The commercial Timesys Corporation "Timesys Factory Build System" - “Embedded Linux BSPs / SDKs”. “Timesys Factory, a graphical, embedded Linux build system, offers optimized workflows and 'cleaned', preconfigured BSP components so developers can create custom BSPs easily and quickly. Developed by Timesys years before the Yocto Project initiative was even announced and continually enhanced since, Timesys’ Factory is an open source tool suite available either in desktop or cloud configurations”
”'Poky' is the name of the Yocto Project’s reference distribution or Reference OS Kit. It contains the build system ( BitBake and OpenEmbedded Core ) as well as a set of metadata to get you started building your own distro”.
“To use the Yocto Project tools, you can download Poky and use it to bootstrap your own distribution. Note that Poky does not contain binary files – it is a working example of how to build your own custom Linux distribution from source”.
Poky, the reference embedded OS is actually a working BUILD EXAMPLE which will build a small embedded OS with the included build system (BitBake, the build engine and OpenEmbedded-Core, the core build system metadata).
The build system is downloaded with Poky build instruction “files” called recipes and layers (defined below). You can alter, copy, extend, or use the Poky build specifics in any way you might need to in order to create your custom embedded Linux.
“Poky. Poky, which is pronounced Pock-ee, is a reference embedded distribution and a reference test configuration... Poky is not a product level distro. Rather, it is a good starting point for customization”.
“Poky began as an open-source project initially developed by OpenedHand. OpenedHand developed Poky from the existing OpenEmbedded build system to create a commercially supportable build system for embedded Linux. After Intel Corporation acquired OpenedHand, the poky project became the basis for the Yocto Project’s build system”.
EN.Wikipedia "BitBake", a Python script. Its operation does not depend on timestamps of files. Indeed, after modification of files, you should run the “bitbake clean” command.