Re: [Qemu-ppc] [Qemu-devel] [PULL 095/107] spapr: clock should count only if vm is running

[Laurent Vivier]

On 02/02/2017 11:40, Mark Cave-Ayland wrote:
> On 02/02/17 09:13, Laurent Vivier wrote:
> 
>> On 02/02/2017 09:37, Mark Cave-Ayland wrote:
>>> On 02/02/17 05:14, David Gibson wrote:
>>>
>> ...
>>> Hi David/Laurent,
>>
>> Hi Mark,
>>
>>> I just noticed this in your pull request today - this looks like it is
>>> along similar lines to the prototype patch I proposed last year as part
>>> of the decrementer migration thread discussion, i.e. use a
>>> vm_change_state_handler() to sync the clock on pause/resume.
>>>
>>> Am I right in thinking this now solves the timebase migration problem,
>>> and so the only part required is to encode the decrementer relative to
>>> the timebase during migration to ensure its value is also migrated
>>> correctly?
>>
>> Do you have a link to this thread discussion?
>>
>> The main purpose of this patch was only to stop the clock (TBR) while
>> the machine is paused, so I'd like to know what is the problem you are
>> speaking about.
> 
> Hi Laurent,
> 
> Yes indeed. The discussion spanned a couple of threads last year, but
> the start of it was my patch to migrate the decrementer to fix an issue
> I was seeing when migrating Darwin images on the Mac machines under TCG:
> 
> https://lists.gnu.org/archive/html/qemu-devel/2016-01/msg00544.html
> 
> This then eventually became a separate thread here:
> 
> https://lists.gnu.org/archive/html/qemu-devel/2016-01/msg04622.html

I think adding the the PPCTimebase field and the VMSTATE_PPC_TIMEBASE_V
macro to the PMac machines should fix your issue.

Do you have a test case I can try?

Laurent