Re: [PATCH 5/8] arm64: Create cache sysfs directory without ACPI PPTT for hardware prefetch control

[Sudeep Holla]

On Tue, Jan 25, 2022 at 04:14:11PM +0900, Kohei Tarumizu wrote:
> This patch will create a cache sysfs directory without ACPI PPTT if
> the CONFIG_HWPF_CONTROL is true.
> 
> Hardware prefetch control driver need cache sysfs directory and cache
> level/type information. In ARM processor, these information can be
> obtained from the register even without PPTT. Therefore, we set the
> cpu_map_populated to true to create cache sysfs directory if the
> machine doesn't have PPTT.

I am assuming this is ACPI enabled system.

This looks bit hacky in my opinion. Before I explore better way of adding it,
I would like to check if you have explored ways to add PPTT reading these
registers from UEFI/EDK2 as PPTT has other topology information which you will
need anyways. That would simplify handling of these cacheinfo sysfs in the
kernel. Let me know what are your thoughts ?

-- 
Regards,
Sudeep