[ofa-general] Userspace support for SA event registration (was: IPoIB path caching)

[Sean Hefty]

> This same argument is why IPoIB ARP decisions really have no bearing
> on IB PRs. IPoIB ARP logic and refreshes is designed to support the
> distributed ND lookup model - IB PR's have completely different
> lifetime rules that are totally unrelated to ARP's liftime rules.  The
> existing trap monitoring in Sean's module covers about 90% of the
> cases in IB when you need to invalidate a PR, the last 10% will need
> something new :(
> 
> Sean, it seems to me that alot of what is being talked about here
> really boils down to policy decisions about the caching. Maybe you'd
> see less resistance if the kernel module didn't have any policy and
> that was left to userspace. Even your choice today of putting the big
> GetTable query in the kernel strikes me as something I'd prefer to see
> in userspace.

In order to migrate the local SA to user space, we need a way to export
SA event registration.  And I don't think we've ever reached agreement
on the best approach to doing this.

I've posted patches for one approach:

http://lists.openfabrics.org/pipermail/general/2007-February/032487.html

This exposes a user space SA interface for event registration and raw IB
multicast support.  The approach is generic enough that it could be
extended to other SA queries, but the user MAD interface covers this
area as well.

I'd like to get agreement on an approach for this, even outside of local 
SA support.

- Sean