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 cmo_free_hint= [PPC] Format: { yes | no }
501 Specify whether pages are marked as being inactive
502 when they are freed. This is used in CMO environments
503 to determine OS memory pressure for page stealing by
507 code_bytes [X86] How many bytes of object code to print
512 com20020= [HW,NET] ARCnet - COM20020 chipset
514 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
516 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
520 ARCnet - COM90xx chipset (memory-mapped buffers)
521 Format: <io>[,<irq>[,<memstart>]]
523 condev= [HW,S390] console device
526 console= [KNL] Output console device and options.
528 tty<n> Use the virtual console device <n>.
532 Use the specified serial port. The options are of
533 the form "bbbbpnf", where "bbbb" is the baud rate,
534 "p" is parity ("n", "o", or "e"), "n" is number of
535 bits, and "f" is flow control ("r" for RTS or
536 omit it). Default is "9600n8".
538 See Documentation/serial-console.txt for more
540 Documentation/networking/netconsole.txt for an
543 uart[8250],io,<addr>[,options]
544 uart[8250],mmio,<addr>[,options]
545 Start an early, polled-mode console on the 8250/16550
546 UART at the specified I/O port or MMIO address,
547 switching to the matching ttyS device later. The
548 options are the same as for ttyS, above.
550 If the device connected to the port is not a TTY but a braille
551 device, prepend "brl," before the device type, for instance
553 For now, only VisioBraille is supported.
556 [KNL] Change the default value for
557 /proc/<pid>/coredump_filter.
558 See also Documentation/filesystems/proc.txt.
560 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
562 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
564 crashkernel=nn[KMG]@ss[KMG]
565 [KNL] Reserve a chunk of physical memory to
566 hold a kernel to switch to with kexec on panic.
568 crashkernel=range1:size1[,range2:size2,...][@offset]
569 [KNL] Same as above, but depends on the memory
570 in the running system. The syntax of range is
571 start-[end] where start and end are both
572 a memory unit (amount[KMG]). See also
573 Documentation/kdump/kdump.txt for a example.
578 cs89x0_media= [HW,NET]
579 Format: { rj45 | aui | bnc }
582 See header of drivers/s390/block/dasd_devmap.c.
584 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
585 (one device per port)
586 Format: <port#>,<type>
587 See also Documentation/input/joystick-parport.txt
589 debug [KNL] Enable kernel debugging (events log level).
592 [KNL] verbose self-tests
594 Print debugging info while doing the locking API
596 We default to 0 (no extra messages), setting it to
597 1 will print _a lot_ more information - normally
598 only useful to kernel developers.
600 debug_objects [KNL] Enable object debugging
603 [KNL] Disable object debugging
605 debugpat [X86] Enable PAT debugging
607 decnet.addr= [HW,NET]
608 Format: <area>[,<node>]
609 See also Documentation/networking/decnet.txt.
612 [same as hugepagesz=] The size of the default
613 HugeTLB page size. This is the size represented by
614 the legacy /proc/ hugepages APIs, used for SHM, and
615 default size when mounting hugetlbfs filesystems.
616 Defaults to the default architecture's huge page size
620 Set number of hash buckets for dentry cache.
623 IO parameters + enable/disable command.
625 digiepca= [HW,SERIAL]
626 See drivers/char/README.epca and
627 Documentation/serial/digiepca.txt.
629 disable_mtrr_cleanup [X86]
630 The kernel tries to adjust MTRR layout from continuous
631 to discrete, to make X server driver able to add WB
632 entry later. This parameter disables that.
634 disable_mtrr_trim [X86, Intel and AMD only]
635 By default the kernel will trim any uncacheable
636 memory out of your available memory pool based on
637 MTRR settings. This parameter disables that behavior,
638 possibly causing your machine to run very slowly.
640 disable_timer_pin_1 [X86]
641 Disable PIN 1 of APIC timer
642 Can be useful to work around chipset bugs.
644 dmasound= [HW,OSS] Sound subsystem buffers
646 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
647 this option disables the debugging code at boot.
649 dma_debug_entries=<number>
650 This option allows to tune the number of preallocated
651 entries for DMA-API debugging code. One entry is
652 required per DMA-API allocation. Use this if the
653 DMA-API debugging code disables itself because the
654 architectural default is too low.
660 dynamic_printk Enables pr_debug()/dev_dbg() calls if
661 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
662 These can also be switched on/off via
663 <debugfs>/dynamic_printk/modules
665 earlycon= [KNL] Output early console device and options.
666 uart[8250],io,<addr>[,options]
667 uart[8250],mmio,<addr>[,options]
668 Start an early, polled-mode console on the 8250/16550
669 UART at the specified I/O port or MMIO address.
670 The options are the same as for ttyS, above.
672 earlyprintk= [X86,SH,BLACKFIN]
674 earlyprintk=serial[,ttySn[,baudrate]]
677 Append ",keep" to not disable it when the real console
680 Only vga or serial or usb debug port at a time.
682 Currently only ttyS0 and ttyS1 are supported.
684 Interaction with the standard serial driver is not
687 The VGA output is eventually overwritten by the real
693 Format: {"off" | "on" | "skip[mbr]"}
695 eisa_irq_edge= [PARISC,HW]
696 See header of drivers/parisc/eisa.c.
699 See comment before function elanfreq_setup() in
700 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
703 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
704 See Documentation/block/as-iosched.txt and
705 Documentation/block/deadline-iosched.txt for details.
707 elfcorehdr= [IA64,PPC,SH,X86]
708 Specifies physical address of start of kernel core
709 image elf header. Generally kexec loader will
710 pass this option to capture kernel.
711 See Documentation/kdump/kdump.txt for details.
713 enable_mtrr_cleanup [X86]
714 The kernel tries to adjust MTRR layout from continuous
715 to discrete, to make X server driver able to add WB
716 entry later. This parameter enables that.
718 enable_timer_pin_1 [X86]
719 Enable PIN 1 of APIC timer
720 Can be useful to work around chipset bugs
721 (in particular on some ATI chipsets).
722 The kernel tries to set a reasonable default.
724 enforcing [SELINUX] Set initial enforcing status.
726 See security/selinux/Kconfig help text.
727 0 -- permissive (log only, no denials).
728 1 -- enforcing (deny and log).
730 Value can be changed at runtime via /selinux/enforce.
732 ether= [HW,NET] Ethernet cards parameters
733 This option is obsoleted by the "netdev=" option, which
734 has equivalent usage. See its documentation for details.
736 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
741 fail_make_request=[KNL]
742 General fault injection mechanism.
743 Format: <interval>,<probability>,<space>,<times>
744 See also /Documentation/fault-injection/.
747 See header of drivers/scsi/fd_mcs.c.
750 See header of drivers/scsi/fdomain.c.
753 See Documentation/blockdev/floppy.txt.
755 force_pal_cache_flush
756 [IA-64] Avoid check_sal_cache_flush which may hang on
757 buggy SAL_CACHE_FLUSH implementations. Using this
758 parameter will force ia64_sal_cache_flush to call
759 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
762 [ftrace] will set and start the specified tracer
763 as early as possible in order to facilitate early
767 [ftrace] will dump the trace buffers on oops.
770 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
771 support via parallel port (up to 5 devices per port)
772 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
773 See also Documentation/input/joystick-parport.txt
777 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
782 See header of drivers/scsi/gdth.c.
784 gpt [EFI] Forces disk with valid GPT signature but
785 invalid Protective MBR to be treated as GPT.
