Hi Alexandra, Ilya,

On 12/19/25 1:18 PM, Ilya Maximets wrote:
> On 12/18/25 6:05 PM, Rukomoinikova Aleksandra wrote:
>> Hi everyone!
>>
>> I added maintainers to copy because I really need your opinion)
>>
>> It seems we are already exceeding the number of available registers in 
>> Open vSwitch, at least at the controller level.
>>
>> Currently, all registers accessible to the controller are already in 
>> use. Earlier in this thread, I sent RFC patch, which at the moment is 
>> nothing more than a messy proof of concept, precisely because I ran into 
>> the issue of lacking registers at the controller level. My goal is 
>> passing register values between pipelines, which can be possible only 
>> with ovn-controller registers. For now, I've implemented this through  a 
>> very dirty workaround using registers from northd, which is just 
>> terrible, but I couldn't find another option.
>>
>> What do you think: should we expand the number of registers in Open 
>> vSwitch? It seems it's time! If it seems it's not yet the right moment, 
>> should I add a separate mff_ field in OVS? I initially dismissed this 
>> idea because transferring a routing table doesn't really fit into the 
>> OpenFlow concept.
>>
>> Thanks in advance! If we agree that it's time to expand the registers, I 
>> would like to take this on myself.
> Hi!  The increase of the number of registers was brought up multiple times,
> I believe, in the recent years.  The latest conversation happened in the
> following thread just recently:
>   https://mail.openvswitch.org/pipermail/ovs-dev/2025-October/426703.html
> 
> And, AFAIK, Dumitru already started working on that some time ago with a
> plan to likely post it in time for the OVS 3.7 soft freeze.  So, we may
> hopefully see a patch for that soon.
> 

I managed to post the patch now, hopefully in time for someone to review
it before soft freeze:

https://patchwork.ozlabs.org/project/openvswitch/patch/[email protected]/

I also ran OVN tests (with a modified version of OVN that still only
uses 16 registers but compiles with OVS that supports 32 registers) and
CI looked green there too.

> FWIW, there was also an off-list conversation about detection of support
> for new registers and how to properly handle turning new features on and
> off based on that.  Primarily in context of maintainability.  E.g. we
> likely need to just not allow use of new features that require extra
> registers instead of trying to work around the limitation and implement
> the same feature differently based on availability.  But that's a separate
> topic that can be explored when implementing first features that need new
> registers in OVN.
> 

I agree, let's figure out the right way to consume this in OVN in the
future.

Regards,
Dumitru

> Best regards, Ilya Maximets.
> 

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