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- Kernel Parameters
- ~~~~~~~~~~~~~~~~~
- The following is a consolidated list of the kernel parameters as implemented
- (mostly) by the __setup() macro and sorted into English Dictionary order
- (defined as ignoring all punctuation and sorting digits before letters in a
- case insensitive manner), and with descriptions where known.
- Module parameters for loadable modules are specified only as the
- parameter name with optional '=' and value as appropriate, such as:
- modprobe usbcore blinkenlights=1
- Module parameters for modules that are built into the kernel image
- are specified on the kernel command line with the module name plus
- '.' plus parameter name, with '=' and value if appropriate, such as:
- usbcore.blinkenlights=1
- This document may not be entirely up to date and comprehensive. The command
- "modinfo -p ${modulename}" shows a current list of all parameters of a loadable
- module. Loadable modules, after being loaded into the running kernel, also
- reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
- parameters may be changed at runtime by the command
- "echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
- The parameters listed below are only valid if certain kernel build options were
- enabled and if respective hardware is present. The text in square brackets at
- the beginning of each description states the restrictions within which a
- parameter is applicable:
- ACPI ACPI support is enabled.
- AGP AGP (Accelerated Graphics Port) is enabled.
- ALSA ALSA sound support is enabled.
- APIC APIC support is enabled.
- APM Advanced Power Management support is enabled.
- AVR32 AVR32 architecture is enabled.
- AX25 Appropriate AX.25 support is enabled.
- BLACKFIN Blackfin architecture is enabled.
- DRM Direct Rendering Management support is enabled.
- EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
- EFI EFI Partitioning (GPT) is enabled
- EIDE EIDE/ATAPI support is enabled.
- FB The frame buffer device is enabled.
- HW Appropriate hardware is enabled.
- IA-64 IA-64 architecture is enabled.
- IOSCHED More than one I/O scheduler is enabled.
- IP_PNP IP DHCP, BOOTP, or RARP is enabled.
- ISAPNP ISA PnP code is enabled.
- ISDN Appropriate ISDN support is enabled.
- JOY Appropriate joystick support is enabled.
- LIBATA Libata driver is enabled
- LP Printer support is enabled.
- LOOP Loopback device support is enabled.
- M68k M68k architecture is enabled.
- These options have more detailed description inside of
- Documentation/m68k/kernel-options.txt.
- MCA MCA bus support is enabled.
- MDA MDA console support is enabled.
- MOUSE Appropriate mouse support is enabled.
- MSI Message Signaled Interrupts (PCI).
- MTD MTD (Memory Technology Device) support is enabled.
- NET Appropriate network support is enabled.
- NUMA NUMA support is enabled.
- GENERIC_TIME The generic timeofday code is enabled.
- NFS Appropriate NFS support is enabled.
- OSS OSS sound support is enabled.
- PV_OPS A paravirtualized kernel is enabled.
- PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
- PARISC The PA-RISC architecture is enabled.
- PCI PCI bus support is enabled.
- PCIE PCI Express support is enabled.
- PCMCIA The PCMCIA subsystem is enabled.
- PNP Plug & Play support is enabled.
- PPC PowerPC architecture is enabled.
- PPT Parallel port support is enabled.
- PS2 Appropriate PS/2 support is enabled.
- RAM RAM disk support is enabled.
- ROOTPLUG The example Root Plug LSM is enabled.
- S390 S390 architecture is enabled.
- SCSI Appropriate SCSI support is enabled.
- A lot of drivers has their options described inside of
- Documentation/scsi/.
- SECURITY Different security models are enabled.
- SELINUX SELinux support is enabled.
- SERIAL Serial support is enabled.
- SH SuperH architecture is enabled.
- SMP The kernel is an SMP kernel.
- SPARC Sparc architecture is enabled.
- SWSUSP Software suspend (hibernation) is enabled.
- SUSPEND System suspend states are enabled.
- TS Appropriate touchscreen support is enabled.
- USB USB support is enabled.
- USBHID USB Human Interface Device support is enabled.
- V4L Video For Linux support is enabled.
- VGA The VGA console has been enabled.
- VT Virtual terminal support is enabled.
- WDT Watchdog support is enabled.
- XT IBM PC/XT MFM hard disk support is enabled.
- X86-32 X86-32, aka i386 architecture is enabled.
- X86-64 X86-64 architecture is enabled.
- More X86-64 boot options can be found in
- Documentation/x86_64/boot-options.txt .
- In addition, the following text indicates that the option:
- BUGS= Relates to possible processor bugs on the said processor.
- KNL Is a kernel start-up parameter.
- BOOT Is a boot loader parameter.
- Parameters denoted with BOOT are actually interpreted by the boot
- loader, and have no meaning to the kernel directly.
- Do not modify the syntax of boot loader parameters without extreme
- need or coordination with <Documentation/i386/boot.txt>.
- There are also arch-specific kernel-parameters not documented here.
- See for example <Documentation/x86_64/boot-options.txt>.
- Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
- a trailing = on the name of any parameter states that that parameter will
- be entered as an environment variable, whereas its absence indicates that
- it will appear as a kernel argument readable via /proc/cmdline by programs
- running once the system is up.
- The number of kernel parameters is not limited, but the length of the
- complete command line (parameters including spaces etc.) is limited to
- a fixed number of characters. This limit depends on the architecture
- and is between 256 and 4096 characters. It is defined in the file
- ./include/asm/setup.h as COMMAND_LINE_SIZE.
- acpi= [HW,ACPI,X86-64,i386]
- Advanced Configuration and Power Interface
- Format: { force | off | ht | strict | noirq }
- force -- enable ACPI if default was off
- off -- disable ACPI if default was on
- noirq -- do not use ACPI for IRQ routing
- ht -- run only enough ACPI to enable Hyper Threading
- strict -- Be less tolerant of platforms that are not
- strictly ACPI specification compliant.
- See also Documentation/power/pm.txt, pci=noacpi
- acpi_apic_instance= [ACPI, IOAPIC]
- Format: <int>
- 2: use 2nd APIC table, if available
- 1,0: use 1st APIC table
- default: 0
- acpi_sleep= [HW,ACPI] Sleep options
- Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering }
- See Documentation/power/video.txt for s3_bios and s3_mode.
- s3_beep is for debugging; it makes the PC's speaker beep
- as soon as the kernel's real-mode entry point is called.
- s4_nohwsig prevents ACPI hardware signature from being
- used during resume from hibernation.
- old_ordering causes the ACPI 1.0 ordering of the _PTS
- control method, wrt putting devices into low power
- states, to be enforced (the ACPI 2.0 ordering of _PTS is
- used by default).
- acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
- Format: { level | edge | high | low }
- acpi_irq_balance [HW,ACPI]
- ACPI will balance active IRQs
- default in APIC mode
- acpi_irq_nobalance [HW,ACPI]
- ACPI will not move active IRQs (default)
- default in PIC mode
- acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
- use by PCI
- Format: <irq>,<irq>...
- acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
- Format: <irq>,<irq>...
- acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
- acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
- Format: To spoof as Windows 98: ="Microsoft Windows"
- acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
- acpi_osi="string1" # add string1 -- only one string
- acpi_osi="!string2" # remove built-in string2
- acpi_osi= # disable all strings
- acpi_serialize [HW,ACPI] force serialization of AML methods
- acpi_skip_timer_override [HW,ACPI]
- Recognize and ignore IRQ0/pin2 Interrupt Override.
- For broken nForce2 BIOS resulting in XT-PIC timer.
- acpi_use_timer_override [HW,ACPI}
- Use timer override. For some broken Nvidia NF5 boards
- that require a timer override, but don't have
- HPET
- acpi.debug_layer= [HW,ACPI]
- Format: <int>
- Each bit of the <int> indicates an ACPI debug layer,
- 1: enable, 0: disable. It is useful for boot time
- debugging. After system has booted up, it can be set
- via /sys/module/acpi/parameters/debug_layer.
- CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
- Available bits (add the numbers together) to enable debug output
- for specific parts of the ACPI subsystem:
- 0x01 utilities 0x02 hardware 0x04 events 0x08 tables
- 0x10 namespace 0x20 parser 0x40 dispatcher
- 0x80 executer 0x100 resources 0x200 acpica debugger
- 0x400 os services 0x800 acpica disassembler.
- The number can be in decimal or prefixed with 0x in hex.
- Warning: Many of these options can produce a lot of
- output and make your system unusable. Be very careful.
- acpi.debug_level= [HW,ACPI]
- Format: <int>
- Each bit of the <int> indicates an ACPI debug level,
- 1: enable, 0: disable. It is useful for boot time
- debugging. After system has booted up, it can be set
- via /sys/module/acpi/parameters/debug_level.
- CONFIG_ACPI_DEBUG must be enabled for this to produce any output.
- Available bits (add the numbers together) to enable different
- debug output levels of the ACPI subsystem:
- 0x01 error 0x02 warn 0x04 init 0x08 debug object
- 0x10 info 0x20 init names 0x40 parse 0x80 load
- 0x100 dispatch 0x200 execute 0x400 names 0x800 operation region
- 0x1000 bfield 0x2000 tables 0x4000 values 0x8000 objects
- 0x10000 resources 0x20000 user requests 0x40000 package.
- The number can be in decimal or prefixed with 0x in hex.
