added linux README

cmake/scripts/BeagleBoneBlack/crosscompile/make-debug-cfg.sh

@@ -3,11 +3,11 @@ counter=0
 cfg_script_name="cmake-build-cfg.py"
 while [ ${counter} -lt 5 ]
 do
-    cd ..
     if [ -f ${cfg_script_name} ];then
         break
     fi
     counter=$((counter=counter + 1))
+    cd ..
 done
 
 if [ "${counter}" -ge 5 ];then

doc/README-bbb.md

@@ -22,7 +22,7 @@ more quickly.
 
 1. SSH connection to the Beagle Bone Black working 
 2. Beagle Bone Black linux environment set up properly
-3. `CMake` installed
+3. `cmake` installed
 
 ## Setting up general prerequisites for Linux systems
 

doc/README-linux.md

@@ -0,0 +1,51 @@
+# Raising Message Queue Size Limit
+
+The FSFW requires a higher message queue maximum lenght than the regular
+value configured for Linux. Failure to adjust this limit will cause
+errors when running FSFW applications.
+
+The following steps raise the maximum allowed message queue length to a higher
+number permanently, which is  required for some framework components. The recommended
+values for the new message length is 130.
+
+2. Edit the /etc/sysctl.conf file
+```sh
+sudo nano /etc/sysctl.conf
+```
+Append at end: 
+```sh
+fs/mqueue/msg_max = <newMsgMaxLen>
+```
+Apply changes with: 
+```sh
+sudo sysctl -p
+```
+
+A possible solution which only persists for the current session is
+```sh
+echo <newMsgMax> | sudo tee /proc/sys/fs/mqueue/msg_max
+```
+
+# Setting up UNIX environment for real-time functionalities
+
+Please note that on most UNIX environments (e.g. Ubuntu), the real time functionalities 
+used by the UNIX pthread module are restricted, which will lead to permission errors when creating these tasks
+and configuring real-time properites like scheduling priorities.
+If you use the real time scheduler in Linux, perform the following steps:
+
+Edit the /etc/security/limits.conf file and add following lines at the end:
+
+```sh
+<username>   hard   rtprio  99
+<username>   soft   rtprio  99
+```
+The soft limit can also be set in the console with `ulimit -Sr` if the hard
+limit has been increased, but it is recommended to add it to the file as well
+for convenience. If adding the second line is not desired for security reasons,
+the soft limit needs to be set for each session. If using an IDE like eclipse 
+in that case, the IDE needs to be started from the console after setting
+the soft limit higher there. After adding the two lines to the file,
+the computer needs to be restarted.
+
+It is also recommended to perform the following change so that the unlockRealtime
+script does not need to be run anymore each time.