Am Donnerstag, 13. Januar 2011, 02:10:12 schrieb Darren Hollenbeck: > I am using CMake to cross compile with an arm toolchain and getting a > linker error: > undefined reference to `__sync_fetch_and_add_4' > > the toolchain has both a shared and static libgcc: > ./lib/gcc/arm-linux-gnueabi/4.5.2/libgcc.a > ./lib/gcc/arm-linux-gnueabi/4.5.2/libgcc_eh.a > ./arm-linux-gnueabi/lib/libgcc_s.so.1 > ./arm-linux-gnueabi/lib/libgcc_s.so > > the path for both is in the linker directories (from CMakeCXXCompiler.cmake > generated in the build directory/CMakeFiles), but the path for the static > is first: > SET(CMAKE_CXX_IMPLICIT_LINK_DIRECTORIES > "/opt/gatecraft/arm/lib/gcc/arm-linux-gnueabi/4.5.2;/opt/gatecraft/arm/arm- > linux-gnueabi/lib;/opt/gatecraft/arm/arm-linux-gnueabi/usr/lib")
Does this matter? No, the libraries have differen names! > The libraries are not the same, the .so does not have the symbol the linker > is complaining about but the .a does (I inspected this with nm). What I > can't figure out is why I can switch the CMAKE_CXX_COMPILER defined in my > toolchain file to another toolchain (with the same shared/static and linker > path order) - keeping everything else the same - and the build succeeds. I > can't find any significant difference in anything in the build directory > between the two, yet one will link libgcc.a (and therefore works) and the > other won't (and gives the error above). > > I found that I have a work-around by forcing -static-libgcc in the linker > flags, but this doesn't explain why it works without this change when I > switch the compiler to the other toolchain. > > > Anyone able to explain the discrepancy here and offer a fix? You probably have different defaults (by gcc configure flags) for code generation. Anyway, this is a problem either with gcc itself, how you configured it or a problem with use a atomic operations in your code. Totally unrelated to cmake. HS _______________________________________________ Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Follow this link to subscribe/unsubscribe: http://www.cmake.org/mailman/listinfo/cmake
