Fetching the source code

One of the main features supported by BitBake is source code fetching. This support has been designed to be as modular and as flexible as possible. The mechanism used by BitBake to fetch the source code is internally called as fetcher backend. There are several fetcher backends supported, which can be configured to align the user requirements and optimize source code fetching.

When the Poky source code is downloaded, what is actually copied is the metadata and the BitBake tool. All other source code is fetched on demand. Every Linux-based system includes the Linux kernel and several other utilities that form the root filesystem, such as openssh. The OpenSSH source code is available from its upstream website as a tar.gz file hosted on a FTP server; the Linux kernel release may be fetched from a Git repository.

BitBake offers support for many different fetcher modules that allow retrieval of tarball files and a number of other protocols such as Git, Subversion, Bazaar...