What is the difference between BSP and distribution layers in Yocto

Question

Can you please explain briefly what are BSP and distribution layers and what is the difference between them?

Actually I'm not looking for Yocto project manual references but will be glad to get explanation as you understand it, in your words.

Answer 1

Well, despite what you ask for, the manual has the definition: Machine and policy configuration

The BSP layer is about providing a machine configuration (describing what HW your machine have) and to provide the necessary low level support, kernel and bootloader, external drivers, and possibly other applications for support and enablement.

The BSP layer must not modify anything in any recipe, unless the machine(s) supported by that layer is selected.

The distribution (policy) layer is responsible for configuration of distribution wide features and selections. Examples could be package format, C library, init system, etc. It should also decide whether to build enable X11, WiFi, Bluetooth, etc, support in all the other recipes. This is done by adding to the DISTRO_FEATURES variable, which different recipes later on should check in order to decide whether or not to build with different configurations.

As previously mentioned, check the manual for more detailed information.