Re: [Xen-devel] [PATCH v3] sndif: add ABI for Para-virtual sound

[Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>]

On Thu, Jan 22, 2015 at 1:08 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>> On 22.01.15 at 11:52, <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx> wrote:
>> On Thu, Jan 22, 2015 at 12:24 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>>> On 22.01.15 at 10:56, <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx> wrote:
>>>> + * Responce for all requests exept the XENSND_GET_VOLUME:
>>>> + *     0    1     2     3     4     5     6     7  octet
>>>> + * +-----+-----+-----+-----+-----+-----+-----+-----+
>>>> + * |       stream_id       |       operation       |
>>>
>>> Is there a really need for echoing the operation, i.e. isn't the echoed
>>> ID sufficient? Because if you'd be able to drop this, request and
>>> response sizes would match up, avoiding wasted space on the
>>> shared page(s).
>> In our implementation there is no matter if is echoed the operation or no.
>> Frontend sends one request and waits a response. So I can simply remove
>> the echoed operation. But in the future if this echoed the operation
>> will be needed
>> it can be simply restored.
>
> Question here is whether "stream_id" really means what its name
> says. If it does, you certainly need another field with a request ID,
> which then also need echoing (and then the question is whether
> stream_id need echoing too).
Our implementation doesn't use a request ID, but this field
may be added to the protocol and in addition this request ID will be echoed.
And stream_id didn't need be echoed.
I'll think how to do it better in the next-patch-set.

> Jan
>

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