When you build targets that require the kernel configuration, dot-config is set to 1, then the top-level Makefile includes auto.conf. However, Make considers its inclusion is optional because the '-include' directive is used here. If a necessary configuration file is missing for the external module building, the following error message is displayed: ERROR: Kernel configuration is invalid. include/generated/autoconf.h or include/config/auto.conf are missing. Run 'make oldconfig && make prepare' on kernel src to fix it. However, Make still continues building; /bin/false let the creation of 'include/config/auto.config' fail, but Make can ignore the error since it is included by the '-include' directive. I guess the reason of using '-include' directive was to suppress the warning when you build the kernel from a pristine source tree: Makefile:605: include/config/auto.conf: No such file or directory The previous commit made sure include/config/auto.conf exists after the 'make *config' stage. Now, we can use the 'include' directive without showing the warning. Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makefile b/Makefile index d15ac32..ef24068 100644 --- a/Makefile +++ b/Makefile @@ -584,7 +584,7 @@ virt-y := virt/ endif # KBUILD_EXTMOD ifeq ($(dot-config),1) --include include/config/auto.conf +include include/config/auto.conf endif # The all: target is the default when no target is given on the -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html