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 GCOV GCOV profiling is enabled.
52 HW Appropriate hardware is enabled.
53 IA-64 IA-64 architecture is enabled.
54 IMA Integrity measurement architecture is enabled.
55 IOSCHED More than one I/O scheduler is enabled.
56 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
57 IPV6 IPv6 support is enabled.
58 ISAPNP ISA PnP code is enabled.
59 ISDN Appropriate ISDN support is enabled.
60 JOY Appropriate joystick support is enabled.
61 KVM Kernel Virtual Machine support is enabled.
62 LIBATA Libata driver is enabled
63 LP Printer support is enabled.
64 LOOP Loopback device support is enabled.
65 M68k M68k architecture is enabled.
66 These options have more detailed description inside of
67 Documentation/m68k/kernel-options.txt.
68 MCA MCA bus support is enabled.
69 MDA MDA console support is enabled.
70 MOUSE Appropriate mouse support is enabled.
71 MSI Message Signaled Interrupts (PCI).
72 MTD MTD (Memory Technology Device) support is enabled.
73 NET Appropriate network support is enabled.
74 NUMA NUMA support is enabled.
75 GENERIC_TIME The generic timeofday code is enabled.
76 NFS Appropriate NFS support is enabled.
77 OSS OSS sound support is enabled.
78 PV_OPS A paravirtualized kernel is enabled.
79 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
80 PARISC The PA-RISC architecture is enabled.
81 PCI PCI bus support is enabled.
82 PCIE PCI Express support is enabled.
83 PCMCIA The PCMCIA subsystem is enabled.
84 PNP Plug & Play support is enabled.
85 PPC PowerPC architecture is enabled.
86 PPT Parallel port support is enabled.
87 PS2 Appropriate PS/2 support is enabled.
88 RAM RAM disk support is enabled.
89 S390 S390 architecture is enabled.
90 SCSI Appropriate SCSI support is enabled.
91 A lot of drivers has their options described inside of
93 SECURITY Different security models are enabled.
94 SELINUX SELinux support is enabled.
95 SERIAL Serial support is enabled.
96 SH SuperH architecture is enabled.
97 SMP The kernel is an SMP kernel.
98 SPARC Sparc architecture is enabled.
99 SWSUSP Software suspend (hibernation) is enabled.
100 SUSPEND System suspend states are enabled.
101 FTRACE Function tracing enabled.
102 TS Appropriate touchscreen support is enabled.
103 UMS USB Mass Storage support is enabled.
104 USB USB support is enabled.
105 USBHID USB Human Interface Device support is enabled.
106 V4L Video For Linux support is enabled.
107 VGA The VGA console has been enabled.
108 VT Virtual terminal support is enabled.
109 WDT Watchdog support is enabled.
110 XT IBM PC/XT MFM hard disk support is enabled.
111 X86-32 X86-32, aka i386 architecture is enabled.
112 X86-64 X86-64 architecture is enabled.
113 More X86-64 boot options can be found in
114 Documentation/x86/x86_64/boot-options.txt .
115 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
117 In addition, the following text indicates that the option:
119 BUGS= Relates to possible processor bugs on the said processor.
120 KNL Is a kernel start-up parameter.
121 BOOT Is a boot loader parameter.
123 Parameters denoted with BOOT are actually interpreted by the boot
124 loader, and have no meaning to the kernel directly.
125 Do not modify the syntax of boot loader parameters without extreme
126 need or coordination with <Documentation/x86/boot.txt>.
128 There are also arch-specific kernel-parameters not documented here.
129 See for example <Documentation/x86/x86_64/boot-options.txt>.
131 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
132 a trailing = on the name of any parameter states that that parameter will
133 be entered as an environment variable, whereas its absence indicates that
134 it will appear as a kernel argument readable via /proc/cmdline by programs
135 running once the system is up.
137 The number of kernel parameters is not limited, but the length of the
138 complete command line (parameters including spaces etc.) is limited to
139 a fixed number of characters. This limit depends on the architecture
140 and is between 256 and 4096 characters. It is defined in the file
141 ./include/asm/setup.h as COMMAND_LINE_SIZE.
145 Advanced Configuration and Power Interface
146 Format: { force | off | ht | strict | noirq | rsdt }
147 force -- enable ACPI if default was off
148 off -- disable ACPI if default was on
149 noirq -- do not use ACPI for IRQ routing
150 ht -- run only enough ACPI to enable Hyper Threading
151 strict -- Be less tolerant of platforms that are not
152 strictly ACPI specification compliant.
153 rsdt -- prefer RSDT over (default) XSDT
155 See also Documentation/power/pm.txt, pci=noacpi
157 acpi_apic_instance= [ACPI, IOAPIC]
159 2: use 2nd APIC table, if available
160 1,0: use 1st APIC table
163 acpi_backlight= [HW,ACPI]
164 acpi_backlight=vendor
166 If set to vendor, prefer vendor specific driver
167 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
168 of the ACPI video.ko driver.
170 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
171 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
173 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
174 debug output. Bits in debug_layer correspond to a
175 _COMPONENT in an ACPI source file, e.g.,
176 #define _COMPONENT ACPI_PCI_COMPONENT
177 Bits in debug_level correspond to a level in
178 ACPI_DEBUG_PRINT statements, e.g.,
179 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
180 The debug_level mask defaults to "info". See
181 Documentation/acpi/debug.txt for more information about
182 debug layers and levels.
184 Enable processor driver info messages:
185 acpi.debug_layer=0x20000000
186 Enable PCI/PCI interrupt routing info messages:
187 acpi.debug_layer=0x400000
188 Enable AML "Debug" output, i.e., stores to the Debug
189 object while interpreting AML:
190 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
191 Enable all messages related to ACPI hardware:
192 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
194 Some values produce so much output that the system is
195 unusable. The "log_buf_len" parameter may be useful
196 if you need to capture more output.
198 acpi_display_output= [HW,ACPI]
199 acpi_display_output=vendor
200 acpi_display_output=video
203 acpi_irq_balance [HW,ACPI]
204 ACPI will balance active IRQs
207 acpi_irq_nobalance [HW,ACPI]
208 ACPI will not move active IRQs (default)
211 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
212 Format: <irq>,<irq>...
214 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
216 Format: <irq>,<irq>...
218 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
220 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
221 Format: To spoof as Windows 98: ="Microsoft Windows"
223 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
224 acpi_osi="string1" # add string1 -- only one string
225 acpi_osi="!string2" # remove built-in string2
226 acpi_osi= # disable all strings
229 Override the pmtimer bug detection: force the kernel
230 to assume that this machine's pmtimer latches its value
231 and always returns good values.
233 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
234 Format: { level | edge | high | low }
236 acpi_serialize [HW,ACPI] force serialization of AML methods
238 acpi_skip_timer_override [HW,ACPI]
239 Recognize and ignore IRQ0/pin2 Interrupt Override.
240 For broken nForce2 BIOS resulting in XT-PIC timer.
242 acpi_sleep= [HW,ACPI] Sleep options
243 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
244 old_ordering, s4_nonvs, sci_force_enable }
245 See Documentation/power/video.txt for information on
247 s3_beep is for debugging; it makes the PC's speaker beep
248 as soon as the kernel's real-mode entry point is called.
249 s4_nohwsig prevents ACPI hardware signature from being
250 used during resume from hibernation.
251 old_ordering causes the ACPI 1.0 ordering of the _PTS
252 control method, with respect to putting devices into
253 low power states, to be enforced (the ACPI 2.0 ordering
254 of _PTS is used by default).
255 s4_nonvs prevents the kernel from saving/restoring the
256 ACPI NVS memory during hibernation.
257 sci_force_enable causes the kernel to set SCI_EN directly
258 on resume from S1/S3 (which is against the ACPI spec,
259 but some broken systems don't work without it).
261 acpi_use_timer_override [HW,ACPI]
262 Use timer override. For some broken Nvidia NF5 boards
263 that require a timer override, but don't have HPET
265 acpi_enforce_resources= [ACPI]
266 { strict | lax | no }
267 Check for resource conflicts between native drivers
268 and ACPI OperationRegions (SystemIO and SystemMemory
269 only). IO ports and memory declared in ACPI might be
270 used by the ACPI subsystem in arbitrary AML code and
271 can interfere with legacy drivers.
272 strict (default): access to resources claimed by ACPI
273 is denied; legacy drivers trying to access reserved
274 resources will fail to bind to device using them.
275 lax: access to resources claimed by ACPI is allowed;
276 legacy drivers trying to access reserved resources
277 will bind successfully but a warning message is logged.
278 no: ACPI OperationRegions are not marked as reserved,
279 no further checks are performed.
282 Format: <io>,<irq>,<dma>,<dma2>,<type>
284 add_efi_memmap [EFI; X86] Include EFI memory map in
285 kernel's map of available physical RAM.
288 See header of drivers/scsi/advansys.c.
290 advwdt= [HW,WDT] Advantech WDT
291 Format: <iostart>,<iostop>
293 aedsp16= [HW,OSS] Audio Excel DSP 16
294 Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
295 See also header of sound/oss/aedsp16.c.
298 { off | try_unsupported }
299 off: disable AGP support
300 try_unsupported: try to drive unsupported chipsets
301 (may crash computer or cause data corruption)
304 See Documentation/scsi/aha152x.txt.
307 Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
310 See Documentation/scsi/aic7xxx.txt.
313 See Documentation/scsi/aic79xx.txt.
316 Allow the default userspace alignment fault handler
317 behaviour to be specified. Bit 0 enables warnings,
318 bit 1 enables fixups, and bit 2 sends a segfault.
320 amd_iommu= [HW,X86-84]
321 Pass parameters to the AMD IOMMU driver in the system.
323 fullflush - enable flushing of IO/TLB entries when
324 they are unmapped. Otherwise they are
325 flushed before they will be reused, which
327 off - do not initialize any AMD IOMMU found in
330 amijoy.map= [HW,JOY] Amiga joystick support
331 Map of devices attached to JOY0DAT and JOY1DAT
333 See also Documentation/kernel/input/joystick.txt
335 analog.map= [HW,JOY] Analog joystick and gamepad support
336 Specifies type or capabilities of an analog joystick
337 connected to one of 16 gameports
338 Format: <type1>,<type2>,..<type16>
341 Power management functions (SPARCstation-4/5 + deriv.)
343 Disable APC CPU standby support. SPARCstation-Fox does
344 not play well with APC CPU idle - disable it if you have
345 APC and your system crashes randomly.
347 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
348 Change the output verbosity whilst booting
349 Format: { quiet (default) | verbose | debug }
350 Change the amount of debugging information output
351 when initialising the APIC and IO-APIC components.
