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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Thu, 4 Mar 2021 21:26:43 +0900
Message-ID: <CAK7LNAS5h2s5ZDx3xOiE2upyGXtPf44f5A76YYUeM1Tk93QXNg@mail.gmail.com>
Subject: Re: [PATCH RFC] gcc-plugins: Handle GCC version mismatch for OOT modules
To:     Josh Poimboeuf <jpoimboe@redhat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Michal Marek <michal.lkml@markovi.net>,
        linux-hardening@vger.kernel.org,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Justin Forbes <jforbes@redhat.com>,
        Ondrej Mosnacek <omosnace@redhat.com>,
        Frank Eigler <fche@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
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On Thu, Mar 4, 2021 at 4:15 AM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> On Thu, Mar 04, 2021 at 03:49:35AM +0900, Masahiro Yamada wrote:
> > > This problem is becoming more prevalent.  We will need to fix it one way
> > > or another, if we want to support distro adoption of these GCC
> > > plugin-based features.
> > >
> > > Frank suggested a possibly better idea: always rebuild the plugins when
> > > the GCC version changes.
> >
> >
> > That is just another form of the previous patch,
> > which was already rejected.
> >
> >
> > - That is a hack just for external modules
> > - Our consensus is, use the same version for the kernel and external modules
> >
> >
> >
> > I use Ubuntu, and I do not see such a problem.
> > (I have never seen it on Debian either, except sid.)
> >
> > I see Fedora providing GCC whose version is different
> > from the one used for building the kernel.
> > That is a problem on the distribution side.
>
> I don't understand.  Are you suggesting that a distro should always
> release GCC and kernel updates simultaneously?

Well, as Greg says, given that GCC is less frequently upgraded
than the kernel, this should not be a big deal.

https://lore.kernel.org/lkml/YBBML2eB%2FIXcTvcn@kroah.com/


> How is this problem specific to Fedora?  Please be specific about what
> Ubuntu and Debian do, which Fedora doesn't do.

I do not know what they exactly do. Looking at only the result,
Ubuntu and Debian do proper engineering, which Fedora doesn't.


>
> Adding Linus, who indicated in another thread that we shouldn't force
> exact GCC versions because there's no technical reason to do so.
>
> --
> Josh
>


-- 
Best Regards
Masahiro Yamada