Based on kernel version 2.6.25. Page generated on 2008-04-18 21:22 EST.
1 kernel-doc nano-HOWTO 2 ===================== 3 4 Many places in the source tree have extractable documentation in the 5 form of block comments above functions. The components of this system 6 are: 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/basic/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 43 How to extract the documentation 44 -------------------------------- 45 46 If you just want to read the ready-made books on the various 47 subsystems (see Documentation/DocBook/*.tmpl), just type 'make 48 psdocs', or 'make pdfdocs', or 'make htmldocs', depending on your 49 preference. If you would rather read a different format, you can type 50 'make sgmldocs' and then use DocBook tools to convert 51 Documentation/DocBook/*.sgml to a format of your choice (for example, 52 'db2html ...' if 'make htmldocs' was not defined). 53 54 If 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 $(find -name '*.h') | split-man.pl /tmp/man 59 60 Here is split-man.pl: 61 62 --> 63 #!/usr/bin/perl 64 65 if ($#ARGV < 0) { 66 die "where do I put the results?\n"; 67 } 68 69 mkdir $ARGV[0],0777; 70 $state = 0; 71 while (<STDIN>) { 72 if (/^\.TH \"[^\"]*\" 4 \"([^\"]*)\"/) { 73 if ($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 84 close OUT; 85 <-- 86 87 If you just want to view the documentation for one function in one 88 file, you can do this: 89 90 $ scripts/kernel-doc -man -function fn file | nroff -man | less 91 92 or this: 93 94 $ scripts/kernel-doc -text -function fn file 95 96 97 How to add extractable documentation to your source files 98 --------------------------------------------------------- 99 100 The format of the block comment is like this: 101 102 /** 103 * function_name(:)? (- short description)? 104 (* @parameterx(space)*: (description of parameter x)?)* 105 (* a blank line)? 106 * (Description:)? (Description of function)? 107 * (section header: (section description)? )* 108 (*)?*/ 109 110 The short function description ***cannot be multiline***, but the other 111 descriptions can be (and they can contain blank lines). If you continue 112 that initial short description onto a second line, that second line will 113 appear further down at the beginning of the description section, which is 114 almost certainly not what you had in mind. 115 116 Avoid putting a spurious blank line after the function name, or else the 117 description will be repeated! 118 119 All descriptive text is further processed, scanning for the following special 120 patterns, which are highlighted appropriately. 121 122 'funcname()' - function 123 '$ENVVAR' - environment variable 124 '&struct_name' - name of a structure (up to two words including 'struct') 125 '@parameter' - name of a parameter 126 '%CONST' - name of a constant. 127 128 NOTE 1: The multi-line descriptive text you provide does *not* recognize 129 line breaks, so if you try to format some text nicely, as in: 130 131 Return codes 132 0 - cool 133 1 - invalid arg 134 2 - out of memory 135 136 this will all run together and produce: 137 138 Return codes 0 - cool 1 - invalid arg 2 - out of memory 139 140 NOTE 2: If the descriptive text you provide has lines that begin with 141 some phrase followed by a colon, each of those phrases will be taken as 142 a new section heading, which means you should similarly try to avoid text 143 like: 144 145 Return codes: 146 0: cool 147 1: invalid arg 148 2: out of memory 149 150 every line of which would start a new section. Again, probably not 151 what you were after. 152 153 Take a look around the source tree for examples. 154 155 156 kernel-doc for structs, unions, enums, and typedefs 157 --------------------------------------------------- 158 159 Beside functions you can also write documentation for structs, unions, 160 enums and typedefs. Instead of the function name you must write the name 161 of the declaration; the struct/union/enum/typedef must always precede 162 the name. Nesting of declarations is not supported. 163 Use the argument mechanism to document members or constants. 164 165 Inside a struct description, you can use the "private:" and "public:" 166 comment tags. Structure fields that are inside a "private:" area 167 are not listed in the generated output documentation. 168 169 Example: 170 171 /** 172 * struct my_struct - short description 173 * @a: first member 174 * @b: second member 175 * 176 * Longer description 177 */ 178 struct my_struct { 179 int a; 180 int b; 181 /* private: */ 182 int c; 183 }; 184 185 186 How to make new SGML template files 187 ----------------------------------- 188 189 SGML template files (*.tmpl) are like normal SGML files, except that 190 they can contain escape sequences where extracted documentation should 191 be inserted. 192 193 !E<filename> is replaced by the documentation, in <filename>, for 194 functions that are exported using EXPORT_SYMBOL: the function list is 195 collected from files listed in Documentation/DocBook/Makefile. 196 197 !I<filename> is replaced by the documentation for functions that are 198 _not_ exported using EXPORT_SYMBOL. 199 200 !D<filename> is used to name additional files to search for functions 201 exported using EXPORT_SYMBOL. 202 203 !F<filename> <function [functions...]> is replaced by the 204 documentation, in <filename>, for the functions listed. 205 206 207 Tim. 208 */ <twaugh[AT]redhat[DOT]com>
