this problem came from trying to create a 64bit executable using 32bit libraries. It seems that bjam does not find the compiler via the path environment variable but somehow directly and thus by default found the 32bit compiler and created 32bit libraries ________________________________ From: FOELSCHE,PETER (A-SantaClara,ex1) Sent: Wednesday, April 30, 2008 17:27 To: 'boost-users@lists.boost.org' Subject: undefined symbols ------ Build started: Project: boost_memory_mapped_io, Configuration: Release x64 ------ Linking... main.obj : error LNK2001: unresolved external symbol "class boost::filesystem::file_status __cdecl boost::filesystem::detail::status_api(class std::basic_string const &,class boost::system::error_code &)" (?status_api@detail@filesystem@boost@@YA?AVfile_status@23@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@AEAVerror_code@system@3@@Z) main.obj : error LNK2001: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_system_category(void)" (?get_system_category@system@boost@@YAAEBVerror_category@12@XZ) main.obj : error LNK2001: unresolved external symbol "class boost::system::error_category const & __cdecl boost::system::get_posix_category(void)" (?get_posix_category@system@boost@@YAAEBVerror_category@12@XZ) main.obj : error LNK2001: unresolved external symbol "struct std::pair __cdecl boost::filesystem::detail::file_size_api(class std::basic_string const &)" (?file_size_api@detail@filesystem@boost@@YA?AU?$pair@Verror_code@system@boost@@_K@std@@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@5@@Z) C:\DocumentsAndSettings\pfoelsch\MyDocuments\boost_memory_mapped_io\x64\Release\boost_memory_mapped_io.exe : fatal error LNK1120: 4 unresolved externals Build log was saved at "file://c:\DocumentsAndSettings\pfoelsch\MyDocuments\boost_memory_mapped_io\boost_memory_mapped_io\x64\Release\BuildLog.htm" boost_memory_mapped_io - 5 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== see attached main.cpp I link with boost_system-vc80-mt-1_35.lib boost_filesystem-vc80-mt-1_35.lib and other boost libraries which are referenced directly. I work on 64bit XP compiling for 64bit.