The Linux kernel feature model has been studied as an example of large scale evolving feature model and yet details of its evolution are not known. We present here a classification of feature changes occurring on the Linux kernel feature model, as well as a tool, FMDiff, designed to automatically extract those changes. With this tool, we obtained the history of more than twenty architecture specific feature models, over ten releases and compared the recovered information with Kconfig file changes. We establish that FMDiff provides a comprehensive view of feature changes and show that the collected data contains promising information regarding the Linux feature model evolution. Preprint accepted for publication in the Proceedings of the 8th International Workshop on Variability Modelling of Software intensive Systems, VaMoS 2014. Nice, France, January 22-24, 2014.