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README.md

Gumstix Repo Manifests for the Yocto Project Build System

This repository provides Repo manifests to setup the Yocto build system for supported Gumstix products.


Note: If you already have a Yocto Project setup and want only the Gumstix BSP layer, use the meta-gumstix repository found here: git://github.com/gumstix/meta-gumstix.git.


The Yocto Project allows the creation of custom linux distributions for embedded systems, including Gumstix-based systems. It is a collection of git repositories known as layers each of which provides recipes to build software packages as well as configuration information.

Repo is a tool that enables the management of many git repositories given a single manifest file. Tell repo to fetch a manifest from this repository and it will fetch the git repositories specified in the manifest and, by doing so, setup a Yocto Project build environment for you!

Getting Started

1. Install Repo.

Download the Repo script:

$ curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > repo

Make it executable:

$ chmod a+x repo

Move it on to your system path:

$ sudo mv repo /usr/local/bin/

If it is correctly installed, you should see a Usage message when invoked with the help flag.

$ repo --help

2. Initialize a Repo client.

Create an empty directory to hold your working files:

$ mkdir yocto
$ cd yocto

Tell Repo where to find the manifest:

$ repo init -u git://github.com/gumstix/Gumstix-YoctoProject-Repo.git 

A successful initialization will end with a message stating that Repo is initialized in your working directory. Your directory should now contain a .repo directory where repo control files such as the manifest are stored but you should not need to touch this directory.


Note: You can use the -b switch to specify the branch of the repository to use. We develop on the guaranteed-to-break dev branch. Most people should use the master branch, which should at least compile.

The -m switch selects the manifest file (default is default.xml). Our default.xml on master is designed to be stable as it pins particular commits.

To test out the bleeding edge, type:

$ repo init -u git://github.com/gumstix/Gumstix-YoctoProject-Repo.git -b dev
$ repo sync

To get back to the known stable version, type:

$ repo init -u git://github.com/gumstix/Gumstix-YoctoProject-Repo.git -b master
$ repo sync

Also you can get a specific version of Yocto Project:

For example,

$ repo init -u git://github.com/gumstix/Gumstix-YoctoProject-Repo.git -b refs/tags/danny

To learn more about repo, look at http://source.android.com/source/version-control.html


3. Fetch all the repositories:

$ repo sync

Now go turn on the coffee machine as this may take 20 minutes depending on your connection.

4. Initialize the Yocto Project Build Environment.

$ export TEMPLATECONF=meta-gumstix-extras/conf 
$ source ./poky/oe-init-build-env

This copies default configuration information into the poky/build/conf directory and sets up some environment variables for the build system. This configuration directory is not under revision control; you may wish to edit these configuration files for your specific setup. In particular, change the MACHINE variable in conf/local.conf if you are not building for the Overo (default).

5. Build an image:

This process downloads several gigabytes of source code and then proceeds to do an awful lot of compilation so make sure you have plenty of space (25GB minimum), and expect a day or so of build time depending on your network connection. Don't worry---it is just the first build that takes a while.

$ bitbake gumstix-console-image

If everything goes well, you should have a compressed root filesystem tarball as well as kernel and bootloader binaries available in your tmp/deploy/images/{ overo | duovero | pepper } directory. If you run into problems, the most likely candidate is missing software packages. Check out http://www.yoctoproject.org/docs/current/yocto-project-qs/yocto-project-qs.html#resources for the list of required packages for operating system. Also, take a look to be sure your operating system is supported: https://wiki.yoctoproject.org/wiki/Distribution_Support

6. Create a bootable micro SD card:

You are one step closer to booting your Gumstix with the new image you built! First you have to create two partitions: boot and rootfs. We have included a small script to help you out with it. Change your directory to poky/meta-gumstix-extras/scripts and you should see a shell script named mk2partsd. Pop in your micro SD card to your card writer, and find out the location of the block device by running dmesg. Now you can run the script as following:

$ sudo ./mk2partsd <block device> 

If you get an error, make sure your operating system has not automatically mounted the drives.

Once this is successful, go ahead and mount both the drives.

7. Flash your image:

Almost there. Now you just have to populate the card with the image you built. Go to the deploy directory as mentioned in step 5:

$ cd build/tmp/deploy/images/{overo|duovero|pepper}   

Write the bootloader, kernel and the root file system into your card:

$ cp MLO u-boot.img uImage /media/boot 
$ sudo tar xaf gumstix-console-image.tar.bz2 -C /media/rootfs --strip-components=1

And you should make sure all the files are written:

$ sync

Hooray you are done!

Staying Up to Date

To pick up the latest changes for all source repositories, run:

$ repo sync

Enter the Yocto Project build environment:

$ source poky/oe-init-build-env

If you forget to setup these environment variables prior to bitbaking, your 
OS will complain that it can't find bitbake on the path.  Don't try to
install bitbake using a package manager, just run the above command.

You can then rebuild as before:

$ bitbake gumstix-console-image

Starting Fresh

So something broke... what do you do now?

There are several degrees of starting fresh: individual packages can be rebuilt or the whole system can be reconstructed.

  1. clean a package: bitbake -c cleansstate
  2. re-download package: bitbake -c cleanall
  3. destroy everything but downloads: rm -rf build/sstate-cache build/tmp (or wherever your sstate and work directories are)
  4. destroy it all (not recommended): rm -rf build

Note: If you've made a change to a recipe and want the package to be rebuilt, just increment the recipe version (the PR variable); cleaning is not necessary.

To understand better how bitbake processes recipes, look at the excellent documentation: http://www.yoctoproject.org/docs/current/poky-ref-manual/poky-ref-manual.html.


To make sense of the differences between these cleaning methods, it is useful to understand that Yocto caches both the downloaded source files for all the packages it tries to build (the DL_DIR configuration parameter) and the packages once built (the SSTATE_DIR configuration parameter). Typically, deleting the downloaded source is a bad idea---this just means re-fetching gigabytes of code which wastes network bandwidth. Cleaning the sstate cache for a particular package ensures that it actually gets rebuilt from source rather than simply restored from the cache.

Customize

Sooner or later, you'll want to customize some aspect of the image either adding more packages, picking up some upstream patches, or tweaking your kernel. To this, you'll want to customize the Repo manifest to point at different repositories and branches or pull in additional meta-layers.

Clone this repository (or fork it on github):

$ git clone git://github.com/gumstix/Gumstix-YoctoProject-Repo.git

Make your changes (and contribute them back if they are generally useful), and then re-initialize your repo client

$ repo init -u <file:///path/to/your/git/repository.git>
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