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1kernel-doc nano-HOWTO
2=====================
3
4Many places in the source tree have extractable documentation in the
5form of block comments above functions. The components of this system
6are:
7
8- scripts/kernel-doc
9
10 This is a perl script that hunts for the block comments and can mark
11 them up directly into DocBook, man, text, and HTML. (No, not
12 texinfo.)
13
14- Documentation/DocBook/*.tmpl
15
16 These are SGML template files, which are normal SGML files with
17 special place-holders for where the extracted documentation should
18 go.
19
20- scripts/docproc.c
21
22 This is a program for converting SGML template files into SGML
23 files. When a file is referenced it is searched for symbols
24 exported (EXPORT_SYMBOL), to be able to distinguish between internal
25 and external functions.
26 It invokes kernel-doc, giving it the list of functions that
27 are to be documented.
28 Additionally it is used to scan the SGML template files to locate
29 all the files referenced herein. This is used to generate dependency
30 information as used by make.
31
32- Makefile
33
34 The targets 'sgmldocs', 'psdocs', 'pdfdocs', and 'htmldocs' are used
35 to build DocBook files, PostScript files, PDF files, and html files
36 in Documentation/DocBook.
37
38- Documentation/DocBook/Makefile
39
40 This is where C files are associated with SGML templates.
41
42
43How to extract the documentation
44--------------------------------
45
46If you just want to read the ready-made books on the various
47subsystems (see Documentation/DocBook/*.tmpl), just type 'make
48psdocs', or 'make pdfdocs', or 'make htmldocs', depending on your
49preference. If you would rather read a different format, you can type
50'make sgmldocs' and then use DocBook tools to convert
51Documentation/DocBook/*.sgml to a format of your choice (for example,
52'db2html ...' if 'make htmldocs' was not defined).
53
54If you want to see man pages instead, you can do this:
55
56$ cd linux
57$ scripts/kernel-doc -man $(find -name '*.c') | split-man.pl /tmp/man
58$ scripts/kernel-doc -man $(find -name '*.h') | split-man.pl /tmp/man
59
60Here is split-man.pl:
61
62-->
63#!/usr/bin/perl
64
65if ($#ARGV < 0) {
66 die "where do I put the results?\n";
67}
68
69mkdir $ARGV[0],0777;
70$state = 0;
71while (<STDIN>) {
72 if (/^\.TH \"[^\"]*\" 4 \"([^\"]*)\"/) {
73 if ($state == 1) { close OUT }
74 $state = 1;
75 $fn = "$ARGV[0]/$1.4";
76 print STDERR "Creating $fn\n";
77 open OUT, ">$fn" or die "can't open $fn: $!\n";
78 print OUT $_;
79 } elsif ($state != 0) {
80 print OUT $_;
81 }
82}
83
84close OUT;
85<--
86
87If you just want to view the documentation for one function in one
88file, you can do this:
89
90$ scripts/kernel-doc -man -function fn file | nroff -man | less
91
92or this:
93
94$ scripts/kernel-doc -text -function fn file
95
96
97How to add extractable documentation to your source files
98---------------------------------------------------------
99
100The format of the block comment is like this:
101
102/**
103 * function_name(:)? (- short description)?
104(* @parameterx: (description of parameter x)?)*
105(* a blank line)?
106 * (Description:)? (Description of function)?
107 * (section header: (section description)? )*
108(*)?*/
109
110The short function description cannot be multiline, but the other
111descriptions can be (and they can contain blank lines). Avoid putting a
112spurious blank line after the function name, or else the description will
113be repeated!
114
115All descriptive text is further processed, scanning for the following special
116patterns, which are highlighted appropriately.
117
118'funcname()' - function
119'$ENVVAR' - environment variable
120'&struct_name' - name of a structure (up to two words including 'struct')
121'@parameter' - name of a parameter
122'%CONST' - name of a constant.
123
124Take a look around the source tree for examples.
125
126
127How to make new SGML template files
128-----------------------------------
129
130SGML template files (*.tmpl) are like normal SGML files, except that
131they can contain escape sequences where extracted documentation should
132be inserted.
133
134!E<filename> is replaced by the documentation, in <filename>, for
135functions that are exported using EXPORT_SYMBOL: the function list is
136collected from files listed in Documentation/DocBook/Makefile.
137
138!I<filename> is replaced by the documentation for functions that are
139_not_ exported using EXPORT_SYMBOL.
140
141!D<filename> is used to name additional files to search for functions
142exported using EXPORT_SYMBOL.
143
144!F<filename> <function [functions...]> is replaced by the
145documentation, in <filename>, for the functions listed.
146
147
148Tim.
149*/ <twaugh@redhat.com>
150