Error "Invalid value for attribute 'type' in element 'backend': 'passt'" when adding user network interface with 'passt' backend

Software environment

• Operating system: Debian 12 (bookworm)
• Architecture: x86_64
• kernel version: 6.1.0-7
• libvirt version: 9.0.0
• Hypervisor and version: QEMU 7.2.0

Description of problem

When i add a VM using a 'user' network interface with 'passt' backend set i get the error error: XML error: Invalid value for attribute 'type' in element 'backend': 'passt'. but passt should be supported on libvirt 9.0.0

Steps to reproduce

1. Define the VM with virsh using net-user-passt.x86_64-latest.xml or add the following 'user' network interface with 'passt' backend in any VM XML

   <interface type="user">
     <backend type='passt'/>
     <portForward proto='tcp'>
       <range start="8022" to="22" />
     </portForward>
     <mac address="52:54:00:b4:5b:1e"/>
     <model type="virtio"/>
   </interface>

Unfortunately the passt support included in 9.0.0 is incomplete, so a decision was made to completely disable it for the Debian 12 release. See https://salsa.debian.org/libvirt-team/libvirt/-/merge_requests/177 and https://salsa.debian.org/libvirt-team/libvirt/-/merge_requests/176 for more information. libvirt 9.2.0, which is currently available in experimental, contains fully working passt support.

closed