- Warning: Many of these options can produce a lot of
- output and make your system unusable. Be very careful.
- acpi_pm_good [X86-32,X86-64]
- Override the pmtimer bug detection: force the kernel
- to assume that this machine's pmtimer latches its value
- and always returns good values.
- agp= [AGP]
- { off | try_unsupported }
- off: disable AGP support
- try_unsupported: try to drive unsupported chipsets
- (may crash computer or cause data corruption)
- enable_timer_pin_1 [i386,x86-64]
- Enable PIN 1 of APIC timer
- Can be useful to work around chipset bugs
- (in particular on some ATI chipsets).
- The kernel tries to set a reasonable default.
- disable_timer_pin_1 [i386,x86-64]
- Disable PIN 1 of APIC timer
- Can be useful to work around chipset bugs.
- ad1848= [HW,OSS]
- Format: <io>,<irq>,<dma>,<dma2>,<type>
- advansys= [HW,SCSI]
- See header of drivers/scsi/advansys.c.
- advwdt= [HW,WDT] Advantech WDT
- Format: <iostart>,<iostop>
- aedsp16= [HW,OSS] Audio Excel DSP 16
- Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
- See also header of sound/oss/aedsp16.c.
- aha152x= [HW,SCSI]
- See Documentation/scsi/aha152x.txt.
- aha1542= [HW,SCSI]
- Format: <portbase>[,<buson>,<busoff>[,<dmaspeed>]]
- aic7xxx= [HW,SCSI]
- See Documentation/scsi/aic7xxx.txt.
- aic79xx= [HW,SCSI]
- See Documentation/scsi/aic79xx.txt.
- amd_iommu= [HW,X86-84]
- Pass parameters to the AMD IOMMU driver in the system.
- Possible values are:
- isolate - enable device isolation (each device, as far
- as possible, will get its own protection
- domain)
- fullflush - enable flushing of IO/TLB entries when
- they are unmapped. Otherwise they are
- flushed before they will be reused, which
- is a lot of faster
- amd_iommu_size= [HW,X86-64]
- Define the size of the aperture for the AMD IOMMU
- driver. Possible values are:
- '32M', '64M' (default), '128M', '256M', '512M', '1G'
- amijoy.map= [HW,JOY] Amiga joystick support
- Map of devices attached to JOY0DAT and JOY1DAT
- Format: <a>,<b>
- See also Documentation/kernel/input/joystick.txt
- analog.map= [HW,JOY] Analog joystick and gamepad support
- Specifies type or capabilities of an analog joystick
- connected to one of 16 gameports
- Format: <type1>,<type2>,..<type16>
- apc= [HW,SPARC]
- Power management functions (SPARCstation-4/5 + deriv.)
- Format: noidle
- Disable APC CPU standby support. SPARCstation-Fox does
- not play well with APC CPU idle - disable it if you have
- APC and your system crashes randomly.
- apic= [APIC,i386] Advanced Programmable Interrupt Controller
- Change the output verbosity whilst booting
- Format: { quiet (default) | verbose | debug }
- Change the amount of debugging information output
- when initialising the APIC and IO-APIC components.
- apm= [APM] Advanced Power Management
- See header of arch/x86/kernel/apm_32.c.
- arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
- Format: <io>,<irq>,<nodeID>
- ataflop= [HW,M68k]
- atarimouse= [HW,MOUSE] Atari Mouse
- atascsi= [HW,SCSI] Atari SCSI
- atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
- EzKey and similar keyboards
- atkbd.reset= [HW] Reset keyboard during initialization
- atkbd.set= [HW] Select keyboard code set
- Format: <int> (2 = AT (default), 3 = PS/2)
- atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
- keyboards
- atkbd.softraw= [HW] Choose between synthetic and real raw mode
- Format: <bool> (0 = real, 1 = synthetic (default))
- atkbd.softrepeat= [HW]
- Use software keyboard repeat
- autotest [IA64]
- baycom_epp= [HW,AX25]
- Format: <io>,<mode>
- baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
- Format: <io>,<mode>
- See header of drivers/net/hamradio/baycom_par.c.
- baycom_ser_fdx= [HW,AX25]
- BayCom Serial Port AX.25 Modem (Full Duplex Mode)
- Format: <io>,<irq>,<mode>[,<baud>]
- See header of drivers/net/hamradio/baycom_ser_fdx.c.
- baycom_ser_hdx= [HW,AX25]
- BayCom Serial Port AX.25 Modem (Half Duplex Mode)
- Format: <io>,<irq>,<mode>
- See header of drivers/net/hamradio/baycom_ser_hdx.c.
- boot_delay= Milliseconds to delay each printk during boot.
- Values larger than 10 seconds (10000) are changed to
- no delay (0).
- Format: integer
- bootmem_debug [KNL] Enable bootmem allocator debug messages.
- bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
- bttv.radio= Most important insmod options are available as
- kernel args too.
- bttv.pll= See Documentation/video4linux/bttv/Insmod-options
- bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
- BusLogic= [HW,SCSI]
- See drivers/scsi/BusLogic.c, comment before function
- BusLogic_ParseDriverOptions().
- c101= [NET] Moxa C101 synchronous serial card
- cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
- Sometimes CPU hardware bugs make them report the cache
- size incorrectly. The kernel will attempt work arounds
- to fix known problems, but for some CPUs it is not
- possible to determine what the correct size should be.
- This option provides an override for these situations.
- security= [SECURITY] Choose a security module to enable at boot.
- If this boot parameter is not specified, only the first
- security module asking for security registration will be
- loaded. An invalid security module name will be treated
- as if no module has been chosen.
- capability.disable=
- [SECURITY] Disable capabilities. This would normally
- be used only if an alternative security model is to be
- configured. Potentially dangerous and should only be
- used if you are entirely sure of the consequences.
- ccw_timeout_log [S390]
- See Documentation/s390/CommonIO for details.
- cgroup_disable= [KNL] Disable a particular controller
- Format: {name of the controller(s) to disable}
- {Currently supported controllers - "memory"}
- checkreqprot [SELINUX] Set initial checkreqprot flag value.
- Format: { "0" | "1" }
- See security/selinux/Kconfig help text.
- 0 -- check protection applied by kernel (includes
- any implied execute protection).
- 1 -- check protection requested by application.
- Default value is set via a kernel config option.
- Value can be changed at runtime via
- /selinux/checkreqprot.
- cio_ignore= [S390]
- See Documentation/s390/CommonIO for details.
- clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
- [Deprecated]
- Forces specified clocksource (if available) to be used
- when calculating gettimeofday(). If specified
- clocksource is not available, it defaults to PIT.
- Format: { pit | tsc | cyclone | pmtmr }
- clocksource= [GENERIC_TIME] Override the default clocksource
- Format: <string>
- Override the default clocksource and use the clocksource
- with the name specified.
- Some clocksource names to choose from, depending on
- the platform:
- [all] jiffies (this is the base, fallback clocksource)
- [ACPI] acpi_pm
- [ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
- pxa_timer,timer3,32k_counter,timer0_1
- [AVR32] avr32
- [X86-32] pit,hpet,tsc,vmi-timer;
- scx200_hrt on Geode; cyclone on IBM x440
- [MIPS] MIPS
- [PARISC] cr16
- [S390] tod
- [SH] SuperH
- [SPARC64] tick
- [X86-64] hpet,tsc
- clearcpuid=BITNUM [X86]
- Disable CPUID feature X for the kernel. See
- include/asm-x86/cpufeature.h for the valid bit numbers.
- Note the Linux specific bits are not necessarily
- stable over kernel options, but the vendor specific
- ones should be.
- Also note that user programs calling CPUID directly
- or using the feature without checking anything
- will still see it. This just prevents it from
- being used by the kernel or shown in /proc/cpuinfo.
- Also note the kernel might malfunction if you disable
- some critical bits.
- code_bytes [IA32/X86_64] How many bytes of object code to print
- in an oops report.
- Range: 0 - 8192
- Default: 64
- hpet= [X86-32,HPET] option to control HPET usage
- Format: { enable (default) | disable | force }
- disable: disable HPET and use PIT instead
- force: allow force enabled of undocumented chips (ICH4,
- VIA, nVidia)
- com20020= [HW,NET] ARCnet - COM20020 chipset
- Format:
- <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
- com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
- Format: <io>[,<irq>]
- com90xx= [HW,NET]
- ARCnet - COM90xx chipset (memory-mapped buffers)
- Format: <io>[,<irq>[,<memstart>]]
- condev= [HW,S390] console device
- conmode=
- console= [KNL] Output console device and options.
- tty<n> Use the virtual console device <n>.
- ttyS<n>[,options]
- ttyUSB0[,options]
- Use the specified serial port. The options are of
- the form "bbbbpnf", where "bbbb" is the baud rate,
- "p" is parity ("n", "o", or "e"), "n" is number of
- bits, and "f" is flow control ("r" for RTS or
- omit it). Default is "9600n8".
- See Documentation/serial-console.txt for more
- information. See
- Documentation/networking/netconsole.txt for an
- alternative.
- uart[8250],io,<addr>[,options]
- uart[8250],mmio,<addr>[,options]
- Start an early, polled-mode console on the 8250/16550
- UART at the specified I/O port or MMIO address,
- switching to the matching ttyS device later. The
- options are the same as for ttyS, above.
