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

[Avi Kivity]

On 06/15/2009 12:09 PM, Mark McLoughlin wrote:
> > > > I think the point is that you don't need version numbers if you have a
> > > > proper device tree.
> > > >
> > > >          
> > > How do you add a new attribute to the device tree and, when a supplied
> > > device tree lacking said attribute, distinguish between a device tree
> > > from an old version of qemu (i.e. use the old default) and a partial
> > > device tree from the VM manager (i.e. use the new default) ?
> > >
> > >        
> > -baseline 0.10
> >      
>
> That's a version number :-)
>
> (I was responding to Anthony's "you don't need a version number")
>    

If you want to prevent incompatibilities, you need to make everything 
new (potentially including bugfixes) non-default.  Eventually the 
default configuration becomes increasingly unusable and you need a new 
baseline.  You must still be able to fall back to the old baseline for 
older guests.  I don't think games with configuration files can hide that.

--
error compiling committee.c: too many arguments to function