from extintr.c

        /*
         * Initialize the soft interrupt masks to block themselves.
         */
        imask[IPL_SOFTCLOCK] = SINT_SERIAL;
        imask[IPL_SOFTNET] = SINT_NET;
        imask[IPL_SOFTSERIAL] = SINT_SERIAL;


I suppose imask[IPL_SOFTCLOCK] should be initialized to SINT_CLOCK and
not something else ?


regards, Andreas