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 KMEMTRACE kmemtrace is enabled.
60 LIBATA Libata driver is enabled
61 LP Printer support is enabled.
62 LOOP Loopback device support is enabled.
63 M68k M68k architecture is enabled.
64 These options have more detailed description inside of
65 Documentation/m68k/kernel-options.txt.
66 MCA MCA bus support is enabled.
67 MDA MDA console support is enabled.
68 MOUSE Appropriate mouse support is enabled.
69 MSI Message Signaled Interrupts (PCI).
70 MTD MTD (Memory Technology Device) support is enabled.
71 NET Appropriate network support is enabled.
72 NUMA NUMA support is enabled.
73 GENERIC_TIME The generic timeofday code is enabled.
74 NFS Appropriate NFS support is enabled.
75 OSS OSS sound support is enabled.
76 PV_OPS A paravirtualized kernel is enabled.
77 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
78 PARISC The PA-RISC architecture is enabled.
79 PCI PCI bus support is enabled.
80 PCIE PCI Express support is enabled.
81 PCMCIA The PCMCIA subsystem is enabled.
82 PNP Plug & Play support is enabled.
83 PPC PowerPC architecture is enabled.
84 PPT Parallel port support is enabled.
85 PS2 Appropriate PS/2 support is enabled.
86 RAM RAM disk support is enabled.
87 ROOTPLUG The example Root Plug LSM is enabled.
88 S390 S390 architecture is enabled.
89 SCSI Appropriate SCSI support is enabled.
90 A lot of drivers has their options described inside of
92 SECURITY Different security models are enabled.
93 SELINUX SELinux support is enabled.
94 SERIAL Serial support is enabled.
95 SH SuperH architecture is enabled.
96 SMP The kernel is an SMP kernel.
97 SPARC Sparc architecture is enabled.
98 SWSUSP Software suspend (hibernation) is enabled.
99 SUSPEND System suspend states are enabled.
100 FTRACE Function tracing enabled.
101 TS Appropriate touchscreen support is enabled.
102 UMS USB Mass Storage support is enabled.
103 USB USB support is enabled.
104 USBHID USB Human Interface Device support is enabled.
105 V4L Video For Linux support is enabled.
106 VGA The VGA console has been enabled.
107 VT Virtual terminal support is enabled.
108 WDT Watchdog support is enabled.
109 XT IBM PC/XT MFM hard disk support is enabled.
110 X86-32 X86-32, aka i386 architecture is enabled.
111 X86-64 X86-64 architecture is enabled.
112 More X86-64 boot options can be found in
113 Documentation/x86/x86_64/boot-options.txt .
114 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
116 In addition, the following text indicates that the option:
118 BUGS= Relates to possible processor bugs on the said processor.
119 KNL Is a kernel start-up parameter.
120 BOOT Is a boot loader parameter.
122 Parameters denoted with BOOT are actually interpreted by the boot
123 loader, and have no meaning to the kernel directly.
124 Do not modify the syntax of boot loader parameters without extreme
125 need or coordination with <Documentation/x86/boot.txt>.
127 There are also arch-specific kernel-parameters not documented here.
128 See for example <Documentation/x86/x86_64/boot-options.txt>.
130 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
131 a trailing = on the name of any parameter states that that parameter will
132 be entered as an environment variable, whereas its absence indicates that
133 it will appear as a kernel argument readable via /proc/cmdline by programs
134 running once the system is up.
136 The number of kernel parameters is not limited, but the length of the
137 complete command line (parameters including spaces etc.) is limited to
138 a fixed number of characters. This limit depends on the architecture
139 and is between 256 and 4096 characters. It is defined in the file
140 ./include/asm/setup.h as COMMAND_LINE_SIZE.
144 Advanced Configuration and Power Interface
145 Format: { force | off | ht | strict | noirq | rsdt }
146 force -- enable ACPI if default was off
147 off -- disable ACPI if default was on
148 noirq -- do not use ACPI for IRQ routing
149 ht -- run only enough ACPI to enable Hyper Threading
150 strict -- Be less tolerant of platforms that are not
151 strictly ACPI specification compliant.
152 rsdt -- prefer RSDT over (default) XSDT
154 See also Documentation/power/pm.txt, pci=noacpi
156 acpi_apic_instance= [ACPI, IOAPIC]
158 2: use 2nd APIC table, if available
159 1,0: use 1st APIC table
162 acpi_backlight= [HW,ACPI]
163 acpi_backlight=vendor
165 If set to vendor, prefer vendor specific driver
166 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
167 of the ACPI video.ko driver.
169 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
170 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
172 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
173 debug output. Bits in debug_layer correspond to a
174 _COMPONENT in an ACPI source file, e.g.,
175 #define _COMPONENT ACPI_PCI_COMPONENT
176 Bits in debug_level correspond to a level in
177 ACPI_DEBUG_PRINT statements, e.g.,
178 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
179 The debug_level mask defaults to "info". See
180 Documentation/acpi/debug.txt for more information about
181 debug layers and levels.
183 Enable processor driver info messages:
184 acpi.debug_layer=0x20000000
185 Enable PCI/PCI interrupt routing info messages:
186 acpi.debug_layer=0x400000
187 Enable AML "Debug" output, i.e., stores to the Debug
188 object while interpreting AML:
189 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
190 Enable all messages related to ACPI hardware:
191 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
193 Some values produce so much output that the system is
194 unusable. The "log_buf_len" parameter may be useful
195 if you need to capture more output.
197 acpi_display_output= [HW,ACPI]
198 acpi_display_output=vendor
199 acpi_display_output=video
202 acpi_irq_balance [HW,ACPI]
203 ACPI will balance active IRQs
206 acpi_irq_nobalance [HW,ACPI]
207 ACPI will not move active IRQs (default)
210 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
211 Format: <irq>,<irq>...
213 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
215 Format: <irq>,<irq>...
217 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
219 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
220 Format: To spoof as Windows 98: ="Microsoft Windows"
222 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
223 acpi_osi="string1" # add string1 -- only one string
224 acpi_osi="!string2" # remove built-in string2
225 acpi_osi= # disable all strings
228 Override the pmtimer bug detection: force the kernel
229 to assume that this machine's pmtimer latches its value
230 and always returns good values.
232 acpi.power_nocheck= [HW,ACPI]
233 Format: 1/0 enable/disable the check of power state.
234 On some bogus BIOS the _PSC object/_STA object of
235 power resource can't return the correct device power
236 state. In such case it is unneccessary to check its
237 power state again in power transition.
238 1 : disable the power state check
240 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
241 Format: { level | edge | high | low }
243 acpi_serialize [HW,ACPI] force serialization of AML methods
245 acpi_skip_timer_override [HW,ACPI]
246 Recognize and ignore IRQ0/pin2 Interrupt Override.
247 For broken nForce2 BIOS resulting in XT-PIC timer.
249 acpi_sleep= [HW,ACPI] Sleep options
250 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
251 old_ordering, s4_nonvs }
252 See Documentation/power/video.txt for information on
254 s3_beep is for debugging; it makes the PC's speaker beep
255 as soon as the kernel's real-mode entry point is called.
256 s4_nohwsig prevents ACPI hardware signature from being
257 used during resume from hibernation.
258 old_ordering causes the ACPI 1.0 ordering of the _PTS
259 control method, with respect to putting devices into
260 low power states, to be enforced (the ACPI 2.0 ordering
261 of _PTS is used by default).
262 s4_nonvs prevents the kernel from saving/restoring the
263 ACPI NVS memory during hibernation.
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.
286 Format: <io>,<irq>,<dma>,<dma2>,<type>
288 add_efi_memmap [EFI; X86] Include EFI memory map in
289 kernel's map of available physical RAM.
292 See header of drivers/scsi/advansys.c.
294 advwdt= [HW,WDT] Advantech WDT
295 Format: <iostart>,<iostop>
297 aedsp16= [HW,OSS] Audio Excel DSP 16
298 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
299 See also header of sound/oss/aedsp16.c.
302 { off | try_unsupported }
303 off: disable AGP support
304 try_unsupported: try to drive unsupported chipsets
305 (may crash computer or cause data corruption)
308 See Documentation/scsi/aha152x.txt.
311 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
314 See Documentation/scsi/aic7xxx.txt.
317 See Documentation/scsi/aic79xx.txt.
319 amd_iommu= [HW,X86-84]
320 Pass parameters to the AMD IOMMU driver in the system.
322 isolate - enable device isolation (each device, as far
323 as possible, will get its own protection
325 share - put every device behind one IOMMU into the
326 same protection domain
327 fullflush - enable flushing of IO/TLB entries when
328 they are unmapped. Otherwise they are
329 flushed before they will be reused, which
332 amd_iommu_size= [HW,X86-64]
333 Define the size of the aperture for the AMD IOMMU
334 driver. Possible values are:
335 '32M', '64M' (default), '128M', '256M', '512M', '1G'
337 amijoy.map= [HW,JOY] Amiga joystick support
338 Map of devices attached to JOY0DAT and JOY1DAT
340 See also Documentation/kernel/input/joystick.txt
342 analog.map= [HW,JOY] Analog joystick and gamepad support
343 Specifies type or capabilities of an analog joystick
344 connected to one of 16 gameports
345 Format: <type1>,<type2>,..<type16>
348 Power management functions (SPARCstation-4/5 + deriv.)
350 Disable APC CPU standby support. SPARCstation-Fox does
351 not play well with APC CPU idle - disable it if you have
352 APC and your system crashes randomly.
354 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
355 Change the output verbosity whilst booting
356 Format: { quiet (default) | verbose | debug }
357 Change the amount of debugging information output
358 when initialising the APIC and IO-APIC components.
