[Qemu-devel] Re: question on virtio

[Michael S. Tsirkin]

On Wed, May 05, 2010 at 02:40:15PM -0500, Anthony Liguori wrote:
> On 05/05/2010 06:09 AM, Michael S. Tsirkin wrote:
>> Hi!
>> I see this in virtio_ring.c:
>>
>>          /* Put entry in available array (but don't update avail->idx *
>>         until they do sync). */
>>
>> Why is it done this way?
>> It seems that updating the index straight away would be simpler, while
>> this might allow the host to specilatively look up the buffer and handle
>> it, without waiting for the kick.
>>    
>
> It should be okay as long as you don't update idx for partial vectors.
>
> Regards,
>
> Anthony Liguori

Sorry, what do you mean by partial vectors here?