Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

This work is based on feedback from Thomas Schlichter.
His comments and suggestions were made just after the original MR was merged.

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

It looks like :
  - when running on a Fedora-host
  - with generic kernel
  - in a container
  - even in privileged mode

That is not enough and priority/schedule settings is not allowed.

So at runtime, we check and in case, we don't set up priorities.

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Mainly comestics and integer type management

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

For whatever reason most of the files had their permission
changed from 644 to 755, which is not wanted.

see oai/openairinterface5g#227

When the UE connects to the eNodeB and receives its IP address from the
network, it calls system() to set it in the linux kernel world. This call
is not done in a realtime thread, but in the NAS, which uses its own thread,
independent of the realtime processing.

In some situations this totally disrupts realtime processing.

It is difficult to know precisely why that happens, but it seems that calling
fork(), as system() does, in a multi-threaded program is not a good idea. (So
say several people on the internet.) It is not clear why the softmodem is
impacted, but it seems that fork() is really what triggers the disruption.
Several tests lead to that conclusion.

To fix the problem, we create a child background process very early in main()
(before anything else basically). Then instead of calling system(), the main
process sends the string to the background process. The background process
gets the string, passes it to system() and reports the success/failure back
to the main process.

This solution involves a lot of system calls, but calling system() in the
first place is not cheap either. As long as no realtime thread uses this
mechanism, things should be fine. Time will tell.