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 EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
47 EFI EFI Partitioning (GPT) is enabled
48 EIDE EIDE/ATAPI support is enabled.
49 DRM Direct Rendering Management support is enabled.
50 DYNAMIC_DEBUG Build in debug messages and enable them at runtime
51 FB The frame buffer device is enabled.
52 GCOV GCOV profiling is enabled.
53 HW Appropriate hardware is enabled.
54 IA-64 IA-64 architecture is enabled.
55 IMA Integrity measurement architecture is enabled.
56 IOSCHED More than one I/O scheduler is enabled.
57 IP_PNP IP DHCP, BOOTP, or RARP is enabled.
58 IPV6 IPv6 support is enabled.
59 ISAPNP ISA PnP code is enabled.
60 ISDN Appropriate ISDN support is enabled.
61 JOY Appropriate joystick support is enabled.
62 KGDB Kernel debugger support is enabled.
63 KVM Kernel Virtual Machine support is enabled.
64 LIBATA Libata driver is enabled
65 LP Printer support is enabled.
66 LOOP Loopback device support is enabled.
67 M68k M68k architecture is enabled.
68 These options have more detailed description inside of
69 Documentation/m68k/kernel-options.txt.
70 MCA MCA bus support is enabled.
71 MDA MDA console support is enabled.
72 MOUSE Appropriate mouse support is enabled.
73 MSI Message Signaled Interrupts (PCI).
74 MTD MTD (Memory Technology Device) support is enabled.
75 NET Appropriate network support is enabled.
76 NUMA NUMA support is enabled.
77 NFS Appropriate NFS support is enabled.
78 OSS OSS sound support is enabled.
79 PV_OPS A paravirtualized kernel is enabled.
80 PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
81 PARISC The PA-RISC architecture is enabled.
82 PCI PCI bus support is enabled.
83 PCIE PCI Express support is enabled.
84 PCMCIA The PCMCIA subsystem is enabled.
85 PNP Plug & Play support is enabled.
86 PPC PowerPC architecture is enabled.
87 PPT Parallel port support is enabled.
88 PS2 Appropriate PS/2 support is enabled.
89 RAM RAM disk support is enabled.
90 S390 S390 architecture is enabled.
91 SCSI Appropriate SCSI support is enabled.
92 A lot of drivers have their options described inside
93 the Documentation/scsi/ sub-directory.
94 SECURITY Different security models are enabled.
95 SELINUX SELinux support is enabled.
96 APPARMOR AppArmor support is enabled.
97 SERIAL Serial support is enabled.
98 SH SuperH architecture is enabled.
99 SMP The kernel is an SMP kernel.
100 SPARC Sparc architecture is enabled.
101 SWSUSP Software suspend (hibernation) is enabled.
102 SUSPEND System suspend states are enabled.
103 FTRACE Function tracing enabled.
104 TPM TPM drivers are enabled.
105 TS Appropriate touchscreen support is enabled.
106 UMS USB Mass Storage support is enabled.
107 USB USB support is enabled.
108 USBHID USB Human Interface Device support is enabled.
109 V4L Video For Linux support is enabled.
110 VGA The VGA console has been enabled.
111 VT Virtual terminal support is enabled.
112 WDT Watchdog support is enabled.
113 XT IBM PC/XT MFM hard disk support is enabled.
114 X86-32 X86-32, aka i386 architecture is enabled.
115 X86-64 X86-64 architecture is enabled.
116 More X86-64 boot options can be found in
117 Documentation/x86/x86_64/boot-options.txt .
118 X86 Either 32bit or 64bit x86 (same as X86-32+X86-64)
119 XEN Xen support is enabled
121 In addition, the following text indicates that the option:
123 BUGS= Relates to possible processor bugs on the said processor.
124 KNL Is a kernel start-up parameter.
125 BOOT Is a boot loader parameter.
127 Parameters denoted with BOOT are actually interpreted by the boot
128 loader, and have no meaning to the kernel directly.
129 Do not modify the syntax of boot loader parameters without extreme
130 need or coordination with <Documentation/x86/boot.txt>.
132 There are also arch-specific kernel-parameters not documented here.
133 See for example <Documentation/x86/x86_64/boot-options.txt>.
135 Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
136 a trailing = on the name of any parameter states that that parameter will
137 be entered as an environment variable, whereas its absence indicates that
138 it will appear as a kernel argument readable via /proc/cmdline by programs
139 running once the system is up.
141 The number of kernel parameters is not limited, but the length of the
142 complete command line (parameters including spaces etc.) is limited to
143 a fixed number of characters. This limit depends on the architecture
144 and is between 256 and 4096 characters. It is defined in the file
145 ./include/asm/setup.h as COMMAND_LINE_SIZE.
149 Advanced Configuration and Power Interface
150 Format: { force | off | strict | noirq | rsdt }
151 force -- enable ACPI if default was off
152 off -- disable ACPI if default was on
153 noirq -- do not use ACPI for IRQ routing
154 strict -- Be less tolerant of platforms that are not
155 strictly ACPI specification compliant.
156 rsdt -- prefer RSDT over (default) XSDT
157 copy_dsdt -- copy DSDT to memory
159 See also Documentation/power/pm.txt, pci=noacpi
161 acpi_apic_instance= [ACPI, IOAPIC]
163 2: use 2nd APIC table, if available
164 1,0: use 1st APIC table
167 acpi_backlight= [HW,ACPI]
168 acpi_backlight=vendor
170 If set to vendor, prefer vendor specific driver
171 (e.g. thinkpad_acpi, sony_acpi, etc.) instead
172 of the ACPI video.ko driver.
174 acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
175 acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
177 CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
178 debug output. Bits in debug_layer correspond to a
179 _COMPONENT in an ACPI source file, e.g.,
180 #define _COMPONENT ACPI_PCI_COMPONENT
181 Bits in debug_level correspond to a level in
182 ACPI_DEBUG_PRINT statements, e.g.,
183 ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
184 The debug_level mask defaults to "info". See
185 Documentation/acpi/debug.txt for more information about
186 debug layers and levels.
188 Enable processor driver info messages:
189 acpi.debug_layer=0x20000000
190 Enable PCI/PCI interrupt routing info messages:
191 acpi.debug_layer=0x400000
192 Enable AML "Debug" output, i.e., stores to the Debug
193 object while interpreting AML:
194 acpi.debug_layer=0xffffffff acpi.debug_level=0x2
195 Enable all messages related to ACPI hardware:
196 acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
198 Some values produce so much output that the system is
199 unusable. The "log_buf_len" parameter may be useful
200 if you need to capture more output.
202 acpi_display_output= [HW,ACPI]
203 acpi_display_output=vendor
204 acpi_display_output=video
207 acpi_irq_balance [HW,ACPI]
208 ACPI will balance active IRQs
211 acpi_irq_nobalance [HW,ACPI]
212 ACPI will not move active IRQs (default)
215 acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
216 Format: <irq>,<irq>...
218 acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
220 Format: <irq>,<irq>...
222 acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
224 acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
225 Format: To spoof as Windows 98: ="Microsoft Windows"
227 acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
228 acpi_osi="string1" # add string1 -- only one string
229 acpi_osi="!string2" # remove built-in string2
230 acpi_osi= # disable all strings
233 Override the pmtimer bug detection: force the kernel
234 to assume that this machine's pmtimer latches its value
235 and always returns good values.
237 acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
238 Format: { level | edge | high | low }
240 acpi_serialize [HW,ACPI] force serialization of AML methods
242 acpi_skip_timer_override [HW,ACPI]
243 Recognize and ignore IRQ0/pin2 Interrupt Override.
244 For broken nForce2 BIOS resulting in XT-PIC timer.
246 acpi_sleep= [HW,ACPI] Sleep options
247 Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
248 old_ordering, s4_nonvs, sci_force_enable }
249 See Documentation/power/video.txt for information on
251 s3_beep is for debugging; it makes the PC's speaker beep
252 as soon as the kernel's real-mode entry point is called.
253 s4_nohwsig prevents ACPI hardware signature from being
254 used during resume from hibernation.
255 old_ordering causes the ACPI 1.0 ordering of the _PTS
256 control method, with respect to putting devices into
257 low power states, to be enforced (the ACPI 2.0 ordering
258 of _PTS is used by default).
259 nonvs prevents the kernel from saving/restoring the
260 ACPI NVS memory during suspend/hibernation and resume.
261 sci_force_enable causes the kernel to set SCI_EN directly
262 on resume from S1/S3 (which is against the ACPI spec,
263 but some broken systems don't work without it).
265 acpi_use_timer_override [HW,ACPI]
266 Use timer override. For some broken Nvidia NF5 boards
267 that require a timer override, but don't have HPET
269 acpi_enforce_resources= [ACPI]
270 { strict | lax | no }
271 Check for resource conflicts between native drivers
272 and ACPI OperationRegions (SystemIO and SystemMemory
273 only). IO ports and memory declared in ACPI might be
274 used by the ACPI subsystem in arbitrary AML code and
275 can interfere with legacy drivers.
276 strict (default): access to resources claimed by ACPI
277 is denied; legacy drivers trying to access reserved
278 resources will fail to bind to device using them.
279 lax: access to resources claimed by ACPI is allowed;
280 legacy drivers trying to access reserved resources
281 will bind successfully but a warning message is logged.
282 no: ACPI OperationRegions are not marked as reserved,
283 no further checks are performed.
285 add_efi_memmap [EFI; X86] Include EFI memory map in
286 kernel's map of available physical RAM.
289 { off | try_unsupported }
290 off: disable AGP support
291 try_unsupported: try to drive unsupported chipsets
292 (may crash computer or cause data corruption)
295 See Documentation/sound/alsa/alsa-parameters.txt
298 Allow the default userspace alignment fault handler
299 behaviour to be specified. Bit 0 enables warnings,
300 bit 1 enables fixups, and bit 2 sends a segfault.
302 amd_iommu= [HW,X86-84]
303 Pass parameters to the AMD IOMMU driver in the system.
305 fullflush - enable flushing of IO/TLB entries when
306 they are unmapped. Otherwise they are
307 flushed before they will be reused, which
309 off - do not initialize any AMD IOMMU found in
312 amijoy.map= [HW,JOY] Amiga joystick support
313 Map of devices attached to JOY0DAT and JOY1DAT
315 See also Documentation/kernel/input/joystick.txt
317 analog.map= [HW,JOY] Analog joystick and gamepad support
318 Specifies type or capabilities of an analog joystick
319 connected to one of 16 gameports
320 Format: <type1>,<type2>,..<type16>
323 Power management functions (SPARCstation-4/5 + deriv.)
325 Disable APC CPU standby support. SPARCstation-Fox does
326 not play well with APC CPU idle - disable it if you have
327 APC and your system crashes randomly.
329 apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
330 Change the output verbosity whilst booting
331 Format: { quiet (default) | verbose | debug }
332 Change the amount of debugging information output
333 when initialising the APIC and IO-APIC components.
