Re: [RFC net-next v3 00/10] net: bridge: mrp: Add support for Media Redundancy Protocol (MRP)

From: Jakub Kicinski
Date: Tue Feb 18 2020 - 11:55:26 EST

On Tue, 18 Feb 2020 13:18:11 +0100 Allan W. Nielsen wrote:
> But we should try make sure this also works in a backwards compatible
> way with future MRP aware HW, and with existing (and future) SwitchDev
> offloaded HW. At the very least we want to make this run on Ocelot, HW
> offload the MRC role, but do the MRM in SW (as the HW is not capable of
> this).
> If we use the kernel to abstract the MRP forwarding (not the entire
> protocol like we did in v1/v2, not just the HW like we did in v3) then
> we will have more flxibility to support other HW with a different set of
> offload facilities, we can most likely achieve better performance, and
> it would be a cleaner design.
> This will mean, that if user-space ask for MRP frame to be generated,
> the kernel should make sure it will happen. The kernel can try to
> offload this via the switchdev API, or it can do it in kernel-space.
> Again, it will mean putting back some code into kernel space, but I
> think it is worth it.

FWIW having the guarantee that the kernel can always perform requested
service/operation (either thru offload or in SW in kernel space) seems
appealing and in line what we've been doing for other offloads.

IOW it'd be nice to have a kernel space software fallback for the
offloaded operations.