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
$(CC) is clang.
Of course, the combination of CC=gcc and LLVM_IAS=1 does not make
sense, but the build system can be more robust against such insane
input.
Commit ba64beb17493a ("kbuild: check the minimum assembler version in
Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
because Kconfig checks the version string from the assembler in use.
Signed-off-by: Masahiro Yamada <[email protected]>
---
Makefile | 2 +-
arch/riscv/Makefile | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/Makefile b/Makefile
index 4ab151060931..8b56c9692c3c 100644
--- a/Makefile
+++ b/Makefile
@@ -844,7 +844,7 @@ else
DEBUG_CFLAGS += -g
endif
-ifneq ($(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
--
2.30.2
On Thu, Aug 5, 2021 at 8:01 AM Masahiro Yamada <[email protected]> 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
> $(CC) is clang.
>
> Of course, the combination of CC=gcc and LLVM_IAS=1 does not make
> sense, but the build system can be more robust against such insane
> input.
>
> Commit ba64beb17493a ("kbuild: check the minimum assembler version in
> Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
> because Kconfig checks the version string from the assembler in use.
>
> Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nick Desaulniers <[email protected]>
> ---
>
> Makefile | 2 +-
> arch/riscv/Makefile | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 4ab151060931..8b56c9692c3c 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -844,7 +844,7 @@ else
> DEBUG_CFLAGS += -g
> endif
>
> -ifneq ($(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
> --
> 2.30.2
>
--
Thanks,
~Nick Desaulniers
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
> $(CC) is clang.
>
> Of course, the combination of CC=gcc and LLVM_IAS=1 does not make
> sense, but the build system can be more robust against such insane
> input.
>
> Commit ba64beb17493a ("kbuild: check the minimum assembler version in
> Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
> because Kconfig checks the version string from the assembler in use.
>
> Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
> ---
>
> Makefile | 2 +-
> arch/riscv/Makefile | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 4ab151060931..8b56c9692c3c 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -844,7 +844,7 @@ else
> DEBUG_CFLAGS += -g
> endif
>
> -ifneq ($(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
>
On Fri, Aug 6, 2021 at 3:46 AM Nathan Chancellor <[email protected]> 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
> > $(CC) is clang.
> >
> > Of course, the combination of CC=gcc and LLVM_IAS=1 does not make
> > sense, but the build system can be more robust against such insane
> > input.
> >
> > Commit ba64beb17493a ("kbuild: check the minimum assembler version in
> > Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
> > because Kconfig checks the version string from the assembler in use.
> >
> > Signed-off-by: Masahiro Yamada <[email protected]>
>
> Reviewed-by: Nathan Chancellor <[email protected]>
Applied to linux-kbuild.
> > ---
> >
> > Makefile | 2 +-
> > arch/riscv/Makefile | 2 +-
> > 2 files changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/Makefile b/Makefile
> > index 4ab151060931..8b56c9692c3c 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -844,7 +844,7 @@ else
> > DEBUG_CFLAGS += -g
> > endif
> >
> > -ifneq ($(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