[PATCH 3/8] Documentation: KUnit: restore note about mrproper in start.rst

Tales Aparecida
2022-08-19T05:33:03Z

The "Getting Started" guide should be beginner-friendly, therefore
add a note about the requirement of a clean source tree when running
kunit_tool for the first time, and its related error.

Signed-off-by: Tales Aparecida <tales.aparecida@gmail.com>
---
Documentation/dev-tools/kunit/start.rst | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/Documentation/dev-tools/kunit/start.rst b/Documentation/dev-tools/kunit/start.rst
index 165d7964aa13..e4b73adde6d0 100644
--- a/Documentation/dev-tools/kunit/start.rst
+++ b/Documentation/dev-tools/kunit/start.rst
@@ -19,6 +19,22 @@ can run kunit_tool:

./tools/testing/kunit/kunit.py run

+.. note ::
+ You might see the error:
+ "The source tree is not clean, please run 'make ARCH=um mrproper'"
+
+ That happens because internally kunit.py specifies the build directory in
+ the command ``make O=output/dir`` through the argument ``--build_dir``,
+ which is ``.kunit`` by default, and before starting out-of-tree build,
+ the source tree must be clean.
+
+ There's also the same caveats mentioned in the "Build directory for the kernel"
+ section of the :doc:`admin-guide </admin-guide/README>`, that is,
+ after it's used it must be used for all invocations of ``make``.
+ The good news is that it can indeed be solved by running
+ ``make ARCH=um mrproper``, just be aware that this will delete the
+ current configuration and all generated files.
+
If everything worked correctly, you should see the following:

.. code-block::
--
2.37.1