789 hashdist= [KNL,NUMA] Large hashes allocated during boot
790 are distributed across NUMA nodes. Defaults on
791 for 64bit NUMA, off otherwise.
792 Format: 0 | 1 (for off | on)
794 hcl= [IA-64] SGI's Hardware Graph compatibility layer
796 hd= [EIDE] (E)IDE hard drive subsystem geometry
797 Format: <cyl>,<head>,<sect>
799 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
800 size of <nn>. This works even on boxes that have no
801 highmem otherwise. This also works to reduce highmem
802 size on bigger boxes.
804 highres= [KNL] Enable/disable high resolution timer mode.
805 Valid parameters: "on", "off"
809 See Documentation/isdn/README.HiSax.
813 hpet= [X86-32,HPET] option to control HPET usage
814 Format: { enable (default) | disable | force |
816 disable: disable HPET and use PIT instead
817 force: allow force enabled of undocumented chips (ICH4,
819 verbose: show contents of HPET registers during setup
821 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
822 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
823 On x86-64 and powerpc, this option can be specified
824 multiple times interleaved with hugepages= to reserve
825 huge pages of different sizes. Valid pages sizes on
826 x86-64 are 2M (when the CPU supports "pse") and 1G
827 (when the CPU supports the "pdpe1gb" cpuinfo flag)
828 Note that 1GB pages can only be allocated at boot time
829 using hugepages= and not freed afterwards.
831 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
832 terminal devices. Valid values: 0..8
833 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
834 If specified, z/VM IUCV HVC accepts connections
835 from listed z/VM user IDs only.
837 i2c_bus= [HW] Override the default board specific I2C bus speed
838 or register an additional I2C bus that is not
839 registered from board initialization code.
843 i8042.debug [HW] Toggle i8042 debug mode
844 i8042.direct [HW] Put keyboard port into non-translated mode
845 i8042.dumbkbd [HW] Pretend that controller can only read data from
846 keyboard and cannot control its state
847 (Don't attempt to blink the leds)
848 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
849 i8042.nokbd [HW] Don't check/create keyboard port
850 i8042.noloop [HW] Disable the AUX Loopback command while probing
852 i8042.nomux [HW] Don't check presence of an active multiplexing
854 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
857 [HW] Frequency with which keyboard LEDs should blink
858 when kernel panics (default is 0.5 sec)
859 i8042.reset [HW] Reset the controller during init and cleanup
860 i8042.unlock [HW] Unlock (ignore) the keylock
864 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
865 indicates that the driver is running on unsupported
867 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
868 does not match list of supported models.
870 [HW] Report power status in /proc/i8k
871 (disabled by default)
872 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
875 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
876 See Documentation/mca.txt.
879 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
881 ide-core.nodma= [HW] (E)IDE subsystem
882 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
883 .vlb_clock .pci_clock .noflush .noprobe .nowerr .cdrom
884 .chs .ignore_cable are additional options
885 See Documentation/ide/ide.txt.
887 idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
888 See Documentation/ide/ide.txt.
890 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
891 Claim all unknown PCI IDE storage controllers.
894 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
895 Poll forces a polling idle loop that can slightly
896 improve the performance of waking up a idle CPU, but
897 will use a lot of power and make the system run hot.
899 idle=mwait: On systems which support MONITOR/MWAIT but
900 the kernel chose to not use it because it doesn't save
901 as much power as a normal idle loop, use the
902 MONITOR/MWAIT idle loop anyways. Performance should be
903 the same as idle=poll.
904 idle=halt: Halt is forced to be used for CPU idle.
905 In such case C2/C3 won't be used again.
906 idle=nomwait: Disable mwait for CPU C-states
908 ignore_loglevel [KNL]
909 Ignore loglevel setting - this will print /all/
910 kernel messages to the console. Useful for debugging.
913 Set number of hash buckets for inode cache.
916 Format: { "0" | "1" }
917 0 -- integrity auditing messages. (Default)
918 1 -- enable informational integrity auditing messages.
921 Formt: { "sha1" | "md5" }
925 See header of drivers/scsi/in2000.c.
929 Run specified binary instead of /sbin/init as init
932 initcall_debug [KNL] Trace initcalls as they are executed. Useful
933 for working out where the kernel is dying during
936 initrd= [BOOT] Specify the location of the initial ramdisk
938 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
941 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
943 Enable intel iommu driver.
945 Disable intel iommu driver.
946 igfx_off [Default Off]
947 By default, gfx is mapped as normal device. If a gfx
948 device has a dedicated DMAR unit, the DMAR unit is
949 bypassed by not enabling DMAR with this option. In
950 this case, gfx device will use physical address for
953 With this option iommu will not optimize to look
954 for io virtual address below 32 bit forcing dual
955 address cycle on pci bus for cards supporting greater
956 than 32 bit addressing. The default is to look
957 for translation below 32 bit and if not available
958 then look in the higher range.
960 With this option on every unmap_single operation will
961 result in a hardware IOTLB flush operation as opposed
962 to batching them for performance.
966 iomem= Disable strict checking of access to MMIO memory
967 strict regions from userspace.
982 io7= [HW] IO7 for Marvel based alpha systems
983 See comment before marvel_specify_io7 in
984 arch/alpha/kernel/core_marvel.c.
986 io_delay= [X86] I/O delay method
988 Standard port 0x80 based delay
990 Alternate port 0xed based delay (needed on some systems)
992 Simple two microseconds delay
997 See Documentation/filesystems/nfsroot.txt.
999 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1000 See comment before ip2_setup() in
1001 drivers/char/ip2/ip2base.c.
1003 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1004 See header of drivers/scsi/ips.c.
1007 When an interrupt is not handled search all handlers
1008 for it. Intended to get systems with badly broken
1012 When an interrupt is not handled search all handlers
1013 for it. Also check all handlers each timer
1014 interrupt. Intended to get systems with badly broken
1018 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1020 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1022 <cpu number>,...,<cpu number>
1024 <cpu number>-<cpu number>
1025 (must be a positive range in ascending order)
1027 <cpu number>,...,<cpu number>-<cpu number>
1029 This option can be used to specify one or more CPUs
1030 to isolate from the general SMP balancing and scheduling
1031 algorithms. You can move a process onto or off an
1032 "isolated" CPU via the CPU affinity syscalls or cpuset.
1033 <cpu number> begins at 0 and the maximum value is
1034 "number of CPUs in system - 1".
1036 This option is the preferred way to isolate CPUs. The
1037 alternative -- manually setting the CPU mask of all
1038 tasks in the system -- can cause problems and
1039 suboptimal load balancer performance.
1043 js= [HW,JOY] Analog joystick
1044 See Documentation/input/joystick.txt.
1048 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1049 specifies the amount of memory usable by the kernel
1050 for non-movable allocations. The requested amount is
1051 spread evenly throughout all nodes in the system. The
1052 remaining memory in each node is used for Movable
1053 pages. In the event, a node is too small to have both
1054 kernelcore and Movable pages, kernelcore pages will
1055 take priority and other nodes will have a larger number
1056 of kernelcore pages. The Movable zone is used for the
1057 allocation of pages that may be reclaimed or moved
1058 by the page migration subsystem. This means that
1059 HugeTLB pages may not be allocated from this zone.
1060 Note that allocations like PTEs-from-HighMem still
1061 use the HighMem zone if it exists, and the Normal
1062 zone if it does not.
