+ifeq ($(ALLSOURCE_ARCHS),)
+ifeq ($(ARCH),um)
+ALLINCLUDE_ARCHS := $(ARCH) $(SUBARCH)
+else
+ALLINCLUDE_ARCHS := $(ARCH)
+endif
+else
+#Allow user to specify only ALLSOURCE_PATHS on the command line, keeping existing behaviour.
+ALLINCLUDE_ARCHS := $(ALLSOURCE_ARCHS)
+endif
+