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

Mark McLoughlin
2009-06-12T14:50:30Z

On Fri, 2009-06-12 at 16:59 +0300, Michael S. Tsirkin wrote:
> 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.

So a "savevm --only-compat-hints" command? It might make sense, since we
would want the compat hints with savevm too.

> > - 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.

An example?

Cheers,
Mark.