1064 kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
1065 Controls whether kmemtrace is enabled
1068 kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
1069 subbufs kmemtrace's relay channel has. Set this
1070 higher than default (KMEMTRACE_N_SUBBUFS in code) if
1071 you experience buffer overruns.
1073 kgdboc= [HW] kgdb over consoles.
1074 Requires a tty driver that supports console polling.
1075 (only serial suported for now)
1076 Format: <serial_device>[,baud]
1078 kmac= [MIPS] korina ethernet MAC address.
1079 Configure the RouterBoard 532 series on-chip
1080 Ethernet adapter MAC address.
1082 kstack=N [X86] Print N words from the kernel stack
1089 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1092 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1095 libata.dma= [LIBATA] DMA control
1096 libata.dma=0 Disable all PATA and SATA DMA
1097 libata.dma=1 PATA and SATA Disk DMA only
1098 libata.dma=2 ATAPI (CDROM) DMA only
1099 libata.dma=4 Compact Flash DMA only
1100 Combinations also work, so libata.dma=3 enables DMA
1101 for disks and CDROMs, but not CFs.
1103 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1107 libata.force= [LIBATA] Force configurations. The format is comma
1108 separated list of "[ID:]VAL" where ID is
1109 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1110 matching port, link or device. Basically, it matches
1111 the ATA ID string printed on console by libata. If
1112 the whole ID part is omitted, the last PORT and DEVICE
1113 values are used. If ID hasn't been specified yet, the
1114 configuration applies to all ports, links and devices.
1116 If only DEVICE is omitted, the parameter applies to
1117 the port and all links and devices behind it. DEVICE
1118 number of 0 either selects the first device or the
1119 first fan-out link behind PMP device. It does not
1120 select the host link. DEVICE number of 15 selects the
1121 host link and device attached to it.
1123 The VAL specifies the configuration to force. As long
1124 as there's no ambiguity shortcut notation is allowed.
1125 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1126 The following configurations can be forced.
1128 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1129 Any ID with matching PORT is used.
1131 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1133 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1134 udma[/][16,25,33,44,66,100,133] notation is also
1137 * [no]ncq: Turn on or off NCQ.
1139 * nohrst, nosrst, norst: suppress hard, soft
1142 If there are multiple matching configurations changing
1143 the same attribute, the last one is used.
1145 lmb=debug [KNL] Enable lmb debug messages.
1147 load_ramdisk= [RAM] List of ramdisks to load from floppy
1148 See Documentation/blockdev/ramdisk.txt.
1150 lockd.nlm_grace_period=P [NFS] Assign grace period.
1153 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1156 lockd.nlm_timeout=T [NFS] Assign timeout value.
1159 lockd.nlm_udpport=M [NFS] Assign UDP port.
1162 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1165 loglevel= All Kernel Messages with a loglevel smaller than the
1166 console loglevel will be printed to the console. It can
1167 also be changed with klogd or other programs. The
1168 loglevels are defined as follows:
1170 0 (KERN_EMERG) system is unusable
1171 1 (KERN_ALERT) action must be taken immediately
1172 2 (KERN_CRIT) critical conditions
1173 3 (KERN_ERR) error conditions
1174 4 (KERN_WARNING) warning conditions
1175 5 (KERN_NOTICE) normal but significant condition
1176 6 (KERN_INFO) informational
1177 7 (KERN_DEBUG) debug-level messages
1179 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1180 Format: { n | nk | nM }
1181 n must be a power of two. The default size
1182 is set in the kernel config file.
1184 logo.nologo [FB] Disables display of the built-in Linux logo.
1185 This may be used to provide more screen space for
1186 kernel log messages and is useful when debugging
1187 kernel boot problems.
1189 lp=0 [LP] Specify parallel ports to use, e.g,
1190 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1191 lp=reset first parallel port). 'lp=0' disables the
1192 lp=auto printer driver. 'lp=reset' (which can be
1193 specified in addition to the ports) causes
1194 attached printers to be reset. Using
1195 lp=port1,port2,... specifies the parallel ports
1196 to associate lp devices with, starting with
1197 lp0. A port specification may be 'none' to skip
1198 that lp device, or a parport name such as
1199 'parport0'. Specifying 'lp=auto' instead of a
1200 port specification list means that device IDs
1201 from each port should be examined, to see if
1202 an IEEE 1284-compliant printer is attached; if
1203 so, the driver will manage that printer.
1204 See also header of drivers/char/lp.c.
1207 Sets loops_per_jiffy to given constant, thus avoiding
1208 time-consuming boot-time autodetection (up to 250 ms per
1209 CPU). 0 enables autodetection (default). To determine
1210 the correct value for your kernel, boot with normal
1211 autodetection and see what value is printed. Note that
1212 on SMP systems the preset will be applied to all CPUs,
1213 which is likely to cause problems if your CPUs need
1214 significantly divergent settings. An incorrect value
1215 will cause delays in the kernel to be wrong, leading to
1216 unpredictable I/O errors and other breakage. Although
1217 unlikely, in the extreme case this might damage your
1221 Format: <io>,<irq>,<dma>
1223 mac5380= [HW,SCSI] Format:
1224 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1226 machvec= [IA64] Force the use of a particular machine-vector
1227 (machvec) in a generic kernel.
1228 Example: machvec=hpzx1_swiotlb
1230 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1231 than or equal to this physical address is ignored.
1233 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1234 should make use of. maxcpus=n : n >= 0 limits the
1235 kernel to using 'n' processors. n=0 is a special case,
1236 it is equivalent to "nosmp", which also disables
1239 max_loop= [LOOP] Maximum number of loopback devices that can
1243 max_luns= [SCSI] Maximum number of LUNs to probe.
1244 Should be between 1 and 2^32-1.
1247 [SCSI] Maximum number of LUNs received.
1248 Should be between 1 and 16384.
1252 mce [X86-32] Machine Check Exception
1254 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1256 md= [HW] RAID subsystems devices and level
1257 See Documentation/md.txt.
1260 Format: <first>,<last>
1261 Specifies range of consoles to be captured by the MDA.
1263 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1264 Amount of memory to be used when the kernel is not able
1265 to see the whole system memory or for test.
1266 [X86-32] Use together with memmap= to avoid physical
1267 address space collisions. Without memmap= PCI devices
1268 could be placed at addresses belonging to unused RAM.
1270 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1274 [KNL,SH] Allow user to override the default size for
1275 per-device physically contiguous DMA buffers.
1277 memmap=exactmap [KNL,X86] Enable setting of an exact
1278 E820 memory map, as specified by the user.
1279 Such memmap=exactmap lines can be constructed based on
1280 BIOS output or other requirements. See the memmap=nn@ss
1283 memmap=nn[KMG]@ss[KMG]
1284 [KNL] Force usage of a specific region of memory
1285 Region of memory to be used, from ss to ss+nn.
1287 memmap=nn[KMG]#ss[KMG]
1288 [KNL,ACPI] Mark specific memory as ACPI data.
1289 Region of memory to be used, from ss to ss+nn.
1291 memmap=nn[KMG]$ss[KMG]
1292 [KNL,ACPI] Mark specific memory as reserved.
1293 Region of memory to be used, from ss to ss+nn.
1294 Example: Exclude memory from 0x18690000-0x1869ffff
1295 memmap=64K$0x18690000
1297 memmap=0x10000$0x18690000
1299 memory_corruption_check=0/1 [X86]
1300 Some BIOSes seem to corrupt the first 64k of
1301 memory when doing things like suspend/resume.
