Andrew Reilly <andrew-freebsd at areilly.bpc-users.org> writes: > Apart from the fact that you are correct, how long is the > instruction encoding of cmpxchg8? Three bytes (0F C7 m64), four for "lock cmpxchg8" (F0 0F C7 m64). If the top two bits of m64 are set, you may get "interesting" results :) DES -- Dag-Erling Smørgrav - des at des.no