From: Masahiro Yamada <masahiroy@kernel.org>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Albert Ou <aou@eecs.berkeley.edu>,
Michal Marek <michal.lkml@markovi.net>,
Nick Desaulniers <ndesaulniers@google.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
clang-built-linux <clang-built-linux@googlegroups.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"open list:SIFIVE DRIVERS" <linux-riscv@lists.infradead.org>
Subject: Re: [PATCH] kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS
Date: Tue, 10 Aug 2021 09:05:58 +0900 [thread overview]
Message-ID: <CAK7LNAT+7y+uNXKfTfW7HpQa1mVt0nuKHFPMQ3tMhjJrKt0v7Q@mail.gmail.com> (raw)
In-Reply-To: <59ce441e-8deb-39ff-700f-4e1c4e871177@kernel.org>
On Fri, Aug 6, 2021 at 3:46 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> On 8/5/2021 8:01 AM, Masahiro Yamada wrote:
> > LLVM_IAS is the user interface to set the -(no-)integrated-as flag,
> > and it should be used only for that purpose.
> >
> > LLVM_IAS is checked in some places to determine the assembler type,
> > but it is not precise.
> >
> > $ make CC=gcc LLVM_IAS=1
> >
> > ... will use the GNU assembler since LLVM_IAS=1 is effective only when
> > $(CC) is clang.
> >
> > Of course, the combination of CC=gcc and LLVM_IAS=1 does not make
> > sense, but the build system can be more robust against such insane
> > input.
> >
> > Commit ba64beb17493a ("kbuild: check the minimum assembler version in
> > Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
> > because Kconfig checks the version string from the assembler in use.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Applied to linux-kbuild.
> > ---
> >
> > Makefile | 2 +-
> > arch/riscv/Makefile | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 4ab151060931..8b56c9692c3c 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -844,7 +844,7 @@ else
> > DEBUG_CFLAGS += -g
> > endif
> >
> > -ifneq ($(LLVM_IAS),1)
> > +ifndef CONFIG_AS_IS_LLVM
> > KBUILD_AFLAGS += -Wa,-gdwarf-2
> > endif
> >
> > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
> > index bc74afdbf31e..dcfbd2a87d41 100644
> > --- a/arch/riscv/Makefile
> > +++ b/arch/riscv/Makefile
> > @@ -41,7 +41,7 @@ endif
> > ifeq ($(CONFIG_LD_IS_LLD),y)
> > KBUILD_CFLAGS += -mno-relax
> > KBUILD_AFLAGS += -mno-relax
> > -ifneq ($(LLVM_IAS),1)
> > +ifndef CONFIG_AS_IS_LLVM
> > KBUILD_CFLAGS += -Wa,-mno-relax
> > KBUILD_AFLAGS += -Wa,-mno-relax
> > endif
> >
--
Best Regards
Masahiro Yamada
prev parent reply other threads:[~2021-08-10 0:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-05 15:01 [PATCH] kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS Masahiro Yamada
2021-08-05 18:22 ` Nick Desaulniers
2021-08-05 18:46 ` Nathan Chancellor
2021-08-10 0:05 ` Masahiro Yamada [this message]
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