Root Complex Register Blocks (RCRBs)
What Problem Does an RCRB Address?
Refer to Figure 21-15 on page 766. Main memory is an extremely popular target. In addition to the processor, it is accessed by the graphics controller and is frequently accessed by PCI, PCI-X and PCI Express devices. This being the case, at a given moment in time, the Root Complex may simultaneously receive memory access requests through multiple ingress ports:
The FSB interface.
The graphics link.
One or more Root Ports.
Figure 21-15. RCRB Example
It should be obvious that a traffic director (labeled “Port/VC Arbitration”) must be implemented within the Root Complex. In its ...
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