Re: [PATCH RFC 0/8] virtio: add guest MSI-X support

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Apr 28, 2009 at 09:47:14AM +0300, Avi Kivity wrote:
> Michael S. Tsirkin wrote:
>>> That saves us the new API (at the expense of a lot more code, but 
>>> with  added flexibility).
>>>     
>>
>> So we'll probably need to rename request_vqs to request_vectors,
>> but we probably still need the driver to pass the number of
>> vectors it wants to the transport. Right?
>>
>>   
>
> I don't think so - virtio will provide the number of interrupts it  
> supports, and virtio-net will tell it to bind ring X to interrupt Y.

This does not work for MSIX - in linux, you must map all MSI-X entries
to interrupt vectors upfront.

So what I see is transports providing something like:

struct virtio_interrupt_mapping {
	int virtqueue;
	int interrupt;
};

map_vqs_to_interrupt(dev, struct virtio_interrupt_mapping *, int nvirtqueues);
unmap_vqs(dev);

-- 
MST