Fast and Precise Retrieval of Forward and Back Porting Information for Linux Device Drivers

Porting Linux device drivers to target more recent and older Linux kernel versions to compensate for the everchanging kernel interface is a continual problem for Linux device driver developers. Acquiring information about interface changes is a necessary, but tedious and error prone, part of this task. In this paper, we propose two tools, Prequel and gcc-reduce, to help the developer collect the needed information. Prequel provides language support for querying git commit histories, while gcc-reduce translates error messages produced by compiling a driver with a target kernel into appropriate Prequel queries. We have used our approach in porting 33 device driver files over up to 3 years of Linux kernel history, amounting to hundreds of thousands of commits. In these experiments, for 3/4 of the porting issues, our approach highlighted commits that enabled solving the porting task. For many porting issues, our approach retrieves relevant commits in 30 seconds or less.