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Date:   Fri, 4 Nov 2022 20:05:30 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Maxime Chevallier <maxime.chevallier@bootlin.com>
Cc:     davem@davemloft.net, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        thomas.petazzoni@bootlin.com, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        linux-arm-kernel@lists.infradead.org,
        Vladimir Oltean <vladimir.oltean@nxp.com>,
        Luka Perkov <luka.perkov@sartura.hr>,
        Robert Marko <robert.marko@sartura.hr>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>
Subject: Re: [PATCH net-next v8 3/5] net: dsa: add out-of-band tagging
 protocol
Message-ID: <20221104200530.3bbe18c6@kernel.org>
In-Reply-To: <20221104174151.439008-4-maxime.chevallier@bootlin.com>
References: <20221104174151.439008-1-maxime.chevallier@bootlin.com>
        <20221104174151.439008-4-maxime.chevallier@bootlin.com>
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On Fri,  4 Nov 2022 18:41:49 +0100 Maxime Chevallier wrote:
> This tagging protocol is designed for the situation where the link
> between the MAC and the Switch is designed such that the Destination
> Port, which is usually embedded in some part of the Ethernet Header, is
> sent out-of-band, and isn't present at all in the Ethernet frame.
> 
> This can happen when the MAC and Switch are tightly integrated on an
> SoC, as is the case with the Qualcomm IPQ4019 for example, where the DSA
> tag is inserted directly into the DMA descriptors. In that case,
> the MAC driver is responsible for sending the tag to the switch using
> the out-of-band medium. To do so, the MAC driver needs to have the
> information of the destination port for that skb.
> 
> Add a new tagging protocol based on SKB extensions to convey the
> information about the destination port to the MAC driver

This is what METADATA_HW_PORT_MUX is for, you shouldn't have 
to allocate a piece of memory for every single packet.

Also the series doesn't build.