README.rst
1QEMU Python Tooling
2===================
3
4This directory houses Python tooling used by the QEMU project to build,
5configure, and test QEMU. It is organized by namespace (``qemu``), and
6then by package (e.g. ``qemu/machine``, ``qemu/qmp``, etc).
7
8``setup.py`` is used by ``pip`` to install this tooling to the current
9environment. ``setup.cfg`` provides the packaging configuration used by
10``setup.py``. You will generally invoke it by doing one of the following:
11
121. ``pip3 install .`` will install these packages to your current
13 environment. If you are inside a virtual environment, they will
14 install there. If you are not, it will attempt to install to the
15 global environment, which is **not recommended**.
16
172. ``pip3 install --user .`` will install these packages to your user's
18 local python packages. If you are inside of a virtual environment,
19 this will fail; you want the first invocation above.
20
21If you append the ``--editable`` or ``-e`` argument to either invocation
22above, pip will install in "editable" mode. This installs the package as
23a forwarder ("qemu.egg-link") that points to the source tree. In so
24doing, the installed package always reflects the latest version in your
25source tree.
26
27Installing ".[devel]" instead of "." will additionally pull in required
28packages for testing this package. They are not runtime requirements,
29and are not needed to simply use these libraries.
30
31Running ``make develop`` will pull in all testing dependencies and
32install QEMU in editable mode to the current environment.
33(It is a shortcut for ``pip3 install -e .[devel]``.)
34
35See `Installing packages using pip and virtual environments
36<https://packaging.python.org/guides/installing-using-pip-and-virtual-environments/>`_
37for more information.
38
39
40Using these packages without installing them
41--------------------------------------------
42
43These packages may be used without installing them first, by using one
44of two tricks:
45
461. Set your PYTHONPATH environment variable to include this source
47 directory, e.g. ``~/src/qemu/python``. See
48 https://docs.python.org/3/using/cmdline.html#envvar-PYTHONPATH
49
502. Inside a Python script, use ``sys.path`` to forcibly include a search
51 path prior to importing the ``qemu`` namespace. See
52 https://docs.python.org/3/library/sys.html#sys.path
53
54A strong downside to both approaches is that they generally interfere
55with static analysis tools being able to locate and analyze the code
56being imported.
57
58Package installation also normally provides executable console scripts,
59so that tools like ``qmp-shell`` are always available via $PATH. To
60invoke them without installation, you can invoke e.g.:
61
62``> PYTHONPATH=~/src/qemu/python python3 -m qemu.qmp.qmp_shell``
63
64The mappings between console script name and python module path can be
65found in ``setup.cfg``.
66
67
68Files in this directory
69-----------------------
70
71- ``qemu/`` Python 'qemu' namespace package source directory.
72- ``tests/`` Python package tests directory.
73- ``avocado.cfg`` Configuration for the Avocado test-runner.
74 Used by ``make check`` et al.
75- ``Makefile`` provides some common testing/installation invocations.
76 Try ``make help`` to see available targets.
77- ``MANIFEST.in`` is read by python setuptools, it specifies additional files
78 that should be included by a source distribution.
79- ``PACKAGE.rst`` is used as the README file that is visible on PyPI.org.
80- ``README.rst`` you are here!
81- ``VERSION`` contains the PEP-440 compliant version used to describe
82 this package; it is referenced by ``setup.cfg``.
83- ``setup.cfg`` houses setuptools package configuration.
84- ``setup.py`` is the setuptools installer used by pip; See above.
85