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]. 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. Regards, Mathieu > > Thanks > Guennadi > > [1] https://thesofproject.github.io/latest/developer_guides/virtualization/virtualization.html
