New Rust code for Linux 6.4 includes the introduction of the pin-init API, which is for dealing with safe pinned initialization and allows reducing the amount of "unsafe" Rust code within the kernel around data structures needing a stable address. The new pin-init API in turn will also be used by other upcoming Rust for Linux abstractions.
Rust example code for the new pin-init API with Linux 6.4.
The Rust code with Linux 6.4 also adds new types and traits to the sync module, a new ioctl module with new "_IOC*" const functions equivalent to the C macros, a new uAPI crate to be accessible by drivers directly, and other improvements to existing modules/crates.
More details on the Rust feature code being added for Linux 6.4 can be found via this pull request .