Re: [Qemu-ppc] [Qemu-devel] [PATCH 0/5] spapr: DRC cleanups (part VI)

[David Gibson]

On Thu, Jul 06, 2017 at 11:31:35AM -0300, Daniel Henrique Barboza wrote:
> 
> 
> On 07/05/2017 06:53 PM, Daniel Henrique Barboza wrote:
> > Worth a try. I'll see if I can make a POC of this DRC reset at incoming
> > migration time.
> 
> 
> Just played a little with the idea of manual reset during migration. I've
> created a
> POC that resets the CPU DRCs in a pre_load hook.

Ok.  I'm not sure does the pre_load hook get called for objects where
nothing ends up being sent in the migration stream?

> Then I've done the same
> experiment - device_add on both source and target before the migration,
> hot unplug the device after migration is completed. The hot unplug worked as
> expected in both QEMU and guest.

That's encouraging.

> 
> To minimize the impact I am resetting only the DRCs of the CPUs that were
> hotplugged
> in the target instead of resetting everybody.

That sounds like more trouble than it's worth, I think it'll be easier
and safer to reset all DRCs.

> I'll see if this solution works for LMBs and PCI devices. In case
> affirmative, and
> if we are fine with this solution of resetting the DRCs in pre_load (not
> sure if pre_load is
> the right place for doing it - suggestions welcome), I can send a patch to
> be applied on top
> of this series.
> 
> 
> 
> Thanks,
> 
> Daniel
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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