Vintage kernel-doc mode

Hint

This section exists mainly for historical reasons. The vintage kernel-doc mode is only relevant for those who have to work with old kernel-doc comments (e.g. Kernel’s Source code documentation).

Within the vintage kernel-doc mode the kernel-doc parser ignores any whitespace formatting/markup. Since formatting with whitespace is substantial for ASCII markups, it’s recommended to use the reST kernel-doc mode on any new or changed comment!

Determined by the history of the kernel-doc comments, the vintage kernel-doc comments contain characters like “*” or strings with e.g. leading/trailing underscore (“_”), which are in-line markups in reST. Here a short example from a vintage comment:

<SNIP> -----
* In contrast to the other drm_get_*_name functions this one here returns a
* const pointer and hence is threadsafe.
<SNAP> -----

Within reST markup (the new base format), the wildcard in the string drm_get_*_name has to be masked by the kernel-doc parser: drm_get_\\*_name. Some more examples from reST markup:

  • Emphasis “*”: like *emphasis* or **emphasis strong**
  • Leading “_” : is a anchor in reST markup (_foo).
  • Trailing “_: is a reference in reST markup (foo_).
  • interpreted text: “`”
  • in-line literals: “``”
  • substitution references: “|”

As long as the kernel-doc parser runs in the vintage kernel-doc mode, these special strings will be masked in the reST output and can’t be used as plain-text markup.

Hint

The kernel source contains tens of thousands of vintage kernel-doc comments, applications which has to work with them must be able to distinguish between vintage and the new reST markup.

To force the parser to switch into the reST mode add the following comment (e.g.) at the top of your source code file (or at any line where reST content starts).:

/* parse-markup: reST */ *

In reST mode the kernel-doc parser pass through all text unchanged to the reST tool-chain including any whitespace and reST markup. To toggle back to Vintage kernel-doc mode type the following line:

/* parse-markup: kernel-doc */

vintage mode quirks

In the following, you will find some quirks of the vintage kernel-doc mode.

  • Since a colon introduce a new section, you can’t use colons. E.g. a comment line like:

    prints out: hello world
    

    will result in a section with the title “prints out” and a paragraph with only “hello world” in, this is mostly not what you expect. To avoid sectioning, place a space in front of the column:

    prints out : hello world
    
  • The multi-line descriptive text you provide does not recognize line breaks, so if you try to format some text nicely, as in:

    Return:
       0 - cool
       1 - invalid arg
       2 - out of memory
    

    this will all run together and produce:

    Return: 0 - cool 1 - invalid arg 2 - out of memory
    
  • If the descriptive text you provide has lines that begin with some phrase followed by a colon, each of those phrases will be taken as a new section heading, which means you should similarly try to avoid text like:

    Return:
      0: cool
      1: invalid arg
      2: out of memory
    

    every line of which would start a new section. Again, probably not what you were after.