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

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Message-ID: <8a20160e-1528-4d0e-9347-0561fc3426b4@ti.com>
Date: Thu, 11 Sep 2025 11:04:02 -0500
From: Andrew Davis <afd@...com>
To: MD Danish Anwar <danishanwar@...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

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 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..)?

Andrew

> Key features of this driver:
> 
> 1. Virtual Ethernet interface using RPMSG framework
> 2. Shared memory-based packet transmission and reception
> 3. Support for multicast address filtering
> 4. Dynamic MAC address assignment
> 5. NAPI support for efficient packet processing
> 6. State machine for managing interface states
> 
> This driver is designed to be generic and vendor-agnostic. Vendors can
> develop firmware for the remote processor to make it compatible with this
> driver by adhering to the shared memory layout and communication protocol
> described in the documentation.
> 
> This patch series has been tested on a TI AM64xx platform with a
> compatible remote processor firmware. Feedback and suggestions for
> improvement are welcome.
> 
> Changes from v3 to v4:
> - Addressed comments from Parthiban Veerasooran regarding return values in
>    patch 4/7
> - Added "depends on REMOTEPROC" in Kconfig entry for RPMSG_ETH as it uses a
>    symbol from REMOTEPROC driver.
> 
> Changes from v2 to v3:
> - Removed the binding patches as suggested by Krzysztof Kozlowski <krzk@...nel.org>
> - Dropped the rpmsg-eth node. The shared memory region is directly added to the
>    "memory-region" in rproc device.
> - Added #include <linux/io.h> header for memory mapping operations
> - Added vendor-specific configuration through rpmsg_eth_data structure
> - Added shared memory region index support with shm_region_index parameter
> - Changed RPMSG channel name from generic "shm-eth" to vendor-specific "ti.shm-eth"
> - Fixed format string warning using %zu instead of %lu for size_t type
> - Updated Documentation to include shm_region_index
> - Added MAINTAINERS entry for the driver
> 
> v3 https://lore.kernel.org/all/20250908090746.862407-1-danishanwar@ti.com/
> v2 https://lore.kernel.org/all/20250902090746.3221225-1-danishanwar@ti.com/
> v1 https://lore.kernel.org/all/20250723080322.3047826-1-danishanwar@ti.com/
> 
> MD Danish Anwar (7):
>    net: rpmsg-eth: Add Documentation for RPMSG-ETH Driver
>    net: rpmsg-eth: Add basic rpmsg skeleton
>    net: rpmsg-eth: Register device as netdev
>    net: rpmsg-eth: Add netdev ops
>    net: rpmsg-eth: Add support for multicast filtering
>    MAINTAINERS: Add entry for RPMSG Ethernet driver
>    arch: arm64: dts: k3-am64*: Add shared memory region
> 
>   .../device_drivers/ethernet/index.rst         |   1 +
>   .../device_drivers/ethernet/rpmsg_eth.rst     | 424 ++++++++++++
>   MAINTAINERS                                   |   6 +
>   arch/arm64/boot/dts/ti/k3-am642-evm.dts       |  11 +-
>   drivers/net/ethernet/Kconfig                  |  11 +
>   drivers/net/ethernet/Makefile                 |   1 +
>   drivers/net/ethernet/rpmsg_eth.c              | 653 ++++++++++++++++++
>   drivers/net/ethernet/rpmsg_eth.h              | 294 ++++++++
>   8 files changed, 1399 insertions(+), 2 deletions(-)
>   create mode 100644 Documentation/networking/device_drivers/ethernet/rpmsg_eth.rst
>   create mode 100644 drivers/net/ethernet/rpmsg_eth.c
>   create mode 100644 drivers/net/ethernet/rpmsg_eth.h
> 
> 
> base-commit: 1f24a240974589ce42f70502ccb3ff3f5189d69a