Table 9-9 Cache Policy For Memory Attribute Encoding; Table 9-10 Ap Encoding; Table 9-11 Xn Encoding - ARM Cortex-M3 Technical Reference Manual

Memory Protection Unit
AP[2:0] Privileged permissions
000 No access
001 Read/write
010 Read/write
011 Read/write
100 Unpredictable
101 Read only
110 Read only
111 Read only
9-14
Table 9-9 describes the cache policy for memory attribute encoding.
Memory attribute encoding (AA and BB)
00
01
10
11
Table 9-10 describes the AP encoding.
User permissions
No access
No access
Read only
Read/write
Unpredictable
No access
Read only
Read only
Table 9-11 describes the XN encoding.
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Table 9-9 Cache policy for memory attribute encoding

Descriptions
All accesses generate a permission fault
Privileged access only
Writes in user mode generate a permission fault
Full access
Reserved
Privileged read only
Privileged/user read only
Privileged/user read only
XN
0
1
Cache policy
Non-cacheable
Write back, write and read allocate
Write through, no write allocate
Write back, no write allocate

Table 9-10 AP encoding

Table 9-11 XN encoding

Description
All instruction fetches enabled
No instruction fetches enabled
ARM DDI 0337B