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[209.85.208.180]) by smtp.gmail.com with ESMTPSA id k6sm2630562lfm.89.2020.07.10.15.31.17 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jul 2020 15:31:17 -0700 (PDT) Received: by mail-lj1-f180.google.com with SMTP id 9so8105336ljv.5 for ; Fri, 10 Jul 2020 15:31:17 -0700 (PDT) X-Received: by 2002:a05:651c:1b6:: with SMTP id c22mr36364030ljn.421.1594420276931; Fri, 10 Jul 2020 15:31:16 -0700 (PDT) MIME-Version: 1.0 References: <20200709221102.323356-1-cesarb@cesarb.eti.br> In-Reply-To: From: Linus Torvalds Date: Fri, 10 Jul 2020 15:31:00 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] Restore gcc check in mips asm/unroll.h To: Nick Desaulniers Cc: Cesar Eduardo Barros , Linux Kernel Mailing List , Steven Rostedt , Masahiro Yamada Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 10, 2020 at 11:43 AM Nick Desaulniers wrote: > > What I'd really like to see as a policy in the kernel going forward in > that ANY new commit that adds some hack or workaround for a specific > compiler version add a comment about which toolchain version was > problematic, that way when we drop support for that version years > later, we can drop whatever hacks and technical debt we've accumulated > to support that older version. The problem is that at the time we find and fix things, it's often _very_ unclear which compiler versions are affected. We also have the situation that a lot of distro compilers aren't necessarily completely "clean" versions, particularly for the "enterprise" ones that get stuck on some old version and then fix up their breakage by backporting fixes. When it's some particular version of a compiler that supports a particular feature, that tends to be much more straightforward. But we've had bugs where it was very unclear when exactly the bug was fixed (fi it was fixed at all by the time we do the workaround). Linus