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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
-
-Hyphens (dashes) and underscores are equivalent in parameter names, so
- log_buf_len=1M print-fatal-signals=1
-can also be entered as
- log-buf-len=1M print_fatal_signals=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.
- ARM ARM architecture 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.
- DYNAMIC_DEBUG Build in debug messages and enable them at runtime
- EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
- EFI EFI Partitioning (GPT) is enabled
- EIDE EIDE/ATAPI support is enabled.
- EVM Extended Verification Module
- FB The frame buffer device is enabled.
- FTRACE Function tracing enabled.
- GCOV GCOV profiling is enabled.
- HW Appropriate hardware is enabled.
- IA-64 IA-64 architecture is enabled.
- IMA Integrity measurement architecture is enabled.
- IOSCHED More than one I/O scheduler is enabled.
- IP_PNP IP DHCP, BOOTP, or RARP is enabled.
- IPV6 IPv6 support is enabled.
- ISAPNP ISA PnP code is enabled.
- ISDN Appropriate ISDN support is enabled.
- JOY Appropriate joystick support is enabled.
- KGDB Kernel debugger support is enabled.
- KVM Kernel Virtual Machine 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.
- MDA MDA console support is enabled.
- MIPS MIPS architecture 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.
- 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.
- S390 S390 architecture is enabled.
- SCSI Appropriate SCSI support is enabled.
- A lot of drivers have their options described inside
- the Documentation/scsi/ sub-directory.
- SECURITY Different security models are enabled.
- SELINUX SELinux support is enabled.
- APPARMOR AppArmor 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.
- TPM TPM drivers are enabled.
- TS Appropriate touchscreen support is enabled.
- UMS USB Mass Storage support is enabled.
- USB USB support is enabled.
- USBHID USB Human Interface Device support is enabled.
- V4L Video For Linux support is enabled.
- VMMIO Driver for memory mapped virtio devices 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/x86_64/boot-options.txt .
- X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
- XEN Xen support is enabled
-
-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/x86/boot.txt>.
-
-There are also arch-specific kernel-parameters not documented here.
-See for example <Documentation/x86/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.
-
-Finally, the [KMG] suffix is commonly described after a number of kernel
-parameter values. These 'K', 'M', and 'G' letters represent the _binary_
-multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
-bytes respectively. Such letter suffixes can also be entirely omitted.
-
-
- acpi= [HW,ACPI,X86]
- Advanced Configuration and Power Interface
- Format: { force | off | strict | noirq | rsdt }
- force -- enable ACPI if default was off
- off -- disable ACPI if default was on
- noirq -- do not use ACPI for IRQ routing
- strict -- Be less tolerant of platforms that are not
- strictly ACPI specification compliant.
- rsdt -- prefer RSDT over (default) XSDT
- copy_dsdt -- copy DSDT to memory
-
- See also Documentation/power/runtime_pm.txt, pci=noacpi
-
- acpi_rsdp= [ACPI,EFI,KEXEC]
- Pass the RSDP address to the kernel, mostly used
- on machines running EFI runtime service to boot the
- second kernel for kdump.
-
- acpi_apic_instance= [ACPI, IOAPIC]
- Format: <int>
- 2: use 2nd APIC table, if available
- 1,0: use 1st APIC table
- default: 0
-
- acpi_backlight= [HW,ACPI]
- acpi_backlight=vendor
- acpi_backlight=video
- If set to vendor, prefer vendor specific driver
- (e.g. thinkpad_acpi, sony_acpi, etc.) instead
- of the ACPI video.ko driver.
-
- acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
- acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
- Format: <int>
- CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
- debug output. Bits in debug_layer correspond to a
- _COMPONENT in an ACPI source file, e.g.,
- #define _COMPONENT ACPI_PCI_COMPONENT
- Bits in debug_level correspond to a level in
- ACPI_DEBUG_PRINT statements, e.g.,
- ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
- The debug_level mask defaults to "info". See
- Documentation/acpi/debug.txt for more information about
- debug layers and levels.
-
- Enable processor driver info messages:
- acpi.debug_layer=0x20000000
- Enable PCI/PCI interrupt routing info messages:
- acpi.debug_layer=0x400000
- Enable AML "Debug" output, i.e., stores to the Debug
- object while interpreting AML:
- acpi.debug_layer=0xffffffff acpi.debug_level=0x2
- Enable all messages related to ACPI hardware:
- acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
-
- Some values produce so much output that the system is
- unusable. The "log_buf_len" parameter may be useful
- if you need to capture more output.
-
- 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_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
- Format: <irq>,<irq>...
-
- acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
- use by PCI
- 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_pm_good [X86]
- Override the pmtimer bug detection: force the kernel
- to assume that this machine's pmtimer latches its value
- and always returns good values.
-
- acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
- Format: { level | edge | high | low }
-
- 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_sleep= [HW,ACPI] Sleep options
- Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
- old_ordering, nonvs, sci_force_enable }
- See Documentation/power/video.txt for information on
- 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, with respect to putting devices into
- low power states, to be enforced (the ACPI 2.0 ordering
- of _PTS is used by default).
- nonvs prevents the kernel from saving/restoring the
- ACPI NVS memory during suspend/hibernation and resume.
- sci_force_enable causes the kernel to set SCI_EN directly
- on resume from S1/S3 (which is against the ACPI spec,
- but some broken systems don't work without it).
-
- 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_enforce_resources= [ACPI]
- { strict | lax | no }
- Check for resource conflicts between native drivers
- and ACPI OperationRegions (SystemIO and SystemMemory
- only). IO ports and memory declared in ACPI might be
- used by the ACPI subsystem in arbitrary AML code and
- can interfere with legacy drivers.
- strict (default): access to resources claimed by ACPI
- is denied; legacy drivers trying to access reserved
- resources will fail to bind to device using them.
- lax: access to resources claimed by ACPI is allowed;
- legacy drivers trying to access reserved resources
- will bind successfully but a warning message is logged.
- no: ACPI OperationRegions are not marked as reserved,
- no further checks are performed.
-
- add_efi_memmap [EFI; X86] Include EFI memory map in
- kernel's map of available physical RAM.
-
- agp= [AGP]
- { off | try_unsupported }
- off: disable AGP support
- try_unsupported: try to drive unsupported chipsets
- (may crash computer or cause data corruption)
-
- ALSA [HW,ALSA]
- See Documentation/sound/alsa/alsa-parameters.txt
-
- alignment= [KNL,ARM]
- Allow the default userspace alignment fault handler
- behaviour to be specified. Bit 0 enables warnings,
- bit 1 enables fixups, and bit 2 sends a segfault.
-
- align_va_addr= [X86-64]
- Align virtual addresses by clearing slice [14:12] when
- allocating a VMA at process creation time. This option
- gives you up to 3% performance improvement on AMD F15h
- machines (where it is enabled by default) for a
- CPU-intensive style benchmark, and it can vary highly in
- a microbenchmark depending on workload and compiler.
-
- 32: only for 32-bit processes
- 64: only for 64-bit processes
- on: enable for both 32- and 64-bit processes
- off: disable for both 32- and 64-bit processes
-
- amd_iommu= [HW,X86-64]
- Pass parameters to the AMD IOMMU driver in the system.
- Possible values are:
- 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
- off - do not initialize any AMD IOMMU found in
- the system
- force_isolation - Force device isolation for all
- devices. The IOMMU driver is not
- allowed anymore to lift isolation
- requirements as needed. This option
- does not override iommu=pt
-
- amd_iommu_dump= [HW,X86-64]
- Enable AMD IOMMU driver option to dump the ACPI table
- for AMD IOMMU. With this option enabled, AMD IOMMU
- driver will print ACPI tables for AMD IOMMU during
- IOMMU initialization.
