cmov was first introduced on the Pentium Pro, i686. gcc should be able to produce code for i386, but all the distro's have since moved to a default target of P4

cmov was first introduced on the Pentium Pro, i686. gcc should be able to produce code for i386, but all the distro's have since moved to a default target of P4 iirc. As you say, -mtune is not the correct compiler flag for this purpose.