On Mon, Jun 11, 2012 at 4:57 PM, Stefan Hajnoczi <stefa...@linux.vnet.ibm.com> wrote: > On Mon, Jun 11, 2012 at 08:28:57AM +0200, Paolo Bonzini 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. >> >> That said, I agree that this is a somewhat fringe usage; most people >> will use -net nic,model=virtio,vlan=1 rather than "-device". We may get >> by with dropping it. I have no strong opinion either way. > > Either we keep backwards compatibility or we don't. Taking a middle > path where we preserve only some of the "VLAN" syntax is confusing and > inconsistent. in terms of technology, i fully agree with you, but in terms of usefulness and our business, it will waste our effort, time and is meaningless if nobody or no customers use this syntax. As i said, if someone complain this later, we can fix it.
> > Like Paolo said, the point here is not to drop "VLAN" support. We're > simply moving this feature into a regular net client (the hub) so that > the special case "VLAN" code in net.c can be removed. > > Stefan > -- Regards, Zhi Yong Wu
