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Figure 1–1 Address Space Overview
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Environment
Main System
Memory
PCI
Memory Space
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PCI I/O Space
Configuration
CSRs
Space
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.
PCI Window
PCI
Device
PCI
Address Map
PCI
Device
System Address Space
A–5
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