Hi Mathieu, On Thu, Apr 16, 2020 at 11:50:48AM -0600, Mathieu Poirier wrote: > Good day Guennadi, > > On Thu, 16 Apr 2020 at 08:06, Guennadi Liakhovetski > <guennadi.liakhovetski@xxxxxxxxxxxxxxx> wrote: > > > > Hi, > > > > It has been proposed to port the VirtIO SOF driver [1], used to > > implement audio support under Linux, running in a KVM guest, to use > > RPMSG to communicate with the SOF vhost driver, running on the Linux > > host. On one hand I see an rpmsg-virtio driver, which should make such > > a port possible, on the other hand I don't see a single VirtIO driver > > in the kernel, using RPMSG for Linux virtualisation. > > Above you wrote "rpmsg-virtio" driver, which I take to mean the code > found in file virtio_rpmsg_bus.c [1]. Exactly. > The code in [1] centers around > the communication between an application processor and some form of > remote processor (micro controller or dsp). The "virtio" part of the > name refers to the underlying infrastructure put in place to > communicate with the remote processor, all coming from the virtio > space. Here instead of using the virtio mechanic to communicate > between a host and a guest, it is used to communicate with a remote > processor. > > I came to the same conclusion a while back - as of today no virtio > drivers are using RPMSG to communicate between host and guest. I > suppose nobody needed it or implemented their own schemes. > > [1]. https://elixir.bootlin.com/linux/v5.7-rc1/source/drivers/rpmsg/virtio_rpmsg_bus.c > > > > > Hence my questions: is this a good idea? Is there anything in the > > kernel VirtIO RPMSG implementation, that would make this impossible? > > I don't see why it wouldn't be a good idea, nor what would technically > prevent such a thing from happening. Two things work in your favour: > 1) the RPMSG foundation has been tailored to be used over different > kinds of hardware and 2) an existing implementation is already using > virtioqueues. > > I suggest to start looking at function rpmsg_register_device(), used > by different RPMSG drivers - the magic is really in the RPMSG > operations (struct rpmsg_device_ops) that are used to abstract the HW > implementation. Exactly, just what I was thinking too. And I also think it can well be possible to reuse the code in virtio_rpmsg_bus.c, possibly with some limited extensions and modifications. I'll get it rolling then. Thanks Guennadi > Regards, > Mathieu > > > [1] https://thesofproject.github.io/latest/developer_guides/virtualization/virtualization.html
