+/* The bit of the ISR which indicates a device has an interrupt. */
+#define VIRTIO_ISR_INTR 0x1
+/* The bit of the ISR which indicates a device configuration change. */
+#define VIRTIO_ISR_CONFIG 0x2
+/* Vector value used to disable MSI for queue. */
+#define VIRTIO_MSI_NO_VECTOR 0xFFFF
+
+/* The alignment to use between consumer and producer parts of vring. */
+#define VIRTIO_VRING_ALIGN 4096
+