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 atascsi= [HW,SCSI] Atari SCSI
372 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
373 EzKey and similar keyboards
375 atkbd.reset= [HW] Reset keyboard during initialization
377 atkbd.set= [HW] Select keyboard code set
378 Format: <int> (2 = AT (default), 3 = PS/2)
380 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
383 atkbd.softraw= [HW] Choose between synthetic and real raw mode
384 Format: <bool> (0 = real, 1 = synthetic (default))
386 atkbd.softrepeat= [HW]
387 Use software keyboard repeat
391 baycom_epp= [HW,AX25]
394 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
396 See header of drivers/net/hamradio/baycom_par.c.
398 baycom_ser_fdx= [HW,AX25]
399 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
400 Format: <io>,<irq>,<mode>[,<baud>]
401 See header of drivers/net/hamradio/baycom_ser_fdx.c.
403 baycom_ser_hdx= [HW,AX25]
404 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
405 Format: <io>,<irq>,<mode>
406 See header of drivers/net/hamradio/baycom_ser_hdx.c.
408 boot_delay= Milliseconds to delay each printk during boot.
409 Values larger than 10 seconds (10000) are changed to
413 bootmem_debug [KNL] Enable bootmem allocator debug messages.
415 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
416 bttv.radio= Most important insmod options are available as
418 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
419 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
422 See drivers/scsi/BusLogic.c, comment before function
423 BusLogic_ParseDriverOptions().
425 c101= [NET] Moxa C101 synchronous serial card
427 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
428 Sometimes CPU hardware bugs make them report the cache
429 size incorrectly. The kernel will attempt work arounds
430 to fix known problems, but for some CPUs it is not
431 possible to determine what the correct size should be.
432 This option provides an override for these situations.
435 [SECURITY] Disable capabilities. This would normally
436 be used only if an alternative security model is to be
437 configured. Potentially dangerous and should only be
438 used if you are entirely sure of the consequences.
440 ccw_timeout_log [S390]
441 See Documentation/s390/CommonIO for details.
443 cgroup_disable= [KNL] Disable a particular controller
444 Format: {name of the controller(s) to disable}
445 {Currently supported controllers - "memory"}
447 checkreqprot [SELINUX] Set initial checkreqprot flag value.
448 Format: { "0" | "1" }
449 See security/selinux/Kconfig help text.
450 0 -- check protection applied by kernel (includes
451 any implied execute protection).
452 1 -- check protection requested by application.
453 Default value is set via a kernel config option.
454 Value can be changed at runtime via
455 /selinux/checkreqprot.
458 See Documentation/s390/CommonIO for details.
460 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
462 Forces specified clocksource (if available) to be used
463 when calculating gettimeofday(). If specified
464 clocksource is not available, it defaults to PIT.
465 Format: { pit | tsc | cyclone | pmtmr }
467 clocksource= [GENERIC_TIME] Override the default clocksource
469 Override the default clocksource and use the clocksource
470 with the name specified.
471 Some clocksource names to choose from, depending on
473 [all] jiffies (this is the base, fallback clocksource)
475 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
476 pxa_timer,timer3,32k_counter,timer0_1
478 [X86-32] pit,hpet,tsc,vmi-timer;
479 scx200_hrt on Geode; cyclone on IBM x440
487 clearcpuid=BITNUM [X86]
488 Disable CPUID feature X for the kernel. See
489 arch/x86/include/asm/cpufeature.h for the valid bit
490 numbers. Note the Linux specific bits are not necessarily
491 stable over kernel options, but the vendor specific
493 Also note that user programs calling CPUID directly
494 or using the feature without checking anything
495 will still see it. This just prevents it from
496 being used by the kernel or shown in /proc/cpuinfo.
497 Also note the kernel might malfunction if you disable
500 code_bytes [X86] How many bytes of object code to print
505 com20020= [HW,NET] ARCnet - COM20020 chipset
507 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
509 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
513 ARCnet - COM90xx chipset (memory-mapped buffers)
514 Format: <io>[,<irq>[,<memstart>]]
516 condev= [HW,S390] console device
519 console= [KNL] Output console device and options.
521 tty<n> Use the virtual console device <n>.
525 Use the specified serial port. The options are of
526 the form "bbbbpnf", where "bbbb" is the baud rate,
527 "p" is parity ("n", "o", or "e"), "n" is number of
528 bits, and "f" is flow control ("r" for RTS or
529 omit it). Default is "9600n8".
531 See Documentation/serial-console.txt for more
533 Documentation/networking/netconsole.txt for an
536 uart[8250],io,<addr>[,options]
537 uart[8250],mmio,<addr>[,options]
538 Start an early, polled-mode console on the 8250/16550
539 UART at the specified I/O port or MMIO address,
540 switching to the matching ttyS device later. The
541 options are the same as for ttyS, above.
543 If the device connected to the port is not a TTY but a braille
544 device, prepend "brl," before the device type, for instance
546 For now, only VisioBraille is supported.
549 [KNL] Change the default value for
550 /proc/<pid>/coredump_filter.
551 See also Documentation/filesystems/proc.txt.
553 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
555 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
557 crashkernel=nn[KMG]@ss[KMG]
558 [KNL] Reserve a chunk of physical memory to
559 hold a kernel to switch to with kexec on panic.
561 crashkernel=range1:size1[,range2:size2,...][@offset]
562 [KNL] Same as above, but depends on the memory
563 in the running system. The syntax of range is
564 start-[end] where start and end are both
565 a memory unit (amount[KMG]). See also
566 Documentation/kdump/kdump.txt for a example.
571 cs89x0_media= [HW,NET]
572 Format: { rj45 | aui | bnc }
575 See header of drivers/s390/block/dasd_devmap.c.
577 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
578 (one device per port)
579 Format: <port#>,<type>
580 See also Documentation/input/joystick-parport.txt
582 debug [KNL] Enable kernel debugging (events log level).
585 [KNL] verbose self-tests
587 Print debugging info while doing the locking API
589 We default to 0 (no extra messages), setting it to
590 1 will print _a lot_ more information - normally
591 only useful to kernel developers.
593 debug_objects [KNL] Enable object debugging
596 [KNL] Disable object debugging
598 debugpat [X86] Enable PAT debugging
600 decnet.addr= [HW,NET]
601 Format: <area>[,<node>]
602 See also Documentation/networking/decnet.txt.
605 [same as hugepagesz=] The size of the default
606 HugeTLB page size. This is the size represented by
607 the legacy /proc/ hugepages APIs, used for SHM, and
608 default size when mounting hugetlbfs filesystems.
609 Defaults to the default architecture's huge page size
613 Set number of hash buckets for dentry cache.
616 IO parameters + enable/disable command.
618 digiepca= [HW,SERIAL]
619 See drivers/char/README.epca and
620 Documentation/serial/digiepca.txt.
622 disable_mtrr_cleanup [X86]
623 The kernel tries to adjust MTRR layout from continuous
624 to discrete, to make X server driver able to add WB
625 entry later. This parameter disables that.
627 disable_mtrr_trim [X86, Intel and AMD only]
628 By default the kernel will trim any uncacheable
629 memory out of your available memory pool based on
630 MTRR settings. This parameter disables that behavior,
631 possibly causing your machine to run very slowly.
633 disable_timer_pin_1 [X86]
634 Disable PIN 1 of APIC timer
635 Can be useful to work around chipset bugs.
637 dmasound= [HW,OSS] Sound subsystem buffers
639 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
640 this option disables the debugging code at boot.
642 dma_debug_entries=<number>
643 This option allows to tune the number of preallocated
644 entries for DMA-API debugging code. One entry is
645 required per DMA-API allocation. Use this if the
646 DMA-API debugging code disables itself because the
647 architectural default is too low.
653 dynamic_printk Enables pr_debug()/dev_dbg() calls if
654 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
655 These can also be switched on/off via
656 <debugfs>/dynamic_printk/modules
658 earlycon= [KNL] Output early console device and options.
