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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Mon, 30 Nov 2020 12:12:39 -0800
Message-ID: <CAKwvOdmfEY6fnNFUUzLvN9bKyeTt7OMc-Uvx=YqTuMR2BuD5XA@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:     Naresh Kamboju <naresh.kamboju@linaro.org>,
        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 Wed, Nov 25, 2020 at 10:38 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> Is the mainline 4.9 tree supposed to work with clang?  I didn't think
> that upstream effort started until 4.19 or so.

(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,
~Nick Desaulniers