Re: [RFC][PATCH 0/2] uq/master: Basic MSI support for in-kernel irqchip mode

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-03-28 13:31, Michael S. Tsirkin wrote:
>>>>> Also, how would this support irqfd in the future? Will we have to
>>>>> rip it all out and replace with per-device tracking that we
>>>>> have today?
>>>>
>>>> Irqfd and kvm device assignment will require additional interfaces (of
>>>> the kvm core in QEMU) via which you will be able to request stable
>>>> routes from such sources to specified MSIs. That will be widely
>>>> orthogonal to what is done in these patches here.
>>>
>>> Yes but not exactly as they will conflict for resources, right?
>>> How do you plan to solve this?
>>
>> As done in my original series: If a static route requires a pseudo GSI
>> and there are none free, we simply flush the dynamic MSI routes.
> 
> Right. So static routes take precedence. This means that in effect
> we will have two APIs in qemu: for fast MSIs and for slow ones,
> the advantage of the slow APIs being that they are easier to use,
> right?

We will have two APIs depending on the source of the MSI. Special
sources are the exception while emulated ones are the majority. And for
the latter we should try very hard to keep things simple and clean.

Jan

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