When memory regions overlap, priority can be used to specify which of them takes priority. By making the priority values signed rather than unsigned, we make it more convenient to implement a situation where one "background" region should appear only where no other region exists: rather than having to explicitly specify a high priority for all the other regions, we can let them take the default (zero) priority and specify a negative priority for the background region.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> Signed-off-by: Marcel Apfelbaum <marce...@redhat.com> --- Changes from v4: - Addressed Peter Maydell comments - Changed commit comment docs/memory.txt | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/docs/memory.txt b/docs/memory.txt index feb9fe9..174c0d7 100644 --- a/docs/memory.txt +++ b/docs/memory.txt @@ -80,6 +80,10 @@ guest. This is done with memory_region_add_subregion_overlap(), which allows the region to overlap any other region in the same container, and specifies a priority that allows the core to decide which of two regions at the same address are visible (highest wins). +Priority values are signed, and the default value is zero. This means that +you can use memory_region_add_subregion_overlap() both to specify a region +that must sit 'above' any others (with a positive priority) and also a +background region that sits 'below' others (with a negative priority). Visibility ---------- -- 1.8.3.1
