anchor.diff:  (defconstant +virtio-gpu-format-a8b8g8r8-unorm+ 121)
   (defconstant +virtio-gpu-format-r8g8b8x8-unorm+ 134)
   
  -(defconstant +virtio-gpu-resource-create-2d-resource-id+ 0)
  -(defconstant +virtio-gpu-resource-create-2d-format+      4)
  -(defconstant +virtio-gpu-resource-create-2d-width+       8)
  -(defconstant +virtio-gpu-resource-create-2d-height+     12)
  -
  -(defconstant +virtio-gpu-resource-create-2d-size+       16)
  -
  -(defconstant +virtio-gpu-resource-unref-resource-id+ 0)
  -
  -(defconstant +virtio-gpu-resource-unref-size+ 8)
  -
  -(defconstant +virtio-gpu-set-scanout-x+ 0)
  -(defconstant +virtio-gpu-set-scanout-y+ 4)
  -(defconstant +virtio-gpu-set-scanout-width+ 8)
  -(defconstant +virtio-gpu-set-scanout-height+ 12)
  -(defconstant +virtio-gpu-set-scanout-scanout-id+ 16)
  -(defconstant +virtio-gpu-set-scanout-resource-id+ 20)
  -
  -(defconstant +virtio-gpu-set-scanout-size+ 24)
  -
  -(defconstant +virtio-gpu-resource-flush-x+ 0)
  -(defconstant +virtio-gpu-resource-flush-y+ 4)
  -(defconstant +virtio-gpu-resource-flush-width+ 8)
  -(defconstant +virtio-gpu-resource-flush-height+ 12)
  -(defconstant +virtio-gpu-resource-flush-resource-id+ 16)
  -
  -(defconstant +virtio-gpu-resource-flush-size+ 24)
  -
  -(defconstant +virtio-gpu-transfer-to-host-2d-x+ 0)
  -(defconstant +virtio-gpu-transfer-to-host-2d-y+ 4)
  -(defconstant +virtio-gpu-transfer-to-host-2d-width+ 8)
  -(defconstant +virtio-gpu-transfer-to-host-2d-height+ 12)
  -(defconstant +virtio-gpu-transfer-to-host-2d-offset+ 16)
  -(defconstant +virtio-gpu-transfer-to-host-2d-resource-id+ 24)
  -
  -(defconstant +virtio-gpu-transfer-to-host-2d-size+ 32)
  -
  -(defconstant +virtio-gpu-resource-attach-backing-resource-id+ 0)
  -(defconstant +virtio-gpu-resource-attach-backing-nr-entries+ 4)
  -(defconstant +virtio-gpu-resource-attach-backing-entry0+ 8)
  -
  -(defconstant +virtio-gpu-mem-entry-addr+   0)
  -(defconstant +virtio-gpu-mem-entry-length+ 8)
  -
  -(defconstant +virtio-gpu-mem-entry-size+ 16)
  -
  -(defconstant +virtio-gpu-resource-detach-backing-resource-id+ 0)
  -
  -(defconstant +virtio-gpu-resource-detach-backing-size+ 8)
  -
   (defconstant +virtio-gpu-update-cursor-scanout-id+ 0)
   (defconstant +virtio-gpu-update-cursor-x+ 4)
   (defconstant +virtio-gpu-update-cursor-y+ 8)
  
positive.code:           (sys.int::%fill-words (convert-to-pmap-address framebuffer-phys) 0 (truncate framebuffer-size 2))
            ;; Attach backing store to framebuffer resource.
            (multiple-value-bind (successp error)
                (virtio-gpu-attach-backing gpu +virtio-gpu-framebuffer-resource-id+ framebuffer-phys framebuffer-size)
              (when (not successp)
                (debug-print-line "virtio-gpu: Unable to attach framebuffer memory: " error)
              (return-from virtio-gpu-register nil)))
  
negative.code: ;; success responses
  (defconstant +virtio-gpu-resp-ok-nodata+               #x1100)
  (defconstant +virtio-gpu-resp-ok-display-info+         #x1101)
  (defconstant +virtio-gpu-resp-ok-capset-info+          #x1102)
  (defconstant +virtio-gpu-resp-ok-capset+               #x1103)
  
  ;; error responses
  (defconstant +virtio-gpu-resp-err-unspec+              #x1200)
  