-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Which gcc version? __sync_fetch_and_add_4 is a gcc intrinsic, and it's never called directly by Boost code (__sync_fetch_and_add is call, gcc expands that to a macro which selects the right version of __sync_fetch_and_add to invoke). This sounds like a problem with your toolchain, not with Boost. You might be neglecting a flag to gcc to properly target 32bit. I could be mistaken about this - the only place in boost that __sync_fetch_and_add is called is in smart_ptr and interprocess, so I'm assuming that your problem is in one of those calls. - -- Bryce Lelbach aka wash boost-spirit.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAk04VzMACgkQ9cB/V3/s9ExVnQCeMvjvPvZ8qVJ6VQ7vjue6ueto upkAnicWX20T8plS3986lfl3bMOKujvb =rSsQ -----END PGP SIGNATURE-----