Re: [Qemu-devel] [PATCH 10/20] nvic: Add NS alias SCS region

[Richard Henderson <richard.henderson@linaro.org>]

On 08/22/2017 08:08 AM, Peter Maydell wrote:
> +    regionlen = arm_feature(&s->cpu->env, ARM_FEATURE_V8) ? 0x21000 : 0x1000;
> +    memory_region_init(&s->container, OBJECT(s), "nvic", regionlen);
>      /* The system register region goes at the bottom of the priority
>       * stack as it covers the whole page.
>       */
> @@ -1185,6 +1242,13 @@ static void armv7m_nvic_realize(DeviceState *dev, Error **errp)
>                                          sysbus_mmio_get_region(systick_sbd, 0),
>                                          1);
>  
> +    if (arm_feature(&s->cpu->env, ARM_FEATURE_V8)) {
> +        memory_region_init_io(&s->sysreg_ns_mem, OBJECT(s),
> +                              &nvic_sysreg_ns_ops, s,
> +                              "nvic_sysregs_ns", 0x1000);
> +        memory_region_add_subregion(&s->container, 0x20000, &s->sysreg_ns_mem);

There's a whole in between the two regions, which you are leaving mapped.  Why
create a sub-region instead of two separate top-level regions for which you can
leave the whole unmapped?


r~