From: Tobias Röhmel <quic_trohmel@quicinc.com>

This register is used by the ARM Cortex-R52.

Signed-off-by: Tobias Röhmel <quic_trohmel@quicinc.com>
---
 target/arm/helper.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 6457e6301c..bdf1df37d5 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -8201,6 +8201,15 @@ void register_cp_regs_for_features(ARMCPU *cpu)
               .accessfn = access_aa64_tid1,
               .type = ARM_CP_CONST, .resetvalue = cpu->revidr },
         };
+        ARMCPRegInfo id_v8r_midr_cp_reginfo[] = {
+            { .name = "MIDR",
+              .cp = 15, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = CP_ANY,
+              .access = PL1_R, .resetvalue = cpu->midr,
+              .writefn = arm_cp_write_ignore, .raw_writefn = raw_write,
+              .readfn = midr_read,
+              .fieldoffset = offsetof(CPUARMState, cp15.c0_cpuid),
+              .type = ARM_CP_OVERRIDE },
+        };
         ARMCPRegInfo id_cp_reginfo[] = {
             /* These are common to v8 and pre-v8 */
             { .name = "CTR",
@@ -8264,7 +8273,9 @@ void register_cp_regs_for_features(ARMCPU *cpu)
             id_mpuir_reginfo.access = PL1_RW;
             id_tlbtr_reginfo.access = PL1_RW;
         }
-        if (arm_feature(env, ARM_FEATURE_V8)) {
+        if (arm_feature(env, ARM_FEATURE_V8_R)) {
+            define_arm_cp_regs(cpu, id_v8r_midr_cp_reginfo);
+        } else if (arm_feature(env, ARM_FEATURE_V8)) {
             define_arm_cp_regs(cpu, id_v8_midr_cp_reginfo);
         } else {
             define_arm_cp_regs(cpu, id_pre_v8_midr_cp_reginfo);
-- 
2.25.1

On Thu, 14 Jul 2022 at 15:54, Tobias Roehmel <quic_trohmel@quicinc.com> wrote:
>
> From: Tobias Röhmel <quic_trohmel@quicinc.com>
>
> This register is used by the ARM Cortex-R52.
>
> Signed-off-by: Tobias Röhmel <quic_trohmel@quicinc.com>
> ---
>  target/arm/helper.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index 6457e6301c..bdf1df37d5 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -8201,6 +8201,15 @@ void register_cp_regs_for_features(ARMCPU *cpu)
>                .accessfn = access_aa64_tid1,
>                .type = ARM_CP_CONST, .resetvalue = cpu->revidr },
>          };
> +        ARMCPRegInfo id_v8r_midr_cp_reginfo[] = {
> +            { .name = "MIDR",
> +              .cp = 15, .crn = 0, .crm = 0, .opc1 = 0, .opc2 = CP_ANY,
> +              .access = PL1_R, .resetvalue = cpu->midr,
> +              .writefn = arm_cp_write_ignore, .raw_writefn = raw_write,
> +              .readfn = midr_read,
> +              .fieldoffset = offsetof(CPUARMState, cp15.c0_cpuid),
> +              .type = ARM_CP_OVERRIDE },

Why do we need this specially for v8R ? The v8R Supplement lists
MIDR and REVIDR as "unchanged" between v8A and v8R, so the
existing id_v8_midr_cp_reginfo[] should be fine.

thanks
-- PMM