Hi All I compiled my application with gcc4.2.4 and I keep getting spin lock errors. The same application, when compiled with gcc 4.1.1, had no issues. I am using -march=pentiumpro as compile option as I am using __sync_lock_test_and_set() calls for spin locks. Any reason that these errors should occur when application is compiled with 4.2.4? I would very much appreciate your help and advice. With Regards Vardhan