Re: [PATCH 0/4] HVM Virtual S3

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

On 15/5/08 13:42, "Ian Pratt" <Ian.Pratt@eu.citrix.com> wrote:

>> 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.
> 
> We wouldn't need to do the pause if the code after the magic port write
> did "cli;hlt". Does it do this or loop?
> [On real hardware the effect of the port write wouldn't be immediate, so
> it must do something]

It spins. But to take advantage of that we have to restructure
s3-suspend/resume so that the reset of machine state happens in the resume
hypercall. At that point suspend, from the point of view of Xen, becomes a
no-op. I suppose we could do that... It seems a bit odd though and I don;t
know that it's guaranteed that all operating systems will happily spin
forever waiting for S3 oblivion. Some may time out.

 -- Keir