..
 # SPDX-FileCopyrightText: <text>Copyright 2022-2023 Arm Limited and/or its
 # affiliates <open-source-office@arm.com></text>
 #
 # SPDX-License-Identifier: MIT

###################
Codeline Management
###################

The Cassini project is developed and released based on Yocto's release branch
process. This strategy allows us to make Major, Minor and Point/Patch Releases
based on upstream stable branches, reducing the risk of having build and runtime
issues.

******************************
Yocto Release Process Overview
******************************

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.. image:: images/cassini_rel_yocto_overview.png
   :align: center

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The diagram above gives an overview of the Yocto branch and release process:

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* Development happens primarily in the main (or master) branch.
* The project has a major release roughly every 6 months where a stable release
  branch is created.
* Each major release has a `codename` which is also used to name the stable
  release branch (e.g. nanbield).
* Once a stable branch is created and released, it only receives bug fixes with
  minor (point) releases on an unscheduled basis.
* The goal is for users and 3rd parties layers to use these codenamed branches
  as a means to be compatible with each other.

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For a complete description of the Yocto release process, support schedule and
other details, see the |Yocto Release Process|_ documentation.

**********************************
Cassini Branch and Release Process
**********************************

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.. image:: images/cassini_rel_dev_branches.png
   :align: center

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Cassini's branch and release process is based on the Yocto release process. The
following sub-sections describe in more details the branch strategy for Cassini's
development and release process.

Cassini main branch
===================

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* Represented by the green line on the diagram above.
* The repository's ``main`` branch is meant to be compatible with
  ``master`` or ``main`` branches from Poky and 3rd party layers.
* ``meta-cassini`` is not actively developed on this ``main`` branch to avoid the
  instability inherited from Yocto development on the master branch.
* To reduce the effort required to move Cassini to a new version of Yocto, this
  main branch is periodically updated with patches from the
  `Cassini development branches`_ .

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Cassini development branches
============================

* Represented by the red line on the diagram above.
* Cassini uses development branches based/compatible with Yocto stable branches.
* A development branch in Cassini is setup for each new Yocto release using the
  name convention ``<codename>-dev`` where `<codename>` comes from target Yocto
  release.
* The development branches in Cassini are where fixes, improvements and new
  features are developed.
* On a regular basis, code from the development branch is ported over to the
  ``main`` branch to reduce the effort required to move Cassini to a new version
  of Yocto.

Cassini release branches
========================

* Represented by the blue line on the diagram above.
* A new release branch in Cassini is setup for each new Yocto release using the
  Yocto `codename` the branch targets.
* Hot fixes in the release branch are back ported to the development branch.
* Release branches are currently maintained not much longer than a Yocto release
  period (~7 months).

Cassini release tags
====================

* Cassini is tagged using the version format ``v<Major>.<Minor>.<Patch>``.
* Tags are always applied to commits from the release branch.
* The first release in a release branch is a `Major` release.
* Following releases in a release branch advance the `Minor` version number.
* `Patch` releases are mainly used for hot fixes which are then back ported to
  the development branch.
* Both `Major` and `Minor` releases may receive fixes, improvements and new
  features while `Patch` releases only receive fixes. Poky and 3rd party layers
  release/stable branches might be updated and pinned.