5ie. VIRTIO_NET_F_HOST_TSO* and VIRTIO_NET_F_HOST_UFO are dependent on VIRTIO_NET_F_CSUM; a dvice which offers the offload features must offer the checksum feature, and a driver which accepts the offload features must accept the checksum feature. Similar logic applies to the VIRTIO_NET_F_GUEST_TSO4 features depending on VIRTIO_NET_F_GUEST_CSUM.