linux-kernel - Re: CPU hyperthreading turned on after soft power-cycle

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Date:	Mon, 21 Nov 2011 22:31:44 +0100
From:	Jiri Polach <clarinet@...as.cz>
To:	John Stultz <john.stultz@...aro.org>
CC:	Jiri Polach <clarinet@...as.cz>, 647095@...s.debian.org,
	Jonathan Nieder <jrnieder@...il.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	LKML <linux-kernel@...r.kernel.org>, x86@...nel.org
Subject: Re: CPU hyperthreading turned on after soft power-cycle


>>> Yea. My rough guess is that the BIOS is somehow sensitive to how the
>>> CMOS RTC is touched.
>>>
>>> Does disabling CONFIG_HPET_EMULATE_RTC change the behavior?
>>
>> But how do I do it? :-)
>>
>> I have not found a way to disable it in "menuconfig". If I comment it
>> out manually in .config, it is automatically set back to "y" as soon as
>> compilation starts ...
>
> Good point. I forgot on x86_64 you can't disable HPET_TIMER.
>
> Could you then use the following patch (and run make oldconfig before
> building).
>
> thanks
> -john
>
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index cb9a104..77b5273 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -640,7 +640,7 @@ config HPET_TIMER
>   	  Choose N to continue using the legacy 8254 timer.
>
>   config HPET_EMULATE_RTC
> -	def_bool y
> +	def_bool n
>   	depends on HPET_TIMER&&  (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
>
>   config APB_TIMER

Applying this patch does not change anything, this kernel is "bad".

Jiri Polach

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