DBGDIDR, Debug ID Register

The DBGDIDR characteristics are:

Purpose

Specifies which version of the Debug architecture is implemented, and some features of the debug implementation.

Configuration

This register is present only when AArch32 is supported. Otherwise, direct accesses to DBGDIDR are UNDEFINED.

If EL1 cannot use AArch32 then the implementation of this register is OPTIONAL and deprecated.

Attributes

DBGDIDR is a 32-bit register.

Field descriptions

313029282726252423222120191817161514131211109876543210
WRPsBRPsCTX_CMPsVersionRES1nSUHD_impRES0SE_impRES0

WRPs, bits [31:28]

The number of watchpoints implemented, minus 1.

Permitted values of this field are from 0b0001 for 2 implemented watchpoints, to 0b1111 for 16 implemented watchpoints.

The value of 0b0000 is reserved.

If AArch64 is implemented, this field has the same value as ID_AA64DFR0_EL1.WRPs.

BRPs, bits [27:24]

The number of breakpoints implemented, minus 1.

Permitted values of this field are from 0b0001 for 2 implemented breakpoint, to 0b1111 for 16 implemented breakpoints.

The value of 0b0000 is reserved.

If AArch64 is implemented, this field has the same value as ID_AA64DFR0_EL1.BRPs.

CTX_CMPs, bits [23:20]

The number of breakpoints that can be used for Context matching, minus 1.

Permitted values of this field are from 0b0000 for 1 Context matching breakpoint, to 0b1111 for 16 Context matching breakpoints.

The Context matching breakpoints must be the highest addressed breakpoints. For example, if six breakpoints are implemented and two are Context matching breakpoints, they must be breakpoints 4 and 5.

If AArch64 is implemented, this field has the same value as ID_AA64DFR0_EL1.CTX_CMPs.

Version, bits [19:16]

Debug architecture version. Indicates presence of Armv8 debug architecture. Defined values are:

VersionMeaning
0b0000

Not supported.

0b0001

Armv6, v6 Debug architecture, with System registers access.

0b0010

Armv6, v6.1 Debug architecture, with System registers access.

0b0011

Armv7, v7 Debug architecture, with only baseline System registers.

0b0100

Armv7, v7 Debug architecture, with all System registers implemented.

0b0101

Armv7, v7.1 Debug architecture, with System registers access.

0b0110

Armv8 debug architecture.

0b0111

Armv8 debug architecture with Virtualization Host Extensions.

0b1000

Armv8.2 debug architecture, FEAT_Debugv8p2.

0b1001

Armv8.4 debug architecture, FEAT_Debugv8p4.

0b1010

Armv8.8 debug architecture, FEAT_Debugv8p8.

All other values are reserved.

The values 0b0000, 0b0001, 0b0010, 0b0011, 0b0100, and 0b0101 are not permitted in Armv8.

FEAT_VHE adds the functionality identified by the value 0b0111.

FEAT_Debugv8p2 adds the functionality identified by the value 0b1000.

FEAT_Debugv8p4 adds the functionality identified by the value 0b1001.

FEAT_Debugv8p8 adds the functionality identified by the value 0b1010.

From Armv8.1, when FEAT_VHE is implemented the value 0b0110 is not permitted.

From Armv8.2, the values 0b0110 and 0b0111 are not permitted.

From Armv8.4, the value 0b1000 is not permitted.

From Armv8.8, the value 0b1001 is not permitted.

Bit [15]

Reserved, RES1.

nSUHD_imp, bit [14]

Previously indicated that Secure User Halting Debug is not implemented.

The value of this bit must match the value of the SE_imp bit.

Bit [13]

Reserved, RES0.

SE_imp, bit [12]

EL3 implemented. The meanings of the values of this bit are:

SE_impMeaning
0b0

EL3 not implemented.

0b1

EL3 implemented.

The value of this bit must match the value of the nSUHD_imp bit.

Bits [11:0]

Reserved, RES0.

Accessing DBGDIDR

Arm deprecates any access to this register from EL0.

Accesses to this register use the following encodings in the System register encoding space:

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

coprocopc1CRnCRmopc2
0b11100b0000b00000b00000b000

if Halted() && ConstrainUnpredictableBool(Unpredictable_IGNORETRAPINDEBUG) then R[t] = DBGDIDR; elsif PSTATE.EL == EL0 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then UNDEFINED; elsif !ELUsingAArch32(EL1) && MDSCR_EL1.TDCC == '1' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x05); else AArch64.AArch32SystemAccessTrap(EL1, 0x05); elsif ELUsingAArch32(EL1) && DBGDSCRext.UDCCdis == '1' then if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x05); elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then AArch32.TakeHypTrapException(0x00); else UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && (HCR_EL2.TGE == '1' || MDCR_EL2.<TDE,TDA> != '00') then AArch64.AArch32SystemAccessTrap(EL2, 0x05); elsif EL2Enabled() && ELUsingAArch32(EL2) && (HCR.TGE == '1' || HDCR.<TDE,TDA> != '00') then AArch32.TakeHypTrapException(0x05); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x05); else R[t] = DBGDIDR; elsif PSTATE.EL == EL1 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then UNDEFINED; elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDA> != '00' then AArch64.AArch32SystemAccessTrap(EL2, 0x05); elsif EL2Enabled() && ELUsingAArch32(EL2) && HDCR.<TDE,TDA> != '00' then AArch32.TakeHypTrapException(0x05); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x05); else R[t] = DBGDIDR; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x05); else R[t] = DBGDIDR; elsif PSTATE.EL == EL3 then R[t] = DBGDIDR;


05/07/2022 17:08; b0421fa9a8865165f9b91af9b4a566111f866305

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