Re: Race betwen the NMI handler and the RTC clock in practially all kernels II

[Andi Kleen <ak@suse.de>]

> >  It's not the dummy read that causes the problem.  It's the index write
> > that does.  It can be solved pretty easily by not changing the index.  It
> 
> True. It has to be cached once.

I checked the Intel datasheets now. Problem is that they define this
register as read-only, and the only way to access it works using
a very chipset specific way (alternative LPC interface) 

So it's impossible to check the old value. The original code is the only
way to do this (if it's even needed, Intel also doesn't say anything
about this bit being a flip-flop). Only possible change would be to 
write an alternative index.

-Andi