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Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.rst')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.rst | 41 |
1 files changed, 24 insertions, 17 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst index e8bdf5e86a9b..39d0e7ff0965 100644 --- a/Documentation/admin-guide/kernel-parameters.rst +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -27,6 +27,16 @@ kernel command line (/proc/cmdline) and collects module parameters when it loads a module, so the kernel command line can be used for loadable modules too. +This document may not be entirely up to date and comprehensive. The command +"modinfo -p ${modulename}" shows a current list of all parameters of a loadable +module. Loadable modules, after being loaded into the running kernel, also +reveal their parameters in /sys/module/${modulename}/parameters/. Some of these +parameters may be changed at runtime by the command +``echo -n ${value} > /sys/module/${modulename}/parameters/${parm}``. + +Special handling +---------------- + Hyphens (dashes) and underscores are equivalent in parameter names, so:: log_buf_len=1M print-fatal-signals=1 @@ -39,8 +49,8 @@ Double-quotes can be used to protect spaces in values, e.g.:: param="spaces in here" -cpu lists: ----------- +cpu lists +~~~~~~~~~ Some kernel parameters take a list of CPUs as a value, e.g. isolcpus, nohz_full, irqaffinity, rcu_nocbs. The format of this list is: @@ -82,12 +92,17 @@ so that "nohz_full=all" is the equivalent of "nohz_full=0-N". The semantics of "N" and "all" is supported on a level of bitmaps and holds for all users of bitmap_parselist(). -This document may not be entirely up to date and comprehensive. The command -"modinfo -p ${modulename}" shows a current list of all parameters of a loadable -module. Loadable modules, after being loaded into the running kernel, also -reveal their parameters in /sys/module/${modulename}/parameters/. Some of these -parameters may be changed at runtime by the command -``echo -n ${value} > /sys/module/${modulename}/parameters/${parm}``. +Metric suffixes +~~~~~~~~~~~~~~~ + +The [KMG] suffix is commonly described after a number of kernel +parameter values. 'K', 'M', 'G', 'T', 'P', and 'E' suffixes are allowed. +These letters represent the _binary_ multipliers 'Kilo', 'Mega', 'Giga', +'Tera', 'Peta', and 'Exa', equaling 2^10, 2^20, 2^30, 2^40, 2^50, and +2^60 bytes respectively. Such letter suffixes can also be entirely omitted. + +Kernel Build Options +-------------------- The parameters listed below are only valid if certain kernel build options were enabled and if respective hardware is present. This list should be kept @@ -118,7 +133,6 @@ is applicable:: HIBERNATION HIBERNATION is enabled. HW Appropriate hardware is enabled. HYPER_V HYPERV support is enabled. - IA-64 IA-64 architecture is enabled. IMA Integrity measurement architecture is enabled. IP_PNP IP DHCP, BOOTP, or RARP is enabled. IPV6 IPv6 support is enabled. @@ -160,6 +174,7 @@ is applicable:: SCSI Appropriate SCSI support is enabled. A lot of drivers have their options described inside the Documentation/scsi/ sub-directory. + SDW SoundWire support is enabled. SECURITY Different security models are enabled. SELINUX SELinux support is enabled. SERIAL Serial support is enabled. @@ -179,8 +194,6 @@ is applicable:: WDT Watchdog support is enabled. X86-32 X86-32, aka i386 architecture is enabled. X86-64 X86-64 architecture is enabled. - More X86-64 boot options can be found in - Documentation/arch/x86/x86_64/boot-options.rst. X86 Either 32-bit or 64-bit x86 (same as X86-32+X86-64) X86_UV SGI UV support is enabled. XEN Xen support is enabled @@ -198,7 +211,6 @@ Do not modify the syntax of boot loader parameters without extreme need or coordination with <Documentation/arch/x86/boot.rst>. There are also arch-specific kernel-parameters not documented here. -See for example <Documentation/arch/x86/x86_64/boot-options.rst>. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that a trailing = on the name of any parameter states that that parameter will @@ -212,10 +224,5 @@ a fixed number of characters. This limit depends on the architecture and is between 256 and 4096 characters. It is defined in the file ./include/uapi/asm-generic/setup.h as COMMAND_LINE_SIZE. -Finally, the [KMG] suffix is commonly described after a number of kernel -parameter values. These 'K', 'M', and 'G' letters represent the _binary_ -multipliers 'Kilo', 'Mega', and 'Giga', equaling 2^10, 2^20, and 2^30 -bytes respectively. Such letter suffixes can also be entirely omitted: - .. include:: kernel-parameters.txt :literal: |