vnet_desc
struct vnet_desc *vd_desc;
dr.descriptor_size = sizeof(struct vnet_desc);
size = roundup(nentries * sizeof(struct vnet_desc), PAGE_SIZE);
vd->vd_desc = (struct vnet_desc *)va;
bzero(vd->vd_desc, nentries * sizeof(struct vnet_desc));
size = vd->vd_nentries * sizeof(struct vnet_desc);
struct vnet_desc desc;