2011/9/10 Simson Garfinkel <simsong(a)acm.org&gt;: Well, this depends on the runtime-version you are using. Newer version supports TLS-callbacks and so -mthreads is an nop-operation for them, but for older runtime-versions it is mandatory to use it for multi-threaded applications, which are using C++. You should make sure in general to use shared libgcc and libstdc++, if you are building an C++ application. This avoids some troubles you otherwise might get into. The pthread library doesn't depend on the -mthreads feature. So in doubt, specify the -mthreads option and the additional the options -shared-libgcc -shared-libstdc++. Regards, Kai