The ID_DFR1 characteristics are:
Provides top level information about the debug system in AArch32.
For general information about the interpretation of the ID registers, see 'Principles of the ID scheme for fields in ID registers'.
AArch32 System register ID_DFR1 bits [31:0] are architecturally mapped to AArch64 System register ID_DFR1_EL1[31:0].
This register is present only when EL1 is capable of using AArch32. Otherwise, direct accesses to ID_DFR1 are UNDEFINED.
Prior to the introduction of the features described by this register, this register was unnamed and reserved, RES0 from EL1, EL2, and EL3.
ID_DFR1 is a 32-bit register.
| 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 | HPMN0 | MTPMU | |||||||||||||||||||||||||||||
Reserved, RES0.
Zero PMU event counters for a Guest operating system.
The value of this field is an IMPLEMENTATION DEFINED choice of:
| HPMN0 | Meaning |
|---|---|
| 0b0000 |
Setting HDCR.HPMN to zero has CONSTRAINED UNPREDICTABLE behavior. |
| 0b0001 |
Setting HDCR.HPMN to zero has defined behavior. |
All other values are reserved.
If FEAT_PMUv3 is not implemented, FEAT_FGT is not implemented, or EL2 is not implemented, the only permitted value is 0b0000.
FEAT_HPMN0 implements the functionality identified by the value 0b0001.
From Armv8.8, in an implementation that includes FEAT_PMUv3, FEAT_FGT, and EL2, the value 0b0000 is not permitted.
Access to this field is RO.
Multi-threaded PMU extension.
The value of this field is an IMPLEMENTATION DEFINED choice of:
| MTPMU | Meaning |
|---|---|
| 0b0000 |
FEAT_MTPMU not implemented. If FEAT_PMUv3 is implemented, it is IMPLEMENTATION DEFINED whether PMEVTYPER<n>.MT are read/write or RES0. |
| 0b0001 |
FEAT_MTPMU and FEAT_PMUv3 implemented. PMEVTYPER<n>.MT are read/write. When FEAT_MTPMU is disabled, the Effective values of PMEVTYPER<n>.MT are 0. |
| 0b1111 |
FEAT_MTPMU not implemented. If FEAT_PMUv3 is implemented, PMEVTYPER<n>.MT are RES0. |
All other values are reserved.
FEAT_MTPMU implements the functionality identified by the value 0b0001.
From Armv8.6, in an implementation that includes FEAT_PMUv3, the value 0b0000 is not permitted.
In an implementation that does not include FEAT_PMUv3, the value 0b0001 is not permitted.
Access to this field is RO.
Accesses to this register use the following encodings in the System register encoding space:
| coproc | opc1 | CRn | CRm | opc2 |
|---|---|---|---|---|
| 0b1111 | 0b000 | 0b0000 | 0b0011 | 0b101 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T0 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T0 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && (IsFeatureImplemented(FEAT_FGT) || !IsZero(ID_DFR1) || boolean IMPLEMENTATION_DEFINED "ID_DFR1 trapped by HCR_EL2.TID3") && HCR_EL2.TID3 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && (IsFeatureImplemented(FEAT_FGT) || !IsZero(ID_DFR1) || boolean IMPLEMENTATION_DEFINED "ID_DFR1 trapped by HCR.TID3") && HCR.TID3 == '1' then AArch32.TakeHypTrapException(0x03); else R[t] = ID_DFR1; elsif PSTATE.EL == EL2 then R[t] = ID_DFR1; elsif PSTATE.EL == EL3 then R[t] = ID_DFR1;
26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6
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