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Date:   Tue, 15 Mar 2022 01:42:44 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Sagi Grimberg <sagi@grimberg.me>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Hannes Reinecke <hare@suse.de>,
        Bart Van Assche <bvanassche@acm.org>,
        Mike Christie <michael.christie@oracle.com>,
        Gabriel Krisman Bertazi <krisman@collabora.com>,
        lsf-pc@lists.linux-foundation.org, linux-block@vger.kernel.org
Subject: Re: [LSF/MM/BPF TOPIC] block drivers in user space
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On Tue, Mar 15, 2022 at 10:38:24AM +0200, Sagi Grimberg wrote:
> 
> > FYI, I have absolutely no interest in supporting any userspace hooks
> > in nvmet.
> 
> Don't think we are discussing adding anything specific to nvmet, a
> userspace backend will most likely sit behind a block device exported
> via nvmet (at least from my perspective). Although I do see issues
> with using the passthru interface...

Well, anything that is properly hidden behind the block device
infrastructure does not matter for nvmet.  But that interface does
not support passthrough.  Anyone who wants to handle raw nvme commands
in userspace should not use nvmet.