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diff --git a/Documentation/kernel-doc-nano-HOWTO.txt b/Documentation/kernel-doc-nano-HOWTO.txt index 2075c0658bf5..0bd32748a467 100644 --- a/Documentation/kernel-doc-nano-HOWTO.txt +++ b/Documentation/kernel-doc-nano-HOWTO.txt @@ -1,6 +1,105 @@ kernel-doc nano-HOWTO ===================== +How to format kernel-doc comments +--------------------------------- + +In order to provide embedded, 'C' friendly, easy to maintain, +but consistent and extractable documentation of the functions and +data structures in the Linux kernel, the Linux kernel has adopted +a consistent style for documenting functions and their parameters, +and structures and their members. + +The format for this documentation is called the kernel-doc format. +It is documented in this Documentation/kernel-doc-nano-HOWTO.txt file. + +This style embeds the documentation within the source files, using +a few simple conventions. The scripts/kernel-doc perl script, some +SGML templates in Documentation/DocBook, and other tools understand +these conventions, and are used to extract this embedded documentation +into various documents. + +In order to provide good documentation of kernel functions and data +structures, please use the following conventions to format your +kernel-doc comments in Linux kernel source. + +We definitely need kernel-doc formatted documentation for functions +that are exported to loadable modules using EXPORT_SYMBOL. + +We also look to provide kernel-doc formatted documentation for +functions externally visible to other kernel files (not marked +"static"). + +We also recommend providing kernel-doc formatted documentation +for private (file "static") routines, for consistency of kernel +source code layout. But this is lower priority and at the +discretion of the MAINTAINER of that kernel source file. + +Data structures visible in kernel include files should also be +documented using kernel-doc formatted comments. + +The opening comment mark "/**" is reserved for kernel-doc comments. +Only comments so marked will be considered by the kernel-doc scripts, +and any comment so marked must be in kernel-doc format. Do not use +"/**" to be begin a comment block unless the comment block contains +kernel-doc formatted comments. The closing comment marker for +kernel-doc comments can be either "*/" or "**/". + +Kernel-doc comments should be placed just before the function +or data structure being described. + +Example kernel-doc function comment: + +/** + * foobar() - short function description of foobar + * @arg1: Describe the first argument to foobar. + * @arg2: Describe the second argument to foobar. + * One can provide multiple line descriptions + * for arguments. + * + * A longer description, with more discussion of the function foobar() + * that might be useful to those using or modifying it. Begins with + * empty comment line, and may include additional embedded empty + * comment lines. + * + * The longer description can have multiple paragraphs. + **/ + +The first line, with the short description, must be on a single line. + +The @argument descriptions must begin on the very next line following +this opening short function description line, with no intervening +empty comment lines. + +Example kernel-doc data structure comment. + +/** + * struct blah - the basic blah structure + * @mem1: describe the first member of struct blah + * @mem2: describe the second member of struct blah, + * perhaps with more lines and words. + * + * Longer description of this structure. + **/ + +The kernel-doc function comments describe each parameter to the +function, in order, with the @name lines. + +The kernel-doc data structure comments describe each structure member +in the data structure, with the @name lines. + +The longer description formatting is "reflowed", losing your line +breaks. So presenting carefully formatted lists within these +descriptions won't work so well; derived documentation will lose +the formatting. + +See the section below "How to add extractable documentation to your +source files" for more details and notes on how to format kernel-doc +comments. + +Components of the kernel-doc system +----------------------------------- + Many places in the source tree have extractable documentation in the form of block comments above functions. The components of this system are: |