[vfio-users] Saving/restoring VFIO VMs

[Quentin Deldycke]

Yes, but windows *knows* the passed device is then shutdown. At reboot
windows *knows* that the device is "freshly" rebooted.

In your case, another OS (linux) use this card at a moment or another,
reset some bus (when re-binded to vfio). The reset of cards is already
hardly supported by windows / linux driver.

For my case: i know that my r9 290 can hard freeze if i shudown badly my
windows vm: the os is completely unloaded "software speaking" but the card
not, and it is still "powered".
2 options, when i restart the driver crash windows, or the driver crash
windows + the card + the host.

No problem when making a correct windows shut-down / start => the card is
cleanly unloaded by windows and cleanly restarted.

--
Deldycke Quentin


On 18 April 2017 at 13:53, Patrick O'Callaghan <poc at usb.ve> wrote:

> On Tue, 2017-04-18 at 13:32 +0200, Quentin Deldycke wrote:
> > You can't do like this. Even sleep is not correctly supported.
> >
> > What is happening to the card during reboot? How windows can know?
>
> Windows supports hibernation on some machines (e.g. laptops and
> tablets). That presumably does save the state of all devices. However
> KVM/QEMU doesn't seem to include the appropriate virtual hardware
> emulation.
>
> poc
>
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