>
> > > The kernel should _not_ enable these bits as it would break lots of systems
> > > having non-parity memory.
> >
> > How?
>
> This would probably enable the parity checks there causing approx. half of all
> memory accesses to cause NMI.
>
> Conclusion: We should not enable these bits explicitly and we should honor
> the information in bits 6 and 7 only if the corresponding NMI sources are set
> in bits 2 and 3 (they are hopefully readable on all MB's since the XT).
Of course. But assuming that when we find an NMI caused by bit 2 and/or
bit 3, we can safely think that the bit(s) was not set in the BIOS (so
enabling these NMI checks) and we can toggle them.
Ciao,
Riccardo.