CNTFRQ Counter-timer Frequency register when FEAT_AA32 is implemented CNTFRQ_EL0 Architectural AArch64 31 0 31 0 31 0 31 0 This register is provided so that software can discover the effective frequency of the system counter. It must be programmed with this value as part of system initialization. The value of the register is not interpreted by hardware. Timer CNTFRQ is a 32-bit register. ClockFreq Clock frequency 31 0 31:0 Clock frequency. Indicates the effective frequency of the system counter, in Hz. AU MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>} if !IsFeatureImplemented(FEAT_AA32) then Undefined(); elsif PSTATE.EL == EL0 then if IsFeatureImplemented(FEAT_AA64EL1) && !ELUsingAArch32(EL1) && !ELIsInHost(EL0) && CNTKCTL_EL1().[EL0PCTEN,EL0VCTEN] == '00' then if EL2Enabled() && (IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2)) && HCR_EL2().TGE == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); else AArch64_AArch32SystemAccessTrap(EL1, 0x03); end; elsif IsFeatureImplemented(FEAT_AA32EL1) && ELUsingAArch32(EL1) && CNTKCTL().PL0PCTEN == '0' && CNTKCTL().PL0VCTEN == '0' then if EL2Enabled() && (IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2)) && HCR_EL2().TGE == '1' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && (IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2)) && HCR().TGE == '1' then AArch32_TakeHypTrapException(0x00); else Undefined(); end; elsif ELIsInHost(EL0) && (IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2)) && CNTHCTL_EL2().[EL0PCTEN,EL0VCTEN] == '00' then AArch64_AArch32SystemAccessTrap(EL2, 0x03); else R(t) = CNTFRQ(); end; elsif PSTATE.EL == EL1 then R(t) = CNTFRQ(); elsif PSTATE.EL == EL2 then R(t) = CNTFRQ(); elsif PSTATE.EL == EL3 then R(t) = CNTFRQ(); end; MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>} if !IsFeatureImplemented(FEAT_AA32) then Undefined(); elsif IsHighestEL(PSTATE.EL) then CNTFRQ() = R(t); else Undefined(); end; 2026-03-26 20:27:25 2026-03_rel