Re: [RFC PATCH] target/arm: update the cortex-a15 MIDR to latest rev

["Arnd Bergmann" <arnd@arndb.de>]

On Tue, Sep 6, 2022, at 7:22 PM, Alex Bennée wrote:
>
> index 3099b38e32..59d5278868 100644
> --- a/target/arm/cpu_tcg.c
> +++ b/target/arm/cpu_tcg.c
> @@ -588,7 +588,9 @@ static void cortex_a15_initfn(Object *obj)
>      set_feature(&cpu->env, ARM_FEATURE_EL3);
>      set_feature(&cpu->env, ARM_FEATURE_PMU);
>      cpu->kvm_target = QEMU_KVM_ARM_TARGET_CORTEX_A15;
> -    cpu->midr = 0x412fc0f1;
> +    /* r4p0 cpu, not requiring expensive tlb flush errata */
> +    cpu->midr = 0x414fc0f0;
> +    cpu->revidr = 0x200;
>      cpu->reset_fpsid = 0x410430f0;
>      cpu->isar.mvfr0 = 0x10110222;
>      cpu->isar.mvfr1 = 0x11111111;

This will work correctly with Linux, but after I checked the
Cortex-A15 MPCore r2/r3/r4 Software Developers Errata Notice again,
I think that setting revidr here is not fully correct:

With an r3p3 CPU, bit 9 of revidr (0x200) indicates that no
workaround is necessary, but with r4p0 and higher, this bit
is marked as reserved and both the Documentation and the
Linux source code assume the hardware works correctly.

So I think this should either be 0x413fc0f3/0x200
or 0x414fc0f0/0.

     Arnd