phys_sge_pairs
len = (nsegs / 8) * sizeof(struct phys_sge_pairs);
struct phys_sge_pairs *sgl;
sgl = (struct phys_sge_pairs *)(cpl + 1);
MPASS(j + 8 * (sgl - (struct phys_sge_pairs *)(cpl + 1)) == nsegs);