Re: [PATCH net-next 08/12] net: dsa: rzn1-a5psw: add FDB support

From: "Clément Léger" <clement.leger@bootlin.com>
To: Vladimir Oltean <olteanv@gmail.com>
Cc: "Andrew Lunn" <andrew@lunn.ch>,
	"Vivien Didelot" <vivien.didelot@gmail.com>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Geert Uytterhoeven" <geert+renesas@glider.be>,
	"Magnus Damm" <magnus.damm@gmail.com>,
	"Heiner Kallweit" <hkallweit1@gmail.com>,
	"Russell King" <linux@armlinux.org.uk>,
	"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
	"Herve Codina" <herve.codina@bootlin.com>,
	"Miquèl Raynal" <miquel.raynal@bootlin.com>,
	"Milan Stevanovic" <milan.stevanovic@se.com>,
	"Jimmy Lalande" <jimmy.lalande@se.com>,
	linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
	linux-renesas-soc@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH net-next 08/12] net: dsa: rzn1-a5psw: add FDB support
Date: Thu, 21 Apr 2022 09:38:03 +0200	[thread overview]
Message-ID: <20220421093803.64ad7cc8@fixe.home> (raw)
In-Reply-To: <20220420195214.dnekbfhha53trbke@skbuf>

Le Wed, 20 Apr 2022 22:52:14 +0300,
Vladimir Oltean <olteanv@gmail.com> a écrit :

> > > 
> > > Shouldn't this contain something along the lines of a VID, FID, something?  
> > 
> > This is extracted directly from the datasheet [1]. The switch FDB table
> > does not seems to store the VID with the entries (See page 300).
> > 
> > [1]
> > https://www.renesas.com/us/en/document/mah/rzn1d-group-rzn1s-group-rzn1l-group-users-manual-r-engine-and-ethernet-peripherals  
> 
> Thanks for the link. I see that the switch has a non-partitionable
> lookup table, not even by VLAN. A shame.
> 
> This is also in contrast with the software bridge driver, where FDB and
> MDB entries can have independent destinations per VID.
> 
> So there's nothing you can do beyond limiting to a single offloaded
> bridge and hoping for the best w.r.t. per-VLAN forwarding destinations.
> 
> Note that if you limit to a single bridge does not mean that you can
> declare ds->fdb_isolation = true. Declaring that would opt you into
> unicast and multicast filtering towards the CPU, i.o.w. a method for
> software to only receive the addresses it has expressed an interest in,
> rather than all packets received on standalone ports. The way that is
> implemented in DSA is by adding FDB and MDB entries on the management
> port, and it would break a lot of things without a partitioning scheme
> for the lookup table.

Thanks Vladimir, it confirms what I thought.

-- 
Clément Léger,
Embedded Linux and Kernel engineer at Bootlin
https://bootlin.com