Kmax: Analyzing the Linux Build System

Large-scale C software like Linux needs software engineering tools. But such codebases are software product families, with complex build systems that tailor the software with myriad features. This variability management is a challenge for tools, because they need awareness of variability to process all software product lines within the family. With over 14,000 features, processing all of Linux’s product lines is infeasible by brute force, and current solutions em-ploy incomplete heuristics. But having the complete set of com-pilation units with precise variability information is key to static tools such a bug-finders, which could miss critical bugs, and refac-toring tools, since behavior-preservation requires a complete view of the software project. Kmax is a new tool for the Linux build system that extracts all compilation units with precise variability information. It processes build system files with a variability-aware make evaluator that stores variables in a conditional symbol table and hoists conditionals around complete statements, while tracking variability information as presence conditions. Kmax is evaluated empirically for correctness and completeness on the Linux kernel. Kmax is compared to previous work for correctness and running time, demonstrating that a complete solution’s added complexity incurs only minor latency compared to the incomplete heuristic so-lutions