[PATCH v2 2/2] ref-manual: tasks: do_cleansstate: recommend using '-f' instead for a shared sstate

[Luca Ceresoli <luca.ceresoli@bootlin.com>]

do_cleansstat can produce build errors when using a shared sstate cache.

Add a note to clearly discourage, provide a safe alternative (bitbake -f),
and the rationale.

Proposed-by: Quentin Schulz  <quentin.schulz@theobroma-systems.com>
Link: https://lore.kernel.org/yocto-docs/20240219155513.76738-1-luca.ceresoli@bootlin.com/T/#m5529687ecb0f9ec2dacddcb6ff58e2df73af9cde
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
 documentation/ref-manual/tasks.rst | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/documentation/ref-manual/tasks.rst b/documentation/ref-manual/tasks.rst
index ebaa03dc7613..9f130bb4e0c9 100644
--- a/documentation/ref-manual/tasks.rst
+++ b/documentation/ref-manual/tasks.rst
@@ -513,6 +513,18 @@ When you run the :ref:`ref-tasks-cleansstate` task, the OpenEmbedded build syste
 no longer uses any sstate. Consequently, building the recipe from
 scratch is guaranteed.
 
+.. note::
+
+   Using :ref:`ref-tasks-cleansstate` with a shared sstate directory is not
+   recommended because it could trigger an error during the build of a
+   separate bitbake instance. This is because the builds check sstate "up
+   front" but download the files later, so it if is deleted in the
+   meantime, it will cause an error but not a total failure as it will
+   rebuild it.
+
+   The reliable and preferred way to force a new build is to use ``bitbake
+   -f`` instead.
+
 .. note::
 
    The :ref:`ref-tasks-cleansstate` task cannot remove sstate from a remote sstate

-- 
2.34.1