Re: [Xen-devel] [PATCH] libxl: invert xc and domain model resume calls in xc_domain_resume()

[Juergen Gross <jgross@xxxxxxxx>]

On 29/11/16 08:34, Wei Liu wrote:
> On Mon, Nov 28, 2016 at 02:53:57PM +0100, Cédric Bosdonnat wrote:
>> Resume is sometimes silently failing for HVM guests. Getting the
>> xc_domain_resume() and libxl__domain_resume_device_model() in the
>> reverse order than what is in the suspend code fixes the problem.
>>
>> Signed-off-by: Cédric Bosdonnat <cbosdonnat@xxxxxxxx>
>  
> I think it would be nice to explain why reversing the order fixes the
> problem for you. My guess is because device model needs to be ready when
> the guest runs, but I'm not fully convinced by this explanation --
> guests should just be trapped in the hypervisor waiting for device model
> to come up.

I'm not completely sure this is true. qemu is in "stopped" state, so it
might be any emulation requests are just silently dropped. In any case
it is just weird to stop qemu in suspend case only after suspending the
domain, but let it continue _after_ resuming the domain. So I'd rather
expect an explanation (not from Cedric) why this should be okay in case
the patch isn't accepted.

> I also CC'ed other people who are more familiar with this area so that
> they can provide insight.

And adding Stefano and Anthony, too.


Juergen

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