336 See Documentation/networking/ipv6.txt.
338 show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
339 Limit apic dumping. The parameter defines the maximal
340 number of local apics being dumped. Also it is possible
341 to set it to "all" by meaning -- no limit here.
342 Format: { 1 (default) | 2 | ... | all }.
343 The parameter valid if only apic=debug or
344 apic=verbose is specified.
345 Example: apic=debug show_lapic=all
347 apm= [APM] Advanced Power Management
348 See header of arch/x86/kernel/apm_32.c.
350 arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
351 Format: <io>,<irq>,<nodeID>
355 atarimouse= [HW,MOUSE] Atari Mouse
357 atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
358 EzKey and similar keyboards
360 atkbd.reset= [HW] Reset keyboard during initialization
362 atkbd.set= [HW] Select keyboard code set
363 Format: <int> (2 = AT (default), 3 = PS/2)
365 atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
368 atkbd.softraw= [HW] Choose between synthetic and real raw mode
369 Format: <bool> (0 = real, 1 = synthetic (default))
371 atkbd.softrepeat= [HW]
372 Use software keyboard repeat
376 baycom_epp= [HW,AX25]
379 baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
381 See header of drivers/net/hamradio/baycom_par.c.
383 baycom_ser_fdx= [HW,AX25]
384 BayCom Serial Port AX.25 Modem (Full Duplex Mode)
385 Format: <io>,<irq>,<mode>[,<baud>]
386 See header of drivers/net/hamradio/baycom_ser_fdx.c.
388 baycom_ser_hdx= [HW,AX25]
389 BayCom Serial Port AX.25 Modem (Half Duplex Mode)
390 Format: <io>,<irq>,<mode>
391 See header of drivers/net/hamradio/baycom_ser_hdx.c.
393 boot_delay= Milliseconds to delay each printk during boot.
394 Values larger than 10 seconds (10000) are changed to
398 bootmem_debug [KNL] Enable bootmem allocator debug messages.
400 bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
401 bttv.radio= Most important insmod options are available as
403 bttv.pll= See Documentation/video4linux/bttv/Insmod-options
404 bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
406 bulk_remove=off [PPC] This parameter disables the use of the pSeries
407 firmware feature for flushing multiple hpte entries
410 c101= [NET] Moxa C101 synchronous serial card
412 cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
413 Sometimes CPU hardware bugs make them report the cache
414 size incorrectly. The kernel will attempt work arounds
415 to fix known problems, but for some CPUs it is not
416 possible to determine what the correct size should be.
417 This option provides an override for these situations.
420 [SECURITY] Disable capabilities. This would normally
421 be used only if an alternative security model is to be
422 configured. Potentially dangerous and should only be
423 used if you are entirely sure of the consequences.
425 ccw_timeout_log [S390]
426 See Documentation/s390/CommonIO for details.
428 cgroup_disable= [KNL] Disable a particular controller
429 Format: {name of the controller(s) to disable}
430 {Currently supported controllers - "memory"}
432 checkreqprot [SELINUX] Set initial checkreqprot flag value.
433 Format: { "0" | "1" }
434 See security/selinux/Kconfig help text.
435 0 -- check protection applied by kernel (includes
436 any implied execute protection).
437 1 -- check protection requested by application.
438 Default value is set via a kernel config option.
439 Value can be changed at runtime via
440 /selinux/checkreqprot.
443 See Documentation/s390/CommonIO for details.
445 clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
447 Forces specified clocksource (if available) to be used
448 when calculating gettimeofday(). If specified
449 clocksource is not available, it defaults to PIT.
450 Format: { pit | tsc | cyclone | pmtmr }
452 clocksource= Override the default clocksource
454 Override the default clocksource and use the clocksource
455 with the name specified.
456 Some clocksource names to choose from, depending on
458 [all] jiffies (this is the base, fallback clocksource)
460 [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
461 pxa_timer,timer3,32k_counter,timer0_1
463 [X86-32] pit,hpet,tsc;
464 scx200_hrt on Geode; cyclone on IBM x440
472 clearcpuid=BITNUM [X86]
473 Disable CPUID feature X for the kernel. See
474 arch/x86/include/asm/cpufeature.h for the valid bit
475 numbers. Note the Linux specific bits are not necessarily
476 stable over kernel options, but the vendor specific
478 Also note that user programs calling CPUID directly
479 or using the feature without checking anything
480 will still see it. This just prevents it from
481 being used by the kernel or shown in /proc/cpuinfo.
482 Also note the kernel might malfunction if you disable
485 cmo_free_hint= [PPC] Format: { yes | no }
486 Specify whether pages are marked as being inactive
487 when they are freed. This is used in CMO environments
488 to determine OS memory pressure for page stealing by
492 code_bytes [X86] How many bytes of object code to print
497 com20020= [HW,NET] ARCnet - COM20020 chipset
499 <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
501 com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
505 ARCnet - COM90xx chipset (memory-mapped buffers)
506 Format: <io>[,<irq>[,<memstart>]]
508 condev= [HW,S390] console device
511 console= [KNL] Output console device and options.
513 tty<n> Use the virtual console device <n>.
517 Use the specified serial port. The options are of
518 the form "bbbbpnf", where "bbbb" is the baud rate,
519 "p" is parity ("n", "o", or "e"), "n" is number of
520 bits, and "f" is flow control ("r" for RTS or
521 omit it). Default is "9600n8".
523 See Documentation/serial-console.txt for more
525 Documentation/networking/netconsole.txt for an
528 uart[8250],io,<addr>[,options]
529 uart[8250],mmio,<addr>[,options]
530 Start an early, polled-mode console on the 8250/16550
531 UART at the specified I/O port or MMIO address,
532 switching to the matching ttyS device later. The
533 options are the same as for ttyS, above.
535 If the device connected to the port is not a TTY but a braille
536 device, prepend "brl," before the device type, for instance
538 For now, only VisioBraille is supported.
540 consoleblank= [KNL] The console blank (screen saver) timeout in
541 seconds. Defaults to 10*60 = 10mins. A value of 0
542 disables the blank timer.
545 [KNL] Change the default value for
546 /proc/<pid>/coredump_filter.
547 See also Documentation/filesystems/proc.txt.
549 cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
551 <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
553 crashkernel=nn[KMG]@ss[KMG]
554 [KNL] Reserve a chunk of physical memory to
555 hold a kernel to switch to with kexec on panic.
557 crashkernel=range1:size1[,range2:size2,...][@offset]
558 [KNL] Same as above, but depends on the memory
559 in the running system. The syntax of range is
560 start-[end] where start and end are both
561 a memory unit (amount[KMG]). See also
562 Documentation/kdump/kdump.txt for a example.
567 cs89x0_media= [HW,NET]
568 Format: { rj45 | aui | bnc }
571 See header of drivers/s390/block/dasd_devmap.c.
573 db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
574 (one device per port)
575 Format: <port#>,<type>
576 See also Documentation/input/joystick-parport.txt
578 ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
579 time. See Documentation/dynamic-debug-howto.txt for
582 debug [KNL] Enable kernel debugging (events log level).
585 [KNL] verbose self-tests
587 Print debugging info while doing the locking API
589 We default to 0 (no extra messages), setting it to
590 1 will print _a lot_ more information - normally
591 only useful to kernel developers.
593 debug_objects [KNL] Enable object debugging
596 [KNL] Disable object debugging
598 debugpat [X86] Enable PAT debugging
600 decnet.addr= [HW,NET]
601 Format: <area>[,<node>]
602 See also Documentation/networking/decnet.txt.
605 [same as hugepagesz=] The size of the default
606 HugeTLB page size. This is the size represented by
607 the legacy /proc/ hugepages APIs, used for SHM, and
608 default size when mounting hugetlbfs filesystems.
609 Defaults to the default architecture's huge page size
613 Set number of hash buckets for dentry cache.
616 IO parameters + enable/disable command.
618 digiepca= [HW,SERIAL]
619 See drivers/char/README.epca and
620 Documentation/serial/digiepca.txt.
623 See Documentation/networking/ipv6.txt.
626 See Documentation/networking/ipv6.txt.
628 disable_mtrr_cleanup [X86]
629 The kernel tries to adjust MTRR layout from continuous
630 to discrete, to make X server driver able to add WB
631 entry later. This parameter disables that.
633 disable_mtrr_trim [X86, Intel and AMD only]
634 By default the kernel will trim any uncacheable
635 memory out of your available memory pool based on
636 MTRR settings. This parameter disables that behavior,
637 possibly causing your machine to run very slowly.
639 disable_timer_pin_1 [X86]
640 Disable PIN 1 of APIC timer
641 Can be useful to work around chipset bugs.
643 dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
644 this option disables the debugging code at boot.
646 dma_debug_entries=<number>
647 This option allows to tune the number of preallocated
648 entries for DMA-API debugging code. One entry is
649 required per DMA-API allocation. Use this if the
650 DMA-API debugging code disables itself because the
651 architectural default is too low.
653 dma_debug_driver=<driver_name>
654 With this option the DMA-API debugging driver
655 filter feature can be enabled at boot time. Just
656 pass the driver to filter for as the parameter.
657 The filter can be disabled or changed to another
658 driver later using sysfs.
662 dynamic_printk Enables pr_debug()/dev_dbg() calls if
663 CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
664 These can also be switched on/off via
665 <debugfs>/dynamic_printk/modules
667 earlycon= [KNL] Output early console device and options.
668 uart[8250],io,<addr>[,options]
669 uart[8250],mmio,<addr>[,options]
670 uart[8250],mmio32,<addr>[,options]
671 Start an early, polled-mode console on the 8250/16550
672 UART at the specified I/O port or MMIO address.
673 MMIO inter-register address stride is either 8bit (mmio)
675 The options are the same as for ttyS, above.
677 earlyprintk= [X86,SH,BLACKFIN]
679 earlyprintk=serial[,ttySn[,baudrate]]
680 earlyprintk=ttySn[,baudrate]
681 earlyprintk=dbgp[debugController#]
683 Append ",keep" to not disable it when the real console
686 Only vga or serial or usb debug port at a time.
688 Currently only ttyS0 and ttyS1 are supported.
690 Interaction with the standard serial driver is not
693 The VGA output is eventually overwritten by the real
696 ekgdboc= [X86,KGDB] Allow early kernel console debugging
699 This is desgined to be used in conjunction with
700 the boot argument: earlyprintk=vga
703 Format: {"off" | "on" | "skip[mbr]"}
705 eisa_irq_edge= [PARISC,HW]
706 See header of drivers/parisc/eisa.c.
709 See comment before function elanfreq_setup() in
710 arch/x86/kernel/cpu/cpufreq/elanfreq.c.
