Re: RFC: New device for zero-copy VM memory access

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* geoff@hostfission.com (geoff@hostfission.com) wrote:
> 
> 
> On 2019-11-01 01:52, Peter Maydell wrote:
> > On Thu, 31 Oct 2019 at 14:26, <geoff@hostfission.com> wrote:
> > > As the author of Looking Glass, I also have to consider the
> > > maintenance
> > > and the complexity of implementing the vhost protocol into the
> > > project.
> > > At this time a complete Porthole client can be implemented in 150
> > > lines
> > > of C without external dependencies, and most of that is boilerplate
> > > socket code. This IMO is a major factor in deciding to avoid
> > > vhost-user.
> > 
> > This is essentially a proposal that we should make our project and
> > code more complicated so that your project and code can be simpler.
> > I hope you can see why this isn't necessarily an argument that will hold
> > very much weight for us :-)
> 
> Certainly, I do which is why I am still going to see about using vhost,
> however, a device that uses vhost is likely more complex then the device
> as it stands right now and as such more maintenance would be involved on
> your end also. Or have I missed something in that vhost-user can be used
> directly as a device?

The basic vhost-user stuff isn't actually that hard;  if you aren't
actually shuffling commands over the queues you should find it pretty
simple - so I think your assumption about it being simpler if you avoid
it might be wrong.  It might be easier if you use it!

Dave

> > 
> > thanks
> > -- PMM
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK