Re: [RFC PATCH v7 14/18] target/arm/cpu-idregs.h.inc: Generate reserved fields

> On 26 Jul 2026, at 8:59 PM, Eric Auger <[email protected]> wrote:
> 
> !-------------------------------------------------------------------|
>  CAUTION: External Email
> 
> |-------------------------------------------------------------------!
> 
> Extract reserved fields: RES0, RES1, RAZ, ...
> 
> Signed-off-by: Eric Auger <[email protected]>
> ---
> target/arm/cpu-idregs.h.inc                   | 69 ++++++++++++++-
> .../update-aarch64-cpu-sysreg-properties.py   | 83 +++++++++++++++----
> 2 files changed, 136 insertions(+), 16 deletions(-)
> 
> diff --git a/target/arm/cpu-idregs.h.inc b/target/arm/cpu-idregs.h.inc
> index 1c8b26133b..5fdc84237c 100644
> --- a/target/arm/cpu-idregs.h.inc
> +++ b/target/arm/cpu-idregs.h.inc
> @@ -15,16 +15,20 @@ IDREG_START(AIDR_EL1)
> IDREG_END(AIDR_EL1)
> 
> IDREG_START(CCSIDR2_EL1)
> +    IDREG_FIELD(CCSIDR2_EL1, RES0, 24, 40)
>     IDREG_FIELD(CCSIDR2_EL1, NumSets, 0, 24)
> IDREG_END(CCSIDR2_EL1)
> 
> IDREG_START(CCSIDR_EL1)
> +    IDREG_FIELD(CCSIDR_EL1, RES0, 56, 8)
>     IDREG_FIELD(CCSIDR_EL1, NumSets, 32, 24)
> +    IDREG_FIELD(CCSIDR_EL1, RES0, 24, 8)
>     IDREG_FIELD(CCSIDR_EL1, Associativity, 3, 21)
>     IDREG_FIELD(CCSIDR_EL1, LineSize, 0, 3)
> IDREG_END(CCSIDR_EL1)
> 
> IDREG_START(CLIDR_EL1)
> +    IDREG_FIELD(CLIDR_EL1, RES0, 47, 17)
>     IDREG_FIELD(CLIDR_EL1, Ttype7, 45, 2)
>     IDREG_FIELD(CLIDR_EL1, Ttype6, 43, 2)
>     IDREG_FIELD(CLIDR_EL1, Ttype5, 41, 2)
> @@ -55,7 +59,10 @@ IDREG_START(CLIDR_EL1)
> IDREG_END(CLIDR_EL1)
> 
> IDREG_START(CTR_EL0)
> +    IDREG_FIELD(CTR_EL0, RES0, 38, 26)
>     IDREG_FIELD(CTR_EL0, TminLine, 32, 6)
> +    IDREG_FIELD(CTR_EL0, RES1, 31, 1)
> +    IDREG_FIELD(CTR_EL0, RES0, 30, 1)
>     IDREG_FIELD_START(CTR_EL0, DIC, 29, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -73,23 +80,28 @@ IDREG_START(CTR_EL0)
>         IDREG_FIELD_ARCH_VAL(2)
>         IDREG_FIELD_ARCH_VAL(3)
>     IDREG_FIELD_END(CTR_EL0, L1Ip)
> +    IDREG_FIELD(CTR_EL0, RES0, 4, 10)
>     IDREG_FIELD(CTR_EL0, IminLine, 0, 4)
> IDREG_END(CTR_EL0)
> 
> IDREG_START(DCZID_EL0)
> +    IDREG_FIELD(DCZID_EL0, RES0, 9, 55)
>     IDREG_FIELD(DCZID_EL0, TBS, 5, 4)
>     IDREG_FIELD(DCZID_EL0, DZP, 4, 1)
>     IDREG_FIELD(DCZID_EL0, BS, 0, 4)
> IDREG_END(DCZID_EL0)
> 
> IDREG_START(GMID_EL1)
> +    IDREG_FIELD(GMID_EL1, RES0, 4, 60)
>     IDREG_FIELD(GMID_EL1, BS, 0, 4)
> IDREG_END(GMID_EL1)
> 
> IDREG_START(ID_AA64AFR0_EL1)
> +    IDREG_FIELD(ID_AA64AFR0_EL1, RES0, 32, 32)
> IDREG_END(ID_AA64AFR0_EL1)
> 
> IDREG_START(ID_AA64AFR1_EL1)
> +    IDREG_FIELD(ID_AA64AFR1_EL1, RES0, 0, 64)
> IDREG_END(ID_AA64AFR1_EL1)
> 
> IDREG_START(ID_AA64DFR0_EL1)
> @@ -136,6 +148,7 @@ IDREG_START(ID_AA64DFR0_EL1)
>     IDREG_FIELD_START(ID_AA64DFR0_EL1, CTX_CMPs, 28, 4)
>         IDREG_FIELD_ARCH_VAL(15)
>     IDREG_FIELD_END(ID_AA64DFR0_EL1, CTX_CMPs)