1302 Setting this option will scan the memory
1303 looking for corruption. Enabling this will
1304 both detect corruption and prevent the kernel
1305 from using the memory being corrupted.
1306 However, its intended as a diagnostic tool; if
1307 repeatable BIOS-originated corruption always
1308 affects the same memory, you can use memmap=
1309 to prevent the kernel from using that memory.
1311 memory_corruption_check_size=size [X86]
1312 By default it checks for corruption in the low
1313 64k, making this memory unavailable for normal
1314 use. Use this parameter to scan for
1315 corruption in more or less memory.
1317 memory_corruption_check_period=seconds [X86]
1318 By default it checks for corruption every 60
1319 seconds. Use this parameter to check at some
1320 other rate. 0 disables periodic checking.
1322 memtest= [KNL,X86] Enable memtest
1324 default : 0 <disable>
1325 Specifies the number of memtest passes to be
1326 performed. Each pass selects another test
1327 pattern from a given set of patterns. Memtest
1328 fills the memory with this pattern, validates
1329 memory contents and reserves bad memory
1330 regions that are detected.
1332 meye.*= [HW] Set MotionEye Camera parameters
1333 See Documentation/video4linux/meye.txt.
1335 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1336 Multi-Function General Purpose Timers on AMD Geode
1339 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1340 the BIOS has incorrectly applied a workaround. TinyBIOS
1341 version 0.98 is known to be affected, 0.99 fixes the
1342 problem by letting the user disable the workaround.
1346 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1347 physical address is ignored.
1350 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1351 parameter allows control of the logging verbosity for
1352 the additional memory initialisation checks. A value
1353 of 0 disables mminit logging and a level of 4 will
1354 log everything. Information is printed at KERN_DEBUG
1355 so loglevel=8 may also need to be specified.
1358 [MOUSE] Maximum time between finger touching and
1359 leaving touchpad surface for touch to be considered
1360 a tap and be reported as a left button click (for
1361 touchpads working in absolute mode only).
1363 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1364 reporting absolute coordinates, such as tablets
1365 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1366 reporting absolute coordinates, such as tablets
1368 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1369 is similar to kernelcore except it specifies the
1370 amount of memory used for migratable allocations.
1371 If both kernelcore and movablecore is specified,
1372 then kernelcore will be at *least* the specified
1373 value but may be more. If movablecore on its own
1374 is specified, the administrator must be careful
1375 that the amount of memory usable for all allocations
1381 MTD_Partition= [MTD]
1382 Format: <name>,<region-number>,<size>,<offset>
1384 MTD_Region= [MTD] Format:
1385 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1388 See drivers/mtd/cmdlinepart.c.
1391 ARM/S3C2412 JIVE boot control
1393 See arch/arm/mach-s3c2412/mach-jive.c
1395 mtouchusb.raw_coordinates=
1396 [HW] Make the MicroTouch USB driver use raw coordinates
1397 ('y', default) or cooked coordinates ('n')
1399 mtrr_chunk_size=nn[KMG] [X86]
1400 used for mtrr cleanup. It is largest continous chunk
1401 that could hold holes aka. UC entries.
1403 mtrr_gran_size=nn[KMG] [X86]
1404 Used for mtrr cleanup. It is granularity of mtrr block.
1406 Large value could prevent small alignment from
1409 mtrr_spare_reg_nr=n [X86]
1411 Range: 0,7 : spare reg number
1413 Used for mtrr cleanup. It is spare mtrr entries number.
1414 Set to 2 or more if your graphical card needs more.
1416 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1419 See header of drivers/scsi/NCR_D700.c.
1423 ncr53c400= [HW,SCSI]
1425 ncr53c400a= [HW,SCSI]
1427 ncr53c406a= [HW,SCSI]
1429 ncr53c8xx= [HW,SCSI]
1431 netdev= [NET] Network devices parameters
1432 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1433 Note that mem_start is often overloaded to mean
1434 something different and driver-specific.
1435 This usage is only documented in each driver source
1439 [NETFILTER] Enable connection tracking flow accounting
1440 0 to disable accounting
1441 1 to enable accounting
1442 Default value depends on CONFIG_NF_CT_ACCT that is
1443 going to be removed in 2.6.29.
1446 See Documentation/filesystems/nfsroot.txt.
1448 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1449 See Documentation/filesystems/nfsroot.txt.
1451 nfs.callback_tcpport=
1452 [NFS] set the TCP port on which the NFSv4 callback
1453 channel should listen.
1455 nfs.idmap_cache_timeout=
1456 [NFS] set the maximum lifetime for idmapper cache
1460 [NFS] enable 64-bit inode numbers.
1461 If zero, the NFS client will fake up a 32-bit inode
1462 number for the readdir() and stat() syscalls instead
1463 of returning the full 64-bit number.
1464 The default is to return 64-bit inode numbers.
1466 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1467 when a NMI is triggered.
1468 Format: [state][,regs][,debounce][,die]
1470 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1471 Format: [panic,][num]
1473 0 - turn nmi_watchdog off
1474 1 - use the IO-APIC timer for the NMI watchdog
1475 2 - use the local APIC for the NMI watchdog using
1476 a performance counter. Note: This will use one
1477 performance counter and the local APIC's performance
1479 When panic is specified, panic when an NMI watchdog
1481 This is useful when you use a panic=... timeout and
1482 need the box quickly up again.
1483 Instead of 1 and 2 it is possible to use the following
1484 symbolic names: lapic and ioapic
1485 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1487 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1488 emulation library even if a 387 maths coprocessor
1492 [HW] Never suspend the console
1493 Disable suspending of consoles during suspend and
1494 hibernate operations. Once disabled, debugging
1495 messages can reach various consoles while the rest
1496 of the system is being put to sleep (ie, while
1497 debugging driver suspend/resume hooks). This may
1498 not work reliably with all consoles, but is known
1499 to work with serial and VGA consoles.
1501 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1502 caches in the slab allocator. Saves per-node memory,
1503 but will impact performance.
1507 noapic [SMP,APIC] Tells the kernel to not make use of any
1508 IOAPICs that may be present in the system.
1510 nobats [PPC] Do not use BATs for mapping kernel lowmem
1511 on "Classic" PPC cores.
1515 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1517 nodelayacct [KNL] Disable per-task delay accounting
1519 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1521 nodsp [SH] Disable hardware DSP at boot time.
1523 noefi [X86] Disable EFI runtime services support.
1528 On X86-32 available only on PAE configured kernels.
1529 noexec=on: enable non-executable mappings (default)
1530 noexec=off: disable non-executable mappings
1533 This affects only 32-bit executables.
1534 noexec32=on: enable non-executable mappings (default)
1535 read doesn't imply executable mappings
1536 noexec32=off: disable non-executable mappings
1537 read implies executable mappings
1539 nofpu [SH] Disable hardware FPU at boot time.
1541 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1542 register save and restore. The kernel will only save
1543 legacy floating-point registers on task switch.
1545 noxsave [BUGS=X86] Disables x86 extended register state save
1546 and restore using xsave. The kernel will fallback to
1547 enabling legacy floating-point and sse state.
1549 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1550 wfi(ARM) instruction doesn't work correctly and not to
1551 use it. This is also useful when using JTAG debugger.
1553 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1554 instruction doesn't work correctly and not to
1557 no_file_caps Tells the kernel not to honor file capabilities. The
1558 only way then for a file to be executed with privilege
1559 is to be setuid root or executed by root.
