linux-kernel - Re: [PATCH 0/4] nvme-pci: support device coredump

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190503121232.GB30013@localhost.localdomain>
Date:   Fri, 3 May 2019 06:12:32 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     Akinobu Mita <akinobu.mita@...il.com>
Cc:     Keith Busch <keith.busch@...el.com>,
        linux-nvme@...ts.infradead.org,
        LKML <linux-kernel@...r.kernel.org>,
        Johannes Berg <johannes@...solutions.net>,
        Jens Axboe <axboe@...com>, Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>
Subject: Re: [PATCH 0/4] nvme-pci: support device coredump

On Fri, May 03, 2019 at 12:38:08PM +0900, Akinobu Mita wrote:
> 2019年5月2日(木) 22:03 Keith Busch <keith.busch@...el.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.

Could you actually explain how the rest is useful? I personally have
never encountered an issue where knowing these values would have helped:
every device timeout always needed device specific internal firmware
logs in my experience.