ring_desc_base
iowrite32(cons, ring_desc_base(ring) + 8);
iowrite32(prod << 16, ring_desc_base(ring) + 8);
iowrite32(value, ring_desc_base(ring) + offset);
iowrite32(value, ring_desc_base(ring) + offset);
iowrite32(value >> 32, ring_desc_base(ring) + offset + 4);