- If the device connected to the port is not a TTY but a braille
- device, prepend "brl," before the device type, for instance
- console=brl,ttyS0
- For now, only VisioBraille is supported.
- earlycon= [KNL] Output early console device and options.
- uart[8250],io,<addr>[,options]
- uart[8250],mmio,<addr>[,options]
- Start an early, polled-mode console on the 8250/16550
- UART at the specified I/O port or MMIO address.
- The options are the same as for ttyS, above.
- no_console_suspend
- [HW] Never suspend the console
- Disable suspending of consoles during suspend and
- hibernate operations. Once disabled, debugging
- messages can reach various consoles while the rest
- of the system is being put to sleep (ie, while
- debugging driver suspend/resume hooks). This may
- not work reliably with all consoles, but is known
- to work with serial and VGA consoles.
- cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
- Format:
- <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
- crashkernel=nn[KMG]@ss[KMG]
- [KNL] Reserve a chunk of physical memory to
- hold a kernel to switch to with kexec on panic.
- crashkernel=range1:size1[,range2:size2,...][@offset]
- [KNL] Same as above, but depends on the memory
- in the running system. The syntax of range is
- start-[end] where start and end are both
- a memory unit (amount[KMG]). See also
- Documentation/kdump/kdump.txt for a example.
- cs4232= [HW,OSS]
- Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
- cs89x0_dma= [HW,NET]
- Format: <dma>
- cs89x0_media= [HW,NET]
- Format: { rj45 | aui | bnc }
- dasd= [HW,NET]
- See header of drivers/s390/block/dasd_devmap.c.
- db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
- (one device per port)
- Format: <port#>,<type>
- See also Documentation/input/joystick-parport.txt
- debug [KNL] Enable kernel debugging (events log level).
- debug_locks_verbose=
- [KNL] verbose self-tests
- Format=<0|1>
- Print debugging info while doing the locking API
- self-tests.
- We default to 0 (no extra messages), setting it to
- 1 will print _a lot_ more information - normally
- only useful to kernel developers.
- debug_objects [KNL] Enable object debugging
- debugpat [X86] Enable PAT debugging
- decnet.addr= [HW,NET]
- Format: <area>[,<node>]
- See also Documentation/networking/decnet.txt.
- vt.default_blu= [VT]
- Format: <blue0>,<blue1>,<blue2>,...,<blue15>
- Change the default blue palette of the console.
- This is a 16-member array composed of values
- ranging from 0-255.
- vt.default_grn= [VT]
- Format: <green0>,<green1>,<green2>,...,<green15>
- Change the default green palette of the console.
- This is a 16-member array composed of values
- ranging from 0-255.
- vt.default_red= [VT]
- Format: <red0>,<red1>,<red2>,...,<red15>
- Change the default red palette of the console.
- This is a 16-member array composed of values
- ranging from 0-255.
- vt.default_utf8=
- [VT]
- Format=<0|1>
- Set system-wide default UTF-8 mode for all tty's.
- Default is 1, i.e. UTF-8 mode is enabled for all
- newly opened terminals.
- dhash_entries= [KNL]
- Set number of hash buckets for dentry cache.
- digi= [HW,SERIAL]
- IO parameters + enable/disable command.
- digiepca= [HW,SERIAL]
- See drivers/char/README.epca and
- Documentation/digiepca.txt.
- disable_mtrr_cleanup [X86]
- enable_mtrr_cleanup [X86]
- The kernel tries to adjust MTRR layout from continuous
- to discrete, to make X server driver able to add WB
- entry later. This parameter enables/disables that.
- mtrr_chunk_size=nn[KMG] [X86]
- used for mtrr cleanup. It is largest continous chunk
- that could hold holes aka. UC entries.
- mtrr_gran_size=nn[KMG] [X86]
- Used for mtrr cleanup. It is granularity of mtrr block.
- Default is 1.
- Large value could prevent small alignment from
- using up MTRRs.
- mtrr_spare_reg_nr=n [X86]
- Format: <integer>
- Range: 0,7 : spare reg number
- Default : 1
- Used for mtrr cleanup. It is spare mtrr entries number.
- Set to 2 or more if your graphical card needs more.
- disable_mtrr_trim [X86, Intel and AMD only]
- By default the kernel will trim any uncacheable
- memory out of your available memory pool based on
- MTRR settings. This parameter disables that behavior,
- possibly causing your machine to run very slowly.
- dmasound= [HW,OSS] Sound subsystem buffers
- dscc4.setup= [NET]
- dtc3181e= [HW,SCSI]
- earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
- earlyprintk=vga
- earlyprintk=serial[,ttySn[,baudrate]]
- Append ",keep" to not disable it when the real console
- takes over.
- Only vga or serial at a time, not both.
- Currently only ttyS0 and ttyS1 are supported.
- Interaction with the standard serial driver is not
- very good.
- The VGA output is eventually overwritten by the real
- console.
- eata= [HW,SCSI]
- edd= [EDD]
- Format: {"off" | "on" | "skip[mbr]"}
- eisa_irq_edge= [PARISC,HW]
- See header of drivers/parisc/eisa.c.
- elanfreq= [X86-32]
- See comment before function elanfreq_setup() in
- arch/x86/kernel/cpu/cpufreq/elanfreq.c.
- elevator= [IOSCHED]
- Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
- See Documentation/block/as-iosched.txt and
- Documentation/block/deadline-iosched.txt for details.
- elfcorehdr= [X86-32, X86_64]
- Specifies physical address of start of kernel core
- image elf header. Generally kexec loader will
- pass this option to capture kernel.
- See Documentation/kdump/kdump.txt for details.
- enforcing [SELINUX] Set initial enforcing status.
- Format: {"0" | "1"}
- See security/selinux/Kconfig help text.
- 0 -- permissive (log only, no denials).
- 1 -- enforcing (deny and log).
- Default value is 0.
- Value can be changed at runtime via /selinux/enforce.
- es1371= [HW,OSS]
- Format: <spdif>,[<nomix>,[<amplifier>]]
- See also header of sound/oss/es1371.c.
- ether= [HW,NET] Ethernet cards parameters
- This option is obsoleted by the "netdev=" option, which
- has equivalent usage. See its documentation for details.
- eurwdt= [HW,WDT] Eurotech CPU-1220/1410 onboard watchdog.
- Format: <io>[,<irq>]
- failslab=
- fail_page_alloc=
- fail_make_request=[KNL]
- General fault injection mechanism.
- Format: <interval>,<probability>,<space>,<times>
- See also /Documentation/fault-injection/.
- fd_mcs= [HW,SCSI]
- See header of drivers/scsi/fd_mcs.c.
- fdomain= [HW,SCSI]
- See header of drivers/scsi/fdomain.c.
- floppy= [HW]
- See Documentation/floppy.txt.
- force_pal_cache_flush
- [IA-64] Avoid check_sal_cache_flush which may hang on
- buggy SAL_CACHE_FLUSH implementations. Using this
- parameter will force ia64_sal_cache_flush to call
- ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
- gamecon.map[2|3]=
- [HW,JOY] Multisystem joystick and NES/SNES/PSX pad
- support via parallel port (up to 5 devices per port)
- Format: <port#>,<pad1>,<pad2>,<pad3>,<pad4>,<pad5>
- See also Documentation/input/joystick-parport.txt
- gamma= [HW,DRM]
- gart_fix_e820= [X86_64] disable the fix e820 for K8 GART
- Format: off | on
- default: on
- gdth= [HW,SCSI]
- See header of drivers/scsi/gdth.c.
- gpt [EFI] Forces disk with valid GPT signature but
- invalid Protective MBR to be treated as GPT.
- gvp11= [HW,SCSI]
- hashdist= [KNL,NUMA] Large hashes allocated during boot
- are distributed across NUMA nodes. Defaults on
- for IA-64, off otherwise.
- Format: 0 | 1 (for off | on)
- hcl= [IA-64] SGI's Hardware Graph compatibility layer
- hd= [EIDE] (E)IDE hard drive subsystem geometry
- Format: <cyl>,<head>,<sect>
- highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact
- size of <nn>. This works even on boxes that have no
- highmem otherwise. This also works to reduce highmem
- size on bigger boxes.
- highres= [KNL] Enable/disable high resolution timer mode.
- Valid parameters: "on", "off"
- Default: "on"
- hisax= [HW,ISDN]
- See Documentation/isdn/README.HiSax.
- hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
- hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
- On x86-64 and powerpc, this option can be specified
- multiple times interleaved with hugepages= to reserve
- huge pages of different sizes. Valid pages sizes on
- x86-64 are 2M (when the CPU supports "pse") and 1G
- (when the CPU supports the "pdpe1gb" cpuinfo flag)
- Note that 1GB pages can only be allocated at boot time
- using hugepages= and not freed afterwards.
- default_hugepagesz=
- [same as hugepagesz=] The size of the default
- HugeTLB page size. This is the size represented by
- the legacy /proc/ hugepages APIs, used for SHM, and
- default size when mounting hugetlbfs filesystems.
- Defaults to the default architecture's huge page size
- if not specified.
