ACTLR_EL1

Provides IMPLEMENTATION DEFINED configuration and control options for execution at EL1 and EL0.

Note

Arm recommends the contents of this register have no effect on the PE when HCR_EL2.{E2H, TGE} is {1, 1}, and instead the configuration and control fields are provided by the ACTLR_EL2 register. This avoids the need for software to manage the contents of these register when switching between a Guest OS and a Host OS.

Configuration

AArch64 System register ACTLR_EL1 bits [31:0] are architecturally mapped to AArch32 System register ACTLR[31:0].

AArch64 System register ACTLR_EL1 bits [63:32] are architecturally mapped to AArch32 System register ACTLR2[31:0].

Attributes

Field descriptions

IMPLEMENTATION DEFINED, bits [63:0]

IMPLEMENTATION DEFINED.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Accessing ACTLR_EL1

Accesses to this register use the following encodings in the System register encoding space:

MRS <Xt>, ACTLR_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0000	0b001

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TACR == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && HCR_EL2.<NV2,NV> == '11' then X[t, 64] = NVMem[0x118]; else X[t, 64] = ACTLR_EL1; elsif PSTATE.EL == EL2 then X[t, 64] = ACTLR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = ACTLR_EL1;

MSR ACTLR_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0000	0b001

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TACR == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && HCR_EL2.<NV2,NV> == '11' then NVMem[0x118] = X[t, 64]; else ACTLR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then ACTLR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then ACTLR_EL1 = X[t, 64];

63	62	61	60	59	58	57	56	55	54	53	52	51	50	49	48	47	46	45	44	43	42	41	40	39	38	37	36	35	34	33	32
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
IMPLEMENTATION DEFINED
IMPLEMENTATION DEFINED

ACTLR_EL1, Auxiliary Control Register (EL1)