4 The following is a consolidated list of the kernel parameters as implemented
5 (mostly) by the __setup() macro and sorted into English Dictionary order
6 (defined as ignoring all punctuation and sorting digits before letters in a
7 case insensitive manner), and with descriptions where known.
9 Module parameters for loadable modules are specified only as the
10 parameter name with optional '=' and value as appropriate, such as:
12 modprobe usbcore blinkenlights=1
14 Module parameters for modules that are built into the kernel image
15 are specified on the kernel command line with the module name plus
16 '.' plus parameter name, with '=' and value if appropriate, such as:
18 usbcore.blinkenlights=1
20 Hyphens (dashes) and underscores are equivalent in parameter names, so
21 log_buf_len=1M print-fatal-signals=1
22 can also be entered as
23 log-buf-len=1M print_fatal_signals=1
26 This document may not be entirely up to date and comprehensive. The command
27 "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
28 module. Loadable modules, after being loaded into the running kernel, also
29 reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
30 parameters may be changed at runtime by the command
31 "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
33 The parameters listed below are only valid if certain kernel build options were
34 enabled and if respective hardware is present. The text in square brackets at
35 the beginning of each description states the restrictions within which a
36 parameter is applicable:
38 ACPI ACPI support is enabled.
39 AGP AGP (Accelerated Graphics Port) is enabled.
40 ALSA ALSA sound support is enabled.
41 APIC APIC support is enabled.
42 APM Advanced Power Management support is enabled.
43 AVR32 AVR32 architecture is enabled.
44 AX25 Appropriate AX.25 support is enabled.
45 BLACKFIN Blackfin architecture is enabled.
46 DRM Direct Rendering Management support is enabled.
47 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
48 EFI EFI Partitioning (GPT) is enabled
49 EIDE EIDE/ATAPI support is enabled.
50 FB The frame buffer device is enabled.
51 HW Appropriate hardware is enabled.
52 IA-64 IA-64 architecture is enabled.
53 IMA Integrity measurement architecture is enabled.
54 IOSCHED More than one I/O scheduler is enabled.
55 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
56 ISAPNP ISA PnP code is enabled.
57 ISDN Appropriate ISDN support is enabled.
58 JOY Appropriate joystick support is enabled.
59 LIBATA Libata driver is enabled
60 LP Printer support is enabled.
61 LOOP Loopback device support is enabled.
62 M68k M68k architecture is enabled.
63 These options have more detailed description inside of
64 Documentation/m68k/kernel-options.txt.
65 MCA MCA bus support is enabled.
66 MDA MDA console support is enabled.
67 MOUSE Appropriate mouse support is enabled.
68 MSI Message Signaled Interrupts (PCI).
69 MTD MTD (Memory Technology Device) support is enabled.
70 NET Appropriate network support is enabled.
71 NUMA NUMA support is enabled.
72 GENERIC_TIME The generic timeofday code is enabled.
73 NFS Appropriate NFS support is enabled.
74 OSS OSS sound support is enabled.
75 PV_OPS A paravirtualized kernel is enabled.
76 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
77 PARISC The PA-RISC architecture is enabled.
78 PCI PCI bus support is enabled.
79 PCIE PCI Express support is enabled.
80 PCMCIA The PCMCIA subsystem is enabled.
81 PNP Plug & Play support is enabled.
82 PPC PowerPC architecture is enabled.
83 PPT Parallel port support is enabled.
84 PS2 Appropriate PS/2 support is enabled.
85 RAM RAM disk support is enabled.
86 ROOTPLUG The example Root Plug LSM is enabled.
87 S390 S390 architecture is enabled.
88 SCSI Appropriate SCSI support is enabled.
89 A lot of drivers has their options described inside of
91 SECURITY Different security models are enabled.
92 SELINUX SELinux support is enabled.
93 SERIAL Serial support is enabled.
94 SH SuperH architecture is enabled.
95 SMP The kernel is an SMP kernel.
96 SPARC Sparc architecture is enabled.
97 SWSUSP Software suspend (hibernation) is enabled.
98 SUSPEND System suspend states are enabled.
99 FTRACE Function tracing enabled.
100 TS Appropriate touchscreen support is enabled.
101 UMS USB Mass Storage support is enabled.
102 USB USB support is enabled.
103 USBHID USB Human Interface Device support is enabled.
104 V4L Video For Linux support is enabled.
105 VGA The VGA console has been enabled.
106 VT Virtual terminal support is enabled.
107 WDT Watchdog support is enabled.
108 XT IBM PC/XT MFM hard disk support is enabled.
109 X86-32 X86-32, aka i386 architecture is enabled.
110 X86-64 X86-64 architecture is enabled.
111 More X86-64 boot options can be found in
112 Documentation/x86/x86_64/boot-options.txt .
113 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
115 In addition, the following text indicates that the option:
117 BUGS= Relates to possible processor bugs on the said processor.
118 KNL Is a kernel start-up parameter.
119 BOOT Is a boot loader parameter.
121 Parameters denoted with BOOT are actually interpreted by the boot
122 loader, and have no meaning to the kernel directly.
123 Do not modify the syntax of boot loader parameters without extreme
124 need or coordination with <Documentation/x86/boot.txt>.
126 There are also arch-specific kernel-parameters not documented here.
127 See for example <Documentation/x86/x86_64/boot-options.txt>.
129 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
130 a trailing = on the name of any parameter states that that parameter will
131 be entered as an environment variable, whereas its absence indicates that
132 it will appear as a kernel argument readable via /proc/cmdline by programs
133 running once the system is up.
135 The number of kernel parameters is not limited, but the length of the
136 complete command line (parameters including spaces etc.) is limited to
137 a fixed number of characters. This limit depends on the architecture
138 and is between 256 and 4096 characters. It is defined in the file
139 ./include/asm/setup.h as COMMAND_LINE_SIZE.
143 Advanced Configuration and Power Interface
144 Format: { force | off | ht | strict | noirq | rsdt }
145 force -- enable ACPI if default was off
146 off -- disable ACPI if default was on
147 noirq -- do not use ACPI for IRQ routing
148 ht -- run only enough ACPI to enable Hyper Threading
149 strict -- Be less tolerant of platforms that are not
150 strictly ACPI specification compliant.
151 rsdt -- prefer RSDT over (default) XSDT
153 See also Documentation/power/pm.txt, pci=noacpi
155 acpi_apic_instance= [ACPI, IOAPIC]
157 2: use 2nd APIC table, if available
158 1,0: use 1st APIC table
161 acpi_backlight= [HW,ACPI]
162 acpi_backlight=vendor
164 If set to vendor, prefer vendor specific driver
165 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
166 of the ACPI video.ko driver.
168 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
169 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
171 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
172 debug output. Bits in debug_layer correspond to a
173 _COMPONENT in an ACPI source file, e.g.,
174 #define _COMPONENT ACPI_PCI_COMPONENT
175 Bits in debug_level correspond to a level in
176 ACPI_DEBUG_PRINT statements, e.g.,
177 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
178 The debug_level mask defaults to "info". See
179 Documentation/acpi/debug.txt for more information about
180 debug layers and levels.
182 Enable processor driver info messages:
183 acpi.debug_layer=0x20000000
184 Enable PCI/PCI interrupt routing info messages:
185 acpi.debug_layer=0x400000
186 Enable AML "Debug" output, i.e., stores to the Debug
187 object while interpreting AML:
188 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
189 Enable all messages related to ACPI hardware:
190 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
192 Some values produce so much output that the system is
193 unusable. The "log_buf_len" parameter may be useful
194 if you need to capture more output.
196 acpi_display_output= [HW,ACPI]
197 acpi_display_output=vendor
198 acpi_display_output=video
201 acpi_irq_balance [HW,ACPI]
202 ACPI will balance active IRQs
205 acpi_irq_nobalance [HW,ACPI]
206 ACPI will not move active IRQs (default)
209 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
210 Format: <irq>,<irq>...
212 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
214 Format: <irq>,<irq>...
216 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
218 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
219 Format: To spoof as Windows 98: ="Microsoft Windows"
221 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
222 acpi_osi="string1" # add string1 -- only one string
223 acpi_osi="!string2" # remove built-in string2
224 acpi_osi= # disable all strings
227 Override the pmtimer bug detection: force the kernel
228 to assume that this machine's pmtimer latches its value
229 and always returns good values.
231 acpi.power_nocheck= [HW,ACPI]
232 Format: 1/0 enable/disable the check of power state.
233 On some bogus BIOS the _PSC object/_STA object of
234 power resource can't return the correct device power
235 state. In such case it is unneccessary to check its
236 power state again in power transition.
237 1 : disable the power state check
239 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
240 Format: { level | edge | high | low }
242 acpi_serialize [HW,ACPI] force serialization of AML methods
244 acpi_skip_timer_override [HW,ACPI]
245 Recognize and ignore IRQ0/pin2 Interrupt Override.
246 For broken nForce2 BIOS resulting in XT-PIC timer.
248 acpi_sleep= [HW,ACPI] Sleep options
249 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
250 old_ordering, s4_nonvs }
251 See Documentation/power/video.txt for information on
253 s3_beep is for debugging; it makes the PC's speaker beep
254 as soon as the kernel's real-mode entry point is called.
255 s4_nohwsig prevents ACPI hardware signature from being
256 used during resume from hibernation.
257 old_ordering causes the ACPI 1.0 ordering of the _PTS
258 control method, with respect to putting devices into
259 low power states, to be enforced (the ACPI 2.0 ordering
260 of _PTS is used by default).
