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Message-ID: <bfbc7352951d1adc714f699acb49e298c24fe7e3.camel@kernel.crashing.org>
Subject: Re: [PATCH 2/3] nvme: Retrieve the required IO queue entry size
 from the controller
From:   Benjamin Herrenschmidt <benh@kernel.crashing.org>
To:     Christoph Hellwig <hch@lst.de>
Cc:     linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
        Jens Axboe <axboe@fb.com>, Keith Busch <kbusch@kernel.org>,
        Paul Pawlowski <paul@mrarm.io>
Date:   Tue, 16 Jul 2019 20:58:28 +1000
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         <ad18ff8d004225e102076f8e1fb617916617f337.camel@kernel.crashing.org>
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On Tue, 2019-07-16 at 11:33 +0200, Christoph Hellwig wrote:
> > >    So back to the version
> > > you circulated to me in private mail that just sets q->sqes and has a
> > > comment that this is magic for The Apple controller.  If/when we get
> > > standardized large SQE support we'll need to discover that earlier or
> > > do a disable/enable dance.  Sorry for misleading you down this road and
> > > creating the extra work.  
> > 
> > I think it's still ok, let me know...
> 
> Ok, let's go with this series then unless the other maintainers have
> objections.
> 
> I'm still not sure if we want to queue this up for 5.3 (new hardware
> enablement) or wait a bit, though.

The main risk is if existing controllers return crap in SQES and we try
to then use that crap. The rest should essentially be NOPs.

Maybe I should add some kind of printk to warn in case we use/detect a
non-standard size. That would help diagnosing issues.

Cheers,
Ben.