aosp-part-infrastructure

APEX activation relies on apexd to mount APEX packages, verify their manifests and signatures, and manage the Mainline module boundaries. This process ensures modular system components are safely integrated before the framework starts.

A/B and Virtual A/B OTA updates use update_engine payloads paired with verity and snapshotting to verify system integrity and manage rollback protection. This architecture ensures devices can safely revert failed updates.

Android virtualization uses AVF as the framework, pKVM for protected hypervisor execution, crosvm as the virtual machine monitor, and Microdroid as the guest OS for isolated workloads.

Mainline modules and platform compatibility are validated using CTS, VTS, and MTS frameworks orchestrated by TradeFederation. Developers can also run targeted tests locally using atest and Ravenwood.

Perfetto tracing captures detailed system metrics across Android infrastructure subsystems like APEX activation and OTA updates. Engineers analyze these traces to diagnose boot delays, virtualization overhead, and update_engine bottlenecks.

SDK Extensions are required for Project Mainline updates when new APIs need to be delivered independently of full platform releases. They define module boundaries and ensure backward compatibility across Android versions.