Re: [PATCH 16/22] virtio_pci: use separate notification offsets for each vq.

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"H. Peter Anvin" <hpa@xxxxxxxxx> writes:
> On 03/27/2013 04:25 AM, Michael S. Tsirkin wrote:
>> 
>> Aha. Yes, good idea.  As for how large the offsets are,
>> I am guessing we should either just say offset is vqn * X and data is
>> vqn, or give hypervisors full flexibility with 32 bit offset and
>> arbitrary data.
>> 16 bit offsets seem neither here nor there ...
>
> Shift count?

You can only have 2^16 vqs per device.  Is it verboten to write 16-bit
values to odd offsets?  If so, we've just dropped it to 2^15 before you
have to do some decoding to do.  Hard to care...

I dislike saying "multiply offset by 2" because implementations will get
it wrong.  That's because 0 will work either way, and that's going to be
the common case.

Cheers,
Rusty.
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