| Message ID | 20210805150102.131008-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS | expand |
On Thu, Aug 5, 2021 at 8:01 AM Masahiro Yamada <masahiroy@kernel.org> 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 > $(CC) is clang. > > Of course, the combination of CC=gcc and LLVM_IAS=1 does not make > sense, but the build system can be more robust against such insane > input. > > Commit ba64beb17493a ("kbuild: check the minimum assembler version in > Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise > because Kconfig checks the version string from the assembler in use. > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > --- > > Makefile | 2 +- > arch/riscv/Makefile | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/Makefile b/Makefile > index 4ab151060931..8b56c9692c3c 100644 > --- a/Makefile > +++ b/Makefile > @@ -844,7 +844,7 @@ else > DEBUG_CFLAGS += -g > endif > > -ifneq ($(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 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 >
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 > >
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
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> --- Makefile | 2 +- arch/riscv/Makefile | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)