-
- amijoy.map= [HW,JOY] Amiga joystick support
- Map of devices attached to JOY0DAT and JOY1DAT
- Format: <a>,<b>
- See also Documentation/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,X86-32] 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.
-
- autoconf= [IPV6]
- See Documentation/networking/ipv6.txt.
-
- show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
- Limit apic dumping. The parameter defines the maximal
- number of local apics being dumped. Also it is possible
- to set it to "all" by meaning -- no limit here.
- Format: { 1 (default) | 2 | ... | all }.
- The parameter valid if only apic=debug or
- apic=verbose is specified.
- Example: apic=debug show_lapic=all
-
- 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
-
- 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
-
- 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=
-
- bulk_remove=off [PPC] This parameter disables the use of the pSeries
- firmware feature for flushing multiple hpte entries
- at a time.
-
- 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.
-
- 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= 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;
- 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
- arch/x86/include/asm/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.
-
- cma=nn[MG] [ARM,KNL]
- Sets the size of kernel global memory area for contiguous
- memory allocations. For more information, see
- include/linux/dma-contiguous.h
-
- cmo_free_hint= [PPC] Format: { yes | no }
- Specify whether pages are marked as being inactive
- when they are freed. This is used in CMO environments
- to determine OS memory pressure for page stealing by
- a hypervisor.
- Default: yes
-
- coherent_pool=nn[KMG] [ARM,KNL]
- Sets the size of memory pool for coherent, atomic dma
- allocations if Contiguous Memory Allocator (CMA) is used.
-
- code_bytes [X86] How many bytes of object code to print
- in an oops report.
- Range: 0 - 8192
- Default: 64
-
- 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.
-
- consoleblank= [KNL] The console blank (screen saver) timeout in
- seconds. Defaults to 10*60 = 10mins. A value of 0
- disables the blank timer.
-
- coredump_filter=
- [KNL] Change the default value for
- /proc/<pid>/coredump_filter.
- See also Documentation/filesystems/proc.txt.
-
- cpuidle.off=1 [CPU_IDLE]
- disable the cpuidle sub-system
-
- cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
- Format:
- <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
-
- crashkernel=size[KMG][@offset[KMG]]
- [KNL] Using kexec, Linux can switch to a 'crash kernel'
- upon panic. This parameter reserves the physical
- memory region [offset, offset + size] for that kernel
- image. If '@offset' is omitted, then a suitable offset
- is selected automatically. Check
- Documentation/kdump/kdump.txt for further details.
-
- 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 an example.
-
- 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
-
- ddebug_query= [KNL,DYNAMIC_DEBUG] Enable debug messages at early boot
- time. See Documentation/dynamic-debug-howto.txt for
- details. Deprecated, see dyndbg.
-
- 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
-
- no_debug_objects
- [KNL] Disable object debugging
-
- debug_guardpage_minorder=
- [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
- parameter allows control of the order of pages that will
- be intentionally kept free (and hence protected) by the
- buddy allocator. Bigger value increase the probability
- of catching random memory corruption, but reduce the
- amount of memory for normal system use. The maximum
- possible value is MAX_ORDER/2. Setting this parameter
- to 1 or 2 should be enough to identify most random
- memory corruption problems caused by bugs in kernel or
- driver code when a CPU writes to (or reads from) a
- random memory location. Note that there exists a class
- of memory corruptions problems caused by buggy H/W or
- F/W or by drivers badly programing DMA (basically when
- memory is written at bus level and the CPU MMU is
- bypassed) which are not detectable by
- CONFIG_DEBUG_PAGEALLOC, hence this option will not help
- tracking down these problems.
-
- debugpat [X86] Enable PAT debugging
-
- decnet.addr= [HW,NET]
- Format: <area>[,<node>]
- See also Documentation/networking/decnet.txt.
-
- 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.
-
- 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/serial/digiepca.txt.
-
- disable= [IPV6]
- See Documentation/networking/ipv6.txt.
-
- disable_ddw [PPC/PSERIES]
- Disable Dynamic DMA Window support. Use this if
- to workaround buggy firmware.
-
- disable_ipv6= [IPV6]
- See Documentation/networking/ipv6.txt.
-
- disable_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 disables that.
-
- 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.
-
- disable_timer_pin_1 [X86]
- Disable PIN 1 of APIC timer
- Can be useful to work around chipset bugs.
-
- dma_debug=off If the kernel is compiled with DMA_API_DEBUG support,
- this option disables the debugging code at boot.
-
- dma_debug_entries=<number>
- This option allows to tune the number of preallocated
- entries for DMA-API debugging code. One entry is
- required per DMA-API allocation. Use this if the
- DMA-API debugging code disables itself because the
- architectural default is too low.
-
- dma_debug_driver=<driver_name>
- With this option the DMA-API debugging driver
- filter feature can be enabled at boot time. Just
- pass the driver to filter for as the parameter.
- The filter can be disabled or changed to another
- driver later using sysfs.
-
- drm_kms_helper.edid_firmware=[<connector>:]<file>
- Broken monitors, graphic adapters and KVMs may
- send no or incorrect EDID data sets. This parameter
- allows to specify an EDID data set in the
- /lib/firmware directory that is used instead.
- Generic built-in EDID data sets are used, if one of
- edid/1024x768.bin, edid/1280x1024.bin,
- edid/1680x1050.bin, or edid/1920x1080.bin is given
- and no file with the same name exists. Details and
- instructions how to build your own EDID data are
- available in Documentation/EDID/HOWTO.txt. An EDID
- data set will only be used for a particular connector,
- if its name and a colon are prepended to the EDID
- name.
-
- dscc4.setup= [NET]
-
- dyndbg[="val"] [KNL,DYNAMIC_DEBUG]
- module.dyndbg[="val"]
- Enable debug messages at boot time. See
- Documentation/dynamic-debug-howto.txt for details.
-
- earlycon= [KNL] Output early console device and options.
- uart[8250],io,<addr>[,options]
- uart[8250],mmio,<addr>[,options]
- uart[8250],mmio32,<addr>[,options]
- Start an early, polled-mode console on the 8250/16550
- UART at the specified I/O port or MMIO address.
- MMIO inter-register address stride is either 8-bit
- (mmio) or 32-bit (mmio32).
- The options are the same as for ttyS, above.
-
- earlyprintk= [X86,SH,BLACKFIN]
- earlyprintk=vga
- earlyprintk=serial[,ttySn[,baudrate]]
- earlyprintk=ttySn[,baudrate]
- earlyprintk=dbgp[debugController#]
-
- Append ",keep" to not disable it when the real console
- takes over.
-
- Only vga or serial or usb debug port at a time.
-
- 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.
-
- ekgdboc= [X86,KGDB] Allow early kernel console debugging
- ekgdboc=kbd
-
- This is designed to be used in conjunction with
- the boot argument: earlyprintk=vga
-
- 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: {"cfq" | "deadline" | "noop"}
- See Documentation/block/cfq-iosched.txt and
- Documentation/block/deadline-iosched.txt for details.
-
- elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
- Specifies physical address of start of kernel core
- image elf header and optionally the size. Generally
- kexec loader will pass this option to capture kernel.
- See Documentation/kdump/kdump.txt for details.
-
- 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 that.
