RE: [RFC PATCH V2 0/3] IXGBE/VFIO: Add live migration support for SRIOV NIC

[Dong, Eddie]

> On Wed, Nov 25, 2015 at 12:21 AM, Lan Tianyu <tianyu.lan@xxxxxxxxx> wrote:
> > On 2015å11æ25æ 13:30, Alexander Duyck wrote:
> >> No, what I am getting at is that you can't go around and modify the
> >> configuration space for every possible device out there.  This
> >> solution won't scale.
> >
> >
> > PCI config space regs are emulation by Qemu and so We can find the
> > free PCI config space regs for the faked PCI capability. Its position
> > can be not permanent.
> 
> Yes, but do you really want to edit every driver on every OS that you plan to
> support this on.  What about things like direct assignment of regular Ethernet
> ports?  What you really need is a solution that will work generically on any
> existing piece of hardware out there.

The fundamental assumption of this patch series is to modify the driver in guest to self-emulate or track the device state, so that the migration may be possible.
I don't think we can modify OS, without modifying the drivers, even using the PCIe hotplug mechanism.  
In the meantime, modifying Windows OS is a big challenge given that only Microsoft can do. While, modifying driver is relatively simple and manageable to device vendors, if the device vendor want to support state-clone based migration.

Thx Eddie