Abstract : Collateral evolutions are a pervasive problem in Linux device driver development, due to the frequent evolution of Linux driver support libraries and APIs. Such evolutions are needed when an evolution in a driver support library affects the library's interface, entailing modifications in all dependent device-specific code. Currently, collateral evolutions in Linux are done nearly manually. The large number of Linux drivers, however, implies that this approach is time-consuming and unreliable, leading to subtle errors when modifications are not done consistently. In this paper, we describe the development of a language-based infrastructure, Coccinelle, with the goal of documenting and automating the kinds of collateral evolutions that occur in device driver code. Because Linux programmers are accustomed to manipulating program modifications in terms of patch files, we base our language on the patch syntax, extending patches to semantic patches.