diff --git a/documentation/getting-started/getting-started-yp-intro.xml b/documentation/getting-started/getting-started-yp-intro.xml index caabb13c10..f39cd70c74 100644 --- a/documentation/getting-started/getting-started-yp-intro.xml +++ b/documentation/getting-started/getting-started-yp-intro.xml @@ -1147,8 +1147,184 @@
Some Basic Terms -
+ + It helps to understand some basic fundamental terms when + learning the Yocto Project. + Although a list of terms exists in the + "Yocto Project Terms" + section of the Yocto Project Reference Manual, this section + provides the definitions of some terms helpful for getting started: + + + Configuration Files: + Files that hold global definitions of variables, + user-defined variables, and hardware configuration + information. + These files tell the OpenEmbedded build system what to + build and what to put into the image to support a + particular platform. + + + Extensible Software Development Kit (eSDK): + A custom SDK for application developers. + This eSDK allows developers to incorporate their library + and programming changes back into the image to make + their code available to other application developers. + For information on the eSDK, see the + Yocto Project Application Development and Extensible Software Development Kit (eSDK) + manual. + + + Layer: + A collection of related recipes. + Layers allow you to consolidate related metadata to + customize your build. + Layers also isolate information used when building + for multiple architectures. + Layers are hierarchical in their ability to override + previous specifications. + You can include any number of available layers from the + Yocto Project and customize the build by adding your + layers after them. + You can search the Layer Index for layers used within + Yocto Project. + For more detailed information on layers, see the + "Understanding and Creating Layers" + section in the Yocto Project Development Tasks Manual. + For a discussion specifically on BSP Layers, see the + "BSP Layers" + section in the Yocto Project Board Support Packages (BSP) + Developer's Guide. + + + Metadata: + A key element of the Yocto Project is the Metadata that + is used to construct a Linux distribution and is contained + in the files that the + OpenEmbedded build system parses + when building an image. + In general, Metadata includes recipes, configuration + files, and other information that refers to the build + instructions themselves, as well as the data used to + control what things get built and the effects of the + build. + Metadata also includes commands and data used to + indicate what versions of software are used, from + where they are obtained, and changes or additions to the + software itself (patches or auxiliary files) that + are used to fix bugs or customize the software for use + in a particular situation. + OpenEmbedded Core is an important set of validated + metadata. + + + OpenEmbedded Build System: + The terms "BitBake" and "build system" are sometimes + used for the OpenEmbedded Build System. + + BitBake is a task scheduler and execution engine + that parses instructions (i.e. recipes) and configuration + data. + After a parsing phase, BitBake creates a dependency tree + to order the compilation, schedules the compilation of + the included code, and finally executes the building + of the specified custom Linux image (distribution). + BitBake is similar to the make + tool. + + During a build process, the build system tracks + dependencies and performs a native or cross-compilation + of the package. + As a first step in a cross-build setup, the framework + attempts to create a cross-compiler toolchain + (i.e. Extensible SDK) suited for the target platform. + + + OpenEmbedded-Core (OE-Core): + OE-Core is metadata comprised of foundation recipes, + classes, and associated files that are meant to be + common among many different OpenEmbedded-derived systems, + including the Yocto Project. + OE-Core is a curated subset of an original repository + developed by the OpenEmbedded community that has been + pared down into a smaller, core set of continuously + validated recipes. + The result is a tightly controlled and an quality-assured + core set of recipes. + + You can see the Metadata in the + meta directory of the Yocto Project + Source Repositories. + + + Packages: + In the context of the Yocto Project, this term refers to a + recipe's packaged output produced by BitBake (i.e. a + "baked recipe"). + A package is generally the compiled binaries produced from the + recipe's sources. + You "bake" something by running it through BitBake. + + It is worth noting that the term "package" can, + in general, have subtle meanings. + For example, the packages referred to in the + "The Build Host Packages" + section in the Yocto Project Quick Start are compiled binaries + that, when installed, add functionality to your Linux + distribution. + + Another point worth noting is that historically within + the Yocto Project, recipes were referred to as packages - thus, + the existence of several BitBake variables that are seemingly + mis-named, + (e.g. PR, + PV, + and + PE). + + + Poky: + Poky, which is pronounced Pock-ee, + is a reference embedded distribution and a reference + test configuration. + Poky provides the following: + + + A base-level functional distro used to illustrate + how to customize a distribution. + + + A means by which to test the Yocto Project + components (i.e. Poky is used to validate + the Yocto Project). + + + A vehicle through which you can download + the Yocto Project. + + + Poky is not a product level distro. + Rather, it is a good starting point for customization. + + Poky is an integration layer on top of OE-Core. + + + + Recipe: + The most common form of metadata. + A recipe contains a list of settings and tasks + (i.e. instructions) for building packages that are then + used to build the binary image. + A recipe describes where you get source code and which + patches to apply. + Recipes describe dependencies for libraries or for other + recipes as well as configuration and compilation options. + Related recipes are consolidated into a layer. + + + +