| Message ID | 20190729091517.5334-1-yamada.masahiro@socionext.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kbuild: initialize CLANG_FLAGS correctly in the top Makefile | expand |
On Mon, Jul 29, 2019 at 6:16 PM Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > CLANG_FLAGS is initialized by the following line: > > CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) > > ..., which is run only when CROSS_COMPILE is set. > > Some build targets (bindeb-pkg etc.) recurse to the top Makefile. > > When you build the kernel with Clang but without CROSS_COMPILE, > the same compiler flags such as -no-integrated-as are accumulated > into CLANG_FLAGS. > > If you run 'make CC=clang' and then 'make CC=clang bindeb-pkg', > Kbuild will recompile everything needlessly due to the build command > change. > > Fix this by correctly initializing CLANG_FLAGS. > > Fixes: 238bcbc4e07f ("kbuild: consolidate Clang compiler flags") > Cc: <stable@vger.kernel.org> # v4.20+ This should be v5.0+ > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > ---
On Mon, Jul 29, 2019 at 06:15:17PM +0900, Masahiro Yamada wrote: > CLANG_FLAGS is initialized by the following line: > > CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) > > ..., which is run only when CROSS_COMPILE is set. > > Some build targets (bindeb-pkg etc.) recurse to the top Makefile. > > When you build the kernel with Clang but without CROSS_COMPILE, > the same compiler flags such as -no-integrated-as are accumulated > into CLANG_FLAGS. > > If you run 'make CC=clang' and then 'make CC=clang bindeb-pkg', > Kbuild will recompile everything needlessly due to the build command > change. > > Fix this by correctly initializing CLANG_FLAGS. > > Fixes: 238bcbc4e07f ("kbuild: consolidate Clang compiler flags") > Cc: <stable@vger.kernel.org> # v4.20+ > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
On Mon, Jul 29, 2019 at 9:04 AM Nathan Chancellor <natechancellor@gmail.com> wrote: > > On Mon, Jul 29, 2019 at 06:15:17PM +0900, Masahiro Yamada wrote: > > CLANG_FLAGS is initialized by the following line: > > > > CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) > > > > ..., which is run only when CROSS_COMPILE is set. > > > > Some build targets (bindeb-pkg etc.) recurse to the top Makefile. > > > > When you build the kernel with Clang but without CROSS_COMPILE, > > the same compiler flags such as -no-integrated-as are accumulated > > into CLANG_FLAGS. > > > > If you run 'make CC=clang' and then 'make CC=clang bindeb-pkg', > > Kbuild will recompile everything needlessly due to the build command > > change. > > > > Fix this by correctly initializing CLANG_FLAGS. > > > > Fixes: 238bcbc4e07f ("kbuild: consolidate Clang compiler flags") > > Cc: <stable@vger.kernel.org> # v4.20+ > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Acked-by: Nick Desaulniers <ndesaulniers@google.com>
On Mon, Jul 29, 2019 at 6:16 PM Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > CLANG_FLAGS is initialized by the following line: > > CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) > > ..., which is run only when CROSS_COMPILE is set. > > Some build targets (bindeb-pkg etc.) recurse to the top Makefile. > > When you build the kernel with Clang but without CROSS_COMPILE, > the same compiler flags such as -no-integrated-as are accumulated > into CLANG_FLAGS. > > If you run 'make CC=clang' and then 'make CC=clang bindeb-pkg', > Kbuild will recompile everything needlessly due to the build command > change. > > Fix this by correctly initializing CLANG_FLAGS. > > Fixes: 238bcbc4e07f ("kbuild: consolidate Clang compiler flags") > Cc: <stable@vger.kernel.org> # v4.20+ > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > --- Applied to linux-kbuild. > > Makefile | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/Makefile b/Makefile > index fa0fbe7851ea..5ee6f6889869 100644 > --- a/Makefile > +++ b/Makefile > @@ -472,6 +472,7 @@ KBUILD_CFLAGS_MODULE := -DMODULE > KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds > KBUILD_LDFLAGS := > GCC_PLUGINS_CFLAGS := > +CLANG_FLAGS := > > export ARCH SRCARCH CONFIG_SHELL HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC > export CPP AR NM STRIP OBJCOPY OBJDUMP PAHOLE KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS > @@ -519,7 +520,7 @@ endif > > ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),) > ifneq ($(CROSS_COMPILE),) > -CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) > +CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) > GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) > CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR) > GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) > -- > 2.17.1 >
diff --git a/Makefile b/Makefile index fa0fbe7851ea..5ee6f6889869 100644 --- a/Makefile +++ b/Makefile @@ -472,6 +472,7 @@ KBUILD_CFLAGS_MODULE := -DMODULE KBUILD_LDFLAGS_MODULE := -T $(srctree)/scripts/module-common.lds KBUILD_LDFLAGS := GCC_PLUGINS_CFLAGS := +CLANG_FLAGS := export ARCH SRCARCH CONFIG_SHELL HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE AS LD CC export CPP AR NM STRIP OBJCOPY OBJDUMP PAHOLE KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS @@ -519,7 +520,7 @@ endif ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),) ifneq ($(CROSS_COMPILE),) -CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) +CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR) GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
CLANG_FLAGS is initialized by the following line: CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%)) ..., which is run only when CROSS_COMPILE is set. Some build targets (bindeb-pkg etc.) recurse to the top Makefile. When you build the kernel with Clang but without CROSS_COMPILE, the same compiler flags such as -no-integrated-as are accumulated into CLANG_FLAGS. If you run 'make CC=clang' and then 'make CC=clang bindeb-pkg', Kbuild will recompile everything needlessly due to the build command change. Fix this by correctly initializing CLANG_FLAGS. Fixes: 238bcbc4e07f ("kbuild: consolidate Clang compiler flags") Cc: <stable@vger.kernel.org> # v4.20+ Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)