On 10.04.2014, at 16:35, Alexey Kardashevskiy <a...@ozlabs.ru> wrote:
> On 04/10/2014 10:10 PM, Alexander Graf wrote: >> >> On 08.04.14 03:26, Alexey Kardashevskiy wrote: >>> On 03/28/2014 12:07 AM, Alexey Kardashevskiy wrote: >>>> On 03/27/2014 11:57 PM, Peter Maydell wrote: >>>>> On 27 March 2014 12:49, Alexey Kardashevskiy <a...@ozlabs.ru> wrote: >>>>>> On 03/27/2014 11:37 PM, Andreas Färber wrote: >>>>>>> Am 27.03.2014 03:41, schrieb Alexey Kardashevskiy: >>>>>>>> This should prevent the destination guest from misbehaving when >>>>>>>> the threads number is different in "-smp" command. >>>>>>> Sorry, I don't understand. When migrating, surely -smp needs to be the >>>>>>> same on source and destination, so how can they differ? >>>>>> >>>>>> The idea is that "-smp" does not migrate and if we run source and >>>>>> destination guests with different numbers in -smp, we end up with weird >>>>>> machine >>>>> Yes, so don't do that. As I understand it: >>>>> (1) if you don't run QEMU with the exact same command line >>>>> and config at both ends then migration won't work >>>>> (2) we don't guarantee to detect and cleanly fail if you >>>>> don't do (1) >>>>> >>>>> It would probably be nice if we did detect config mismatches, >>>> Yep, we do not send the device tree (as libvirt does). Pure command line >>>> matching won't work. >>>> >>>>> but that seems to me like a problem we should be addressing >>>>> more globally than just for one particular config item for >>>>> one particular target... >>> >>> Ok. So. Let's assume I want to implement migration of "-smp" parameters. >>> What would be the correct way of doing this in terms of the current QOM >>> principles? Thanks. >> >> You don't. The migration protocol doesn't migrate configuration. If you >> want to start to transfer VM configuration (which I'd be all in for), do it >> properly and transfer _all_ configuration. > > > Then what is the purpose of many, many VMSTATE_.*_EQUAL? Probably legacy from old vmstate layouts. > And I do not want to send configuration by the proposed patch, I want to > make sure that the new guest is able to continue. Why exactly is this bad? It's not bad, but we should solve this properly, not one field at a time. Alex
