Re: [Qemu-devel] [PATCH v4 06/16] net: Remove vlan qdev property

[Luiz Capitulino]

On Mon, 11 Jun 2012 22:15:55 +0800
Zhi Yong Wu <address@hidden> wrote:

> On Mon, Jun 11, 2012 at 2:28 PM, Paolo Bonzini <address@hidden> wrote:
> > Il 09/06/2012 05:04, Zhi Yong Wu ha scritto:
> >>>>> This commit looks suspicious because it removes a user-visible qdev
> >>>>> property but we're trying to preserve backward compatibility.  This
> >>>>> command-line will break:
> >>>>>
> >>>>> x86_64-softmmu/qemu-system-x86_64 -net user,vlan=1 -device 
> >>>>> virtio-net-pci,vlan=1
> >>>>>
> >>>>> Instead of dropping the qdev_prop_vlan completely the
> >>>>> hw/qdev-properties.c code needs to call net/hub.h external functions
> >>>>> to implement equivalent functionality:
> >>>>>
> >>>>> 1. Setting the vlan=<id> property looks up the hub port and assigns
> >>>>> the NICConf->peer field.
> >>>>> 2. Getting the vlan property looks up the hub id (i.e. vlan id) given
> >>>>> the peer.  If the peer is not a hub port the result is -1.
> >>>>>
> >>>>> When I wrote this patch I missed the big picture and forgot about
> >>>>> backwards compatibility :(.
> >>>>>
> >> To be honest, i am concerned if anyone uses this syntax. Since the
> >> feature will finally be discarded, i suggest that we don't support
> >> this now. If someone complains this later, we can fix it. If nobody
> >> complains, that is what we hope.
> >
> > I think you're missing the big picture of this series, which is exactly
> > _not_ to discard the VLAN feature, but just to rewrite it in a better way.
> Yeah, i know that this series are rewriting VLAN feature in one better way.
> 
> What i mean was that luiz and other some guys think that the -net
> syntax should be completely removed.

One of the motivations for having the hub feature is to preserve the vlan
functionality, in that case we shouldn't break cmd-line backwards compatibility.