Question : What's the purpose of "MAKEFILE" macro in a makefile?

Consider following makefile:

MAKEFILE  =   makefile_platform
..
..

lib:            $(OBJS) $(MAKEFILE)
            @echo Making Archive Library:  $(LIB_DEST)$(LIB_NAME)...
            $(AR) $(ARFLAGS) $(LIB_DEST)$(LIB_NAME) [email protected]

Does this mean lib target will only get built if filename makefile_platform exists?  Instead, what if filename makefile exists, will the target lib get built?  Instead, what if filename is makefile_mine, will the target lib get built?

Answer : What's the purpose of "MAKEFILE" macro in a makefile?

Yes, if it doesn't exist it should say "Don't know how to make makefile_platform" and not build lib.  Unless you have a rule somewhere else in the makefile starting "makefile_platform:" that will build that file.