diff options
author | Randy Dunlap <rdunlap@infradead.org> | 2024-10-29 11:03:20 -0700 |
---|---|---|
committer | Jonathan Corbet <corbet@lwn.net> | 2024-11-04 11:03:24 -0700 |
commit | 32643e10dfdda489b322348465cd7b1b93ff10f3 (patch) | |
tree | 92d6c31e96deb7eb7db4e573a19dab673545af14 /Documentation | |
parent | 062d98be0e3f6dcf08e40a1101e967b2eb4fb92f (diff) |
Documentation: admin: reorganize kernel-parameters intro
Reorganize the introduction to the kernel-parameters file to place
related paragraphs together:
- move module info together and near the beginning
- add a Special Handling section for dashes, underscores, double quotes,
cpu lists, and metric (KMG) suffixes. Expand the KMG suffixes to
include TPE as well.
- add a Kernel Build Options section
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20241029180320.412629-1-rdunlap@infradead.org
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/admin-guide/kernel-parameters.rst | 36 |
1 files changed, 23 insertions, 13 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst index fdea7c26ef80..6247bbc9547c 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 @@ -211,10 +226,5 @@ 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: |