Re: [Xen-devel] [OSSTEST PATCH 2/2] libvirt: Do not attempt save/restore when migration not advertised

[Martin Kletzander <mkletzan@xxxxxxxxxx>]

On Thu, Oct 06, 2016 at 10:59:06AM +0100, Ian Jackson wrote:
> Martin Kletzander writes ("Re: [OSSTEST PATCH 2/2] libvirt: Do not attempt 
> save/restore when migration not advertised"):
> > Since offline migration (as in migrating a domain between hosts without
> > being running) is not that used in the code and talked about, I'm
> > guessing offline means save restore.  Looking at the history it was
> > added before the "offline" migration, so it probably means
> > save/restore.  To avoid confusion, I would suggest we add either
> > <offline/> or rather <save/> (the naming is not important) and document
> > what it means.  And then you can use it exactly how you'd like.  And
> > you'll be also sure it means what you need it to mean ;)  The patches
> > will be straigh-forward, let me know if I can help anyhow.
> Except that the point of the exercise is to detect which features are
> supported in which versions.  Whatever I do in osstest needs to work
> with older libvirt versions, which do not report
>  /capabilities/host/migration_features/save
> even on x86, where it is supported.  I suppose I could detect
>  /capabilities/host/migration_features/live
> and assume that save/restore was supported (since it's unlikely that
> live migration would be supported but not save/restore).
>
> So for now I think I need to use
>  /capabilities/host/migration_features
> as a proxy for save/restore ?
Well then, unfortunately you do.

Also, looking at how the code is structured, if you have live migration
but don't have save/restore, you won't have <migration_features/> there
at all.

> Ian.

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