| 摘要 |
The inventive system essentially hides redundant paths to the peripheral devices from the operating system, by reporting a single "virtual" path to the peripheral busses over PCI bus 0. The virtual path includes at least a virtual peripheral bus controller and a virtual video controller. The system also tells the operating system that the real controllers are on another PCI bus on an opposite side of a PCI-to-PCI bridge connected also to PCI bus 0. An I/O system manager selects one of the actual paths, which may, but need not, be connected to PCI bus 0, to handle communications with the peripheral devices. The I/O system manager maintains the controllers on the unselected path in an off-line or standby mode, in case of a failure of one or more of the controllers on the selected path. If a failure occurs, the I/O system manager performs a fail-over operation to change the selection of controllers, and the peripheral devices continue to operate in the same manner on the peripheral busses. The operating system does not respond to the controller failure by declaring a system failure, however, because the operating system continues to look to the virtual path, with its virtual controllers, as a valid path to the peripheral devices. The system also allows hot swapping of PCI bridges, through FET isolation of the unselected controllers. The devices on the PCI bus and the peripheral busses may also be hot swapped through selective FET isolation. |
