[PATCH] arm: allow single CPU configuration by adjusting NR_CPUS range and defaults

[Suchit K]

On Thu, 24 Jul 2025 at 23:16, Russell King (Oracle)
<linux at armlinux.org.uk> wrote:
>
> On Thu, Jul 24, 2025 at 10:56:03PM +0530, Suchit Karunakaran wrote:
> > Previously, the NR_CPUS config for ARM required a minimum of 2 CPUs.
> > This patch changes the minimum NR_CPUS to 1 when SMP is not enabled,
> > sets range to exactly 1 if !SMP, allowing only a single CPU setting and
> > adds conditional defaults:
> >     - default to 1 if SMP is disabled (uniprocessor)
> >     - default to 4 if SMP is enabled (multiprocessor)
> >
> > Signed-off-by: Suchit Karunakaran <suchitkarunakaran at gmail.com>
>
> This hasn't been tested. NR_CPUS depends on SMP, so if SMP is not
> enabled, then NR_CPUS doesn't exist in the configuration. Therefore,
> providing a default for !SMP is meaningless.
>

Oops, I think I misunderstood the intent of commit
278d1ed65e25d80af7c3a112d707b3f70516ddb4(cpumask: make CONFIG_NR_CPUS
always valid). And sorry for not testing it, I wasn't exactly sure how
to test it. Could you please point out the issues so I can fix them
properly? I appreciate your patience. I’m still learning my way around
kernel development and trying to improve. Thanks!