[ofa-general] Allowing end-users to query for fabric information

[Roland Dreier]

 > What was the reason for making this design choice? While I could
 > certainly provide boot scripts to change the permissions to
 > /dev/infiniband/umad*, I'd rather understand why the decision was made
 > to restrict access.

because /dev/infiniband/umadX allows full unfiltered access to
send/receive any MADs.  Including changing routing tables, bringing
ports down, etc.  Not stuff that unprivileged users should be able to do.

It would make sense to have a higher-level interface that only allows
safe queries without side effects, but that's quite a bit more work than
just changing permissions on device nodes.

 - R.