659 uart[8250],io,<addr>[,options]
660 uart[8250],mmio,<addr>[,options]
661 Start an early, polled-mode console on the 8250/16550
662 UART at the specified I/O port or MMIO address.
663 The options are the same as for ttyS, above.
665 earlyprintk= [X86,SH,BLACKFIN]
667 earlyprintk=serial[,ttySn[,baudrate]]
670 Append ",keep" to not disable it when the real console
673 Only vga or serial or usb debug port at a time.
675 Currently only ttyS0 and ttyS1 are supported.
677 Interaction with the standard serial driver is not
680 The VGA output is eventually overwritten by the real
686 Format: {"off" | "on" | "skip[mbr]"}
688 eisa_irq_edge= [PARISC,HW]
689 See header of drivers/parisc/eisa.c.
692 See comment before function elanfreq_setup() in
693 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
696 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
697 See Documentation/block/as-iosched.txt and
698 Documentation/block/deadline-iosched.txt for details.
700 elfcorehdr= [IA64,PPC,SH,X86]
701 Specifies physical address of start of kernel core
702 image elf header. Generally kexec loader will
703 pass this option to capture kernel.
704 See Documentation/kdump/kdump.txt for details.
706 enable_mtrr_cleanup [X86]
707 The kernel tries to adjust MTRR layout from continuous
708 to discrete, to make X server driver able to add WB
709 entry later. This parameter enables that.
711 enable_timer_pin_1 [X86]
712 Enable PIN 1 of APIC timer
713 Can be useful to work around chipset bugs
714 (in particular on some ATI chipsets).
715 The kernel tries to set a reasonable default.
717 enforcing [SELINUX] Set initial enforcing status.
719 See security/selinux/Kconfig help text.
720 0 -- permissive (log only, no denials).
721 1 -- enforcing (deny and log).
723 Value can be changed at runtime via /selinux/enforce.
725 ether= [HW,NET] Ethernet cards parameters
726 This option is obsoleted by the "netdev=" option, which
727 has equivalent usage. See its documentation for details.
729 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
734 fail_make_request=[KNL]
735 General fault injection mechanism.
736 Format: <interval>,<probability>,<space>,<times>
737 See also /Documentation/fault-injection/.
740 See header of drivers/scsi/fd_mcs.c.
743 See header of drivers/scsi/fdomain.c.
746 See Documentation/blockdev/floppy.txt.
748 force_pal_cache_flush
749 [IA-64] Avoid check_sal_cache_flush which may hang on
750 buggy SAL_CACHE_FLUSH implementations. Using this
751 parameter will force ia64_sal_cache_flush to call
752 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
755 [ftrace] will set and start the specified tracer
756 as early as possible in order to facilitate early
760 [ftrace] will dump the trace buffers on oops.
763 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
764 support via parallel port (up to 5 devices per port)
765 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
766 See also Documentation/input/joystick-parport.txt
770 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
775 See header of drivers/scsi/gdth.c.
777 gpt [EFI] Forces disk with valid GPT signature but
778 invalid Protective MBR to be treated as GPT.
782 hashdist= [KNL,NUMA] Large hashes allocated during boot
783 are distributed across NUMA nodes. Defaults on
784 for 64bit NUMA, off otherwise.
785 Format: 0 | 1 (for off | on)
787 hcl= [IA-64] SGI's Hardware Graph compatibility layer
789 hd= [EIDE] (E)IDE hard drive subsystem geometry
790 Format: <cyl>,<head>,<sect>
792 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
793 size of <nn>. This works even on boxes that have no
794 highmem otherwise. This also works to reduce highmem
795 size on bigger boxes.
797 highres= [KNL] Enable/disable high resolution timer mode.
798 Valid parameters: "on", "off"
802 See Documentation/isdn/README.HiSax.
806 hpet= [X86-32,HPET] option to control HPET usage
807 Format: { enable (default) | disable | force |
809 disable: disable HPET and use PIT instead
810 force: allow force enabled of undocumented chips (ICH4,
812 verbose: show contents of HPET registers during setup
814 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
815 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
816 On x86-64 and powerpc, this option can be specified
817 multiple times interleaved with hugepages= to reserve
818 huge pages of different sizes. Valid pages sizes on
819 x86-64 are 2M (when the CPU supports "pse") and 1G
820 (when the CPU supports the "pdpe1gb" cpuinfo flag)
821 Note that 1GB pages can only be allocated at boot time
822 using hugepages= and not freed afterwards.
824 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
825 terminal devices. Valid values: 0..8
826 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
827 If specified, z/VM IUCV HVC accepts connections
828 from listed z/VM user IDs only.
830 i2c_bus= [HW] Override the default board specific I2C bus speed
831 or register an additional I2C bus that is not
832 registered from board initialization code.
836 i8042.debug [HW] Toggle i8042 debug mode
837 i8042.direct [HW] Put keyboard port into non-translated mode
838 i8042.dumbkbd [HW] Pretend that controller can only read data from
839 keyboard and cannot control its state
840 (Don't attempt to blink the leds)
841 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
842 i8042.nokbd [HW] Don't check/create keyboard port
843 i8042.noloop [HW] Disable the AUX Loopback command while probing
845 i8042.nomux [HW] Don't check presence of an active multiplexing
847 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
850 [HW] Frequency with which keyboard LEDs should blink
851 when kernel panics (default is 0.5 sec)
852 i8042.reset [HW] Reset the controller during init and cleanup
853 i8042.unlock [HW] Unlock (ignore) the keylock
857 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
858 indicates that the driver is running on unsupported
860 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
861 does not match list of supported models.
863 [HW] Report power status in /proc/i8k
864 (disabled by default)
865 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
868 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
869 See Documentation/mca.txt.
872 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
874 ide-core.nodma= [HW] (E)IDE subsystem
875 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
876 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
877 .chs .ignore_cable are additional options
878 See Documentation/ide/ide.txt.
880 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
881 See Documentation/ide/ide.txt.
883 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
884 Claim all unknown PCI IDE storage controllers.
887 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
888 Poll forces a polling idle loop that can slightly
889 improve the performance of waking up a idle CPU, but
890 will use a lot of power and make the system run hot.
892 idle=mwait: On systems which support MONITOR/MWAIT but
893 the kernel chose to not use it because it doesn't save
894 as much power as a normal idle loop, use the
895 MONITOR/MWAIT idle loop anyways. Performance should be
896 the same as idle=poll.
897 idle=halt: Halt is forced to be used for CPU idle.
898 In such case C2/C3 won't be used again.
899 idle=nomwait: Disable mwait for CPU C-states
901 ignore_loglevel [KNL]
902 Ignore loglevel setting - this will print /all/
903 kernel messages to the console. Useful for debugging.
906 Set number of hash buckets for inode cache.
909 Format: { "0" | "1" }
910 0 -- integrity auditing messages. (Default)
911 1 -- enable informational integrity auditing messages.
914 Formt: { "sha1" | "md5" }
918 Load a policy which meets the needs of the Trusted
919 Computing Base. This means IMA will measure all
920 programs exec'd, files mmap'd for exec, and all files
921 opened for read by uid=0.
924 See header of drivers/scsi/in2000.c.
928 Run specified binary instead of /sbin/init as init
931 initcall_debug [KNL] Trace initcalls as they are executed. Useful
932 for working out where the kernel is dying during
935 initrd= [BOOT] Specify the location of the initial ramdisk
937 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
940 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
942 Enable intel iommu driver.
944 Disable intel iommu driver.
945 igfx_off [Default Off]
946 By default, gfx is mapped as normal device. If a gfx
947 device has a dedicated DMAR unit, the DMAR unit is
948 bypassed by not enabling DMAR with this option. In
949 this case, gfx device will use physical address for
952 With this option iommu will not optimize to look
953 for io virtual address below 32 bit forcing dual
954 address cycle on pci bus for cards supporting greater
955 than 32 bit addressing. The default is to look
956 for translation below 32 bit and if not available
957 then look in the higher range.
959 With this option on every unmap_single operation will
960 result in a hardware IOTLB flush operation as opposed
961 to batching them for performance.
965 iomem= Disable strict checking of access to MMIO memory
966 strict regions from userspace.
981 io7= [HW] IO7 for Marvel based alpha systems
982 See comment before marvel_specify_io7 in
983 arch/alpha/kernel/core_marvel.c.
985 io_delay= [X86] I/O delay method
987 Standard port 0x80 based delay
989 Alternate port 0xed based delay (needed on some systems)
991 Simple two microseconds delay
996 See Documentation/filesystems/nfsroot.txt.
998 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
999 See comment before ip2_setup() in
1000 drivers/char/ip2/ip2base.c.
1002 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1003 See header of drivers/scsi/ips.c.
1006 When an interrupt is not handled search all handlers
1007 for it. Intended to get systems with badly broken
1011 When an interrupt is not handled search all handlers
1012 for it. Also check all handlers each timer
1013 interrupt. Intended to get systems with badly broken
1017 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1019 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1021 <cpu number>,...,<cpu number>
1023 <cpu number>-<cpu number>
1024 (must be a positive range in ascending order)
1026 <cpu number>,...,<cpu number>-<cpu number>
1028 This option can be used to specify one or more CPUs
1029 to isolate from the general SMP balancing and scheduling
1030 algorithms. You can move a process onto or off an
1031 "isolated" CPU via the CPU affinity syscalls or cpuset.
1032 <cpu number> begins at 0 and the maximum value is
1033 "number of CPUs in system - 1".
