[ovs-dev] [PATCH 1/1] Add support for tun_key to OVS datapath

[Jesse Gross]

Hi Kyle,

Sorry again about the long delay in getting back to you on this and
thanks for being so patient.  I definitely intend to be much quicker
about future patches.

I think your approach of doing incremental changes is a good one since
the full set of changes is pretty large.  The one thing that I think
we should be careful about is trying not to break compatibility too
many times.  Since my intention is to switch wholesale over to this
new mechanism and drop the old, we'll have to do it at least once,
which is why we never sent the tunneling code upstream.  However, we
should avoid doing it more than that, which is obviously the downside
of smaller incremental changes.  Do you have a rough idea of the order
in which you plan to procede?  My inclination is that we should get
all of the kernel changes in so that both the old and new mechanisms
work fully, start adding userspace code that incrementally relies on
more and more of the new code, and then drop the old kernel code.

On Fri, Aug 31, 2012 at 7:02 PM, Kyle Mestery (kmestery)
<kmestery at cisco.com> wrote:
> Jesse:
>
> Are you going to have a chance to review these next week? Can you also
> comment on if you want to iterate over all of Simon's original patches, or go
> down the path I started with these patches, which was to try and get the
> initial tun_key changes in, leaving existing functionality in place, before
> moving on to the rest of the series?
>
> Thanks!
> Kyle
>
> On Aug 29, 2012, at 8:17 PM, Simon Horman wrote:
>
>> On Wed, Aug 29, 2012 at 10:00:45AM -0400, Kyle Mestery wrote:
>>> This is a first pass at providing a tun_key which can be
>>> used as the basis for flow-based tunnelling. The tun_key
>>> includes and replaces the tun_id in both struct ovs_skb_cb
>>> and struct sw_tun_key.
>>>
>>> In ovs_skb_cb tun_key is a pointer as it is envisaged that it will grow
>>> when support for IPv6 to an extent that inlining the structure will result
>>> in ovs_skb_cb being larger than the 48 bytes available in skb->cb.
>>>
>>> As OVS does not support IPv6 as the outer transport protocol for tunnels
>>> the IPv6 portions of this change, which appeared in the previous revision,
>>> have been dropped in order to limit the scope and size of this patch.
>>>
>>> This patch allows all existing tun_id behaviour to still work. However,
>>> when the userspace code is updated to make use of the new tun_key, the
>>> old behaviour will be deprecated and removed.
>>>
>>> Signed-off-by: Kyle Mestery <kmestery at cisco.com>
>>> Cc: Simon Horman <horms at verge.net.au>
>>> ---
>>> V2:
>>> - Fix blank line addition/removal found by Simon.
>>> - Fix hex printing output found by Simon.
>>
>> Thanks
>>
>> Acked-by: Simon Horman <horms at verge.net.au>
>