> +    IDREG_FIELD(ID_AA64DFR0_EL1, RES0, 24, 4)
>     IDREG_FIELD(ID_AA64DFR0_EL1, WRPs, 20, 4)
>     IDREG_FIELD_START(ID_AA64DFR0_EL1, PMSS, 16, 4)
>         IDREG_FIELD_ARCH_VAL(0)
> @@ -209,6 +222,7 @@ IDREG_START(ID_AA64DFR1_EL1)
> IDREG_END(ID_AA64DFR1_EL1)
> 
> IDREG_START(ID_AA64DFR2_EL1)
> +    IDREG_FIELD(ID_AA64DFR2_EL1, RES0, 28, 36)
>     IDREG_FIELD_START(ID_AA64DFR2_EL1, TRBE_EXC, 24, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -221,6 +235,7 @@ IDREG_START(ID_AA64DFR2_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64DFR2_EL1, SPE_EXC)
> +    IDREG_FIELD(ID_AA64DFR2_EL1, RES0, 8, 8)
>     IDREG_FIELD_START(ID_AA64DFR2_EL1, BWE, 4, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -233,6 +248,7 @@ IDREG_START(ID_AA64DFR2_EL1)
> IDREG_END(ID_AA64DFR2_EL1)
> 
> IDREG_START(ID_AA64FPFR0_EL1)
> +    IDREG_FIELD(ID_AA64FPFR0_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_AA64FPFR0_EL1, F8CVT, 31, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -257,10 +273,13 @@ IDREG_START(ID_AA64FPFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64FPFR0_EL1, F8MM4)
> +    IDREG_FIELD(ID_AA64FPFR0_EL1, RES0, 16, 10)
>     IDREG_FIELD_START(ID_AA64FPFR0_EL1, F16MM2, 15, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64FPFR0_EL1, F16MM2)
> +    IDREG_FIELD(ID_AA64FPFR0_EL1, RES0, 8, 7)
> +    IDREG_FIELD(ID_AA64FPFR0_EL1, RAZ, 2, 6)
>     IDREG_FIELD_START(ID_AA64FPFR0_EL1, F8E4M3, 1, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -312,6 +331,7 @@ IDREG_START(ID_AA64ISAR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64ISAR0_EL1, RDM)
> +    IDREG_FIELD(ID_AA64ISAR0_EL1, RES0, 24, 4)
>     IDREG_FIELD_START(ID_AA64ISAR0_EL1, Atomic, 20, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(2)
> @@ -335,6 +355,7 @@ IDREG_START(ID_AA64ISAR0_EL1)
>         IDREG_FIELD_ARCH_VAL(1)
>         IDREG_FIELD_ARCH_VAL(2)
>     IDREG_FIELD_END(ID_AA64ISAR0_EL1, AES)
> +    IDREG_FIELD(ID_AA64ISAR0_EL1, RES0, 0, 4)
> IDREG_END(ID_AA64ISAR0_EL1)
> 
> IDREG_START(ID_AA64ISAR1_EL1)
> @@ -498,6 +519,7 @@ IDREG_START(ID_AA64ISAR2_EL1)
> IDREG_END(ID_AA64ISAR2_EL1)
> 
> IDREG_START(ID_AA64ISAR3_EL1)
> +    IDREG_FIELD(ID_AA64ISAR3_EL1, RES0, 48, 16)
>     IDREG_FIELD_START(ID_AA64ISAR3_EL1, LSCP, 44, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -561,6 +583,7 @@ IDREG_START(ID_AA64MMFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(1)
>         IDREG_FIELD_ARCH_VAL(2)
>     IDREG_FIELD_END(ID_AA64MMFR0_EL1, FGT)
> +    IDREG_FIELD(ID_AA64MMFR0_EL1, RES0, 48, 8)
>     IDREG_FIELD_START(ID_AA64MMFR0_EL1, ExS, 44, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -713,6 +736,7 @@ IDREG_START(ID_AA64MMFR2_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64MMFR2_EL1, TTL)
> +    IDREG_FIELD(ID_AA64MMFR2_EL1, RES0, 44, 4)
>     IDREG_FIELD_START(ID_AA64MMFR2_EL1, FWB, 40, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -778,6 +802,7 @@ IDREG_START(ID_AA64MMFR3_EL1)
