System Control
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
4-235
ID021414
Non-Confidential
MRC p15, 4, <Rt>, c2, c1, 2; Read VTCR into Rt
MCR p15, 4, <Rt>, c2, c1, 2; Write Rt to VTCR
4.5.45
Domain Access Control Register
The DACR characteristics are:
Purpose
Defines the access permission for each of the sixteen memory domains.
Usage constraints
This register is accessible as follows:
Configurations
DACR (NS) is architecturally mapped to AArch64 register
DACR32_EL2. See
Domain Access Control Register
on page 4-92
.
There are separate Secure and Non-secure copies of this register.
DACR has write access to the Secure copy of the register disabled when
the
CP15SDISABLE
signal is asserted HIGH.
DACR has no function when TTBCR.EAE is set to 1, to select the
Long-descriptor translation table format.
Attributes
DACR is a 32-bit register.
Figure 4-119
shows the DACR bit assignments.
Figure 4-119 DACR bit assignments
Table 4-214
shows the DACR bit assignments.
To access the DACR:
MRC p15, 0, <Rt>, c3, c0, 0 ; Read DACR into Rt
MCR p15, 0, <Rt>, c3, c0, 0 ; Write Rt to DACR
EL0
(NS)
EL0
(S)
EL1
(NS)
EL1
(S)
EL2
EL3
(SCR.NS = 1)
EL3
(SCR.NS = 0)
-
-
RW
RW
RW
RW
RW
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
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
Table 4-214 DACR bit assignments
Bits
Name
Function
[31:0]
D<
n
>, bits
[2
n
+1:2
n
], for
n
= 0 to 15
Domain
n
access permission, where
n
= 0 to 15. Permitted values are:
0b00
No access. Any access to the domain generates a Domain fault.
0b01
Client. Accesses are checked against the permission bits in the translation tables.
0b11
Manager. Accesses are not checked against the permission bits in the translation tables.
The value
0b10
is reserved.