1561 nohalt [IA-64] Tells the kernel not to use the power saving
1562 function PAL_HALT_LIGHT when idle. This increases
1563 power-consumption. On the positive side, it reduces
1564 interrupt wake-up latency, which may improve performance
1565 in certain environments such as networked servers or
1568 nohz= [KNL] Boottime enable/disable dynamic ticks
1569 Valid arguments: on, off
1572 noiotrap [SH] Disables trapped I/O port accesses.
1574 noirqdebug [X86-32] Disables the code which attempts to detect and
1575 disable unhandled interrupt sources.
1577 no_timer_check [X86,APIC] Disables the code which tests for
1578 broken timer IRQ sources.
1580 noisapnp [ISAPNP] Disables ISA PnP code.
1582 noinitrd [RAM] Tells the kernel not to load any configured
1587 nojitter [IA64] Disables jitter checking for ITC timers.
1589 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1591 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1593 noltlbs [PPC] Do not use large page/tlb entries for kernel
1594 lowmem mapping on PPC40x.
1596 nomca [IA-64] Disable machine check abort handling
1598 nomce [X86-32] Machine Check Exception
1600 nomfgpt [X86-32] Disable Multi-Function General Purpose
1601 Timer usage (for AMD Geode machines).
1603 norandmaps Don't use address space randomization. Equivalent to
1604 echo 0 > /proc/sys/kernel/randomize_va_space
1606 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1608 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1609 with UP alternatives
1611 noresidual [PPC] Don't use residual data on PReP machines.
1613 noresume [SWSUSP] Disables resume and restores original swap
1616 no-scroll [VGA] Disables scrollback.
1617 This is required for the Braillex ib80-piezo Braille
1618 reader made by F.H. Papenmeier (Germany).
1622 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1624 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1625 and disable the IO APIC. legacy for "maxcpus=0".
1627 nosoftlockup [KNL] Disable the soft-lockup detector.
1629 noswapaccount [KNL] Disable accounting of swap in memory resource
1630 controller. (See Documentation/cgroups/memory.txt)
1632 nosync [HW,M68K] Disables sync negotiation for all devices.
1634 notsc [BUGS=X86-32] Disable Time Stamp Counter
1636 nousb [USB] Disable the USB subsystem
1640 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1642 nptcg= [IA64] Override max number of concurrent global TLB
1643 purges which is reported from either PAL_VM_SUMMARY or
1646 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1648 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1649 one of ['zone', 'node', 'default'] can be specified
1650 This can be set from sysctl after boot.
1651 See Documentation/sysctl/vm.txt for details.
1653 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1654 See Documentation/debugging-via-ohci1394.txt for more
1657 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1658 Rather than timing out after 20 ms if an EC
1659 command is not properly ACKed, override the length
1660 of the timeout. We have interrupts disabled while
1661 waiting for the ACK, so if this is set too high
1662 interrupts *may* be lost!
1667 oprofile.timer= [HW]
1668 Use timer interrupt instead of performance counters
1670 osst= [HW,SCSI] SCSI Tape Driver
1671 Format: <buffer_size>,<write_threshold>
1672 See also Documentation/scsi/st.txt.
1674 panic= [KNL] Kernel behaviour on panic
1677 parkbd.port= [HW] Parallel port number the keyboard adapter is
1678 connected to, default is 0.
1680 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1681 0 for XT, 1 for AT (default is AT).
1684 parport= [HW,PPT] Specify parallel ports. 0 disables.
1685 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1686 Use 'auto' to force the driver to use any
1687 IRQ/DMA settings detected (the default is to
1688 ignore detected IRQ/DMA settings because of
1689 possible conflicts). You can specify the base
1690 address, IRQ, and DMA settings; IRQ and DMA
1691 should be numbers, or 'auto' (for using detected
1692 settings on that particular port), or 'nofifo'
1693 (to avoid using a FIFO even if it is detected).
1694 Parallel ports are assigned in the order they
1695 are specified on the command line, starting
1698 parport_init_mode= [HW,PPT]
1699 Configure VIA parallel port to operate in
1700 a specific mode. This is necessary on Pegasos
1701 computer where firmware has no options for setting
1702 up parallel port mode and sets it to spp.
1703 Currently this function knows 686a and 8231 chips.
1704 Format: [spp|ps2|epp|ecp|ecpepp]
1706 pas2= [HW,OSS] Format:
1707 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1710 See header of drivers/scsi/pas16.c.
1713 Halt all CPUs after the first oops has been printed for
1714 the specified number of seconds. This is to be used if
1715 your oopses keep scrolling off the screen.
1720 See header of drivers/block/paride/pcd.c.
1721 See also Documentation/blockdev/paride.txt.
1723 pci=option[,option...] [PCI] various PCI subsystem options:
1724 earlydump [X86] dump PCI config space before the kernel
1726 off [X86] don't probe for the PCI bus
1727 bios [X86-32] force use of PCI BIOS, don't access
1728 the hardware directly. Use this if your machine
1729 has a non-standard PCI host bridge.
1730 nobios [X86-32] disallow use of PCI BIOS, only direct
1731 hardware access methods are allowed. Use this
1732 if you experience crashes upon bootup and you
1733 suspect they are caused by the BIOS.
1734 conf1 [X86] Force use of PCI Configuration
1736 conf2 [X86] Force use of PCI Configuration
1738 noaer [PCIE] If the PCIEAER kernel config parameter is
1739 enabled, this kernel boot option can be used to
1740 disable the use of PCIE advanced error reporting.
1741 nodomains [PCI] Disable support for multiple PCI
1742 root domains (aka PCI segments, in ACPI-speak).
1743 nommconf [X86] Disable use of MMCONFIG for PCI
1745 nomsi [MSI] If the PCI_MSI kernel config parameter is
1746 enabled, this kernel boot option can be used to
1747 disable the use of MSI interrupts system-wide.
1748 noioapicquirk [APIC] Disable all boot interrupt quirks.
1749 Safety option to keep boot IRQs enabled. This
1750 should never be necessary.
1751 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1752 primary IO-APIC for bridges that cannot disable
1753 boot IRQs. This fixes a source of spurious IRQs
1754 when the system masks IRQs.
1755 noioapicreroute [APIC] Disable workaround that uses the
1756 boot IRQ equivalent of an IRQ that connects to
1757 a chipset where boot IRQs cannot be disabled.
1758 The opposite of ioapicreroute.
1759 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1760 routing table. These calls are known to be buggy
1761 on several machines and they hang the machine
1762 when used, but on other computers it's the only
1763 way to get the interrupt routing table. Try
1764 this option if the kernel is unable to allocate
1765 IRQs or discover secondary PCI buses on your
1767 rom [X86] Assign address space to expansion ROMs.
1768 Use with caution as certain devices share
1769 address decoders between ROMs and other
1771 norom [X86] Do not assign address space to
1772 expansion ROMs that do not already have
1773 BIOS assigned address ranges.
1774 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1775 assigned automatically to PCI devices. You can
1776 make the kernel exclude IRQs of your ISA cards
1778 pirqaddr=0xAAAAA [X86] Specify the physical address
1779 of the PIRQ table (normally generated
1780 by the BIOS) if it is outside the
1781 F0000h-100000h range.
1782 lastbus=N [X86] Scan all buses thru bus #N. Can be
1783 useful if the kernel is unable to find your
1784 secondary buses and you want to tell it
1785 explicitly which ones they are.