-
- enable_timer_pin_1 [X86]
- 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.
-
- 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.
-
- erst_disable [ACPI]
- Disable Error Record Serialization Table (ERST)
- support.
-
- ether= [HW,NET] Ethernet cards parameters
- This option is obsoleted by the "netdev=" option, which
- has equivalent usage. See its documentation for details.
-
- evm= [EVM]
- Format: { "fix" }
- Permit 'security.evm' to be updated regardless of
- current integrity status.
-
- failslab=
- fail_page_alloc=
- fail_make_request=[KNL]
- General fault injection mechanism.
- Format: <interval>,<probability>,<space>,<times>
- See also Documentation/fault-injection/.
-
- floppy= [HW]
- See Documentation/blockdev/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.
-
- ftrace=[tracer]
- [FTRACE] will set and start the specified tracer
- as early as possible in order to facilitate early
- boot debugging.
-
- ftrace_dump_on_oops[=orig_cpu]
- [FTRACE] will dump the trace buffers on oops.
- If no parameter is passed, ftrace will dump
- buffers of all CPUs, but if you pass orig_cpu, it will
- dump only the buffer of the CPU that triggered the
- oops.
-
- ftrace_filter=[function-list]
- [FTRACE] Limit the functions traced by the function
- tracer at boot up. function-list is a comma separated
- list of functions. This list can be changed at run
- time by the set_ftrace_filter file in the debugfs
- tracing directory.
-
- ftrace_notrace=[function-list]
- [FTRACE] Do not trace the functions specified in
- function-list. This list can be changed at run time
- by the set_ftrace_notrace file in the debugfs
- tracing directory.
-
- ftrace_graph_filter=[function-list]
- [FTRACE] Limit the top level callers functions traced
- by the function graph tracer at boot up.
- function-list is a comma separated list of functions
- that can be changed at run time by the
- set_graph_function file in the debugfs tracing directory.
-
- 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
-
- gcov_persist= [GCOV] When non-zero (default), profiling data for
- kernel modules is saved and remains accessible via
- debugfs, even when the module is unloaded/reloaded.
- When zero, profiling data is discarded and associated
- debugfs files are removed at module unload time.
-
- gpt [EFI] Forces disk with valid GPT signature but
- invalid Protective MBR to be treated as GPT.
-
- hashdist= [KNL,NUMA] Large hashes allocated during boot
- are distributed across NUMA nodes. Defaults on
- for 64-bit NUMA, 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>
-
- hest_disable [ACPI]
- Disable Hardware Error Source Table (HEST) support;
- corresponding firmware-first mode error processing
- logic will be disabled.
-
- 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.
-
- hlt [BUGS=ARM,SH]
-
- hpet= [X86-32,HPET] option to control HPET usage
- Format: { enable (default) | disable | force |
- verbose }
- disable: disable HPET and use PIT instead
- force: allow force enabled of undocumented chips (ICH4,
- VIA, nVidia)
- verbose: show contents of HPET registers during setup
-
- 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.
-
- hvc_iucv= [S390] Number of z/VM IUCV hypervisor console (HVC)
- terminal devices. Valid values: 0..8
- hvc_iucv_allow= [S390] Comma-separated list of z/VM user IDs.
- If specified, z/VM IUCV HVC accepts connections
- from listed z/VM user IDs only.
-
- keep_bootcon [KNL]
- Do not unregister boot console at start. This is only
- useful for debugging when something happens in the window
- between unregistering the boot console and initializing
- the real console.
-
- i2c_bus= [HW] Override the default board specific I2C bus speed
- or register an additional I2C bus that is not
- registered from board initialization code.
- Format:
- <bus_id>,<clkrate>
-
- i8042.debug [HW] Toggle i8042 debug mode
- 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.notimeout [HW] Ignore timeout condition signalled by controller
- 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.
-
- i915.invert_brightness=
- [DRM] Invert the sense of the variable that is used to
- set the brightness of the panel backlight. Normally a
- brightness value of 0 indicates backlight switched off,
- and the maximum of the brightness value sets the backlight
- to maximum brightness. If this parameter is set to 0
- (default) and the machine requires it, or this parameter
- is set to 1, a brightness value of 0 sets the backlight
- to maximum brightness, and the maximum of the brightness
- value switches the backlight off.
- -1 -- never invert brightness
- 0 -- machine default
- 1 -- force brightness inversion
-
- icn= [HW,ISDN]
- Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
-
- ide-core.nodma= [HW] (E)IDE subsystem
- Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc
- .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
- .cdrom .chs .ignore_cable are additional options
- See Documentation/ide/ide.txt.
-
- ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
- Claim all unknown PCI IDE storage controllers.
-
- idle= [X86]
- Format: idle=poll, idle=mwait, idle=halt, idle=nomwait
- Poll forces a polling idle loop that can slightly
- improve 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
-
- ignore_loglevel [KNL]
- Ignore loglevel setting - this will print /all/
- kernel messages to the console. Useful for debugging.
- We also add it as printk module parameter, so users
- could change it dynamically, usually by
- /sys/module/printk/parameters/ignore_loglevel.
-
- ihash_entries= [KNL]
- Set number of hash buckets for inode cache.
-
- ima_audit= [IMA]
- Format: { "0" | "1" }
- 0 -- integrity auditing messages. (Default)
- 1 -- enable informational integrity auditing messages.
-
- ima_hash= [IMA]
- Format: { "sha1" | "md5" }
- default: "sha1"
-
- ima_tcb [IMA]
- Load a policy which meets the needs of the Trusted
- Computing Base. This means IMA will measure all
- programs exec'd, files mmap'd for exec, and all files
- opened for read by uid=0.
-
- 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>
-
- intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
- on
- Enable intel iommu driver.
- 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.
- sp_off [Default Off]
- By default, super page will be supported if Intel IOMMU
- has the capability. With this option, super page will
- not be supported.
-
- intel_idle.max_cstate= [KNL,HW,ACPI,X86]
- 0 disables intel_idle and fall back on acpi_idle.
- 1 to 6 specify maximum depth of C-state.
-
- intremap= [X86-64, Intel-IOMMU]
- on enable Interrupt Remapping (default)
- off disable Interrupt Remapping
- nosid disable Source ID checking
- no_x2apic_optout
- BIOS x2APIC opt-out request will be ignored
-
- iomem= Disable strict checking of access to MMIO memory
- strict regions from userspace.
- relaxed
-
- iommu= [x86]
- off
- force
- noforce
- biomerge
- panic
- nopanic
- merge
- nomerge
- forcesac
- soft
- pt [x86, IA-64]
- group_mf [x86, IA-64]
-
-
- io7= [HW] IO7 for Marvel based alpha systems
- See comment before marvel_specify_io7 in
- arch/alpha/kernel/core_marvel.c.
-
- io_delay= [X86] 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
-
- ip= [IP_PNP]
- See Documentation/filesystems/nfs/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.
-
- 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. You can move a process onto or off an
- "isolated" CPU via the CPU affinity syscalls or cpuset.
- <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.
-
- keepinitrd [HW,ARM]
-
- kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] 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.
-
- kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port.
- Format: <Controller#>[,poll interval]
- The controller # is the number of the ehci usb debug
- port as it is probed via PCI. The poll interval is
- optional and is the number seconds in between
- each poll cycle to the debug port in case you need
- the functionality for interrupting the kernel with
- gdb or control-c on the dbgp connection. When
- not using this parameter you use sysrq-g to break into
- the kernel debugger.