354 See Documentation/networking/ipv6.txt.
356 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
357 Limit apic dumping. The parameter defines the maximal
358 number of local apics being dumped. Also it is possible
359 to set it to "all" by meaning -- no limit here.
360 Format: { 1 (default) | 2 | ... | all }.
361 The parameter valid if only apic=debug or
362 apic=verbose is specified.
363 Example: apic=debug show_lapic=all
365 apm= [APM] Advanced Power Management
366 See header of arch/x86/kernel/apm_32.c.
368 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
369 Format: <io>,<irq>,<nodeID>
373 atarimouse= [HW,MOUSE] Atari Mouse
375 atascsi= [HW,SCSI] Atari SCSI
377 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
378 EzKey and similar keyboards
380 atkbd.reset= [HW] Reset keyboard during initialization
382 atkbd.set= [HW] Select keyboard code set
383 Format: <int> (2 = AT (default), 3 = PS/2)
385 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
388 atkbd.softraw= [HW] Choose between synthetic and real raw mode
389 Format: <bool> (0 = real, 1 = synthetic (default))
391 atkbd.softrepeat= [HW]
392 Use software keyboard repeat
396 baycom_epp= [HW,AX25]
399 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
401 See header of drivers/net/hamradio/baycom_par.c.
403 baycom_ser_fdx= [HW,AX25]
404 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
405 Format: <io>,<irq>,<mode>[,<baud>]
406 See header of drivers/net/hamradio/baycom_ser_fdx.c.
408 baycom_ser_hdx= [HW,AX25]
409 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
410 Format: <io>,<irq>,<mode>
411 See header of drivers/net/hamradio/baycom_ser_hdx.c.
413 boot_delay= Milliseconds to delay each printk during boot.
414 Values larger than 10 seconds (10000) are changed to
418 bootmem_debug [KNL] Enable bootmem allocator debug messages.
420 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
421 bttv.radio= Most important insmod options are available as
423 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
424 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
427 See drivers/scsi/BusLogic.c, comment before function
428 BusLogic_ParseDriverOptions().
430 c101= [NET] Moxa C101 synchronous serial card
432 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
433 Sometimes CPU hardware bugs make them report the cache
434 size incorrectly. The kernel will attempt work arounds
435 to fix known problems, but for some CPUs it is not
436 possible to determine what the correct size should be.
437 This option provides an override for these situations.
440 [SECURITY] Disable capabilities. This would normally
441 be used only if an alternative security model is to be
442 configured. Potentially dangerous and should only be
443 used if you are entirely sure of the consequences.
445 ccw_timeout_log [S390]
446 See Documentation/s390/CommonIO for details.
448 cgroup_disable= [KNL] Disable a particular controller
449 Format: {name of the controller(s) to disable}
450 {Currently supported controllers - "memory"}
452 checkreqprot [SELINUX] Set initial checkreqprot flag value.
453 Format: { "0" | "1" }
454 See security/selinux/Kconfig help text.
455 0 -- check protection applied by kernel (includes
456 any implied execute protection).
457 1 -- check protection requested by application.
458 Default value is set via a kernel config option.
459 Value can be changed at runtime via
460 /selinux/checkreqprot.
463 See Documentation/s390/CommonIO for details.
465 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
467 Forces specified clocksource (if available) to be used
468 when calculating gettimeofday(). If specified
469 clocksource is not available, it defaults to PIT.
470 Format: { pit | tsc | cyclone | pmtmr }
472 clocksource= [GENERIC_TIME] Override the default clocksource
474 Override the default clocksource and use the clocksource
475 with the name specified.
476 Some clocksource names to choose from, depending on
478 [all] jiffies (this is the base, fallback clocksource)
480 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
481 pxa_timer,timer3,32k_counter,timer0_1
483 [X86-32] pit,hpet,tsc,vmi-timer;
484 scx200_hrt on Geode; cyclone on IBM x440
492 clearcpuid=BITNUM [X86]
493 Disable CPUID feature X for the kernel. See
494 arch/x86/include/asm/cpufeature.h for the valid bit
495 numbers. Note the Linux specific bits are not necessarily
496 stable over kernel options, but the vendor specific
498 Also note that user programs calling CPUID directly
499 or using the feature without checking anything
500 will still see it. This just prevents it from
501 being used by the kernel or shown in /proc/cpuinfo.
502 Also note the kernel might malfunction if you disable
505 cmo_free_hint= [PPC] Format: { yes | no }
506 Specify whether pages are marked as being inactive
507 when they are freed. This is used in CMO environments
508 to determine OS memory pressure for page stealing by
512 code_bytes [X86] How many bytes of object code to print
517 com20020= [HW,NET] ARCnet - COM20020 chipset
519 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
521 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
525 ARCnet - COM90xx chipset (memory-mapped buffers)
526 Format: <io>[,<irq>[,<memstart>]]
528 condev= [HW,S390] console device
531 console= [KNL] Output console device and options.
533 tty<n> Use the virtual console device <n>.
537 Use the specified serial port. The options are of
538 the form "bbbbpnf", where "bbbb" is the baud rate,
539 "p" is parity ("n", "o", or "e"), "n" is number of
540 bits, and "f" is flow control ("r" for RTS or
541 omit it). Default is "9600n8".
543 See Documentation/serial-console.txt for more
545 Documentation/networking/netconsole.txt for an
548 uart[8250],io,<addr>[,options]
549 uart[8250],mmio,<addr>[,options]
550 Start an early, polled-mode console on the 8250/16550
551 UART at the specified I/O port or MMIO address,
552 switching to the matching ttyS device later. The
553 options are the same as for ttyS, above.
555 If the device connected to the port is not a TTY but a braille
556 device, prepend "brl," before the device type, for instance
558 For now, only VisioBraille is supported.
560 consoleblank= [KNL] The console blank (screen saver) timeout in
561 seconds. Defaults to 10*60 = 10mins. A value of 0
562 disables the blank timer.
565 [KNL] Change the default value for
566 /proc/<pid>/coredump_filter.
567 See also Documentation/filesystems/proc.txt.
569 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
571 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
573 crashkernel=nn[KMG]@ss[KMG]
574 [KNL] Reserve a chunk of physical memory to
575 hold a kernel to switch to with kexec on panic.
577 crashkernel=range1:size1[,range2:size2,...][@offset]
578 [KNL] Same as above, but depends on the memory
579 in the running system. The syntax of range is
580 start-[end] where start and end are both
581 a memory unit (amount[KMG]). See also
582 Documentation/kdump/kdump.txt for a example.
587 cs89x0_media= [HW,NET]
588 Format: { rj45 | aui | bnc }
591 See header of drivers/s390/block/dasd_devmap.c.
593 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
594 (one device per port)
595 Format: <port#>,<type>
596 See also Documentation/input/joystick-parport.txt
598 debug [KNL] Enable kernel debugging (events log level).
601 [KNL] verbose self-tests
603 Print debugging info while doing the locking API
605 We default to 0 (no extra messages), setting it to
606 1 will print _a lot_ more information - normally
607 only useful to kernel developers.
609 debug_objects [KNL] Enable object debugging
612 [KNL] Disable object debugging
614 debugpat [X86] Enable PAT debugging
616 decnet.addr= [HW,NET]
617 Format: <area>[,<node>]
618 See also Documentation/networking/decnet.txt.
621 [same as hugepagesz=] The size of the default
622 HugeTLB page size. This is the size represented by
623 the legacy /proc/ hugepages APIs, used for SHM, and
624 default size when mounting hugetlbfs filesystems.
625 Defaults to the default architecture's huge page size
629 Set number of hash buckets for dentry cache.
632 IO parameters + enable/disable command.
634 digiepca= [HW,SERIAL]
635 See drivers/char/README.epca and
636 Documentation/serial/digiepca.txt.
639 See Documentation/networking/ipv6.txt.
642 See Documentation/networking/ipv6.txt.
644 disable_mtrr_cleanup [X86]
645 The kernel tries to adjust MTRR layout from continuous
646 to discrete, to make X server driver able to add WB
647 entry later. This parameter disables that.
649 disable_mtrr_trim [X86, Intel and AMD only]
650 By default the kernel will trim any uncacheable
651 memory out of your available memory pool based on
652 MTRR settings. This parameter disables that behavior,
653 possibly causing your machine to run very slowly.
655 disable_timer_pin_1 [X86]
656 Disable PIN 1 of APIC timer
657 Can be useful to work around chipset bugs.
659 dmasound= [HW,OSS] Sound subsystem buffers
661 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
662 this option disables the debugging code at boot.
664 dma_debug_entries=<number>
665 This option allows to tune the number of preallocated
666 entries for DMA-API debugging code. One entry is
667 required per DMA-API allocation. Use this if the
668 DMA-API debugging code disables itself because the
669 architectural default is too low.
671 dma_debug_driver=<driver_name>
672 With this option the DMA-API debugging driver
673 filter feature can be enabled at boot time. Just
674 pass the driver to filter for as the parameter.
675 The filter can be disabled or changed to another
676 driver later using sysfs.
682 dynamic_printk Enables pr_debug()/dev_dbg() calls if
683 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
684 These can also be switched on/off via
685 <debugfs>/dynamic_printk/modules
687 earlycon= [KNL] Output early console device and options.
688 uart[8250],io,<addr>[,options]
689 uart[8250],mmio,<addr>[,options]
690 Start an early, polled-mode console on the 8250/16550
691 UART at the specified I/O port or MMIO address.
692 The options are the same as for ttyS, above.
694 earlyprintk= [X86,SH,BLACKFIN]
696 earlyprintk=serial[,ttySn[,baudrate]]
697 earlyprintk=ttySn[,baudrate]
698 earlyprintk=dbgp[debugController#]
700 Append ",keep" to not disable it when the real console
703 Only vga or serial or usb debug port at a time.
705 Currently only ttyS0 and ttyS1 are supported.
707 Interaction with the standard serial driver is not
710 The VGA output is eventually overwritten by the real
716 Format: {"off" | "on" | "skip[mbr]"}
718 eisa_irq_edge= [PARISC,HW]
719 See header of drivers/parisc/eisa.c.
722 See comment before function elanfreq_setup() in
723 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
726 Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
727 See Documentation/block/as-iosched.txt and
728 Documentation/block/deadline-iosched.txt for details.
730 elfcorehdr= [IA64,PPC,SH,X86]
731 Specifies physical address of start of kernel core
732 image elf header. Generally kexec loader will
733 pass this option to capture kernel.
