Before you begin downloading OpenEmbedded, you need to setup your working environment. The first step is to decide where on your system you wish to work. This document will use the $OEBASE variable to denote the base directory of the OpenEmbedded environment. For example, $OEBASE could be /home/joe/work/oe. The base directory of your OpenEmbedded environment ($OEBASE) is the location where sources will be checked out (or unpacked). You must choose a location with no symlinks above it. To create the directory structure: $ mkdir -p $OEBASE/build/conf $ cd $OEBASE The $OEBASE/build directory will contain your local configurations and extensions to the OpenEmbedded system which allow you to build your applications and images. The $OEBASE will also contain both bitbake/ and openembedded/ directories. These will be discussed in and .

Before using OE, you must first obtain the build tool it needs: bitbake. It is recommended to run bitbake without installing it, as a sibling directory of openembedded/ and build/ directories. Indeed, as bitbake is written in python it does not need compilation for being used. You'll just have to set the PATH variable so that the BitBake tools are accessible (see ).

To checkout the latest version of the BitBake 1.8 branch, use the following command: $ cd $OEBASE $ svn co svn://svn.berlios.de/bitbake/branches/bitbake-1.8/ bitbake BitBake is checked out now and the $OEBASE directory will contain a bitbake/ subdirectory. If you need to access a Subversion server through a proxy, see the SVN FAQ

Bitbake is being revised fairly often. Periodically it's a good idea to check the repository of bitbake stable branches to see if a new stable branch is available or if the current branch has been revised. Compare your existing bitbake directory with the latest bitbake branch in the repository. Your existing bitbake branch and its 'last changed revision' number can be found as follows: $ cd $OEBASE/bitbake; svn info If there is a new stable branch, you will want to move or delete your existing bitbake directory and repeat the process listed above under "To obtain bitbake". If there is no new branch, it is easy to update bitbake: $ cd $OEBASE/bitbake; svn update

Note: Once upon a time OpenEmbedded used Monotone for version control. If you have an OE Monotone repository on your computer, you should replace it with the Git repository. The OpenEmbedded metadata has a high rate of development, so it's a good idea to stay up to date. You'll need Git to get the metadata and stay up to date. Git is available in most distributions and has binaries at Git homepage.

Once you have installed Git, checkout the OpenEmbedded repository: $ cd $OEBASE $ git clone git://git.openembedded.net/openembedded The $OEBASE/openembedded/ directory should now exist.

The org.openembedded.dev branch of OpenEmbedded is updated very frequently (as much as several times an hour). The distro branches are not updated as much but still fairly often. It seems good practice to update your OpenEmbedded tree at least daily. To do this, run: $ cd $OEBASE $ git pull

Working with multiple branches is very easy to do with Git. The OpenEmbedded repository holds many branches. To list all branches, use this command: $ git branch -a Branch names that begin with origin/ denote branches that exist on the remote server. The name with a * in front of it is the branch currently checked out. If you want to work with a remote branch, you must first create a local copy of it. The following command will create a local copy of a remote branch: $ git branch <local_name> <remote_name> To change branches, use this command: $ git checkout <branch_name> There are more complicated branch operations that can be done with git, but those are beyond the scope of this document.

At this point, your $OEBASE/ directory should contain at least the following subdirectories: build/ bitbake/ openembedded/

There are a few environment variables that you will need to set before you can build software for OpenEmbedded using BitBake. You will need to set these variables every time you open a terminal for development. You can automate this in ~/.profile, /etc/profile, or perhaps use a script to set the necessary variables for using BitBake. Since the path to your OpenEmbedded installation will be used in many places, setting it in your environment will allow you to use the $OEBASE variable in all pathes and make it easier to change in the future should the need arise. To set $OEBASE if you use a Bourne like shell If you use a CSH like shell (e.g. on a FreeBSD system), you will set environment variables like this: $ setenv VAR_NAME "VAR_VALUE" , do this: $ export OEBASE=/path/to/your/oe/installation If you followed the recommendation to use BitBake from svn, you will need to add the path to the BitBake executable to your PATH environment variable like this: $ export PATH=$OEBASE/bitbake/bin:$PATH In order for bitbake to find the configuration files for OpenEmbedded, you will need to set the BBPATH variable. $ export BBPATH=$OEBASE/build:$OEBASE/openembedded Finally, if you wish to allow BitBake to inherit the $OEBASE variable from the environment, you will need to set the BB_ENV_EXTRAWHITE variable: $ export BB_ENV_EXTRAWHITE="OEBASE" Note the absence of the "$" character which implies that you are setting BB_ENV_EXTRAWHITE to the variable name, not the variable value.

