Features/Documentation: Difference between revisions

Revision as of 23:25, 7 November 2016

QEMU's documentation needs some reorganization.

Ultimately there should be five manuals:

QEMU user mode emulation (docs/qemu-user): currently in qemu-doc.texi
QEMU full-system emulation user's guide (docs/qemu-system): the largest part of qemu-doc.texi; also covers qemu-img, qemu-io; parts of docs/
QEMU full-system emulation management guide (docs/qemu-system-mgmt): qmp-commands.txt; docs/specs/vhost-user.txt; probably should include file format specs in docs/specs/
QEMU full-system emulation guest hardware specifications (docs/qemu-system-hw): currently in docs/specs/
QEMU developer's guide (docs/qemu-devel): the rest of docs/; the implementation notes in qemu-doc.texi; tcg/README; doc comments in the source code; automatically generated docs for Python classes in qemu-iotests and scripts/qmp

Choices

Based on experience from the Linux kernel, QEMU's docs pipeline is going to be based on Sphinx. Sphinx is extensible and it is easy to add new input formats and input directives.

Currently, QEMU documentation is written in a mix of Texinfo and text files roughly based on Markdown. Sphinx's native format is reStructuredText (rST). Texinfo input is not supported by Sphinx, but Paolo has a Sphinx (docutils) parser for Docbook; Texinfo is able to convert .texi input files into Docbook.

Currently, QEMU doc comments have never been actually used together with a actual documentation generator in mind, but are roughly based on gtk-doc syntax. We will probably end up keeping a copy of the Linux kernel's kernel-doc script. kernel-doc currently supports rST and Docbook output.

As a first step, we should decide how to evolve this into something more structured.

For text, the two possible choices should ultimately be:

Convert everything to reStructuredText
Advantages: Flexible enough, native format for Sphinx, Linux is using it

Disadvantages: Less "obvious" than Markdown (though a basic conversion seems to be simple enough), looks somewhat weird when you use more advanced features
Convert everything to Texinfo
Advantages: qemu-doc.texi and command-line doc comments are already written in Texinfo, more traditional/"precise" markup

Disadvantages: Most different from basic ASCII text, not supported by kernel-doc

For C doc comments, the three possible choices are:

Use reStructuredText markup
Advantages: Flexible enough, native format for Sphinx, Linux is using it

Disadvantages: Would not want to use rST for doc comments but not for the rest of docs/, or for command-line doc comments
Extend kernel-doc to support Texinfo markup, and convert that to Docbook
Advantages: qemu-doc.texi and command-line doc comments are already written in Texinfo

Disadvantages: More work to do
Use no markup, apart from annotating fields, functions etc. using sigils (e.g. kernel-doc's &struct Foo or GtkDoc's %Foo).
Advantages: Simplest solution, can use any kernel-doc backend (DocBook and rST)

Disadvantages: command-line doc comments are already written in Texinfo

Things to do

For now in no particular order:

Prepare five wiki pages to work collaboratively on the manuals' table of contents
Split qemu-doc.texi so that the bulk of its contents is included from small files in docs/

@@ Line 34: / Line 34: @@
 # Convert everything to reStructuredText
-#:'''Advantages:'''
+#:'''Advantages:''' Flexible enough, native format for Sphinx, Linux is using it
-#:'''Disadvantages:'''
+#:'''Disadvantages:''' Less "obvious" than Markdown (though a basic conversion seems to be simple enough), looks somewhat weird when you use more advanced features
 # Convert everything to Texinfo
-#:'''Advantages:'''
+#:'''Advantages:''' qemu-doc.texi and command-line doc comments are already written in Texinfo, more traditional/"precise" markup
-#:'''Disadvantages:'''
+#:'''Disadvantages:''' Most different from basic ASCII text, not supported by kernel-doc
-For comments, the three possible choices are:
+For C doc comments, the three possible choices are:
 # Use reStructuredText markup
-#:'''Advantages:'''
+#:'''Advantages:''' Flexible enough, native format for Sphinx, Linux is using it
-#:'''Disadvantages:'''
+#:'''Disadvantages:''' Would not want to use rST for doc comments but not for the rest of docs/, or for command-line doc comments
 # Extend kernel-doc to support Texinfo markup, and convert that to Docbook
-#:'''Advantages:'''
+#:'''Advantages:''' qemu-doc.texi and command-line doc comments are already written in Texinfo
-#:'''Disadvantages:'''
+#:'''Disadvantages:''' More work to do
 # Use no markup, apart from annotating fields, functions etc. using sigils (e.g. kernel-doc's <tt>&struct Foo</tt> or GtkDoc's <tt>%Foo</tt>).
-#:'''Advantages:'''
+#:'''Advantages:''' Simplest solution, can use any kernel-doc backend (DocBook and rST)
-#:'''Disadvantages:'''
+#:'''Disadvantages:''' command-line doc comments are already written in Texinfo
 == Things to do ==