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From: Masahiro Yamada <>
Cc: Masahiro Yamada <>,
	Albert Ou <>,
	Michal Marek <>,
	Nathan Chancellor <>,
	Nick Desaulniers <>,
	Palmer Dabbelt <>,
	Paul Walmsley <>,,,
Subject: [PATCH] kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS
Date: Fri,  6 Aug 2021 00:01:02 +0900	[thread overview]
Message-ID: <> (raw)

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

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 <>

 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
-ifneq ($(LLVM_IAS),1)
 KBUILD_AFLAGS	+= -Wa,-gdwarf-2
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index bc74afdbf31e..dcfbd2a87d41 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -41,7 +41,7 @@ endif
 ifeq ($(CONFIG_LD_IS_LLD),y)
 	KBUILD_CFLAGS += -mno-relax
 	KBUILD_AFLAGS += -mno-relax
-ifneq ($(LLVM_IAS),1)
 	KBUILD_CFLAGS += -Wa,-mno-relax
 	KBUILD_AFLAGS += -Wa,-mno-relax

             reply	other threads:[~2021-08-05 15:02 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05 15:01 Masahiro Yamada [this message]
2021-08-05 18:22 ` [PATCH] kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS Nick Desaulniers
2021-08-05 18:46 ` Nathan Chancellor
2021-08-10  0:05   ` Masahiro Yamada

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