M. Koehrer wrote:
> Hi Jan, 
> 
> here is the result - I have logged with a serial console (as my kernel freezes).
> There are many printk messages...
> 
> I hope that helps a little bit

Not yet (was a silly patch, please revert first). Another try

--- linux-2.6.20.orig/include/asm-i386/ipipe.h
+++ linux-2.6.20/include/asm-i386/ipipe.h
@@ -262,6 +262,9 @@ static inline unsigned long __ipipe_ffnz
 do { \
 	local_irq_enable_nohead(ipd);				 \
 	if (ipd == ipipe_root_domain) {				 \
+if (!ipd->irqs[irq].handler) { \
+	ipipe_set_printk_sync(ipd); printk("irq=%d\n", irq); BUG(); \
+}; \
 		if (likely(!ipipe_virtual_irq_p(irq))) {	 \
 			__ipipe_call_root_xirq_handler(ipd,irq); \
 		} else {					 \