labs/sysdev-application-development-and-debugging: document gdb warnings

Signed-off-by: Michael Opdenacker <[email protected]>
Reported-by: Mark Long <[email protected]>

labs/sysdev-application-development-and-debugging/sysdev-application-development-and-debugging.tex

@@ -219,10 +219,27 @@ \section{Post mortem analysis}
 target to get a \code{core.xxx} file dumped when you run
 \code{nunchuk-mpd-client} again.
 
-Once you have such a file, inspect it with \ifdefstring{\labboard}{beagleplay}{\code{aarch64-linux-gdb}}{\code{arm-linux-gdb}} on
-the host, set the \code{sysroot} setting, and then generate
-a backtrace to see where the program crashed.
+Once you have such a file, inspect it with \ifdefstring{\labboard}{beagleplay}{\code{aarch64-linux-gdb}}{\code{arm-linux-gdb}}
+on the host as explained in the lectures.
 
+Don't be surprised, the below warnings are expected:
+
+{\small
+\begin{verbatim}
+warning: Can't open file /root/nunchuk-mpd-client during file-backed mapping note processing
+
+warning: Can't open file /usr/lib/libc.so.6 during file-backed mapping note processing
+
+warning: Can't open file /usr/lib/libmpdclient.so.2.20 during file-backed mapping note processing
+
+warning: Can't open file /usr/lib/ld-linux-armhf.so.3 during file-backed mapping note processing
+
+warning: core file may not match specified executable file.
+\end{verbatim}
+}
+
+In the \code{gdb} shell, set the \code{sysroot} setting as previously, and then
+generate a backtrace to see where the program crashed.
 You can even see the value of all variables in the different
 function contexts of your program: