VIRTQUEUE_NUM
VIRTQUEUE_NUM, req->tc.sdata, req->tc.size);
VIRTQUEUE_NUM, req->rc.sdata, req->rc.capacity);
VIRTQUEUE_NUM, req->tc.sdata, req->tc.size);
out += pack_sg_list_p(chan->sg, out, VIRTQUEUE_NUM,
VIRTQUEUE_NUM, req->rc.sdata, in_hdr_len);
pack_sg_list_p(chan->sg, out + in, VIRTQUEUE_NUM,
sg_init_table(chan->sg, VIRTQUEUE_NUM);
struct scatterlist sg[VIRTQUEUE_NUM];
.maxsize = PAGE_SIZE * (VIRTQUEUE_NUM - 3),