21555 Non-Transparent PCI-to-PCI Bridge User Manual 47
Address Decoding
4.6 21555 Bar Summary
Table 12 shows a summary of the 21555 BARs.
Table 12. Bar Summary
Bar Size Address Translation
Primary CSR and Downstream
Memory 0
4KB to 2GB
Low 4 KB: None
Above 4KB boundary: Direct Offset
Primary CSR I/O 256 bytes —
Secondary CSR Memory 4 KB —
Secondary CSR I/O 256 bytes —
Primary Expansion ROM 4 KB to 16 MB —
Downstream I/O or Memory 1
64 bytes to 256 bytes (I/O) or
4 KB to 2 GB (memory)
Direct Offset
Downstream Memory 2 4 KB to 2 GB Direct Offset
Downstream Memory 3 4 KB to 2
63
bytes
Direct Offset ( < 4 GB)
None (Š4GB)
Upstream I/O or Memory 0
64 bytes to 256 bytes (I/O) or
4 KB to 2 GB (memory)
Direct Offset
Upstream Memory 1 4 KB to 2 GB Direct Offset
Upstream Memory 2 64 KB to 16 MB Lookup Table
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