The build directory is initially empty (except for this README file). It
gets populated with configuration files by kas-container checkout
after which it looks like this:
build
├── conf
│ ├── bblayers.conf
│ ├── local.conf
│ └── templateconf.cfg
└── README.md
The build process (i.e., running bitbake) adds additional files and directories. Here is a directory tree (some file omitted for brevity; you may not have all these files, depending on your configuration).
build
├── cache
├── conf
│ ├── bblayers.conf
│ ├── local.conf
│ └── templateconf.cfg
├── downloads
├── README.md
├── sstate-cache
└── tmp
For more information, see the Yocto Project's documentation of the build directory.