diff --git a/usr/src/uts/common/io/mlxcx/mlxcx_gld.c b/usr/src/uts/common/io/mlxcx/mlxcx_gld.c
index 5490472d50a0..ec72f1061a24 100644
--- a/usr/src/uts/common/io/mlxcx/mlxcx_gld.c
+++ b/usr/src/uts/common/io/mlxcx/mlxcx_gld.c
@@ -128,14 +128,13 @@ mlxcx_speed_to_bits(mlxcx_eth_proto_t proto, mlxcx_ext_eth_proto_t ext_proto)
 	case MLXCX_EXTPROTO_100GAUI_2_100GBASE_CR2_KR2:
 	case MLXCX_EXTPROTO_100GAUI_1_100GBASE_CR_KR:
 		return (100ULL * GBITS);
-#if 0	/* Not yet... */
 	case MLXCX_EXTPROTO_200GAUI_4_200GBASE_CR4_KR4:
 	case MLXCX_EXTPROTO_200GAUI_2_200GBASE_CR2_KR2:
+		return (200ULL * GBITS);
 	case MLXCX_EXTPROTO_400GAUI_8:
 	case MLXCX_EXTPROTO_400GAUI_4_400GBASE_CR4_KR4:
-		/* Not yet supported... */
+		return (400ULL * GBITS);
 		break;
-#endif /* Not yet... */
 	default:
 		/*
 		 * There ARE legitimate single-bit values we don't support,
@@ -1359,6 +1358,18 @@ mlxcx_mac_propinfo(void *arg, const char *pr_name, mac_prop_id_t pr_num,
 		mac_prop_info_set_perm(prh, MAC_PROP_PERM_RW);
 		mac_prop_info_set_default_fec(prh, LINK_FEC_AUTO);
 		break;
+	case MAC_PROP_ADV_400GFDX_CAP:
+	case MAC_PROP_EN_400GFDX_CAP:
+		mac_prop_info_set_perm(prh, MAC_PROP_PERM_READ);
+		mac_prop_info_set_default_uint8(prh,
+		    (port->mlp_ext_oper_proto & MLXCX_EXTPROTO_400G) != 0);
+		break;
+	case MAC_PROP_ADV_200GFDX_CAP:
+	case MAC_PROP_EN_200GFDX_CAP:
+		mac_prop_info_set_perm(prh, MAC_PROP_PERM_READ);
+		mac_prop_info_set_default_uint8(prh,
+		    (port->mlp_ext_oper_proto & MLXCX_EXTPROTO_200G) != 0);
+		break;
 	case MAC_PROP_ADV_100GFDX_CAP:
 	case MAC_PROP_EN_100GFDX_CAP:
 		mac_prop_info_set_perm(prh, MAC_PROP_PERM_READ);
diff --git a/usr/src/uts/common/io/mlxcx/mlxcx_reg.h b/usr/src/uts/common/io/mlxcx/mlxcx_reg.h
index 4bca99246d9b..be922ef5bd13 100644
--- a/usr/src/uts/common/io/mlxcx/mlxcx_reg.h
+++ b/usr/src/uts/common/io/mlxcx/mlxcx_reg.h
@@ -2352,6 +2352,13 @@ typedef enum {
 	MLXCX_EXTPROTO_100GAUI_2_100GBASE_CR2_KR2 | \
 	MLXCX_EXTPROTO_100GAUI_1_100GBASE_CR_KR)
 
+/* 200G and higher only are in the extended protocol bits. */
+#define	MLXCX_EXTPROTO_200G	(MLXCX_EXTPROTO_200GAUI_4_200GBASE_CR4_KR4 | \
+	MLXCX_EXTPROTO_200GAUI_2_200GBASE_CR2_KR2)
+
+#define	MLXCX_EXTPROTO_400G	(MLXCX_EXTPROTO_400GAUI_8 | \
+	MLXCX_EXTPROTO_400GAUI_4_400GBASE_CR4_KR4)
+
 
 typedef enum {
 	MLXCX_AUTONEG_DISABLE_CAP	= 1 << 5,