..
 # Copyright (c) 2022, Arm Limited.
 #
 # SPDX-License-Identifier: MIT

######
Borrow
######

This document is a deeper explanation of how to reuse the components, patches
in this software stack.

****************************
Reusing the Firmware Patches
****************************

The firmware (``linux-system.axf``) consists of U-Boot and the base device tree,
bundled together with boot-wrapper-aarch64. Both U-Boot and boot-wrapper-aarch64
are patched to support the Armv8-R AArch64 architecture. These patches live in
``meta-arm-bsp`` [1]_.

For further details on the boot-wrapper-aarch64 patches see the
:ref:`Boot-wrapper-aarch64` section in :doc:`/manual/index`. The U-Boot
:ref:`Additional Patches` section provides more details on the U-Boot patches.

The base device tree [2]_ can be found in the meta-arm-bsp Yocto layer.

***********************
Reusing the Xen Patches
***********************

The patch series in Xen's `integration/mpu`_ branch initialize the PoC (Proof of
Concept) of Xen on the Armv8-R AArch64 architecture. The `integration/mpu`_
branch with these patches can be built and run as a standalone project outside
of this software stack, to support Xen on the Armv8-R AArch64 architecture. Here
is the `guidance`_ on how to run it outside of this stack.

.. _integration/mpu: https://gitlab.com/xen-project/fusa/xen-integration/-/tree/integration/mpu
.. _guidance: https://gitlab.com/xen-project/fusa/xen-integration/-/merge_requests/15

*********
Reference
*********

.. [1] https://git.yoctoproject.org/meta-arm/tree/meta-arm-bsp?h=kirkstone

.. [2] https://git.yoctoproject.org/meta-arm/tree/meta-arm-bsp/recipes-kernel/linux/files/fvp-baser-aemv8r64/fvp-baser-aemv8r64.dts?h=kirkstone