Re: [RFC/PATCH] arm: do not skip SMP init calls on SMP_ON_UP case

From: Russell King - ARM Linux
Date: Mon Nov 23 2015 - 07:04:13 EST

On Mon, Nov 23, 2015 at 02:59:06PM +0300, nyushchenko@xxxxxxxxxxxxx wrote:
> From: Nikita Yushchenko <nyushchenko@xxxxxxxxxxxxx>
> While running an imx6s boasrd, I got following message in boot log:
> [ 0.032414] CPU1: failed to boot: -38
> This looked strange: imx6s is singe-core and kernel perfectly knows
> that. However, for some reason it tries to initialize CPU 1?
> I found this to be caused by
> - CONFIG_SMP_ON_UP successfully detects that system is single core,
> - this causes is_smp() to return false,
> - this causes setup_arch() to skip smp_init_cpus() call,
> - this skips board-specific code that sets cpu_possible mask.

Right, so you should end up with the possible and present masks
containing just one CPU, which should prevent the kernel trying to
bring any secondary CPUs online.

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