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Date: Thu, 26 Feb 2026 14:45:58 -0700
From: Nathan Chancellor <nathan@kernel.org>
To: Thomas =?iso-8859-1?Q?Wei=DFschuh?= <linux@weissschuh.net>
Cc: Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	Nicolas Schier <nsc@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
	Shuah Khan <skhan@linuxfoundation.org>, llvm@lists.linux.dev,
	linux-kbuild@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] tools/build: Reject unexpected values for LLVM=
Message-ID: <20260226214558.GB1534917@ax162>
References: <20260226-kbuild-llvm-followup-v1-0-201cc2a492d9@weissschuh.net>
 <20260226-kbuild-llvm-followup-v1-2-201cc2a492d9@weissschuh.net>
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In-Reply-To: <20260226-kbuild-llvm-followup-v1-2-201cc2a492d9@weissschuh.net>

On Thu, Feb 26, 2026 at 10:23:58PM +0100, Thomas Weißschuh wrote:
> Since commit 502678b88cb3 ("kbuild: Reject unexpected values for LLVM=")
> the regular kbuild rejects unexpected values of LLVM=1 instead of
> silently treating them as LLVM=1.
> 
> Align the tools build to kbuild.
> 
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> 
> ---
> There is no formal maintainer for this file.
> IMO this change should go through kbuild.

Ironically I just rejected a tools/ patch going through Kbuild:

  https://lore.kernel.org/20260225192505.GC2755225@ax162/

but since there is no formal maintainer, it is the same change done in
Kbuild, and the risk of fallout is much less than that change, I think
we can make an exception and take it.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
>  tools/scripts/Makefile.include | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
> index b5ecf137febc..41971a68972d 100644
> --- a/tools/scripts/Makefile.include
> +++ b/tools/scripts/Makefile.include
> @@ -56,6 +56,8 @@ ifneq ($(filter %/,$(LLVM)),)
>  LLVM_PREFIX := $(LLVM)
>  else ifneq ($(filter -%,$(LLVM)),)
>  LLVM_SUFFIX := $(LLVM)
> +else ifneq ($(LLVM),1)
> +$(error Invalid value for LLVM, see Documentation/kbuild/llvm.rst)
>  endif
>  
>  $(call allow-override,CC,$(LLVM_PREFIX)clang$(LLVM_SUFFIX))
> 
> -- 
> 2.53.0
>