261 s4_nonvs prevents the kernel from saving/restoring the
262 ACPI NVS memory during hibernation.
264 acpi_use_timer_override [HW,ACPI]
265 Use timer override. For some broken Nvidia NF5 boards
266 that require a timer override, but don't have HPET
268 acpi_enforce_resources= [ACPI]
269 { strict | lax | no }
270 Check for resource conflicts between native drivers
271 and ACPI OperationRegions (SystemIO and SystemMemory
272 only). IO ports and memory declared in ACPI might be
273 used by the ACPI subsystem in arbitrary AML code and
274 can interfere with legacy drivers.
275 strict (default): access to resources claimed by ACPI
276 is denied; legacy drivers trying to access reserved
277 resources will fail to bind to device using them.
278 lax: access to resources claimed by ACPI is allowed;
279 legacy drivers trying to access reserved resources
280 will bind successfully but a warning message is logged.
281 no: ACPI OperationRegions are not marked as reserved,
282 no further checks are performed.
285 Format: <io>,<irq>,<dma>,<dma2>,<type>
287 add_efi_memmap [EFI; X86] Include EFI memory map in
288 kernel's map of available physical RAM.
291 See header of drivers/scsi/advansys.c.
293 advwdt= [HW,WDT] Advantech WDT
294 Format: <iostart>,<iostop>
296 aedsp16= [HW,OSS] Audio Excel DSP 16
297 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
298 See also header of sound/oss/aedsp16.c.
301 { off | try_unsupported }
302 off: disable AGP support
303 try_unsupported: try to drive unsupported chipsets
304 (may crash computer or cause data corruption)
307 See Documentation/scsi/aha152x.txt.
310 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
313 See Documentation/scsi/aic7xxx.txt.
316 See Documentation/scsi/aic79xx.txt.
318 amd_iommu= [HW,X86-84]
319 Pass parameters to the AMD IOMMU driver in the system.
321 isolate - enable device isolation (each device, as far
322 as possible, will get its own protection
324 share - put every device behind one IOMMU into the
325 same protection domain
326 fullflush - enable flushing of IO/TLB entries when
327 they are unmapped. Otherwise they are
328 flushed before they will be reused, which
331 amijoy.map= [HW,JOY] Amiga joystick support
332 Map of devices attached to JOY0DAT and JOY1DAT
334 See also Documentation/kernel/input/joystick.txt
336 analog.map= [HW,JOY] Analog joystick and gamepad support
337 Specifies type or capabilities of an analog joystick
338 connected to one of 16 gameports
339 Format: <type1>,<type2>,..<type16>
342 Power management functions (SPARCstation-4/5 + deriv.)
344 Disable APC CPU standby support. SPARCstation-Fox does
345 not play well with APC CPU idle - disable it if you have
346 APC and your system crashes randomly.
348 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
349 Change the output verbosity whilst booting
350 Format: { quiet (default) | verbose | debug }
351 Change the amount of debugging information output
352 when initialising the APIC and IO-APIC components.
354 apm= [APM] Advanced Power Management
355 See header of arch/x86/kernel/apm_32.c.
357 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
358 Format: <io>,<irq>,<nodeID>
362 atarimouse= [HW,MOUSE] Atari Mouse
364 atascsi= [HW,SCSI] Atari SCSI
366 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
367 EzKey and similar keyboards
369 atkbd.reset= [HW] Reset keyboard during initialization
371 atkbd.set= [HW] Select keyboard code set
372 Format: <int> (2 = AT (default), 3 = PS/2)
374 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
377 atkbd.softraw= [HW] Choose between synthetic and real raw mode
378 Format: <bool> (0 = real, 1 = synthetic (default))
380 atkbd.softrepeat= [HW]
381 Use software keyboard repeat
385 baycom_epp= [HW,AX25]
388 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
390 See header of drivers/net/hamradio/baycom_par.c.
392 baycom_ser_fdx= [HW,AX25]
393 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
394 Format: <io>,<irq>,<mode>[,<baud>]
395 See header of drivers/net/hamradio/baycom_ser_fdx.c.
397 baycom_ser_hdx= [HW,AX25]
398 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
399 Format: <io>,<irq>,<mode>
400 See header of drivers/net/hamradio/baycom_ser_hdx.c.
402 boot_delay= Milliseconds to delay each printk during boot.
403 Values larger than 10 seconds (10000) are changed to
407 bootmem_debug [KNL] Enable bootmem allocator debug messages.
409 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
410 bttv.radio= Most important insmod options are available as
412 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
413 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
416 See drivers/scsi/BusLogic.c, comment before function
417 BusLogic_ParseDriverOptions().
419 c101= [NET] Moxa C101 synchronous serial card
421 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
422 Sometimes CPU hardware bugs make them report the cache
423 size incorrectly. The kernel will attempt work arounds
424 to fix known problems, but for some CPUs it is not
425 possible to determine what the correct size should be.
426 This option provides an override for these situations.
429 [SECURITY] Disable capabilities. This would normally
430 be used only if an alternative security model is to be
431 configured. Potentially dangerous and should only be
432 used if you are entirely sure of the consequences.
434 ccw_timeout_log [S390]
435 See Documentation/s390/CommonIO for details.
437 cgroup_disable= [KNL] Disable a particular controller
438 Format: {name of the controller(s) to disable}
439 {Currently supported controllers - "memory"}
441 checkreqprot [SELINUX] Set initial checkreqprot flag value.
442 Format: { "0" | "1" }
443 See security/selinux/Kconfig help text.
444 0 -- check protection applied by kernel (includes
445 any implied execute protection).
446 1 -- check protection requested by application.
447 Default value is set via a kernel config option.
448 Value can be changed at runtime via
449 /selinux/checkreqprot.
452 See Documentation/s390/CommonIO for details.
454 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
456 Forces specified clocksource (if available) to be used
457 when calculating gettimeofday(). If specified
458 clocksource is not available, it defaults to PIT.
459 Format: { pit | tsc | cyclone | pmtmr }
461 clocksource= [GENERIC_TIME] Override the default clocksource
463 Override the default clocksource and use the clocksource
464 with the name specified.
465 Some clocksource names to choose from, depending on
467 [all] jiffies (this is the base, fallback clocksource)
469 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
470 pxa_timer,timer3,32k_counter,timer0_1
472 [X86-32] pit,hpet,tsc,vmi-timer;
473 scx200_hrt on Geode; cyclone on IBM x440
481 clearcpuid=BITNUM [X86]
482 Disable CPUID feature X for the kernel. See
483 arch/x86/include/asm/cpufeature.h for the valid bit
484 numbers. Note the Linux specific bits are not necessarily
485 stable over kernel options, but the vendor specific
487 Also note that user programs calling CPUID directly
488 or using the feature without checking anything
489 will still see it. This just prevents it from
490 being used by the kernel or shown in /proc/cpuinfo.
491 Also note the kernel might malfunction if you disable
494 cmo_free_hint= [PPC] Format: { yes | no }
495 Specify whether pages are marked as being inactive
496 when they are freed. This is used in CMO environments
497 to determine OS memory pressure for page stealing by
501 code_bytes [X86] How many bytes of object code to print
506 com20020= [HW,NET] ARCnet - COM20020 chipset
508 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
510 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
514 ARCnet - COM90xx chipset (memory-mapped buffers)
515 Format: <io>[,<irq>[,<memstart>]]
517 condev= [HW,S390] console device
520 console= [KNL] Output console device and options.
522 tty<n> Use the virtual console device <n>.
526 Use the specified serial port. The options are of
527 the form "bbbbpnf", where "bbbb" is the baud rate,
528 "p" is parity ("n", "o", or "e"), "n" is number of
529 bits, and "f" is flow control ("r" for RTS or
530 omit it). Default is "9600n8".
532 See Documentation/serial-console.txt for more
534 Documentation/networking/netconsole.txt for an
537 uart[8250],io,<addr>[,options]
538 uart[8250],mmio,<addr>[,options]
539 Start an early, polled-mode console on the 8250/16550
540 UART at the specified I/O port or MMIO address,
541 switching to the matching ttyS device later. The
542 options are the same as for ttyS, above.
544 If the device connected to the port is not a TTY but a braille
545 device, prepend "brl," before the device type, for instance
547 For now, only VisioBraille is supported.
549 consoleblank= [KNL] The console blank (screen saver) timeout in
550 seconds. Defaults to 10*60 = 10mins. A value of 0
551 disables the blank timer.
554 [KNL] Change the default value for
555 /proc/<pid>/coredump_filter.
556 See also Documentation/filesystems/proc.txt.
558 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
560 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
562 crashkernel=nn[KMG]@ss[KMG]
563 [KNL] Reserve a chunk of physical memory to
564 hold a kernel to switch to with kexec on panic.
566 crashkernel=range1:size1[,range2:size2,...][@offset]
567 [KNL] Same as above, but depends on the memory
568 in the running system. The syntax of range is
569 start-[end] where start and end are both
570 a memory unit (amount[KMG]). See also
571 Documentation/kdump/kdump.txt for a example.
576 cs89x0_media= [HW,NET]
577 Format: { rj45 | aui | bnc }
580 See header of drivers/s390/block/dasd_devmap.c.
582 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
583 (one device per port)
584 Format: <port#>,<type>
585 See also Documentation/input/joystick-parport.txt
587 debug [KNL] Enable kernel debugging (events log level).
590 [KNL] verbose self-tests
592 Print debugging info while doing the locking API
594 We default to 0 (no extra messages), setting it to
595 1 will print _a lot_ more information - normally
596 only useful to kernel developers.
