Intel
®
81341 and 81342—Address Translation Unit (PCI Express)
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
312
Order Number: 315037-002US
3.16.16 Inbound ATU Base Address Register 1 - IABAR1
The Inbound ATU Base Address Register 1 (IABAR1) together with the Inbound ATU
Upper Base Address Register 1 (IAUBAR1) defines the block of memory addresses
where the inbound translation window 1 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 IABAR1 and IAUBAR1 define
the base address and describes the required memory block size; see
“Determining Block Sizes for Base Address Registers” on page 310
. Bits 31 through 12
of the IABAR1 is either read/write bits or read only with a value of 0 depending on the
value located within the IALR1. This configuration allows the IABAR1 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 IALR1 is cleared prior to host configuration, the user should also clear the
Prefetchable Indicator and the Type Indicator. Assuming IALR1 is not cleared:
a. 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.
b. 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 IABAR1.
Table 150. Inbound ATU Base Address Register 1 - IABAR1
Bit
Default
Description
31:12
00000H
Translation Base Address 1 - These bits define the actual location of window 1 on the PCI Express Link.
11:04
00H
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:
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
Internal Bus Address Offset
+018H