What does CC?= in a Makefile mean?
From http://www.gnu.org/software/make/manual/make.html: There is another assignment operator for variables, `?=’. This is called a conditional variable assignment operator, because it only has an effect if the variable is not yet defined. This statement: FOO ?= bar is exactly equivalent to this (see The origin Function): ifeq ($(origin FOO), undefined) FOO = bar endif Probably CC … Read more