ref-manual: add documentation for the barebox class

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>

1 files changed, 29 insertions, 0 deletions

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 702a6caf87..8b996f216b 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -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