This info copied from: https://vuanhduy.wordpress.com/2014/05/02/the-variants-of-gnu-makefile-assignment-operation/ The differences in =, :=, ?= and += when assigning a macro in Makefile. = operation If the variable does not have a value, the operation assign the value to it If the variable already had a value, it is replaced. This value will be expanded when the variable is […]