ARM Cortex-M3 - Table 9-9 Cache Policy for Memory Attribute Encoding; Table 9-10 AP Encoding; Table 9-11 XN Encoding

Memory Protection Unit
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Table 9-9 describes the cache policy for memory attribute encoding.
Note
All cache policies presented by HPROT and MEMATTR relate to an outer cache.
Table 9-10 describes the AP encoding.
Table 9-11 describes the XN encoding.
Table 9-9 Cache policy for memory attribute encoding
Memory attribute encoding (AA and BB) Cache policy
00 Non-cacheable
01 Write back, write and read allocate
10 Write through, no write allocate
11 Write back, no write allocate
Table 9-10 AP encoding
AP[2:0] Privileged permissions User permissions Descriptions
000 No access No access All accesses generate a permission fault
001 Read/write No access Privileged access only
010 Read/write Read only Writes in user mode generate a permission fault
011 Read/write Read/write Full access
100 Unpredictable Unpredictable Reserved
101 Read only No access Privileged read only
110 Read only Read only Privileged/user read only
111 Read only Read only Privileged/user read only
Table 9-11 XN encoding
XN Description
0 All instruction fetches enabled
1 Instruction fetches disabled