I/O Address Map; Itanium™ Processor And Chipset-Specific Memory Space - Intel 460GX Software Developer’s Manual

Figure 4-2. Itanium™ Processor and Chipset-specific Memory Space
FFFF_FFFF
FF00_0000
FEC0_0000
FE00_0000
4.2

I/O Address Map

The 460GX chipset allows I/O addresses to be mapped to resources supported on the I/O buses
underneath the 460GX chipset controller. This I/O space is partitioned into sixteen 4K byte
segments. Each of the segments can be individually configured to any I/O bus. Segment 0 is always
assigned to the compatibility I/O bus (of which there is only one per system).
There are four classes of I/O addresses that are specifically decoded by the 460GX chipset:
•
All I/O addresses less than 100h: These addresses are specifically decoded as "defer-only"
addresses. The SAC does not post any I/O accesses to this range, regardless of the state of the
I/O posting enable bit. This is necessary because I/O accesses below 100h have historically
had ordering side effects: e.g. accesses to the 8259 Interrupt Masks.
Intel® 460GX Chipset Software Developer's Manual
System
Firmware
16 MB
Processor
Specific
4 MB
Chipset
Specific
12 MB
FEFF_FFFF
I/O reserved
1 MB FEF0_0000
Interrupt Delivery
On system bus - 1MB FEE0_0000
I/O reserved
1 MB FED0_0000
I/O SAPIC #255
FECF_F000
I/O SAPIC
#3 to # 254
4KB each
FEC0_3000
I/O SAPIC #2
FEC0_2000
I/O SAPIC #1
FEC0_1000
I/O SAPIC #0
FEC0_0000
FEBF_FFFF
Chipset
FE60_0000
Reserved
8 MB
FE40_0000
GART Table
2 MB
FE20_0000
Chipset
Reserved
2 MB FE00_0000
System Address Map
PCI Bus mapping
of SAPIC addresses.
PCI Bus 2A
PCI Bus 1A
PCI Bus 0B
PCI Bus 0A
4-5