598 debug_objects [KNL] Enable object debugging
601 [KNL] Disable object debugging
603 debugpat [X86] Enable PAT debugging
605 decnet.addr= [HW,NET]
606 Format: <area>[,<node>]
607 See also Documentation/networking/decnet.txt.
610 [same as hugepagesz=] The size of the default
611 HugeTLB page size. This is the size represented by
612 the legacy /proc/ hugepages APIs, used for SHM, and
613 default size when mounting hugetlbfs filesystems.
614 Defaults to the default architecture's huge page size
618 Set number of hash buckets for dentry cache.
621 IO parameters + enable/disable command.
623 digiepca= [HW,SERIAL]
624 See drivers/char/README.epca and
625 Documentation/serial/digiepca.txt.
627 disable_mtrr_cleanup [X86]
628 The kernel tries to adjust MTRR layout from continuous
629 to discrete, to make X server driver able to add WB
630 entry later. This parameter disables that.
632 disable_mtrr_trim [X86, Intel and AMD only]
633 By default the kernel will trim any uncacheable
634 memory out of your available memory pool based on
635 MTRR settings. This parameter disables that behavior,
636 possibly causing your machine to run very slowly.
638 disable_timer_pin_1 [X86]
639 Disable PIN 1 of APIC timer
640 Can be useful to work around chipset bugs.
642 dmasound= [HW,OSS] Sound subsystem buffers
644 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
645 this option disables the debugging code at boot.
647 dma_debug_entries=<number>
648 This option allows to tune the number of preallocated
649 entries for DMA-API debugging code. One entry is
650 required per DMA-API allocation. Use this if the
651 DMA-API debugging code disables itself because the
652 architectural default is too low.
654 dma_debug_driver=<driver_name>
655 With this option the DMA-API debugging driver
656 filter feature can be enabled at boot time. Just
657 pass the driver to filter for as the parameter.
658 The filter can be disabled or changed to another
659 driver later using sysfs.
665 dynamic_printk Enables pr_debug()/dev_dbg() calls if
666 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
667 These can also be switched on/off via
668 <debugfs>/dynamic_printk/modules
670 earlycon= [KNL] Output early console device and options.
671 uart[8250],io,<addr>[,options]
672 uart[8250],mmio,<addr>[,options]
673 Start an early, polled-mode console on the 8250/16550
674 UART at the specified I/O port or MMIO address.
675 The options are the same as for ttyS, above.
677 earlyprintk= [X86,SH,BLACKFIN]
679 earlyprintk=serial[,ttySn[,baudrate]]
682 Append ",keep" to not disable it when the real console
685 Only vga or serial or usb debug port at a time.
687 Currently only ttyS0 and ttyS1 are supported.
689 Interaction with the standard serial driver is not
692 The VGA output is eventually overwritten by the real
698 Format: {"off" | "on" | "skip[mbr]"}
700 eisa_irq_edge= [PARISC,HW]
701 See header of drivers/parisc/eisa.c.
704 See comment before function elanfreq_setup() in
705 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
708 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
709 See Documentation/block/as-iosched.txt and
710 Documentation/block/deadline-iosched.txt for details.
712 elfcorehdr= [IA64,PPC,SH,X86]
713 Specifies physical address of start of kernel core
714 image elf header. Generally kexec loader will
715 pass this option to capture kernel.
716 See Documentation/kdump/kdump.txt for details.
718 enable_mtrr_cleanup [X86]
719 The kernel tries to adjust MTRR layout from continuous
720 to discrete, to make X server driver able to add WB
721 entry later. This parameter enables that.
723 enable_timer_pin_1 [X86]
724 Enable PIN 1 of APIC timer
725 Can be useful to work around chipset bugs
726 (in particular on some ATI chipsets).
727 The kernel tries to set a reasonable default.
729 enforcing [SELINUX] Set initial enforcing status.
731 See security/selinux/Kconfig help text.
732 0 -- permissive (log only, no denials).
733 1 -- enforcing (deny and log).
735 Value can be changed at runtime via /selinux/enforce.
737 ether= [HW,NET] Ethernet cards parameters
738 This option is obsoleted by the "netdev=" option, which
739 has equivalent usage. See its documentation for details.
741 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
746 fail_make_request=[KNL]
747 General fault injection mechanism.
748 Format: <interval>,<probability>,<space>,<times>
749 See also /Documentation/fault-injection/.
752 See header of drivers/scsi/fd_mcs.c.
755 See header of drivers/scsi/fdomain.c.
758 See Documentation/blockdev/floppy.txt.
760 force_pal_cache_flush
761 [IA-64] Avoid check_sal_cache_flush which may hang on
762 buggy SAL_CACHE_FLUSH implementations. Using this
763 parameter will force ia64_sal_cache_flush to call
764 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
767 [FTRACE] will set and start the specified tracer
768 as early as possible in order to facilitate early
772 [FTRACE] will dump the trace buffers on oops.
774 ftrace_filter=[function-list]
775 [FTRACE] Limit the functions traced by the function
776 tracer at boot up. function-list is a comma separated
777 list of functions. This list can be changed at run
778 time by the set_ftrace_filter file in the debugfs
781 ftrace_notrace=[function-list]
782 [FTRACE] Do not trace the functions specified in
783 function-list. This list can be changed at run time
784 by the set_ftrace_notrace file in the debugfs
788 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
789 support via parallel port (up to 5 devices per port)
790 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
791 See also Documentation/input/joystick-parport.txt
795 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
800 See header of drivers/scsi/gdth.c.
802 gpt [EFI] Forces disk with valid GPT signature but
803 invalid Protective MBR to be treated as GPT.
807 hashdist= [KNL,NUMA] Large hashes allocated during boot
808 are distributed across NUMA nodes. Defaults on
809 for 64bit NUMA, off otherwise.
810 Format: 0 | 1 (for off | on)
812 hcl= [IA-64] SGI's Hardware Graph compatibility layer
814 hd= [EIDE] (E)IDE hard drive subsystem geometry
815 Format: <cyl>,<head>,<sect>
817 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
818 size of <nn>. This works even on boxes that have no
819 highmem otherwise. This also works to reduce highmem
820 size on bigger boxes.
822 highres= [KNL] Enable/disable high resolution timer mode.
823 Valid parameters: "on", "off"
827 See Documentation/isdn/README.HiSax.
831 hpet= [X86-32,HPET] option to control HPET usage
832 Format: { enable (default) | disable | force |
834 disable: disable HPET and use PIT instead
835 force: allow force enabled of undocumented chips (ICH4,
837 verbose: show contents of HPET registers during setup
839 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
840 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
841 On x86-64 and powerpc, this option can be specified
842 multiple times interleaved with hugepages= to reserve
843 huge pages of different sizes. Valid pages sizes on
844 x86-64 are 2M (when the CPU supports "pse") and 1G
845 (when the CPU supports the "pdpe1gb" cpuinfo flag)
846 Note that 1GB pages can only be allocated at boot time
847 using hugepages= and not freed afterwards.
849 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
850 terminal devices. Valid values: 0..8
851 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
852 If specified, z/VM IUCV HVC accepts connections
853 from listed z/VM user IDs only.
855 i2c_bus= [HW] Override the default board specific I2C bus speed
856 or register an additional I2C bus that is not
857 registered from board initialization code.
861 i8042.debug [HW] Toggle i8042 debug mode
862 i8042.direct [HW] Put keyboard port into non-translated mode
863 i8042.dumbkbd [HW] Pretend that controller can only read data from
864 keyboard and cannot control its state
865 (Don't attempt to blink the leds)
866 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
867 i8042.nokbd [HW] Don't check/create keyboard port
868 i8042.noloop [HW] Disable the AUX Loopback command while probing
870 i8042.nomux [HW] Don't check presence of an active multiplexing
872 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
875 [HW] Frequency with which keyboard LEDs should blink
876 when kernel panics (default is 0.5 sec)
877 i8042.reset [HW] Reset the controller during init and cleanup
878 i8042.unlock [HW] Unlock (ignore) the keylock
882 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
883 indicates that the driver is running on unsupported
885 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
886 does not match list of supported models.
888 [HW] Report power status in /proc/i8k
889 (disabled by default)
890 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
893 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
894 See Documentation/mca.txt.
897 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
899 ide-core.nodma= [HW] (E)IDE subsystem
900 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
901 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
902 .cdrom .chs .ignore_cable are additional options
903 See Documentation/ide/ide.txt.
905 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
906 Claim all unknown PCI IDE storage controllers.
909 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
910 Poll forces a polling idle loop that can slightly
911 improve the performance of waking up a idle CPU, but
912 will use a lot of power and make the system run hot.
914 idle=mwait: On systems which support MONITOR/MWAIT but
915 the kernel chose to not use it because it doesn't save
916 as much power as a normal idle loop, use the
917 MONITOR/MWAIT idle loop anyways. Performance should be
918 the same as idle=poll.
919 idle=halt: Halt is forced to be used for CPU idle.
920 In such case C2/C3 won't be used again.
921 idle=nomwait: Disable mwait for CPU C-states
923 ignore_loglevel [KNL]
924 Ignore loglevel setting - this will print /all/
925 kernel messages to the console. Useful for debugging.
928 Set number of hash buckets for inode cache.
931 Format: { "0" | "1" }
932 0 -- integrity auditing messages. (Default)
933 1 -- enable informational integrity auditing messages.
936 Formt: { "sha1" | "md5" }
940 Load a policy which meets the needs of the Trusted
941 Computing Base. This means IMA will measure all
942 programs exec'd, files mmap'd for exec, and all files
943 opened for read by uid=0.
