Hello,

This allow rdma ucm to establish an XRC connection between two nodes. Most
of the changes are related to modify_qp since the API is different
whether the QP is on the send or receive side.
To create an XRC receive QP, the cap.max_send_wr must be set to 0.
Conversely, to create the send XRC QP, that attribute must be non-zero.

Regards,
  Frank