opendreambox 2.6

This is the build system of the opendreambox distribution, an embedded Linux distribution for Set-Top-Boxes manufactured by Dream Property GmbH.

It is based on the OpenEmbedded build framework, which uses BitBake to transform build instructions into distributable firmware images and software packages.

The current version is based on the Yocto Project release 2.3 „Pyro“, an umbrella project for OpenEmbedded and related tools.

We highly recommend taking a look at the Yocto Project Reference Manual.

Contributions

Maintainers of this release are:

• Andreas Monzner
• Andreas Oberritter
• Stephan Reichholf

Bug reports

Please use GitHub's issue tracker to create bug reports, or send a mail to [email protected] or one of the maintainers listed above.

Patches

We accept pull-requests on GitHub as well as patches submitted by mail to [email protected] or one of the maintainers listed above.

When sending patches by mail, please use something like git send-email -M -1 --to [email protected] to let git send it, or git format-patch -M -1 and send the resulting file as attachment, after all changes have been committed to your local copy of the repository.

Supported products

This release includes support for the following products:

Product name	Environment variable
Dreambox One	MACHINE=dreamone

License

Copyright (c) 2019 Dream Property GmbH, Germany
                   https://dreambox.de/

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

Obtaining the source code

To initially download the source into the current directory, issue the following command:

git clone -b pyro https://github.com/opendreambox/opendreambox.git

Quick start

For the impatient:

make -C opendreambox image

If this command fails, prerequisites may be missing. See section „Prerequisites“ below.

Directory structure

Currently, these layers are used:

• meta-dreambox
• meta-games
• meta-golang
• meta-opendreambox
• meta-openembedded/meta-filesystems
• meta-openembedded/meta-multimedia
• meta-openembedded/meta-networking
• meta-openembedded/meta-oe
• meta-openembedded/meta-python
• meta-openembedded/meta-webserver
• meta-qt5
• openembedded-core/meta

If a recipe for the same package exists in multiple layers, then the higher priority layer takes precedence over the lower priority layer.

For example, if libmad_0.15.1b.bb existed in both meta-openembedded and openembedded-core, the recipe in meta-openembedded would be used, because openembedded-core has lower priority. Priority values are determined by the variable BBFILE_PRIORITY in conf/layer.conf of each layer.

NOTE: This would still be true even if the version of libmad in openembeded-core was higher than the version in meta-openembedded, unless PREFERRED_VERSION_libmad was set to the version in openembedded-core. There is currently no way to prefer a version of a lower priority layer, if the same version is present in a higher priority layer.

openembedded-core and meta-openembedded

These directories contain copies of Git repositories from git.openembedded.org, including the OpenEmbedded-Core layer and the (Meta-)OpenEmbedded layers. They get created automatically when building the distribution for the first time.

Throughout this document, the combination of these directories will be referred to as OpenEmbedded.

The latest changes to these Git repositories can be seen at:

• https://git.openembedded.org/openembedded-core-contrib/log/?h=obi/pyro
• https://git.openembedded.org/meta-openembedded-contrib/log/?h=obi/pyro

meta-opendreambox

This directory contains:

• Recipes for packages written specifically for the opendreambox distribution
• Modifications to recipes from OpenEmbedded
• Recipes for different software versions than those available from OpenEmbedded

meta-dreambox

The directory meta-dreambox contains Board Support Packages (BSP) for the supported Dreambox models. This includes:

• Hardware drivers
• Machine specific overrides
• The Linux kernel
• The boot loader
• Splash images

Prerequisites

The OpenEmbedded project provides a general list of prerequisites for many Linux distributions and also for some other operating systems.

• https://www.openembedded.org/wiki/Getting_started#Required_software

It is highly recommended to use Linux to build opendreambox. In theory, any recent distribution will do, but not many distributions have been verified to build opendreambox without errors. Tested distributions include:

• Debian 9 „Stretch“ [amd64]

• Ubuntu 18.04 LTS „Bionic Beaver“ [amd64]

Major changes since previous public release (2.5)

• Added support for Dreambox One.
• Moved from Yocto „Krogoth“ to „Pyro“.
• OpenEmbedded switched to recipe-specific sysroots, which mandates passing an additional parameter to cross-compile.env, to specify the sysroot to be used.
• You may pass a machine name to bitbake.env, which allows tools like devtool to be used.

Known issues

• Machines other than Dreambox One are not supported yet.

Building opendreambox

In the top level directory, there is a Makefile, which is used to set up build directories and to fetch or update all used repositories. The Makefile can be influenced by environment variables, either by specifying them on the command-line or by storing them in a file called conf/make.conf. It is not recommended to edit the Makefile directly in order to avoid conflicts with future updates.