946 See header of drivers/scsi/in2000.c.
950 Run specified binary instead of /sbin/init as init
953 initcall_debug [KNL] Trace initcalls as they are executed. Useful
954 for working out where the kernel is dying during
957 initrd= [BOOT] Specify the location of the initial ramdisk
959 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
962 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
964 Enable intel iommu driver.
966 Disable intel iommu driver.
967 igfx_off [Default Off]
968 By default, gfx is mapped as normal device. If a gfx
969 device has a dedicated DMAR unit, the DMAR unit is
970 bypassed by not enabling DMAR with this option. In
971 this case, gfx device will use physical address for
974 With this option iommu will not optimize to look
975 for io virtual address below 32 bit forcing dual
976 address cycle on pci bus for cards supporting greater
977 than 32 bit addressing. The default is to look
978 for translation below 32 bit and if not available
979 then look in the higher range.
981 With this option on every unmap_single operation will
982 result in a hardware IOTLB flush operation as opposed
983 to batching them for performance.
987 iomem= Disable strict checking of access to MMIO memory
988 strict regions from userspace.
1003 io7= [HW] IO7 for Marvel based alpha systems
1004 See comment before marvel_specify_io7 in
1005 arch/alpha/kernel/core_marvel.c.
1007 io_delay= [X86] I/O delay method
1009 Standard port 0x80 based delay
1011 Alternate port 0xed based delay (needed on some systems)
1013 Simple two microseconds delay
1018 See Documentation/filesystems/nfsroot.txt.
1020 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1021 See comment before ip2_setup() in
1022 drivers/char/ip2/ip2base.c.
1024 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1025 See header of drivers/scsi/ips.c.
1028 When an interrupt is not handled search all handlers
1029 for it. Intended to get systems with badly broken
1033 When an interrupt is not handled search all handlers
1034 for it. Also check all handlers each timer
1035 interrupt. Intended to get systems with badly broken
1039 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1041 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1043 <cpu number>,...,<cpu number>
1045 <cpu number>-<cpu number>
1046 (must be a positive range in ascending order)
1048 <cpu number>,...,<cpu number>-<cpu number>
1050 This option can be used to specify one or more CPUs
1051 to isolate from the general SMP balancing and scheduling
1052 algorithms. You can move a process onto or off an
1053 "isolated" CPU via the CPU affinity syscalls or cpuset.
1054 <cpu number> begins at 0 and the maximum value is
1055 "number of CPUs in system - 1".
1057 This option is the preferred way to isolate CPUs. The
1058 alternative -- manually setting the CPU mask of all
1059 tasks in the system -- can cause problems and
1060 suboptimal load balancer performance.
1064 js= [HW,JOY] Analog joystick
1065 See Documentation/input/joystick.txt.
1069 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1070 specifies the amount of memory usable by the kernel
1071 for non-movable allocations. The requested amount is
1072 spread evenly throughout all nodes in the system. The
1073 remaining memory in each node is used for Movable
1074 pages. In the event, a node is too small to have both
1075 kernelcore and Movable pages, kernelcore pages will
1076 take priority and other nodes will have a larger number
1077 of kernelcore pages. The Movable zone is used for the
1078 allocation of pages that may be reclaimed or moved
1079 by the page migration subsystem. This means that
1080 HugeTLB pages may not be allocated from this zone.
1081 Note that allocations like PTEs-from-HighMem still
1082 use the HighMem zone if it exists, and the Normal
1083 zone if it does not.
1085 kgdboc= [HW] kgdb over consoles.
1086 Requires a tty driver that supports console polling.
1087 (only serial supported for now)
1088 Format: <serial_device>[,baud]
1090 kmac= [MIPS] korina ethernet MAC address.
1091 Configure the RouterBoard 532 series on-chip
1092 Ethernet adapter MAC address.
1094 kmemleak= [KNL] Boot-time kmemleak enable/disable
1095 Valid arguments: on, off
1098 kstack=N [X86] Print N words from the kernel stack
1105 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1108 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1111 libata.dma= [LIBATA] DMA control
1112 libata.dma=0 Disable all PATA and SATA DMA
1113 libata.dma=1 PATA and SATA Disk DMA only
1114 libata.dma=2 ATAPI (CDROM) DMA only
1115 libata.dma=4 Compact Flash DMA only
1116 Combinations also work, so libata.dma=3 enables DMA
1117 for disks and CDROMs, but not CFs.
1119 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1123 libata.force= [LIBATA] Force configurations. The format is comma
1124 separated list of "[ID:]VAL" where ID is
1125 PORT[:DEVICE]. PORT and DEVICE are decimal numbers
1126 matching port, link or device. Basically, it matches
1127 the ATA ID string printed on console by libata. If
1128 the whole ID part is omitted, the last PORT and DEVICE
1129 values are used. If ID hasn't been specified yet, the
1130 configuration applies to all ports, links and devices.
1132 If only DEVICE is omitted, the parameter applies to
1133 the port and all links and devices behind it. DEVICE
1134 number of 0 either selects the first device or the
1135 first fan-out link behind PMP device. It does not
1136 select the host link. DEVICE number of 15 selects the
1137 host link and device attached to it.
1139 The VAL specifies the configuration to force. As long
1140 as there's no ambiguity shortcut notation is allowed.
1141 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1142 The following configurations can be forced.
1144 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1145 Any ID with matching PORT is used.
1147 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1149 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1150 udma[/][16,25,33,44,66,100,133] notation is also
1153 * [no]ncq: Turn on or off NCQ.
1155 * nohrst, nosrst, norst: suppress hard, soft
1158 If there are multiple matching configurations changing
1159 the same attribute, the last one is used.
1161 lmb=debug [KNL] Enable lmb debug messages.
1163 load_ramdisk= [RAM] List of ramdisks to load from floppy
1164 See Documentation/blockdev/ramdisk.txt.
1166 lockd.nlm_grace_period=P [NFS] Assign grace period.
1169 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1172 lockd.nlm_timeout=T [NFS] Assign timeout value.
1175 lockd.nlm_udpport=M [NFS] Assign UDP port.
1178 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1181 loglevel= All Kernel Messages with a loglevel smaller than the
1182 console loglevel will be printed to the console. It can
1183 also be changed with klogd or other programs. The
1184 loglevels are defined as follows:
1186 0 (KERN_EMERG) system is unusable
1187 1 (KERN_ALERT) action must be taken immediately
1188 2 (KERN_CRIT) critical conditions
1189 3 (KERN_ERR) error conditions
1190 4 (KERN_WARNING) warning conditions
1191 5 (KERN_NOTICE) normal but significant condition
1192 6 (KERN_INFO) informational
1193 7 (KERN_DEBUG) debug-level messages
1195 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1196 Format: { n | nk | nM }
1197 n must be a power of two. The default size
1198 is set in the kernel config file.
1200 logo.nologo [FB] Disables display of the built-in Linux logo.
1201 This may be used to provide more screen space for
1202 kernel log messages and is useful when debugging
1203 kernel boot problems.
1205 lp=0 [LP] Specify parallel ports to use, e.g,
1206 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1207 lp=reset first parallel port). 'lp=0' disables the
1208 lp=auto printer driver. 'lp=reset' (which can be
1209 specified in addition to the ports) causes
1210 attached printers to be reset. Using
1211 lp=port1,port2,... specifies the parallel ports
1212 to associate lp devices with, starting with
1213 lp0. A port specification may be 'none' to skip
1214 that lp device, or a parport name such as
1215 'parport0'. Specifying 'lp=auto' instead of a
1216 port specification list means that device IDs
1217 from each port should be examined, to see if
1218 an IEEE 1284-compliant printer is attached; if
1219 so, the driver will manage that printer.
1220 See also header of drivers/char/lp.c.
1223 Sets loops_per_jiffy to given constant, thus avoiding
1224 time-consuming boot-time autodetection (up to 250 ms per
1225 CPU). 0 enables autodetection (default). To determine
1226 the correct value for your kernel, boot with normal
1227 autodetection and see what value is printed. Note that
1228 on SMP systems the preset will be applied to all CPUs,
1229 which is likely to cause problems if your CPUs need
1230 significantly divergent settings. An incorrect value
1231 will cause delays in the kernel to be wrong, leading to
1232 unpredictable I/O errors and other breakage. Although
1233 unlikely, in the extreme case this might damage your
1237 Format: <io>,<irq>,<dma>
1239 mac5380= [HW,SCSI] Format:
1240 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1242 machvec= [IA64] Force the use of a particular machine-vector
1243 (machvec) in a generic kernel.
1244 Example: machvec=hpzx1_swiotlb
1246 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1247 than or equal to this physical address is ignored.
1249 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1250 should make use of. maxcpus=n : n >= 0 limits the
1251 kernel to using 'n' processors. n=0 is a special case,
1252 it is equivalent to "nosmp", which also disables
1255 max_loop= [LOOP] Maximum number of loopback devices that can
1259 max_luns= [SCSI] Maximum number of LUNs to probe.
1260 Should be between 1 and 2^32-1.
1263 [SCSI] Maximum number of LUNs received.
1264 Should be between 1 and 16384.
1268 mce [X86-32] Machine Check Exception
1270 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1272 md= [HW] RAID subsystems devices and level
1273 See Documentation/md.txt.
1276 Format: <first>,<last>
1277 Specifies range of consoles to be captured by the MDA.
1279 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1280 Amount of memory to be used when the kernel is not able
1281 to see the whole system memory or for test.
1282 [X86-32] Use together with memmap= to avoid physical
1283 address space collisions. Without memmap= PCI devices
1284 could be placed at addresses belonging to unused RAM.
1286 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1290 [KNL,SH] Allow user to override the default size for
1291 per-device physically contiguous DMA buffers.
