Hi, Does anyone know how to detect the machine (Pentium or Athlon) in the cook library and use the right flags for the machine? Attached is the one only works for a specific machine type. if [not [defined cc_optimize]] then { if [matches [operating_system machine] i686] then cc_optimize = [catenate "-O -mtune=athlon-xp "]; else cc_optimize = -O; } Thanks GZ