Re: [PATCH v6 2/3] Makefile: infer --target from ARCH for CC=clang

[Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>]

On Mon, Aug 2, 2021 at 8:39 PM 'Nick Desaulniers' via Clang Built
Linux <clang-built-linux@googlegroups.com> wrote:
>
> We get constant feedback that the command line invocation of make is too
> long when compiling with LLVM. CROSS_COMPILE is helpful when a toolchain
> has a prefix of the target triple, or is an absolute path outside of
> $PATH.
>
> Since a Clang binary is generally multi-targeted, we can infer a given
> target from SRCARCH/ARCH.  If CROSS_COMPILE is not set, simply set
> --target= for CLANG_FLAGS, KBUILD_CFLAGS, and KBUILD_AFLAGS based on
> $SRCARCH.
>
> Previously, we'd cross compile via:
> $ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make LLVM=1 LLVM_IAS=1
> Now:
> $ ARCH=arm64 make LLVM=1 LLVM_IAS=1
>
> For native builds (not involving cross compilation) we now explicitly
> specify a target triple rather than rely on the implicit host triple.
>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1399
> Suggested-by: Arnd Bergmann <arnd@kernel.org>
> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
> Suggested-by: Nathan Chancellor <nathan@kernel.org>
> Acked-by: Arnd Bergmann <arnd@kernel.org>
> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>

Acked-by: Miguel Ojeda <ojeda@kernel.org>

Cheers,
Miguel