2. Platform Compatibility Policy

2.1. Introduction

This document clarifies the project’s policy around compatibility for upstream platforms.

2.2. Platform compatibility policy

Platform compatibility is mainly affected by changes to Platform APIs (as documented in the Porting Guide), driver APIs (like the GICv3 drivers) or library interfaces (like xlat_table library). The project will try to maintain compatibility for upstream platforms. Due to evolving requirements and enhancements, there might be changes affecting platform compatibility which means the previous interface needs to be deprecated and a new interface introduced to replace it. In case the migration to the new interface is trivial, the contributor of the change is expected to make good effort to migrate the upstream platforms to the new interface.

The deprecated interfaces are listed inside Release Processes as well as the release after which each one will be removed. When an interface is deprecated, the page must be updated to indicate the release after which the interface will be removed. This must be at least 1 full release cycle in future. For non-trivial interface changes, an email should be sent out to the TF-A public mailing list to notify platforms that they should migrate away from the deprecated interfaces. Platforms are expected to migrate before the removal of the deprecated interface.

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