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March 2002 Release
1-800-255-7778
Virtex-II Pro™ Platform FPGA Documentation
Chapter 5:
Memory-System Management
R
0
6
7
8
9
10 11
14
15
20
21
22
23
27
31
LWL LWOA SWOA DPP1
IPP
U0XE
LBDE
PFC PFNC NCRS FWOA
CIS
CWS
Figure 5-13:
Core-Configuration Register (CCR0)
Table 5-6:
Core-Configuration Register (CCR0) Field Definitions
Bit
Name
Function
Description
0:5
Reserved
6
LWL
Load Word as Line
0—Load only requested data
1—Load entire cacheline
When this bit is set to 1, eight words are loaded into the fill buffer
when a data-cache load-miss occurs, or when a load from non-
cacheable memory occurs. The requested data is included in the
eight words. When this bit is cleared to 0, only the requested data
is loaded.
7
LWOA
Load Without Allocate
0—Allocate
1—Do not allocate
When this bit is set to 1, a load miss behaves like a non-cacheable
load and does not allocate a data cacheline. When cleared to 0, load
misses allocate a data cacheline.
8
SWOA
Store Without Allocate
0—Allocate
1—Do not allocate
When this bit is set to 1, a store miss behaves like a non-cacheable
store and does not allocate a data cacheline. When cleared to 0,
store misses to write-back memory allocate a data cacheline.
9
DPP1
DCU PLB-Priority Bit 1
0—DCU PLB priority 0 on bit 1
1—DCU PLB priority 1 on bit 1
Establishes the value of bit 1 in the 2-bit request-priority signal
driven by the data-cache unit onto the processor local bus (PLB). Bit
0 is controlled by the processor and cannot be controlled by
software. See
for more
information.
10:11
IPP
ICU PLB-Priority Bits 0:1
00—Lowest PLB req priority
01—Next-to-lowest priority
02—Next-to-highest priority
03—Highest PLB req priority
Establishes the value of the 2-bit request-priority signal driven by
the instruction-cache unit onto the processor local bus (PLB). See
for more information.
12:13
Reserved
14
U0XE
Enable U0 Exception
0—Disabled
1—Enabled
Controls data-storage interrupts for memory with the U0 storage
attribute set. A data-storage interrupt occurs when this bit is set to
1 and a store is performed to U0 memory. See
for more information.
15
LDBE
Load-Debug Enable
0—Load data is not visible on
the data-side OCM
1—Load data is visible on the
data-side OCM.
16:19
Reserved
20
PFC
Prefetching for Cacheable
Regions
0—Disabled.
1—Enabled.
When this bit is set to 1, the processor can prefetch instructions
from cacheable memory regions into the instruction-prefetch
buffers. Clearing this bit to 0 disables prefetching from cacheable
memory regions, generally at a cost to performance.
21
PFNC
Prefetching for Non-Cacheable
Regions
0—Disabled.
1—Enabled.
When this bit is set to 1, the processor can prefetch instructions
from non-cacheable memory regions into the instruction-prefetch
buffers. Clearing this bit to 0 disables prefetching from non-
cacheable memory regions, generally at a cost to performance.
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