Re: [PATCH 5/5] xen: Add V4V implementation

[Jean Guyader <jean.guyader@citrix.com>]

On 09/08 11:38, Tim Deegan wrote:
> Hi,
> 
> This looks pretty good; I think you've addressed almost all my comments
> except for one, which is really a design decision raether than an
> implementation one.  As I said last time: 
> 
> ] And what about protocol?  Protocol seems to have ended up as a bit of a
> ] second-class citizen in v4v; it's defined, and indeed required, but not
> ] used for routing or for acccess control, so all traffic to a given port
> ] _on every protocol_ ends up on the same ring. 
> ] 
> ] This is the inverse of the TCP/IP namespace that you're copying, where
> ] protocol demux happens before port demux.  And I think it will bite
> ] someone if you ever, for example, want to send ICMP or GRE over a v4v
> ] channel.
> 

The protocol field is used to inform about the type a message on the ring.

Right now we use two protocols in our linux driver: V4V_PROTO_DGRAM and
V4V_PROTO_STREAM. In the future that could probably be extended to new protocol
like V4V_PROTO_ICMP for instance.

The demultiplexing will happens at the other end, the driver can look at the
message and decide what to do with it based on the protocol field.

Jean