Package: linux-image-4.9.0-3-rt-amd64 Version: 4.9.30-2+deb9u2 With the current and all previous rt-kernel package for debian 9 it is almost impossible to use gdb for debugging. Kernel.release: 4.9.30-rt20 Known issues in rt-20-patch : gdb. While gdb is following a task it is possible that after a fork() operation the task is waiting for gdb and gdb waiting for the task. In rt-21-patch the problem is solved! My wish: using rt-21-patch or newer in next update Thanks for attention