Re: [Qemu-devel] [PATCH for-3.2 01/11] vhost-user: define conventions for vhost-user backends

[Michael S. Tsirkin]

On Mon, Dec 10, 2018 at 10:36:29PM +0400, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 10, 2018 at 6:30 PM Gerd Hoffmann <address@hidden> wrote:
> >
> > On Mon, Nov 26, 2018 at 04:42:40PM +0400, Marc-André Lureau wrote:
> > > As discussed during "[PATCH v4 00/29] vhost-user for input & GPU"
> > > review, let's define a common set of backend conventions to help with
> > > management layer implementation, and interoperability.
> > >
> > > Signed-off-by: Marc-André Lureau <address@hidden>
> > > Reviewed-by: Daniel P. Berrangé <address@hidden>
> >
> > Acked-by: Gerd Hoffmann <address@hidden>
> >
> > btw: have you seen the idea to use a vfio-style interface for
> > communication between qemu and external device emulation processes?
> 
> I heard there was some discussion during KVM forum.
> 
> Fwiwi, this is also an idea I proposed last year (and quickly
> discussed during my talk about multi-process qemu).
> I also experimented with the idea, and wrote a vfio-user backend, with
> a PCI serial device running in a seperate process:
> the qemu tree: https://github.com/elmarco/qemu/tree/wip/vfio-user (dirty tree)
> and the serial device:
> https://github.com/elmarco/qemu/blob/wip/vfio-user/contrib/libvfio-user/vfio-user-serial.c

Right. The main issue is that we need to make sure only
in-tree devices are supported. vhost-user by design
is for out of tree users. It needn't be hard,
maybe it's enough to just make qemu launch these processes
as opposed to connecting to them on command line.

> 
> 
> >
> > cheers,
> >   Gerd
> >