Re: [Qemu-devel] [PATCH v4 1/4] vhost-user: add new vhost user messages to support virtio config space

[Michael S. Tsirkin]

On Thu, Oct 19, 2017 at 05:43:18PM +0200, Paolo Bonzini wrote:
> On 19/10/2017 17:39, Michael S. Tsirkin wrote:
> >> Add VHOST_USER_GET_CONFIG/VHOST_USER_SET_CONFIG messages which can be
> >> used for live migration of vhost user devices, also vhost user devices
> >> can benefit from the messages to get/set virtio config space from/to the
> >> I/O target. For the purpose to support virtio config space change,
> >> VHOST_USER_SET_CONFIG_FD message is added as the event notifier
> >> in case virtio config space change in the I/O target.
> >>
> >> Signed-off-by: Changpeng Liu <address@hidden>
> > I don't much like it that config is getting passed through.
> > 
> > IMO this makes managing things harder not easier.
> > 
> > How about specific messages about specific parts of
> > config space that you want to get from the backend?
> 
> In the case of virtio-blk that would be all of it.  Do you have a case
> in mind where some part of the configuration space is owned by QEMU?
> 
> Paolo

Yes. seg_max