Re: [PATCH RFC v3 21/21] cpumask: Add enabled cpumask for present CPUs that can be brought online

[Thomas Gleixner <tglx@xxxxxxxxxxxxx>]

On Wed, Dec 13 2023 at 12:50, Russell King (Oracle) wrote:
> From: James Morse <james.morse@xxxxxxx>
>
> The 'offline' file in sysfs shows all offline CPUs, including those
> that aren't present. User-space is expected to remove not-present CPUs
> from this list to learn which CPUs could be brought online.
>
> CPUs can be present but not-enabled. These CPUs can't be brought online
> until the firmware policy changes, which comes with an ACPI notification
> that will register the CPUs.
>
> With only the offline and present files, user-space is unable to
> determine which CPUs it can try to bring online. Add a new CPU mask
> that shows this based on all the registered CPUs.
>
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Tested-by: Miguel Luis <miguel.luis@xxxxxxxxxx>
> Tested-by: Vishnu Pajjuri <vishnu@xxxxxxxxxxxxxxxxxxxxxx>
> Tested-by: Jianyong Wu <jianyong.wu@xxxxxxx>

Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>