http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59801
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Those two cases are different, the other PR was about automatic volatile variables, where if they are unused it is really hard to come up with a way how they could be modified behind compiler's back. While for this case, variable in .data/.bss etc. section it is not so hard, the variable has a name through which it can be referenced, eventhough only from within the same assembly file. User could inject some assembly which will access it, the var can use section attribute that places it into some magic section that is e.g. IO mapped, etc.
