Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 2 Mar 2022 10:40:43 -0800
From:   Kees Cook <keescook@chromium.org>
To:     Nathan Chancellor <nathan@kernel.org>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Peter Zijlstra <peterz@infradead.org>, x86@kernel.org,
        joao@overdrivepizza.com, hjl.tools@gmail.com, jpoimboe@redhat.com,
        andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org,
        samitolvanen@google.com, mark.rutland@arm.com,
        alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org,
        mhiramat@kernel.org, alexei.starovoitov@gmail.com,
        Masahiro Yamada <masahiroy@kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        llvm@lists.linux.dev
Subject: Re: [PATCH v2 01/39] kbuild: Fix clang build
Message-ID: <202203021039.0DF89D3F2C@keescook>
References: <20220224145138.952963315@infradead.org>
 <20220224151322.072632223@infradead.org>
 <CAKwvOdkD2WY=hEHy8_0zs70AGx6LRQwxL5mEZyB30uqpruYJyA@mail.gmail.com>
 <Yh+dMJsH+ZMPfqwD@thelio-3990X>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Yh+dMJsH+ZMPfqwD@thelio-3990X>
Precedence: bulk

On Wed, Mar 02, 2022 at 09:37:04AM -0700, Nathan Chancellor wrote:
> However, I think we could still address Peter's complaint of "there
> should be an easier way for me to use the tools that are already in my
> PATH" with his first iteration of this patch [1], which I feel is
> totally reasonable:
> 
> $ make LLVM=-14
> 
> It is still easy to use (in fact, it is shorter than 'CC=clang-14') and
> it does not change anything else about how we build with LLVM. We would
> just have to add something along the lines of
> 
> "If your LLVM tools have a suffix like Debian's (clang-14, ld.lld-14,
> etc.), use LLVM=<suffix>.
> 
> $ make LLVM=-14"
> 
> to Documentation/kbuild/llvm.rst.
> 
> I might change the patch not to be so clever though:
> 
> ifneq ($(LLVM),)
> ifneq ($(LLVM),1)
> LLVM_SFX := $(LLVM)
> endif
> endif

I like this idea! I think it's much easier to control than PATH (though
I see the rationale there too).

-- 
Kees Cook