Re: [RFC net-next v3 04/10] net: bridge: mrp: Add generic netlink interface to configure MRP

[Allan W. Nielsen]

On 25.01.2020 16:34, Andrew Lunn wrote:
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> On Fri, Jan 24, 2020 at 05:18:22PM +0100, Horatiu Vultur wrote:
> > Implement the generic netlink interface to configure MRP. The implementation
> > will do sanity checks over the attributes and then eventually call the MRP
> > interface which eventually will call the switchdev API.
> What was your thinking between adding a new generic netlink interface,
> and extending the current one?
>
> I've not looked at your user space code yet, but i assume it has to
> make use of both? It needs to create the bridge and add the
> interfaces. And then it needs to control the MRP state.
>
> Allan mentioned you might get around to implementing 802.1CB? Would
> that be another generic netlink interface, or would you extend the MRP
> interface?
Horatiu, if you have given this any thoughts, then please share them.

Here are my thoughts on 802.1CB: If we look at this with the traditional
NIC/host POW, then it would be natural to look at the HSR interface as
Vinicius suggested, and expose it as a new interface (HSR0). But when
looking at how 802.1CB say a bridge should act, and also what the
capabilities of the HW are, then it seem more natural to extend the TC
system. In HW it is a TCAM classifying the traffic, and it has some
actions to either replicate the matched frames, or eliminate the
additional copies.

The HW also supports CFM (see [1]), which we need (partly) to complete
the MRP implementation with MIM/MIC roles. This is also useful for none
MRP users (like ERPS).

This seems like an argument for moving this to the existing netlink
interfaces instead of having it as a generic netlink.

[1] https://en.wikipedia.org/wiki/IEEE_802.1ag

/Allan