713 Format: {"cfq" | "deadline" | "noop"}
714 See Documentation/block/as-iosched.txt and
715 Documentation/block/deadline-iosched.txt for details.
717 elfcorehdr= [IA64,PPC,SH,X86]
718 Specifies physical address of start of kernel core
719 image elf header. Generally kexec loader will
720 pass this option to capture kernel.
721 See Documentation/kdump/kdump.txt for details.
723 enable_mtrr_cleanup [X86]
724 The kernel tries to adjust MTRR layout from continuous
725 to discrete, to make X server driver able to add WB
726 entry later. This parameter enables that.
728 enable_timer_pin_1 [X86]
729 Enable PIN 1 of APIC timer
730 Can be useful to work around chipset bugs
731 (in particular on some ATI chipsets).
732 The kernel tries to set a reasonable default.
734 enforcing [SELINUX] Set initial enforcing status.
736 See security/selinux/Kconfig help text.
737 0 -- permissive (log only, no denials).
738 1 -- enforcing (deny and log).
740 Value can be changed at runtime via /selinux/enforce.
743 Disable Error Record Serialization Table (ERST)
746 ether= [HW,NET] Ethernet cards parameters
747 This option is obsoleted by the "netdev=" option, which
748 has equivalent usage. See its documentation for details.
752 fail_make_request=[KNL]
753 General fault injection mechanism.
754 Format: <interval>,<probability>,<space>,<times>
755 See also /Documentation/fault-injection/.
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
771 ftrace_dump_on_oops[=orig_cpu]
772 [FTRACE] will dump the trace buffers on oops.
773 If no parameter is passed, ftrace will dump
774 buffers of all CPUs, but if you pass orig_cpu, it will
775 dump only the buffer of the CPU that triggered the
778 ftrace_filter=[function-list]
779 [FTRACE] Limit the functions traced by the function
780 tracer at boot up. function-list is a comma separated
781 list of functions. This list can be changed at run
782 time by the set_ftrace_filter file in the debugfs
785 ftrace_notrace=[function-list]
786 [FTRACE] Do not trace the functions specified in
787 function-list. This list can be changed at run time
788 by the set_ftrace_notrace file in the debugfs
791 ftrace_graph_filter=[function-list]
792 [FTRACE] Limit the top level callers functions traced
793 by the function graph tracer at boot up.
794 function-list is a comma separated list of functions
795 that can be changed at run time by the
796 set_graph_function file in the debugfs tracing directory.
799 [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
800 support via parallel port (up to 5 devices per port)
801 Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
802 See also Documentation/input/joystick-parport.txt
806 gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
810 gcov_persist= [GCOV] When non-zero (default), profiling data for
811 kernel modules is saved and remains accessible via
812 debugfs, even when the module is unloaded/reloaded.
813 When zero, profiling data is discarded and associated
814 debugfs files are removed at module unload time.
816 gpt [EFI] Forces disk with valid GPT signature but
817 invalid Protective MBR to be treated as GPT.
819 hashdist= [KNL,NUMA] Large hashes allocated during boot
820 are distributed across NUMA nodes. Defaults on
821 for 64bit NUMA, off otherwise.
822 Format: 0 | 1 (for off | on)
824 hcl= [IA-64] SGI's Hardware Graph compatibility layer
826 hd= [EIDE] (E)IDE hard drive subsystem geometry
827 Format: <cyl>,<head>,<sect>
830 Disable Hardware Error Source Table (HEST) support;
831 corresponding firmware-first mode error processing
832 logic will be disabled.
834 highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
835 size of <nn>. This works even on boxes that have no
836 highmem otherwise. This also works to reduce highmem
837 size on bigger boxes.
839 highres= [KNL] Enable/disable high resolution timer mode.
840 Valid parameters: "on", "off"
844 See Documentation/isdn/README.HiSax.
848 hpet= [X86-32,HPET] option to control HPET usage
849 Format: { enable (default) | disable | force |
851 disable: disable HPET and use PIT instead
852 force: allow force enabled of undocumented chips (ICH4,
854 verbose: show contents of HPET registers during setup
856 hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
857 hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
858 On x86-64 and powerpc, this option can be specified
859 multiple times interleaved with hugepages= to reserve
860 huge pages of different sizes. Valid pages sizes on
861 x86-64 are 2M (when the CPU supports "pse") and 1G
862 (when the CPU supports the "pdpe1gb" cpuinfo flag)
863 Note that 1GB pages can only be allocated at boot time
864 using hugepages= and not freed afterwards.
866 hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
867 terminal devices. Valid values: 0..8
868 hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
869 If specified, z/VM IUCV HVC accepts connections
870 from listed z/VM user IDs only.
872 i2c_bus= [HW] Override the default board specific I2C bus speed
873 or register an additional I2C bus that is not
874 registered from board initialization code.
878 i8042.debug [HW] Toggle i8042 debug mode
879 i8042.direct [HW] Put keyboard port into non-translated mode
880 i8042.dumbkbd [HW] Pretend that controller can only read data from
881 keyboard and cannot control its state
882 (Don't attempt to blink the leds)
883 i8042.noaux [HW] Don't check for auxiliary (== mouse) port
884 i8042.nokbd [HW] Don't check/create keyboard port
885 i8042.noloop [HW] Disable the AUX Loopback command while probing
887 i8042.nomux [HW] Don't check presence of an active multiplexing
889 i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
891 i8042.notimeout [HW] Ignore timeout condition signalled by conroller
892 i8042.reset [HW] Reset the controller during init and cleanup
893 i8042.unlock [HW] Unlock (ignore) the keylock
897 i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
898 indicates that the driver is running on unsupported
900 i8k.force [HW] Activate i8k driver even if SMM BIOS signature
901 does not match list of supported models.
903 [HW] Report power status in /proc/i8k
904 (disabled by default)
905 i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
909 Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
911 ide-core.nodma= [HW] (E)IDE subsystem
912 Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
913 .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
914 .cdrom .chs .ignore_cable are additional options
915 See Documentation/ide/ide.txt.
917 ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
918 Claim all unknown PCI IDE storage controllers.
921 Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
922 Poll forces a polling idle loop that can slightly
923 improve the performance of waking up a idle CPU, but
924 will use a lot of power and make the system run hot.
926 idle=mwait: On systems which support MONITOR/MWAIT but
927 the kernel chose to not use it because it doesn't save
928 as much power as a normal idle loop, use the
929 MONITOR/MWAIT idle loop anyways. Performance should be
930 the same as idle=poll.
931 idle=halt: Halt is forced to be used for CPU idle.
932 In such case C2/C3 won't be used again.
933 idle=nomwait: Disable mwait for CPU C-states
935 ignore_loglevel [KNL]
936 Ignore loglevel setting - this will print /all/
937 kernel messages to the console. Useful for debugging.
940 Set number of hash buckets for inode cache.
943 Format: { "0" | "1" }
944 0 -- integrity auditing messages. (Default)
945 1 -- enable informational integrity auditing messages.
948 Format: { "sha1" | "md5" }
952 Load a policy which meets the needs of the Trusted
953 Computing Base. This means IMA will measure all
954 programs exec'd, files mmap'd for exec, and all files
955 opened for read by uid=0.
959 Run specified binary instead of /sbin/init as init
962 initcall_debug [KNL] Trace initcalls as they are executed. Useful
963 for working out where the kernel is dying during
966 initrd= [BOOT] Specify the location of the initial ramdisk
968 inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
971 intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
973 Enable intel iommu driver.
975 Disable intel iommu driver.
976 igfx_off [Default Off]
977 By default, gfx is mapped as normal device. If a gfx
978 device has a dedicated DMAR unit, the DMAR unit is
979 bypassed by not enabling DMAR with this option. In
980 this case, gfx device will use physical address for
983 With this option iommu will not optimize to look
984 for io virtual address below 32 bit forcing dual
985 address cycle on pci bus for cards supporting greater
986 than 32 bit addressing. The default is to look
987 for translation below 32 bit and if not available
988 then look in the higher range.
990 With this option on every unmap_single operation will
991 result in a hardware IOTLB flush operation as opposed
992 to batching them for performance.
994 intremap= [X86-64, Intel-IOMMU]
995 Format: { on (default) | off | nosid }
996 on enable Interrupt Remapping (default)
997 off disable Interrupt Remapping
998 nosid disable Source ID checking
1002 iomem= Disable strict checking of access to MMIO memory
1003 strict regions from userspace.
1019 io7= [HW] IO7 for Marvel based alpha systems
1020 See comment before marvel_specify_io7 in
1021 arch/alpha/kernel/core_marvel.c.
1023 io_delay= [X86] I/O delay method
1025 Standard port 0x80 based delay
1027 Alternate port 0xed based delay (needed on some systems)
1029 Simple two microseconds delay
1034 See Documentation/filesystems/nfs/nfsroot.txt.
1036 ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
1037 See comment before ip2_setup() in
1038 drivers/char/ip2/ip2base.c.
1041 When an interrupt is not handled search all handlers
1042 for it. Intended to get systems with badly broken
1046 When an interrupt is not handled search all handlers
1047 for it. Also check all handlers each timer
1048 interrupt. Intended to get systems with badly broken
1052 Format: <RDP>,<reset>,<pci_scan>,<verbosity>
1054 isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
1056 <cpu number>,...,<cpu number>
1058 <cpu number>-<cpu number>
1059 (must be a positive range in ascending order)
1061 <cpu number>,...,<cpu number>-<cpu number>
1063 This option can be used to specify one or more CPUs
1064 to isolate from the general SMP balancing and scheduling
1065 algorithms. You can move a process onto or off an
1066 "isolated" CPU via the CPU affinity syscalls or cpuset.
1067 <cpu number> begins at 0 and the maximum value is
1068 "number of CPUs in system - 1".
1070 This option is the preferred way to isolate CPUs. The
1071 alternative -- manually setting the CPU mask of all
1072 tasks in the system -- can cause problems and
1073 suboptimal load balancer performance.
