Shreyansh Chouhan <chouhan.shreyansh2...@gmail.com> writes:
> Just an update: > > I've studied the virtio specification along with the source code and I now > understand what the device implementation is > going to look like. Also I understand the source code a lot better. I am > now reading about the qemu vhost-user protocol. > > Although I haven't read about the vhost-user daemon in detail, from what > little I have read, I would say that the daemon > would get the virtqueues from the virtio device and forward it to the sound > device of the host. (This is the hard part > I think, since an in QEMU device would use code already written for > processing these queues.) I can't comment on the difficulty there but this does point more towards using the in-QEMU approach given we have a bunch of utility functions already. > I think only the tx and rx > queues would be shared, and although I do not know exactly how the sharing > will be implemented, I think the memory > will be shared to the vhost-user daemon too? So now the virtqueue memory is > shared between the virtio driver in guest > OS, the virtio device in QEMU, and the vhost-user daemon running in the > host userspace. QEMU uses a memfd file descriptor to share the guests entire memory map with the daemon. > As for the configuration part, the driver will negotiate features with the > virtio device in QEMU, which in turn will communicate > with the vhost-user daemon (via sockets) to get the features supported I > think. > > This is what I think it will roughly look like. (Of course modulo the > implementation details.) I do not yet understand how > much more difficult will implementing the vhost-user daemon be, and since I > was already > warned about the difficulty, I will not risk making any hasty decisions > that later hinder the project. I will read up > about the vhost-user daemon and how it's implemented to get a better idea, > and then make the final call. If you want to see an example of a branch new vhost-user daemon being built up from scratch see my recent virtio-rpmb series. The first few patches of in-QEMU code will be the same boilerplate either way I think: https://patchew.org/QEMU/20200925125147.26943-1-alex.ben...@linaro.org/ > Anyways I am super excited about the project. I got to learn about some > really cool things in the past couple of days, > and I can not wait to implement it. :) -- Alex Bennée
