LORN_EL1

Holds the number of the LORegion described in the current LORegion descriptor selected by LORC_EL1.DS.

Configuration

This register is present only when FEAT_LOR is implemented. Otherwise, direct accesses to LORN_EL1 are UNDEFINED.

Attributes

Field descriptions

Bits [63:8]

Num, bits [7:0]

Number of the LORegion described in the current LORegion descriptor selected by LORC_EL1.DS.

The maximum number of LORegions supported by the PE is 256. If the maximum number is less than 256, then bits[8:N] are RES0, where N is (Log₂(Number of LORegions supported by the PE)).

If this field points to a LORegion that is not supported by the PE, then the current LORegion descriptor does not match any LORegion.

The reset behavior of this field is:

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

Accessing LORN_EL1

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

MRS <Xt>, LORN_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b1010	0b0100	0b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.TLOR == '1' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.NS == '0' then UNDEFINED; elsif EL2Enabled() && HCR_EL2.TLOR == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.LORN_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3.TLOR == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = LORN_EL1; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.TLOR == '1' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.TLOR == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = LORN_EL1; elsif PSTATE.EL == EL3 then if SCR_EL3.NS == '0' then UNDEFINED; else X[t, 64] = LORN_EL1;

MSR LORN_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b1010	0b0100	0b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.TLOR == '1' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.NS == '0' then UNDEFINED; elsif EL2Enabled() && HCR_EL2.TLOR == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.LORN_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3.TLOR == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else LORN_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.TLOR == '1' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.TLOR == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else LORN_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then if SCR_EL3.NS == '0' then UNDEFINED; else LORN_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
RES0
RES0																								Num

LORN_EL1, LORegion Number (EL1)

Purpose