Provided are a method, system, and program for interfacing with device hardware supporting a plurality of devices. A device interface driver is initialized to represent the device hardware as a virtual bus to an operating system and to represent to the operating system each device supported in the device hardware as a device attached to the virtual bus. The device hardware is initialized and accessed to determine devices supported by the device hardware. One device object is generated for each determined device supported by the device hardware, wherein each generated device object represents the determined device to the operating system. The determined devices are reported to the operating system, wherein the operating system loads a device driver for each of the reported devices supported by the device hardware.