Re: [PATCH 10/10] x86, ACPI: default to reboot via ACPI (again)

Ingo Molnar
2008-11-11T20:45:05Z

* Eric W. Biederman <ebiederm@xmission.com> wrote:

> "H. Peter Anvin" <hpa@zytor.com> writes:
>
> > Ingo Molnar wrote:
> >>
> >> well then we could insert CF9 to before the triple fault, and solve
> >> some of the problems as well, without unnecessary risks.
> >>
> >> This is a separate patch from ACPI reboot itself, naturally.
> >>
> >
> > This is a pretty good point. There is extremely low risk of being
> > something at port CF9 that is something other than the reset
> > register. It may not be there, but if it isn't, the worst thing
> > that happened is we confused a device right before reset.
> >
> > Even better if we condition the port CF9 write on existence a PCI
> > bus (or even more specifically PCI Configuration Method #1 or #2).
> > Port CF9 is extremely unlikely to exist on a machine without a PCI
> > bus, and extremely unlikely to conflict with anything else on a
> > machine with a PCI bus.
>
> Yes. What we are guarding against in practice is a write that
> causes the system to hang. Anything else and we will make it to the
> next reset method.

yeah. Patches are welcome :)

Ingo