port#>,<type>
574 See also Documentation/input/joystick-parport.txt
576 debug [KNL] Enable kernel debugging (events log level).
579 [KNL] verbose self-tests
581 Print debugging info while doing the locking API
583 We default to 0 (no extra messages), setting it to
584 1 will print _a lot_ more information - normally
585 only useful to kernel developers.
587 debug_objects [KNL] Enable object debugging
590 [KNL] Disable object debugging
592 debugpat [X86] Enable PAT debugging
594 decnet.addr= [HW,NET]
595 Format: <area>[,<node>]
596 See also Documentation/networking/decnet.txt.
599 [same as hugepagesz=] The size of the default
600 HugeTLB page size. This is the size represented by
601 the legacy /proc/ hugepages APIs, used for SHM, and
602 default size when mounting hugetlbfs filesystems.
603 Defaults to the default architecture's huge page size
607 Set number of hash buckets for dentry cache.
610 IO parameters + enable/disable command.
612 digiepca= [HW,SERIAL]
613 See drivers/char/README.epca and
614 Documentation/serial/digiepca.txt.
616 disable_mtrr_cleanup [X86]
617 The kernel tries to adjust MTRR layout from continuous
618 to discrete, to make X server driver able to add WB
619 entry later. This parameter disables that.
621 disable_mtrr_trim [X86, Intel and AMD only]
622 By default the kernel will trim any uncacheable
623 memory out of your available memory pool based on
624 MTRR settings. This parameter disables that behavior,
625 possibly causing your machine to run very slowly.
627 disable_timer_pin_1 [X86]
628 Disable PIN 1 of APIC timer
629 Can be useful to work around chipset bugs.
631 dmasound= [HW,OSS] Sound subsystem buffers
633 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
634 this option disables the debugging code at boot.
636 dma_debug_entries=<number>
637 This option allows to tune the number of preallocated
638 entries for DMA-API debugging code. One entry is
639 required per DMA-API allocation. Use this if the
640 DMA-API debugging code disables itself because the
641 architectural default is too low.
643 dma_debug_driver=<driver_name>
644 With this option the DMA-API debugging driver
645 filter feature can be enabled at boot time. Just
646 pass the driver to filter for as the parameter.
647 The filter can be disabled or changed to another
648 driver later using sysfs.
654 dynamic_printk Enables pr_debug()/dev_dbg() calls if
655 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
656 These can also be switched on/off via
657 <debugfs>/dynamic_printk/modules
659 earlycon= [KNL] Output early console device and options.
660 uart[8250],io,<addr>[,options]
661 uart[8250],mmio,<addr>[,options]
662 Start an early, polled-mode console on the 8250/16550
663 UART at the specified I/O port or MMIO address.
664 The options are the same as for ttyS, above.
666 earlyprintk= [X86,SH,BLACKFIN]
668 earlyprintk=serial[,ttySn[,baudrate]]
671 Append ",keep" to not disable it when the real console
674 Only vga or serial or usb debug port at a time.
676 Currently only ttyS0 and ttyS1 are supported.
678 Interaction with the standard serial driver is not
681 The VGA output is eventually overwritten by the real
687 Format: {"off" | "on" | "skip[mbr]"}
689 eisa_irq_edge= [PARISC,HW]
690 See header of drivers/parisc/eisa.c.
693 See comment before function elanfreq_setup() in
694 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
697 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
698 See Documentation/block/as-iosched.txt and
699 Documentation/block/deadline-iosched.txt for details.
701 elfcorehdr= [IA64,PPC,SH,X86]
702 Specifies physical address of start of kernel core
703 image elf header. Generally kexec loader will
704 pass this option to capture kernel.
705 See Documentation/kdump/kdump.txt for details.
707 enable_mtrr_cleanup [X86]
708 The kernel tries to adjust MTRR layout from continuous
709 to discrete, to make X server driver able to add WB
710 entry later. This parameter enables that.
712 enable_timer_pin_1 [X86]
713 Enable PIN 1 of APIC timer
714 Can be useful to work around chipset bugs
715 (in particular on some ATI chipsets).
716 The kernel tries to set a reasonable default.
718 enforcing [SELINUX] Set initial enforcing status.
720 See security/selinux/Kconfig help text.
721 0 -- permissive (log only, no denials).
722 1 -- enforcing (deny and log).
724 Value can be changed at runtime via /selinux/enforce.
726 ether= [HW,NET] Ethernet cards parameters
727 This option is obsoleted by the "netdev=" option, which
728 has equivalent usage. See its documentation for details.
730 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
735 fail_make_request=[KNL]
736 General fault injection mechanism.
737 Format: <interval>,<probability>,<space>,<times>
738 See also /Documentation/fault-injection/.
741 See header of drivers/scsi/fd_mcs.c.
744 See header of drivers/scsi/fdomain.c.
747 See Documentation/blockdev/floppy.txt.
749 force_pal_cache_flush
750 [IA-64] Avoid check_sal_cache_flush which may hang on
751 buggy SAL_CACHE_FLUSH implementations. Using this
752 parameter will force ia64_sal_cache_flush to call
753 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
756 [FTRACE] will set and start the specified tracer
757 as early as possible in order to facilitate early
761 [FTRACE] will dump the trace buffers on oops.
763 ftrace_filter=[function-list]
764 [FTRACE] Limit the functions traced by the function
765 tracer at boot up. function-list is a comma separated
766 list of functions. This list can be changed at run
767 time by the set_ftrace_filter file in the debugfs
770 ftrace_notrace=[function-list]
771 [FTRACE] Do not trace the functions specified in
772 function-list. This list can be changed at run time
773 by the set_ftrace_notrace file in the debugfs
777 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
778 support via parallel port (up to 5 devices per port)
779 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
780 See also Documentation/input/joystick-parport.txt
784 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
789 See header of drivers/scsi/gdth.c.
791 gpt [EFI] Forces disk with valid GPT signature but
792 invalid Protective MBR to be treated as GPT.
796 hashdist= [KNL,NUMA] Large hashes allocated during boot
797 are distributed across NUMA nodes. Defaults on
798 for 64bit NUMA, off otherwise.
799 Format: 0 | 1 (for off | on)
801 hcl= [IA-64] SGI's Hardware Graph compatibility layer
803 hd= [EIDE] (E)IDE hard drive subsystem geometry
804 Format: <cyl>,<head>,<sect>
806 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
807 size of <nn>. This works even on boxes that have no
808 highmem otherwise. This also works to reduce highmem
809 size on bigger boxes.
811 highres= [KNL] Enable/disable high resolution timer mode.
812 Valid parameters: "on", "off"
816 See Documentation/isdn/README.HiSax.
820 hpet= [X86-32,HPET] option to control HPET usage
821 Format: { enable (default) | disable | force |
823 disable: disable HPET and use PIT instead
824 force: allow force enabled of undocumented chips (ICH4,
826 verbose: show contents of HPET registers during setup
828 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
829 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
830 On x86-64 and powerpc, this option can be specified
831 multiple times interleaved with hugepages= to reserve
832 huge pages of different sizes. Valid pages sizes on
833 x86-64 are 2M (when the CPU supports "pse") and 1G
834 (when the CPU supports the "pdpe1gb" cpuinfo flag)
835 Note that 1GB pages can only be allocated at boot time
836 using hugepages= and not freed afterwards.
