Re: [Qemu-devel] [RFC 1/2] spec/vhost-user: Introduce secondary channel for slave initiated requests

[Marc-André Lureau <marcandre.lureau@gmail.com>]

Hi

On Tue, Apr 11, 2017 at 5:53 PM Maxime Coquelin <maxime.coquelin@redhat.com> wrote:

Hi Marc-André,

On 04/11/2017 03:06 PM, Marc-André Lureau wrote:
> Hi
>
> On Tue, Apr 11, 2017 at 12:10 PM Maxime Coquelin
> <maxime.coquelin@redhat.com <mailto:maxime.coquelin@redhat.com>> wrote:
>
>     This vhost-user specification update aims at enabling the
>     slave to send requests to the master using a dedicated socket
>     created by the master.
>
>     It can be used for example when the slave implements a device
>     IOTLB to send cache miss requests to the master.
>
>     The message types list is updated with an "Initiator" field to
>     indicate for each type whether the master and/or slave can
>     initiate the request.
>
>     Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com
>     <mailto:maxime.coquelin@redhat.com>>
>
>
> This is very similar to a patch I proposed for shutdown slave initiated
> requests:
> https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg00095.html

Indeed, thanks for pointing this out, I wasn't aware of your series.

I find your proposal of having dedicated messages types
(VHOST_USER_SLAVE_*) cleaner.

ok
 

Are you ok if I handover your patch, and replace
VHOST_USER_SET_SLAVE_FD to VHOST_USER_SET_SLAVE_REQ_FD?

They are very similar, I suggest you update your patch with the best of both.

I suppose you came to the same conclusion with me that trying to make the communication both ways on the same fd would be quite difficult, although it's a bit strange that the qemu implementation forces the design of the protocol in some direction.

--

Marc-André Lureau