[openib-general] Re: A Couple of User CM Questions

[Hal Rosenstock]

On Mon, 2005-05-09 at 14:39, Libor Michalek wrote: 
> On Mon, May 09, 2005 at 01:22:17PM -0400, Hal Rosenstock wrote:
> > Hi Libor,
> > 
> > I have a couple of questions pertaining to the user CM.
> > 
> > 1. It appears that device (and port) are not supported either incoming
> > or outgoing. So if that is correct, I presume only the first device
> > (first port) is the only one which can be expected to work. Correct ?
> > If so, that should be added to README as a current limitation.

So I am presuming this is a current limitation.

> > 2. Any idea on how device would be supported ? Would this just be with
> > an IB device number or a string like "mthca0" ?
> 
>   I was thinking that the destination GID in the req_event path record
> would be sufficient to identify the local device/port, but I had not
> taken a look at sidr_req_event. I think this is the correct GID to use
> for creating the QP, but I have not taken a look at how easy it is to
> turn a GID into a suitable device/portin user verbs. Thoughts?

and source GID (in the REQ primary path) on the active side ? 

That seems like it would work but wouldn't you need to walk the GID
tables on each port on each IB device until you find the match ? Sounds
a little expensive but would only be done once per connection.

The advantage of GID is this would be common across all IB devices. Not
sure what else could be other than a deterministic numbering of IB
devices locally which I believe does not currently exist.

-- Hal