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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Tue, 9 Apr 2019 08:43:09 +0200
Message-ID: <CAK8P3a39NqQOp+0=WYuWh0UmpH=kEFLKyymNYm8DH-0gx9XaaQ@mail.gmail.com>
Subject: Re: [PATCH 03/12] s390: purgatory: pass --target option to clang
To:     Nathan Chancellor <natechancellor@gmail.com>
Cc:     Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        clang-built-linux@googlegroups.com,
        Nick Desaulniers <ndesaulniers@google.com>,
        linux-s390 <linux-s390@vger.kernel.org>,
        Philipp Rudo <prudo@linux.ibm.com>,
        Hendrik Brueckner <brueckner@linux.ibm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Tue, Apr 9, 2019 at 12:03 AM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> On Mon, Apr 08, 2019 at 11:26:16PM +0200, Arnd Bergmann wrote:
> > The purgatory Makefile does not inherit the original cflags,
> > so clang falls back to the default target architecture when
> > building it, typically this would be x86 when cross-compiling.
> >
> > Pass --target=s390x-linux to all compilers that understand
> > this option.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > ---
> >  arch/s390/purgatory/Makefile | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/s390/purgatory/Makefile b/arch/s390/purgatory/Makefile
> > index ce6a3f75065b..3a14b968cec3 100644
> > --- a/arch/s390/purgatory/Makefile
> > +++ b/arch/s390/purgatory/Makefile
> > @@ -22,6 +22,7 @@ KBUILD_CFLAGS := -fno-strict-aliasing -Wall -Wstrict-prototypes
> >  KBUILD_CFLAGS += -Wno-pointer-sign -Wno-sign-compare
> >  KBUILD_CFLAGS += -fno-zero-initialized-in-bss -fno-builtin -ffreestanding
> >  KBUILD_CFLAGS += -c -MD -Os -m64 -msoft-float -fno-common
> > +KBUILD_CFLAGS += $(call cc-option,--target=s390x-linux)
> >  KBUILD_CFLAGS += $(call cc-option,-fno-PIE)
> >  KBUILD_AFLAGS := $(filter-out -DCC_USING_EXPOLINE,$(KBUILD_AFLAGS))
> >
> Would
>
> ifdef CONFIG_CC_IS_CLANG
> KBUILD_CFLAGS += --target=s390x-linux
> endif
>
> be a little clearer (and save a cc-option call)?

Fine with me as well. Actually I noticed later that we need the same
thing for arch/s390/boot/Makefile and arch/s390/boot/compressed/Makefile
in some form, so maybe we should drop this one for now and find
a solution that works for all three of them. The boot stuff is the one
patch I did not send, since I did not think I had a good solution there,
just one that happened to make it build.

> Otherwise, makes sense.
>
> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>

 Thanks,

       Arnd