Re: [PATCH 7/8] evtchn: add FIFO-based event channel ABI

[David Vrabel <david.vrabel@citrix.com>]

On 20/03/13 10:32, Jan Beulich wrote:
>>>> On 19.03.13 at 22:00, David Vrabel <david.vrabel@citrix.com> wrote:
>> From: David Vrabel <david.vrabel@citrix.com>
>>
>> Add the event channel hypercall sub-ops and the definitions for the
>> shared data structures for the FIFO-based event channel ABI.
>>
>> The design document for this new ABI is available here:
>>
>> http://xenbits.xen.org/people/dvrabel/event-channels-C.pdf 
>>
>> In summary, events are reported using a per-domain shared event array
>> of event words.  Each event word has PENDING, LINKED and MASKED bits
>> and a LINK field for pointing to the next event in the event queue.
>>
>> There are 16 event queues (with different priorities) per-VCPU.
>>
>> Key advantages of this new ABI include:
>>
>> - Support for over 100,000 events (2^17).
> 
> As said in a comment on the design doc B, I'm missing a way for
> the guest to learn the width of the involved mask (17 here, but
> obviously there is nothing preventing this from being 16, 18, or
> yet some other implementation specific value <= 29).

I haven't forgotten this.  I was focusing on the core implementation so
not all the design review feedback has been incorporated yet.

David