- i8042.direct [HW] Put keyboard port into non-translated mode
- i8042.dumbkbd [HW] Pretend that controller can only read data from
- keyboard and cannot control its state
- (Don't attempt to blink the leds)
- i8042.noaux [HW] Don't check for auxiliary (== mouse) port
- i8042.nokbd [HW] Don't check/create keyboard port
- i8042.noloop [HW] Disable the AUX Loopback command while probing
- for the AUX port
- i8042.nomux [HW] Don't check presence of an active multiplexing
- controller
- i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
- controllers
- i8042.panicblink=
- [HW] Frequency with which keyboard LEDs should blink
- when kernel panics (default is 0.5 sec)
- i8042.reset [HW] Reset the controller during init and cleanup
- i8042.unlock [HW] Unlock (ignore) the keylock
- i810= [HW,DRM]
- i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
- indicates that the driver is running on unsupported
- hardware.
- i8k.force [HW] Activate i8k driver even if SMM BIOS signature
- does not match list of supported models.
- i8k.power_status
- [HW] Report power status in /proc/i8k
- (disabled by default)
- i8k.restricted [HW] Allow controlling fans only if SYS_ADMIN
- capability is set.
- ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter
- See Documentation/mca.txt.
- icn= [HW,ISDN]
- Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
- ide= [HW] (E)IDE subsystem
- Format: ide=nodma or ide=doubler
- See Documentation/ide/ide.txt.
- idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
- See Documentation/ide/ide.txt.
- idle= [X86]
- Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
- Poll forces a polling idle loop that can slightly improves the performance
- of waking up a idle CPU, but will use a lot of power and make the system
- run hot. Not recommended.
- idle=mwait. On systems which support MONITOR/MWAIT but the kernel chose
- to not use it because it doesn't save as much power as a normal idle
- loop use the MONITOR/MWAIT idle loop anyways. Performance should be the same
- as idle=poll.
- idle=halt. Halt is forced to be used for CPU idle.
- In such case C2/C3 won't be used again.
- idle=nomwait. Disable mwait for CPU C-states
- ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
- Claim all unknown PCI IDE storage controllers.
- ignore_loglevel [KNL]
- Ignore loglevel setting - this will print /all/
- kernel messages to the console. Useful for debugging.
- ihash_entries= [KNL]
- Set number of hash buckets for inode cache.
- in2000= [HW,SCSI]
- See header of drivers/scsi/in2000.c.
- init= [KNL]
- Format: <full_path>
- Run specified binary instead of /sbin/init as init
- process.
- initcall_debug [KNL] Trace initcalls as they are executed. Useful
- for working out where the kernel is dying during
- startup.
- initrd= [BOOT] Specify the location of the initial ramdisk
- inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
- Format: <irq>
- inttest= [IA64]
- iommu= [x86]
- off
- force
- noforce
- biomerge
- panic
- nopanic
- merge
- nomerge
- forcesac
- soft
- intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
- off
- Disable intel iommu driver.
- igfx_off [Default Off]
- By default, gfx is mapped as normal device. If a gfx
- device has a dedicated DMAR unit, the DMAR unit is
- bypassed by not enabling DMAR with this option. In
- this case, gfx device will use physical address for
- DMA.
- forcedac [x86_64]
- With this option iommu will not optimize to look
- for io virtual address below 32 bit forcing dual
- address cycle on pci bus for cards supporting greater
- than 32 bit addressing. The default is to look
- for translation below 32 bit and if not available
- then look in the higher range.
- strict [Default Off]
- With this option on every unmap_single operation will
- result in a hardware IOTLB flush operation as opposed
- to batching them for performance.
- io_delay= [X86-32,X86-64] I/O delay method
- 0x80
- Standard port 0x80 based delay
- 0xed
- Alternate port 0xed based delay (needed on some systems)
- udelay
- Simple two microseconds delay
- none
- No delay
- io7= [HW] IO7 for Marvel based alpha systems
- See comment before marvel_specify_io7 in
- arch/alpha/kernel/core_marvel.c.
- ip= [IP_PNP]
- See Documentation/filesystems/nfsroot.txt.
- ip2= [HW] Set IO/IRQ pairs for up to 4 IntelliPort boards
- See comment before ip2_setup() in
- drivers/char/ip2/ip2base.c.
- ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
- See header of drivers/scsi/ips.c.
- ports= [IP_VS_FTP] IPVS ftp helper module
- Default is 21.
- Up to 8 (IP_VS_APP_MAX_PORTS) ports
- may be specified.
- Format: <port>,<port>....
- irqfixup [HW]
- When an interrupt is not handled search all handlers
- for it. Intended to get systems with badly broken
- firmware running.
- irqpoll [HW]
- When an interrupt is not handled search all handlers
- for it. Also check all handlers each timer
- interrupt. Intended to get systems with badly broken
- firmware running.
- isapnp= [ISAPNP]
- Format: <RDP>,<reset>,<pci_scan>,<verbosity>
- isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
- Format:
- <cpu number>,...,<cpu number>
- or
- <cpu number>-<cpu number> (must be a positive range in ascending order)
- or a mixture
- <cpu number>,...,<cpu number>-<cpu number>
- This option can be used to specify one or more CPUs
- to isolate from the general SMP balancing and scheduling
- algorithms. The only way to move a process onto or off
- an "isolated" CPU is via the CPU affinity syscalls.
- <cpu number> begins at 0 and the maximum value is
- "number of CPUs in system - 1".
- This option is the preferred way to isolate CPUs. The
- alternative -- manually setting the CPU mask of all
- tasks in the system -- can cause problems and
- suboptimal load balancer performance.
- iucv= [HW,NET]
- js= [HW,JOY] Analog joystick
- See Documentation/input/joystick.txt.
- kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
- specifies the amount of memory usable by the kernel
- for non-movable allocations. The requested amount is
- spread evenly throughout all nodes in the system. The
- remaining memory in each node is used for Movable
- pages. In the event, a node is too small to have both
- kernelcore and Movable pages, kernelcore pages will
- take priority and other nodes will have a larger number
- of kernelcore pages. The Movable zone is used for the
- allocation of pages that may be reclaimed or moved
- by the page migration subsystem. This means that
- HugeTLB pages may not be allocated from this zone.
- Note that allocations like PTEs-from-HighMem still
- use the HighMem zone if it exists, and the Normal
- zone if it does not.
- movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
- is similar to kernelcore except it specifies the
- amount of memory used for migratable allocations.
- If both kernelcore and movablecore is specified,
- then kernelcore will be at *least* the specified
- value but may be more. If movablecore on its own
- is specified, the administrator must be careful
- that the amount of memory usable for all allocations
- is not too small.
- keepinitrd [HW,ARM]
- kstack=N [X86-32,X86-64] Print N words from the kernel stack
- in oops dumps.
- kgdboc= [HW] kgdb over consoles.
- Requires a tty driver that supports console polling.
- (only serial suported for now)
- Format: <serial_device>[,baud]
- kmac= [MIPS] korina ethernet MAC address.
- Configure the RouterBoard 532 series on-chip
- Ethernet adapter MAC address.
- l2cr= [PPC]
- l3cr= [PPC]
- lapic [X86-32,APIC] Enable the local APIC even if BIOS
- disabled it.
- lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer in
- C2 power state.
- libata.dma= [LIBATA] DMA control
- libata.dma=0 Disable all PATA and SATA DMA
- libata.dma=1 PATA and SATA Disk DMA only
- libata.dma=2 ATAPI (CDROM) DMA only
- libata.dma=4 Compact Flash DMA only
- Combinations also work, so libata.dma=3 enables DMA
- for disks and CDROMs, but not CFs.
- libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
- when set.
- Format: <int>
- libata.force= [LIBATA] Force configurations. The format is comma
- separated list of "[ID:]VAL" where ID is
- PORT[:DEVICE]. PORT and DEVICE are decimal numbers
- matching port, link or device. Basically, it matches
- the ATA ID string printed on console by libata. If
- the whole ID part is omitted, the last PORT and DEVICE
- values are used. If ID hasn't been specified yet, the
- configuration applies to all ports, links and devices.
- If only DEVICE is omitted, the parameter applies to
- the port and all links and devices behind it. DEVICE
- number of 0 either selects the first device or the
- first fan-out link behind PMP device. It does not
- select the host link. DEVICE number of 15 selects the
- host link and device attached to it.
- The VAL specifies the configuration to force. As long
- as there's no ambiguity shortcut notation is allowed.
- For example, both 1.5 and 1.5G would work for 1.5Gbps.
- The following configurations can be forced.
- * Cable type: 40c, 80c, short40c, unk, ign or sata.
- Any ID with matching PORT is used.
- * SATA link speed limit: 1.5Gbps or 3.0Gbps.
- * Transfer mode: pio[0-7], mwdma[0-4] and udma[0-7].
- udma[/][16,25,33,44,66,100,133] notation is also
- allowed.
- * [no]ncq: Turn on or off NCQ.
- * nohrst, nosrst, norst: suppress hard, soft
- and both resets.
- If there are multiple matching configurations changing
- the same attribute, the last one is used.
- load_ramdisk= [RAM] List of ramdisks to load from floppy
- See Documentation/ramdisk.txt.
- lockd.nlm_grace_period=P [NFS] Assign grace period.
- Format: <integer>
- lockd.nlm_tcpport=N [NFS] Assign TCP port.
- Format: <integer>
- lockd.nlm_timeout=T [NFS] Assign timeout value.
