Like any build tool (make, ant, jam), the OpenEmbedded build tool BitBake controls how to build things and the build dependencies. But unlike single project . bitbake tool. Contribute to openembedded/bitbake development by creating an account on GitHub. Contribute to openembedded/bitbake development by creating an account on GitHub. scottrifenbark and rpurdie bitbake-user-manual: Created unique tags for.
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This work is licensed under the Creative Commons Attribution License. To view a copy of this license, visit http: Welcome to the BitBake User Manual. This manual provides information on the BitBake tool.
The information attempts to be as independent as possible regarding systems that use BitBake, such as the Yocto Project and OpenEmbedded.
In some cases, scenarios or examples that within the context of a build system are used in the manual to help with bibake. For these cases, the manual clearly states the context. Fundamentally, BitBake is a generic task execution engine that allows shell and Python tasks to be run efficiently and in parallel while working within complex inter-task dependency constraints.
One of BitBake’s main users, OpenEmbedded, takes this core and builds embedded Linux software stacks using a task-oriented approach. BitBake executes tasks according to provided metadata that builds up the tasks. Metadata is stored in recipe. BitBake includes a fetcher library for obtaining source code from various places such as source control systems or manuall. The instructions for each unit to be built e.
BitBake was originally a part of the OpenEmbedded project. It was inspired by the Portage package management system used by the Gentoo Linux distribution.
On December 7,OpenEmbedded project team member, Chris Larson split the project into two distinct pieces:. Today, BitBake is the primary basis of the OpenEmbedded project, which is being used to build and maintain Linux distributions such as the Angstrom Distribution and which is used as the build tool for Linux projects such as the Yocto Project.
Prior to BitBake, no other build tool adequately met the needs of an aspiring embedded Linux distribution. All of the build systems used by traditional desktop Linux distributions lacked important functionality, and none of the ad-hoc Buildroot-based systems, prevalent in the embedded space, were scalable or maintainable.
Handle inter-package dependencies build time on target architecture, build time on native architecture, and runtime. Support running any number of tasks within a given package, including, but not limited to, fetching upstream sources, unpacking them, patching them, configuring them, and so forth.
Be Linux distribution agnostic for both build and target systems. Support multiple build and target operating systems e. Cygwin, the BSDs, and so forth. Be self contained, rather than tightly integrated into the build machine’s root filesystem. Handle conditional metadata on the target architecture, operating system, distribution, and machine.
Be easy to use the tools to supply local metadata and packages against which to operate. Be easy to use BitBake to collaborate between multiple projects for their builds. Provide an inheritance mechanism that share common metadata between many packages.
Over time it became apparent that some further requirements were necessary:. Handle variants of a base recipe e.
Split metadata into layers and allow layers to override each other. Allow representation of a given set of input variables to a task as a checksum.
BitBake – Wikipedia
Based on that checksum, allow acceleration of builds with prebuilt components. BitBake satisfies all the original requirements and many more with extensions being made to the basic functionality to reflect the additional requirements. Flexibility and power have always been the priorities.
BitBake is highly extensible and supports embedded Python code and execution of any arbitrary tasks. Bithake is a program written in the Python language. At the highest level, BitBake interprets metadata, decides what tasks are required to run, and executes those tasks. GNU Make achieves its control through “makefiles”.
BitBake extends the capabilities of a simple tool like GNU Make by allowing for much more complex tasks to be completed, such as assembling entire embedded Linux distributions.
The remainder of this section introduces several concepts that should be understood in order to better leverage the power of BitBake. BitBake Recipes, which are denoted by the file extension. These recipe files provide BitBake with the following:. Within the context of BitBake, or any project utilizing BitBake as its build system, files with the.
Bitbake Cheat Sheet
Configuration files, which are denoted by the. These files fall into several areas that define machine configuration options, distribution configuration options, compiler tuning options, general common configuration options, and user configuration options. The main configuration file is the sample bitbake. Class files, which are denoted by the. The BitBake source tree currently comes with one class metadata file called base.
You can find this file in the classes directory. This class contains definitions for standard basic tasks such as fetching, unpacking, configuring empty by defaultcompiling runs any Makefile presentinstalling empty by default and packaging empty by default. These tasks are often overridden or extended by other classes added during the project development process. Layers allow you to isolate different types of customizations from each other.
While you might find it tempting to keep everything in one layer when working on a single project, the more modular you organize your metadata, the easier it is to cope mabual future changes. To illustrate how you can use layers to keep things modular, consider customizations you might make to support a specific target machine. These types of customizations typically reside in a special layer, rather than a general layer, called a Board Specific Package BSP Layer.
Furthermore, the machine customizations should be isolated from recipes and metadata that support a new GUI environment, for example. This situation gives you a couple of layers: It is important to understand, however, that the BSP layer can still make machine-specific additions to maanual within the GUI environment layer without polluting the GUI layer itself with those nanual changes.
You can accomplish this through a recipe that is a BitBake append. Append files, which are files that have the. BitBake expects every append file to have a corresponding recipe file.
Furthermore, the hitbake file and corresponding recipe file must use manhal same root filename. The filenames can differ only in the file type suffix used e.
Information in append files overrides the information in the similarly-named recipe file. For example, suppose you have an append file named as follows:. So, the append file would match the following recipe names:.
Using Git to clone the BitBake source msnual repository is the recommended method for obtaining BitBake. Cloning the repository makes it easy to get bug fixes and have access to stable branches and the master branch.
Once you have cloned BitBake, you should use the latest stable branch for development since the master branch is for BitBake development and might contain less stable changes.
You usually need a version of BitBake that mmanual the metadata you are using. The metadata is generally backwards compatible but not forward compatible. This command clones the BitBake Git repository into a directory called bitbake. Alternatively, you can designate a directory after the git clone command if you want to call the new directory something other than bitbaks.
Here is an example that names the directory bbdev:. Installation using your Distribution Package Management System: This method is not recommended because the BitBake version that is provided by your distribution, in most cases, is several releases behind a snapshot of the BitBake repository. Taking a snapshot of BitBake: Downloading a snapshot of BitBake from the source code repository gives you access to a known branch or release of BitBake. After extraction of the tarball using the tar utility, you have a directory entitled bitbake The bitbake command is the primary interface to the BitBake tool.
This section presents the BitBake command syntax and provides several execution examples. Executing tasks for a single recipe file is relatively simple. You specify bigbake file in question, and BitBake parses it and executes the specified mqnual. BitBake obeys inter-task dependencies when doing so. The following command runs the clean task on the foo. There are a number of additional complexities introduced when one wants to manage multiple.
Clearly there needs to be a way to tell BitBake what files are available, and of those, which you want to execute. There also needs to be a way for each recipe bitbakf express its dependencies, both for build-time and runtime. There must be a way for you to express recipe preferences when multiple recipes provide the same functionality, or when there are multiple versions of a recipe.
You cannot provide anything else. BitBake is able to generate bitvake graphs using the dot syntax.
Bitbake Cheat Sheet –
You can convert these graphs into images using the dot tool from Graphviz. When you generate a dependency graph, BitBake writes four files to the current working directory:. Shows BitBake’s knowledge of dependencies between runtime targets. Shows dependencies between build-time targets i.
Shows dependencies between tasks. Shows a simple list of targets that are to be built.