Quoting Stephen Boyd (2024-07-10 13:12:38) > Add test managed wrappers for of_overlay_apply() that automatically > removes the overlay when the test is finished. This API is intended for > use by KUnit tests that test code which relies on 'struct device_node's > and of_*() APIs. > > KUnit tests will call of_overlay_apply_kunit() to load an overlay that's > been built into the kernel image. When the test is complete, the overlay > will be removed. > > This has a few benefits: > > 1) It keeps the tests hermetic because the overlay is removed when the > test is complete. Tests won't even be aware that an overlay was > loaded in another test. > > 2) The overlay code can live right next to the unit test that loads it. > The overlay and the unit test can be compiled into one kernel module > if desired. > > 3) We can test different device tree configurations by loading > different overlays. The overlays can be written for a specific test, > and there can be many of them loaded per-test without needing to jam > all possible combinations into one DTB. > > 4) It also allows KUnit to test device tree dependent code on any > architecture, not just UML. This allows KUnit tests to test > architecture specific device tree code. > > There are some potential pitfalls though. Test authors need to be > careful to not overwrite properties in the live tree. The easiest way to > do this is to add and remove nodes with a 'kunit-' prefix, almost > guaranteeing that the same node won't be present in the tree loaded at > boot. > > Suggested-by: Rob Herring <robh@xxxxxxxxxx> > Cc: Rob Herring <robh@xxxxxxxxxx> > Cc: Saravana Kannan <saravanak@xxxxxxxxxx> > Reviewed-by: Rob Herring (Arm) <robh@xxxxxxxxxx> > Reviewed-by: David Gow <davidgow@xxxxxxxxxx> > Signed-off-by: Stephen Boyd <sboyd@xxxxxxxxxx> > --- Applied to clk-next