>         IDREG_FIELD_ARCH_VAL(2)
>         IDREG_FIELD_ARCH_VAL(3)
>     IDREG_FIELD_END(ID_AA64MMFR3_EL1, SDERR)
> +    IDREG_FIELD(ID_AA64MMFR3_EL1, RES0, 48, 4)
>     IDREG_FIELD_START(ID_AA64MMFR3_EL1, ANERR, 44, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1031,6 +1056,7 @@ IDREG_START(ID_AA64PFR1_EL1)
>         IDREG_FIELD_ARCH_VAL(1)
>         IDREG_FIELD_ARCH_VAL(2)
>     IDREG_FIELD_END(ID_AA64PFR1_EL1, SME)
> +    IDREG_FIELD(ID_AA64PFR1_EL1, RES0, 20, 4)
>     IDREG_FIELD_START(ID_AA64PFR1_EL1, MPAM_frac, 16, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1058,6 +1084,7 @@ IDREG_START(ID_AA64PFR1_EL1)
> IDREG_END(ID_AA64PFR1_EL1)
> 
> IDREG_START(ID_AA64PFR2_EL1)
> +    IDREG_FIELD(ID_AA64PFR2_EL1, RES0, 48, 16)
>     IDREG_FIELD_START(ID_AA64PFR2_EL1, VMTETCL, 44, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1117,6 +1144,7 @@ IDREG_START(ID_AA64SMFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64SMFR0_EL1, FA64)
> +    IDREG_FIELD(ID_AA64SMFR0_EL1, RES0, 62, 1)
>     IDREG_FIELD_START(ID_AA64SMFR0_EL1, LUT6, 61, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1136,6 +1164,7 @@ IDREG_START(ID_AA64SMFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(15)
>     IDREG_FIELD_END(ID_AA64SMFR0_EL1, I16I64)
> +    IDREG_FIELD(ID_AA64SMFR0_EL1, RES0, 49, 3)
>     IDREG_FIELD_START(ID_AA64SMFR0_EL1, F64F64, 48, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1180,6 +1209,7 @@ IDREG_START(ID_AA64SMFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64SMFR0_EL1, F32F32)
> +    IDREG_FIELD(ID_AA64SMFR0_EL1, RES0, 31, 1)
>     IDREG_FIELD_START(ID_AA64SMFR0_EL1, SF8FMA, 30, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1192,6 +1222,7 @@ IDREG_START(ID_AA64SMFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64SMFR0_EL1, SF8DP2)
> +    IDREG_FIELD(ID_AA64SMFR0_EL1, RES0, 26, 2)
>     IDREG_FIELD_START(ID_AA64SMFR0_EL1, SBitPerm, 25, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1204,10 +1235,12 @@ IDREG_START(ID_AA64SMFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64SMFR0_EL1, SFEXPA)
> +    IDREG_FIELD(ID_AA64SMFR0_EL1, RES0, 17, 6)
>     IDREG_FIELD_START(ID_AA64SMFR0_EL1, STMOP, 16, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64SMFR0_EL1, STMOP)
> +    IDREG_FIELD(ID_AA64SMFR0_EL1, RES0, 1, 15)
>     IDREG_FIELD_START(ID_AA64SMFR0_EL1, SMOP4, 0, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1215,6 +1248,7 @@ IDREG_START(ID_AA64SMFR0_EL1)
> IDREG_END(ID_AA64SMFR0_EL1)
> 
> IDREG_START(ID_AA64ZFR0_EL1)
> +    IDREG_FIELD(ID_AA64ZFR0_EL1, RES0, 60, 4)
>     IDREG_FIELD_START(ID_AA64ZFR0_EL1, F64MM, 56, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1235,10 +1269,12 @@ IDREG_START(ID_AA64ZFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64ZFR0_EL1, SM4)
> +    IDREG_FIELD(ID_AA64ZFR0_EL1, RES0, 36, 4)