-
- kgdboc= [KGDB,HW] kgdb over consoles.
- Requires a tty driver that supports console polling,
- or a supported polling keyboard driver (non-usb).
- Serial only format: <serial_device>[,baud]
- keyboard only format: kbd
- keyboard and serial format: kbd,<serial_device>[,baud]
- Optional Kernel mode setting:
- kms, kbd format: kms,kbd
- kms, kbd and serial format: kms,kbd,<ser_dev>[,baud]
-
- kgdbwait [KGDB] Stop kernel execution and enter the
- kernel debugger at the earliest opportunity.
-
- kmac= [MIPS] korina ethernet MAC address.
- Configure the RouterBoard 532 series on-chip
- Ethernet adapter MAC address.
-
- kmemleak= [KNL] Boot-time kmemleak enable/disable
- Valid arguments: on, off
- Default: on
-
- kstack=N [X86] Print N words from the kernel stack
- in oops dumps.
-
- kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
- Default is 0 (don't ignore, but inject #GP)
-
- kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
- KVM MMU at runtime.
- Default is 0 (off)
-
- kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
- Default is 1 (enabled)
-
- kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
- for all guests.
- Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
-
- kvm-intel.ept= [KVM,Intel] Disable extended page tables
- (virtualized MMU) support on capable Intel chips.
- Default is 1 (enabled)
-
- kvm-intel.emulate_invalid_guest_state=
- [KVM,Intel] Enable emulation of invalid guest states
- Default is 0 (disabled)
-
- kvm-intel.flexpriority=
- [KVM,Intel] Disable FlexPriority feature (TPR shadow).
- Default is 1 (enabled)
-
- kvm-intel.nested=
- [KVM,Intel] Enable VMX nesting (nVMX).
- Default is 0 (disabled)
-
- kvm-intel.unrestricted_guest=
- [KVM,Intel] Disable unrestricted guest feature
- (virtualized real and unpaged mode) on capable
- Intel chips. Default is 1 (enabled)
-
- kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
- feature (tagged TLBs) on capable Intel chips.
- Default is 1 (enabled)
-
- l2cr= [PPC]
-
- l3cr= [PPC]
-
- lapic [X86-32,APIC] Enable the local APIC even if BIOS
- disabled it.
-
- lapic_timer_c2_ok [X86,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.ignore_hpa= [LIBATA] Ignore HPA limit
- libata.ignore_hpa=0 keep BIOS limits (default)
- libata.ignore_hpa=1 ignore limits, using full disk
-
- 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.
-
- * dump_id: dump IDENTIFY data.
-
- If there are multiple matching configurations changing
- the same attribute, the last one is used.
-
- memblock=debug [KNL] Enable memblock debug messages.
-
- load_ramdisk= [RAM] List of ramdisks to load from floppy
- See Documentation/blockdev/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[KMG] Sets the size of the printk ring buffer,
- in bytes. 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>
-
- machvec= [IA-64] Force the use of a particular machine-vector
- (machvec) in a generic kernel.
- Example: machvec=hpzx1_swiotlb
-
- machtype= [Loongson] Share the same kernel image file between different
- yeeloong laptop.
- Example: machtype=lemote-yeeloong-2f-7inch
-
- max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
- than or equal to this physical address is ignored.
-
- 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_loop= [LOOP] The number of loop block devices that get
- (loop.max_loop) unconditionally pre-created at init time. The default
- number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
- of statically allocating a predefined number, loop
- devices can be requested on-demand with the
- /dev/loop-control interface.
-
- mce [X86-32] Machine Check Exception
-
- mce=option [X86-64] See Documentation/x86/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.
-
- memchunk=nn[KMG]
- [KNL,SH] Allow user to override the default size for
- per-device physically contiguous DMA buffers.
-
- memmap=exactmap [KNL,X86] 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
-
- memory_corruption_check=0/1 [X86]
- Some BIOSes seem to corrupt the first 64k of
- memory when doing things like suspend/resume.
- Setting this option will scan the memory
- looking for corruption. Enabling this will
- both detect corruption and prevent the kernel
- from using the memory being corrupted.
- However, its intended as a diagnostic tool; if
- repeatable BIOS-originated corruption always
- affects the same memory, you can use memmap=
- to prevent the kernel from using that memory.
-
- memory_corruption_check_size=size [X86]
- By default it checks for corruption in the low
- 64k, making this memory unavailable for normal
- use. Use this parameter to scan for
- corruption in more or less memory.
-
- memory_corruption_check_period=seconds [X86]
- By default it checks for corruption every 60
- seconds. Use this parameter to check at some
- other rate. 0 disables periodic checking.
-
- memtest= [KNL,X86] Enable memtest
- Format: <integer>
- default : 0 <disable>
- Specifies the number of memtest passes to be
- performed. Each pass selects another test
- pattern from a given set of patterns. Memtest
- fills the memory with this pattern, validates
- memory contents and reserves bad memory
- regions that are detected.
-
- 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]
-
- min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
- physical address is ignored.
-
- mini2440= [ARM,HW,KNL]
- Format:[0..2][b][c][t]
- Default: "0tb"
- MINI2440 configuration specification:
- 0 - The attached screen is the 3.5" TFT
- 1 - The attached screen is the 7" TFT
- 2 - The VGA Shield is attached (1024x768)
- Leaving out the screen size parameter will not load
- the TFT driver, and the framebuffer will be left
- unconfigured.
- b - Enable backlight. The TFT backlight pin will be
- linked to the kernel VESA blanking code and a GPIO
- LED. This parameter is not necessary when using the
- VGA shield.
- c - Enable the s3c camera interface.
- t - Reserved for enabling touchscreen support. The
- touchscreen support is not enabled in the mainstream
- kernel as of 2.6.30, a preliminary port can be found
- in the "bleeding edge" mini2440 support kernel at
- http://repo.or.cz/w/linux-2.6/mini2440.git
-
- 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
-
- movablecore=nn[KMG] [KNL,X86,IA-64,PPC] 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.
-
- 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.
-
- multitce=off [PPC] This parameter disables the use of the pSeries
- firmware feature for updating multiple TCE entries
- at a time.
-
- onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration
-
- Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
-
- boundary - index of last SLC block on Flex-OneNAND.
- The remaining blocks are configured as MLC blocks.
- lock - Configure if Flex-OneNAND boundary should be locked.
- Once locked, the boundary cannot be changed.
- 1 indicates lock status, 0 indicates unlock status.
-
- 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')
-
- mtrr_chunk_size=nn[KMG] [X86]
- used for mtrr cleanup. It is largest continuous 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.
-
- n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
-
- 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 is 0.
-
- nfsaddrs= [NFS] Deprecated. Use ip= instead.
- See Documentation/filesystems/nfs/nfsroot.txt.
-
- nfsroot= [NFS] nfs root filesystem for disk-less boxes.
- See Documentation/filesystems/nfs/nfsroot.txt.
-
- nfsrootdebug [NFS] enable nfsroot debugging messages.
- See Documentation/filesystems/nfs/nfsroot.txt.
-
- nfs.callback_tcpport=
- [NFS] set the TCP port on which the NFSv4 callback
- channel should listen.
-
- nfs.cache_getent=
- [NFS] sets the pathname to the program which is used
- to update the NFS client cache entries.
-
- nfs.cache_getent_timeout=
- [NFS] sets the timeout after which an attempt to
- update a cache entry is deemed to have failed.
-
- 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.
-
- nfs.max_session_slots=
- [NFSv4.1] Sets the maximum number of session slots
- the client will attempt to negotiate with the server.
