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ref-manual: add documentation for the barebox class

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This adds the initial documentation for the newly added barebox.bbclass
to the Reference Manual's class list.
It also adds the two most notable variables to the variable list.

(From yocto-docs rev: cc8179122441cdc26ff62511dcd97f7bf9bf7e3d)

Signed-off-by: Enrico Jörns <ejo@pengutronix.de>
Reviewed-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Enrico Jörns
2025-01-19 23:10:05 +01:00
committed by Richard Purdie
parent 5a38f96a33
commit dfab86d2f4
2 changed files with 66 additions and 0 deletions
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37
documentation/ref-manual/classes.rst
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@@ -128,6 +128,43 @@ It's useful to have some idea of how the tasks defined by the
- :ref:`ref-tasks-install` --- runs ``make install`` and
passes in ``${``\ :term:`D`\ ``}`` as ``DESTDIR``.
.. _ref-classes-barebox:
``barebox``
===========
The :ref:`ref-classes-barebox` class manages building the barebox bootloader.
If a file named ``defconfig`` is included in the :term:`SRC_URI`, it will be
copied to ``.config`` in the build directory and used as the barebox
configuration.
Instead of providing a ``defconfig`` file, you can set :term:`BAREBOX_CONFIG`
to a defconfig provided by the barebox source tree.
If neither ``defconfig`` nor :term:`BAREBOX_CONFIG` is specified, the class
will raise an error.
The :ref:`ref-classes-barebox` class supports config fragments and internally
includes the :ref:`ref-classes-cml1` class to provide `Kconfig
<https://docs.kernel.org/kbuild/kconfig-language.html>`__ support for
barebox, enabling tasks such as :ref:`ref-tasks-menuconfig` and
:ref:`ref-tasks-diffconfig`.
The generated barebox binaries are deployed to
:term:`DEPLOY_DIR_IMAGE` as well as installed to ``BAREBOX_INSTALL_PATH``
(``/boot`` by default) making them part of the recipe’s base package.
This setup supports both using the barebox binaries as independent artifacts
and installing them into a rootfs.
:term:`BAREBOX_BINARY` can be used to select a distinct binary to deploy and
install.
If ``barebox`` is set as the :term:`EFI_PROVIDER`, the class will leverage
:oe_git:`conf/image-uefi.conf </openembedded-core/tree/meta/conf/image-uefi.conf>`
to define the default installation paths and naming conventions.
The compiled-in barebox environment can be extended by adding environment files
to the ``BAREBOX_ENV_DIR``.
The ``BAREBOX_FIRMWARE_DIR`` variable allows you to specify the firmware blob
search directory, enabling loading of additional firmware like TF-A or OP-TEE.
.. _ref-classes-base:
``base``

29
documentation/ref-manual/variables.rst
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@@ -293,6 +293,35 @@ system and gives an overview of their function and contents.
:term:`PACKAGE_EXCLUDE` variables for related
information.
:term:`BAREBOX_BINARY`
When using the :ref:`ref-classes-barebox` class, this variable allows you
to specify a particular binary that should be deployed and installed.
The barebox build system can build multiple barebox binaries at once.
By default, all built binaries will be deployed and installed under their
original name.
Here is an example usage of this variable::
BAREBOX_BINARY = "barebox-boundarydevices-imx6dl-nitrogen6x-1g.img"
:term:`BAREBOX_CONFIG`
When using the :ref:`ref-classes-barebox` class, this variable allows you
to specify the name of the barebox defconfig to build.
The name must be a defconfig file known to the barebox build environment.
This variable is mainly useful for generic use cases where a dedicated
configuration is not required.
The :ref:`ref-classes-barebox` class itself already sets it for some QEMU
machines::
BAREBOX_CONFIG:qemuarm = "multi_v7_defconfig"
BAREBOX_CONFIG:qemuarm64 = "multi_v8_defconfig"
BAREBOX_CONFIG:qemux86-64 = "efi_defconfig"
Except for these, the default value of :term:`BAREBOX_CONFIG` is empty.
For more information on how to provide a barebox configuration, see the
:ref:`ref-classes-barebox` class.
:term:`BASE_LIB`
The library directory name for the CPU or Application Binary
Interface (ABI) tune. The :term:`BASE_LIB` applies only in the Multilib