Asterinas is a production-grade, memory-safe operating system kernel written in Rust that aims to be Linux-compatible. It implements a framekernel architecture combining monolithic performance with microkernel-inspired separation, providing system call interfaces, device drivers, filesystems, networking, and process management. The project includes the OSDK (OS Development Kit) for building, running, and testing Rust kernels, and supports multiple architectures (x86-64, RISC-V, LoongArch) with varying tier levels. While it has strong research roots (evidenced by recent academic papers), its primary focus is on creating a usable OS that can run real-world applications via NixOS distribution.
This repository implements 'moss', a monolithic, Unix-like operating system kernel written in Rust, targeting AArch64 (with stubs for x86_64). It boots on QEMU and aims to run unmodified Linux userspace binaries (e.g., bash, coreutils, strace) by providing a Linux-compatible syscall interface. The kernel features an asynchronous core: all non-trivial syscalls are async functions, and the scheduler (EEVDF) and synchronization primitives are designed for async operation. The architecture includes a Hardware Abstraction Layer (HAL) via the `Arch` trait, but the majority of the code is ARM64-specific, covering boot, exception handling, MMU, interrupt controllers (GICv2/v3), UART drivers, timers, RTC, virtio, and a virtio-GPU display driver. The kernel provides a full process model with clone, execve, signals, futex, epoll, inotify, ptrace, and POSIX credentials. Memory management includes demand paging, copy-on-write, mmap, brk, a slab allocator with per-CPU caches, and a buddy allocator for physical frames. The VFS supports multiple filesystems: tmpfs, ext4 (via the ext4plus crate), FAT32, procfs, devfs, sysfs, and a cgroupfs stub. Networking uses the smoltcp stack for TCP/UDP and provides Unix domain sockets. The codebase is experimental and contains many stubs and unimplemented syscalls, but it is actively developed with a working init process, shell, and basic tools. Key strengths include the clean separation of architecture-independent kernel building blocks in the `libkernel` crate, the async-friendly synchronization primitives (`WakerSet`, `CondVar`, `Mutex`), the generic page table framework, and the driver registration macro. The code is well-structured for a kernel of this complexity, with extensive use of Rust's type system for safety (e.g., typed addresses, user-copy abstractions). However, the project is not production-hardened, relies on nightly Rust, and has significant architecture-specific code that limits portability.