It is now time to create your local configuration. While you could copy the default local.conf.sample like this: $ cd $OEBASE $ cp openembedded/conf/local.conf.sample build/conf/local.conf $ vi build/conf/local.conf It is actually recommended to start smaller and keep local.conf.sample in the background. Add entries from there step-by-step as you understand and need them. Please, do not just edit build/conf/local.conf.sample but actually READ it (read it and then edit it). For building an org.openembedded.dev branch, in your local.conf file, you should have at least the following three entries: BBFILES, DISTRO and MACHINE. For example, consider the following mininal local.conf file for the Ångström distribution and the Openmoko gta01 machine: BBFILES = "${OEBASE}/openembedded/recipes/*/*.bb" DISTRO = "angstrom-2008.1" MACHINE = "om-gta01"

The primary interface to the build system is the bitbake command (see the BitBake users manual). BitBake will download and patch files from the internet, so it helps if you are on a well connected machine. Note that you should issue all BitBake commands from inside of the build/ directory, or you should override TMPDIR in your $OEBASE/build/conf/local.conf to point elsewhere (by default it goes to tmp/ relative to the directory you run bitbake commands in). BitBake might complain that there is a problem with the setting in /proc/sys/vm/mmap_min_addr, which needs to be set to zero. You can set it by doing the following as root: # echo 0 > /proc/sys/vm/mmap_min_addr Note that you can not use a text editor to do this since files in /proc are not real files. Also note that this above change will be lost when you reboot your system. To have the change made automatically when the system boots, some systems provide a /etc/sysctl.conf file. Add the following line to that file: vm.mmap_min_addr=0 If your system does not provide the /etc/sysctl.conf mechanism, you can try adding the above echo command line to your /etc/rc.local. Once BitBake and OpenEmbedded are set up and configured, you can build software and images like this: $ bitbake <recipe_name> A recipe name corresponds to a BitBake .bb file. A BitBake file is a logical unit of tasks to be executed. Normally this is a package to be built. Inter-recipe dependencies are obeyed. The recipes are located by BitBake via the BBFILES variable (set in your $OEBASE/build/conf/local/conf), which is a space separated list of .bb files, and does handle wildcards. To build a single package, bypassing the long parse step (and therefore its dependencies -- use with care): $ bitbake -b $OEBASE/openembedded/recipes/blah/blah.bb There are a few groups of special recipes located in subdirectories of the $OEBASE/openembedded/recipes/ directory. These groups are: tasks/ A collection of meta-packages that depend on real packages to make managing package sets easier. meta/ A collection of usefull meta tasks and recipes that don't fit in a general category. images/ A collection of image targets that depend on packages that will be installed into an image which can be put on the target system.

Although BitBake can build individual packages, it is often more useful to build a set of packages and combine them into an image. The following recipe names are commonly used to that effect.

helloworld-image Builds an image, that if used as a root filesystem, will start a static executable that prints hello world then loops infinitely. Can be used to test the Linux boot procedure into user space (init). bootstrap-image Build image contains task-base packages. console-image Build an image without the X11, gtk+, or qt windowing libraries. x11-image Builds an image with X11. beagleboard-demo-image Builds the Ångström distribution like Koen proposed. opie-image Build image based on the Open Palmtop Integrated Environment (OPIE). OPIE is a completely Open Source based graphical user environment and suite of applications for small form-factor devices, such as PDAs, running Linux. opie-kdepim-image Build image based on the OPIE and full featured KDE-based PIM (pi-sync, ko/pi, ka/pi, etc). pivotboot-image Build image that is necessary to flash a Sharp SL C3000, Zaurus. It pivots after booting from the NAND and finalizes the install to the HD during the first boot. twin-image A image with task-base plus a couple of editors, nano and vim (why two?), and a mail reader, mutt. uml-image A root image for user-mode-linux. Includes task-base, and parts of opie. gpe-image Build a GPE Palmtop Environment based kernel and rootfs. The GPE provides a user interface environment for palmtop/handheld computers running the GNU/Linux or any other UNIX-like operating system.

task-base Build a kernel and core packages for a basic installation. You won't be able to do much more than ssh to the machine if this is all that is installed. task-dvb Meta-package for DVB application (DVB = Digital Video Broadcasting). task-python-everything All of python. task-native-sdk Mata-package for native (on-device) SDK.

meta-opie Build all OPIE related packages and some more for OPIE based usage. meta-gpe Basic packages to go with gpe-image.

helloworld Builds a static executable that prints hello world then loops infinitely. world Build everything. This takes a long time, a lot of network bandwidth, and a lot of disc space. Can also break your toolchain. package-index Target to update the "feed" files to reflect the current set of .ipk's that exist in the deploy directory. Commonly used after building some packages individually to update the feed and allow them to be installed via a package manager or the ipkg command line tools. virtual/kernel Builds the appropriate kernel for your device.