Remove Ubuntu 18.04 from supported distributions

Ubuntu 18.04 is now in "Extended Security Maintenance", but otherwise
gets no updates. Remove it from supported distributions (regarding
installing packages); users can of course still use it.

Users are encouraged to upgrade to Ubuntu 20+.

CMakeLists.txt

@@ -180,22 +180,6 @@ add_boolean_option(SANITIZE_ADDRESS False "enable the address sanitizer (ASan)"
 if (SANITIZE_ADDRESS)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=address -fno-omit-frame-pointer -fno-common")
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address -fno-omit-frame-pointer -fno-common")
-  # There seems to be some incompatibility with pthread_create and the RT scheduler, which
-  # results in pthread_create hanging.
-  #
-  # When we switch from Ubuntu 16.04 to 18.04, we found that running with the address sanitizer,
-  # the pthread_create function calls were not working. The inital thought was that we were
-  # trying to create a thread that was not-blocking and would eventually crash the machine during
-  # the run. After more debugging, we found that we would never even start the thread. We narrowed
-  # down the first two instances of pthread_create in the gNB and NR UE to be sctp_eNB_task and
-  # one_thread, respectively. We found that adding sleeps, and various other pauses to the threads
-  # had not effect. From there, we found that if we add an abort(); prior to the thread loop, we
-  # do not execute that. This indicated to us that the problem is not likely to be a non-blocking
-  # thread, but perhaps and issue with pthread_create itself. From there we begain to research the
-  # issue on the web. See: https://github.com/google/sanitizers/issues/1125
-  #
-  # Google searching indicates this appears to be a problem since at least 2018. This could be something
-  # wrong in the pthread library, or something subtly wrong in this CMakeLists.txt. Use Ubuntu 20.04 instead.
 endif ()
 
 add_boolean_option(SANITIZE_THREAD False "enable the address sanitizer (TSan)" ON)

README.md

@@ -4,7 +4,6 @@
 
 <p align="center">
     <a href="https://gitlab.eurecom.fr/oai/openairinterface5g/-/blob/master/LICENSE"><img src="https://img.shields.io/badge/license-OAI--Public--V1.1-blue" alt="License"></a>
-    <a href="https://releases.ubuntu.com/18.04/"><img src="https://img.shields.io/badge/OS-Ubuntu18-Green" alt="Supported OS Ubuntu 18"></a>
     <a href="https://releases.ubuntu.com/20.04/"><img src="https://img.shields.io/badge/OS-Ubuntu20-Green" alt="Supported OS Ubuntu 20"></a>
     <a href="https://releases.ubuntu.com/22.04/"><img src="https://img.shields.io/badge/OS-Ubuntu22-Green" alt="Supported OS Ubuntu 22"></a>
     <a href="https://releases.ubuntu.com/24.04/"><img src="https://img.shields.io/badge/OS-Ubuntu24-Green" alt="Supported OS Ubuntu 24"></a>

cmake_targets/build_oai

@@ -418,7 +418,6 @@ function main() {
             CMAKE_CMD="$CMAKE_CMD -DSANITIZE_ADDRESS=True -DSANITIZE_UNDEFINED=True"
             shift;;
         --sanitize-address | -fsanitize=address)
-            grep -sq "Ubuntu 18.04" /etc/os-release && echo_error "Bug in OS with this option, see CMakeLists.txt"
             CMAKE_CMD="$CMAKE_CMD -DSANITIZE_ADDRESS=True"
             shift;;
         --sanitize-undefined | -fsanitize=undefined)

cmake_targets/tools/build_helper

@@ -108,7 +108,6 @@ check_supported_distribution() {
         "ubuntu22.04") return 0 ;;
         "ubuntu21.04") return 0 ;;
         "ubuntu20.04") return 0 ;;
-        "ubuntu18.04") return 0 ;;
         "debian11")    return 0 ;;
         "fedora36")    return 0 ;;
         "fedora37")    return 0 ;;
@@ -322,7 +321,7 @@ check_install_usrp_uhd_driver(){
         $SUDO apt-get remove libuhd3.14.1 -y || true
         $SUDO apt-get remove libuhd3.15.0 -y || true
         local distribution=$(get_distribution_release)
-        if [[ "$distribution" == "ubuntu18.04" || "$distribution" == "ubuntu20.04" || "$distribution" == "ubuntu22.04" ]]; then
+        if [[ "$distribution" == "ubuntu20.04" || "$distribution" == "ubuntu22.04" ]]; then
             $SUDO apt-get remove libuhd4.?.? -y || true
         fi
         v=$(lsb_release -cs)
@@ -352,7 +351,7 @@ check_install_usrp_uhd_driver(){
         $SUDO apt-get update
         $SUDO apt-get -y install python-tk  $boost_libs_ubuntu libusb-1.0-0-dev
         case "$(get_distribution_release)" in
-          "ubuntu18.04" | "ubuntu20.04" | "ubuntu22.04")
+          "ubuntu20.04" | "ubuntu22.04")
             $SUDO apt-get -y install libuhd-dev libuhd4.5.0 uhd-host
             ;;
         esac
@@ -529,24 +528,11 @@ check_install_soapy () {
     install_soapy_iris_from_source
 }
 
-# for ubuntu 18 we need a special repository (https://apt.kitware.com/) to install cmake >= 3.12
-add_cmake_repo () {
-  $SUDO $INSTALLER -y install wget
-  wget -O - https://apt.kitware.com/keys/kitware-archive-latest.asc 2>/dev/null | gpg --dearmor - | $SUDO tee /usr/share/keyrings/kitware-archive-keyring.gpg >/dev/null
-  echo 'deb [signed-by=/usr/share/keyrings/kitware-archive-keyring.gpg] https://apt.kitware.com/ubuntu/ bionic main' | $SUDO tee /etc/apt/sources.list.d/kitware.list >/dev/null
-  $SUDO $INSTALLER -y update
-  $SUDO rm /usr/share/keyrings/kitware-archive-keyring.gpg
-  $SUDO $INSTALLER -y install kitware-archive-keyring
-}
-
 check_install_additional_tools (){
   $SUDO $INSTALLER update -y
   local optional_packages=""
   if [[ "$OS_BASEDISTRO" == "debian" ]]; then
     case "$(get_distribution_release)" in
-        "ubuntu18.04")
-            optional_packages="python-dev python-pip python-pyroute2 python python-numpy python-scipy python-matplotlib ctags"
-            ;;
         "ubuntu20.04" | "ubuntu21.04" | "ubuntu22.04" | "debian11" )
             optional_packages="python3 python3-pip python3-dev python3-scipy python3-matplotlib python3-pyroute2 universal-ctags"
             ;;
@@ -587,10 +573,6 @@ check_install_oai_software() {
   if [[ "$OS_BASEDISTRO" == "debian" ]]; then
     $SUDO apt install -y software-properties-common
     case "$(get_distribution_release)" in
-        "ubuntu18.04")
-            add_cmake_repo
-            specific_packages=""
-            ;;
          "debian11")
             specific_packages="libz-dev"
             ;;