Fixed-latency GBT links RX
Some efforts have been invested into fixed-latency GBT links RX for the GEM QC8 APEX GBTx-based TTC link. There are signs of this in !145 and !155 (merged), such as new registers in the address table and new commented-out signals in the gbt
module. However, none of the changes to the GBT cores have been committed and pushed.
The fixed-latency GBT links RX changes should be polished, committed, and pushed upstream in order to allow, among others, building from scratch the QC8 APEX flavors. The feature should be optional (e.g. enabled on the GBTx-link TTC links and disabled on the normal GBT links) during initial validation since instabilities have been reported at QC8.