Modules/Platform/kFreeBSD.cmake - third_party/github.com/Kitware/CMake - Git at Google

 # kFreeBSD is a Debian GNU distribution with a kernel from FreeBSD,
 # and should be marked as LINUX
 include(Platform/Linux)

 set(CMAKE_LIBRARY_ARCHITECTURE_REGEX "[a-z0-9_]+(-[a-z0-9_]+)?-kfreebsd-gnu[a-z0-9_]*")
	# kFreeBSD is a Debian GNU distribution with a kernel from FreeBSD,
	# and should be marked as LINUX
	include(Platform/Linux)

	set(CMAKE_LIBRARY_ARCHITECTURE_REGEX "[a-z0-9_]+(-[a-z0-9_]+)?-kfreebsd-gnu[a-z0-9_]*")