As you can see at http://www.boost.org/development/tests/master/developer/asio.html, there are many fails on Android/x86, when tests are built by clang. There was ticket filed to CrystaX NDK tracker about that: https://tracker.crystax.net/issues/912. After some research, I've found reason of fails and created pull request for Boost.Asio: https://github.com/boostorg/asio/pull/17. Shortly speaking, there is intersection of several bugs - one is inability of clang to emulate thread-local variables without support from underlying runtime (gcc can do that), and second is misconfiguration in Boost.Asio headers. I've tested locally with change from https://github.com/boostorg/asio/pull/17 and all '___tls_get_addr' errors disappeared. Now I'm waiting for that pull request to be merged into upstream, but I don't see any activity in Boost.Asio repository. Is there something wrong with my pull request? It's very simple so I wonder why it not yet merged? I'd like to see it merged to the upstream (including 'master') before 1.58 release - just because this bug cause not only Boost.Asio fails, but several others libraries too. -- Dmitry Moskalchuk