- Format: <integer>
- lockd.nlm_udpport=M [NFS] Assign UDP port.
- Format: <integer>
- logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
- Format: <irq>
- loglevel= All Kernel Messages with a loglevel smaller than the
- console loglevel will be printed to the console. It can
- also be changed with klogd or other programs. The
- loglevels are defined as follows:
- 0 (KERN_EMERG) system is unusable
- 1 (KERN_ALERT) action must be taken immediately
- 2 (KERN_CRIT) critical conditions
- 3 (KERN_ERR) error conditions
- 4 (KERN_WARNING) warning conditions
- 5 (KERN_NOTICE) normal but significant condition
- 6 (KERN_INFO) informational
- 7 (KERN_DEBUG) debug-level messages
- log_buf_len=n Sets the size of the printk ring buffer, in bytes.
- Format: { n | nk | nM }
- n must be a power of two. The default size
- is set in the kernel config file.
- logo.nologo [FB] Disables display of the built-in Linux logo.
- This may be used to provide more screen space for
- kernel log messages and is useful when debugging
- kernel boot problems.
- lp=0 [LP] Specify parallel ports to use, e.g,
- lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
- lp=reset first parallel port). 'lp=0' disables the
- lp=auto printer driver. 'lp=reset' (which can be
- specified in addition to the ports) causes
- attached printers to be reset. Using
- lp=port1,port2,... specifies the parallel ports
- to associate lp devices with, starting with
- lp0. A port specification may be 'none' to skip
- that lp device, or a parport name such as
- 'parport0'. Specifying 'lp=auto' instead of a
- port specification list means that device IDs
- from each port should be examined, to see if
- an IEEE 1284-compliant printer is attached; if
- so, the driver will manage that printer.
- See also header of drivers/char/lp.c.
- lpj=n [KNL]
- Sets loops_per_jiffy to given constant, thus avoiding
- time-consuming boot-time autodetection (up to 250 ms per
- CPU). 0 enables autodetection (default). To determine
- the correct value for your kernel, boot with normal
- autodetection and see what value is printed. Note that
- on SMP systems the preset will be applied to all CPUs,
- which is likely to cause problems if your CPUs need
- significantly divergent settings. An incorrect value
- will cause delays in the kernel to be wrong, leading to
- unpredictable I/O errors and other breakage. Although
- unlikely, in the extreme case this might damage your
- hardware.
- ltpc= [NET]
- Format: <io>,<irq>,<dma>
- mac5380= [HW,SCSI] Format:
- <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
- machvec= [IA64] Force the use of a particular machine-vector
- (machvec) in a generic kernel.
- Example: machvec=hpzx1_swiotlb
- max_loop= [LOOP] Maximum number of loopback devices that can
- be mounted
- Format: <1-256>
- maxcpus= [SMP] Maximum number of processors that an SMP kernel
- should make use of. maxcpus=n : n >= 0 limits the
- kernel to using 'n' processors. n=0 is a special case,
- it is equivalent to "nosmp", which also disables
- the IO APIC.
- max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
- equal to this physical address is ignored.
- max_luns= [SCSI] Maximum number of LUNs to probe.
- Should be between 1 and 2^32-1.
- max_report_luns=
- [SCSI] Maximum number of LUNs received.
- Should be between 1 and 16384.
- mcatest= [IA-64]
- mce [X86-32] Machine Check Exception
- mce=option [X86-64] See Documentation/x86_64/boot-options.txt
- md= [HW] RAID subsystems devices and level
- See Documentation/md.txt.
- mdacon= [MDA]
- Format: <first>,<last>
- Specifies range of consoles to be captured by the MDA.
- mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
- Amount of memory to be used when the kernel is not able
- to see the whole system memory or for test.
- [X86-32] Use together with memmap= to avoid physical
- address space collisions. Without memmap= PCI devices
- could be placed at addresses belonging to unused RAM.
- mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel
- memory.
- memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
- E820 memory map, as specified by the user.
- Such memmap=exactmap lines can be constructed based on
- BIOS output or other requirements. See the memmap=nn@ss
- option description.
- memmap=nn[KMG]@ss[KMG]
- [KNL] Force usage of a specific region of memory
- Region of memory to be used, from ss to ss+nn.
- memmap=nn[KMG]#ss[KMG]
- [KNL,ACPI] Mark specific memory as ACPI data.
- Region of memory to be used, from ss to ss+nn.
- memmap=nn[KMG]$ss[KMG]
- [KNL,ACPI] Mark specific memory as reserved.
- Region of memory to be used, from ss to ss+nn.
- Example: Exclude memory from 0x18690000-0x1869ffff
- memmap=64K$0x18690000
- or
- memmap=0x10000$0x18690000
- memtest= [KNL,X86] Enable memtest
- Format: <integer>
- range: 0,4 : pattern number
- default : 0 <disable>
- meye.*= [HW] Set MotionEye Camera parameters
- See Documentation/video4linux/meye.txt.
- mfgpt_irq= [IA-32] Specify the IRQ to use for the
- Multi-Function General Purpose Timers on AMD Geode
- platforms.
- mfgptfix [X86-32] Fix MFGPT timers on AMD Geode platforms when
- the BIOS has incorrectly applied a workaround. TinyBIOS
- version 0.98 is known to be affected, 0.99 fixes the
- problem by letting the user disable the workaround.
- mga= [HW,DRM]
- mminit_loglevel=
- [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
- parameter allows control of the logging verbosity for
- the additional memory initialisation checks. A value
- of 0 disables mminit logging and a level of 4 will
- log everything. Information is printed at KERN_DEBUG
- so loglevel=8 may also need to be specified.
- mousedev.tap_time=
- [MOUSE] Maximum time between finger touching and
- leaving touchpad surface for touch to be considered
- a tap and be reported as a left button click (for
- touchpads working in absolute mode only).
- Format: <msecs>
- mousedev.xres= [MOUSE] Horizontal screen resolution, used for devices
- reporting absolute coordinates, such as tablets
- mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
- reporting absolute coordinates, such as tablets
- mpu401= [HW,OSS]
- Format: <io>,<irq>
- MTD_Partition= [MTD]
- Format: <name>,<region-number>,<size>,<offset>
- MTD_Region= [MTD] Format:
- <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
- mtdparts= [MTD]
- See drivers/mtd/cmdlinepart.c.
- mtdset= [ARM]
- ARM/S3C2412 JIVE boot control
- See arch/arm/mach-s3c2412/mach-jive.c
- mtouchusb.raw_coordinates=
- [HW] Make the MicroTouch USB driver use raw coordinates
- ('y', default) or cooked coordinates ('n')
- n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
- NCR_D700= [HW,SCSI]
- See header of drivers/scsi/NCR_D700.c.
- ncr5380= [HW,SCSI]
- ncr53c400= [HW,SCSI]
- ncr53c400a= [HW,SCSI]
- ncr53c406a= [HW,SCSI]
- ncr53c8xx= [HW,SCSI]
- netdev= [NET] Network devices parameters
- Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
- Note that mem_start is often overloaded to mean
- something different and driver-specific.
- This usage is only documented in each driver source
- file if at all.
- nf_conntrack.acct=
- [NETFILTER] Enable connection tracking flow accounting
- 0 to disable accounting
- 1 to enable accounting
- Default value depends on CONFIG_NF_CT_ACCT that is
- going to be removed in 2.6.29.
- nfsaddrs= [NFS]
- See Documentation/filesystems/nfsroot.txt.
- nfsroot= [NFS] nfs root filesystem for disk-less boxes.
- See Documentation/filesystems/nfsroot.txt.
- nfs.callback_tcpport=
- [NFS] set the TCP port on which the NFSv4 callback
- channel should listen.
- nfs.idmap_cache_timeout=
- [NFS] set the maximum lifetime for idmapper cache
- entries.
- nfs.enable_ino64=
- [NFS] enable 64-bit inode numbers.
- If zero, the NFS client will fake up a 32-bit inode
- number for the readdir() and stat() syscalls instead
- of returning the full 64-bit number.
- The default is to return 64-bit inode numbers.
- nmi_debug= [KNL,AVR32] Specify one or more actions to take
- when a NMI is triggered.
- Format: [state][,regs][,debounce][,die]
- nmi_watchdog= [KNL,BUGS=X86-32] Debugging features for SMP kernels
- no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
- emulation library even if a 387 maths coprocessor
- is present.
- noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
- caches in the slab allocator. Saves per-node memory,
- but will impact performance.
- noalign [KNL,ARM]
- noapic [SMP,APIC] Tells the kernel to not make use of any
- IOAPICs that may be present in the system.
- nobats [PPC] Do not use BATs for mapping kernel lowmem
- on "Classic" PPC cores.
- nocache [ARM]
- nodelayacct [KNL] Disable per-task delay accounting
- nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
- noefi [X86-32,X86-64] Disable EFI runtime services support.
- noexec [IA-64]
- noexec [X86-32,X86-64]
- On X86-32 available only on PAE configured kernels.
- noexec=on: enable non-executable mappings (default)
- noexec=off: disable non-executable mappings
- noexec32 [X86-64]
- This affects only 32-bit executables.
- noexec32=on: enable non-executable mappings (default)
- read doesn't imply executable mappings
- noexec32=off: disable non-executable mappings
- read implies executable mappings
- nofxsr [BUGS=X86-32] Disables x86 floating point extended
- register save and restore. The kernel will only save
- legacy floating-point registers on task switch.