>     IDREG_FIELD_START(ID_AA64ZFR0_EL1, SHA3, 32, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64ZFR0_EL1, SHA3)
> +    IDREG_FIELD(ID_AA64ZFR0_EL1, RES0, 28, 4)
>     IDREG_FIELD_START(ID_AA64ZFR0_EL1, B16B16, 24, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1258,6 +1294,7 @@ IDREG_START(ID_AA64ZFR0_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_AA64ZFR0_EL1, EltPerm)
> +    IDREG_FIELD(ID_AA64ZFR0_EL1, RES0, 8, 4)
>     IDREG_FIELD_START(ID_AA64ZFR0_EL1, AES, 4, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1274,9 +1311,11 @@ IDREG_START(ID_AA64ZFR0_EL1)
> IDREG_END(ID_AA64ZFR0_EL1)
> 
> IDREG_START(ID_AFR0_EL1)
> +    IDREG_FIELD(ID_AFR0_EL1, RES0, 0, 64)
> IDREG_END(ID_AFR0_EL1)
> 
> IDREG_START(ID_DFR0_EL1)
> +    IDREG_FIELD(ID_DFR0_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_DFR0_EL1, TraceFilt, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1328,6 +1367,7 @@ IDREG_START(ID_DFR0_EL1)
> IDREG_END(ID_DFR0_EL1)
> 
> IDREG_START(ID_DFR1_EL1)
> +    IDREG_FIELD(ID_DFR1_EL1, RES0, 8, 56)
>     IDREG_FIELD_START(ID_DFR1_EL1, HPMN0, 4, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1340,6 +1380,7 @@ IDREG_START(ID_DFR1_EL1)
> IDREG_END(ID_DFR1_EL1)
> 
> IDREG_START(ID_ISAR0_EL1)
> +    IDREG_FIELD(ID_ISAR0_EL1, RES0, 28, 36)
>     IDREG_FIELD_START(ID_ISAR0_EL1, Divide, 24, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1375,6 +1416,7 @@ IDREG_START(ID_ISAR0_EL1)
> IDREG_END(ID_ISAR0_EL1)
> 
> IDREG_START(ID_ISAR1_EL1)
> +    IDREG_FIELD(ID_ISAR1_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_ISAR1_EL1, Jazelle, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1413,6 +1455,7 @@ IDREG_START(ID_ISAR1_EL1)
> IDREG_END(ID_ISAR1_EL1)
> 
> IDREG_START(ID_ISAR2_EL1)
> +    IDREG_FIELD(ID_ISAR2_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_ISAR2_EL1, Reversal, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1458,6 +1501,7 @@ IDREG_START(ID_ISAR2_EL1)
> IDREG_END(ID_ISAR2_EL1)
> 
> IDREG_START(ID_ISAR3_EL1)
> +    IDREG_FIELD(ID_ISAR3_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_ISAR3_EL1, T32EE, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1495,6 +1539,7 @@ IDREG_START(ID_ISAR3_EL1)
> IDREG_END(ID_ISAR3_EL1)
> 
> IDREG_START(ID_ISAR4_EL1)
> +    IDREG_FIELD(ID_ISAR4_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_ISAR4_EL1, SWP_frac, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1519,12 +1564,12 @@ IDREG_START(ID_ISAR4_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_ISAR4_EL1, Writeback)
> -    IDREG_FIELD_START(ID_ISAR4_EL1, WithShifts, 4, 4)
> +    IDREG_FIELD_START(ID_ISAR4_EL1, WI, 4, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>         IDREG_FIELD_ARCH_VAL(3)
>         IDREG_FIELD_ARCH_VAL(4)
> -    IDREG_FIELD_END(ID_ISAR4_EL1, WithShifts)
> +    IDREG_FIELD_END(ID_ISAR4_EL1, WI)

unintended change?

This is the problem with relying solely on AARCHMRS?