- This limits the number of simultaneous RPC requests
- that the client can send to the NFSv4.1 server.
- Note that there is little point in setting this
- value higher than the max_tcp_slot_table_limit.
-
- nfs.nfs4_disable_idmapping=
- [NFSv4] When set to the default of '1', this option
- ensures that both the RPC level authentication
- scheme and the NFS level operations agree to use
- numeric uids/gids if the mount is using the
- 'sec=sys' security flavour. In effect it is
- disabling idmapping, which can make migration from
- legacy NFSv2/v3 systems to NFSv4 easier.
- Servers that do not support this mode of operation
- will be autodetected by the client, and it will fall
- back to using the idmapper.
- To turn off this behaviour, set the value to '0'.
-
- nfs.send_implementation_id =
- [NFSv4.1] Send client implementation identification
- information in exchange_id requests.
- If zero, no implementation identification information
- will be sent.
- The default is to send the implementation identification
- information.
-
- nfsd.nfs4_disable_idmapping=
- [NFSv4] When set to the default of '1', the NFSv4
- server will return only numeric uids and gids to
- clients using auth_sys, and will accept numeric uids
- and gids from such clients. This is intended to ease
- migration from NFSv2/v3.
-
- objlayoutdriver.osd_login_prog=
- [NFS] [OBJLAYOUT] sets the pathname to the program which
- is used to automatically discover and login into new
- osd-targets. Please see:
- Documentation/filesystems/pnfs.txt for more explanations
-
- nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
- when a NMI is triggered.
- Format: [state][,regs][,debounce][,die]
-
- nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
- Format: [panic,][nopanic,][num]
- Valid num: 0
- 0 - turn nmi_watchdog off
- When panic is specified, panic when an NMI watchdog
- timeout occurs (or 'nopanic' to override the opposite
- default).
- This is useful when you use a panic=... timeout and
- need the box quickly up again.
-
- netpoll.carrier_timeout=
- [NET] Specifies amount of time (in seconds) that
- netpoll should wait for a carrier. By default netpoll
- waits 4 seconds.
-
- no387 [BUGS=X86-32] Tells the kernel to use the 387 maths
- emulation library even if a 387 maths coprocessor
- is present.
-
- 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.
- To facilitate more flexible debugging, we also add
- console_suspend, a printk module parameter to control
- it. Users could use console_suspend (usually
- /sys/module/printk/parameters/console_suspend) to
- turn on/off it dynamically.
-
- 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.
-
- noautogroup Disable scheduler automatic task group creation.
-
- nobats [PPC] Do not use BATs for mapping kernel lowmem
- on "Classic" PPC cores.
-
- nocache [ARM]
-
- noclflush [BUGS=X86] Don't use the CLFLUSH instruction
-
- nodelayacct [KNL] Disable per-task delay accounting
-
- nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
-
- nodsp [SH] Disable hardware DSP at boot time.
-
- noefi [X86] Disable EFI runtime services support.
-
- noexec [IA-64]
-
- noexec [X86]
- On X86-32 available only on PAE configured kernels.
- noexec=on: enable non-executable mappings (default)
- noexec=off: disable non-executable mappings
-
- nosmep [X86]
- Disable SMEP (Supervisor Mode Execution Protection)
- even if it is supported by processor.
-
- 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
-
- nofpu [SH] Disable hardware FPU at boot time.
-
- 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.
-
- noxsave [BUGS=X86] Disables x86 extended register state save
- and restore using xsave. The kernel will fallback to
- enabling legacy floating-point and sse state.
-
- nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
- wfi(ARM) instruction doesn't work correctly and not to
- use it. This is also useful when using JTAG debugger.
-
- no-hlt [BUGS=X86-32] Tells the kernel that the hlt
- instruction doesn't work correctly and not to
- use it.
-
- no_file_caps Tells the kernel not to honor file capabilities. The
- only way then for a file to be executed with privilege
- is to be setuid root or executed by root.
-
- 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
-
- noiotrap [SH] Disables trapped I/O port accesses.
-
- noirqdebug [X86-32] Disables the code which attempts to detect and
- disable unhandled interrupt sources.
-
- no_timer_check [X86,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.
-
- nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
- remapping.
- [Deprecated - use intremap=off]
-
- nointroute [IA-64]
-
- nojitter [IA-64] Disables jitter checking for ITC timers.
-
- no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
-
- no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
- fault handling.
-
- no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
- steal time is computed, but won't influence scheduler
- behaviour
-
- 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).
-
- nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
- shutdown the other cpus. Instead use the REBOOT_VECTOR
- irq.
-
- nomodule Disable module load
-
- nopat [X86] Disable PAT (page attribute table extension of
- pagetables) support.
-
- norandmaps Don't use address space randomization. Equivalent to
- echo 0 > /proc/sys/kernel/randomize_va_space
-
- noreplace-paravirt [X86,IA-64,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.
-
- nordrand [X86] Disable the direct use of the RDRAND
- instruction even if it is supported by the
- processor. RDRAND is still available to user
- space applications.
-
- 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
-
- nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
-
- nowb [ARM]
-
- nox2apic [X86-64,APIC] Do not enable x2APIC mode.
-
- nptcg= [IA-64] Override max number of concurrent global TLB
- purges which is reported from either PAL_VM_SUMMARY or
- SAL PALO.
-
- nr_cpus= [SMP] Maximum number of processors that an SMP kernel
- could support. nr_cpus=n : n >= 1 limits the kernel to
- supporting 'n' processors. Later in runtime you can not
- use hotplug cpu feature to put more cpu back to online.
- just like you compile the kernel NR_CPUS=n
-
- nr_uarts= [SERIAL] maximum number of UARTs to be registered.
-
- 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.
-
- ohci1394_dma=early [HW] enable debugging via the ohci1394 driver.
- See Documentation/debugging-via-ohci1394.txt for more
- info.
-
- 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!
-
- omap_mux= [OMAP] Override bootloader pin multiplexing.
- Format: <mux_mode0.mode_name=value>...
- For example, to override I2C bus2:
- omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100
-
- oprofile.timer= [HW]
- Use timer interrupt instead of performance counters
-
- oprofile.cpu_type= Force an oprofile cpu type
- This might be useful if you have an older oprofile
- userland or if you want common events.
- Format: { arch_perfmon }
- arch_perfmon: [X86] Force use of architectural
- perfmon on Intel CPUs instead of the
- CPU specific event set.
- timer: [X86] Force use of architectural NMI
- timer mode (see also oprofile.timer
- for generic hr timer mode)
- [s390] Force legacy basic mode sampling
- (report cpu_type "timer")
-
- oops=panic Always panic on oopses. Default is to just kill the
- process, but there is a small probability of
- deadlocking the machine.
- This will also cause panics on machine check exceptions.
- Useful together with panic=30 to trigger a reboot.
-
- OSS [HW,OSS]
- See Documentation/sound/oss/oss-parameters.txt
-
- panic= [KNL] Kernel behaviour on panic: delay <timeout>
- timeout > 0: seconds before rebooting
- timeout = 0: wait forever
- timeout < 0: reboot immediately
- 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]
-
- 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/blockdev/paride.txt.
-
- pci=option[,option...] [PCI] various PCI subsystem options:
- earlydump [X86] dump PCI config space before the kernel
- changes anything
- off [X86] 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] Force use of PCI Configuration
- Mechanism 1.