1077 js= [HW,JOY] Analog joystick
1078 See Documentation/input/joystick.txt.
1082 kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1083 specifies the amount of memory usable by the kernel
1084 for non-movable allocations. The requested amount is
1085 spread evenly throughout all nodes in the system. The
1086 remaining memory in each node is used for Movable
1087 pages. In the event, a node is too small to have both
1088 kernelcore and Movable pages, kernelcore pages will
1089 take priority and other nodes will have a larger number
1090 of kernelcore pages. The Movable zone is used for the
1091 allocation of pages that may be reclaimed or moved
1092 by the page migration subsystem. This means that
1093 HugeTLB pages may not be allocated from this zone.
1094 Note that allocations like PTEs-from-HighMem still
1095 use the HighMem zone if it exists, and the Normal
1096 zone if it does not.
1098 kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
1099 Format: <Controller#>[,poll interval]
1100 The controller # is the number of the ehci usb debug
1101 port as it is probed via PCI. The poll interval is
1102 optional and is the number seconds in between
1103 each poll cycle to the debug port in case you need
1104 the functionality for interrupting the kernel with
1105 gdb or control-c on the dbgp connection. When
1106 not using this parameter you use sysrq-g to break into
1107 the kernel debugger.
1109 kgdboc= [KGDB,HW] kgdb over consoles.
1110 Requires a tty driver that supports console polling,
1111 or a supported polling keyboard driver (non-usb).
1112 Serial only format: <serial_device>[,baud]
1113 keyboard only format: kbd
1114 keyboard and serial format: kbd,<serial_device>[,baud]
1115 Optional Kernel mode setting:
1116 kms, kbd format: kms,kbd
1117 kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
1119 kgdbwait [KGDB] Stop kernel execution and enter the
1120 kernel debugger at the earliest opportunity.
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.mmu_audit= [KVM] This is a R/W parameter which allows audit
1143 kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
1144 Default is 1 (enabled)
1146 kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
1148 Default is 1 (enabled) if in 64bit or 32bit-PAE mode
1150 kvm-intel.bypass_guest_pf=
1151 [KVM,Intel] Disables bypassing of guest page faults
1152 on Intel chips. Default is 1 (enabled)
1154 kvm-intel.ept= [KVM,Intel] Disable extended page tables
1155 (virtualized MMU) support on capable Intel chips.
1156 Default is 1 (enabled)
1158 kvm-intel.emulate_invalid_guest_state=
1159 [KVM,Intel] Enable emulation of invalid guest states
1160 Default is 0 (disabled)
1162 kvm-intel.flexpriority=
1163 [KVM,Intel] Disable FlexPriority feature (TPR shadow).
1164 Default is 1 (enabled)
1166 kvm-intel.unrestricted_guest=
1167 [KVM,Intel] Disable unrestricted guest feature
1168 (virtualized real and unpaged mode) on capable
1169 Intel chips. Default is 1 (enabled)
1171 kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
1172 feature (tagged TLBs) on capable Intel chips.
1173 Default is 1 (enabled)
1179 lapic [X86-32,APIC] Enable the local APIC even if BIOS
1182 lapic_timer_c2_ok [X86,APIC] trust the local apic timer
1185 libata.dma= [LIBATA] DMA control
1186 libata.dma=0 Disable all PATA and SATA DMA
1187 libata.dma=1 PATA and SATA Disk DMA only
1188 libata.dma=2 ATAPI (CDROM) DMA only
1189 libata.dma=4 Compact Flash DMA only
1190 Combinations also work, so libata.dma=3 enables DMA
1191 for disks and CDROMs, but not CFs.
1193 libata.ignore_hpa= [LIBATA] Ignore HPA limit
1194 libata.ignore_hpa=0 keep BIOS limits (default)
1195 libata.ignore_hpa=1 ignore limits, using full disk
1197 libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
1201 libata.force= [LIBATA] Force configurations. The format is comma
1202 separated list of "[ID:]VAL" where ID is
1203 PORT[.DEVICE]. PORT and DEVICE are decimal numbers
1204 matching port, link or device. Basically, it matches
1205 the ATA ID string printed on console by libata. If
1206 the whole ID part is omitted, the last PORT and DEVICE
1207 values are used. If ID hasn't been specified yet, the
1208 configuration applies to all ports, links and devices.
1210 If only DEVICE is omitted, the parameter applies to
1211 the port and all links and devices behind it. DEVICE
1212 number of 0 either selects the first device or the
1213 first fan-out link behind PMP device. It does not
1214 select the host link. DEVICE number of 15 selects the
1215 host link and device attached to it.
1217 The VAL specifies the configuration to force. As long
1218 as there's no ambiguity shortcut notation is allowed.
1219 For example, both 1.5 and 1.5G would work for 1.5Gbps.
1220 The following configurations can be forced.
1222 * Cable type: 40c, 80c, short40c, unk, ign or sata.
1223 Any ID with matching PORT is used.
1225 * SATA link speed limit: 1.5Gbps or 3.0Gbps.
1227 * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
1228 udma[/][16,25,33,44,66,100,133] notation is also
1231 * [no]ncq: Turn on or off NCQ.
1233 * nohrst, nosrst, norst: suppress hard, soft
1236 * dump_id: dump IDENTIFY data.
1238 If there are multiple matching configurations changing
1239 the same attribute, the last one is used.
1241 memblock=debug [KNL] Enable memblock debug messages.
1243 load_ramdisk= [RAM] List of ramdisks to load from floppy
1244 See Documentation/blockdev/ramdisk.txt.
1246 lockd.nlm_grace_period=P [NFS] Assign grace period.
1249 lockd.nlm_tcpport=N [NFS] Assign TCP port.
1252 lockd.nlm_timeout=T [NFS] Assign timeout value.
1255 lockd.nlm_udpport=M [NFS] Assign UDP port.
1258 logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
1261 loglevel= All Kernel Messages with a loglevel smaller than the
1262 console loglevel will be printed to the console. It can
1263 also be changed with klogd or other programs. The
1264 loglevels are defined as follows:
1266 0 (KERN_EMERG) system is unusable
1267 1 (KERN_ALERT) action must be taken immediately
1268 2 (KERN_CRIT) critical conditions
1269 3 (KERN_ERR) error conditions
1270 4 (KERN_WARNING) warning conditions
1271 5 (KERN_NOTICE) normal but significant condition
1272 6 (KERN_INFO) informational
1273 7 (KERN_DEBUG) debug-level messages
1275 log_buf_len=n Sets the size of the printk ring buffer, in bytes.
1276 Format: { n | nk | nM }
1277 n must be a power of two. The default size
1278 is set in the kernel config file.
1280 logo.nologo [FB] Disables display of the built-in Linux logo.
1281 This may be used to provide more screen space for
1282 kernel log messages and is useful when debugging
1283 kernel boot problems.
1285 lp=0 [LP] Specify parallel ports to use, e.g,
1286 lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
1287 lp=reset first parallel port). 'lp=0' disables the
1288 lp=auto printer driver. 'lp=reset' (which can be
1289 specified in addition to the ports) causes
1290 attached printers to be reset. Using
1291 lp=port1,port2,... specifies the parallel ports
1292 to associate lp devices with, starting with
1293 lp0. A port specification may be 'none' to skip
1294 that lp device, or a parport name such as
1295 'parport0'. Specifying 'lp=auto' instead of a
1296 port specification list means that device IDs
1297 from each port should be examined, to see if
1298 an IEEE 1284-compliant printer is attached; if
1299 so, the driver will manage that printer.
1300 See also header of drivers/char/lp.c.
1303 Sets loops_per_jiffy to given constant, thus avoiding
1304 time-consuming boot-time autodetection (up to 250 ms per
1305 CPU). 0 enables autodetection (default). To determine
1306 the correct value for your kernel, boot with normal
1307 autodetection and see what value is printed. Note that
1308 on SMP systems the preset will be applied to all CPUs,
1309 which is likely to cause problems if your CPUs need
1310 significantly divergent settings. An incorrect value
1311 will cause delays in the kernel to be wrong, leading to
1312 unpredictable I/O errors and other breakage. Although
1313 unlikely, in the extreme case this might damage your
1317 Format: <io>,<irq>,<dma>
1319 machvec= [IA64] Force the use of a particular machine-vector
1320 (machvec) in a generic kernel.
1321 Example: machvec=hpzx1_swiotlb
1323 machtype= [Loongson] Share the same kernel image file between different
1325 Example: machtype=lemote-yeeloong-2f-7inch
1327 max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
1328 than or equal to this physical address is ignored.
1330 maxcpus= [SMP] Maximum number of processors that an SMP kernel
1331 should make use of. maxcpus=n : n >= 0 limits the
1332 kernel to using 'n' processors. n=0 is a special case,
1333 it is equivalent to "nosmp", which also disables
1336 max_loop= [LOOP] Maximum number of loopback devices that can
1342 mce [X86-32] Machine Check Exception
1344 mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt
1346 md= [HW] RAID subsystems devices and level
1347 See Documentation/md.txt.
1350 Format: <first>,<last>
1351 Specifies range of consoles to be captured by the MDA.
1353 mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
1354 Amount of memory to be used when the kernel is not able
1355 to see the whole system memory or for test.
1356 [X86-32] Use together with memmap= to avoid physical
1357 address space collisions. Without memmap= PCI devices
1358 could be placed at addresses belonging to unused RAM.
1360 mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
1364 [KNL,SH] Allow user to override the default size for
1365 per-device physically contiguous DMA buffers.
1367 memmap=exactmap [KNL,X86] Enable setting of an exact
1368 E820 memory map, as specified by the user.
1369 Such memmap=exactmap lines can be constructed based on
1370 BIOS output or other requirements. See the memmap=nn@ss
1373 memmap=nn[KMG]@ss[KMG]
1374 [KNL] Force usage of a specific region of memory
1375 Region of memory to be used, from ss to ss+nn.
1377 memmap=nn[KMG]#ss[KMG]
1378 [KNL,ACPI] Mark specific memory as ACPI data.
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 reserved.
1383 Region of memory to be used, from ss to ss+nn.
1384 Example: Exclude memory from 0x18690000-0x1869ffff
1385 memmap=64K$0x18690000
1387 memmap=0x10000$0x18690000
1389 memory_corruption_check=0/1 [X86]
1390 Some BIOSes seem to corrupt the first 64k of
1391 memory when doing things like suspend/resume.
1392 Setting this option will scan the memory
1393 looking for corruption. Enabling this will
1394 both detect corruption and prevent the kernel
1395 from using the memory being corrupted.
1396 However, its intended as a diagnostic tool; if
1397 repeatable BIOS-originated corruption always
1398 affects the same memory, you can use memmap=
1399 to prevent the kernel from using that memory.
