Re: [PATCH v2 for 4.5] xen/arm: Add support for GICv3 for domU

[Julien Grall <julien.grall@linaro.org>]

On 06/11/2014 10:11, Jan Beulich wrote:
>>>> On 06.11.14 at 10:45, <julien.grall@linaro.org> wrote:
>> Hi Jan,
>>
>> On 05/11/2014 17:15, Jan Beulich wrote:
>>>>>> Julien Grall <julien.grall@linaro.org> 11/04/14 6:27 PM >>>
>>>> On 11/03/2014 04:39 PM, Konrad Rzeszutek Wilk wrote:
>>>>> It also needs Acks from Daniel and Jan.
>>>>
>>>> This patch doesn't modify the x86 part. So I'm not sure if Jan ack is
>>>> required. Would Ian C. ack be enough?
>>>
>>> Yes, it would.
>>>
>>>> Anyway, Jan do you have any objection on this patch?
>>>
>>> As said previously, I'm not particularly happy about it, but I also don't
>> strongly
>>> mind it going in in the current shape.
>>
>> May I ask what is wrong with the new approach to the a DOMCTL in this patch?
>>
>> The DOMCTL has been clearly identify as arm specific (there is "arm" in
>> the name). Therefore it doesn't seem necessary to expose it for other
>> architecture than ARM32 and ARM64.
>
> I didn't say there's anything actively wrong with it, all I said is that
> I'm not particularly happy about it: Irrespective of its name it doesn't
> look to be really arch-specific in the long run, plus it feels like the
> data being set here should rather be specified right at domain
> creation, or via a mechanism similar to x86'es HVM parameters (iirc
> the value set here can't be changed once the domain got first
> unpaused).


TBH I choose this solution because I though you would be disagree with 
extending the domain create hypercall.

In long run, there will be more parameters such as the number of spis. 
All will be required at the same time. So the HVM parameters solution 
won't really help here.

However, I could give a look to extending the domain creation hypercall 
(xen_domctl_createdomain) to add arch specific field.

But I don't think it's Xen 4.5 material. So I would prefer to stay on 
this approach for this release because we'd like to have GICv3 guest 
support on Xen. Though I could rename the DOMCTL to DOMCTL_get_gic_version.

Regards,

-- 
Julien Grall