[ofw] partial review of mlx4 branch

[Fab Tillier]

Hefty, Sean wrote on Tue, 18 Oct 2011 at 09:29:46

>> How would a kernel driver establish a trusted communications link with
>> a user- space path record service? What is the failover position for
>> the case when the user-space PR agent is unavailable? Would a caching
>> user-space PR agent be accessible from other nodes?
> 
> well, opensm is a user space service...
> 
> Communication with a service can be done using QP 1, through TCP/IP, or
> some other means, like named pipes.  We're only limited by what Windows
> supports in the kernel.  The location of the service doesn't have to be local,
> as long as the address is known.

Agreed.

> This raises an issue with the Windows stack, in that access to QP0/1 are open
> to any application that wishes to create havoc on the subnet.

Agreed also, though I think we could add checks for this without affecting the ABI.  I'd expect the majority of user-mode applications to deal with IP addresses, and not to ever want to learn about the wonders of IB fabric management and SA queries.

Might be worth coming up with a list of verbs that should require elevated privileges, vs. those that are open to anyone?  Something like "you must run with elevated privileges to register a MAD service".

-Fab