Outbound Pci Address Translation - Motorola MPC8240 User Manual

3.3.2 Outbound PCI Address Translation

For outbound translation, an outbound memory window is specified in the upper 2 Gbytes
of the MPC8240's address space, and an outbound translation window is specified in the
PCI memory space. Processor and DMA transactions that fall within the outbound memory
window are forwarded to the PCI bus with the address translated to the outbound translation
window. Outbound transaction addresses outside of the outbound memory window are
forwarded to the PCI bus untranslated.
Figure 3-7 shows outbound PCI address translation from the processor core address space
to PCI memory space.
PCI Memory Space
0
Host memory space
Outbound
Outbound translation
window size
PCI memory space
4G
Figure 3-7. Outbound PCI Address Translation
Transactions to the MPC8240 address space marked as configuration address,
configuration data, and interrupt acknowledge (0xFEC0_0000–0xFEFF_FFFF) are
excluded from the outbound memory window. If the outbound memory base address is set
to include this range, the MPC8240 will not translate the accesses to the outbound
translation window. That is, the range appears as a hole in the outbound translation.
Outbound translation
base address
window
Outbound address
translation
Transactions outside the
outbound memory
window are forwarded
without translation
Chapter 3. Address Maps
Address Translation
Processor
View
0
Local memory space
TOM
2G
PCI memory space
Outbound memory
base address
Outbound memory
window
4G - 20M
4G - 16M
4G
3-13