Add a DEBUGGER_ON_POWERFAIL option. This makes the power button on ultra 10s

work like an NMI button.

sys/conf/options.sparc64

@@ -8,6 +8,7 @@ PANIC_REBOOT_WAIT_TIME	opt_panic.h
 EBUS_DEBUG		opt_ebus.h
 PSYCHO_DEBUG		opt_psycho.h
 PSYCHO_STRAY		opt_psycho.h
+DEBUGGER_ON_POWERFAIL	opt_psycho.h
 OFW_PCI_DEBUG		opt_ofw_pci.h
 # Normal IOMMU debugging
 IOMMU_DEBUG		opt_iommu.h

sys/sparc64/pci/psycho.c

@@ -760,8 +760,15 @@ psycho_powerfail(void *arg)
 {
 
 	/* We lost power.  Try to shut down NOW. */
+#ifdef DEBUGGER_ON_POWERFAIL
+	struct psycho_softc *sc = (struct psycho_softc *)arg;
+
+	Debugger("powerfail");
+	PSYCHO_WRITE8(sc, PSR_POWER_INT_CLR, 0);
+#else
 	printf("Power Failure Detected: Shutting down NOW.\n");
 	shutdown_nice(0);
+#endif
 }
 
 #ifdef PSYCHO_MAP_WAKEUP