1293 memmap=exactmap [KNL,X86] Enable setting of an exact
1294 E820 memory map, as specified by the user.
1295 Such memmap=exactmap lines can be constructed based on
1296 BIOS output or other requirements. See the memmap=nn@ss
1299 memmap=nn[KMG]@ss[KMG]
1300 [KNL] Force usage of a specific region of memory
1301 Region of memory to be used, from ss to ss+nn.
1303 memmap=nn[KMG]#ss[KMG]
1304 [KNL,ACPI] Mark specific memory as ACPI data.
1305 Region of memory to be used, from ss to ss+nn.
1307 memmap=nn[KMG]$ss[KMG]
1308 [KNL,ACPI] Mark specific memory as reserved.
1309 Region of memory to be used, from ss to ss+nn.
1310 Example: Exclude memory from 0x18690000-0x1869ffff
1311 memmap=64K$0x18690000
1313 memmap=0x10000$0x18690000
1315 memory_corruption_check=0/1 [X86]
1316 Some BIOSes seem to corrupt the first 64k of
1317 memory when doing things like suspend/resume.
1318 Setting this option will scan the memory
1319 looking for corruption. Enabling this will
1320 both detect corruption and prevent the kernel
1321 from using the memory being corrupted.
1322 However, its intended as a diagnostic tool; if
1323 repeatable BIOS-originated corruption always
1324 affects the same memory, you can use memmap=
1325 to prevent the kernel from using that memory.
1327 memory_corruption_check_size=size [X86]
1328 By default it checks for corruption in the low
1329 64k, making this memory unavailable for normal
1330 use. Use this parameter to scan for
1331 corruption in more or less memory.
1333 memory_corruption_check_period=seconds [X86]
1334 By default it checks for corruption every 60
1335 seconds. Use this parameter to check at some
1336 other rate. 0 disables periodic checking.
1338 memtest= [KNL,X86] Enable memtest
1340 default : 0 <disable>
1341 Specifies the number of memtest passes to be
1342 performed. Each pass selects another test
1343 pattern from a given set of patterns. Memtest
1344 fills the memory with this pattern, validates
1345 memory contents and reserves bad memory
1346 regions that are detected.
1348 meye.*= [HW] Set MotionEye Camera parameters
1349 See Documentation/video4linux/meye.txt.
1351 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1352 Multi-Function General Purpose Timers on AMD Geode
1355 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1356 the BIOS has incorrectly applied a workaround. TinyBIOS
1357 version 0.98 is known to be affected, 0.99 fixes the
1358 problem by letting the user disable the workaround.
1362 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1363 physical address is ignored.
1366 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1367 parameter allows control of the logging verbosity for
1368 the additional memory initialisation checks. A value
1369 of 0 disables mminit logging and a level of 4 will
1370 log everything. Information is printed at KERN_DEBUG
1371 so loglevel=8 may also need to be specified.
1374 [MOUSE] Maximum time between finger touching and
1375 leaving touchpad surface for touch to be considered
1376 a tap and be reported as a left button click (for
1377 touchpads working in absolute mode only).
1379 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1380 reporting absolute coordinates, such as tablets
1381 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1382 reporting absolute coordinates, such as tablets
1384 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1385 is similar to kernelcore except it specifies the
1386 amount of memory used for migratable allocations.
1387 If both kernelcore and movablecore is specified,
1388 then kernelcore will be at *least* the specified
1389 value but may be more. If movablecore on its own
1390 is specified, the administrator must be careful
1391 that the amount of memory usable for all allocations
1397 MTD_Partition= [MTD]
1398 Format: <name>,<region-number>,<size>,<offset>
1400 MTD_Region= [MTD] Format:
1401 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1404 See drivers/mtd/cmdlinepart.c.
1407 ARM/S3C2412 JIVE boot control
1409 See arch/arm/mach-s3c2412/mach-jive.c
1411 mtouchusb.raw_coordinates=
1412 [HW] Make the MicroTouch USB driver use raw coordinates
1413 ('y', default) or cooked coordinates ('n')
1415 mtrr_chunk_size=nn[KMG] [X86]
1416 used for mtrr cleanup. It is largest continuous chunk
1417 that could hold holes aka. UC entries.
1419 mtrr_gran_size=nn[KMG] [X86]
1420 Used for mtrr cleanup. It is granularity of mtrr block.
1422 Large value could prevent small alignment from
1425 mtrr_spare_reg_nr=n [X86]
1427 Range: 0,7 : spare reg number
1429 Used for mtrr cleanup. It is spare mtrr entries number.
1430 Set to 2 or more if your graphical card needs more.
1432 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1435 See header of drivers/scsi/NCR_D700.c.
1439 ncr53c400= [HW,SCSI]
1441 ncr53c400a= [HW,SCSI]
1443 ncr53c406a= [HW,SCSI]
1445 ncr53c8xx= [HW,SCSI]
1447 netdev= [NET] Network devices parameters
1448 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1449 Note that mem_start is often overloaded to mean
1450 something different and driver-specific.
1451 This usage is only documented in each driver source
1455 [NETFILTER] Enable connection tracking flow accounting
1456 0 to disable accounting
1457 1 to enable accounting
1458 Default value depends on CONFIG_NF_CT_ACCT that is
1459 going to be removed in 2.6.29.
1462 See Documentation/filesystems/nfsroot.txt.
1464 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1465 See Documentation/filesystems/nfsroot.txt.
1467 nfs.callback_tcpport=
1468 [NFS] set the TCP port on which the NFSv4 callback
1469 channel should listen.
1471 nfs.idmap_cache_timeout=
1472 [NFS] set the maximum lifetime for idmapper cache
1476 [NFS] enable 64-bit inode numbers.
1477 If zero, the NFS client will fake up a 32-bit inode
1478 number for the readdir() and stat() syscalls instead
1479 of returning the full 64-bit number.
1480 The default is to return 64-bit inode numbers.
1482 nmi_debug= [KNL,AVR32] Specify one or more actions to take
1483 when a NMI is triggered.
1484 Format: [state][,regs][,debounce][,die]
1486 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1487 Format: [panic,][num]
1489 0 - turn nmi_watchdog off
1490 1 - use the IO-APIC timer for the NMI watchdog
1491 2 - use the local APIC for the NMI watchdog using
1492 a performance counter. Note: This will use one
1493 performance counter and the local APIC's performance
1495 When panic is specified, panic when an NMI watchdog
1497 This is useful when you use a panic=... timeout and
1498 need the box quickly up again.
1499 Instead of 1 and 2 it is possible to use the following
1500 symbolic names: lapic and ioapic
1501 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1503 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1504 emulation library even if a 387 maths coprocessor
1508 [HW] Never suspend the console
1509 Disable suspending of consoles during suspend and
1510 hibernate operations. Once disabled, debugging
1511 messages can reach various consoles while the rest
1512 of the system is being put to sleep (ie, while
1513 debugging driver suspend/resume hooks). This may
1514 not work reliably with all consoles, but is known
1515 to work with serial and VGA consoles.
1517 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1518 caches in the slab allocator. Saves per-node memory,
1519 but will impact performance.
1523 noapic [SMP,APIC] Tells the kernel to not make use of any
1524 IOAPICs that may be present in the system.
1526 nobats [PPC] Do not use BATs for mapping kernel lowmem
1527 on "Classic" PPC cores.
1531 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1533 nodelayacct [KNL] Disable per-task delay accounting
1535 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1537 nodsp [SH] Disable hardware DSP at boot time.
1539 noefi [X86] Disable EFI runtime services support.
1544 On X86-32 available only on PAE configured kernels.
1545 noexec=on: enable non-executable mappings (default)
1546 noexec=off: disable non-executable mappings
1549 This affects only 32-bit executables.
1550 noexec32=on: enable non-executable mappings (default)
1551 read doesn't imply executable mappings
1552 noexec32=off: disable non-executable mappings
1553 read implies executable mappings
1555 nofpu [SH] Disable hardware FPU at boot time.
1557 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1558 register save and restore. The kernel will only save
1559 legacy floating-point registers on task switch.
1561 noxsave [BUGS=X86] Disables x86 extended register state save
1562 and restore using xsave. The kernel will fallback to
1563 enabling legacy floating-point and sse state.
1565 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1566 wfi(ARM) instruction doesn't work correctly and not to
1567 use it. This is also useful when using JTAG debugger.
1569 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1570 instruction doesn't work correctly and not to
1573 no_file_caps Tells the kernel not to honor file capabilities. The
1574 only way then for a file to be executed with privilege
1575 is to be setuid root or executed by root.
1577 nohalt [IA-64] Tells the kernel not to use the power saving
1578 function PAL_HALT_LIGHT when idle. This increases
1579 power-consumption. On the positive side, it reduces
1580 interrupt wake-up latency, which may improve performance
1581 in certain environments such as networked servers or
1584 nohz= [KNL] Boottime enable/disable dynamic ticks
1585 Valid arguments: on, off
1588 noiotrap [SH] Disables trapped I/O port accesses.
1590 noirqdebug [X86-32] Disables the code which attempts to detect and
1591 disable unhandled interrupt sources.
1593 no_timer_check [X86,APIC] Disables the code which tests for
1594 broken timer IRQ sources.
1596 noisapnp [ISAPNP] Disables ISA PnP code.
1598 noinitrd [RAM] Tells the kernel not to load any configured
1601 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1606 nojitter [IA64] Disables jitter checking for ITC timers.
1608 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1610 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1612 noltlbs [PPC] Do not use large page/tlb entries for kernel
1613 lowmem mapping on PPC40x.
