Introduction
In this topic you will download Buildroot so you can create binary image files ready to flash onto a SD Memory card using adefault orcustom configuration for the target:ATSAMA5D27 SOM1 EK1 Evaluation Kit.
The process of getting the Buildroot source code involves copying (git clone) of a remote repository onto a local directory on your computer. This is theofficial repository of the Buildroot project.
You will also copy a Microchip Technology maintained external files that contain additional software packages.
Prerequisites
Git
If you are new togit there are many online resources. One such resource is the online bookPro Git by Scott Chacon and Ben Straub. It is available in several languages and you can also download the book in eBook formats (EPUB and MOBI) and PDF.
Another excellent resource is theLearn Git tutorial by Atlassian®.
Download - Getting Buildroot
1
Create a Project Directory
It is a good practice to create a project directory to place the source code for a given project. This way, you can archive the contents of the project directory for others and/or for archival purposes.
For the purposes of this how-to tutorial, we’ll name our project directoryproject_1:
$ mkdir project_1
2
Get Buildroot
You will get Buildroot by copying (git clone) the Buildroot source code from a remote repository
to your project directory:
Change directory to the project directory:
$ cd ~/project_1
Copy (git clone) the Buildroot source code to your project directory:
$ git clonegit://git.buildroot.net/buildroot
When yougit clone the Buildroot remote repositorygit.buildroot.net/buildroot you are creating a copy to your computer’s project directory (also known togit as the working directory or local directory).
Whengit is finished copying the Buildroot source code to your project directory, you will see a number of files and directories. The contents of each are explained in the Buildroot user manual:How Buildroot Works.
3
Checkout the LTS Branch (Version)
At this point, the copy of Buildroot in your project directory contains several branches (versions) of Buildroot. Since you just cloned the remote repository, the HEAD pointer is pointing to the “master” branch. You can see this by changing directory into thebuildroot directory and issuing agit status command:
$ cd ~/project_1/buildroot
$ git status
On branch master
Your branch is up-to-date with ‘origin/master’.
nothing to commit, working tree clean
The “master” branch is the latest (as of the time you cloned the repository) branch the Buildroot team is developing with. The development branch can be unstable. Instead, we want to use the latest-and-greatest stable version, known as theLong Term Support (LTS) version. To do this issue theget checkout command with the version number (also known as checking out the branch):
$ git checkout 2019.02.3
We determine which LTS version we will checkout by referring to theBuildroot download page. The Buildroot project publishes one long term support release per year and it is maintained for one year – security, bug, and build fixes.
Now issue agit status command:
$ git status
HEAD detached at 2019.02.3
nothing to commit, working tree clean
The HEAD pointer has been detached from the master and is now pointing at version 2019.02.3. It is important that you do not commit any changes to your local Buildroot directory in this state. If you do, they will be lost. If you want to make changes, create a new branch.
By the way, if you would like to see a list of the branches (versions) available you can issue thegit tag command.
$ git tag
0_0
2009.02
2009.02_rc1
2009.02_rc2
…
4
Get the Microchip Buildroot External Tree
The Microchip maintained external Buildroot tree contains additional packages and default configuration (defconfig) files for demonstrations running on SAMA5 and SAM9x60 series evaluation kits.
First, change directory into the project directory:
$ cd ~/project_1
Copy (git clone) the Microchip Buildroot external source code to your project directory:
5
Checkout the Latest Linux4SAM® demo
The latest version of Linux4SAM demonstration software is located on theLinux4SAM website. Checkout the latest Linux4SAM demonstration branch:
$ cd ~/project_1/buildroot-external-microchip
$ git checkout linux4sam_6.0
Recall that you can list the available branches (versions) by issuing thegit tag command.
Alternate Download Method
You may also download Buildroot in a compressedtar file (also known as a tarball) from the official Buildroot project websitedownload page. There are two compressed formats you can choose fromgzip, which have a*.tgz or*.tar.gz andbzip2 which have a*.tar.bz2 suffix.
If you are new to thetar utility, there are many resources online. Try searching: “linux tar tutorial”.
gzip - The command to decompress ( -z ) and extract ( -x ) a file ( -f ) is:
$ cd ~/project_1
$ tar -zxf buildroot-2019.02.3.tar.gz
bzip2 - The command to decompress ( -j ) and extract ( -x ) a file is ( -f ) is:
$ cd ~/project_1
$ tar -jxf buildroot-2019.02.3.tar.gz
You may want to add the verbose option ( -v ) to watch the progress of the decompress and extract command.
To download thebuildroot-external-microchip file, using your favorite web browser go to:Microchip SAMA5 Buildroot External
Click on the green buttonClone or download and selectDownload ZIP.
The command to decompress the file:
$ unzip buildroot-external-microchip
Summary
In this topic we explained the process of getting the official Buildroot source code using thegit clone command. Next, we explained how to “checkout” the long term support branch (version).
We also explained the process of getting the Microchip vendor maintained external files, buildroot-external-microchip. These contain additional packages and default configuration (defconfig) files for demonstration programs running on SAMA5 and SAM9x60 series evaluation kits.
What’s Next?
Before you can build the entire embedded system (cross-compilation toolchain, bootloaders, kernel, device tree, and target software packages) Buildroot must first be configured.
There are two methods in which you can perform the configuration:
- From adefault configuration (defconfig) file, or
- Manually, creating a custom project.
If you are new to Buildroot, you may want to try a default configuration first to familiarize yourself with the process and ensure everything works. With the knowledge you gain from configuring with a default configuration, you can customize your own Buildroot configuration for a custom project.
