Pick an arbitrary hart ID for the target

src/rtos/riscv_debug.c

@@ -167,6 +167,8 @@ static int riscv_gdb_thread_packet(struct connection *connection, const char *pa
 
 		switch (tid) {
 		case 0:
+			riscv_set_rtos_hartid(target, 0);
+			break;
 		case -1:
 			riscv_set_all_rtos_harts(target);
 			break;