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.

This work was done by Laurent Thomas.

On some hosts, compilations with the T tracer was failing.

The error was:
  common/utils/T/T.h:15:19: fatal error: T_IDs.h: No such file or directory

The problem was that in CMakeLists.txt some targets depend on the
pre-generation of T_IDs.h but this dependancy relation was not set,
so those targets could be generated before the T (it was the case
with HASHTABLE).

This commit fixes that. Basically, we take all the targets found in
"add_executable" and "add_library" and make them depend on the
T if the T is enabled. Almost all existing targets were added,
even those that may not need it.

The problem of this approach is that someone adding a new target
using the T will not necessarily add a dependancy there.

Another solution would be to generate T_IDs.h at "cmake" stage,
not "make" stage and use an "if (NOT EXISTS T_IDs.h)" to generate
the file. We lose the dependancy relation though.

Things may be changed if maintenance cost is too high.

This reverts commit d31634c3.

Laurent Thomas had a problem on one machine with the build_oai
way of checking for nettle.

The problem with the alternative solution of including nettle/bignum.h
is that it is very unclear.

The problem with nettle is that the file nettle/config.h does not
exist for version 2. It was introduced in version 3.

We want to support both versions, but there is an API incompatibility.
So we need an #if #else mechanism.

The file nettle/bignum.h is present in both versions 2 and 3 and it
includes nettle/version.h in the version 3.

So by including this file, we can check for the existence of
NETTLE_VERSION_MAJOR (that comes from nettle/config.h) in the
code.

But as you can see, the reasoning is way too complex.

So it's better to keep the check in cmake_targets/CMakeLists.txt.

As long as we support version 2 this will be the way to go.

It is possible to force a given version in specific non-generic
customized environments.

when testing on haswell, using apt-get to install LimeSDR
libraries and includes, it put it in /usr/include, not
/usr/local/include

As reported on the mailing list, there was a problem
for some users. The link phase of building the simulators
was giving the error "undefined reference to ATL_scopy".

Another way to set those two variables has to be used for the
specific UE case (use a sub CMakeLists.txt, see in build_oai).

debugging information in lte-enb, addition of external reference option in lte-softmodem and usrp_lib.cpp

- add progess bar report
- reduce ssh max_tries to 10
- cleanOldPrograms -> change kill cmd line to be able to run autotest on same machine than lte-softmodem (thanks Rohit & Gabriel)
- Cleanning output prints
- add --skip-machine-preparation on cmd line
- add --skip-sanity-check on cmd line
- add HTML REPORT (no-S1 only)
- add XML detailled report (no-S1 only)

           1- Implement SRS procedures

The text has been updated in all those files.

	modified:   README.txt
	modified:   cmake_targets/CMakeLists.txt
	modified:   cmake_targets/at_commands/CMakeLists.txt
	modified:   cmake_targets/autotests/core.py
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	modified:   cmake_targets/autotests/run_exec_lte-softmodem_tests.py
	modified:   cmake_targets/autotests/tools/configure_cots_bandrich_ue.py
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	modified:   openair2/DOCS/TEMPLATES/README/Readme.doxy
	modified:   openair2/DOCS/TEMPLATES/README/readme.txt
	modified:   openair2/Makefile
	modified:   openair2/UTIL/OCG/Readme.doxy
	modified:   openair2/UTIL/OCG/readme.txt
	modified:   openair2/UTIL/OSD/recep.php
	modified:   openair2/X2AP/MESSAGES/ASN1/asn1tostruct.py
	modified:   openair3/DOCS/DOXYGEN/Makefile.am
	modified:   openair3/DOCS/Latex/EPC/Makefile
	modified:   openair3/DOCS/Makefile.am
	modified:   openair3/GTPV1-U/Makefile.am
	modified:   openair3/GTPV1-U/Makefile.eNB
	modified:   openair3/NAS/TEST/AS_SIMULATOR/Makefile
	modified:   openair3/NAS/TEST/NETWORK/Makefile
	modified:   openair3/NAS/TEST/USER/Makefile
	modified:   openair3/NAS/TOOLS/Makefile
	modified:   openair3/NAS/UE/API/USER/Makefile
	modified:   openair3/NAS/UE/API/USER/tst/Makefile
	modified:   openair3/NAS/UE/API/USIM/Makefile
	modified:   openair3/S1AP/MESSAGES/ASN1/asn1tostruct.py
	modified:   openair3/TEST/Makefile.am
	modified:   targets/ARCH/EXMIMO/USERSPACE/OCTAVE/gpib_send.cc
	modified:   targets/ARCH/EXMIMO/USERSPACE/OCTAVE/oarf_config_exmimo.cc
	modified:   targets/ARCH/EXMIMO/USERSPACE/OCTAVE/oarf_get_frame.cc
	modified:   targets/ARCH/EXMIMO/USERSPACE/OCTAVE/oarf_get_num_detected_cards.cc
	modified:   targets/ARCH/EXMIMO/USERSPACE/OCTAVE/oarf_send_frame.cc
	modified:   targets/ARCH/EXMIMO/USERSPACE/OCTAVE/oarf_stop.cc
	modified:   targets/ARCH/EXMIMO/USERSPACE/OCTAVE/oarf_stop_without_reset.cc
	modified:   targets/PROJECTS/E-MBMS/build_all.bash
	modified:   targets/PROJECTS/E-MBMS/start_enb.bash
	modified:   targets/PROJECTS/E-MBMS/start_ue.bash
	modified:   targets/PROJECTS/E-MBMS/utils.bash
	modified:   targets/PROJECTS/GENERIC-LTE-EPC/interfaces.bash
	modified:   targets/PROJECTS/GENERIC-LTE-EPC/networks.bash
	modified:   targets/PROJECTS/GENERIC-LTE-EPC/start_enb_and_ue_virt.bash
	modified:   targets/PROJECTS/GENERIC-LTE-EPC/start_ue.bash
	modified:   targets/PROJECTS/GENERIC-LTE-EPC/utils.bash
	modified:   targets/PROJECTS/GENERIC-LTE-EPC/virtual_box.bash
	modified:   targets/SCRIPTS/install_asn1c_0.9.24.modified.bash
	modified:   targets/TEST/OAI/case01.py
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	modified:   targets/TEST/OAI/core.py
	modified:   targets/TEST/OAI/log.py
	modified:   targets/TEST/OAI/openair.py
	modified:   targets/TEST/OAI/test01.py
	modified:   targets/TEST/OAI/test02.py
	modified:   targets/TEST/PDCP/readme.txt
	modified:   targets/build_helper.bash
	modified:   targets/build_oai.bash
	modified:   targets/perf_oai.bash