PV driver domains and S3 sleep

[Rafal Wojtczuk <rafal@invisiblethingslab.com>]

Hello,

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? 

Thanks in advance,
Rafal Wojtczuk