Hello,

> I also think this snippet is mighty interesting... note comment.
> 
> void GrandCentralInterruptController::enableVector(long vectorNumber,
> 						   IOInterruptVector *vector)
> {
>   unsigned long     maskTmp;
>   
>   maskTmp = lwbrx(maskReg);
>   maskTmp |= (1 << vectorNumber);
>   stwbrx(maskTmp, maskReg);
>   eieio();
>   if (lwbrx(levelsReg) & (1 << vectorNumber)) {
>     // lost the interrupt
>     causeVector(vectorNumber, vector);
>   }
> }

Yes, this agrees with the comment from Linux I posted earlier - if you enable an interrupt and its line is already active it won't fire. I've added something similar without apparent change but my code might be wrong ( I just marked the interrupt as pending in this case so it would be called soon enough ). We can't call it directly because that would disrupt the priority handling, but when we enable an interrupt it's because it was marked pending and got disabled temporarily so we're going to call its handler anyway and won't (really) lose interrupts because of this.

have fun
Michael