This patch is simply adding a comment to reserve save record number space
to avoid the risk of clashes between existent downstream changes made by
Amazon and future upstream changes which may be incompatible.
Signed-off-by: Paul Durrant <pdurrant@amazon.com> Reviewed-by: Wei Liu <wl@xen.org> Acked-by: Jan Beulich <jbeulich@suse.com>