1035 This option is the preferred way to isolate CPUs. The
1036 alternative -- manually setting the CPU mask of all
1037 tasks in the system -- can cause problems and
1038 suboptimal load balancer performance.
1042 js= [HW,JOY] Analog joystick
1043 See Documentation/input/joystick.txt.
1047 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1048 specifies the amount of memory usable by the kernel
1049 for non-movable allocations. The requested amount is
1050 spread evenly throughout all nodes in the system. The
1051 remaining memory in each node is used for Movable
1052 pages. In the event, a node is too small to have both
1053 kernelcore and Movable pages, kernelcore pages will
1054 take priority and other nodes will have a larger number
1055 of kernelcore pages. The Movable zone is used for the
1056 allocation of pages that may be reclaimed or moved
1057 by the page migration subsystem. This means that
1058 HugeTLB pages may not be allocated from this zone.
1059 Note that allocations like PTEs-from-HighMem still
1060 use the HighMem zone if it exists, and the Normal
1061 zone if it does not.
1063 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1064 Controls whether kmemtrace is enabled
1067 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1068 subbufs kmemtrace's relay channel has. Set this
1069 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1070 you experience buffer overruns.
1072 kgdboc= [HW] kgdb over consoles.
1073 Requires a tty driver that supports console polling.
1074 (only serial suported for now)
1075 Format: <serial_device>[,baud]
1077 kmac= [MIPS] korina ethernet MAC address.
1078 Configure the RouterBoard 532 series on-chip
1079 Ethernet adapter MAC address.
1081 kstack=N [X86] Print N words from the kernel stack
1088 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1091 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1094 libata.dma= [LIBATA] DMA control
1095 libata.dma=0 Disable all PATA and SATA DMA
1096 libata.dma=1 PATA and SATA Disk DMA only
1097 libata.dma=2 ATAPI (CDROM) DMA only
1098 libata.dma=4 Compact Flash DMA only
1099 Combinations also work, so libata.dma=3 enables DMA
1100 for disks and CDROMs, but not CFs.
1102 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1106 libata.force= [LIBATA] Force configurations. The format is comma
1107 separated list of "[ID:]VAL" where ID is
1108 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1109 matching port, link or device. Basically, it matches
1110 the ATA ID string printed on console by libata. If
1111 the whole ID part is omitted, the last PORT and DEVICE
1112 values are used. If ID hasn't been specified yet, the
1113 configuration applies to all ports, links and devices.
1115 If only DEVICE is omitted, the parameter applies to
1116 the port and all links and devices behind it. DEVICE
1117 number of 0 either selects the first device or the
1118 first fan-out link behind PMP device. It does not
1119 select the host link. DEVICE number of 15 selects the
1120 host link and device attached to it.
1122 The VAL specifies the configuration to force. As long
1123 as there's no ambiguity shortcut notation is allowed.
1124 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1125 The following configurations can be forced.
1127 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1128 Any ID with matching PORT is used.
1130 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1132 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1133 udma[/][16,25,33,44,66,100,133] notation is also
1136 * [no]ncq: Turn on or off NCQ.
1138 * nohrst, nosrst, norst: suppress hard, soft
1141 If there are multiple matching configurations changing
1142 the same attribute, the last one is used.
1144 lmb=debug [KNL] Enable lmb debug messages.
1146 load_ramdisk= [RAM] List of ramdisks to load from floppy
1147 See Documentation/blockdev/ramdisk.txt.
1149 lockd.nlm_grace_period=P [NFS] Assign grace period.
1152 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1155 lockd.nlm_timeout=T [NFS] Assign timeout value.
1158 lockd.nlm_udpport=M [NFS] Assign UDP port.
1161 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1164 loglevel= All Kernel Messages with a loglevel smaller than the
1165 console loglevel will be printed to the console. It can
1166 also be changed with klogd or other programs. The
1167 loglevels are defined as follows:
1169 0 (KERN_EMERG) system is unusable
1170 1 (KERN_ALERT) action must be taken immediately
1171 2 (KERN_CRIT) critical conditions
1172 3 (KERN_ERR) error conditions
1173 4 (KERN_WARNING) warning conditions
1174 5 (KERN_NOTICE) normal but significant condition
1175 6 (KERN_INFO) informational
1176 7 (KERN_DEBUG) debug-level messages
1178 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1179 Format: { n | nk | nM }
1180 n must be a power of two. The default size
1181 is set in the kernel config file.
1183 logo.nologo [FB] Disables display of the built-in Linux logo.
1184 This may be used to provide more screen space for
1185 kernel log messages and is useful when debugging
1186 kernel boot problems.
1188 lp=0 [LP] Specify parallel ports to use, e.g,
1189 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1190 lp=reset first parallel port). 'lp=0' disables the
1191 lp=auto printer driver. 'lp=reset' (which can be
1192 specified in addition to the ports) causes
1193 attached printers to be reset. Using
1194 lp=port1,port2,... specifies the parallel ports
1195 to associate lp devices with, starting with
1196 lp0. A port specification may be 'none' to skip
1197 that lp device, or a parport name such as
1198 'parport0'. Specifying 'lp=auto' instead of a
1199 port specification list means that device IDs
1200 from each port should be examined, to see if
1201 an IEEE 1284-compliant printer is attached; if
1202 so, the driver will manage that printer.
1203 See also header of drivers/char/lp.c.
1206 Sets loops_per_jiffy to given constant, thus avoiding
1207 time-consuming boot-time autodetection (up to 250 ms per
1208 CPU). 0 enables autodetection (default). To determine
1209 the correct value for your kernel, boot with normal
1210 autodetection and see what value is printed. Note that
1211 on SMP systems the preset will be applied to all CPUs,
1212 which is likely to cause problems if your CPUs need
1213 significantly divergent settings. An incorrect value
1214 will cause delays in the kernel to be wrong, leading to
1215 unpredictable I/O errors and other breakage. Although
1216 unlikely, in the extreme case this might damage your
1220 Format: <io>,<irq>,<dma>
1222 mac5380= [HW,SCSI] Format:
1223 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1225 machvec= [IA64] Force the use of a particular machine-vector
1226 (machvec) in a generic kernel.
1227 Example: machvec=hpzx1_swiotlb
1229 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1230 than or equal to this physical address is ignored.
1232 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1233 should make use of. maxcpus=n : n >= 0 limits the
1234 kernel to using 'n' processors. n=0 is a special case,
1235 it is equivalent to "nosmp", which also disables
1238 max_loop= [LOOP] Maximum number of loopback devices that can
1242 max_luns= [SCSI] Maximum number of LUNs to probe.
1243 Should be between 1 and 2^32-1.
1246 [SCSI] Maximum number of LUNs received.
1247 Should be between 1 and 16384.
1251 mce [X86-32] Machine Check Exception
1253 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1255 md= [HW] RAID subsystems devices and level
1256 See Documentation/md.txt.
1259 Format: <first>,<last>
1260 Specifies range of consoles to be captured by the MDA.
1262 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1263 Amount of memory to be used when the kernel is not able
1264 to see the whole system memory or for test.
1265 [X86-32] Use together with memmap= to avoid physical
1266 address space collisions. Without memmap= PCI devices
1267 could be placed at addresses belonging to unused RAM.
1269 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1273 [KNL,SH] Allow user to override the default size for
1274 per-device physically contiguous DMA buffers.
1276 memmap=exactmap [KNL,X86] Enable setting of an exact
1277 E820 memory map, as specified by the user.
1278 Such memmap=exactmap lines can be constructed based on
1279 BIOS output or other requirements. See the memmap=nn@ss
1282 memmap=nn[KMG]@ss[KMG]
1283 [KNL] Force usage of a specific region of memory
1284 Region of memory to be used, from ss to ss+nn.
1286 memmap=nn[KMG]#ss[KMG]
1287 [KNL,ACPI] Mark specific memory as ACPI data.
1288 Region of memory to be used, from ss to ss+nn.
1290 memmap=nn[KMG]$ss[KMG]
1291 [KNL,ACPI] Mark specific memory as reserved.
1292 Region of memory to be used, from ss to ss+nn.
1293 Example: Exclude memory from 0x18690000-0x1869ffff
1294 memmap=64K$0x18690000
1296 memmap=0x10000$0x18690000
1298 memory_corruption_check=0/1 [X86]
1299 Some BIOSes seem to corrupt the first 64k of
1300 memory when doing things like suspend/resume.
1301 Setting this option will scan the memory
1302 looking for corruption. Enabling this will
1303 both detect corruption and prevent the kernel
1304 from using the memory being corrupted.
1305 However, its intended as a diagnostic tool; if
1306 repeatable BIOS-originated corruption always
1307 affects the same memory, you can use memmap=
1308 to prevent the kernel from using that memory.
1310 memory_corruption_check_size=size [X86]
1311 By default it checks for corruption in the low
1312 64k, making this memory unavailable for normal
1313 use. Use this parameter to scan for
1314 corruption in more or less memory.
1316 memory_corruption_check_period=seconds [X86]
1317 By default it checks for corruption every 60
1318 seconds. Use this parameter to check at some
1319 other rate. 0 disables periodic checking.
