On Sat, Feb 9, 2019 at 2:27 AM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote: > > On Thu, Feb 7, 2019 at 9:51 PM Nathan Chancellor > <natechancellor@xxxxxxxxx> wrote: > > > > On Thu, Feb 07, 2019 at 02:01:51PM -0800, ndesaulniers@xxxxxxxxxx wrote: > > > This is needed because clang doesn't select which linker to use based on > > > $LD but rather -fuse-ld=$(LD). This is problematic especially for > > > cc-ldoption, which checks for linker flag support via invoking the > > > compiler, rather than the linker. What do you mean by 'problematic' ? I see no build error in arch/arm64/kernel/vdso/Makefile, at least. Clang uses BFD linker by default, which may not match to the $(LD) passed in. Is this what you mean? > > > Link: https://github.com/ClangBuiltLinux/linux/issues/342 > > > Suggested-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > > --- > > > Makefile | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/Makefile b/Makefile > > > index 0eae4277206e..6307c17259ea 100644 > > > --- a/Makefile > > > +++ b/Makefile > > > @@ -502,6 +502,9 @@ endif > > > CLANG_FLAGS += -no-integrated-as > > > KBUILD_CFLAGS += $(CLANG_FLAGS) > > > KBUILD_AFLAGS += $(CLANG_FLAGS) > > > +ifneq ($(shell $(LD) --version 2>&1 | head -n 1 | grep LLD),) > > > +CLANG_FLAGS += -fuse-ld=lld > > Sorry, Sedat reports [0] that this is not quite correct; if $(LD) > matches LLD, then we need to set -fuse-ld=$(LD), not -fuse-ld=lld, > since you may have lld installed as lld-7 or lld-8, for example: > https://github.com/ClangBuiltLinux/linux/issues/358 Hmm, $(LD) might be a full path. Looks like Clang can take a full-path for -fuse-ld=, but does it work for GCC? > > > +endif > > > > This section needs to be moved up above KBUILD_CFLAGS otherwise it never > > actually gets passed along. > > > > With that change, please add: > > > > Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > Tested-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > > > > export CLANG_FLAGS > > > endif > > > > > > -- > > > 2.20.1.791.gb4d0f1c61a-goog > > > > > > > -- > Thanks, > ~Nick Desaulniers -- Best Regards Masahiro Yamada
