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Date: Tue, 7 Sep 2021 17:42:27 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Marco Elver <elver@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>, llvm@lists.linux.dev,
        LSM List <linux-security-module@vger.kernel.org>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Guenter Roeck <linux@roeck-us.net>, Kees Cook <keescook@chromium.org>,
        Mark Brown <broonie@kernel.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vipin Sharma <vipinsh@google.com>, Chris Down <chris@chrisdown.name>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Vlastimil Babka <vbabka@suse.cz>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Revert "Enable '-Werror' by default for all kernel builds"
Message-ID: <20210907224227.GL1583@gate.crashing.org>
References: <20210907183843.33028-1-ndesaulniers@google.com> <CAHk-=whJOxDefgSA1_ojGbweRJGonWX9_nihA-=fbXFV1DhuxQ@mail.gmail.com> <CAKwvOdkuYoke=Sa8Qziveo9aSA2zaNWEcKW8LZLg+d3TPwHkoA@mail.gmail.com> <YTfkO2PdnBXQXvsm@elver.google.com>
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On Wed, Sep 08, 2021 at 12:14:19AM +0200, Marco Elver wrote:
> Here's a datapoint: I had to disable CONFIG_WERROR on a bunch of syzbot
> instances which started failing because of -Werror [1], because syzbot's
> time is better spent on fuzzing, and having the odd warning in some
> subsystem penalize fuzzing of the entire kernel is not appropriate.

Similarly, I have to disable -Werror (which various archs and subsystems
already use) whenever I test building the kernel with new toolchains.
It is the biggest set of kernel patches I keep, already, since many
years.

I actually have good hopes that a centralised -Werror thing will make
this easier :-)

Maybe there can be an E=[01] kernel build flag to disable / enable
CONFIG_WERROR?  Something that will override it for just that command.
This would make life easier for many use cases, while at the same time
not being something that people can "forget" they did.


Segher