ref-manual: add mention of DISTUTILS_SETUP_PATH

Add a variable glossary entry and corresponding 3.3 migration
section entry for DISTUTILS_SETUP_PATH.

(From yocto-docs rev: 0823237e6f4b9dbdf48500b3c1e8cc61696fa2d2)

Signed-off-by: Paul Eggleton <paul.eggleton@microsoft.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 42 insertions, 0 deletions

diff --git a/documentation/ref-manual/migration-3.3.rst b/documentation/ref-manual/migration-3.3.rst
index db1619e627..4fb51a39dc 100644
--- a/documentation/ref-manual/migration-3.3.rst
+++ b/documentation/ref-manual/migration-3.3.rst
@@ -74,6 +74,35 @@ Some example recipes where this change has been made: ``gpgme``, ``libcap-ng``,
 ``python3-pycairo``.
 
 
+.. _migration-3.3-distutils-path:
+
+``setup.py`` path for python modules
+------------------------------------
+
+In a Python module, sometimes ``setup.py`` can be buried deep in the
+source tree. Previously this was handled in recipes by setting :term:`S` to
+point to the subdirectory within the source where ``setup.py`` is located.
+However with the recent :ref:`pseudo <overview-manual/concepts:fakeroot and pseudo>`
+changes, some Python modules make changes to files beneath ``${S}``, for
+example::
+
+   S = "${WORKDIR}/git/python/pythonmodule"
+
+then in ``setup.py`` it works with source code in a relative fashion, such
+as ``../../src``. This causes pseudo to abort as it isn't able to track
+the paths properly. This release introduces a new :term:`DISTUTILS_SETUP_PATH`
+variable so that recipes can specify it explicitly, for example::
+
+   S = "${WORKDIR}/git"
+   DISTUTILS_SETUP_PATH = "${S}/python/pythonmodule"
+
+Recipes that inherit from :ref:`distutils3 <ref-classes-distutils3>` (or
+:ref:`setuptools3 <ref-classes-setuptools3>` which itself inherits
+:ref:`distutils3 <ref-classes-distutils3>`) that also set :term:`S` to
+point to a Python module within a subdirectory in the aforementioned
+manner should be changed to set :term:`DISTUTILS_SETUP_PATH` instead.
+
+
 .. _migration-3.3-bitbake:
 
 BitBake changes
diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 8f059650d3..74ac12bf98 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -1978,6 +1978,19 @@ system and gives an overview of their function and contents.
       is included in the default value of
       :term:`OVERRIDES`.
 
+   :term:`DISTUTILS_SETUP_PATH`
+      When used by recipes that inherit the
+      :ref:`distutils3 <ref-classes-distutils3>` or
+      :ref:`setuptools3 <ref-classes-setuptools3>` class, this variable should
+      be used to specify the directory in which the ``setup.py`` file is
+      located if it is not at the root of the source tree (as specified by
+      :term:`S`). For example, in a recipe where the sources are fetched from
+      a Git repository and ``setup.py`` is in a ``python/pythonmodule``
+      subdirectory, you would have this::
+
+         S = "${WORKDIR}/git"
+         DISTUTILS_SETUP_PATH = "${S}/python/pythonmodule"
+
    :term:`DL_DIR`
       The central download directory used by the build process to store
       downloads. By default, ``DL_DIR`` gets files suitable for mirroring