1615 nomca [IA-64] Disable machine check abort handling
1617 nomce [X86-32] Machine Check Exception
1619 nomfgpt [X86-32] Disable Multi-Function General Purpose
1620 Timer usage (for AMD Geode machines).
1622 norandmaps Don't use address space randomization. Equivalent to
1623 echo 0 > /proc/sys/kernel/randomize_va_space
1625 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1627 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1628 with UP alternatives
1630 noresidual [PPC] Don't use residual data on PReP machines.
1632 noresume [SWSUSP] Disables resume and restores original swap
1635 no-scroll [VGA] Disables scrollback.
1636 This is required for the Braillex ib80-piezo Braille
1637 reader made by F.H. Papenmeier (Germany).
1641 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1643 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1644 and disable the IO APIC. legacy for "maxcpus=0".
1646 nosoftlockup [KNL] Disable the soft-lockup detector.
1648 noswapaccount [KNL] Disable accounting of swap in memory resource
1649 controller. (See Documentation/cgroups/memory.txt)
1651 nosync [HW,M68K] Disables sync negotiation for all devices.
1653 notsc [BUGS=X86-32] Disable Time Stamp Counter
1655 nousb [USB] Disable the USB subsystem
1659 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1661 nptcg= [IA64] Override max number of concurrent global TLB
1662 purges which is reported from either PAL_VM_SUMMARY or
1665 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1667 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1668 one of ['zone', 'node', 'default'] can be specified
1669 This can be set from sysctl after boot.
1670 See Documentation/sysctl/vm.txt for details.
1672 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1673 See Documentation/debugging-via-ohci1394.txt for more
1676 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1677 Rather than timing out after 20 ms if an EC
1678 command is not properly ACKed, override the length
1679 of the timeout. We have interrupts disabled while
1680 waiting for the ACK, so if this is set too high
1681 interrupts *may* be lost!
1686 oprofile.timer= [HW]
1687 Use timer interrupt instead of performance counters
1689 oprofile.cpu_type= Force an oprofile cpu type
1690 This might be useful if you have an older oprofile
1691 userland or if you want common events.
1692 Format: { archperfmon }
1693 archperfmon: [X86] Force use of architectural
1694 perfmon on Intel CPUs instead of the
1695 CPU specific event set.
1697 osst= [HW,SCSI] SCSI Tape Driver
1698 Format: <buffer_size>,<write_threshold>
1699 See also Documentation/scsi/st.txt.
1701 panic= [KNL] Kernel behaviour on panic
1704 parkbd.port= [HW] Parallel port number the keyboard adapter is
1705 connected to, default is 0.
1707 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1708 0 for XT, 1 for AT (default is AT).
1711 parport= [HW,PPT] Specify parallel ports. 0 disables.
1712 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1713 Use 'auto' to force the driver to use any
1714 IRQ/DMA settings detected (the default is to
1715 ignore detected IRQ/DMA settings because of
1716 possible conflicts). You can specify the base
1717 address, IRQ, and DMA settings; IRQ and DMA
1718 should be numbers, or 'auto' (for using detected
1719 settings on that particular port), or 'nofifo'
1720 (to avoid using a FIFO even if it is detected).
1721 Parallel ports are assigned in the order they
1722 are specified on the command line, starting
1725 parport_init_mode= [HW,PPT]
1726 Configure VIA parallel port to operate in
1727 a specific mode. This is necessary on Pegasos
1728 computer where firmware has no options for setting
1729 up parallel port mode and sets it to spp.
1730 Currently this function knows 686a and 8231 chips.
1731 Format: [spp|ps2|epp|ecp|ecpepp]
1733 pas2= [HW,OSS] Format:
1734 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1737 See header of drivers/scsi/pas16.c.
1740 Halt all CPUs after the first oops has been printed for
1741 the specified number of seconds. This is to be used if
1742 your oopses keep scrolling off the screen.
1747 See header of drivers/block/paride/pcd.c.
1748 See also Documentation/blockdev/paride.txt.
1750 pci=option[,option...] [PCI] various PCI subsystem options:
1751 earlydump [X86] dump PCI config space before the kernel
1753 off [X86] don't probe for the PCI bus
1754 bios [X86-32] force use of PCI BIOS, don't access
1755 the hardware directly. Use this if your machine
1756 has a non-standard PCI host bridge.
1757 nobios [X86-32] disallow use of PCI BIOS, only direct
1758 hardware access methods are allowed. Use this
1759 if you experience crashes upon bootup and you
1760 suspect they are caused by the BIOS.
1761 conf1 [X86] Force use of PCI Configuration
1763 conf2 [X86] Force use of PCI Configuration
1765 noaer [PCIE] If the PCIEAER kernel config parameter is
1766 enabled, this kernel boot option can be used to
1767 disable the use of PCIE advanced error reporting.
1768 nodomains [PCI] Disable support for multiple PCI
1769 root domains (aka PCI segments, in ACPI-speak).
1770 nommconf [X86] Disable use of MMCONFIG for PCI
1772 nomsi [MSI] If the PCI_MSI kernel config parameter is
1773 enabled, this kernel boot option can be used to
1774 disable the use of MSI interrupts system-wide.
1775 noioapicquirk [APIC] Disable all boot interrupt quirks.
1776 Safety option to keep boot IRQs enabled. This
1777 should never be necessary.
1778 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1779 primary IO-APIC for bridges that cannot disable
1780 boot IRQs. This fixes a source of spurious IRQs
1781 when the system masks IRQs.
1782 noioapicreroute [APIC] Disable workaround that uses the
1783 boot IRQ equivalent of an IRQ that connects to
1784 a chipset where boot IRQs cannot be disabled.
1785 The opposite of ioapicreroute.
1786 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1787 routing table. These calls are known to be buggy
1788 on several machines and they hang the machine
1789 when used, but on other computers it's the only
1790 way to get the interrupt routing table. Try
1791 this option if the kernel is unable to allocate
1792 IRQs or discover secondary PCI buses on your
1794 rom [X86] Assign address space to expansion ROMs.
1795 Use with caution as certain devices share
1796 address decoders between ROMs and other
1798 norom [X86] Do not assign address space to
1799 expansion ROMs that do not already have
1800 BIOS assigned address ranges.
1801 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1802 assigned automatically to PCI devices. You can
1803 make the kernel exclude IRQs of your ISA cards
1805 pirqaddr=0xAAAAA [X86] Specify the physical address
1806 of the PIRQ table (normally generated
1807 by the BIOS) if it is outside the
1808 F0000h-100000h range.
1809 lastbus=N [X86] Scan all buses thru bus #N. Can be
1810 useful if the kernel is unable to find your
1811 secondary buses and you want to tell it
1812 explicitly which ones they are.
1813 assign-busses [X86] Always assign all PCI bus
1814 numbers ourselves, overriding
1815 whatever the firmware may have done.
1816 usepirqmask [X86] Honor the possible IRQ mask stored
1817 in the BIOS $PIR table. This is needed on
1818 some systems with broken BIOSes, notably
1819 some HP Pavilion N5400 and Omnibook XE3
1820 notebooks. This will have no effect if ACPI
1821 IRQ routing is enabled.
1822 noacpi [X86] Do not use ACPI for IRQ routing
1823 or for PCI scanning.
1824 use_crs [X86] Use _CRS for PCI resource
1826 routeirq Do IRQ routing for all PCI devices.
1827 This is normally done in pci_enable_device(),
1828 so this option is a temporary workaround
1829 for broken drivers that don't call it.
1830 skip_isa_align [X86] do not align io start addr, so can
1831 handle more pci cards
1832 firmware [ARM] Do not re-enumerate the bus but instead
1833 just use the configuration from the
1834 bootloader. This is currently used on
1835 IXP2000 systems where the bus has to be
1836 configured a certain way for adjunct CPUs.
1837 noearly [X86] Don't do any early type 1 scanning.
1838 This might help on some broken boards which
1839 machine check when some devices' config space
1840 is read. But various workarounds are disabled
1841 and some IOMMU drivers will not work.
1842 bfsort Sort PCI devices into breadth-first order.
1843 This sorting is done to get a device
1844 order compatible with older (<= 2.4) kernels.
1845 nobfsort Don't sort PCI devices into breadth-first order.
1846 cbiosize=nn[KMG] The fixed amount of bus space which is
1847 reserved for the CardBus bridge's IO window.
1848 The default value is 256 bytes.
1849 cbmemsize=nn[KMG] The fixed amount of bus space which is
1850 reserved for the CardBus bridge's memory
1851 window. The default value is 64 megabytes.
1854 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1855 Specifies alignment and device to reassign
1856 aligned memory resources.
1857 If <order of align> is not specified,
1858 PAGE_SIZE is used as alignment.
1859 PCI-PCI bridge can be specified, if resource
1860 windows need to be expanded.
1862 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1865 force Enable ASPM even on devices that claim not to support it.
1866 WARNING: Forcing ASPM on may cause system lockups.
1868 pcmv= [HW,PCMCIA] BadgePAD 4
1871 See Documentation/blockdev/paride.txt.
1873 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
1876 See arch/parisc/kernel/pdc_chassis.c
1879 See Documentation/blockdev/paride.txt.
1882 See Documentation/blockdev/paride.txt.
1884 pirq= [SMP,APIC] Manual mp-table setup
1885 See Documentation/x86/i386/IO-APIC.txt.
1887 plip= [PPT,NET] Parallel port network link
1888 Format: { parport<nr> | timid | 0 }
1889 See also Documentation/parport.txt.
1891 pmtmr= [X86] Manual setup of pmtmr I/O Port.
