Repo is a repository management tool that is built on top of Git. Repo unifies the many Git repositories when necessary, and automates parts of the development workflow. Repo is not meant to replace Git, only to make it easier to work with Git in the context of development.The repo command is an executable Python script that you can put anywhere in your path. In working with the source files, you will use Repo for across-network operations. For example, with a single Repo command you can download files from multiple repositories into your local working directory. More details about repo tool is present at https://source.android.com/source/developing.html
Step 1: Preparing the Build Environment
Install Repo
#Download the Repo script:
$ curl https://storage.googleapis.com/git-repo-downloads/repo > repo
#Make it executable:
$ chmod a+x repo
#Move it on to your local home directory path:
$ mv repo ~/bin/
#Add it to your path
$ PATH=$PATH:~/bin
#If it is correctly installed, you should see a Usage message when invoked with the help flag.
$ repo --help
Fetch all sources
#repo init to the project of desire
$ repo init -u git://github.com/Xilinx/yocto-manifests.git -b <current-release>
#repo sync to get all sources
$ repo sync
#repo start a branch
$ repo start <current-release> --all
<current-release> : rel-v2018.1, rel-v2017.3 etc
Source environment
#source the environment to build using bitbake
$ source setupsdk