RustInQemu: Difference between revisions

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For the old RustInQemu page, see [[RustInQemu/2022]]
For the old RustInQemu page, see [[RustInQemu/2022]]


== Active efforts in 2024 ==
== Active effort ==


* <code>Subject: [RFC 0/6] scripts: Rewrite simpletrace printer in Rust</code><br /><code>Date: Mon, 27 May 2024 16:14:15 +0800</code><br />[https://lore.kernel.org/qemu-devel/20240527081421.2258624-1-zhao1.liu@intel.com/ RFC v1]
* [https://lore.kernel.org/qemu-devel/d3d1944e-2482-4aa7-b621-596246a08107@gnu.org/ Current state]
* ARM PL011 UART device model in Rust<br /><code>Subject: [RFC PATCH v1 0/6] Implement ARM PL011 in Rust</code><br /><code>Date: Mon, 10 Jun 2024 21:22:35 +0300</code><br />[https://lore.kernel.org/qemu-devel/cover.rust-pl011-rfc-v1.git.manos.pitsidianakis@linaro.org/ RFC v1] [https://lore.kernel.org/qemu-devel/rust-pl011-rfc-v6.git.manos.pitsidianakis@linaro.org/ v6]
* [https://www.qemu.org/docs/master/devel/rust.html Documentation]
** Meson and configure integration
* Past updates: [https://lore.kernel.org/qemu-devel/17ad81c3-98fc-44c2-8f65-f5e2cc07030b@gnu.org/ January 2025] |  [https://lore.kernel.org/all/cc40943e-dec1-4890-a1d9-579350ce296f@pbonzini.local/ November 2024]
** Bindings generation
 
After some discussion we decided to use rustc directly without going through cargo and each external crate becomes a Meson subproject. Meson 1.5.0+'s support for <tt>method = cargo</tt> is pretty good for host-compiled packages, but it doesn't work for dependencies of build-compiled packages (i.e. dependencies of procedural macros). This is tracked by https://github.com/mesonbuild/meson/issues/11121. Until then, meson.build files for procedural macros and their dependencies have to be written by hand. (Currently _all_ dependencies use hand-written meson.build).
 
While cargo would be fine as an interim solution, using Meson to compile the Rust code removes some moving parts. The extra cost of writing meson.build files for dependencies is expected to be small and will mostly happen upfront.


== Past efforts ==
== Past efforts ==


* <code>[RFC v3 00/32] Rust binding for QAPI and qemu-ga QMP handler examples</code><br />[https://patchew.org/QEMU/20210907121943.3498701-1-marcandre.lureau@redhat.com/ on patchew] [https://lore.kernel.org/qemu-devel/20210907121943.3498701-1-marcandre.lureau@redhat.com/ on lore]
* <code>[RFC v3 00/32] Rust binding for QAPI and qemu-ga QMP handler examples</code><br />[https://patchew.org/QEMU/20210907121943.3498701-1-marcandre.lureau@redhat.com/ on patchew] [https://lore.kernel.org/qemu-devel/20210907121943.3498701-1-marcandre.lureau@redhat.com/ on lore]
* <code>Subject: [RFC 0/6] scripts: Rewrite simpletrace printer in Rust</code><br /><code>Date: Mon, 27 May 2024 16:14:15 +0800</code><br />[https://lore.kernel.org/qemu-devel/20240527081421.2258624-1-zhao1.liu@intel.com/ RFC v1]


