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

Anthony Liguori
2009-06-12T16:12:56Z

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)
>
>