I've been looking for some time now, even studying the driver code, but I have not been able to figure it out yet. I know that there are IEEE1588 capable NICs that Intel offers. But it seems as if most just support timestamping at the MAC level, and then sending a follow-up message with this timestamp, i.e., the two-step process. So the simple question is: are there one-step capable NICs? Especially datacenter NICS (10 or 40GE)?