GDB does not see any threads besides

Question

GDB does not see any threads besides the one in which crash occurred; or SIGTRAP kills my program when I set a breakpoint.

Answer 1

This frequently happen on Linux, especially on embedded targets. There are two common causes:

• you are using glibc, and you have stripped libpthread.so.0
• mismatch between libpthread.so.0 and libthread_db.so.1

GDB itself does not know how to decode "thread control blocks" maintained by glibc and considered to be glibc private implementation detail. It uses libthread_db.so.1 (part of glibc) to help it do so. Therefore, libthread_db.so.1 and libpthread.so.0 must match in version and compilation flags. In addition, libthread_db.so.1 requires certain non-global symbols to be present in libpthread.so.0.

Solution: use strip --strip-debug libpthread.so.0 instead of strip libpthread.so.0.

If you are doing remote debugging, make sure libpthread.so.0 on target and libthread_db.so.1 on host match.