docs/system/virtio-net-failover.rst

9 virtio-net device. Before migration the vfio device is unplugged and data flows
10 through the virtio-net device, on the target side another vfio-pci device is
14 The two devices are called primary and standby device. The fast hardware based
15 networking device is called the primary device and the virtio-net device is the
16 standby device.
23 devices are allowed as primary device. The user needs to ensure that primary
30 fast networking device by falling back to a virtio-net device for the
34 device via the PCIe based hotplug handler and traffic will go through
35 the virtio-net device. On the target system the primary device will be
37 again as the primary device.
42 The primary device can be hotplugged or be part of the startup configuration
46   -device virtio-net-pci,netdev=hostnet1,id=net1,mac=52:54:00:6f:55:cc,bus=root2,failover=on
52   -device vfio-pci,host=5e:00.2,id=hostdev0,bus=root1,failover_pair_id=net1
54 ``failover_pair_id`` references the id of the virtio-net standby device.
61 Both primary and standby device can be hotplugged via the QEMU
62 monitor. Note that if the virtio-net device is plugged first a warning
63 will be issued that it couldn't find the primary device.
70 will go into this state. It will wait until the device unplug is
73 feature bit was negotiated for the virtio-net standby device.