On Mon, Jun 10, 2024 at 10:47 PM Stefan Hajnoczi <stefa...@gmail.com> wrote: > On Mon, 10 Jun 2024 at 16:27, Manos Pitsidianakis > <manos.pitsidiana...@linaro.org> wrote: > > > > On Mon, 10 Jun 2024 22:59, Stefan Hajnoczi <stefa...@gmail.com> wrote: > > >> What are the issues with not using the compiler, rustc, directly? > > >> ----------------------------------------------------------------- > > >> [whataretheissueswith] Back to [TOC] > > >> > > >> 1. Tooling > > >> Mostly writing up the build-sys tooling to do so. Ideally we'd > > >> compile everything without cargo but rustc directly. > > > > > >Why would that be ideal? > > > > It remove the indirection level of meson<->cargo<->rustc. I don't have a > > concrete idea on how to tackle this, but if cargo ends up not strictly > > necessary, I don't see why we cannot use one build system. > > The convenience of being able to use cargo dependencies without > special QEMU meson build system effort seems worth the overhead of > meson<->cargo<->rustc to me. There is a blog post that explores using > cargo crates using meson's wrap dependencies here, and it seems like > extra work: > https://coaxion.net/blog/2023/04/building-a-gstreamer-plugin-in-rust-with-meson-instead-of-cargo/
The worst part of using cargo from meson (like in libblkio) is the lack of integration with Rust tests, but otherwise it's a much better experience. IIUC Meson's cargo subprojects do not support build.rs, which is a problem if one of your dependencies (for example libc) needs it. https://mesonbuild.com/Wrap-dependency-system-manual.html#cargo-wraps On the other hand, I think it's possible, possibly even clearer, to invoke bindgen from meson. I would prefer to have many small .rs files produced by bindgen, to be imported via "use", and I would prefer an allowlist approach that excludes symbols from system headers. > > >I guess there will be interest in using rust-vmm crates in some way. Yes, especially the ByteValued, VolatileMemory and Bytes traits. One complication in that respect is that anything that does DMA depends on either RCU or the BQL. We could, at least at the beginning, introduce a dummy guard that simply enforces at run-time that the BQL is taken. Paolo
