Re: [PATCH RFC v3 05/21] ACPI: Rename ACPI_HOTPLUG_CPU to include 'present'

["Rafael J. Wysocki" <rafael@xxxxxxxxxx>]

On Wed, Dec 13, 2023 at 1:49 PM Russell King <rmk+kernel@xxxxxxxxxxxxxxx> wrote:
>
> From: James Morse <james.morse@xxxxxxx>
>
> The code behind ACPI_HOTPLUG_CPU allows a not-present CPU to become
> present.

Right.

> This isn't the only use of HOTPLUG_CPU. On arm64 and riscv
> CPUs can be taken offline as a power saving measure.

But still there is the case in which a non-present CPU can become
present, isn't it there?

> On arm64 an offline CPU may be disabled by firmware, preventing it from
> being brought back online, but it remains present throughout.
>
> Adding code to prevent user-space trying to online these disabled CPUs
> needs some additional terminology.
>
> Rename the Kconfig symbol CONFIG_ACPI_HOTPLUG_PRESENT_CPU to reflect
> that it makes possible CPUs present.

Honestly, I don't think that this change is necessary or even useful.