[docs][PATCH v2] ref-manual/variables.rst: document SSTATE_SKIP_CREATION

[ecordonnier@snap.com]

From: Etienne Cordonnier <ecordonnier@snap.com>

Signed-off-by: Etienne Cordonnier <ecordonnier@snap.com>
---
 documentation/ref-manual/variables.rst | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 643a3e7ae8f..dc6dd2f1ba4 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -9049,6 +9049,26 @@ system and gives an overview of their function and contents.
 
       For details on the process, see the :ref:`ref-classes-staging` class.
 
+   :term:`SSTATE_SKIP_CREATION`
+      The :term:`SSTATE_SKIP_CREATION` variable can be used to skip the creation of
+      :ref:`shared state <overview-manual/concepts:shared state cache>` tarball files. It makes sense e.g. for image creation tasks as
+      tarring images and keeping them in sstate would consume a lot of
+      disk space.
+
+      In general it is not recommended to use this variable as missing sstate
+      artefacts adversely impact the build, particularly for entries in the
+      middle of dependency chains. The case it can make sense is where the
+      size and time costs of the artefact are similar to just running the
+      tasks. This generally only applies to end artefact output like images.
+
+      The syntax to disable it for one task is:
+
+          SSTATE_SKIP_CREATION:task-image-complete = "1"
+
+      The syntax to disable it for the whole recipe is:
+
+          SSTATE_SKIP_CREATION = "1"
+
    :term:`STAGING_BASE_LIBDIR_NATIVE`
       Specifies the path to the ``/lib`` subdirectory of the sysroot
       directory for the build host.
-- 
2.43.0