[openib-general] Re: [PATCH] [uCM] user specified context in CM events + new test program

[Sean Hefty]

Steve Wooding wrote:
> I've just starting looking into IB connection establishment and I was 
> wondering what the ib_cm_init_qp_attr() function actually does. Studying 
> the MindShare IB book, it talks about exchanging the QPNs, pSNs etc., 
> via the REQ and REP messages. However, looking at your cmpost.c example, 
> I see, for exmaple, that in the req handler the event containing the REQ 
> message is never actually used when modyfing the QP to RTR. The 
> ib_cm_init_qp_attr() function is used instead. Does the info in the REQ 
> message get read in kernel space?

The kernel CM stores the information used in the establishment of a connection. 
  It then formats the QP attribute structure for the user.  This avoids every 
app from having to store these same values and format the QP attribute structure.

- Sean