BitBake provides a very easy-to-use way to write conditional metadata. It is done by a mechanism called overrides.

The OVERRIDES variable contains values separated by colons (:), and each value is an item we want to satisfy conditions. So, if we have a variable that is conditional on arm, and arm is in OVERRIDES, then the version of the variable that is specific to arm is used rather than the non-conditional version, as shown:

OVERRIDES = "architecture:os:machine"
TEST = "defaultvalue"
TEST_os = "osspecificvalue"
TEST_other = "othercondvalue"

In this example, TEST will be osspecificvalue due to the condition of os being in OVERRIDES.