1786 assign-busses [X86] Always assign all PCI bus
1787 numbers ourselves, overriding
1788 whatever the firmware may have done.
1789 usepirqmask [X86] Honor the possible IRQ mask stored
1790 in the BIOS $PIR table. This is needed on
1791 some systems with broken BIOSes, notably
1792 some HP Pavilion N5400 and Omnibook XE3
1793 notebooks. This will have no effect if ACPI
1794 IRQ routing is enabled.
1795 noacpi [X86] Do not use ACPI for IRQ routing
1796 or for PCI scanning.
1797 use_crs [X86] Use _CRS for PCI resource
1799 routeirq Do IRQ routing for all PCI devices.
1800 This is normally done in pci_enable_device(),
1801 so this option is a temporary workaround
1802 for broken drivers that don't call it.
1803 skip_isa_align [X86] do not align io start addr, so can
1804 handle more pci cards
1805 firmware [ARM] Do not re-enumerate the bus but instead
1806 just use the configuration from the
1807 bootloader. This is currently used on
1808 IXP2000 systems where the bus has to be
1809 configured a certain way for adjunct CPUs.
1810 noearly [X86] Don't do any early type 1 scanning.
1811 This might help on some broken boards which
1812 machine check when some devices' config space
1813 is read. But various workarounds are disabled
1814 and some IOMMU drivers will not work.
1815 bfsort Sort PCI devices into breadth-first order.
1816 This sorting is done to get a device
1817 order compatible with older (<= 2.4) kernels.
1818 nobfsort Don't sort PCI devices into breadth-first order.
1819 cbiosize=nn[KMG] The fixed amount of bus space which is
1820 reserved for the CardBus bridge's IO window.
1821 The default value is 256 bytes.
1822 cbmemsize=nn[KMG] The fixed amount of bus space which is
1823 reserved for the CardBus bridge's memory
1824 window. The default value is 64 megabytes.
1827 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1828 Specifies alignment and device to reassign
1829 aligned memory resources.
1830 If <order of align> is not specified,
1831 PAGE_SIZE is used as alignment.
1832 PCI-PCI bridge can be specified, if resource
1833 windows need to be expanded.
1835 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1838 force Enable ASPM even on devices that claim not to support it.
1839 WARNING: Forcing ASPM on may cause system lockups.
1841 pcmv= [HW,PCMCIA] BadgePAD 4
1844 See Documentation/blockdev/paride.txt.
1846 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1849 See arch/parisc/kernel/pdc_chassis.c
1852 See Documentation/blockdev/paride.txt.
1855 See Documentation/blockdev/paride.txt.
1857 pirq= [SMP,APIC] Manual mp-table setup
1858 See Documentation/x86/i386/IO-APIC.txt.
1860 plip= [PPT,NET] Parallel port network link
1861 Format: { parport<nr> | timid | 0 }
1862 See also Documentation/parport.txt.
1864 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1865 Override pmtimer IOPort with a hex value.
1869 Enable PNP debug messages. This depends on the
1870 CONFIG_PNP_DEBUG_MESSAGES option.
1876 { on | off | curr | res | no-curr | no-res }
1879 [ISAPNP] Exclude IRQs for the autoconfiguration
1882 [ISAPNP] Exclude DMAs for the autoconfiguration
1884 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1885 Ranges are in pairs (I/O port base and size).
1888 [ISAPNP] Exclude memory regions for the
1890 Ranges are in pairs (memory base and size).
1892 ports= [IP_VS_FTP] IPVS ftp helper module
1894 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1896 Format: <port>,<port>....
1898 print-fatal-signals=
1899 [KNL] debug: print fatal signals
1900 print-fatal-signals=1: print segfault info to
1904 printk.time= Show timing data prefixed to each printk message line
1905 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1907 processor.max_cstate= [HW,ACPI]
1908 Limit processor to maximum C-state
1909 max_cstate=9 overrides any DMI blacklist limit.
1911 processor.nocst [HW,ACPI]
1912 Ignore the _CST method to determine C-states,
1913 instead using the legacy FADT method
1915 profile= [KNL] Enable kernel profiling via /proc/profile
1916 Format: [schedule,]<number>
1917 Param: "schedule" - profile schedule points.
1918 Param: <number> - step/bucket size as a power of 2 for
1919 statistical time based profiling.
1920 Param: "sleep" - profile D-state sleeping (millisecs).
1921 Requires CONFIG_SCHEDSTATS
1922 Param: "kvm" - profile VM exits.
1924 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1926 See Documentation/blockdev/ramdisk.txt.
1928 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1929 probe for; one of (bare|imps|exps|lifebook|any).
1930 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1932 psmouse.resetafter= [HW,MOUSE]
1933 Try to reset the device after so many bad packets
1936 [HW,MOUSE] Set desired mouse resolution, in dpi.
1937 psmouse.smartscroll=
1938 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1939 0 = disabled, 1 = enabled (default).
1941 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1943 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1946 See Documentation/blockdev/paride.txt.
1949 [KNL] Number of legacy pty's. Overwrites compiled-in
1952 quiet [KNL] Disable most log messages
1957 See Documentation/md.txt.
1959 ramdisk_blocksize= [RAM]
1960 See Documentation/blockdev/ramdisk.txt.
1962 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1963 See Documentation/blockdev/ramdisk.txt.
1965 rcupdate.blimit= [KNL,BOOT]
1966 Set maximum number of finished RCU callbacks to process
1969 rcupdate.qhimark= [KNL,BOOT]
1970 Set threshold of queued
1971 RCU callbacks over which batch limiting is disabled.
1973 rcupdate.qlowmark= [KNL,BOOT]
1974 Set threshold of queued RCU callbacks below which
1975 batch limiting is re-enabled.
1979 Run specified binary instead of /init from the ramdisk,
1980 used for early userspace startup. See initrd.
1982 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
1983 Format: <reboot_mode>[,<reboot_mode2>[,...]]
1984 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
1987 [KNL, SMP] Set scheduler's default relax_domain_level.
1988 See Documentation/cgroups/cpusets.txt.
1990 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
1992 reservetop= [X86-32]
1994 Reserves a hole at the top of the kernel virtual
1997 reset_devices [KNL] Force drivers to reset the underlying device
1998 during initialization.
2001 Specify the partition device for software suspend
2003 resume_offset= [SWSUSP]
2004 Specify the offset from the beginning of the partition
2005 given by "resume=" at which the swap header is located,
2006 in <PAGE_SIZE> units (needed only for swap files).
2007 See Documentation/power/swsusp-and-swap-files.txt
2009 retain_initrd [RAM] Keep initrd memory after extraction
2011 rhash_entries= [KNL,NET]
2012 Set number of hash buckets for route cache
2014 riscom8= [HW,SERIAL]
2015 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2017 ro [KNL] Mount root device read-only on boot
2019 root= [KNL] Root filesystem
2021 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2022 mount the root filesystem
2024 rootflags= [KNL] Set root filesystem mount option string
2026 rootfstype= [KNL] Set root filesystem type
2028 rootwait [KNL] Wait (indefinitely) for root device to show up.
2029 Useful for devices that are detected asynchronously
2030 (e.g. USB and MMC devices).
