This artifact contains the source code of FlexOS, the proof of-concept of our flexible isolation approach presented at ASPLOS'22 ("FlexOS: Towards Flexible OS Isolation"), along with all scripts necessary to reproduce the paper���s measurements and plots. The goal of this artifact is to allow readers to reproduce the paper���s results, and build new research on top of FlexOS. Abstract of the paper: At design time, modern operating systems are locked in a specific safety and isolation strategy that mixes one or more hardware/software protection mechanisms (e.g. user/kernel separation); revisiting these choices after deployment requires a major refactoring effort. This rigid approach shows its limits given the wide variety of modern applications' safety/performance requirements, when new hardware isolation mechanisms are rolled out, or when existing ones break. We present FlexOS, a novel OS allowing users to easily specialize the safety and isolation strategy of an OS at compilation/deployment time instead of design time. This modular LibOS is composed of fine-grained components that can be isolated via a range of hardware protection mechanisms with various data sharing strategies and additional software hardening. The OS ships with an exploration technique helping the user navigate the vast safety/performance design space it unlocks. We implement a prototype of the system and demonstrate, for several applications (Redis/Nginx/SQLite), FlexOS��� vast configuration space as well as the efficiency of the exploration technique: we evaluate 80 FlexOS configurations for Redis and show how that space can be probabilistically subset to the 5 safest ones under a given performance budget. We also show that, under equivalent configurations, FlexOS performs similarly or better than several baselines/competitors.

Version 0.2 includes fixes developed during the Artifact Evaluation time. The latest version of this artifact is also available on GitHub: https://github.com/project-flexos/asplos22-ae