System Control Coprocessor
ARM DDI 0301H Copyright © 2004-2009 ARM Limited. All rights reserved. 3-63
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3.2.16 c3, Domain Access Control Register
The purpose of the Domain Access Control Register is to hold the access permissions for a
maximum of 16 domains.
Table 3-59 lists the purposes of the individual bits in the Domain Access Control Register.
The Domain Access Control Register is:
•in CP15 c3
• a 32-bit read/write register banked for Secure and Non-secure worlds
• accessible in privileged modes only.
Figure 3-35 shows the bit arrangement of the Domain Access Control Register.
Figure 3-35 Domain Access Control Register format
Table 3-59 lists how the bit values correspond with the Domain Access Control Register
functions.
Attempts to write to this register in Secure Privileged mode when CP15SDISABLE is HIGH
result in an Undefined exception, see TrustZone write access disable on page 2-9.
Table 3-60 lists the results of attempted access for each mode.
To use the Domain Access Control Register read or write CP15 c3 with:
• Opcode_1 set to 0
• CRn set to c3
• CRm set to c0
• Opcode_2 set to 0.
For example:
D15
31
30
29 28 27 26 25 24 23
22
21
20 19 18
17
16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Table 3-59 Domain Access Control Register bit functions
Bits
Field
name
Function
-
D<n>
a
The purpose of the fields D15-D0 in the register is to define the access permissions for each one of
the 16 domains. These domains can be either sections, large pages or small pages of memory:
b00 = No access, reset value. Any access generates a domain fault.
b01 = Client. Accesses are checked against the access permission bits in the TLB entry.
b10 = Reserved. Any access generates a domain fault.
b11 = Manager. Accesses are not checked against the access permission bits in the TLB entry, so a
permission fault cannot be generated.
a. n is the Domain number in the range between 0 and 15
Table 3-60 Results of access to the Domain Access Control Register
Secure Privileged Non-secure Privileged
User
Read Write Read Write
Secure data Secure data Non-secure data Non-secure data Undefined exception
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