838 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
839 terminal devices. Valid values: 0..8
840 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
841 If specified, z/VM IUCV HVC accepts connections
842 from listed z/VM user IDs only.
844 i2c_bus= [HW] Override the default board specific I2C bus speed
845 or register an additional I2C bus that is not
846 registered from board initialization code.
850 i8042.debug [HW] Toggle i8042 debug mode
851 i8042.direct [HW] Put keyboard port into non-translated mode
852 i8042.dumbkbd [HW] Pretend that controller can only read data from
853 keyboard and cannot control its state
854 (Don't attempt to blink the leds)
855 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
856 i8042.nokbd [HW] Don't check/create keyboard port
857 i8042.noloop [HW] Disable the AUX Loopback command while probing
859 i8042.nomux [HW] Don't check presence of an active multiplexing
861 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
864 [HW] Frequency with which keyboard LEDs should blink
865 when kernel panics (default is 0.5 sec)
866 i8042.reset [HW] Reset the controller during init and cleanup
867 i8042.unlock [HW] Unlock (ignore) the keylock
871 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
872 indicates that the driver is running on unsupported
874 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
875 does not match list of supported models.
877 [HW] Report power status in /proc/i8k
878 (disabled by default)
879 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
882 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
883 See Documentation/mca.txt.
886 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
888 ide-core.nodma= [HW] (E)IDE subsystem
889 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
890 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
891 .cdrom .chs .ignore_cable are additional options
892 See Documentation/ide/ide.txt.
894 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
895 Claim all unknown PCI IDE storage controllers.
898 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
899 Poll forces a polling idle loop that can slightly
900 improve the performance of waking up a idle CPU, but
901 will use a lot of power and make the system run hot.
903 idle=mwait: On systems which support MONITOR/MWAIT but
904 the kernel chose to not use it because it doesn't save
905 as much power as a normal idle loop, use the
906 MONITOR/MWAIT idle loop anyways. Performance should be
907 the same as idle=poll.
908 idle=halt: Halt is forced to be used for CPU idle.
909 In such case C2/C3 won't be used again.
910 idle=nomwait: Disable mwait for CPU C-states
912 ignore_loglevel [KNL]
913 Ignore loglevel setting - this will print /all/
914 kernel messages to the console. Useful for debugging.
917 Set number of hash buckets for inode cache.
920 Format: { "0" | "1" }
921 0 -- integrity auditing messages. (Default)
922 1 -- enable informational integrity auditing messages.
925 Formt: { "sha1" | "md5" }
929 Load a policy which meets the needs of the Trusted
930 Computing Base. This means IMA will measure all
931 programs exec'd, files mmap'd for exec, and all files
932 opened for read by uid=0.
935 See header of drivers/scsi/in2000.c.
939 Run specified binary instead of /sbin/init as init
942 initcall_debug [KNL] Trace initcalls as they are executed. Useful
943 for working out where the kernel is dying during
946 initrd= [BOOT] Specify the location of the initial ramdisk
948 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
951 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
953 Enable intel iommu driver.
955 Disable intel iommu driver.
956 igfx_off [Default Off]
957 By default, gfx is mapped as normal device. If a gfx
958 device has a dedicated DMAR unit, the DMAR unit is
959 bypassed by not enabling DMAR with this option. In
960 this case, gfx device will use physical address for
963 With this option iommu will not optimize to look
964 for io virtual address below 32 bit forcing dual
965 address cycle on pci bus for cards supporting greater
966 than 32 bit addressing. The default is to look
967 for translation below 32 bit and if not available
968 then look in the higher range.
970 With this option on every unmap_single operation will
971 result in a hardware IOTLB flush operation as opposed
972 to batching them for performance.
976 iomem= Disable strict checking of access to MMIO memory
977 strict regions from userspace.
992 io7= [HW] IO7 for Marvel based alpha systems
993 See comment before marvel_specify_io7 in
994 arch/alpha/kernel/core_marvel.c.
996 io_delay= [X86] I/O delay method
998 Standard port 0x80 based delay
1000 Alternate port 0xed based delay (needed on some systems)
1002 Simple two microseconds delay
1007 See Documentation/filesystems/nfsroot.txt.
1009 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1010 See comment before ip2_setup() in
1011 drivers/char/ip2/ip2base.c.
1013 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1014 See header of drivers/scsi/ips.c.
1017 When an interrupt is not handled search all handlers
1018 for it. Intended to get systems with badly broken
1022 When an interrupt is not handled search all handlers
1023 for it. Also check all handlers each timer
1024 interrupt. Intended to get systems with badly broken
1028 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1030 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1032 <cpu number>,...,<cpu number>
1034 <cpu number>-<cpu number>
1035 (must be a positive range in ascending order)
1037 <cpu number>,...,<cpu number>-<cpu number>
1039 This option can be used to specify one or more CPUs
1040 to isolate from the general SMP balancing and scheduling
1041 algorithms. You can move a process onto or off an
1042 "isolated" CPU via the CPU affinity syscalls or cpuset.
1043 <cpu number> begins at 0 and the maximum value is
1044 "number of CPUs in system - 1".
1046 This option is the preferred way to isolate CPUs. The
1047 alternative -- manually setting the CPU mask of all
1048 tasks in the system -- can cause problems and
1049 suboptimal load balancer performance.
1053 js= [HW,JOY] Analog joystick
1054 See Documentation/input/joystick.txt.
1058 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1059 specifies the amount of memory usable by the kernel
1060 for non-movable allocations. The requested amount is
1061 spread evenly throughout all nodes in the system. The
1062 remaining memory in each node is used for Movable
1063 pages. In the event, a node is too small to have both
1064 kernelcore and Movable pages, kernelcore pages will
1065 take priority and other nodes will have a larger number
1066 of kernelcore pages. The Movable zone is used for the
1067 allocation of pages that may be reclaimed or moved
1068 by the page migration subsystem. This means that
1069 HugeTLB pages may not be allocated from this zone.
1070 Note that allocations like PTEs-from-HighMem still
1071 use the HighMem zone if it exists, and the Normal
1072 zone if it does not.
1074 kgdboc= [HW] kgdb over consoles.
1075 Requires a tty driver that supports console polling.
1076 (only serial supported for now)
1077 Format: <serial_device>[,baud]
1079 kmac= [MIPS] korina ethernet MAC address.
1080 Configure the RouterBoard 532 series on-chip
1081 Ethernet adapter MAC address.
1083 kmemleak= [KNL] Boot-time kmemleak enable/disable
1084 Valid arguments: on, off
1087 kstack=N [X86] Print N words from the kernel stack
1094 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1097 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1100 libata.dma= [LIBATA] DMA control
1101 libata.dma=0 Disable all PATA and SATA DMA
1102 libata.dma=1 PATA and SATA Disk DMA only
1103 libata.dma=2 ATAPI (CDROM) DMA only
1104 libata.dma=4 Compact Flash DMA only
1105 Combinations also work, so libata.dma=3 enables DMA
1106 for disks and CDROMs, but not CFs.
1108 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1112 libata.force= [LIBATA] Force configurations. The format is comma
1113 separated list of "[ID:]VAL" where ID is
1114 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1115 matching port, link or device. Basically, it matches
1116 the ATA ID string printed on console by libata. If
1117 the whole ID part is omitted, the last PORT and DEVICE
1118 values are used. If ID hasn't been specified yet, the
1119 configuration applies to all ports, links and devices.
