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