1321 memtest= [KNL,X86] Enable memtest
1323 default : 0 <disable>
1324 Specifies the number of memtest passes to be
1325 performed. Each pass selects another test
1326 pattern from a given set of patterns. Memtest
1327 fills the memory with this pattern, validates
1328 memory contents and reserves bad memory
1329 regions that are detected.
1331 meye.*= [HW] Set MotionEye Camera parameters
1332 See Documentation/video4linux/meye.txt.
1334 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1335 Multi-Function General Purpose Timers on AMD Geode
1338 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1339 the BIOS has incorrectly applied a workaround. TinyBIOS
1340 version 0.98 is known to be affected, 0.99 fixes the
1341 problem by letting the user disable the workaround.
1345 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1346 physical address is ignored.
1349 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1350 parameter allows control of the logging verbosity for
1351 the additional memory initialisation checks. A value
1352 of 0 disables mminit logging and a level of 4 will
1353 log everything. Information is printed at KERN_DEBUG
1354 so loglevel=8 may also need to be specified.
1357 [MOUSE] Maximum time between finger touching and
1358 leaving touchpad surface for touch to be considered
1359 a tap and be reported as a left button click (for
1360 touchpads working in absolute mode only).
1362 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1363 reporting absolute coordinates, such as tablets
1364 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1365 reporting absolute coordinates, such as tablets
1367 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1368 is similar to kernelcore except it specifies the
1369 amount of memory used for migratable allocations.
1370 If both kernelcore and movablecore is specified,
1371 then kernelcore will be at *least* the specified
1372 value but may be more. If movablecore on its own
1373 is specified, the administrator must be careful
1374 that the amount of memory usable for all allocations
1380 MTD_Partition= [MTD]
1381 Format: <name>,<region-number>,<size>,<offset>
1383 MTD_Region= [MTD] Format:
1384 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1387 See drivers/mtd/cmdlinepart.c.
1390 ARM/S3C2412 JIVE boot control
1392 See arch/arm/mach-s3c2412/mach-jive.c
1394 mtouchusb.raw_coordinates=
1395 [HW] Make the MicroTouch USB driver use raw coordinates
1396 ('y', default) or cooked coordinates ('n')
1398 mtrr_chunk_size=nn[KMG] [X86]
1399 used for mtrr cleanup. It is largest continous chunk
1400 that could hold holes aka. UC entries.
1402 mtrr_gran_size=nn[KMG] [X86]
1403 Used for mtrr cleanup. It is granularity of mtrr block.
1405 Large value could prevent small alignment from
1408 mtrr_spare_reg_nr=n [X86]
1410 Range: 0,7 : spare reg number
1412 Used for mtrr cleanup. It is spare mtrr entries number.
1413 Set to 2 or more if your graphical card needs more.
1415 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1418 See header of drivers/scsi/NCR_D700.c.
1422 ncr53c400= [HW,SCSI]
1424 ncr53c400a= [HW,SCSI]
1426 ncr53c406a= [HW,SCSI]
1428 ncr53c8xx= [HW,SCSI]
1430 netdev= [NET] Network devices parameters
1431 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1432 Note that mem_start is often overloaded to mean
1433 something different and driver-specific.
1434 This usage is only documented in each driver source
1438 [NETFILTER] Enable connection tracking flow accounting
1439 0 to disable accounting
1440 1 to enable accounting
1441 Default value depends on CONFIG_NF_CT_ACCT that is
1442 going to be removed in 2.6.29.
1445 See Documentation/filesystems/nfsroot.txt.
1447 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1448 See Documentation/filesystems/nfsroot.txt.
1450 nfs.callback_tcpport=
1451 [NFS] set the TCP port on which the NFSv4 callback
1452 channel should listen.
1454 nfs.idmap_cache_timeout=
1455 [NFS] set the maximum lifetime for idmapper cache
1459 [NFS] enable 64-bit inode numbers.
1460 If zero, the NFS client will fake up a 32-bit inode
1461 number for the readdir() and stat() syscalls instead
1462 of returning the full 64-bit number.
1463 The default is to return 64-bit inode numbers.
1465 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1466 when a NMI is triggered.
1467 Format: [state][,regs][,debounce][,die]
1469 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1470 Format: [panic,][num]
1472 0 - turn nmi_watchdog off
1473 1 - use the IO-APIC timer for the NMI watchdog
1474 2 - use the local APIC for the NMI watchdog using
1475 a performance counter. Note: This will use one
1476 performance counter and the local APIC's performance
1478 When panic is specified, panic when an NMI watchdog
1480 This is useful when you use a panic=... timeout and
1481 need the box quickly up again.
1482 Instead of 1 and 2 it is possible to use the following
1483 symbolic names: lapic and ioapic
1484 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1486 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1487 emulation library even if a 387 maths coprocessor
1491 [HW] Never suspend the console
1492 Disable suspending of consoles during suspend and
1493 hibernate operations. Once disabled, debugging
1494 messages can reach various consoles while the rest
1495 of the system is being put to sleep (ie, while
1496 debugging driver suspend/resume hooks). This may
1497 not work reliably with all consoles, but is known
1498 to work with serial and VGA consoles.
1500 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1501 caches in the slab allocator. Saves per-node memory,
1502 but will impact performance.
1506 noapic [SMP,APIC] Tells the kernel to not make use of any
1507 IOAPICs that may be present in the system.
1509 nobats [PPC] Do not use BATs for mapping kernel lowmem
1510 on "Classic" PPC cores.
1514 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1516 nodelayacct [KNL] Disable per-task delay accounting
1518 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1520 nodsp [SH] Disable hardware DSP at boot time.
1522 noefi [X86] Disable EFI runtime services support.
1527 On X86-32 available only on PAE configured kernels.
1528 noexec=on: enable non-executable mappings (default)
1529 noexec=off: disable non-executable mappings
1532 This affects only 32-bit executables.
1533 noexec32=on: enable non-executable mappings (default)
1534 read doesn't imply executable mappings
1535 noexec32=off: disable non-executable mappings
1536 read implies executable mappings
1538 nofpu [SH] Disable hardware FPU at boot time.
1540 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1541 register save and restore. The kernel will only save
1542 legacy floating-point registers on task switch.
1544 noxsave [BUGS=X86] Disables x86 extended register state save
1545 and restore using xsave. The kernel will fallback to
1546 enabling legacy floating-point and sse state.
1548 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1549 wfi(ARM) instruction doesn't work correctly and not to
1550 use it. This is also useful when using JTAG debugger.
1552 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1553 instruction doesn't work correctly and not to
1556 no_file_caps Tells the kernel not to honor file capabilities. The
1557 only way then for a file to be executed with privilege
1558 is to be setuid root or executed by root.
1560 nohalt [IA-64] Tells the kernel not to use the power saving
1561 function PAL_HALT_LIGHT when idle. This increases
1562 power-consumption. On the positive side, it reduces
1563 interrupt wake-up latency, which may improve performance
1564 in certain environments such as networked servers or
1567 nohz= [KNL] Boottime enable/disable dynamic ticks
1568 Valid arguments: on, off
1571 noiotrap [SH] Disables trapped I/O port accesses.
1573 noirqdebug [X86-32] Disables the code which attempts to detect and
1574 disable unhandled interrupt sources.
1576 no_timer_check [X86,APIC] Disables the code which tests for
1577 broken timer IRQ sources.
1579 noisapnp [ISAPNP] Disables ISA PnP code.
1581 noinitrd [RAM] Tells the kernel not to load any configured
1586 nojitter [IA64] Disables jitter checking for ITC timers.
1588 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1590 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1592 noltlbs [PPC] Do not use large page/tlb entries for kernel
1593 lowmem mapping on PPC40x.
1595 nomca [IA-64] Disable machine check abort handling
1597 nomce [X86-32] Machine Check Exception
1599 nomfgpt [X86-32] Disable Multi-Function General Purpose
1600 Timer usage (for AMD Geode machines).
1602 norandmaps Don't use address space randomization. Equivalent to
1603 echo 0 > /proc/sys/kernel/randomize_va_space
1605 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1607 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1608 with UP alternatives
1610 noresidual [PPC] Don't use residual data on PReP machines.
1612 noresume [SWSUSP] Disables resume and restores original swap
1615 no-scroll [VGA] Disables scrollback.
1616 This is required for the Braillex ib80-piezo Braille
1617 reader made by F.H. Papenmeier (Germany).
1621 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1623 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1624 and disable the IO APIC. legacy for "maxcpus=0".
1626 nosoftlockup [KNL] Disable the soft-lockup detector.
1628 noswapaccount [KNL] Disable accounting of swap in memory resource
1629 controller. (See Documentation/cgroups/memory.txt)
1631 nosync [HW,M68K] Disables sync negotiation for all devices.
