Calculate Linux 15 has the Linux 3.18 kernel, KDE 4.14.12, Mesa 10.3.7, GCC 4.8.5, LLVM 3.5.0, and X.Org Server 1.16.4 by default on an EXT4 file-system. Calculate Linux 15 was tested on the same Intel Haswell Xeon + AMD FirePro system as used in the other Linux distributions, of course.