Re: [Xen-devel] xl list -l doesn't work for incoming domain

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Nov 10, 2014 at 12:08:18PM -0500, Zhigang Wang wrote:
> On 11/10/2014 10:25 AM, Wei Liu wrote:
> > On Mon, Nov 10, 2014 at 10:01:22AM -0500, Zhigang Wang wrote:
> >> On 11/10/2014 07:35 AM, Wei Liu wrote:
> >>> I see. At that point the configuration was not available, yet. After the
> >>> domain is successfully migrated, the configuration should be available.
> >>>
> >>> I think a domain under construction without domain configuration is a
> >>> valid state. What do you think?
> >>
> >> Here is my thought:
> >>
> >> 1. In this design, if I watch xenstore @introduceDomain, it will not been
> >>    triggered until migration finish.
> >>
> > 
> > OK. What in this design makes behavior different than before? Are you
> > suggesting "xl list -l" has something to do with your xenstore watch? I
> > don't think I can get this.
> > 
> > My guess is that, you have some tool that watches @introduceDomain,
> > which happens *before* the domain creation is finished. And your tool
> > needs to get domain information once your watch fires.  Here with this
> > design, your tool cannot get the correct information until migration is
> > finished. Am I right?
> > 
> > However, in previous design, even if you manage to get configuration
> > before migration is finished, I don't think that configuration reflects
> > the true configuration of that domain. It's conceptually bogus.
> > 
> > In any case, if you look at xenstore code, XS_INTRODUCE doesn't mean a
> > domain is started, so using it for that purpose would be wrong.
> > 
> >> 2. Because we have multiple places (hypervisor, xenstore, /var/lib/xen) 
> >> holding
> >>    domain state, we need to define what does it mean by "VM started".
> >>
> > 
> > If my above analysis is correct, will some kind of @startDomain event solve
> > your problem?
> > 
> > But this involves making changes to Xenstore protocol. Let's not go into
> > details until we make sure your requirement is well understood.
> 
> We do currently watch xenstore @introduceDomain for VM start.
> 
> I thought the @introduceDomain behavior is different than xm/xend,
> but I just did a test and I was wrong.
> 
> xm/xend also trigger @introduceDomain until domain migration finish. (but 
> before
> @introduceDomain, all the VM xenstore entries are already there.)
> 
> Right now, I'm all set if we fix the xl list -l issue during migration.
> 

Just to be sure -- you're fine with "xl list -l" displaying no
configuration for an incoming domain, am I correct?

Wei.

> Thanks,
> 
> Zhigang

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