Re: Paravirtualizing bits of acpi access

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Sunday 22 March 2009, Jeremy Fitzhardinge wrote:
> Rafael J. Wysocki wrote:
> > Well, why don't you implement the platform suspend operations for Xen?
> > I guess you don't want ACPI _PTS to be executed during suspend as well.
> >   
> 
> I don't know.  What's _PTS?

It's an ACPI method called to prepare the platform to enter the sleep state
(the name stands for "prepare to sleep").  Executing it may affect the
hardware.

> I think for the most part we want Linux to do most of the acpi work of 
> bringing the machine into an idle state.  Its just that Xen is 
> responsible for the very low level cpu context save/restore, because the 
> Linux kernel is still running on vcpus rather than the physical cpus.

I think you really should not execute any global ACPI methods to suspend a
guest, because that may affect the host.  That's why I think it's better to
regard Xen as a platform and implement a separate set of suspend operations for
it.

Thanks,
Rafael