2032 root_plug.vendor_id=
2033 [ROOTPLUG] Override the default vendor ID
2035 root_plug.product_id=
2036 [ROOTPLUG] Override the default product ID
2039 [ROOTPLUG] Enable debugging output
2041 rw [KNL] Mount root device read-write on boot
2043 S [KNL] Run init in single mode
2046 See drivers/net/irda/sa1100_ir.c.
2048 sbni= [NET] Granch SBNI12 leased line adapter
2050 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2051 Format: <io>[,<timeout>[,<isapnp>]]
2053 scsi_debug_*= [SCSI]
2054 See drivers/scsi/scsi_debug.c.
2056 scsi_default_dev_flags=
2057 [SCSI] SCSI default device flags
2060 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2061 Format: <vendor>:<model>:<flags>
2062 (flags are integer value)
2064 scsi_logging_level= [SCSI] a bit mask of logging levels
2065 See drivers/scsi/scsi_logging.h for bits. Also
2066 settable via sysctl at dev.scsi.logging_level
2067 (/proc/sys/dev/scsi/logging_level).
2068 There is also a nice 'scsi_logging_level' script in the
2069 S390-tools package, available for download at
2070 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2072 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2073 discovered. async scans them in kernel threads,
2074 allowing boot to proceed. none ignores them, expecting
2075 user space to do the scan.
2077 security= [SECURITY] Choose a security module to enable at boot.
2078 If this boot parameter is not specified, only the first
2079 security module asking for security registration will be
2080 loaded. An invalid security module name will be treated
2081 as if no module has been chosen.
2083 selinux= [SELINUX] Disable or enable SELinux at boot time.
2084 Format: { "0" | "1" }
2085 See security/selinux/Kconfig help text.
2088 Default value is set via kernel config option.
2089 If enabled at boot time, /selinux/disable can be used
2090 later to disable prior to initial policy load.
2092 serialnumber [BUGS=X86-32]
2095 Maximal number of shapers.
2097 show_msr= [x86] show boot-time MSR settings
2098 Format: { <integer> }
2099 Show boot-time (BIOS-initialized) MSR settings.
2100 The parameter means the number of CPUs to show,
2101 for example 1 means boot CPU only.
2104 See header of drivers/scsi/sim710.c.
2111 slub_debug[=options[,slabs]] [MM, SLUB]
2112 Enabling slub_debug allows one to determine the
2113 culprit if slab objects become corrupted. Enabling
2114 slub_debug can create guard zones around objects and
2115 may poison objects when not in use. Also tracks the
2116 last alloc / free. For more information see
2117 Documentation/vm/slub.txt.
2119 slub_max_order= [MM, SLUB]
2120 Determines the maximum allowed order for slabs.
2121 A high setting may cause OOMs due to memory
2122 fragmentation. For more information see
2123 Documentation/vm/slub.txt.
2125 slub_min_objects= [MM, SLUB]
2126 The minimum number of objects per slab. SLUB will
2127 increase the slab order up to slub_max_order to
2128 generate a sufficiently large slab able to contain
2129 the number of objects indicated. The higher the number
2130 of objects the smaller the overhead of tracking slabs
2131 and the less frequently locks need to be acquired.
2132 For more information see Documentation/vm/slub.txt.
2134 slub_min_order= [MM, SLUB]
2135 Determines the mininum page order for slabs. Must be
2136 lower than slub_max_order.
2137 For more information see Documentation/vm/slub.txt.
2139 slub_nomerge [MM, SLUB]
2140 Disable merging of slabs with similar size. May be
2141 necessary if there is some reason to distinguish
2142 allocs to different slabs. Debug options disable
2143 merging on their own.
2144 For more information see Documentation/vm/slub.txt.
2147 Format: <io1>[,<io2>[,...,<io8>]]
2149 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2150 attempt to substitute SMP alternatives once at boot.
2152 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2153 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2154 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2155 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2156 smsc-ircc2.ircc_irq= [HW] IRQ line
2157 smsc-ircc2.ircc_dma= [HW] DMA channel
2158 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2159 0: Toshiba Satellite 1800 (GP data pin select)
2160 1: Fast pin select (default)
2163 snd-ad1816a= [HW,ALSA]
2165 snd-ad1848= [HW,ALSA]
2167 snd-ali5451= [HW,ALSA]
2169 snd-als100= [HW,ALSA]
2171 snd-als4000= [HW,ALSA]
2173 snd-azt2320= [HW,ALSA]
2175 snd-cmi8330= [HW,ALSA]
2177 snd-cmipci= [HW,ALSA]
2179 snd-cs4231= [HW,ALSA]
2181 snd-cs4232= [HW,ALSA]
2183 snd-cs4236= [HW,ALSA]
2185 snd-cs4281= [HW,ALSA]
2187 snd-cs46xx= [HW,ALSA]
2189 snd-dt019x= [HW,ALSA]
2191 snd-dummy= [HW,ALSA]
2193 snd-emu10k1= [HW,ALSA]
2195 snd-ens1370= [HW,ALSA]
2197 snd-ens1371= [HW,ALSA]
2199 snd-es968= [HW,ALSA]
2201 snd-es1688= [HW,ALSA]
2203 snd-es18xx= [HW,ALSA]
2205 snd-es1938= [HW,ALSA]
2207 snd-es1968= [HW,ALSA]
2209 snd-fm801= [HW,ALSA]
2211 snd-gusclassic= [HW,ALSA]
2213 snd-gusextreme= [HW,ALSA]
2215 snd-gusmax= [HW,ALSA]
2219 snd-ice1712= [HW,ALSA]
2221 snd-intel8x0= [HW,ALSA]
2223 snd-interwave= [HW,ALSA]
2228 snd-korg1212= [HW,ALSA]
2230 snd-maestro3= [HW,ALSA]
2232 snd-mpu401= [HW,ALSA]
2234 snd-mtpav= [HW,ALSA]
2236 snd-nm256= [HW,ALSA]
2238 snd-opl3sa2= [HW,ALSA]
2246 snd-opti93x= [HW,ALSA]
2250 snd-rme32= [HW,ALSA]
2252 snd-rme96= [HW,ALSA]
2254 snd-rme9652= [HW,ALSA]
2260 snd-sbawe= [HW,ALSA]
2262 snd-serial= [HW,ALSA]
2264 snd-sgalaxy= [HW,ALSA]
2266 snd-sonicvibes= [HW,ALSA]
2271 snd-sun-cs4231= [HW,ALSA]
2273 snd-trident= [HW,ALSA]
2275 snd-usb-audio= [HW,ALSA,USB]
2277 snd-via82xx= [HW,ALSA]
2279 snd-virmidi= [HW,ALSA]
2281 snd-wavefront= [HW,ALSA]
2283 snd-ymfpci= [HW,ALSA]
2286 [KNL] Should the soft-lockup detector generate panics.
2288 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2289 See Documentation/sonypi.txt
2291 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2292 See Documentation/serial/specialix.txt.
2294 spia_io_base= [HW,MTD]
2300 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2302 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2303 See Documentation/scsi/st.txt.
2306 Enabled the stack tracer on boot up.
2310 Set the STI (builtin display/keyboard on the HP-PARISC
2311 machines) console (graphic card) which should be used
2312 as the initial boot-console.
2313 See also comment in drivers/video/console/sticore.c.
2316 See comment in drivers/video/console/sticore.c.
2319 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2323 Control how the NFS server code allocates CPUs to
2324 service thread pools. Depending on how many NICs
2325 you have and where their interrupts are bound, this
2326 option will affect which CPUs will do NFS serving.