1401 memory_corruption_check_size=size [X86]
1402 By default it checks for corruption in the low
1403 64k, making this memory unavailable for normal
1404 use. Use this parameter to scan for
1405 corruption in more or less memory.
1407 memory_corruption_check_period=seconds [X86]
1408 By default it checks for corruption every 60
1409 seconds. Use this parameter to check at some
1410 other rate. 0 disables periodic checking.
1412 memtest= [KNL,X86] Enable memtest
1414 default : 0 <disable>
1415 Specifies the number of memtest passes to be
1416 performed. Each pass selects another test
1417 pattern from a given set of patterns. Memtest
1418 fills the memory with this pattern, validates
1419 memory contents and reserves bad memory
1420 regions that are detected.
1422 meye.*= [HW] Set MotionEye Camera parameters
1423 See Documentation/video4linux/meye.txt.
1425 mfgpt_irq= [IA-32] Specify the IRQ to use for the
1426 Multi-Function General Purpose Timers on AMD Geode
1429 mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
1430 the BIOS has incorrectly applied a workaround. TinyBIOS
1431 version 0.98 is known to be affected, 0.99 fixes the
1432 problem by letting the user disable the workaround.
1436 min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
1437 physical address is ignored.
1439 mini2440= [ARM,HW,KNL]
1440 Format:[0..2][b][c][t]
1442 MINI2440 configuration specification:
1443 0 - The attached screen is the 3.5" TFT
1444 1 - The attached screen is the 7" TFT
1445 2 - The VGA Shield is attached (1024x768)
1446 Leaving out the screen size parameter will not load
1447 the TFT driver, and the framebuffer will be left
1449 b - Enable backlight. The TFT backlight pin will be
1450 linked to the kernel VESA blanking code and a GPIO
1451 LED. This parameter is not necessary when using the
1453 c - Enable the s3c camera interface.
1454 t - Reserved for enabling touchscreen support. The
1455 touchscreen support is not enabled in the mainstream
1456 kernel as of 2.6.30, a preliminary port can be found
1457 in the "bleeding edge" mini2440 support kernel at
1458 http://repo.or.cz/w/linux-2.6/mini2440.git
1461 [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
1462 parameter allows control of the logging verbosity for
1463 the additional memory initialisation checks. A value
1464 of 0 disables mminit logging and a level of 4 will
1465 log everything. Information is printed at KERN_DEBUG
1466 so loglevel=8 may also need to be specified.
1469 [MOUSE] Maximum time between finger touching and
1470 leaving touchpad surface for touch to be considered
1471 a tap and be reported as a left button click (for
1472 touchpads working in absolute mode only).
1474 mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
1475 reporting absolute coordinates, such as tablets
1476 mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
1477 reporting absolute coordinates, such as tablets
1479 movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
1480 is similar to kernelcore except it specifies the
1481 amount of memory used for migratable allocations.
1482 If both kernelcore and movablecore is specified,
1483 then kernelcore will be at *least* the specified
1484 value but may be more. If movablecore on its own
1485 is specified, the administrator must be careful
1486 that the amount of memory usable for all allocations
1489 MTD_Partition= [MTD]
1490 Format: <name>,<region-number>,<size>,<offset>
1492 MTD_Region= [MTD] Format:
1493 <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
1496 See drivers/mtd/cmdlinepart.c.
1498 multitce=off [PPC] This parameter disables the use of the pSeries
1499 firmware feature for updating multiple TCE entries
1502 onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
1504 Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
1506 boundary - index of last SLC block on Flex-OneNAND.
1507 The remaining blocks are configured as MLC blocks.
1508 lock - Configure if Flex-OneNAND boundary should be locked.
1509 Once locked, the boundary cannot be changed.
1510 1 indicates lock status, 0 indicates unlock status.
1513 ARM/S3C2412 JIVE boot control
1515 See arch/arm/mach-s3c2412/mach-jive.c
1517 mtouchusb.raw_coordinates=
1518 [HW] Make the MicroTouch USB driver use raw coordinates
1519 ('y', default) or cooked coordinates ('n')
1521 mtrr_chunk_size=nn[KMG] [X86]
1522 used for mtrr cleanup. It is largest continuous chunk
1523 that could hold holes aka. UC entries.
1525 mtrr_gran_size=nn[KMG] [X86]
1526 Used for mtrr cleanup. It is granularity of mtrr block.
1528 Large value could prevent small alignment from
1531 mtrr_spare_reg_nr=n [X86]
1533 Range: 0,7 : spare reg number
1535 Used for mtrr cleanup. It is spare mtrr entries number.
1536 Set to 2 or more if your graphical card needs more.
1538 n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
1540 netdev= [NET] Network devices parameters
1541 Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
1542 Note that mem_start is often overloaded to mean
1543 something different and driver-specific.
1544 This usage is only documented in each driver source
1548 [NETFILTER] Enable connection tracking flow accounting
1549 0 to disable accounting
1550 1 to enable accounting
1553 nfsaddrs= [NFS] Deprecated. Use ip= instead.
1554 See Documentation/filesystems/nfs/nfsroot.txt.
1556 nfsroot= [NFS] nfs root filesystem for disk-less boxes.
1557 See Documentation/filesystems/nfs/nfsroot.txt.
1559 nfsrootdebug [NFS] enable nfsroot debugging messages.
1560 See Documentation/filesystems/nfs/nfsroot.txt.
1562 nfs.callback_tcpport=
1563 [NFS] set the TCP port on which the NFSv4 callback
1564 channel should listen.
1567 [NFS] sets the pathname to the program which is used
1568 to update the NFS client cache entries.
1570 nfs.cache_getent_timeout=
1571 [NFS] sets the timeout after which an attempt to
1572 update a cache entry is deemed to have failed.
1574 nfs.idmap_cache_timeout=
1575 [NFS] set the maximum lifetime for idmapper cache
1579 [NFS] enable 64-bit inode numbers.
1580 If zero, the NFS client will fake up a 32-bit inode
1581 number for the readdir() and stat() syscalls instead
1582 of returning the full 64-bit number.
1583 The default is to return 64-bit inode numbers.
1585 nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
1586 when a NMI is triggered.
1587 Format: [state][,regs][,debounce][,die]
1589 nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
1590 Format: [panic,][num]
1592 0 - turn nmi_watchdog off
1593 When panic is specified, panic when an NMI watchdog
1595 This is useful when you use a panic=... timeout and
1596 need the box quickly up again.
1598 netpoll.carrier_timeout=
1599 [NET] Specifies amount of time (in seconds) that
1600 netpoll should wait for a carrier. By default netpoll
1603 no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
1604 emulation library even if a 387 maths coprocessor
1608 [HW] Never suspend the console
1609 Disable suspending of consoles during suspend and
1610 hibernate operations. Once disabled, debugging
1611 messages can reach various consoles while the rest
1612 of the system is being put to sleep (ie, while
1613 debugging driver suspend/resume hooks). This may
1614 not work reliably with all consoles, but is known
1615 to work with serial and VGA consoles.
1617 noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
1618 caches in the slab allocator. Saves per-node memory,
1619 but will impact performance.
1623 noapic [SMP,APIC] Tells the kernel to not make use of any
1624 IOAPICs that may be present in the system.
1626 noautogroup Disable scheduler automatic task group creation.
1628 nobats [PPC] Do not use BATs for mapping kernel lowmem
1629 on "Classic" PPC cores.
1633 noclflush [BUGS=X86] Don't use the CLFLUSH instruction
1635 nodelayacct [KNL] Disable per-task delay accounting
1637 nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
1639 nodsp [SH] Disable hardware DSP at boot time.
1641 noefi [X86] Disable EFI runtime services support.
1646 On X86-32 available only on PAE configured kernels.
1647 noexec=on: enable non-executable mappings (default)
1648 noexec=off: disable non-executable mappings
1651 This affects only 32-bit executables.
1652 noexec32=on: enable non-executable mappings (default)
1653 read doesn't imply executable mappings
1654 noexec32=off: disable non-executable mappings
1655 read implies executable mappings
1657 nofpu [SH] Disable hardware FPU at boot time.
1659 nofxsr [BUGS=X86-32] Disables x86 floating point extended
1660 register save and restore. The kernel will only save
1661 legacy floating-point registers on task switch.
1663 noxsave [BUGS=X86] Disables x86 extended register state save
1664 and restore using xsave. The kernel will fallback to
1665 enabling legacy floating-point and sse state.
1667 nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
1668 wfi(ARM) instruction doesn't work correctly and not to
1669 use it. This is also useful when using JTAG debugger.
1671 no-hlt [BUGS=X86-32] Tells the kernel that the hlt
1672 instruction doesn't work correctly and not to
1675 no_file_caps Tells the kernel not to honor file capabilities. The
1676 only way then for a file to be executed with privilege
1677 is to be setuid root or executed by root.
1679 nohalt [IA-64] Tells the kernel not to use the power saving
1680 function PAL_HALT_LIGHT when idle. This increases
1681 power-consumption. On the positive side, it reduces
1682 interrupt wake-up latency, which may improve performance
1683 in certain environments such as networked servers or
1686 nohz= [KNL] Boottime enable/disable dynamic ticks
1687 Valid arguments: on, off
1690 noiotrap [SH] Disables trapped I/O port accesses.
1692 noirqdebug [X86-32] Disables the code which attempts to detect and
1693 disable unhandled interrupt sources.
1695 no_timer_check [X86,APIC] Disables the code which tests for
1696 broken timer IRQ sources.
1698 noisapnp [ISAPNP] Disables ISA PnP code.
1700 noinitrd [RAM] Tells the kernel not to load any configured
1703 nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
1705 [Deprecated - use intremap=off]
1709 nojitter [IA64] Disables jitter checking for ITC timers.
1711 no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
1713 nolapic [X86-32,APIC] Do not enable or use the local APIC.
1715 nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
1717 noltlbs [PPC] Do not use large page/tlb entries for kernel
1718 lowmem mapping on PPC40x.
1720 nomca [IA-64] Disable machine check abort handling
1722 nomce [X86-32] Machine Check Exception
1724 nomfgpt [X86-32] Disable Multi-Function General Purpose
1725 Timer usage (for AMD Geode machines).
1727 nopat [X86] Disable PAT (page attribute table extension of
1728 pagetables) support.
1730 norandmaps Don't use address space randomization. Equivalent to
1731 echo 0 > /proc/sys/kernel/randomize_va_space
1733 noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
1735 noreplace-smp [X86-32,SMP] Don't replace SMP instructions
1736 with UP alternatives
1738 noresidual [PPC] Don't use residual data on PReP machines.
