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# ICC_AP0R<n>, Interrupt Controller Active Priorities Group 0 Registers, n = 0 - 3

The ICC_AP0R<n> characteristics are:

## Purpose

Provides information about Group 0 active priorities.

## Configuration

AArch32 System register ICC_AP0R<n> bits [31:0] are architecturally mapped to AArch64 System register ICC_AP0R<n>_EL1[31:0] .

Some or all RW fields of this register have defined reset values. These apply only if the PE resets into an Exception level that is using AArch32. Otherwise, RW fields in this register reset to architecturally UNKNOWN values.

## Attributes

ICC_AP0R<n> is a 32-bit register.

## Field descriptions

The ICC_AP0R<n> bit assignments are:

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
IMPLEMENTATION DEFINED

#### IMPLEMENTATION DEFINED, bits [31:0]

IMPLEMENTATION DEFINED.

This field resets to 0.

The contents of these registers are IMPLEMENTATION DEFINED with the one architectural requirement that the value 0x00000000 is consistent with no interrupts being active.

## Accessing the ICC_AP0R<n>

Writing to these registers with any value other than the last read value of the register (or 0x00000000 when there are no Group 0 active priorities) might result in UNPREDICTABLE behavior of the interrupt prioritization system, causing:

- Interrupts that should preempt execution to not preempt execution.
- Interrupts that should not preempt execution to preempt execution.

ICC_AP0R1 is only implemented in implementations that support 6 or more bits of preemption. ICC_AP0R2 and ICC_AP0R3 are only implemented in implementations that support 7 bits of preemption. Unimplemented registers are UNDEFINED.

Note

The number of bits of preemption is indicated by ICH_VTR.PREbits.

Writing to the active priority registers in any order other than the following order will result in UNPREDICTABLE behavior:

- ICC_AP0R<n>.
- Secure ICC_AP1R<n>.
- Non-secure ICC_AP1R<n>.

Accesses to this register use the following encodings:

#### MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coproc | opc1 | CRn | CRm | opc2
--- | --- | --- | --- | ---
0b1111 | 0b000 | 0b1100 | 0b1000 | 0b1[n:1:0]

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then AArch32.TakeHypTrapException(0x03); elsif ICC_SRE.SRE == '0' then UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && ICH_HCR_EL2.TALL0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TALL0 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.FMO == '1' then return ICV_AP0R[UInt(opc2<1:0>)]; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR.FMO == '1' then return ICV_AP0R[UInt(opc2<1:0>)]; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else return ICC_AP0R[UInt(opc2<1:0>)]; elsif PSTATE.EL == EL2 then if ICC_HSRE.SRE == '0' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else return ICC_AP0R[UInt(opc2<1:0>)]; elsif PSTATE.EL == EL3 then if ICC_MSRE.SRE == '0' then UNDEFINED; else return ICC_AP0R[UInt(opc2<1:0>)];

#### MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coproc | opc1 | CRn | CRm | opc2
--- | --- | --- | --- | ---
0b1111 | 0b000 | 0b1100 | 0b1000 | 0b1[n:1:0]

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then AArch32.TakeHypTrapException(0x03); elsif ICC_SRE.SRE == '0' then UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && ICH_HCR_EL2.TALL0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && ICH_HCR.TALL0 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.FMO == '1' then ICV_AP0R[UInt(opc2<1:0>)] = R[t]; elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR.FMO == '1' then ICV_AP0R[UInt(opc2<1:0>)] = R[t]; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && PSTATE.M != M32_Monitor && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else ICC_AP0R[UInt(opc2<1:0>)] = R[t]; elsif PSTATE.EL == EL2 then if ICC_HSRE.SRE == '0' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && SCR_EL3.FIQ == '1' then AArch64.AArch32SystemAccessTrap(EL3, 0x03); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && SCR.FIQ == '1' then AArch32.TakeMonitorTrapException(); else ICC_AP0R[UInt(opc2<1:0>)] = R[t]; elsif PSTATE.EL == EL3 then if ICC_MSRE.SRE == '0' then UNDEFINED; else ICC_AP0R[UInt(opc2<1:0>)] = R[t];

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

27/03/2019 21:59; e5e4db499bf9867a4b93324c4dbac985d3da9376

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