Inbound Pci Address Translation - Motorola MPC8240 User Manual

Address Translation
.
PCI Memory Space
0
Local memory
base address Inbound memory
window
4G
Inbound address translation only allows address translation to the local memory space (the
lower 1 Gbyte of the address space). This means that an external PCI master cannot access
devices in the ROM/Port X address space when using inbound address translation. Since
the local memory space is restricted to addresses below 0x4000_0000 (1 Gbyte), any access
that gets translated above 0x4000_0000 triggers a memory select error. Thus, the entire
inbound translation window must be programmed to be below 0x4000_0000.
The local memory base address register (LMBAR) and the inbound translation window
register (ITWR) specify the location and size of the inbound memory window and the
inbound translation window. These registers are described in Section 3.3.3, "Address
Translation Registers." Inbound address translation may be disabled by programming the
inbound window size in the ITWR to all zeros. If inbound translation is disabled, the
MPC8240 ignores all PCI memory transactions.
Note that overlapping the inbound memory window and the outbound translation window
is not supported and can cause unpredictable behavior. Also note that the inbound memory
window must not overlap the EUMB as specified by the PCSRBAR (PCI memory space
view). See Section 3.4, "Embedded Utilities Memory Block (EUMB)," for more
information.
3-12
Inbound address
translation
Figure 3-6. Inbound PCI Address Translation
MPC8240 Integrated Processor User's Manual
Processor
Core
View
0
Local memory space
Inbound translation
window
1G
2G
PCI memory space
4G
Inbound translation
base address
Inbound window
size