| Message ID | 20241024-rust-round-2-v1-0-051e7a25b978@linaro.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Rust device model patches and misc cleanups | expand |
On 10/24/24 16:02, Manos Pitsidianakis wrote: > Hello everyone, the pathological corrosion of QEMU code continues. > This series expands the device model harness work performed in the > initial Rust work from the previous month. In particular: Wow, there's a lot of stuff here! The very good news is that it's basically all the code that is needed to get CI running, after which we can start with the fun stuff. At the same time, "the fun stuff" is also the one that risks introducing technical debt, so we need to switch to quality-over-quantity mode and have a serious design discussion about it. I'll do that later as a reply to the patches. > Code and functionality duplication is not fun, and pl011 was mostly > done as a proof of concept for a Rust device because of its small > complexity. As of this moment we have not decided on a policy for how > to handle these things and it is not in **scope for this patch series > anyway**. That's fine. Looking at the currently posted series, it seems that we have three main themes: 1) small scale cleanups: duplicated and useless code, improved testing. These are in https://lore.kernel.org/qemu-devel/20241021163538.136941-1-pbonzini@redhat.com/T/ and they have been reviewed already. But these two: > Revert "rust: add PL011 device model" > rust: add PL011 device model ... should definitely be moved on top to clean up the authorship in "git blame" and other similar tools. Sorry about that. 2) allow using older rustc/bindgen, extend CI to cover it. This is https://lore.kernel.org/qemu-devel/20241022100956.196657-1-pbonzini@redhat.com/T/ which still needs review. These five: > rust: add support for migration in device models > rust/pl011: move CLK_NAME static to function scope > rust/pl011: add TYPE_PL011_LUMINARY device > rust/pl011: remove commented out C code > rust/pl011: Use correct masks for IBRD and FBRD (minus the usage of #[derive()] should be included in that series, so that qtests pass. It's not a huge amount of work and I can extract it, of course with proper attribution/authorship. The rest are future work: > rust/qemu-api-macros: introduce Device proc macro This is useful as a starting point but it has the limit of being very device-specific. This is of course okay with properties and vmstate, but in my opinion the implementation of class_init should be as generic as possible, and not too specialized for methods in Object or Device. As I said above, we first need to agree on the design. > rust/pl011: move pub callback decl to local scope This depends a lot on how we go implementing bindings to chardev. For example if the callbacks turn out to be a trait, it would have to be undone. Possibly the C callback wrappers would move to rust/qemu-api/chardev. For now I'd leave it aside. > rust/qemu-api: add log module > rust/pl011: log guest/unimp errors This also needs design discussion. Do we want the API to be the same as C, i.e. keep the qemu_* prefix? Do we want wrapper macros that include the format!() call? You also have "pub enum LogMask" to work around the fact that log masks are preprocessor macros. Is that okay, or do we want to modify C code to make the bindings nicer? I for example would prefer the latter and then declaring LogMask as a bitfield in bindgen. Thanks, Paolo > > rust/wrapper.h | 1 + > rust/hw/char/pl011/src/device.rs | 419 +++++++++++++++++--------- > rust/hw/char/pl011/src/device_class.rs | 70 ----- > rust/hw/char/pl011/src/lib.rs | 2 +- > rust/qemu-api-macros/src/device.rs | 370 +++++++++++++++++++++++ > rust/qemu-api-macros/src/lib.rs | 46 +-- > rust/qemu-api-macros/src/object.rs | 107 +++++++ > rust/qemu-api-macros/src/symbols.rs | 57 ++++ > rust/qemu-api-macros/src/utilities.rs | 152 ++++++++++ > rust/qemu-api-macros/src/vmstate.rs | 113 +++++++ > rust/qemu-api/meson.build | 5 +- > rust/qemu-api/src/definitions.rs | 97 ------ > rust/qemu-api/src/device_class.rs | 128 -------- > rust/qemu-api/src/lib.rs | 10 +- > rust/qemu-api/src/log.rs | 140 +++++++++ > rust/qemu-api/src/objects.rs | 90 ++++++ > rust/qemu-api/src/tests.rs | 49 --- > rust/qemu-api/src/vmstate.rs | 403 +++++++++++++++++++++++++ > subprojects/packagefiles/syn-2-rs/meson.build | 1 + > 19 files changed, 1726 insertions(+), 534 deletions(-) > --- > base-commit: 55522f72149fbf95ee3b057f1419da0cad46d0dd > change-id: 20241024-rust-round-2-69fa10c9a0c9 > > -- > γαῖα πυρί μιχθήτω > > >
