This flag was originally added to allow clang to find the GNU cross
tools in commit
785f11aa595b ("kbuild: Add better clang cross build
support"). This flag was not enough to find the tools at times so
'--prefix' was added to the list in commit
ef8c4ed9db80 ("kbuild: allow
to use GCC toolchain not in Clang search path") and improved upon in
commit
ca9b31f6bb9c ("Makefile: Fix GCC_TOOLCHAIN_DIR prefix for Clang
cross compilation"). Now that '--prefix' specifies a full path and
prefix, '--gcc-toolchain' serves no purpose because the kernel builds
with '-nostdinc' and '-nostdlib'.
This has been verified with self compiled LLVM 10.0.1 and LLVM 13.0.0 as
well as a distribution version of LLVM 11.1.0 without binutils in the
LLVM toolchain locations.
Link: https://reviews.llvm.org/D97902
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE))
-GCC_TOOLCHAIN := $(realpath $(GCC_TOOLCHAIN_DIR)/..)
-endif
-ifneq ($(GCC_TOOLCHAIN),)
-CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN)
endif
ifneq ($(LLVM_IAS),1)
CLANG_FLAGS += -no-integrated-as