ib_mtu
maxval = state->hs_queryport.ib_mtu;
cp->cp_max_mtu = port->ib_mtu; /* XXX now from query_port */
uint32_t ib_mtu :4;
uint32_t ib_mtu :4;
enum ib_mtu max_mtu;
enum ib_mtu active_mtu;
enum ib_mtu path_mtu;