734 See Documentation/kdump/kdump.txt for details.
736 enable_mtrr_cleanup [X86]
737 The kernel tries to adjust MTRR layout from continuous
738 to discrete, to make X server driver able to add WB
739 entry later. This parameter enables that.
741 enable_timer_pin_1 [X86]
742 Enable PIN 1 of APIC timer
743 Can be useful to work around chipset bugs
744 (in particular on some ATI chipsets).
745 The kernel tries to set a reasonable default.
747 enforcing [SELINUX] Set initial enforcing status.
749 See security/selinux/Kconfig help text.
750 0 -- permissive (log only, no denials).
751 1 -- enforcing (deny and log).
753 Value can be changed at runtime via /selinux/enforce.
755 ether= [HW,NET] Ethernet cards parameters
756 This option is obsoleted by the "netdev=" option, which
757 has equivalent usage. See its documentation for details.
759 eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
764 fail_make_request=[KNL]
765 General fault injection mechanism.
766 Format: <interval>,<probability>,<space>,<times>
767 See also /Documentation/fault-injection/.
770 See header of drivers/scsi/fd_mcs.c.
773 See header of drivers/scsi/fdomain.c.
776 See Documentation/blockdev/floppy.txt.
778 force_pal_cache_flush
779 [IA-64] Avoid check_sal_cache_flush which may hang on
780 buggy SAL_CACHE_FLUSH implementations. Using this
781 parameter will force ia64_sal_cache_flush to call
782 ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
785 [FTRACE] will set and start the specified tracer
786 as early as possible in order to facilitate early
790 [FTRACE] will dump the trace buffers on oops.
792 ftrace_filter=[function-list]
793 [FTRACE] Limit the functions traced by the function
794 tracer at boot up. function-list is a comma separated
795 list of functions. This list can be changed at run
796 time by the set_ftrace_filter file in the debugfs
799 ftrace_notrace=[function-list]
800 [FTRACE] Do not trace the functions specified in
801 function-list. This list can be changed at run time
802 by the set_ftrace_notrace file in the debugfs
805 ftrace_graph_filter=[function-list]
806 [FTRACE] Limit the top level callers functions traced
807 by the function graph tracer at boot up.
808 function-list is a comma separated list of functions
809 that can be changed at run time by the
810 set_graph_function file in the debugfs tracing directory.
813 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
814 support via parallel port (up to 5 devices per port)
815 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
816 See also Documentation/input/joystick-parport.txt
820 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
824 gcov_persist= [GCOV] When non-zero (default), profiling data for
825 kernel modules is saved and remains accessible via
826 debugfs, even when the module is unloaded/reloaded.
827 When zero, profiling data is discarded and associated
828 debugfs files are removed at module unload time.
831 See header of drivers/scsi/gdth.c.
833 gpt [EFI] Forces disk with valid GPT signature but
834 invalid Protective MBR to be treated as GPT.
838 hashdist= [KNL,NUMA] Large hashes allocated during boot
839 are distributed across NUMA nodes. Defaults on
840 for 64bit NUMA, off otherwise.
841 Format: 0 | 1 (for off | on)
843 hcl= [IA-64] SGI's Hardware Graph compatibility layer
845 hd= [EIDE] (E)IDE hard drive subsystem geometry
846 Format: <cyl>,<head>,<sect>
848 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
849 size of <nn>. This works even on boxes that have no
850 highmem otherwise. This also works to reduce highmem
851 size on bigger boxes.
853 highres= [KNL] Enable/disable high resolution timer mode.
854 Valid parameters: "on", "off"
858 See Documentation/isdn/README.HiSax.
862 hpet= [X86-32,HPET] option to control HPET usage
863 Format: { enable (default) | disable | force |
865 disable: disable HPET and use PIT instead
866 force: allow force enabled of undocumented chips (ICH4,
868 verbose: show contents of HPET registers during setup
870 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
871 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
872 On x86-64 and powerpc, this option can be specified
873 multiple times interleaved with hugepages= to reserve
874 huge pages of different sizes. Valid pages sizes on
875 x86-64 are 2M (when the CPU supports "pse") and 1G
876 (when the CPU supports the "pdpe1gb" cpuinfo flag)
877 Note that 1GB pages can only be allocated at boot time
878 using hugepages= and not freed afterwards.
880 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
881 terminal devices. Valid values: 0..8
882 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
883 If specified, z/VM IUCV HVC accepts connections
884 from listed z/VM user IDs only.
886 i2c_bus= [HW] Override the default board specific I2C bus speed
887 or register an additional I2C bus that is not
888 registered from board initialization code.
892 i8042.debug [HW] Toggle i8042 debug mode
893 i8042.direct [HW] Put keyboard port into non-translated mode
894 i8042.dumbkbd [HW] Pretend that controller can only read data from
895 keyboard and cannot control its state
896 (Don't attempt to blink the leds)
897 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
898 i8042.nokbd [HW] Don't check/create keyboard port
899 i8042.noloop [HW] Disable the AUX Loopback command while probing
901 i8042.nomux [HW] Don't check presence of an active multiplexing
903 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
906 [HW] Frequency with which keyboard LEDs should blink
907 when kernel panics (default is 0.5 sec)
908 i8042.reset [HW] Reset the controller during init and cleanup
909 i8042.unlock [HW] Unlock (ignore) the keylock
913 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
914 indicates that the driver is running on unsupported
916 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
917 does not match list of supported models.
919 [HW] Report power status in /proc/i8k
920 (disabled by default)
921 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
924 ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
925 See Documentation/mca.txt.
928 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
930 ide-core.nodma= [HW] (E)IDE subsystem
931 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
932 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
933 .cdrom .chs .ignore_cable are additional options
934 See Documentation/ide/ide.txt.
936 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
937 Claim all unknown PCI IDE storage controllers.
940 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
941 Poll forces a polling idle loop that can slightly
942 improve the performance of waking up a idle CPU, but
943 will use a lot of power and make the system run hot.
945 idle=mwait: On systems which support MONITOR/MWAIT but
946 the kernel chose to not use it because it doesn't save
947 as much power as a normal idle loop, use the
948 MONITOR/MWAIT idle loop anyways. Performance should be
949 the same as idle=poll.
950 idle=halt: Halt is forced to be used for CPU idle.
951 In such case C2/C3 won't be used again.
952 idle=nomwait: Disable mwait for CPU C-states
954 ignore_loglevel [KNL]
955 Ignore loglevel setting - this will print /all/
956 kernel messages to the console. Useful for debugging.
959 Set number of hash buckets for inode cache.
962 Format: { "0" | "1" }
963 0 -- integrity auditing messages. (Default)
964 1 -- enable informational integrity auditing messages.
967 Format: { "sha1" | "md5" }
971 Load a policy which meets the needs of the Trusted
972 Computing Base. This means IMA will measure all
973 programs exec'd, files mmap'd for exec, and all files
974 opened for read by uid=0.
977 See header of drivers/scsi/in2000.c.
981 Run specified binary instead of /sbin/init as init
984 initcall_debug [KNL] Trace initcalls as they are executed. Useful
985 for working out where the kernel is dying during
988 initrd= [BOOT] Specify the location of the initial ramdisk
990 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
993 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
995 Enable intel iommu driver.
997 Disable intel iommu driver.
998 igfx_off [Default Off]
999 By default, gfx is mapped as normal device. If a gfx
1000 device has a dedicated DMAR unit, the DMAR unit is
1001 bypassed by not enabling DMAR with this option. In
1002 this case, gfx device will use physical address for
1005 With this option iommu will not optimize to look
1006 for io virtual address below 32 bit forcing dual
1007 address cycle on pci bus for cards supporting greater
1008 than 32 bit addressing. The default is to look
1009 for translation below 32 bit and if not available
1010 then look in the higher range.
1011 strict [Default Off]
1012 With this option on every unmap_single operation will
1013 result in a hardware IOTLB flush operation as opposed
1014 to batching them for performance.
1018 iomem= Disable strict checking of access to MMIO memory
1019 strict regions from userspace.
1035 io7= [HW] IO7 for Marvel based alpha systems
1036 See comment before marvel_specify_io7 in
1037 arch/alpha/kernel/core_marvel.c.
1039 io_delay= [X86] I/O delay method
1041 Standard port 0x80 based delay
1043 Alternate port 0xed based delay (needed on some systems)
1045 Simple two microseconds delay
1050 See Documentation/filesystems/nfs/nfsroot.txt.
1052 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1053 See comment before ip2_setup() in
1054 drivers/char/ip2/ip2base.c.
1056 ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
1057 See header of drivers/scsi/ips.c.
1060 When an interrupt is not handled search all handlers
1061 for it. Intended to get systems with badly broken
1065 When an interrupt is not handled search all handlers
1066 for it. Also check all handlers each timer
1067 interrupt. Intended to get systems with badly broken
1071 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1073 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1075 <cpu number>,...,<cpu number>
1077 <cpu number>-<cpu number>
1078 (must be a positive range in ascending order)
1080 <cpu number>,...,<cpu number>-<cpu number>
1082 This option can be used to specify one or more CPUs
1083 to isolate from the general SMP balancing and scheduling
1084 algorithms. You can move a process onto or off an
1085 "isolated" CPU via the CPU affinity syscalls or cpuset.
1086 <cpu number> begins at 0 and the maximum value is
1087 "number of CPUs in system - 1".
1089 This option is the preferred way to isolate CPUs. The
1090 alternative -- manually setting the CPU mask of all
1091 tasks in the system -- can cause problems and
1092 suboptimal load balancer performance.
1096 js= [HW,JOY] Analog joystick
1097 See Documentation/input/joystick.txt.
1101 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1102 specifies the amount of memory usable by the kernel
1103 for non-movable allocations. The requested amount is
1104 spread evenly throughout all nodes in the system. The
1105 remaining memory in each node is used for Movable
1106 pages. In the event, a node is too small to have both
1107 kernelcore and Movable pages, kernelcore pages will
1108 take priority and other nodes will have a larger number
1109 of kernelcore pages. The Movable zone is used for the
1110 allocation of pages that may be reclaimed or moved
1111 by the page migration subsystem. This means that
1112 HugeTLB pages may not be allocated from this zone.
1113 Note that allocations like PTEs-from-HighMem still
1114 use the HighMem zone if it exists, and the Normal
1115 zone if it does not.
