ConfigFix: Interactive Configuration Conflict Resolution for the Linux Kernel

Abstract

Highly configurable systems are highly complex systems. The Linux kernel is arguably one of the most well-known examples. Given its vast configuration space, researchers have used it to conduct many empirical studies as well as to build dedicated methods and tools for analyzing, configuring, testing, optimizing, and maintaining the kernel. However, despite a large body of work, mainly bug fixes that were the result of such research made it back into the kernel's source tree. Unfortunately, Linux users still struggle with kernel configuration and resolving configuration conflicts, since the kernel largely lacks automated support. Additionally, there are technical and community requirements for supporting automated conflict resolution in the kernel, for example, using a pure C-based solution that uses only compatible third-party libraries (if any).With the aim of contributing back to the Linux community, we present Co n f ig Fi x , a tooling that we integrated with the Linux kernel configurator, that is purely implemented in C, and that is finally a working solution able to produce fixes for configuration conflicts. We describe our experiences of building upon the large body of research done on the kernel configuration mechanisms as well as how we designed and realized Co n f ig Fix while adhering to the Linux kernel's community requirements and standards. Co n f ig Fi x not only helps Linux kernel users obtain their desired configuration, but our implemented semantic abstraction provides the basis for many of the above techniques supporting kernel configuration.

Towards Feature-based ML-enabled Behaviour Location

“…Consequently, we need to use a solver to check that all constraints are satisfied. If any constraints are violated, we must develop strategies to rectify the configuration, such as through repair methods [3,6,8,14]. As illustrated in the right part of Figure 1, this repair process should consider the input trace to ensure that the output of the repair procedure remains capable of executing the trace.…”

Options Matter: Documenting and Fixing Non-Reproducible Builds in Highly-Configurable Systems

“…We use the tool ConfigFix [10] to extract the set of choices at the same level of a given option. ConfigFix is a tool able to produce fixes for configuration conflicts.…”

“…The Q&A mentions a possible difference between two different binaries for the same configuration due to "different compilers/linkers used, because of build timestamp and so on" 9 . However, the mention of the variable to set in order to remove the timestamp variation was found in the mailing list from 2017 10 . Hence setting KCONFIG_NOTIMESTAMP=1 disables the build timestamp embedding in the binary.…”

Software variability in service robotics

“…Since large systems can have many variation points, these are often controlled by features (Berger et al 2015) (explained shortly) modeled in a feature model (Berger et al 2013;Czarnecki et al 2012;Nešić et al 2019)-tree-like structures organizing features in a hierarchy, together with constraints among the features. Feature models allow keeping an overview understanding of the platform's variability and, together with configurator tools (Bashroush et al 2017;Krueger 2007;Kastner et al 2009;Hubaux et al 2012;Franz et al 2021), allow deriving individual variants in an automated process. Variants are determined by a selection of features-i.e., the configuration-that adhere to constraints specified in the feature model.…”