add preeliminary support for ubuntu 20 or debian 11, add file for 5G SA

openair2/RRC/NR/nr_rrc_gNB.c

+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Author and copyright: Laurent Thomas, open-cells.com
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+rrc_gNB_send_NGAP_NAS_FIRST_REQ() {
+   // We are noCore only now
+   // create message that should come from 5GC
+  
+   // send it dow
+   rrc_gNB_process_NGAP_DOWNLINK_NAS()
+}
+
+rrc_gNB_process_NGAP_DOWNLINK_NAS () {
+   do_DLInformationTransfer();
+   // send it as DL data
+    rrc_data_req (
+      &ctxt,
+      srb_id,
+      (*rrc_eNB_mui)++,
+      SDU_CONFIRM_NO,
+      length,
+      buffer,
+      PDCP_TRANSMISSION_MODE_CONTROL);
+
+}
+
+
+:q
+