Hi Stefan, Sorry for the delay, I attach a proposal! On Wed, 29 Jan 2025 at 18:44, Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote: > > +Cc rust-vmm ML, since in past years we have used QEMU as an umbrella > project for rust-vmm ideas for GSoC. > > Thanks, > Stefano > > On Tue, 28 Jan 2025 at 17:17, Stefan Hajnoczi <stefanha@xxxxxxxxx> wrote: > > > > Dear QEMU and KVM communities, > > QEMU will apply for the Google Summer of Code internship > > program again this year. Regular contributors can submit project > > ideas that they'd like to mentor by replying to this email by > > February 7th. > > > > About Google Summer of Code > > ----------------------------------------- > > GSoC (https://summerofcode.withgoogle.com/) offers paid open > > source remote work internships to eligible people wishing to participate > > in open source development. QEMU has been doing internship for > > many years. Our mentors have enjoyed helping talented interns make > > their first open source contributions and some former interns continue > > to participate today. > > > > Who can mentor > > ---------------------- > > Regular contributors to QEMU and KVM can participate as mentors. > > Mentorship involves about 5 hours of time commitment per week to > > communicate with the intern, review their patches, etc. Time is also > > required during the intern selection phase to communicate with > > applicants. Being a mentor is an opportunity to help someone get > > started in open source development, will give you experience with > > managing a project in a low-stakes environment, and a chance to > > explore interesting technical ideas that you may not have time to > > develop yourself. > > > > How to propose your idea > > ------------------------------ > > Reply to this email with the following project idea template filled in: === vhost-user devices in Rust on macOS and *BSD === '''Summary:''' Extend rust-vmm crates to support vhost-user devices running on POSIX system like macOS and *BSD VIRTIO devices can be emulated in an external process to QEMU thanks to the vhost-user protocol, which allows QEMU to offload the entire emulation to a daemon. This is done through an AF_UNIX socket used as a control path between the frontend (i.e. QEMU) and the backend (i.e. the vhost-user daemon). QEMU will share guest memory with the daemon, provide all the information for data path setup, and notification mechanisms. Moving the emulation of VIRTIO devices to a separate process from QEMU offers significant advantages, primarily in terms of safety, if a device crashes, we can restart it without affecting QEMU. Additionally, this approach simplifies updating device implementations, allows development in other languages (such as Rust as we do in the rust-vmm community), and enhances isolation through seccomp, cgroups, and similar mechanisms. The rust-vmm community already provides several crates (e.g. vhost, vhost-user-backend, etc.) to implement a vhost-user backend in an external daemon. For example, these crates are used by virtiofsd (virtio-fs vhost-user device) but also by all vhost-user devices maintained by the rust-vmm community in the rust-vmm/vhost-device workspace. These crates work great on Linux, but unfortunately they use some Linux-specific system calls such as epoll(7) and eventfd(2) that make them impossible to use on other POSIX systems. The goal of this project is to make sure that we can use rust-vmm's vhost and vhost-user-backend crates on other POSIX systems besides Linux. If time permits, we could also fix up simple devices such as vhost-device-console or vhost-device-vsock to run on any POSIX systems. '''Tasks:''' * Becoming familiar with QEMU and vhost-user devices * Run QEMU with a vhost-user device on macOS or FreeBSD/OpenBSD as covered in the FOSDEM 2025 talk * Analyze rust-vmm crates (vmm-sys-util, vhost, vhost-user-backend) to understand which components are Linux-specific * Replace epoll(7) with alternatives such as https://github.com/smol-rs/polling * Automatic fallback to pipe()/pipe2() if eventfd(2) is not available as QEMU already does * Handle any other cases discovered during the analysis * Adapt a simple device such as vhost-device-console or vhost-device-vsock to test that everything works on macOS or FreeBSD/OpenBSD '''Links:''' * FOSDEM 2025 talk: [https://fosdem.org/2025/schedule/event/fosdem-2025-5100-can-qemu-and-vhost-user-devices-be-used-on-macos-and-bsd-/ Can QEMU and vhost-user devices be used on macOS and *BSD?] * [https://qemu-project.gitlab.io/qemu/interop/vhost-user.html vhost-user spacification] * [https://patchew.org/QEMU/20240618100043.144657-1-sgarzare@xxxxxxxxxx/ QEMU series to support vhost-user on any POSIX] * [https://gitlab.com/sgarzarella/qemu/-/tree/macos-vhost-user sgarzare's tree where to find some missing QEMU patches] * [https://github.com/rust-vmm/vhost rust-vmm vhost & vhost-user-backend crates] * [https://github.com/rust-vmm/vmm-sys-util rust-vmm vmm-sys-util crate] * [https://github.com/rust-vmm/vhost-device rust-vmm vhost-device workspace] * [https://gitlab.com/virtio-fs/virtiofsd virtio-fs vhost-user device] * [https://github.com/rust-vmm/vhost/issues/110 Mac build support #110 - rust-vmm/vhost] * [https://gitlab.com/virtio-fs/virtiofsd/-/issues/169 Add macOS support #169 - virtio-fs/virtiofsd] '''Details:''' * Project size: 350 hours * Skill level: intermediate * Language: Rust * Mentors: Stefano Garzarella <sgarzare@xxxxxxxxxx>, German Maglione <gmaglione@xxxxxxxxxx> Thanks, Stefano