1121 If only DEVICE is omitted, the parameter applies to
1122 the port and all links and devices behind it. DEVICE
1123 number of 0 either selects the first device or the
1124 first fan-out link behind PMP device. It does not
1125 select the host link. DEVICE number of 15 selects the
1126 host link and device attached to it.
1128 The VAL specifies the configuration to force. As long
1129 as there's no ambiguity shortcut notation is allowed.
1130 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1131 The following configurations can be forced.
1133 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1134 Any ID with matching PORT is used.
1136 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1138 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1139 udma[/][16,25,33,44,66,100,133] notation is also
1142 * [no]ncq: Turn on or off NCQ.
1144 * nohrst, nosrst, norst: suppress hard, soft
1147 If there are multiple matching configurations changing
1148 the same attribute, the last one is used.
1150 lmb=debug [KNL] Enable lmb debug messages.
1152 load_ramdisk= [RAM] List of ramdisks to load from floppy
1153 See Documentation/blockdev/ramdisk.txt.
1155 lockd.nlm_grace_period=P [NFS] Assign grace period.
1158 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1161 lockd.nlm_timeout=T [NFS] Assign timeout value.
1164 lockd.nlm_udpport=M [NFS] Assign UDP port.
1167 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1170 loglevel= All Kernel Messages with a loglevel smaller than the
1171 console loglevel will be printed to the console. It can
1172 also be changed with klogd or other programs. The
1173 loglevels are defined as follows:
1175 0 (KERN_EMERG) system is unusable
1176 1 (KERN_ALERT) action must be taken immediately
1177 2 (KERN_CRIT) critical conditions
1178 3 (KERN_ERR) error conditions
1179 4 (KERN_WARNING) warning conditions
1180 5 (KERN_NOTICE) normal but significant condition
1181 6 (KERN_INFO) informational
1182 7 (KERN_DEBUG) debug-level messages
1184 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1185 Format: { n | nk | nM }
1186 n must be a power of two. The default size
1187 is set in the kernel config file.
1189 logo.nologo [FB] Disables display of the built-in Linux logo.
1190 This may be used to provide more screen space for
1191 kernel log messages and is useful when debugging
1192 kernel boot problems.
1194 lp=0 [LP] Specify parallel ports to use, e.g,
1195 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1196 lp=reset first parallel port). 'lp=0' disables the
1197 lp=auto printer driver. 'lp=reset' (which can be
1198 specified in addition to the ports) causes
1199 attached printers to be reset. Using
1200 lp=port1,port2,... specifies the parallel ports
1201 to associate lp devices with, starting with
1202 lp0. A port specification may be 'none' to skip
1203 that lp device, or a parport name such as
1204 'parport0'. Specifying 'lp=auto' instead of a
1205 port specification list means that device IDs
1206 from each port should be examined, to see if
1207 an IEEE 1284-compliant printer is attached; if
1208 so, the driver will manage that printer.
1209 See also header of drivers/char/lp.c.
1212 Sets loops_per_jiffy to given constant, thus avoiding
1213 time-consuming boot-time autodetection (up to 250 ms per
1214 CPU). 0 enables autodetection (default). To determine
1215 the correct value for your kernel, boot with normal
1216 autodetection and see what value is printed. Note that
1217 on SMP systems the preset will be applied to all CPUs,
1218 which is likely to cause problems if your CPUs need
1219 significantly divergent settings. An incorrect value
1220 will cause delays in the kernel to be wrong, leading to
1221 unpredictable I/O errors and other breakage. Although
1222 unlikely, in the extreme case this might damage your
1226 Format: <io>,<irq>,<dma>
1228 mac5380= [HW,SCSI] Format:
1229 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1231 machvec= [IA64] Force the use of a particular machine-vector
1232 (machvec) in a generic kernel.
1233 Example: machvec=hpzx1_swiotlb
1235 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1236 than or equal to this physical address is ignored.
1238 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1239 should make use of. maxcpus=n : n >= 0 limits the
1240 kernel to using 'n' processors. n=0 is a special case,
1241 it is equivalent to "nosmp", which also disables
1244 max_loop= [LOOP] Maximum number of loopback devices that can
1248 max_luns= [SCSI] Maximum number of LUNs to probe.
1249 Should be between 1 and 2^32-1.
1252 [SCSI] Maximum number of LUNs received.
1253 Should be between 1 and 16384.
1257 mce [X86-32] Machine Check Exception
1259 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1261 md= [HW] RAID subsystems devices and level
1262 See Documentation/md.txt.
1265 Format: <first>,<last>
1266 Specifies range of consoles to be captured by the MDA.
1268 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1269 Amount of memory to be used when the kernel is not able
1270 to see the whole system memory or for test.
1271 [X86-32] Use together with memmap= to avoid physical
1272 address space collisions. Without memmap= PCI devices
1273 could be placed at addresses belonging to unused RAM.
1275 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1279 [KNL,SH] Allow user to override the default size for
1280 per-device physically contiguous DMA buffers.
1282 memmap=exactmap [KNL,X86] Enable setting of an exact
1283 E820 memory map, as specified by the user.
1284 Such memmap=exactmap lines can be constructed based on
1285 BIOS output or other requirements. See the memmap=nn@ss
1288 memmap=nn[KMG]@ss[KMG]
1289 [KNL] Force usage of a specific region of memory
1290 Region of memory to be used, from ss to ss+nn.
1292 memmap=nn[KMG]#ss[KMG]
1293 [KNL,ACPI] Mark specific memory as ACPI data.
1294 Region of memory to be used, from ss to ss+nn.
1296 memmap=nn[KMG]$ss[KMG]
1297 [KNL,ACPI] Mark specific memory as reserved.
1298 Region of memory to be used, from ss to ss+nn.
1299 Example: Exclude memory from 0x18690000-0x1869ffff
1300 memmap=64K$0x18690000
1302 memmap=0x10000$0x18690000
1304 memory_corruption_check=0/1 [X86]
1305 Some BIOSes seem to corrupt the first 64k of
1306 memory when doing things like suspend/resume.
1307 Setting this option will scan the memory
1308 looking for corruption. Enabling this will
1309 both detect corruption and prevent the kernel
1310 from using the memory being corrupted.
1311 However, its intended as a diagnostic tool; if
1312 repeatable BIOS-originated corruption always
1313 affects the same memory, you can use memmap=
1314 to prevent the kernel from using that memory.
1316 memory_corruption_check_size=size [X86]
1317 By default it checks for corruption in the low
1318 64k, making this memory unavailable for normal
1319 use. Use this parameter to scan for
1320 corruption in more or less memory.
1322 memory_corruption_check_period=seconds [X86]
1323 By default it checks for corruption every 60
1324 seconds. Use this parameter to check at some
1325 other rate. 0 disables periodic checking.
1327 memtest= [KNL,X86] Enable memtest
1329 default : 0 <disable>
1330 Specifies the number of memtest passes to be
1331 performed. Each pass selects another test
1332 pattern from a given set of patterns. Memtest
1333 fills the memory with this pattern, validates
1334 memory contents and reserves bad memory
1335 regions that are detected.
