linux-kernel - Re: [PATCH net-next v4 0/7] Add RPMSG Ethernet Driver

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Message-ID: <7cd06f8f-bd74-429d-bf2c-71858178950a@ti.com>
Date: Wed, 17 Sep 2025 17:14:57 +0530
From: MD Danish Anwar <danishanwar@...com>
To: Andrew Davis <afd@...com>, "David S. Miller" <davem@...emloft.net>,
        Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni
	<pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
        Jonathan Corbet
	<corbet@....net>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra
	<vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>, Rob Herring
	<robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
	<conor+dt@...nel.org>,
        Andrew Lunn <andrew+netdev@...n.ch>,
        Mengyuan Lou
	<mengyuanlou@...-swift.com>,
        Lei Wei <quic_leiwei@...cinc.com>, Xin Guo
	<guoxin09@...wei.com>,
        Michael Ellerman <mpe@...erman.id.au>, Fan Gong
	<gongfan1@...wei.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Parthiban
 Veerasooran <Parthiban.Veerasooran@...rochip.com>,
        Lukas Bulwahn
	<lukas.bulwahn@...hat.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>
CC: <netdev@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH net-next v4 0/7] Add RPMSG Ethernet Driver

Hi Andrew,

On 11/09/25 9:34 pm, Andrew Davis wrote:
> On 9/11/25 6:36 AM, MD Danish Anwar wrote:
>> This patch series introduces the RPMSG Ethernet driver, which provides a
>> virtual Ethernet interface for communication between a host processor and
>> a remote processor using the RPMSG framework. The driver enables
>> Ethernet-like packet transmission and reception over shared memory,
>> facilitating inter-core communication in systems with heterogeneous
>> processors.
>>
> 
> This is neat and all but I have to ask: why? What does this provide
> that couldn't be done with normal RPMSG messages? Or from a userspace
> TAP/TUN driver on top of RPMSG?
> 

This is different from RPMSG because here I am not using RPMSG to do the
actual TX / RX. RPMSG is only used to share information (tx / rx
offsets, buffer size, etc) between driver and firmware. The TX / RX
happens in the shared memory. This implementation uses a shared memory
circular buffer with head/tail pointers for efficient data passing
without copies between cores.

> This also feels like some odd layering, as RPMSG sits on virtio, and
> we have virtio-net, couldn't we have a firmware just expose that (or
> would the firmware be vhost-net..)?
> 

PMSG sits on virtio, and we do have virtio-net but I am not trying to do
ethernet communication over RPMSG. RPMSG is only used to exchange
information between cores regarding the shared memory where the actual
ethernet communication happens.

> Andrew
> 


-- 
Thanks and Regards,
Danish