1117 kgdboc= [HW] kgdb over consoles.
1118 Requires a tty driver that supports console polling.
1119 (only serial supported for now)
1120 Format: <serial_device>[,baud]
1122 kmac= [MIPS] korina ethernet MAC address.
1123 Configure the RouterBoard 532 series on-chip
1124 Ethernet adapter MAC address.
1126 kmemleak= [KNL] Boot-time kmemleak enable/disable
1127 Valid arguments: on, off
1130 kstack=N [X86] Print N words from the kernel stack
1133 kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
1134 Default is 0 (don't ignore, but inject #GP)
1136 kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
1137 Default is 1 (enabled)
1139 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1142 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1144 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1146 kvm-intel.bypass_guest_pf=
1147 [KVM,Intel] Disables bypassing of guest page faults
1148 on Intel chips. Default is 1 (enabled)
1150 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1151 (virtualized MMU) support on capable Intel chips.
1152 Default is 1 (enabled)
1154 kvm-intel.emulate_invalid_guest_state=
1155 [KVM,Intel] Enable emulation of invalid guest states
1156 Default is 0 (disabled)
1158 kvm-intel.flexpriority=
1159 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1160 Default is 1 (enabled)
1162 kvm-intel.unrestricted_guest=
1163 [KVM,Intel] Disable unrestricted guest feature
1164 (virtualized real and unpaged mode) on capable
1165 Intel chips. Default is 1 (enabled)
1167 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1168 feature (tagged TLBs) on capable Intel chips.
1169 Default is 1 (enabled)
1175 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1178 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1181 libata.dma= [LIBATA] DMA control
1182 libata.dma=0 Disable all PATA and SATA DMA
1183 libata.dma=1 PATA and SATA Disk DMA only
1184 libata.dma=2 ATAPI (CDROM) DMA only
1185 libata.dma=4 Compact Flash DMA only
1186 Combinations also work, so libata.dma=3 enables DMA
1187 for disks and CDROMs, but not CFs.
1189 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1190 libata.ignore_hpa=0 keep BIOS limits (default)
1191 libata.ignore_hpa=1 ignore limits, using full disk
1193 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1197 libata.force= [LIBATA] Force configurations. The format is comma
1198 separated list of "[ID:]VAL" where ID is
1199 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1200 matching port, link or device. Basically, it matches
1201 the ATA ID string printed on console by libata. If
1202 the whole ID part is omitted, the last PORT and DEVICE
1203 values are used. If ID hasn't been specified yet, the
1204 configuration applies to all ports, links and devices.
1206 If only DEVICE is omitted, the parameter applies to
1207 the port and all links and devices behind it. DEVICE
1208 number of 0 either selects the first device or the
1209 first fan-out link behind PMP device. It does not
1210 select the host link. DEVICE number of 15 selects the
1211 host link and device attached to it.
1213 The VAL specifies the configuration to force. As long
1214 as there's no ambiguity shortcut notation is allowed.
1215 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1216 The following configurations can be forced.
1218 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1219 Any ID with matching PORT is used.
1221 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1223 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1224 udma[/][16,25,33,44,66,100,133] notation is also
1227 * [no]ncq: Turn on or off NCQ.
1229 * nohrst, nosrst, norst: suppress hard, soft
1232 If there are multiple matching configurations changing
1233 the same attribute, the last one is used.
1235 lmb=debug [KNL] Enable lmb debug messages.
1237 load_ramdisk= [RAM] List of ramdisks to load from floppy
1238 See Documentation/blockdev/ramdisk.txt.
1240 lockd.nlm_grace_period=P [NFS] Assign grace period.
1243 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1246 lockd.nlm_timeout=T [NFS] Assign timeout value.
1249 lockd.nlm_udpport=M [NFS] Assign UDP port.
1252 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1255 loglevel= All Kernel Messages with a loglevel smaller than the
1256 console loglevel will be printed to the console. It can
1257 also be changed with klogd or other programs. The
1258 loglevels are defined as follows:
1260 0 (KERN_EMERG) system is unusable
1261 1 (KERN_ALERT) action must be taken immediately
1262 2 (KERN_CRIT) critical conditions
1263 3 (KERN_ERR) error conditions
1264 4 (KERN_WARNING) warning conditions
1265 5 (KERN_NOTICE) normal but significant condition
1266 6 (KERN_INFO) informational
1267 7 (KERN_DEBUG) debug-level messages
1269 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1270 Format: { n | nk | nM }
1271 n must be a power of two. The default size
1272 is set in the kernel config file.
1274 logo.nologo [FB] Disables display of the built-in Linux logo.
1275 This may be used to provide more screen space for
1276 kernel log messages and is useful when debugging
1277 kernel boot problems.
1279 lp=0 [LP] Specify parallel ports to use, e.g,
1280 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1281 lp=reset first parallel port). 'lp=0' disables the
1282 lp=auto printer driver. 'lp=reset' (which can be
1283 specified in addition to the ports) causes
1284 attached printers to be reset. Using
1285 lp=port1,port2,... specifies the parallel ports
1286 to associate lp devices with, starting with
1287 lp0. A port specification may be 'none' to skip
1288 that lp device, or a parport name such as
1289 'parport0'. Specifying 'lp=auto' instead of a
1290 port specification list means that device IDs
1291 from each port should be examined, to see if
1292 an IEEE 1284-compliant printer is attached; if
1293 so, the driver will manage that printer.
1294 See also header of drivers/char/lp.c.
1297 Sets loops_per_jiffy to given constant, thus avoiding
1298 time-consuming boot-time autodetection (up to 250 ms per
1299 CPU). 0 enables autodetection (default). To determine
1300 the correct value for your kernel, boot with normal
1301 autodetection and see what value is printed. Note that
1302 on SMP systems the preset will be applied to all CPUs,
1303 which is likely to cause problems if your CPUs need
1304 significantly divergent settings. An incorrect value
1305 will cause delays in the kernel to be wrong, leading to
1306 unpredictable I/O errors and other breakage. Although
1307 unlikely, in the extreme case this might damage your
1311 Format: <io>,<irq>,<dma>
1313 mac5380= [HW,SCSI] Format:
1314 <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
1316 machvec= [IA64] Force the use of a particular machine-vector
1317 (machvec) in a generic kernel.
1318 Example: machvec=hpzx1_swiotlb
1320 machtype= [Loongson] Share the same kernel image file between different
1322 Example: machtype=lemote-yeeloong-2f-7inch
1324 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1325 than or equal to this physical address is ignored.
1327 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1328 should make use of. maxcpus=n : n >= 0 limits the
1329 kernel to using 'n' processors. n=0 is a special case,
1330 it is equivalent to "nosmp", which also disables
1333 max_loop= [LOOP] Maximum number of loopback devices that can
1337 max_luns= [SCSI] Maximum number of LUNs to probe.
1338 Should be between 1 and 2^32-1.
1341 [SCSI] Maximum number of LUNs received.
1342 Should be between 1 and 16384.
1346 mce [X86-32] Machine Check Exception
1348 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1350 md= [HW] RAID subsystems devices and level
1351 See Documentation/md.txt.
1354 Format: <first>,<last>
1355 Specifies range of consoles to be captured by the MDA.
1357 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1358 Amount of memory to be used when the kernel is not able
1359 to see the whole system memory or for test.
1360 [X86-32] Use together with memmap= to avoid physical
1361 address space collisions. Without memmap= PCI devices
1362 could be placed at addresses belonging to unused RAM.
1364 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1368 [KNL,SH] Allow user to override the default size for
1369 per-device physically contiguous DMA buffers.
1371 memmap=exactmap [KNL,X86] Enable setting of an exact
1372 E820 memory map, as specified by the user.
1373 Such memmap=exactmap lines can be constructed based on
1374 BIOS output or other requirements. See the memmap=nn@ss
1377 memmap=nn[KMG]@ss[KMG]
1378 [KNL] Force usage of a specific region of memory
1379 Region of memory to be used, from ss to ss+nn.
1381 memmap=nn[KMG]#ss[KMG]
1382 [KNL,ACPI] Mark specific memory as ACPI data.
1383 Region of memory to be used, from ss to ss+nn.
1385 memmap=nn[KMG]$ss[KMG]
1386 [KNL,ACPI] Mark specific memory as reserved.
1387 Region of memory to be used, from ss to ss+nn.
1388 Example: Exclude memory from 0x18690000-0x1869ffff
1389 memmap=64K$0x18690000
1391 memmap=0x10000$0x18690000
1393 memory_corruption_check=0/1 [X86]
1394 Some BIOSes seem to corrupt the first 64k of
1395 memory when doing things like suspend/resume.
1396 Setting this option will scan the memory
1397 looking for corruption. Enabling this will
1398 both detect corruption and prevent the kernel
1399 from using the memory being corrupted.
1400 However, its intended as a diagnostic tool; if
1401 repeatable BIOS-originated corruption always
1402 affects the same memory, you can use memmap=
1403 to prevent the kernel from using that memory.
1405 memory_corruption_check_size=size [X86]
1406 By default it checks for corruption in the low
1407 64k, making this memory unavailable for normal
1408 use. Use this parameter to scan for
1409 corruption in more or less memory.
1411 memory_corruption_check_period=seconds [X86]
1412 By default it checks for corruption every 60
1413 seconds. Use this parameter to check at some
1414 other rate. 0 disables periodic checking.
1416 memtest= [KNL,X86] Enable memtest
1418 default : 0 <disable>
1419 Specifies the number of memtest passes to be
1420 performed. Each pass selects another test
1421 pattern from a given set of patterns. Memtest
1422 fills the memory with this pattern, validates
1423 memory contents and reserves bad memory
1424 regions that are detected.
1426 meye.*= [HW] Set MotionEye Camera parameters
1427 See Documentation/video4linux/meye.txt.
1429 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1430 Multi-Function General Purpose Timers on AMD Geode
1433 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1434 the BIOS has incorrectly applied a workaround. TinyBIOS
1435 version 0.98 is known to be affected, 0.99 fixes the
1436 problem by letting the user disable the workaround.