== Minimum supported versions ==
1.59.0 has const <tt>CStr::from_bytes_with_nul_unchecked</tt>, not really possible to go below that.
Bindgen 0.60.x has --allowlist-file. Ubuntu 22.04 has 0.59.x which is a problem.
In the future 1.83.0 would allow nested offset_of.
== Done ==
* only generate bindings.rs.inc once
* disabling the cast_ptr_alignment lint is too broad
* update bundled meson to 1.5.0
* add support for --rustc and RUSTC environment variables
* remove --no-include-path-detection from bindgen invocation
* rename subprojects to use Meson 1.5.0+ convention and add meson.override_dependency() call
* add support for cross compilation of Rust subprojects (<tt>native: true</tt> for deps of procedural macro crates)
* fix licenses for Rust subprojects
* Enable use of rustc 1.63.0
** fix cfgs for proc-macro2
** core::ffi (stable in 1.64.0)
** "if let" usage in bilge-impl needs to be patched out (stable in 1.65.0)
** std::sync::OnceLock (stable in 1.70.0)
** MaybeUninit::zeroed() (stable in 1.75.0 in const context)
** c"" literals (stable in 1.77.0)
** offset_of! (stable in 1.77.0)
* Enable use of older bindgen
** What to do about Ubuntu 22.04? Bindgen 0.59.x does not have --allowlist-file
* Install rustc/bindgen in all containers
* feature parity for pl011
** [https://lore.kernel.org/qemu-devel/CAFEAcA9X5iBFMEw3dxsgBPZo7FBuNYp3dK5gf7v+cEyVa+pErA@mail.gmail.com/T/ support pl011-luminary]
** migration
* clean up Cargo usage via workspace
== Posted ==
* [https://lore.kernel.org/qemu-devel/20241108180139.117112-1-pbonzini@redhat.com/T/ improved integration with cargo]
** automatically generate rustc flags from Cargo.toml
** Perform clippy checks and reformat code ("ninja clippy", "ninja rustfmt") - TODO: rustfmt configuration currently requires nightly due to use of unstable features
** Rustfmt, clippy, rustdoc in CI
* [https://lore.kernel.org/qemu-devel/20241104085159.76841-1-pbonzini@redhat.com/T/ qemu_irq + interior mutability]
== Work in progress ==
== Work in progress ==
=== Paolo ===
=== Paolo ===
* [https://gitlab.com/bonzini/qemu/-/commits/rust-qom QOM] (defining QOM classes entirely without macros, QOM casts and reference counting)
* Waiting for Meson 1.8.1: "objects:", rustdoc,
** also documentation for public APIs in qemu-api and qemu-api-macros
* Later: pinned_init... maybe use MaybeUninit as a first step?
* Running doctests
* Upstream Meson support for clippy, rustfmt, rustdoc


=== Manos ===
=== Manos ===
* [https://lore.kernel.org/qemu-devel/ml0lj.kelxgd4xtqc7@linaro.org/raw Fix functional tests]
=== Zhao ===
* Documentation
 
=== Kevin ===
=== Kevin ===
* Executing async code
* Executing async code, block driver implementations
* Block driver implementations
** https://lore.kernel.org/qemu-devel/20250211214328.640374-1-kwolf@redhat.com/


=== pl011 breakage ===
== Bugs ==
reproducer:
* Add BQL abstraction for tests - avoid running them with "--test-threads 1"
* [https://github.com/mesonbuild/meson/issues/8828 Distros would prefer to link libstd dynamically]; Rust-enabled QEMU binaries are huge


wget https://archives.fedoraproject.org/pub/archive/fedora/linux/releases/29/Everything/armhfp/os/images/pxeboot/vmlinuz
== Possible project targets ==
./qemu-system-arm -kernel vmlinuz -append 'printk.time=0 console=ttyAMA0' -M virt -nographic


== TODO ==
=== Nice things to have ===
* Remove need for manual "meson subprojects update --reset" when updating packagefiles/
* Remove need for manual "meson subprojects update --reset" when updating packagefiles/
* Improve tool integration
* Improve tool integration
** Run code checks a la "meson test --suite codecheck"? (clippy and rustfmt)
** Run code checks a la "meson test --suite codecheck"? (clippy and rustfmt)
* rustfmt currently requires nightly, decide what to do about it
* Place rustdoc output for master somewhere?
* Place rustdoc output for master somewhere?
* split qemu_api into multiple crates
* distros need dynamically linked libstd
** rewrite all main()s in Rust and use [https://github.com/mesonbuild/meson/issues/14224 -C prefer-dynamic]?
** or should Meson be able to link C programs with rlibs?
=== New code to write===
* more QOM procedural macros
** generate qdev properties
** generate parts of TypeInfo?
** monomorphization of <tt>T: IsA&lt;Class&gt;</tt> to <tt>&T</tt> (like the momo crate)
* feature parity for pl011
* feature parity for pl011
** check for new commits
* safe object creation with [https://docs.rs/pinned-init/ pinned_init, originating from Linux])
* bindings
* Generic Rust<->C interop, Error (https://github.com/bonzini/rust-qemu)
** MemoryRegion (callbacks)
* DMA (investigate vm-memory?)
** Chardev (callbacks, functions)
* Trace/log (Summer of Code)
** DMA (investigate vm-memory?)
* other experiments
** https://github.com/bonzini/rust-qemu (Generic Rust<->C interop, Error)
** safe object creation: use MaybeUninit in instance_init? (long-term investigate [https://docs.rs/pinned-init/ pinned_init crate, originating from Linux])
* more QOM procedural macros (currently <tt>#[derive(Object)]</tt>)
** generate qdev properties?
** generate parts of TypeInfo?


