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# RMR, Reset Management Register

The RMR characteristics are:

## Purpose

If EL1 or EL3 is the highest implemented Exception level and this register is implemented:

- A write to the register at the highest implemented Exception level can request a Warm reset.
- If the highest implemented Exception level can use AArch32 and AArch64, this register specifies the Execution state that the PE boots into on a Warm reset.

## Configuration

AArch32 System register RMR bits [31:0] are architecturally mapped to AArch64 System register RMR_EL1[31:0] when IsHighestEL(EL1).

AArch32 System register RMR bits [31:0] are architecturally mapped to AArch64 System register RMR_EL3[31:0] when HaveEL(EL3).

Only implemented if EL1 or EL3 is the highest implemented Exception level. In this case:

- If the highest implemented Exception level can use AArch32 and AArch64 then this register must be implemented.
- If the highest implemented Exception level cannot use AArch64 then it is IMPLEMENTATION DEFINED whether the register is implemented.

See the field descriptions for the reset values. These apply whenever the register is implemented.

## Attributes

RMR is a 32-bit register.

## Field descriptions

The RMR 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 | RR | AA64

#### Bits [31:2]

Reserved, RES0.

#### RR, bit [1]

Reset Request. Setting this bit to 1 requests a Warm reset.

This field resets to 0.

#### AA64, bit [0]

When the highest implemented Exception level can use AArch64, determines which Execution state the PE boots into after a Warm reset:

AA64 | Meaning
--- | ---
0b0 | AArch32.
0b1 | AArch64.

On coming out of the Warm reset, execution starts at the IMPLEMENTATION DEFINED reset vector address of the specified Execution state.

If the highest implemented Exception level cannot use AArch64 this bit is RAZ/WI.

When implemented as a RW field, this field resets to 0 on a Cold reset.

## Accessing the RMR

When EL3 is implemented, Arm deprecates accessing this register from any PE mode other than Monitor mode.

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 | 0b0000 | 0b010

if PSTATE.EL IN {EL3, EL1} && IsHighestEL(PSTATE.EL) then return RMR; else UNDEFINED;

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

coproc | opc1 | CRn | CRm | opc2
--- | --- | --- | --- | ---
0b1111 | 0b000 | 0b1100 | 0b0000 | 0b010

if PSTATE.EL IN {EL3, EL1} && IsHighestEL(PSTATE.EL) then RMR = R[t]; else UNDEFINED;

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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