1440 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1441 physical address is ignored.
1443 mini2440= [ARM,HW,KNL]
1444 Format:[0..2][b][c][t]
1446 MINI2440 configuration specification:
1447 0 - The attached screen is the 3.5" TFT
1448 1 - The attached screen is the 7" TFT
1449 2 - The VGA Shield is attached (1024x768)
1450 Leaving out the screen size parameter will not load
1451 the TFT driver, and the framebuffer will be left
1453 b - Enable backlight. The TFT backlight pin will be
1454 linked to the kernel VESA blanking code and a GPIO
1455 LED. This parameter is not necessary when using the
1457 c - Enable the s3c camera interface.
1458 t - Reserved for enabling touchscreen support. The
1459 touchscreen support is not enabled in the mainstream
1460 kernel as of 2.6.30, a preliminary port can be found
1461 in the "bleeding edge" mini2440 support kernel at
1462 http://repo.or.cz/w/linux-2.6/mini2440.git
1465 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1466 parameter allows control of the logging verbosity for
1467 the additional memory initialisation checks. A value
1468 of 0 disables mminit logging and a level of 4 will
1469 log everything. Information is printed at KERN_DEBUG
1470 so loglevel=8 may also need to be specified.
1473 [MOUSE] Maximum time between finger touching and
1474 leaving touchpad surface for touch to be considered
1475 a tap and be reported as a left button click (for
1476 touchpads working in absolute mode only).
1478 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1479 reporting absolute coordinates, such as tablets
1480 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1481 reporting absolute coordinates, such as tablets
1483 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1484 is similar to kernelcore except it specifies the
1485 amount of memory used for migratable allocations.
1486 If both kernelcore and movablecore is specified,
1487 then kernelcore will be at *least* the specified
1488 value but may be more. If movablecore on its own
1489 is specified, the administrator must be careful
1490 that the amount of memory usable for all allocations
1496 MTD_Partition= [MTD]
1497 Format: <name>,<region-number>,<size>,<offset>
1499 MTD_Region= [MTD] Format:
1500 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1503 See drivers/mtd/cmdlinepart.c.
1505 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1507 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1509 boundary - index of last SLC block on Flex-OneNAND.
1510 The remaining blocks are configured as MLC blocks.
1511 lock - Configure if Flex-OneNAND boundary should be locked.
1512 Once locked, the boundary cannot be changed.
1513 1 indicates lock status, 0 indicates unlock status.
1516 ARM/S3C2412 JIVE boot control
1518 See arch/arm/mach-s3c2412/mach-jive.c
1520 mtouchusb.raw_coordinates=
1521 [HW] Make the MicroTouch USB driver use raw coordinates
1522 ('y', default) or cooked coordinates ('n')
1524 mtrr_chunk_size=nn[KMG] [X86]
1525 used for mtrr cleanup. It is largest continuous chunk
1526 that could hold holes aka. UC entries.
1528 mtrr_gran_size=nn[KMG] [X86]
1529 Used for mtrr cleanup. It is granularity of mtrr block.
1531 Large value could prevent small alignment from
1534 mtrr_spare_reg_nr=n [X86]
1536 Range: 0,7 : spare reg number
1538 Used for mtrr cleanup. It is spare mtrr entries number.
1539 Set to 2 or more if your graphical card needs more.
1541 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1544 See header of drivers/scsi/NCR_D700.c.
1548 ncr53c400= [HW,SCSI]
1550 ncr53c400a= [HW,SCSI]
1552 ncr53c406a= [HW,SCSI]
1554 ncr53c8xx= [HW,SCSI]
1556 netdev= [NET] Network devices parameters
1557 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1558 Note that mem_start is often overloaded to mean
1559 something different and driver-specific.
1560 This usage is only documented in each driver source
1564 [NETFILTER] Enable connection tracking flow accounting
1565 0 to disable accounting
1566 1 to enable accounting
1567 Default value depends on CONFIG_NF_CT_ACCT that is
1568 going to be removed in 2.6.29.
1571 See Documentation/filesystems/nfs/nfsroot.txt.
1573 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1574 See Documentation/filesystems/nfs/nfsroot.txt.
1576 nfs.callback_tcpport=
1577 [NFS] set the TCP port on which the NFSv4 callback
1578 channel should listen.
1581 [NFS] sets the pathname to the program which is used
1582 to update the NFS client cache entries.
1584 nfs.cache_getent_timeout=
1585 [NFS] sets the timeout after which an attempt to
1586 update a cache entry is deemed to have failed.
1588 nfs.idmap_cache_timeout=
1589 [NFS] set the maximum lifetime for idmapper cache
1593 [NFS] enable 64-bit inode numbers.
1594 If zero, the NFS client will fake up a 32-bit inode
1595 number for the readdir() and stat() syscalls instead
1596 of returning the full 64-bit number.
1597 The default is to return 64-bit inode numbers.
1599 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1600 when a NMI is triggered.
1601 Format: [state][,regs][,debounce][,die]
1603 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1604 Format: [panic,][num]
1606 0 - turn nmi_watchdog off
1607 1 - use the IO-APIC timer for the NMI watchdog
1608 2 - use the local APIC for the NMI watchdog using
1609 a performance counter. Note: This will use one
1610 performance counter and the local APIC's performance
1612 When panic is specified, panic when an NMI watchdog
1614 This is useful when you use a panic=... timeout and
1615 need the box quickly up again.
1616 Instead of 1 and 2 it is possible to use the following
1617 symbolic names: lapic and ioapic
1618 Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
1620 netpoll.carrier_timeout=
1621 [NET] Specifies amount of time (in seconds) that
1622 netpoll should wait for a carrier. By default netpoll
1625 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1626 emulation library even if a 387 maths coprocessor
1630 [HW] Never suspend the console
1631 Disable suspending of consoles during suspend and
1632 hibernate operations. Once disabled, debugging
1633 messages can reach various consoles while the rest
1634 of the system is being put to sleep (ie, while
1635 debugging driver suspend/resume hooks). This may
1636 not work reliably with all consoles, but is known
1637 to work with serial and VGA consoles.
1639 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1640 caches in the slab allocator. Saves per-node memory,
1641 but will impact performance.
1645 noapic [SMP,APIC] Tells the kernel to not make use of any
1646 IOAPICs that may be present in the system.
1648 nobats [PPC] Do not use BATs for mapping kernel lowmem
1649 on "Classic" PPC cores.
1653 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1655 nodelayacct [KNL] Disable per-task delay accounting
1657 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1659 nodsp [SH] Disable hardware DSP at boot time.
1661 noefi [X86] Disable EFI runtime services support.
1666 On X86-32 available only on PAE configured kernels.
1667 noexec=on: enable non-executable mappings (default)
1668 noexec=off: disable non-executable mappings
1671 This affects only 32-bit executables.
1672 noexec32=on: enable non-executable mappings (default)
1673 read doesn't imply executable mappings
1674 noexec32=off: disable non-executable mappings
1675 read implies executable mappings
1677 nofpu [SH] Disable hardware FPU at boot time.
1679 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1680 register save and restore. The kernel will only save
1681 legacy floating-point registers on task switch.
1683 noxsave [BUGS=X86] Disables x86 extended register state save
1684 and restore using xsave. The kernel will fallback to
1685 enabling legacy floating-point and sse state.
1687 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1688 wfi(ARM) instruction doesn't work correctly and not to
1689 use it. This is also useful when using JTAG debugger.
1691 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1692 instruction doesn't work correctly and not to
1695 no_file_caps Tells the kernel not to honor file capabilities. The
1696 only way then for a file to be executed with privilege
1697 is to be setuid root or executed by root.
1699 nohalt [IA-64] Tells the kernel not to use the power saving
1700 function PAL_HALT_LIGHT when idle. This increases
1701 power-consumption. On the positive side, it reduces
1702 interrupt wake-up latency, which may improve performance
1703 in certain environments such as networked servers or
1706 nohz= [KNL] Boottime enable/disable dynamic ticks
1707 Valid arguments: on, off
1710 noiotrap [SH] Disables trapped I/O port accesses.
1712 noirqdebug [X86-32] Disables the code which attempts to detect and
1713 disable unhandled interrupt sources.
1715 no_timer_check [X86,APIC] Disables the code which tests for
1716 broken timer IRQ sources.
1718 noisapnp [ISAPNP] Disables ISA PnP code.
1720 noinitrd [RAM] Tells the kernel not to load any configured
1723 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1728 nojitter [IA64] Disables jitter checking for ITC timers.
1730 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1732 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1734 noltlbs [PPC] Do not use large page/tlb entries for kernel
1735 lowmem mapping on PPC40x.
1737 nomca [IA-64] Disable machine check abort handling
1739 nomce [X86-32] Machine Check Exception
1741 nomfgpt [X86-32] Disable Multi-Function General Purpose
1742 Timer usage (for AMD Geode machines).
1744 nopat [X86] Disable PAT (page attribute table extension of
1745 pagetables) support.
1747 norandmaps Don't use address space randomization. Equivalent to
1748 echo 0 > /proc/sys/kernel/randomize_va_space
1750 noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
1752 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1753 with UP alternatives
1755 noresidual [PPC] Don't use residual data on PReP machines.
1757 noresume [SWSUSP] Disables resume and restores original swap
1760 no-scroll [VGA] Disables scrollback.
1761 This is required for the Braillex ib80-piezo Braille
1762 reader made by F.H. Papenmeier (Germany).
1766 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1768 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1769 and disable the IO APIC. legacy for "maxcpus=0".
1771 nosoftlockup [KNL] Disable the soft-lockup detector.
1773 noswapaccount [KNL] Disable accounting of swap in memory resource
1774 controller. (See Documentation/cgroups/memory.txt)
1776 nosync [HW,M68K] Disables sync negotiation for all devices.
1778 notsc [BUGS=X86-32] Disable Time Stamp Counter
1780 nousb [USB] Disable the USB subsystem
1784 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1786 nptcg= [IA64] Override max number of concurrent global TLB
1787 purges which is reported from either PAL_VM_SUMMARY or
1790 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1791 could support. nr_cpus=n : n >= 1 limits the kernel to
1792 supporting 'n' processors. Later in runtime you can not
1793 use hotplug cpu feature to put more cpu back to online.