1633 notsc [BUGS=X86-32] Disable Time Stamp Counter
1635 nousb [USB] Disable the USB subsystem
1639 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1641 nptcg= [IA64] Override max number of concurrent global TLB
1642 purges which is reported from either PAL_VM_SUMMARY or
1645 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1647 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1648 one of ['zone', 'node', 'default'] can be specified
1649 This can be set from sysctl after boot.
1650 See Documentation/sysctl/vm.txt for details.
1652 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1653 See Documentation/debugging-via-ohci1394.txt for more
1656 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1657 Rather than timing out after 20 ms if an EC
1658 command is not properly ACKed, override the length
1659 of the timeout. We have interrupts disabled while
1660 waiting for the ACK, so if this is set too high
1661 interrupts *may* be lost!
1666 oprofile.timer= [HW]
1667 Use timer interrupt instead of performance counters
1669 osst= [HW,SCSI] SCSI Tape Driver
1670 Format: <buffer_size>,<write_threshold>
1671 See also Documentation/scsi/st.txt.
1673 panic= [KNL] Kernel behaviour on panic
1676 parkbd.port= [HW] Parallel port number the keyboard adapter is
1677 connected to, default is 0.
1679 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1680 0 for XT, 1 for AT (default is AT).
1683 parport= [HW,PPT] Specify parallel ports. 0 disables.
1684 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1685 Use 'auto' to force the driver to use any
1686 IRQ/DMA settings detected (the default is to
1687 ignore detected IRQ/DMA settings because of
1688 possible conflicts). You can specify the base
1689 address, IRQ, and DMA settings; IRQ and DMA
1690 should be numbers, or 'auto' (for using detected
1691 settings on that particular port), or 'nofifo'
1692 (to avoid using a FIFO even if it is detected).
1693 Parallel ports are assigned in the order they
1694 are specified on the command line, starting
1697 parport_init_mode= [HW,PPT]
1698 Configure VIA parallel port to operate in
1699 a specific mode. This is necessary on Pegasos
1700 computer where firmware has no options for setting
1701 up parallel port mode and sets it to spp.
1702 Currently this function knows 686a and 8231 chips.
1703 Format: [spp|ps2|epp|ecp|ecpepp]
1705 pas2= [HW,OSS] Format:
1706 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1709 See header of drivers/scsi/pas16.c.
1712 Halt all CPUs after the first oops has been printed for
1713 the specified number of seconds. This is to be used if
1714 your oopses keep scrolling off the screen.
1719 See header of drivers/block/paride/pcd.c.
1720 See also Documentation/blockdev/paride.txt.
1722 pci=option[,option...] [PCI] various PCI subsystem options:
1723 earlydump [X86] dump PCI config space before the kernel
1725 off [X86] don't probe for the PCI bus
1726 bios [X86-32] force use of PCI BIOS, don't access
1727 the hardware directly. Use this if your machine
1728 has a non-standard PCI host bridge.
1729 nobios [X86-32] disallow use of PCI BIOS, only direct
1730 hardware access methods are allowed. Use this
1731 if you experience crashes upon bootup and you
1732 suspect they are caused by the BIOS.
1733 conf1 [X86] Force use of PCI Configuration
1735 conf2 [X86] Force use of PCI Configuration
1737 noaer [PCIE] If the PCIEAER kernel config parameter is
1738 enabled, this kernel boot option can be used to
1739 disable the use of PCIE advanced error reporting.
1740 nodomains [PCI] Disable support for multiple PCI
1741 root domains (aka PCI segments, in ACPI-speak).
1742 nommconf [X86] Disable use of MMCONFIG for PCI
1744 nomsi [MSI] If the PCI_MSI kernel config parameter is
1745 enabled, this kernel boot option can be used to
1746 disable the use of MSI interrupts system-wide.
1747 noioapicquirk [APIC] Disable all boot interrupt quirks.
1748 Safety option to keep boot IRQs enabled. This
1749 should never be necessary.
1750 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1751 primary IO-APIC for bridges that cannot disable
1752 boot IRQs. This fixes a source of spurious IRQs
1753 when the system masks IRQs.
1754 noioapicreroute [APIC] Disable workaround that uses the
1755 boot IRQ equivalent of an IRQ that connects to
1756 a chipset where boot IRQs cannot be disabled.
1757 The opposite of ioapicreroute.
1758 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1759 routing table. These calls are known to be buggy
1760 on several machines and they hang the machine
1761 when used, but on other computers it's the only
1762 way to get the interrupt routing table. Try
1763 this option if the kernel is unable to allocate
1764 IRQs or discover secondary PCI buses on your
1766 rom [X86] Assign address space to expansion ROMs.
1767 Use with caution as certain devices share
1768 address decoders between ROMs and other
1770 norom [X86] Do not assign address space to
1771 expansion ROMs that do not already have
1772 BIOS assigned address ranges.
1773 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1774 assigned automatically to PCI devices. You can
1775 make the kernel exclude IRQs of your ISA cards
1777 pirqaddr=0xAAAAA [X86] Specify the physical address
1778 of the PIRQ table (normally generated
1779 by the BIOS) if it is outside the
1780 F0000h-100000h range.
1781 lastbus=N [X86] Scan all buses thru bus #N. Can be
1782 useful if the kernel is unable to find your
1783 secondary buses and you want to tell it
1784 explicitly which ones they are.
1785 assign-busses [X86] Always assign all PCI bus
1786 numbers ourselves, overriding
1787 whatever the firmware may have done.
1788 usepirqmask [X86] Honor the possible IRQ mask stored
1789 in the BIOS $PIR table. This is needed on
1790 some systems with broken BIOSes, notably
1791 some HP Pavilion N5400 and Omnibook XE3
1792 notebooks. This will have no effect if ACPI
1793 IRQ routing is enabled.
1794 noacpi [X86] Do not use ACPI for IRQ routing
1795 or for PCI scanning.
1796 use_crs [X86] Use _CRS for PCI resource
1798 routeirq Do IRQ routing for all PCI devices.
1799 This is normally done in pci_enable_device(),
1800 so this option is a temporary workaround
1801 for broken drivers that don't call it.
1802 skip_isa_align [X86] do not align io start addr, so can
1803 handle more pci cards
1804 firmware [ARM] Do not re-enumerate the bus but instead
1805 just use the configuration from the
1806 bootloader. This is currently used on
1807 IXP2000 systems where the bus has to be
1808 configured a certain way for adjunct CPUs.
1809 noearly [X86] Don't do any early type 1 scanning.
1810 This might help on some broken boards which
1811 machine check when some devices' config space
1812 is read. But various workarounds are disabled
1813 and some IOMMU drivers will not work.
1814 bfsort Sort PCI devices into breadth-first order.
1815 This sorting is done to get a device
1816 order compatible with older (<= 2.4) kernels.
1817 nobfsort Don't sort PCI devices into breadth-first order.
1818 cbiosize=nn[KMG] The fixed amount of bus space which is
1819 reserved for the CardBus bridge's IO window.
1820 The default value is 256 bytes.
1821 cbmemsize=nn[KMG] The fixed amount of bus space which is
1822 reserved for the CardBus bridge's memory
1823 window. The default value is 64 megabytes.
1826 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1827 Specifies alignment and device to reassign
1828 aligned memory resources.
1829 If <order of align> is not specified,
1830 PAGE_SIZE is used as alignment.
1831 PCI-PCI bridge can be specified, if resource
1832 windows need to be expanded.
1834 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1837 force Enable ASPM even on devices that claim not to support it.
1838 WARNING: Forcing ASPM on may cause system lockups.
1840 pcmv= [HW,PCMCIA] BadgePAD 4
1843 See Documentation/blockdev/paride.txt.
1845 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1848 See arch/parisc/kernel/pdc_chassis.c
1851 See Documentation/blockdev/paride.txt.
1854 See Documentation/blockdev/paride.txt.
1856 pirq= [SMP,APIC] Manual mp-table setup
1857 See Documentation/x86/i386/IO-APIC.txt.
1859 plip= [PPT,NET] Parallel port network link
1860 Format: { parport<nr> | timid | 0 }
1861 See also Documentation/parport.txt.
1863 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1864 Override pmtimer IOPort with a hex value.
1868 Enable PNP debug messages. This depends on the
1869 CONFIG_PNP_DEBUG_MESSAGES option.
1875 { on | off | curr | res | no-curr | no-res }
1878 [ISAPNP] Exclude IRQs for the autoconfiguration
1881 [ISAPNP] Exclude DMAs for the autoconfiguration
1883 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1884 Ranges are in pairs (I/O port base and size).
1887 [ISAPNP] Exclude memory regions for the
1889 Ranges are in pairs (memory base and size).
1891 ports= [IP_VS_FTP] IPVS ftp helper module
1893 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1895 Format: <port>,<port>....
1897 print-fatal-signals=
1898 [KNL] debug: print fatal signals
1899 print-fatal-signals=1: print segfault info to
1903 printk.time= Show timing data prefixed to each printk message line
1904 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1906 processor.max_cstate= [HW,ACPI]
1907 Limit processor to maximum C-state
1908 max_cstate=9 overrides any DMI blacklist limit.
1910 processor.nocst [HW,ACPI]
1911 Ignore the _CST method to determine C-states,
1912 instead using the legacy FADT method
1914 profile= [KNL] Enable kernel profiling via /proc/profile
1915 Format: [schedule,]<number>
1916 Param: "schedule" - profile schedule points.
1917 Param: <number> - step/bucket size as a power of 2 for
1918 statistical time based profiling.
