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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

authored by

Randy Dunlap and committed by
Jonathan Corbet 32643e10 062d98be

+23 -13
+23 -13
Documentation/admin-guide/kernel-parameters.rst
··· 27 27 when it loads a module, so the kernel command line can be used for 28 28 loadable modules too. 29 29 30 + This document may not be entirely up to date and comprehensive. The command 31 + "modinfo -p ${modulename}" shows a current list of all parameters of a loadable 32 + module. Loadable modules, after being loaded into the running kernel, also 33 + reveal their parameters in /sys/module/${modulename}/parameters/. Some of these 34 + parameters may be changed at runtime by the command 35 + ``echo -n ${value} > /sys/module/${modulename}/parameters/${parm}``. 36 + 37 + Special handling 38 + ---------------- 39 + 30 40 Hyphens (dashes) and underscores are equivalent in parameter names, so:: 31 41 32 42 log_buf_len=1M print-fatal-signals=1 ··· 49 39 50 40 param="spaces in here" 51 41 52 - cpu lists: 53 - ---------- 42 + cpu lists 43 + ~~~~~~~~~ 54 44 55 45 Some kernel parameters take a list of CPUs as a value, e.g. isolcpus, 56 46 nohz_full, irqaffinity, rcu_nocbs. The format of this list is: ··· 92 82 The semantics of "N" and "all" is supported on a level of bitmaps and holds for 93 83 all users of bitmap_parselist(). 94 84 95 - This document may not be entirely up to date and comprehensive. The command 96 - "modinfo -p ${modulename}" shows a current list of all parameters of a loadable 97 - module. Loadable modules, after being loaded into the running kernel, also 98 - reveal their parameters in /sys/module/${modulename}/parameters/. Some of these 99 - parameters may be changed at runtime by the command 100 - ``echo -n ${value} > /sys/module/${modulename}/parameters/${parm}``. 85 + Metric suffixes 86 + ~~~~~~~~~~~~~~~ 87 + 88 + The [KMG] suffix is commonly described after a number of kernel 89 + parameter values. 'K', 'M', 'G', 'T', 'P', and 'E' suffixes are allowed. 90 + These letters represent the _binary_ multipliers 'Kilo', 'Mega', 'Giga', 91 + 'Tera', 'Peta', and 'Exa', equaling 2^10, 2^20, 2^30, 2^40, 2^50, and 92 + 2^60 bytes respectively. Such letter suffixes can also be entirely omitted. 93 + 94 + Kernel Build Options 95 + -------------------- 101 96 102 97 The parameters listed below are only valid if certain kernel build options 103 98 were enabled and if respective hardware is present. This list should be kept ··· 225 210 a fixed number of characters. This limit depends on the architecture 226 211 and is between 256 and 4096 characters. It is defined in the file 227 212 ./include/uapi/asm-generic/setup.h as COMMAND_LINE_SIZE. 228 - 229 - Finally, the [KMG] suffix is commonly described after a number of kernel 230 - parameter values. These 'K', 'M', and 'G' letters represent the _binary_ 231 - multipliers 'Kilo', 'Mega', and 'Giga', equaling 2^10, 2^20, and 2^30 232 - bytes respectively. Such letter suffixes can also be entirely omitted: 233 213 234 214 .. include:: kernel-parameters.txt 235 215 :literal: