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diff --git a/docs/process/platform-ports-policy.rst b/docs/process/platform-ports-policy.rst new file mode 100644 index 0000000..02eb6bd --- /dev/null +++ b/docs/process/platform-ports-policy.rst @@ -0,0 +1,56 @@ +Platform Ports Policy +===================== + +This document clarifies a couple of policy points around platform ports +management. + +Platform compatibility policy +----------------------------- + +Platform compatibility is mainly affected by changes to Platform APIs (as +documented in the :ref:`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 project will generally not take into account downstream platforms. If those +are affected by a deprecation / removal decision, we encourage their maintainers +to upstream their platform code or copy the latest version of the code being +deprecated into their downstream tree. + +The deprecated interfaces are listed inside :ref:`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. + +Deprecation policy +------------------ + +If a platform, driver or library interface is no longer maintained, it is best +to deprecate it to keep the projects' source tree clean and healthy. Deprecation +can be a 1-stage or 2-stage process (up to the maintainers). + + - *2-stage*: The source code can be kept in the repository for a cooling off + period before deleting it (typically 2 release cycles). In this case, we keep + track of the *Deprecated* version separately from the *Deleted* version. + + - *1-stage*: The source code can be deleted straight away. In this case, both + versions are the same. + +The :ref:`Platform Ports` page provides a list of all deprecated/deleted +platform ports (or soon to be) to this day. + +-------------- + +*Copyright (c) 2018-2023, Arm Limited and Contributors. All rights reserved.* + +.. _TF-A public mailing list: https://lists.trustedfirmware.org/mailman3/lists/tf-a.lists.trustedfirmware.org/ |