Re: [PATCH 03/16] target/arm: Update qemu-system-arm -cpu max to cortex-a57

[Peter Maydell]

On Sat, 9 Apr 2022 at 01:11, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> Instead of starting with cortex-a15 and adding v8 features to
> a v7 cpu, begin with a v8 cpu stripped of its aarch64 features.
> This fixes the long-standing to-do where we only enabled v8
> features for user-only.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/cpu_tcg.c | 134 ++++++++++++++++++++++++++-----------------
>  1 file changed, 80 insertions(+), 54 deletions(-)
>
> diff --git a/target/arm/cpu_tcg.c b/target/arm/cpu_tcg.c
> index 13d0e9b195..43ac3e27fa 100644
> --- a/target/arm/cpu_tcg.c
> +++ b/target/arm/cpu_tcg.c
> @@ -938,71 +938,97 @@ static void arm_v7m_class_init(ObjectClass *oc, void 
> *data)
>  static void arm_max_initfn(Object *obj)
>  {
>      ARMCPU *cpu = ARM_CPU(obj);
> +    uint32_t t;
>
> -    cortex_a15_initfn(obj);
> +    /* aarch64_a57_initfn, advertising none of the aarch64 features */
> +    cpu->dtb_compatible = "arm,cortex-a57";
> +    set_feature(&cpu->env, ARM_FEATURE_V8);
> +    set_feature(&cpu->env, ARM_FEATURE_NEON);
> +    set_feature(&cpu->env, ARM_FEATURE_GENERIC_TIMER);
> +    set_feature(&cpu->env, ARM_FEATURE_CBAR_RO);
> +    set_feature(&cpu->env, ARM_FEATURE_EL2);
> +    set_feature(&cpu->env, ARM_FEATURE_EL3);
> +    set_feature(&cpu->env, ARM_FEATURE_PMU);
> +    cpu->midr = 0x411fd070;

If we're going to claim in the MIDR that we're an A57 then we
should provide the A57's impdef sysregs, at least those of
them that are visible to AArch32. This may otherwise cause
problems if the guest OS tries to write to one of them as
part of some errata workaround.

thanks
-- PMM