hi,
i am starting the twothreads example with
gdb 5.0 and doing a break (ctrl-c).
After 'bt' prints some frames i got
Reply contains invalid hex digit 84
Turning debugging on shows that gdb
tries to dereference 0xdeadbeef.
Its clear why the stub is causing
an exception invoking himself again
I know you've identified the stack checking as the reason, but it's not
really the cause (other than GDB's stack guesswork), so there's still
another interesting issue with this: the stub shouldn't barf. There's
meant to be code to catch this (see cyg_hal_exception_handler() in
hal/powerpc/arch/current/src/hal_misc.c - look at the stuff at the top
about __mem_fault_handler).