Hi Segher, >> You mean -mcpu= . Eljay said previously... > I thought -mcpu was a deprecated synonym for -mtune. > > Whereas -march implies -mtune, but is not a synonym for -mtune. > > My understanding may be out of date. http://gcc.gnu.org/onlinedocs/gcc-4.4.0/gcc/Option-Summary.html It appears that -m options can vary greatly by hardware model and configurations. Some may use -mcpu, some -march, some -mtune, and others may use entirely different -m switches. I stand corrected. Thanks, --Eljay PS to Tim: :-)