Comment # 7 on bug 94667 from Chris Wilson

Objects used for sharing backing pixmaps are converted to linear
(SharePixmapBacking). Prime imports use whatever tiling is registered with the
foreign surface (both DRI3 and SetSharedPixmapBacking), similarly we
communicate the tiling for an export of an existing pixmap (DRI3). We
definitely want to be able to pass tiled surfaces between DRI2/DRI3 clients and
the Xserver!