'gdb can't read core files on this machine'

[walt <wa1ter@xxxxxxxxxxxxx>]

After updating world/kernel on -current today, I just got
a panic when trying to exit from X.  On reboot the machine
saved a core in /var/crash, but I can't seem to do anything
with it.

I tried gdb --kernel -c vmcore.0 and a few other variations
but I always get the same error message.

Any ideas?