linux-kernel - Re: [PATCH 0/3] Add NETIF_F_HW

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Message-Id: <20190822.153209.365750764799027706.davem@davemloft.net>
Date:   Thu, 22 Aug 2019 15:32:09 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     horatiu.vultur@...rochip.com
Cc:     roopa@...ulusnetworks.com, nikolay@...ulusnetworks.com,
        UNGLinuxDriver@...rochip.com, alexandre.belloni@...tlin.com,
        allan.nielsen@...rochip.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, bridge@...ts.linux-foundation.org
Subject: Re: [PATCH 0/3] Add NETIF_F_HW_BRIDGE feature

From: Horatiu Vultur <horatiu.vultur@...rochip.com>
Date: Thu, 22 Aug 2019 21:07:27 +0200

> Current implementation of the SW bridge is setting the interfaces in
> promisc mode when they are added to bridge if learning of the frames is
> enabled.
> In case of Ocelot which has HW capabilities to switch frames, it is not
> needed to set the ports in promisc mode because the HW already capable of
> doing that. Therefore add NETIF_F_HW_BRIDGE feature to indicate that the
> HW has bridge capabilities. Therefore the SW bridge doesn't need to set
> the ports in promisc mode to do the switching.
> This optimization takes places only if all the interfaces that are part
> of the bridge have this flag and have the same network driver.
> 
> If the bridge interfaces is added in promisc mode then also the ports part
> of the bridge are set in promisc mode.

This doesn't look right at all.

The Linux bridge provides a software bridge.

By default, all hardware must provide a hardware implementation of
that software bridge behavior.

Anything that deviates from that behavior has to be explicitly asked
for by the user by explicit config commands.