On Wed, Apr 10, 2019 at 10:12:40PM +0200, Arnd Bergmann wrote: > llvm does does not understand -march=z9-109 and older target > specifiers, so disable the respective Kconfig settings and > the logic to make the boot code work on old systems when > building with clang. > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> > --- > arch/s390/Kconfig | 6 ++++++ > arch/s390/boot/Makefile | 2 ++ > 2 files changed, 8 insertions(+) ... > diff --git a/arch/s390/boot/Makefile b/arch/s390/boot/Makefile > index c844eaf24ed7..953a74d04990 100644 > --- a/arch/s390/boot/Makefile > +++ b/arch/s390/boot/Makefile > @@ -11,6 +11,7 @@ KASAN_SANITIZE := n > KBUILD_AFLAGS := $(KBUILD_AFLAGS_DECOMPRESSOR) > KBUILD_CFLAGS := $(KBUILD_CFLAGS_DECOMPRESSOR) > > +ifndef CONFIG_CC_IS_CLANG > # > # Use -march=z900 for als.c to be able to print an error > # message if the kernel is started on a machine which is too old > @@ -25,6 +26,7 @@ CFLAGS_als.o += -march=z900 > CFLAGS_REMOVE_sclp_early_core.o += $(CC_FLAGS_MARCH) > CFLAGS_sclp_early_core.o += -march=z900 > endif > +endif This contradicts the whole purpose of als.c - printing an error message to the console if the kernel is compiled for a newer architecture than it is running on (and therefore uses instructions unknown to the current system). If this can't be fixed/changed in clang, then it should be at least changed to the lowest possible architecture.
