Hi Matt,
Adding my response to your earlier questions.
We have been using RHEL-7 (7.6 or later most recently I believe) to serve small RTEMS 4.9.2 and 4.10.2 systems (uC5282 boards so 68K with only 16MB RAM) over NFSv2, with no ill effects. I don’t think we’ve tested RHEL-8 as an NFSv2 server yet but we will have
to fairly soon I’m sure. The ability to enable v2 is not a bug AFAIK, but Red Hat won’t actively support it.
I did read the other day that the latest Linux kernel release will not support NFS over UDP by default (v2 only works over UDP, I’m not sure about v3) so the writing is on the wall, but it’ll hopefully be a year or two until RHEL gets to that kernel.
As far as I know, all versions of NFS work over TCP, at least on Linux (and for a long time, you can find references to this all the way back on RHEL 4 doc, probably earlier). Quoting the Reference Guide:
All versions of NFS can use Transmission Control Protocol (TCP) running over an IP network, with NFSv4 requiring it. NFSv2 and NFSv3 can use the User Datagram Protocol (UDP) running over an IP network to provide a stateless network connection between the client and server.
Other vendors have added TCP support to NFSv2, so it's not an isolated case.
If UDP support is the problem, that could be a way around it. Of course, moving to (at least) NFSv3 would be ideal.
Cheers,
Ricardo