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Date: Fri, 8 Jun 2012 14:23:04 +0100
Message-ID: <CAJSP0QXgh7CcgUOjaMLm4=o+HO3DiE_degWHeNDs3d1Ykbeotw@mail.gmail.com>
From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH v4 06/16] net: Remove vlan qdev property
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To: zwu.kernel@gmail.com
Cc: aliguori@us.ibm.com, stefanha@linux.vnet.ibm.com, jan.kiszka@siemens.com, qemu-devel@nongnu.org, Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>, luowenj@cn.ibm.com, pbonzini@redhat.com

On Mon, Jun 4, 2012 at 6:29 AM,  <zwu.kernel@gmail.com> wrote:
> From: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
>
> The vlan feature is implemented using hubs and no longer uses
> special-purpose VLANState structs that are accessible as qdev
> properties.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
> ---
> =A0hw/qdev-properties.c | =A0 72 ----------------------------------------=
----------
> =A0hw/qdev.c =A0 =A0 =A0 =A0 =A0 =A0| =A0 =A02 -
> =A0hw/qdev.h =A0 =A0 =A0 =A0 =A0 =A0| =A0 =A04 ---
> =A0net.h =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0| =A0 =A03 --
> =A04 files changed, 0 insertions(+), 81 deletions(-)

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=3D1 -device virtio-net-pci=
,vlan=3D1

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=3D<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 :(.

Do you feel comfortable rewriting this commit?

Stefan