diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
index ba8129afab..b35c332c82 100644
--- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
+++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.rst
@@ -1972,6 +1972,24 @@ looking at the source code of the ``bb`` module, which is in
 the commonly used functions ``bb.utils.contains()`` and
 ``bb.utils.mkdirhier()``, which come with docstrings.
 
+Extending Python Library Code
+-----------------------------
+
+If you wish to add your own Python library code (e.g. to provide
+functions/classes you can use from Python functions in the metadata)
+you can do so from any layer using the ``addpylib`` directive.
+This directive is typically added to your layer configuration (
+``conf/layer.conf``) although it will be handled in any ``.conf`` file.
+
+Usage is of the form::
+
+   addpylib <directory> <namespace>
+
+Where <directory> specifies the directory to add to the library path.
+The specified <namespace> is imported automatically, and if the imported
+module specifies an attribute named ``BBIMPORTS``, that list of
+sub-modules is iterated and imported too.
+
 Testing and Debugging BitBake Python code
 -----------------------------------------
 
diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
index 1cf37d5fcd..fc7cb88238 100644
--- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
+++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst
@@ -348,6 +348,14 @@ overview of their function and contents.
 
       For example usage, see :term:`BB_GIT_SHALLOW`.
 
+   :term:`BB_GLOBAL_PYMODULES`
+      Specifies the list of Python modules to place in the global namespace.
+      It is intended that only the core layer should set this and it is meant
+      to be a very small list, typically just ``os`` and ``sys``.
+      :term:`BB_GLOBAL_PYMODULES` is expected to be set before the first
+      ``addpylib`` directive.
+      See also ":ref:`bitbake-user-manual/bitbake-user-manual-metadata:extending python library code`".
+
    :term:`BB_HASHCHECK_FUNCTION`
       Specifies the name of the function to call during the "setscene" part
       of the task's execution in order to validate the list of task hashes.