1794 just like you compile the kernel NR_CPUS=n
1796 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1798 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1799 one of ['zone', 'node', 'default'] can be specified
1800 This can be set from sysctl after boot.
1801 See Documentation/sysctl/vm.txt for details.
1803 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1804 See Documentation/debugging-via-ohci1394.txt for more
1807 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1808 Rather than timing out after 20 ms if an EC
1809 command is not properly ACKed, override the length
1810 of the timeout. We have interrupts disabled while
1811 waiting for the ACK, so if this is set too high
1812 interrupts *may* be lost!
1814 omap_mux= [OMAP] Override bootloader pin multiplexing.
1815 Format: <mux_mode0.mode_name=value>...
1816 For example, to override I2C bus2:
1817 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1822 oprofile.timer= [HW]
1823 Use timer interrupt instead of performance counters
1825 oprofile.cpu_type= Force an oprofile cpu type
1826 This might be useful if you have an older oprofile
1827 userland or if you want common events.
1828 Format: { arch_perfmon }
1829 arch_perfmon: [X86] Force use of architectural
1830 perfmon on Intel CPUs instead of the
1831 CPU specific event set.
1833 osst= [HW,SCSI] SCSI Tape Driver
1834 Format: <buffer_size>,<write_threshold>
1835 See also Documentation/scsi/st.txt.
1837 panic= [KNL] Kernel behaviour on panic
1840 parkbd.port= [HW] Parallel port number the keyboard adapter is
1841 connected to, default is 0.
1843 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1844 0 for XT, 1 for AT (default is AT).
1847 parport= [HW,PPT] Specify parallel ports. 0 disables.
1848 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1849 Use 'auto' to force the driver to use any
1850 IRQ/DMA settings detected (the default is to
1851 ignore detected IRQ/DMA settings because of
1852 possible conflicts). You can specify the base
1853 address, IRQ, and DMA settings; IRQ and DMA
1854 should be numbers, or 'auto' (for using detected
1855 settings on that particular port), or 'nofifo'
1856 (to avoid using a FIFO even if it is detected).
1857 Parallel ports are assigned in the order they
1858 are specified on the command line, starting
1861 parport_init_mode= [HW,PPT]
1862 Configure VIA parallel port to operate in
1863 a specific mode. This is necessary on Pegasos
1864 computer where firmware has no options for setting
1865 up parallel port mode and sets it to spp.
1866 Currently this function knows 686a and 8231 chips.
1867 Format: [spp|ps2|epp|ecp|ecpepp]
1869 pas2= [HW,OSS] Format:
1870 <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
1873 See header of drivers/scsi/pas16.c.
1876 Halt all CPUs after the first oops has been printed for
1877 the specified number of seconds. This is to be used if
1878 your oopses keep scrolling off the screen.
1883 See header of drivers/block/paride/pcd.c.
1884 See also Documentation/blockdev/paride.txt.
1886 pci=option[,option...] [PCI] various PCI subsystem options:
1887 earlydump [X86] dump PCI config space before the kernel
1889 off [X86] don't probe for the PCI bus
1890 bios [X86-32] force use of PCI BIOS, don't access
1891 the hardware directly. Use this if your machine
1892 has a non-standard PCI host bridge.
1893 nobios [X86-32] disallow use of PCI BIOS, only direct
1894 hardware access methods are allowed. Use this
1895 if you experience crashes upon bootup and you
1896 suspect they are caused by the BIOS.
1897 conf1 [X86] Force use of PCI Configuration
1899 conf2 [X86] Force use of PCI Configuration
1901 noaer [PCIE] If the PCIEAER kernel config parameter is
1902 enabled, this kernel boot option can be used to
1903 disable the use of PCIE advanced error reporting.
1904 nodomains [PCI] Disable support for multiple PCI
1905 root domains (aka PCI segments, in ACPI-speak).
1906 nommconf [X86] Disable use of MMCONFIG for PCI
1908 check_enable_amd_mmconf [X86] check for and enable
1909 properly configured MMIO access to PCI
1910 config space on AMD family 10h CPU
1911 nomsi [MSI] If the PCI_MSI kernel config parameter is
1912 enabled, this kernel boot option can be used to
1913 disable the use of MSI interrupts system-wide.
1914 noioapicquirk [APIC] Disable all boot interrupt quirks.
1915 Safety option to keep boot IRQs enabled. This
1916 should never be necessary.
1917 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1918 primary IO-APIC for bridges that cannot disable
1919 boot IRQs. This fixes a source of spurious IRQs
1920 when the system masks IRQs.
1921 noioapicreroute [APIC] Disable workaround that uses the
1922 boot IRQ equivalent of an IRQ that connects to
1923 a chipset where boot IRQs cannot be disabled.
1924 The opposite of ioapicreroute.
1925 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1926 routing table. These calls are known to be buggy
1927 on several machines and they hang the machine
1928 when used, but on other computers it's the only
1929 way to get the interrupt routing table. Try
1930 this option if the kernel is unable to allocate
1931 IRQs or discover secondary PCI buses on your
1933 rom [X86] Assign address space to expansion ROMs.
1934 Use with caution as certain devices share
1935 address decoders between ROMs and other
1937 norom [X86] Do not assign address space to
1938 expansion ROMs that do not already have
1939 BIOS assigned address ranges.
1940 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1941 assigned automatically to PCI devices. You can
1942 make the kernel exclude IRQs of your ISA cards
1944 pirqaddr=0xAAAAA [X86] Specify the physical address
1945 of the PIRQ table (normally generated
1946 by the BIOS) if it is outside the
1947 F0000h-100000h range.
1948 lastbus=N [X86] Scan all buses thru bus #N. Can be
1949 useful if the kernel is unable to find your
1950 secondary buses and you want to tell it
1951 explicitly which ones they are.
1952 assign-busses [X86] Always assign all PCI bus
1953 numbers ourselves, overriding
1954 whatever the firmware may have done.
1955 usepirqmask [X86] Honor the possible IRQ mask stored
1956 in the BIOS $PIR table. This is needed on
1957 some systems with broken BIOSes, notably
1958 some HP Pavilion N5400 and Omnibook XE3
1959 notebooks. This will have no effect if ACPI
1960 IRQ routing is enabled.
1961 noacpi [X86] Do not use ACPI for IRQ routing
1962 or for PCI scanning.
1963 use_crs [X86] Use PCI host bridge window information
1964 from ACPI. On BIOSes from 2008 or later, this
1965 is enabled by default. If you need to use this,
1966 please report a bug.
1967 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1968 If you need to use this, please report a bug.
1969 routeirq Do IRQ routing for all PCI devices.
1970 This is normally done in pci_enable_device(),
1971 so this option is a temporary workaround
1972 for broken drivers that don't call it.
1973 skip_isa_align [X86] do not align io start addr, so can
1974 handle more pci cards
1975 firmware [ARM] Do not re-enumerate the bus but instead
1976 just use the configuration from the
1977 bootloader. This is currently used on
1978 IXP2000 systems where the bus has to be
1979 configured a certain way for adjunct CPUs.
1980 noearly [X86] Don't do any early type 1 scanning.
1981 This might help on some broken boards which
1982 machine check when some devices' config space
1983 is read. But various workarounds are disabled
1984 and some IOMMU drivers will not work.
1985 bfsort Sort PCI devices into breadth-first order.
1986 This sorting is done to get a device
1987 order compatible with older (<= 2.4) kernels.
1988 nobfsort Don't sort PCI devices into breadth-first order.
1989 cbiosize=nn[KMG] The fixed amount of bus space which is
1990 reserved for the CardBus bridge's IO window.
1991 The default value is 256 bytes.
1992 cbmemsize=nn[KMG] The fixed amount of bus space which is
1993 reserved for the CardBus bridge's memory
1994 window. The default value is 64 megabytes.
1997 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1998 Specifies alignment and device to reassign
1999 aligned memory resources.
2000 If <order of align> is not specified,
2001 PAGE_SIZE is used as alignment.
2002 PCI-PCI bridge can be specified, if resource
2003 windows need to be expanded.
2004 ecrc= Enable/disable PCIe ECRC (transaction layer
2005 end-to-end CRC checking).
2006 bios: Use BIOS/firmware settings. This is the
2011 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
2014 force Enable ASPM even on devices that claim not to support it.
2015 WARNING: Forcing ASPM on may cause system lockups.
2017 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2018 off Do not use native PCIe PME signaling.
2019 force Use native PCIe PME signaling even if the BIOS refuses
2020 to allow the kernel to control the relevant PCIe config
2022 nomsi Do not use MSI for native PCIe PME signaling (this makes
2023 all PCIe root ports use INTx for everything).
2025 pcmv= [HW,PCMCIA] BadgePAD 4
2028 See Documentation/blockdev/paride.txt.
2030 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2033 See arch/parisc/kernel/pdc_chassis.c
2035 percpu_alloc= Select which percpu first chunk allocator to use.
2036 Currently supported values are "embed" and "page".
2037 Archs may support subset or none of the selections.
2038 See comments in mm/percpu.c for details on each
2039 allocator. This parameter is primarily for debugging
2040 and performance comparison.
2043 See Documentation/blockdev/paride.txt.
2046 See Documentation/blockdev/paride.txt.
2048 pirq= [SMP,APIC] Manual mp-table setup
2049 See Documentation/x86/i386/IO-APIC.txt.
2051 plip= [PPT,NET] Parallel port network link
2052 Format: { parport<nr> | timid | 0 }
2053 See also Documentation/parport.txt.
2055 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2056 Override pmtimer IOPort with a hex value.
2060 Enable PNP debug messages. This depends on the
2061 CONFIG_PNP_DEBUG_MESSAGES option.
2067 { on | off | curr | res | no-curr | no-res }
2070 [ISAPNP] Exclude IRQs for the autoconfiguration
2073 [ISAPNP] Exclude DMAs for the autoconfiguration
2075 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2076 Ranges are in pairs (I/O port base and size).
2079 [ISAPNP] Exclude memory regions for the
2081 Ranges are in pairs (memory base and size).
2083 ports= [IP_VS_FTP] IPVS ftp helper module
2085 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2087 Format: <port>,<port>....
2089 print-fatal-signals=
2090 [KNL] debug: print fatal signals
2092 If enabled, warn about various signal handling
2093 related application anomalies: too many signals,
2094 too many POSIX.1 timers, fatal signals causing a
2097 If you hit the warning due to signal overflow,
2098 you might want to try "ulimit -i unlimited".
