Intel
®
81341 and 81342—Address Translation Unit (PCI-X)
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
164
Order Number: 315037-002US
2.13.17 Inbound ATU Base Address Register 2 - IABAR2
The Inbound ATU Base Address Register 2 (IABAR2) together with the Inbound ATU
Upper Base Address Register 2 (IAUBAR2) defines the block of memory space
addresses where the inbound translation window 2 begins. The inbound ATU decodes
and forwards the bus request to the 81341 and 81342 internal bus with a translated
address to map into 81341 and 81342 local memory. The IABAR2 and IAUBAR2
(Memory Space only) define the base address and describes the required address block
size; see
Section 2.13.23, “Determining Block Sizes for Base Address Registers” on
. Bits 31 through 8 of the IABAR2 is either read/write bits or read only with a
value of 0 depending on the value located within the IALR2. This configuration allows
the IABAR2 to be programmed per PCI Local Bus Specification, Revision 2.3.
The programmed value within the base address register must comply with the PCI
programming requirements for address alignment. Refer to the PCI Local Bus
Specification, Revision 2.3 for additional information on programming base address
registers.
Warning:
When IALR2 is cleared prior to host configuration, the user should also clear the
Prefetchable Indicator and the Type Indicator. Assuming IALR2 is not cleared:
e. Since non prefetchable memory windows can never be placed above the 4 Gbyte address boundary,
when the Prefetchable Indicator is cleared prior to host configuration, the user should also set the
Type Indicator for 32 bit addressability.
f. For compliance to the PCI-X Protocol Addendum to the PCI Local Bus Specification, Revision 2.0,
when the Prefetchable Indicator is set prior to host configuration, the user should also set the Type
Indicator for 64 bit addressability. This is the default for IABAR2.
Table 39. Inbound ATU Base Address Register 2 - IABAR2
Bit
Default
Description
31:12
00000H
Translation Base Address 2 - These bits define the actual location the translation function is to respond
to when addressed from the PCI bus.
11:04
000H
Reserved.
03
0
2
Prefetchable Indicator - When set, defines the memory space as prefetchable.
02:01
00
2
Type Indicator - Defines the width of the addressability for this memory window (Memory Space
Indicator = 0):
00 - Memory Window is locatable anywhere in 32 bit address space
10 - Memory Window is locatable anywhere in 64 bit address space
00
0
2
Memory Space Indicator - This bit field describes memory or I/O space base address. The ATU does not
occupy I/O space, thus this bit must be zero.
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rv
rv
rv
rv
rv
rv
rv
rv
rv
rv
rv
rv
rv
rv
rv
rv
rw
ro
rw
ro
ro
ro
ro
ro
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Register Offset
+020H