[PATCH v9 19/19] cpumask: Add enabled cpumask for present CPUs that can be brought online

[Gavin Shan]

On 5/1/24 00:24, Jonathan Cameron wrote:
> From: James Morse <james.morse at arm.com>
> 
> 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 at arm.com>
> Tested-by: Miguel Luis <miguel.luis at oracle.com>
> Tested-by: Vishnu Pajjuri <vishnu at os.amperecomputing.com>
> Tested-by: Jianyong Wu <jianyong.wu at arm.com>
> Acked-by: Thomas Gleixner <tglx at linutronix.de>
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
> Signed-off-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>
> 
> ---
> v9: No change
> ---
>   .../ABI/testing/sysfs-devices-system-cpu      |  6 +++++
>   drivers/base/cpu.c                            | 10 ++++++++
>   include/linux/cpumask.h                       | 25 +++++++++++++++++++
>   kernel/cpu.c                                  |  3 +++
>   4 files changed, 44 insertions(+)
> 

Reviewed-by: Gavin Shan <gshan at redhat.com>