Ubuntu 10.10, GDB 7.2. I attach to an application, watch stacks in every thread, everything looks good. Do generate-core-file and try to open that coredump in gdb. No routines is shown in backtraces.
I send SIGSEGV to the application and open this new coredump in gdb. Stacks are ok and verbose.
Please tell me if you experienced a similar incorrect behaviour of generate-core-file.
This is a known bug in GDB. The link has also a patch for fixing the problem.