This article records using HP 544+FLR-QSFP (Mellanox ConnectX-3 Pro based) on Ubuntu 20.04 for RDMA and NVMe-oF testing.
Hardware
HP 544+FLR-QSFP 40Gb/s dual-port adapter.

Driver
Use Mellanox OFED package for Ubuntu 20.04 from NVIDIA networking site.