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4.2.2. c1 registers

Table 4.3 shows the CP15 system control registers you can access when CRn is c1.

Table 4.3. c1 register summary
Op1CRmOp2Name TypeReset Description
0c00

SCTLR

RW-[a]

System Control Register

1

ACTLR[b]

RW0x00000000

Auxiliary Control Register

2

CPACR

RW

-[c]

Coprocessor Access Control Register

c10SCR[d][e]RW0x00000000

Secure Configuration Register

1SDER[d]RW0x00000000Secure Debug Enable Register
2NSACRRW[f]-[g]Non-secure Access Control Register
3VCR[d]RW0x00000000Virtualization Control Register

[a] Depends on input signals. See System Control Register.

[b] RO in Non-secure state if NSACR[18]=0 and RW if NSACR[18]=1.

[c] The reset value depends on the VFP and NEON configuration.

  • If VFP and NEON are implemented, and NEON is powered up, the reset value is 0x00000000

  • If VFP is implemented, and NEON is not implemented or powered down, the reset value is 0x80000000

  • If VFP and NEON are not implemented, the reset value is 0xC0000000.

[d] No access in Non-secure state.

[e] SCR[6] is not implemented, RAZ/WI.

[f] RW in Secure state and RO in the Non-secure state.

[g] 0x00000000 if NEON present and 0x0000C000 if NEON not present.


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