Imagine a named model/management stack using _WithShifts
prop, and suddenly it no longer exists.

>     IDREG_FIELD_START(ID_ISAR4_EL1, Unpriv, 0, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1533,6 +1578,7 @@ IDREG_START(ID_ISAR4_EL1)
> IDREG_END(ID_ISAR4_EL1)
> 
> IDREG_START(ID_ISAR5_EL1)
> +    IDREG_FIELD(ID_ISAR5_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_ISAR5_EL1, VCMA, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1541,6 +1587,7 @@ IDREG_START(ID_ISAR5_EL1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(ID_ISAR5_EL1, RDM)
> +    IDREG_FIELD(ID_ISAR5_EL1, RES0, 20, 4)
>     IDREG_FIELD_START(ID_ISAR5_EL1, CRC32, 16, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1565,6 +1612,7 @@ IDREG_START(ID_ISAR5_EL1)
> IDREG_END(ID_ISAR5_EL1)
> 
> IDREG_START(ID_ISAR6_EL1)
> +    IDREG_FIELD(ID_ISAR6_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_ISAR6_EL1, CLRBHB, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1601,6 +1649,7 @@ IDREG_START(ID_ISAR6_EL1)
> IDREG_END(ID_ISAR6_EL1)
> 
> IDREG_START(ID_MMFR0_EL1)
> +    IDREG_FIELD(ID_MMFR0_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_MMFR0_EL1, InnerShr, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1647,6 +1696,7 @@ IDREG_START(ID_MMFR0_EL1)
> IDREG_END(ID_MMFR0_EL1)
> 
> IDREG_START(ID_MMFR1_EL1)
> +    IDREG_FIELD(ID_MMFR1_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_MMFR1_EL1, BPred, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1695,6 +1745,7 @@ IDREG_START(ID_MMFR1_EL1)
> IDREG_END(ID_MMFR1_EL1)
> 
> IDREG_START(ID_MMFR2_EL1)
> +    IDREG_FIELD(ID_MMFR2_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_MMFR2_EL1, HWAccFlg, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1733,6 +1784,7 @@ IDREG_START(ID_MMFR2_EL1)
> IDREG_END(ID_MMFR2_EL1)
> 
> IDREG_START(ID_MMFR3_EL1)
> +    IDREG_FIELD(ID_MMFR3_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_MMFR3_EL1, Supersec, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(15)
> @@ -1772,6 +1824,7 @@ IDREG_START(ID_MMFR3_EL1)
> IDREG_END(ID_MMFR3_EL1)
> 
> IDREG_START(ID_MMFR4_EL1)
> +    IDREG_FIELD(ID_MMFR4_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_MMFR4_EL1, EVT, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1809,6 +1862,7 @@ IDREG_START(ID_MMFR4_EL1)
> IDREG_END(ID_MMFR4_EL1)
> 
> IDREG_START(ID_MMFR5_EL1)
> +    IDREG_FIELD(ID_MMFR5_EL1, RES0, 8, 56)
>     IDREG_FIELD_START(ID_MMFR5_EL1, nTLBPA, 4, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1822,6 +1876,7 @@ IDREG_START(ID_MMFR5_EL1)
> IDREG_END(ID_MMFR5_EL1)
> 
> IDREG_START(ID_PFR0_EL1)
> +    IDREG_FIELD(ID_PFR0_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_PFR0_EL1, RAS, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1863,6 +1918,7 @@ IDREG_START(ID_PFR0_EL1)
> IDREG_END(ID_PFR0_EL1)
> 
> IDREG_START(ID_PFR1_EL1)
> +    IDREG_FIELD(ID_PFR1_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(ID_PFR1_EL1, GIC, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1902,6 +1958,7 @@ IDREG_START(ID_PFR1_EL1)
> IDREG_END(ID_PFR1_EL1)
> 
> IDREG_START(ID_PFR2_EL1)
> +    IDREG_FIELD(ID_PFR2_EL1, RES0, 12, 52)
>     IDREG_FIELD_START(ID_PFR2_EL1, RAS_frac, 8, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1949,11 +2006,14 @@ IDREG_START(MIDR_EL1)
> IDREG_END(MIDR_EL1)
> 
> IDREG_START(MPIDR_EL1)
> +    IDREG_FIELD(MPIDR_EL1, RES0, 40, 24)
>     IDREG_FIELD(MPIDR_EL1, Aff3, 32, 8)
> +    IDREG_FIELD(MPIDR_EL1, RES1, 31, 1)
>     IDREG_FIELD_START(MPIDR_EL1, U, 30, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
>     IDREG_FIELD_END(MPIDR_EL1, U)
> +    IDREG_FIELD(MPIDR_EL1, RES0, 25, 5)
>     IDREG_FIELD_START(MPIDR_EL1, MT, 24, 1)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -1964,6 +2024,7 @@ IDREG_START(MPIDR_EL1)
