After resolving address information using rdma_getaddrinfo, a user may use this call to allocate an
rdma_cm_id based on the results.
If the rdma_cm_id will be used on the active side of a connection, meaning that res->ai_flag does not
have RAI_PASSIVE set, rdma_create_ep will automatically create a QP on the rdma_cm_id if qp_init_attr is
not NULL. The QP will be associated with the specified protection domain, if provided, or a default
protection domain if not. Users should see rdma_create_qp for details on the use of the pd and
qp_init_attr parameters. After calling rdma_create_ep, the returned rdma_cm_id may be connected by
calling rdma_connect. The active side calls rdma_resolve_addr and rdma_resolve_route are not necessary.
If the rdma_cm_id will be used on the passive side of a connection, indicated by having res->ai_flag
RAI_PASSIVE set, this call will save the provided pd and qp_init_attr parameters. When a new connection
request is retrieved by calling rdma_get_request, the rdma_cm_id associated with the new connection will
automatically be associated with a QP using the pd and qp_init_attr parameters. After calling
rdma_create_ep, the returned rdma_cm_id may be placed into a listening state by immediately calling
rdma_listen. The passive side call rdma_bind_addr is not necessary. Connection requests may then be
retrieved by calling rdma_get_request.
The newly created rdma_cm_id will be set to use synchronous operation. Users that wish asynchronous
operation must migrate the rdma_cm_id to a user created event channel using rdma_migrate_id.
Users must release the created rdma_cm_id by calling rdma_destroy_ep.