Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK 데이터 시트
제품 코드
AT91SAM9N12-EK
Programmer’s Model
ARM DDI0198D
Copyright © 2001-2003 ARM Limited. All rights reserved.
2-15
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the RR bit.
Assuming that TCM regions are disabled, the caches behave as shown in Table 2-12.
If either the DCache or the ICache is disabled, then the contents of that cache are not
accessed. If the cache is subsequently re-enabled, the contents will not have changed.
To guarantee that memory coherency is maintained, the DCache must be cleaned of
dirty data before it is disabled.
accessed. If the cache is subsequently re-enabled, the contents will not have changed.
To guarantee that memory coherency is maintained, the DCache must be cleaned of
dirty data before it is disabled.
Table 2-12 Effects of Control Register on caches
Cache
MMU
Behavior
ICache disabled
Enabled or
disabled
disabled
All instruction fetches are from external memory (AHB).
ICache enabled
Disabled
All instruction fetches are cachable, with no protection checks. All addresses are flat
mapped. That is VA = MVA = PA.
mapped. That is VA = MVA = PA.
ICache enabled
Enabled
Instruction fetches are cachable or noncachable, and protection checks are performed.
All addresses are remapped from VA to PA, depending on the MMU page table entry.
That is, VA translated to MVA, MVA remapped to PA.
All addresses are remapped from VA to PA, depending on the MMU page table entry.
That is, VA translated to MVA, MVA remapped to PA.
DCache disabled
Enabled or
disabled
disabled
All data accesses are to external memory (AHB).
DCache enabled
Disabled
All data accesses are noncachable nonbufferable. All addresses are flat mapped. That
is VA = MVA = PA.
is VA = MVA = PA.
DCache enabled
Enabled
All data accesses are cachable or noncachable, and protection checks are performed.
All addresses are remapped from VA to PA, depending on the MMU page table entry.
That is, VA translated to MVA, MVA remapped to PA.
All addresses are remapped from VA to PA, depending on the MMU page table entry.
That is, VA translated to MVA, MVA remapped to PA.