1919 Param: "sleep" - profile D-state sleeping (millisecs).
1920 Requires CONFIG_SCHEDSTATS
1921 Param: "kvm" - profile VM exits.
1923 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1925 See Documentation/blockdev/ramdisk.txt.
1927 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1928 probe for; one of (bare|imps|exps|lifebook|any).
1929 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1931 psmouse.resetafter= [HW,MOUSE]
1932 Try to reset the device after so many bad packets
1935 [HW,MOUSE] Set desired mouse resolution, in dpi.
1936 psmouse.smartscroll=
1937 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1938 0 = disabled, 1 = enabled (default).
1940 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1942 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1945 See Documentation/blockdev/paride.txt.
1948 [KNL] Number of legacy pty's. Overwrites compiled-in
1951 quiet [KNL] Disable most log messages
1956 See Documentation/md.txt.
1958 ramdisk_blocksize= [RAM]
1959 See Documentation/blockdev/ramdisk.txt.
1961 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1962 See Documentation/blockdev/ramdisk.txt.
1964 rcupdate.blimit= [KNL,BOOT]
1965 Set maximum number of finished RCU callbacks to process
1968 rcupdate.qhimark= [KNL,BOOT]
1969 Set threshold of queued
1970 RCU callbacks over which batch limiting is disabled.
1972 rcupdate.qlowmark= [KNL,BOOT]
1973 Set threshold of queued RCU callbacks below which
1974 batch limiting is re-enabled.
1978 Run specified binary instead of /init from the ramdisk,
1979 used for early userspace startup. See initrd.
1981 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1982 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1983 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1986 [KNL, SMP] Set scheduler's default relax_domain_level.
1987 See Documentation/cgroups/cpusets.txt.
1989 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1991 reservetop= [X86-32]
1993 Reserves a hole at the top of the kernel virtual
1996 reset_devices [KNL] Force drivers to reset the underlying device
1997 during initialization.
2000 Specify the partition device for software suspend
2002 resume_offset= [SWSUSP]
2003 Specify the offset from the beginning of the partition
2004 given by "resume=" at which the swap header is located,
2005 in <PAGE_SIZE> units (needed only for swap files).
2006 See Documentation/power/swsusp-and-swap-files.txt
2008 retain_initrd [RAM] Keep initrd memory after extraction
2010 rhash_entries= [KNL,NET]
2011 Set number of hash buckets for route cache
2013 riscom8= [HW,SERIAL]
2014 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2016 ro [KNL] Mount root device read-only on boot
2018 root= [KNL] Root filesystem
2020 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2021 mount the root filesystem
2023 rootflags= [KNL] Set root filesystem mount option string
2025 rootfstype= [KNL] Set root filesystem type
2027 rootwait [KNL] Wait (indefinitely) for root device to show up.
2028 Useful for devices that are detected asynchronously
2029 (e.g. USB and MMC devices).
2031 root_plug.vendor_id=
2032 [ROOTPLUG] Override the default vendor ID
2034 root_plug.product_id=
2035 [ROOTPLUG] Override the default product ID
2038 [ROOTPLUG] Enable debugging output
2040 rw [KNL] Mount root device read-write on boot
2042 S [KNL] Run init in single mode
2045 See drivers/net/irda/sa1100_ir.c.
2047 sbni= [NET] Granch SBNI12 leased line adapter
2049 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2050 Format: <io>[,<timeout>[,<isapnp>]]
2052 scsi_debug_*= [SCSI]
2053 See drivers/scsi/scsi_debug.c.
2055 scsi_default_dev_flags=
2056 [SCSI] SCSI default device flags
2059 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2060 Format: <vendor>:<model>:<flags>
2061 (flags are integer value)
2063 scsi_logging_level= [SCSI] a bit mask of logging levels
2064 See drivers/scsi/scsi_logging.h for bits. Also
2065 settable via sysctl at dev.scsi.logging_level
2066 (/proc/sys/dev/scsi/logging_level).
2067 There is also a nice 'scsi_logging_level' script in the
2068 S390-tools package, available for download at
2069 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2071 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2072 discovered. async scans them in kernel threads,
2073 allowing boot to proceed. none ignores them, expecting
2074 user space to do the scan.
2076 security= [SECURITY] Choose a security module to enable at boot.
2077 If this boot parameter is not specified, only the first
2078 security module asking for security registration will be
2079 loaded. An invalid security module name will be treated
2080 as if no module has been chosen.
2082 selinux= [SELINUX] Disable or enable SELinux at boot time.
2083 Format: { "0" | "1" }
2084 See security/selinux/Kconfig help text.
2087 Default value is set via kernel config option.
2088 If enabled at boot time, /selinux/disable can be used
2089 later to disable prior to initial policy load.
2091 serialnumber [BUGS=X86-32]
2094 Maximal number of shapers.
2096 show_msr= [x86] show boot-time MSR settings
2097 Format: { <integer> }
2098 Show boot-time (BIOS-initialized) MSR settings.
2099 The parameter means the number of CPUs to show,
2100 for example 1 means boot CPU only.
2103 See header of drivers/scsi/sim710.c.
2110 slub_debug[=options[,slabs]] [MM, SLUB]
2111 Enabling slub_debug allows one to determine the
2112 culprit if slab objects become corrupted. Enabling
2113 slub_debug can create guard zones around objects and
2114 may poison objects when not in use. Also tracks the
2115 last alloc / free. For more information see
2116 Documentation/vm/slub.txt.
2118 slub_max_order= [MM, SLUB]
2119 Determines the maximum allowed order for slabs.
2120 A high setting may cause OOMs due to memory
2121 fragmentation. For more information see
2122 Documentation/vm/slub.txt.
2124 slub_min_objects= [MM, SLUB]
2125 The minimum number of objects per slab. SLUB will
2126 increase the slab order up to slub_max_order to
2127 generate a sufficiently large slab able to contain
2128 the number of objects indicated. The higher the number
2129 of objects the smaller the overhead of tracking slabs
2130 and the less frequently locks need to be acquired.
2131 For more information see Documentation/vm/slub.txt.
2133 slub_min_order= [MM, SLUB]
2134 Determines the mininum page order for slabs. Must be
2135 lower than slub_max_order.
2136 For more information see Documentation/vm/slub.txt.
2138 slub_nomerge [MM, SLUB]
2139 Disable merging of slabs with similar size. May be
2140 necessary if there is some reason to distinguish
2141 allocs to different slabs. Debug options disable
2142 merging on their own.
2143 For more information see Documentation/vm/slub.txt.
2146 Format: <io1>[,<io2>[,...,<io8>]]
2148 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2149 attempt to substitute SMP alternatives once at boot.
2151 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2152 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2153 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2154 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2155 smsc-ircc2.ircc_irq= [HW] IRQ line
2156 smsc-ircc2.ircc_dma= [HW] DMA channel
2157 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2158 0: Toshiba Satellite 1800 (GP data pin select)
2159 1: Fast pin select (default)
2162 snd-ad1816a= [HW,ALSA]
2164 snd-ad1848= [HW,ALSA]
2166 snd-ali5451= [HW,ALSA]
2168 snd-als100= [HW,ALSA]
2170 snd-als4000= [HW,ALSA]
2172 snd-azt2320= [HW,ALSA]
2174 snd-cmi8330= [HW,ALSA]
2176 snd-cmipci= [HW,ALSA]
2178 snd-cs4231= [HW,ALSA]
2180 snd-cs4232= [HW,ALSA]
2182 snd-cs4236= [HW,ALSA]
2184 snd-cs4281= [HW,ALSA]
2186 snd-cs46xx= [HW,ALSA]
2188 snd-dt019x= [HW,ALSA]
2190 snd-dummy= [HW,ALSA]
2192 snd-emu10k1= [HW,ALSA]
2194 snd-ens1370= [HW,ALSA]
2196 snd-ens1371= [HW,ALSA]
2198 snd-es968= [HW,ALSA]
2200 snd-es1688= [HW,ALSA]
2202 snd-es18xx= [HW,ALSA]
2204 snd-es1938= [HW,ALSA]
2206 snd-es1968= [HW,ALSA]
2208 snd-fm801= [HW,ALSA]
2210 snd-gusclassic= [HW,ALSA]
2212 snd-gusextreme= [HW,ALSA]
2214 snd-gusmax= [HW,ALSA]
2218 snd-ice1712= [HW,ALSA]
2220 snd-intel8x0= [HW,ALSA]
2222 snd-interwave= [HW,ALSA]
2227 snd-korg1212= [HW,ALSA]
2229 snd-maestro3= [HW,ALSA]
2231 snd-mpu401= [HW,ALSA]
2233 snd-mtpav= [HW,ALSA]
2235 snd-nm256= [HW,ALSA]
2237 snd-opl3sa2= [HW,ALSA]
2245 snd-opti93x= [HW,ALSA]
2249 snd-rme32= [HW,ALSA]
2251 snd-rme96= [HW,ALSA]
2253 snd-rme9652= [HW,ALSA]
2259 snd-sbawe= [HW,ALSA]
2261 snd-serial= [HW,ALSA]
2263 snd-sgalaxy= [HW,ALSA]
2265 snd-sonicvibes= [HW,ALSA]
2270 snd-sun-cs4231= [HW,ALSA]
2272 snd-trident= [HW,ALSA]
2274 snd-usb-audio= [HW,ALSA,USB]
2276 snd-via82xx= [HW,ALSA]
2278 snd-virmidi= [HW,ALSA]
2280 snd-wavefront= [HW,ALSA]
2282 snd-ymfpci= [HW,ALSA]
2285 [KNL] Should the soft-lockup detector generate panics.
