[ovs-dev] [PATCH 3/3] datapath: Add support for 4.3 kernel.

Jesse Gross jesse at nicira.com
Fri Sep 25 03:37:48 UTC 2015


On Thu, Sep 24, 2015 at 8:06 PM, Pravin Shelar <pshelar at nicira.com> wrote:
> On Thu, Sep 24, 2015 at 7:11 PM, Jesse Gross <jesse at nicira.com> wrote:
>> On Thu, Sep 24, 2015 at 3:18 PM, Pravin Shelar <pshelar at nicira.com> wrote:
>>> I am not targeting STT and LISP in this 4.3 patch set, Once this
>>> backport are done, I will work on these tunnel implementation.
>>
>> Even if it isn't done immediately, do you have an idea of what it
>> would look like long term? Not just for STT and LISP but also any
>> future feature backports to the tunnels that are upstream (like IPv6)?
>> It seems like this could be a real pain to maintain for both pre-4.3
>> and post-4.3 kernels.
>
> I do not think we have option for STT and LISP but to maintain two
> different code bases.
> For IPv6 tunnels, I think it would be available on kernel which
> support it. So only kernel from distributions which has backported
> IPv6 tunnels and kernel 4.4 or newer will support such tunnels.

I think this would be the first feature that isn't available with the
out of tree module running on older kernels. I believe any other
limitations that we might have are strictly performance related, at
worst. If that's correct, that would make this a significant departure
and something that we shouldn't do lightly.

I wonder if it might be possible to create a shim layer (perhaps using
per-CPU data as a safe place to store things) to emulate the skb dst
changes to carry metadata around purely internal to OVS. We could then
have backports of the netdevices (or new netdevices in the case of STT
and LISP) in the OVS tree, which should be possible on all kernels.
That would seem to eliminate both problems if we can pull it off.



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