Devil: An IDL for Hardware Programming

To keep up with the frantic pace at which devices come out, drivers need to be quickly developed, debugged and tested. Although a driver is a critical system component, the driver development process has made little (if any) progress. The situation is particularly disastrous when considering the hardware operating code (i.e., the layer interacting with the device). Writing this code often relies on inaccurate or incomplete device documentation and involves assembly-level operations. As a result, hardware operating code is tedious to write, prone to errors, and hard to debug and maintain. This paper presents a new approach to developing hardware operating code based on an Interface Definition Language (IDL) for hardware functionalities, named Devil. This IDL allows a high-level definition of the communication with a device. A compiler automatically checks the consistency of a Devil definition and generates efficient low-level code. Because the Devil compiler checks safety critical properties, the long-awaited notion of robustness for hardware operating code is made possible. Finally, the wide variety of devices that we have already specified (mouse, sound, DMA, interrupt, Ethernet, video, and IDE disk controllers) demonstrates the expressiveness of the Devil language.