Re: [Qemu-devel] [PATCH v2 3/6] ACPI: Add Virtual Machine Generation ID support

[Michael S. Tsirkin]

On Tue, Jan 17, 2017 at 02:00:58PM +0100, Igor Mammedov wrote:
> Question is how you'd get address of it and I think that's where
> writable fwcfg files come in play.
> I'd prefer fwcfg_loader in firmware to write it back after buffer
> allocation is done as it's already has utilities for fw_cfg,
> but that probably would mean extending loader protocol to support
> new writeback command.

Right. It's quite easy to do as at least seabios was written to
ignore commands it does not recognize. So with old bios you
just don't get a write. Not sure about UEFI, worth checking.

> PS, address one would get from guest should be migrated as well

IIRC writeable fw cfg blobs are migrated automatically.

-- 
MST