1892 Override pmtimer IOPort with a hex value.
1896 Enable PNP debug messages. This depends on the
1897 CONFIG_PNP_DEBUG_MESSAGES option.
1903 { on | off | curr | res | no-curr | no-res }
1906 [ISAPNP] Exclude IRQs for the autoconfiguration
1909 [ISAPNP] Exclude DMAs for the autoconfiguration
1911 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
1912 Ranges are in pairs (I/O port base and size).
1915 [ISAPNP] Exclude memory regions for the
1917 Ranges are in pairs (memory base and size).
1919 ports= [IP_VS_FTP] IPVS ftp helper module
1921 Up to 8 (IP_VS_APP_MAX_PORTS) ports
1923 Format: <port>,<port>....
1925 print-fatal-signals=
1926 [KNL] debug: print fatal signals
1927 print-fatal-signals=1: print segfault info to
1931 printk.time= Show timing data prefixed to each printk message line
1932 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
1934 processor.max_cstate= [HW,ACPI]
1935 Limit processor to maximum C-state
1936 max_cstate=9 overrides any DMI blacklist limit.
1938 processor.nocst [HW,ACPI]
1939 Ignore the _CST method to determine C-states,
1940 instead using the legacy FADT method
1942 profile= [KNL] Enable kernel profiling via /proc/profile
1943 Format: [schedule,]<number>
1944 Param: "schedule" - profile schedule points.
1945 Param: <number> - step/bucket size as a power of 2 for
1946 statistical time based profiling.
1947 Param: "sleep" - profile D-state sleeping (millisecs).
1948 Requires CONFIG_SCHEDSTATS
1949 Param: "kvm" - profile VM exits.
1951 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
1953 See Documentation/blockdev/ramdisk.txt.
1955 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
1956 probe for; one of (bare|imps|exps|lifebook|any).
1957 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
1959 psmouse.resetafter= [HW,MOUSE]
1960 Try to reset the device after so many bad packets
1963 [HW,MOUSE] Set desired mouse resolution, in dpi.
1964 psmouse.smartscroll=
1965 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
1966 0 = disabled, 1 = enabled (default).
1968 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
1970 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
1973 See Documentation/blockdev/paride.txt.
1976 [KNL] Number of legacy pty's. Overwrites compiled-in
1979 quiet [KNL] Disable most log messages
1984 See Documentation/md.txt.
1986 ramdisk_blocksize= [RAM]
1987 See Documentation/blockdev/ramdisk.txt.
1989 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
1990 See Documentation/blockdev/ramdisk.txt.
1992 rcupdate.blimit= [KNL,BOOT]
1993 Set maximum number of finished RCU callbacks to process
1996 rcupdate.qhimark= [KNL,BOOT]
1997 Set threshold of queued
1998 RCU callbacks over which batch limiting is disabled.
2000 rcupdate.qlowmark= [KNL,BOOT]
2001 Set threshold of queued RCU callbacks below which
2002 batch limiting is re-enabled.
2006 Run specified binary instead of /init from the ramdisk,
2007 used for early userspace startup. See initrd.
2009 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2010 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2011 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2014 [KNL, SMP] Set scheduler's default relax_domain_level.
2015 See Documentation/cgroups/cpusets.txt.
2017 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2019 reservetop= [X86-32]
2021 Reserves a hole at the top of the kernel virtual
2024 reset_devices [KNL] Force drivers to reset the underlying device
2025 during initialization.
2028 Specify the partition device for software suspend
2030 resume_offset= [SWSUSP]
2031 Specify the offset from the beginning of the partition
2032 given by "resume=" at which the swap header is located,
2033 in <PAGE_SIZE> units (needed only for swap files).
2034 See Documentation/power/swsusp-and-swap-files.txt
2036 retain_initrd [RAM] Keep initrd memory after extraction
2038 rhash_entries= [KNL,NET]
2039 Set number of hash buckets for route cache
2041 riscom8= [HW,SERIAL]
2042 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2044 ro [KNL] Mount root device read-only on boot
2046 root= [KNL] Root filesystem
2048 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2049 mount the root filesystem
2051 rootflags= [KNL] Set root filesystem mount option string
2053 rootfstype= [KNL] Set root filesystem type
2055 rootwait [KNL] Wait (indefinitely) for root device to show up.
2056 Useful for devices that are detected asynchronously
2057 (e.g. USB and MMC devices).
2059 root_plug.vendor_id=
2060 [ROOTPLUG] Override the default vendor ID
2062 root_plug.product_id=
2063 [ROOTPLUG] Override the default product ID
2066 [ROOTPLUG] Enable debugging output
2068 rw [KNL] Mount root device read-write on boot
2070 S [KNL] Run init in single mode
2073 See drivers/net/irda/sa1100_ir.c.
2075 sbni= [NET] Granch SBNI12 leased line adapter
2077 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2078 Format: <io>[,<timeout>[,<isapnp>]]
2080 scsi_debug_*= [SCSI]
2081 See drivers/scsi/scsi_debug.c.
2083 scsi_default_dev_flags=
2084 [SCSI] SCSI default device flags
2087 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2088 Format: <vendor>:<model>:<flags>
2089 (flags are integer value)
2091 scsi_logging_level= [SCSI] a bit mask of logging levels
2092 See drivers/scsi/scsi_logging.h for bits. Also
2093 settable via sysctl at dev.scsi.logging_level
2094 (/proc/sys/dev/scsi/logging_level).
2095 There is also a nice 'scsi_logging_level' script in the
2096 S390-tools package, available for download at
2097 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2099 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2100 discovered. async scans them in kernel threads,
2101 allowing boot to proceed. none ignores them, expecting
2102 user space to do the scan.
2104 security= [SECURITY] Choose a security module to enable at boot.
2105 If this boot parameter is not specified, only the first
2106 security module asking for security registration will be
2107 loaded. An invalid security module name will be treated
2108 as if no module has been chosen.
2110 selinux= [SELINUX] Disable or enable SELinux at boot time.
2111 Format: { "0" | "1" }
2112 See security/selinux/Kconfig help text.
2115 Default value is set via kernel config option.
2116 If enabled at boot time, /selinux/disable can be used
2117 later to disable prior to initial policy load.
2119 serialnumber [BUGS=X86-32]
2122 Maximal number of shapers.
2124 show_msr= [x86] show boot-time MSR settings
2125 Format: { <integer> }
2126 Show boot-time (BIOS-initialized) MSR settings.
2127 The parameter means the number of CPUs to show,
2128 for example 1 means boot CPU only.
2131 See header of drivers/scsi/sim710.c.
2138 slub_debug[=options[,slabs]] [MM, SLUB]
2139 Enabling slub_debug allows one to determine the
2140 culprit if slab objects become corrupted. Enabling
2141 slub_debug can create guard zones around objects and
2142 may poison objects when not in use. Also tracks the
2143 last alloc / free. For more information see
2144 Documentation/vm/slub.txt.
2146 slub_max_order= [MM, SLUB]
2147 Determines the maximum allowed order for slabs.
2148 A high setting may cause OOMs due to memory
2149 fragmentation. For more information see
2150 Documentation/vm/slub.txt.
2152 slub_min_objects= [MM, SLUB]
2153 The minimum number of objects per slab. SLUB will
2154 increase the slab order up to slub_max_order to
2155 generate a sufficiently large slab able to contain
2156 the number of objects indicated. The higher the number
2157 of objects the smaller the overhead of tracking slabs
2158 and the less frequently locks need to be acquired.
2159 For more information see Documentation/vm/slub.txt.
2161 slub_min_order= [MM, SLUB]
2162 Determines the mininum page order for slabs. Must be
2163 lower than slub_max_order.
2164 For more information see Documentation/vm/slub.txt.
2166 slub_nomerge [MM, SLUB]
2167 Disable merging of slabs with similar size. May be
2168 necessary if there is some reason to distinguish
2169 allocs to different slabs. Debug options disable
2170 merging on their own.
2171 For more information see Documentation/vm/slub.txt.
2174 Format: <io1>[,<io2>[,...,<io8>]]
2176 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2177 attempt to substitute SMP alternatives once at boot.
2179 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2180 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2181 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2182 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2183 smsc-ircc2.ircc_irq= [HW] IRQ line
2184 smsc-ircc2.ircc_dma= [HW] DMA channel
2185 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2186 0: Toshiba Satellite 1800 (GP data pin select)
2187 1: Fast pin select (default)
2190 snd-ad1816a= [HW,ALSA]
2192 snd-ad1848= [HW,ALSA]
2194 snd-ali5451= [HW,ALSA]
2196 snd-als100= [HW,ALSA]
2198 snd-als4000= [HW,ALSA]
2200 snd-azt2320= [HW,ALSA]
2202 snd-cmi8330= [HW,ALSA]
2204 snd-cmipci= [HW,ALSA]
2206 snd-cs4231= [HW,ALSA]
2208 snd-cs4232= [HW,ALSA]
2210 snd-cs4236= [HW,ALSA]
2212 snd-cs4281= [HW,ALSA]
2214 snd-cs46xx= [HW,ALSA]
2216 snd-dt019x= [HW,ALSA]
2218 snd-dummy= [HW,ALSA]
2220 snd-emu10k1= [HW,ALSA]
2222 snd-ens1370= [HW,ALSA]
2224 snd-ens1371= [HW,ALSA]
2226 snd-es968= [HW,ALSA]
2228 snd-es1688= [HW,ALSA]
2230 snd-es18xx= [HW,ALSA]
2232 snd-es1938= [HW,ALSA]
2234 snd-es1968= [HW,ALSA]
2236 snd-fm801= [HW,ALSA]
2238 snd-gusclassic= [HW,ALSA]
2240 snd-gusextreme= [HW,ALSA]
2242 snd-gusmax= [HW,ALSA]
2246 snd-ice1712= [HW,ALSA]
2248 snd-intel8x0= [HW,ALSA]
2250 snd-interwave= [HW,ALSA]
2255 snd-korg1212= [HW,ALSA]
2257 snd-maestro3= [HW,ALSA]
2259 snd-mpu401= [HW,ALSA]
2261 snd-mtpav= [HW,ALSA]
2263 snd-nm256= [HW,ALSA]
2265 snd-opl3sa2= [HW,ALSA]
2273 snd-opti93x= [HW,ALSA]
2277 snd-rme32= [HW,ALSA]
2279 snd-rme96= [HW,ALSA]
2281 snd-rme9652= [HW,ALSA]
2287 snd-sbawe= [HW,ALSA]
2289 snd-serial= [HW,ALSA]
2291 snd-sgalaxy= [HW,ALSA]
2293 snd-sonicvibes= [HW,ALSA]
2298 snd-sun-cs4231= [HW,ALSA]
2300 snd-trident= [HW,ALSA]
2302 snd-usb-audio= [HW,ALSA,USB]
2304 snd-via82xx= [HW,ALSA]
2306 snd-virmidi= [HW,ALSA]
2308 snd-wavefront= [HW,ALSA]
2310 snd-ymfpci= [HW,ALSA]
2313 [KNL] Should the soft-lockup detector generate panics.
