Re: [Qemu-devel] [PATCH] powerpc iommu: enable multiple TCE requests

[Paolo Bonzini]

Il 20/08/2013 11:13, Benjamin Herrenschmidt ha scritto:
> On Tue, 2013-08-20 at 11:09 +0200, Paolo Bonzini wrote:
>>> Sorry if I miss anything, but is not it what the patch already
>> does? :)
>>
>> No, you need to expose multitce unconditionally in the device tree.
> 
> If I'm not mistaken the multitce kernel side patches are still not
> upstream so I disagree. Exposing it will make Linux use it which means
> that anything running on 3.10 or 3.11 will become very slow.
> 
> So no, multitce should not be exposed if KVM doesn't support it.

Then you have to do it right and:

- provide the infrastructure to enable/disable it from the command line
(which will be enough design effort alone);

- add pseries-1.6 as a synonym of pseries in 1.6.1;

- add pseries-1.7 a synonym of pseries in master;

- add a pseries-1.6 machine type in master that always disables it.

Paolo