- noclflush [BUGS=X86] Don't use the CLFLUSH instruction
- nohlt [BUGS=ARM]
- no-hlt [BUGS=X86-32] Tells the kernel that the hlt
- instruction doesn't work correctly and not to
- use it.
- nohalt [IA-64] Tells the kernel not to use the power saving
- function PAL_HALT_LIGHT when idle. This increases
- power-consumption. On the positive side, it reduces
- interrupt wake-up latency, which may improve performance
- in certain environments such as networked servers or
- real-time systems.
- nohz= [KNL] Boottime enable/disable dynamic ticks
- Valid arguments: on, off
- Default: on
- noirqbalance [X86-32,SMP,KNL] Disable kernel irq balancing
- noirqdebug [X86-32] Disables the code which attempts to detect and
- disable unhandled interrupt sources.
- no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
- broken timer IRQ sources.
- noisapnp [ISAPNP] Disables ISA PnP code.
- noinitrd [RAM] Tells the kernel not to load any configured
- initial RAM disk.
- nointroute [IA-64]
- nojitter [IA64] Disables jitter checking for ITC timers.
- nolapic [X86-32,APIC] Do not enable or use the local APIC.
- nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
- noltlbs [PPC] Do not use large page/tlb entries for kernel
- lowmem mapping on PPC40x.
- nomca [IA-64] Disable machine check abort handling
- nomce [X86-32] Machine Check Exception
- nomfgpt [X86-32] Disable Multi-Function General Purpose
- Timer usage (for AMD Geode machines).
- noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
- noreplace-smp [X86-32,SMP] Don't replace SMP instructions
- with UP alternatives
- noresidual [PPC] Don't use residual data on PReP machines.
- noresume [SWSUSP] Disables resume and restores original swap
- space.
- no-scroll [VGA] Disables scrollback.
- This is required for the Braillex ib80-piezo Braille
- reader made by F.H. Papenmeier (Germany).
- nosbagart [IA-64]
- nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
- nosmp [SMP] Tells an SMP kernel to act as a UP kernel,
- and disable the IO APIC. legacy for "maxcpus=0".
- nosoftlockup [KNL] Disable the soft-lockup detector.
- nosync [HW,M68K] Disables sync negotiation for all devices.
- notsc [BUGS=X86-32] Disable Time Stamp Counter
- nousb [USB] Disable the USB subsystem
- nowb [ARM]
- nptcg= [IA64] Override max number of concurrent global TLB
- purges which is reported from either PAL_VM_SUMMARY or
- SAL PALO.
- numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
- one of ['zone', 'node', 'default'] can be specified
- This can be set from sysctl after boot.
- See Documentation/sysctl/vm.txt for details.
- nr_uarts= [SERIAL] maximum number of UARTs to be registered.
- olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
- Rather than timing out after 20 ms if an EC
- command is not properly ACKed, override the length
- of the timeout. We have interrupts disabled while
- waiting for the ACK, so if this is set too high
- interrupts *may* be lost!
- opl3= [HW,OSS]
- Format: <io>
- oprofile.timer= [HW]
- Use timer interrupt instead of performance counters
- osst= [HW,SCSI] SCSI Tape Driver
- Format: <buffer_size>,<write_threshold>
- See also Documentation/scsi/st.txt.
- panic= [KNL] Kernel behaviour on panic
- Format: <timeout>
- parkbd.port= [HW] Parallel port number the keyboard adapter is
- connected to, default is 0.
- Format: <parport#>
- parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
- 0 for XT, 1 for AT (default is AT).
- Format: <mode>
- parport= [HW,PPT] Specify parallel ports. 0 disables.
- Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
- Use 'auto' to force the driver to use any
- IRQ/DMA settings detected (the default is to
- ignore detected IRQ/DMA settings because of
- possible conflicts). You can specify the base
- address, IRQ, and DMA settings; IRQ and DMA
- should be numbers, or 'auto' (for using detected
- settings on that particular port), or 'nofifo'
- (to avoid using a FIFO even if it is detected).
- Parallel ports are assigned in the order they
- are specified on the command line, starting
- with parport0.
- parport_init_mode= [HW,PPT]
- Configure VIA parallel port to operate in
- a specific mode. This is necessary on Pegasos
- computer where firmware has no options for setting
- up parallel port mode and sets it to spp.
- Currently this function knows 686a and 8231 chips.
- Format: [spp|ps2|epp|ecp|ecpepp]
- pas2= [HW,OSS] Format:
- <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
- pas16= [HW,SCSI]
- See header of drivers/scsi/pas16.c.
- pause_on_oops=
- Halt all CPUs after the first oops has been printed for
- the specified number of seconds. This is to be used if
- your oopses keep scrolling off the screen.
- pcbit= [HW,ISDN]
- pcd. [PARIDE]
- See header of drivers/block/paride/pcd.c.
- See also Documentation/paride.txt.
- pci=option[,option...] [PCI] various PCI subsystem options:
- off [X86-32] don't probe for the PCI bus
- bios [X86-32] force use of PCI BIOS, don't access
- the hardware directly. Use this if your machine
- has a non-standard PCI host bridge.
- nobios [X86-32] disallow use of PCI BIOS, only direct
- hardware access methods are allowed. Use this
- if you experience crashes upon bootup and you
- suspect they are caused by the BIOS.
- conf1 [X86-32] Force use of PCI Configuration
- Mechanism 1.
- conf2 [X86-32] Force use of PCI Configuration
- Mechanism 2.
- noaer [PCIE] If the PCIEAER kernel config parameter is
- enabled, this kernel boot option can be used to
- disable the use of PCIE advanced error reporting.
- nodomains [PCI] Disable support for multiple PCI
- root domains (aka PCI segments, in ACPI-speak).
- nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
- Configuration
- nomsi [MSI] If the PCI_MSI kernel config parameter is
- enabled, this kernel boot option can be used to
- disable the use of MSI interrupts system-wide.
- biosirq [X86-32] Use PCI BIOS calls to get the interrupt
- routing table. These calls are known to be buggy
- on several machines and they hang the machine
- when used, but on other computers it's the only
- way to get the interrupt routing table. Try
- this option if the kernel is unable to allocate
- IRQs or discover secondary PCI buses on your
- motherboard.
- rom [X86-32] Assign address space to expansion ROMs.
- Use with caution as certain devices share
- address decoders between ROMs and other
- resources.
- norom [X86-32,X86_64] Do not assign address space to
- expansion ROMs that do not already have
- BIOS assigned address ranges.
- irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
- assigned automatically to PCI devices. You can
- make the kernel exclude IRQs of your ISA cards
- this way.
- pirqaddr=0xAAAAA [X86-32] Specify the physical address
- of the PIRQ table (normally generated
- by the BIOS) if it is outside the
- F0000h-100000h range.
- lastbus=N [X86-32] Scan all buses thru bus #N. Can be
- useful if the kernel is unable to find your
- secondary buses and you want to tell it
- explicitly which ones they are.
- assign-busses [X86-32] Always assign all PCI bus
- numbers ourselves, overriding
- whatever the firmware may have done.
- usepirqmask [X86-32] Honor the possible IRQ mask stored
- in the BIOS $PIR table. This is needed on
- some systems with broken BIOSes, notably
- some HP Pavilion N5400 and Omnibook XE3
- notebooks. This will have no effect if ACPI
- IRQ routing is enabled.
- noacpi [X86-32] Do not use ACPI for IRQ routing
- or for PCI scanning.
- use_crs [X86-32] Use _CRS for PCI resource
- allocation.
- routeirq Do IRQ routing for all PCI devices.
- This is normally done in pci_enable_device(),
- so this option is a temporary workaround
- for broken drivers that don't call it.
- skip_isa_align [X86] do not align io start addr, so can
- handle more pci cards
- firmware [ARM] Do not re-enumerate the bus but instead
- just use the configuration from the
- bootloader. This is currently used on
- IXP2000 systems where the bus has to be
- configured a certain way for adjunct CPUs.
- noearly [X86] Don't do any early type 1 scanning.
- This might help on some broken boards which
- machine check when some devices' config space
- is read. But various workarounds are disabled
- and some IOMMU drivers will not work.
- bfsort Sort PCI devices into breadth-first order.
- This sorting is done to get a device
- order compatible with older (<= 2.4) kernels.
- nobfsort Don't sort PCI devices into breadth-first order.
- cbiosize=nn[KMG] The fixed amount of bus space which is
- reserved for the CardBus bridge's IO window.
- The default value is 256 bytes.
- cbmemsize=nn[KMG] The fixed amount of bus space which is
- reserved for the CardBus bridge's memory
- window. The default value is 64 megabytes.
- pcmv= [HW,PCMCIA] BadgePAD 4
- pd. [PARIDE]
- See Documentation/paride.txt.
- pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
- boot time.
- Format: { 0 | 1 }
- See arch/parisc/kernel/pdc_chassis.c
- pf. [PARIDE]
- See Documentation/paride.txt.
- pg. [PARIDE]
- See Documentation/paride.txt.
- pirq= [SMP,APIC] Manual mp-table setup
- See Documentation/i386/IO-APIC.txt.
