ixgbe_dmamap_create
error = ixgbe_dmamap_create(rxr->ptag, 0, &rxbuf->pmap);
r = ixgbe_dmamap_create(dma->dma_tag, 0, &dma->dma_map);
error = ixgbe_dmamap_create(txr->txtag, 0, &txbuf->map);
int ixgbe_dmamap_create(ixgbe_dma_tag_t *, int, bus_dmamap_t *);