1Platform Ports Policy 2===================== 3 4This document clarifies a couple of policy points around platform ports 5management. 6 7Platform compatibility policy 8----------------------------- 9 10Platform compatibility is mainly affected by changes to Platform APIs (as 11documented in the :ref:`Porting Guide`), driver APIs (like the GICv3 drivers) or 12library interfaces (like xlat_table library). The project will try to maintain 13compatibility for upstream platforms. Due to evolving requirements and 14enhancements, there might be changes affecting platform compatibility which 15means the previous interface needs to be deprecated and a new interface 16introduced to replace it. In case the migration to the new interface is trivial, 17the contributor of the change is expected to make good effort to migrate the 18upstream platforms to the new interface. 19 20The deprecated interfaces are listed inside :ref:`Release Processes` as well as 21the release after which each one will be removed. When an interface is 22deprecated, the page must be updated to indicate the release after which the 23interface will be removed. This must be at least 1 full release cycle in future. 24For non-trivial interface changes, an email should be sent out to the `TF-A 25public mailing list`_ to notify platforms that they should migrate away from the 26deprecated interfaces. Platforms are expected to migrate before the removal of 27the deprecated interface. 28 29Platform deprecation policy 30--------------------------- 31 32If a platform is no longer maintained, it is best to deprecate it to keep the 33projects' source tree clean and healthy. Deprecation can be a 1-stage or 2-stage 34process (up to the platform maintainers). 35 36 - *2-stage*: The platform's source code can be kept in the repository for a 37 cooling off period before deleting it (typically 2 release cycles). In this 38 case, we keep track ot the *Deprecated* version separately from the *Deleted* 39 version. 40 41 - *1-stage*: The platform's source code can be deleted straight away. In this 42 case, both versions are the same. 43 44The :ref:`Platform Ports` page provides a list of all deprecated/deleted 45platform ports (or soon to be) to this day. 46 47-------------- 48 49*Copyright (c) 2018-2022, Arm Limited and Contributors. All rights reserved.* 50 51.. _TF-A public mailing list: https://lists.trustedfirmware.org/mailman3/lists/tf-a.lists.trustedfirmware.org/ 52