It does not depend on the OS. The difference in the scenario. In my case it is a relatively small test program and a number of relocatable libraries in Ada or not. GDB seems uncapable to step into a library. I do not expect it to step into the libraries with MS symbols, e.g. to use pdb files, however ObjectAda did that. But it cannot even do that with the libraries built by the GCC toolchain with -g.