path: root/Documentation/kernel-doc-nano-HOWTO.txt
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authorLinus Torvalds <>2005-04-16 15:20:36 -0700
committerLinus Torvalds <>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/kernel-doc-nano-HOWTO.txt
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+kernel-doc nano-HOWTO
+Many places in the source tree have extractable documentation in the
+form of block comments above functions. The components of this system
+- scripts/kernel-doc
+ This is a perl script that hunts for the block comments and can mark
+ them up directly into DocBook, man, text, and HTML. (No, not
+ texinfo.)
+- Documentation/DocBook/*.tmpl
+ These are SGML template files, which are normal SGML files with
+ special place-holders for where the extracted documentation should
+ go.
+- scripts/docproc.c
+ This is a program for converting SGML template files into SGML
+ files. When a file is referenced it is searched for symbols
+ exported (EXPORT_SYMBOL), to be able to distinguish between internal
+ and external functions.
+ It invokes kernel-doc, giving it the list of functions that
+ are to be documented.
+ Additionally it is used to scan the SGML template files to locate
+ all the files referenced herein. This is used to generate dependency
+ information as used by make.
+- Makefile
+ The targets 'sgmldocs', 'psdocs', 'pdfdocs', and 'htmldocs' are used
+ to build DocBook files, PostScript files, PDF files, and html files
+ in Documentation/DocBook.
+- Documentation/DocBook/Makefile
+ This is where C files are associated with SGML templates.
+How to extract the documentation
+If you just want to read the ready-made books on the various
+subsystems (see Documentation/DocBook/*.tmpl), just type 'make
+psdocs', or 'make pdfdocs', or 'make htmldocs', depending on your
+preference. If you would rather read a different format, you can type
+'make sgmldocs' and then use DocBook tools to convert
+Documentation/DocBook/*.sgml to a format of your choice (for example,
+'db2html ...' if 'make htmldocs' was not defined).
+If you want to see man pages instead, you can do this:
+$ cd linux
+$ scripts/kernel-doc -man $(find -name '*.c') | /tmp/man
+$ scripts/kernel-doc -man $(find -name '*.h') | /tmp/man
+Here is
+if ($#ARGV < 0) {
+ die "where do I put the results?\n";
+mkdir $ARGV[0],0777;
+$state = 0;
+while (<STDIN>) {
+ if (/^\.TH \"[^\"]*\" 4 \"([^\"]*)\"/) {
+ if ($state == 1) { close OUT }
+ $state = 1;
+ $fn = "$ARGV[0]/$1.4";
+ print STDERR "Creating $fn\n";
+ open OUT, ">$fn" or die "can't open $fn: $!\n";
+ print OUT $_;
+ } elsif ($state != 0) {
+ print OUT $_;
+ }
+close OUT;
+If you just want to view the documentation for one function in one
+file, you can do this:
+$ scripts/kernel-doc -man -function fn file | nroff -man | less
+or this:
+$ scripts/kernel-doc -text -function fn file
+How to add extractable documentation to your source files
+The format of the block comment is like this:
+ * function_name(:)? (- short description)?
+(* @parameterx: (description of parameter x)?)*
+(* a blank line)?
+ * (Description:)? (Description of function)?
+ * (section header: (section description)? )*
+The short function description cannot be multiline, but the other
+descriptions can be (and they can contain blank lines). Avoid putting a
+spurious blank line after the function name, or else the description will
+be repeated!
+All descriptive text is further processed, scanning for the following special
+patterns, which are highlighted appropriately.
+'funcname()' - function
+'$ENVVAR' - environment variable
+'&struct_name' - name of a structure (up to two words including 'struct')
+'@parameter' - name of a parameter
+'%CONST' - name of a constant.
+Take a look around the source tree for examples.
+How to make new SGML template files
+SGML template files (*.tmpl) are like normal SGML files, except that
+they can contain escape sequences where extracted documentation should
+be inserted.
+!E<filename> is replaced by the documentation, in <filename>, for
+functions that are exported using EXPORT_SYMBOL: the function list is
+collected from files listed in Documentation/DocBook/Makefile.
+!I<filename> is replaced by the documentation for functions that are
+_not_ exported using EXPORT_SYMBOL.
+!D<filename> is used to name additional files to search for functions
+exported using EXPORT_SYMBOL.
+!F<filename> <function [functions...]> is replaced by the
+documentation, in <filename>, for the functions listed.
+*/ <>