fwdma_malloc_size
seg->v_addr = fwdma_malloc_size(am->dma_tag, &seg->dma_map,
void *fwdma_malloc_size(bus_dma_tag_t, bus_dmamap_t *, bus_size_t, bus_addr_t *, int);
db_tr->buf = fwdma_malloc_size(dbch->dmat,