core dump support in gdb

The gdb versions I have used on mipsel-linux do not seem to be able to read a core file generated on the same platform failing with

warning: Hit heuristic-fence-post without finding
warning: enclosing function for address 0x20008413

Anyone know what the problem is?
Increasing the value of heuristic-fence-post does not help. The address mentioned seems not to exist in the address space of the program. Running the program from within gdb seems however to give meaningful results when the program crashes.

/Brian