Re: [Qemu-devel] [PATCH] q35: Remove old machine versions

[John Snow]

On 08/24/2015 02:54 AM, Markus Armbruster wrote:
> John Snow <address@hidden> writes:
> 
>> On 08/19/2015 02:55 AM, Dr. David Alan Gilbert wrote:
>>> * Eduardo Habkost (address@hidden) wrote:
>>>> Migration with q35 was not possible before commit
>>>> 04329029a8c539eb5f75dcb6d8b016f0c53a031a, because q35 unconditionally 
>>>> creates
>>>> an ich9-ahci device, that was marked as unmigratable. So all q35 machines
>>>> before pc-q35-2.4 were unmigratable, and there's no point in keeping
>>>> compatibility code for them.
>>>>
>>>> Remove all old pc-q35 machine classes and keep only pc-q35-2.4.
>>>
>>> But doesn't that mean that anyone who has a machine configured with one
>>> of those machine types will suddenly find it wont start?
>>>
>>> Dave
>>>
>>
>> To some extent, all versions of this board prior to 2.4 should be
>> considered unsupported and we should discourage their use anyway.
>>
>> If you really want, I suppose we could just alias them to 2.4 ...
> 
> I'd very much prefer an honest "won't start" over a silent change of the
> machine type.
> 
> If we really want to bend over backwards for existing uses of these
> machine types, we could make them error out with "use pc-q35-2.5
> instead".  Since I don't think they exist outside testing, I wouldn't
> bother.
> 

I like the discrete error idea, but I'm not sure how much clutter it'd
require to code in. If it's not a lot, it would be nice.