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Date:   Mon, 13 Sep 2021 11:46:13 +0200
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Randy Dunlap <rdunlap@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Marco Elver <elver@google.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        llvm@lists.linux.dev,
        LSM List <linux-security-module@vger.kernel.org>,
        linux-toolchains@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
        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"
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On Mon, Sep 13, 2021 at 11:32:56AM +0200, Pavel Machek wrote:
> Hi!
> 
> > >>  config WERROR
> > >>         bool "Compile the kernel with warnings as errors"
> > >>-       default y
> > >>+       default COMPILE_TEST
> > >
> > >That seems reasonable. It very much is about build-testing.
> > 
> > That and 2 more things IMO:
> > 
> > a. having developers be responsible for build warnings, not just
> >    build errors
> > 
> > b. having maintainers merge them more like they are build errors
> >    and not just some warnings that can be overlooked.
> > 
> > I don't see enough of a. or b.  :(
> 
> Do we really want developers treat warnings as errors? When the code
> is okay but some random version of gcc dislikes it...
> 
> Plus, there's question of stable. We already get ton of churn there
> ("this fixes random warning"). WERROR will only encourage that...

I will not be backporting this patch to older stable kernels, but I
_want_ to see stable builds build with no warnings.  When we add
warnings, they are almost always things we need to fix up properly.

Over time, I have worked to reduce the number of build warnings in older
stable kernels.  For newer versions of gcc, sometimes that is
impossible, but we are close...

thanks,

greg k-h