ID_PFR2

For general information about the interpretation of the ID registers see 'Principles of the ID scheme for fields in ID registers'.

Configuration

AArch64 System register ID_PFR2_EL1 bits [31:0] are architecturally mapped to AArch32 System register ID_PFR2[31:0].

Attributes

Field descriptions

When AArch32 is supported:

Bits [63:12]

RAS_frac, bits [11:8]

RAS Extension fractional field. Defined values are:

RAS_frac	Meaning
0b0000	If ID_PFR0_EL1.RAS == 0b0001, RAS Extension implemented.
0b0001	If ID_PFR0_EL1.RAS == 0b0001, as 0b0000 and adds support for additional ERXMISC<m> System registers. Error records accessed through System registers conform to RAS System Architecture v1.1, which includes simplifications to ERR<n>STATUS and support for the optional RAS Timestamp Extension.

RAS_frac

Meaning

0b0000

If ID_PFR0_EL1.RAS == 0b0001, RAS Extension implemented.

0b0001

If ID_PFR0_EL1.RAS == 0b0001, as 0b0000 and adds support for additional ERXMISC<m> System registers.

Error records accessed through System registers conform to RAS System Architecture v1.1, which includes simplifications to ERR<n>STATUS and support for the optional RAS Timestamp Extension.

All other values are reserved.

This field is valid only if ID_PFR0_EL1.RAS == 0b0001.

SSBS, bits [7:4]

Speculative Store Bypassing controls in AArch64 state. Defined values are:

SSBS	Meaning
0b0000	AArch32 provides no mechanism to control the use of Speculative Store Bypassing.
0b0001	AArch32 provides the PSTATE.SSBS mechanism to mark regions that are Speculative Store Bypass Safe.

In Armv8.0, the permitted values are 0b0000 and 0b0001.

From Armv8.5, the only permitted value is 0b0001.

All other values are reserved.

CSV3, bits [3:0]

Speculative use of faulting data. Defined values are:

CSV3	Meaning
0b0000	This PE does not disclose whether data loaded under speculation with a permission or domain fault can be used to form an address or generate condition codes or SVE predicate values to be used by other instructions in the speculative sequence.
0b0001	Data loaded under speculation with a permission or domain fault cannot be used to form an address, generate condition codes, or generate SVE predicate values to be used by other instructions in the speculative sequence. The execution timing of any other instructions in the speculative sequence is not a function of the data loaded under speculation.

All other values are reserved.

FEAT_CSV3 implements the functionality identified by the value 0b0001.

In Armv8.0, the permitted values are 0b0000 and 0b0001.

From Armv8.5, the only permitted value is 0b0001.

If FEAT_E0PD is implemented, FEAT_CSV3 must be implemented.

Otherwise:

Bits [63:0]

Accessing ID_PFR2_EL1

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

MRS <Xt>, ID_PFR2_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b0000	0b0011	0b100

if PSTATE.EL == EL0 then if IsFeatureImplemented(FEAT_IDST) then if EL2Enabled() && HCR_EL2.TGE == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.SystemAccessTrap(EL1, 0x18); else UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && (IsFeatureImplemented(FEAT_FGT) || !IsZero(ID_PFR2_EL1) || boolean IMPLEMENTATION_DEFINED "ID_PFR2_EL1 trapped by HCR_EL2.TID3") && HCR_EL2.TID3 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else X[t, 64] = ID_PFR2_EL1; elsif PSTATE.EL == EL2 then X[t, 64] = ID_PFR2_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = ID_PFR2_EL1;

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																				RAS_frac				SSBS				CSV3

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
UNKNOWN
UNKNOWN

ID_PFR2_EL1, AArch32 Processor Feature Register 2

Purpose

Configuration

Attributes

Field descriptions

When AArch32 is supported:

Bits [63:12]

RAS_frac, bits [11:8]

SSBS, bits [7:4]

CSV3, bits [3:0]

Otherwise:

Bits [63:0]

Accessing ID_PFR2_EL1

MRS <Xt>, ID_PFR2_EL1