Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor

[David Miller <davem@davemloft.net>]

From: Jason Baron <jbaron@akamai.com>
Date: Fri, 22 Dec 2017 16:54:01 -0500

> The ability to set speed and duplex for virtio_net in useful in various
> scenarios as described here:
> 
> 16032be virtio_net: add ethtool support for set and get of settings
> 
> However, it would be nice to be able to set this from the hypervisor,
> such that virtio_net doesn't require custom guest ethtool commands.
> 
> 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'.
> 
> Signed-off-by: Jason Baron <jbaron@akamai.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>

Looks mostly fine to me but need some virtio_net reviewers on this one.

> @@ -57,6 +57,8 @@
>  					 * Steering */
>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>  
> +#define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Host set linkspeed and duplex */
> +

Why use a value so far away from the largest existing one?

Just curious.