anchor.diff:  (defstruct (virtio-gpu
                (:area :wired))
     virtio-device
  -  irq-handler-function
  -  (irq-latch (make-latch "Virtio-Block IRQ Notifier"))
     request-phys
     request-virt
     scanout
  
positive.code:           (sys.int::memref-unsigned-byte-32 (+ addr +virtio-gpu-ctrl-hdr-fence-id+) 0) fence-id
            (sys.int::memref-unsigned-byte-32 (+ addr +virtio-gpu-ctrl-hdr-ctx-id+) 0) ctx-id)))
  
  (defun virtio-gpu-issue-command (gpu command-length response-length &optional in-unsafe-context-p)
    (let* ((req-phys (virtio-gpu-request-phys gpu))
           (dev (virtio-gpu-virtio-device gpu))
           (vq (virtio-virtqueue dev +virtio-gpu-controlq+))
  
negative.code:           (t
             (values nil resp-type)))))
  
  (defun virtio-gpu-transfer-to-host-2d (gpu x y width height offset resource-id)
    (virtio-gpu-configure-command gpu
                                  +virtio-gpu-cmd-transfer-to-host-2d+
                                  0
  