1 files changed, 13 insertions, 0 deletions

diff --git a/sys/dev/e1000/if_igb.c b/sys/dev/e1000/if_igb.c
index 5f0557833a3f..d6f7162a57c6 100644
--- a/sys/dev/e1000/if_igb.c
+++ b/sys/dev/e1000/if_igb.c
@@ -4712,6 +4712,18 @@ igb_initialize_receive_units(struct adapter *adapter)
 		rctl |= E1000_RCTL_SZ_2048;
 	}
 
+	/*
+	 * If TX flow control is disabled and there's >1 queue defined,
+	 * enable DROP.
+	 *
+	 * This drops frames rather than hanging the RX MAC for all queues.
+	 */
+	if ((adapter->num_queues > 1) &&
+	    (adapter->fc == e1000_fc_none ||
+	     adapter->fc == e1000_fc_rx_pause)) {
+		srrctl |= E1000_SRRCTL_DROP_EN;
+	}
+
 	/* Setup the Base and Length of the Rx Descriptor Rings */
 	for (int i = 0; i < adapter->num_queues; i++, rxr++) {
 		u64 bus_addr = rxr->rxdma.dma_paddr;
@@ -6255,6 +6267,7 @@ igb_set_flowcntl(SYSCTL_HANDLER_ARGS)
 
 	adapter->hw.fc.current_mode = adapter->hw.fc.requested_mode;
 	e1000_force_mac_fc(&adapter->hw);
+	/* XXX TODO: update DROP_EN on each RX queue if appropriate */
 	return (error);
 }