Re: [PATCH v2 2/5] target/arm: Allow setting 'pmu' only for host and max

[Peter Maydell]

On Tue, 16 Jul 2024 at 09:28, Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
>
> Setting 'pmu' does not make sense for CPU types emulating physical
> CPUs.
>
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>  target/arm/cpu.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/target/arm/cpu.c b/target/arm/cpu.c
> index 14d4eca12740..8c180c679ce2 100644
> --- a/target/arm/cpu.c
> +++ b/target/arm/cpu.c
> @@ -1594,6 +1594,13 @@ static bool arm_get_pmu(Object *obj, Error **errp)
>  static void arm_set_pmu(Object *obj, bool value, Error **errp)
>  {
>      ARMCPU *cpu = ARM_CPU(obj);
> +    const char *typename = object_get_typename(obj);
> +
> +    if (strcmp(typename, ARM_CPU_TYPE_NAME("host")) &&
> +        strcmp(typename, ARM_CPU_TYPE_NAME("max"))) {
> +        error_setg(errp, "Setting 'pmu' is only supported by host and max");
> +        return;
> +    }

This doesn't seem right. In general where we provide a
user-facing -cpu foo,bar=off option we allow the user to
use it to disable the bar feature on named CPUs too.
So you can use it to say "give me a neoverse-v1 without the PMU".

thanks
-- PMM