20.16.16. Channel
This represents a private communication channel between the host physical machine and the guest virtual machine and is manipulated by making changes to your guest virtual machine virtual machine using a management tool that results in changes made to the following section of the domain xml
...
<devices>
<channel type='unix'>
<source mode='bind' path='/tmp/guestfwd'/>
<target type='guestfwd' address='10.0.2.1' port='4600'/>
</channel>
<!-- KVM virtio channel -->
<channel type='pty'>
<target type='virtio' name='arbitrary.virtio.serial.port.name'/>
</channel>
<channel type='unix'>
<source mode='bind' path='/var/lib/libvirt/qemu/f16x86_64.agent'/>
<target type='virtio' name='org.qemu.guest_agent.0'/>
</channel>
<channel type='spicevmc'>
<target type='virtio' name='com.redhat.spice.0'/>
</channel>
</devices>
...Figure 20.63. Channel
This can be implemented in a variety of ways. The specific type of
<channel> is given in the type attribute of the <target> element. Different channel types have different target attributes as follows:
guestfwd- Dictates that TCP traffic sent by the guest virtual machine to a given IP address and port is forwarded to the channel device on the host physical machine. Thetargetelement must have address and port attributes.virtio- Paravirtualized virtio channel.<channel>is exposed in the guest virtual machine under/dev/vport*, and if the optional elementnameis specified,/dev/virtio-ports/$name(for more info, see http://fedoraproject.org/wiki/Features/VirtioSerial). The optional elementaddresscan tie the channel to a particulartype='virtio-serial'controller, documented above. With QEMU, if name is "org.qemu.guest_agent.0", then libvirt can interact with a guest virtual machine agent installed in the guest virtual machine, for actions such as guest virtual machine shutdown or file system quiescing.spicevmc- Paravirtualized SPICE channel. The domain must also have a SPICE server as a graphics device, at which point the host physical machine piggy-backs messages across the main channel. Thetargetelement must be present, with attributetype='virtio';an optional attributenamecontrols how the guest virtual machine will have access to the channel, and defaults toname='com.redhat.spice.0'. The optional<address>element can tie the channel to a particulartype='virtio-serial'controller.
