Re: [RFC PATCH 0/6] virtio: Add support for Virtio message transport

[Rob Herring]

On Wed, Jul 30, 2025 at 4:29 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
>
> Hello,
>
> This RFC series introduces support for a new Virtio transport type:
> "virtio-msg", as proposed in [1]. Unlike existing transport types like
> virtio-mmio or virtio-pci, which rely on memory-mapped registers, virtio-msg
> implements transport operations via structured messages. Those messages can be
> transported through different mechanisms such as mailboxes, shared memory based
> FIFO or specific protocols such as FF-A on Arm.
>
> This series includes:
> - Core virtio-msg transport support.
> - Two message transport bus implementations:
>   - virtio-msg-ffa: based on ARM's Firmware Framework for Arm (FF-A).
>   - virtio-msg-loopback: a loopback device for testing and validation.
>
> The code is available here for reference: [2] and virtio-msg loopback and FF-A
> test setups are explained here: [3] and [4].
>
> This series is based on v6.16 and depends on commit [5].
>
>
> ### Memory Mapping and Reserved Memory Usage
>
> The first two patches enhance the reserved-memory subsystem to support attaching
> struct device`s that do not originate from DT nodes — essential for virtual or
> dynamically discovered devices like the FF-A or loopback buses.

We support creating devices from reserved-memory nodes. Just add a
compatible which you should do anyways because node names are not
supposed to be that specific or an ABI.

Rob