opendreambox

Andreas Oberritter <obi@opendreambox.org>

March 2012

Contents

1 Introduction
 1.1 Target audience
 1.2 Supported products
 1.3 License
 1.4 Obtaining the source code
 1.5 Quick start
 1.6 Directory structure
  1.6.1 openembedded-core and meta-openembedded
  1.6.2 meta-opendreambox
  1.6.3 meta-bsp
2 Prerequisites
 2.1 Required software
3 Major changes since previous releases
 3.1 Changes since release 1.6
4 Known Bugs
5 Building OpenDreambox
 5.1 Makefile targets
 5.2 Configuration variables
  5.2.1 BB_NUMBER_THREADS
  5.2.2 MACHINE
  5.2.3 PARALLEL_MAKE
 5.3 Adding custom layers
 5.4 Adding custom options
  5.4.1 DISTRO_FEED_PREFIX
  5.4.2 DISTRO_FEED_URI
  5.4.3 INHERIT
 5.5 Setting up a build directory
 5.6 Building a firmware image
 5.7 Building a package
6 Development hints
 6.1 Cross-compilation of external software
 6.2 Coding style
 6.3 Package architecture
7 Bug reports and patches

1 Introduction

This document briefly describes the OpenDreambox distribution, an embedded Linux distribution for Set-Top-Boxes manufactured by Dream Multimedia GmbH.

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

1.1 Target audience

Developers familiar with previous versions of OpenDreambox or OpenEmbedded in general.

1.2 Supported products

The current version includes support for the following machines:



Product name Environment variable


DM 500 HD MACHINE=dm500hd
DM 800 HD PVR MACHINE=dm800
DM 800 HD SE MACHINE=dm800se
DM 7020 HD MACHINE=dm7020hd
DM 8000 HD PVRMACHINE=dm8000


1.3 License

Copyright (c) 2010-2012 Dream Multimedia GmbH, Germany  
                        http://www.dream-multimedia-tv.de/  
Authors:  
  Andreas Frisch <fraxinas@opendreambox.org>  
  Andreas Monzner <ghost@opendreambox.org>  
  Andreas Oberritter <obi@opendreambox.org>  
  Mladen Horvat <acid-burn@opendreambox.org>  
  Stefan Pluecken <thedoc@opendreambox.org>  
  Stephan Reichholf <reichi@opendreambox.org>  
 
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.  
    

1.4 Obtaining the source code

OpenDreambox uses the Git version control system. To obtain the source code, it is required to install Git. See http://git-scm.com/.

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

git clone git://git.opendreambox.org/git/opendreambox.git

1.5 Quick start

For the impatient:

make -C opendreambox image

If this command fails, prerequisites my be missing. See section 2.

1.6 Directory structure

OpenDreambox consists of a set of layers containing build instructions. This meta data is used by BitBake to download and compile source code and to assemble installable software packages and firmware images.

Currently, there are five layers, ordered by priority from lowest to highest:

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, libmad_0.15.1b.bb exists in both meta-openembedded and openembedded-core. The recipe in meta-openembedded will be used, because openembedded-core has lower priority.

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.

1.6.1 openembedded-core and meta-openembedded

These directories contain copies of Git repositories from git.openembedded.org, including the OpenEmbedded-Core layer (”meta”) and the OpenEmbedded layer (”meta-oe”). 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.

1.6.2 meta-opendreambox

This directory contains:

1.6.3 meta-bsp

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

2 Prerequisites

2.1 Required software

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

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:

Distributions known not to work:

3 Major changes since previous releases

3.1 Changes since release 1.6

4 Known Bugs

None.

5 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 specifing 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:

5.1 Makefile targets

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

5.2 Configuration variables

5.2.1 BB_NUMBER_THREADS

Controls how many BitBake tasks may run at a time. Defaults to the number of cores available on the build system. The number of cores is obtained from /proc/cpuinfo. If this file is unavailable, the default value is 1.

5.2.2 MACHINE

Controls the target machine to build packages for. See section 1.2 for a list of supported products.

5.2.3 PARALLEL_MAKE

Controls how many processes per recipe make may use. Defaults to the number of cores available on the build system. The number of cores is obtained from /proc/cpuinfo. If this file is unavailable, the default value is 1.

NOTE: If you see seemingly random build failures, try setting this variable to 1.

5.3 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"

5.4 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 develoment machine, which happens to be 192.168.1.1 and has a webserver configured to point to tmp/deploy/ipk, 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.

5.4.1 DISTRO_FEED_PREFIX

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

Default: DISTRO_FEED_PREFIX = "remote"

5.4.2 DISTRO_FEED_URI

DISTRO_FEED_URI specifies the URI of the package update feed.

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

5.4.3 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 testlab" to INHERIT.

Default: INHERIT = ""

Some examples:

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

INHERIT += "opendreambox-autorev"

Remove temporary files of previous versions of a recipe before a newer version gets built:

INHERIT += "rm_old_work"

Remove temporary files of a recipe after it has been built and packaged successfully.

INHERIT += "rm_work"

5.5 Setting up a build directory

To set up a build directory for e.g. DM 500 HD run make MACHINE=dm500hd. If MACHINE=dm500hd has been set in conf/make.conf, you can simply run make with no arguments instead. This will create and initialize the directory build/dm500hd.

5.6 Building a firmware image

To build a firmware image for e.g. DM 500 HD run make MACHINE=dm500hd image. If MACHINE=dm500hd has been set in conf/make.conf, you can simply run make image instead.

5.7 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

BitBake must be run from the machine’s build directory. For DM 500 HD run:

cd build/dm500hd

In order to build enigma2, run:

bitbake enigma2.

6 Development hints

6.1 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:

The script needs to know the target machine, which can be one of the supported products (see 1.2). Because the script adds aliases to your currently running shell session, it has to be invoked using source or . (the dot operator), e.g.:

source cross-compile.env dm7020hd

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.

6.2 Coding style

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

6.3 Package architecture

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

7 Bug reports and patches

Please send bug reports and patches to the Enigma2 development mailing list <enigma2-devel@lists.elitedvb.net>.

A comfortable way to create patches is to use git format-patch, after all changes have been committed to your local copy of the repository.