Hmm, you could make the watchdog send a SIGSTOP to the main thread and offer the user to either stop the DSP (and do SIGCONT), start GDB, or quit PD... ? Maybe a 4th option would be to "pause (inhibit) all t_clocks (and do SIGCONT)" ?)
i was thinking about switching of dsp and closing the audio interfaces ... still, i hope the watchdog will be obsolete soon due to the rt-limit kernel patches ...
cheers ... tim