On Mon, Oct 31, 2022 at 04:32:27PM +0200, Edward Haas wrote:
> Hi Igor and Laine,
>
> I would like to revive a 2 years old discussion [1] about consistent network
> interfaces in the guest.
>
> That discussion mentioned that a guest PCI address may change in two cases:
> - The PCI topology changes.
> - The machine type changes.
>
> Usually, the machine type is not expected to change, especially if one
> wants to allow migrations between nodes.
> I would hope to argue this should not be problematic in practice, because
> guest images would be made per a specific machine type.
>
> Regarding the PCI topology, I am not sure I understand what changes
> need to occur to the domxml for a defined guest PCI address to change.
> The only think that I can think of is a scenario where hotplug/unplug is
> used,
> but even then I would expect existing devices to preserve their PCI address
> and the plug/unplug device to have a reserved address managed by the one
> acting on it (the management system).
>
> Could you please help clarify in which scenarios the PCI topology can cause
> a mess to the naming of interfaces in the guest?
>
> Are there any plans to add the acpi_index support?
This was implemented a year & a half ago
https://libvirt.org/formatdomain.html#network-interfaces
though due to QEMU limitations this only works for the old
i440fx chipset, not Q35 yet.
I think most deployments today use Q35.
Are there plans to resolve it there?
BTW, should this limitation be added to the documentation?
With regards,
Daniel
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