1337 meye.*= [HW] Set MotionEye Camera parameters
1338 See Documentation/video4linux/meye.txt.
1340 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1341 Multi-Function General Purpose Timers on AMD Geode
1344 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1345 the BIOS has incorrectly applied a workaround. TinyBIOS
1346 version 0.98 is known to be affected, 0.99 fixes the
1347 problem by letting the user disable the workaround.
1351 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1352 physical address is ignored.
1355 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1356 parameter allows control of the logging verbosity for
1357 the additional memory initialisation checks. A value
1358 of 0 disables mminit logging and a level of 4 will
1359 log everything. Information is printed at KERN_DEBUG
1360 so loglevel=8 may also need to be specified.
1363 [MOUSE] Maximum time between finger touching and
1364 leaving touchpad surface for touch to be considered
1365 a tap and be reported as a left button click (for
1366 touchpads working in absolute mode only).
1368 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1369 reporting absolute coordinates, such as tablets
1370 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1371 reporting absolute coordinates, such as tablets
1373 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1374 is similar to kernelcore except it specifies the
1375 amount of memory used for migratable allocations.
1376 If both kernelcore and movablecore is specified,
1377 then kernelcore will be at *least* the specified
1378 value but may be more. If movablecore on its own
1379 is specified, the administrator must be careful
1380 that the amount of memory usable for all allocations
1386 MTD_Partition= [MTD]
1387 Format: <name>,<region-number>,<size>,<offset>
1389 MTD_Region= [MTD] Format:
1390 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1393 See drivers/mtd/cmdlinepart.c.
1396 ARM/S3C2412 JIVE boot control
1398 See arch/arm/mach-s3c2412/mach-jive.c
1400 mtouchusb.raw_coordinates=
1401 [HW] Make the MicroTouch USB driver use raw coordinates
1402 ('y', default) or cooked coordinates ('n')
1404 mtrr_chunk_size=nn[KMG] [X86]
1405 used for mtrr cleanup. It is largest continuous chunk
1406 that could hold holes aka. UC entries.
1408 mtrr_gran_size=nn[KMG] [X86]
1409 Used for mtrr cleanup. It is granularity of mtrr block.
1411 Large value could prevent small alignment from
1414 mtrr_spare_reg_nr=n [X86]
1416 Range: 0,7 : spare reg number
1418 Used for mtrr cleanup. It is spare mtrr entries number.
1419 Set to 2 or more if your graphical card needs more.
1421 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1424 See header of drivers/scsi/NCR_D700.c.
1428 ncr53c400= [HW,SCSI]
1430 ncr53c400a= [HW,SCSI]
1432 ncr53c406a= [HW,SCSI]
1434 ncr53c8xx= [HW,SCSI]
1436 netdev= [NET] Network devices parameters
1437 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1438 Note that mem_start is often overloaded to mean
1439 something different and driver-specific.
1440 This usage is only documented in each driver source
1444 [NETFILTER] Enable connection tracking flow accounting
1445 0 to disable accounting
1446 1 to enable accounting
1447 Default value depends on CONFIG_NF_CT_ACCT that is
1448 going to be removed in 2.6.29.
1451 See Documentation/filesystems/nfsroot.txt.
1453 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1454 See Documentation/filesystems/nfsroot.txt.
1456 nfs.callback_tcpport=
1457 [NFS] set the TCP port on which the NFSv4 callback
1458 channel should listen.
1460 nfs.idmap_cache_timeout=
1461 [NFS] set the maximum lifetime for idmapper cache
1465 [NFS] enable 64-bit inode numbers.
1466 If zero, the NFS client will fake up a 32-bit inode
1467 number for the readdir() and stat() syscalls instead
1468 of returning the full 64-bit number.
1469 The default is to return 64-bit inode numbers.
1471 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1472 when a NMI is triggered.
1473 Format: [state][,regs][,debounce][,die]
1475 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1476 Format: [panic,][num]
1478 0 - turn nmi_watchdog off
1479 1 - use the IO-APIC timer for the NMI watchdog
1480 2 - use the local APIC for the NMI watchdog using
1481 a performance counter. Note: This will use one
1482 performance counter and the local APIC's performance
1484 When panic is specified, panic when an NMI watchdog
1486 This is useful when you use a panic=... timeout and
1487 need the box quickly up again.
1488 Instead of 1 and 2 it is possible to use the following
1489 symbolic names: lapic and ioapic
1490 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1492 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1493 emulation library even if a 387 maths coprocessor
1497 [HW] Never suspend the console
1498 Disable suspending of consoles during suspend and
1499 hibernate operations. Once disabled, debugging
1500 messages can reach various consoles while the rest
1501 of the system is being put to sleep (ie, while
1502 debugging driver suspend/resume hooks). This may
1503 not work reliably with all consoles, but is known
1504 to work with serial and VGA consoles.
1506 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1507 caches in the slab allocator. Saves per-node memory,
1508 but will impact performance.
1512 noapic [SMP,APIC] Tells the kernel to not make use of any
1513 IOAPICs that may be present in the system.
1515 nobats [PPC] Do not use BATs for mapping kernel lowmem
1516 on "Classic" PPC cores.
1520 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1522 nodelayacct [KNL] Disable per-task delay accounting
1524 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1526 nodsp [SH] Disable hardware DSP at boot time.
1528 noefi [X86] Disable EFI runtime services support.
1533 On X86-32 available only on PAE configured kernels.
1534 noexec=on: enable non-executable mappings (default)
1535 noexec=off: disable non-executable mappings
1538 This affects only 32-bit executables.
1539 noexec32=on: enable non-executable mappings (default)
1540 read doesn't imply executable mappings
1541 noexec32=off: disable non-executable mappings
1542 read implies executable mappings
1544 nofpu [SH] Disable hardware FPU at boot time.
1546 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1547 register save and restore. The kernel will only save
1548 legacy floating-point registers on task switch.
1550 noxsave [BUGS=X86] Disables x86 extended register state save
1551 and restore using xsave. The kernel will fallback to
1552 enabling legacy floating-point and sse state.
1554 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1555 wfi(ARM) instruction doesn't work correctly and not to
1556 use it. This is also useful when using JTAG debugger.
1558 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1559 instruction doesn't work correctly and not to
1562 no_file_caps Tells the kernel not to honor file capabilities. The
1563 only way then for a file to be executed with privilege
1564 is to be setuid root or executed by root.
1566 nohalt [IA-64] Tells the kernel not to use the power saving
1567 function PAL_HALT_LIGHT when idle. This increases
1568 power-consumption. On the positive side, it reduces
1569 interrupt wake-up latency, which may improve performance
1570 in certain environments such as networked servers or
1573 nohz= [KNL] Boottime enable/disable dynamic ticks
1574 Valid arguments: on, off
1577 noiotrap [SH] Disables trapped I/O port accesses.
1579 noirqdebug [X86-32] Disables the code which attempts to detect and
1580 disable unhandled interrupt sources.
1582 no_timer_check [X86,APIC] Disables the code which tests for
1583 broken timer IRQ sources.
1585 noisapnp [ISAPNP] Disables ISA PnP code.
1587 noinitrd [RAM] Tells the kernel not to load any configured
1590 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1595 nojitter [IA64] Disables jitter checking for ITC timers.
1597 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1599 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1601 noltlbs [PPC] Do not use large page/tlb entries for kernel
1602 lowmem mapping on PPC40x.
