[Qemu-devel] Re: [PATCH 0/2] pckbd improvements

[Paolo Bonzini]

> > > In 2/2, A20 logic changes a bit but I doubt any guest would be broken
> > > if A20 line written through I/O port 92 couldn't be read via i8042.
> > > The reverse (write using i8042 and read port 92) will work.
> > >
> >
> >  Why take the risk?
> 
> The alternative is to route a signal from port 92 to i8042. Or maybe
> port 92 should belong to i8042, that could make things simpler but
> then the port would appear on non-PC architectures as well.
>
> But I doubt any OS would depend on such details, because the details
> seem to be murky:
> http://www.win.tue.nl/~aeb/linux/kbd/A20.html

True, but I don't see why we should introduce a possible regression.
I would at the very least test it on real hardware before doing the
change.

Paolo