+# external modules needs include/linux/autoconf.h and include/config/auto.conf
+# but do not care if they are up-to-date. Use auto.conf to trigger the test
+PHONY += include/config/auto.conf
+
+include/config/auto.conf:
+ $(Q)test -e include/linux/autoconf.h -a -e $@ || ( \
+ echo; \
+ echo " ERROR: Kernel configuration is invalid."; \
+ echo " include/linux/autoconf.h or $@ are missing."; \
+ echo " Run 'make oldconfig && make prepare' on kernel src to fix it."; \
+ echo; \
+ /bin/false)
+
+endif # KBUILD_EXTMOD