Re: [PATCH 0/4] HVM Virtual S3

[Keir Fraser <keir.fraser@eu.citrix.com>]

On 15/5/08 12:45, "Ian Pratt" <Ian.Pratt@eu.citrix.com> wrote:

>> The 'pause' state visible to tools is a specific type of
>> domain_pause(), and
>> *has* to be entered via the pause domctl hypercall. So don't worry --
>> your new type of pause should stack on top of 'xm pause/unpause' no
> problem.
> 
> In fact, does the S3 suspended guest need to go into a pause state at
> all? Presumably we could just let it block?
> Xend does need to be able to know when the S3 suspend has actually
> happened -- there should probably be a VIRQ for this.

S3 suspend is enacted by an I/O port write from the guest, trapped by qemu,
so the final reset of machine state is synchronously triggered by the tools
anyway.

As for pause-vs-block I think this is just a matter of terminology. At the
end of the day we want the domain to not run until s3-resume is triggered.
The natural way to do this within the hypervisor is to maintain a per-domain
is_s3_suspended flag and domain_[un]pause() when this flag toggles.

 -- Keir