A quick note in haste. Seems that I had ulimit still slightly too small. Trying to get a backtrace on a full core ($ ls -ltrh core -rw------- 1 ael ael 229M Oct 12 11:06 core ) gives: (gdb) bt #0 0x00007f623be8957c in ?? () Backtrace stopped: Cannot access memory at address 0x7fff724b0460 ael