The HRMR characteristics are:
If EL2 is the highest implemented Exception level and this register is implemented:
This register is part of:
AArch32 System register HRMR is architecturally mapped to AArch64 System register RMR_EL2.
Only implemented if EL2 is the highest implemented Exception level. In this case:
See the field descriptions for the reset values. These apply whenever the register is implemented.
HRMR is a 32-bit register.
The HRMR 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 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | RR | AA64 |
Reserved, RES0.
Reset Request. Setting this bit to 1 requests a Warm reset.
This field resets to 0 on a Warm or Cold reset.
When EL2 can use AArch64, determines which Execution state the PE boots into after a Warm reset:
AA64 | Meaning |
---|---|
0 |
AArch32. |
1 |
AArch64. |
On coming out of the Warm reset, execution starts at the IMPLEMENTATION DEFINED reset vector address of the specified Execution state.
If EL2 cannot use AArch64 this bit is RAZ/WI.
When implemented as a RW field, this field resets to 0 on a Cold reset.
This register can be read using MRC with the following syntax:
MRC <syntax>
This register can be written using MCR with the following syntax:
MCR <syntax>
This syntax uses the following encoding in the System instruction encoding space:
<syntax> | opc1 | opc2 | CRn | coproc | CRm |
---|---|---|---|---|---|
p15, 4, <Rt>, c12, c0, 2 | 100 | 010 | 1100 | 1111 | 0000 |
The register is accessible as follows:
Configuration | Control | Accessibility | |||||
---|---|---|---|---|---|---|---|
E2H | TGE | NS | EL0 | EL1 | EL2 | EL3 | |
EL2 is the highest implemented Exception level | x | 0 | 1 | - | - | RW | n/a |
EL2 is the highest implemented Exception level | x | 1 | 1 | - | n/a | RW | n/a |
This table applies to all instructions that can access this register.
When HRMR is not implemented, the encoding for this register is UNDEFINED.
For a description of the prioritization of any generated exceptions, see section G1.11.2 (Exception priority order) in the ARM® Architecture Reference Manual, ARMv8, for ARMv8-A architecture profile for exceptions taken to AArch32 state, and section D1.13.2 (Synchronous exception prioritization) for exceptions taken to AArch64 state. Subject to the prioritization rules, the following traps and enables are applicable when accessing this register.
When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 && HCR_EL2.E2H==0 :
If HSTR_EL2.T12==1, Non-secure accesses to this register from EL1 are trapped to EL2.
When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 && HCR_EL2.E2H==1 && HCR_EL2.TGE==0 :
If HSTR_EL2.T12==1, Non-secure accesses to this register from EL1 are trapped to EL2.
When EL2 is implemented and is using AArch32 and SCR_EL3.NS==1 :
If HSTR.T12==1, Non-secure accesses to this register from EL1 are trapped to Hyp mode.
18/04/2017 17:00
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