The EF_RX_TIMESTAMPING_ORDERING environment variable allows the user to select either NIC hardware timestamps or timestamps generated by an external equipment in cPacket trailer format.
For more information, refer to onload_ordered_epoll_wait.
onload_timestamping_request() function supports received packet timestamps from multiple sources with sub-nanosecond resolution.
Timestamps can be generated by the network adapter and/or timestamps applied by an external equipment using the cPacket trailer format.
See onload_timestamping_request for details.