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Date:   Thu, 9 May 2019 07:49:17 -0600
From:   Keith Busch <kbusch@kernel.org>
To:     Stefan Hajnoczi <stefanha@gmail.com>
Cc:     Maxim Levitsky <mlevitsk@redhat.com>,
        Christoph Hellwig <hch@lst.de>, Fam Zheng <fam@euphon.net>,
        "Busch, Keith" <keith.busch@intel.com>,
        Sagi Grimberg <sagi@grimberg.me>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        Wolfram Sang <wsa@the-dreams.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Liang, Cunming" <cunming.liang@intel.com>,
        Nicolas Ferre <nicolas.ferre@microchip.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
        "David S . Miller" <davem@davemloft.net>,
        Jens Axboe <axboe@fb.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        "Liu, Changpeng" <changpeng.liu@intel.com>,
        "Paul E . McKenney" <paulmck@linux.ibm.com>,
        Amnon Ilan <ailan@redhat.com>, John Ferlan <jferlan@redhat.com>
Subject: Re: [PATCH v2 00/10] RFC: NVME MDEV
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On Thu, May 09, 2019 at 02:12:55AM -0700, Stefan Hajnoczi wrote:
> On Mon, May 06, 2019 at 12:04:06PM +0300, Maxim Levitsky wrote:
> > On top of that, it is expected that newer hardware will support the PASID based
> > device subdivision, which will allow us to _directly_ pass through the
> > submission queues of the device and _force_ us to use the NVME protocol for the
> > frontend.
> 
> I don't understand the PASID argument.  The data path will be 100%
> passthrough and this driver won't be necessary.

We still need a non-passthrough component to handle slow path,
non-doorbell controller registers and admin queue. That doesn't
necessarily need to be a kernel driver, though.