https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78181
ktkachov at gcc dot gnu.org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED CC| |ktkachov at gcc dot gnu.org Resolution|--- |INVALID --- Comment #1 from ktkachov at gcc dot gnu.org --- support for Cortex-A73 was added to GCC 7. Are you using a non-FSF GCC 6.2? Perhaps a Linaro toolchain? In any case, -mtune guides tuning decisions without enforcing any particular architecture features. -mcpu requires the toolchain to use the architecture features of its argument (Cortex-A73 in this case) so it outputs that information in the assembly. You require assembler support for that. You need to update your binutils as support for Cortex-A73 was added to them in June 2016. I think it was in the 2.26 release