[PATCH 01/15] kbuild: add ld-name macro and support for GNU gold

[Nick Desaulniers]

+ Kbuild mailing list and maintainers

The use of these ternary like operations will need to be expanded if
additional compilers come along (less likely), or additional linkers
(more likely, we are looking into lld right now) but we can cross that
bridge when we get there.

Reviewed-by: Nick Desaulniers <ndesaulniers at google.com>

On Fri, Nov 3, 2017 at 10:11 AM, Sami Tolvanen <samitolvanen at google.com> wrote:
> GNU gold may require different flags than GNU ld. Add a macro for
> detecting the linker and conditionally add gold specific flags from
> LDFLAGS_GOLD.
>
> Signed-off-by: Sami Tolvanen <samitolvanen at google.com>
> ---
>  Makefile               | 5 +++++
>  scripts/Kbuild.include | 4 ++++
>  2 files changed, 9 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 3a8868ee967e..59980d5a03d0 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -826,6 +826,11 @@ include scripts/Makefile.kasan
>  include scripts/Makefile.extrawarn
>  include scripts/Makefile.ubsan
>
> +# Add any flags specific to ld.gold
> +ifeq ($(ld-name),gold)
> +LDFLAGS                += $(LDFLAGS_GOLD)
> +endif
> +
>  # Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
>  # last assignments
>  KBUILD_CPPFLAGS += $(ARCH_CPPFLAGS) $(KCPPFLAGS)
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index 9ffd3dda3889..584d6cecd7c0 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -172,6 +172,10 @@ ld-option = $(call try-run,\
>  # Important: no spaces around options
>  ar-option = $(call try-run, $(AR) rc$(1) "$$TMP",$(1),$(2))
>
> +# ld-name
> +# Expands to either bfd or gold
> +ld-name = $(shell $(LD) -v 2>&1 | grep -q "GNU gold" && echo gold || echo bfd)
> +
>  # ld-version
>  # Note this is mainly for HJ Lu's 3 number binutil versions
>  ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh)
> --
> 2.15.0.403.gc27cc4dac6-goog
>



-- 
Thanks,
~Nick Desaulniers