Azure Sphere: Fitting Linux Security in 4 MiB of RAM
summary
Azure Sphere fits a customized Linux kernel into a microcontroller with a 4 MiB RAM target by using execute-in-place to keep code in flash, trimming configs and hash tables, and adding a tiny custom LSM for app identity and granular GPIO/quota controls. The resulting kernel image is ~2.4 MB with ~2,100 KB RAM after init, ~227 private commits on top of mainline, per-app isolated filesystems, and OTA patching that rolled out a Wi‑Fi fix in 24 hours.
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chapters (12)
- 0:00Start
- 6:19High Level Os Kernel
- 7:39Kernel Customizations
- 16:18Add App Identity
- 19:31Access Control to Existing Features
- 22:44Out of Box System Apps
- 27:05Example Manifest
- 30:57Opportunities for the Future
- 32:00File System
- 32:31Namespaces
- 34:58Takeaways
- 40:13Running Linux on the Cortex
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