And I think that's TX-side BERT functionality done, other than rate control (it's fixed 10.3125 Gbps right now... sub-rate to divide by 2/4/8/16 will be straightforward but hitting nice round lower rates will require some DRP fun since the QPLL is fixed 10.3125 for 10GbE in the same quad).
This is probably complete enough feature set wise that I can start building the scopehal driver. There's no RX over SCPI yet, but that will come later.