Re: Configuration vs. compat hints [was Re: [Qemu-devel] [PATCHv3 03/13] qemu: add routines to manage PCI capabilities]

Michael S. Tsirkin
2009-06-12T14:02:47Z

On Fri, Jun 12, 2009 at 09:43:29AM +0100, Mark McLoughlin wrote:
> = Solution - Separate configuration from compat hints =
>
> As I suggested before:
>
> - Allow the VM manager to dump compat hints; this would be an opaque
> file format, more like the savevm format than a config file

Why make it "like the savevm" format then?
If they are opaque anyway, compat hints could be part of savevm format.

> - Use defaults where compat hints are not available; e.g. if the VM
> manager specifies a device config, but no compat hints are
> supplied for it, then just use default values
>
> - Make the config override compat hints; e.g. if there are compat
> hints specified for a device not included in the machine config,
> just ignore those hints
>
> Cheers,
> Mark.

If compat hints are opaque and only editable by qemu, we can get into a
situation where one can't create a specific setup with a new qemu.

--
MST