/**
* Return the physical address (or virtual address in case of
* virtio-user) of mbuf data buffer.
+ *
+ * The address is firstly casted to the word size (sizeof(uintptr_t))
+ * before casting it to uint64_t. This is to make it work with different
+ * combination of word size (64 bit and 32 bit) and virtio device
+ * (virtio-pci and virtio-user).
*/
-#define VIRTIO_MBUF_ADDR(mb, vq) (*(uint64_t *)((uintptr_t)(mb) + (vq)->offset))
+#define VIRTIO_MBUF_ADDR(mb, vq) \
+ ((uint64_t)(*(uintptr_t *)((uintptr_t)(mb) + (vq)->offset)))
#else
#define VIRTIO_MBUF_ADDR(mb, vq) ((mb)->buf_physaddr)
#endif