Re: [Qemu-devel] [PATCH 1/3] qemu: add capability for vhost-net busy polling

[Eduardo Habkost <ehabkost@redhat.com>]

On Mon, Jun 26, 2017 at 07:23:50AM -0600, Eric Blake wrote:
> On 06/17/2017 09:15 PM, Eduardo Habkost wrote:
> > (CCing qemu-devel and the QAPI maintainers.  I have a question
> > about introspection below.)
> > 
> 
> > 
> > Fortunately, netdev options are modelled in the QAPI schema as
> > union Netdev.  However, 'query-qmp-schema' doesn't seem to
> > include union Netdev because it is not referenced by any QMP
> > command or event.
> 
> I've posted patches in the past (qemu 2.6 timeframe, if I recall) that
> changed netdev_add into a fully-advertised interface, but we didn't take
> it then because we weren't sure how to handle the fact that netdev_add
> can currently accept both an integer (1) and a string ("1") as
> identical, and we didn't want to risk breaking clients that passed a
> string when the promoted command would only accept integers.  I guess we
> should revive that.
> 
> > 
> > Markus, Eric, Michael: is there any way libvirt can query the
> > definition of union Netdev from the schema with current QEMU?
> 
> Really, we need to promote netdev_add to a full-fledged QMP command.

This may be enough for -netdev, but do we want to make command-line
option introspection always depend on having the same struct being used
in a QMP command to work?  What if the arguments for the command-line
option don't match precisely the input of a QMP command?

-- 
Eduardo