第1行，将该layer的路径加入BBPATH变量，从bitbake -e rdk-general-broadband-image的输出可以看到

第2到第5行，将该layer中的所有recipe文件和recipe附加文件添加到BBFILES变量。从bitbake -e rdk-general-broadband-image的输出可以看到

第7行将该层的名字加入到BBFILE_COLLECTIONS变量中。BBFILE_COLLECTIONS变量的解释如下

Lists the names of configured layers. These names are used to find the other BBFILE_* variables. Typically, each layer will append its name to this variable in its conf/layer.conf file.

从bitbake -e rdk-general-broadband-image的输出可以看到

第8行，设置该层的BBFILE_PATTERN，其解释入下

Variable that expands to match files from BBFILES in a particular layer. This variable is used in the conf/layer.conf file and must be suffixed with the name of the specific layer (e.g. BBFILE_PATTERN_emenlow).

第14行，设置该层的LAYERDEPEND，其解释如下

Lists the layers, separated by spaces, on which this recipe depends.An error is produced if any dependency is missing or the version numbers (if specified) do not match exactly. This variable is used in the conf/layer.conf file and must be suffixed with the name of the specific layer

第16行，将conf/include/rdb-bbmasks-emulator.inc文件插入到该文件，其内容为

BBMASK用于阻止Bitbake处理一些recipe文件和recipe附加文件。

第18行设置daisy的GCC版本

第20和第21行追加功能bluetooth和bluez5到DISTRO_FEATURE变量。