> IDREG_END(MPIDR_EL1)
> 
> IDREG_START(MVFR0_EL1)
> +    IDREG_FIELD(MVFR0_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(MVFR0_EL1, FPRound, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -2002,6 +2063,7 @@ IDREG_START(MVFR0_EL1)
> IDREG_END(MVFR0_EL1)
> 
> IDREG_START(MVFR1_EL1)
> +    IDREG_FIELD(MVFR1_EL1, RES0, 32, 32)
>     IDREG_FIELD_START(MVFR1_EL1, SIMDFMAC, 28, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -2040,6 +2102,7 @@ IDREG_START(MVFR1_EL1)
> IDREG_END(MVFR1_EL1)
> 
> IDREG_START(MVFR2_EL1)
> +    IDREG_FIELD(MVFR2_EL1, RES0, 8, 56)
>     IDREG_FIELD_START(MVFR2_EL1, FPMisc, 4, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(1)
> @@ -2059,6 +2122,7 @@ IDREG_START(REVIDR_EL1)
> IDREG_END(REVIDR_EL1)
> 
> IDREG_START(SMIDR_EL1)
> +    IDREG_FIELD(SMIDR_EL1, RES0, 60, 4)
>     IDREG_FIELD_START(SMIDR_EL1, NSMC, 56, 4)
>         IDREG_FIELD_ARCH_VAL(0)
>         IDREG_FIELD_ARCH_VAL(15)
> @@ -2094,6 +2158,7 @@ IDREG_START(SMIDR_EL1)
>         IDREG_FIELD_ARCH_VAL(2)
>         IDREG_FIELD_ARCH_VAL(3)
>     IDREG_FIELD_END(SMIDR_EL1, SH)
> +    IDREG_FIELD(SMIDR_EL1, RES0, 12, 1)
>     IDREG_FIELD(SMIDR_EL1, Affinity, 0, 12)
> IDREG_END(SMIDR_EL1)
> 
> diff --git a/scripts/update-aarch64-cpu-sysreg-properties.py b/scripts/update-aarch64-cpu-sysreg-properties.py
> index e1d6c4afef..9e829fda2e 100644
> --- a/scripts/update-aarch64-cpu-sysreg-properties.py
> +++ b/scripts/update-aarch64-cpu-sysreg-properties.py
> @@ -81,9 +81,13 @@ def collect_fields(item, bit_offset=0):
> 
>     # Normal Field Types
>     leaf_types = ['Fields.Field', 'Fields.ConstantField',
> -                  'Fields.EnumeratedField', 'Fields.Bitfield']
> +                  'Fields.EnumeratedField', 'Fields.Bitfield', 'Fields.Reserved']
>     if _type in leaf_types:
>         field_copy = item.copy()
> +
> +        if _type == 'Fields.Reserved' and not field_copy.get('name'):
> +            field_copy['name'] = item.get('value', 'RES0')
> +
>         if field_copy.get('rangeset'):
>             new_ranges = []
>             for r in field_copy['rangeset']:
> @@ -96,7 +100,7 @@ def collect_fields(item, bit_offset=0):
>         return fields
> 
>     # Traverse the hierarchy for other cases
> -    for key in ['fields', 'values', 'fieldsets']:
> +    for key in ['fields', 'values', 'fieldsets', 'constants']:
>         for nested in item.get(key, []):
>             fields.extend(collect_fields(nested, bit_offset))
> 
> @@ -163,44 +167,95 @@ def generate_sysreg_properties_from_registers_json(id_reg_names, raw_json_path):
> 
>         final_output += f"IDREG_START({reg_name})\n"
> 
> -        unique_fields = {}
> +        fieldset_variants = []
> +
>         for fieldset in register.get('fieldsets', []):
> +            current_fieldset_fields = {}
>             candidates = collect_fields(fieldset)
> +
>             for val in candidates:
> -                name = (val.get('name') or val.get('label', '')).strip()
> -                if not name or "RESERVED" in name.upper():
> +                raw_name = val.get('name') or val.get('label') or val.get('value') or ''
> +                name = raw_name.strip()
> +                if not name:
>                     continue
> +
> +                name_upper = name.upper()
> +
> +                # Check for architectural target states, including UNKNOWN remapping
> +                base_reserved = None
> +                for r_type in ["RES0", "RES1", "RAZ", "RAO", "WI", "UNKNOWN"]:
> +                    if r_type in name_upper:
> +                        base_reserved = "RES0" if r_type == "UNKNOWN" else r_type
> +                        break
> +
