Re: [Xen-devel] PV driver domains and S3 sleep

[Joanna Rutkowska <joanna@xxxxxxxxxxxxxxxxxxxxxx>]

On 09/16/10 13:52, Keir Fraser wrote:
> On 16/09/2010 12:44, "Rafal Wojtczuk" <rafal@xxxxxxxxxxxxxxxxxxxxxx> wrote:
> 
>> The topic is self-explanatory: how to ensure that a PV driver domain 
>> correctly
>> prepares its PCI devices for S3 sleep?
>> If I do "pm-suspend" in dom0, and the driver domain has active network
>> interfaces, 
>> suspend hangs the system. Yes, in case of this particular machine, suspend
>> works
>> fine when there is no driver domain.
>> It is possible to manually invoke scripts from /usr/lib64/pm-utils/sleep.d/ 
>> in
>> driver 
>> domain. In the test case, "ifconfig down wlan0" in the driver domain allows
>> the suspend to go smoothly. But generally, is it enough ? The kernel device
>> driver should 
>> prepare the PCI device properly for S3, shouldn't it ?
>> Would it be more proper to [somehow] notify a driver domain _kernel_ that we
>> are 
>> going to S3 (just like dom0 kernel is notified), and let it execute all
>> necessary actions
>> (including, but not only, launching of usermode pm-utils scripts), just like
>> dom0 kernel 
>> does ? Would it work at all, considering that driver domain kernel has no
>> access to 
>> ACPI tables ? 
>> Currently, how are these issues taken care of in the mainstream Xen?
> 
> I don't think it currently is handled. HVM driver domains (using VT-d or
> equivalent) can be put into virtual S3. We would need an equivalent concept
> for PV driver domains. Or for devices to be hot-unplugged from the driver
> domain, and re-plugged on resume?
> 

But, can you explain how Xen notifies Dom0 when the system enters S3,
and if the same mechanism could be (easily) used to do the same for a
driver PV domain?

Thanks,
joanna.

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