BRBIDR0

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BRBIDR0_EL1, Branch Record Buffer ID0 Register

Purpose

Configuration

This register is present only when FEAT_BRBE is implemented. Otherwise, direct accesses to BRBIDR0_EL1 are UNDEFINED.

Attributes

Field descriptions

Bits [63:16]

CC, bits [15:12]

FORMAT, bits [11:8]

CC	Meaning
0b0101	20-bit cycle counter implemented.

Data format of records of the Branch record buffer. Defined values are:

FORMAT	Meaning
0b0000	Format 0.

All other values are reserved.

Access to this field is RO.

NUMREC, bits [7:0]

Number of records supported.

The value of this field is an IMPLEMENTATION DEFINED choice of:

NUMREC	Meaning
0x08	8 branch records implemented.
0x10	16 branch records implemented.
0x20	32 branch records implemented.
0x40	64 branch records implemented.

All other values are reserved.

Access to this field is RO.

Accessing BRBIDR0_EL1

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

MRS <Xt>, BRBIDR0_EL1

op0	op1	CRn	CRm	op2
0b10	0b001	0b1001	0b0010	0b000

if !IsFeatureImplemented(FEAT_BRBE) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().SBRBE != '11' && SCR_EL3().NS == '0' then Undefined(); elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().SBRBE IN {'x0'} && SCR_EL3().NS == '1' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HDFGRTR_EL2().nBRBIDR == '0' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3().SBRBE != '11' && SCR_EL3().NS == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif HaveEL(EL3) && MDCR_EL3().SBRBE IN {'x0'} && SCR_EL3().NS == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = BRBIDR0_EL1(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().SBRBE != '11' && SCR_EL3().NS == '0' then Undefined(); elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3().SBRBE IN {'x0'} && SCR_EL3().NS == '1' then Undefined(); elsif HaveEL(EL3) && MDCR_EL3().SBRBE != '11' && SCR_EL3().NS == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif HaveEL(EL3) && MDCR_EL3().SBRBE IN {'x0'} && SCR_EL3().NS == '1' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = BRBIDR0_EL1(); end; elsif PSTATE.EL == EL3 then X{64}(t) = BRBIDR0_EL1(); end;

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RES0
RES0																CC				FORMAT				NUMREC