From: Nathan Chancellor <nathan@kernel.org>
To: Masahiro Yamada <masahiroy@kernel.org>, linux-kbuild@vger.kernel.org
Cc: 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@googlegroups.com, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org
Subject: Re: [PATCH] kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS
Date: Thu, 5 Aug 2021 11:46:10 -0700 [thread overview]
Message-ID: <59ce441e-8deb-39ff-700f-4e1c4e871177@kernel.org> (raw)
In-Reply-To: <20210805150102.131008-1-masahiroy@kernel.org>
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
> $(CC) is clang.
>
> Of course, the combination of CC=gcc and LLVM_IAS=1 does not make
> sense, but the build system can be more robust against such insane
> input.
>
> Commit ba64beb17493a ("kbuild: check the minimum assembler version in
> Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
> because Kconfig checks the version string from the assembler in use.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> ---
>
> Makefile | 2 +-
> arch/riscv/Makefile | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 4ab151060931..8b56c9692c3c 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -844,7 +844,7 @@ else
> DEBUG_CFLAGS += -g
> endif
>
> -ifneq ($(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
>
next prev parent reply other threads:[~2021-08-05 18:46 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 [this message]
2021-08-10 0:05 ` Masahiro Yamada
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