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# ICH_ELRSR, Interrupt Controller Empty List Register Status Register

The ICH_ELRSR characteristics are:

## Purpose

Indicates which List registers contain valid interrupts.

## Configuration

AArch32 System register ICH_ELRSR bits [31:0] are architecturally mapped to AArch64 System register ICH_ELRSR_EL2[31:0] .

If EL2 is not implemented, this register is RES0 from EL3.

## Attributes

ICH_ELRSR is a 32-bit register.

## Field descriptions

The ICH_ELRSR 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
RES0 | Status<n>, bit [n], for n = 0 to 15

#### Bits [31:16]

Reserved, RES0.

#### Status<n>, bit [n], for n = 0 to 15

Status bit for List register <n>, ICH_LR<n>:

Status<n> | Meaning
--- | ---
0b0 | List register ICH_LR<n>, if implemented, contains a valid interrupt. Using this List register can result in overwriting a valid interrupt.
0b1 | List register ICH_LR<n> does not contain a valid interrupt. The List register is empty and can be used without overwriting a valid interrupt or losing an EOI maintenance interrupt.

For any List register <n>, the corresponding status bit is set to 1 if ICH_LRC<n>.State is 0b00 and either ICH_LRC<n>.HW is 1 or ICH_LRC<n>.EOI (bit [9]) is 0.

## Accessing the ICH_ELRSR

Accesses to this register use the following encodings:

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

coproc | opc1 | CRn | CRm | opc2
--- | --- | --- | --- | ---
0b1111 | 0b100 | 0b1100 | 0b1011 | 0b101

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); else UNDEFINED; elsif PSTATE.EL == EL2 then if ICC_HSRE.SRE == '0' then UNDEFINED; else return ICH_ELRSR; elsif PSTATE.EL == EL3 then if ICC_MSRE.SRE == '0' then UNDEFINED; else return ICH_ELRSR;

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

15/04/2019 16:47; 8c23526ba8a13a72aada4137daf3e3977b49036e

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