On Wed, Sep 13, 2017 at 06:17:21PM +0100, Mark Cave-Ayland wrote: > On 13/09/17 08:19, David Gibson wrote: > > >> When pausing a VM, does execution stop at the end of the current TB > >> rather than immediately? If so, perhaps someone could confirm that > >> guarantee is good enough for access_type? > > > > I'm pretty sure it has to; we'd have to come up out of an individual > > TB in order to get to the main loop where we check the "please pause" > > flag. I'm not sure if that helps us here though - I *think* access > > type is about carrying information from the point where we trigger an > > exception to the point where we actually start processing the > > exception. > > > > This code is really ugly and I've never understood it well :(. It's > > always seemed bogus to me that we have an essentially global variable > > to carry information over that small gap, though. Unfortunately it's > > unlikely that I'd be able to dive into this and work out if it's > > really needed any time soon. > > >From my testing yesterday it does appear to be required for TCG (or > unless this is exposing another bug in the Mac migration) so I can check > it works here and then maybe someone else confirm it works on KVM? > > A couple of things I've noticed: the heathrow VMStateDescription looks > good, however I can see that the OpenPIC timers won't likely migrate > correctly without adding a few more fields - that's easy to fix.
Right. And since OpenPIC isn't used on any platforms that have real
production use in the wild, it's fine to bump the migration stream
version for it.
> Another thing is that if we're changing the migration stream for Mac
> models Ben has some OpenPIC and other related changes in his wip queue
> that it might make sense to put those in first before properly fixing
> the Mac machine migration.
That would have something to be said for it.
It's probably not essential, though, since I don't consider the
non-pseries platforms at this stage sufficiently mature that we
guarantee a stable migration stream format.
--
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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