Intel
®
81341 and 81342—Address Translation Unit (PCI Express)
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
322
Order Number: 315037-002US
3.16.28 Inbound ATU Limit Register 0 - IALR0
Inbound address translation for memory window 0 occurs for requests originating in
the PCI Express domain and targeting the 81341 and 81342 internal bus. The address
translation block converts PCI addresses to internal bus addresses.
The inbound translation base address for inbound window 0 is specified in
. When determining block size requirements — as described in
— the translation limit register provides the block size requirements for
the base address register. The remaining registers used for performing address
translation are discussed in
The 81341 and 81342 value register’s programmed value must be naturally aligned
with the base address register’s programmed value. The limit register is used as a
mask; thus, the lower address bits programmed into the 81341 and 81342 value
register are invalid. Refer to the PCI Local Bus Specification, Revision 2.3 for additional
information on programming base address registers.
Bits 31 to 12 within the IALR0 have a direct effect on the IABAR0 register, bits 31 to 12,
with a one to one correspondence. A value of 0 in a bit within the IALR0 makes the
corresponding bit within the IABAR0 a read only bit which always returns 0. A value of
1 in a bit within the IALR0 makes the corresponding bit within the IABAR0 read/write
from PCI. Note that a consequence of this programming scheme is that unless a valid
value exists within the IALR0, all writes to the IABAR0 has no effect since a value of all
zeros within the IALR0 makes the IABAR0 a read only register.
Note:
Bit 0 can be used to disable claiming of Memory Cycles that hit Inbound Memory
Window 0 even though the host processor has allocated memory of the size requested
by IABAR0/IALR0[31:12].
.
Table 162. Inbound ATU Limit Register 0 - IALR0
Bit
Default
Description
31:12
FF000H
Inbound Translation Limit 0 - This readback value determines the memory block size required for
inbound memory window 0 of the address translation unit. This defaults to an inbound window of 16MB.
11:01
000H
Reserved
00
0
2
Memory Window 0 Claim Disable -- When clear, Inbound Memory Window 0 claims PCI Memory Cycles
Normally. When set, memory transactions targeting Inbound Memory Window 0 is terminated as an
Unsupported Request (UR).
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
rv
rv
rv
rv
rv
rv
rw
rw
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
+040H