Re: [Qemu-devel] [RFC PATCH 08/26] ppc/xive: add flags to the XIVE interrupt source

[Cédric Le Goater]

On 07/24/2017 11:50 AM, David Gibson wrote:
> On Mon, Jul 24, 2017 at 05:00:57PM +1000, Benjamin Herrenschmidt wrote:
>> On Mon, 2017-07-24 at 14:36 +1000, David Gibson wrote:
>>> On Wed, Jul 05, 2017 at 07:13:21PM +0200, Cédric Le Goater wrote:
>>>> These flags define some characteristics of the source :
>>>>
>>>>  - XIVE_SRC_H_INT_ESB  the Event State Buffer are controlled with a
>>>>                        specific hcall H_INT_ESB
>>>
>>> What's the other option?
>>
>> Direct MMIO access. Normally all interrupts use normal MMIOs,
>> each interrupts has an associated MMIO page with special MMIOs
>> to control the source state (PQ bits). This is something I added
>> to the PAPR spec (and the OPAL <-> Linux interface) to allow firmware
>> to work around broken HW (which happens on some P9 versions).
> 
> Ok.. and that's something that can be decided at runtime?
> 

This is a characteristic of an Interrupt Source and the associated 
object should be created with such a flag. But I don't think will 
ever use it in QEMU, maybe with KVM.

C.