gmac_mapcache_create
sc->sc_rxmaps = gmac_mapcache_create(sc->sc_dmat, MAX_RXMAPS,
sc->sc_txmaps = gmac_mapcache_create(sc->sc_dmat, MAX_TXMAPS,
gmac_mapcache_create(bus_dma_tag_t, size_t, bus_size_t, int);