> serial port, the CPU receives NMI exception, and we fall into KDB shell. > So, it is our "debug console", and it is able to interrupt (and thus > debug) even IRQ handlers themselves. You seem to have an assumption of single core here. What happens if the NMI hits CPU #0 and the serial IRQ hits CPU #1 simultaneously ? Alan -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html