Apple open sourced the kernel of iOS and macOS for ARM processors
Apple has always shared the kernel of macOS after each major release. This kernel also runs on iOS devices as both macOS and iOS are built on the same foundation. This year, Apple also shared the most recent version of the kernel on GitHub.
Context & Ripple Effects
This is another step in a deliberate Apple pattern rather than a one-off: after announcing plans to open-source Swift in 2015 and publishing a Swift benchmarking suite the following year, Apple is now putting the XNU kernel itself — the code both macOS and iOS are built on — on GitHub for ARM processors. Later entries in the same arc include open-sourcing the FoundationDB core and parts of the HomeKit Accessory Development Kit.
The significance is architectural as much as philosophical: because macOS and iOS share this kernel foundation, publishing it publicly documents the common base that Apple would later lean on when it said Macs running its own chips could natively run iOS apps.
First-order effects
- Developers and security researchers get direct access to the ARM kernel code on GitHub, letting them audit and study the foundation both macOS and iOS devices run on.
Second-order effects
- Public visibility into the shared kernel strengthens the case for Apple's single-architecture strategy — the same shared-foundation argument that underpinned bringing iOS apps to Apple-silicon Macs.
Third-order effects
- If the cadence holds — Swift, then the kernel, then FoundationDB and HomeKit tooling — Apple's model becomes selective openness of foundations while keeping the product layer closed, using transparency at the base to grow its developer ecosystem.
The trend: Apple is incrementally open-sourcing its foundational layers — languages, kernels, databases, dev kits — while keeping its consumer products closed, making the base layer an ecosystem recruiting tool.