When the Makefile is run for the first time, the following steps will be executed:

• Creation of configuration files

  • bitbake.env
  • conf/opendreambox.conf
  • build/${MACHINE}/conf/bblayers.conf
  • build/${MACHINE}/conf/local.conf

• Update or checkout of Git repositories

  • opendreambox
  • BitBake
  • OpenEmbedded

Makefile targets

Run make help to get a list of targets of the top level Makefile, together with a brief description.

Configuration variables

BB_NUMBER_THREADS

Controls how many BitBake tasks may run at a time. Defaults to the number of cores available on the build system.

MACHINE

Controls the target machine to build packages for. See section Products for a list of supported products.

PARALLEL_MAKE

Controls how many processes per recipe make may use. Defaults to the number of cores available on the build system.

Adding custom layers

It is possible to add custom layers to the build system. This can be done globally and per machine. To add a layer globally, edit conf/bblayers-ext.conf. To add a machine-specific layer, edit conf/bblayers-${MACHINE}-ext.conf. Assuming that an additional layer is available at ${HOME}/custom-layer, the entry to add to the file will look like this:

BBLAYERS =+ "${HOME}/custom-layer"

Adding custom options

It is possible to tweak a lot more options than those used by the Makefile by editing conf/local-ext.conf or conf/local-${MACHINE}-ext.conf.

For example, if the firmware shall use the package feed built on the development machine, which happens to be 192.168.1.1 and has a web server configured to point to tmp-glibc/deploy/deb, a line like the following may be added:

DISTRO_FEED_URI = "http://192.168.1.1/${DISTRO}/${DISTRO_VERSION}"

In general, any variable in OpenEmbedded that uses weak assignment (?=) may be overridden from these files.

The following sections list some commonly used options.

DISTRO_FEED_PREFIX

DISTRO_FEED_PREFIX specifies the name of the package update feed. This name may be chosen arbitrarily.

Default: DISTRO_FEED_PREFIX = "remote"

DISTRO_FEED_URI

DISTRO_FEED_URI specifies the URI of the package update feed.

Default: DISTRO_FEED_URI = "http://my-distribution.example/remote-feed/"

INHERIT

INHERIT specifies bbclasses to include from a configuration file. Usually, this variable gets appended to by using the += operator.

The opendreambox distribution automatically appends "buildhistory recipe_sanity" to INHERIT.

Default: INHERIT = ""

Some examples:

Always build the latest versions of opendreambox-related projects from Git:

INHERIT += "opendreambox-autorev"

Setting up a build directory

To set up a build directory for e.g. DM920 run make MACHINE=dm920. If MACHINE=dm920 has been set in conf/make.conf (default: dreamone), you can simply run make with no arguments instead. This will create and initialize the directory build/dm920.

Building a firmware image

To build a firmware image for e.g. DM920 run make MACHINE=dm920 image. If MACHINE=dm920 has been set in conf/make.conf (default: dreamone), you can simply run make image instead.

Building a package

To build a single package, BitBake has to be used directly. First, the environment has to be set up, in order to make BitBake available to the shell. This can be done with the following command:

source bitbake.env dm920

You can omit the last parameter, in which case you need to change to the build directory of your target machine before starting a build (cd build/dm920).

In order to build enigma2, run:

bitbake enigma2.

Development hints

Cross-compilation of external software

Opendreambox provides a script called cross-compile.env. Once run, the script will create the following commands (shell aliases), aiming to ease cross-compilation of external source trees:

• oe_autoreconf - Calls OE’s version of autoreconf. Useful for projects based on GNU autotools.
• oe_runconf - Calls ./configure with parameters suitable for OE. Useful for projects based on GNU autotools.
• oe_runmake - Calls make with parameters suitable for OE. Useful for projects based on GNU autotools or GNU make.
• oe_env - Useful to execute arbitrary commands in the OE environment (e.g. oe_env env).
• oe_setenv - Exports the OE environment to the currently running shell session.

The script needs to know the target machine, which can be one of the supported products (see Products). Because the script adds aliases to your currently running shell session, it has to be invoked using source or . (the dot operator).

Starting with opendreambox 2.6, another parameter became mandatory, because of OpenEmbedded's switch to recipe-specific sysroots, e.g.:

source cross-compile.env dreamone busybox

This tells cross-compile.env to set up aliases using the sysroot of busybox. Note that you need to build busybox first, before being able to use this command.

The script may be called from any location, but must reside inside the opendreambox Git tree. You may want to create a symlink to cross-compile.env somewhere in your PATH.

Coding style

Run scripts/do_stylize.sh on new recipes to ensure proper coding style.

Package architecture

Set PACKAGE_ARCH = "${MACHINE_ARCH}" if either condition is met:

• The recipe uses COMBINED_FEATURES, MACHINE_FEATURES or DREAMBOX_FEATURES.
• The recipe uses COMPATIBLE_MACHINE.
• The recipe is part of meta-dreambox.