Intel CONTROLLERS 413808 - Manual (Page 85)

Intel ® 413808 and 413812 I/O Controllers in TPER Mode
October 2007 Developer’s Manual
Order Number: 317805-001US 85
Address Translation Unit (PCI-X)—Intel
®
413808 and 413812
2.6.1.3 Inbound Delayed Write Queue
The IDWQ is used specifically for inbound configuration write cycles to the ATU. I/O
Write transactions are not accepted by the ATU and result in a Master Abort.
The IDWQ contains both the address and data of a configuration write cycle. When
operating in the conventional PCI mode, the configuration writes are handled as
delayed writes. When operating in the PCI-X mode, the configuration writes are
handled as split writes. When the write cycle is initiated on the PCI bus, the address
and data are entered into the 8 byte queue, and forwarded to the internal bus. The
transaction is forwarded to the internal bus once transaction ordering has been
satisfied. The status of the transaction (normal completion) is maintained in the IDWQ
for return to the PCI master on the initiating bus. When operating in the PCI-X mode, a
write completion message is generated by the ATU to indicate the successful execution
of the configuration write transaction.
The IDWQ can only hold 32-bits of data and should never be accessed with
REQ64#
asserted per the PCI Local Bus Specification, Revision 2.3 which states that “only
memory transactions support 64-bit data transfers”. In addition, the cycle should
always return only 32-bits of data on the internal bus.
2.6.1.4 Inbound Transaction Queues Command Translation Summary
Table 11. PCI to Internal Bus Command Translation for All Inbound Transactions
PCI Command Conventional Mode PCI-X Mode Internal Bus Command
Memory Write a a Write
Memory Write and Invalidate a Write
Memory Write Block a Write
Alias to Memory Write Block a Write
Memory Read a Read
Memory Read Line a Read
Memory Read Multiple a Read
Memory Read Block a Read
Alias to Memory Read Block a Read
Memory Read DWORD a Read
Configuration Read a a Read
Configuration Write a a Write
Split Read Completion a Data Transfer
Split Write Completion a None
Split Completion Error Message a Data Transfer Abort
All Other Commands Not
Claimed by the ATU
a a N/A