2327 Note: this parameter cannot be changed while the
2328 NFS server is running.
2330 auto the server chooses an appropriate mode
2331 automatically using heuristics
2332 global a single global pool contains all CPUs
2333 percpu one pool for each CPU
2334 pernode one pool for each NUMA node (equivalent
2335 to global on non-NUMA machines)
2337 swiotlb= [IA-64] Number of I/O TLB slabs
2341 sym53c416= [HW,SCSI]
2342 See header of drivers/scsi/sym53c416.c.
2344 sysrq_always_enabled
2346 Ignore sysrq setting - this boot parameter will
2347 neutralize any effect of /proc/sys/kernel/sysrq.
2348 Useful for debugging.
2351 See header of drivers/scsi/t128.c.
2355 test_suspend= [SUSPEND]
2356 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2357 standby suspend) as the system sleep state to briefly
2358 enter during system startup. The system is woken from
2359 this state using a wakeup-capable RTC alarm.
2361 thash_entries= [KNL,NET]
2362 Set number of hash buckets for TCP connection
2364 thermal.act= [HW,ACPI]
2365 -1: disable all active trip points in all thermal zones
2366 <degrees C>: override all lowest active trip points
2368 thermal.crt= [HW,ACPI]
2369 -1: disable all critical trip points in all thermal zones
2370 <degrees C>: override all critical trip points
2372 thermal.nocrt= [HW,ACPI]
2373 Set to disable actions on ACPI thermal zone
2374 critical and hot trip points.
2376 thermal.off= [HW,ACPI]
2377 1: disable ACPI thermal control
2379 thermal.psv= [HW,ACPI]
2380 -1: disable all passive trip points
2381 <degrees C>: override all passive trip points to this
2384 thermal.tzp= [HW,ACPI]
2385 Specify global default ACPI thermal zone polling rate
2386 <deci-seconds>: poll all this frequency
2387 0: no polling (default)
2390 See comment before function dc390_setup() in
2391 drivers/scsi/tmscsim.c.
2395 Specify if the kernel should make use of the cpu
2396 topology informations if the hardware supports these.
2397 The scheduler will make use of these informations and
2398 e.g. base its process migration decisions on it.
2403 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2405 trix= [HW,OSS] MediaTrix AudioTrix Pro
2407 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2409 tsc= Disable clocksource-must-verify flag for TSC.
2411 [x86] reliable: mark tsc clocksource as reliable, this
2412 disables clocksource verification at runtime.
2413 Used to enable high-resolution timer mode on older
2414 hardware, and in virtualized environment.
2416 turbografx.map[2|3]= [HW,JOY]
2417 TurboGraFX parallel port interface
2419 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2420 See also Documentation/input/joystick-parport.txt
2422 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2423 See header of drivers/scsi/u14-34f.c.
2432 [USB] Ignore overcurrent events (default N).
2433 Some badly-designed motherboards generate lots of
2434 bogus events, for ports that aren't wired to
2435 anything. Set this parameter to avoid log spamming.
2436 Note that genuine overcurrent events won't be
2441 Set unknown_nmi_panic=1 early on boot.
2443 usbcore.autosuspend=
2444 [USB] The autosuspend time delay (in seconds) used
2445 for newly-detected USB devices (default 2). This
2446 is the time required before an idle device will be
2447 autosuspended. Devices for which the delay is set
2448 to a negative value won't be autosuspended at all.
2450 usbcore.usbfs_snoop=
2451 [USB] Set to log all usbfs traffic (default 0 = off).
2453 usbcore.blinkenlights=
2454 [USB] Set to cycle leds on hubs (default 0 = off).
2456 usbcore.old_scheme_first=
2457 [USB] Start with the old device initialization
2458 scheme (default 0 = off).
2460 usbcore.use_both_schemes=
2461 [USB] Try the other device initialization scheme
2462 if the first one fails (default 1 = enabled).
2464 usbcore.initial_descriptor_timeout=
2465 [USB] Specifies timeout for the initial 64-byte
2466 USB_REQ_GET_DESCRIPTOR request in milliseconds
2467 (default 5000 = 5.0 seconds).
2470 [USBHID] The interval which mice are to be polled at.
2472 usb-storage.delay_use=
2473 [UMS] The delay in seconds before a new device is
2474 scanned for Logical Units (default 5).
2477 [UMS] A list of quirks entries to supplement or
2478 override the built-in unusual_devs list. List
2479 entries are separated by commas. Each entry has
2480 the form VID:PID:Flags where VID and PID are Vendor
2481 and Product ID values (4-digit hex numbers) and
2482 Flags is a set of characters, each corresponding
2483 to a common usb-storage quirk flag as follows:
2484 a = SANE_SENSE (collect more than 18 bytes
2486 c = FIX_CAPACITY (decrease the reported
2487 device capacity by one sector);
2488 h = CAPACITY_HEURISTICS (decrease the
2489 reported device capacity by one
2490 sector if the number is odd);
2491 i = IGNORE_DEVICE (don't bind to this
2493 l = NOT_LOCKABLE (don't try to lock and
2494 unlock ejectable media);
2495 m = MAX_SECTORS_64 (don't transfer more
2496 than 64 sectors = 32 KB at a time);
2497 o = CAPACITY_OK (accept the capacity
2498 reported by the device);
2499 r = IGNORE_RESIDUE (the device reports
2500 bogus residue values);
2501 s = SINGLE_LUN (the device has only one
2503 w = NO_WP_DETECT (don't test whether the
2504 medium is write-protected).
2505 Example: quirks=0419:aaf5:rl,0421:0433:rc
2508 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2509 vdso=1: enable VDSO (default)
2510 vdso=0: disable VDSO mapping
2513 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2514 vdso32=1: enable 32-bit VDSO (default)
2515 vdso32=0: disable 32-bit VDSO mapping
2518 vector=percpu: enable percpu vector domain
2520 video= [FB] Frame buffer configuration
2521 See Documentation/fb/modedb.txt.
2523 vga= [BOOT,X86-32] Select a particular video mode
2524 See Documentation/x86/boot.txt and
2525 Documentation/svga.txt.
2526 Use vga=ask for menu.
2527 This is actually a boot loader parameter; the value is
2528 passed to the kernel using a special protocol.
2530 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2531 size of <nn>. This can be used to increase the
2532 minimum size (128MB on x86). It can also be used to
2533 decrease the size and leave more room for directly
2536 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2539 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2542 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2545 vt.default_blu= [VT]
2546 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2547 Change the default blue palette of the console.
2548 This is a 16-member array composed of values
2551 vt.default_grn= [VT]
2552 Format: <green0>,<green1>,<green2>,...,<green15>
2553 Change the default green palette of the console.
2554 This is a 16-member array composed of values
2557 vt.default_red= [VT]
2558 Format: <red0>,<red1>,<red2>,...,<red15>
2559 Change the default red palette of the console.
2560 This is a 16-member array composed of values
2566 Set system-wide default UTF-8 mode for all tty's.
2567 Default is 1, i.e. UTF-8 mode is enabled for all
2568 newly opened terminals.
2570 waveartist= [HW,OSS]
2571 Format: <io>,<irq>,<dma>,<dma2>
2574 See header of drivers/scsi/wd33c93.c.
2577 See header of drivers/scsi/wd7000.c.
2580 See Documentation/watchdog/wdt.txt.
2582 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2583 default x2apic cluster mode on platforms
2586 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2587 xd_geo= See header of drivers/block/xd.c.
2589 xirc2ps_cs= [NET,PCMCIA]
2591 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2593 ______________________________________________________________________
2597 Add documentation for ALSA options.
2598 Add more DRM drivers.
projects / linux-2.6 / blob