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This is a big PR, but most of it is interdependent to the rest.
- Shared Rust infrastructure: `libkernel`, `libmodule`, `libcore`,
`liballoc`, `libcompiler_builtins`.
+ The Rust modules are now much smaller since they do not contain
several copies of those libraries. Our example `.ko` on release
is just 12 KiB, down from 1.3 MiB. For reference:
`vmlinux` on release w/ Rust is 23 MiB (compressed: 2.1 MiB)
`vmlinux` on release w/o Rust is 22 MiB (compressed: 1.9 MiB)
i.e. the bulk is now shared.
+ Multiple builtin modules are now supported since their symbols
do not collide against each other (fixes #9).
+ Faster compilation (less crates to compile & less repetition).
+ We achieve this by compiling all the shared code to `.rlib`s
(and the `.so` for the proc macro). For loadable modules,
we need to rely on the upcoming v0 Rust mangling scheme,
plus we need to export the Rust symbols needed by the `.ko`s.
- Simpler, flat file structure: now a small driver may only need
a single file like `drivers/char/rust_example.rs`, like in C.
+ All the `rust/*` and `driver/char/rust_example/*` files moved
to fit in the new structure. Way less files around!
- Only `rust-lang/{rust,rust-bindgen,compiler-builtins}` as dependencies.
+ Also helps with the faster compilation.
- Offline builds, always; i.e. there is no "online compilation"
anymore (fixes #17).
- No more interleaved Cargo output (fixes #29).
- One less nightly dependency (Cargo's `build-std`); since now we manage
the cross-compilation ourselves (should fix #27).
- Since now a kernel can be "Rust-enabled", a new `CONFIG_RUST` option
is added to enable/disable it manually, regardless of whether one has
`rustc` available or not (`CONFIG_HAS_RUST`).
- Improved handling of `rustc` flags (`opt-level`, `debuginfo`, etc.),
following what the user selected for C (no Cargo profiles).
- Added Kconfig menu for tweaking `rustc` options, like overflow checks.
- This rewrite of the Kbuild support is cleaner, i.e. less hacks
in general handling paths (e.g. no more `shell readlink` for `O=`).
- Duplicated the example driver 3 times so that we can test in the CI
that 2 builtins and 2 loadables work, all at the same time.
- Updated the quick start guide.
- Updated CI `.config`s:
+ Add the new options and test with 2 builtins and 2 loadables.
At the same time, remove the matrix test for builtin/loadable.
+ Debug: more things enabled (debuginfo, kgdb, unit testing, etc.)
that mimic more what a developer would have. Running the CI
will be slightly slower, but should be OK.
+ Release: disabled `EXPERT` and changed a few things to make it
look more like a normal configuration.
+ Also update both configs to v5.9 while I was at it.
(I could have split a few of these ones off into another PR,
but anyway it is for the CI only and I had already done it).
- Less `extern crate`s needed since we pass it via `rustc`
(closer to idiomatic 2018 edition Rust code).
Things to note:
- There is one more nightly feature used (the new Rust mangling scheme),
but we know that one will be stable (and the default one, later on).
- The hack at `exports.c` to export symbols to loadable modules.
- The hack at `allocator.rs` to get the `__rust_*()` functions.
There are a few TODOs that we can improve later if we agree on this:
- Kbuild:
+ Actually use the `*.d` files.
+ Complete `make clean`.
+ Support single-object compilation.
+ Pass `objtool` to make the ORC unwinder work.
+ Echo the building of the rust/* libraries and the bindgen call.
- Figure out how to pick symbols to export automatically from
Rust code instead of managing the list by hand.
Perhaps we could use a no-op macro on the Rust code, which is then
parse by a script to pick up the symbols:
pub fn foo() {}
export_symbol!(foo);
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>- Loading branch information
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