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

[Anthony Liguori]

Mark McLoughlin wrote:
> On Fri, 2009-06-12 at 09:55 -0500, Anthony Liguori wrote:
>   
> > Mark McLoughlin wrote:
> >     
> > > On Wed, 2009-06-10 at 20:27 +0100, Jamie Lokier 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
> > >   
> > >       
> > How is compat hints different from a device tree?
> >
> > In my mind, that's what compat hints is.  I don't see another sane way 
> > to implement it.
> >     
>
> A device tree with a different purpose than a config file.
>
> In its simplest form it could be a device tree with a version number for
> each device[1]. 
>   

I think the point is that you don't need version numbers if you have a 
proper device tree.  NB the device tree contains no host configuration 
information.

Regards,

Anthony Liguori

> The other obvious piece to add to it would be PCI addresses, so that
> even if you remove a device, the addresses assigned to existing devices
> don't change.
>
> Cheers,
> Mark.
>
> [1] - Adding such a per-device version number to the config file would
> solve problem (2)
>
>