On Thu, Jan 17, 2008 at 10:42:28PM +0100, Andreas Herrmann3 wrote:
> On Thu, Jan 17, 2008 at 10:13:08PM +0100, Ingo Molnar wrote:
> > 
> > * Andreas Herrmann3 <andreas.herrmann3@amd.com> wrote:
> > 
> > > Yes.
> > > 
> > > Meanwhile I have figured out that it is some ACPI stuff that maps the 
> > > page cached. I've changed the ioremap's in drivers/acpi/osl.c to 
> > > ioremap_nocache. See attached patch.
> > > 
> > > Now the machine boots without conflicts.
> > 
> > ah, nice!
> > 
> > but in general we must be robust enough in this case and just degrade 
> > any overlapping page to UC (and emit a warning perhaps) - instead of 
> > failing the ioremap and thus failing the driver (and the bootup).
> > 
> > Does my third patch (which falls back to UC in case of attribute 
> > conflicts, also attached below) instead of your ioremap_nocache() patch 
> > solve your bootup problem too?
> 
> I'll check this asap


So, now that I've avoided this tiny NULL-pointer-dereference, the system boots
fine as well with your (slightly modified) patch. See dmesg attached.


Andreas