+ifneq ($(SCAN_EXTRA),)
+SCAN_STAMP=tmp/info/.scan-$(SCAN_TARGET)-$(shell ls $(SCAN_EXTRA) 2>/dev/null | (md5sum || md5) 2>/dev/null | cut -d' ' -f1)
+$(SCAN_STAMP):
+ rm -f tmp/info/.scan-$(SCAN_TARGET)-*
+ touch $@
+endif
+
+# FIXME: generate this dynamically?
+ifeq ($(SCAN_TARGET),packageinfo)
+tmp/info/.packageinfo-kernel: $(wildcard package/kernel/modules/*.mk)
+endif
+