1740 noresume [SWSUSP] Disables resume and restores original swap
1743 no-scroll [VGA] Disables scrollback.
1744 This is required for the Braillex ib80-piezo Braille
1745 reader made by F.H. Papenmeier (Germany).
1749 nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
1751 nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
1752 and disable the IO APIC. legacy for "maxcpus=0".
1754 nosoftlockup [KNL] Disable the soft-lockup detector.
1756 noswapaccount [KNL] Disable accounting of swap in memory resource
1757 controller. (See Documentation/cgroups/memory.txt)
1759 nosync [HW,M68K] Disables sync negotiation for all devices.
1761 notsc [BUGS=X86-32] Disable Time Stamp Counter
1763 nousb [USB] Disable the USB subsystem
1765 nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
1769 nox2apic [X86-64,APIC] Do not enable x2APIC mode.
1771 nptcg= [IA64] Override max number of concurrent global TLB
1772 purges which is reported from either PAL_VM_SUMMARY or
1775 nr_cpus= [SMP] Maximum number of processors that an SMP kernel
1776 could support. nr_cpus=n : n >= 1 limits the kernel to
1777 supporting 'n' processors. Later in runtime you can not
1778 use hotplug cpu feature to put more cpu back to online.
1779 just like you compile the kernel NR_CPUS=n
1781 nr_uarts= [SERIAL] maximum number of UARTs to be registered.
1783 numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
1784 one of ['zone', 'node', 'default'] can be specified
1785 This can be set from sysctl after boot.
1786 See Documentation/sysctl/vm.txt for details.
1788 ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
1789 See Documentation/debugging-via-ohci1394.txt for more
1792 olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
1793 Rather than timing out after 20 ms if an EC
1794 command is not properly ACKed, override the length
1795 of the timeout. We have interrupts disabled while
1796 waiting for the ACK, so if this is set too high
1797 interrupts *may* be lost!
1799 omap_mux= [OMAP] Override bootloader pin multiplexing.
1800 Format: <mux_mode0.mode_name=value>...
1801 For example, to override I2C bus2:
1802 omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
1804 oprofile.timer= [HW]
1805 Use timer interrupt instead of performance counters
1807 oprofile.cpu_type= Force an oprofile cpu type
1808 This might be useful if you have an older oprofile
1809 userland or if you want common events.
1810 Format: { arch_perfmon }
1811 arch_perfmon: [X86] Force use of architectural
1812 perfmon on Intel CPUs instead of the
1813 CPU specific event set.
1816 See Documentation/sound/oss/oss-parameters.txt
1818 panic= [KNL] Kernel behaviour on panic
1821 parkbd.port= [HW] Parallel port number the keyboard adapter is
1822 connected to, default is 0.
1824 parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
1825 0 for XT, 1 for AT (default is AT).
1828 parport= [HW,PPT] Specify parallel ports. 0 disables.
1829 Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
1830 Use 'auto' to force the driver to use any
1831 IRQ/DMA settings detected (the default is to
1832 ignore detected IRQ/DMA settings because of
1833 possible conflicts). You can specify the base
1834 address, IRQ, and DMA settings; IRQ and DMA
1835 should be numbers, or 'auto' (for using detected
1836 settings on that particular port), or 'nofifo'
1837 (to avoid using a FIFO even if it is detected).
1838 Parallel ports are assigned in the order they
1839 are specified on the command line, starting
1842 parport_init_mode= [HW,PPT]
1843 Configure VIA parallel port to operate in
1844 a specific mode. This is necessary on Pegasos
1845 computer where firmware has no options for setting
1846 up parallel port mode and sets it to spp.
1847 Currently this function knows 686a and 8231 chips.
1848 Format: [spp|ps2|epp|ecp|ecpepp]
1851 Halt all CPUs after the first oops has been printed for
1852 the specified number of seconds. This is to be used if
1853 your oopses keep scrolling off the screen.
1858 See header of drivers/block/paride/pcd.c.
1859 See also Documentation/blockdev/paride.txt.
1861 pci=option[,option...] [PCI] various PCI subsystem options:
1862 earlydump [X86] dump PCI config space before the kernel
1864 off [X86] don't probe for the PCI bus
1865 bios [X86-32] force use of PCI BIOS, don't access
1866 the hardware directly. Use this if your machine
1867 has a non-standard PCI host bridge.
1868 nobios [X86-32] disallow use of PCI BIOS, only direct
1869 hardware access methods are allowed. Use this
1870 if you experience crashes upon bootup and you
1871 suspect they are caused by the BIOS.
1872 conf1 [X86] Force use of PCI Configuration
1874 conf2 [X86] Force use of PCI Configuration
1876 noaer [PCIE] If the PCIEAER kernel config parameter is
1877 enabled, this kernel boot option can be used to
1878 disable the use of PCIE advanced error reporting.
1879 nodomains [PCI] Disable support for multiple PCI
1880 root domains (aka PCI segments, in ACPI-speak).
1881 nommconf [X86] Disable use of MMCONFIG for PCI
1883 check_enable_amd_mmconf [X86] check for and enable
1884 properly configured MMIO access to PCI
1885 config space on AMD family 10h CPU
1886 nomsi [MSI] If the PCI_MSI kernel config parameter is
1887 enabled, this kernel boot option can be used to
1888 disable the use of MSI interrupts system-wide.
1889 noioapicquirk [APIC] Disable all boot interrupt quirks.
1890 Safety option to keep boot IRQs enabled. This
1891 should never be necessary.
1892 ioapicreroute [APIC] Enable rerouting of boot IRQs to the
1893 primary IO-APIC for bridges that cannot disable
1894 boot IRQs. This fixes a source of spurious IRQs
1895 when the system masks IRQs.
1896 noioapicreroute [APIC] Disable workaround that uses the
1897 boot IRQ equivalent of an IRQ that connects to
1898 a chipset where boot IRQs cannot be disabled.
1899 The opposite of ioapicreroute.
1900 biosirq [X86-32] Use PCI BIOS calls to get the interrupt
1901 routing table. These calls are known to be buggy
1902 on several machines and they hang the machine
1903 when used, but on other computers it's the only
1904 way to get the interrupt routing table. Try
1905 this option if the kernel is unable to allocate
1906 IRQs or discover secondary PCI buses on your
1908 rom [X86] Assign address space to expansion ROMs.
1909 Use with caution as certain devices share
1910 address decoders between ROMs and other
1912 norom [X86] Do not assign address space to
1913 expansion ROMs that do not already have
1914 BIOS assigned address ranges.
1915 nobar [X86] Do not assign address space to the
1916 BARs that weren't assigned by the BIOS.
1917 irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be
1918 assigned automatically to PCI devices. You can
1919 make the kernel exclude IRQs of your ISA cards
1921 pirqaddr=0xAAAAA [X86] Specify the physical address
1922 of the PIRQ table (normally generated
1923 by the BIOS) if it is outside the
1924 F0000h-100000h range.
1925 lastbus=N [X86] Scan all buses thru bus #N. Can be
1926 useful if the kernel is unable to find your
1927 secondary buses and you want to tell it
1928 explicitly which ones they are.
1929 assign-busses [X86] Always assign all PCI bus
1930 numbers ourselves, overriding
1931 whatever the firmware may have done.
1932 usepirqmask [X86] Honor the possible IRQ mask stored
1933 in the BIOS $PIR table. This is needed on
1934 some systems with broken BIOSes, notably
1935 some HP Pavilion N5400 and Omnibook XE3
1936 notebooks. This will have no effect if ACPI
1937 IRQ routing is enabled.
1938 noacpi [X86] Do not use ACPI for IRQ routing
1939 or for PCI scanning.
1940 use_crs [X86] Use PCI host bridge window information
1941 from ACPI. On BIOSes from 2008 or later, this
1942 is enabled by default. If you need to use this,
1943 please report a bug.
1944 nocrs [X86] Ignore PCI host bridge windows from ACPI.
1945 If you need to use this, please report a bug.
1946 routeirq Do IRQ routing for all PCI devices.
1947 This is normally done in pci_enable_device(),
1948 so this option is a temporary workaround
1949 for broken drivers that don't call it.
1950 skip_isa_align [X86] do not align io start addr, so can
1951 handle more pci cards
1952 firmware [ARM] Do not re-enumerate the bus but instead
1953 just use the configuration from the
1954 bootloader. This is currently used on
1955 IXP2000 systems where the bus has to be
1956 configured a certain way for adjunct CPUs.
1957 noearly [X86] Don't do any early type 1 scanning.
1958 This might help on some broken boards which
1959 machine check when some devices' config space
1960 is read. But various workarounds are disabled
1961 and some IOMMU drivers will not work.
1962 bfsort Sort PCI devices into breadth-first order.
1963 This sorting is done to get a device
1964 order compatible with older (<= 2.4) kernels.
1965 nobfsort Don't sort PCI devices into breadth-first order.
1966 cbiosize=nn[KMG] The fixed amount of bus space which is
1967 reserved for the CardBus bridge's IO window.
1968 The default value is 256 bytes.
1969 cbmemsize=nn[KMG] The fixed amount of bus space which is
1970 reserved for the CardBus bridge's memory
1971 window. The default value is 64 megabytes.
1974 [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
1975 Specifies alignment and device to reassign
1976 aligned memory resources.
1977 If <order of align> is not specified,
1978 PAGE_SIZE is used as alignment.
1979 PCI-PCI bridge can be specified, if resource
1980 windows need to be expanded.
1981 ecrc= Enable/disable PCIe ECRC (transaction layer
1982 end-to-end CRC checking).
1983 bios: Use BIOS/firmware settings. This is the
1988 pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
1991 force Enable ASPM even on devices that claim not to support it.
1992 WARNING: Forcing ASPM on may cause system lockups.
1994 pcie_ports= [PCIE] PCIe ports handling:
1995 auto Ask the BIOS whether or not to use native PCIe services
1996 associated with PCIe ports (PME, hot-plug, AER). Use
1997 them only if that is allowed by the BIOS.
1998 native Use native PCIe services associated with PCIe ports
2000 compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
2003 pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
2004 nomsi Do not use MSI for native PCIe PME signaling (this makes
2005 all PCIe root ports use INTx for all services).
2007 pcmv= [HW,PCMCIA] BadgePAD 4
2010 See Documentation/blockdev/paride.txt.
2012 pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
2015 See arch/parisc/kernel/pdc_chassis.c
2017 percpu_alloc= Select which percpu first chunk allocator to use.
