Without this, we were only ever using the first 256MB of VRAM. Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97593 Tested-by: Konstantin A. Lepikhov <lakostis@altlinux.org> Tested-by: Arek Ruśniak <arek.rusi@gmail.com> Reviewed-by: Alex Deucher <alexander.deucher@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>