..
 # SPDX-FileCopyrightText: Copyright (c) 2025, Linaro Limited.
 #
 # SPDX-FileCopyrightText: <text>Copyright 2022-2024 Arm Limited and/or its
 # affiliates <open-source-office@arm.com></text>
 #
 # SPDX-License-Identifier: MIT

############
Yocto Layers
############

The ``meta-cassini`` repository provides three layers compatible with the Yocto
Project, in the following sub-directories:

  * ``meta-cassini-bsp``

    A Yocto layer which holds board-specific recipes or append files that
    either:

      * will not be upstreamed (Cassini specific modifications)

      * have not been upstreamed yet

  * ``meta-cassini-distro``

    A Yocto distribution layer providing top-level and general policies for the
    Cassini distribution images.

  * ``meta-cassini-tests``

    A Yocto software layer with recipes that include run-time tests to validate
    Cassini functionalities.

.. _layer_dependency_overview_label:

*************************
Layer Dependency Overview
*************************

The following diagram illustrates the layers which are integrated by the
Cassini project, which are further expanded on below.
|layer dependency statement|

|

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

|

Cassini distribution depends on the following layer dependency sources:

  .. code-block:: yaml
    :substitutions:

    URL: https://git.yoctoproject.org/git/poky
    layers: meta, meta-poky
    branch: |poky branch|
    revision: |poky revision|

    URL: https://git.openembedded.org/meta-openembedded
    layers: meta-filesystems, meta-networking, meta-oe, meta-python
    branch: |meta-openembedded branch|
    revision: |meta-openembedded revision|

    URL: https://git.yoctoproject.org/git/meta-virtualization
    layer: meta-virtualization
    branch: |meta-virtualization branch|
    revision: |meta-virtualization revision|

    URL: https://git.yoctoproject.org/git/meta-security
    layers: meta-parsec
    branch: |meta-security branch|
    revision: |meta-security revision|

    URL: https://github.com/kraj/meta-clang
    layers: meta-clang
    branch: |meta-clang branch|
    revision: |meta-clang revision|

Additional layers are conditionally required, depending on the specific Cassini
distribution image being built and the platform being targeted. 

  .. code-block:: yaml
    :substitutions:

    URL: https://gitlab.arm.com/cassini/meta-cassini-bsp
    layers: meta-cassini-bsp
    branch: |meta-cassini-bsp branch|
    revision: |meta-cassini-bsp revision|

    URL: https://git.yoctoproject.org/git/meta-arm
    layers: meta-arm, meta-arm-bsp, meta-arm-toolchain
    branch: |meta-arm branch|
    revision: |meta-arm revision|

    URL: https://github.com/Wind-River/meta-secure-core
    layers: meta, meta-efi-secure-boot, meta-signing-key
    branch: |meta-secure-core branch|
    revision: |meta-secure-core revision|

    URL: https://gitlab.com/Linaro/trustedsubstrate/meta-ts.git
    layers: meta-trustedsubstrate
    branch: |meta-ts branch|
    revision: |meta-ts revision|

    URL: https://gitlab.com/Linaro/trustedsubstrate/meta-ledge-secure.git
    layers: meta-ledge-secure
    branch: |meta-ledge-secure branch|
    revision: |meta-ledge-secure revision|

    URL: https://github.com/Xilinx/meta-xilinx
    layers: meta-xilinx-core
    branch: |meta-xilinx branch|
    revision: |meta-xilinx revision|

    URL: https://github.com/aws/meta-aws
    layers: meta-aws
    branch: |meta-aws branch|
    revision: |meta-aws revision|

    URL: https://github.com/mendersoftware/meta-mender
    layers: meta-mender
    branch: |meta-mender branch|
    revision: |meta-mender revision|


  * Cassini firmware images built for the Corstone-1000
    platforms requires ``meta-cassini-bsp``, ``meta-arm``, ``meta-arm-bsp``,
    and ``meta-arm-toolchain``.

  * Cassini firmware images built for the Corstone-1000 also use
    ``efi-secure-boot`` and its dependencies to generate certificates for UEFI
    capsule images

  * Cassini firmware images built for KV260 also require
    ``meta-arm``, ``meta-arm-toolchain``, ``meta-trustedsubstrate``,
    ``meta-xilinx-core``, and ``meta-ledge-secure``.

  * Cassini distro images built with the greengrass-cloud feature also require
    ``meta-aws`` and ``meta-multimedia``.

  * Cassini distro images built with the mender-ota feature also require
    ``meta-mender``.