RustInQemu

For the old RustInQemu page, see RustInQemu/2022

Active effort

• Current state
• Documentation
• Past updates: April 2025 | January 2025 | November 2024

Past efforts

• [RFC v3 00/32] Rust binding for QAPI and qemu-ga QMP handler examples
  on patchew on lore
• Subject: [RFC 0/6] scripts: Rewrite simpletrace printer in Rust
Date: Mon, 27 May 2024 16:14:15 +0800
  RFC v1

Work in progress

To be merged

• let Meson handle mixed-language linking of Rust and C objects: avoids staticlib hack, and optionally enables usage of Rust libstd

needs const_refs_static in Rust 1.83.0:

• complete vmstate bindings
• first round of typesafe qdev property generation

Paolo

• Improving Cargo support in Meson
• Tracing (summer of code 2025)

Manos

• generate qdev properties via macros

Zhao

• vm-memory integration

Kevin

• Executing async code, block driver implementations
  • https://lore.kernel.org/qemu-devel/20250211214328.640374-1-kwolf@redhat.com/

Bugs

• Add BQL abstraction for tests - avoid running them with "--test-threads 1"

Possible project targets

Projects with some code

• visitors/QOM properties, could be interesting for hw/sensor/tmp105.c...
  • https://lore.kernel.org/qemu-devel/20250605101124.367270-1-pbonzini@redhat.com/

Check if distros package the dependent Rust crates

Mostly useful for distros to enable Rust when building QEMU.

• Missing in Fedora: arbitrary-int, bilge, bilge-impl, foreign
  • Fedora does have bitfield-struct, which is a bit inferior to bilge in some respects but smaller
• Debian?

Cleanups

• split qemu_api into multiple crates (each with its own prelude, too)
• look into replacing pointer and BqlCell usage in HPET with self_cell (e.g. BqlRefCell<SelfCell<HPETRegisters, [HPETTimer; 8]>>).

Nice things to have

• Remove need for manual "meson subprojects update --reset" when updating packagefiles/
• Improve tool integration
  • Run code checks a la "meson test --suite codecheck"? (clippy and rustfmt)
• Place rustdoc output for master somewhere?
  • Or generate with sphinx, with something like sphinx-rust
• More bindings: I2C?

New code to write

• more QOM procedural macros
  • generate qdev properties (started)
  • generate parts of TypeInfo?
  • monomorphization of T: IsA<Class> to &T (like the momo crate)
• safe object creation with pinned_init, originating from Linux)
  • https://lore.kernel.org/qemu-devel/aCysct2L8Bosqy0N@intel.com/
• Character device flow control

Improved clippy coverage in CI?

• run clippy as part of "make check"
• add to CI a fallible job that runs on nightly clippy with -Dclippy::complexity -Dclippy::perf -Dclippy::suspicious -Dclippy::style -Dunknown_lints. the job should generally pass, and if a new lint triggers it probably should be added to Cargo.toml as either "allow" (rare) or "deny" (possibly after adding #[allow()] to the source).

Miscellanea

• qemu-bridge-helper.c Re-write SUID C executable with useful features.

Devices

• hw/block/pflash_cfi01.c, hw/block/pflash_cfi02.c (claimed, WIP)
  • needs block bindings
• hw/timer/i8254.c (claimed, WIP)
• hw/mem/nvdimm.c (suggested by Manos)