anchor.diff:      ;; Set the driver bit in the status field.
       (setf (virtio-device-status device) (logior +virtio-status-acknowledge+
                                                   +virtio-status-driver+))
  +    (debug-print-line "virtio-gpu: " (virtio-device-specific-header/32 device +virtio-gpu-config-num-scanouts+) " scanouts")
  +    (debug-print-line "virtio-gpu: " (virtio-device-specific-header/32 device +virtio-gpu-config-num-capsets+) " capsets")
  +    ;; Enable virgl, if present.
  +    (when (virtio-device-feature device +virtio-gpu-f-virgl+)
  +      (debug-print-line "virtio-gpu: virgl enabled")
  +      (setf (virtio-driver-feature device +virtio-gpu-f-virgl+) t)
  +      (setf (virtio-gpu-virgl-p gpu) t))
       ;; Allocate virtqueues.
       (when (not (virtio-configure-virtqueues device 2))
         (setf (virtio-device-status device) +virtio-status-failed+)
         (return-from virtio-gpu-register nil))
  -    (when (virtio-device-feature device +virtio-gpu-f-virgl+)
  -      (setf (virtio-driver-feature device +virtio-gpu-f-virgl+) t)
  -      (debug-print-line "virtio-gpu: virgl enabled"))
       ;; Configuration complete, go to OK mode.
       (setf (virtio-device-status device) (logior +virtio-status-acknowledge+
                                                   +virtio-status-driver+
  
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: (defconstant +virtio-gpu-format-a8b8g8r8-unorm+ 121)
  (defconstant +virtio-gpu-format-r8g8b8x8-unorm+ 134)
  
  (defconstant +virtio-gpu-update-cursor-scanout-id+ 0)
  (defconstant +virtio-gpu-update-cursor-x+ 4)
  (defconstant +virtio-gpu-update-cursor-y+ 8)
  