[Xen-devel] Re: Paravirtualizing bits of acpi access

[Ingo Molnar <mingo@xxxxxxx>]

* Rafael J. Wysocki <rjw@xxxxxxx> wrote:

> 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.

I'd agree with that. That also allows the reuse of existing 
callbacks, right?

        Ingo

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