Joins a multicast group.
(struct rdma_cm_id *id,
struct sockaddr *addr,
Communication identifier associated with the request.
Multicast address identifying the group to join.
User-defined context associated with the join request.
Joins a multicast group and attaches an associated QP to the group.
Returns 0 on success, or -1 on error. If an error occurs, errno will be
set to indicate the failure reason.
Before joining a multicast group, the rdma_cm_id must be bound to
an RDMA device by calling rdma_bind_addr or rdma_resolve_addr. Use of
rdma_resolve_addr requires the local routing tables to resolve the
multicast address to an RDMA device, unless a specific source address
is provided. The user must call rdma_leave_multicast to leave the
multicast group and release any multicast resources. After the join
operation completes, if a QP is associated with the rdma_cm_id,
it is automatically attached to the multicast group when the multicast
event is retrieved by the user. Otherwise, the user is responsible
for calling ibv_attach_mcast to bind the QP to the multicast group.
The join context is returned to the user through the private_data
field in the rdma_cm_event.