2287 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2288 See Documentation/sonypi.txt
2290 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2291 See Documentation/serial/specialix.txt.
2293 spia_io_base= [HW,MTD]
2299 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2301 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2302 See Documentation/scsi/st.txt.
2305 Enabled the stack tracer on boot up.
2309 Set the STI (builtin display/keyboard on the HP-PARISC
2310 machines) console (graphic card) which should be used
2311 as the initial boot-console.
2312 See also comment in drivers/video/console/sticore.c.
2315 See comment in drivers/video/console/sticore.c.
2318 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2322 Control how the NFS server code allocates CPUs to
2323 service thread pools. Depending on how many NICs
2324 you have and where their interrupts are bound, this
2325 option will affect which CPUs will do NFS serving.
2326 Note: this parameter cannot be changed while the
2327 NFS server is running.
2329 auto the server chooses an appropriate mode
2330 automatically using heuristics
2331 global a single global pool contains all CPUs
2332 percpu one pool for each CPU
2333 pernode one pool for each NUMA node (equivalent
2334 to global on non-NUMA machines)
2336 swiotlb= [IA-64] Number of I/O TLB slabs
2340 sym53c416= [HW,SCSI]
2341 See header of drivers/scsi/sym53c416.c.
2343 sysrq_always_enabled
2345 Ignore sysrq setting - this boot parameter will
2346 neutralize any effect of /proc/sys/kernel/sysrq.
2347 Useful for debugging.
2350 See header of drivers/scsi/t128.c.
2354 test_suspend= [SUSPEND]
2355 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2356 standby suspend) as the system sleep state to briefly
2357 enter during system startup. The system is woken from
2358 this state using a wakeup-capable RTC alarm.
2360 thash_entries= [KNL,NET]
2361 Set number of hash buckets for TCP connection
2363 thermal.act= [HW,ACPI]
2364 -1: disable all active trip points in all thermal zones
2365 <degrees C>: override all lowest active trip points
2367 thermal.crt= [HW,ACPI]
2368 -1: disable all critical trip points in all thermal zones
2369 <degrees C>: override all critical trip points
2371 thermal.nocrt= [HW,ACPI]
2372 Set to disable actions on ACPI thermal zone
2373 critical and hot trip points.
2375 thermal.off= [HW,ACPI]
2376 1: disable ACPI thermal control
2378 thermal.psv= [HW,ACPI]
2379 -1: disable all passive trip points
2380 <degrees C>: override all passive trip points to this
2383 thermal.tzp= [HW,ACPI]
2384 Specify global default ACPI thermal zone polling rate
2385 <deci-seconds>: poll all this frequency
2386 0: no polling (default)
2389 See comment before function dc390_setup() in
2390 drivers/scsi/tmscsim.c.
2394 Specify if the kernel should make use of the cpu
2395 topology informations if the hardware supports these.
2396 The scheduler will make use of these informations and
2397 e.g. base its process migration decisions on it.
2402 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2404 trix= [HW,OSS] MediaTrix AudioTrix Pro
2406 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2408 tsc= Disable clocksource-must-verify flag for TSC.
2410 [x86] reliable: mark tsc clocksource as reliable, this
2411 disables clocksource verification at runtime.
2412 Used to enable high-resolution timer mode on older
2413 hardware, and in virtualized environment.
2415 turbografx.map[2|3]= [HW,JOY]
2416 TurboGraFX parallel port interface
2418 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2419 See also Documentation/input/joystick-parport.txt
2421 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2422 See header of drivers/scsi/u14-34f.c.
2431 [USB] Ignore overcurrent events (default N).
2432 Some badly-designed motherboards generate lots of
2433 bogus events, for ports that aren't wired to
2434 anything. Set this parameter to avoid log spamming.
2435 Note that genuine overcurrent events won't be
2440 Set unknown_nmi_panic=1 early on boot.
2442 usbcore.autosuspend=
2443 [USB] The autosuspend time delay (in seconds) used
2444 for newly-detected USB devices (default 2). This
2445 is the time required before an idle device will be
2446 autosuspended. Devices for which the delay is set
2447 to a negative value won't be autosuspended at all.
2449 usbcore.usbfs_snoop=
2450 [USB] Set to log all usbfs traffic (default 0 = off).
2452 usbcore.blinkenlights=
2453 [USB] Set to cycle leds on hubs (default 0 = off).
2455 usbcore.old_scheme_first=
2456 [USB] Start with the old device initialization
2457 scheme (default 0 = off).
2459 usbcore.use_both_schemes=
2460 [USB] Try the other device initialization scheme
2461 if the first one fails (default 1 = enabled).
2463 usbcore.initial_descriptor_timeout=
2464 [USB] Specifies timeout for the initial 64-byte
2465 USB_REQ_GET_DESCRIPTOR request in milliseconds
2466 (default 5000 = 5.0 seconds).
2469 [USBHID] The interval which mice are to be polled at.
2471 usb-storage.delay_use=
2472 [UMS] The delay in seconds before a new device is
2473 scanned for Logical Units (default 5).
2476 [UMS] A list of quirks entries to supplement or
2477 override the built-in unusual_devs list. List
2478 entries are separated by commas. Each entry has
2479 the form VID:PID:Flags where VID and PID are Vendor
2480 and Product ID values (4-digit hex numbers) and
2481 Flags is a set of characters, each corresponding
2482 to a common usb-storage quirk flag as follows:
2483 a = SANE_SENSE (collect more than 18 bytes
2485 c = FIX_CAPACITY (decrease the reported
2486 device capacity by one sector);
2487 h = CAPACITY_HEURISTICS (decrease the
2488 reported device capacity by one
2489 sector if the number is odd);
2490 i = IGNORE_DEVICE (don't bind to this
2492 l = NOT_LOCKABLE (don't try to lock and
2493 unlock ejectable media);
2494 m = MAX_SECTORS_64 (don't transfer more
2495 than 64 sectors = 32 KB at a time);
2496 o = CAPACITY_OK (accept the capacity
2497 reported by the device);
2498 r = IGNORE_RESIDUE (the device reports
2499 bogus residue values);
2500 s = SINGLE_LUN (the device has only one
2502 w = NO_WP_DETECT (don't test whether the
2503 medium is write-protected).
2504 Example: quirks=0419:aaf5:rl,0421:0433:rc
2507 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2508 vdso=1: enable VDSO (default)
2509 vdso=0: disable VDSO mapping
2512 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2513 vdso32=1: enable 32-bit VDSO (default)
2514 vdso32=0: disable 32-bit VDSO mapping
2517 vector=percpu: enable percpu vector domain
2519 video= [FB] Frame buffer configuration
2520 See Documentation/fb/modedb.txt.
2522 vga= [BOOT,X86-32] Select a particular video mode
2523 See Documentation/x86/boot.txt and
2524 Documentation/svga.txt.
2525 Use vga=ask for menu.
2526 This is actually a boot loader parameter; the value is
2527 passed to the kernel using a special protocol.
2529 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2530 size of <nn>. This can be used to increase the
2531 minimum size (128MB on x86). It can also be used to
2532 decrease the size and leave more room for directly
2535 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2538 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2541 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2544 vt.default_blu= [VT]
2545 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2546 Change the default blue palette of the console.
2547 This is a 16-member array composed of values
2550 vt.default_grn= [VT]
2551 Format: <green0>,<green1>,<green2>,...,<green15>
2552 Change the default green palette of the console.
2553 This is a 16-member array composed of values
2556 vt.default_red= [VT]
2557 Format: <red0>,<red1>,<red2>,...,<red15>
2558 Change the default red palette of the console.
2559 This is a 16-member array composed of values
2565 Set system-wide default UTF-8 mode for all tty's.
2566 Default is 1, i.e. UTF-8 mode is enabled for all
2567 newly opened terminals.
2569 waveartist= [HW,OSS]
2570 Format: <io>,<irq>,<dma>,<dma2>
2573 See header of drivers/scsi/wd33c93.c.
2576 See header of drivers/scsi/wd7000.c.
2579 See Documentation/watchdog/wdt.txt.
2581 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2582 default x2apic cluster mode on platforms
2585 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2586 xd_geo= See header of drivers/block/xd.c.
2588 xirc2ps_cs= [NET,PCMCIA]
2590 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2592 ______________________________________________________________________
2596 Add documentation for ALSA options.
2597 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob