--- /dev/null
+#
+# Copyright (C) 2007 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+# debug flags:
+#
+# d: show subdirectory tree
+# t: show added targets
+# l: show legacy targets
+# v: verbose (no .SILENCE for common targets)
+
+ifeq ($(DEBUG),all)
+ build_debug:=dltv
+else
+ build_debug:=$(DEBUG)
+endif
+
+define debug
+$$(findstring $(2),$$(if $$(DEBUG_DIR),$$(if $$(filter $$(DEBUG_DIR)%,$(1)),$(build_debug)),$(build_debug)))
+endef
+
+define warn
+$$(if $(call debug,$(1),$(2)),$$(warning $(3)))
+endef
+
+define warn_eval
+$(call warn,$(1),$(2),$(3) $(4))
+$(4)
+endef
+
+