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From:   Akinobu Mita <akinobu.mita@gmail.com>
Date:   Fri, 3 May 2019 12:38:08 +0900
Message-ID: <CAC5umygdADGrYeJy=F53Mm4bNPHmo+WY4SD3HFSRqi_cLrz9jw@mail.gmail.com>
Subject: Re: [PATCH 0/4] nvme-pci: support device coredump
To:     Keith Busch <keith.busch@intel.com>
Cc:     linux-nvme@lists.infradead.org,
        LKML <linux-kernel@vger.kernel.org>,
        Johannes Berg <johannes@sipsolutions.net>,
        Jens Axboe <axboe@fb.com>, Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>
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2019=E5=B9=B45=E6=9C=882=E6=97=A5(=E6=9C=A8) 22:03 Keith Busch <keith.busch=
@intel.com>:
>
> On Thu, May 02, 2019 at 05:59:17PM +0900, Akinobu Mita wrote:
> > This enables to capture snapshot of controller information via device
> > coredump machanism, and it helps diagnose and debug issues.
> >
> > The nvme device coredump is triggered before resetting the controller
> > caused by I/O timeout, and creates the following coredump files.
> >
> > - regs: NVMe controller registers, including each I/O queue doorbell
> >         registers, in nvme-show-regs style text format.
>
> You're supposed to treat queue doorbells as write-only. Spec says:
>
>   The host should not read the doorbell registers. If a doorbell register
>   is read, the value returned is vendor specific.

OK.  I'll exclude the doorbell registers from register dump.  It will work
out without the information if we have snapshot of the queues.