Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
583
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
When the secondary memory window address range is defined outside the defined
primary memory window, access made to the SDRAM memory via to the secondary
memory window may not be able to access the SDRAM memory array, or may access
unintended parts of the SDRAM memory array. If the secondary memory window
address range is defined outside the primary memory window, transactions made to
the secondary memory window will be claimed, but the DMCU discards the transactions
and will post an Address Range Error, bit 3 of the
Table 393, “DDR Memory Controller
Interrupt Status Register — DMCISR” on page 647
.
Since the DMCU maintains memory coherency as described in section
“DMCU Port Coherency” on page 571
, the upper four bits [35:32] of the secondary
memory window address are translated by the value provided in the
Base Register — SDUBR” on page 633
. The translated address, which is now a primary
memory window address, is then used by the coherency logic. In addition, since the
DMCU translates the secondary memory window address to a primary memory window
address, errors are logged using the primary memory window address.
Note:
Accessing the SDRAM memory via the Secondary Memory Window must only be
performed by the Intel XScale® microarchitecture. Other Internal Bus Masters like the
Address Translation Units and the DMA Engines must access the SDRAM memory only
via the Primary Memory Window.