Hello everyone, the pathological corrosion of QEMU code continues. This series expands the device model harness work performed in the initial Rust work from the previous month. In particular: - A new derive proc macro, Device, is introduced and the Object derive macro is heavily expanded upon. Many hack-like macros and fixups to declare FFI code for QEMU to consume were removed and now everything is generated by macros in the qemu-api-macros procmacro crate. - Add support for device migration by allowing device models to declare their VMState description, fields, subsections like in C code. This should also allow new qemu versions to transparently migrate any VMs that used C device models that were afterwards ported to Rust. - Add a small logging interface in qemu-api crate to allow calling qemu_log() and qemu_log_mask() from Rust code. - Some minor code cleanups in the Rust pl011 device, and also port of one fix patch and one log prints addition patch that was added in the C pl011. In the future if we go forward with rewriting device models in Rust, and keep having both of them in-tree while Rust is not required for building QEMU, we could alter checkpatch.pl to produce a warning if a C device model has changes but the corresponding Rust implementation doesn't. Code and functionality duplication is not fun, and pl011 was mostly done as a proof of concept for a Rust device because of its small complexity. As of this moment we have not decided on a policy for how to handle these things and it is not in **scope for this patch series anyway**. In the meantime there are lots of TODOs written in my personal notes, my personal repos, in the QEMU wiki, in mailing list threads. I plan on consolidating them all in gitlab issues to streamline things and who-does-what to avoid duplicating work. Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org> --- Manos Pitsidianakis (11): Revert "rust: add PL011 device model" rust: add PL011 device model rust/qemu-api-macros: introduce Device proc macro rust: add support for migration in device models rust/pl011: move CLK_NAME static to function scope rust/pl011: add TYPE_PL011_LUMINARY device rust/pl011: move pub callback decl to local scope rust/pl011: remove commented out C code rust/pl011: Use correct masks for IBRD and FBRD rust/qemu-api: add log module rust/pl011: log guest/unimp errors rust/wrapper.h | 1 + rust/hw/char/pl011/src/device.rs | 419 +++++++++++++++++--------- rust/hw/char/pl011/src/device_class.rs | 70 ----- rust/hw/char/pl011/src/lib.rs | 2 +- rust/qemu-api-macros/src/device.rs | 370 +++++++++++++++++++++++ rust/qemu-api-macros/src/lib.rs | 46 +-- rust/qemu-api-macros/src/object.rs | 107 +++++++ rust/qemu-api-macros/src/symbols.rs | 57 ++++ rust/qemu-api-macros/src/utilities.rs | 152 ++++++++++ rust/qemu-api-macros/src/vmstate.rs | 113 +++++++ rust/qemu-api/meson.build | 5 +- rust/qemu-api/src/definitions.rs | 97 ------ rust/qemu-api/src/device_class.rs | 128 -------- rust/qemu-api/src/lib.rs | 10 +- rust/qemu-api/src/log.rs | 140 +++++++++ rust/qemu-api/src/objects.rs | 90 ++++++ rust/qemu-api/src/tests.rs | 49 --- rust/qemu-api/src/vmstate.rs | 403 +++++++++++++++++++++++++ subprojects/packagefiles/syn-2-rs/meson.build | 1 + 19 files changed, 1726 insertions(+), 534 deletions(-) --- base-commit: 55522f72149fbf95ee3b057f1419da0cad46d0dd change-id: 20241024-rust-round-2-69fa10c9a0c9 -- γαῖα πυρί μιχθήτω