Re: [PATCH 2/4] Makefile: clang: choose GCC_TOOLCHAIN_DIR not on LD

[Nathan Chancellor <natechancellor@gmail.com>]

On Thu, Feb 07, 2019 at 02:01:50PM -0800, ndesaulniers@google.com wrote:
> This causes an issue when trying to build with `make LD=ld.lld` if
> ld.lld and the rest of your cross tools aren't in the same directory
> (ex. /usr/local/bin) (as is the case for Android's build system), as the
> GCC_TOOLCHAIN_DIR then gets set based on `which $(LD)` which will point
> where LLVM tools are, not GCC/binutils tools are located.
> 
> Instead, select the GCC_TOOLCHAIN_DIR based on another tool provided by
> binutils for which LLVM does not provide a substitute for, such as
> elfedit.
> 
> Fixes commit 785f11aa595b ("kbuild: Add better clang cross build support")
> 
> Link: https://github.com/ClangBuiltLinux/linux/issues/341
> Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>

> ---
>  Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Makefile b/Makefile
> index 3142e67d03f1..0eae4277206e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -492,7 +492,7 @@ endif
>  ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
>  ifneq ($(CROSS_COMPILE),)
>  CLANG_FLAGS	:= --target=$(notdir $(CROSS_COMPILE:%-=%))
> -GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
> +GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit))
>  CLANG_FLAGS	+= --prefix=$(GCC_TOOLCHAIN_DIR)
>  GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
>  endif
> -- 
> 2.20.1.791.gb4d0f1c61a-goog
>