config root man

.TH "RDMA_CM" 7 "2008-01-02" "librdmacm" "Librdmacm Programmer's Manual" librdmacm
.SH NAME
rdma_cm \- RDMA communication manager.
.SH SYNOPSIS
.B "#include <rdma/rdma_cma.h>"
.SH "DESCRIPTION"
Used to establish communication over RDMA transports.
.SH "NOTES"
The RDMA CM is a communication manager used to setup reliable, connected
and unreliable datagram data transfers.  It provides an RDMA transport
neutral interface for establishing connections.  The API is based on sockets,
but adapted for queue pair (QP) based semantics: communication must be
over a specific RDMA device, and data transfers are message based.
.P
The RDMA CM only provides the communication management (connection setup /
teardown) portion of an RDMA API.  It works in conjunction with the verbs
API defined by the libibverbs library.  The libibverbs library provides the
interfaces needed to send and receive data.
.SH "CLIENT OPERATION"
This section provides a general overview of the basic operation for the active,
or client, side of communication.  A general connection flow would be:
.IP rdma_create_event_channel
create channel to receive events
.IP rdma_create_id
allocate an rdma_cm_id, this is conceptually similar to a socket
.IP rdma_resolve_addr
obtain a local RDMA device to reach the remote address
.IP rdma_get_cm_event
wait for RDMA_CM_EVENT_ADDR_RESOLVED event
.IP rdma_ack_cm_event
ack event
.IP rdma_create_qp
allocate a QP for the communication
.IP rdma_resolve_route
determine the route to the remote address
.IP rdma_get_cm_event
wait for RDMA_CM_EVENT_ROUTE_RESOLVED event
.IP rdma_ack_cm_event
ack event
.IP rdma_connect
connect to the remote server
.IP rdma_get_cm_event
wait for RDMA_CM_EVENT_ESTABLISHED event
.IP rdma_ack_cm_event
ack event
.P
Perform data transfers over connection
.IP rdma_disconnect
tear-down connection
.IP rdma_get_cm_event
wait for RDMA_CM_EVENT_DISCONNECTED event
.IP rdma_ack_cm_event
ack event
.IP rdma_destroy_qp
destroy the QP
.IP rdma_destroy_id
release the rdma_cm_id
.IP rdma_destroy_event_channel
release the event channel
.P
An almost identical process is used to setup unreliable datagram (UD)
communication between nodes.  No actual connection is formed between QPs
however, so disconnection is not needed.
.P
Although this example shows the client initiating the disconnect, either side
of a connection may initiate the disconnect.
.SH "SERVER OPERATION"
This section provides a general overview of the basic operation for the passive,
or server, side of communication.  A general connection flow would be:
.IP rdma_create_event_channel
create channel to receive events
.IP rdma_create_id
allocate an rdma_cm_id, this is conceptually similar to a socket
.IP rdma_bind_addr
set the local port number to listen on
.IP rdma_listen
begin listening for connection requests
.IP rdma_get_cm_event
wait for RDMA_CM_EVENT_CONNECT_REQUEST event with a new rdma_cm_id
.IP rdma_create_qp
allocate a QP for the communication on the new rdma_cm_id
.IP rdma_accept
accept the connection request
.IP rdma_ack_cm_event
ack event
.IP rdma_get_cm_event
wait for RDMA_CM_EVENT_ESTABLISHED event
.IP rdma_ack_cm_event
ack event
.P
Perform data transfers over connection
.IP rdma_get_cm_event
wait for RDMA_CM_EVENT_DISCONNECTED event
.IP rdma_ack_cm_event
ack event
.IP rdma_disconnect
tear-down connection
.IP rdma_destroy_qp
destroy the QP
.IP rdma_destroy_id
release the connected rdma_cm_id
.IP rdma_destroy_id
release the listening rdma_cm_id
.IP rdma_destroy_event_channel
release the event channel
.SH "RETURN CODES"
.IP "=  0"
success
.IP "= -1"
error - see errno for more details
.P
Librdmacm functions return 0 to indicate success, and a -1 return value
to indicate failure.  If a function operates asynchronously, a return value of 0
means that the operation was successfully started.  The operation could still
complete in error; users should check the status of the related event.  If the
return value is -1, then errno will contain additional information
regarding the reason for the failure.
.P
Prior versions of the library would return -errno and not set errno for some cases
related to ENOMEM, ENODEV, ENODATA, EINVAL, and EADDRNOTAVAIL codes. Applications
that want to check these codes and have compatability with prior library versions
must manually set errno to the negative of the return code if it is < -1.
.SH "SEE ALSO"
rdma_create_event_channel(3), rdma_get_cm_event(3), rdma_create_id(3),
rdma_resolve_addr(3), rdma_bind_addr(3), rdma_create_qp(3),
rdma_resolve_route(3), rdma_connect(3), rdma_listen(3), rdma_accept(3),
rdma_reject(3), rdma_join_multicast(3), rdma_leave_multicast(3), rdma_notify(3),
rdma_ack_cm_event(3), rdma_disconnect(3), rdma_destroy_qp(3), rdma_destroy_id(3),
rdma_destroy_event_channel(3), rdma_get_devices(3), rdma_free_devices(3),
rdma_get_peer_addr(3), rdma_get_local_addr(3),
rdma_get_dst_port(3), rdma_get_src_port(3), rdma_set_option(3)
ucmatose(1), udaddy(1), mckey(1), rping(1)