Re: [PATCH 4/4] virtio-net: add linkspeed and duplex settings to virtio-net

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Mar 02, 2018 at 03:14:01PM +0800, Jason Wang wrote:
> 
> 
> On 2018年03月02日 11:46, Jason Baron wrote:
> > Although linkspeed and duplex can be set in a linux guest via 'ethtool -s',
> > this requires custom ethtool commands for virtio-net by default.
> > 
> > Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
> > the hypervisor to export a linkspeed and duplex setting. The user can
> > subsequently overwrite it later if desired via: 'ethtool -s'.
> > 
> > Linkspeed and duplex settings can be set as:
> > '-device virtio-net,speed=10000,duplex=full'
> 
> I was thinking whether or not it's better to decide the duplex by the type
> of backends.
> 
> E.g userspace and vhost-kernel implement a in fact half duplex. But dpdk
> implement a full duplex.
> 
> Thanks

OTOH it's a priority for some people to be able to support migration
between different backend types. Breaking that won't be nice.

> > 
> > where speed is [0...INT_MAX], and duplex is ["half"|"full"].
> > 
> > Signed-off-by: Jason Baron<jbaron@akamai.com>
> > Cc: "Michael S. Tsirkin"<mst@redhat.com>
> > Cc: Jason Wang<jasowang@redhat.com>
> > Cc:virtio-dev@lists.oasis-open.org
> > ---