I suspect this is a FAQ, but can anyone give me clues about how
to use gdb to rake over the remains of deceased kernels?

I have the crash dump and I can load it into gdb. The problem is that
the backtrack it totally uninformative. It always shows the current location
as in mi_switch as if this function has been spontaneously called (probably
from assembly code routine. I had naively hoped to go up frames until
I found the point panic was called.

I have found the gdbscripts directory but I can't see anything which would
let me find and switch to another stack.

Any clues appreciated.

Ian