- conf2 [X86] 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] Disable use of MMCONFIG for PCI
- Configuration
- check_enable_amd_mmconf [X86] check for and enable
- properly configured MMIO access to PCI
- config space on AMD family 10h CPU
- 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.
- noioapicquirk [APIC] Disable all boot interrupt quirks.
- Safety option to keep boot IRQs enabled. This
- should never be necessary.
- ioapicreroute [APIC] Enable rerouting of boot IRQs to the
- primary IO-APIC for bridges that cannot disable
- boot IRQs. This fixes a source of spurious IRQs
- when the system masks IRQs.
- noioapicreroute [APIC] Disable workaround that uses the
- boot IRQ equivalent of an IRQ that connects to
- a chipset where boot IRQs cannot be disabled.
- The opposite of ioapicreroute.
- 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] Assign address space to expansion ROMs.
- Use with caution as certain devices share
- address decoders between ROMs and other
- resources.
- norom [X86] Do not assign address space to
- expansion ROMs that do not already have
- BIOS assigned address ranges.
- nobar [X86] Do not assign address space to the
- BARs that weren't assigned by the BIOS.
- irqmask=0xMMMM [X86] 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] Specify the physical address
- of the PIRQ table (normally generated
- by the BIOS) if it is outside the
- F0000h-100000h range.
- lastbus=N [X86] 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] Always assign all PCI bus
- numbers ourselves, overriding
- whatever the firmware may have done.
- usepirqmask [X86] 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] Do not use ACPI for IRQ routing
- or for PCI scanning.
- use_crs [X86] Use PCI host bridge window information
- from ACPI. On BIOSes from 2008 or later, this
- is enabled by default. If you need to use this,
- please report a bug.
- nocrs [X86] Ignore PCI host bridge windows from ACPI.
- If you need to use this, please report a bug.
- 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.
- resource_alignment=
- Format:
- [<order of align>@][<domain>:]<bus>:<slot>.<func>[; ...]
- Specifies alignment and device to reassign
- aligned memory resources.
- If <order of align> is not specified,
- PAGE_SIZE is used as alignment.
- PCI-PCI bridge can be specified, if resource
- windows need to be expanded.
- ecrc= Enable/disable PCIe ECRC (transaction layer
- end-to-end CRC checking).
- bios: Use BIOS/firmware settings. This is the
- the default.
- off: Turn ECRC off
- on: Turn ECRC on.
- realloc= Enable/disable reallocating PCI bridge resources
- if allocations done by BIOS are too small to
- accommodate resources required by all child
- devices.
- off: Turn realloc off
- on: Turn realloc on
- realloc same as realloc=on
- noari do not use PCIe ARI.
- pcie_scan_all Scan all possible PCIe devices. Otherwise we
- only look for one device below a PCIe downstream
- port.
-
- pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
- Management.
- off Disable ASPM.
- force Enable ASPM even on devices that claim not to support it.
- WARNING: Forcing ASPM on may cause system lockups.
-
- pcie_hp= [PCIE] PCI Express Hotplug driver options:
- nomsi Do not use MSI for PCI Express Native Hotplug (this
- makes all PCIe ports use INTx for hotplug services).
-
- pcie_ports= [PCIE] PCIe ports handling:
- auto Ask the BIOS whether or not to use native PCIe services
- associated with PCIe ports (PME, hot-plug, AER). Use
- them only if that is allowed by the BIOS.
- native Use native PCIe services associated with PCIe ports
- unconditionally.
- compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
- ports driver.
-
- pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
- nomsi Do not use MSI for native PCIe PME signaling (this makes
- all PCIe root ports use INTx for all services).
-
- pcmv= [HW,PCMCIA] BadgePAD 4
-
- pd. [PARIDE]
- See Documentation/blockdev/paride.txt.
-
- pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
- boot time.
- Format: { 0 | 1 }
- See arch/parisc/kernel/pdc_chassis.c
-
- percpu_alloc= Select which percpu first chunk allocator to use.
- Currently supported values are "embed" and "page".
- Archs may support subset or none of the selections.
- See comments in mm/percpu.c for details on each
- allocator. This parameter is primarily for debugging
- and performance comparison.
-
- pf. [PARIDE]
- See Documentation/blockdev/paride.txt.
-
- pg. [PARIDE]
- See Documentation/blockdev/paride.txt.
-
- pirq= [SMP,APIC] Manual mp-table setup
- See Documentation/x86/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
-
- pnp.debug=1 [PNP]
- Enable PNP debug messages (depends on the
- CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time
- via /sys/module/pnp/parameters/debug. We always show
- current resource usage; turning this on also shows
- possible settings and some assignment information.
-
- 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).
-
- 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>....
-
- print-fatal-signals=
- [KNL] debug: print fatal signals
-
- If enabled, warn about various signal handling
- related application anomalies: too many signals,
- too many POSIX.1 timers, fatal signals causing a
- coredump - etc.
-
- If you hit the warning due to signal overflow,
- you might want to try "ulimit -i unlimited".
-
- default: off.
-
- printk.always_kmsg_dump=
- Trigger kmsg_dump for cases other than kernel oops or
- panics
- Format: <bool> (1/Y/y=enable, 0/N/n=disable)
- default: disabled
-
- printk.time= Show timing data prefixed to each printk message line
- Format: <bool> (1/Y/y=enable, 0/N/n=disable)
-
- 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
-
- 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.
-
- prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
- before loading.
- See Documentation/blockdev/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).
-
- pstore.backend= Specify the name of the pstore backend to use
-
- pt. [PARIDE]
- See Documentation/blockdev/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/blockdev/ramdisk.txt.
-
- ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
- See Documentation/blockdev/ramdisk.txt.
-
- rcutree.blimit= [KNL,BOOT]
- Set maximum number of finished RCU callbacks to process
- in one batch.
-
- rcutree.qhimark= [KNL,BOOT]
- Set threshold of queued
- RCU callbacks over which batch limiting is disabled.
-
- rcutree.qlowmark= [KNL,BOOT]
- Set threshold of queued RCU callbacks below which
- batch limiting is re-enabled.
-
- rcutree.rcu_cpu_stall_suppress= [KNL,BOOT]
- Suppress RCU CPU stall warning messages.
-
- rcutree.rcu_cpu_stall_timeout= [KNL,BOOT]
- Set timeout for RCU CPU stall warning messages.
-
- rcutorture.fqs_duration= [KNL,BOOT]
- Set duration of force_quiescent_state bursts.
-
- rcutorture.fqs_holdoff= [KNL,BOOT]
- Set holdoff time within force_quiescent_state bursts.
-
- rcutorture.fqs_stutter= [KNL,BOOT]
- Set wait time between force_quiescent_state bursts.
-
- rcutorture.irqreader= [KNL,BOOT]
- Test RCU readers from irq handlers.
-
- rcutorture.n_barrier_cbs= [KNL,BOOT]
- Set callbacks/threads for rcu_barrier() testing.
-
- rcutorture.nfakewriters= [KNL,BOOT]
- Set number of concurrent RCU writers. These just
- stress RCU, they don't participate in the actual
- test, hence the "fake".
-
- rcutorture.nreaders= [KNL,BOOT]
- Set number of RCU readers.
-
- rcutorture.onoff_holdoff= [KNL,BOOT]
- Set time (s) after boot for CPU-hotplug testing.
-
- rcutorture.onoff_interval= [KNL,BOOT]
- Set time (s) between CPU-hotplug operations, or
- zero to disable CPU-hotplug testing.
-
- rcutorture.shuffle_interval= [KNL,BOOT]
- Set task-shuffle interval (s). Shuffling tasks
- allows some CPUs to go into dyntick-idle mode
- during the rcutorture test.
-
- rcutorture.shutdown_secs= [KNL,BOOT]
- Set time (s) after boot system shutdown. This
- is useful for hands-off automated testing.
-
- rcutorture.stall_cpu= [KNL,BOOT]
- Duration of CPU stall (s) to test RCU CPU stall
- warnings, zero to disable.
-
- rcutorture.stall_cpu_holdoff= [KNL,BOOT]
- Time to wait (s) after boot before inducing stall.
-
- rcutorture.stat_interval= [KNL,BOOT]
- Time (s) between statistics printk()s.
-
- rcutorture.stutter= [KNL,BOOT]
- Time (s) to stutter testing, for example, specifying
- five seconds causes the test to run for five seconds,
- wait for five seconds, and so on. This tests RCU's
- ability to transition abruptly to and from idle.
-
- rcutorture.test_boost= [KNL,BOOT]
- Test RCU priority boosting? 0=no, 1=maybe, 2=yes.
- "Maybe" means test if the RCU implementation
- under test support RCU priority boosting.
-
- rcutorture.test_boost_duration= [KNL,BOOT]
- Duration (s) of each individual boost test.
-
- rcutorture.test_boost_interval= [KNL,BOOT]
- Interval (s) between each boost test.
-
- rcutorture.test_no_idle_hz= [KNL,BOOT]
- Test RCU's dyntick-idle handling. See also the
- rcutorture.shuffle_interval parameter.
-
- rcutorture.torture_type= [KNL,BOOT]
- Specify the RCU implementation to test.
-
- rcutorture.verbose= [KNL,BOOT]
- Enable additional printk() statements.
-
- 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/cgroups/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.
-
- reservelow= [X86]
- Format: nn[K]
- Set the amount of memory to reserve for BIOS at
- the bottom of the address space.
-
- reset_devices [KNL] Force drivers to reset the underlying device
- during initialization.
-
- resume= [SWSUSP]
- Specify the partition device for software suspend
- Format:
- {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
-
- 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
-
- resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to
- read the resume files
-
- resumewait [HIBERNATION] Wait (indefinitely) for resume device to show up.
- Useful for devices that are detected asynchronously
- (e.g. USB and MMC devices).
-
- hibernate= [HIBERNATION]
- noresume Don't check if there's a hibernation image
- present during boot.
- nocompress Don't compress/decompress hibernation images.
-
- 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
- See name_to_dev_t comment in init/do_mounts.c.
-
- 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).
-
- 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
-
- sched_debug [KNL] Enables verbose scheduler debug messages.
-
- skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate
- xtime_lock contention on larger systems, and/or RCU lock
- contention on all systems with CONFIG_MAXSMP set.
- Format: { "0" | "1" }
- 0 -- disable. (may be 1 via CONFIG_CMDLINE="skew_tick=1"
- 1 -- enable.
- Note: increases power consumption, thus should only be
- enabled if running jitter sensitive (HPC/RT) workloads.
-
- 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.
-
- 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.
-
- apparmor= [APPARMOR] Disable or enable AppArmor at boot time
- Format: { "0" | "1" }
- See security/apparmor/Kconfig help text
- 0 -- disable.
- 1 -- enable.
- Default value is set via kernel config option.
-
- 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.
-
- simeth= [IA-64]
- simscsi=
-
- slram= [HW,MTD]
-
- slab_max_order= [MM, SLAB]
- Determines the maximum allowed order for slabs.
- A high setting may cause OOMs due to memory
- fragmentation. Defaults to 1 for systems with
- more than 32MB of RAM, 0 otherwise.
-
- 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 minimum 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
-
- softlockup_panic=
- [KNL] Should the soft-lockup detector generate panics.
- Format: <integer>
-
- sonypi.*= [HW] Sony Programmable I/O Control Device driver
- See Documentation/laptops/sonypi.txt
-
- specialix= [HW,SERIAL] Specialix multi-serial port adapter
- See Documentation/serial/specialix.txt.
-
- spia_io_base= [HW,MTD]
- spia_fio_base=
- spia_pedr=
- spia_peddr=
-
- stacktrace [FTRACE]
- Enabled the stack tracer on boot up.
-
- stacktrace_filter=[function-list]
- [FTRACE] Limit the functions that the stack tracer
- will trace at boot up. function-list is a comma separated
- list of functions. This list can be changed at run
- time by the stack_trace_filter file in the debugfs
- tracing directory. Note, this enables stack tracing
- and the stacktrace above is not needed.
-
- 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.min_resvport=
- sunrpc.max_resvport=
- [NFS,SUNRPC]
- SunRPC servers often require that client requests
- originate from a privileged port (i.e. a port in the
- range 0 < portnr < 1024).
- An administrator who wishes to reserve some of these
- ports for other uses may adjust the range that the
- kernel's sunrpc client considers to be privileged
- using these two parameters to set the minimum and
- maximum port values.
-
- 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)
-
- sunrpc.tcp_slot_table_entries=
- sunrpc.udp_slot_table_entries=
- [NFS,SUNRPC]
- Sets the upper limit on the number of simultaneous
- RPC calls that can be sent from the client to a
- server. Increasing these values may allow you to
- improve throughput, but will also increase the
- amount of memory reserved for use by the client.
-
- swapaccount[=0|1]
- [KNL] Enable accounting of swap in memory resource
- controller if no parameter or 1 is given or disable
- it if 0 is given (See Documentation/cgroups/memory.txt)
-
- swiotlb= [IA-64] Number of I/O TLB slabs
-
- switches= [HW,M68k]
-
- sysfs.deprecated=0|1 [KNL]
- Enable/disable old style sysfs layout for old udev
- on older distributions. When this option is enabled
- very new udev will not work anymore. When this option
- is disabled (or CONFIG_SYSFS_DEPRECATED not compiled)
- in older udev will not work anymore.
- Default depends on CONFIG_SYSFS_DEPRECATED_V2 set in
- the kernel configuration.
-
- sysrq_always_enabled
- [KNL]
- Ignore sysrq setting - this boot parameter will
- neutralize any effect of /proc/sys/kernel/sysrq.
- Useful for debugging.
-
- 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>: override 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)
-
- threadirqs [KNL]
- Force threading of all interrupt handlers except those
- marked explicitly IRQF_NO_THREAD.
-
- topology= [S390]
- Format: {off | on}
- Specify if the kernel should make use of the cpu
- topology information if the hardware supports this.
- The scheduler will make use of this information and
- e.g. base its process migration decisions on it.
- Default is on.
-
- tp720= [HW,PS2]
-
- tpm_suspend_pcr=[HW,TPM]
- Format: integer pcr id
- Specify that at suspend time, the tpm driver
- should extend the specified pcr with zeros,
- as a workaround for some chips which fail to
- flush the last written pcr on TPM_SaveState.
- This will guarantee that all the other pcrs
- are saved.
-
- trace_buf_size=nn[KMG]
- [FTRACE] will set tracing buffer size.
-
- trace_event=[event-list]
- [FTRACE] Set and start specified trace events in order
- to facilitate early boot debugging.
- See also Documentation/trace/events.txt
-
- transparent_hugepage=
- [KNL]
- Format: [always|madvise|never]
- Can be used to control the default behavior of the system
- with respect to transparent hugepages.
- See Documentation/vm/transhuge.txt for more details.
-
- tsc= Disable clocksource stability checks for TSC.
