Re: [Xen-devel] Testing for domain states (before starting, before restarting, and after "save")

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

Hi,

At 00:32 +0000 on 20 Nov (1258677171), Dan Magenheimer wrote:
> Is there a way (in the hypervisor) to test a domain to see if is
> created but has not yet executed its first instruction (or has been
> restored/live-migrated but has not yet executed its first instruction
> post-restore)? 

I don't think that's explicitly available, but if it's paused and all
its vcpus' scheduler stats are at zero, that's probably good enough for
the kind of sanity check you're talking about.

> Or to see if it has been stopped in anticipation of a
> save (or live migrate) and will not execute more instructions
> unless/until it is restored (or revived on the live-migrate target
> machine)?

That's easier: it's shut down with shutdown code suspend.  That doesn't
mean it will never run again in this domain, because of the Remus
fast-resume path, but it does mean no more instructions executed before
some kind of resume.

Cheers,

Tim.

> I'm writing routines for tsc_mode that assumes each of those conditions and, 
> rather than just comment about it, thought it would be nice to fail if the 
> assumption is incorrect.  If not (or if it is too complicated), I'll just use 
> comments.
> 
> Thanks,
> Dan
> 

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-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

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