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4.3.35. System Control Register, EL2

The SCTLR_EL2 characteristics are:

Purpose

Provides top level control of the system, including its memory system at EL2.

SCTLR_EL2 is part of:

  • The Virtual memory control registers functional group.

  • The Hypervisor and virtualization registers functional group.

Usage constraints

This register is accessible as follows:

EL0

EL1

(NS)

EL1

(S)

EL2

EL3

(SCR.NS = 1)

EL3

(SCR.NS = 0)

---RWRWRW
Configurations

SCTLR_EL2 is architecturally mapped to AArch32 register HSCTLR. See Hyp System Control Register.

Attributes

SCTLR_EL2 is a 32-bit register.

Figure 4.32 shows the SCTLR_EL2 bit assignments.

Figure 4.32. SCTLR_EL2 bit assignments

Figure 4.32. SCTLR_EL2 bit assignments

Table 4.76 shows the SCTLR_EL2 bit assignments.

Table 4.76.  SCTLR_EL2 bit assignments
BitsNameFunction
[31:30]-

Reserved, res0.

[29:28]-Reserved, res1.
[27:26]-Reserved, res0.
[25]EE

Exception endianness. The possible values are:

0

Little endian.

1

Big endian.

The reset value depends on the value of the CFGEND configuration input.

[24]-Reserved, res0.
[23:22]-Reserved, res1.
[21:20]-Reserved, res0.
[19]WXN

Force treatment of all memory regions with write permissions as XN. The possible values are:

0

Regions with write permissions are not forced XN. This is the reset value.

1

Regions with write permissions are forced XN.

[18]-Reserved, res1.
[17]-

Reserved, res0.

[16]-Reserved, res1.
[15:13]-

Reserved, res0.

[12]I

Instruction cache enable. The possible values are:

0

Instruction caches disabled. This is the reset value.

1

Instruction caches enabled.

[11]-Reserved, res1.
[10:6]-Reserved, res0.
[5:4]-Reserved, res1.
[3]SA

Enables stack alignment check. The possible values are:

0

Disables stack alignment check.

1

Enables stack alignment check. This is the reset value.

[2]C

Global enable for data and unifies caches. The possible values are:

0

Disables data and unified caches. This is the reset value.

1

Enables data and unified caches.

[1]A

Enable alignment fault check The possible values are:

0

Disables alignment fault checking. This is the reset value.

1

Enables alignment fault checking.

[0]M

Global enable for the EL2 MMU. The possible values are:

0

Disables EL2 MMU. This is the reset value.

1

Enables EL2 MMU.


To access the SCTLR_EL2:

MRS <Xt>, SCTLR_EL2 ; Read SCTLR_EL2 into Xt
MSR SCTLR_EL2, <Xt> ; Write Xt to SCTLR_EL2
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