2018 Currently supported values are "embed" and "page".
2019 Archs may support subset or none of the selections.
2020 See comments in mm/percpu.c for details on each
2021 allocator. This parameter is primarily for debugging
2022 and performance comparison.
2025 See Documentation/blockdev/paride.txt.
2028 See Documentation/blockdev/paride.txt.
2030 pirq= [SMP,APIC] Manual mp-table setup
2031 See Documentation/x86/i386/IO-APIC.txt.
2033 plip= [PPT,NET] Parallel port network link
2034 Format: { parport<nr> | timid | 0 }
2035 See also Documentation/parport.txt.
2037 pmtmr= [X86] Manual setup of pmtmr I/O Port.
2038 Override pmtimer IOPort with a hex value.
2042 Enable PNP debug messages. This depends on the
2043 CONFIG_PNP_DEBUG_MESSAGES option.
2049 { on | off | curr | res | no-curr | no-res }
2052 [ISAPNP] Exclude IRQs for the autoconfiguration
2055 [ISAPNP] Exclude DMAs for the autoconfiguration
2057 pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
2058 Ranges are in pairs (I/O port base and size).
2061 [ISAPNP] Exclude memory regions for the
2063 Ranges are in pairs (memory base and size).
2065 ports= [IP_VS_FTP] IPVS ftp helper module
2067 Up to 8 (IP_VS_APP_MAX_PORTS) ports
2069 Format: <port>,<port>....
2071 print-fatal-signals=
2072 [KNL] debug: print fatal signals
2074 If enabled, warn about various signal handling
2075 related application anomalies: too many signals,
2076 too many POSIX.1 timers, fatal signals causing a
2079 If you hit the warning due to signal overflow,
2080 you might want to try "ulimit -i unlimited".
2084 printk.time= Show timing data prefixed to each printk message line
2085 Format: <bool> (1/Y/y=enable, 0/N/n=disable)
2087 processor.max_cstate= [HW,ACPI]
2088 Limit processor to maximum C-state
2089 max_cstate=9 overrides any DMI blacklist limit.
2091 processor.nocst [HW,ACPI]
2092 Ignore the _CST method to determine C-states,
2093 instead using the legacy FADT method
2095 profile= [KNL] Enable kernel profiling via /proc/profile
2096 Format: [schedule,]<number>
2097 Param: "schedule" - profile schedule points.
2098 Param: <number> - step/bucket size as a power of 2 for
2099 statistical time based profiling.
2100 Param: "sleep" - profile D-state sleeping (millisecs).
2101 Requires CONFIG_SCHEDSTATS
2102 Param: "kvm" - profile VM exits.
2104 prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
2106 See Documentation/blockdev/ramdisk.txt.
2108 psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
2109 probe for; one of (bare|imps|exps|lifebook|any).
2110 psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
2112 psmouse.resetafter= [HW,MOUSE]
2113 Try to reset the device after so many bad packets
2116 [HW,MOUSE] Set desired mouse resolution, in dpi.
2117 psmouse.smartscroll=
2118 [HW,MOUSE] Controls Logitech smartscroll autorepeat.
2119 0 = disabled, 1 = enabled (default).
2122 See Documentation/blockdev/paride.txt.
2125 [KNL] Number of legacy pty's. Overwrites compiled-in
2128 quiet [KNL] Disable most log messages
2133 See Documentation/md.txt.
2135 ramdisk_blocksize= [RAM]
2136 See Documentation/blockdev/ramdisk.txt.
2138 ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
2139 See Documentation/blockdev/ramdisk.txt.
2141 rcupdate.blimit= [KNL,BOOT]
2142 Set maximum number of finished RCU callbacks to process
2145 rcupdate.qhimark= [KNL,BOOT]
2146 Set threshold of queued
2147 RCU callbacks over which batch limiting is disabled.
2149 rcupdate.qlowmark= [KNL,BOOT]
2150 Set threshold of queued RCU callbacks below which
2151 batch limiting is re-enabled.
2155 Run specified binary instead of /init from the ramdisk,
2156 used for early userspace startup. See initrd.
2158 reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
2159 Format: <reboot_mode>[,<reboot_mode2>[,...]]
2160 See arch/*/kernel/reboot.c or arch/*/kernel/process.c
2163 [KNL, SMP] Set scheduler's default relax_domain_level.
2164 See Documentation/cgroups/cpusets.txt.
2166 reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
2168 reservetop= [X86-32]
2170 Reserves a hole at the top of the kernel virtual
2175 Set the amount of memory to reserve for BIOS at
2176 the bottom of the address space.
2178 reset_devices [KNL] Force drivers to reset the underlying device
2179 during initialization.
2182 Specify the partition device for software suspend
2184 resume_offset= [SWSUSP]
2185 Specify the offset from the beginning of the partition
2186 given by "resume=" at which the swap header is located,
2187 in <PAGE_SIZE> units (needed only for swap files).
2188 See Documentation/power/swsusp-and-swap-files.txt
2190 hibernate= [HIBERNATION]
2191 noresume Don't check if there's a hibernation image
2192 present during boot.
2193 nocompress Don't compress/decompress hibernation images.
2195 retain_initrd [RAM] Keep initrd memory after extraction
2197 rhash_entries= [KNL,NET]
2198 Set number of hash buckets for route cache
2200 riscom8= [HW,SERIAL]
2201 Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
2203 ro [KNL] Mount root device read-only on boot
2205 root= [KNL] Root filesystem
2207 rootdelay= [KNL] Delay (in seconds) to pause before attempting to
2208 mount the root filesystem
2210 rootflags= [KNL] Set root filesystem mount option string
2212 rootfstype= [KNL] Set root filesystem type
2214 rootwait [KNL] Wait (indefinitely) for root device to show up.
2215 Useful for devices that are detected asynchronously
2216 (e.g. USB and MMC devices).
2218 rw [KNL] Mount root device read-write on boot
2220 S [KNL] Run init in single mode
2223 See drivers/net/irda/sa1100_ir.c.
2225 sbni= [NET] Granch SBNI12 leased line adapter
2227 sched_debug [KNL] Enables verbose scheduler debug messages.
2229 security= [SECURITY] Choose a security module to enable at boot.
2230 If this boot parameter is not specified, only the first
2231 security module asking for security registration will be
2232 loaded. An invalid security module name will be treated
2233 as if no module has been chosen.
2235 selinux= [SELINUX] Disable or enable SELinux at boot time.
2236 Format: { "0" | "1" }
2237 See security/selinux/Kconfig help text.
2240 Default value is set via kernel config option.
2241 If enabled at boot time, /selinux/disable can be used
2242 later to disable prior to initial policy load.
2244 apparmor= [APPARMOR] Disable or enable AppArmor at boot time
2245 Format: { "0" | "1" }
2246 See security/apparmor/Kconfig help text
2249 Default value is set via kernel config option.
2251 serialnumber [BUGS=X86-32]
2254 Maximal number of shapers.
2256 show_msr= [x86] show boot-time MSR settings
2257 Format: { <integer> }
2258 Show boot-time (BIOS-initialized) MSR settings.
2259 The parameter means the number of CPUs to show,
2260 for example 1 means boot CPU only.
2267 slub_debug[=options[,slabs]] [MM, SLUB]
2268 Enabling slub_debug allows one to determine the
2269 culprit if slab objects become corrupted. Enabling
2270 slub_debug can create guard zones around objects and
2271 may poison objects when not in use. Also tracks the
2272 last alloc / free. For more information see
2273 Documentation/vm/slub.txt.
2275 slub_max_order= [MM, SLUB]
2276 Determines the maximum allowed order for slabs.
2277 A high setting may cause OOMs due to memory
2278 fragmentation. For more information see
2279 Documentation/vm/slub.txt.
2281 slub_min_objects= [MM, SLUB]
2282 The minimum number of objects per slab. SLUB will
2283 increase the slab order up to slub_max_order to
2284 generate a sufficiently large slab able to contain
2285 the number of objects indicated. The higher the number
2286 of objects the smaller the overhead of tracking slabs
2287 and the less frequently locks need to be acquired.
2288 For more information see Documentation/vm/slub.txt.
2290 slub_min_order= [MM, SLUB]
2291 Determines the mininum page order for slabs. Must be
2292 lower than slub_max_order.
2293 For more information see Documentation/vm/slub.txt.
2295 slub_nomerge [MM, SLUB]
2296 Disable merging of slabs with similar size. May be
2297 necessary if there is some reason to distinguish
2298 allocs to different slabs. Debug options disable
2299 merging on their own.
2300 For more information see Documentation/vm/slub.txt.
2303 Format: <io1>[,<io2>[,...,<io8>]]
2305 smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
2306 attempt to substitute SMP alternatives once at boot.
2308 smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
2309 smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
2310 smsc-ircc2.ircc_sir= [HW] SIR base I/O port
2311 smsc-ircc2.ircc_fir= [HW] FIR base I/O port
2312 smsc-ircc2.ircc_irq= [HW] IRQ line
2313 smsc-ircc2.ircc_dma= [HW] DMA channel
2314 smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
2315 0: Toshiba Satellite 1800 (GP data pin select)
2316 1: Fast pin select (default)
2320 [KNL] Should the soft-lockup detector generate panics.
2322 sonypi.*= [HW] Sony Programmable I/O Control Device driver
2323 See Documentation/sonypi.txt
2325 specialix= [HW,SERIAL] Specialix multi-serial port adapter
2326 See Documentation/serial/specialix.txt.
2328 spia_io_base= [HW,MTD]
2334 Enabled the stack tracer on boot up.
2338 Set the STI (builtin display/keyboard on the HP-PARISC
2339 machines) console (graphic card) which should be used
2340 as the initial boot-console.
2341 See also comment in drivers/video/console/sticore.c.
2344 See comment in drivers/video/console/sticore.c.
2347 Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
2349 sunrpc.min_resvport=
2350 sunrpc.max_resvport=
2352 SunRPC servers often require that client requests
2353 originate from a privileged port (i.e. a port in the
2354 range 0 < portnr < 1024).
2355 An administrator who wishes to reserve some of these
2356 ports for other uses may adjust the range that the
2357 kernel's sunrpc client considers to be privileged
2358 using these two parameters to set the minimum and
2359 maximum port values.
2363 Control how the NFS server code allocates CPUs to
2364 service thread pools. Depending on how many NICs
2365 you have and where their interrupts are bound, this
2366 option will affect which CPUs will do NFS serving.
