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ARM Cortex-A72 MPCore Processor Technical Reference Manual : Auxiliary Control Register, EL2

Auxiliary Control Register, EL2

The ACTLR_EL2 characteristics are:

Purpose
Controls access to IMPLEMENTATION DEFINED registers in Non-secure EL1.
Usage constraints

The accessibility to ACTLR_EL2 in AArch64 state by Exception level is:

EL0 EL1(NS) EL1(S) EL2 EL3(SCR.NS = 1) EL3(SCR.NS = 0)
- - - RW RW RW

The accessibility to the HACTLR in AArch32 state by Exception level is:

EL0 EL1(NS) EL1(S) EL2 EL3(SCR.NS = 1) EL3(SCR.NS = 0)
- - - RW RW -
Configurations

The ACTLR_EL2 is:

  • A Banked EL2 register.
  • Architecturally mapped to the AArch32 HACTLR register.
Attributes
See the register summary in Table 4-4 AArch64 other System registers.

The following figure shows the ACTLR_EL2 bit assignments.

Figure 4-30 ACTLR_EL2 bit assignments


The following table shows the ACTLR_EL2 bit assignments.

Table 4-46 ACTLR_EL2 bit assignments

Bits Name Function
[31:7] - Reserved, RES0.
[6] L2ACTLR access control

L2ACTLR access control. The possible values are:

0The register is not accessible from Non-secure EL1.
1The register is accessible from Non-secure EL1.
[5] L2ECTLR access control

L2ECTLR access control. The possible values are:

0The register is not accessible from Non-secure EL1.
1The register is accessible from Non-secure EL1.
[4] L2CTLR access control

L2CTLR access control. The possible values are:

0The register is not accessible from Non-secure EL1.
1The register is accessible from Non-secure EL1.
[3:2] - Reserved, RES0.
[1] CPUECTLR access control

CPUECTLR access control. The possible values are:

0The register is not accessible from Non-secure EL1.
1The register is accessible from Non-secure EL1.
[0] CPUACTLR access control

CPUACTLR access control. The possible values are:

0The register is not accessible from Non-secure EL1.
1The register is accessible from Non-secure EL1.

To access the ACTLR_EL2 in AArch64 state, read or write the register with:

MRS <Xt>, ACTLR_EL2; Read EL2 Auxiliary Control Register
MSR ACTLR_EL2, <Xt>; Write EL2 Auxiliary Control Register

To access the HACTLR in AArch32 state, read or write the CP15 register with:

MRC p15, 4, <Rt>, c1, c0, 1; Read Hypervisor Auxiliary Control Register
MCR p15, 4, <Rt>, c1, c0, 1; Write Hypervisor Auxiliary Control Register