2102 printk.time= Show timing data prefixed to each printk message line
2103 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2105 processor.max_cstate= [HW,ACPI]
2106 Limit processor to maximum C-state
2107 max_cstate=9 overrides any DMI blacklist limit.
2109 processor.nocst [HW,ACPI]
2110 Ignore the _CST method to determine C-states,
2111 instead using the legacy FADT method
2113 profile= [KNL] Enable kernel profiling via /proc/profile
2114 Format: [schedule,]<number>
2115 Param: "schedule" - profile schedule points.
2116 Param: <number> - step/bucket size as a power of 2 for
2117 statistical time based profiling.
2118 Param: "sleep" - profile D-state sleeping (millisecs).
2119 Requires CONFIG_SCHEDSTATS
2120 Param: "kvm" - profile VM exits.
2122 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2124 See Documentation/blockdev/ramdisk.txt.
2126 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2127 probe for; one of (bare|imps|exps|lifebook|any).
2128 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2130 psmouse.resetafter= [HW,MOUSE]
2131 Try to reset the device after so many bad packets
2134 [HW,MOUSE] Set desired mouse resolution, in dpi.
2135 psmouse.smartscroll=
2136 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2137 0 = disabled, 1 = enabled (default).
2139 pss= [HW,OSS] Personal Sound System (ECHO ESC614)
2141 <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
2144 See Documentation/blockdev/paride.txt.
2147 [KNL] Number of legacy pty's. Overwrites compiled-in
2150 quiet [KNL] Disable most log messages
2155 See Documentation/md.txt.
2157 ramdisk_blocksize= [RAM]
2158 See Documentation/blockdev/ramdisk.txt.
2160 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2161 See Documentation/blockdev/ramdisk.txt.
2163 rcupdate.blimit= [KNL,BOOT]
2164 Set maximum number of finished RCU callbacks to process
2167 rcupdate.qhimark= [KNL,BOOT]
2168 Set threshold of queued
2169 RCU callbacks over which batch limiting is disabled.
2171 rcupdate.qlowmark= [KNL,BOOT]
2172 Set threshold of queued RCU callbacks below which
2173 batch limiting is re-enabled.
2177 Run specified binary instead of /init from the ramdisk,
2178 used for early userspace startup. See initrd.
2180 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2181 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2182 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2185 [KNL, SMP] Set scheduler's default relax_domain_level.
2186 See Documentation/cgroups/cpusets.txt.
2188 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2190 reservetop= [X86-32]
2192 Reserves a hole at the top of the kernel virtual
2195 reset_devices [KNL] Force drivers to reset the underlying device
2196 during initialization.
2199 Specify the partition device for software suspend
2201 resume_offset= [SWSUSP]
2202 Specify the offset from the beginning of the partition
2203 given by "resume=" at which the swap header is located,
2204 in <PAGE_SIZE> units (needed only for swap files).
2205 See Documentation/power/swsusp-and-swap-files.txt
2207 retain_initrd [RAM] Keep initrd memory after extraction
2209 rhash_entries= [KNL,NET]
2210 Set number of hash buckets for route cache
2212 riscom8= [HW,SERIAL]
2213 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2215 ro [KNL] Mount root device read-only on boot
2217 root= [KNL] Root filesystem
2219 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2220 mount the root filesystem
2222 rootflags= [KNL] Set root filesystem mount option string
2224 rootfstype= [KNL] Set root filesystem type
2226 rootwait [KNL] Wait (indefinitely) for root device to show up.
2227 Useful for devices that are detected asynchronously
2228 (e.g. USB and MMC devices).
2230 rw [KNL] Mount root device read-write on boot
2232 S [KNL] Run init in single mode
2235 See drivers/net/irda/sa1100_ir.c.
2237 sbni= [NET] Granch SBNI12 leased line adapter
2239 sched_debug [KNL] Enables verbose scheduler debug messages.
2241 sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
2242 Format: <io>[,<timeout>[,<isapnp>]]
2244 scsi_debug_*= [SCSI]
2245 See drivers/scsi/scsi_debug.c.
2247 scsi_default_dev_flags=
2248 [SCSI] SCSI default device flags
2251 scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
2252 Format: <vendor>:<model>:<flags>
2253 (flags are integer value)
2255 scsi_logging_level= [SCSI] a bit mask of logging levels
2256 See drivers/scsi/scsi_logging.h for bits. Also
2257 settable via sysctl at dev.scsi.logging_level
2258 (/proc/sys/dev/scsi/logging_level).
2259 There is also a nice 'scsi_logging_level' script in the
2260 S390-tools package, available for download at
2261 http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
2263 scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
2264 discovered. async scans them in kernel threads,
2265 allowing boot to proceed. none ignores them, expecting
2266 user space to do the scan.
2268 security= [SECURITY] Choose a security module to enable at boot.
2269 If this boot parameter is not specified, only the first
2270 security module asking for security registration will be
2271 loaded. An invalid security module name will be treated
2272 as if no module has been chosen.
2274 selinux= [SELINUX] Disable or enable SELinux at boot time.
2275 Format: { "0" | "1" }
2276 See security/selinux/Kconfig help text.
2279 Default value is set via kernel config option.
2280 If enabled at boot time, /selinux/disable can be used
2281 later to disable prior to initial policy load.
2283 serialnumber [BUGS=X86-32]
2286 Maximal number of shapers.
2288 show_msr= [x86] show boot-time MSR settings
2289 Format: { <integer> }
2290 Show boot-time (BIOS-initialized) MSR settings.
2291 The parameter means the number of CPUs to show,
2292 for example 1 means boot CPU only.
2295 See header of drivers/scsi/sim710.c.
2302 slub_debug[=options[,slabs]] [MM, SLUB]
2303 Enabling slub_debug allows one to determine the
2304 culprit if slab objects become corrupted. Enabling
2305 slub_debug can create guard zones around objects and
2306 may poison objects when not in use. Also tracks the
2307 last alloc / free. For more information see
2308 Documentation/vm/slub.txt.
2310 slub_max_order= [MM, SLUB]
2311 Determines the maximum allowed order for slabs.
2312 A high setting may cause OOMs due to memory
2313 fragmentation. For more information see
2314 Documentation/vm/slub.txt.
2316 slub_min_objects= [MM, SLUB]
2317 The minimum number of objects per slab. SLUB will
2318 increase the slab order up to slub_max_order to
2319 generate a sufficiently large slab able to contain
2320 the number of objects indicated. The higher the number
2321 of objects the smaller the overhead of tracking slabs
2322 and the less frequently locks need to be acquired.
2323 For more information see Documentation/vm/slub.txt.
2325 slub_min_order= [MM, SLUB]
2326 Determines the mininum page order for slabs. Must be
2327 lower than slub_max_order.
2328 For more information see Documentation/vm/slub.txt.
2330 slub_nomerge [MM, SLUB]
2331 Disable merging of slabs with similar size. May be
2332 necessary if there is some reason to distinguish
2333 allocs to different slabs. Debug options disable
2334 merging on their own.
2335 For more information see Documentation/vm/slub.txt.
2338 Format: <io1>[,<io2>[,...,<io8>]]
2340 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2341 attempt to substitute SMP alternatives once at boot.
2343 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2344 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2345 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2346 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2347 smsc-ircc2.ircc_irq= [HW] IRQ line
2348 smsc-ircc2.ircc_dma= [HW] DMA channel
2349 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2350 0: Toshiba Satellite 1800 (GP data pin select)
2351 1: Fast pin select (default)
2354 snd-ad1816a= [HW,ALSA]
2356 snd-ad1848= [HW,ALSA]
2358 snd-ali5451= [HW,ALSA]
2360 snd-als100= [HW,ALSA]
2362 snd-als4000= [HW,ALSA]
2364 snd-azt2320= [HW,ALSA]
2366 snd-cmi8330= [HW,ALSA]
2368 snd-cmipci= [HW,ALSA]
2370 snd-cs4231= [HW,ALSA]
2372 snd-cs4232= [HW,ALSA]
2374 snd-cs4236= [HW,ALSA]
2376 snd-cs4281= [HW,ALSA]
2378 snd-cs46xx= [HW,ALSA]
2380 snd-dt019x= [HW,ALSA]
2382 snd-dummy= [HW,ALSA]
2384 snd-emu10k1= [HW,ALSA]
2386 snd-ens1370= [HW,ALSA]
2388 snd-ens1371= [HW,ALSA]
2390 snd-es968= [HW,ALSA]
2392 snd-es1688= [HW,ALSA]
2394 snd-es18xx= [HW,ALSA]
2396 snd-es1938= [HW,ALSA]
2398 snd-es1968= [HW,ALSA]
2400 snd-fm801= [HW,ALSA]
2402 snd-gusclassic= [HW,ALSA]
2404 snd-gusextreme= [HW,ALSA]
2406 snd-gusmax= [HW,ALSA]
2410 snd-ice1712= [HW,ALSA]
2412 snd-intel8x0= [HW,ALSA]
2414 snd-interwave= [HW,ALSA]
2419 snd-korg1212= [HW,ALSA]
2421 snd-maestro3= [HW,ALSA]
2423 snd-mpu401= [HW,ALSA]
2425 snd-mtpav= [HW,ALSA]
2427 snd-nm256= [HW,ALSA]
2429 snd-opl3sa2= [HW,ALSA]
2437 snd-opti93x= [HW,ALSA]
2441 snd-rme32= [HW,ALSA]
2443 snd-rme96= [HW,ALSA]
2445 snd-rme9652= [HW,ALSA]
2451 snd-sbawe= [HW,ALSA]
2453 snd-serial= [HW,ALSA]
2455 snd-sgalaxy= [HW,ALSA]
2457 snd-sonicvibes= [HW,ALSA]
2462 snd-sun-cs4231= [HW,ALSA]
2464 snd-trident= [HW,ALSA]
2466 snd-usb-audio= [HW,ALSA,USB]
2468 snd-via82xx= [HW,ALSA]
2470 snd-virmidi= [HW,ALSA]
2472 snd-wavefront= [HW,ALSA]
2474 snd-ymfpci= [HW,ALSA]
2477 [KNL] Should the soft-lockup detector generate panics.
2479 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2480 See Documentation/sonypi.txt
2482 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2483 See Documentation/serial/specialix.txt.