- Format: <string>
- [x86] reliable: mark tsc clocksource as reliable, this
- disables clocksource verification at runtime, as well
- as the stability checks done at bootup. Used to enable
- high-resolution timer mode on older hardware, and in
- virtualized environment.
- [x86] noirqtime: Do not use TSC to do irq accounting.
- Used to run time disable IRQ_TIME_ACCOUNTING on any
- platforms where RDTSC is slow and this accounting
- can add overhead.
-
- 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
-
- udbg-immortal [PPC] When debugging early kernel crashes that
- happen after console_init() and before a proper
- console driver takes over, this boot options might
- help "seeing" what's going on.
-
- uhash_entries= [KNL,NET]
- Set number of hash buckets for UDP/UDP-Lite connections
-
- 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] Cause panic on unknown NMI.
-
- usbcore.authorized_default=
- [USB] Default USB device authorization:
- (default -1 = authorized except for wireless USB,
- 0 = not authorized, 1 = authorized)
-
- 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.
-
- usbcore.usbfs_snoop=
- [USB] Set to log all usbfs traffic (default 0 = off).
-
- usbcore.blinkenlights=
- [USB] Set to cycle leds on hubs (default 0 = off).
-
- usbcore.old_scheme_first=
- [USB] Start with the old device initialization
- scheme (default 0 = off).
-
- usbcore.usbfs_memory_mb=
- [USB] Memory limit (in MB) for buffers allocated by
- usbfs (default = 16, 0 = max = 2047).
-
- usbcore.use_both_schemes=
- [USB] Try the other device initialization scheme
- if the first one fails (default 1 = enabled).
-
- usbcore.initial_descriptor_timeout=
- [USB] Specifies timeout for the initial 64-byte
- USB_REQ_GET_DESCRIPTOR request in milliseconds
- (default 5000 = 5.0 seconds).
-
- usbhid.mousepoll=
- [USBHID] The interval which mice are to be polled at.
-
- usb-storage.delay_use=
- [UMS] The delay in seconds before a new device is
- scanned for Logical Units (default 5).
-
- usb-storage.quirks=
- [UMS] A list of quirks entries to supplement or
- override the built-in unusual_devs list. List
- entries are separated by commas. Each entry has
- the form VID:PID:Flags where VID and PID are Vendor
- and Product ID values (4-digit hex numbers) and
- Flags is a set of characters, each corresponding
- to a common usb-storage quirk flag as follows:
- a = SANE_SENSE (collect more than 18 bytes
- of sense data);
- b = BAD_SENSE (don't collect more than 18
- bytes of sense data);
- c = FIX_CAPACITY (decrease the reported
- device capacity by one sector);
- d = NO_READ_DISC_INFO (don't use
- READ_DISC_INFO command);
- e = NO_READ_CAPACITY_16 (don't use
- READ_CAPACITY_16 command);
- h = CAPACITY_HEURISTICS (decrease the
- reported device capacity by one
- sector if the number is odd);
- i = IGNORE_DEVICE (don't bind to this
- device);
- l = NOT_LOCKABLE (don't try to lock and
- unlock ejectable media);
- m = MAX_SECTORS_64 (don't transfer more
- than 64 sectors = 32 KB at a time);
- n = INITIAL_READ10 (force a retry of the
- initial READ(10) command);
- o = CAPACITY_OK (accept the capacity
- reported by the device);
- r = IGNORE_RESIDUE (the device reports
- bogus residue values);
- s = SINGLE_LUN (the device has only one
- Logical Unit);
- w = NO_WP_DETECT (don't test whether the
- medium is write-protected).
- Example: quirks=0419:aaf5:rl,0421:0433:rc
-
- user_debug= [KNL,ARM]
- Format: <int>
- See arch/arm/Kconfig.debug help text.
- 1 - undefined instruction events
- 2 - system calls
- 4 - invalid data aborts
- 8 - SIGSEGV faults
- 16 - SIGBUS faults
- Example: user_debug=31
-
- userpte=
- [X86] Flags controlling user PTE allocations.
-
- nohigh = do not allocate PTE pages in
- HIGHMEM regardless of setting
- of CONFIG_HIGHPTE.
-
- vdso= [X86,SH]
- vdso=2: enable compat VDSO (default with COMPAT_VDSO)
- vdso=1: enable VDSO (default)
- vdso=0: disable VDSO mapping
-
- vdso32= [X86]
- 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.
-
- virtio_mmio.device=
- [VMMIO] Memory mapped virtio (platform) device.
-
- <size>@<baseaddr>:<irq>[:<id>]
- where:
- <size> := size (can use standard suffixes
- like K, M and G)
- <baseaddr> := physical base address
- <irq> := interrupt number (as passed to
- request_irq())
- <id> := (optional) platform device id
- example:
- virtio_mmio.device=1K@0x100b0000:48:7
-
- Can be used multiple times for multiple devices.
-
- vga= [BOOT,X86-32] Select a particular video mode
- See Documentation/x86/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>
-
- vsyscall= [X86-64]
- Controls the behavior of vsyscalls (i.e. calls to
- fixed addresses of 0xffffffffff600x00 from legacy
- code). Most statically-linked binaries and older
- versions of glibc use these calls. Because these
- functions are at fixed addresses, they make nice
- targets for exploits that can control RIP.
-
- emulate [default] Vsyscalls turn into traps and are
- emulated reasonably safely.
-
- native Vsyscalls are native syscall instructions.
- This is a little bit faster than trapping
- and makes a few dynamic recompilers work
- better than they would in emulation mode.
- It also makes exploits much easier to write.
-
- none Vsyscalls don't work at all. This makes
- them quite hard to use for exploits but
- might break your system.
-
- vt.cur_default= [VT] Default cursor shape.
- Format: 0xCCBBAA, where AA, BB, and CC are the same as
- the parameters of the <Esc>[?A;B;Cc escape sequence;
- see VGA-softcursor.txt. Default: 2 = underline.
-
- 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.
-
- vt.global_cursor_default=
- [VT]
- Format=<-1|0|1>
- Set system-wide default for whether a cursor
- is shown on new VTs. Default is -1,
- i.e. cursors will be created by default unless
- overridden by individual drivers. 0 will hide
- cursors, 1 will display them.
-
- watchdog timers [HW,WDT] For information on watchdog timers,
- see Documentation/watchdog/watchdog-parameters.txt
- or other driver-specific files in the
- Documentation/watchdog/ directory.
-
- x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of
- default x2apic cluster mode on platforms
- supporting x2apic.
-
- x86_mrst_timer= [X86-32,APBT]
- Choose timer option for x86 Moorestown MID platform.
- Two valid options are apbt timer only and lapic timer
- plus one apbt timer for broadcast timer.
- x86_mrst_timer=apbt_only | lapic_and_apbt
-
- xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks.
- xd_geo= See header of drivers/block/xd.c.
-
- xen_emul_unplug= [HW,X86,XEN]
- Unplug Xen emulated devices
- Format: [unplug0,][unplug1]
- ide-disks -- unplug primary master IDE devices
- aux-ide-disks -- unplug non-primary-master IDE devices
- nics -- unplug network devices
- all -- unplug all emulated devices (NICs and IDE disks)
- unnecessary -- unplugging emulated devices is
- unnecessary even if the host did not respond to
- the unplug protocol
- never -- do not unplug even if version check succeeds
-
- xirc2ps_cs= [NET,PCMCIA]
- Format:
- <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
-
-______________________________________________________________________
-
-TODO:
-
- Add more DRM drivers.