Bachelor's Thesis Nr. 88 B

In the early days, connecting devices with a computer involved many different connectors and the attachment of the devices had to be done before the host computer was powered on. The universal serial bus (USB) has replaced many of those old-fashioned connectors and provides a unified and universal connector with hot-plug support. The versatility of the USB makes it an indispensable way of connecting devices with a host computer. Therefore having USB support in an operation system is a precondition for extensibility and usability in the sense of extending the storage capacity with mass storage devices or to provide a way of user input with a USB keyboard. In the context of the multi-kernel operating system Barrelfish, the USB subsystem has to be designed in a distributed fashion and run as pure user-level services. The design idea is to separate the USB stack into two parts. An USB Manager that provides the USB driver interface and handles the configuration of the host controller hardware and a USB client driver for each attached USB device. The USB subsystem should provide hotplug capabilities that the USB client drivers are started and terminated when a device is attached respectively detached on an USB port.