Significance of local.conf and bblayers.conf file in Yocto

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When you run source poky/oe-init-build-env, it will create a "build" folder in that directory, and inside this build folder, it will create "conf" folder which contains two files:

1. local.conf
2. bblayers.conf

1. local.conf :
Configures almost every aspect of the build system:

  • Machine we are building for (MACHINE)
  • Tool chain host architecture to be used for a custom cross-toolchain (SDKMACHINE)
  • Optimize options for maximum build time reduction (BB_NUMBER_THREADS, PARALLEL_MAKE)
  • Where to place downloads (DL_DIR)
  • Package Management options , which type of packages to generate (PACKAGE_CLASSES)

2. bblayers.conf:

bblayers.conf file tells bitbake what layers you want to be considered during the build. By default, the layers listed in this file include layers minimally needed by the build system. However, you must manually add any custom layers you have created.

E.g: BBLAYERS = "\
                                  /home/jamal/poky/meta \
                                 /home/jamal/poky/meta-poky \
                                 /home/jamal/poky/meta-yocto-bsp \
                                 /home/jamal/poky/meta-mylayer \
                                 "
This example enables four layers, one of which is a custom user defined layer named "meta-mylayer"

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