Changes between Version 12 and Version 13 of troubleshooting

Timestamp:

Feb 18, 2019, 2:14:19 PM (7 years ago)

Author:

Sanahuja Guillaume

Comment:

--

troubleshooting

@@ -21 +21 @@
 * check if ''/dev/shm'' is clean. It should not contain files like ''sem.simu_*'' or ''simu_*''. The files are shared memories between control and simulation part; they should be destroyed when all programs are closed. You can safely remove it manually if not.
 * if problem is still present, make [https://devel.hds.utc.fr/software/flair/newticket a new ticket] describing your problem and the output message of the simulator.
+
+== Simulator does not start (libGL error) ==
+
+If you have a message like this one at executing the simulator:
+{{{
+libGL error: unable to load driver: i965_dri.so
+}}}
+
+The idea is that we're using the system video card driver since it's not included in robomap3.
+
+The driver itself (eg: i965_dri.so) should be loaded automatically (from /usr/lib/x86_64-linux-gnu/dri/). But this driver may not succesfully load since it requires some specific library versions that may not match robomap3's.
+
+To debug this you should launch your 3D graphic program (eg: simulator) with the LIBGL_DEBUG environment variable set to verbose. 
+For example
+{{{
+$ LIBGL_DEBUG=verbose ./LineFollower_simulator_nrt -n x4_0 -t x4 -a 127.0.0.1 -p 9000 -x setup_x4.xml (...)
+}}}
+Notice the line that look like {{{ libstdc++.so.6: version `CXXABI_1.3.9' not found (required by /usr/lib/x86_64-linux-gnu/dri/i965_dri.so) }}}.
+This means that the local system driver needs a version of libstdc++.so.6 that defines the symbol CXXABI_1.3.9 (meaning application binary interface version 1.3.9).
+The version of libstdc++ included in robomap3 probably doesn't define this symbol. You can make sure with 
+{{{
+strings /.../robomap3/1.7.3/core2-64/sysroots/core2-64-poky-linux/usr/lib/libstdc++.so.6 | grep CXXABI_ 
+}}}
+So we need to preload the libstdc++ library of the system to avoid robomap3 one to be loaded. 
+To achieve this we need to set the LD_PRELOAD environment variable like this
+{{{
+LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libstdc++.so.6 ./LineFollower_simulator_nrt ...
+}}}
+
+
+Stopping here may be enough, but you then can see errors like {{{ i965_dri.so: undefined symbol: nouveau_drm_new }}}.
+
+Same problem: the driver needs a version of a library (here libdrm_nouveau.so.2) which defines a specific symbol that doesn't exist in robomap3 version (yet).
+
+Same solution: preload the local system library.
+Repeat this until all unresolved symbols are gone.
+
+* On ubuntu 16.10 with robomap3 1.7.3, I ended up with the following
+{{{
+LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libstdc++.so.6:/usr/lib/x86_64-linux-gnu/libdrm_intel.so.1:/usr/lib/x86_64-linux-gnu/libdrm_nouveau.so.2:/usr/lib/x86_64-linux-gnu/libdrm_radeon.so.1  ./LineFollower_simulator_nrt -n x4_0 -t x4 ...
+}}}
+
+* On mint 19.1 with robomap 2.1.3, I ended up with the following
+{{{
+LD_PRELOAD=/lib/x86_64-linux-gnu/libm.so.6:/usr/lib/x86_64-linux-gnu/libstdc++.so.6 ./LineFollower_simulator_nrt -n x4_0 -t x4 ...
+}}}
+
+
+To avoid setting this variable every time, you can modify the script used to launch the program (usually in build/bin, eg: simulator_xx.sh) and add this line __after__ the first one
+{{{
+export LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libstdc++.so.6:/usr/lib/x86_64-linux-gnu/libdrm_intel.so.1:/usr/lib/x86_64-linux-gnu/libdrm_nouveau.so.2:/usr/lib/x86_64-linux-gnu/libdrm_radeon.so.1
+}}}
 
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