This patch implements the devices post parse callback and uses it to fill
the default qemu network card model into the XML if none is specified.
Libvirt assumes that the network card model for qemu is the "rtl8139".
Record this in the XML using the new callback to avoid user
confusion.
The following config elements now support a <vlan> subelements:
within a domain: <interface>, and the <actual> subelement of <interface>
within a network: the toplevel, as well as any <portgroup>
Each vlan element must have one or more <tag id='n'/> subelements. If
there is more than one tag, it is assumed that vlan trunking is being
requested. If trunking is required with only a single tag, the
attribute "trunk='yes'" should be added to the toplevel <vlan>
element.
Some examples:
<interface type='hostdev'/>
<vlan>
<tag id='42'/>
</vlan>
<mac address='52:54:00:12:34:56'/>
...
</interface>
<network>
<name>vlan-net</name>
<vlan trunk='yes'>
<tag id='30'/>
</vlan>
<virtualport type='openvswitch'/>
</network>
<interface type='network'/>
<source network='vlan-net'/>
...
</interface>
<network>
<name>trunk-vlan</name>
<vlan>
<tag id='42'/>
<tag id='43'/>
</vlan>
...
</network>
<network>
<name>multi</name>
...
<portgroup name='production'/>
<vlan>
<tag id='42'/>
</vlan>
</portgroup>
<portgroup name='test'/>
<vlan>
<tag id='666'/>
</vlan>
</portgroup>
</network>
<interface type='network'/>
<source network='multi' portgroup='test'/>
...
</interface>
IMPORTANT NOTE: As of this patch there is no backend support for the
vlan element for *any* network device type. When support is added in
later patches, it will only be for those select network types that
support setting up a vlan on the host side, without the guest's
involvement. (For example, it will be possible to configure a vlan for
a guest connected to an openvswitch bridge, but it won't be possible
to do that for one that is connected to a standard Linux host bridge.)
