#define VIRTQUEUE_NUSED(vq) ((uint16_t)((vq)->vq_ring.used->idx - (vq)->vq_used_cons_idx))
void vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx);
#define VIRTQUEUE_NUSED(vq) ((uint16_t)((vq)->vq_ring.used->idx - (vq)->vq_used_cons_idx))
void vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx);