GDB's gcore command doesn't work / needs to be implemented / ported in GDB:

tschwinge@flubber:~ $ gcore 8371
[New Thread 8371.1]
[New Thread 8371.2]
[New Thread 8371.3]
/media/data/home/tschwinge/core.cA0ICY:2: Error in sourced command file:
Undefined command: "gcore".  Try "help".
gcore: failed to create core.8371

Will probably need to implement gdb/, gdb/

If someone is working in this area, they may want to port, too.