BUSDMA_MD_VIRT
error = bd_md_add_seg(md, BUSDMA_MD_VIRT, ioc.u.md.virt_addr, len);
bd_md_del_segs(md, BUSDMA_MD_VIRT, 0);
error = bd_md_add_seg(md, BUSDMA_MD_VIRT, addr, tag->u.tag.maxsz);
bd_md_del_segs(md, BUSDMA_MD_VIRT, 1);
space != BUSDMA_MD_VIRT) {