[ovs-discuss] flow match reg0=1 is not working

[Ben Pfaff]

On Wed, May 27, 2020 at 11:24:24AM +0200, Miroslav Kubiczek wrote:
> I'd like to configure flows to use different table based on packet size. I
> have configured the flows like this:
> 
> #ovs-ofctl dump-flows br0
> ...
> cookie=0x0, table=0, priority=20000
> actions=check_pkt_larger(100)->NXM_NX_REG0[0],resubmit(,1)
> cookie=0x1, table=1, priority=1000,udp,reg0=0,tp_dst=2123
> actions=resubmit(,2)
> ...
> 
> The problem is that the 2nd flow is always positive, i.e. it's always
> resubmitted to table 2. I tried it also with reg0=1 but it has the same
> effect. Am I doing anything wrong or is it a bug?

This makes it sound like the feature doesn't work at all, but we know
that it does, since it's used in OVN.  In your place, I'd launch into
the general purpose troubleshooting procedure here, starting with
checking the "ofproto/trace" results, then looking at the datapath
flows, and moving on from there.