XDP_UMEM_SG_FLAG
mbuf = pool->dev && (umem->flags & XDP_UMEM_SG_FLAG);
xs->sg = !!(xs->umem->flags & XDP_UMEM_SG_FLAG);
if (umem_shared && !(pool->umem->flags & XDP_UMEM_SG_FLAG)) {
pool->umem->flags |= XDP_UMEM_SG_FLAG;
if (umem->flags & XDP_UMEM_SG_FLAG)