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AssigneeInternational Business Machines Corporation
InventorsBishop Chapman Brock, Gary Dale Carpenter
Estimating the term…
A system in which bus signals are selectively modified to effectively isolate desired bus agents from the bus. The selective modification of bus signals may be determined from a stored table (permission table) indicating permitted and prohibited bus transaction initiator/target pairs. The permission table may be located in a dedicated device, such as a programmable logic array or application specific integrated circuit. Alternatively, the permission table may be integrated into the bus arbiter. The permission table may be used to provide a unique 1-bit signal to each bus agent indicating whether the corresponding bus agent is permitted to receive transactions from the current bus master. The permission bit may be routed to external gating circuitry associated with each bus agent. The gating circuitry may receive one or more bus control signals and may modify the control signals depending upon the state of the permission bit. In an embodiment in which the bus is a PCI bus, the gating circuitry may receive the FRAME# and GNT# signals for each bus agent.
A data processing system, comprising:
A permission controller suitable for connecting to a bus in a data processing system, the controller comprising permission control logic configured to receive a plurality of grant signals generated by a bus arbiter wherein the grant signals indicate which of a set of corresponding bus agents is granted mastership of the bus and further configured to generate at least one permission signal responsive to the grant signals and indicative of whether a corresponding bus agent is permitted as a target of a transaction initiated by the granted bus agent.
A method of selectively targeting bus agents on a shared bus of a data processing system, comprising:
Dependencies are inferred from the claim text.