-XBT_PUBLIC(void) SIMIX_req_comm_set_copy_data_callback(void (*callback)(smx_action_t,size_t));
-XBT_PUBLIC(void) SIMIX_req_comm_copy_pointer_callback(smx_action_t comm, size_t buff_size);
-XBT_PUBLIC(void) SIMIX_req_comm_copy_buffer_callback(smx_action_t comm, size_t buff_size);