HelenOS sources

ethip_get_mtu      60 uspace/srv/net/ethip/ethip.c static errno_t ethip_get_mtu(iplink_srv_t *srv, size_t *mtu);
ethip_get_mtu      73 uspace/srv/net/ethip/ethip.c 	.get_mtu = ethip_get_mtu,
HelenOS homepage, sources at GitHub