Re: [Qemu-ppc] [PATCH 1/4] spapr: remove irq_hint parameter from spapr_irq_alloc()

[Cédric Le Goater]

On 05/28/2018 08:17 AM, Thomas Huth wrote:
> On 25.05.2018 16:02, Greg Kurz wrote:
>> On Fri, 18 May 2018 18:44:02 +0200
>> Cédric Le Goater <address@hidden> wrote:
>>
>>> This IRQ number hint can possibly be used by the VIO devices if the
>>> "irq" property is defined on the command line but it seems it is never
>>> the case. It is not used in libvirt for instance. So, let's remove it
>>> to simplify future changes.
>>>
>>
>> Setting an irq manually looks a bit anachronistic. I doubt anyone would
>> do that nowadays, and the patch does a nice cleanup. So this looks like
>> a good idea.
> [...]
>>> diff --git a/hw/ppc/spapr_vio.c b/hw/ppc/spapr_vio.c
>>> index 472dd6f33a96..cc064f64fccf 100644
>>> --- a/hw/ppc/spapr_vio.c
>>> +++ b/hw/ppc/spapr_vio.c
>>> @@ -455,7 +455,7 @@ static void spapr_vio_busdev_realize(DeviceState *qdev, 
>>> Error **errp)
>>>          dev->qdev.id = id;
>>>      }
>>>  
>>> -    dev->irq = spapr_irq_alloc(spapr, dev->irq, false, &local_err);
>>> +    dev->irq = spapr_irq_alloc(spapr, false, &local_err);
>>
>> Silently breaking "irq" like this looks wrong. I'd rather officially remove
>> it first (ie, kill spapr_vio_props, -5 lines in spapr_vio.c).
>>
>> Of course, this raises the question of interface deprecation, and it should
>> theoretically follow the process described at:
>>
>> https://wiki.qemu.org/Features/LegacyRemoval#Rules_for_removing_an_interface
>>
>> Cc'ing Thomas, our Chief Deprecation Officer, for insights :)
> 
> The property is a public interface. Just because it's not used by
> libvirt does not mean that nobody is using it. So yes, please follow the
> rules and mark it as deprecated first for two release, before you really
> remove it.

This "irq" property is a problem to introduce a new static layout of IRQ 
numbers. It is in complete opposition. 

Can we keep it as it is for old pseries machine (settable) and ignore it 
for newer ? Would that be fine ?

Thanks,

C.