> > > 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
