BF_KMEM_ALLOC_CONTIG
dmat->bounce_flags |= BF_KMEM_ALLOC_CONTIG;
BF_KMEM_ALLOC = BF_KMEM_ALLOC_PAGES | BF_KMEM_ALLOC_CONTIG,
(dmat->bounce_flags & BF_KMEM_ALLOC_CONTIG) == 0)