On Mon, Nov 5, 2018 at 1:19 AM Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > On Mon, Nov 5, 2018 at 6:10 PM Stefan Agner <stefan@xxxxxxxx> wrote: > > > > On 05.11.2018 03:48, Masahiro Yamada wrote: > > > Add basic options for Clang such as --target, --prefix, --gcc-toolchain, > > > -no-integrated-as to a single variable CLANG_FLAGS. > > > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> > > > --- > > > > > > Makefile | 13 ++++++------- > > > 1 file changed, 6 insertions(+), 7 deletions(-) > > > > > > diff --git a/Makefile b/Makefile > > > index 93315eb..58c838a 100644 > > > --- a/Makefile > > > +++ b/Makefile > > > @@ -487,18 +487,17 @@ endif > > > > > > ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),) > > > ifneq ($(CROSS_COMPILE),) > > > -CLANG_TARGET := --target=$(notdir $(CROSS_COMPILE:%-=%)) > > > +CLANG_FLAGS = --target=$(notdir $(CROSS_COMPILE:%-=%)) > > > GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD))) > > > -CLANG_PREFIX := --prefix=$(GCC_TOOLCHAIN_DIR) > > > +CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR) > > > > So this will expand later now, is this ok? > > > > -- > > Stefan > > > > > GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..) > > > endif > > > ifneq ($(GCC_TOOLCHAIN),) > > > -CLANG_GCC_TC := --gcc-toolchain=$(GCC_TOOLCHAIN) > > > +CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN) > > > endif > > > -KBUILD_CFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX) > > > -KBUILD_AFLAGS += $(CLANG_TARGET) $(CLANG_GCC_TC) $(CLANG_PREFIX) > > > -KBUILD_CFLAGS += $(call cc-option, -no-integrated-as) > > > -KBUILD_AFLAGS += $(call cc-option, -no-integrated-as) > > > +CLANG_FLAGS += $(call cc-option, -no-integrated-as) > > > +KBUILD_CFLAGS += $(CLANG_FLAGS) > > > +KBUILD_AFLAGS += $(CLANG_FLAGS) > > > CLANG_FLAGS is expanded here because KBUILD_CFLAGS and KBUILD_AFLAGS > are defined by using := > > So, it should be OK, but turning CLANG_FLAGS into a simple variable > will be a little more efficient since $(call cc-option, -no-integrated-as) > is evaluated just once. > > (Or, this cc-option may not be necessary any longer.) > > Will send v2. If the ultimate goal is not evaluate cc-option more than once, removing cc-option from both KBUILD_CFLAGS and KBUILD_AFLAGS for clang is the better approach; we always want those for clang unconditionally. And if you by chance have an ancient version of clang that doesn't support those flags, you wont be able to compile a kernel anyways. Eventually we want to get Clang's integrated assembler in shape to be used to assemble the kernel, but I think we're a ways off there still. -- Thanks, ~Nick Desaulniers
