+ XBT_ERROR(" (ucontext was disabled at compilation time on this machine -- check configure logs for details)");
+#endif
+#ifdef HAVE_BOOST_CONTEXT
+ XBT_ERROR(" boost: this uses the boost libraries context implementation");
+#else
+ XBT_ERROR(" (boost was disabled at compilation time on this machine -- check configure logs for details. Did you install the libboost-context-dev package?)");