2891 lines
98 KiB
Plaintext
2891 lines
98 KiB
Plaintext
Kernel Parameters
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~~~~~~~~~~~~~~~~~
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The following is a consolidated list of the kernel parameters as implemented
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(mostly) by the __setup() macro and sorted into English Dictionary order
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(defined as ignoring all punctuation and sorting digits before letters in a
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case insensitive manner), and with descriptions where known.
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Module parameters for loadable modules are specified only as the
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parameter name with optional '=' and value as appropriate, such as:
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modprobe usbcore blinkenlights=1
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Module parameters for modules that are built into the kernel image
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are specified on the kernel command line with the module name plus
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'.' plus parameter name, with '=' and value if appropriate, such as:
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usbcore.blinkenlights=1
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Hyphens (dashes) and underscores are equivalent in parameter names, so
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log_buf_len=1M print-fatal-signals=1
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can also be entered as
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log-buf-len=1M print_fatal_signals=1
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This document may not be entirely up to date and comprehensive. The command
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"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
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module. Loadable modules, after being loaded into the running kernel, also
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reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
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parameters may be changed at runtime by the command
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"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
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The parameters listed below are only valid if certain kernel build options were
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enabled and if respective hardware is present. The text in square brackets at
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the beginning of each description states the restrictions within which a
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parameter is applicable:
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ACPI ACPI support is enabled.
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AGP AGP (Accelerated Graphics Port) is enabled.
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ALSA ALSA sound support is enabled.
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APIC APIC support is enabled.
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APM Advanced Power Management support is enabled.
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ARM ARM architecture is enabled.
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AVR32 AVR32 architecture is enabled.
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AX25 Appropriate AX.25 support is enabled.
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BLACKFIN Blackfin architecture is enabled.
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DRM Direct Rendering Management support is enabled.
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DYNAMIC_DEBUG Build in debug messages and enable them at runtime
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EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
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EFI EFI Partitioning (GPT) is enabled
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EIDE EIDE/ATAPI support is enabled.
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EVM Extended Verification Module
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FB The frame buffer device is enabled.
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FTRACE Function tracing enabled.
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GCOV GCOV profiling is enabled.
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HW Appropriate hardware is enabled.
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IA-64 IA-64 architecture is enabled.
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IMA Integrity measurement architecture is enabled.
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IOSCHED More than one I/O scheduler is enabled.
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IP_PNP IP DHCP, BOOTP, or RARP is enabled.
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IPV6 IPv6 support is enabled.
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ISAPNP ISA PnP code is enabled.
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ISDN Appropriate ISDN support is enabled.
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JOY Appropriate joystick support is enabled.
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KGDB Kernel debugger support is enabled.
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KVM Kernel Virtual Machine support is enabled.
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LIBATA Libata driver is enabled
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LP Printer support is enabled.
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LOOP Loopback device support is enabled.
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M68k M68k architecture is enabled.
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These options have more detailed description inside of
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Documentation/m68k/kernel-options.txt.
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MCA MCA bus support is enabled.
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MDA MDA console support is enabled.
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MIPS MIPS architecture is enabled.
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MOUSE Appropriate mouse support is enabled.
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MSI Message Signaled Interrupts (PCI).
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MTD MTD (Memory Technology Device) support is enabled.
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NET Appropriate network support is enabled.
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NUMA NUMA support is enabled.
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NFS Appropriate NFS support is enabled.
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OSS OSS sound support is enabled.
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PV_OPS A paravirtualized kernel is enabled.
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PARIDE The ParIDE (parallel port IDE) subsystem is enabled.
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PARISC The PA-RISC architecture is enabled.
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PCI PCI bus support is enabled.
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PCIE PCI Express support is enabled.
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PCMCIA The PCMCIA subsystem is enabled.
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PNP Plug & Play support is enabled.
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PPC PowerPC architecture is enabled.
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PPT Parallel port support is enabled.
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PS2 Appropriate PS/2 support is enabled.
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RAM RAM disk support is enabled.
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S390 S390 architecture is enabled.
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SCSI Appropriate SCSI support is enabled.
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A lot of drivers have their options described inside
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the Documentation/scsi/ sub-directory.
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SECURITY Different security models are enabled.
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SELINUX SELinux support is enabled.
