Re: [PATCH RFC 00/11] nvmet: Add NVMe target mdev/vfio driver

[Mike Christie <michael.christie@oracle.com>]

On 3/13/25 1:47 AM, Christoph Hellwig wrote:
> On Thu, Mar 13, 2025 at 12:18:01AM -0500, Mike Christie wrote:
>>
>> If we agree on a new virtual NVMe driver being ok, why mdev vs vhost?
>> =====================================================================
>> The problem with a vhost nvme is:
>>
>> 2.1. If we do a fully vhost nvmet solution, it will require new guest
>> drivers that present NVMe interfaces to userspace then perform the
>> vhost spec on the backend like how vhost-scsi does.
>>
>> I don't want to implement a windows or even a linux nvme vhost
>> driver. I don't think anyone wants the extra headache.
> 
> As in a nvme-virtio spec?  Note that I suspect you could use the
> vhost infrastructure for something that isn't virtio, but it would> be a fair amount of work.

Yeah, for this option 2.1 I meant a full nvme-virtio spec.

(forgot to cc Hannes's so cc'ing him now)

And you can use the vhost infrastructure for something that's not virtio.
Hannes's did that for vhost megasas:

https://github.com/Datera/rts-megasas/blob/master/rts_megasas-fabric-v6.patch

but perf is not good, it's extra userspace code and I think it's
just a little more messy because it requires the extra
QEMU code which I know those engineers didn't want.