Intel
®
81341 and 81342—Address Translation Unit (PCI Express)
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
240
Order Number: 315037-002US
The ATU unit allows for recognition and generation of multiple PCI Express Transaction
Layer Packets (TLP) types.
shows the commands supported for both inbound
and outbound ATU transactions. The type of operation seen by the ATU on inbound
transactions are determined by the PCI Express requester who initiates the transaction.
Claiming an inbound transaction depends on the address range programmed within the
inbound translation window. The type of transaction used by the ATU on outbound
transactions generated by the core processor is determined by the internal bus address
and the fixed outbound windowing scheme.
ATU supports all four address spaces defined within the PCI Express architecture as
both a requester and completer. These address spaces and corresponding transaction
types are detailed in
.
ATU does not support Locked Requests as a Completer nor generate them as a
Requestor.
Table 115. Supported Address Spaces and Transaction Types
Address Space
Transaction Type
Basic Usage
Memory
a
a. ATU supports both 32-bit and 64-bit addressing for Memory space transactions.
Read
Write
Transfer data to/from a memory-
mapped location
I/O
Read
Write
Transfer data to/from and I/O-
mapped location
Configuration
Read
Write
Device configurations/setup
Message
Baseline
Vendor-defined
From event signalling mechanism to
general purpose messaging