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APPARMOR AppArmor support is enabled.
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SERIAL Serial support is enabled.
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SH SuperH architecture is enabled.
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SMP The kernel is an SMP kernel.
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SPARC Sparc architecture is enabled.
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SWSUSP Software suspend (hibernation) is enabled.
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SUSPEND System suspend states are enabled.
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TPM TPM drivers are enabled.
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TS Appropriate touchscreen support is enabled.
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UMS USB Mass Storage support is enabled.
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USB USB support is enabled.
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USBHID USB Human Interface Device support is enabled.
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V4L Video For Linux support is enabled.
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VGA The VGA console has been enabled.
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VT Virtual terminal support is enabled.
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WDT Watchdog support is enabled.
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XT IBM PC/XT MFM hard disk support is enabled.
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X86-32 X86-32, aka i386 architecture is enabled.
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X86-64 X86-64 architecture is enabled.
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More X86-64 boot options can be found in
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Documentation/x86/x86_64/boot-options.txt .
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X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64)
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XEN Xen support is enabled
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In addition, the following text indicates that the option:
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BUGS= Relates to possible processor bugs on the said processor.
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KNL Is a kernel start-up parameter.
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BOOT Is a boot loader parameter.
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Parameters denoted with BOOT are actually interpreted by the boot
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loader, and have no meaning to the kernel directly.
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Do not modify the syntax of boot loader parameters without extreme
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need or coordination with <Documentation/x86/boot.txt>.
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There are also arch-specific kernel-parameters not documented here.
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See for example <Documentation/x86/x86_64/boot-options.txt>.
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Note that ALL kernel parameters listed below are CASE SENSITIVE, and that
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a trailing = on the name of any parameter states that that parameter will
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be entered as an environment variable, whereas its absence indicates that
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it will appear as a kernel argument readable via /proc/cmdline by programs
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running once the system is up.
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The number of kernel parameters is not limited, but the length of the
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complete command line (parameters including spaces etc.) is limited to
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a fixed number of characters. This limit depends on the architecture
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and is between 256 and 4096 characters. It is defined in the file
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./include/asm/setup.h as COMMAND_LINE_SIZE.
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Finally, the [KMG] suffix is commonly described after a number of kernel
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parameter values. These 'K', 'M', and 'G' letters represent the _binary_
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multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
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bytes respectively. Such letter suffixes can also be entirely omitted.
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acpi= [HW,ACPI,X86]
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Advanced Configuration and Power Interface
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Format: { force | off | strict | noirq | rsdt }
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force -- enable ACPI if default was off
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off -- disable ACPI if default was on
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noirq -- do not use ACPI for IRQ routing
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strict -- Be less tolerant of platforms that are not
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strictly ACPI specification compliant.
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rsdt -- prefer RSDT over (default) XSDT
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copy_dsdt -- copy DSDT to memory
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See also Documentation/power/runtime_pm.txt, pci=noacpi
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acpi_rsdp= [ACPI,EFI,KEXEC]
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Pass the RSDP address to the kernel, mostly used
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on machines running EFI runtime service to boot the
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second kernel for kdump.
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acpi_apic_instance= [ACPI, IOAPIC]
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Format: <int>
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2: use 2nd APIC table, if available
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1,0: use 1st APIC table
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default: 0
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acpi_backlight= [HW,ACPI]
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acpi_backlight=vendor
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acpi_backlight=video
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If set to vendor, prefer vendor specific driver
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(e.g. thinkpad_acpi, sony_acpi, etc.) instead
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of the ACPI video.ko driver.
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acpi.debug_layer= [HW,ACPI,ACPI_DEBUG]
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acpi.debug_level= [HW,ACPI,ACPI_DEBUG]
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Format: <int>
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CONFIG_ACPI_DEBUG must be enabled to produce any ACPI
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debug output. Bits in debug_layer correspond to a
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_COMPONENT in an ACPI source file, e.g.,
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#define _COMPONENT ACPI_PCI_COMPONENT
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Bits in debug_level correspond to a level in
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ACPI_DEBUG_PRINT statements, e.g.,
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ACPI_DEBUG_PRINT((ACPI_DB_INFO, ...
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The debug_level mask defaults to "info". See
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Documentation/acpi/debug.txt for more information about
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debug layers and levels.