> +                is_valid_reserved = base_reserved is not None
> +                if "RESERVED" in name_upper and not is_valid_reserved:
> +                    continue
> +
> +                # Force naming uniformity across padding blocks
> +                if is_valid_reserved:
> +                    name = base_reserved
> +
>                 for r in val.get('rangeset', []):
>                     lsb = int(r.get('start'))
>                     width = r.get('width')
>                     msb = lsb + int(width) - 1
> 
> -                    # Only keep the fields with the highest MSB
> -                    # needed fir CCSIDR_EL1
> -                    if name not in unique_fields or msb > unique_fields[name]['msb']:
> -                        # extract enum values if any
> +                    if is_valid_reserved:
> +                        unique_key = f"{name}_{lsb}"
> +                    else:
> +                        unique_key = name
> +
> +                    if unique_key not in current_fieldset_fields or \
> +                       msb > current_fieldset_fields[unique_key]['msb']:
>                         enums = extract_field_enums(val)
> -                        unique_fields[name] = {'lsb': lsb, 'msb': msb, 'width': width, 'enums': enums}
> +                        current_fieldset_fields[unique_key] = {
> +                            'raw_name': name,
> +                            'lsb': lsb,
> +                            'msb': msb,
> +                            'width': width,
> +                            'enums': enums
> +                        }
> +
> +            if current_fieldset_fields:
> +                fieldset_variants.append(current_fieldset_fields)
> +
> +        best_fieldset = {}
> +        max_total_width = -1
> +
> +        for variant in fieldset_variants:
> +            total_width = sum(f['width'] for f in variant.values())
> +            # prioritize layout variants with the highest MSB coverage
> +            max_msb = max(f['msb'] for f in variant.values()) if variant else 0
> +
> +            # Combine width and max_msb into a fitness score tuple
> +            if (total_width, max_msb) > (max_total_width, max_total_width):
> +                max_total_width = total_width
> +                best_fieldset = variant
> +
> +        unique_fields = best_fieldset
> 
>         # Sort decreasing lsbs
>         sorted_fields = sorted(unique_fields.items(),
>                                key=lambda x: x[1]['lsb'], reverse=True)
> 
> -        for name, bits in sorted_fields:
> +        for unique_key, bits in sorted_fields:
>             enums_list = bits.get('enums', [])
> 
> +            clean_name = bits.get('raw_name', unique_key)
> +
>             if enums_list:
>                line = (f"    IDREG_FIELD_START({reg_name}, "
> -                       f"{name}, {bits['lsb']}, {bits['width']})\n")
> +                       f"{clean_name}, {bits['lsb']}, {bits['width']})\n")
>             else:
>                line = (f"    IDREG_FIELD({reg_name}, "
> -                       f"{name}, {bits['lsb']}, {bits['width']})\n")
> +                       f"{clean_name}, {bits['lsb']}, {bits['width']})\n")
>             final_output += line
>             # add the enum value definition if any
>             for enum_item in enums_list:
>                 final_output += (f"        IDREG_FIELD_ARCH_VAL({enum_item['value']})\n")
>             if enums_list:
> -               line = (f"    IDREG_FIELD_END({reg_name}, {name})\n")
> +               line = (f"    IDREG_FIELD_END({reg_name}, {clean_name})\n")
>                final_output += line
> 
>         final_output += f"IDREG_END({reg_name})\n"
> -- 
> 2.53.0
>