Mellanox ConnectX-3 interfaces disappear

[digity]

I'm trying to speed test some Mellanox ConnectX-3 dual port 40GbE NICs on my LGA2011 servers (using a Linux live USB, System Rescue CD) and I'm getting this weird behavior where the assigned interface/logical name disappears (i.e., en25ps0) when I connect a QSFP+ network cable to a port. If I boot up with a cable already connected I get no interface/logical name at all. If I boot up without a cable connected and leave it unconnected, the interface/logical name stays. I'm not sure if this matters, but the other end of the cables are connected to another ConnectX-3 in a LGA2011 server running Ubuntu 19.10 live USB.

Any idea why this happening? Any ideas on how to resolve this?

 

[BeTeP]

The most likely reason is that the cards are in VPI mode. You can switch them into ethernet only mode with mstconfig:

apt install mstflint
lspci -nnd 15b3:: | awk '{print$1}' | xargs -n1 -I{} mstconfig -d {} -y set LINK_TYPE_P1=2 LINK_TYPE_P2=2
reboot