[ovs-dev] OVS / OVN split - post 2.12

Mark Michelson mmichels at redhat.com
Thu Jul 25 18:35:46 UTC 2019

On 7/25/19 12:37 PM, Ilya Maximets wrote:
> Hi.
> I have a question regarding the split.
> Sorry if it's obvious from the RFC splitting code which I didn't look at.
> The question is:
> How the patches for the common data structures (lists, hash maps) will be
> applied to OVN? Will we need to post same patch for both repositories in the
> future if it changes/fixes common libraries? Or all this code will be hosted
> only in OVS repo and will be included like a submodule or something like that?
> Best regards, Ilya Maximets.

Hi Ilya,

OVN will be a separate repo from OVS. Initially, OVS will be a subtree 
of OVN, but soon, we will want to be able to build OVN while having a 
completely separate OVS on the system. When all is said and done, it 
should be possible to build OVN as long as you have, say, an ovs-devel 
package installed on your system.

I think the answer to your question is that as an OVS developer, if you 
make a change to a core component, you only need to post the change to 
the OVS repo.

 From an OVN developer's perspective, if an OVN feature/bugfix requires 
a parallel change to be made to a core OVS library, then the OVN 
developer will need to post the library change to OVS as well as the 
usage of that change to OVN. As long as OVS is a subtree of OVN, it's 
just a matter of ensuring the subtree is kept up to date. However, once 
OVS is built separately, then configure-time checks of OVS features or 
minimum version checks will need to be added to OVN to ensure that the 
code can build properly.

This approach should place most of the burden of OVN compatibility with 
OVS on OVN developers rather than OVS developers.
>> Numan and I have discussed this, and we're planning to perform the split
>> tomorrow July 25. Numan will be applying the commits he referenced below
>> to the ovn-org branch to get it up to date. I will be submitting a
>> review for OVS to remove all of the OVN code, documentation, etc. from it.
>> If there are any reasons why we should hold off on this, please mention
>> them as soon as possible.
>> Thanks
>> On 7/22/19 2:35 PM, Numan Siddique wrote:
>>> Hi Ben, Mark and All,
>>> Now that branch 2.12 is created, shall we proceed with the OVS/OVN split ?
>>> In order to do the split we need to do the below tasks
>>> In ovn-org/ovn repo
>>> Step 1. Sync the ovs subtree to the latest (from the OVS repo).
>>> 2. Delete all the ovn related code from the root dir. Right now there is
>>> no history for the OVN files in the ovn-org/ovn repo
>>> 3. Copy OVN files from openvswitch/ovs repo using git-filter-branch.
>>> This will preserver the history.
>>> 4. Sync the test files from ovs subtree so that tests pass.
>>> During this period its better to freeze merging OVN related patches in
>>> the OVS repo.
>>> And finally delete the OVN related code from the OVS repo.
>>> I have done a PoC here -
>>> https://github.com/numansiddique/ovn/commits/ovn_sync_from_ovs_v3/p4
>>> All the relates commits can be found here.
>>> Does these steps seem fine ? Any concerns ?
>>> If this seems fine, can we choose a date to start this process ?
>>> Thanks
>>> Numan

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