Hello, I get the error below compiling with (Xcode 2.5 / OS X 10.4.11) only for PPC arch. boost_1_53_0/boost/atomic/detail/gcc-ppc.hpp:1204: error: impossible constraint in 'asm' The related code is: static boost::atomic<long> messageCount_(0); number_ = messageCount_.fetch_add(1, boost::memory_order_relaxed); Is this a known bug ? Is there any way to fix it ? Thanks.