The use of an undefined macro in an #if directive is warned, but only in *.c files. No warning from other files such as *.S, *.lds.S. Since -Wundef is a preprocessor-related warning, it should be added to KBUILD_CPPFLAGS instead of KBUILD_CFLAGS. Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> --- Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Makefile b/Makefile index 027d9163eff6..898a759e314e 100644 --- a/Makefile +++ b/Makefile @@ -523,12 +523,12 @@ LINUXINCLUDE := \ $(USERINCLUDE) KBUILD_AFLAGS := -D__ASSEMBLY__ -fno-PIE -KBUILD_CFLAGS := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \ +KBUILD_CFLAGS := -Wall -Werror=strict-prototypes -Wno-trigraphs \ -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE \ -Werror=implicit-function-declaration -Werror=implicit-int \ -Werror=return-type -Wno-format-security \ -std=gnu11 -KBUILD_CPPFLAGS := -D__KERNEL__ +KBUILD_CPPFLAGS := -D__KERNEL__ -Wundef KBUILD_AFLAGS_KERNEL := KBUILD_CFLAGS_KERNEL := KBUILD_AFLAGS_MODULE := -DMODULE -- 2.34.1
