Index: sys/dev/sfxge/common/ef10_nic.c
===================================================================
--- sys/dev/sfxge/common/ef10_nic.c
+++ sys/dev/sfxge/common/ef10_nic.c
@@ -1135,6 +1135,12 @@
 	else
 		encp->enc_rx_var_packed_stream_supported = B_FALSE;
 
+	/* Check if the firmware supports FW subvariant w/o Tx checksumming */
+	if (CAP_FLAGS2(req, FW_SUBVARIANT_NO_TX_CSUM))
+		encp->enc_fw_subvariant_no_tx_csum_supported = B_TRUE;
+	else
+		encp->enc_fw_subvariant_no_tx_csum_supported = B_FALSE;
+
 	/* Check if the firmware supports set mac with running filters */
 	if (CAP_FLAGS1(req, VADAPTOR_PERMIT_SET_MAC_WHEN_FILTERS_INSTALLED))
 		encp->enc_allow_set_mac_with_installed_filters = B_TRUE;
Index: sys/dev/sfxge/common/efx.h
===================================================================
--- sys/dev/sfxge/common/efx.h
+++ sys/dev/sfxge/common/efx.h
@@ -1287,6 +1287,7 @@
 	boolean_t		enc_init_evq_v2_supported;
 	boolean_t		enc_rx_packed_stream_supported;
 	boolean_t		enc_rx_var_packed_stream_supported;
+	boolean_t		enc_fw_subvariant_no_tx_csum_supported;
 	boolean_t		enc_pm_and_rxdp_counters;
 	boolean_t		enc_mac_stats_40g_tx_size_bins;
 	uint32_t		enc_tunnel_encapsulations_supported;
Index: sys/dev/sfxge/common/siena_nic.c
===================================================================
--- sys/dev/sfxge/common/siena_nic.c
+++ sys/dev/sfxge/common/siena_nic.c
@@ -178,6 +178,7 @@
 	encp->enc_allow_set_mac_with_installed_filters = B_TRUE;
 	encp->enc_rx_packed_stream_supported = B_FALSE;
 	encp->enc_rx_var_packed_stream_supported = B_FALSE;
+	encp->enc_fw_subvariant_no_tx_csum_supported = B_FALSE;
 
 	/* Siena supports two 10G ports, and 8 lanes of PCIe Gen2 */
 	encp->enc_required_pcie_bandwidth_mbps = 2 * 10000;