2367 Note: this parameter cannot be changed while the
2368 NFS server is running.
2370 auto the server chooses an appropriate mode
2371 automatically using heuristics
2372 global a single global pool contains all CPUs
2373 percpu one pool for each CPU
2374 pernode one pool for each NUMA node (equivalent
2375 to global on non-NUMA machines)
2377 sunrpc.tcp_slot_table_entries=
2378 sunrpc.udp_slot_table_entries=
2380 Sets the upper limit on the number of simultaneous
2381 RPC calls that can be sent from the client to a
2382 server. Increasing these values may allow you to
2383 improve throughput, but will also increase the
2384 amount of memory reserved for use by the client.
2387 [KNL] Enable accounting of swap in memory resource
2388 controller if no parameter or 1 is given or disable
2389 it if 0 is given (See Documentation/cgroups/memory.txt)
2391 swiotlb= [IA-64] Number of I/O TLB slabs
2395 sysfs.deprecated=0|1 [KNL]
2396 Enable/disable old style sysfs layout for old udev
2397 on older distributions. When this option is enabled
2398 very new udev will not work anymore. When this option
2399 is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
2400 in older udev will not work anymore.
2401 Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
2402 the kernel configuration.
2404 sysrq_always_enabled
2406 Ignore sysrq setting - this boot parameter will
2407 neutralize any effect of /proc/sys/kernel/sysrq.
2408 Useful for debugging.
2412 test_suspend= [SUSPEND]
2413 Specify "mem" (for Suspend-to-RAM) or "standby" (for
2414 standby suspend) as the system sleep state to briefly
2415 enter during system startup. The system is woken from
2416 this state using a wakeup-capable RTC alarm.
2418 thash_entries= [KNL,NET]
2419 Set number of hash buckets for TCP connection
2421 thermal.act= [HW,ACPI]
2422 -1: disable all active trip points in all thermal zones
2423 <degrees C>: override all lowest active trip points
2425 thermal.crt= [HW,ACPI]
2426 -1: disable all critical trip points in all thermal zones
2427 <degrees C>: override all critical trip points
2429 thermal.nocrt= [HW,ACPI]
2430 Set to disable actions on ACPI thermal zone
2431 critical and hot trip points.
2433 thermal.off= [HW,ACPI]
2434 1: disable ACPI thermal control
2436 thermal.psv= [HW,ACPI]
2437 -1: disable all passive trip points
2438 <degrees C>: override all passive trip points to this
2441 thermal.tzp= [HW,ACPI]
2442 Specify global default ACPI thermal zone polling rate
2443 <deci-seconds>: poll all this frequency
2444 0: no polling (default)
2448 Specify if the kernel should make use of the cpu
2449 topology informations if the hardware supports these.
2450 The scheduler will make use of these informations and
2451 e.g. base its process migration decisions on it.
2456 tpm_suspend_pcr=[HW,TPM]
2457 Format: integer pcr id
2458 Specify that at suspend time, the tpm driver
2459 should extend the specified pcr with zeros,
2460 as a workaround for some chips which fail to
2461 flush the last written pcr on TPM_SaveState.
2462 This will guarantee that all the other pcrs
2465 trace_buf_size=nn[KMG]
2466 [FTRACE] will set tracing buffer size.
2468 trace_event=[event-list]
2469 [FTRACE] Set and start specified trace events in order
2470 to facilitate early boot debugging.
2471 See also Documentation/trace/events.txt
2473 tsc= Disable clocksource stability checks for TSC.
2475 [x86] reliable: mark tsc clocksource as reliable, this
2476 disables clocksource verification at runtime, as well
2477 as the stability checks done at bootup. Used to enable
2478 high-resolution timer mode on older hardware, and in
2479 virtualized environment.
2480 [x86] noirqtime: Do not use TSC to do irq accounting.
2481 Used to run time disable IRQ_TIME_ACCOUNTING on any
2482 platforms where RDTSC is slow and this accounting
2485 turbografx.map[2|3]= [HW,JOY]
2486 TurboGraFX parallel port interface
2488 <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
2489 See also Documentation/input/joystick-parport.txt
2491 uhash_entries= [KNL,NET]
2492 Set number of hash buckets for UDP/UDP-Lite connections
2495 [USB] Ignore overcurrent events (default N).
2496 Some badly-designed motherboards generate lots of
2497 bogus events, for ports that aren't wired to
2498 anything. Set this parameter to avoid log spamming.
2499 Note that genuine overcurrent events won't be
2504 Set unknown_nmi_panic=1 early on boot.
2506 usbcore.autosuspend=
2507 [USB] The autosuspend time delay (in seconds) used
2508 for newly-detected USB devices (default 2). This
2509 is the time required before an idle device will be
2510 autosuspended. Devices for which the delay is set
2511 to a negative value won't be autosuspended at all.
2513 usbcore.usbfs_snoop=
2514 [USB] Set to log all usbfs traffic (default 0 = off).
2516 usbcore.blinkenlights=
2517 [USB] Set to cycle leds on hubs (default 0 = off).
2519 usbcore.old_scheme_first=
2520 [USB] Start with the old device initialization
2521 scheme (default 0 = off).
2523 usbcore.use_both_schemes=
2524 [USB] Try the other device initialization scheme
2525 if the first one fails (default 1 = enabled).
2527 usbcore.initial_descriptor_timeout=
2528 [USB] Specifies timeout for the initial 64-byte
2529 USB_REQ_GET_DESCRIPTOR request in milliseconds
2530 (default 5000 = 5.0 seconds).
2533 [USBHID] The interval which mice are to be polled at.
2535 usb-storage.delay_use=
2536 [UMS] The delay in seconds before a new device is
2537 scanned for Logical Units (default 5).
2540 [UMS] A list of quirks entries to supplement or
2541 override the built-in unusual_devs list. List
2542 entries are separated by commas. Each entry has
2543 the form VID:PID:Flags where VID and PID are Vendor
2544 and Product ID values (4-digit hex numbers) and
2545 Flags is a set of characters, each corresponding
2546 to a common usb-storage quirk flag as follows:
2547 a = SANE_SENSE (collect more than 18 bytes
2549 b = BAD_SENSE (don't collect more than 18
2550 bytes of sense data);
2551 c = FIX_CAPACITY (decrease the reported
2552 device capacity by one sector);
2553 h = CAPACITY_HEURISTICS (decrease the
2554 reported device capacity by one
2555 sector if the number is odd);
2556 i = IGNORE_DEVICE (don't bind to this
2558 l = NOT_LOCKABLE (don't try to lock and
2559 unlock ejectable media);
2560 m = MAX_SECTORS_64 (don't transfer more
2561 than 64 sectors = 32 KB at a time);
2562 o = CAPACITY_OK (accept the capacity
2563 reported by the device);
2564 r = IGNORE_RESIDUE (the device reports
2565 bogus residue values);
2566 s = SINGLE_LUN (the device has only one
2568 w = NO_WP_DETECT (don't test whether the
2569 medium is write-protected).
2570 Example: quirks=0419:aaf5:rl,0421:0433:rc
2573 [X86] Flags controlling user PTE allocations.
2575 nohigh = do not allocate PTE pages in
2576 HIGHMEM regardless of setting
2580 vdso=2: enable compat VDSO (default with COMPAT_VDSO)
2581 vdso=1: enable VDSO (default)
2582 vdso=0: disable VDSO mapping
2585 vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
2586 vdso32=1: enable 32-bit VDSO (default)
2587 vdso32=0: disable 32-bit VDSO mapping
2590 vector=percpu: enable percpu vector domain
2592 video= [FB] Frame buffer configuration
2593 See Documentation/fb/modedb.txt.
2595 vga= [BOOT,X86-32] Select a particular video mode
2596 See Documentation/x86/boot.txt and
2597 Documentation/svga.txt.
2598 Use vga=ask for menu.
2599 This is actually a boot loader parameter; the value is
2600 passed to the kernel using a special protocol.
2602 vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
2603 size of <nn>. This can be used to increase the
2604 minimum size (128MB on x86). It can also be used to
2605 decrease the size and leave more room for directly
2608 vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
2611 vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
2614 vmpoff= [KNL,S390] Perform z/VM CP command after power off.
2617 vt.cur_default= [VT] Default cursor shape.
2618 Format: 0xCCBBAA, where AA, BB, and CC are the same as
2619 the parameters of the <Esc>[?A;B;Cc escape sequence;
2620 see VGA-softcursor.txt. Default: 2 = underline.
2622 vt.default_blu= [VT]
2623 Format: <blue0>,<blue1>,<blue2>,...,<blue15>
2624 Change the default blue palette of the console.
2625 This is a 16-member array composed of values
2628 vt.default_grn= [VT]
2629 Format: <green0>,<green1>,<green2>,...,<green15>
2630 Change the default green palette of the console.
2631 This is a 16-member array composed of values
2634 vt.default_red= [VT]
2635 Format: <red0>,<red1>,<red2>,...,<red15>
2636 Change the default red palette of the console.
2637 This is a 16-member array composed of values
2643 Set system-wide default UTF-8 mode for all tty's.
2644 Default is 1, i.e. UTF-8 mode is enabled for all
2645 newly opened terminals.
2647 vt.global_cursor_default=
2650 Set system-wide default for whether a cursor
2651 is shown on new VTs. Default is -1,
2652 i.e. cursors will be created by default unless
2653 overridden by individual drivers. 0 will hide
2654 cursors, 1 will display them.
2656 watchdog timers [HW,WDT] For information on watchdog timers,
2657 see Documentation/watchdog/watchdog-parameters.txt
2658 or other driver-specific files in the
2659 Documentation/watchdog/ directory.
2661 x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
2662 default x2apic cluster mode on platforms
2665 x86_mrst_timer= [X86-32,APBT]
2666 Choose timer option for x86 Moorestown MID platform.
2667 Two valid options are apbt timer only and lapic timer
2668 plus one apbt timer for broadcast timer.
2669 x86_mrst_timer=apbt_only | lapic_and_apbt
2671 xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
2672 xd_geo= See header of drivers/block/xd.c.
2674 xen_emul_unplug= [HW,X86,XEN]
2675 Unplug Xen emulated devices
2676 Format: [unplug0,][unplug1]
2677 ide-disks -- unplug primary master IDE devices
2678 aux-ide-disks -- unplug non-primary-master IDE devices
2679 nics -- unplug network devices
2680 all -- unplug all emulated devices (NICs and IDE disks)
2681 unnecessary -- unplugging emulated devices is
2682 unnecessary even if the host did not respond to
2684 never -- do not unplug even if version check succeeds
2686 xirc2ps_cs= [NET,PCMCIA]
2688 <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
2690 ______________________________________________________________________
2694 Add more DRM drivers.
git.openpandora.org / pandora-kernel.git / blob