Re: [PATCH 14/16] hw/i3c: remote_i3c: Add model

[Jeremy Kerr <jk@codeconstruct.com.au>]

Hi Joe,

> Adds a model to communicate to remote I3C devices over chardev. This
> allows QEMU to communicate to I3C targets that exist outside of QEMU.

Nice!

I've been wanting something similar for a while, both for i2c and i3c
busses, to the point of having a similar concept partly implemented.

A couple of design decisions though:

1) Is this something that qemu upstream would accept? Do we need a
formal description of the guest-to-host interface somewhere? Or is there
a more standard way of exposing busses like this?

2) My approach was at the bus level rather than the device level: the
protocol is bidirectional to allow the model to either participate as a
i3c controller or a target. There's quite a bit of mis-fit when applying
that to the qemu device structure though, so your approach is a lot
cleaner.

I'll have a go at adapting my client to your protocol, and see how the
device interface goes.

Assuming we do adopt your approach though, I think the protocol
description needs some work. There seems to be other messages not listed
in your protocol comments, and the direction of some seems to be
reversed. I'm happy to contribute to that documentation if you like.

Cheers,


Jeremy