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. 14 15Due to evolving requirements and enhancements, there might be changes affecting 16platform compatibility, which means the previous interface needs to be deprecated 17and a new interface introduced to replace it. In case the migration to the new 18interface is trivial, the contributor of the change is expected to make good 19effort to migrate the upstream platforms to the new interface. 20 21The project will generally not take into account downstream platforms. If those 22are affected by a deprecation / removal decision, we encourage their maintainers 23to upstream their platform code or copy the latest version of the code being 24deprecated into their downstream tree. 25 26The deprecated interfaces are listed inside :ref:`Release Processes` as well as 27the release after which each one will be removed. When an interface is 28deprecated, the page must be updated to indicate the release after which the 29interface will be removed. This must be at least 1 full release cycle in future. 30For non-trivial interface changes, an email should be sent out to the `TF-A 31public mailing list`_ to notify platforms that they should migrate away from the 32deprecated interfaces. Platforms are expected to migrate before the removal of 33the deprecated interface. 34 35Platform deprecation policy 36--------------------------- 37 38If a platform is no longer maintained, it is best to deprecate it to keep the 39projects' source tree clean and healthy. Deprecation can be a 1-stage or 2-stage 40process (up to the platform maintainers). 41 42 - *2-stage*: The platform's source code can be kept in the repository for a 43 cooling off period before deleting it (typically 2 release cycles). In this 44 case, we keep track ot the *Deprecated* version separately from the *Deleted* 45 version. 46 47 - *1-stage*: The platform's source code can be deleted straight away. In this 48 case, both versions are the same. 49 50The :ref:`Platform Ports` page provides a list of all deprecated/deleted 51platform ports (or soon to be) to this day. 52 53-------------- 54 55*Copyright (c) 2018-2023, Arm Limited and Contributors. All rights reserved.* 56 57.. _TF-A public mailing list: https://lists.trustedfirmware.org/mailman3/lists/tf-a.lists.trustedfirmware.org/ 58