[RFC/PATCH] arm: do not skip SMP init calls on SMP_ON_UP case
Nikita Yushchenko
nyushchenko at dev.rtsoft.ru
Mon Nov 23 04:47:34 PST 2015
>>>>> 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?
>
> Indeed looks so:
>
> # ls /proc/device-tree/cpus
> #address-cells #size-cells cpu at 0 cpu at 1 name
>
> But my custom device tree just includes imx6dl.dtsi
>
> So it is imx6dl.dtsi in linux-imx tree broken?..
Just booted mainline... unline linux-imx, it does not try to init cpu1.
However, imx6dl.dtsi from mainline also has both cpu at 0 and cpu at 1
So missing piece in linux-imx is elsewhere :(
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