Method and apparatus for providing support for dynamic resource assignment and configuration of peripheral devices when enabling or disabling plug-and-play aware operating systems

Abstract

A computer system allows devices to be unmasked so to be detected or to be masked invisible to the Plug-and-Play architecture or similar architectures. When operating under Plug-and-Play, which assigns systems resources to system devices in a predetermined order despite a limited number of such resources, a user uses software to set the switch in the device's memory such that an undesired device becomes “invisible” to a subsequent power-up configuration of the system. Device configuration proceeds in two phases. During a first configuration phase, the invisible device cannot be configured, i.e. cannot be assigned resources, including interrupt request lines. Hence, those lines remain available to other devices on the system that would not have received resource allocation during a prior-art configuration. During the first phase, the other devices can be assigned the necessary resources to operate properly. Thus, software can command a configuration that would otherwise be impossible. During a second phase, yet-unconfigured devices are configured. When commanded to do so by software, the memory is reset such that the device becomes visible and thus configurable by the Plug-and-Play architecture. The switch is either a non-volatile memory on the device itself, or a dedicated region within the PCI configuration space. When the system is rebooted, the devices that are invisible are not assigned resources, while the visible devices are assigned resources including interrupt request lines. Thus, a programmable select mask prevents configuration of the peripheral during a first configuration phase when the peripheral device is masked and permits configuration of the peripheral during the first configuration phase when the peripheral device is unmasked. A programmable select mask register or a programmable select mask routine (the latter being executable by the processor) includes a mask indicator corresponding to a peripheral device. If desired, the mask indicator itself forms the invention. The invention also includes a step of, during a second configuration phase, configuring the peripheral device.