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SubjectRe: CPU hyperthreading turned on after soft power-cycle
On 11/17/2011 9:32 PM, John Stultz wrote:
> On Wed, 2011-11-16 at 23:49 +0100, Clarinet wrote:
>> Hi all,
>>
>>>> Result of bisecting: v2.6.38-rc1 exhibits the problem. v2.6.37 and
>>>> many of the topic branches merged in the 2.6.38 merge window work ok.
>>>> Some other topic branches do not boot at all.
>>>>
>>>> Jiri: if you have gitk installed, then "git bisect visualize" can help
>>>> get a sense of what's in the middle of the regression range.
>>>> "gitk --bisect --first-parent v2.6.37..v2.6.38-rc1" might be a good way
>>>> to find mainline commits to test before finding a topic branch to delve
>>>> into.
>>>
>>> I have been able to narrow the interval manually a little bit from the
>>> "top" (the bad side) and I will go on from the bottom now. However,
>>> there seems to be a large area where kernels are unbootable for me -
>>> they mostly stop when init is called and I do not know why.
>>
>> Finally! After another 50+ compilations a have it! It took some time as
>> first I had to find a reason why some revisions did not boot (almost 2/3
>> were unbootable and the first bad commit was among them). Having this
>> solved I have been able to bisect without "skipping". The result is
>> surprising (at least for me) - believe it or not, the first bad commit
>> is 6610e089 "RTC: Rework RTC code to use timerqueue for events" from
>> John Stultz (I am sending him a copy of this message).
>>
>> I would never expect this would be a problem, but my understanding of
>> this commit is very limited, so I am certainly missing the point.
>> However, I have tried to compile 2.6.38 (which was "bad") with "Real
>> Time Clock" configuration option turned off and it behaves "normally"
>> then (= is "good").
>
> Huh. That's *very* odd. Is your system doing anything in-particular
> with the RTC? I don't have a clue right off, so probably the next step

Yes, it is very odd. The system does not do anything special with RTC.
It is a diskless computational workstation.

> is doing a bit of instrumentation to try to figure out where exactly we
> trigger the behavior. Could you checkout commit 6610e089 and apply the
> patch below to see if we can't narrow it down?

With the patch applied the system does not show the strange behavior (=
is "good").

> Could you also send your .config to me?

Sure. It is attached. I have found that if I turn CONFIG_RTC_DRV_CMOS
off, the system behaves normally (= is "good") too.

Thank you.

Jiri Polach

> thanks
> -john
>
> diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
> index 5856167..d049344 100644
> --- a/drivers/rtc/rtc-cmos.c
> +++ b/drivers/rtc/rtc-cmos.c
> @@ -497,13 +497,13 @@ static int cmos_procfs(struct device *dev, struct seq_file *seq)
> static const struct rtc_class_ops cmos_rtc_ops = {
> .read_time = cmos_read_time,
> .set_time = cmos_set_time,
> - .read_alarm = cmos_read_alarm,
> - .set_alarm = cmos_set_alarm,
> - .proc = cmos_procfs,
> - .irq_set_freq = cmos_irq_set_freq,
> - .irq_set_state = cmos_irq_set_state,
> - .alarm_irq_enable = cmos_alarm_irq_enable,
> - .update_irq_enable = cmos_update_irq_enable,
> +// .read_alarm = cmos_read_alarm,
> +// .set_alarm = cmos_set_alarm,
> +// .proc = cmos_procfs,
> +// .irq_set_freq = cmos_irq_set_freq,
> +// .irq_set_state = cmos_irq_set_state,
> +// .alarm_irq_enable = cmos_alarm_irq_enable,
> +// .update_irq_enable = cmos_update_irq_enable,
> };
>
> /*----------------------------------------------------------------*/


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