Outbound Memory Base Address Register (Ombar) - Motorola MPC8240 User Manual

Address Translation
Bits Name
31 — 0
30–12 Inbound Undefined R/W
translation
base address
11–5 — All 0s
4–0 Inbound All 0s
window size
The lower-order address bits of the base address field of ITWR that are within the range
specified by the window size are ignored and the MPC8240 ignores the incoming
lower-order address bits (within the range specified by the window size). However, for
future compatibility, it is recommended that the base address be programmed to be
naturally aligned to the window size. For example, if the window size is programmed as 1
Mbyte, then the base address should be aligned to a 1-Mbyte boundary (as ITWR[19–12]
are not used to determine if there is a hit to the inbound translation window for a 1-Mbyte
window).

3.3.3.3 Outbound Memory Base Address Register (OMBAR)

The OMBAR, shown in Figure 3-10 and Table 3-10, defines the outbound memory
window.
1
31 30
Figure 3-10. Outbound Memory Base Address Register (OMBAR)—0x0_2300
3-16
Table 3-9. Bit Settings for ITWR—0x0_2310
Reset
R/W
Value
R Reserved. Translated addresses can only be targeted at local memory in
the lower 2 Gbytes of the MPC8240 address space.
Local memory address that is the starting address for the inbound
translation window. The inbound translation window should be aligned
based on the granularity specified by the inbound window size.
R Reserved
R/W Inbound window size. The inbound window size is encoded as N where
the window size is 2
maximum window size is 1 Gbyte. Note that the inbound window size
sets the size of both the inbound memory window and the inbound
translation window.
00000 Inbound address translation disabled
00001 Reserved
...
01010 Reserved
12
01011 2
13
01100 2
14
01101 2
...
30
11101 2
11110 Reserved
11111 Reserved
Note that the inbound memory window must not overlap with the EUMB.
Outbound Memory Base Address
MPC8240 Integrated Processor User's Manual
Description
N+1
bytes. The minimum window size is 4 Kbytes; the
= 4 Kbyte window size
= 8 Kbyte window size
= 16 Kbyte window size
= 1 Gbyte window size
12 11
Reserved
0 0 0 0 0 0 0 0 0 0 0 0
5 4 0