CADOS: Configurability-Aware Development of Operating Systems

CADOS的目的是研究可伸缩的方法和技术，以掌握系统软件的可变性。例如，Linux 4.2提供了超过15000个静态可配置的特性，用于特定问题的适配，这些特性在技术上被实现并分布在生成过程的几个级别上（配置系统、构建系统、C预处理器、链接器等）。在当前的资金阶段，从系统软件开发人员的角度，这已经被集中在（现有的）静态可变性及其在多个级别和工件语言中的实现上。所开发的方法和工具显著改善了高度可配置的系统相关软件中的静态分析，以及（跨级别）实施中的可变性错误（“#ifdef bugs”）.从“开发者的角度”（可变性的提供者），这是朝着全面掌握系统软件静态可变性迈出的决定性一步，在接下来的资助阶段，将焦点扩展到非静态可变性的形式，但特别是扩展到“用户视图”（可变性的专业用户）：从操作系统的数万个可配置特征中手动选择用于特定问题的“正确”特征已经是几乎不可能的任务。此外，还有大量其他系统软件（库、服务器进程、实用程序），因此，最大配置（标准发行版）在实践中被应用，携带了许多不必要的和昂贵的“cruft”，而由于真正的交替特性，仍然需要多个变体。（可使用特殊指令、单核或多核、中断控制器）。由此产生的系统软件既“太大”（关于不需要的选项）和“太小”因此，下一个供资阶段的研究主题是分析、实施和应用“半动态可变性”，作为在系统软件中实现灵活和视情况而定的可选和替代功能的一种手段，在语言和编译器级别以及关于来自操作系统的必要支持。另一个研究主题是“自动系统范围修剪”，通过这种方法，整个系统软件栈可以跨层边界进行分析，以便自动配置和修剪所产生的系统软件，而只需很少的人工工作。在研究中，我们将主要采用建设性的方法在操作系统构造（内核，链接器和加载器，监控）和编译器（语言，静态分析和代码生成）领域。研究的主题是开源系统软件。

Purpose of CADOS is to research scalable methods and techniques to master the variability of (and in) system software. Linux 4.2, for example, offers more than fifteen thousand statically configurable features for problem-specific adaptation, which are technically implemented and distributed over several levels of the generation process (configuration system, build system, C preprocessor, linker, ...). The resulting variability is no longer manageable in practice.In the current funding phase, this has been examined with focus on (existing) static variability and its implementation across multiple levels and artifact languages from the viewpoint of system-software develpers. The devloped methods and tools significantly improve static analysis in highly configurable, system-related software, as well as the detection of (cross-level) variability errors in their implementation ("#ifdef bugs").From the "developer's point of view" (provider of variability), this is a decisive step towards the comprehensive mastery of static variability in system software.In the following funding phase, the focus shall be expanded to forms of non-static variability, but in particular to the "user view" (professional users of variability): Manually selecting the "right" features for a specific problem from tens of thousands of configurable features for the operating system is already a nearly inpossible undertaking. In addition, there is an extensive stack of other system software (libraries, server processes, utilities) that must be taken into account as well for the specific application.Hence, maximum configurations (standard distributions) are applied in practice that carry a lot of unneeded and costly "cruft", while there are still multiple variants required due to genuinely alternatvive features (availability of special instructions, single or multicore, interrupt controller used). The resulting system software is both “too big” (with regard to options that are not required) and “too small” (with regard to required but context-dependent alternatives).The subject of research for the following funding phase is therefore the analysis, implementation and application of "semi-dynamic variability" as a means of realizing flexible and context-dependent optional and alternative features in system software, both at the language and compiler level and with regard to the necessary support from the operating system.The other subject of research is "automatic system-wide pruning", through which the entire system software stack is to be analyzed across layer boundaries in order to automatically configure and trim the resulting system software with little manual effort.In the research we will apply mostly constructive methods in the domains of operating-system construction (kernel, linker and loader, monitoring) and compilers (language, static analysis and code generation). The subject of research is open-source system software.