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Enable processor driver info messages:
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acpi.debug_layer=0x20000000
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Enable PCI/PCI interrupt routing info messages:
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acpi.debug_layer=0x400000
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Enable AML "Debug" output, i.e., stores to the Debug
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object while interpreting AML:
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acpi.debug_layer=0xffffffff acpi.debug_level=0x2
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Enable all messages related to ACPI hardware:
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acpi.debug_layer=0x2 acpi.debug_level=0xffffffff
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Some values produce so much output that the system is
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unusable. The "log_buf_len" parameter may be useful
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if you need to capture more output.
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acpi_irq_balance [HW,ACPI]
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ACPI will balance active IRQs
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default in APIC mode
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acpi_irq_nobalance [HW,ACPI]
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ACPI will not move active IRQs (default)
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default in PIC mode
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acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
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Format: <irq>,<irq>...
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acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
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use by PCI
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Format: <irq>,<irq>...
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acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT
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acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS
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Format: To spoof as Windows 98: ="Microsoft Windows"
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acpi_osi= [HW,ACPI] Modify list of supported OS interface strings
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acpi_osi="string1" # add string1 -- only one string
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acpi_osi="!string2" # remove built-in string2
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acpi_osi= # disable all strings
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acpi_pm_good [X86]
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Override the pmtimer bug detection: force the kernel
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to assume that this machine's pmtimer latches its value
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and always returns good values.
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acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
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Format: { level | edge | high | low }
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acpi_serialize [HW,ACPI] force serialization of AML methods
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acpi_skip_timer_override [HW,ACPI]
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Recognize and ignore IRQ0/pin2 Interrupt Override.
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For broken nForce2 BIOS resulting in XT-PIC timer.
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acpi_sleep= [HW,ACPI] Sleep options
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Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
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old_ordering, nonvs, sci_force_enable }
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See Documentation/power/video.txt for information on
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s3_bios and s3_mode.
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s3_beep is for debugging; it makes the PC's speaker beep
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as soon as the kernel's real-mode entry point is called.
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s4_nohwsig prevents ACPI hardware signature from being
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used during resume from hibernation.
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old_ordering causes the ACPI 1.0 ordering of the _PTS
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control method, with respect to putting devices into
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low power states, to be enforced (the ACPI 2.0 ordering
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of _PTS is used by default).
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nonvs prevents the kernel from saving/restoring the
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ACPI NVS memory during suspend/hibernation and resume.
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sci_force_enable causes the kernel to set SCI_EN directly
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on resume from S1/S3 (which is against the ACPI spec,
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but some broken systems don't work without it).
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acpi_use_timer_override [HW,ACPI]
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Use timer override. For some broken Nvidia NF5 boards
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that require a timer override, but don't have HPET
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acpi_enforce_resources= [ACPI]
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{ strict | lax | no }
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Check for resource conflicts between native drivers
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and ACPI OperationRegions (SystemIO and SystemMemory
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only). IO ports and memory declared in ACPI might be
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used by the ACPI subsystem in arbitrary AML code and
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can interfere with legacy drivers.
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strict (default): access to resources claimed by ACPI
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is denied; legacy drivers trying to access reserved
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resources will fail to bind to device using them.
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lax: access to resources claimed by ACPI is allowed;
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legacy drivers trying to access reserved resources
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will bind successfully but a warning message is logged.
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no: ACPI OperationRegions are not marked as reserved,
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no further checks are performed.
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add_efi_memmap [EFI; X86] Include EFI memory map in
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kernel's map of available physical RAM.
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agp= [AGP]
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{ off | try_unsupported }
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off: disable AGP support
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try_unsupported: try to drive unsupported chipsets
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(may crash computer or cause data corruption)
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ALSA [HW,ALSA]
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See Documentation/sound/alsa/alsa-parameters.txt
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alignment= [KNL,ARM]
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Allow the default userspace alignment fault handler
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behaviour to be specified. Bit 0 enables warnings,
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bit 1 enables fixups, and bit 2 sends a segfault.
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align_va_addr= [X86-64]
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Align virtual addresses by clearing slice [14:12] when
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allocating a VMA at process creation time. This option
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gives you up to 3% performance improvement on AMD F15h
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machines (where it is enabled by default) for a
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CPU-intensive style benchmark, and it can vary highly in
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a microbenchmark depending on workload and compiler.