2315 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2316 See Documentation/sonypi.txt
2318 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2319 See Documentation/serial/specialix.txt.
2321 spia_io_base= [HW,MTD]
2327 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2329 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2330 See Documentation/scsi/st.txt.
2333 Enabled the stack tracer on boot up.
2337 Set the STI (builtin display/keyboard on the HP-PARISC
2338 machines) console (graphic card) which should be used
2339 as the initial boot-console.
2340 See also comment in drivers/video/console/sticore.c.
2343 See comment in drivers/video/console/sticore.c.
2346 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2350 Control how the NFS server code allocates CPUs to
2351 service thread pools. Depending on how many NICs
2352 you have and where their interrupts are bound, this
2353 option will affect which CPUs will do NFS serving.
2354 Note: this parameter cannot be changed while the
2355 NFS server is running.
2357 auto the server chooses an appropriate mode
2358 automatically using heuristics
2359 global a single global pool contains all CPUs
2360 percpu one pool for each CPU
2361 pernode one pool for each NUMA node (equivalent
2362 to global on non-NUMA machines)
2364 swiotlb= [IA-64] Number of I/O TLB slabs
2368 sym53c416= [HW,SCSI]
2369 See header of drivers/scsi/sym53c416.c.
2371 sysrq_always_enabled
2373 Ignore sysrq setting - this boot parameter will
2374 neutralize any effect of /proc/sys/kernel/sysrq.
2375 Useful for debugging.
2378 See header of drivers/scsi/t128.c.
2382 test_suspend= [SUSPEND]
2383 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2384 standby suspend) as the system sleep state to briefly
2385 enter during system startup. The system is woken from
2386 this state using a wakeup-capable RTC alarm.
2388 thash_entries= [KNL,NET]
2389 Set number of hash buckets for TCP connection
2391 thermal.act= [HW,ACPI]
2392 -1: disable all active trip points in all thermal zones
2393 <degrees C>: override all lowest active trip points
2395 thermal.crt= [HW,ACPI]
2396 -1: disable all critical trip points in all thermal zones
2397 <degrees C>: override all critical trip points
2399 thermal.nocrt= [HW,ACPI]
2400 Set to disable actions on ACPI thermal zone
2401 critical and hot trip points.
2403 thermal.off= [HW,ACPI]
2404 1: disable ACPI thermal control
2406 thermal.psv= [HW,ACPI]
2407 -1: disable all passive trip points
2408 <degrees C>: override all passive trip points to this
2411 thermal.tzp= [HW,ACPI]
2412 Specify global default ACPI thermal zone polling rate
2413 <deci-seconds>: poll all this frequency
2414 0: no polling (default)
2417 See comment before function dc390_setup() in
2418 drivers/scsi/tmscsim.c.
2422 Specify if the kernel should make use of the cpu
2423 topology informations if the hardware supports these.
2424 The scheduler will make use of these informations and
2425 e.g. base its process migration decisions on it.
2430 trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
2432 trix= [HW,OSS] MediaTrix AudioTrix Pro
2434 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2436 tsc= Disable clocksource-must-verify flag for TSC.
2438 [x86] reliable: mark tsc clocksource as reliable, this
2439 disables clocksource verification at runtime.
2440 Used to enable high-resolution timer mode on older
2441 hardware, and in virtualized environment.
2443 turbografx.map[2|3]= [HW,JOY]
2444 TurboGraFX parallel port interface
2446 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2447 See also Documentation/input/joystick-parport.txt
2449 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2450 See header of drivers/scsi/u14-34f.c.
2459 [USB] Ignore overcurrent events (default N).
2460 Some badly-designed motherboards generate lots of
2461 bogus events, for ports that aren't wired to
2462 anything. Set this parameter to avoid log spamming.
2463 Note that genuine overcurrent events won't be
2468 Set unknown_nmi_panic=1 early on boot.
2470 usbcore.autosuspend=
2471 [USB] The autosuspend time delay (in seconds) used
2472 for newly-detected USB devices (default 2). This
2473 is the time required before an idle device will be
2474 autosuspended. Devices for which the delay is set
2475 to a negative value won't be autosuspended at all.
2477 usbcore.usbfs_snoop=
2478 [USB] Set to log all usbfs traffic (default 0 = off).
2480 usbcore.blinkenlights=
2481 [USB] Set to cycle leds on hubs (default 0 = off).
2483 usbcore.old_scheme_first=
2484 [USB] Start with the old device initialization
2485 scheme (default 0 = off).
2487 usbcore.use_both_schemes=
2488 [USB] Try the other device initialization scheme
2489 if the first one fails (default 1 = enabled).
2491 usbcore.initial_descriptor_timeout=
2492 [USB] Specifies timeout for the initial 64-byte
2493 USB_REQ_GET_DESCRIPTOR request in milliseconds
2494 (default 5000 = 5.0 seconds).
2497 [USBHID] The interval which mice are to be polled at.
2499 usb-storage.delay_use=
2500 [UMS] The delay in seconds before a new device is
2501 scanned for Logical Units (default 5).
2504 [UMS] A list of quirks entries to supplement or
2505 override the built-in unusual_devs list. List
2506 entries are separated by commas. Each entry has
2507 the form VID:PID:Flags where VID and PID are Vendor
2508 and Product ID values (4-digit hex numbers) and
2509 Flags is a set of characters, each corresponding
2510 to a common usb-storage quirk flag as follows:
2511 a = SANE_SENSE (collect more than 18 bytes
2513 c = FIX_CAPACITY (decrease the reported
2514 device capacity by one sector);
2515 h = CAPACITY_HEURISTICS (decrease the
2516 reported device capacity by one
2517 sector if the number is odd);
2518 i = IGNORE_DEVICE (don't bind to this
2520 l = NOT_LOCKABLE (don't try to lock and
2521 unlock ejectable media);
2522 m = MAX_SECTORS_64 (don't transfer more
2523 than 64 sectors = 32 KB at a time);
2524 o = CAPACITY_OK (accept the capacity
2525 reported by the device);
2526 r = IGNORE_RESIDUE (the device reports
2527 bogus residue values);
2528 s = SINGLE_LUN (the device has only one
2530 w = NO_WP_DETECT (don't test whether the
2531 medium is write-protected).
2532 Example: quirks=0419:aaf5:rl,0421:0433:rc
2535 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2536 vdso=1: enable VDSO (default)
2537 vdso=0: disable VDSO mapping
2540 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2541 vdso32=1: enable 32-bit VDSO (default)
2542 vdso32=0: disable 32-bit VDSO mapping
2545 vector=percpu: enable percpu vector domain
2547 video= [FB] Frame buffer configuration
2548 See Documentation/fb/modedb.txt.
2550 vga= [BOOT,X86-32] Select a particular video mode
2551 See Documentation/x86/boot.txt and
2552 Documentation/svga.txt.
2553 Use vga=ask for menu.
2554 This is actually a boot loader parameter; the value is
2555 passed to the kernel using a special protocol.
2557 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2558 size of <nn>. This can be used to increase the
2559 minimum size (128MB on x86). It can also be used to
2560 decrease the size and leave more room for directly
2563 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2566 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2569 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2572 vt.default_blu= [VT]
2573 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2574 Change the default blue palette of the console.
2575 This is a 16-member array composed of values
2578 vt.default_grn= [VT]
2579 Format: <green0>,<green1>,<green2>,...,<green15>
2580 Change the default green palette of the console.
2581 This is a 16-member array composed of values
2584 vt.default_red= [VT]
2585 Format: <red0>,<red1>,<red2>,...,<red15>
2586 Change the default red palette of the console.
2587 This is a 16-member array composed of values
2593 Set system-wide default UTF-8 mode for all tty's.
2594 Default is 1, i.e. UTF-8 mode is enabled for all
2595 newly opened terminals.
2597 waveartist= [HW,OSS]
2598 Format: <io>,<irq>,<dma>,<dma2>
2601 See header of drivers/scsi/wd33c93.c.
2604 See header of drivers/scsi/wd7000.c.
2607 See Documentation/watchdog/wdt.txt.
2609 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2610 default x2apic cluster mode on platforms
2613 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2614 xd_geo= See header of drivers/block/xd.c.
2616 xirc2ps_cs= [NET,PCMCIA]
2618 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2620 ______________________________________________________________________
2624 Add documentation for ALSA options.
2625 Add more DRM drivers.
projects / linux-2.6 / blob