There are several outstanding tickets (2114, 2309, 3697) dealing with GCC symbol visibility across shared libraries (DSO's on UNIX-like systems, DLL's on Windows-like systems). A particular problem that is affecting several Boost libraries (system, filesystem, threads, etc) is that with compiler switch -fvisibility=hidden an exception thrown in one library cannot be caught in another library or in the main program. For more background, see http://gcc.gnu.org/wiki/Visibility Ticket 2114 provided patches to fix the problem, and work started on getting them ready for trunk. But that work seems to have stalled. See http://svn.boost.org/trac/boost/ticket/2114 What needs to be done to restart this effort? It would be better is discussion could occur on this list, rather than as comments attached to the ticket. That will ensure more eyeballs look at this. --Beman