Can you share what your experience with implementing IPoIB with used gear was? I'm asking mainly because I actually got interested recently with such setups however I got rather discouraged by the driver support.

As an example here is the driver page for Mellanox, now owned by Nvidia, since they are a major Infiniband equipment supplier: https://network.nvidia.com/products/infiniband-drivers/linux...

It seems that some decent support only exists for more recent generations. The older ones like ConnectX-3 or earlier, which typically show up on ebay are either not supported any more or maybe available for older kernel versions and soon to be EOLed.

So do I understand it correctly that to use such adapters one has to actually downgrade to an older kernel version?

Or is there some basic support in the latest Linux kernels for older generations still?