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

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Message-ID: <56530769.4030403@arm.com>
Date:	Mon, 23 Nov 2015 12:32:41 +0000
From:	Vladimir Murzin <vladimir.murzin@....com>
To:	Nikita Yushchenko <nyushchenko@....rtsoft.ru>
CC:	Russell King - ARM Linux <linux@....linux.org.uk>,
	kuznetsovg@....rtsoft.ru, Ian Campbell <ian.campbell@...rix.com>,
	Mason <slash.tmp@...e.fr>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Will Deacon <will.deacon@....com>,
	Paul Kocialkowski <contact@...lk.fr>,
	linux-kernel@...r.kernel.org,
	Masahiro Yamada <yamada.m@...panasonic.com>,
	Pavel Machek <pavel@....cz>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC/PATCH] arm: do not skip SMP init calls on SMP_ON_UP case

On 23/11/15 12:06, Nikita Yushchenko wrote:
> 23.11.2015 15:03, Russell King - ARM Linux пишет:
>> On Mon, Nov 23, 2015 at 02:59:06PM +0300, nyushchenko@....rtsoft.ru wrote:
>>> From: Nikita Yushchenko <nyushchenko@....rtsoft.ru>
>>>
>>> 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.
> 
> Kernel that is running here still tries to init CPU 1 for some reason.

I *guess* cpus node [1] in your dts has more than one cpu entry, could
you check please?

[1] Documentation/devicetree/bindings/arm/cpus.txt

Vladimir

> 
> Will try to check mainline (although not sure if that will be possible
> on available custom hardware)
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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