1604 nomca [IA-64] Disable machine check abort handling
1606 nomce [X86-32] Machine Check Exception
1608 nomfgpt [X86-32] Disable Multi-Function General Purpose
1609 Timer usage (for AMD Geode machines).
1611 norandmaps Don't use address space randomization. Equivalent to
1612 echo 0 > /proc/sys/kernel/randomize_va_space
1614 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1616 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1617 with UP alternatives
1619 noresidual [PPC] Don't use residual data on PReP machines.
1621 noresume [SWSUSP] Disables resume and restores original swap
1624 no-scroll [VGA] Disables scrollback.
1625 This is required for the Braillex ib80-piezo Braille
1626 reader made by F.H. Papenmeier (Germany).
1630 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1632 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1633 and disable the IO APIC. legacy for "maxcpus=0".
1635 nosoftlockup [KNL] Disable the soft-lockup detector.
1637 noswapaccount [KNL] Disable accounting of swap in memory resource
1638 controller. (See Documentation/cgroups/memory.txt)
1640 nosync [HW,M68K] Disables sync negotiation for all devices.
1642 notsc [BUGS=X86-32] Disable Time Stamp Counter
1644 nousb [USB] Disable the USB subsystem
1648 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1650 nptcg= [IA64] Override max number of concurrent global TLB
1651 purges which is reported from either PAL_VM_SUMMARY or
1654 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1656 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1657 one of ['zone', 'node', 'default'] can be specified
1658 This can be set from sysctl after boot.
1659 See Documentation/sysctl/vm.txt for details.
1661 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1662 See Documentation/debugging-via-ohci1394.txt for more
1665 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1666 Rather than timing out after 20 ms if an EC
1667 command is not properly ACKed, override the length
1668 of the timeout. We have interrupts disabled while
1669 waiting for the ACK, so if this is set too high
1670 interrupts *may* be lost!
1675 oprofile.timer= [HW]
1676 Use timer interrupt instead of performance counters
1678 oprofile.cpu_type= Force an oprofile cpu type
1679 This might be useful if you have an older oprofile
1680 userland or if you want common events.
1681 Format: { archperfmon }
1682 archperfmon: [X86] Force use of architectural
1683 perfmon on Intel CPUs instead of the
1684 CPU specific event set.
1686 osst= [HW,SCSI] SCSI Tape Driver
1687 Format: <buffer_size>,<write_threshold>
1688 See also Documentation/scsi/st.txt.
1690 panic= [KNL] Kernel behaviour on panic
1693 parkbd.port= [HW] Parallel port number the keyboard adapter is
1694 connected to, default is 0.
1696 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1697 0 for XT, 1 for AT (default is AT).
1700 parport= [HW,PPT] Specify parallel ports. 0 disables.
1701 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1702 Use 'auto' to force the driver to use any
1703 IRQ/DMA settings detected (the default is to
1704 ignore detected IRQ/DMA settings because of
1705 possible conflicts). You can specify the base
1706 address, IRQ, and DMA settings; IRQ and DMA
1707 should be numbers, or 'auto' (for using detected
1708 settings on that particular port), or 'nofifo'
1709 (to avoid using a FIFO even if it is detected).
1710 Parallel ports are assigned in the order they
1711 are specified on the command line, starting
1714 parport_init_mode= [HW,PPT]
1715 Configure VIA parallel port to operate in
1716 a specific mode. This is necessary on Pegasos
1717 computer where firmware has no options for setting
1718 up parallel port mode and sets it to spp.
1719 Currently this function knows 686a and 8231 chips.
1720 Format: [spp|ps2|epp|ecp|ecpepp]
1722 pas2= [HW,OSS] Format:
1723 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1726 See header of drivers/scsi/pas16.c.
1729 Halt all CPUs after the first oops has been printed for
1730 the specified number of seconds. This is to be used if
1731 your oopses keep scrolling off the screen.
1736 See header of drivers/block/paride/pcd.c.
1737 See also Documentation/blockdev/paride.txt.
1739 pci=option[,option...] [PCI] various PCI subsystem options:
1740 earlydump [X86] dump PCI config space before the kernel
1742 off [X86] don't probe for the PCI bus
1743 bios [X86-32] force use of PCI BIOS, don't access
1744 the hardware directly. Use this if your machine
1745 has a non-standard PCI host bridge.
1746 nobios [X86-32] disallow use of PCI BIOS, only direct
1747 hardware access methods are allowed. Use this
1748 if you experience crashes upon bootup and you
1749 suspect they are caused by the BIOS.
1750 conf1 [X86] Force use of PCI Configuration
1752 conf2 [X86] Force use of PCI Configuration
1754 noaer [PCIE] If the PCIEAER kernel config parameter is
1755 enabled, this kernel boot option can be used to
1756 disable the use of PCIE advanced error reporting.
1757 nodomains [PCI] Disable support for multiple PCI
1758 root domains (aka PCI segments, in ACPI-speak).
1759 nommconf [X86] Disable use of MMCONFIG for PCI
1761 nomsi [MSI] If the PCI_MSI kernel config parameter is
1762 enabled, this kernel boot option can be used to
1763 disable the use of MSI interrupts system-wide.
1764 noioapicquirk [APIC] Disable all boot interrupt quirks.
1765 Safety option to keep boot IRQs enabled. This
1766 should never be necessary.
1767 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1768 primary IO-APIC for bridges that cannot disable
1769 boot IRQs. This fixes a source of spurious IRQs
1770 when the system masks IRQs.
1771 noioapicreroute [APIC] Disable workaround that uses the
1772 boot IRQ equivalent of an IRQ that connects to
1773 a chipset where boot IRQs cannot be disabled.
1774 The opposite of ioapicreroute.
1775 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1776 routing table. These calls are known to be buggy
1777 on several machines and they hang the machine
1778 when used, but on other computers it's the only
1779 way to get the interrupt routing table. Try
1780 this option if the kernel is unable to allocate
1781 IRQs or discover secondary PCI buses on your
1783 rom [X86] Assign address space to expansion ROMs.
1784 Use with caution as certain devices share
1785 address decoders between ROMs and other
1787 norom [X86] Do not assign address space to
1788 expansion ROMs that do not already have
1789 BIOS assigned address ranges.
1790 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1791 assigned automatically to PCI devices. You can
1792 make the kernel exclude IRQs of your ISA cards
1794 pirqaddr=0xAAAAA [X86] Specify the physical address
1795 of the PIRQ table (normally generated
1796 by the BIOS) if it is outside the
1797 F0000h-100000h range.
1798 lastbus=N [X86] Scan all buses thru bus #N. Can be
1799 useful if the kernel is unable to find your
1800 secondary buses and you want to tell it
1801 explicitly which ones they are.
1802 assign-busses [X86] Always assign all PCI bus
1803 numbers ourselves, overriding
1804 whatever the firmware may have done.
1805 usepirqmask [X86] Honor the possible IRQ mask stored
1806 in the BIOS $PIR table. This is needed on
1807 some systems with broken BIOSes, notably
1808 some HP Pavilion N5400 and Omnibook XE3
1809 notebooks. This will have no effect if ACPI
1810 IRQ routing is enabled.
1811 noacpi [X86] Do not use ACPI for IRQ routing
1812 or for PCI scanning.
