+# The BayLibre ACME driver needs sys/timerfd.h. Don't try to build it if
+# this header isn't available.
+AC_CHECK_HEADERS([sys/timerfd.h], [], [HW_BAYLIBRE_ACME="no"])
+
+# The ACME driver can only be built for Linux.
+case "$host" in
+ *linux*) ;;
+ *) HW_BAYLIBRE_ACME="no" ;;
+esac
+