== Ideas for lints without breaking CI ==
=== Improved clippy coverage in CI? ===
See https://github.com/bonzini/rust-qemu/commit/95b25f7c5f4e2694a85a5503050cc98da7562c7c
* run clippy as part of "make check"
* run clippy as part of "make check", possibly only if Rust is newer than some version (1.74.0 so that clippy can be configured in Cargo.toml?)
* deny many individual lints, do not deny groups (complexity, perf, style, suspicious) on regular builds. allow unknown_lints.
* add to CI a fallible job that runs on nightly clippy with <tt>-Dclippy::complexity -Dclippy::perf -Dclippy::suspicious -Dclippy::style -Dunknown_lints</tt>. 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).
* add to CI a fallible job that runs on nightly clippy with <tt>-Dclippy::complexity -Dclippy::perf -Dclippy::suspicious -Dclippy::style -Dunknown_lints</tt>. 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).


== Possible project targets ==
=== Miscellanea  ===
 
* <code>qemu-bridge-helper.c</code> Re-write SUID C executable with useful features.


=== Miscellanea  ===
=== Bindings ===


- <code>qemu-bridge-helper.c</code> Re-write SUID C executable with useful features.
* visitors/QOM properties, could be interesting for <code>hw/sensor/tmp105.c</code>...
* complete vmstate bindings (needs const_refs_static in Rust 1.83.0, Zhao+Paolo have a prototype)


=== Devices  ===
=== Devices  ===
Line 113: Line 69:
** needs block bindings
** needs block bindings
* <code>hw/timer/i8254.c</code> (claimed, WIP)
* <code>hw/timer/i8254.c</code> (claimed, WIP)
** needs timer bindgings
* <code>hw/mem/nvdimm.c</code> (suggested by [[User:Manos|Manos]])
* <code>hw/mem/nvdimm.c</code> (suggested by [[User:Manos|Manos]])


[[Category:RustInQemu]]
[[Category:RustInQemu]]

Revision as of 12:50, 2 May 2025

For the old RustInQemu page, see RustInQemu/2022

Active effort

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

Paolo

  • Waiting for Meson 1.8.1: "objects:", rustdoc,
  • Later: pinned_init... maybe use MaybeUninit as a first step?

Manos

Zhao

Kevin

Bugs

Possible project targets

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?
  • split qemu_api into multiple crates
  • distros need dynamically linked libstd
    • rewrite all main()s in Rust and use -C prefer-dynamic?
    • or should Meson be able to link C programs with rlibs?

New code to write

  • more QOM procedural macros
    • generate qdev properties
    • generate parts of TypeInfo?
    • monomorphization of T: IsA<Class> to &T (like the momo crate)
  • feature parity for pl011
  • safe object creation with pinned_init, originating from Linux)
  • Generic Rust<->C interop, Error (https://github.com/bonzini/rust-qemu)
  • DMA (investigate vm-memory?)
  • Trace/log (Summer of Code)

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.

Bindings

  • visitors/QOM properties, could be interesting for hw/sensor/tmp105.c...
  • complete vmstate bindings (needs const_refs_static in Rust 1.83.0, Zhao+Paolo have a prototype)

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)
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