Re: [Qemu-devel] [PATCH 2/3] hw/virtio-net.c: set config size using host features

[Alexander Graf <agraf@suse.de>]

On 02/06/2013 12:47 AM, Jesse Larrew wrote:
> Currently, the config size for virtio devices is hard coded. When a new
> feature is added that changes the config size, drivers that assume a static
> config size will break. For purposes of backward compatibility, there needs
> to be a way to inform drivers of the config size needed to accommodate the
> set of features enabled.
>
> Signed-off-by: Jesse Larrew<jlarrew@linux.vnet.ibm.com>

The following patch gets my s390 virtio guest working again, but I doubt 
it's the right fix.

What is the expected dependency chain of feature calls?


Alex

diff --git a/hw/s390x/s390-virtio-bus.c b/hw/s390x/s390-virtio-bus.c
index 089ed92..81be971 100644
--- a/hw/s390x/s390-virtio-bus.c
+++ b/hw/s390x/s390-virtio-bus.c
@@ -154,7 +154,7 @@ static int s390_virtio_net_init(VirtIOS390Device *dev)
      VirtIODevice *vdev;

      vdev = virtio_net_init((DeviceState *)dev, &dev->nic, &dev->net,
-                           dev->host_features);
+                           dev->host_features | (1 << VIRTIO_NET_F_MAC));
      if (!vdev) {
          return -1;
      }