Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
209
Address Translation Unit (PCI-X)—Intel
®
81341 and 81342
2.13.64 Inbound ATU Base Address Register 3 - IABAR3
The Inbound ATU Base Address Register 3 (IABAR3) together with the Inbound ATU
Upper Base Address Register 3 (IAUBAR3) defines the block of memory addresses
where the inbound translation window 3 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 IABAR3 and IAUBAR3 define
the base address and describe the required memory block size; see
“Determining Block Sizes for Base Address Registers” on page 169
. Bits 31 through 12
of the IABAR3 is either read/write bits or read only with a value of 0 depending on the
value located within the IALR3. This configuration allows the IABAR3 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.
Note:
Since IABAR3 does not appear in the standard PCI configuration header space (offsets
00H - 3CH), IABAR3 is not configured by the host during normal system initialization.
Warning:
When a non-zero value is not written to IALR3, the user should not set either the
Prefetchable Indicator or the Type Indicator for 64 bit addressability. This is the default
for IABAR3. Assuming a non-zero value is written to IALR3, the user may set the
Prefetchable Indicator or the Type Indicator:
a. Since non prefetchable memory windows can never be placed above the 4 Gbyte
address boundary, when the Prefetchable Indicator is not set, the user should
also leave the Type Indicator set for 32 bit addressability. This is the default for
IABAR3.
b. For compliance to the PCI-X Protocol Addendum to the PCI Local Bus
Specification, Revision 2.0, when the Prefetchable Indicator is set, the user
should also set the Type Indicator for 64 bit addressability.
Table 87. Inbound ATU Base Address Register 3 - IABAR3
Bit
Default
Description
31:12
00000H
Translation Base Address 3 - These bits define the actual location the translation function is to respond
to when addressed from the PCI bus.
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
Register Offset
+200H