1813 use_crs [X86] Use _CRS for PCI resource
1815 routeirq Do IRQ routing for all PCI devices.
1816 This is normally done in pci_enable_device(),
1817 so this option is a temporary workaround
1818 for broken drivers that don't call it.
1819 skip_isa_align [X86] do not align io start addr, so can
1820 handle more pci cards
1821 firmware [ARM] Do not re-enumerate the bus but instead
1822 just use the configuration from the
1823 bootloader. This is currently used on
1824 IXP2000 systems where the bus has to be
1825 configured a certain way for adjunct CPUs.
1826 noearly [X86] Don't do any early type 1 scanning.
1827 This might help on some broken boards which
1828 machine check when some devices' config space
1829 is read. But various workarounds are disabled
1830 and some IOMMU drivers will not work.
1831 bfsort Sort PCI devices into breadth-first order.
1832 This sorting is done to get a device
1833 order compatible with older (<= 2.4) kernels.
1834 nobfsort Don't sort PCI devices into breadth-first order.
1835 cbiosize=nn[KMG] The fixed amount of bus space which is
1836 reserved for the CardBus bridge's IO window.
1837 The default value is 256 bytes.
1838 cbmemsize=nn[KMG] The fixed amount of bus space which is
1839 reserved for the CardBus bridge's memory
1840 window. The default value is 64 megabytes.
1843 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1844 Specifies alignment and device to reassign
1845 aligned memory resources.
1846 If <order of align> is not specified,
1847 PAGE_SIZE is used as alignment.
1848 PCI-PCI bridge can be specified, if resource
1849 windows need to be expanded.
1851 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1854 force Enable ASPM even on devices that claim not to support it.
1855 WARNING: Forcing ASPM on may cause system lockups.
1857 pcmv= [HW,PCMCIA] BadgePAD 4
1860 See Documentation/blockdev/paride.txt.
1862 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1865 See arch/parisc/kernel/pdc_chassis.c
1868 See Documentation/blockdev/paride.txt.
1871 See Documentation/blockdev/paride.txt.
1873 pirq= [SMP,APIC] Manual mp-table setup
1874 See Documentation/x86/i386/IO-APIC.txt.
1876 plip= [PPT,NET] Parallel port network link
1877 Format: { parport<nr> | timid | 0 }
1878 See also Documentation/parport.txt.
1880 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1881 Override pmtimer IOPort with a hex value.
1885 Enable PNP debug messages. This depends on the
1886 CONFIG_PNP_DEBUG_MESSAGES option.
1892 { on | off | curr | res | no-curr | no-res }
1895 [ISAPNP] Exclude IRQs for the autoconfiguration
1898 [ISAPNP] Exclude DMAs for the autoconfiguration
1900 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1901 Ranges are in pairs (I/O port base and size).
1904 [ISAPNP] Exclude memory regions for the
1906 Ranges are in pairs (memory base and size).
1908 ports= [IP_VS_FTP] IPVS ftp helper module
1910 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1912 Format: <port>,<port>....
1914 print-fatal-signals=
1915 [KNL] debug: print fatal signals
1916 print-fatal-signals=1: print segfault info to
1920 printk.time= Show timing data prefixed to each printk message line
1921 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1923 processor.max_cstate= [HW,ACPI]
1924 Limit processor to maximum C-state
1925 max_cstate=9 overrides any DMI blacklist limit.
1927 processor.nocst [HW,ACPI]
1928 Ignore the _CST method to determine C-states,
1929 instead using the legacy FADT method
1931 profile= [KNL] Enable kernel profiling via /proc/profile
1932 Format: [schedule,]<number>
1933 Param: "schedule" - profile schedule points.
1934 Param: <number> - step/bucket size as a power of 2 for
1935 statistical time based profiling.
1936 Param: "sleep" - profile D-state sleeping (millisecs).
1937 Requires CONFIG_SCHEDSTATS
1938 Param: "kvm" - profile VM exits.
1940 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1942 See Documentation/blockdev/ramdisk.txt.
1944 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1945 probe for; one of (bare|imps|exps|lifebook|any).
1946 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1948 psmouse.resetafter= [HW,MOUSE]
1949 Try to reset the device after so many bad packets
1952 [HW,MOUSE] Set desired mouse resolution, in dpi.
1953 psmouse.smartscroll=
1954 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1955 0 = disabled, 1 = enabled (default).
1957 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1959 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1962 See Documentation/blockdev/paride.txt.
1965 [KNL] Number of legacy pty's. Overwrites compiled-in
1968 quiet [KNL] Disable most log messages
1973 See Documentation/md.txt.
1975 ramdisk_blocksize= [RAM]
1976 See Documentation/blockdev/ramdisk.txt.
1978 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1979 See Documentation/blockdev/ramdisk.txt.
1981 rcupdate.blimit= [KNL,BOOT]
1982 Set maximum number of finished RCU callbacks to process
1985 rcupdate.qhimark= [KNL,BOOT]
1986 Set threshold of queued
1987 RCU callbacks over which batch limiting is disabled.
1989 rcupdate.qlowmark= [KNL,BOOT]
1990 Set threshold of queued RCU callbacks below which
1991 batch limiting is re-enabled.
1995 Run specified binary instead of /init from the ramdisk,
1996 used for early userspace startup. See initrd.
1998 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1999 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2000 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2003 [KNL, SMP] Set scheduler's default relax_domain_level.
2004 See Documentation/cgroups/cpusets.txt.
2006 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2008 reservetop= [X86-32]
2010 Reserves a hole at the top of the kernel virtual
2013 reset_devices [KNL] Force drivers to reset the underlying device
2014 during initialization.
2017 Specify the partition device for software suspend
2019 resume_offset= [SWSUSP]
2020 Specify the offset from the beginning of the partition
2021 given by "resume=" at which the swap header is located,
2022 in <PAGE_SIZE> units (needed only for swap files).
2023 See Documentation/power/swsusp-and-swap-files.txt
2025 retain_initrd [RAM] Keep initrd memory after extraction
2027 rhash_entries= [KNL,NET]
2028 Set number of hash buckets for route cache
2030 riscom8= [HW,SERIAL]
2031 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2033 ro [KNL] Mount root device read-only on boot
2035 root= [KNL] Root filesystem
2037 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2038 mount the root filesystem
2040 rootflags= [KNL] Set root filesystem mount option string
2042 rootfstype= [KNL] Set root filesystem type
2044 rootwait [KNL] Wait (indefinitely) for root device to show up.
2045 Useful for devices that are detected asynchronously
2046 (e.g. USB and MMC devices).
2048 root_plug.vendor_id=
2049 [ROOTPLUG] Override the default vendor ID
2051 root_plug.product_id=
2052 [ROOTPLUG] Override the default product ID
2055 [ROOTPLUG] Enable debugging output
2057 rw [KNL] Mount root device read-write on boot
2059 S [KNL] Run init in single mode
2062 See drivers/net/irda/sa1100_ir.c.
2064 sbni= [NET] Granch SBNI12 leased line adapter
2066 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2067 Format: <io>[,<timeout>[,<isapnp>]]
2069 scsi_debug_*= [SCSI]
2070 See drivers/scsi/scsi_debug.c.
2072 scsi_default_dev_flags=
2073 [SCSI] SCSI default device flags
2076 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2077 Format: <vendor>:<model>:<flags>
2078 (flags are integer value)
2080 scsi_logging_level= [SCSI] a bit mask of logging levels
2081 See drivers/scsi/scsi_logging.h for bits. Also
2082 settable via sysctl at dev.scsi.logging_level
2083 (/proc/sys/dev/scsi/logging_level).
