QEMU Documentation
QEMU’s documentation is written in reStructuredText format and built using the Sphinx documentation generator. We generate both the HTML manual and the manpages from the some documentation sources.
hxtool and .hx files
The documentation for QEMU command line options and Human Monitor Protocol
(HMP) commands is written in files with the .hx
suffix. These
are processed in two ways:
scripts/hxtool
creates C header files from them, which are included in QEMU to do things like handle the--help
option outputa Sphinx extension in
docs/sphinx/hxtool.py
generates rST output to be included in the HTML or manpage documentation
The syntax of these .hx
files is simple. It is broadly an
alternation of C code put into the C output and rST format text
put into the documentation. A few special directives are recognised;
these are all-caps and must be at the beginning of the line.
HXCOMM
is the comment marker. The line, including any arbitrary
text after the marker, is discarded and appears neither in the C output
nor the documentation output.
SRST
starts a reStructuredText section. Following lines
are put into the documentation verbatim, and discarded from the C output.
The alternative form SRST()
is used to define a label which can be
referenced from elsewhere in the rST documentation. The label will take
the form <DOCNAME-HXFILE-LABEL>
, where DOCNAME
is the name of the
top level rST file, HXFILE
is the filename of the .hx file without
the .hx
extension, and LABEL
is the text provided within the
SRST()
directive. For example,
<system/invocation-qemu-options-initrd>
.
ERST
ends the documentation section started with SRST
,
and switches back to a C code section.
DEFHEADING()
defines a heading that should appear in both the
--help
output and in the documentation. This directive should
be in the C code block. If there is a string inside the brackets,
this is the heading to use. If this string is empty, it produces
a blank line in the --help
output and is ignored for the rST
output.
ARCHHEADING()
is a variant of DEFHEADING()
which produces
the heading only if the specified guest architecture was compiled
into QEMU. This should be avoided in new documentation.
Within C code sections, you should check the comments at the top
of the file to see what the expected usage is, because this
varies between files. For instance in qemu-options.hx
we use
the DEF()
macro to define each option and specify its --help
text, but in hmp-commands.hx
the C code sections are elements
of an array of structs of type HMPCommand
which define the
name, behaviour and help text for each monitor command.
In the file qemu-options.hx
, do not try to explicitly define a
reStructuredText label within a documentation section. This file
is included into two separate Sphinx documents, and some
versions of Sphinx will complain about the duplicate label
that results. Use the SRST()
directive documented above, to
emit an unambiguous label.