Hi, Ruoyao, On Sun, Jun 25, 2023 at 2:42 AM WANG Xuerui <kernel@xxxxxxxxxx> wrote: > > From: WANG Xuerui <git@xxxxxxxxxx> > > Now the arch code is mostly ready for LLVM/Clang consumption, it is time > to re-organize the CFLAGS a little to actually enable the LLVM build. > > In particular, -mexplicit-relocs and -mdirect-extern-access are not > necessary nor supported on Clang; feature detection via cc-option would > not work, because that way the broken combo of "new GNU as + old GCC" > would seem to get "fixed", but actually produce broken kernels. > Explicitly depending on CONFIG_CC_IS_CLANG is thus necessary to not > regress UX for those building their own kernels. > > A build with !RELOCATABLE && !MODULE is confirmed working within a QEMU > environment; support for the two features are currently blocked on > LLVM/Clang, and will come later. > > Signed-off-by: WANG Xuerui <git@xxxxxxxxxx> > --- > arch/loongarch/Makefile | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile > index 366771016b99..82c619791a63 100644 > --- a/arch/loongarch/Makefile > +++ b/arch/loongarch/Makefile > @@ -51,7 +51,9 @@ LDFLAGS_vmlinux += -static -n -nostdlib > > # When the assembler supports explicit relocation hint, we must use it. > # GCC may have -mexplicit-relocs off by default if it was built with an old > -# assembler, so we force it via an option. > +# assembler, so we force it via an option. For LLVM/Clang the desired behavior > +# is the default, and the flag is not supported, so don't pass it if Clang is > +# being used. > # > # When the assembler does not supports explicit relocation hint, we can't use > # it. Disable it if the compiler supports it. > @@ -61,8 +63,10 @@ LDFLAGS_vmlinux += -static -n -nostdlib > # combination of a "new" assembler and "old" compiler is not supported. Either > # upgrade the compiler or downgrade the assembler. > ifdef CONFIG_AS_HAS_EXPLICIT_RELOCS > +ifndef CONFIG_CC_IS_CLANG > cflags-y += -mexplicit-relocs > KBUILD_CFLAGS_KERNEL += -mdirect-extern-access > +endif I prefer to drop CONFIG_CC_IS_CLANG and use cflags-y += $(call cc-option,-mexplicit-relocs) KBUILD_CFLAGS_KERNEL += $(call cc-option,-mdirect-extern-access) Then Patch-6 can be merged in this. What's your opinion? Huacai > else > cflags-y += $(call cc-option,-mno-explicit-relocs) > KBUILD_AFLAGS_KERNEL += -Wa,-mla-global-with-pcrel > -- > 2.40.0 >