2084 There is also a nice 'scsi_logging_level' script in the
2085 S390-tools package, available for download at
2086 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2088 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2089 discovered. async scans them in kernel threads,
2090 allowing boot to proceed. none ignores them, expecting
2091 user space to do the scan.
2093 security= [SECURITY] Choose a security module to enable at boot.
2094 If this boot parameter is not specified, only the first
2095 security module asking for security registration will be
2096 loaded. An invalid security module name will be treated
2097 as if no module has been chosen.
2099 selinux= [SELINUX] Disable or enable SELinux at boot time.
2100 Format: { "0" | "1" }
2101 See security/selinux/Kconfig help text.
2104 Default value is set via kernel config option.
2105 If enabled at boot time, /selinux/disable can be used
2106 later to disable prior to initial policy load.
2108 serialnumber [BUGS=X86-32]
2111 Maximal number of shapers.
2113 show_msr= [x86] show boot-time MSR settings
2114 Format: { <integer> }
2115 Show boot-time (BIOS-initialized) MSR settings.
2116 The parameter means the number of CPUs to show,
2117 for example 1 means boot CPU only.
2120 See header of drivers/scsi/sim710.c.
2127 slub_debug[=options[,slabs]] [MM, SLUB]
2128 Enabling slub_debug allows one to determine the
2129 culprit if slab objects become corrupted. Enabling
2130 slub_debug can create guard zones around objects and
2131 may poison objects when not in use. Also tracks the
2132 last alloc / free. For more information see
2133 Documentation/vm/slub.txt.
2135 slub_max_order= [MM, SLUB]
2136 Determines the maximum allowed order for slabs.
2137 A high setting may cause OOMs due to memory
2138 fragmentation. For more information see
2139 Documentation/vm/slub.txt.
2141 slub_min_objects= [MM, SLUB]
2142 The minimum number of objects per slab. SLUB will
2143 increase the slab order up to slub_max_order to
2144 generate a sufficiently large slab able to contain
2145 the number of objects indicated. The higher the number
2146 of objects the smaller the overhead of tracking slabs
2147 and the less frequently locks need to be acquired.
2148 For more information see Documentation/vm/slub.txt.
2150 slub_min_order= [MM, SLUB]
2151 Determines the mininum page order for slabs. Must be
2152 lower than slub_max_order.
2153 For more information see Documentation/vm/slub.txt.
2155 slub_nomerge [MM, SLUB]
2156 Disable merging of slabs with similar size. May be
2157 necessary if there is some reason to distinguish
2158 allocs to different slabs. Debug options disable
2159 merging on their own.
2160 For more information see Documentation/vm/slub.txt.
2163 Format: <io1>[,<io2>[,...,<io8>]]
2165 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2166 attempt to substitute SMP alternatives once at boot.
2168 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2169 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2170 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2171 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2172 smsc-ircc2.ircc_irq= [HW] IRQ line
2173 smsc-ircc2.ircc_dma= [HW] DMA channel
2174 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2175 0: Toshiba Satellite 1800 (GP data pin select)
2176 1: Fast pin select (default)
2179 snd-ad1816a= [HW,ALSA]
2181 snd-ad1848= [HW,ALSA]
2183 snd-ali5451= [HW,ALSA]
2185 snd-als100= [HW,ALSA]
2187 snd-als4000= [HW,ALSA]
2189 snd-azt2320= [HW,ALSA]
2191 snd-cmi8330= [HW,ALSA]
2193 snd-cmipci= [HW,ALSA]
2195 snd-cs4231= [HW,ALSA]
2197 snd-cs4232= [HW,ALSA]
2199 snd-cs4236= [HW,ALSA]
2201 snd-cs4281= [HW,ALSA]
2203 snd-cs46xx= [HW,ALSA]
2205 snd-dt019x= [HW,ALSA]
2207 snd-dummy= [HW,ALSA]
2209 snd-emu10k1= [HW,ALSA]
2211 snd-ens1370= [HW,ALSA]
2213 snd-ens1371= [HW,ALSA]
2215 snd-es968= [HW,ALSA]
2217 snd-es1688= [HW,ALSA]
2219 snd-es18xx= [HW,ALSA]
2221 snd-es1938= [HW,ALSA]
2223 snd-es1968= [HW,ALSA]
2225 snd-fm801= [HW,ALSA]
2227 snd-gusclassic= [HW,ALSA]
2229 snd-gusextreme= [HW,ALSA]
2231 snd-gusmax= [HW,ALSA]
2235 snd-ice1712= [HW,ALSA]
2237 snd-intel8x0= [HW,ALSA]
2239 snd-interwave= [HW,ALSA]
2244 snd-korg1212= [HW,ALSA]
2246 snd-maestro3= [HW,ALSA]
2248 snd-mpu401= [HW,ALSA]
2250 snd-mtpav= [HW,ALSA]
2252 snd-nm256= [HW,ALSA]
2254 snd-opl3sa2= [HW,ALSA]
2262 snd-opti93x= [HW,ALSA]
2266 snd-rme32= [HW,ALSA]
2268 snd-rme96= [HW,ALSA]
2270 snd-rme9652= [HW,ALSA]
2276 snd-sbawe= [HW,ALSA]
2278 snd-serial= [HW,ALSA]
2280 snd-sgalaxy= [HW,ALSA]
2282 snd-sonicvibes= [HW,ALSA]
2287 snd-sun-cs4231= [HW,ALSA]
2289 snd-trident= [HW,ALSA]
2291 snd-usb-audio= [HW,ALSA,USB]
2293 snd-via82xx= [HW,ALSA]
2295 snd-virmidi= [HW,ALSA]
2297 snd-wavefront= [HW,ALSA]
2299 snd-ymfpci= [HW,ALSA]
2302 [KNL] Should the soft-lockup detector generate panics.
2304 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2305 See Documentation/sonypi.txt
2307 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2308 See Documentation/serial/specialix.txt.
2310 spia_io_base= [HW,MTD]
2316 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2318 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2319 See Documentation/scsi/st.txt.
2322 Enabled the stack tracer on boot up.
2326 Set the STI (builtin display/keyboard on the HP-PARISC
2327 machines) console (graphic card) which should be used
2328 as the initial boot-console.
2329 See also comment in drivers/video/console/sticore.c.
2332 See comment in drivers/video/console/sticore.c.
2335 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2339 Control how the NFS server code allocates CPUs to
2340 service thread pools. Depending on how many NICs
2341 you have and where their interrupts are bound, this
2342 option will affect which CPUs will do NFS serving.
2343 Note: this parameter cannot be changed while the
2344 NFS server is running.
2346 auto the server chooses an appropriate mode
2347 automatically using heuristics
2348 global a single global pool contains all CPUs
2349 percpu one pool for each CPU
2350 pernode one pool for each NUMA node (equivalent
2351 to global on non-NUMA machines)
2353 swiotlb= [IA-64] Number of I/O TLB slabs
2357 sym53c416= [HW,SCSI]
2358 See header of drivers/scsi/sym53c416.c.
2360 sysrq_always_enabled
2362 Ignore sysrq setting - this boot parameter will
2363 neutralize any effect of /proc/sys/kernel/sysrq.
