diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c
index 8f156bc07c95..6415fb5ac572 100644
--- a/sys/dev/sio/sio.c
+++ b/sys/dev/sio/sio.c
@@ -270,7 +270,6 @@ struct com_s {
 	u_long	error_counts[CE_NTYPES];
 
 	u_long	rclk;
-	int	gdb;
 
 	struct resource *irqres;
 	struct resource *ioportres;
@@ -1174,12 +1173,12 @@ determined_type: ;
 		if (ret)
 			device_printf(dev, "could not activate interrupt\n");
 #if defined(DDB) && (defined(BREAK_TO_DEBUGGER) || \
-    defined(ALT_BREAK_TO_DEBUGGER) || defined(GDB_AUTO_ENTER))
+    defined(ALT_BREAK_TO_DEBUGGER))
 		/*
 		 * Enable interrupts for early break-to-debugger support
-		 * on the console and/or gdb port.
+		 * on the console.
 		 */
-		if (ret == 0 && (unit == comconsole || unit == siogdbunit))
+		if (ret == 0 && unit == comconsole)
 			outb(siocniobase + com_ier, IER_ERXRDY | IER_ERLS |
 			    IER_EMSC);
 #endif
@@ -1426,13 +1425,13 @@ comhardclose(com)
 	tp = com->tp;
 
 #if defined(DDB) && (defined(BREAK_TO_DEBUGGER) || \
-    defined(ALT_BREAK_TO_DEBUGGER) || defined(GDB_AUTO_ENTER))
+    defined(ALT_BREAK_TO_DEBUGGER))
 	/*
 	 * Leave interrupts enabled and don't clear DTR if this is the
 	 * console. This allows us to detect break-to-debugger events
 	 * while the console device is closed.
 	 */
-	if (com->unit != comconsole || com->unit != siogdbunit)
+	if (com->unit != comconsole)
 #endif
 	{
 		sio_setreg(com, com_ier, 0);
@@ -1807,17 +1806,6 @@ siointr1(com)
 			    db_alt_break(recv_data, &com->alt_brk_state) != 0)
 				breakpoint();
 #endif /* ALT_BREAK_TO_DEBUGGER */
-#ifdef GDB_AUTO_ENTER
-			if (gdb_auto_enter != 0 && com->unit == siogdbunit) {
-				printf("gdb: %c\n", recv_data);
-				if (db_gdb_packet(recv_data, &com->gdb) != 0) {
-					printf("going to gdb mode\n");
-					boothowto |= RB_GDB;
-					breakpoint();
-					/* goto cont; */
-				}
-			}
-#endif /* GDB_AUTO_ENTER */
 #endif /* DDB */
 			if (line_status & (LSR_BI | LSR_FE | LSR_PE)) {
 				/*