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

[Zhigang Wang <zhigang.x.wang@xxxxxxxxxx>]

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.

Thanks,

Zhigang

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