2364 Useful for debugging.
2367 See header of drivers/scsi/t128.c.
2371 test_suspend= [SUSPEND]
2372 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2373 standby suspend) as the system sleep state to briefly
2374 enter during system startup. The system is woken from
2375 this state using a wakeup-capable RTC alarm.
2377 thash_entries= [KNL,NET]
2378 Set number of hash buckets for TCP connection
2380 thermal.act= [HW,ACPI]
2381 -1: disable all active trip points in all thermal zones
2382 <degrees C>: override all lowest active trip points
2384 thermal.crt= [HW,ACPI]
2385 -1: disable all critical trip points in all thermal zones
2386 <degrees C>: override all critical trip points
2388 thermal.nocrt= [HW,ACPI]
2389 Set to disable actions on ACPI thermal zone
2390 critical and hot trip points.
2392 thermal.off= [HW,ACPI]
2393 1: disable ACPI thermal control
2395 thermal.psv= [HW,ACPI]
2396 -1: disable all passive trip points
2397 <degrees C>: override all passive trip points to this
2400 thermal.tzp= [HW,ACPI]
2401 Specify global default ACPI thermal zone polling rate
2402 <deci-seconds>: poll all this frequency
2403 0: no polling (default)
2406 See comment before function dc390_setup() in
2407 drivers/scsi/tmscsim.c.
2411 Specify if the kernel should make use of the cpu
2412 topology informations if the hardware supports these.
2413 The scheduler will make use of these informations and
2414 e.g. base its process migration decisions on it.
2419 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2421 trix= [HW,OSS] MediaTrix AudioTrix Pro
2423 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2425 tsc= Disable clocksource-must-verify flag for TSC.
2427 [x86] reliable: mark tsc clocksource as reliable, this
2428 disables clocksource verification at runtime.
2429 Used to enable high-resolution timer mode on older
2430 hardware, and in virtualized environment.
2432 turbografx.map[2|3]= [HW,JOY]
2433 TurboGraFX parallel port interface
2435 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2436 See also Documentation/input/joystick-parport.txt
2438 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2439 See header of drivers/scsi/u14-34f.c.
2448 [USB] Ignore overcurrent events (default N).
2449 Some badly-designed motherboards generate lots of
2450 bogus events, for ports that aren't wired to
2451 anything. Set this parameter to avoid log spamming.
2452 Note that genuine overcurrent events won't be
2457 Set unknown_nmi_panic=1 early on boot.
2459 usbcore.autosuspend=
2460 [USB] The autosuspend time delay (in seconds) used
2461 for newly-detected USB devices (default 2). This
2462 is the time required before an idle device will be
2463 autosuspended. Devices for which the delay is set
2464 to a negative value won't be autosuspended at all.
2466 usbcore.usbfs_snoop=
2467 [USB] Set to log all usbfs traffic (default 0 = off).
2469 usbcore.blinkenlights=
2470 [USB] Set to cycle leds on hubs (default 0 = off).
2472 usbcore.old_scheme_first=
2473 [USB] Start with the old device initialization
2474 scheme (default 0 = off).
2476 usbcore.use_both_schemes=
2477 [USB] Try the other device initialization scheme
2478 if the first one fails (default 1 = enabled).
2480 usbcore.initial_descriptor_timeout=
2481 [USB] Specifies timeout for the initial 64-byte
2482 USB_REQ_GET_DESCRIPTOR request in milliseconds
2483 (default 5000 = 5.0 seconds).
2486 [USBHID] The interval which mice are to be polled at.
2488 usb-storage.delay_use=
2489 [UMS] The delay in seconds before a new device is
2490 scanned for Logical Units (default 5).
2493 [UMS] A list of quirks entries to supplement or
2494 override the built-in unusual_devs list. List
2495 entries are separated by commas. Each entry has
2496 the form VID:PID:Flags where VID and PID are Vendor
2497 and Product ID values (4-digit hex numbers) and
2498 Flags is a set of characters, each corresponding
2499 to a common usb-storage quirk flag as follows:
2500 a = SANE_SENSE (collect more than 18 bytes
2502 c = FIX_CAPACITY (decrease the reported
2503 device capacity by one sector);
2504 h = CAPACITY_HEURISTICS (decrease the
2505 reported device capacity by one
2506 sector if the number is odd);
2507 i = IGNORE_DEVICE (don't bind to this
2509 l = NOT_LOCKABLE (don't try to lock and
2510 unlock ejectable media);
2511 m = MAX_SECTORS_64 (don't transfer more
2512 than 64 sectors = 32 KB at a time);
2513 o = CAPACITY_OK (accept the capacity
2514 reported by the device);
2515 r = IGNORE_RESIDUE (the device reports
2516 bogus residue values);
2517 s = SINGLE_LUN (the device has only one
2519 w = NO_WP_DETECT (don't test whether the
2520 medium is write-protected).
2521 Example: quirks=0419:aaf5:rl,0421:0433:rc
2524 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2525 vdso=1: enable VDSO (default)
2526 vdso=0: disable VDSO mapping
2529 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2530 vdso32=1: enable 32-bit VDSO (default)
2531 vdso32=0: disable 32-bit VDSO mapping
2534 vector=percpu: enable percpu vector domain
2536 video= [FB] Frame buffer configuration
2537 See Documentation/fb/modedb.txt.
2539 vga= [BOOT,X86-32] Select a particular video mode
2540 See Documentation/x86/boot.txt and
2541 Documentation/svga.txt.
2542 Use vga=ask for menu.
2543 This is actually a boot loader parameter; the value is
2544 passed to the kernel using a special protocol.
2546 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2547 size of <nn>. This can be used to increase the
2548 minimum size (128MB on x86). It can also be used to
2549 decrease the size and leave more room for directly
2552 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2555 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2558 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2561 vt.default_blu= [VT]
2562 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2563 Change the default blue palette of the console.
2564 This is a 16-member array composed of values
2567 vt.default_grn= [VT]
2568 Format: <green0>,<green1>,<green2>,...,<green15>
2569 Change the default green palette of the console.
2570 This is a 16-member array composed of values
2573 vt.default_red= [VT]
2574 Format: <red0>,<red1>,<red2>,...,<red15>
2575 Change the default red palette of the console.
2576 This is a 16-member array composed of values
2582 Set system-wide default UTF-8 mode for all tty's.
2583 Default is 1, i.e. UTF-8 mode is enabled for all
2584 newly opened terminals.
2586 waveartist= [HW,OSS]
2587 Format: <io>,<irq>,<dma>,<dma2>
2590 See header of drivers/scsi/wd33c93.c.
2593 See header of drivers/scsi/wd7000.c.
2596 See Documentation/watchdog/wdt.txt.
2598 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2599 default x2apic cluster mode on platforms
2602 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2603 xd_geo= See header of drivers/block/xd.c.
2605 xirc2ps_cs= [NET,PCMCIA]
2607 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2609 ______________________________________________________________________
2613 Add documentation for ALSA options.
2614 Add more DRM drivers.
projects / platform / adaptation / renesas_rcar / renesas_kernel.git / blob