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

To: Rafal Wojtczuk <rafal@xxxxxxxxxxxxxxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] PV driver domains and S3 sleep
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Thu, 16 Sep 2010 12:52:02 +0100
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Thread-topic: [Xen-devel] PV driver domains and S3 sleep
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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?

 -- Keir

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