Running device drivers as unprivileged user-level code, encapsulated into their own process, has often been proposed as a technique for increasing system robustness.

Providing efficient device driver support in the Fluke operating system presents novel challenges, which stem from two conflicting factors: (i) a design and maintenance requirement to reuse unmodified legacy device drivers, and (ii) the mismatch between the Fluke kernel's internal execution environment and the execution environment expected by these legacy device drivers. This thesis presents a solution to this conflict: a framework whose design is based on running device drivers as usermode servers, which resolves the fundamental execution environment mismatch. This approach

This thesis presents FIFS (Framework for Implementing File Systems), a framework that facilitates academic file system research under Windows NT. FIFS addresses the high cost of file system development under Windows NT by providing a simple user-mode development environment. The environment is a Common Internet File System (CIFS) loopback server that seamlessly integrates with NT's Installable File System (IFS) architecture via the Common Internet File System (CIFS) client included in the operating system. As such, it can provide full NT remote file system semantics. Initial performance measurements of the prototype FIFS implementation show FIFS capable of achieving good performance. Our prototype non-caching user-mode NFS implementation performs at about 70% the speed of a commercial non-caching kernel-mode NFS implementation.

This paper presents our progress towards FUSE-NT, a Windows port of Filesystem in Userspace (FUSE). FUSE is a service that allows users to implement functional file systems in userspace. It provides a simple but sufficiently powerful set of APIs which allow users to design and implement original file systems without dealing with the complications of kernel programming. Currently, FUSE itself is available on Linux, BSD, and Mac OS, but not Windows. Implementing FUSE on Windows brings about new challenges due to different file system design principles and ethics of the two systems, and a good amount of complexity in the Windows interfaces. This paper describes our unsuccessful attempts at writing a Windows port of FUSE using a native file system driver and some of the difficulties we faced as well as design decisions we had to make. It then describes our prototype that uses a server for the Common Internet File System (CIFS) to provide the FIFS interface.