Re: [PATCH RFC v1 1/8] cpu/hotplug: Allow architecture-specific primary CPU bringup

[Borislav Petkov]

On Sat, Sep 12, 2026 at 12:08:07AM +0000, Chang S. Bae wrote:
> Parallel CPU bringup currently proceeds in two phases: first for the SMT
> primary threads and then second for the remaining secondary threads. This
> ordering avoids race conditions, specifically for x86 microcode loading.
> 
> Upcoming x86 changes expand the microcode loading scope beyond a single
> core to package scope or even system-wide updates. Introduce architecture
> hooks that allow customizing which CPUs participate in the first phase:
> 
>  * arch_cpuhp_primary_aware() - indicates whether the architecture
>    provides a custom primary CPU selection scheme, or not.
> 
>  * arch_cpuhp_get_primary_cpus() - returns a CPU mask for the first
>    bringup iteration.

Why are there two?

Why are there even accessors at all when you can simply use
cpu_primary_thread_mask whereever you need it and drop all that gunk here and
in the next patch?

-- 
Regards/Gruss,
    Boris.

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