Thank You for Your time and answer, Dirk: > Not all i586-CPUs have MMX, so I'm not sure if the kernel would use > MMX in i586-mode (despite for runtime-mmx-detection, but this option > you can have without march=i586). And you are always free to > a) compile a kernel with march=i586 > b) use mmx in your favorite userland application Could You be a bit more specific here w/ b) option? Thank You, once again.