Re: [RFC PATCH net-next 0/4] switchdev: avoid duplicate packet forwarding

On Tue, Jun 16, 2015 at 11:30 PM, Jiri Pirko [off-list ref] wrote:

Scott, again, I'm not talking about br0 ifindex! I'm talking about
ifindexes of the port netdevs.

br0
  sw1p1  ifindex=1
  sw1p2  ifindex=2
  sw2p1  ifindex=3
  sw2p2  ifindex=4


now we have 2 groups, one in each switch. So for sw1 group (sw1p1 and
sw1p2) we select mark one of the ifindexes, so either "1" or "2"
For second group, from sw2 we select "3" or "4". So for example:
br0
  sw1p1  mark=1
  sw1p2  mark=1
  sw2p1  mark=4
  sw2p2  mark=4

This is generic, usable for every group.

Oooh, that's good.  I like it.  If the port is not grouped, set
mark=ifindex.  Or mark=0 to have a dflt group for ungrouped ports.

Do you see a way to code this up?  The only thing that comes to mind
is for the swX driver to keep track of mark picked for each bridge
brY, but I was hoping you have an idea how to do this without any
storage?