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The access permission bits control access to the corresponding memory region. If an access is made to an area of memory without the required permissions, then a permission fault is raised.
The access permissions are determined by the AP[2:0] bits in the Data Access Permission Registers.
Table 5.7 shows the bit values of the AP[2:0] bits that determines the permissions for Privileged and User data access.
Table 5.7. Access data permission bit encoding
| AP[2:0] | Privileged permissions | User permissions | Description |
|---|---|---|---|
| b000 | No access | No access | All accesses generate a permission fault |
| b001 | Read/write | No access | Privileged access only |
| b010 | Read/write | Read-only | Writes in User mode generate permission faults |
| b011 | Read/write | Read/write | Full access |
| b100 | UNP | UNP | Reserved |
| b101 | Read-only | No access | Privileged read-only |
| b110 | Read-only | Read-only | Privileged/User read-only |
| b111 | UNP | UNP | Reserved |