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

Russell King (Oracle) linux at armlinux.org.uk
Thu Jul 24 10:45:56 PDT 2025


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. 

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