Re: [PATCH V2] irqchip/loongson-eiointc: Use early_cpu_to_node() instead of cpu_to_node()

[Huacai Chen]

Hi, Thomas,

On Sun, Jun 23, 2024 at 5:21 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>
> Huacai!
>
> On Sat, Jun 22 2024 at 19:23, Huacai Chen wrote:
> > On Sat, Jun 22, 2024 at 6:17 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> >> That does not make sense because it's exactly the same situation when
> >> you compile a kernel with NR_CPU=8 and boot it on a system with 16
> >> CPUs. Then early_cpu_to_node() does not give you anything either.
> >>
> >> So what's the technical problem you are trying to solve?
> >
> > Frankly, there are some drawbacks on our hardware. On a dual-bridge
> > machine, there are two eiointc instances. Even if nr_cpus limits the
> > "possible" CPUs, we still hope the eiointc driver can initialize
> > correctly, otherwise the machine cannot boot.
>
> Hope does not help with technical limitations :)
>
> So if CONFIG_NR_CPUS is not big enough to map the second node, then the
> machine can't boot.
>
> If nr_cpus limits it then early_cpu_to_node() because that mapping is
> only limited by CONFIG_NR_CPUS.
Yes, if NR_CPUS is not big enough, then we have no solution.

>
> Right?
>
> If so, then please explain all of this properly in the change log.
OK, I will explain in detail.

Huacai

>
> Thanks,
>
>         tglx
>
>