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From:   Naresh Kamboju <naresh.kamboju@linaro.org>
Date:   Tue, 1 Dec 2020 14:31:52 +0530
Message-ID: <CA+G9fYtWappsU-njZx87ZJVxmTHOr1zUNE_q=k0Dz5cW16rBkQ@mail.gmail.com>
Subject: Re: [stable 4.9] PANIC: double fault, error_code: 0x0 - clang boot
 failed on x86_64
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        linux-stable <stable@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        lkft-triage@lists.linaro.org, Sasha Levin <sashal@kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        x86@vger.kernel.org, Matthias Kaehlcke <mka@chromium.org>
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On Tue, 1 Dec 2020 at 13:49, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Nov 30, 2020 at 12:12:39PM -0800, Nick Desaulniers wrote:
> >
> > (For historical records, separate from the initial bug report that
> > started this thread)
> >
> > I consider 785f11aa595b ("kbuild: Add better clang cross build
> > support") to be the starting point of a renewed effort to upstream
> > clang support. 785f11aa595b landed in v4.12-rc1.  I think most patches
> > landed between there and 4.15 (would have been my guess).  From there,
> > support was backported to 4.14, 4.9, and 4.4 for x86_64 and aarch64.
> > We still have CI coverage of those branches+arches with Clang today.
> > Pixel 2 shipped with 4.4+clang, Pixel 3 and 3a with 4.9+clang, Pixel 4
> > and 4a with 4.14+clang.  CrOS has also shipped clang built kernels
> > since 4.4+.
>
> Thanks for the info.  Naresh, does this help explain why maybe testing
> these kernel branches with clang might not be the best thing to do?

It is clear now.

FYI,
With this note LKFT will not test 4.14+clang and old branches.

- Naresh