The svc_run routine calls the select routine to wait for RPC
    requests. When a request arrives, svc_run calls the svc_getreqset
    routine. Then svc_run calls the select routine again.

    The svc_run routine never returns.

    You may use the global variable svc_fdset with the svc_run
    routine. See the svc_getreqset routine for more information about
    svc_fdset.