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32: only for 32-bit processes
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64: only for 64-bit processes
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on: enable for both 32- and 64-bit processes
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off: disable for both 32- and 64-bit processes
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amd_iommu= [HW,X86-64]
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Pass parameters to the AMD IOMMU driver in the system.
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Possible values are:
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fullflush - enable flushing of IO/TLB entries when
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they are unmapped. Otherwise they are
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flushed before they will be reused, which
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is a lot of faster
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off - do not initialize any AMD IOMMU found in
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the system
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force_isolation - Force device isolation for all
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devices. The IOMMU driver is not
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allowed anymore to lift isolation
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requirements as needed. This option
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does not override iommu=pt
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amijoy.map= [HW,JOY] Amiga joystick support
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Map of devices attached to JOY0DAT and JOY1DAT
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Format: <a>,<b>
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See also Documentation/input/joystick.txt
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analog.map= [HW,JOY] Analog joystick and gamepad support
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Specifies type or capabilities of an analog joystick
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connected to one of 16 gameports
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Format: <type1>,<type2>,..<type16>
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apc= [HW,SPARC]
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Power management functions (SPARCstation-4/5 + deriv.)
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Format: noidle
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Disable APC CPU standby support. SPARCstation-Fox does
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not play well with APC CPU idle - disable it if you have
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APC and your system crashes randomly.
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apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
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Change the output verbosity whilst booting
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Format: { quiet (default) | verbose | debug }
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Change the amount of debugging information output
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when initialising the APIC and IO-APIC components.
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autoconf= [IPV6]
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See Documentation/networking/ipv6.txt.
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show_lapic= [APIC,X86] Advanced Programmable Interrupt Controller
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Limit apic dumping. The parameter defines the maximal
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number of local apics being dumped. Also it is possible
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to set it to "all" by meaning -- no limit here.
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Format: { 1 (default) | 2 | ... | all }.
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The parameter valid if only apic=debug or
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apic=verbose is specified.
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Example: apic=debug show_lapic=all
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apm= [APM] Advanced Power Management
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See header of arch/x86/kernel/apm_32.c.
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arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
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Format: <io>,<irq>,<nodeID>
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ataflop= [HW,M68k]
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atarimouse= [HW,MOUSE] Atari Mouse
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atkbd.extra= [HW] Enable extra LEDs and keys on IBM RapidAccess,
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EzKey and similar keyboards
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atkbd.reset= [HW] Reset keyboard during initialization
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atkbd.set= [HW] Select keyboard code set
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Format: <int> (2 = AT (default), 3 = PS/2)
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atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
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keyboards
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atkbd.softraw= [HW] Choose between synthetic and real raw mode
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Format: <bool> (0 = real, 1 = synthetic (default))
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atkbd.softrepeat= [HW]
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Use software keyboard repeat
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autotest [IA-64]
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baycom_epp= [HW,AX25]
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Format: <io>,<mode>
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baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
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Format: <io>,<mode>
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See header of drivers/net/hamradio/baycom_par.c.
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baycom_ser_fdx= [HW,AX25]
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BayCom Serial Port AX.25 Modem (Full Duplex Mode)
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Format: <io>,<irq>,<mode>[,<baud>]
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See header of drivers/net/hamradio/baycom_ser_fdx.c.
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baycom_ser_hdx= [HW,AX25]
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BayCom Serial Port AX.25 Modem (Half Duplex Mode)
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Format: <io>,<irq>,<mode>
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See header of drivers/net/hamradio/baycom_ser_hdx.c.
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boot_delay= Milliseconds to delay each printk during boot.
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Values larger than 10 seconds (10000) are changed to
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no delay (0).
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Format: integer
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bootmem_debug [KNL] Enable bootmem allocator debug messages.
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bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
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bttv.radio= Most important insmod options are available as
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kernel args too.
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bttv.pll= See Documentation/video4linux/bttv/Insmod-options
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bttv.tuner=
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bulk_remove=off [PPC] This parameter disables the use of the pSeries
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firmware feature for flushing multiple hpte entries
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at a time.
