System Address Space
A–5
Address Map
Figure 1–1 Address Space Overview
DMA access to the system memory is achieved using windows in one of the follow-
ing three ways:
•
Directly, using the “Monster Window” with dual-address cycles (DAC), where
ad<33:0> equals addr_h<33:0>.
•
Directly-mapped, by concatenating an offset to a portion of the PCI address.
•
Virtually, through a scatter-gather translation map. The scatter-gather map
allows any 8KB page of PCI memory address region to be redirected to any
8KB cached memory page, as shown in Figure 1–2.
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Environment
Main System
Memory
PCI
Memory Space
PCI Window
PCI I/O Space
PCI
Device
PCI
Configuration
Space
CSRs
PCI
Device
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LJ-05395.AI4