The Cray XT Series is supported by the TotalView x86_64 distribution. The discussion here is based on running applications on Cray XT Catamount, some of which is also applicable to using Cray Linux Environment (CLE). The primary difference between the two, and it is a big difference, is that CLE uses aprun to launch programs rather than yod (See "Cray Linux Environment (CLE)" for details).