November 28, 2025
Rust in peace, Linux?
Moss: a Rust Linux-compatible kernel in 26,000 lines of code
Tiny Rust kernel drops, fans cheer, skeptics fear MIT vibes
TLDR: Moss is a tiny Rust-made kernel that runs many Linux userland tools, aiming at compatibility, not full replacement yet. Commenters cheered the safety angle but debated the MIT license’s implications, asked if it could replace Android/Ubuntu now (no), and revived the classic “just a hobby?” meme.
Meet Moss, a tiny, Rust-made Linux-compatible kernel that’s already running most BusyBox commands — and running the community’s mouth. The creator, hexagonal-sun, dropped the 26,000‑line bomb, touting an async, safety-first core and ARM64 support, and commenters instantly split into hype vs. side‑eye.
On one side: pure curiosity. maxloh asks the practical question everyone’s thinking — can you swap it into Ubuntu or Android and keep everything booting? Short answer from the thread’s vibe: not yet; Moss is aiming for Linux app compatibility, not drop‑in replacement status today. On the other side: marty-oehme sounding the alarm about the MIT license and an “Linux ABI-compatible” kernel (plain talk: it runs Linux apps). The fear? Big companies could love a permissive license way more than the GPL that governs Linux.
Then came the wishlist crowd: meisel dreams of a memory‑safe OS for sensitive systems and wonders if Moss could actually beat Linux in speed. And the meme brigade rolled in with nikanj channeling the legendary line: “Just a hobby?” Cue popcorn. Folks joked about Android kernels, corporate playbooks, and whether Moss becomes a cozy dev toy or the next big “Rust saves the world” headline.
It’s tiny. It’s bold. It’s stirring drama. Online.
Key Points
- •Moss is a Rust and AArch64-assembly Unix-like kernel aiming for Linux userspace binary compatibility.
- •It features an async core where non-trivial syscalls are async, with compiler checks preventing spinlocks over await points.
- •Current capabilities include AArch64 support, MMU/page tables, CoW pages, 49 Linux syscalls, task scheduling/migration via IPIs, and VFS with ramdisk, FAT32 (RO), and devtmpfs.
- •Built on libkernel with strong address typing and extensive cross-architecture tests (230+), enabling host-based logic testing.
- •Build/run instructions include QEMU and cargo; roadmap targets TCP/IP networking, scheduler improvements, expanded syscalls, and a read/write filesystem (ext2/4).