IDT PCI Express 89HPES32NT24xG2, User Manual, Page: 253 / 744

IDT Non-Transparent Switch Operation
PES32NT24xG2 User Manual 14 - 5 January 30, 2013
Notes
The destination partition of the translated TLP is specified by the Translated Partition (TPART) field in
the corresponding BARSETUPx register. If the destination partition associated with the translated TLP is
invalid (e.g., there is no NT endpoint associated with the destination partition, the destination partition is not
in the active state, or the destination partition is the same as the partition on which the TLP was received),
then the TLP is treated as an unsupported request by the NT endpoint that received the request.
Refer to section Non Transparent Operation Restrictions on page 14-40 for restrictions on the program-
ming of the translated base address.
Lookup Table Address Translation
BARs two and four may be configured to support lookup table address translation.
– BAR two may be configured to support either a 12-entry or 24-entry lookup table.
– BAR four only supports 12-entry lookup table address translation. Configuring BAR four for 24-
entry lookup table address translation produces undefined results.
– If both BARs two and four are configured for lookup table address translation, then BAR two only
supports a 12-entry lookup table. Configuring BAR two for 24-entry lookup table address transla-
tion while BAR four is configured for 12-entry lookup table address translation produces undefined
results.
Figure 14.3 illustrates the address translation process for a BAR configured as a memory address
window with lookup table address translation.
Figure 14.3 Lookup Table Translation
The address of a TLP that falls within the effective BAR aperture of a BAR may be partitioned into a
base address, index, and offset.
– The base address is equal to the value programmed in the BAR BADDR field bits that are read/
write.
– If the BAR is configured for a 12-entry lookup table, then the index corresponds to the next 4-bits
of the address.
– If the BAR is configured for a 24-entry lookup table, then the index corresponds to the next 5-
address bits.
– The offset address corresponds to address bits that are not part of the base address or index.
Base Address Offset
BAR Translated Base Address
Transaction Address
+
Index
Translated Base Address
Translated Base Address
0
1
Translated Base Address
Translated Base Address
3
4
...
Translated Base Address
Translated Base Address
22
23
Lookup Table