Hardcode (noS1) PDU session ID to 10

Defacto, the PDU session ID for noS1 modes is already hardcoded, as
starting the nr-softmodem with --noS1 --default-pdu-id 1 leads to

    Assertion (entity != ((void *)0)) failed!
    In start_sdap_tun_gnb_first_ue_default_pdu_session() openair2/SDAP/nr_sdap/nr_sdap.c:163

Further, the --default-pdu-id parameter will be deactivated in a later
commit, and we cannot rely on it. Therefore:

- hardcode noS1 PDU ID (also used in --do-ra/--phy-test modes) to 10 and
  use in gNB&UE
- pass the PDU session ID used in SDAP entity initialization down to
  start_sdap_tun_gnb_first_ue_default_pdu_session() to always use the
  correct one

openair2/SDAP/nr_sdap/nr_sdap.c

@@ -157,9 +157,9 @@ static void *sdap_tun_read_thread(void *arg)
   return NULL;
 }
 
-void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id)
+void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id, int pdu_session_id)
 {
-  nr_sdap_entity_t *entity = nr_sdap_get_entity(ue_id, get_softmodem_params()->default_pdu_session_id);
+  nr_sdap_entity_t *entity = nr_sdap_get_entity(ue_id, pdu_session_id);
   DevAssert(entity != NULL);
   DevAssert(entity->is_gnb);
   char *ifprefix = get_softmodem_params()->nsa ? "oaitun_gnb" : "oaitun_enb";

openair2/SDAP/nr_sdap/nr_sdap.h

@@ -60,7 +60,7 @@ void sdap_data_ind(int pdcp_entity,
                    char *buf,
                    int size);
 
-void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id);
+void start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id_t ue_id, int pdu_session_id);
 void create_ue_ip_if(const char *ipv4, const char *ipv6, int ue_id, int pdu_session_id);
 
 #endif

openair2/SDAP/nr_sdap/nr_sdap_entity.c

@@ -534,7 +534,7 @@ static void nr_sdap_add_entity(const int is_gnb, const ue_id_t ue_id, const sdap
   if (IS_SOFTMODEM_NOS1 && is_gnb) {
     // In NOS1 mode, terminate SDAP for the first UE on the gNB. This allows injecting/receiving
     // PDCP SDUs to/from the TUN interface.
-    start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id);
+    start_sdap_tun_gnb_first_ue_default_pdu_session(ue_id, sdap_entity->pdusession_id);
   }
 }