ICC_BPR0
Interrupt Controller Binary Point Register 0
when FEAT_AA32EL1 is implemented and GICv3 is implemented
ICC_BPR0_EL1
Architectural
AArch64
31
0
31
0
31
0
31
0
Defines the point at which the priority value fields split into two parts, the group priority field and the subpriority field. The group priority field determines Group 0 interrupt preemption.
GIC control registers
GIC
ICC_BPR0 is a 32-bit register.
31
3
31:3
Reserved, RES0.
BinaryPoint
2
0
2:0
The value of this field controls how the 8-bit interrupt priority field is split into a group priority field, that determines interrupt preemption, and a subpriority field. This is done as follows:
Binary point valueGroup priority fieldSubpriority fieldField with binary point
0[7:1][0]ggggggg.s
1[7:2][1:0]gggggg.ss
2[7:3][2:0]ggggg.sss
3[7:4][3:0]gggg.ssss
4[7:5][4:0]ggg.sssss
5[7:6][5:0]gg.ssssss
6[7][6:0]g.sssssss
7No preemption[7:0].ssssssss
AU
The minimum binary point value is derived from the number of implemented priority bits. The number of priority bits is IMPLEMENTATION DEFINED, and reported by ICC_CTLR.PRIbits and ICC_MCTLR.PRIbits.
An attempt to program the binary point field to a value less than the minimum value sets the field to the minimum value. On a reset, the binary point field is set to the minimum supported value.
MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}
if !(IsFeatureImplemented(FEAT_AA32EL1) && IsFeatureImplemented(FEAT_GICv3)) then
Undefined();
elsif PSTATE.EL == EL0 then
Undefined();
elsif PSTATE.EL == EL1 then
if HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
Undefined();
elsif HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR().FIQ == '1' then
Undefined();
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T12 == '1' then
AArch64_AArch32SystemAccessTrap(EL2, 0x03);
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T12 == '1' then
AArch32_TakeHypTrapException(0x03);
elsif ICC_SRE().SRE == '0' then
Undefined();
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && ICH_HCR_EL2().TALL0 == '1' then
AArch64_AArch32SystemAccessTrap(EL2, 0x03);
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && ICH_HCR().TALL0 == '1' then
AArch32_TakeHypTrapException(0x03);
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HCR_EL2().FMO == '1' then
R(t) = ICV_BPR0();
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HCR().FMO == '1' then
R(t) = ICV_BPR0();
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch64_AArch32SystemAccessTrap(EL3, 0x03);
end;
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch32_TakeMonitorTrapException();
end;
else
R(t) = ICC_BPR0();
end;
elsif PSTATE.EL == EL2 then
if HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
Undefined();
elsif HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && SCR().FIQ == '1' then
Undefined();
elsif ICC_HSRE().SRE == '0' then
Undefined();
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch64_AArch32SystemAccessTrap(EL3, 0x03);
end;
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && SCR().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch32_TakeMonitorTrapException();
end;
else
R(t) = ICC_BPR0();
end;
elsif PSTATE.EL == EL3 then
if ICC_MSRE().SRE == '0' then
Undefined();
else
R(t) = ICC_BPR0();
end;
end;
MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}
if !(IsFeatureImplemented(FEAT_AA32EL1) && IsFeatureImplemented(FEAT_GICv3)) then
Undefined();
elsif PSTATE.EL == EL0 then
Undefined();
elsif PSTATE.EL == EL1 then
if HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
Undefined();
elsif HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR().FIQ == '1' then
Undefined();
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HSTR_EL2().T12 == '1' then
AArch64_AArch32SystemAccessTrap(EL2, 0x03);
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HSTR().T12 == '1' then
AArch32_TakeHypTrapException(0x03);
elsif ICC_SRE().SRE == '0' then
Undefined();
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && ICH_HCR_EL2().TALL0 == '1' then
AArch64_AArch32SystemAccessTrap(EL2, 0x03);
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && ICH_HCR().TALL0 == '1' then
AArch32_TakeHypTrapException(0x03);
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA64EL2) && !ELUsingAArch32(EL2) && HCR_EL2().FMO == '1' then
ICV_BPR0() = R(t);
elsif EL2Enabled() && IsFeatureImplemented(FEAT_AA32EL2) && ELUsingAArch32(EL2) && HCR().FMO == '1' then
ICV_BPR0() = R(t);
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch64_AArch32SystemAccessTrap(EL3, 0x03);
end;
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch32_TakeMonitorTrapException();
end;
else
ICC_BPR0() = R(t);
end;
elsif PSTATE.EL == EL2 then
if HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
Undefined();
elsif HaveEL(EL3) && EL3SDDUndefPriority() && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && SCR().FIQ == '1' then
Undefined();
elsif ICC_HSRE().SRE == '0' then
Undefined();
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA64EL3) && !ELUsingAArch32(EL3) && SCR_EL3().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch64_AArch32SystemAccessTrap(EL3, 0x03);
end;
elsif HaveEL(EL3) && IsFeatureImplemented(FEAT_AA32EL3) && ELUsingAArch32(EL3) && SCR().FIQ == '1' then
if EL3SDDUndef() then
Undefined();
else
AArch32_TakeMonitorTrapException();
end;
else
ICC_BPR0() = R(t);
end;
elsif PSTATE.EL == EL3 then
if ICC_MSRE().SRE == '0' then
Undefined();
else
ICC_BPR0() = R(t);
end;
end;
2026-03-26 20:27:25
2026-03_rel