Merge-Tree: Visualizing the Integration of Commits into Linux

Version control systems are an asset to software development, enabling developers to keep snapshots of the code as they work. Stored in the version control system is the entire history of the software project, rich in information about who is contributing to the project, when contributions are made, and to what part of the project they are being made. Presented in the right way, this information can be made invaluable in helping software developers continue the development of the project, and maintainers to understand how the changes to the current version can be applied to older versions of projects. Maintainers are unable to effectively use the information stored within a software repository to assist with the maintanance older versions of that software in highly-collaborative projects. The Linux kernel repository is an example of such a project. This thesis focuses on improving visualizations of the Linux kernel repository, developing new visualizations that help answer questions about how commits are integrated into the project. Older versions of the kernel are used in a variety of systems where it is impractical to update to the current version of the kernel. Some of these applications include the controllers for spacecrafts, the core of mobile phones, the operating system driving internet routers, and as Internet-Of-Things (IOT) device firmware. As vulnerabilities are discovered in the kernel, they are patched in the current version. To ensure that older versions are also protected against the vulnerabilities, the patches applied to the current version of the kernel must be applied back to the older version. To do this, maintainers must be able to understand how the patch that fixed the vulnerability was