[bitfolk] CPU optimisations for gentoo linux

Being a bit of a Bitfolk newbie and a gentoo rice racer, I was wondering if anyone could tell me what the best -march setting would be? I understand that its only really a concern if the VM was migrated to another host with differing CPU features. Does this ever happen or are VM's fairly tightly coupled with the host? Cheers, Ashley Nicholls -- --------- Open all hailing frequencies and broadcast in all known languages. Including Welsh. - Arnold J. Rimmer