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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Thu, 28 Apr 2022 09:04:34 +0200
Message-ID: <CAK8P3a2aHBxRJbOcXBGM7gjAqpErBAeaG3NmfgBTn4TNYscSgw@mail.gmail.com>
Subject: Re: [PATCH v3 1/1] soc: fujitsu: Add A64FX diagnostic interrupt driver
To:     "hasegawa-hitomi@fujitsu.com" <hasegawa-hitomi@fujitsu.com>
Cc:     Daniel Thompson <daniel.thompson@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        SoC Team <soc@kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
        Sumit Garg <sumit.garg@linaro.org>,
        Olof Johansson <olof@lixom.net>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Jason Wessel <jason.wessel@windriver.com>,
        Doug Anderson <dianders@chromium.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "kgdb-bugreport@lists.sourceforge.net" 
        <kgdb-bugreport@lists.sourceforge.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Mike Travis <mike.travis@hpe.com>
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On Thu, Apr 28, 2022 at 4:15 AM hasegawa-hitomi@fujitsu.com
<hasegawa-hitomi@fujitsu.com> wrote:
>
> Hi Greg, Arnd, and Daniel,
>
> > I understand that it is not appropriate to hardcode c.
> > How about using __setup() to add a new kernel parameter and allow the admin
> > to specify the sysrq command when booting?
>
> I have received a lot of advice regarding sysrq, but after some consideration,
> I would like to change to calling panic() directly as in v1 instead of sysrq.
>
> If the administrator wants to request a diagnostic, I think they usually
> expect crash with NMI like x86 and take a dump the kernel. It's not common
> to handle diagnostic interrupts with sysrq now, so I don't think
> it's necessary to make this driver extensible at this time.

Ok, fair enough. Matching x86 behavior sounds like a reasonable outcome.
If we want to make this configurable in the future, that can still be done then,
and it should work the same across architectures but adding the logic
in nmi_panic() directly.

        Arnd