Intel
®
81341 and 81342—Address Translation Unit (PCI Express)
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
254
Order Number: 315037-002US
3.3.2.3
Outbound DMA Transactions
The ATU provides all ADMA channels with a transparent path through the PCI Express
interface. The entire 64-bit Host I/O Interface address programmed in the DMA
descriptor is passed to the PCI Express link unmodified.
3.3.2.4
Outbound Function Number
The 81341 and 81342 is a multi-function device and the ATU associates each
transaction with the correct PCI Express function number according to the following
algorithm:
• Outbound Configuration transactions use the function number field specified in the
“Outbound Configuration Cycle Function Number - OCCFN” on page 388
.
• Outbound I/O transactions use the function number field specified in the
I/O Base Address Register - OIOBAR” on page 376
.
• Outbound transactions targeting the outbound memory windows utilize the
“Outbound Window x Function Number Mapping” programmed into bits 30:28 of
the associated OUMBARx registers
• Outbound ADMA transactions use the “Host I/O Interface Function Number”
programmed in the ADMA byte count register.
Figure 28. Outbound Address Translation Windows
ATU Outbound Memory
Translation Windows
(Default)
ATU Outbound I/O Cycle
Translation Window
(default)
1 0000 0000H
2 0000 0000H
0 0000 0000H
1 FFFF FFFFH
2 FFFF FFFFH
Memory Window 0
Memory Window 1
Code / Data
I/O Window
4 Gbytes
64 Kbytes
External Memory
Note: These memory section defaults can be modified by programming the
OUMBAR0-3 registers prior to enabling outbound translation in the ATUCR.
3 0000 0000H
3 FFFF FFFFH
Memory Window 2
4 0000 0000H
4 FFFF FFFFH
Memory Window 3
0 FFFD 0000H
0 FFFD FFFFH
0 FFFC FFFFH
B6197-01