- plip= [PPT,NET] Parallel port network link
- Format: { parport<nr> | timid | 0 }
- See also Documentation/parport.txt.
- pmtmr= [X86] Manual setup of pmtmr I/O Port.
- Override pmtimer IOPort with a hex value.
- e.g. pmtmr=0x508
- pnpacpi= [ACPI]
- { off }
- pnpbios= [ISAPNP]
- { on | off | curr | res | no-curr | no-res }
- pnp_reserve_irq=
- [ISAPNP] Exclude IRQs for the autoconfiguration
- pnp_reserve_dma=
- [ISAPNP] Exclude DMAs for the autoconfiguration
- pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
- Ranges are in pairs (I/O port base and size).
- pnp_reserve_mem=
- [ISAPNP] Exclude memory regions for the
- autoconfiguration.
- Ranges are in pairs (memory base and size).
- print-fatal-signals=
- [KNL] debug: print fatal signals
- print-fatal-signals=1: print segfault info to
- the kernel console.
- default: off.
- printk.time= Show timing data prefixed to each printk message line
- Format: <bool> (1/Y/y=enable, 0/N/n=disable)
- profile= [KNL] Enable kernel profiling via /proc/profile
- Format: [schedule,]<number>
- Param: "schedule" - profile schedule points.
- Param: <number> - step/bucket size as a power of 2 for
- statistical time based profiling.
- Param: "sleep" - profile D-state sleeping (millisecs).
- Requires CONFIG_SCHEDSTATS
- Param: "kvm" - profile VM exits.
- processor.max_cstate= [HW,ACPI]
- Limit processor to maximum C-state
- max_cstate=9 overrides any DMI blacklist limit.
- processor.nocst [HW,ACPI]
- Ignore the _CST method to determine C-states,
- instead using the legacy FADT method
- prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
- before loading.
- See Documentation/ramdisk.txt.
- psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
- probe for; one of (bare|imps|exps|lifebook|any).
- psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
- per second.
- psmouse.resetafter= [HW,MOUSE]
- Try to reset the device after so many bad packets
- (0 = never).
- psmouse.resolution=
- [HW,MOUSE] Set desired mouse resolution, in dpi.
- psmouse.smartscroll=
- [HW,MOUSE] Controls Logitech smartscroll autorepeat.
- 0 = disabled, 1 = enabled (default).
- pss= [HW,OSS] Personal Sound System (ECHO ESC614)
- Format:
- <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
- pt. [PARIDE]
- See Documentation/paride.txt.
- pty.legacy_count=
- [KNL] Number of legacy pty's. Overwrites compiled-in
- default number.
- quiet [KNL] Disable most log messages
- r128= [HW,DRM]
- raid= [HW,RAID]
- See Documentation/md.txt.
- ramdisk_blocksize= [RAM]
- See Documentation/ramdisk.txt.
- ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
- See Documentation/ramdisk.txt.
- rcupdate.blimit= [KNL,BOOT]
- Set maximum number of finished RCU callbacks to process
- in one batch.
- rcupdate.qhimark= [KNL,BOOT]
- Set threshold of queued
- RCU callbacks over which batch limiting is disabled.
- rcupdate.qlowmark= [KNL,BOOT]
- Set threshold of queued RCU callbacks below which
- batch limiting is re-enabled.
- rdinit= [KNL]
- Format: <full_path>
- Run specified binary instead of /init from the ramdisk,
- used for early userspace startup. See initrd.
- reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
- Format: <reboot_mode>[,<reboot_mode2>[,...]]
- See arch/*/kernel/reboot.c or arch/*/kernel/process.c
- relax_domain_level=
- [KNL, SMP] Set scheduler's default relax_domain_level.
- See Documentation/cpusets.txt.
- reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
- reservetop= [X86-32]
- Format: nn[KMG]
- Reserves a hole at the top of the kernel virtual
- address space.
- reset_devices [KNL] Force drivers to reset the underlying device
- during initialization.
- resume= [SWSUSP]
- Specify the partition device for software suspend
- resume_offset= [SWSUSP]
- Specify the offset from the beginning of the partition
- given by "resume=" at which the swap header is located,
- in <PAGE_SIZE> units (needed only for swap files).
- See Documentation/power/swsusp-and-swap-files.txt
- retain_initrd [RAM] Keep initrd memory after extraction
- rhash_entries= [KNL,NET]
- Set number of hash buckets for route cache
- riscom8= [HW,SERIAL]
- Format: <io_board1>[,<io_board2>[,...<io_boardN>]]
- ro [KNL] Mount root device read-only on boot
- root= [KNL] Root filesystem
- rootdelay= [KNL] Delay (in seconds) to pause before attempting to
- mount the root filesystem
- rootflags= [KNL] Set root filesystem mount option string
- rootfstype= [KNL] Set root filesystem type
- rootwait [KNL] Wait (indefinitely) for root device to show up.
- Useful for devices that are detected asynchronously
- (e.g. USB and MMC devices).
- root_plug.vendor_id=
- [ROOTPLUG] Override the default vendor ID
- root_plug.product_id=
- [ROOTPLUG] Override the default product ID
- root_plug.debug=
- [ROOTPLUG] Enable debugging output
- rw [KNL] Mount root device read-write on boot
- S [KNL] Run init in single mode
- sa1100ir [NET]
- See drivers/net/irda/sa1100_ir.c.
- sbni= [NET] Granch SBNI12 leased line adapter
- sc1200wdt= [HW,WDT] SC1200 WDT (watchdog) driver
- Format: <io>[,<timeout>[,<isapnp>]]
- scsi_debug_*= [SCSI]
- See drivers/scsi/scsi_debug.c.
- scsi_default_dev_flags=
- [SCSI] SCSI default device flags
- Format: <integer>
- scsi_dev_flags= [SCSI] Black/white list entry for vendor and model
- Format: <vendor>:<model>:<flags>
- (flags are integer value)
- scsi_logging_level= [SCSI] a bit mask of logging levels
- See drivers/scsi/scsi_logging.h for bits. Also
- settable via sysctl at dev.scsi.logging_level
- (/proc/sys/dev/scsi/logging_level).
- There is also a nice 'scsi_logging_level' script in the
- S390-tools package, available for download at
- http://www-128.ibm.com/developerworks/linux/linux390/s390-tools-1.5.4.html
- scsi_mod.scan= [SCSI] sync (default) scans SCSI busses as they are
- discovered. async scans them in kernel threads,
- allowing boot to proceed. none ignores them, expecting
- user space to do the scan.
- selinux [SELINUX] Disable or enable SELinux at boot time.
- Format: { "0" | "1" }
- See security/selinux/Kconfig help text.
- 0 -- disable.
- 1 -- enable.
- Default value is set via kernel config option.
- If enabled at boot time, /selinux/disable can be used
- later to disable prior to initial policy load.
- selinux_compat_net =
- [SELINUX] Set initial selinux_compat_net flag value.
- Format: { "0" | "1" }
- 0 -- use new secmark-based packet controls
- 1 -- use legacy packet controls
- Default value is 0 (preferred).
- Value can be changed at runtime via
- /selinux/compat_net.
- serialnumber [BUGS=X86-32]
- shapers= [NET]
- Maximal number of shapers.
- show_msr= [x86] show boot-time MSR settings
- Format: { <integer> }
- Show boot-time (BIOS-initialized) MSR settings.
- The parameter means the number of CPUs to show,
- for example 1 means boot CPU only.
- sim710= [SCSI,HW]
- See header of drivers/scsi/sim710.c.
- simeth= [IA-64]
- simscsi=
- slram= [HW,MTD]
- slub_debug[=options[,slabs]] [MM, SLUB]
- Enabling slub_debug allows one to determine the
- culprit if slab objects become corrupted. Enabling
- slub_debug can create guard zones around objects and
- may poison objects when not in use. Also tracks the
- last alloc / free. For more information see
- Documentation/vm/slub.txt.
- slub_max_order= [MM, SLUB]
- Determines the maximum allowed order for slabs.
- A high setting may cause OOMs due to memory
- fragmentation. For more information see
- Documentation/vm/slub.txt.
- slub_min_objects= [MM, SLUB]
- The minimum number of objects per slab. SLUB will
- increase the slab order up to slub_max_order to
- generate a sufficiently large slab able to contain
- the number of objects indicated. The higher the number
- of objects the smaller the overhead of tracking slabs
- and the less frequently locks need to be acquired.
- For more information see Documentation/vm/slub.txt.
- slub_min_order= [MM, SLUB]
- Determines the mininum page order for slabs. Must be
- lower than slub_max_order.
- For more information see Documentation/vm/slub.txt.
- slub_nomerge [MM, SLUB]
- Disable merging of slabs with similar size. May be
- necessary if there is some reason to distinguish
- allocs to different slabs. Debug options disable
- merging on their own.
- For more information see Documentation/vm/slub.txt.
- smart2= [HW]
- Format: <io1>[,<io2>[,...,<io8>]]
- smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
- attempt to substitute SMP alternatives once at boot.
- smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
- smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
- smsc-ircc2.ircc_sir= [HW] SIR base I/O port
- smsc-ircc2.ircc_fir= [HW] FIR base I/O port
- smsc-ircc2.ircc_irq= [HW] IRQ line
- smsc-ircc2.ircc_dma= [HW] DMA channel
- smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
- 0: Toshiba Satellite 1800 (GP data pin select)
- 1: Fast pin select (default)
- 2: ATC IRMode
- snd-ad1816a= [HW,ALSA]
- snd-ad1848= [HW,ALSA]
- snd-ali5451= [HW,ALSA]
- snd-als100= [HW,ALSA]
- snd-als4000= [HW,ALSA]
- snd-azt2320= [HW,ALSA]
- snd-cmi8330= [HW,ALSA]
- snd-cmipci= [HW,ALSA]
- snd-cs4231= [HW,ALSA]
- snd-cs4232= [HW,ALSA]
- snd-cs4236= [HW,ALSA]
- snd-cs4281= [HW,ALSA]
- snd-cs46xx= [HW,ALSA]
- snd-dt019x= [HW,ALSA]
- snd-dummy= [HW,ALSA]
- snd-emu10k1= [HW,ALSA]
- snd-ens1370= [HW,ALSA]
- snd-ens1371= [HW,ALSA]
- snd-es968= [HW,ALSA]
- snd-es1688= [HW,ALSA]
- snd-es18xx= [HW,ALSA]
- snd-es1938= [HW,ALSA]
- snd-es1968= [HW,ALSA]
- snd-fm801= [HW,ALSA]
- snd-gusclassic= [HW,ALSA]
- snd-gusextreme= [HW,ALSA]
- snd-gusmax= [HW,ALSA]
- snd-hdsp= [HW,ALSA]
- snd-ice1712= [HW,ALSA]
- snd-intel8x0= [HW,ALSA]
- snd-interwave= [HW,ALSA]
- snd-interwave-stb=
- [HW,ALSA]
- snd-korg1212= [HW,ALSA]
- snd-maestro3= [HW,ALSA]
- snd-mpu401= [HW,ALSA]
- snd-mtpav= [HW,ALSA]
- snd-nm256= [HW,ALSA]
- snd-opl3sa2= [HW,ALSA]
- snd-opti92x-ad1848=
- [HW,ALSA]
- snd-opti92x-cs4231=
- [HW,ALSA]
- snd-opti93x= [HW,ALSA]
- snd-pmac= [HW,ALSA]
- snd-rme32= [HW,ALSA]
- snd-rme96= [HW,ALSA]
- snd-rme9652= [HW,ALSA]
- snd-sb8= [HW,ALSA]
- snd-sb16= [HW,ALSA]
- snd-sbawe= [HW,ALSA]
- snd-serial= [HW,ALSA]
- snd-sgalaxy= [HW,ALSA]
- snd-sonicvibes= [HW,ALSA]
- snd-sun-amd7930=
- [HW,ALSA]
- snd-sun-cs4231= [HW,ALSA]
- snd-trident= [HW,ALSA]
- snd-usb-audio= [HW,ALSA,USB]
- snd-via82xx= [HW,ALSA]
- snd-virmidi= [HW,ALSA]
- snd-wavefront= [HW,ALSA]
- snd-ymfpci= [HW,ALSA]
- softlockup_panic=
- [KNL] Should the soft-lockup detector generate panics.
- sonypi.*= [HW] Sony Programmable I/O Control Device driver
- See Documentation/sonypi.txt
- specialix= [HW,SERIAL] Specialix multi-serial port adapter
- See Documentation/specialix.txt.
- spia_io_base= [HW,MTD]
- spia_fio_base=
- spia_pedr=
- spia_peddr=
- sscape= [HW,OSS]
- Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
- st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
- See Documentation/scsi/st.txt.
- sti= [PARISC,HW]
- Format: <num>
- Set the STI (builtin display/keyboard on the HP-PARISC
- machines) console (graphic card) which should be used
- as the initial boot-console.
- See also comment in drivers/video/console/sticore.c.
- sti_font= [HW]
- See comment in drivers/video/console/sticore.c.
- stifb= [HW]
- Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
- sunrpc.pool_mode=
- [NFS]
- Control how the NFS server code allocates CPUs to
- service thread pools. Depending on how many NICs
- you have and where their interrupts are bound, this
- option will affect which CPUs will do NFS serving.
- Note: this parameter cannot be changed while the
- NFS server is running.
- auto the server chooses an appropriate mode
- automatically using heuristics
- global a single global pool contains all CPUs
- percpu one pool for each CPU
- pernode one pool for each NUMA node (equivalent
- to global on non-NUMA machines)
- swiotlb= [IA-64] Number of I/O TLB slabs
- switches= [HW,M68k]
- sym53c416= [HW,SCSI]
- See header of drivers/scsi/sym53c416.c.
- sysrq_always_enabled
- [KNL]
- Ignore sysrq setting - this boot parameter will
- neutralize any effect of /proc/sys/kernel/sysrq.
- Useful for debugging.
- t128= [HW,SCSI]
- See header of drivers/scsi/t128.c.
- tdfx= [HW,DRM]
- test_suspend= [SUSPEND]
- Specify "mem" (for Suspend-to-RAM) or "standby" (for
- standby suspend) as the system sleep state to briefly
- enter during system startup. The system is woken from
- this state using a wakeup-capable RTC alarm.
- thash_entries= [KNL,NET]
- Set number of hash buckets for TCP connection
- thermal.act= [HW,ACPI]
- -1: disable all active trip points in all thermal zones
- <degrees C>: override all lowest active trip points
- thermal.crt= [HW,ACPI]
- -1: disable all critical trip points in all thermal zones
- <degrees C>: lower all critical trip points
- thermal.nocrt= [HW,ACPI]
- Set to disable actions on ACPI thermal zone
- critical and hot trip points.
- thermal.off= [HW,ACPI]
- 1: disable ACPI thermal control
- thermal.psv= [HW,ACPI]
- -1: disable all passive trip points
- <degrees C>: override all passive trip points to this value
- thermal.tzp= [HW,ACPI]
- Specify global default ACPI thermal zone polling rate
- <deci-seconds>: poll all this frequency
- 0: no polling (default)
- tmscsim= [HW,SCSI]
- See comment before function dc390_setup() in
- drivers/scsi/tmscsim.c.
- tp720= [HW,PS2]
- trix= [HW,OSS] MediaTrix AudioTrix Pro
- Format:
- <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
- turbografx.map[2|3]= [HW,JOY]
- TurboGraFX parallel port interface
- Format:
- <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
- See also Documentation/input/joystick-parport.txt
- u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
- See header of drivers/scsi/u14-34f.c.
- uart401= [HW,OSS]
- Format: <io>,<irq>
- uart6850= [HW,OSS]
- Format: <io>,<irq>
- uhci-hcd.ignore_oc=
- [USB] Ignore overcurrent events (default N).
- Some badly-designed motherboards generate lots of
- bogus events, for ports that aren't wired to
- anything. Set this parameter to avoid log spamming.
- Note that genuine overcurrent events won't be
- reported either.
- unknown_nmi_panic
- [X86-32,X86-64]
- Set unknown_nmi_panic=1 early on boot.
- usbcore.autosuspend=
- [USB] The autosuspend time delay (in seconds) used
- for newly-detected USB devices (default 2). This
- is the time required before an idle device will be
- autosuspended. Devices for which the delay is set
- to a negative value won't be autosuspended at all.
- usbhid.mousepoll=
- [USBHID] The interval which mice are to be polled at.
- add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
- kernel's map of available physical RAM.
- vdso= [X86-32,SH,x86-64]
- vdso=2: enable compat VDSO (default with COMPAT_VDSO)
- vdso=1: enable VDSO (default)
- vdso=0: disable VDSO mapping
- vdso32= [X86-32,X86-64]
- vdso32=2: enable compat VDSO (default with COMPAT_VDSO)
- vdso32=1: enable 32-bit VDSO (default)
- vdso32=0: disable 32-bit VDSO mapping
- vector= [IA-64,SMP]
- vector=percpu: enable percpu vector domain
- video= [FB] Frame buffer configuration
- See Documentation/fb/modedb.txt.
- vga= [BOOT,X86-32] Select a particular video mode
- See Documentation/i386/boot.txt and
- Documentation/svga.txt.
- Use vga=ask for menu.
- This is actually a boot loader parameter; the value is
- passed to the kernel using a special protocol.
- vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
- size of <nn>. This can be used to increase the
- minimum size (128MB on x86). It can also be used to
- decrease the size and leave more room for directly
- mapped kernel RAM.
- vmhalt= [KNL,S390] Perform z/VM CP command after system halt.
- Format: <command>
- vmpanic= [KNL,S390] Perform z/VM CP command after kernel panic.
- Format: <command>
- vmpoff= [KNL,S390] Perform z/VM CP command after power off.
- Format: <command>
- waveartist= [HW,OSS]
- Format: <io>,<irq>,<dma>,<dma2>
- wd33c93= [HW,SCSI]
- See header of drivers/scsi/wd33c93.c.
- wd7000= [HW,SCSI]
- See header of drivers/scsi/wd7000.c.
- wdt= [WDT] Watchdog
- See Documentation/watchdog/wdt.txt.
- xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
- xd_geo= See header of drivers/block/xd.c.
- xirc2ps_cs= [NET,PCMCIA]
- Format:
- <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
- norandmaps Don't use address space randomization
- Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
- ______________________________________________________________________
- TODO:
- Add documentation for ALSA options.
- Add more DRM drivers.
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