docs/memory: Explictly state that MemoryRegion priority is signed

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.maydell@linaro.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marcel Apfelbaum <marcel.a@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Marcel Apfelbaum 2013-09-16 11:21:15 +03:00 committed by Michael S. Tsirkin
parent a1ff8ae066
commit 8002ccd6e4
1 changed files with 4 additions and 0 deletions

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@ -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
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