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c101= [NET] Moxa C101 synchronous serial card
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cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
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Sometimes CPU hardware bugs make them report the cache
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size incorrectly. The kernel will attempt work arounds
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to fix known problems, but for some CPUs it is not
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possible to determine what the correct size should be.
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This option provides an override for these situations.
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capability.disable=
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[SECURITY] Disable capabilities. This would normally
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be used only if an alternative security model is to be
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configured. Potentially dangerous and should only be
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used if you are entirely sure of the consequences.
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ccw_timeout_log [S390]
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See Documentation/s390/CommonIO for details.
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cgroup_disable= [KNL] Disable a particular controller
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Format: {name of the controller(s) to disable}
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{Currently supported controllers - "memory"}
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checkreqprot [SELINUX] Set initial checkreqprot flag value.
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Format: { "0" | "1" }
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See security/selinux/Kconfig help text.
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0 -- check protection applied by kernel (includes
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any implied execute protection).
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1 -- check protection requested by application.
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Default value is set via a kernel config option.
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Value can be changed at runtime via
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/selinux/checkreqprot.
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cio_ignore= [S390]
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See Documentation/s390/CommonIO for details.
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clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
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[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.
|
|
|
|
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
|
|
|
|
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.
|
|
|
|
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.
|
|
|
|
dscc4.setup= [NET]
|
|
|
|
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 conroller
|
|
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.
|
|
|
|
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.
|
|
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
|
|
|
|
inttest= [IA-64]
|
|
|
|
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.
|
|
|
|
mcatest= [IA-64]
|
|
|
|
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.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'.
|
|
|
|
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.
|
|
|
|
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 reallocate PCI resources if allocations done by BIOS
|
|
are erroneous.
|
|
|
|
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_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.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.
|
|
|
|
rcupdate.blimit= [KNL,BOOT]
|
|
Set maximum number of finished RCU callbacks to process
|
|
in one batch.
|
|
|
|
rcupdate.qhimark= [KNL,BOOT]
|
|
Set threshold of queued
|
|
RCU callbacks over which batch limiting is disabled.
|
|
|
|
rcupdate.qlowmark= [KNL,BOOT]
|
|
Set threshold of queued RCU callbacks below which
|
|
batch limiting is re-enabled.
|
|
|
|
rdinit= [KNL]
|
|
Format: <full_path>
|
|
Run specified binary instead of /init from the ramdisk,
|
|
used for early userspace startup. See initrd.
|
|
|
|
reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
|
|
Format: <reboot_mode>[,<reboot_mode2>[,...]]
|
|
See arch/*/kernel/reboot.c or arch/*/kernel/process.c
|
|
|
|
relax_domain_level=
|
|
[KNL, SMP] Set scheduler's default relax_domain_level.
|
|
See Documentation/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
|
|
|
|
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.
|
|
|
|
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 mininum page order for slabs. Must be
|
|
lower than slub_max_order.
|
|
For more information see Documentation/vm/slub.txt.
|
|
|
|
slub_nomerge [MM, SLUB]
|
|
Disable merging of slabs with similar size. May be
|
|
necessary if there is some reason to distinguish
|
|
allocs to different slabs. Debug options disable
|
|
merging on their own.
|
|
For more information see Documentation/vm/slub.txt.
|
|
|
|
smart2= [HW]
|
|
Format: <io1>[,<io2>[,...,<io8>]]
|
|
|
|
smp-alt-once [X86-32,SMP] On a hotplug CPU system, only
|
|
attempt to substitute SMP alternatives once at boot.
|
|
|
|
smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices
|
|
smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port
|
|
smsc-ircc2.ircc_sir= [HW] SIR base I/O port
|
|
smsc-ircc2.ircc_fir= [HW] FIR base I/O port
|
|
smsc-ircc2.ircc_irq= [HW] IRQ line
|
|
smsc-ircc2.ircc_dma= [HW] DMA channel
|
|
smsc-ircc2.ircc_transceiver= [HW] Transceiver type:
|
|
0: Toshiba Satellite 1800 (GP data pin select)
|
|
1: Fast pin select (default)
|
|
2: ATC IRMode
|
|
|
|
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.
|
|
|
|
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 explicitely 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
|
|
|
|
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.
|
|
|
|
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.
|