2485 spia_io_base= [HW,MTD]
2491 Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
2493 st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
2494 See Documentation/scsi/st.txt.
2497 Enabled the stack tracer on boot up.
2501 Set the STI (builtin display/keyboard on the HP-PARISC
2502 machines) console (graphic card) which should be used
2503 as the initial boot-console.
2504 See also comment in drivers/video/console/sticore.c.
2507 See comment in drivers/video/console/sticore.c.
2510 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2512 sunrpc.min_resvport=
2513 sunrpc.max_resvport=
2515 SunRPC servers often require that client requests
2516 originate from a privileged port (i.e. a port in the
2517 range 0 < portnr < 1024).
2518 An administrator who wishes to reserve some of these
2519 ports for other uses may adjust the range that the
2520 kernel's sunrpc client considers to be privileged
2521 using these two parameters to set the minimum and
2522 maximum port values.
2526 Control how the NFS server code allocates CPUs to
2527 service thread pools. Depending on how many NICs
2528 you have and where their interrupts are bound, this
2529 option will affect which CPUs will do NFS serving.
2530 Note: this parameter cannot be changed while the
2531 NFS server is running.
2533 auto the server chooses an appropriate mode
2534 automatically using heuristics
2535 global a single global pool contains all CPUs
2536 percpu one pool for each CPU
2537 pernode one pool for each NUMA node (equivalent
2538 to global on non-NUMA machines)
2540 sunrpc.tcp_slot_table_entries=
2541 sunrpc.udp_slot_table_entries=
2543 Sets the upper limit on the number of simultaneous
2544 RPC calls that can be sent from the client to a
2545 server. Increasing these values may allow you to
2546 improve throughput, but will also increase the
2547 amount of memory reserved for use by the client.
2549 swiotlb= [IA-64] Number of I/O TLB slabs
2553 sym53c416= [HW,SCSI]
2554 See header of drivers/scsi/sym53c416.c.
2556 sysrq_always_enabled
2558 Ignore sysrq setting - this boot parameter will
2559 neutralize any effect of /proc/sys/kernel/sysrq.
2560 Useful for debugging.
2563 See header of drivers/scsi/t128.c.
2567 test_suspend= [SUSPEND]
2568 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2569 standby suspend) as the system sleep state to briefly
2570 enter during system startup. The system is woken from
2571 this state using a wakeup-capable RTC alarm.
2573 thash_entries= [KNL,NET]
2574 Set number of hash buckets for TCP connection
2576 thermal.act= [HW,ACPI]
2577 -1: disable all active trip points in all thermal zones
2578 <degrees C>: override all lowest active trip points
2580 thermal.crt= [HW,ACPI]
2581 -1: disable all critical trip points in all thermal zones
2582 <degrees C>: override all critical trip points
2584 thermal.nocrt= [HW,ACPI]
2585 Set to disable actions on ACPI thermal zone
2586 critical and hot trip points.
2588 thermal.off= [HW,ACPI]
2589 1: disable ACPI thermal control
2591 thermal.psv= [HW,ACPI]
2592 -1: disable all passive trip points
2593 <degrees C>: override all passive trip points to this
2596 thermal.tzp= [HW,ACPI]
2597 Specify global default ACPI thermal zone polling rate
2598 <deci-seconds>: poll all this frequency
2599 0: no polling (default)
2602 See comment before function dc390_setup() in
2603 drivers/scsi/tmscsim.c.
2607 Specify if the kernel should make use of the cpu
2608 topology informations if the hardware supports these.
2609 The scheduler will make use of these informations and
2610 e.g. base its process migration decisions on it.
2615 trace_buf_size=nn[KMG]
2616 [FTRACE] will set tracing buffer size.
2618 trace_event=[event-list]
2619 [FTRACE] Set and start specified trace events in order
2620 to facilitate early boot debugging.
2621 See also Documentation/trace/events.txt
2623 trix= [HW,OSS] MediaTrix AudioTrix Pro
2625 <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
2627 tsc= Disable clocksource-must-verify flag for TSC.
2629 [x86] reliable: mark tsc clocksource as reliable, this
2630 disables clocksource verification at runtime.
2631 Used to enable high-resolution timer mode on older
2632 hardware, and in virtualized environment.
2634 turbografx.map[2|3]= [HW,JOY]
2635 TurboGraFX parallel port interface
2637 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2638 See also Documentation/input/joystick-parport.txt
2640 u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
2641 See header of drivers/scsi/u14-34f.c.
2649 uhash_entries= [KNL,NET]
2650 Set number of hash buckets for UDP/UDP-Lite connections
2653 [USB] Ignore overcurrent events (default N).
2654 Some badly-designed motherboards generate lots of
2655 bogus events, for ports that aren't wired to
2656 anything. Set this parameter to avoid log spamming.
2657 Note that genuine overcurrent events won't be
2662 Set unknown_nmi_panic=1 early on boot.
2664 usbcore.autosuspend=
2665 [USB] The autosuspend time delay (in seconds) used
2666 for newly-detected USB devices (default 2). This
2667 is the time required before an idle device will be
2668 autosuspended. Devices for which the delay is set
2669 to a negative value won't be autosuspended at all.
2671 usbcore.usbfs_snoop=
2672 [USB] Set to log all usbfs traffic (default 0 = off).
2674 usbcore.blinkenlights=
2675 [USB] Set to cycle leds on hubs (default 0 = off).
2677 usbcore.old_scheme_first=
2678 [USB] Start with the old device initialization
2679 scheme (default 0 = off).
2681 usbcore.use_both_schemes=
2682 [USB] Try the other device initialization scheme
2683 if the first one fails (default 1 = enabled).
2685 usbcore.initial_descriptor_timeout=
2686 [USB] Specifies timeout for the initial 64-byte
2687 USB_REQ_GET_DESCRIPTOR request in milliseconds
2688 (default 5000 = 5.0 seconds).
2691 [USBHID] The interval which mice are to be polled at.
2693 usb-storage.delay_use=
2694 [UMS] The delay in seconds before a new device is
2695 scanned for Logical Units (default 5).
2698 [UMS] A list of quirks entries to supplement or
2699 override the built-in unusual_devs list. List
2700 entries are separated by commas. Each entry has
2701 the form VID:PID:Flags where VID and PID are Vendor
2702 and Product ID values (4-digit hex numbers) and
2703 Flags is a set of characters, each corresponding
2704 to a common usb-storage quirk flag as follows:
2705 a = SANE_SENSE (collect more than 18 bytes
2707 b = BAD_SENSE (don't collect more than 18
2708 bytes of sense data);
2709 c = FIX_CAPACITY (decrease the reported
2710 device capacity by one sector);
2711 h = CAPACITY_HEURISTICS (decrease the
2712 reported device capacity by one
2713 sector if the number is odd);
2714 i = IGNORE_DEVICE (don't bind to this
2716 l = NOT_LOCKABLE (don't try to lock and
2717 unlock ejectable media);
2718 m = MAX_SECTORS_64 (don't transfer more
2719 than 64 sectors = 32 KB at a time);
2720 o = CAPACITY_OK (accept the capacity
2721 reported by the device);
2722 r = IGNORE_RESIDUE (the device reports
2723 bogus residue values);
2724 s = SINGLE_LUN (the device has only one
2726 w = NO_WP_DETECT (don't test whether the
2727 medium is write-protected).
2728 Example: quirks=0419:aaf5:rl,0421:0433:rc
2731 [X86] Flags controlling user PTE allocations.
2733 nohigh = do not allocate PTE pages in
2734 HIGHMEM regardless of setting
2738 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2739 vdso=1: enable VDSO (default)
2740 vdso=0: disable VDSO mapping
2743 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2744 vdso32=1: enable 32-bit VDSO (default)
2745 vdso32=0: disable 32-bit VDSO mapping
2748 vector=percpu: enable percpu vector domain
2750 video= [FB] Frame buffer configuration
2751 See Documentation/fb/modedb.txt.
2753 vga= [BOOT,X86-32] Select a particular video mode
2754 See Documentation/x86/boot.txt and
2755 Documentation/svga.txt.
2756 Use vga=ask for menu.
2757 This is actually a boot loader parameter; the value is
2758 passed to the kernel using a special protocol.
2760 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2761 size of <nn>. This can be used to increase the
2762 minimum size (128MB on x86). It can also be used to
2763 decrease the size and leave more room for directly
2766 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2769 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2772 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2775 vt.cur_default= [VT] Default cursor shape.
2776 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2777 the parameters of the <Esc>[?A;B;Cc escape sequence;
2778 see VGA-softcursor.txt. Default: 2 = underline.
2780 vt.default_blu= [VT]
2781 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2782 Change the default blue palette of the console.
2783 This is a 16-member array composed of values
2786 vt.default_grn= [VT]
2787 Format: <green0>,<green1>,<green2>,...,<green15>
2788 Change the default green palette of the console.
2789 This is a 16-member array composed of values
2792 vt.default_red= [VT]
2793 Format: <red0>,<red1>,<red2>,...,<red15>
2794 Change the default red palette of the console.
2795 This is a 16-member array composed of values
2801 Set system-wide default UTF-8 mode for all tty's.
2802 Default is 1, i.e. UTF-8 mode is enabled for all
2803 newly opened terminals.
2805 vt.global_cursor_default=
2808 Set system-wide default for whether a cursor
2809 is shown on new VTs. Default is -1,
2810 i.e. cursors will be created by default unless
2811 overridden by individual drivers. 0 will hide
2812 cursors, 1 will display them.
2814 waveartist= [HW,OSS]
2815 Format: <io>,<irq>,<dma>,<dma2>
2818 See header of drivers/scsi/wd33c93.c.
2821 See header of drivers/scsi/wd7000.c.
2824 See Documentation/watchdog/wdt.txt.
2826 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2827 default x2apic cluster mode on platforms
2830 x86_mrst_timer= [X86-32,APBT]
2831 Choose timer option for x86 Moorestown MID platform.
2832 Two valid options are apbt timer only and lapic timer
2833 plus one apbt timer for broadcast timer.
2834 x86_mrst_timer=apbt_only | lapic_and_apbt
2836 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2837 xd_geo= See header of drivers/block/xd.c.
2839 xirc2ps_cs= [NET,PCMCIA]
2841 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2843 ______________________________________________________________________
2847 Add documentation for ALSA options.
2848 Add more DRM drivers.
git://ftp.safe.ca / safe / jmp / linux-2.6 / blob