http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56165
--- Comment #14 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-03 14:57:19 UTC --- Not fake, but the default and smallest value, i.e. for x86_64 ABI we don't allow lowering the value to smaller than ABI required alignments. Only for 32-bit i?86 code it is allowed to lower it from 16 down to 4 bytes (the argument to -mpreferred-stack-boundary is N where (1 << N) is the alignment).
