linux-kernel - Re: [PATCH v2] kbuild: userprogs: use correct linker when mixing clang and GNU ld

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Message-ID: <CAK7LNATXk1xKrCXmdV1jEgtgxGxPvTRr8V=pWczKD++da3N+3g@mail.gmail.com>
Date: Tue, 29 Jul 2025 22:49:28 +0900
From: Masahiro Yamada <masahiroy@...nel.org>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Cc: Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas.schier@...ux.dev>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, linux-kbuild@...r.kernel.org, 
	linux-kernel@...r.kernel.org, llvm@...ts.linux.dev, stable@...r.kernel.org
Subject: Re: [PATCH v2] kbuild: userprogs: use correct linker when mixing
 clang and GNU ld

On Mon, Jul 28, 2025 at 10:50 PM Thomas Weißschuh
<thomas.weissschuh@...utronix.de> wrote:
>
> The userprogs infrastructure does not expect clang being used with GNU ld
> and in that case uses /usr/bin/ld for linking, not the configured $(LD).
> This fallback is problematic as it will break when cross-compiling.
> Mixing clang and GNU ld is used for example when building for SPARC64,
> as ld.lld is not sufficient; see Documentation/kbuild/llvm.rst.
>
> Relax the check around --ld-path so it gets used for all linkers.
>
> Fixes: dfc1b168a8c4 ("kbuild: userprogs: use correct lld when linking through clang")
> Cc: stable@...r.kernel.org
> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
> Reviewed-by: Nathan Chancellor <nathan@...nel.org>
> ---

Applied to linux-kbuild.
Thanks.


> Changes in v2:
> - Use plain ifdef instead of ifneq
> - Rebase onto v6.16
> - Pick up review tag from Nathan
> - Link to v1: https://lore.kernel.org/r/20250724-userprogs-clang-gnu-ld-v1-1-3d3d071e53a7@linutronix.de
> ---
>  Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 478f2004602da03c9039044e3288f24a13833cc7..7d24245d118c0e903119263b871d2e5c2759f48a 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1134,7 +1134,7 @@ KBUILD_USERCFLAGS  += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD
>  KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
>
>  # userspace programs are linked via the compiler, use the correct linker
> -ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_LD_IS_LLD),yy)
> +ifdef CONFIG_CC_IS_CLANG
>  KBUILD_USERLDFLAGS += --ld-path=$(LD)
>  endif
>
>
> ---
> base-commit: 038d61fd642278bab63ee8ef722c50d10ab01e8f
> change-id: 20250723-userprogs-clang-gnu-ld-7a1c16fc852d
>
> Best regards,
> --
> Thomas Weißschuh <thomas.weissschuh@...utronix.de>
>


-- 
Best Regards
Masahiro Yamada