ref-manual/classes,variables: document the CCACHE_DISABLE variable

Can be used in recipes that want to explicitly skip Ccache support when
the ccache class is enabled.

Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
(From yocto-docs rev: e4fb6cd20955046a397b63bfe57f6cb4020b9cbb)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
(cherry picked from commit b1b4adc8d4d9d23ff6fd91bca632bb0f5277e72b)
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

2 files changed, 11 insertions, 2 deletions

diff --git a/documentation/ref-manual/classes.rst b/documentation/ref-manual/classes.rst
index e238575a15..d5d59cdc99 100644
--- a/documentation/ref-manual/classes.rst
+++ b/documentation/ref-manual/classes.rst
@@ -355,8 +355,12 @@ file for details about how to enable this mechanism in your configuration
 file, how to disable it for specific recipes, and how to share ``ccache``
 files between builds.
 
-However, using the class can lead to unexpected side-effects. Thus, using
-this class is not recommended.
+Recipes can also explicitly disable `Ccache` support even when the
+:ref:`ref-classes-ccache` class is enabled, by setting the
+:term:`CCACHE_DISABLE` variable to "1".
+
+Using the :ref:`ref-classes-ccache` class can lead to unexpected side-effects.
+Using this class is not recommended.
 
 .. _ref-classes-chrpath:
 
diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 4c67baaadd..f517388317 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -1458,6 +1458,11 @@ system and gives an overview of their function and contents.
    :term:`CC`
       The minimal command and arguments used to run the C compiler.
 
+   :term:`CCACHE_DISABLE`
+      When inheriting the :ref:`ref-classes-ccache` class, the
+      :term:`CCACHE_DISABLE` variable can be set to "1" in a recipe to disable
+      `Ccache` support. This is useful when the recipe is known to not support it.
+
    :term:`CCLD`
       The minimal command and arguments used to run the linker when the C
       compiler is being used as the linker.